COMPARISON OF SINGLE LAYER AND DOUBLE LAYER WINDING IN SURFACE MOUNTED PMSG FOR AIRCRAFT APPLICATION

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International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 8, August 2017, pp. 1310 1320, Article ID: IJMET_08_08_133 Available online at http://www.iaeme.com/ijmet/issues.

1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 8, August 2017, pp , Article ID: IJMET_08_08_133 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed COMPARISON OF SINGLE LAYER AND DOUBLE LAYER WINDING IN SURFACE MOUNTED PMSG FOR AIRCRAFT APPLICATION Assistant Professor, Department of Electrical and Electronics, Veltech Dr.RR & Dr.SR University, India ABSTRACT In this paper, the electromagnetic performance of Surface Mounted Permanent Magnet Synchronous Generator (SM-PMSG) with single and double layer windings are compared for aircraft application. The electromagnetic analysis of SM-PMSG is investigated by 2 dimensional transient motion analysis using FEA software. Finally, the overall performance such as electromagnetic analysis, voltage, current, temperature of analytically calculated machine is compared with simulation results. Keywords: Aircraft, SM-PMSG; single layer and double layer winding; Finite Element Analysis software; Electromagnetic and Thermal analysis. Cite this Article:, Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application, International Journal of Mechanical Engineering and Technology 8(8), 2017, pp INTRODUCTION Indian aircraft project is called LCA (Light Combat Aircraft), It is replaced by MiG 21s and MiG 23s other old Russian fighters belongs to second generation design, The new aircraft design is modified by Indian aeronautics limited [1], The aircraft that would spawn from the program was designated the LCA and it would be one of the world s lightest, yet most capable dedicated multi-role aircraft of all time, it is so called as Fourth generation aircraft [2] In LCA KVA generator provided electrical power supply for aircraft electrical loads, during emergency conditions if this power system fails means in order to provide backup power supply IGS (Integrated Generator System) is used, IGS provides emergency loads such as landing, cockpits, cabin lighting, gunshots and food preparation, etc. Electrical machines are playing a vital role in the development of Aircrafts. Multi stage generator system act as a backup power supply unit to the Aircrafts. This generator system gets the mechanical input from the aircraft engine through the Aircraft mounted auxiliary gearbox (AMAGB). A common shaft connects all the three integrated machines in this editor@iaeme.com

2 Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application generator system [2-4]. In general, the speed of modern aircraft generators lies from 7000rpm to 24000rpm and output power is from 30W to 250KW. The traditional civil aircrafts have two main distribution power busses such as high power 3Ф, 115V Ac, 400Hz and low power 28V DC [5]. Normally, PMSG is one of the machines used in the multistage generator system for aircraft power supply. The main advantage of this machine is to eliminate slip rings & brushes. In addition, it has the advantages of high power density and better heat dissipation capability. Due to its self-excitation capability, high PF & efficient operation is possible and the machine has the capability of overloading & handling full load at a very low speed operation [6-9]. In this paper, the entire model of 63W/14.83 V, RPM permanent magnet synchronous generator designed theoretically. The Electromagnetic and Thermal analyses of PMSG carried out using the software of 2D-transient finite element analysis. At last, the overall performance of the machine compared with the single and double layer coil. The organization of the paper is as follows: Second section deals with description of overall system, modeling and design parameters. The simulation analysis is given in section III. The work is concluded in section IV. 2. SYSTEM DESCRIPTION 2.1. Integrated Generator System The objective of the Integrated Generator System is to provide dc power for the different loads in the aircraft. The structure of such an Integrated Generator System is shown in Figure 1. Gear box coupled with aircraft engine PMSG Main exciter Rotating rectifier Alternator Rectifier DC load Generator control unit Figure 1.General structure of Integrated Generator System. The Integrated Generator System comprises of three integrated machines. They are Permanent Magnet Synchronous Generator (PMSG), Main Exciter (ME) and Main Generator (MG). All the three machines mounted on a common shaft and coupled to the aircraft engine through a gearbox. The AC output voltage of PMG rectified by Generator control unit (GCU) for exciting the field winding of the main generator. The rectified output of GCU is a regulated DC voltage, which will apply to field windings of the main exciter. The main exciter generates ac voltage which is then rectifies by a rotating rectifier in to constant dc voltage output. The output voltage of the main generator regulates by the main exciter. The output of the main generator rectified using 12-pulse AC DC converters in to 28V DC, which will supply to an emergency DC load bus of the aircraft. The generator incorporates with forced air-cooling and operates at high speed, high ambient temperature and handles very high current editor@iaeme.com

High-energy samarium cobalt (Sm 2 Co 17 ) used as permanent magnets on the rotor. The design consideration of the SM- PMSG is to meet the power requirement of aircraft.

