Conventional electric servo drive systems suffer from high common-mode voltage (CMV) due to the use of zero vectors in Space Vector Pulse Width Modulation (SVPWM). To mitigate this issue, this paper proposes an inverted SVPWM (I-SVPWM) strategy. By simply inverting the switching actions of a specific phase, this strategy avoids the use of zero vectors and achieves an effect similar to Active Zero-State PWM (AZSPWM), thereby effectively suppressing common-mode voltage. Compared with AZSPWM, the proposed method eliminates the need to recalculate vector action times or design new switching sequences. It can be seamlessly implemented by applying a straightforward inversion logic to the switching signals of one phase based on conventional SVPWM, which significantly enhances its practical convenience. Furthermore, similar to AZSPWM, the elimination of zero vectors in I-SVPWM leads to an increase in harmonic peaks in the output voltage and current compared to conventional SVPWM. To address this, an Alternating Inverted SVPWM (AI-SVPWM) strategy is introduced. Since the sequence of vector actions differs in each cycle, the high and low levels of the line voltage shift locally within each switching period. This causes the reconstruction of harmonic and even fundamental components in the output waveform, thereby reducing harmonic peaks at even multiples of the switching frequency. Simulations of SVPWM, AZSPWM1, AZSPWM3, I-SVPWM, and AI-SVPWM are conducted in MATLAB/Simulink. The results confirm that the proposed strategies effectively reduce common-mode voltage. Although AI-SVPWM achieves a lower harmonic amplitude compared to I-SVPWM, conventional SVPWM still maintains superior steady-state performance.
Zhang et al. (Wed,) studied this question.