Integration of DC-DC Converters for OBC, LDC, and TC in Electric Vehicles

Conventional dc-dc power conversion system for electric vehicles (EVs) needs separate dc-dc converter for each on-board charger (OBC), low-voltage dc-dc converter (LDC), and traction converter (TC). This increases the total number of components, volume, weight, and cost of overall system. To handle this, many studies on integrated system have been conducted. However, they still need additional components and have disadvantages such as limited voltage range operation, unidirectional operation, nonisolated characteristic, and so on. To overcome these limitations, this article proposed the new OBC-LDC-TC integrated dc-dc conversion system (OLTID), which combines the OBC, LDC, and TC together. The proposed OLTID operates in all required modes for each OBC, LDC, and TC. Also, it performs two simultaneous operations by charging the high-voltage battery (HVB) and low-voltage battery (LVB) at the same time and regulating the dc-link voltage to drive the EV when it charges the LVB. As a result, the proposed OLTID can minimize the total number of components and cost, while satisfying all requirements like bidirectional operation, simultaneous operation, wide voltage ranges, and so on. The circuit configuration and operating characteristics of the proposed OLTID are described. Then, its design specifications are analyzed. Finally, its practical effectiveness is verified by experimental tests on the hardware prototype of 1.5 kW.