Torque Ripple Reduction Using Variable DC-link Voltage Technique for Permanent Magnet Synchronous Motor in Battery Electric Vehicle

A new torque ripple reduction strategy is presented for permanent magnet synchronous motors in electric vehicle applications. Within the control scheme, the dc-link voltage of the traction inverter is modified to produce a counteracting power against the torque pulsation. A cascaded multilevel inverter is built to generate the variable dc-link voltage. The suggested technique can reduce the torque ripple resulting from the interaction of the current MMF with the nonsinusoidal back-EMF. Simulation results confirm that adding suitable 6th-order voltage to the dc-link reduces the 6th-order component of the torque ripple. In the experiments, the stator current is observed. The injected 6th-order voltage effectively eliminates the 5th- and 7th-order current harmonics.