Sliding-mode control, dynamic assessment and practical implementation of a bidirectional buck/boost DC-to-DC converter

Bidirectional power converters are frequently applied when interfacing energy-storage devices such as supercapacitors, uninterruptible-power-supply batteries and generators, electric-vehicle motors and renewable-energy-system generators. This paper presents a bidirectional half bridge DC/DC converter, featuring a novel sliding-mode controller, input and output short-circuit protection and a wide input voltage operating range. The ability to achieve step-up or step-down voltage conversion and accommodate a wide input voltage variation makes this design particularly useful for interfacing energy storage devices whose voltage varies widely with state of charge such as supercapacitor modules. The control theory and design methodology are described and converter performance is assessed at realistic operating levels by simulation and experiment. Benefits are shown to include good performance over a wide range of operating conditions and a relatively simple controller-hardware requirement.