This thesis focuses on resistive winding losses in rotating electrical machines, with special attention on circulating currents in random-wound machines. Five methods are developed for computationally efficient analysis, including one analytical circuit model and four 2D finite element models. The circuit model, as well as two of the numerical models, focus on circulating currents, while the remaining two numerical models also include all eddy current effects. Furthermore, a stochastic approach is proposed to model the uncertainty included in random-wound windings. Finally, a large set of measurement data concerning high-speed induction machines is analysed and used to validate the stochastic approach. According to simulations, all of the developed models yield reasonably accurate results at a significantly reduced computational cost. The two numerical methods that also consider eddy current effects are found to be particularly precise. The stochastic approach is also found to be able to predict the variation in measured circulating current losses. The measured machines are observed to exhibit significant circulating current losses. On average, they increase the winding losses by 60 %. Furthermore, the losses are found to vary significantly even between nominally identical machines. Finally, according to simulations, also medium-speed machines with 50 Hz rated supply are found susceptible to high circulating current losses, especially if supplied by an inverter.
|Translated title of the contribution||Kierto- ja pyörrevirtahäviöt pyörökuparikäämityissä sähkökoneissa|
|Publication status||Published - 2017|
|MoE publication type||G5 Doctoral dissertation (article)|
- Circulating currents
- eddy currents
- finite element analysis