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# Buck型变换器的输入电压全补偿前馈控制

Abstract：To improve the dynamic performance of DC/DC converter against input voltage disturbance, and eliminate the low frequency ripple of output voltage, a uniform average equivalent circuit is established for buck series converters under voltage mode PWM control and in continuous conduction mode. According to the invariance principle and the equivalent circuit analysis, fully compensated input voltage feedforward control method and its implementation is presented. The buck series converter using this control method can fully compensate for the input voltage disturbance deviation, and achieve the dynamic invariance of output voltage against the input disturbance. Simulation results verify the correctness of the fully compensated input voltage feedforward control method and its implementation.

Keyword：Average variable, Invariance principle, Feedforward control, Full compensation, Dynamic invariance

1 前言

DC/DC变换器是构建开关电源等许多其他类型电能变换器的核心组成部分。在DC/DC变换器电路中，传统的电压型PWM单环反馈控制系统的动态响应速度较慢，往往无法及时消除输入电压扰动对输出电压的影响。因此，在输入电压波动时，变换器输出电压幅值波动大，存在较大低频纹波。为克服上述缺点，可引入提前按扰动进行补偿的前馈控制[1-7]。

2 Buck型变换器的平均变量等效电路

(1)

vDs(t)=mvin(t) d(t)/n (2)

Buck型变换器无输入电压前馈控制时，输入电压vin(t)与占空比d (t)之间相互独立，vDs(t)随输入电压vin(t)的变化而变化，输入电压vin(t)的扰动直接影响受控源vDs(t)的大小，进而影响变换器输出电压vo(t)。

3 Buck型变换器的输入电压前馈控制原理

vDs(t) =Kvr(t) (3)

(4)