级联多电平逆变器的频谱分析及滤波器设计

为解决级联多电平技术过大的电压变化率和相对集中的高次谐波的问题,通过计算机仿真技术,深入比较了几种典型拓扑结构的逆变器输出电压谐波的频谱,分析了基于载波组SPWM调制技术的级联多电平逆变器输出电压的谐波特征后,针对该结构电压谐波的特点,提出一种级联多电平逆变器的LC滤波器设计方法并给出了电抗参数和电容参数的具体设计原则和方法。该方法综合考虑了滤波器频率特性和功率因数等要素,通过仿真实验证明,通过该方法选择的滤波器参数满足系统各方面的要求,达到预期的滤波效果,对于不同功率因数的负载,均有很好的滤波效果,并提高了系统的功率因数。

Frequency Spectrum Analysis and Filter Design of Cascade Multi-level Inverter

The technology based on the cascade multi-level inverter has been widely applied in the large-power and high-voltage energy control areas. But this kind of inverter have some disadvantages such as the transient increase or decline of the output voltage and the relatively concentrated high harmonics. In this paper, different typical topological structure of the cascade multi-level inverters is deeply investigated and analyzed through computer simulations, and a comparison of the different frequency spectrums is maked. The cascade multi-level inverter based on the Carrier Group SPWM technology and the output voltage harmonic characteristics is analyzed. In order to solve the problem of the harmonics, A kind of method in designing the LC filter for the cascade multi-level inverter is improved which based on the voltage harmonic characteristics, and the principles and methods in calculating the reactance and capacitive parameters is brought forward. This kind of method takes the elements of the filter frequency characteristics and the system power factor into consideration. The simulation results proves that the filter parameters which chosen by this method can meet the various requirements of the system . The desired effect of filtering is achieved. For the different power factor loads, this filter have the ability to get an ideal filtering effect and to improve the system's power factor.