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

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

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 www.technologyfuturae.com

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 www.technologyfuturae.com

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

Contd… Classification of SRM www.technologyfuturae.com

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 www.technologyfuturae.com

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

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

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

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

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 www.technologyfuturae.com

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

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

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, www.technologyfuturae.com

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 www.technologyfuturae.com

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 www.technologyfuturae.com

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 www.technologyfuturae.com

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

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