Dave Staton

Improved synchronous machine thermal modelling

It is well accepted nowadays that in synchronous machine design procedures thermal aspects should be weighed equally with electromagnetic issues and considered in an iterative manner. Synchronous machine thermal models are being constantly optimised and improved, and many design areas are well understood and documented. Even so, there are a number of thermal model design aspects that require significant further study and analysis. These aspects include accurate machine operational loss prediction, precise loss distribution, thermal model discretisation level issues and cooling air flow implications. They will be analysed in the paper, with future related investigations being identified.

A comparison of an interior permanent magnet and copper rotor induction motor in a hybrid electric vehicle application

This paper compares a permanent magnet motor to an induction motor in a hybrid electric vehicle application. The comparison considers replacing an existing 50kW Interior Permanent Magnet (IPM) motor with a copper-rotor induction motor (CR-IM). The 2004 Toyota Prius Hybrid system is used as the baseline for the analysis. The size, weight and cost of the two topologies are compared and the difference in lifetime energy use over various drive cycles is analysed. Additional considerations including the impact on battery sizing and the inverter VA rating are also considered and discussed.

Modern heat extraction systems for electrical machines - A review

This paper presents a review of modern cooling system employed for the thermal management of electrical machines. Various solutions for heat extractions are described: high thermal conductivity insulation materials, spray cooling, high thermal conductivity fluids, combined liquid and air forced convection, loss mitigation techniques.

Brushless AC interior-permanent magnet motor design: Comparison of slot/pole combinations and distributed vs. concentrated windings

This paper compares the attributes of 36 slot, 33 slot and 12 slot brushless interior permanent magnet motor designs, each with an identical 10 pole interior magnet rotor. The aim of the paper is to quantify the trade-offs between alternative distributed and concentrated winding configurations taking into account aspects such as thermal performance, field weakening behaviour, acoustic noise, and efficiency. It is found that the concentrated 12 slot design gives the highest theoretical performance however significant rotor losses are found during testing and a large amount of acoustic noise and vibration is generated. The 33 slot design is found to have marginally better performance than the 36 slot but it also generates some unbalanced magnetic pull on the rotor which may lead to mechanical issues at higher speeds.

Thermal Modelling of TEFC Alternators

The importance and necessity for an electrical machine design process where thermal and electromagnetic issues are considered in an iterative manner is clear today. A commercially available thermal modelling package is used to investigate the design of a TEFC synchronous machine for a mobile refrigeration application, which imposes significant demands on the thermal performance of the machine. Experimental results of a fully instrumented machine have been used to show that the software package predicts the thermal performance of the machine to a high degree of accuracy. Sensitivity analysis was used to optimise the machine for the required application

FEM and Lumped Circuit Thermal Analysis of External Rotor Motor

In the recent years outer rotor motors, mainly brushless ones, have been the object of increasing attention for some specific applications, thanks to their high inertia and other interesting characteristics. However they are particularly difficult to design from the point of view of their thermal behaviour, as the heat is mainly generated form the internal part of the motor and because some mechanical parts involved in the driving system are embedded in the machine and contribute to the heating or cooling of the machine, consequently they cannot be ignored in the thermal analysis. The production of such advanced machines is very demanding of development time and production cost and therefore a fast and reliable thermal design as a preliminary is greatly beneficial

Analytical thermal models for small induction motors

Thermal analysis is an important design aspect and becoming a more important component of the electric motor design process due to the push for reduced weights and costs and increased efficiency. The accuracy of analytical thermal models depends on the accuracy of the thermal resistance computation and on the number of nodes in the equivalent thermal circuit. In this paper several thermal analytical models with different numbers of nodes are compared against with each other and with experimental data. It will be demonstrated that the more sophisticated and detailed model having a larger number of nodes can be used to calibrate the simpler but faster models with less nodes. The models are all for the same range of small TENV induction motors.

Thermal modeling of a short-duty motor

In some applications electric motors operate only for a very short period of time. Thermal designs of such motors are extremely important to optimize system weight and size. This paper discusses transient thermal performance of a short-duty rated motor. An analytical study shows that the quality of impregnation plays a significant role in transient performance. Thermal protection with temperature sensors will not be reliable due to delays in temperature measurement, and a predictive protection is essential. The analysis is confirmed by 2-dimentional finite element analysis and prototype motor testing.

Design of a 50000 rpm high-speed high-power six-phase PMSM for use in aircraft applications

This paper deals with the challenge of designing a high-speed permanent-magnet synchronous machine (PMSM) with a continuous power of 700 kW as a turbo generator for the usage in aircrafts. For this application, high-power density above 5kW/kg is required. To identify the best topology and to fulfil the given requirements, various design solutions for the PMSM are taken into account. This contains various six-phase winding configurations to minimize losses or weight. Moreover, a possible magnet and various sleeve materials are taken into account in order to ensure mechanical stability. Furthermore, a thermal design is presented. Results given are based on analytical, as well as FE simulations.

A Line-Fed Permanent-Magnet Motor Solution for Drum-Motor and Conveyor-Roller Applications

This paper describes a new solution for drum-motor and conveyor-roller applications. The specially designed three-phase line-fed permanent-magnet motor ensures that a self-starting capability is combined with high efficiency and operation at constant speed with varying load.