Selective Noise Suppression in Random SVPWM to Shape the Voltage and Current Spectrum

The conventional space vector pulse width modulation (CSVPWM) is widely used in AC motor powered by two-level three-phase inverter, resulting in sideband noise near the switching frequency and its integer multiples in the motor. Random switching frequency space vector pulse width modulation (RF-SVPWM) and random pulse position space vector pulse width modulation (RP-SVPWM) can spread the voltage spectrum to eliminate sideband noise. However, the sideband electromagnetic force is broadband, and these methods increase the possibility that the motor will resonate at the modal frequency. In this paper, two novel selective noise suppression methods at specific frequency are proposed. The first method is to build the relationship between the pulse position and duty cycle. The simulation results show that a gap in Power Spectrum Density (PSD) at specific frequency can be achieved in the low modulation index. The second method combines RF-SVPWM and RP-SVPWM to build the relationship of the switching frequency, pulse position and duty cycle. And the simulation results show that selective noise suppression at specific frequency can be achieved with the advantage of wide modulation index range. The proposed methods provide a reference to eliminate the electromagnetic noise at the modal frequencies in motors.