逆变器并联系统死区的环流效应及其抑制方法

针对大功率逆变器易发生的因死区效应引起的并联系统谐波环流问题,提出一种结合谐波电导法的恒定参考电流控制策略,以含LCL型滤波器的逆变器为例,建立其输出阻抗模型,将逆变器死区效应带来的偏差电压影响视为一种同时包含基波和谐波分量的控制扰动量,分析多逆变器并联系统的环流产生机理并给出影响逆变器环流产生的两大因素,引入谐波电导为逆变器谐波电流提供一条回路,同时采用恒定参考电流控制策略来达到抑制谐波环流的目的。最后,在PSIM 9.0平台上搭建仿真模型并进行相关试验共同验证了所提控制策略的可行性。

Circulating Current Caused by Dead-zone Effect in Parallel Inverters and Its Suppression Method

Aiming at the harmonic circulating current problem easily caused by dead-zone effect of high-power inverter in parallel system, a constant reference current control strategy combined with harmonic conductance was put forward. Taking the inverter with the LCL filter as the research object, its output impedance model was built. Meanwhile, the impact of offset voltage caused by inverter dead-zone effect was regarded as a perturbation control containing both the fundamental and harmonic components. And then the circulating current generating mechanism of multi-inverter parallel system was analyzed and two factors about affecting the circulating current generation were given. This paper proposed the introduction of harmonic conductance which provided a circuit for the inverter harmonic current, and adopted a constant reference current control strategy to achieve the purpose of suppressing harmonic circulating current. Finally, building simulation model on the PSIM9.0 platform and doing the related experiments jointly verified the feasibility of the proposed control strategy.