What is the working principle of a DC brushless motor?

The main body of the DC brushless motor and the driver constitute a typical example of mechatronics. The stator windings of the motor are mostly made in a three-phase symmetrical star connection, which is very similar to a three-phase asynchronous motor. The working principle is as follows.

The driver is composed of power electronic devices and integrated circuits, etc. The controller triggers each power transistor in the driving circuit in an orderly manner according to the motor rotor position measured by the position sensor, for orderly commutation, to drive the DC brushless motor. It accepts the start, stop, and braking signals of the motor to control the start, stop, and braking of the motor, accepts the position sensor signal and the forward/reverse signal, to control the on-off of each power transistor in the inverter bridge, generate continuous torque, accepts the speed command and speed feedback signal, to control and adjust the speed, provide protection and display.

The DC brushless motor has a fast response, a large starting torque, and can provide the rated torque from zero speed to the rated speed. The microprocessor speed is also getting faster and faster, which can realize the control of the AC motor in a rotating two-axis orthogonal coordinate system, and appropriately control the current components of the two axes of the AC motor.

The mechanical power vehicle system is gradually being replaced by DC brushless motors. Proper control of the current components of the DC brushless motor can achieve similar DC motor control and have the performance comparable to the DC brushless motor.