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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-
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-
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-
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.
To find out more about our brushless motor controllers and related services you can CLICK HERE or if you would like to contact one of our engineers with a question please CLICK HERE.
Frequently Asked Questions
There are a huge range of applications which can be effectively dealt with using sensorless brushless motor controllers. You can explore some of our stock range of BLDC motor controllers and if you have a particular application that you would like to discuss please get in touch and our engineers will be happy to help.
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