Frequently Asked Questions

Welcome to the Frequently Asked Questions

 

Here you can browse FAQs by category or submit a question to our team.

 

Popular FAQs

SENSORLESS BRUSHLESS MOTOR CONTROL USING BACK EMF

Back EMF stands for Back Electromotive Force. In simple terms, the Back EMF is an electromotive force which occurs as the brushless motor turns. This acts like a generator creating electromotive resistance within the motor. Critically, motor controllers such as the ZDBL15 can measure the back-EMF generated. As the back-EMF frequency is proportional to the motor speed this enables us to determine the exact speed of the motor.

An intelligent motor controller such as the ZDBL15 brushless ESC can then read this force and use it to measure the actual speed of the motor. The ZDBL15 can then maintain this speed using Back EMF as a reference to measure and adjust the speed. It is this method which enables a sensorless brushless motor controller such as the ZDBL15 to be able to deliver constant speed under a variable load.

ARE THERE DISADVANTAGES TO USING BACK EMF IN SENSORLESS BRUSHLESS MOTOR CONTROLLERS?

No back EMF is generated when the motor is stationary, meaning that start up is difficult. As such, the motor can take a small amount of time to settle and run efficiently. A second disadvantage is that at low speeds the back EMF is weak and therefore quite difficult to measure accurately. This can result in inefficient operation in the form of jumpiness. Stepper motors are perfect if your application needs reliable operation at low speeds.

WHAT ARE THE MAIN ADVANTAGES OF USING BACK EMF IN THE CONTROL OF SENSORLESS BRUSHLESS MOTORS?

Using back-EMF as a means of maintaining and accurately controlling motor speed in brushless DC motors is a much lower cost solution than brushless DC motors with sensors and is also much more reliable as there are less component parts which can go wrong. A sensored brushless DC motor and a sensored motor controller will become completely useless if the sensors fail. However, a sensorless brushless motor controller will be able to function reliably without risk of sensor failure.

To browse the range of ZDBL Series Brushless Motor Controllers which optimise back-EMF to deliver exceptionally accurate brushless motor control please CLICK HERE

If you have any additional questions please CONTACT US to discuss. 

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THE QUICK ANSWER…

A typical stepper motor has 200 steps to complete a 360 degree complete rotation (hence 1.8 degree stepper motors such as the ZDSPN1718). Full step mode would therefore enable a total of 200 positions in the 360 degree circle.

Microstepping is where a stepper motor controller is driven in a way that enables it to divide these steps up into further steps (or microsteps). These start at half steps but can go as high as 1/128 microsteps with the ZD Series of Stepper Motor Controllers.

This means that each of the 200 individual steps that are built into the motor have now been divided up into 128 separate steps by the controller. This enables the combined motor and controller to stop at anyone of 25600 possible positions around the 360 degree complete revolution.

MICROSTEPPING DOES NOT JUST DELIVER IMPROVED POSITIONAL ACCURACY…

When we first explain microstepping to some of our customers they assume that the main advantage of additional microstepping is that it delivers much greater positional accuracy for applications such as robotics or highly accurate dosing.

However, there are a number of other additional benefits which can be derived from microstepping;

  • Quieter operation – microstepping smoothes out the drive signal going into a stepper motor by replacing the square wave step-step-step with a more smoothed out (finer resolution) curve. It is not a sinusoidal drive but the obvious analogy would be between very low resolution digital audio and higher resolution digital audio. By increasing the
  • More efficient operation – by smoothing the drive signal out it is possible to reduce energy consumption. In part this is the result of

MICROSTEPPING IS FASTER

Don’t forget that, because microstepping is more energy efficient and uses smaller, more frequent pulses, it allows stepper motors to reach slightly higher speeds than they normally would.

WHEN TO THINK ABOUT USING MICROSTEPPING

Based on the key points identified above it can be seen that the most appropriate applications for microstepping are those which either require exceptional positioning accuracy or those where energy efficiency and noise are important. In the majority of cases we would normally suggest using microstepping of some kind as it can usually lead to general improvements such as quieter and smoother operation but depending on the torque requirements of your project or application it is always best to discuss with one of our engineers first.

CONCLUSION

Using microstepping offers a large range of potential benefits depending on the nature of your application. From increased smoothness and positional accuracy to greater energy efficiency and speed. Why not browse our range of ZD Series Stepper Motor Drivers and see what they could do for your application today.

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CHOOSE THE RIGHT MOTOR FOR YOUR APPLICATION

The first port of call is to understand what torque and speed you require. This will immediately give you a clear idea of what is possible. As a quick example, most stepper motors do not exceed 1000rpm. Therefore if you need to go above this you will need a brushed DC or brushless DC motor. Equally if you require positional accuracy or easy monitoring of number of revolutions for an application such as dosing or pumps, then a stepper will perform much better.

SELECTING THE MOST IMPORTANT FEATURES AND PERFORMANCE CRITERIA YOU REQUIRE IN A MOTOR

The second port of call is to understand what you require from the motor for it to work successfully in your application and the extent to which each type of motor might be able to achieve this? For example, ask yourself the following questions;

1. Do you need high positional or speed accuracy?

2. Is energy efficiency and lifespan a high priority?

3. Do you need to maintain a constant torque or constant speed?

If you require high positional accuracy stepper motors are by far the best choice as they can be micro-controlled to rotate 1/100th of a degree (or more) if required. If energy efficiency are more important to your project than positional accuracy then it is likely that a brushless DC motor will be best as these offer much greater lifespan than brushed DC motors and are more efficient than stepper motors. Once you have prioritised the most important characteristics required from the motor you can then make a decision. Below is a simple table with the pros and cons of each type of motor to help you further.

CONCLUSION – PRIORITISE THE KEY FEATURES THAT ARE MOST IMPORTANT TO YOU

Fundamentally there are applications where one type of motor will be the obvious choice – for example a peristaltic pump application requiring high resolution dosing. However, on the reverse side of this there are a large number of applications where it may be possible to use any number of different types of motors. In such applications it is important to understand the pros and cons of each type of motor and how they relate to the key priorities of your specific motor control project or application

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Browse all FAQs

We offer comprehensive motor control technical support of all our product range, including bespoke design work. We do this over the phone, via email, via online chat and forums and in person on site.

OVER THE PHONE

Our UK based engineers are available on the phone to talk through any problems that you may have. Simply call +44 (0) 333 123 7130 and choose the relevant option for your enquiry.

ON SITE SUPPORT TO HELP GET YOUR MOTOR CONTROL PROJECT MOVING?

We offer fully insured on site technical support from qualified engineers. You can find out more information by clicking HERE

ROLLING TECHNICAL SUPPORT AS A MAJOR PART OF YOUR ORGANISATION

For customers who are looking at using any Zikodrive Stepper Motor Controllers or BLDC Motor Drivers as a key component of a product that may require modification or setup for a range of different customers we offer ONGOING TECHNICAL SUPPORT PACKAGES where we effectively operate as an employee of your organisation. This is proving to be one of our most popular services. If this is something that interest you, please get in touch with us to discuss.

This method works as follows. If you get a technical enquiry from one of your customers and need assistance you can have a direct link to one of our engineers who will answer your question and get you moving again either by email or over the phone if preferred. If you have a customer who needs on site technical support to setup or repair a system we can also do this. Depending on the likely amount of use that you will incur from this service we can offer this as a fixed price arrangement (effectively a retainer) or we can simply charge as you go.

Category: Commercial
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Of course!

For more information on this question and the range of technical support we offer please visit either the SUPPORT section of the website. If you have any other questions about help with a specific project or application then please feel free to CONTACT US.

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The costs of modifying an existing ‘off the shelf’ stepper motor controller or BLDC Motor Driver depend largely on the extent of the modifications that you require. As a basic guide we would split this cost up into the tooling costs involved in making changes to the board and then the design and testing time required to ensure the motor controller meets the exact specifications you require.

