The design of this demonstration board is scalable, whereby two converters can be paralleled to achieve 3 kW or three converters can be paralleled to achieve 4.5 kW. The board features four EPC2206 100 V eGaN FETs and is controlled by a module that includes the Microchip dsPIC33CK256MP503 16-bit digital controller.
By 2025, one of every 10 vehicles sold worldwide is projected to be a 48 V mild hybrid. These 48 V systems are able to boost fuel efficiency and deliver four times the power without increasing engine size, and reduce carbon-dioxide emissions without increasing system costs. These systems will require a 48V – 12V bidirectional converter, with power ranging from 1.5 kW to 6 kW. The design priorities for these systems are size, cost, and high reliability.
EPC eGaN FETs can operate with 97% efficiency at 250 kHz switching frequency, enabling 800 W/phase compared to silicon-based solutions, which are limited to 600 W/phase due to the limitation on the inductor current at 100 kHz maximum switching frequency.
By using GaN FETs, it is possible to reduce the number of phases from five to four for a 3.5 KW converter while increasing efficiency. According to EPC, the efficiency of a four-phase GaN converter operating at 250 kHz is 1.5% higher than a five-phase silicon MOSFET-based converter operating at 100 kHz.
Overall, the DCDC converter is three times faster, greater than 35% smaller and lighter, and offers greater than 1.5% higher efficiency compared to silicon MOSFET solutions. And the overall system cost is less. In addition, the efficiency and thermal performance of GaN FETs enables air cooling instead of water cooling and the small size of the GaN FETs strongly reduce heat-dissipating aluminum housing for additional system cost saving.
“eGaN FETs provide the fast switching, small size, and high efficiency needed to further reduce the size and weight of 48 V – 12 V automotive power system converters. The demonstrated superior reliability of GaN FETs make them ideal for this very demanding application,” said Alex Lidow, CEO of EPC. “The EPC9137 is a great example of the capabilities of GaN FETs to increase frequency and efficiency to allow smaller inductance for less phases and higher power density.”
