Research on Subsection Synchronization Harmonic Optimum Pulsewidth Modulation for Inverters

This paper presents the synchronous harmonic optimum pulsewidth modulation (SHOPWM) for three level diode clamped inverter. First, the problem of minimizing stator current harmonics when the asynchronous machine is fed by PWM inverter is introduced. A distortion factor in proportion to the total stator current harmonic distortion is selected for solving the problem. A subsection synchronization modulation method is then proposed according to the change of fundamental stator frequency and inverter output voltage. With the help of Matlab optimization toolbox, the genetic algorithm (GA) is used first to generate feasible initial values. Calculation of SHOPWM switching angles is done by the gradient method then. Finally, the proposed method is realized with TMS320F28335 digital signal processor (DSP) and line voltage spectrums of each subsection are given for verification.