Spectrum-Dispersion Effects of Random Triangular Carrier Wave SVPWM for NPC Three-Level Inverters

As a modulation technology for low electromagnetic interference, random pulsewidth modulation has been increasingly applied to inverter power supply for three-phase motors. This article proposes a random triangular carrier wave space vector pulse width modulation (RTCW-SVPWM) strategy with dual random parameters, which are subject to a uniform distribution. In this strategy, the shape of the triangular carrier wave changes with random carrier frequency and random pulse center position while the duty cycle of the pulse is the same as that in the conventional SVPWM. 2-D Fourier analysis is used to describe the basic principle of the harmonic dispersion effects in the proposed strategy. The simulation and experimental results show that the dominant harmonics of the output voltage at the integral multiples of the carrier frequency are scattered to their sidebands. Therefore, the prominent harmonic peaks can be greatly attenuated and the harmonics in the high-frequency band are evenly distributed.