A High-Density, High-Efficiency, Isolated On-Board Vehicle Battery Charger Utilizing Silicon Carbide Power Devices

Abstract

This paper presents an isolated on-board vehicular battery charger that utilizes silicon carbide (SiC) power devices to achieve high density and high efficiency for application in electric vehicles (EVs) and plug-in hybrid EVs (PHEVs). The proposed level 2 charger has a two-stage architecture where the first stage is a bridgeless boost ac-dc converter and the second stage is a phaseshifted full-bridge isolated dc-dc converter. The operation of both topologies is presented and the specific advantages gained through the use of SiC power devices are discussed. The design of power stage components, the packaging of the multichip power module, and the system-level packaging is presented with a primary focus on system density and a secondary focus on system efficiency. In this work, a hardware prototype is developed and a peak system efficiency of 95% is measured while operating both power stages with a switching frequency of 200 kHz. A maximum output power of 6.1 kW results in a volumetric power density of 5.0 kW/L and a gravimetric power density of 3.8 kW/kg when considering the volume and mass of the system including a case.Index Terms-AC-DC power converters, battery charger, dc-dc power converters, electric vehicles (EVs), power electronics, silicon carbide (SiC).

A study on power losses of the 50 kVA SiC converter including reverse conduction phenomenon

“…The observed differences suggest that the circuit simulation results confirm the calculations performed on the base of new equations -differences are not higher than 3.5% and decreases as the measured values increase. (8) For phase II the transistor power losses occur during two time periods (angle δ, see Fig. 3a), which leads to an equation: 4 diode dissipates conduction power losses only during phase III:…”

“…1b). The same can be said about literature examples [3][4][5][6][7][8][9][10][11][12] and an offer of the manufacturers providing integrated power modules [4,10,12,25]. From the point of view of on-state power losses, this case is the may be a serious problem during the design process of threephase converters with new SiC power devices, and especially crucial for converters with conduction losses dominating over the switching losses (i.e.…”

“…New diodes and transistors (unipolar JFETs and MOSFETs, as well as bipolar BJTs), available mostly in 1200 V and 1700 V voltage class, can be applied in three-phase converters rated up to several tens of kVAs [2][3][4][5][6][7][8][9][10][11][12]. This field is nowadays dominated by well-established technology of silicon IGBTs, which show different properties in comparison to new SiC power devices.…”

High efficiency design approach of a LLC resonant converter for on-board electrical vehicle battery charge applications

“…On-board battery charging designs allow the user a flexibility to be charged EV's battery from any available power point. Thus, user interest in EV can be increased with reducing of battery charge depletion anxiety [1]. However, adapting battery charge module on board increases the volume, weight and cost of the EVs [2]- [4].…”

“…For the second stage, in order to reach high power density and high efficiency, soft switching dc-dc converters allowing operation at high switching frequency are used. The phase shifted full bridge pulse width modulated converter and resonant converters are usually preferred [1], [10]- [13]. The soft switching operation of phase shifted full bridge converter becomes poor under light load conditions [14], [15].…”