Selective Voltage Noise Cancellation in Three-Phase Inverter Using Random SVPWM

This study has focused on the noise elimination at a selected frequency from the line voltage of a two-level three-phase inverter, when it is driven by random space-vector pulse-width modulation. Distribution of noise power in a wide range of frequencies in the conventional random pulse-width modulation (RPWM) methods may cause system resonant frequency excitation. Therefore, it can increase the acoustic noise and vibration in loads of inverters, especially ac motors. Thus, for the effective utilization of RPWM techniques, it is necessary to cancel noise at a specified frequency. The proposed method is able to create a gap in the spectrum of the line voltage at a selective frequency in the human hearing range. Therefore, unlike conventional RPWM techniques, switching periods are determined based on the position of the rotary reference vector. The presented relation between switching periods and the reference vector is used for the conventional space-vector pulse-width modulation (SVPWM) and two-phase SVPWM. The simulation and experimental results confirm that the proposed method effectively creates a gap at the selected frequency in power spectrum density of the line voltage of the three-phase inverter using random SVPWM.