Multiple Winding Linear Transformer for Interleaved Step-up ZVT Converter

Abstract

In this paper, the concept of three winding linear transformer based voltage multiplier cell is derived to generate an interleaved high step-up converter. The switch duty cycle and the transformer turns ratio can be employed as two controllable parameters to increase the voltage ratio flexibly. The power device voltage stress can also be reduced to improve the circuit performance and the active clamp scheme is adopted to recycle the leakage energy, absorb the switch turn-off voltage spikes, and achieve zero-voltage switching (ZVS) operation for all active switches. The linear transformer based voltage multiplier cell is composed of three transformer windings, two voltage multiplier diodes, and two voltage multiplier capacitors. The voltage multiplier capacitors are charged and discharged alternatively to double the voltage gain. Meanwhile, the diode reverse recovery problem is alleviated by the leakage inductance of the built-in transformer. All these factors benefit the circuit performance improvements in the high step-up and large current applications. It can also reduce input current ripple, output voltage ripple and size of passive components. Soft switching technique is used to reduce the switching loss.