Harmonic Analysis of Random Pulse Position Space Vector PWM

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.