TOOLING COSTS

Any modifications that are made will require custom made tooling to be made in order to then deliver them as full production units. Typically the cost of this is £800.

DEVELOPMENT TIME

The development time required to deliver your modifications obviously depends on the complexity of what you require and how different it is to the standard version of the stepper motor controller or Brushless ESC. To provide a basic idea our charges for this are £40/hr for design and testing time and £80/hr for any on site work that may be required. If it is as simple as adding one or two onboard features to an existing stepper motor controller or BLDC Motor Driver then this may only require 1-2 days work to get done. For more complex changes it could take several days or a few weeks. Please note that we are more than happy to provide fixed price quotes for changes if preferred.

OPTIONAL BREAK-OUT OR PLUGIN BOARDS?

For some applications it may be more cost effective to use an existing stepper motor controller or brushless ESC and purchase a custom made plugin board to deliver the features you require. This is generally the case where modifications are much more about physical user interfaces such as additional buttons, pots or displays and is often also true where additional communications types or similar are required. If you are anticipating relatively high volume (200+ a year) then it will probably be lower cost to get a custom made board. For anything below this, adding a plugin board could save you money.

CONCLUSION

If this is something that you are considering then the first port of call is to talk to one of our engineers about your requirements. They will advise on the most cost effective method for achieving your project requirements and we can then take the project from there.

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Yes, purchasing full intellectual property is an option. It is worth remembering that purchasing the IP for a stepper motor controller or brushless Esc (or indeed whatever project you may have in mind) is more expensive but it is certainly possible. Bear in mind that if the controller is already commercially available then we will not be in a position to sell the intellectual property at this stage. This is a more common approach with bespoke design projects rather than controller modifications.

To discuss this in detail we would suggest that you CONTACT US as this type of issue is best dealt with on a case by case basis. You can also read more information about our bespoke design projects, our OEM modification and customisation service and some case studies of work we have previously carried out.

Category: Commercial
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One of the main advantages of using Zikodrive Motor Controllers over many similar manufacturers is that our motor controllers are fully programmable and that we can help you out with the programming.

QUICK SETUP OF THE BASIC PARAMETERS OF YOUR STEPPER MOTOR CONTROLLER OR BLDC MOTOR DRIVER

At its most basic, we can set up a stepper motor controller with basic settings such as current and speed. This is particularly useful for those customers who require a motor driver that runs in a set speed range or who just need a motor driver which will accurately and repeatedly run at a set speed. Our aim here is to simplify things as much as possible for our customers by setting up the basic parameters on the stepper motor controller or brushless motor driver before you even use them. 

STEPPER MOTOR DRIVERS AND BRUSHLESS ESCS THAT MAKE IT SIMPLE AND EASY FOR YOU

The central aim of this type of programming is to deliver drivers which are set up and ready to go for the specific application that you need. Many of our customers have previously used stepper motor drivers or brushless ESCs where they have to try and manually set up specific speeds using either a pot or other mechanical methods but with Zikodrive Motor Controllers we can preset exact speeds into your motor controller so that you can simply take it out the box and plug it in….

MORE COMPLEX PROGRAMMING OF YOUR STEPPER MOTOR CONTROLLER OR BLDC MOTOR DRIVER…

As useful as the simple parameter setting programming can be in a range of applications it is just the tip of the iceberg of what can be achieved with Zikodrive Stepper Motor Controllers or Brushless ESCs.

For more technically advanced and demanding motor control applications we can set up controllers to run specific sequences (see the Rotating Prism Case Study). These sequences can then be triggered with a signal input or can be setup to be modified using external switches or pots. Always bear in mind that we can set up any motor controller to operate with a range of external user controlled inputs such as buttons, pots and more.

In even more complex examples the level of programming and motor control that we can implement is limited by memory on the motor controllers. To pre-programme detailed sequences obviously takes time and the more complex the requirement the more memory the programme will ultimately take up but there is a significant amount of programming that can be done on all our motor controllers.

If you want to get a sense of the level of complexity that can be achieved then a good place to start is with the iD Stepper Motor Controller specifically developed for Boxer Pumps . This features a significant amount of complex programming in order to incorporate automatic pump calibration, dosing monitoring, a full usre interface and second tier calibration interface and a whole host of other features.

CONCLUSION –  COMPLETE PROGRAMMING OF STEPPER MOTOR CONTROLLERS AND BRUSHLESS MOTOR DRIVERS TO MEET YOUR PROJECT’S NEEDS

Just ask! If you have a specific requirement that you would prefer to be directly programmed into a controller rather than operated by UART or similar protocol then we are probably able to help. Stepper Motor Drivers such as the ZD4LCD are designed to be customised and so we will need to work with you to develop your specific application.

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Two methods for implementing closed loop control with brushless motors…

Closed loop control involves driving a motor but then monitoring the speed of the motor and using the monitored information to inform the behaviour of the driver.

In this sense there are two methods by which brushless motors can be operated in a closed loop.

The first is using a sensored brushless motor and using the onboard hall effect sensors to monitor the rotor speed and position. This can then be fed back into a brushless motor controller which can then process the information and change the way in which it drives the motor according to the core requirements of the application.

The second method involves using sensorless brushless motor controllers but then using the back electro-motive force (also known as back-EMF) to monitor the speed and number of rotations of the rotor.

Is one method better?

This is the big question!

Broadly speaking, most engineers would argue that using hall effect sensors is ultimately the most accurate and therefore the best route to go down if you need a closed loop brushless system.

The onboard sensors can tell you exactly where the rotor is and what speed it is doing and essentially do the job of an encoder but without the additional cost of buying an encoder.

That said, sensored motors and controllers do typically cost more money which can be a downside depending on other applications.

They also are ultimately less reliable than sensorless brushless motors because there are more things that can go wrong, typically the sensors. This is an especially important factor to consider in applications where there may be lots of dust or other issues which could interfere with the sensors.

If one of these sensors breaks then the controller will not be able to operate and this could lead to an expensive repair.

Which brushless motor controller do I need for each method?

To use the sensors on a sensored brushless motor you will need to use a sensored brushless motor controller. A sensorless brushless motor controller will be able to drive a sensored brushless motor but not by using the sensors.

For a closed loop brushless system based on back-EMF you will need a sensorless brushless motor controller such as the ZDBL15.

This sensorless brushless motor controller will be able to drive either a sensored or a sensorless brushless motor controller in a closed loop system by using the back-EMF generated to measure motor speed and determine rotor position.

In conclusion…

The type of brushless closed loop system we would recommend will ultimately depend on the type of project or application that you have. Both systems have pros and cons which are technical and financial.

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Optimised for your motor and your application…

If you have looked through our website and particularly the sections on brushless motors and brushless motors then you have probably seen reference to optimising brushless motor controllers for your specific motor.
What we mean by this is that we can set up any of our ZDBL Series Brushless Motor Controllers to be specifically optimised to the motor that you have chosen and the application that you are working in.

OK, I think I understand, so how does this work in practice?

In practice, we will request a sample of the motor that you are using or are wanting to use and will also request details of the application that you are using the motor in (we are always happy to sign NDAs as required). Once we understand this we will then be able to optimise all aspects of the controller to deliver the maximum possible mechanical performance and the most energy efficient performance from the motor.

We do this by profiling the motor and application based on the number of poles, the inertia at startup, the inductance of the coils in the motor and other factors such as top speed, acceleration required and more. Once we understand all of these we can then programme the brushless motor controller that you have chosen to deliver the exact performance you require.

This sounds good but why should I use it?

In practice, optimising a brushless motor can deliver significantly improved performance most notably in sensorless brushless applications where issues are arising with the startup phase and also the general running of the motor. Parts of this improvement are akin to getting the timing exactly right on an internal combustion engine. If one cylinder is misfiring or the timing is marginally out then the point at which the force is applied will not be the optimum point. This then leads to a situation in which the power will not only be wasted but will actually then start to work against the engine.

