AC Resistance Factor in One-Layer Form-Wound Winding Used in Rotating Electrical Machines

Analytical calculation of circulating and eddy currents in windings has been under research for almost a century, yet the calculation accuracy has improved slowly. However, over the recent years, the development of finite-element methods (FEM) has boosted the research. A lot of effort has been taken to calculate the ac resistance losses in transformers in the past, whereas rotating electrical machines have received less attention. These models have not taken the end-winding effect into account. In this paper, 2-D FEM results are compared with analytical equations. Based on these results, a more accurate model compared with Dowell's model for single-layer form-wound windings used in electrical machines is developed empirically, and the end winding resistance is analytically taken into account in the results. A maximum error of 5% is achieved in the range of 0-200 Hz for a single-layer form-wound winding.