Device loss estimation and heat-sink design for SiC based power converter feeding a switched reluctance machine

Asymmetric H-bridge converter is widely used for feeding a switched reluctance machine (SRM). This paper discusses a method to estimate the losses in the power devices in such type of converters, where average torque control or square current injection is employed. This paper presents the cooling system design for a silicon carbide (SiC) based asymmetric H-bridge converter. The SiC MOSFETs and the diodes are TO-247 packaged. A specially designed heat-sink is presented for effective forced air cooling of the devices. The thermal performances of an existing heat-sink and the proposed heat-sink are compared based on simplified thermal analysis, detailed thermal simulations and actual measurements. The thermal resistance of the two heat-sinks are measured and compared for different values of power dissipation.