Volume 118 No. 19 2018, 1805-1815 ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu ijpam.eu A Study on Distributed and Concentric Winding of Permanent Magnet Brushless AC Motor Jun-Kyu Kang 1, Hong-Sik Lim 2, Ki-Chan Kim* 3 1 Dept. of Electrical Engineering, Hanbat National University, Daejeon, 305-719, South Korea kckim@hanbat.ac.kr 1, here91@naver.com 2, ghdtlr0607@naver.com 3, Corresponding author* Phone:+82-042-821-1090 February 4, 2018 Abstract Background/Objectives: Recently, environmental problems are increasing. As a result, research and development are being actively conducted to replace the existing engine drive system with a motor drive system. Methods/Statistical analysis: In this paper,brushless alternating current (BLAC) motor for neighborhood electric vehicle (NEV) was analyzed. The electrical characteristics of the permanent magnet brushless AC motor according to the winding method are analyzed. A motor of the same size was designed by finite element method (FEM) simulation with distributed winding and concentric winding by changing only the winding method. Findings: Distributed winding has higher winding factor than concentric winding. Distributed winding has a larger No-load back electromotive force (EMF) size than the concentric winding and has a higher output. Therefore, 1 1805
the distributed winding has a large no-load back-emf and a high output. Since the winding is distributed the back- EMF is sinusoidal, so the total harmonic distortion (THD) of the back-emf is small. Improvements/Applications: The NEV runs at low speed.but it is a promising field of study because it is convenient to drive in complex urban areas and research activities are actively conducted. Key Words: BLAC, Concentric winding, Distributed winding, EMF,FEM 1 Introduction Recently, environmental problems caused by the use of fossil fuels and depletion of fossil fuels have become problems 1. This has led to increased interest in environmental issues around the world. In addition, researches are continuously carried out to develop environmentally friendly energy. In the automobile industry, much efforts have been made to reduce the proportion of existing internal combustion engines used in vehicles. A typical example of this is the application of an environmentally friendly motor 2. Research and development are being actively conducted to replace the existing engine drive system with a motor drive system. Permanent magnet synchronous motor (PMSM) is used as a traction motor mounted on hybrid electric vehicle (HEV) and electric vehicle (EV) 3,4. The permanent magnet synchronous motor uses a permanent magnet, so the amount of magnet and the torque ripple are excellent 5. Also, PMSM has different electrical characteristics depending on the winding method of the stator. The distributed windings have lower harmonics than the concentric windings and the waveforms are more sinusoidal 6,7. Especially, the neighborhood electric vehicle (NEV) is operated at low speed, but it is advantageous to drive in a complex city center 8,9,10. In this paper, a 16(kW) BLAC motor used in NEV operating at low speed was studied. In particular, permanent magnet brushless AC motors are widely used for high efficiency, miniaturization, and high power density. In this paper, the electrical characteristics of the permanent magnet brushless AC motor according to the winding method are analyzed. Permanent magnet brushless AC motors 2 1806
of the same size are designed through finite element method (FEM) simulation by changing only the winding method. In the case of concentric winding, the distribution factor is 1 because all the coils have the same EMF. In the case of distributed winding, the coils have the same magnitude. Therefore, the distribution coefficient, flux linkage, back-emf and harmonics for distributed winding and concentric winding are compared. The characteristics of the permanent magnet brushless AC motor according to the winding method are presented through comparative analysis of two models. 