High-frequency three-phase inverter employing new six-pulse-modulation (SPM) technique for rural electrification/micro-grid/DERs/EVs

This paper proposes a novel six-pulse-modulation (SPM) technique to switch voltage-fed dual front-end full-bridge converters in high-frequency three-phase inverter for rural electrification/islanded micro-grid/distributed energy resources (DER)/electric vehicles (EVs). High frequency pulsed dc voltage is produced by two full-bridge converters, summation of which results in 6-pulse waveform at 6x line frequency. This topology eliminates the need for dc-link capacitor which reduces the size and volume; it also helps in retaining the three-phase 6 pulse information at the input of three-phase inverter. Proposed SPM scheme achieves reduction in switching losses of the inverter devices. At any instant of line cycle, only two out of six switches are required to commutate at high frequency and remaining switches being retained at unique switching state. Moreover, devices are not switched when current through them is at its peak value. Drop in switching loss accounts to be around 21.7% in comparison with a standard voltage source inverter (VSI) switched using sine pulse width modulation (SPWM). Steady-state operation and analysis of the complete inverter system controlled by the proposed SPM along with its implementation has been explained. Complete inverter design has been presented. Analysis and design have been verified by simulation results using PSIM9.0.4 and experimental results on a developed and tested lab prototype of 1 kW have been demonstrated.