In many respects a brushless motor and controller are similar. By understanding the application requirements and the key specifications of the motor we can ensure that power is applied in the most efficient manner possible to deliver the output that is required.

How much does it cost?

We charge £40/hr for setup and testing and most motors can be set up in 2-3 hours. Once this is complete you will then receive a part number which you can then use to reorder the exact same controller/programme combination at the stock price.

For more complex projects that may need fine tuning in situ we can also help but this may require a site visit. If you have a project or application that you would like to use an optimised controller for then you can CONTACT US today to talk to one of our engineers.

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THEY ARE ALL FUNDAMENTALLY DESIGNED TO MAKE A BRUSHLESS MOTOR TURN AS YOU REQUIRE IT TO

Fundamentally all of the various types of brushless motor controller that we discuss below all do basically the same job, making a brushless motor operate in the way that you would like it to. Some of these are much simpler than others and all have certain pros and cons both technically speaking and commercially speaking. So, let’s get started then….

THE DIFFERENT TERMS USED FOR BRUSHLESS MOTOR CONTROLLERS

  1. Brushless ESC a Brushless ESC standards for a brushless electronic speed controller. The term is used quite widely for the lowest cost type of brushless motor controller. Essentially these are low cost simple drivers for brushless motors which translate incoming power into the correct sequence required to successfully drive a brushless motor using discrete components. We sometimes use this phrase in relation to the ZDBL Series of Sensorless Brushless Motor Controllers as a useful shorthand for certain applications.
  2. Brushless Motor Controller a brushless motor controller will typically feature more in depth and powerful control over the brushless motor and is often based around an intelligent microcontroller which can deliver increased reliability, improved energy efficiency and greater control over particularly difficult aspects of brushless motor control such as starting a sensorless brushless motor under load. Where a brushless ESC will typically convert an incoming voltage into the right drive pattern for a brushless motor, a brushless motor controller can be much better optimised to deliver a range of performance advantages, including closed loop control using back EMF to deliver constant speed under a variable load. It is important to note that a brushless motor controller may be designed specifically for a sensored brushless DC motor (as opposed to a sensorless brushless motor). Always remember that a sensorless brushless motor controller can drive a sensored or sensorless brushless motor but a sensored brushless motor controller can only drive a sensored brushless motor.
  3. Sensorless Brushless Motor Controller a sensorless brushless motor controller is a motor controller which is designed to operate specifically with a sensorless brushless motor. The crux of the matter is that a sensorless brushless motor does not include sensors which can tell the controller where the rotor within the motor is. Sensorless brushless motor controllers therefore typically operate an open loop system but can be used in an closed loop by using back-EMF to sense where the rotor is. 
  4. BLDC Motor Driver As you probably know, the phrase BLDC is shorthand for Brush Less DC. A BLDC motor driver is generally very similar to a Brushless ESC in the sense that it is designed to drive the motor and control its speed without adding any additional control intelligence.

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THE QUICK ANSWER…

Yes, although starting sensorless brushless motors under load is one of the hardest aspects of operation of sensorless brushless motors.

THE KEY PROBLEM WITH STARTING A SENSORLESS BRUSHLESS MOTOR UNDER LOAD – HOW TO APPLY STARTUP POWER WITHOUT KNOWING THE ROTOR POSITION…

The key to successfully using a sensorless brushless motor controller to drive sensorless brushless motors in an energy efficient and practical way is the timing of the power input into the motor coils. If the timing is slightly out then this will cause major inefficiencies within the motor and can even act as a brake on the motor’s turning.

This can also create excess heat and wasted energy (a common issue with lower cost brushless ESCs which often start to overheat and burn out relatively quickly).

When a motor is up and running it is relatively easy to know the rotor positions on a sensorless brushless DC motor as this can be detected using back EMF and then optimised at the testing and setup stage through testing and understanding the exact motor being used. 

However, at the startup stage it is impossible for the BLDC motor driver to know the inertia on the rotor or the rotor position on a sensorless BLDC motor because there is no movement from which to gain the back EMF information which the brushless motor controller can use to pinpoint the rotor location.
It is therefore quite common for sensorless motors to jump around a little at the start if they have not been properly optimised because the brushless motor controller being used is powering on coils on an assumed position with the aim of pulling the rotor into that pattern when it will then function normally.

Hence, the often stuttered startup followed by a sudden boost as the rotor aligns with the drive pattern (this is often compared to an engine struggling to start, coughing and spluttering, before suddenly roaring into life).

OPTIMISING SENSORLESS BRUSHLESS MOTOR CONTROLLERS TO START UNDER LOAD

The key to optimising a brushless motor controller to start under load is firstly to know the motor that you are working with and its application and then to optimise the brushless motor controller to the key specifications of this particular motor and the application. Key variables such as inertia, number of poles, inductance and more can all be used to optimise the controller to run well.

The Vert Rotor case study provides a good example of this.

Once this is done the running of the motor will be as efficient as possible and this knowledge can then be used to inform the startup sequence for the motor. Knowing the number of poles and the motor inductance is a big part of this as this can be optimised specifically for the motor.

However, advanced programming in the ZDBL range of brushless motor controllers is also carefully optimised to read changes in back-EMF at the earliest possible stage of motor commutation therefore allowing it to quickly pick up the rotor position and apply power in the optimal way.

A TAILORED SOLUTION DELIVERS THE BEST RESULTS

There is no doubt that starting a sensorless brushless dc motor under load is not the easiest aspect of motor control to master but with the ZDBL series of brushless ESCs we have come pretty close to developing a system which works well in a huge number of applications.

Sometimes this can require a significant amount of optimisation and hard work but in the long run it pays off, particularly where such performance is a key part of your application.

For more information you can browse the Vert Rotor Case Study or browse our range of brushless motor controllers (brushless ESCs) for more information.

If you have any questions at all please do not hesitate to CONTACT US to discuss with one of our engineers.

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CAN’T I JUST USE A FLOW METER?

Of course you can, but using a flow meter can be expensive and complex and there are some other interesting alternative options which are worth investigating first….

THE SIMPLEST BRUSHLESS ESC DOSING SOLUTION – DOSING BY TIME…

The quickest and simplest way of setting up a sensorless brushless ESC or sensorless brushless motor controller for dosing applications is to use time. In essence this can be done through an automated system which will calibrate a specific liquid through a specific tube diameter over time. Once the amount dosed/time is known it is then possible to calibrate the system using a simple control mechanism so that if a certain volume is required, the controller will know that it needs to run for a certain amount of time. For example, if the calibration process has worked out that 10s will deliver 100ml of a particular substance then a user could input 75ml into the controller and it would run for 7.5 seconds.

 

WHAT ARE THE PROBLEMS WITH USING TIME AS THE KEY VALUE IN DOSING APPLICATIONS?

The key issue with using time as the key ‘measurable’ in a dosing application is that time is not volume – in other words we are not accurately measuring the volume of a particular substance but are approximating volume by time. Whilst this might sound slightly it is fundamentally important. If one considers a large barrel of a particular chemical – for example chlorine – which is being dosed into a swimming pool at regular intervals to ensure the water remains fit for human use then the output of this barrel must be at the bottom of the barrel.

As the barrel reduces the pressure on the fluid will reduce. Whereas the first few doses will have practically  been forced out by gravity, the last few require careful pumping to be delivered. If time were used as the key variable by which the volume was determined, it is therefore quite likely that there may be a significant difference between the first dose out of the barrel (which would have been heavily gravity assisted) and the final dose (which would potentially have had gravity opposing it). The result is a changing volume as the pressure changes.

NOTE: it is worth highlighting here that in applications where the input pressure on a pump is stable, time can be a very good measure provided all other factors remain constant (such as tube diameter, distance pumped etc.). However, in practice most applications have changing pressure of some sort so time will never be quite as accurate as other methods.

