Dual-Port Inverters With Internal DC–DC Conversion for Adjustable DC-Link Voltage Operation of Electric Vehicles

摘要

Adjustable dc-link voltage operation is an attractive solution to improve the overall efficiency of electric vehicles (EVromans/roman). This article proposes a dual-port inverter (DPI) with an internal dc–dc conversion system for the adjustable dc-link operation of the EVromans/roman. Unlike the conventional two-stage structure, the DPI provides a power flow path from the battery to the inverter directly. Hence, the power processed by the dc–dc converter can be reduced, resulting in higher efficiency and reduced power rating of the dc–dc converter. To fully explore the potential of this inverter in both high-speed and low-speed range, two operation modes with corresponding modulation strategies are investigated. A two-stage modulation strategy is proposed to produce undistorted current even in the presence of unevenly distributed and dynamically changing space vectors in the high-speed mode. Furthermore, the power processed by the dc–dc converter is minimized with the proposed two-stage modulation strategy, and the overall efficiency of the system is further improved. Experimental results with a 1.1-kW permanent-magnet synchronous motor are presented to validate the effectiveness of the proposed method.