apresentação petrov vinicius

LIMC-DEE-CEEI-UFCG

Permanent Magnet applicati ons In Electric Motors

Prof. Dr. Benedito Antonio LucianoPetrov Crescencio Lobo

Vinicius Magno Uchôa Lima Oliveira

DEE – CEEI - UFCG

LIMC-DEE-CEEI-UFCG 2/21

Presentati on Topics

Introduction

Historical review of Permanent Magnet (PM) Technology

Rare-Earth Magnets Considerations

• Definition• Characteristics

Use of PM in electrical machines

• Classification of PM Motors• Benefits using the PM in Motors• Limitations of PM Motors

Conclusions

References


Introducti on

The electrical motors perform a crucial role in the industrial process. They are present in various types of applications such as :

• water pumping, • refrigeration, • ventilation, • material processing• all industrial branches

60/70 per cent of the electrical consumption in the industrial field is dictated by electrical motor systems [1].

In the current scenario where energy conservation is increasingly relevant, researches in the domain of permanent magnets (PM), have contributed to the energy efficiency. [2].

In the past 20 years, with the improvement of the properties of PM materials, and a reduction in its costs, the utilization in electrical motors has become viable, delivering a higher efficiency, with good reliability [3].


Introducti on

Source: IEA 2007

Percentage of different motor systems of total electricity use in United States.


Historical review of PM technology

• Over the past 35 years, researches and developments led to massive changes on PM materials that cover from the basic chemistry, to cost issues.

• The benefits were noticed in the materials properties, such as reduction of cost and a better efficient PM motors [3].

• Alnico and ceramic/ferrite magnet materials were the base of electric motor technology during the early 1940´s to the late 1960´s.

1. Alnico: Achieves high flux densities, but limitation in use for motors due to the poor resistance to demagnetization.

2. Ferrites/Ceramics: These magnets allow the motor to achieve air gap flux densities in higher levels than performed by induction motors. Have shown to be an economical option of PM.



• Around 1970, the first rare-earth materials were introduced:

1. Samarium Cobalt (SmCo5 and Sm2Co17). With these materials, the motor air-gap flux levels achieved were comparable to the levels of the induction motors. Thermal capabilities are outstanding (minimal variation of flux in temperature and maximum temperature capability). Costs limited the use of this PM in simple applications [3].

Source: [3]



• Only in the 1980´s, the costs for rare-earth PM started to reduce (in comparison with samarium cobalt magnets):

1. Neodymium iron boron (Nd2Fe14B). The initial magnets had limitations in temperature capabilities, these magnets had high susceptibility to demagnetization above 1200C. After 15 years, this level raised to 1800C, through improvements of material properties. [3].

Source: [4]


Rare-Earth Magnet Considerati ons

The rare-earth magnets are included in the still growing family of hard magnetic alloys.

• These PM are based on the alloy formed by the junction of 3d-transition metals (TM, notably Co and Fe), with rare-earth elements of the 4f-transition series, the lanthanides Ce, Pr, Nd, Sm, Gd, Dy and others.

• The study of these synthetic metallic substances and their properties began in the 1950´s and continues nowadays. [4].

• Rare-earth magnets have an important role in electric motors applications, such as operating auxiliary devices like windshield wipers, cooling fans, windows, seats, mirrors and roof actuators.

• When the weight and size are important aspects to consider in a project, such as in aerospace applications, dense Sm-Co and Nd-Fe-B are also added.


Rare-Earth Magnet Considerati ons

In Fig.3, is represented the replacement of the wound-field stator by Alnico, then switched to anisotropic ferrite, and finally the use of rare earth permanent magnet:

Source: [4]

The modern step motors use mostly permanent magnet rotors in the called hybrid types (permanent magnet plus toothed iron wheels)


PM Motors

• DC commutator:

1. Stator with permanent magnets2. Rotor with windings3. Brushes + commutator

Source: [13]

Source: [14]

Source: [6]


PM vs Wound Motors

• DC Commutator

Source: [13]

• DC brushless

1. Rotor with permanent magnets2. Stator with windings3. No brushes

• About 90% of troubles in electrical motors issues from sliding brushes.


PM Motors

Source: [14]

Source: [13]

• AC synchronous

PM Motors


Source: [13]

PM Motors


Source: [15]

• Higher efficiency (no electrical losses to maintain motor’s magnetic field).• Higher torque and power density.• Linear torque speed characteristics. (that are more predictable).• Better dynamic performance due to higher magnetic flux density in air gap.• Simplified construction and essentially maintenance-free.• More compact size.

