一种无桥PFC变换器的预测电流控制算法

A predictive current control algorithm for a bridgeless PFC converter

针对无桥PFC变换器控制方法中存在控制效果差、动态响应慢等问题,提出了一种新型的预测电流控制算法。该算法首先采集前馈输入电压、输入电流和输出电压等3个控制量,然后将采集到的前馈输入电压送入到电压项,输入电流和输出电压送入电流项,计算出下一个周期输入电流跟踪参考电流所需要的占空比,以对功率因素进行校正。为了验证该控制算法的有效性,对预测电流控制算法及传统平均电流控制算法的控制效果进行了仿真比较,同时,设计并制作了一台实验样机进行实际测试。仿真和实测的结果均表明,预测电流控制算法对输入电流的控制效果好,输入电流能较好且快速地跟踪输入电压,有效提高变换器的功率因数和动态响应速度,减小输入电流的THD值。

Due to the poor control effect and slow dynamic response of the control method based on the bridgeless converter, a new predictive current control algorithm is proposed. The algorithm is implemented by firstly sampling the three parameters, such as： the feedforward input voltage, input current and output voltage, then sending the input voltage to the voltage term and both the input current and the output voltage to current term at the same time so as to calculate out the duty ratio to be needed in order to make the input current track the reference current during the next period, thus realizing the correctness of the power factor. In order to verify the effectiveness of the algorithm, a respective simulation of the predictive current control algorithm and the conventional average current control algorithm is made, and a comparison of the results obtained based on them is performed. A prototype converter is built for practical testing. The simulation and experimental results show that the predictive current control algorithm has the advantages that it has a good control effect to the input current, the input current can track the input voltage well and fast, and the power factor and the dynamic response speed of the converter can be effectively improved and the THD value of the input current can be reduced.