USING BACK-EMF TO MEASURE THE NUMBER OF TURNS OF THE BRUSHLESS DC MOTOR

The ZDBL Series of Sensorless Brushless Motor Controllers use back-EMF most commonly as a means of determining (and potentially adjusting) the speed of the motor. However the ZDBL BLDC Motor Controllers can also be set up to count the rotations of the motor which can therefore give a much more accurate indication of volume (depending on the type of pump being used) because if we know the volume of the pump and the rate it pumps at then we can determine that a set volume requires a set number of turns. In a test carried out with an OEM diaphragm pump on dosing 50ml using this method we generated a margin of error of 1-1.5%.

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BRUSHLESS DC MOTORS – THE FUNDAMENTALS

In order to know whether a not a Brushless DC motor is right for your application you need to think about several factors, some mechanical, some commercial and some of which will be down to your choice of brushless motor controller (sometimes also know as a brushless ESC or BLDC motor driver)

MECHANICAL FACTORS WHEN CONSIDERING BRUSHLESS DC MOTORS

BLDC Motors offer the highest speeds possible from any motor and have exceptional life. This is due quite simply to the absence of brushes within the motor which reduces friction (and therefore enables higher speeds) but also improves lifespan by removing the one part a brushed DC motor which will wear out with time and use. Bear in mind that the performance you can get from a brushless DC motor will also strongly be dictated by the brushless motor controller you choose to use. A low end BLDC ESC will deliver basic speed controls but may not be energy efficient or able to use advanced features such as back-EMF monitoring and constant speed adjustment whereas a more advanced industrial type BLDC Motor Driver such as the ZDBL15 can be optimised to be hugely energy efficient and also to maximise the mechanical performance of the motor.

An important to consider if you are looking for specific qualities in a BLDC motor is that they are not generally known for positional accuracy or torque. If you need high torque you could add a gearbox but if positional accuracy is important you would be best looking at stepper motors.

COMMERCIAL FACTORS – DOES USING A BRUSHLESS MOTOR AND BLDC MOTOR CONTROLLER MAKE FINANCIAL SENSE FOR MY APPLICATION?

Brushless motors are not the cheapest motors on the planet but they are probably the longest lasting. However, if your project is very price sensitive then a BLDC motor could still be achievable but it is likely that you would save money by using a brushed DC motor. If financial considerations are a major part of your considerations it is worth thinking about the lifespan of the project that you have as a brushless motor controller will last an average 5 times longer than a standard DC motor. If the cost of a brushless system is four times the brushed system but you need solid performance over a long lifespan then it is likely that the brushless motor system will be the most cost effective over the project lifetime.
A useful rule of thumb when selecting a motor for your project is that a brushed DC motor will typically operate well for 2000 hours whereas a brushless DC motor will operate well for 10000 hours. This obviously varies by manufacturer and motor type but if your application is likely to require regular and sustained use then a brushless DC motor and controller could actually be the most cost effective in the long run.

 

CONCLUSION – THINK ABOUT THE THINGS WHICH ARE MOST IMPORTANT FOR YOUR APPLICATION

Motor choice is rarely simple! The trade offs between life, performance and cost are something that needs to be taken into account when making the decision as well as the importance or value attached to key features such as constant speed under variable load. Think about which of these factors is most important to you before making a decision and if you require any advice at all please CONTACT US and we will be more than happy to help.

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AN EMERGING TREND IN MOTOR CONTROL APPLICATIONS

The simple answer is yes.

Many companies are increasingly replacing DC motors with brushless DC motors in a wide range of applications.

The main reasons for this is that BLDC motors and controllers offer improved lifespan, improved power density and improved mechanical performance.

In other words, they deliver more power from a smaller package, last longer and go faster!

THINGS TO CONSIDER WHEN SWAPPING A DC MOTOR FOR A BRUSHLESS DC MOTOR

The key to making the transition successful is knowing the performance characteristics and key specifications of the DC motor that you are wanting to replace and then being able to make a good match with a brushless DC motor.

This does not need to be an exhaustive list but a focus on torque and speed requirements as well as the physical dimensions of the shaft and motor body will usually suffice.

Always bear in mind you will also need to use a brushless motor controller or brushless ESC to drive the brushless motor so make sure you also have room for this within the space you need.

CHOOSING THE RIGHT BLDC MOTOR DRIVER OR CONTROLLER FOR YOUR APPLICATION

As mentioned above, with brushless motors you will need a brushless motor controller (sometimes known as a brushless ESC or BLDC motor driver) such as the ZDBL5 brushless motor driver in order to drive the motor.

This is because applying direct power to a brushless motor will simply lock it in one position. In order to make the motor turn you therefore require a motor, a controller and a method for telling the controller what you want it to do.

If you have been using a very basic DC motor then it is likely that you will simply want to apply a voltage and current and get the motor to turn at the speed and torque that it did before.

If this is the case, we can help.

Our engineers can custom programme the ZDBL Series to very closely match the performance characteristics of a previously installed DC motor. It does take a little time to get it right but once it is set up we will simply assign a part number and you can order the same pre-programmed controller at your leisure.

If this is what you are looking for then we strongly recommend that you CONTACT US via email or online chat with a datasheet or part number of the motor that you want to replace. We will then review the best options available and get back to you with a proposal. Of course, if you have any questions at all about doing this please do not hesitate to give us a call.

FINER CONTROL OF THE MOTOR

However, if you are looking for something with finer control then using a brushless motor controller from the ZDBL Series will enable you  to control the speed of the motor in a number of ways.

For example, the speed can be controlled by using external hardware such as pots or by using a 0-5v analogue voltage input (onto the brushless motor controller) or by using a range of COMMUNICATIONS PROTOCOLS delivered from a PLC or other form of central controller.

For more on the pros and cons of different motor types please see our guide to CHOOSING A MOTOR.

CONCLUSION

It is worth re-emphasising the importance of the physical size of the motor in making the change as we have worked with some clients who have found the perfect motor specification from a torque and speed point of view but who have missed the fact that the brushless motor they had chosen had a 5mm shaft when they needed a 4mm shaft to make a direct replacement.

1mm difference can take up a huge amount of time and money so please do check.

Beyond this focus on the key performance criteria of torque and speed and how you would like to control the motor.

Once you have these specifications in place it is possible to source a similar brushless motor and use a brushless motor controller to drive it.

If you have any questions at all about what is best you can always CONTACT US and we will be more than happy to help.

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A BRUSHLESS DC MOTOR WITH THE HALL EFFECT SENSORS TAKEN OUT…

A sensorless brushless DC motor (sensorless BLDC motor) is quite simply a brushless DC motor without hall effect sensors. Hall effect sensors are sensors which are built into sensored brushless motors which are used to tell the brushless motor controller exactly where the rotor position is. This can be useful for maintaining set speeds and is particularly useful at start up as the rotor position dictates the start up sequence for the motor.

OPERATING A BRUSHLESS MOTOR WITHOUT SENSORS – THE IMPORTANCE OF SENSORLESS BRUSHLESS MOTOR CONTROLLERS

Based on the fact that the motor has no in built sensors then this means that the brushless motor controller has to operate the motor without the use of sensors. One of the ways this can be achieved is through using the back-EMF of the motor to actively monitor the rotor position (and therefore speed). Put simply, back-EMF can be defined as the voltage created by the motor (as a generator). A brushless DC motor is actually very similar to a generator such as one might find in a dynamo or turbine and so as it is driven round by the BLDC motor driver it will also start to generate electromagnetic force. This then works against the forward voltage produced by the driver but crucially the frequency of the force is directly related to the speed of the rotor and can be measured by an intelligent sensorless brushless motor controller such as the ZDBL10. By using this back-EMF frequency measurement it is therefore possible to measure the speed of the motor and compare it to the speed that the brushless motor controller is trying to achieve – any discrepancies can then be adjusted if required (a closed loop system) or left as they are (an open loop system).

