GA optimized SHE PWM hybrid cascaded H-bridge multilevel inverter with capacitor voltage balancing

Abstract

Multilevel inverters are high voltage, high power devices with wide electrical applications due to their lower output harmonic component and device stress management capabilities. Manifold control strategies have been proposed and implemented for MLIs and fundamental frequency switching strategies are especially suited due to their ability to provide for higher efficiency. This paper proposes a hybrid cascaded multilevel inverter (HCMLI) using selective harmonic elimination pulse width modulation (SHE-PWM) that produces an eleven-level output voltage with two dc sources and a pre-charged capacitor using twelve switches, instead of conventional twenty switches and five dc sources. Genetic algorithm (GA) has been implemented to compute switching angles of the HCMLI in this work.GA optimized SHE-PWM technique is implemented in closed loop with switching logic enabling capacitor charge balancing embedded. A capacitor voltage averaging scheme to reduce the steady state voltage error of capacitor voltage is presented and the benefits for the same are analyzed and discussed in the simulation results. The control of HCMLI has been experimentally validated using 0.5-kW laboratory prototype and related experimental results are provided in this paper. © 2017 IEEE.