Inverter-induced bearing currents – A thorough study of the cause-and-effect chains

In the last three decades, the study of inverter-induced bearing currents has become a very important line of research, and hundreds of works related to this theme can be found in the literature. Thus, several contributions concerning these currents were made, such as in the areas of modeling and simulation techniques, selection of appropriate mitigation method, developments of new mitigation devices and damage monitoring within the bearings, among others. In this context, much information related to bearing currents cause-and-effect chains is available. However, many contributions that have been developed in recent years for describing the mechanisms behind the bearing currents occurrence can only be found in a fragmented way. Thus, great efforts must be employed to provide a clear comprehension of each bearing current type and all the corresponding issues. To overcome this problem, this paper provides a broad overview of the physical principles related to the inverter induced bearing current, by means of a detailed and didactic approach. A huge volume of information was compiled, describing the expected currents maximum amplitudes, their probability of occurrence and the motor size which they are more expected to occur, among other relevant issues.