Hybrid Si-SiC half-bridge module

Second, the cold-plate underside consists of highly porous media composed of silver-bonded copper spheres that transfer thermal energy through conduction and aid convective heat transfer to the coolant. Heat-transfer capability is greatly 

Numerical simulations of the thermal performance of the module were performed using finite element analysis. In the present model, the fluid path is represented by a series of interconnected nodes. Convection processes are modeled as transfer processes between these nodes (or volumes) and surfaces of the geometrical mesh. In this case, a series of analyses based on knowledge of the fluid properties, flow rates, and the relative sizes of the fluid passages and solid phase interconnections led to the value of 3.88 W/cm -K for the effective heat-transfer coefficient. Convective heat transfer using this coefficient was used on all of the internal free surfaces of the module. 

Silicon Carbide Technology and Power Electronics Applications 

To represent the module cooling behavior, it is convenient to define the heat dissipation capability as the ratio of total heat generated to the maximum temperature difference experienced by the switch assembly. This ratio can then be plotted as a fnnction of coolant flow rate to establish the operating range and functional safety margins. Reference [31] shows the heat dissipation capability of the heat sink assembly. 

Note that as the coolant flow rate is increased at lower rates, the capability of the heat sink to remove thermal energy is enhanced. This effect has diminishing retnrns at high rates due to the increased dependency on condnctive rather than convective heat transfer. At low flow rates and at reduced effective heat-transfer coefficients, the resnlts are somewhat impractical. In these cases, adjacent IGBTs are not maintained at equal temperatures. This condition would generate imbalances in the electrical current sharing, resulting in nndesirable switch performance. 

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