Assessment criteria of the feasibility of replacement standard efficiency electric motors with high-efficiency motors

Energy-efficient electric motors are gathering an increased attention since they are used in electric cars or to reduce operational costs, for instance. Due to their high efficiency, permanent-magnet synchronous motors are used progressively more. However, the need to use rare-earth magnets for such high-efficiency motors is problematic not only in regard to the cost but also in socio-political and environmental aspects. Therefore, an increasing effort has to be put in finding the best design possible. The goals to achieve are, among others, to reduce the amount of rare-earth magnet material but also to increase the efficiency. In the first part of this multipart paper, characteristics of optimization problems in engineering and general methods to solve them are presented. In part two, different approaches to the design optimization problem of electric motors are highlighted. The last part will evaluate the different categories of optimization methods with respect to the criteria: degrees of freedom, computing time and the required user experience. As will be seen, there is a conflict of objectives regarding the criteria mentioned above. Requirements, which a new optimization method has to fulfil in order to solve the conflict of objectives will be presented in this last paper.

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Numerical and experimental investigation of flow phenomena in rotating step-holes for direct-spray-cooled electric motors

International Journal of Engine Research ◽

10.1177/1468087420918046 ◽

2020 ◽

pp. 146808742091804

Author(s):

Christopher Beck ◽

Jürgen Schorr ◽

Harald Echtle ◽

Jasmin Verhagen ◽

Annette Jooss ◽

...

Keyword(s):

Flow Rate ◽

Electric Motor ◽

Rotational Speed ◽

High Speed ◽

High Efficiency ◽

Volumetric Flow Rate ◽

Dielectric Fluid ◽

Electric Motors ◽

Test Environment ◽

Operating Points

Despite their high efficiency, electric motors are thermally limited in some operating points by several types of losses. Whenever temperature–critical components threaten to overheat, the performance is reduced for component protection (derating). The use of a suitable cooling concept may reduce the derating. The design of efficient cooling concepts of electric motors in traction drives with increased power densities is challenging, caused by the fact that the heat releases in the components vary considerably with the operating point. One option to reduce the temperatures is to place the heat sinks close to heat sources. Therefore, direct spray cooling with nozzles located in the rotor shaft is often used for cooling the end windings. The dielectric fluid (e.g. oil) is introduced into the mainly air-filled interior of the electric motor. In the following study, the behavior of the jet in the rotating step-holes at different volumetric flow rates is examined. To carry out the investigation, a new test rig and a novel optically accessible electric motor were designed. In this specifically designed test environment, the shape of the jets of different operating points is investigated by direct high-speed visualization. The cinematography setup is made of a four-light-emitting diode system in combination with a high-speed camera. A combined approach of experiment and simulation is used to find basic mechanisms of spray formation produced by rotating step-holes. Depending on the volumetric flow rate and the rotational speed, the direction of the oil jet gets more curved in relation to the rotating nozzle after exiting the small bore. If the deflection is large, the jet impinges on the wall of the large bore before reaching the end of the nozzle. The jet formation at the exit of the step-hole is mainly driven by the divergent forces in the liquid caused by impingement and the counteracting Coriolis force. Depending on the volumetric flow rate with constant rotational speed, different cross-sectional shapes of the jet at the exit are observed. These characteristic shapes can be grouped as a round undisturbed jet, strands with a connecting lamella and a C-shaped cross-section.

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THE PERFORMANCE OF CONDENSER UNDER DIFFERENT VEHICLE SPEEDS

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132513500132 ◽

2013 ◽

Vol 21 (02) ◽

pp. 1350013 ◽

Cited By ~ 1

Author(s):

CHIH-CHIU SHEN ◽

JAU-HUAI LU

Keyword(s):

Electric Vehicle ◽

Electric Vehicles ◽

Air Conditioning ◽

High Efficiency ◽

Cooling Capacity ◽

Vehicle Speed ◽

Air Conditioner ◽

Electric Motors ◽

No Emission ◽

Air Conditioning System

Due to the concern in energy shortage and environmental protection, electric vehicle is considered to be a substitute for the conventional gasoline-powered vehicles due to its characteristics of high efficiency and no emission. However, the load of air conditioning causes a serious problem for electric vehicles, especially in tropical and subtropical areas. The compressor of conventional air conditioning system is driven by engine and its speed is thus coupled to vehicle speed. In electric vehicles, the compressor is driven by electric motors and compressor speed could be decoupled to vehicle speed. This mechanism provides an opportunity to improve the energy efficiency of electric vehicle since the operation of air conditioning system may be independent of vehicle speed. The purpose of this paper is to find out the electric fan operation model as vehicle speed is varied. This paper was to establish a theoretical model for the condenser of automotive air conditioner and to conduct simulation to evaluate the effect of vehicle speed on the cooling capacity and sub-cooling of condenser. Results of simulation demonstrated that vehicle with 6 km h-1 speed has the 5°C of sub-cooling at 0.0266 kg s-1 of refrigerant flow rate and the cooling capacity was 4.93 kW. In this study, an increase of 16.6% in cooling capacity can be reached as the speed of vehicle was raised from 6 to 110 km h-1 and can promote the sub-cooling to 19.5°C. It was also found that the cooling capacity of air conditioner is extremely sensitive to vehicle speed while the vehicle is running at low speed. Furthermore, increases in the vehicle speed resulted in reduction of the length of superheat region from 17.5 to 8.5 cm. Finally, a correlation among these variables and the simulated cooling capacity was obtained in this study, enabling the relevant researchers to evaluate automotive air conditioner performance under different vehicle speeds more easily.