KEY ADVANTAGES OF A CLOSED LOOP SENSORLESS BRUSHLESS MOTOR SYSTEM

With an intelligent controller such as the ZDBL15 brushless ESC closed loop sensorless brushless motor systems can achieve impressive performance both in terms of accurate speed maintenance but also dosing performance in small brushless gear pumps or diaphragm pumps. Key to this is the fact that accurate back-EMF measurement not only delivers accurate speed monitoring but it can also be used to count revolutions of the motor.

Of course, a further additional advantage is that sensorless brushless motors and BLDC motor controllers are also lower cost than Sensored Brushless Motors.

If you have any questions in relation to Sensorless Brushless Motors please feel free to CONTACT US to discuss.

 

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A sensored BLDC motor is a brushless DC motor with inbuilt positional sensors (called hall effect sensors). These sensors can be used by a brushless motor controller (brushless ESC) to monitor the exact position of the rotor and are therefore a useful method of maintaining speed of the brushless motor. These sensors are also particularly useful during the start up phase as it enables an optimised sequence to be applied depending on the exact position of the rotor.

THE DISADVANTAGES OF USING SENSORED BRUSHLESS MOTORS

There are however, disadvantages to such motors. Firstly, they are more expensive than sensorless bldc motors due to the added components and the additional complexity involved in construction. As a result of the additional complexity they are also more prone to problems, especially in applications where there are potential issues with humidity or dirt as any interference with the sensor’s performance will ultimately jeopardise the entire control of the motor.

I HAVE A SENSORED BRUSHLESS DC MOTOR, CAN I USE A SENSORLESS BRUSHLESS MOTOR CONTROLLER?

The simple answer is yes, although the sensorless brushless motor controller will clearly not be able to make use of the hall effect sensors.

A sensorless BLDC ESC or brushless motor driver such as the ZDBL10 will not be able to make use of the inbuilt sensors within the motor but it will still be able to drive the motor using a sensorless brushless drive. Speed can be accurately maintained by using the back-EMF generated by the motor to read and determine the speed of the motor (in the same way the hall sensors would do in a sensored bldc motor). This can then be used to maintain a fixed speed even under a variable or changing load.

If you are not sure about how this might impact on performance please CONTACT US TO DISCUSS.

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THE QUICK ANSWER…

A typical stepper motor has 200 steps to complete a 360 degree complete rotation (hence 1.8 degree stepper motors such as the ZDSPN1718). Full step mode would therefore enable a total of 200 positions in the 360 degree circle.

Microstepping is where a stepper motor controller is driven in a way that enables it to divide these steps up into further steps (or microsteps). These start at half steps but can go as high as 1/128 microsteps with the ZD Series of Stepper Motor Controllers.

This means that each of the 200 individual steps that are built into the motor have now been divided up into 128 separate steps by the controller. This enables the combined motor and controller to stop at anyone of 25600 possible positions around the 360 degree complete revolution.

MICROSTEPPING DOES NOT JUST DELIVER IMPROVED POSITIONAL ACCURACY…

When we first explain microstepping to some of our customers they assume that the main advantage of additional microstepping is that it delivers much greater positional accuracy for applications such as robotics or highly accurate dosing.

However, there are a number of other additional benefits which can be derived from microstepping;

  • Quieter operation – microstepping smoothes out the drive signal going into a stepper motor by replacing the square wave step-step-step with a more smoothed out (finer resolution) curve. It is not a sinusoidal drive but the obvious analogy would be between very low resolution digital audio and higher resolution digital audio. By increasing the
  • More efficient operation – by smoothing the drive signal out it is possible to reduce energy consumption. In part this is the result of

MICROSTEPPING IS FASTER

Don’t forget that, because microstepping is more energy efficient and uses smaller, more frequent pulses, it allows stepper motors to reach slightly higher speeds than they normally would.

WHEN TO THINK ABOUT USING MICROSTEPPING

Based on the key points identified above it can be seen that the most appropriate applications for microstepping are those which either require exceptional positioning accuracy or those where energy efficiency and noise are important. In the majority of cases we would normally suggest using microstepping of some kind as it can usually lead to general improvements such as quieter and smoother operation but depending on the torque requirements of your project or application it is always best to discuss with one of our engineers first.

CONCLUSION

Using microstepping offers a large range of potential benefits depending on the nature of your application. From increased smoothness and positional accuracy to greater energy efficiency and speed. Why not browse our range of ZD Series Stepper Motor Drivers and see what they could do for your application today.

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STEPPER MOTOR CONTROLLERS VERSUS STEPPER MOTOR DRIVERS – THE TERMS IN GENERAL USE

The first thing to understand with the comparison between a stepper motor driver and a stepper motor controller is that the terms are used rather interchangeably despite often being strictly incorrect.

As happens within many walks of life it is often quicker to refer to something as a ‘driver’ or ‘controller’ rather than a ‘combined stepper motor controller and driver’. (We are ourselves guilty of doing the same thing on this website for the sake of trying to make articles and descriptions easier to read).

LET’S UNDERSTAND THE TECHNICALLY CORRECT TERMS THEN

A stepper motor driver is an electronic component which can convert an input signal of some kind into movement of the stepper motor without itself being able to issue instructions (or control) the stepper motor.

It is often useful to consider the driver as a ‘translator’ between input signals and the physical movement of the stepper motor.

In some cases stepper motor drivers may be designed specifically to work with a set communication protocol such as analogue or CANbus but the broad principle is simple – they do not have any ability to control the motor themselves except where they are given control instructions from a computer, PLC or other control device.

In contrast to this a stepper motor controller such as the ZD Series Stepper Motor Controllers can actively control and drive the motor itself. Strictly speaking such units should be referred to as a stepper motor driver and controller but it is perhaps understandable why people frequently shorten this down to stepper motor controller for ease of use.

A good visual example of this is probably the ZDLCD Series Stepper Motor Controllers. A stepper motor controller such as the ZD4LCD can quite clearly be seen to be both driving and controlling the stepper motor from the same unit.

The person using the controller puts in the instructions they need and the controller part of the unit then issues instructions to the driver part of the unit which converts the instructions into the physical sequences that the motor needs in order to turn.

CONCLUSION – A SLIGHT MINEFIELD

Hopefully you can now understand the basic differences between the two units in a technical sense and also understand why the terms are often a bit muddled in general use.

In simple terms the most important thing to understand is what you need for your project to work well and whether or not this is a stepper motor controller or driver.

If you have any questions about this you can always CONTACT US to talk to one of our engineers or alternatively review some of our similar questions in the FAQs section.

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Quite simply, yes.

There are several ways to do this.

Using an Encoder, a pot or Hall Effect Sensors

By using an encoder or pot on the back of a motor it is possible to actively monitor the exact speed of the motor and adjust it at any time to the speed required. This is called a closed loop system. An incremental encoder works by pulsing as the shaft turns and then sending these signals back to controller. This enables the controller to read the speed of the pulses and therefore accurately calculate the speed. An absolute encoder or pot works in a similar way but uses the variable resistance of the pot or the electromechanical construction of the encoder to enable the controller to calculate the absolute position of the shaft.

Hall effect sensors are largely used in brushless DC motors as a method for sensing the position of the shaft within the motor itself. These sensors are (perhaps rather predictably!) only found in sensored brushless DC motors and not in sensorless brushless DC motors. Bear in mind that sensored brushless DC motors can be driven by sensorless brushless DC motor controllers but that sensorless brushless DC motors cannot be driven by sensored brushless DC controllers…

All of these methods can be used to accurately judge the exact speed of the motor shaft and therefore make adjustments and can be used in both brushless motors or stepper motors (or indeed brushed DC motors). In all of these cases a change in the actual speed of the motor which was caused by an increase or decrease in load would be instantly picked up by an intelligent controller such as the ZD10 Stepper Motor Driver or the ZDBL15 Sensorless Brushless DC Motor Controller and the ZD10 or ZDDC could then be programmed to increase or decrease the power going into the motor to correct the speed.

