comparison of single layer and double layer winding … · mig 23s other old russian fighters...

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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.asp?JType=IJMET&VType=8&IType=8

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

COMPARISON OF SINGLE LAYER AND

DOUBLE LAYER WINDING IN SURFACE

MOUNTED PMSG FOR AIRCRAFT

APPLICATION

Bharathi Thangaraj

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: Bharathi Thangaraj, 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. 1310–1320.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=8

1. 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 20-60 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

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, 95000 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.

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.

Gear box

coupled

with

aircraft

engine

PMSG Main

exciter

Rotating

rectifier

Alternator Rectifier DC

load

Generator

control unit

Bharathi Thangaraj


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

(Sm2Co17) 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.

(a) (b)

Figure 2 Solid model View of SM-PMSG; (a) Single layer winding (b) Double layer winding

The RMS value of the fundamental component of the generated voltage/phase in PMSG is

given by

E�� 4.44fN��K��Ф�� (1)

Where,

f is frequency of the induced voltage in PMSG, in Hz., Nph is No. of turns in the stator

coils per phase, Kw1 is fundamental harmonic winding factor, ΦPM is flux per pole of the

permanent magnet in weber.

Percentage of Armature Reaction MMF is given by

%F �� ∅��

�� (2)

Where,

Iph is phase current in amps, Ntc and Ncp 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 !"� %

&'()�*

&+ (3)

Where

Rs is stator winding resistance per phase, Iabc is stator phase current, Vabc is stator phase

voltages and λabc 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.


Application


V&� = R�i&

� + &'-

*

&+− ω0λ&

� (4)

V2� = R�i2

� + &'3

*

&+− ω0λ2

� (5)

Where

Vsd and V

sq are the d-q-axis stator voltages, i

sd and i

sq are the d-q-axis stator currents, λ

sd

and λsq are the d-q-axis stator Flux linkages, Rs is stator resistance and ωe is the electrical

speed in rad/s.

The expressions for flux linkage are

456 = 7585

6 + 49 (6)

4:6 = 7:8:

6 (7)

The expressions for length of the magnet are

L� ==

?@ (8)

Where,

Bg is gap flux density, Lg is air gap length and Hm is field intensity of the magnet.

The expressions for magnet pole area are

A� =

Bharathi Thangaraj


Table 1 Parameters of the PMSG.

Parameters Values

Rated Power, (W) 63

Rated DC Voltage, Vdc (V) 14.83

Phase Current, Iph (A) 4.23

Stator Outer Diameter, ods (mm) 108

Rotor Outer Diameter, odr (mm) 78.5

Length of the Air gap, Lg (mm) 0.6

Speed, N (rpm) 9500

Number of Slots, S 9

Number of Poles, P 8

Power Factor 0.88

Flux/Pole, (kMax) 6.62

Total Losses, (W) 21.24

Efficiency, (%) 85.5

3. 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 (θ0) = θ� ×�

�

Where, θ� = Mechanical degree, P = number of poles

Mechanical degree (θ�) = θ0 ×�

�

Where, θ0 = Electrical degree, P = number of poles

(θ�) = 120° ×

�

Q = 30 degree


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 bottom.

Windings Total Number of Stator Slots

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

(a) Single layer winding methodology

Windings Total Number of Stator Slots

Slot 1 Slot 2 Slot 3 Slot 4 Slot 5 Slot 6 Slot 7 Slot 8 Slot 9

R R1

bottom R6 top R2 top

R3

bottom R4 top

R5

Bottom

Y Y4 top Y5

bottom

Y1

bottom Y6 top Y2 top

Y3

Bottom

B B3

bottom B4 top

B5

bottom

B1

bottom B6 top B2 top

Table 2 winding methodology; (b) Double layer winding methodology

(a) (b)

Figure 3 Three phase winding technique (a) Single layer winding (b) 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/m2

for single layer winding SM-PMSG, Maximum flux produced by double layer winding SM-

PMSG at 9500 rpm is 1.84 Wb/m2, 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

Bharathi Thangaraj


there will be no leakage occurs in the outer periphery, air gap as well as shaft of the SM-

PMSG

(a) (b)

Figure 4 Magnetic flux distribution; (a) Single layer winding (b) 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.

(a) (b)

Figure 5 No load voltage waveform for all 3 phases, (a) Single layer winding, (b) double layer

winding

(a) (b)

Figure 6 No load current waveform for all 3 phases, (a) Single layer winding, (b) double layer

winding


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

(a) (b)

Figure 7 The flux linkage for all three phases; (a) Single layer winding (b) 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 0.00025 Wb, in double

layer coil maximum flux linkage occurs is 0.00075 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 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.

(a) (b)

Figure 8 SM-PMSG connected with resistive load (a) single layer winding (b) 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 14.189 Volts and maximum of 3.7486 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 14.83 Volts and maximum

DC current of 4.23 Amps

Bharathi Thangaraj


(a) (b)

Figure 9 single layer winding (a) DC voltage (b) DC current at 9500 rpm

(a) (b)

Figure 10 Double layer winding (a) DC voltage (b) 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 20.218 degree Celsius occurs at edges of

stator teeth and surface of Permanent Magnet, in double layer winding design carries

maximum heat of 20.217 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.


Application


(a) (b)

Figure 11 (a) Temperature of SM-PMSG at 9500 rpm, (a) Single layer winding (b) Double layer

winding

Parameter Single layer winding SM-PMSG Double layer winding SM-PMSG

DC voltage 14.189 Volts 14.83 Volts

DC current 3.74 Amps 4.23 Amps

Power 53.0668 Watts 62.7 Watts

Losses 22.7 Watts 21.24 Watts

Temperature 20.217 degree celsius 20.213 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] https://en.wikipedia.org/wiki/HAL_Tejas

[2] http://www.tejas.gov.in/

Bharathi Thangaraj


[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-49-61.

[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-1246-1250.

[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. 22315284, 2012.

[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. 12211227, 2012.

[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. 1883-1887, 2010.

[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. 911-914, 2012.

[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. 674681, 2008.

[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. 34- 44.

[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. 457–469

[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. 264–272.

comparison of single layer and double layer winding … · mig 23s other old russian fighters...

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