Torque compensation in permanent magnet synchronous motor drives for constant torque, varying flux operation

Current vector control of AC motor drives controls the motor torque at constant flux. However, in some applications e.g. on-line loss minimization control and power factor control it is required to vary the motor flux at constant torque. In these applications vector control is not sufficient since the changes of flux vary the torque. In this paper different torque compensation schemes are discussed and a torque compensation controller is proposed for permanent magnet synchronous motor drives to overcome the effect of flux variation on torque. This provides constant torque, varying flux operation of motor drives. Simulation results confirmed by experimental evaluation prove the validity of the proposed controller.