Forced Air Cooling of  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 andpower electronic converters can be observed. Forced air-cooling of powerelectronic converters offers reduced complexity of the cooling circuit compared to water-cooling. For air-cooled, high-ambient temperature rated converters, fans are required to 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 powerelectronics cooling are typically rated up to 75°C, rarely fans are specified up to 105°C. In this paper, the electrical and mechanical design of a 40 mm × 40 mm × 28 mm fan is presented in detail that offers an operational temperature range from -40 °C to 250°C at the rated speed of 19 000 min^-1 and comparable fluid dynamic performance in terms of static pressure and volume flow at 120 °C as commercial high performance fans at 20°C. The three-phase brushless direct current machine driving the fan is integrated into its hub and has got an input power of 15 W. The fan can be driven using a three-phase inverter supplied from 12 V dc voltage with an inverter switching frequency of less than 1.3 kHz.