Abstract: Aiming at motor control system performance testing problem, a new motor four quadrant operation dynamic loading approach was proposed, basing on direct torque control. Asynchronous motor under direct torque control model was selected as loading motor. It was connected to testing motor by speed reducer. Loading motor direct torque control instruction was determined by testing motor running condition and load torque features. Loading motor worked at four quadrant operation, providing demanded torque for testing motor. The proposed method was used to permanent magnet synchronous motor speed control system. Simulation result shows the proposed approach can provide dynamic loading demanded torque quickly and exactly. And it can reduce torque ripple influence on dynamic loading induced by direct torque control.

Key words: Dynamic loading, Direct torque control, Four quadrant operation, Asynchronous motor