An Universal On-board Battery Charger with Wide Output Voltage Range for Electric Transportation

Battery operated electric vehicles (EVs) and plug-in-hybrid electric vehicles (PHEVs), contains an inherent on-board charger (OBC) to resolve the mileage anxiety and provide instant charge with available normal household power sockets. Conventionally, a two-stage converter is used in OBC that connects the input grid supply and battery pack whose output voltage levels differ from vehicle architecture. Typically, OBCs are available in voltage range of 200-450, 48-72 and 96-150 V. This paper mainly focus on the analysis and design of a novel universal battery charger with a voltage range of 50-500 V, suitable for automotive application. A control structure to attain the variable DC link in power factor correction stage (PFC) is presented here. Moreover, the design of high frequency (HF) transformer is highlighted with JMAG simulations. Isolated DC-DC converter along with the design considerations and implemented control algorithms is also presented in paper. An experimental set-up for 1 kW prototype of the proposed converter along with the results are presented in this paper. A high efficient universal charger, which can address the wide range of battery pack voltages, is most suitable for charging all range of vehicles.

I. Introduction

Electric vehicles (EVs) and Plug-in hybrid electric vehicles (PHEVs) have emerged as a promising technology these days in automotive industry. Carbon emissions from combustion vehicles into the environment provoked the automotive sector to focus more to ecofriendly vehicles. Battery as the main energy source and with electric power train, these vehicles exhibit a smooth operation with tremendous performance [1]–[2]. The energy in EVs can be easily charged using battery chargers. These accepts the input AC grid supply and converts to DC to charge the battery packs. However, the charge time depends on the available input supply and the ratings of battery packs. Fast charging (FC) systems provide interim solutions for the quick refill of the energy in the battery packs [3]. However, due to lack of FC infrastructures, on-board battery chargers (OBCs) are more preferable these days [4]. A two-stage layout is in build in these converters. The first stage represents to maintain high input power quality and the second stage represents the DC-DC converter to charge the battery packs. As per SAE J1772 [5], isolation is not a mandatory requirement but all the chargers are in built with this feature in the second stage. The typical rating of OBC available in the market are in range of 36—72, 72—150 and 200—450 V [6]–[7]. In these OBC, a front end rectifier with boost configuration is commonly used to maintain high input power quality. A review on existing PFC topologies with boost configuration is highlighted [8]–[9]. However, the boost configuration operates more efficiently only for an output voltage greater than peak of input voltage. For this reason, a standard PFC voltage of above 380 V is typically maintained with boost configured topologies. This restricts the output of OBCs to a limited voltage range as mentioned above and also differs in size to weight ratio because of high frequency (HF) transformer.