D. Lampard

A fully integrated 30 kW motor drive using matrix converter technology

This paper explores the viability of using direct power converter technology to realize integrated motor drives, at power levels significantly higher than is possible with traditional approaches, fitting within the same space envelope as an equivalent motor. The integrated motor design was targeted at pump and fan applications where the need to install motor drives in a separate location is often an impediment to the replacement of fixed speed motors. In order to achieve this objective the thermal and electrical design of the integrated drive have to be considered together. This paper presents the final design that achieves all these objectives, including fully tested and evaluated demonstrations of the power converter and the cooling arrangements. The final integrated motor drive design only differs from a standard motor in terms of one end plate, the terminal box and the shaft driven fan. Full practical results of the 30 kW demonstrator are presented in the paper

Conjugate heat transfer analysis of a salient pole rotor in an air cooled synchronous generator

A study of combined heat transfer by conduction and convection for the rotor of an air-cooled, 4-pole generator was carried out using a general purpose CFD code. A simplified generator design was used to demonstrate a technique to analyse temperature distribution through the salient pole rotor at the design stage. Whilst CFD has the capability to predict airflow and convective heat transfer, it is shown that it is also necessary to model heat conduction, including the heat input from the losses, to produce a realistic thermal model of the rotor. A strip-on-edge coil structure is considered and it is shown that modelling the coils as homogeneous materials with anisotropic thermal conductivity provides sufficient accuracy for the prediction of local coil temperatures. Consideration is given to the effect of the coil size and structure on the cooling. To demonstrate the capability of the method, a modification to the test model considered is presented in which the airflow is modified, leading to enhanced heat convection and field coil temperature reduction.

An Integrated 30kW Matrix Converter based Induction Motor Drive

This paper explores the viability of using direct power converter technology to realize integrated motor drives, at power levels significantly higher than is possible with traditional approaches, fitting within the same space envelope as an equivalent motor. The integrated motor design was targeted at pump and fan applications where the need to install motor drives in a separate location is often an impediment to the replacement of fixed speed motors. In order to achieve this objective the thermal and electrical design of the integrated drive have to be considered together. This paper presents the final design that achieves all these objectives, including fully tested and evaluated demonstrations of the power converter and the cooling arrangements. The final integrated motor drive design only differs from a standard motor in terms of one end plate, the terminal box and the shaft driven fan. Full practical results of the 30 kW demonstrator are presented in the paper

Modelling ventilation and cooling of the rotors of salient pole machines

Computational fluid dynamics (CFD) offers the potential to model ventilation and cooling in electrical machines. This can provide the opportunity to optimize the thermal design of machines at an early stage without the need for extensive and costly experimentation. However, designers need to have confidence in the use of CFD and this paper summarizes the results of research work to validate the CFD modelling of large salient pole machines. It is shown that the commercial CFD code Fluent demonstrates a good ability to predict air flow and heat transfer on the rotor of a salient pole machine.

The impact of matrix converter technology on motor design for an integrated flight control surface actuation system

This paper describes research related to producing integrated electric motor driven flight control surface actuation systems, for a More Electric Aircraft. The main requirements and motor options are discussed. The advantage of the matrix converter in terms of compactness, due to removal of energy storage elements, is highlighted. However, this advantage is shown to bring with it problems when motors which have pulsed voltage and current waveforms are employed. The resulting discontinuities in power flow during current commutations are reflected at the input terminals to the drive as supply current harmonics.

Prediction of the heat transfer from the end winding of a TEFC strip-wound induction motor

The flow field and heat transfer in the end region of a TEFC induction motor have been simulated experimentally and computationally. The test rig included a strip-wound end winding taken from a two-pole production motor. A single loop of the winding was instrumented with thermocouples and miniature heat flux gauges and supplied with a heating current. The measured local heat transfer coefficients on the winding surface differed from the computed values by a maximum of 30%. Their spatial variations agreed closely in form and reflected the computed flow field.

The Use of Computational Fluid Dynamics in the Thermal Design of Rotating Electrical Machines

Thermal constraints impose limitations on the power capability of many electric motors and generators. However, inadequate data on ventilation air flows and convection heat transfer coefficients hamper the design process. Computational fluid dynamics (CFD) presents an opportunity to predict air flow and heat transfer in many situations. However, the complex geometries combined with rotation in the end regions of electric motors and generators present significant difficulties for CFD. An experimental study of air flow and heat transfer in the end region of a 200 kW 2 pole totally enclosed, fan cooled (TEFC) induction motor was carried out. Detailed measurements of heat transfer coefficient around the end windings and frame were made along with measurements of windage loss and airflow at particular locations within the end region. These were compared with a detailed model of the end region using the CFD software Fluent UNS and good agreement was found. The results are presented and the reasons for the difference between the measured values and CFD predictions are discussed. It is concluded that general purpose CFD software is now at a stage of development where it can be used in a design office environment to undertake design analysis of electrical machines.