22 kW Bi-Directional CLLC Utilizing IMS Board

This reference design demonstrates the application of Wolfspeed’s automotive qualified E3M 1200V SiC MOSFETs in a TO-263-7 (J2) surface mount package to create a 22 kW Bi-Directional High Efficiency DC/DC Converter based on insulated metal substrate (IMS) board for electric vehicle (EV) on-board charger (OBC) and similar applications. The AEC-Q101 compliant E3M™ series MOSFETs are ideally suited 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 480 V-800 V. 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 32mΩ automotive qualified SiC MOSFETs enhance thermal performance and facilitates assembly automation. The use of IMS PCB in this reference design exhibits superior thermal performance.

The design accomplishes

• Peak efficiency of 98.6% in both charging and discharging mode
• Power density of 9.4 kW/L
• Bi-directional operation

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

Specifications

Charging Mode

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

Discharging Mode

• Input Voltage: 300 V – 800 V DC
• Output Voltage: 360 V – 750 V DC Nominal
• Output Power: 6.6 kW; Output current: 19 A

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