具有开关电容的隔离型交错并联Boost变换器

提出一种具有开关电容的隔离型交错并联Boost变换器。由于开关电容的存在，此变换器的变压器可交替工作在反激与正激模态，从而将部分输出能量存储在开关电容中，因此，这种变换器的功率等级有了一定提高，磁芯的体积可有效减小。开关电容内在的倍压能力提高了电路的电压增益，因此降低了变压器的匝比和副边二极管的电压应力。开关电容的充放电平衡使得输出各相之间的电流自动均衡。开关管的非对称连接方式，使得并联运行的2个支路只需要一个有源钳位电路就可吸收2个变压器原边的漏感能量，因此，主开关管和钳位管都实现了零电压开通和零电压关断。由于二极管的电流下降率受到变压器漏感的限制，因此反向恢复问题得到抑制。一台1 kW 48 V/380 V的实验样机的实验结果验证了理论分析的有效性。

Interleaved and Isolated Boost Converters With Switched Capacitors

An interleaved and isolated boost converter with switched capacitors was presented. The switched capacitors were used to realize the inherent voltage-lift function which increases the voltage gain and the power level of the converter. Due to the extended voltage gain, the turns ratio of the transformers could be reduced and the voltage stresses of the diodes were alleviated. Because of the transformers operating in fly-back and forward modes alternately which made part of the output energy stored in the switched capacitors, the size of magnetic components could be reduced. Moreover, the load current could be auto-shared by each phase according to capacitor charge balance. Only one active clamp circuit was needed for the interleaved two phases to recycle the leakage energy and absorb the voltage spikes caused by the leakage inductance, which reduces the circuit complexity. Both the main and the clamp switches are in ZVT operation during the whole switching transition, therefore, the switching losses could be reduced. Since the clamping and output diode turn-off current falling rate was controlled by the leakage inductance, the diode reverse-recovery problem was alleviated. The experimental results based on a 1kW 48V to 380V DC/DC prototype verify the effectiveness of the theoretical analysis.