Sliding Mode Control with Minimum-Deviation Transient Response for Non-Inverting Buck-Boost DC-DC Converters

Recent work has demonstrated that utilization of all possible switching states in non-inverting buck-boost (NIBB) DCDC converters leads to substantial transient response improvements compared to responses in buck-only or boost-only modes of operation. This paper presents a hybrid digital controller for NIBB converters, which utilizes PID control and sliding mode control based the novel control algorithm. The sliding mode controller executes the transient response with an optimal sliding surface achieving the lowest possible output voltage deviation. The implemented digital controller enables seamless transition to PID regulation, which handles standard fixed-frequency steady-state regulation. The proposed solution is verified by circuit simulations and experimental results on a digitally controlled low-voltage NIBB converter suitable for mobile applications.