Prevention of harmful EDM currents in inverter-fed AC machines by use of electrostatic shields in the stator winding overhang

In this paper, an inexpensive mitigation technique is used for prevention of harmful EDM currents in small power inverter-fed AC machines. An electrostatic shield is mounted close to the stator winding overhang to eliminate the capacitive coupling between the stator end winding and the rotor surface. The bearing voltage that is caused by the common mode voltage at the motor terminals via the machine capacitances is reduced and the harmful EDM currents are eliminated. A 3D finite element method (FEM) is proposed for the calculation of the machine capacitances. The results are verified by analytical calculation, 2D FEM calculation and measurements.

[1]  A. Binder,et al.  High-frequency induction machine models for calculation and prediction of common mode stator ground currents in electric drive systems , 2009, 2009 13th European Conference on Power Electronics and Applications.

[2]  A. Binder,et al.  Calculation of Motor Capacitances for Prediction of the Voltage Across the Bearings in Machines of Inverter-Based Drive Systems , 2007, IEEE Transactions on Industry Applications.

[3]  A. Binder,et al.  Generation of high-frequency common mode currents in machines of inverter-based drive systems , 2005, 2005 European Conference on Power Electronics and Applications.

[4]  Doyle F. Busse,et al.  An evaluation of the electrostatic shielded induction motor: a solution for rotor shaft voltage buildup and bearing current , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[5]  A. Binder,et al.  Prediction of common mode ground current in motors of inverter-based drive systems , 2007, 2007 International Aegean Conference on Electrical Machines and Power Electronics.

[6]  Doyle F. Busse,et al.  Bearing currents and their relationship to PWM drives , 1995, Proceedings of IECON '95 - 21st Annual Conference on IEEE Industrial Electronics.

[7]  Annette Muetze,et al.  Practical Rules for Assessment of Inverter-Induced Bearing Currents in Inverter-Fed AC Motors up to 500 kW , 2007, IEEE Transactions on Industrial Electronics.

[8]  A. Binder,et al.  Scaling Effects of Inverter-Induced Bearing Currents in AC Machines , 2008, IEEE Transactions on Industry Applications.

[9]  Xavier Roboam,et al.  Use of extra degrees of freedom in multilevel drives , 2002, IEEE Trans. Ind. Electron..