Cascaded H-bridge inverter motor drives for hybrid electric vehicle applications

This paper presents the asymmetric cascaded H-bridge multilevel inverter for electric vehicles (EV) and hybrid electric vehicles (HEV) applications. Currently available power inverter systems for HEVs use a DC-DC boost converter to boost the battery voltage for a traditional three-phase inverter. The present HEV drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. Asymmetric cascaded H-bridge multilevel inverter design for EV and HEV applications without the use of inductors to output a boosted AC voltage is proposed in this paper. Traditionally, each H-bridge needs a DC power supply having equal values of DC power sources. The proposed design uses the asymmetric cascaded multilevel inverter using non-equal DC power sources based on specified ratios. A fundamental switching scheme is used to do modulation control and to produce a seven-level phase voltage.