阶梯充电自平衡开关电容多电平逆变器

Switched capacitor multilevel inverter with step-chargingand self-balancing

针对传统多电平逆变器功率器件多、结构复杂等缺点,将开关电容技术应用于多电平逆变器拓扑,提出一种可扩展的模块化多电平逆变器。所提逆变器通过开关电容模块中的双电容阶梯充电与串联叠加以及模块的串并联转换,能够以较少的器件输出更多的电平,可以降低逆变器输出电压的谐波畸变率。逆变器不需要额外的电压平衡控制或电压平衡回路即可实现电容电压的自平衡,简化了逆变器调制策略,并且单电源输入的特点拓宽了其适用范围。逆变器具有升压能力,进一步简化系统升压环节,降低系统复杂性以及制造成本。文中给出了所提逆变器的拓扑结构、工作原理和调制策略,分析了电容参数,并对提出的逆变器拓扑进行对比研究。最后,在19电平逆变器原型机上进行广泛实验验证,结果与理论分析一致,验证了逆变器的可行性与调制策略的正确性。

Aiming at the disadvantages of traditional multilevel inverters,such as numerous power devices and complex circuit structures,an extended modular multilevel inverter utilizing the switched capacitor technology is proposed.The proposed inverter contains series-parallel conversion of modules,which performs double capacitor step-charging and series stacking in a switched capacitor module.With this structure,the proposed inverter output more levels with fewer devices,and reduced the harmonic distortion rate of the inverter output-voltage.Besides,the proposed inverter eliminated the need for additional voltage balancing control or voltage balancing circuit to achieve self-balancing of the capacitor voltage.Thus,both the structure and the modulation strategy were simplified.Meanwhile,the characteristic of single power input broadened the application scope of the inverter.The inverter has the boosting capability,which further simplifies the system boosting link,and reduces system complexity and manufacturing cost.In addition,the proposed inverter topology,operation principle,modulation strategy,analysis of the capacitor parameter,comparative studies of the related inverter topologies were presented.At last,to verify the proposed inverter,extensive experiments were carried out with the 19-level inverter prototype.Results are consistent with the theory analysis,and prove the feasibility and the correctness of the proposed inverter.