A Turn-Ratio-Changing Half-Bridge CLLC DC–DC Bidirectional Battery Charger Using a GaN HEMT

Yueh-Tsung Shieh, Chih-Chiang Wu, Shyr-Long Jeng, Ching-Yao Liu, Shiang-Yu Hsieh, Chi-Chun Haung, Wen-Yuh Shieh, Wei-Hua Chieng () and Edward-Yi Chang
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Yueh-Tsung Shieh: Department of Mechanical Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Chih-Chiang Wu: Mechanical and Mechatronics Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan
Shyr-Long Jeng: Department of Mechanical Engineering, Lunghwa University of Science and Technology, Taoyuan City 333326, Taiwan
Ching-Yao Liu: Department of Mechanical Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Shiang-Yu Hsieh: Department of Mechanical Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Chi-Chun Haung: Department of MCU/DSP System Design, ELAN Microelectronics Corporation, Hsinchu 30076, Taiwan
Wen-Yuh Shieh: Department of MCU/DSP System Design, ELAN Microelectronics Corporation, Hsinchu 30076, Taiwan
Wei-Hua Chieng: Department of Mechanical Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Edward-Yi Chang: Department of Material Science and Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan

Energies, 2023, vol. 16, issue 16, 1-28

Abstract: This paper presents a 250 kHz bidirectional battery charger circuit using a GaN HEMT. The charger is subjected to a high-/low-side constant voltage at 200 V/20 V. The charger circuit is a hybrid of the LLC and flyback circuit topologies. Both the power output analysis and efficiency control of this circuit are simplified when the magnetization current is minimized using the low-resistance GaN HEMT. The switching frequency is controlled to match the series resonance in a way that is analogous to conventional LLC circuit controls, while the duty ratio that determines the power output and the dead time, which determines the zero voltage switching, is controlled in an analogous manner to the flyback circuit control. The charging and discharging modes were altered by applying a double-throw relay that changes the transformer turn ratio, which is different from conventional LLC designs using the switching frequency adjustment. A nominal turn ratio with N p = 35 and N s = 3.5 for a 200 V/20 V converter can only produce an internal series resonance with no current flowing in any charging direction. The proposed circuit using a transformer with multiple windings (N p = 35, N s,F = 4, and N s,R = 3) was fabricated to deliver 125 W output power from the power grid battery to the vehicle battery in the forward (charging) mode and 90 W in the reverse (discharging) mode. The conversion efficiency was calculated to be as high as 97% in the forward mode and 95% in the reverse mode. The high conversion efficiency is due to the characteristics of the GaN HEMT, including low resistive and switching losses. The equations derived in this paper associate these losses with the series resonant frequency and power conversion rate, which highlight the advantages of using a GaN HEMT in this CLLC design.

Keywords: half-bridge; CLLC converter; transformer; cascode; GaN HEMT (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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