This article presents the feasibility of a flyback charger for electric vehicles (EV) based on silicon-carbide (SiC) devices. The flyback topology is simplest, but its device voltage stresses are strongly affected by the transformer leakage inductance. To reduce the device voltage stresses by recovering the energy stored in the transformer leakage inductance, an active-clamp circuit and active snubber circuit are adopted in both sides of the transformer. Also, the active-clamp circuit helps to reduce the switching losses by making zero-voltage-switching (ZVS) condition. By deriving the loss equations of switching devices and transformer as a function of the switching frequency and magnetic flux swing, design optimization considering loss and volume is attempted. The snubber capacity and diode voltage stress are quantitatively suggested through the analysis of the power absorbed by the active snubber. Based on the analysis, a 3.3 kW/100 kHz prototype is designed and experimented to show the feasibility. Test results demonstrate 96.7% peak efficiency and 96.4% full load efficiency at 330V output voltage.

中文翻译：

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基于带有源缓冲器的反激式转换器的 3.3 kW/100 kHz EV 充电器的设计


本文介绍了基于碳化硅 (SiC) 器件的电动汽车 (EV) 反激式充电器的可行性。反激式拓扑最简单，但其器件电压应力受到变压器漏感的强烈影响。为了通过恢复变压器漏感中存储的能量来降低器件电压应力，在变压器两侧采用有源钳位电路和有源缓冲电路。此外，有源钳位电路通过形成零电压开关 (ZVS) 条件有助于降低开关损耗。通过推导开关器件和变压器的损耗方程作为开关频率和磁通量摆幅的函数，尝试考虑损耗和体积的设计优化。通过分析有源缓冲器吸收的功率，定量地建议缓冲器容量和二极管电压应力。基于分析，设计并实验了3.3 kW/100 kHz样机，验证了可行性。测试结果表明，在 330V 输出电压下，峰值效率为 96.7%，满载效率为 96.4%。