GaN-Based High Power Density Multifunctional Onboard Charger for Electric Vehicles Eliminating Auxiliary Power Module

This article proposes a multifunctional onboard charger (MOC) for electric vehicles (EVs) that facilitates main battery charging (MBC) from a single-phase grid. It can also feed power to single-phase load or back to the grid, and as an auxiliary power module (APM), supplying low-voltage dc (LVDC) power to the vehicle's auxiliary system. The proposed charger is a two-stage converter wherein the first-stage consists of front-end Totem-pole power factor correction (PFC) circuit with an integrated ripple power compensation (RPC) circuit to absorb the second harmonic ripple power. The second-stage is a dual active bride (DAB), used to control the power to/from the main battery. To facilitate the APM mode of operation, the first-stage circuitry is reconfigured to form an interleaved buck converter to supply high current to the LVDC bus. In addition, the dc conversion ratio of DAB is maintained near unity by adjusting the winding configuration of the transformer ensuring soft-switching in all the operating modes. The high dc link voltage requirement of the integrated RPC is addressed by using a novel RPC control methodology, thereby facilitating the use of 650 V GaN switches in the converter. Detailed simulation studies are carried out to predict the performance of the converter for all the modes of operation, and these results are experimentally validated on a 7.2 kW laboratory prototype.