Double-Phase High-Efficiency, Wide Load Range High- Voltage/Low-Voltage LLC DC/DC Converter for Electric/Hybrid Vehicles

• Published in: IEEE transactions on power electronics Vol. 30; no. 4; pp. 1876 - 1886
• Main Authors: Gang Yang, Dubus, Patrick, Sadarnac, Daniel
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-04-2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Converters; Current distribution; Density; Direct current; Electric power generation; Electric vehicles; Energy efficiency; Engineering Sciences; Hybrid vehicles; Inductance; Magnetic resonance; MOSFET; Multichip modules; Power supply; Prototypes; Resistance; Semiconductors; Switches; Topology; Transformers; efficiency improvement; magnetic components; prototype development; LLC resonant converter; Current sharing; Index Terms—Current sharing
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2014.2328554

In this paper, a 2.5-kW 330-410-V/14-V, 250-kHz dc/dc converter prototype is developed targeted for electric vehicle/hybrid vehicle applications. Benefiting from numerous advantages brought by the LLC resonant topology, this converter is able to perform high efficiency, high power density, and low EMI. To arrange high-output current, this paper proposes a parallel-connected LLC structure with developed novel double-loop control to realize an equal current distribution and an overall efficiency improvement. Considering the LLC cell's dimensioning, this paper establishes a more precise model by taking the secondary leakage inductance into consideration. System amelioration and design considerations of the developed LLC are also presented in this paper. A special transformer is presented, and various types of power losses are quantified to improve its efficiency. This converter also implements synchronous rectification, power semiconductor module, and an air-cooling system. The power conversion performance of this prototype is measured and the developed prototype attains a peak efficiency of 95% and efficiency is higher than 94% from 500 W to 2 kW, with a power density of 1 W/cm 3 . Finally, the EMC results of this prototype are also measured and presented.