复合控制单相直流侧串联型有源电力滤波器

单相直流侧串联型有源电力滤波器由分别工作在高、低频率的全控型功率器件以及二极管构成的混合全桥逆变器组成,串联在整流桥的直流输出端和直流负载之间,只需处理部分功率,可实现降压的功能,是一种新型的单相整流桥谐波治理方案。将平均电流控制应用于直流侧串联型有源电力滤波器的控制将有助于其实现数字控制。文中首先分析了直接应用平均电流控制时控制效果差的原因:由于在低频开关的切换点前后,高频开关的占空比需要实现0、1的跳变,而当采用单一的调制方式时,调制信号不能产生与占空比相对应的波形变化,引起了输入电流的波形畸变。文中提出了一种在不同的工作区间分别采用前沿调制和后沿调制相结合的复合控制策略,避免了对调制信号的突变要求,但可实现占空比的跳变,成功地将平均电流控制应用于单相直流侧串联型有源电力滤波器的控制,可大幅提高输入电流波形质量。实验结果对文中的分析结论和提出的复合控制方式的正确性进行了验证。

Hybrid Control of Single-Phase DC Link Series Active Power Filter

Single-phase DC link series active power filter is a newly developed harmonic correction method for single-phase diode rectifier.The dc link series active power filter is composed of a hybrid full-bridge inverter which includes high-frequency and low-frequency working fully-controlled power devices and power diodes,and is series between the dc terminal of the diode rectifier and the dc load,and also features with the property of voltage stepping-down.Application of average current control to this type of active power filter will be benefit for digital control.The control performance with average current control is evaluated firstly.The results show that the line current waveforms have large distortion at the low-frequency switching points due to large duty-ratio variation requirement between 0 and 1 before and after the low-frequency transition points.In order to overcome this current waveform distortion problem,a hybrid control scheme is proposed in this paper.Leading-edge and trailing-edge modulation are employed in different time intervals,and then the requirement of the fast response speed of modulation signal is relaxed and the control performance is enhanced greatly.Experimental results of the original average current control and the hybrid approach are compared and show good improvement of the line current performance.