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在高压大功率场合,传统有源电力滤波器的应用受限于功率器件的耐压与频率。研究一种单相不对称五电平变换器,它能充分利用不同电力电子器件的耐压和工作频率,在保证良好补偿性能的情况下所需电力电子器件和直流母线电源较少;控制策略上,针对该变换器提出基于载波层叠脉宽调制(pulse width modulation,PWM)的新型调制方法,使高压电力电子器件工作在基频,低压电力电子器件工作在高频;采用无需谐波电流检测的双闭环控制策略,并在此基础上引入电压均衡控制方法,可有效均衡直流侧电容电压。最后,搭建控制系统仿真模型,仿真结果表明:在新型调制方法和控制策略下,该五电平有源电力滤波器具有良好的补偿特性,也验证了均压控制方法的正确性。
In the case of high voltage and high power, the application of the traditional active power filter is limited by the withstand voltage and the frequency of the power device. This paper studies a single-phase asymmetric five-level converter, which can make full use of the withstand voltage and operating frequency of different power electronic devices, and requires less power electronics and DC bus power to ensure good compensation performance. The control strategy , A novel modulation method based on carrier pulse width modulation (PWM) is proposed for the converter, so that the high-voltage power electronic device operates at the fundamental frequency and the low-voltage power electronic device operates at the high frequency. The invention adopts the method without harmonic current detection Double closed-loop control strategy, and on the basis of the introduction of voltage balance control method, which can effectively balance the DC side capacitor voltage. Finally, the simulation model of the control system is established. The simulation results show that the five-level active power filter has good compensation characteristics under the new modulation method and control strategy, and also verifies the correctness of the voltage-sharing control method.