基于双重傅里叶级数的混沌SPWM频谱量化分析

混沌SPWM控制因其可以有效地降低变换器的电磁干扰而得到越来越多的关注,目前对于电磁干扰效果的分析主要以仿真和实验为主,缺乏一种量化的分析方法.本文利用双重傅里叶级数的方法,首先给出了多周期及准随机SPWM的频谱量化表达式,并且针对多周期SPWM进行了频谱计算与仿真的对比验证,然后本文将此计算方法拓展应用到混沌SPWM中,并分析了混沌频谱计算的可行性.为了验证不同映射及不同载波周期波动范围对频谱的影响,文中选择了常用的Tent和Chebyshev映射分别进行了对比实验,实验结果表明,载波周期波动范围对扩频效果具有较大的影响,而且从长期看,混沌序列的分布概率密度会影响扩频的效果,从短期来看,序列的初始值选取也会对扩频效果有较大影响.本文的频谱分析方法对混沌SPWM抑制电磁干扰原理提供了一定的理论基础,而且可以为其工程实践提供设计参考.

Spectrum calculation of chaotic SPWM signals based on double fourier series

Chaotic SPWM control has attracted much interests due to its effectiveness for EMI suppression in power converters. However, most researches focus on the simulation and experiment of power converter under chaotic SPWM control, which is lacking a quantitative method. Based on double Fourier series this paper provides a spectrum calculation method for multi-period SPWM or quasi-random SPWM signals firstly, and the related spectrum calculation and simulation for multi-period SPWM are given to verify the accuracy of the spectrum calculation method; then the calculation method is extended to the spectral analysis of chaotic SPWM signals. To observe the impact on the spectrum of chaotic SPWM signals generated by different mappings and in different variation ranges of carrier period, a spectrum comparison between the Tent and Chebyshev mappings is conducted, in which results indicate that the variation range of the carrier period and the selection of mappings have a great influence on spectrum distribution; in the long term, probability density distribution of chaotic mapping will certainly affect the spectrum, and in the short term the initial value of the mapping will also affect the spread spectrum distribution. In summary, the proposed spectrum calculation method in this paper provides a theoretical foundation for the spread spectrum principle of chaotic SPWM control and for the design reference in practical engineering application.
Keywords：quasi-random SPWMdouble Fourier serieschaotic SPWMspectrum calculation