Z-源逆变器直流链升压电路控制器的研究

Study of control strategy for DC-link boost voltage in Z-source inverter

本文提出了一种PID控制器控制Z-源逆变器Z-源网络电容两端的电压,得到较为恒定的直流链电压。基于Z-源网络小信号模型和直通占空比调制信号传递函数的基础上,得到整个环路的开环增益,设计了PID控制器。该控制器具有抑制诸如电源电压波动、负载电流扰动等的功能。同时,由于增加了微分(D)调节,系统的动态性能和稳定裕度都得到了很大程度的改善;能够克服由于Z-源网络电容和直通占空比之间的非线性关系给系统带来的闭环控制器设计困难、系统的动态性能差等缺点,使控制器参数设计非常准确、简单,动态、静态有了明显的提高。通过仿真和实验结果验证了理论分析的正确性。

A PID controller for DC-link boost voltage in Z-source inverter has been presented.With this technique a constant Z-network capacitor voltage can be achieved with an excellent transient performance which enhances the rejection of disturbance,including the input voltage ripple and load current variation,and have good ride-through for voltage-sags.Based on derived transfer function of shoot-through duty cycle-to-Z-network capacitor voltage and simplified modulation strategy,the modulation strategy of Z-network capacitor voltage has been described in detail,which simplified the controller design and improved the transient response.The simulation and experimental results verified the validity of proposed control strategy.