Design of de-ionised water cooling of power converters

Power electronics converters need cooling devices. High thermal performances allows decrease of converter volume and cost, and have a major impact on long-term reliability. Semiconductors encapsulation structure have to combine two opposite requirements, namely low thermal resistance and electrical insulation capabilities. Among numbers of designs (ceramics, diamond, polymers etc.), dielectric fluid cooling has been used for high voltage applications (oil, freon and substitutes, deionised water). In de-ionised water cooling, due to water intrinsic resistivity, special care has to be taken with design and corrosion issues. This paper presents design rules and figures for medium voltage applications.