Performance Optimization of a High Current Dual Active Bridge with a Wide Operating Voltage Range

The main aim of this paper is to improve the performance of high current dual active bridge converters when operated over a wide voltage range. A typical application is for fuel cell vehicles where a bi-directional interface between a 12 V battery and a high voltage DC bus is required. The battery side voltage ranges from 11 V to 16 V while the fuel cell is operated between 220 V and 447 V and the required power is typically 1 kW. Careful analysis shows that the high currents on the battery side cause significant design issues in order to obtain a high efficiency. The standard phase shift modulation method can result in high conduction and switching losses. This paper proposes a combined triangular and trapezoidal modulation method to reduce losses over the wide operating range. Approximately, a 2% improvement in efficiency can be expected. An experimental system is used to verify the improved performance of the dual active bridge using the proposed advanced modulation method