A developed PWM Switch model is proposed for bidirectional power flow application. A typical Buck/Boost bidirectional converter is chosen as a test bench for evaluation. Small signal analysis results show that the mode transition between battery charging and discharging modes can be achieved with only Buck main switch controlled. It provides a fast simulation tool to investigate steady and transient responses of converters. The accuracy of the modeling technique is verified by a detailed comparison of simulation results of the developed PWM Switch model and the component circuit.