Please note that in such systems safety features can become very important as there is obviously a cut off point at which the stepper motor controller or BLDC motor driver will not be able to deliver the power required to turn the motor if too much load is applied (ie the top power rating of the controller and/or motor). By having maximum current settings and other protective measures it is possible to protect the motor and controller by simply stalling the system and highlighting the error accordingly.

Using Sensorless Brushless Motor Controllers that measure Back EMF

Speed monitoring and constant speed can also be achieved without encoders and similar devices by using a brushless motor driver (brushless ESC) such as the ZDBL10 which can measure the back EMF from a brushless motor and therefore determine the speed of the motor and make adjustments accordingly. Back EMF stands for Back Electro Motive Force and is a force generated by the action of the brushless motor turning. Because Back EMF frequency is directly related to the speed of the motor (it is similar to the way in which power is generated using a wind turbine for example) this frequency can be read by the BLDC motor driver and the speed of the motor calculated accordingly. It should be noted that this is generally a much lower cost option than using encoders and similar devices.

Conclusion

The nature of your application and the budget that you are working to will ultimately determine the most appropriate way to set your system up but the key thing to note is that there are several ways in which constant speed under variable load can quickly be achieved. Of these, using a sensorless brushless motor controller such as the ZDBL15 is probably the lowest cost and simplest but if you require a greater level of accuracy then it may well be the case that using an encoder or pot would be more beneficial.

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What are the main advantages of using stepper motors?

POSITIONAL ACCURACY WITH STEPPER MOTORS

In general the main use of stepper motors is in motor control applications where positional accuracy is hugely important. Whereas a ‘traditional’ brushed DC motor turns constantly as soon as enough power is applied, a stepper motor can be turned an exact number of steps (up to 25600 steps in one complete revolution with a stepper motor drivers such as the ZD2). Depending on the number of degrees per step in the motor (this varies from motor to motor but in a standard 200 step motor this equates to 1.8 degrees per step) this can then enable the motor to move from one fixed position to another fixed position at any point of the circle. By using intelligent controllers such as the ZD series of stepper motor drivers, this movement can then be controlled very accurately with programmable acceleration and deceleration curves being applied. This is especially useful in dosing or process control applications where exceptional accuracy is crucial.

STEPPER MOTOR PERFORMANCE IS 90% DOWN TO THE STEPPER MOTOR CONTROLLER

The way in which a stepper motor performs and is able to operate is clearly heavily influenced by the build quality of that particularly motor. Conventional factors such as the quality of the bearings and magnets used are still of great importance. However, in terms of delivering the true potential of the stepper, it is the controller that can really make a difference.

As an example a simple stepper motor driver will simple convert an input current and voltage into motor torque and speed. Compare this to a comprehensive ‘all in one’ stepper motor driver and controller such as the Zikodrive ZD4 Stepper Motor Controller which has onboard memory, 128 microstepping and full programmability. With the ZD4 Stepper Motor Controller being used it becomes possible to directly control the stepper motor position, its acceleration and deceleration curves, custom startup sequences, the exact speed and torque and to store these settings within the controller. This enables the stepper motor to be completely optimised and opens up a whole new world of potential mechanical performance and applications.

ALTERNATIVE APPLICATIONS FOR STEPPER MOTORS

The simplest case study which highlights some of the advantages of stepper motors of this type of application is the rotary prism system built by Zikodrive Motor Controllers and S3 Design. Whereas a brushless DC motor and controller would require careful calibration, timing and the use of encoders and limit switches to rotate a prism 120 degrees, wait a set time and rotate another 120 degrees, with a stepper motor this can be achieved relatively simply because it is possible to measure the exact number of steps required to make this movement and use an intelligent controller to make this movement.

If one considers more complex applications such as robotics or highly accurate dosing equipment then one can appreciate how useful having this level of control would be. By adding a controller capable of microstepping such as the ZD4 Stepper Motor Driver (this offers up to 128 microsteps) it is possible to gain exceptional positional accuracy. Based on a standard 1.8 degree 200 step stepper motor, the ZD4 Stepper Motor Driver can move accurately between any of 25600 points of a circle.

CONCLUSION – COMPLETE MOTOR CONTROL

Fundamentally, it can therefore be the key advantages of stepper motors is that they enable the motor to stop and start at any point required with exceptional accuracy. In combination with an intelligent stepper motor controller it is possible to achieve exceptional positional accuracy and performance from a stepper motor that is quite simply unachievable with any other type of motor.

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Replacing a brushed DC motor with a stepper motor and controller?

REPLACING BRUSHED DC MOTORS WITH STEPPER MOTORS – THE QUICK ANSWER

Yes but you must be careful to make sure that the specifications of the original motor you have and the new motor and controller you install match. If in doubt at all you can CONTACT US to discuss your application.

AN EMERGING TREND IN THE MOTION CONTROL INDUSTRY

Many companies are increasingly replacing DC motors with brushless DC motors and brushless motor controllers in a wide range of systems.

You can find out more about this by reading our article on replacing brushed DC motors with brushless motors.

However, swapping DC motors to stepper motors and controllers is less common. That said, as with lots of things in life and in engineering, just because something is not common, does not necessarily make it a bad idea. There are a number of specific applications in which replacing a brushed DC system, (particularly a geared DC system) with a stepper motor and controller can be a very sensible choice.

WHY SHOULD I REPLACE A BRUSHED DC MOTOR WITH A STEPPER MOTOR?

The simple benefits of doing so are that you will improve the lifespan of the system you have (stepper motors only have bearings as parts that can wear out as opposed to brushes).

Stepper motors also improve the range of performance options available (they can turn a fixed number of degrees easily).

Stepper motors can also be used to increase the

REPLACING GEARED DC MOTORS WITH STEPPER MOTORS AND CONTROLLERS IN DOSING APPLICATIONS

What is more common is to replace geared brushed DC motors with a stepper motor in applications such as pumps, lab equipment and similar applications where positional accuracy can be improved vastly by using a stepper motor and stepper motor controller.

Many applications were addressed in years gone by by using a geared DC motor and timing as a means of dosing and measuring – however developments in stepper motor controller technology such as on the ZD4 Stepper Motor Controller means that huge advances have been made in the accuracy, flexibility and performance of suhc systems.

Of equal importance, the cost of such technology has dropped considerably in recent years, making advanced performance options affordable to a broad range of applications.

Whereas 10 or 20 years ago a programmable stepper motor controller would have cost a fortune, these days it is much less.

The result of this trend is that many people and companies have started to look at replacing geared brushed DC motors with stepper motor controllers as a means of improving the performance of the system and also as a way of adding more features.

DON’T FORGET TO DO YOUR HOMEWORK

The key to making the transition between the two units successful is making sure you know the performance characteristics and key specifications of the motor that you are wanting to replace and then being able to make an appropriate match with a stepper motor and controller. If you are not sure how to find out the performance characteristics of the motor (and gearbox) that you have you can start with the part number of the motor and research that. Key characteristics to look for are max and nominal RPM and torque.

Once you have these details you then need to source an appropriate stepper motor with the right performance characteristics. Don’t forget to check the torque speed curve of the motor to make sure it will deliver the torque you need at the speed you want (if you are not sure about this you can find out more about this by reading our guide to understanding torque speed curves). If you have any questions at all about implementing this system then you can always CONTACT US and talk to one of our engineers about your specific project or application.

WHAT NEXT?

If you have an existing project where you are looking to replace a DC motor with a stepper motor and controller you could start by having a look at our main STEPPER MOTOR page. This page has links to case studies, applications, stepper motors with controllers and much more…

If you have any questions about anything that you have read above please feel free to CONTACT US to discuss.

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How much speed can I get with a stepper motor?

