Generalized N-State Random Pulse Position Discontinuous PWM for High-Frequency Harmonics Reduction and Performance Improvement at High Modulation Ratios

In previous studies, generalized N-state random pulse position space vector pulsewidth modulation (GNSRPP-SVPWM) has been verified to significantly disperse dominant high-frequency PWM harmonics with constant sampling frequency. However, due to the short durations of zero-voltage vectors at high modulation ratios, SVPWM with two equally distributed zero-voltage vectors is inferior than discontinuous PWM (DPWM) with one zero-voltage vector in reducing harmonic distortion and switching power losses. Therefore, to significantly disperse dominant high-frequency PWM harmonics, reduce harmonic distortion and improve inverter performance, this article proposed GNSRPP-DPWM, which is more advantageous than other random PWM (RPWM) strategies at high modulation ratios. In addition, by avoiding the switching operations of the phase with higher phase current magnitude, GNSRPP-DPWM further reduces switching power losses. At the same time, GNSRPP-DPWM maintains constant sampling frequency, thus not affecting the closed-loop control system. Mathematical analysis, simulations and experiments all verify the effectiveness and advantages of the proposed GNSRPP-DPWM.