适用于中点箝位型三电平逆变器的多目标调制策略

Multi-objective modulation strategy for neutral point clamped three-level inverter

为同时实现中点箝位型三电平逆变器的中点电压平衡和共模电压降低,分别分析了基于载波脉宽调制(CBPWM)和基于虚拟空间矢量脉宽调制(VSVPWM)的中点电压平衡和共模电压降低方法。基于CBPWM提出一种可以降低共模电压的载波脉宽调制(RCMV_CBPWM)策略,可将大多数工作区域的共模电压限制在直流侧电压的1/6以内。为了实现上述2个目标,同时不过分增加开关损耗,在RCMV_CBPWM基础上提出了一种多目标调制(MOPWM)策略,在全调制度和全负载功率因数范围内,共模电压可限制在直流侧电压的1/6以内并实现中点电压平衡,且其开关损耗低于VSVPWM。比较了MOPWM、RCMV_CBPWM和VSVPWM在中点电压控制、共模电压降低和开关损耗降低方面的性能。实验结果验证了MOPWM的可行性和优越性。

In order to realize the neutral point voltage balance and common mode voltage reduction of the neutral point clamped three-level inverter at the same time,the neutral point voltage balance and common mode voltage reduction methods based on carrier-based pulse width modulation(CBPWM)and virtual space vector pulse width modulation(VSVPWM)are analyzed respectively.A novel modulation strategy,reducing common mode voltage carrier-based pulse width modulation(RCMV_CBPWM),is proposed based on CBPWM,which can limit the common mode voltage of most working areas to one-sixth of the DC side voltage.In order to achieve the above two objectives without excessively increasing the switching loss,a multi-objective pulse width modulation(MOPWM)strategy based on RCMV_CBPWM is proposed.In the range of full modulation and full load power factor,the common mode voltage can be limited to one-sixth of the DC side voltage and the neutral point voltage balance can be achieved,and its switching loss is lower than VSVPWM.The performance of MOPWM,RCMV_CBPWM and VSVPWM in the aspects of neutral point voltage control,common mode voltage reduction and switching loss reduction are compared.Experimental results verify the feasibility and superiority of MOPWM.