轻载条件下单相Vienna整流器的简化前馈控制

A Simplified Feedforward Control for Single-phase Vienna Rectifier Under Extremely Light-load Condition

单相Vienna整流器轻载或者空载工作时,很容易触发输出电压过压保护。传统上,采用间歇控制的方法,在输出电压超过设定_阈值时,关闭驱动一段时间迫使电压下降。但这种控制方法会导致输出电压大范围波动。前馈控制方法通过计'算轻载或空载时的占空比并叠加到调制波中,可以有效地稳定输出电压。然而,断续导通模式(DCM)下的前馈表达式非常复杂,难以使用数字控制器如数字信号处理器(DSP)来实现。因此,此处提出了一种简化的前馈控制方法,使得DCM下的前馈表达式更易实现。详细分析了简化算法,并在此基础上搭建实验样机,对算法的正确性和有效性进行了验证。

It is difficult to run single-phase Vienna rectifier under light or no-load conditions since the converter is easily triggered for overvoltage protection.The conventional burst-mode control can solve this problem,but it leads to a large voltage fluctuation.The feedforward control is a more effective method to stabilize the voltage because the duty ratio required for light or no-load conditions is calculated and superimposed on the regulator.Nevertheless,the feedforward expression in discontinuous conduction mode(DCM) is complex and difficult to be implemented by the digital controller,such as digital signal processor(DSP).A simplified feedforward control which makes the DCM feedforward more easily implemented is proposed.The algorithm is analyzed and experimental results are presented to verify the effectiveness of the control.