Brushless direct current motor speed control based on soft Switching and sliding mode

Abstract

Brushless DC motor (BLDCM) is basically a multi-parameter non-linear system, and also the ultra-lower inductance of it gives more stringent needs on the performance of the control system, which makes it difficult using the traditional Proportional Integral (PI) control method and the intelligent control methods, like fuzzy control method and neural network control method, to efficiently control a low-inductance BLDCM with high-performance demands. Accordingly, this thesis made 2and#8223; significant contributions. newlineThe first contribution implements a new inverter with passive components (LDC-Inductor Diode and Coupling capacitor) instead of the traditional one for 3-phase BLDCM. A Chopper is employed for controlling the input voltage which is applied to the inverter of BLDCM. The BLDCM uses trapezoidal commutation process. The motor could be controlled by performing soft switching passive loss-less snubber for Pulse Width Modulation (PWM) inverters. This can significantly reduce di/dt amid turn-ON transient as well as dv/dt amid turn-OFF transient to attain Zero-Current (ZC) turn-ON and Zero-Voltage (ZV) turn-OFF. The chief benefit of passive soft switching method is the reduction of spikes on the switching circuit along with very low implementation cost. This new inverter driver topology utilizes lossless passive components that are unique in BLDCM drive. Using PIC (Peripheral Interface Controller) Micro-controller, PWM signals are generated and applied to the gate terminals of the inverter switches. By altering the chopper switchand#8223;s duty ratio, the input voltage to the inverter is changed and thereby achieving the change in speed of the BLDCM. newline