3 2.2. Mathematical Modeling of SM-PMSG In this section, an accurate model of PMSG modeled to satisfy the need in the aircraft application. The PMSG has nine stator slots and 8 rotor poles, as shown in (Figure 2). The stator has winding and the rotor carries permanent magnet. High-energy samarium cobalt (Sm 2 Co 17 ) used as permanent magnets on the rotor. The design consideration of the SM- PMSG is to meet the power requirement of aircraft. The magnets on the rotor mounted in such a way that the leakage flux is less and the working flux is high. Cold rolled Steel uses for stator/rotor laminations with 0.35mm thickness. Figure 2 Solid model View of SM-PMSG; Single layer winding Double layer winding The RMS value of the fundamental component of the generated voltage/phase in PMSG is given by E 4.44 f N K Ф (1) f is frequency of the induced voltage in PMSG, in Hz., N ph is No. of turns in the stator coils per phase, K w1 is fundamental harmonic winding factor, Φ PM is flux per pole of the permanent magnet in weber. Percentage of Armature Reaction MMF is given by %F (2) I ph is phase current in amps, N tc and N cp is number of turns per coil and number of coils per pole respectively, Ф is power factor angle, A is number of parallel paths, P is number of rotor poles. The state vector form of the stator voltages in general can be expressed as in Eq. (3), V!" R I!" % &' * () &+ Where R s is stator winding resistance per phase, I abc is stator phase current, V abc is stator phase voltages and λ abc is Flux linkage with the stator coils. The stator voltage equations in synchronous reference frame is given as in Eq. (4) & (5) respectively for d-axis and q-axis. (3) editor@iaeme.com

4 Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application V & = R i & + &' - * &+ ω 0λ & V 2 = R i 2 + &' 3 * ω &+ 0λ 2 (5) Where V s d and V s q are the d-q-axis stator voltages, i s d and i s q are the d-q-axis stator currents, λ s d and λ s q are the d-q-axis stator Flux linkages, R s is stator resistance and ω e is the electrical speed in rad/s. The expressions for flux linkage are = (6) 4 : 6 = 7 : 8 : 6 (7) The expressions for length of the magnet are L = < => = B g is gap flux density, L g is air gap length and H m is field intensity of the magnet. The expressions for magnet pole area are (4) A = < = = Where A g is air gap area and B m is flux density of the magnet. The expressions for mass of the magnet are (9) m= CDE < (10) F G r is radius of the magnet, B is magnetic flux density of the magnet and μ I is permeabilitywhere L d and L q are inductances along d-axis and q-axis and λ m is the flux linkage due to permanent magnet. Total mass of the machine in kilogram(kg)is given by M tot = M ts +M cs +M ir +M sr +M m +M con (11) M ts is Mass of the stator teeth in kg, M cs is Mass of the stator core in kg, M ir is Mass of the rotor iron in kg, M sr is Mass of the rotor shaft, M m is Mass of the magnet in kg, M con is Mass of the conductor in kg, Total loss of the machine in watts is calculated as L tot =L cop +L core +L teeth +L fri (12) L cop is three phase copper loss in watts, L core is Core loss in watts, L teeth is Stator teeth loss in watts, L fri is Frictional & windage loss in watts Design Specifications In this section, the PMSG designed by applying standard design expression available in the literature. The machine designed to meet the power output specifications for an aircraft. The specifications of such a design listed in Table 1.It is clear from the design parameters that the machine subjected to operate at two different winding techniques and also with different temperatures changes editor@iaeme.com

