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.