A SiC Bidirectional LLC On-Board Charger*

2019 IEEE Applied Power Electronics Conference and Exposition (APEC) Pub Date : 2019-03-17 DOI:10.1109/APEC.2019.8722324

Haoran Li, Shengdong Wang, Zhiliang Zhang, Jiacheng Tang, X. Ren, Qianhong Chen

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引用次数: 18

Abstract

The LLC converters are widely used in the unidirectional chargers. However, the reverse LLC voltage gain is lower than unity. The DC-link voltage is then lower than the peak grid voltage so that the buck type DC-AC converters cannot be grid-tied directly, which causes the LLC reverse operation difficult in bidirectional charging applications. This paper proposed a SiC bidirectional LLC on-board charger architecture to achieve high efficiency and high power density. The first stage is an interleaved bridgeless totem pole PFC to achieve unity power factor. The second stage is a 300-kHz LLC taking advantage of wide ZVS range and magnetic integration. Thanks to extra control freedom of high DC-link voltage, the DC-DC voltage gain regulation burden is shared by the DC/AC stage taking advantage of high voltage SiC MOSFETs. An LLC reverse voltage gain compensation control by regulating DC-link voltage is proposed to enable the LLC bidirectional operation. A digital adaptive synchronous rectification driving scheme is proposed based on the LLC primary driver signals. The adaptive SR on-time is modified in every switching control cycle guaranteeing fast transient response and suitable for high frequency applications. A prototype of 6.6 kW SiC bidirectional LLC charger was built and the battery voltage from 240 V to 420 V. The power density is 44 W/in3 with 3 kW /kg and increases 22.2% over the Wolfspeed design. The charging peak efficiency is 95.3% through, and 1.3% higher than the state-of-the-art products. The peak discharging efficiency under 6.6 kW is 95.6%, and 0.6% higher than the state-of-the-art efficiency.

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一种SiC双向LLC车载充电器*

有限责任公司变换器广泛应用于单向充电器中。然而，反向LLC电压增益低于单位。由于直流链路电压低于电网峰值电压，降压型直流-交流变换器不能直接并网，导致双向充电应用中有限责任反向运行困难。为了实现高效率和高功率密度，提出了一种SiC双向LLC车载充电器结构。第一阶段是交错的无桥图腾柱PFC，以实现统一的功率因数。第二阶段是利用宽ZVS范围和磁集成的300 khz LLC。由于高直流链路电压的额外控制自由度，DC-DC电压增益调节负担由DC/AC级利用高压SiC mosfet分担。提出了一种通过调节直流链路电压实现LLC反向电压增益补偿控制的方法，使LLC双向工作。提出了一种基于LLC主驱动信号的数字自适应同步整流驱动方案。在每个开关控制周期中修改自适应SR导通时间，保证快速瞬态响应，适合高频应用。制作了6.6 kW SiC双向LLC充电器样机，电池电压为240 V ~ 420 V。功率密度为44 W/in3，功率密度为3 kW /kg，比Wolfspeed设计提高22.2%。充电峰值效率为95.3%，比同类产品高出1.3%。在6.6 kW下的峰值放电效率为95.6%，比现有效率高出0.6%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2019 IEEE Applied Power Electronics Conference and Exposition (APEC)

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