Inverter Harmonic Suppression for Permanent Magnet Synchronous Machine Drives Based on Discontinuous SVPWM With Variable Switching Frequency

Since one phase of discontinuous space vector pulsewidth modulation (DSVPWM) is always clamped, the inverter nonlinearity induces obvious third and sixth harmonics in
dq
-axis currents and voltages. Besides, there are non-negligible spiky switching harmonics in permanent magnet synchronous machine (PMSM) drives of PWM-controlled with fixed switching frequency. To solve these issues, an inverter harmonic suppression strategy for DSVPWM with variable switching frequency is proposed in this article. First, an inverter nonlinearity model including dead time, switching delay, and device voltage drops under DSVPWM is proposed, and a standstill test is presented for the estimation of distorted voltage terms due to inverter nonlinearity. Then the spiky switching harmonics are dispersed by the proposed chaotic DSVPWM based on the Tent map. Finally, the effectiveness of the proposed method is demonstrated on a PMSM platform, which shows quite good performance in the suppression of both low- and high-frequency harmonics. This article reveals that the inverter harmonics under DSVPWM can be easily reduced by distorted voltage compensation and variable switching frequency.