Extended HF equivalent model of a drive train

The knowledge of the system behavior of modern drive trains is essential for more and more integrated drive systems with variable-speed operation. While state-of-the-art inverters have a lot of advantages, there are also some downsides. Parasitic currents driven by the common-mode voltage of voltage source inverters can damage the machine elements of the drive train. Three different types of these currents are reported to literature: high-frequency circulating currents in the motor, high-frequency rotor ground currents and Electrical Discharge Machining (EDM) currents as arc discharges in the different lubrication gaps. This paper focuses on third current type and expand this parasitic effect on the whole drive system. For this it is important to see the drive train as a high-frequency electrical system. In this work the basics of previous investigations about the motor behavior will be used in combination with new models for the rest of the drive train. By the use of a simulation model of a motor, coupled with a single stage gearbox, it will be shown, that the occurrence of parasitic currents is strongly influenced by the operating conditions, geometrical properties as well as the time depending behavior of the gear mesh.

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