Power Control of a Bi-Directional DC-DC Converter used for Fuel-Cell Hybrid Electric Vehicles (FCHEVs)

This paper presents a bi-directional DC/DC converter used in hybrid electric vehicles. The converter operates as a full-bridge converter when the power transferred from the traction battery to the supercapacitor and performs as a pushpull converter when the power flow is in opposite direction. A new multi-structure control approach has been proposed, which is able to robustly control the converter in both power flow directions. The control structure can provide a very efficient power conversion between the two buses by controlling the phaseshift of the full-bridge converter in one direction and the dutyratio of the push-pull converter in the other power flow direction. Simulation results and experimental results demonstrate the superior performance of the proposed control system.