A low torque ripple direct torque control method for interior permanent magnet motor

This paper proposes a simple method to generate stable voltage commands for permanent magnet synchronous motors to achieve low torque ripple based on space vector modulation direct torque control (SVM-DTC). The relationship between applied voltage and electromagnetic torque is first analyzed and the effect of the voltage and flux linkage on torque ripple is discussed. Then, the new method is developed to reduce torque ripple by giving low-fluctuation voltage commands to the voltage source inverter. The magnitude of the voltage command is calculated by avoiding the effect of flux linkage angle that can be estimated inaccurately during motor operation. Therefore, the fluctuation of the voltage command can be significantly reduced. In order to validate the proposed method, Simulink is first used for simulation and the performance of the proposed method is evaluated. It is found that the torque ripple can be substantially reduced while keeping a low switching frequency and improving system response. Then, a hardware-in-the-loop (HIL) technique is applied to test the developed algorithm that is written into a Texas Instruments microcontroller. This validates the simulation results and the proposed method.