22 kW Bi-Directional CLLC

This reference design demonstrates the application of Wolfspeed’s 1200V SiC MOSFETs to create a 22kW Bi-directional High Efficiency DC/DC Converter for electric vehicle (EV) on-board (OBC) and off-board fast charging applications. The C3M™ series MOSFETs are ideally suited for off-board fast charging, while the automotive qualified E-Series E3M devices are ready for the most challenging on-board applications. This design is intended to work with an active-front-end (AFE) converter that adjusts the input voltage to the DC/DC converter to optimize the system efficiency based on the output (battery) voltage. The range of the DC input is designed to be compatible with both single and three-phase AFE systems while supporting a wide DC output voltage range of 480V-800V. A full bridge CLLC resonant converter with a flexible control scheme; implements frequency modulation; phase shift control; adaptive synchronous rectification and a bridge reconfiguration technique. The use of 1200V 32mOhm SiC MOSFET’s in a TO- 247-4 package provides the best figure of merit (FOM) while reducing switching loss and cross talk.

The design accomplishes

• Peak efficiencies of 98.5% in both charging and discharging mode
• Power densities of 8kW/L

This reference design is offered as a comprehensive design package which can be used as a starting point for new SiC designs.

Specifications

Charging Mode

• Output Voltage : 480V-800V DC Nominal. System capable of 200V-800V DC
• At Vin=650V-900V DC ; Output Power : 22kW ; Output current : 36A
• At Vin=380V-900V DC ; Output Power : 6.6kW ; Output current : 26.4A

Discharging Mode

• Output Voltage : 360V-750V DC Nominal
• Output Power : 6.6kW ; Output current : 19A

• Full bridge CLLC resonant converter operating at 135-250kHz
• Tooled heatsink to simulate cooling plate
• CAN interface