Symmetrical ASL Hybrid DC-DC Converter with Low Voltage Stress

Active switched inductor (ASL) DC-DC converters utilize parallel charging and series discharging of inductors, which improves the voltage gain. In practice, the inductors often have unequal values, leading to variations in instantaneous currents when switching from parallel charging to series discharging. This leads to an increase in voltage stress across the switches of ASL cells. This paper proposes a symmetrical ASL hybrid DC-DC converter, providing a current path of the inductor currents when circuit configuration changes from parallel charging and series discharging of inductors, lowering the voltage stress. The operating principle, design equation, and device stress are analyzed. Finally, a laboratory prototype (22/308V) generating 430W is developed and tested to validate the analytical analysis.