In order to understand four quadrant motor control it is worth starting with a very quick overview of one and two quadrant motor control. In simple terms, in one quadrant motor control the controller can apply torque only in the same vector polarity (direction) that the motor is currently running at. A 2 quadrant motor controller is reversible but the same principle applies. However, with a 4 quadrant controller it is possible to use the motor controller to drive the motor in the opposite direction to its current velocity and hence to ‘brake’ it.
Put simply, the four quadrants that the controller can work in are:
1. Motor going clockwise, controller applying clockwise drive.
2. Motor going anti-clockwise, controller applying anti-clockwise drive.
3. Motor going clockwise, controller applying anti-clockwise drive.
4. Motor going anti-clockwise, controller applying clockwise drive.
It can therefore be seen that with a four quadrant controller, such as the ZDBL50DC brushless DC motor controller, it is possible to gain a much finer level of control over the motor than would be possible with a one or two quadrant system.
In most ‘traditional’ motor control applications the deceleration of the motor has been addressed either through the innate friction/resistance within the application or through the use of brakes. At its simplest, a brushed DC or AC motor was simply switched off and the system would naturally reduce to a stop. Where more active braking was required this could be achieved through the use of brakes, either mounted directly on the motor shaft or sometimes in other parts of the system.
The major benefit of four quadrant control over simply relying on the friction or resistance in the specific application is obviously that it provides more control over deceleration. However, the critical advantage of four quadrant over braking is twofold.
1. Firstly, four quadrant control can be more accurately applied than a brake to reduce the motor speed over a specific ramp. A brake system based on friction can obviously get very near this with trial and error but it will not be able to be applied in the same way.
2. Secondly, four quadrant control will reduce the risk of current spikes (and therefore motor controller damage) which can occur when a brake is suddenly applied to a system running at relatively high speed.
One of the most exciting opportunities created with four quadrant control is the possibilities of regenerative braking. As the motor is slowed down, the kinetic energy of the motor turning transfers into electrical energy which, if the controller is setup correctly, can then be used to charge a battery. It is important that this is not an inevitable benefit of four quadrant control but something that can be achieved with a controller set up in the correct way.
If you have an interest in this area please contact us to discuss.
Four quadrant control as a principle can be applied to every type of motor that has ever been made (more or less) but in reality the most common types of motor that are used with four quadrant control are brushed DC motors and brushless DC motors.
Within this categorisation the most common type of motor that is used as a four quadrant system is the sensored brushless DC motor (sensored BLDC). Controllers such as the Zikodrive ZDBL20DC brushless motor controller are typical of this in the sense that they work with sensored brushless DC motors and brushed DC motors but not with sensorless brushless motors.
If you are actively looking for a four quadrant controller for a motor that you have already chosen we would recommend that you get in touch with us to discuss the specification you require
Four quadrant controllers are technically superior to one or two quadrant controllers in every respect. They are capable of offering exactly the same level of performance as a one or two quadrant controller but they have the added advantage of being able to use the four quadrant process to actively and safely brake the motor being used. The only con of a four quadrant controller is that they tend to be more expensive than similarly spec’d one or two quadrant designs.
If we extend this argument out to a two quadrant brushless motor controller and brushless motor with a brake installed then there are a several important advantages beyond cost which are worth thinking about. These are:
1. Smoother deceleration – the four quadrant system can be used to generate smoother and more managed deceleration curves.
2. Longer controller life. A brake can cause significant current spikes which can cause damage to the motor but especially the controller. Four quadrant control removes this as an issue.
3. Energy efficiency – instead of losing energy in the form of heat or a damaging current spike, the four quadrant system is more efficient.
The importance of energy efficiency in every aspect of engineering is becoming ever more important as a result of the increasing issues and problems associated with climate change. There is therefore a major move to be able to make things as energy efficient as possible and in motor controls the advantages of four quadrant control are a good example of how technological advancements can contribute to this change.
The double advantage of increased energy efficiency and also removing the need for brakes on motor systems is hugely important because it reduces energy use and also improves the life of motors and especially controllers by removing the impact of brakes (and their related current spikes) on the core components.
Depending on the application that you are working on, four quadrant motor control could be completely unnecessary or it could be the key to making the project function as you require it to. What is certainly true is that in increasing numbers of applications such as robotics and similar types of projects, four quadrant control is becoming ever more important because of the significant performance advantages that it offers over traditional one or two quadrant design.
Zikodrive Motor Controllers offer both two quadrant and four quadrant motor controllers so if you would like to try both you can purchase both online now. Alternatively, if you have any questions about the suitability of four quadrant control for your project we would be happy to discuss your requirements.