Electrical Engineering

, Volume 88, Issue 5, pp 403–409 | Cite as

Frequency domain modelling of random wound motor windings for insulation stress analysis

Original Paper


The use of conventional low voltage induction motors fed by pulse width modulated (PWM) inverters has begun to present important problems. These waveforms consist of steep-fronted pulses having very short rise times (about 100 ns in modern IGBT bridges) and high frequency repetition rates (up to 20 kHz) whose immediate consequences are additional electrical stresses in an induction motor’s insulation system. In this paper a frequency domain model for the analysis and characterization of the internal voltage distribution in random wound coils is presented. The model allows voltage prediction in time domain when an inverse fast Fourier transform (FFT) transformation is performed, and requires only a few frequency domain impedance measurements. This methodology will be useful for accurately predicting the voltage distribution in motor windings during the design stage, and reducing the risk of premature failure in motor insulation. Experimental and theoretical results are presented and compared and model effectiveness using different approximations is studied.


Frequency domain analysis Time domain analysis Random wound winding Pulse width modulation Steep-fronted transients Voltage distribution 


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Electrical Engineering DepartmentUniversity Carlos III de MadridLeganés (Madrid)Spain

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