三电平交流斩波电路及其浮动电容电压控制策略的研究

Research on a Novel Three-Level AC Chopper and Voltage Controlling Method of the Flying-Capacitor

提出一种用于高压电能变换的新型三电平交流斩波电路,该电路允许使用低电压等级的器件完成高压电能变换,并采用较多的电平数去逼近所希望的波形,使输出电压或电流的质量大大提高,谐波含量减少.在斩波电路的工作过程中,稳定的浮动电容电压是非常重要的.三电平交流斩波电路的中间电平对应着两个工作模式.它们虽然产生同样的电平,但对于浮动电容来讲,充、放电的情况正好相反.利用这一特性分析了浮动电容电压的可控性,提出了滞环比较方法控制浮动电容电压,并通过实验验证了电路的工作原理.

A novel three-level AC chopper is proposed, which is a new multi-level converter applied to high voltage conversion, and utilizes more electric levels to form output voltage and decrease the harmonic content of output waveform. A stable flying capacitor voltage must be maintained to facilitate the operation of the chopper. When the circuit is working, there are two switching modes corresponding to the same voltage level, but the current direction in flying-capacitor is opposite, so the voltage of flying capacitor can be controlled by the ratio of the two different modes with the same voltage level. The detail control method of flying-capacitor voltage is discussed. Experiments were carried out to confirm its working principle.