A Trajectory Controlled 48-to-24 V Resonant Switched Capacitor Converter with 98.7% Efficiency and Ultrafast Dynamic Response

Resonant converters have high power conversion efficiency and can achieve soft switching over a wide range of load conditions. However, during load transients, mismatches between the current provided by the resonant tank and the load current can cause abrupt voltage changes, affecting stability. Maintaining stable output voltage requires a large output capacitance, increasing cost and size. By controlling the trajectory of the resonant tank, rapid recovery after each load transient can be achieved. This work proposes a trajectory control method for a 48- to-24 V resonant switching capacitor converter to improve the transient response performance with a maximum load current of 20 A and output power of 480 W, a 90% reduction in output capacitance for the same output voltage ripple can be achieved with a peak efficiency of 98.7% and a very fast transient recovery of under 300 ns.