具有谐波补偿功能的中频PWM整流器研究

On 400 Hz PWM rectifier with harmonic compensation function

为使中频PWM整流器为系统等效直流负载提供稳定直流电的同时,能够补偿系统中由非线性负载引入的谐波电流,以基于LCL滤波器的3H桥中频PWM整流器为研究对象,首先建立了一相的精确模型,然后采用电压外环PI控制和电流内环PR控制的双环控制策略,并根据LCL滤波器特点,对输入电流的相位偏差进行了精确计算及校正,最终实现了在静止坐标系下对交流输入电流进行任意波形的零静差控制和单位功率因数控制。Matlab仿真和试验结果表明:中频PWM整流器在提供稳定的直流电压的同时能够有效补偿电网谐波电流,且具有良好的动态性能。

Aiming at the problem of compensating the harmonics caused by the non-linear AC loads when supplying steady DC power for the equivalent DC loads, this paper takes the three H-bridges medium-frequency PWM rectifier with LCL filter as an object of study. Firstly, a precise model of one phase is established by adopting the dual-loop control strategy with PI controller in voltage loop and PR controller in current loop. And then, the phase correction angle of input current is calculated considering the character of LCL filter. Consequently, zero steady-state error control of input AC current with free wave, as well as unit power factor control in stationary coordinate system is achieved. The Matlab simulation and experiment results show that the medium-frequency PWM rectifier can effectively compensate the harmonics in grid current while supplying steady DC voltage with satisfactory function in dynamic response.