Vaporizable dielectric fluid cooling for IGBT power semiconductors

An electrical drive utilizing a common dielectric fluid as the coolant in two-phase operation for cooling 1700V 450A Isolated Gate Bipolar Transistor semiconductor modules has been proposed and demonstrated as a proof-of-concept system. While water as a coolant is very common for such drive systems, a variety of liquids are used in commercial, industrial, aerospace, and military electronics systems. Use of water as a coolant is often regarded as the most prevalent fluid for commercial and industrial electrical drives. The use of alternative coolants is often determined by existing industry practices, component availability, and knowledge base for proven approaches. Use of water or deionized water may also require additives for biological control and antifreeze, colorants, and other inhibitors. The use of water may also require, variously, particle filters, deionization filters, and similar hardware components. The consideration of alternative liquid coolants is driven by system requirements. System requirements impact several aspects of system design, including operating pressures, coolant heat capacity (including any required additives), safety, electrical hazard prevention, need for additives, and maintenance requirements. An alternative cooling technology is the use of a dielectric liquid in a low-flow rate, pumped cooling system utilizing two-phase cooling (without the use of compression), liquid cold plates, flow-through pumps, and a vapour condenser or heat exchanger. The use of such a system with a common vaporizable dielectric fluid will be described as a practical implementation in the power semiconductor market, with examples of individual applications in electronic systems. The vaporizable dielectric fluid is R-134a, a common refrigerant, selected for well-known properties and wide commercial availability at relatively low costs. The use of such refrigerants in pumped, low-flow systems required the development of pumps with and without flow-through cooling, specific to the fluid properties. Referred to as Variable Dielectric Fluid (VDF) cooling systems, these low-flow rate systems are now in use in commercial systems.