Investigation of Cooling Techniques and Enclosure Types for Integrated Motor Drives

Integrated motor drives (IMDs) combine power electronics and an electric motor into a single enclosure to improve power density and provide other performance advantages. Wide-bandgap (WBG) power switches and current-source inverters (CSIs) offer appealing thermal features for future IMDs because they operate at high efficiency with WBG power devices and inductors that can withstand high operating temperatures. Alternative cooling strategies are investigated using several enclosure types for a prototype 3 kW WBG-based IMD unit. These cooling configurations were carefully designed to efficiently dissipate heat from the power devices without overheating surrounding components in a very compact system package. Three IMD prototype units have been developed that are electrically identical but with different enclosure types and cooling strategies, enabling meaningful comparisons of their thermal performance. Experimental results show that it is possible to design cooling systems combining air convection and heat conduction that effectively cool the IMD electronics for both ventilated and non-ventilated machine enclosures, including the most demanding totally-enclosed, non-ventilated (TENV) configuration.