桥侧反馈的LCL型PWM整流器无阻尼控制研究

Research on the Undamped Control of PWM Rectifiers with LCL Filter Using the Bridge Side Currents as Feedback Signals

针对桥侧电流反馈的LCL型PWM整流器由于LCL谐振和数字控制固有延时引起的稳定性问题,建立电流内环数学模型,分析了LCL谐振频率和固有延时对系统稳定性的影响,推导出系统无阻尼稳定的边界条件。通过调整LCL滤波器电容大小,使得LCL谐振频率满足该边界条件就能保证系统无阻尼稳定,减少了系统的设计成本和难度。实验验证了该结论的正确性和可行性。

For the stability problem of bridge side currents feedback PWM rectifiers with LCL filter due to LCL resonance and inherent delay of digital control, the inner current loop mathematical model was set up to analyze the impact of LCL resonant frequency and inherent delay on the system stability, then deduced the boundary condition that damping wasn＇t required. In doing so, the system can be stable without damp by adjust the capacitor size of LCL filter in sure the resonance frequency of LCL satisfy the boundary conditions, reducing the design cost and the difficulty of system. Experimental results demonstrate the feasibility and correctness of the conclusion.