1. DESIGN OF SWITCHED RELUCTANCE MOTOR FOR ELECTRIC VEHICLE
VIJITH K
Edited By
Sarath S Nair

2. OUTLINE INTRODUCTION SWITCHED RELUCATNCE MOTOR PRINCIPLE OF OPERATIONS
EQUIVALENT CIRCUIT
DESIGN CONSIDERATIONS
FINITE ELEMENT ANALYSIS
DESIGN OF SRM FOR EV
CONCLUSIONS
REFERENCES

3. INTRODUCTION High mileage and low emission vehicle – HEV, EV
Motor for EV – Cost, Weight, Efficiency
Switched reluctance motors are a good choice for an electric vehicle
SRM rotates due to reluctance torque , originates from change of resistance of the magnetic circuit
Advances in power electronics made SRMs an attractive candidates for EV
Finite element analysis

4. SWITCHED RELUCTANCE MOTOR
The reluctance motor is a type of synchronous machine
Torque is produced by the tendency of its moveable part to move to a position where the inductance of the excited winding is maximized
The machine is a doubly salient machine
The rotor is aligned whenever the diametrically opposite stator poles are excited

5. Contd… Operation of switched reluctance motor
(a) Phase c aligned and (b) Phase a aligned

6. Contd…
Classification of SRM

7. PRINCIPLE OF OPERATION
Torque production - Principle of electromechanical energy conversion
The incremental mechanical energy,
ΔWm = TeΔθ
Te =ΔWm/Δθ
When the mmf is constant, the incremental mechanical energy is equal to the change in magnetic coenergy
ΔWm = ΔW′f

8. Contd… W′f = (½) L(θ, i) i2 Te =(ΔWm/Δθ) = (ΔW′f /Δθ) = (∂W′f / ∂θ)
∂θ 2

9. EQUIVALENT CIRCUIT The applied voltage to a phase is equal to,

10. Contd… The equivalent circuit for one phase of the SRM
Mutual inductance neglected

11. Contd… q-d axis voltage equations are, Vq = rs iq + ω ʎd + p ʎq
Vd = rs id - ω ʎq + p ʎd
Electromagnetic torque is,

12. DESIGN COSIDERATIONS In the general design, β r > β s
Optimal design of the motor is an important way to achieve good performance price ratio
In the SRM design , the requirement of the pole arc for stator and rotor is,
In the general design, β r > β s

13. Contd… Here a improved stator structure is proposed

14. Contd…
Example of an SRM design

15. FINITE ELEMENT ANALYSIS
Design process combines design calculations and finite element analysis
Finite element method - Magnetic field analysis and Heat transfer analysis
ANSYS software – FEM
Static torque calculation,

16. Contd…
The magnetic field analysis is carried out in order to obtain the heat quantity of the coil
The heat transfer between SRM and outside air is done by natural convection

17. DESIGN OF SRM FOR EV Dimension of SRM Moderating ratio
Power rating of SRM and number of motor required
Drive system
Calculation of temperature rise

18. CONCLUSION Basic concepts of switched reluctance motor was discussed
It includes principle of operation, torque and voltage equations and equivalent circuit of SRM
Design considerations of SRM motor for EV was discussed
Basic concepts of Finite element analysis was also discussed

19. REFERENCES
[1] Kazuhiro Ohyama, Maged Naguib F. Nashed, Kenichi Aso, Hiroaki Fujii, and Hitoshi Uehara,Department of Electrical Eng., Fukuoka Institute of Technology, Fukuoka, Japan, “Design Using Finite Element Analysis of Switched Reluctance Motor for Electric Vehicle” IEEE Trans 2006 [2] M. Morimoto, N. Matsui, and Y. Takeda, "Recent Advances of Reluctance Motors", IEEETrans. IA, Vol.119, No.10, , 1999 [3] Li Weili, Sheng Man, Huo Fei, “Optimal design and Finite Element Analysis of Switched Reluctance Motor for Electric Vehicles” , IEEE Vehicle Power and Propulsion Conference (VPPC), September 3-5, 2008, Harbin, China [4] Lisiate Takau, Simon Round, “Design of a Switched reluctance motor for an Electric vehicle” , Department of Electrical and Computer Engineering University of Canterbury

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