2 Analysis Model of BLAC 2.1 Characteristics of BLAC motor design The operating characteristics for designing thebrushless AC motor are shown in Table 1. As shown in Table 1, rated power is 16(kW) and rated speed is 3000(rpm). The finite element method was used to design the distributed winding and the concentric winding through FEM simulation. Table. 1. Driving characteristics 2.2 2D model FEM Simulation Permanent magnet brushless AC motor is designed through FEM. To compare distributed and concentric windings, both models took the same size rotor and stator configuration. Table 2 shows the BLAC design specification. As shown in Table 2, the number of parallel circuits of the two models is 2 and the fill factor is 61.54(%). Figure 1 shows FEM modeling with BLAC design. 3 1807
Table. 2.Design specifications for BLAC motor Fig. 1. 2D FEM model 3 Comparison of BLAC motor characteristics 3.1 Winding and EMF phasor diagram Figure 2 shows the winding diagram. Figure 2(a) shows the distributed winding diagram(phase A) and Figure 2(b) shows the concentric winding diagram(phase A). Figure 3 shows the EMF phasor diagrams of the two models. Figure 3(a) shows the EMF phasor diagram of the distributed winding. Figure 3(b) shows the EMF phasor diagram of the concentric winding. The distribution factor of two models is expressed as equation (1) and the pitch factor is expressed by equation (2). In the case of distributed winding, the phases are shifted from each other by one slot pitch. Using the equation (1), the distribution factor is 0.984. Also, the total phase EMF of the distributed 4 1808
winding is 7.88(V). On the other hand, in the case of concentric winding, the distribution factor is 1 because the EMF of all the coils are in phase with each other. As shown in Figure 2(b), each coil in the pole-group has a different coil-span. The pitch factor of the outer coil is 0.924 when calculated according to equation (2), and the pitch factor of the inner coil is 0.924. The total phase EMF of the concentric winding is 7.39(V). Therefore, at the same turn number and conductor size, the distributed winding has about 6.6(%) higher EMF than the concentric winding. Fig. 2. Winding diagram (a) Distributed winding diagram (phase A)(b) Concentric winding diagram (phase A) 5 1809
Fig. 3. Winding diagram k d = sin( π 2m ) q sin π 2mq (1) 3.1.1 No-load analysis kq = sin(/2) (2) Figure 4 shows a comparison of No-load analysis at 1000(rpm) for both models. Figure 4(a) shows flux linkage. The distributed winding is 0.0287(Wb). Since the concentric winding is 0.0241(Wb), the distributed winding is about 19(%) higher than the concentric winding. Figure 4(b) shows back-emf. The distributed winding is 6.02(V rms ). Since the concentric winding is 5.08(V rms ), the distributed winding is about 19(%) higher than the concentric winding. Figure 4(c) shows the line back-emf. The distributed winding is 7.74(V rms ). The concentric winding is 6.57(V rms ). 6 1810
Fig. 4. Comparison of No-load analysis for two models Finally, Figure 5 shows the harmonic analysis of No-load back- EMF. As a result of THD analysis, distributed winding is 5.64(%) and concentric winding is 10.64(%). Therefore, the distributed winding has lower harmonics than the concentric winding, and the waveform is more sinusoidal. Fig. 5. Harmonic analysis of no-load back-emf 3.1.2 Load analysis Figure 6 shows a comparison of the load analysis in 3000(rpm) for the two models. Figure 6(a) shows back-emf(phase A). The distributed winding is 22.86 (V rms ) and the concentric winding is 19.88 7 1811
(Vrms), so distributed winding is about 15(%) higher than the concentric winding.figure 6(b) shows the line voltage. The distributed winding is 39.41 (V rms ) and the concentric winding is 38.81 (V rms ). Distributed winding has higher voltage than concentric winding. This is because the distributed winding back-emf is large. Fig. 6. Comparison of load analysis for two models Figure 7 shows the harmonic analysis of back-emf. Analysis of THD shows that the distributed winding is 5.85(%) and the concentric winding is 13.33(%). The BLAC requires about 50(Nm) at rated speed 3000(rpm) under load. In the case of distributed winding, the input current for satisfying the torque is 353((A rms ). In the case of concentric winding, the input current for satisfying the torque is 431(A rms ). Therefore, in order to satisfy the same torque, concentric winding shows that the magnitude of applied current is higher than distributed winding. 4 Conclusion Fig. 7. Harmonic analysis of back-emf In this paper, the compared characteristics of BLAC with distributed winding and concentric winding. Distributed winding has 8 1812
