Current-mode control to enhance closed-loop performance of asymmetrical half-bridge DC-DC converters

Asymmetrical half-bridge (ASHB) DC-DC converters exhibit fourth-order power stage dynamics. When the conventional voltage-mode control is adapted to ASHB DC-DC converters, fourth-order power stage dynamics impose certain constraints on the voltage feedback compensation design, and the resulting design offers only limited performance for closed-loop controlled converters. It is demonstrated that current-mode control can be adapted to ASHB converters to enhance their closed-loop performance in the presence of fourth-order power stage dynamics. The principles, performance and experimental results of the current-mode control adapted to ASHB converters are presented in comparison with those of the conventional voltage-mode control.