5 Table 1 Parameters of the PMSG. Parameters Values Rated Power, (W) 63 Rated DC Voltage, V dc (V) Phase Current, I ph (A) 4.23 Stator Outer Diameter, ods (mm) 108 Rotor Outer Diameter, odr (mm) 78.5 Length of the Air gap, L g (mm) 0.6 Speed, N (rpm) 9500 Number of Slots, S 9 Number of Poles, P 8 Power Factor 0.88 Flux/Pole, (k Max ) 6.62 Total Losses, (W) Efficiency, (%) SIMULATION ANALYSIS In this section, the design of PMSG discussed. In the finite element method, a given system divides into finite elements called meshes and an approximate solution of the problem developed in each phase. This method allows accurate representation of complex geometrics & inclusion of dissimilar materials. It enables accurate representation of the solution within each element to bring out all local effects. The design parameters evaluated in section 2 is modeled and simulated in the FEM environment using MagNet and ThermNet packages. 3.1 Electromagnetic analysis of SM-PMSG In this electromagnetic analysis is carried out using MagNet software 7.2, it is a powerful simulation software used to carried out nonlinear elements with complicated structure, In preprocessor used to design generator and also applying materials, in this PMSG have 9 stator slots with cold rolled steel material, 8 rotor poles with samarium cobalt material and winding carries copper material, in the postprocessor carries simulation of mesh analysis with size of 2mm; if size reduced below means chances for overlap occurs and 2d transient analysis for time period of 10secs,with time step of one The developed SM-PMSG provide power supply of 63 W,14.83 V at 9500 rpm to GCU, in this simulation is carried out for single layer winding and double layer winding with all parameters as same. Figure 3 shows the winding technique carried out for single layer and double layer winding technique. In single and double layer winding technique winding has to be make without overlapping, In order to provide 120 degree for winding [R Y B], calculation has made by slots/poles (9/8=1.2) is 1.2,it is rounding into 2.mechanical degree calculation is carried out with this formula Electrical degree (θ 0 )=θ θ = Mechanical degree, P = number of poles Mechanical degree (θ )=θ 0 θ 0 = Electrical degree, P = number of poles (θ )=120 = 30 degree Q editor@iaeme.com

Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application The winding technique

winding and it helps to produce more uniform flux distribution.

coil but in double layer winding two coils are wounded by top and.

B3 B1 B2 Single layer winding methodology Windings R Y B Total Number of Stator Slots Slot 1 Slot 2 Slot 3 Slot 4 Slot 5 Slot

Table 2 winding methodology; Double layer winding methodology Figure 3 Three phase winding technique Single layer winding

Mounted Permanent Magnet Synchronous Generator at 9500 rpm is 1.

6 Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application The winding technique according to slot pitch for both single layer and double layer is shown below in the table 2, there will be no overlap in the winding and it helps to produce more uniform flux distribution. This table shows how the winding is carried out for all three coils [R Y B], for single layer winding each slot has only one coil but in double layer winding two coils are wounded by top and. Total Number of Stator Slots Windings Slot 1 Slot 2 Slot 3 Slot 4 Slot 5 Slot 6 Slot 7 Slot 8 Slot 9 R R1 R2 R3 Y Y1 Y2 Y3 B B3 B1 B2 Single layer winding methodology Windings R Y B Total Number of Stator Slots Slot 1 Slot 2 Slot 3 Slot 4 Slot 5 Slot 6 Slot 7 Slot 8 Slot 9 R1 Y4 top R6 top B3 R2 top Y5 Y1 B4 top R3 Y6 top Y2 top B5 R4 top B1 Y3 Bottom B6 top R5 Bottom B2 top Table 2 winding methodology; Double layer winding methodology Figure 3 Three phase winding technique Single layer winding Double layer winding Maximum flux distribution is shown in the figure 4, it shows that maximum flux produced by Surface Mounted Permanent Magnet Synchronous Generator at 9500 rpm is 1.79 Wb/m 2 for single layer winding SM-PMSG, Maximum flux produced by double layer winding SM- PMSG at 9500 rpm is 1.84 Wb/m 2, both in single layer and double layer maximum flux produced at edges of the stator teeth. There will be uniform flux distribution occurs and also editor@iaeme.com

there will be no leakage occurs in the outer

Figure 4 Magnetic flux distribution; Single layer

of the unloaded SM-PMSG at 9500 rpm is shown in

that voltage induced is sinusoidal and the

Figure 5 No load voltage waveform for all 3

winding Figure 6 No load current waveform for all

7 there will be no leakage occurs in the outer periphery, air gap as well as shaft of the SMPMSG Figure 4 Magnetic flux distribution; Single layer winding double layer winding The voltage waveform of the unloaded SM-PMSG at 9500 rpm is shown in the figure 5, from the waveform it is observed that voltage induced is sinusoidal and the maximum voltage obtained is 2 volts in the single layer winding and 7.2 volts in the double layer winding. Figure 5 No load voltage waveform for all 3 phases, Single layer winding, double layer winding Figure 6 No load current waveform for all 3 phases, Single layer winding, double layer winding editor@iaeme.com

Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application During No load condition current

at 9500 rpm produced 1.2 Amps during no load condition, in double layer winding SM-PMSG at 9500 rpm produced 3.

shown in the figure 7, from the flux linkage waveform, it is observed that flux distribution occurs sinusoidal uniformly, maximum flux

00075 Wb The output of SM-PMSG is AC but Generator Control Unit (GCU) requires DC input, so output of SM-PMSG is converted to DC by

2 ohms resistor, figure 8 shows the diode bridge rectifier circuit for single and double layer winding, this circuit is available in MagNet

The rectified DC output voltage and DC current waveform is shown in the figure 9, from the waveform observes that single layer SM-PMSG at

8 Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application During No load condition current waveform is sinusoidal it is shown in the figure 6,from the waveform observed that maximum current obtained for single layer winding SM-PMSG at 9500 rpm produced 1.2 Amps during no load condition, in double layer winding SM-PMSG at 9500 rpm produced 3.5 amps Figure 7 The flux linkage for all three phases; Single layer winding double layer winding The flux linkage for all three phases is shown in the figure 7, from the flux linkage waveform, it is observed that flux distribution occurs sinusoidal uniformly, maximum flux linkage occurs in the SM-PMSG at 9500 rpm in single layer coil is Wb, in double layer coil maximum flux linkage occurs is Wb The output of SM-PMSG is AC but Generator Control Unit (GCU) requires DC input, so output of SM-PMSG is converted to DC by connecting diode bridge rectifier with 3.2 ohms resistor, figure 8 shows the diode bridge rectifier circuit for single and double layer winding, this circuit is available in MagNet software. Figure 8 SM-PMSG connected with resistive load single layer winding double layer winding. The rectified DC output voltage and DC current waveform is shown in the figure 9, from the waveform observes that single layer SM-PMSG at 9500 rpm produces maximum DC voltage of Volts and maximum of Amps DC current, figure 10 shows the rectified maximum DC voltage and DC current of double layer winding SM-PMSG at 9500 rpm, from the waveform observes that maximum DC voltage of Volts and maximum DC current of 4.23 Amps editor@iaeme.com

Figure 9 single layer winding DC voltage DC

winding DC voltage DC current at 9500 rpm 3.

deals with the thermal analysis of machine; the

directly or implemented with the ThermNet

This analysis shows the temperature of SM-PMSG

out the main sources of heat, figure 11 shows

and double layer winding, from the temperature

design carries maximum temperature of 20.

teeth and surface of Permanent Magnet, in double

217 degree Celsius occurs at conductors,edges of

conductor carries maximum heat because it carries

9 Figure 9 single layer winding DC voltage DC current at 9500 rpm Figure 10 Double layer winding DC voltage DC current at 9500 rpm 3.2 Thermal analysis SM-PMSG This section fully deals with the thermal analysis of machine; the designed SM-PMSG in MagNet software is coupled directly or implemented with the ThermNet software. This analysis shows the temperature of SM-PMSG generated during different time period and find out the main sources of heat, figure 11 shows temperature flow of SM-PMSG for both single layer and double layer winding, from the temperature flow figure observes that single layer winding design carries maximum temperature of degree Celsius occurs at edges of stator teeth and surface of Permanent Magnet, in double layer winding design carries maximum heat of degree Celsius occurs at conductors,edges of stator teeth, surface of Permanent Magnet, conductor carries maximum heat because it carries higher current than single layer winding, so high temperature occurs at conductor side editor@iaeme.com

Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application Figure 11 Temperature of SM-PMSG at 9500 rpm, Single layer winding Double layer

7 Watts 21.24 Watts Temperature 20.217 degree celsius 20.213 degree celsius Efficiency 84.2 % 85.

winding produces 63 Watts power during simulation and also temperature of machine comes within the 30 degree celsius limit, double layer winding is suitable to operate at high speed

83 V single layer and double layer SM-PMSG is designed for 9500 rpm for Integrated Generated System provides safe and efficient operation of the Aircrafts, Electromagnetic analysis of

Double layer winding produces 63 W and its thermal performance also comes within the limit.

