High power bi-directional DC/DC converter with controlled device stresses

A novel isolated bi-directional dc/dc converter suitable for high-power applications is proposed. The converter uses system parasitics effectively in transferring power. The power output of the converter is controlled by varying the duty ratio and phase-shift angle between the primary and secondary bridges. In the proposed topology, control of the phase-shift angle and duty cycle enables controlled-current stresses in the switching devices over a wide source voltage range. Furthermore, soft switching is available throughout all the switching devices when, so called, a flat-top condition is obtained. This paper presents analytical derivations of the device current and output power equations. Using the equations, the performance of the converter is characterized. Throughout the characterization, it is proven that the total-device rating and power loss are at minimum when a specific condition is obtained. Furthermore, soft switching capability of the switching devices is also analyzed for the control inputs, showing soft switching regions of this topology. Finally, multi kilowatt experimental verification is presented to prove the converter’s operation.