Abstract
The great advance of the power electronics technics brought about a significant improvement for motor control. Especially, induction motors and commutatorless motors driven by current source inverter have many excellent characteristics on steady and dynamic state, and these driving systems are intended for practical use as ideal variable speed motors. The torque pulsation, however, is considerably large and it has bad influence upon the mechanical system. Many studies have been made in order to reduce the torque pulsation. Some intended to improve the current wave forms, others designed to make a multi-phase system. These methods are very useful to improve the torque pulsation, but there are few reports which examined the experimental results of the instantaneous torque.
Generally speaking, the motor driving system forms a high Q torsional resonator and instantaneous torque on the motor shaft contains a large sinusoidal wave component at the resonance frequency. Cosequently, it is very difficult to measure the instantaneous torque generated by the motor. Many measurement methods have been reported, but they are not sufficient for exactness and laborious.
In this paper, the equivalent circuit of the motor driving system is derived and the system is precisely represented as a second-order equation. A new method is proposed, which compensates the torsional oscillation with band rejection filter. It is proved with the experimental results that this measurement method is very useful and accurate.
