基于小信号模型的新型Buck变换器补偿网络设计

Design of a Novel Buck Converter Compensation Network Based on Small Signal Model

对Buck变换器主电路在CCM工作模式下进行动态小信号分析,详细推导其状态方程得出小信号模型.先后设计3种闭环控制补偿网络,即PD,PID和双极点-双零点补偿网络,推导出补偿网络后系统的开环传递函数,由Matlab仿真出补偿网络补偿前后的开环传递函数的伯德图.结果表明,双极点-双零点补偿网络设计后,相角裕度为51.1°,稳态误差为0,在高频段幅频特性的下降频率为-40 d B/dec,获得了更好的稳态和动态性能,能更好地抑制高频干扰,这对研究其他开关电源有着非常好的借鉴作用.

The main circuit of Buck converter is analyzed in CCM mode, and the small signal model is derived in detail. Three kinds of closed-loop control compensation networks have been designed and named PD, PID and the ＂double-pole and double-zero＂ compensation networks. This paper derived the system of the open-loop transfer function after compensation network, and simulated the Bode plot of the open-loop transfer function before and after the compensation network in matlab. The results indicated that the phase margin was 51.5 degrees, the steady-state error was zero, and the down frequency of amplitude-frequency characteristics was -40dB/dec at high frequencies after＂double-pole and double-zero＂ compensation network. The results had better stability and dynamic performance, and better suppress in high frequency interference. The result has a very good reference for further research of other switching power supply.