Experiment informed methodology for thermal design of PM machines

Abstract

The common approach used in the thermal design of electrical machines is calibrating thermal models based on the designer's previous experience, or hardware tests on a prototype machine. This allows for various manufacture and assembly nuances to be accounted for in the design process, assuring accurate and computationally efficient predictions of the machine thermal behaviour. The post-manufacture calibration of thermal models from tests on a complete machine has limited use in development of machine topologies, where no previous experience or machine hardware exist. In this context, an experiment informed design technique that makes use of reduced order machine sub-assemblies presents an attractive alternative. In particular, the hardware manufacture cost and time is significantly reduced compared to the prototyping of the complete machine assembly. This allows for numerous hardware samples to be constructed and tested, to inform the machine design process. The use of the machine sub-assembly testing is focused, but not limited to identifying and quantifying various power loss and heat transfer phenomena. This paper reviews the applicability of the sub-assembly testing in a broader context of the machine design. The aim of the research focuses on formulating a basis for sub-assembly based, experiment informed methodology for the thermal design of electrical machines.

Design of a brushless PM starter-generator for low-cost manufacture and a high-aspect-ratio mechanical space envelope

“…The experimental approach comprises tests on machine hardware subassemblies (motoretts). The stator winding subassembly has been found to be particularly useful in assessing various manufacture and assembly nuances affecting the power loss and heat transfer from the winding body into the machine periphery, which are notoriously difficult to derive accurately using theoretical techniques [14], [23], [24], [26]. A detailed description of the design process supplemented with experimental and theoretical data has been provided in consecutive sections of the paper.…”

Experimentally Calibrated Thermal Stator Modeling of AC Machines for Short-Duty Transient Operation

“…The experiment is set such that the convective heat transfer from the motorette surface, not in contact with the cold plate is negligible [16][17][18][19][20][21]. Due to the use of the thermally insulated chamber, the water cooled cold plate is the primary means of heat extraction from the sample.…”

“…The approach adopted here is to obtain the required thermal calibration from tests on stator sub-assemblies, referred to as 'motorettes' [16][17][18][19][20][21]. A motorette is a representative subassembly of the stator and winding, manufactured using materials and processes commonly used in construction of the final electrical machine prototype.…”

A systematic experimental approach in deriving stator-winding heat transfer

“…The existing body of work related with the thermal design and analysis of electrical machines provides various methods of representing and accounting for the stator-winding heat transfer. All these techniques are strongly related with the experimental and/or theoretical methods used [1]- [9]. However, the various existing approaches do not allow for a simple and direct comparison of the heat transfer efficacy between alternative machines and stator-winding designs.…”