基于平均电流控制的Buck变换器建模和仿真

Model Building of Average Current Model Control and Simulink for DC-DC Buck Converter

电压控制模式的DC/DC变换器只有输出电压一个反馈量,工况(电压或负载)变化导致输出电压变化时,控制器才会自动调整,稳定性差且响应速度慢.平均电流控制是提高DC/DC变换器稳定性和动态调节性能的有效方法.本文采用状态空间平均法,建立Buck型DC/DC变换器在电流连续模式下的交流小信号模型,求出该变换器的电流和电压控制环的开环和闭环传输函数,分析其稳定性和动态特性.用matlab软件仿真,结果表明理论模型正确,并确定电流和电压控制器校正装置的关键参数.

Because of the only feedback quantity, output voltage in voltage control mode DC/DC converter, the controller can automatically adjust when the changes in working conditions （voltage or load） result in output voltage change, which has poor stability and slow response. Average current control mode is an effective way to improve dynamic adjustment performance and stability of buck converter. Using the state space average method, this paper builds AC small signal model of the DC/DC buck converter in continuous current mode, obtains open and closed loop transfer functions in this converter having voltage control loop and current control loop, and analyzes its stability and dynamic characteristics. Using Matlab, the results show that the theoretical model is correct, and the key component value of correcting circuits in the current and voltage controller are determined.