基于全微分法的Buck变换器建模及控制策略

Modeling and Control Strategy of Buck Converter Based on Total Differential Method

Buck型DC-DC变换器的小信号模型(Small Signal Model,SSM)被广泛用于其分析和控制器设计。为了提高建模精度、改善控制效果,基于状态平均和全微分法建立了一种适用于连续电流模式(Continuous Conduction Mode,CCM)Buck变换器的改进小信号模型(Improved Small Signal Model,ISSM)。建模过程中,考虑寄生参数对电感电流的影响,得到了改进的系统传输函数。分别对SSM、ISSM和电路模型作频谱分析,发现ISSM比SSM具有更高的中低频段精度。分别基于SSM和ISSM模型设计PID控制器,得到了不同的控制参数。仿真结果表明,基于ISSM模型设计的控制器能够消除输出电压过冲,并提升其78%的动态响应速度。

Small Signal Model(SSM)for buck DC-DC converter is widely used for the stability analysis and controller design.In order to improve the modeling accuracy and control performance,this paper proposes an Improved Small Signal Model(ISSM)for buck converter operating in Continuous Conduction Mode(CCM).Based on state space averaging and total differential methods,the transfer functions are improved owing to the consideration of parasitics influences to the inductor current.Spectrum analysis to SSM,ISSM and circuit models prove that ISSM achieves higher accuracy than SSM at low and medium frequencies.Furthermore,the PID controller is designed according to SSM and ISSM,respectively.Simulations prove that the design based on ISSM eliminates the overshoot,while improves the transient response of output voltage by 78%.