Dynamic analysis of a modular isolated bidirectional dc-dc converter for high power applications

A new configuration for modular isolated bidirectional dc-dc converters is presented. The proposed converter has interesting features such as fewer switching devices, bidirectional power flow, and low switching losses. The simple modular structure, high frequency operation, zero voltage switching (ZVS) capability, and fewer switching devices make the extended configuration of the proposed converter suitable for high power applications. The operation principle of the proposed converter is analyzed in steady state, and then ZVS analysis of the converter is presented in detail. A generalized averaging technique, which uses dc and first order terms of Fourier's series of state variables, is applied to model the converter. A small-signal average model is developed to obtain the control-to-output transfer function of the converter. In order to obtain acceptable dynamic response, closed-loop control of the converter using a PID controller is studied. Finally, measurement and simulation results are presented to verify the operation principles of the converter and effectiveness of the PID controller.