An Isolated Three-Port Bidirectional DC-DC Converter With Decoupled Power Flow Management

TLDR

The converter’s topology and control are relevant to multi‑voltage systems in hybrid electric vehicles and renewable energy generation. The paper proposes an isolated three‑port bidirectional DC‑DC converter with phase‑shift and duty‑cycle control to optimize power flow and minimize losses. A control‑oriented model, Bode‑plot analysis, and a decoupled power‑flow strategy were developed to achieve fast dynamic response. A 1.5 kW prototype was built, confirming the theoretical analysis.

Abstract

An isolated three-port bidirectional dc-dc converter composed of three full-bridge cells and a high-frequency transformer is proposed in this paper. Besides the phase shift control managing the power flow between the ports, utilization of the duty cycle control for optimizing the system behavior is discussed and the control laws ensuring the minimum overall system losses are studied. Furthermore, the dynamic analysis and associated control design are presented. A control-oriented converter model is developed and the Bode plots of the control-output transfer functions are given. A control strategy with the decoupled power flow management is implemented to obtain fast dynamic response. Finally, a 1.5 kW prototype has been built to verify all theoretical considerations. The proposed topology and control is particularly relevant to multiple voltage electrical systems in hybrid electric vehicles and renewable energy generation systems.