This paper proposes a three-port bidirectional dc-dc converter with an interleaved parallel boost port for electric vehicle’s power distribution network. The boost port benefits low current ripple, voltage matching for ZVS and low transformer turns ratio. With all control degrees of freedom involved and considering the energy stored in MOSFET’s parasitic capacitance, inductor currents, transmission power and ZVS boundaries are mathematically and accurately expressed through frequency-domain analysis, which can be directly used for further system optimization. The proposed model is verified via computer simulation results.