一种新颖的Z源逆变器直流链峰值电压控制策略

提出了一种适合于Z源逆变器的直流链峰值电压直接检测与控制方法。Z源逆变器中逆变桥等效输入电压为其直流链峰值电压,控制直流链峰值电压恒定有利于减小功率器件的电压应力,同时给逆变级提供一个相对稳定的工作状态以及简化逆变侧的设计。在分析Z源逆变器直流链电压特性的基础上,给出了直流链峰值电压的直接检测方法,具有实现方案简单、成本低,不存在现有直流链峰值检测方法中的延时以及算法复杂等缺点。通过对检测得到的直流链峰值电压进行控制,在不同的输入电压与负载条件下都能实现直流链峰值电压的恒定。交流输出电压采用了峰值电压控制策略,通过采样输出电压,能实时计算得到输出电压峰值,通过控制峰值电压的恒定能够实现输出电压的稳定。基于所提出的直流链峰值电压与输出电压峰值控制策略,能够同时实现直流链峰值电压和输出电压的稳定,稳态与动态性能良好。实验结果证实了该控制策略的有效性。

New Peak DC-Link Voltage Control Strategy of Z-Source Inverters

A new direct peak DC-link voltage control strategy of Z-source inverter (ZSI) is proposed. For ZSI, the peak DC-link voltage is the actual voltage fed to the inversion stage. Controlling the peak DC-link voltage at the constant level can effectively decrease the voltage stress and simplify the design process of the inversion stage. A direct peak DC-link voltage detection method is developed with a simple sampling circuit, and then controlled directly. Therefore, the constant peak DC-link voltage can be achieved in different input and load conditions. The peak AC output is calculated in real-time by sampling the AC phase voltage, and it is controlled to the desired value without steady-state error. With the proposed direct peak DC-link voltage control and the peak AC output control, both the peak DC-link voltage and AC output are controlled to a desired level under different input and load conditions. Experimental results demonstrate the feasibility of the proposed control strategy.