This paper deals with the investigation of the influence of different parameters such as end effect and power cable length on the machine performances. This influence is highlighted for the extra low voltage applications (< 60 V DC) using six-phase permanent magnet assisted synchronous-reluctance machines. The investigation presented in this work combines different methods such as 3D finite elements, experimental tests, and information from technical data sheets. Firstly, the machine is designed using 2D finite element analysis, and then tested using two test benches, the first one with long cables and the second with short cables. The experimental power- speed characteristics obtained by these tests are compared to those obtained with simulations. The impact of the real modulation index, end effect and power cable length on the power speed characteristics is evaluated.

This study presents a test campaign carried out at IFPEN aimed at understanding and characterizing the thermal behavior of electric motors incorporating direct oil cooling. Several cooling systems and oils are evaluated at different operating points, and the effect of parameter variations is investigated. Experimentations are defined and performed to understand and quantify the impact of different oils and direct cooling systems on the performances of the electrical machine. The test results make it possible to verify and quantify the gain on the thermal behavior obtained by adding an oil injection system directly to the active parts of the machine in addition to an indirect water jacket cooling. This gain is observed for a representative set of operating points and oil injection parameters. The impact of physicochemical properties of oils on direct cooling performance is assessed by a comparison of several oils. The viscous friction losses are also identified. The results presented include a repeatability and reproducibility study for speed values up to 14 krpm and continuous powers up to 60 kW.

The work presented in this document deals with the no-load losses distribution of an electric motor. A prototype machine is designed and manufactured. This prototype includes two different types of direct oil cooling systems: radial on the coil end-windings and axial on the rotor. Several configurations are tested to evaluate and quantify the effect of each source of losses such as: bearings, iron, sealings, airgap windage, and viscous friction (oil directly on active parts). These losses are observed for a representative set of operating points up to 15,000 rpm.

This article presents a testing procedure for the no-load loss separation of high-speed electric machines designed for Electrically-Assisted Turbochargers. The main contribution of this paper is to introduce a loss separation method suitable for low power (several kW) high-speed electric motors. The paper begins by presenting the environmental context of the study, the overall system and motivations to develop such a method. Then, the experimental procedure using several back-to-back (B2B) configurations supported by an air bearing is proposed to identify the no-load losses including: no-load iron, air bearing and windage losses. Finally, the method is applied to three stator topologies to compare the no-load iron losses levels. The presented principle enables a no-load loss separation for very high-speed machines in the range of several kilowatts without the use of a torque meter. In addition, the identification of the air bearing losses makes possible the evaluation of the motor efficiency on the presented B2B test bench without any major modifications.