Current Sharing Analysis of Parallel Strands in Low-Voltage High-Speed Machines

The electrical frequency in high-speed machines leads to more pronounced parasitic effects such as skin and proximity effects. In low-voltage machines, a low turn count is needed, requiring individual strands to be connected in parallel and further enhancing these adverse effects. This results in an uneven distribution of the current across the strands and circulating currents. This paper presents a simple yet flexible method to estimate this distribution, based on finite-element simulations and basic circuit equations. The effects of strand displacements or twisting can be accounted for in the actual machine geometry using a 3-D finite-element method, without requiring excessive computer memory or time. Experiments are performed to confirm the modeling method. Straight and twisted windings are compared, clearly showing the effectiveness of twisting the strands.