a larger No-load back-emf size than the concentric winding and has a higher output. Distributed winding has higher winding factor than concentric winding. Therefore, the distributed winding has a large no-load back-emf and a high output. Since the winding is distributed, the back-emf is sinusoidal, so the THD of the back- EMF is small. Therefore, in order to satisfy the same torque, the magnitude of the applied current is larger in the concentric winding than in the distributed winding. This shows that the concentric winding has higher copper loss than the distributed winding. However, when viewed from the production side, the concentric winding is generally used in induction motors, and in general winding is inserted by an automatic winding machine. Distributed winding is used for large motors by inserting winding coils by hand. As a result, concentric winding uses an automatic winding machine, which makes it easier to produce than distributed winding. Acknowledgment This material is based upon work supported by the Ministry of Trade, Industry & Energy(MOTIE, Korea) under Industrial Technology Innovation Program. No.10063339, Development of 80kW electric traction system with electromagnetic transmission for electric powered vehicle. References [1] Hochang Jung, Deokjin Kim, Chun-Beom Lee, JihyunAhn, Sang-Yong Jung, Numerical and Experimental Design Validation for Adaptive Efficiency Distribution Compatible to Frequent Operating Range of IPMSM. IEEE TRANSACTIONS ON MAGNETICS, 2014, 50 (2). [2] Ki-Chan Kim, A Novel Calculation Method on the Current Information of Vector Inverter for Interior Permanent Magnet Synchronous Motor for Electric Vehicle. IEEE TRANS- ACTIONS ON MAGNETICS, 2014, 50 (2). [3] Sung-Il Kim, Geun-Ho Lee, Jung-Pyo Hong, Tae-Uk Jung, Design Process of Interior PM Synchronous Motor for 42-V Electric Air-Conditioner System in Hybrid Electric Vehicle. IEEE 9 1813
TRANSACTIONS ON MAGNETICS, 2008, 44 (6), pp. 1590-1593. [4] Jung-Min Mun, Gyeong-Jae Park, SangHyeokSeo, Dae-Woo kim, Yong-Jae Kim, Sang-Yong Jung, Design Characteristics of IPMSM With Wide Constant Power Speed Range for EV Traction. IEEE TRANSACTIONS ON MAGNETICS, 2017, 53 (6). [5] Ayman Samy Abdel-Khalik, Shehab Ahmed, Ahmed M. Massoud, Effect of Multilayer Windings With Different Stator Winding Connections on Interior PM Machines for EV Applications. IEEE TRANSACTIONS ON MAGNETICS, 2016, 52 (2) [6] Myung-Seop Lim, Seung-Hee Chai, Jung-Pyo Hong, Design of Saliency-Based Sensorless-Controlled IPMSM With Concentrated Winding for EV Traction. IEEE TRANSACTIONS ON MAGNETICS, 2016, 52 (3). [7] Hyung-Woo Lee, Ki-Doek Lee, Won-Ho Kim, Ik-Sang Jang, Mi-Jung Kim, Jae-Jun Lee, Ju Lee, Parameter Design of IPMSM With Concentrated Winding Considering Partial Magnetic Saturation. IEEE TRANSACTIONS ON MAGNET- ICS, 2011, 47 (10), pp. 3653-3656. [8] Jae-Woo Jung, Sang-Ho Lee, Geun-Ho Lee, Jung-Pyo Hong, Dong-Hoon Lee, Ki-Nam Kim, Reduction Design of Vibration and Noise in IPMSM Type Integrated Starter and Generator for HEV. IEEE TRANSACTIONS ON MAGNETICS, 2010, 46 (6), pp. 2454-2457. [9] Young-Kyoun Kim, Lee Jung Jeong, Se-Hyun Rhyu, In-Soung Jung, A Study on Permanent Magnet Synchronous Motor for Neighborhood Electric Vehicle. IEEE Vehicle Power and Propulsion Conference, 2012, pp. 1081-1085. [10] MarullyTanujaya, Dong-Hee Lee, Jin-Woo Ahn, Design a Novel Switched Reluctance Motor for Neighborhoods Electric Vehicle. 8th International Conference on Power Electronics - ECCE Asia, 2011, pp. 1674-1681. 10 1814
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