面向输出电压波形质量及中点电位动态性能提升的三电平逆变器混合虚拟空间矢量调制策略

Neutral-point potential balance is a prerequisite for the stable operation of a three-level inverter, and the existing neutral-point potential control method based on virtual space vector modulation enhances the dynamic performance of neutral-point potential control, however, it facilitates a degradation in the quality of output AC voltage waveforms during the selection of switching vectors across sectors. To address this issue, this paper proposes a hybrid virtual space vector modulation strategy that selects the corresponding neutral-point potential control mode according to the degree of neutral-point potential offset. When the neutral-point potential offset is small, the vectors are selected in all sectors according to the principle of the “nearest three vectors” to improve the output AC voltage waveform quality, with the neutral-point potential stabilized through closed-loop control. Meanwhile, when the neutral-point potential deviation is large, the small vectors in the sequence are screened, and the action time of the small vectors is increased to ensure that the neutral-point potential control achieves expected response speed. The effectiveness and superiority of the proposed modulation strategy are validated through experiments.