随机脉冲位置空间矢量PWM的谐波分析

Harmonic Analysis of Random Pulse Position Space Vector PWM

摘要:

随机脉冲位置空间矢量脉宽调制(RPPPWM)打破了传统脉宽调制的对称性，可以减小输出电压和电流脉冲频谱的集簇效应,针对此，在感性主导的三角形负载假设下分析了电流纹波的表达式,以均方值为依据推导了RPPPWM策略下微观(开关周期)和宏观(基波周期)上谐波畸变率(HDF)的理论表达式,其包含3个随机变量的复杂随机函数，数字特征的求解十分困难,因此采用蒙特卡洛方法进行求解，给出了过程并编程计算。以数值解的形式得到了HDF的数字特征函数及HDF最大值和最小值时3个随机变量的取值。从HDF的角度分析了RPPPWM与其他常见的PWM策略间本质的联系与区别，为RPPPWM的应用和进一步研究提供了定性和定量评价的理论依据。

Abstract:

Random pulse position space vector pulse width modulation (RPPPWM) can reduce the cluster effect of the output voltage and current pulse spectrum because RPPPWM destroys the symmetry characteristic of the traditional pulse width modulation. The mathematic formulas for the ripple current are analyzed based on the prominent inductance load with the delta connection. Based on the mean square root value, the harmonic distortion factor (HDF) formulas were deduced through the ripple current on the microscopic level (switching period) and macroscopic level (fundamental period). The theoretical formulas of HDF are random functions with three random variables, and the numerical characteristics are difficult to get. Therefore Monte Carlo method was utilized, and the process was given. Through programming some numerical characteristics were presented, such as the characteristic function, values of the three random variables where the macro HDF reached the limited values. The relationships between RPPPWM and the other PWM strategies were analyzed on the aspect of HDF. The paper provides the qualitative and quantitative assessment on RPPPWM, and the foundation for application and further research.