一类新型的混合H桥级联逆变器构成方案

A New Scheme of Hybrid H-bridge Cascaded Inverter

传统的混合H桥级联逆变器构成方案中,直流电压一般均是按照指数或倍数规律分配。随着级联单元数增加,消除电流倒灌、改善输出电压质量这2个指标与降低高压单元开关频率、简化调制策略这2个目标之间的矛盾骤增。为此,该文从提高逆变器的电压和功率等级出发,为在增加级联单元数时平衡上述矛盾,提出一类新型的混合H桥级联逆变器构成方案。该新方案融合了混合级联和混合调制的思想,优化了直流电压分配规律,改进了混合调制策略。在输出电平数相等情况下,虽然新方案与传统方案相比所用的级联单元多,但是在较低的调制难度下,新方案增强了高压单元的扩展性、实现了高压单元工作在基波频率、消除了电流倒灌和保证了输出电压波形质量。通过仿真和实验结果验证所提新方案的正确性和可行性。

In the traditional hybrid H-bridge cascaded inverter schemes, the DC-voltage was generally distributed according to the exponential law or multiple law. As the number of cascaded cells increases, the contradiction between the two indicators: eliminating reverse current and improving the quality of output voltage, and the two targets: reducing the switching frequency of high voltage cells and simplifying the modulation strategies, is sharply aggravated. Therefore, starting from the improvement of the voltage and power level of the inverter, this paper proposed a new scheme of hybrid H-bridge cascaded inverter, aiming to balance the above contradiction when increasing the number of cascaded cells. The new scheme combined the idea of hybrid cascade and hybrid modulation, and optimized the distribution law of DC-voltage and improved the hybrid modulation strategy. When the number of output levels is equal, although the new scheme has more cascaded cells compared with the traditional one, the new scheme enhances the expansibility of high voltage cells, realizes the high voltage cells working at the fundamental frequency, eliminates the reverse current and improves the waveform quality of output voltage under the lower modulation difficulty. Simulation and experimental results verify the correctness and feasibility of the new scheme proposed in this paper.