Yew Chuan Chong

The Ventilation Effect on Stator Convective Heat Transfer of an Axial-Flux Permanent-Magnet Machine

This paper investigates the effect of the inlet configuration on cooling for an air-cooled axial-flux permanent-magnet (AFPM) machine. Temperature rises in the stator were measured and compared with results predicted using computational fluid dynamic (CFD) methods linked to a detailed machine loss characterization. It is found that an improved inlet design can significantly reduce the stator temperature rises. Comparison between the validated CFD model results and the values obtained from heat transfer correlations addresses the suitability of those correlations proposed specifically for AFPM machines.

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.

Pressure loss measurement in rotor-stator gap of radial flux electrical machines

The present paper investigates the effects of rotation on flow resistance of the flow passing through the rotor-stator gap of radial flux electrical machine. Rotational pressure loss was measured and compared with the results predicted using computational fluid dynamic (CFD) methods. By using dimensional analysis, correlation for the shock loss coefficient is proposed. It provides a significant contribution to the field of thermal modelling of electrical machines, such as thermofluid modelling using Motor-CAD.

Thermal Design of a Magnet-free Axial-Flux Switch Reluctance Motor for Automotive Applications

With the requirement to develop magnet-free motors for automotive application, more design effort is needed for thermal design as the machine temperature limits the motor performance. Thermal design procedure of automotive motor has to fully exploit the modern approaches in electrical machine thermal analysis in terms of accuracy and solving time. This paper proposes a computational-cost-effective way to obtain the optimum thermal design of an axial-flux switched reluctance motor by means of lumped circuit methods with some inputs from Computational Fluid Dynamic simulations.

Shaft cooling and the influence on the electromagnetic performance of traction motors

This paper addresses the heat transfer coefficient associated with a shaft-cooling of traction motors. In such shaft-cooling systems, the 50–50 ethylene glycol-water is made to flow through the shaft hole in order to cool the machine. The heat transfer coefficient is estimated using a computational fluid dynamics(CFD) method, where the effect of the rotational velocity as well as the liquid flow rate have been accounted for. The results from two different turbulence models were compared. As a result of the simulations, it is concluded that the rotational speed can significantly increase the convective heat transfer in the shaft hole above the stationary condition. Finally, the benefits of implementing a shaft-cooling to an existing ferrite magnet traction motor, in terms of the continuous torque capability, is described.

Improved thermal model for predicting end-windings heat transfer

The thermal analysis of the end space region of an electrical machine is mainly linked to the characterization of the convective heat transfer between the solid surfaces and the cooling fluid, normally air. Different relations have been proposed in literature by several authors but the calculation of the heat transfer coefficients (HTC) is still mainly related to empirical correlation factors, based on the experience. The aim of this work is to investigate the convection inside the end space region with the double objective of studying how the geometry influences the HTCs and of developing a new improved correlation for the computation of the HTCs. The study is conducted with the support of an advance CFD software. The investigation leads, as main result, to a dimensionless equation that links the Nusselt number to the rotational Reynolds number in the end-space region.