EXTENDED SPEED RANGE OPERATION OF PERMANENT MAGNET BRUSHLESS MACHINES USING OPTIMAL PHASE ANGLE CONTROL IN THE VOLTAGE MODE OPERATION

摘要

A system for controlling the torque of a sinusoidally excited permanent magnet motor (12). The system includes a rotor position encoder (14), speed measuring circuit (16), controller (18), power circuit (20) and power source (22). The position and speed signals (24, 26) and a torque command signal (28) are applied to the controller (18). The torque command signal (28) is indicative of the desired motor torque. The controller (18) determines a voltage amplitude (30) required to develop the desired torque by using the position, speed, and torque command signals (24, 26, 28) and other fixed motor parameter values. The controller (18) transforms the voltage amplitude signal (30) into three phase signals by determining phase voltage command signals (Va, V?b?, V?c?) from the voltage amplitude signal (30) and the position signal (24). Motor voltage command signals (32) of the controller (18) are applied to a power inverter (23) that is coupled with a power source (22) to apply phase voltages (34) to the stator windings of the motor in response to the motor voltage command signals (32). Whereby the power circuit can achieve required torque levels with lower currents for power switches.