Method for diagnostic of permanent-magnet electrical machines.

This paper proves that the use of conventional diagnostic methods of rotor crack and local demagnetization based on the harmonic analysis of the output voltage or back-electromotive force is effective only with a certain ratio of the number of slots and poles. This statement was proved experimentally. The diagnostic method of the rotor cracks and local demagnetization which is universal for all types of windings and the number of slots of 2-pole synchronous electric machines with permanent magnets is proposed. The mathematical apparatus for the implementation of the proposed method is developed and is verified with the help of FEM and experimental studies. All the experimental studies have been carried out for various rotor magnetic systems and a different number of stator slots

High-Performance Generator for a New Generation of Aircrafts

The article describes multidisciplinary design process of high-performance electric generator for advanced aircrafts by analytical methods and computer modeling techniques (electromagnetic, thermal and mechanical calculations). New technical solutions used in its development are described. The main ideas are revealed of the method of EG voltage stabilization we used. To improve the heat dissipation efficiency, we have developed a new cooling system, and provide its study and description in this paper. The advantages of this cooling system include the fact that EG is made with dry, uncooled rotor. This allowed eliminating additional pumps, and significantly reducing the size of CSD. According to the results of our study, we created an experimental full capacity layout, and its studies are also provided in this paper

Parameters Variation to Estimate Performance Characteristics of 3-Phase Asynchronous Motor

The 3-phase asynchronous squirrel cage motors (SCIM) are main competitor machines placed instead of other motors in the commercial and industrial fields. The stator and rotor material selection and construction topology influence the electrical machine design. The results illustrated with the motor of a 15 KW, variable controlled speed, for the constant frequency of 50 Hz or 60 Hz. The motor parameters created inside the simulation model must be matched with the value of a standard parameter for SCIM to achieve a high dynamic response. This work examines the effect of the parameters variation for synchronous motor on the performance characteristics at starting point and at a load change for different time and speed regions. Changing of the rotor power is taken into consideration, this occurs with dynamic change of the hydraulic pump load from the valve. In the industrial applications, production, and manufacturing, till present there are still struggles to find the most holistic environment of the SCIM to achieve its efficiency at the lowest cost and same time control the motor performance, so we predicted the method of reducing the most effective motor parameters to improve the efficiency. The offline method used the SCIM parameters to calculate the time-varying current, torque, and rotor speed. The results illustrated that this method was fully consistent with the experiment tests and the standard theoretical values. A MATLAB program is used to simulate this study. The simulation model proved the feasibility of the proposed method with encouraging performance

Power Loss and Thermal Analysis of a MW High-Speed Permanent Magnet Synchronous Machine

High speed permanent magnet synchronous machines (PMSMs) have attracted much attention due to their high power density, high efficiency, and compact size for direct-drive applications. However, the consequent power loss density is high and heat transfer is also deemed as a technical challenge. This is particularly the case for high-speed operation. In this paper, electromagnetic and mechanical power losses in a MW level high speed PMSM is comprehensively investigated by finite element analysis; the transient machine demagnetization performance is studied with the proposed rotor composite structure to improve the machine anti-demagnetization capability; the temperature distribution of the high speed PMSM is also analyzed by a fluid-thermal coupling method with calculated power loss. The high speed PMSM is prototyped and experimentally tested to validate the effectiveness of numerical models and calculated results

Coupling calculation and analysis of three-dimensional temperature and fluid field for high-power high-speed permanent magnet machine

© The Institution of Engineering and Technology 2019. In order to accurately estimate the temperature rise for high-power high-speed permanent magnet machines (HSPMMs), a novel temperature calculation method considering the non-linear variation of material properties with temperature is proposed based on multi-physics co-simulation analysis. According to the theory of computational fluid dynamics and heat transfer, the computation model of fluid-solid-heat coupling heat transfer is established, and the coupled field is calculated using finite volume method with fundamental assumptions and corresponding boundary conditions. With the influences from temperature gradient and water flow rate considered, the heat transfer coefficients of water pipe surfaces are obtained by the application of the inverse iteration method. Thus, HSPMM temperature and fluid field can be simulated numerically by the finite volume methods, while the spatial temperature distributions for the machine main components are analysed in this study. The 1.12â€.MW, 18,000â€.rpm HSPMM is prototyped with experiments conducted on it, while the test data are then compared with the calculated results, which validate the correctness of the solution method of the coupled field

High-speed synchronous generators. A critical assessment

Considering that there are electromagnetic, mechanical and thermal constraints that determine the design of high-speed electrical machines, the criteria that lead to adequate selection of the machine are established in this work. Moreover, taking into account the current state of technology, the critical values in the ratio (output power)/(rotation speed), are presented. The paper focuses on the high-speed synchronous generators, especially in permanent magnet generators, inductor alternators and flux switching alternators, emphasizing their constructive fundamentals and their advantages and disadvantages. The analysis is completed with a critical assessment that classifies them according to previously defined requirements. Although the decision of the final choice is largely determined by the application of interest, it can be said that, in general, synchronous generators with permanent magnets in the rotor are the best option.Postprint (published version

Impact of soft magnetic material on design of high speed permanent magnet machines

This paper investigates the effect of two soft magnetic materials on a high speed machine design, namely 6.5% Silicon Steel and Cobalt-Iron alloy. The effect of design parameters on the machine performance as an aircraft starter-generator is analysed. The material properties which include B-H characteristics and the losses are obtained at different frequencies under an experiment and used to predict the machine performance accurately. In the investigation presented in this paper, it is shown that machines designed with 6.5% Silicon Steel at a high core flux density has lower weight and lower losses than the Cobalt-Iron alloy designs. This is mainly due to the extra weight contributed by the copper content especially in the end-windings. Due to the high operating frequencies, the core-losses in the Cobalt-Iron machine designs are found to outweigh the copper-losses incurred in the Silicon Steel machines. It is also shown that change in stack length/number of turns has a considerable effect on the copper losses at starting, however has no significant advantage on rated efficiency which happens to be in a field-weakening operating point. It is also shown that the performance of the machine designs depend significantly on material selection and the operating point of the core. The implications of the variation of design parameters on the machine performance is discussed and provides insight into the influence of parameters that effect overall power density