New Integrated DC-DC Conversion System for Electric Vehicles

This article proposes a new integrated dc-dc conversion system (IDCS) with dual-output phase-shift control for electric vehicles (EVs). The conventional dc-dc conversion system for EVs requires each dc-dc converter for on-board charger (OBC), traction converter (TC), and low-voltage dc-dc converter (LDC). It leads to the increase in the number of total components, overall volume, weight, and cost. Therefore, many studies on integrated power converter have been made to solve these problems. Nevertheless, they still need additional components and have drawbacks, such as high-voltage stress, nonisolation characteristics, and hard switching. To overcome these limitations, the new IDCS, which integrates the dc-dc converters of OBC, TC, and LDC at once is proposed. The proposed IDCS performs all functions of each dc-dc converter of OBC, LDC, and TC, while effectively reducing the total number of components and cost. In particular, it performs two simultaneous operations. One is to charge both the high-voltage battery and low-voltage battery (LVB) at the same time, and the other is to regulate the dc-link voltage, while charging the LVB. Moreover, the proposed IDCS increases the overall efficiency by synchronous rectification control. The featured characteristic and operational principles of proposed IDCS are first explained. Then, its design specifications are carefully investigated. Finally, the practical effectiveness is verified by experimental tests on the hardware prototype of 1.5 kW.