Random PWM Selective Harmonic Elimination Method With Master-Slave Mode for Seven-Level MPUC Inverter

Abstract

A random pulse width modulation (PWM) selective harmonic elimination method with master-slave mode for seven-level modified packed U-cells (MPUC) inverter based on cell division is proposed. In this method, a U-cell in the multilevel MPUC inverter is regarded as a basic cell. And then the multilevel MPUC inverter is regarded as the result of series connection of several basic cells. Firstly, the random pulse width modulation (RPWM) selective harmonic elimination is realized in one basic cell, and the coordinated control among the cells is realized by using the carrier stacking strategy. If the specific harmonic does not appear in the output voltage of each cell, it will not appear in the total voltage after addition. The master-slave mode in RPWM selective harmonic elimination method is proposed in the process of coordinated control of series connected cells. That is, the main cell is mainly used to selectively eliminate specific sub harmonics, and the slave cell is mainly used to control the output of fundamental power, so as to solve the problem that the inverter output level is unnecessary to flip in the traditional method, and reduce the output harmonic distortion.