PM Motors benefi ts


Features of various motor types in moti on control apps

LIMC-DEE-CEEI-UFCG 17/21Source: [16]

• The high price for material is affected by many factors in a complex scenario• China dominates the world’s production: about 95%• Rare-earth is a by-product of other metals and minerals mines.

PM Motors Drawbacks


Source: [17]

• Enterprises researches how to make more efficient motors without employing rare earths.

1. Hitachi has made 11 kW motor with amorphous metal2. Toyota started to develop motors with no rare-earth.

PM Motors Drawbacks


Source: [10]Source: [12]

• Energy efficiency• Rare-earth presents the best set for engines performance• Success involves geological and economic realities also

Conclusions



References

[1] T. Fleiter, W. Eichhammer e J. Schleich, Energy efficiency in electric motor systems: Technical potentials and policy approaches for developing countries, Viena: UNITED NATIONS INDUSTRIAL DEVELOPMENT ORGANIZATION, 2011.

[2] J. F. Gieras e M. Wing, Permanent Magnet Motor Technology, New York: Marcel Dekker, 2002. [3] M. J. Melfi, S. D. Rogers, S. Evon e B. Martin, “Permanent Magnet Motors for Energy Savings in Industrial

Applications,” IEEE Transactions on Industry Applications, vol. 5, n. 44, pp. 1360-1366, Sep/Oct 2008. [4] K. J. Strnat, “Modern Permanet Magnets for Applications in Electro-Technology,” Proceedings of the IEEE, vol.

78, n. 6, p. 923, Jun 1990. [5] I. Petrov e J. Pyrhönen, “Performance of low cost permanent magnet material in PM synchronous machines,”

IEEE Transactions on Industrial Electronics, vol. PP, n. 99, 22 Mar 2012. [6] CST AG, “Permanent-Magnet DC Machine Simulation using CST EM STUDIO™,” 19 Feb 2012. [Online]. Available:

http://www.cst.com/Content/Applications/Article/Article.aspx?id=270. [Acesso em 21 11 2012].[7] C. Elanchezhan e G. S. Sundar, Computer Aided Manufacturing, 2nd ed., Laxmi Publications, 2007. [8] H. Oman e R. Simpson-Clark, “Permanent Magnets for Vehicle-Propulsion Motors: Cost/Availability,” em 31st

Intersociety Energy Conversion Engineering Conference, Washington, DC, 1996. [9] W. M. Morrison e R. Tang, “China’s Rare Earth Industry and Export Regime: Economic and Trade Implications for

the United States,” em Congressional Research Service Report for Congress, 2012. [10] Hitachi, Ltd, “Highly efficient industrial 11kW permanent magnet synchronous,” 14 Apr 2012. [Online].

Available: http://www.hitachi.com/New/cnews/120411.html. [Acess in 19 11 2012].[11] Baldor Electric Company, “Rare Earth-Free Traction Motor for Electric Vehicle Applications,” 01 Jan 2012.

[Online]. Available: http://arpa-e.energy.gov/Portals/0/Documents/FundedProjects/REACT%20Slicks/Final_Slick_Baldor.pdf. [Acess in 19 11 2012].

[12] Reuters, “Reuters.com,” 23 Jan 2012. [Online]. Available: http://www.reuters.com/article/2012/01/23/us-toyota-rare-earth-idUSTRE80M0JK20120123. [Acess in 19 11 2012].

[13] Evworks; [Online]. Available: http://www.evworks.com.au/tech/?section=motors [14] Freescale: [Online]. Available: http://www.freescale.com/webapp/sps/site/overview.jsp?

nodeId=0ST2BDF5DC55DC9[15] Motor Trend [Online]. Available: http://wot.motortrend.com/gm-will-build-chevrolet-spark-ev-electric-motor-

domestically-129993.html/[16] J. Puranen, "Induction motor versus permanent magnet synchronous motor in motion control applications: a

comparative study," Lappeenranta University of Technology [Thesis], 2006.[17] Morning Whistle, April 2012. [Online]. Available:

http://www.morningwhistle.com/html/2012/Macro_0425/211984.html.

http://www.evworks.com.au/tech/?section=motors





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•www.dee.ufcg.edu.br/~l imc•[email protected]•petrov. [email protected]•vin ic iusuchoa@gmai l .com

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