Carrier-Based Discontinuous PWM Strategy by Switching Clamp Modes for Vienna Rectifier With Unbalanced DC-Links

When the DC-links of Vienna rectifier are unbalanced, there are issues of the distortion in input current and the fluctuation in neutral point (NP) voltage. To solve the above problems, a carried-based discontinuous pulse-width modulation strategy by switching clamp modes is proposed. According to the NP current, the influences of different clamping modes on the NP voltage are analyzed in the presence of unbalanced DC-links. Under the unbalanced degree, the clamping modes are switched to reduce the NP voltage fluctuation. At the same time, the additional switching actions introduced by the clamp modes are reduced by optimizing the switching sequence and carrier. Finally, the effective of the proposed strategy is verified on a Vienna rectifier experimental platform.