Three-port bidirectional CLLC resonant converter based onboard charger for PEV hybrid energy management system

Abstract

In the hybrid energy management systems of plug in electric vehicles (PEVs), a power electronic interface (PEI) is required to interface among the grid side dc link, the onboard battery pack, and the ultra-capacitor (UC) bank. In this paper, an integrated three-port PEI is proposed for use in such applications. The PEI integrates the interleaved bidirectional buck/boost topology with the bidirectional CLLC resonant topology. Due to circuit reuse, the circuit components count is effectively reduced. The interleaved structure offers the benefits of increased power rating and reduced output ripples. The high power density UC bank smooths the current transients of the battery remarkably, which helps to extend the battery lifetime. Moreover, zero voltage switching (ZVS) and zero current switching (ZCS) are achieved among all power MOSFETs and diodes, respectively. A scaled down prototype rated at 1 kW is designed, optimized and tested to charge one 150 V to 250 V battery pack. By hybridizing the pulse-frequency modulation (PFM) and the pulse-width modulation (PWM), the switching frequency range is confined within 60.2 kHz–99.7 kHz. The output voltage/current ripples are well suppressed to meet the battery charging requirements. 96.14% conversion efficiency at rated power and good overall efficiency performance are reported.