基于反馈线性化的Boost PFC控制策略研究

Research on Boost PFC control strategy based on feedback linearization

Boost型功率因数校正(PFC)变换器有多种控制方法。传统的双闭环控制方法具有一定的超调量,有部分非线性控制方法可以改善这一问题,但在负载扰动较大时这类控制方法会产生输入输出调整时间长的弱点。文中针对PI及这些非线性控制策略的缺点,以恒压输出为例进行功率因数校正,采用反馈精确线性化方法建立起Boost变换器的数学模型,通过构造合适的输出变量函数,将传统的Boost非线性控制系统转化成线性控制系统,最后根据经典线性系统控制理论进行控制器设计,并在推导过程中对该控制律的稳定性作了相应的证明。经PSIM仿真结果表明:输入电压电流相位保持一致,波形光滑,负载跳变时,输入电流瞬间调整完成并能实现恒压输出,输出电压除纹波有变化外,直流平均值不受影响,整个系统具有极强的鲁棒特性,同时搭建了一台300 W的实验样机进行验证,获得与仿真同样的结果。

There are many control methods for Boost power factor correction(PFC)converter.A certain overshoot will occur in the application of the traditional double closed⁃loop control methods.It can be improved with some nonlinear control methods.However,when the load disturbance is large,these control methods will show the shortcoming of long input/output adjustment time.In view of the shortcoming of PI and these nonlinear control strategies,PFC is carried out by taking the constant voltage output as an example,the feedback precise linearization method is adopted to establish the mathematical model of boost converter.The traditional boost nonlinear control system is transformed into a linear control system by constructing the appropriate output variable function.The controller is designed according to the classical linear system control theory,and the stability of the control law is proved in the derivation process.The simulation results of PSIM show that,when the input voltage and current phase are consistent,the waveform is smooth and the input current is jump,the input current is adjusted instantaneously and the constant voltage output can be realized;the output voltage has no influence on the DC average value except ripple;the whole system has strong robustness.A experimental prototype with 300 W was built to verify the proposed method.The same results as simulation was obtained.