A fast-recovery buck converter with differential current control and ripple suppression for energy constrained applications

Abstract

Fast transient response and precise load regulation are critical in renewable energy systems, particularly in low-voltage control units driven by erratic sources like solar or wind. While traditional current-mode control (CMC) in buck converters enables fast dynamic response to load and input variations, but suffers from subharmonic oscillations due to limited duty cycle information and slow inner-loop dynamics. Although the capacitor current control can mitigate this issue, it compromises impedance matching and system stability. To address these challenges,this paper proposes a differential current dynamic on-time (DCDOT) control scheme for buck converter, providing enhanced transient performance and improved stability without requiring direct capacitor current sensing. The differential current is derived as the difference between the inductor current and load current, enabling precise transient behavior with reduced sensing complexity. A fixed-frequency switching mechanism is implemented through a dedicated control loop that stabilizes the on-time duration, maintaining a constant switching frequency of 500 kHz. Ramp compensation is incorporated to suppress output ripple and prevent instability. The system is modeled and validated using MATLAB Simulink. Experimental results show significant performance improvements, achieving a transient recovery time of $0.45\mu s$ for a 0.01 A to 1 A load step and $0.3\mu s$ for the reverse transition.