Heat sink design considerations in medium power electronic applications with long power cycles

Abstract

The aim of this work is to investigate the impact of the heat sink thickness and material, as well as, of the convection coefficient of the water cooling system on the power-electronics module thermal stressing. The heat extraction capability of different thicknesses is tested. It is concluded that the thickest heat sink results in marginally lower temperature variation at the junction level compared to the second thickest one. In the thickest heat sink case, the linear dependence of the thermal resistance on the thickness counteracts the benefit of the increased thermal capacitance. The increase in the cooling medium flow rate, which corresponds to an increase in the convection coefficient between the heat sink bottom surface and the water, can be avoided by increasing the thickness of the heat sink. In this way, the energy consumption of the cooling system is reduced. The increase in the flow rate drastically reduces the thermal stressing in the thinnest heat sink case. The increase of the heat sink thickness can be beneficial for long power cycles. Copper and aluminum are the two materials that are compared, with the copper heat sink exhibiting a slightly increased performance. The study is conducted for a medium power DC-DC converter of a magnet supply with focus on long power cycles.Presented at: EPE 2015, 7-10 September 2015, Geneva, Switzerland Geneva, Switzerland October, 2015 Heat sink design considerations in medium power electronic applications with long power cycles AbstractThe aim of this work is to investigate the impact of the heat sink thickness and material, as well as, of the convection coefficient of the water cooling system on the power-electronics module thermal stressing. The heat extraction capability of different thicknesses is tested. It is concluded that the thickest heat sink results in marginally lower temperature variation at the junction level compared to the second thickest one. In the thickest heat sink case, the linear dependence of the thermal resistance on the thickness counteracts the benefit of the increased thermal capacitance. The increase in the cooling medium flow rate, which corresponds to an increase in the convection coefficient between the heat sink bottom surface and the water, can be avoided by increasing the thickness of the heat sink. In this way, the energy consumption of the cooling system is reduced. The increase in the flow rate drastically reduces the thermal stressing in the thinnest heat sink case. The increase of the heat sink thickness can be beneficial for long power cycles. Copper and aluminum are the two materials that are compared, with the copper heat sink exhibiting a slightly increased performance. The study is conducted for a medium power DC-DC converter of a magnet supply with focus on long power cycles.

On lifetime evaluation of medium‐voltage drives based on modular multilevel converter

“…The heat sink parameters (thermal resistance and capacitance) are estimated based on [27], where a simplified heat sink model for power converter is proposed. This methodology considers a uniform temperature profile throughout the power devices baseplate and heat sink volume.…”

“…5 b . In such conditions, the heat sink parameters can be computed by [27]: where is the heat sink thickness, is the thermal conductivity of the heat sink material, is the heat sink surface area, is the specific heat capacity and is the material density. For comparison purposes, copper and aluminium heat sinks are used.…”

“…The heat sink thermal capacitance can affect considerably the thermal stresses during transients and the power cycling in the power devices. This is discussed in [27], which compares aluminium and copper heat sinks for a magnet supply system. Nevertheless, the technical literature does not discusses how the traditional lifetime evaluation affects the analysis, since it neglects the heat sink thermal capacitance.…”

Electro-thermal Design of a Solid-State MVDC Circuit Breaker

“…Therefore, the design of a high-performance cooling system is required to ensure an efficient operation of the DC CBs. For this purpose, a heatsink is used in order to dissipate the thermal energy generated in the chips to the ambient within a reasonable time period [8]. This will lead to lower temperature at the junction, and hence, the conduction losses will also be minimized.…”

Current sharing inside a high power IGBT module at the negative temperature coefficient operating region

“…Therefore, the power ratings of the power modules must be enhanced by increasing the silicon area per chip and limit the temperature rise. As a result, the IGBT module may operate at a current level not above 25% of its nominal ratings [2].…”