Generating torque analysis and measurement by space rotating current vector during self-controlled synchronous motor starting

Generating torque in starting of self-controlled synchronous motor is analyzed, and the developed method of torque measurement using the space rotating current vector is described. A self-controlled synchronous motor known as a commutatorless dc motor, consists of a synchronous motor with a shaft position sensor and a inverter switched by the pulses from the position sensor. The inverter frequency is the functions of the motor speed, and in lower speed range during the synchronous motor starting period, the low frequency current leads to a rectangular waveform. Then, the current waveform produces torque pulsation. In this case, an analysis of the starting characteristics of the commutation of the inverter is presented, and the measurement results of the generating torque and shaft torque are shown.