Applying Mode Exchange to High Step-Down Converter to Obtain Wide Input Voltage Range

This paper presents a non-isolated high step-down converter with switching zero voltage switching (ZVS). Compared with the traditional buck converter, in addition to using the duty cycle to determine the voltage gain, the proposed converter also use coupled inductors to achieve relatively high step-down voltage gain. In automotive electronics and telecommunications applications, the input voltage may instantaneously change. As the input voltage increases, the efficiency of the high step-down converter will be decreased. In order to overcome this problem, this paper presents a wide input voltage range for this converter. Based on the input voltage, changing the circuit topology provides a suitable voltage gain and hence obtains a relatively suitable duty cycle. Accordingly, the converter operating under the most load over a wide input voltage range can perform relatively good efficiency. In addition, the leakage inductance energy can be recovered to reduce switch voltage spikes. The protype circuit, with input voltage of 18-54V, output voltage of 2.5V and output current of 10A, is employed to demonstrate the effectiveness of the proposed control strategy.