基于混杂系统理论,分析了DC/DC功率变换器在连续工作模式下的动态特性,采用ν步离散法得到一个占空比控制变量与连续变量直接相互作用的数学模型,即分段仿射(PWA)模型。结合预测控制方法,在建立的数学模型基础之上,设定系统的二次型性能指标,并引入预测误差对系统的输出进行反馈校正,通过性能指标的优化计算得到占空比控制信号,由此出设计预测控制器。以Buck功率变换器为研究对象,设计了一个开关频率为400 KHz的实验样机,仿真结果和实验结果验证了该方法的有效性。
DC/DC converter is a typical hybrid system. In this paper, the dynamical characteristic of the DC/DC converter under continuous current mode (CCM) is analyzed by the hybrid system theory. Using the method of νsteps discretization, the PWA (piecewise–affine) model of DC/DC converter, in which the PWM signal and continuous variable interact on each other, is given. Combined with the predictive control method, the linear quadratic performance index is proposed for the design of the controller. Moreover, the feedback signal is introduced to correct the predictive error of the output voltage. Thus, the required PWM signal is optimized by solving the linear quadratic performance index, and the predictive controller is presented. Finally, a 400-kHz switching frequency Buck converter is built with the proposed control strategy, and the simulation and experiment results demonstrate the effectiveness of the algorithm.