Torque ripple suppression method with multilevel inverter and feedforward dead-time compensation

This paper discusses the suppression of torque ripples in motor drives. Current ripples caused by pulse-width modulation with frequencies of 10-100 kHz can be reduced by using high-frequency switching. On the other hand, current ripples caused by dead-times with 6kth-order ripples of fundamental frequencies increase with the switching frequency. Therefore, there is a trade-off relationship between the two ripples. To compensate for dead-times, feedforward compensation is widely used. However, effective compensation cannot be achieved if the feedforward compensation values contain modeling errors. This paper therefore reveals that the robustness of the output torque against compensation errors can be improved by using multilevel inverters. The proposed method is validated through simulations and experimental results.