A Practical Carrier-Based Discontinuous PWM Method of Vienna Rectifier Considering Neutral-Point Voltage Fluctuation

This paper proposes a practical carrier-based discontinuous PWM (PCB-DPWM) method for Vienna rectifier considering the neutral-point (NP) voltage fluctuation. The operation of the DPWM method induces relatively large fluctuation in the NP voltage compared to the continuous PWM (CPWM) method. For systems with low dc-link capacitance, this fluctuation causes the pole voltage error which severely distorts the phase current. Although the phase current distortion can be mitigated by suppressing the NP voltage through previously proposed methods, it has a disadvantage of leading to increase in switching losses due to reduction in the clamping region of DPWM method. In this paper, the PCB-DPWM method is proposed to reduce the phase current distortion caused by the NP voltage fluctuation. In the proposed method, the pole voltage error is effectively compensated without reduction of the clamping region, by modifying the duty signals with consideration of the NP voltage fluctuation. The effectiveness of the proposed method is verified through simulation results.