THE AVERAGE MAXIMUM SPEED OF A STEPPER MOTOR

Generally speaking the top speed of a stepper motor is approximately 1000rpm. The exact speeds that are possible depend on the specific motor being used and the controller being used with it. For example it is possible to overdrive a smaller stepper motor with a higher powered controller but this will result in reduced life span and any of the benefits of doing so will largely be minimal in comparison to using a brushless DC motor at the rated speed. It is important to remember that the torque generated by a stepper motor is significantly reduced as the speed increases.

If you would like more information on torque speed curves and how they can help you choose the best motor for your project then please see What is a torque/speed curve and how does it affect what I need?

If you need to go above this speed but still require intelligent control of the motor you should consider a brushless DC motor and controller (brushless ESC).

STEPPER MOTORS HAVE DECREASING TORQUE AS THE SPEED INCREASES

A point which is often overlooked is the fact that the available torque from a stepper motor decreases significantly as the speed increases. This often means that in applications where the motor is under a certain load (which it obviously has to be as it is driving something) the max speed will be inherently reduced by the amount of load on the motor. This is why it is so important to understand the load that you need to place on the motor when choosing a motor.

I NEED A LOWER SPEED AND A HIGHER TORQUE FROM A STEPPER MOTOR

If you need a lower speed and higher torque to make your motor control project work do not forget that you can always use geared stepper motors. Gearbox ratios typically range from 2:1 up to about 50:1 and this can dramatically increase the torque available from the stepper motor (albeit at the cost of significantly reducing the maximum speed available from the stepper motor). For example, a typical NEMA 17 stepper motor with a ZDSP Stepper motor driver will be able to achieve 0.65Nm of torque. However, by adding a gearbox to this motor – such as in the case of the ZDSPN1727GB geared stepper motor and driver package this can be increased up to 3Nm.

CONCLUSION – THINK ABOUT THE KEY SPECIFICATIONS THAT YOU NEED AND THEN DECIDE WHICH MOTOR AND CONTROLLER IS BEST FOR YOUR APPLICATION

The maximum speed of a stepper motor is dictated by a combination of stepper motor size, the type of stepper motor controller that it is being used with and also the specific application that it is going into. All of these factors need to be considered when assessing how much speed you can realistically achieve for a set application or package.

If you have any questions at all about this please feel free to get in touch with us to discuss your requirements with one of our engineers.

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NEMA Motor Frame Size Guide for Stepper Motors

FIRST THINGS FIRST

The frame size of motors is used for both stepper motors and brushless DC motors but it is used most commonly with stepper motors as a useful shorthand for power and torque.

Always remember that (within the NEMA sizing system) the length of the motor will vary but the NEMA frame size simply refers to the diameter of the motor face.

Most commonly these faces are square (for example the ZD4N2318 which is a square faced NEMA 23 stepper motor) but in some cases they may be circular.

Frame sizes are split up into NEMA (National Electronic Manufacturers Association) ratings which are a useful shorthand for motor sizes.

DIAMETER ISN’T EVERYTHING WHEN IT COMES TO STEPPER MOTOR POWER

Changing the stack length will generally not impact on the speeds that you can get but it will have a major impact on the torque (turning force) that you are able to achieve.

For example the ZD2N2318 and ZD10N2318 stepper motors are both NEMA 23 motors (therefore 57mm diameter) but the ZD2N2318 is 42mm long whereas the ZD10N2318 is 104 mm long.

The difference in torque between the 2 motors is 0.6Nm for the ZD2N2318 and 2.4Nm for the ZD10N2318. The difference in stack length of a motor with the same NEMA rating has therefore quadrupled the possible torque.

THE STEPPER MOTOR CONTROLLER YOU CHOOSE MATTERS!

Equally the stepper motor controller that you use will have a major impact on the mechanical performance you are able to achieve using the motor. If the controller is not able to deliver more poewr than the motor can handle then it is unlikely that you will be able to achieve the maximum possible mechanical performance from the motor.

As an example of this, our stepper motors with integrated controllers have higher powered controllers the bigger the motors get.

See the table below for an overview of frame sizes.

MOTOR FRAMES AND TYPICAL SPECIFICATIONS FOR STEPPER MOTORS

WHAT NEXT?

If your interest in motor sizes was purely academic then we hope we have helped. If you have any questions about this please do not hesitate to get in touch and we will do our best to help.

Alternatively if you are looking for a motor and aren’t sure which is best for your application then you could start by having a quick look at our standard range.

We offer a range of stepper motors of different sizes which are available in geared or standard format.

As always, if you have any questions about choosing the right motor or the pros and cons of a long stack NEMA 17 versus a short stack NEMA 23 (for example) then you can get in touch with us via online chat, phone or email.

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I need a custom user interface for a stepper motor controller or brushless ESC.

Depending on your requirement there are a number of potential options

SIMPLE POTS, SWITCHES AND BUTTONS?

Potentiometers and buttons/switches are the simplest form of user interface which will work with the Zikodrive range of stepper motor controllers and brushless ESCs. In combination with the programmability of all of our controllers these can be set up to operate in pretty much whatever way you might want. Typical methods usually involve having a pot as a speed control and buttons for stop/go and forward/reverse but we have sometimes added additional controls for features such as current control and microstepping. The simplest thing to do if you have something slightly more customised in mind is to give us a call or an email and we will tell you what we can do.

STEPPER MOTOR CONTROLLERS OR BRUSHLESS ESCS WITH LCD DISPLAYS AND VISUAL INTERFACES

Not all of our controllers can be set up to work with LCD displays but the ZDLCD series of stepper motor controllers shows what can be done by adding an LCD screen. Again, there are virtually limitless options available in terms of screen sizes, resolutions etc. and everything can be custom set up to what you require. To see a specific case study example of how we can develop this type of system you can view the Boxer Pumps iD Stepper Motor Controller Case Study.

To discuss your requirements in more detail send us a message or give us a call today.

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What is the difference between a single shaft and double shaft motor?

Quite simply a single shaft motor has one shaft which comes out of the face of the motor and a dual shaft motor has the shaft coming out of the face and rear of the motor. The single shaft is a straight forward concept which can be easily understood. The dual shaft can be used in a number of ways. One example is to drive 2 applications on either side of the motor. A second is to use the rear shaft to mount an encoder to actively monitor the actual speed of the motor and then make adjustments as required.

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Get the right motor controller for your motors

ALREADY CHOSEN A MOTOR AND LOOKING FOR A STEPPER MOTOR CONTROLLER OR BRUSHLESS DC MOTOR CONTROLLER?

If you have already chosen a motor for your application then you should have a good starting point with the electrical specifications of the motor. It is always best to choose a controller which has more power than the motor rating as using a controller with less power can often result in damage to the controller and will also not get the full mechanical performance range from the motor. Once you have looked at the motor drivers which meet your electrical requirements it is then time to think about what features you require.

NOT CHOSEN A MOTOR?

If you haven’t chosen a motor why not read out FAQ post on Choosing A Motor. This section is designed to highlight some of the most important issues which arise when choosing a motor and will then lead on to how to select the right brushless motor controller or stepper motor controller for your specific application.

CASE STUDY: ZIKODRIVE ZDSP STEPPER MOTOR CONTROLLER VS ZIKODRIVE ZD2 STEPPER MOTOR CONTROLLER

For this example, let’s assume you have picked a small NEMA 23 stepper motor which outputs 0.65Nm torque and requires an input current of 1.5A at 12v. Both the ZDSP Stepper motor Controller and ZD2 Stepper Motor Controller can handle this power level but they have different features which may have an impact on your choice. The ZDSP offers microstepping up to 1/16th microsteps whereas the ZD2 Stepper Motor Controller can go up to 1/128th microstepping. The ZDSP Stepper motor Controller features a 24 bit speed resolution whereas the ZD2 has a 20 bit speed resolution.

In practice the key to making the right decision is to prioritise the performance features which are most important to your specific motor control application. If you needed exceptional positional accuracy and smoothness from your motor then the ZD2 Stepper Motor Driver would be the most useful. However, if finding and maintaining an accurate speed was the most important factor then you would be better with the ZDSP Stepper Motor Controller.

