High-temperature (250 °C / 500 °F) 19′000 rpm BLDC fan for forced air-cooling of advanced automotive power electronics

In an increasing number of application areas and industry sectors, such as the automotive, aerospace, military or oil and gas industry, a trend towards higher ambient temperature rating from 120 °C upward for electrical machines and power electronic converters can be observed. Forced air-cooling of power electronic converters offers reduced complexity of the cooling circuit compared to water-cooling. For high ambient temperature rated converters fans are required that withstand these temperatures and still feature performance comparable to standard conditions in order to still enable a high converter power density and efficiency. Commercially available fans for power electronics cooling are typically rated up to 75 °C, very rarely fans are specified up to 105 °C. In this paper, the electrical and mechanical design of a 40mm × 40mm × 28mm fan is presented in detail that offers an operational temperature range up to 250 °C at the rated speed of 19'000 rpm and similar fluid dynamical performance in terms of static pressure and volume flow at 120 °C as commercial high performance fans at 20 °C. The 3-phase BLDC machine driving the fan is integrated into its hub and has got an input power of 15W. The fan can be driven using a 3-phase inverter supplied from 12V DC voltage with an inverter switching frequency of less than 1.3 kHz.