10 Comparison of Single Layer and Double Layer Winding In Surface Mounted Pmsg for Aircraft Application Figure 11 Temperature of SM-PMSG at 9500 rpm, Single layer winding Double layer winding Parameter Single layer winding SM-PMSG Double layer winding SM-PMSG DC voltage Volts Volts DC current 3.74 Amps 4.23 Amps Power Watts 62.7 Watts Losses 22.7 Watts Watts Temperature degree celsius degree celsius Efficiency 84.2 % 85.5 % Table 3 Performance comparison From the above simulation result for the constrained dimension of SM-PMSG for single layer winding and double layer winding shows that double layer winding produces 63 Watts power during simulation and also temperature of machine comes within the 30 degree celsius limit, double layer winding is suitable to operate at high speed operation with required dimension 4. CONCLUSION In this paper 63 W/14.83 V single layer and double layer SM-PMSG is designed for 9500 rpm for Integrated Generated System provides safe and efficient operation of the Aircrafts, Electromagnetic analysis of SM-PMSG for electromagnetic flux distribution, voltage and current using MagNet software, The temperature analysis of SM-PMSG is simulated using ThermNet software, after that analysis Double layer winding produces 63 W and its thermal performance also comes within the limit. Finally the overall performance of the PMSG is better and efficient at high speed operation, this kind of efficient generator is most commonly used in Aircraft, marine industry and flywheel energy storage applications. The performance of outer rotor Permanent Magnet Synchronous Generator for aircraft application will be studied in the future. REFERENCES [1] [2] editor@iaeme.com

11 [3] Brahim L. Chikouche, Kamel Boughrara and Rachid Ibtiouen (2015), Cogging torque minimization of surface mounted Permanent Magnet Synchronous Machines using hybrid magnet shapes, Progress in electromagnetics research, Volume. 62, pp [4] Lijun zhou, Yongwei Geng and Zhuoran Zhang (2015), Comparative study on concentrated winding on permanent magnet synchronous machines with different rotor structures for aircraft generator application, ICEMS, October 25-28, pp [5] Rahul Singh, Vinit Chandray Roy and C.K.Dwivedi, Speed control of permanent magnet synchronous motor drive using an inverter, International Journal of Electrical and Electronics Engineering, Volume. 1, pp , [6] Mohammad S Widyan and Rolf E Hanitsh, High power density radial flux permanent magnet sinusoidal three phase three slot four pole electrical generator, Electrical power and Energy systems, Volume. 43, pp , [7] Guannan Duan, Haifeng Wang, Hui Guo and Guobiao Gu, Direct drive permanent magnet wind generator design and electromagnetic field finite element analysis, IEEE transactions on applied superconductivity, Vol. 20, pp , [8] Jae Woo Jung, Byeong Hwa Lee, Do Jin Kim, Jung Pyo Hong, Jae Young Kim, Seong Min Jeon and DoHoon Song, Mechanical stress reduction of rotor core of interior permanent magnet synchronous generator, IEEE Transactions on Magnetics, Volume. 48, pp , [9] Sandra Eriksson, Andreas Solum, Mats Leijon and Hans Bernhoff, Simulations and experiments on a 12 kilowatts direct driven PM synchronous generator for wind power, Renewable Energy, Volume. 33, pp , [10] Salon S. J, Finite Element Analysis of Electrical Machines, The springer International Series in Engineering and Computer Science (1995). [11] Sawhney A. K, Course in Electrical Machine design, Dhanpat rai & sons publications, Sixth edition (2006). [12] : S. P. Chaphalkar and V. S. Byakod, Design and Analysis of Bridge with Two Ends Fixed on Vertical Wall Using Finite Element Analysis, International Journal of Civil Engineering and Technology, 7(2), 2016, pp [13] A. Sreenivasa Rao and K Venkata Rao. A Study on Machining Characteristics in Milling of Ti-6Al-4V using Experimental and Finite Element Analysis. International Journal of Civil Engineering and Technology, 8(7), 2017, pp [14] M. Senthil Kumar, R. Ramesh Kumar, Mathew Alphonse and K Karthik. Design and Analys of Knuckle Streering using Finite Element Analysis International Journal of Mechanical Engineering and Technology, 8(6), 2017, pp editor@iaeme.com

THE UNIVERSITY OF BRITISH COLUMBIA. Department of Electrical and Computer Engineering. EECE 365: Applied Electronics and Electromechanics

THE UNIVERSITY OF BRITISH COLUMBIA Department of Electrical and Computer Engineering EECE 365: Applied Electronics and Electromechanics Final Exam / Sample-Practice Exam Spring 2008 April 23 Topics Covered: