PWM Strategy for Current Ripple Minimization in IPM and SynR Machines

The high frequency current ripple in electrical machines is caused by the switching action of voltage source inverters. The ripple has a negative effect on the operation of the machines, resulting in additional copper losses and a high-frequency pulsation of the magnetic field in the air gap. Magnetic flux pulsation is responsible for additional losses in the iron core and the permanent magnets, and can generate torque ripple, mechanical vibrations, and acoustic noise. This paper addresses the minimization of the current ripple generated by a two-level inverter controlled with carrier-based pulse-width modulation in machines with rotor saliency. The simulations show a reduction of the ripple, which is highly dependent on the magnitude of the rotor saliency and the effective position of the voltage vector modulated by the inverter in the d-q plane.