DESIGN OF SWITCHED RELUCTANCE MOTOR FOR ELECTRIC VEHICLE

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

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

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

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

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

Contd… Ø Classification of SRM www. technologyfuturae. com 6

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

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

EQUIVALENT CIRCUIT Ø The applied voltage to a phase is equal to, www. technologyfuturae. com 9

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

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

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

Contd… Ø Here a improved stator structure is proposed www. technologyfuturae. com 13

Contd… Ø Example of an SRM design www. technologyfuturae. com 14

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

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

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

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

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, 1145 -1148, 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 www. technologyfuturae. com 19

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