一种单相五电平逆变器及其控制策略

A Single-phase Five-level Inverter and Its Control Strategy

针对中点钳位型多电平逆变器直流电压源利用率低、中点电位不平衡等问题,提出了一种两级式单相五电平逆变器。该五电平逆变器的前级可等效为三电平DC/DC变换器,后级通过连接H桥电路实现逆变。该五电平逆变器与中点钳位型三电平逆变器相比,直流电压利用率提高了4倍,同时利用单滞环比较器实现了中点电位平衡,应用载波层叠调制技术、单闭环完成了逆变器的调制与控制。最后搭建模型进行仿真,验证了该五电平逆变器的可行性和正确性。

Aiming at the problems of low utilization rate of the DC voltage source of the midpoint clamped multilevel inverter and unbalanced midpoint potential,a two-level single-phase five-level inverter was proposed.The front stage of the five-level inverter could be equivalent to a three-level DC/DC converter,and the latter stage was connected to an H-bridge circuit to achieve inversion.Compared with the midpoint clamped three-level inverter,the five-level inverter has a 4 times higher DC voltage utilization rate.At the same time,the single hysteresis loop comparator was used to achieve the neutral point potential balance,and the carrier stack modulation technology and single closed loop were used to complete the modulation and control of the inverter.Finally,a model was built for simulation to verify the feasibility and correctness of the five-level inverter.