Integral sliding mode based direct power control of isolated DC-DC converter for improved voltage regulation

This article presents an isolated bidirectional DC-DC dual active bridge (DAB) converter with an integral sliding mode-based direct power control (SM-DPC). Maintaining the dc-link stability and obtaining a robust control for the converter during sudden load change is a significant challenge. The sliding mode control is well known for its robustness, stability, and tracking performance. The sliding surface based on output voltage error is selected, while the proposed method utilizes the equivalent control approach to generate the power reference for the DAB converter. The direct power control provides an easy control method for the DAB converter as the output voltage depends on the transmitted power, governed by the phase shift angle of two H-bridges of the converter. The proposed method enhances the steady-state performance and renders a fast transient response under load change and input voltage variation. Moreover, the method avoids complicated converter modeling and utilizes the voltage dynamic equation and power transfer equation for the controller design. The controller performance and effectiveness are validated with experimental results for a 2-kW DAB converter.