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On-line Detection and Classification of PMSM Stator Winding Faults Based on Stator Current Symmetrical Components Analysis and the KNN Algorithm

Electronics ◽

10.3390/electronics10151786 ◽

2021 ◽

Vol 10 (15) ◽

pp. 1786

Author(s):

Przemyslaw Pietrzak ◽

Marcin Wolkiewicz

Keyword(s):

High Efficiency ◽

Dynamic Properties ◽

Stator Winding ◽

Electric Motors ◽

Permanent Magnet Synchronous Motors ◽

K Nearest Neighbors ◽

Short Circuits ◽

Drive Systems ◽

The Impact

The significant advantages of permanent magnet synchronous motors, such as very good dynamic properties, high efficiency and power density, have led to their frequent use in many drive systems today. However, like other types of electric motors, they are exposed to various types of faults, including stator winding faults. Stator winding faults are mainly inter-turn short circuits and are among the most common faults in electric motors. In this paper, the possibility of using the spectral analysis of symmetrical current components to extract fault symptoms and the machine-learning-based K-Nearest Neighbors (KNN) algorithm for the detection and classification of the PMSM stator winding fault is presented. The impact of the key parameters of this classifier on the effectiveness of stator winding fault detection and classification is presented and discussed in detail, which has not been researched in the literature so far. The proposed solution was verified experimentally using a 2.5 kW PMSM, the construction of which was specially prepared for carrying out controlled inter-turn short circuits.

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Analysis Of The Effect Of Frequency Decrease On Performance On Five Phase Induction Motor

Jurnal Mekintek : Jurnal Mekanikal, Energi, Industri, Dan Teknologi ◽

10.35335/mekintek.v12i2.29 ◽

2021 ◽

Vol 12 (2) ◽

pp. 58-64

Author(s):

Suranta Sitorus

Keyword(s):

Induction Motor ◽

High Efficiency ◽

Induction Motors ◽

Electric Motors ◽

Variable Speed ◽

Motor Speed ◽

Variable Speed Drive ◽

Synchronous Motors ◽

Speed Regulation ◽

Motor Tests

Almost 70% of the energy produced by the generator is consumed by electric motors. The use of induction motors in industry and factories is more profitable than DC or synchronous motors, one of the advantages is easy maintenance and high efficiency. On machines in the industry speed regulation is absolutely necessary. Along with the development of power electronics, this has become very easy to do, namely by supplying a motor with a variable speed drive (VSD) inverter. With the supply of a variable speed drive inverter, it is possible to adjust the motor speed by adjusting the voltage frequency.This study was conducted to determine the effect of decreasing the frequency using a variable speed drive inverter on the performance of a five-phase induction motor. Tests are carried out at a frequency of 50 Hz (grid frequency), 35, 40, 45, 50 Hz (inverter frequency) and the motor is loaded at 0.5, 1, 1.5, 2, 2.5Nm. From the research, it was concluded that, among others, the use of a variable speed drive inverter resulted in greater motor losses and the motor produced a louder sound. At the same frequency (50 Hz) the efficiency of the motor is better when supplied directly from the grid.

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Development of Magnetic Material Testing Equipment

Acta Materialia Transilvanica ◽

10.33924/amt-2020-01-06 ◽

2020 ◽

Vol 3 (1) ◽

pp. 33-37

Author(s):

András Nagy ◽

Imre Némedi

Keyword(s):

Magnetic Material ◽

Magnetic Properties ◽

Thin Plate ◽

High Frequency ◽

Small Volume ◽

High Efficiency ◽

Amorphous Structure ◽

Material Testing ◽

Electric Motors

AbstractThis paper deals with the development of equipment that can accurately determine the magnetic properties of small volume thin plate samples. The alloys to be tested are sheets of amorphous structure, such as Finemet alloy, which has excellent high frequency magnetic properties, making it a good candidate for the construction of high efficiency electric motors. This article discusses the components and operation of the equipment under development, whilst giving a brief overview of the efficiency classification of electric motors and the importance of the emerging efficiency class.

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