ARE THERE ANY PHYSICAL RESTRICTIONS WHICH COULD IMPACT ON YOUR CHOICE OF MOTOR CONTROLLER?

You will hear us say this a lot but never forget to check the physical sizes of a stepper motor controller or brushless ESC and think about how this might impact on your application or how you might fix the controller in its particular location. Some controllers such as the ZD Series Stepper Motor Controllers have been designed to be mounted onto specifically sized stepper motors but other controllers may have been designed to be mounted ‘in line’ or fixed in DIN Rail Casings.

In addition remember that certain controllers can need heat sinking or clear air flow around them so make sure you have enough space to achieve this. If in doubt you can always give us a call and select option 2 on the initial menu to talk to someone in our technical team.

CONCLUSION – FIRST THINK ABOUT BASIC POWER REQUIREMENTS THEN THE CONTROL FEATURES YOU NEED IN A MOTOR CONTROLLER

Electrical and power ratings are fundamentally the most important factors. After that, think about what key performance features you are looking for from a motor controller. If you are looking for some practical examples of how to match stepper motor controllers to NEMA 17 and NEMA 23 stepper motors then why not view some of our stepper motor packages

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Using a torque/speed curve to determine which motor and controller you need?

WHAT DOES A MOTOR TORQUE SPEED CURVE SHOW?

A torque/speed curve plots the torque of a motor against the speed that it is going at. The relationship between the torque and the speed is critical to choosing the right motor for your application.

The most important point to consider is the relationship between the torque and the speed as the amount of torque available changes with a change in speed. A common mistake is to buy a motor based on its rated or holding torque (thinking this is perfect for your application) only to find that this torque is not available at the required speed.

Consider the torque/speed curve opposite for a typical stepper motor.

The ZD Series of Stepper Motor Controllers can be run using a range of external inputs, offers 25600 potential positions (on a standard 200 step stepper motor) and can be programmed to do virtually anything!

Depending on the torque and speed that you require for you application, we can supply the ZD Series of Stepper Motor Controllers with a range of stepper motors giving you plenty of choice!

WHAT HAPPENS TO THE AVAILABLE TORQUE AS THE SPEED INCREASES CAN BE VERY DIFFERENT FROM MOTOR TO MOTOR

As you can see in the example above the torque at lower rpm is very high but as the speed builds within the motor, the torque begins to drop away. In many respects this can be seen as a resultant trade-off given that the power going into the motor is the same. By using the power to generate higher speeds it is not possible to maintain the same level of torque. Bear in mind that the torque speed curve displayed on a datasheet is the maximum possible and that it is possible to use an intelligent controller to maintain fixed torque over a set speed range (see red line on graph). The red line illustrates how it is possible to maintain 2Nm of torque up to 800rpm but above 800rpm the torque starts dropping below this rating.

It is important to bear in mind that different motors will have unique torque speed curves and also that with stepper and bldc motors, the controller used will also directly affect the torque speed curve. The key to using torque/speed curves is therefore to understand the exact or minimum requirements that you need from a motor and therefore use the torque speed curve to make a much more accurate assessment of the motor and controller that you need.

THE IMPORTANCE OF THE STEPPER MOTOR DRIVER OR STEPPER MOTOR CONTROLLER WHEN USING A STEPPER MOTOR TORQUE SPEED CURVE

When viewing a stepper motor torque speed curve such as the one above it is common to see an explanation at the top of the diagram which will explain what controller was used in the measuring of that particular curve. Different stepper motor controllers can output different levels of power and it may be the case that the motor you are looking at could output more power if it was used with a higher powered stepper motor controller. Equally it is also important to bear in mind that a stepper motor controller set on full step will typically generate a higher torque than a stepper motor controller running a microstepping sequence so if you are thinking of utilising a microstepping programme then it is worth contacting us first to discuss.

CONCLUSION – A USEFUL GUIDE TO WHAT YOU CAN EXPECT FROM A MOTOR

The torque speed is a fundamental guide to what you can expect to get in terms of mechanical performance but it is important to understand the specific situation in which a torque speed curve was created in order to ensure it meets your expectations. If you have any questions at all about torque speed curves and how they might affect your choice of motor then please don’t hesitate to contact us via online chat or phone and we will be more than happy to help.

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CHOOSE THE RIGHT MOTOR FOR YOUR APPLICATION

The first port of call is to understand what torque and speed you require. This will immediately give you a clear idea of what is possible. As a quick example, most stepper motors do not exceed 1000rpm. Therefore if you need to go above this you will need a brushed DC or brushless DC motor. Equally if you require positional accuracy or easy monitoring of number of revolutions for an application such as dosing or pumps, then a stepper will perform much better.

SELECTING THE MOST IMPORTANT FEATURES AND PERFORMANCE CRITERIA YOU REQUIRE IN A MOTOR

The second port of call is to understand what you require from the motor for it to work successfully in your application and the extent to which each type of motor might be able to achieve this? For example, ask yourself the following questions;

1. Do you need high positional or speed accuracy?

2. Is energy efficiency and lifespan a high priority?

3. Do you need to maintain a constant torque or constant speed?

If you require high positional accuracy stepper motors are by far the best choice as they can be micro-controlled to rotate 1/100th of a degree (or more) if required. If energy efficiency are more important to your project than positional accuracy then it is likely that a brushless DC motor will be best as these offer much greater lifespan than brushed DC motors and are more efficient than stepper motors. Once you have prioritised the most important characteristics required from the motor you can then make a decision. Below is a simple table with the pros and cons of each type of motor to help you further.

CONCLUSION – PRIORITISE THE KEY FEATURES THAT ARE MOST IMPORTANT TO YOU

Fundamentally there are applications where one type of motor will be the obvious choice – for example a peristaltic pump application requiring high resolution dosing. However, on the reverse side of this there are a large number of applications where it may be possible to use any number of different types of motors. In such applications it is important to understand the pros and cons of each type of motor and how they relate to the key priorities of your specific motor control project or application

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SENSORLESS BRUSHLESS MOTOR CONTROL USING BACK EMF

Back EMF stands for Back Electromotive Force. In simple terms, the Back EMF is an electromotive force which occurs as the brushless motor turns. This acts like a generator creating electromotive resistance within the motor. Critically, motor controllers such as the ZDBL15 can measure the back-EMF generated. As the back-EMF frequency is proportional to the motor speed this enables us to determine the exact speed of the motor.

An intelligent motor controller such as the ZDBL15 brushless ESC can then read this force and use it to measure the actual speed of the motor. The ZDBL15 can then maintain this speed using Back EMF as a reference to measure and adjust the speed. It is this method which enables a sensorless brushless motor controller such as the ZDBL15 to be able to deliver constant speed under a variable load.

ARE THERE DISADVANTAGES TO USING BACK EMF IN SENSORLESS BRUSHLESS MOTOR CONTROLLERS?

No back EMF is generated when the motor is stationary, meaning that start up is difficult. As such, the motor can take a small amount of time to settle and run efficiently. A second disadvantage is that at low speeds the back EMF is weak and therefore quite difficult to measure accurately. This can result in inefficient operation in the form of jumpiness. Stepper motors are perfect if your application needs reliable operation at low speeds.

WHAT ARE THE MAIN ADVANTAGES OF USING BACK EMF IN THE CONTROL OF SENSORLESS BRUSHLESS MOTORS?

Using back-EMF as a means of maintaining and accurately controlling motor speed in brushless DC motors is a much lower cost solution than brushless DC motors with sensors and is also much more reliable as there are less component parts which can go wrong. A sensored brushless DC motor and a sensored motor controller will become completely useless if the sensors fail. However, a sensorless brushless motor controller will be able to function reliably without risk of sensor failure.

To browse the range of ZDBL Series Brushless Motor Controllers which optimise back-EMF to deliver exceptionally accurate brushless motor control please CLICK HERE

If you have any additional questions please CONTACT US to discuss. 

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