DC Transformer with Series-Connected Power Devices Based on Active Clamp Balancing Circuit

This paper reports a DC transformer (DCT) with series-connected power devices. The series-connected power devices are balanced using an active clamp method. Each power device is paralleled with an active clamping module (ACM), consisting of only one active clamping capacitor and one auxiliary switch (S a ). The voltage of power device is clamped to the clamping capacitor, as long as the clamping capacitor voltages are balanced, the turn-OFF voltages of the main devices can be shared equally. ACM does not affect the normal operation of main device, and only causes minimal loss. Experimental tests under different operating conditions show the effectiveness of the voltage balancing method. With less than 3% voltage imbalance degree, series-connected power devices can achieve both dynamic and static voltage sharing. At 3kV input, the peak efficiency of the prototype can reach 98.4%.