Reduction of Winding AC Losses by Accurate Conductor Placement in High Frequency Electrical Machines

Abstract

In the design of electrical machines, the increase of power density has become one of the main research themes. With most of the power loss in high power density electrical machines often being generated in the stator winding assembly, it is necessary to reduce these losses. The effects of strands and bundle positions in the slot on the AC losses in the winding are often overlooked. Taking as a case-study an existing high frequency machine, this paper analyzes and provides an in-depth insight into such effects. Exploiting the rapid advancements in precision 3D printing, it is found and experimentally verified that by controlling the position of the conductors within the top of the slot the AC losses can be markedly reduced.

High-Power Machines and Starter-Generator Topologies for More Electric Aircraft: A Technology Outlook

“…6) Efficient and lightweight PECs, based on WBG devices, for loss reduction and ultra-high switching frequency. An increased switching frequency can be required for high-frequency electrical machines [194] with high-speed operation, i.e., fundamental frequency (f ) moving toward the kilohertz (kHz) territory, as well as solving challenges for iron-less (or coreless) machines with low inductance. .…”

Optimized Magnet wire size and Slot winding height for minimum AC losses in a Traction Machine

“…For computational efficiency, the same methodology for simplification of modelling described in [12] is used for analysis in this paper. That is, finite-element model is reduced to one slot pitch for faster computational time.…”

“…After laying the strands in the slot geometry, the strands are clustered into bundles to resemble randomly-wound winding following a similar methodology described in [12]. With the purpose of selecting the optimum winding height, the winding is then pushed towards the slot bottom in steps.…”

“…These gives select number of plausible models. Similar methodology as described in [12] is used. The article shows accuracy of over 90% between FEA and experimental results.…”

“…However, at high frequencies the flat rectangular wires may incur significant loss and laying the rectangular flat wires flat across the slot causes manufacturing challenges and increase the production cost. Authors in [12], experimentally verified that by carefully controlling the shape of the bundles near the slot top, the AC losses can be significantly reduced.…”