A Simplified Bearing Testbed for Evaluating Bearing Current and Degradation in Wide Bandgap Inverter Fed Electric Machines

Bearing currents induced by motor drive systems can result in electrochemical corrosion of bearings, adversely affecting the motor reliability. Conventional bearing testing methods inside electric machines encounter difficulties in the replacement of bearing under test. To overcome this limitation, a simplified motor bearing testbed is proposed in this paper. Unlike conventional setups involving the actual electric machine, this testbed tests the bearing separately, allowing for easier inspection and replacement. It offers a simpler alternative to running an actual electric machine while accurately simulating the bearing operating conditions. The effectiveness of the proposed testbed is verified through a comprehensive comparison and analysis of voltage and current waveforms in bearings, conducted on both the proposed testbed and the actual operational electric machine. The testbed can test the bearings under a specific working condition for an extended duration and the bearing degradation is examined using a Scanning Electron Microscope. This testbed and investigation contribute to the theoretical understanding of bearing currents and their associated damage mechanisms.