How to Design a 2 kW 48 V/12 V Bi-Directional Power Module with GaN FETs for 48 V Mild Hybrid Electric Vehicles
8月 25, 2022
Environmental pressures are creating pressure to quickly adopt newer, cleaner, and more efficient transportation options. In 2025, 1 in 10 vehicles sold are expected to be a more fuel efficient 48 V mild hybrid. 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. GaN power conversion solutions are perfect to support a 48 V to 12 V bidirectional converter used in these newer models.
A new reference design demo board, the EPC9165, is available to help jump start the design of a 2 kW bi-directional converter. The EPC9165 is a synchronous buck/boost converter with other supporting circuitry including current sensors and temperature sensor. The EPC9528 controller board ships with the EPC9165 to incorporate digital control and housekeeping power supply; this board uses the dsPIC33CK256MP503 digital controller from Microchip.
Capitalizing on the benefits of newer power electronics such as the highly reliable EPC2302 used in the EPC9165 demo board, this FET allows an engineer to realize 4 times better figure of merit (die area ·Ron) compared to a more traditional MOSFETs design. For the same gate voltage of 5 V, GaN FETs have at least 5 times lower gate charge than MOSFETs. Other important advantages of GaN FETs include lower Coss, faster voltage transition, zero reverse recovery and are physically smaller.
Thermal Management of the EPC9165 uses a standard commercially available 8th brick heatsink.
At full load, EPC eGaN FETs can operate with 96% efficiency at 500 kHz switching frequency, enabling 1 kW/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. Further, the solution is scalable; two converters can be paralleled for 4 kW, three converters for 6 kW or only one phase can be used for 1 kW.
A full application note (How to Design a 2 kW 48 V/12 V Bi-Directional Power Module with packaged eGaN FETs (How2AppNote 031) is available that details the design of the bi-directional high power EPC9165 converter for mild-hybrid cars and battery backup units using four EPC2302 packaged GaN FETs.
Reference design demo boards such as the EPC9165 are the perfect tool to “test drive” a new design!
All design files including schematic, bill of materials, and gerbers can be found on the EPC9165 landing page.