brushless dc motor control principle, a lot of people say brushless motor controller with a brush motor controller has a different, indeed, cancel the physical carbon brush, brushless motor controller, a brush motor controller is improved quick wear of carbon brush, and carbon brush friction noise and high speed spark of a problem. But since there is no physical module of carbon brush this turn, so the brushless motor controller to change to digital signal control, to join the brushless drive to control has become a necessary condition. Brushless dc drives, including power supply module and control module: power supply module provides three-phase power supply to power a brushless motor controller, the control module according to the input signal power frequency. Power supply module can be directly to dc input (Normally for 12 v / 24 v / 48 v)Or in an alternating current input (220 V)Will have to the first, if the input is an alternating current into dc converter. Both input dc or ac input coil to turn to motor controller must be before the dc voltage by the inverter into three phase voltage to drive the motor controller. Control module provides PWM (Pulse width modulation)Motor controller and power converter commutation time. Generally want to use the brushless dc motor controller in the speed can be stable in value when the load changes will not change speed control, so the brushless motor controller with can induced magnetic field sensor (Generally for hall sensor)As speed closed loop control, and at the same time as the basis of phase sequence control. But that is only used for speed control and not as a positioning control. Positioning control and servo motor controller need to add the encoder. Most of the brushless motor controller and the servo motor controller is same closed-loop structure. To make the brushless motor controller turn, first of all control modules must be according to the sensor sensing the position of the rotor current brushless motor controller, and then according to the stator winding decided to open (Or close)Inverter power transistor in order, AH, BH, CH in the inverter (These are called upper arm power transistor)And AL, BL, CL (These are called lower arm power transistor), made the current flowing through the motor controller in a sequence coil generates positive (Or reverse)A rotating magnetic field, and interact with the rotor magnet, so can make the motor controller is/reverse rotation. When the rotor rotating motor controller to the position of the sensor sensing out another set of signals, the control module to open again the next set of power transistor, so cycle, brushless motor controller could keep rotating until the control module in the same direction decided to brushless motor controller to stop the close power transistor (Or just open the arm power transistor); Brushless motor controller to open the power transistor reverse turn order instead.
