The control principle of the brushless DC motor, to make the motor rotate, the control part must first according to the position of the motor rotor sensed by the hall-sensor, and then decide to turn on (or turn off) the inverter's intermediate power according to the stator winding. The order of the transistors, AH, BH, CH (these are called upper arm power transistors) and AL, BL, CL (these are called lower arm power transistors) in the inverter, make the current flow through the motor coils in order to produce a forward (or reverse) ) The rotating magnetic field interacts with the magnets of the rotor, so that the motor can rotate clockwise/counterclockwise. When the motor rotor rotates to the position where the hall-sensor senses another set of signals, the control unit turns on the next set of power transistors, so that the circulating motor can continue to rotate in the same direction until the control unit decides to stop the motor rotor and turn off the power Transistor (or only turn on the lower arm power transistor); if the motor rotor is reversed, the power transistor turns on in the reverse order.
Basically, the opening method of power transistor can be exemplified as follows: AH, BL group → AH, CL group → BH, CL group → BH, AL group → CH, AL group → CH, BL group, but never Open into AH, AL or BH, BL or CH, CL. In addition, because electronic parts always have the response time of the switch, the response time of the parts should be taken into account when the power transistor is turned off and on. Otherwise, when the upper arm (or lower arm) is not completely closed, the lower arm (or upper arm) is already Turning on, as a result, the upper and lower arms are short-circuited and the power transistor is burned out.