Abstract
Thermal management is often considered a bottleneck in the pursuit of the next-generation electrical machines for electrified transportation with a step change in power density. Slot-channel cooling is considered to be an effective cooling technique, either as an independent method or as a secondary heat transfer path, which compliments traditional cooling systems. The slot-channel specific geometry and position effects on the thermal benefits are not thoroughly investigated in the literature, while previous work focuses on passing fluid through the unused space left in between coils forming concentrated windings. In this article, slot-channel cooling is implemented within an oil-flooded cooling system for a high power density motor that is used as a pump. A flexible and detailed lumped parameter thermal network (LPTN) is proposed for the cooling system, with the LPTN used to optimize the slot-channel dimensions and location for obtaining maximum thermal benefits. Finally, a surface-mount permanent magnet (SPM) machine with the optimized slot channel geometry is built and tested to validate the thermal model, experimentally achieving an armature continuous current density in excess of 30 A/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .
Highlights
With the increasingly stringent emission legislations, the world is developing moreelectric and all-electric transportation technologies at an unprecedented rate
As this paper investigates the thermal performance of the surfacemount permanent magnet (SPM) machine with Slot channel cooling system (SCCS) and fully flooded oil cooling system (FFOCS), losses play a critical part in determining the thermal conditions of the electrical machine
Firstly the thermal performance of the slot channel cooling system combined with fully flooded oil cooling system for a SPM machine is investigated with a bespoke designed thermal network, which captures the slot channel geometry variation
Summary
With the increasingly stringent emission legislations, the world is developing moreelectric and all-electric transportation technologies at an unprecedented rate. In some circumstances this intensive fully flooded cooling system is not sufficient to remove the massive heat generated by the windings in a high power density electrical machine, and combinations of different cooling techniques may be required. LPTN is used for the design and thermal analysis on a fully flooded oil cooling system (FFOCS) for a high power density electrical machine. The structure of the paper is as follows: in section II, the designed SPM machine is presented, together with the proposed LPTN thermal model for the cooling system, which incorporates both the fully flooded oil cooling system (FFOCS) and the slot channel cooling system (SCCS). Other IPM motors with different rotor topologies could be considered, to minimise the inertia of the rotor the advantages of an SPM Halbach and the very thin rotor back iron did represent the best choice for the case in hand
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