A High Power DC/DC Converter Designed for Single Coolant Loop Hybrid Electric Vehicle Application

One potential system configuration for future hybrid electrical vehicles (HEV) is to use a single coolant loop for both internal combustion engines and power electronics inverters/converters. Under these conditions, coolant temperatures could be as high as 105°C. This paper proposes a high power DC/DC converter topology suitable for high temperature application. The new interleaved topology implements the power sharing on both high voltage side and low voltage side to alleviate the thermal stress. The DC/DC converter topology features a wide soft switching range to reduce the switching loss of the power semiconductor devices. In addition, a power module design approach is proposed to reduce the thermal resistance of the power semiconductor devices. The power-module-based approach provides for a higher level of integration by means of a wirebond-interconnected power stage. The more simplified interconnection strategy of this approach greatly increases the reliability and reduces the power loss and parasitic inductance. Detailed design considerations of key electrical and thermal parameters are provided. The concept is fully verified by experimental results with 105°C coolant, 5 kW, 200-400V to 14V isolated DC/DC converter prototypes.