Design and Control of the Induction Motor Propulsion of an Electric Vehicle

Transcription

1 Design and Control of the Induction Motor Propulsion of an Electric Vehicle Bekheira aache, Adelaziz Kheloui, Mohamed Benouzid o cite this version: Bekheira aache, Adelaziz Kheloui, Mohamed Benouzid. Design and Control of the Induction Motor Propulsion of an Electric Vehicle. IEEE VPPC 010, Sep 010, Lille, France. pp.1-6, 010. <hal > HAL Id: hal Sumitted on 0 Mar 011 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are pulished or not. he documents may come from teaching and research institutions in France or aroad, or from pulic or private research centers. L archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, puliés ou non, émanant des étalissements d enseignement et de recherche français ou étrangers, des laoratoires pulics ou privés.

2 Design and Control of the Induction Motor Propulsion of an Electric Vehicle B. aache 1,, A. Kheloui and M.E.H. Benouzid 1 1 University of Brest, EA 435 LBMS Rue de Kergoat, CS 93837, 938 Brest Cedex 03, France Electrical Engineering Department, Polytechnic Military Academy, Algiers, Algeria Mohamed.Benouzid@univ-rest.fr Astract his paper deals with a methodology for presizing the induction motor propulsion of an Electric Vehicle (EV). Based on the EV desired performances, the induction motor optimal power can e calculated. he final ojective is to find its minimum weight, volume, and cost that meet the design constraints with minimum power under the European uran (ECE-15) and su-uran (EUDC) driving cycles. he power presizing methodology is validated through extensive simulations for different induction motor-ased EVs using a siding mode control technique. Index erms Electric Vehicle (EV), induction motor, presizing, driving cycle. I. INRODUCION Recently, Electric Vehicles (EVs) including fuel-cell and hyrid vehicles have een developed very rapidly as a solution to energy and environmental prolems. From the point of view of control engineering, EVs have much attractive potential [1]. he shortcomings, which caused the EV to lose its early competitive edge, have not yet een totally overcome. Indeed, EVs have a low energy density and long charging time for the present atteries. herefore, optimal energy management is very important in EVs; in addition optimum design of the electric motor, selection of a proper drive, and optimal control strategy are the other major factors in EVs. Selection of traction motors for the EV propulsion systems is a very important step that requires special attention. In fact, the automotive industry is still seeking for the most appropriate electric propulsion system. In this case, key features are efficiency, reliaility and cost. he process of selecting the appropriate electric propulsion systems is however difficult and should e carried out at the system level. In fact, the choice of electric propulsion systems for EVs mainly depends on three factors: driver expectation, vehicle constraint, and energy source. For EVs propulsion, the cage induction motor seems to e candidate that etter fulfils their major requirements. his is mainly due to its low cost, roustness, highly reliale and free from maintenance []. his paper presents a methodology for presizing the induction motor propulsion of an EV. Based on the EV desired performances, the induction motor optimal power can e calculated. he main ojective ehind is to find its minimum weight, volume, and cost that meet the design constraints with minimum power under the European uran (ECE-15) and suuran (EUDC) driving cycles. II. EV MODELING A. Nomenclature V = vehicle speed; α = Grade angle; P v = Vehicle driving power; F w = Road load; F ro = Rolling resistance force; F sf = Stokes or viscous friction force; F ad = Aerodynamic drag force; F cr = Climing and downgrade resistance force; μ = ire rolling resistance coefficient (0.015 < μ < 0.3); m = Vehicle mass; g = Gravitational acceleration constant; k A = Stokes coefficient; ξ = Air density; C w = Aerodynamic drag coefficient (0. < C w < 0.4); A f = Vehicle frontal area; v 0 = is the head-wind velocity; F = ractive force; k m = Rotational inertia coefficient (1.08 < k m < 1.1); a = Vehicle acceleration; J = otal inertia (rotor and load); ω m = Motor mechanical speed; B = Load torque accounting for friction and windage; L = Load torque; m = Motor torque; i = ransmission ratio; η t = ransmission efficiency; R = Wheel radius; J V (J W ) = Shaft (wheel) inertia moment; λ = Wheel slip. B. Dynamics Analysis his section derives the driving power to ensure vehicle operation (Fig. 1) [3]. 1) Road load and tractive force. he road load consists of Fw = Fro + Fsf + Fad + Fcr (1) he rolling resistance force F ro is produced y the tire flattening at the roadway contact surface. Fro = μmgcos α () /10/$ IEEE

3 y F sf F ro F cr α mg C g F ad F Fro Moving direction F sf -mg Fig. 1. Elementary forces acting on a vehicle. F ad Roadway he rolling resistance force can e minimized y keeping the tires as much inflated as possile. F sf = kv (3) A Aerodynamic drag, F ad, is the viscous resistance of air acting upon the vehicle. 1 F C A V V ad = ξ w f ( + 0) (4) he climing resistance (F cr with positive operational sign) and the downgrade force (F cr with negative operational sign) is given y Fcr =± mgsin α (5) he tractive force in an electric vehicle is supplied y the electric motor in overcoming the road load. he equation of motion is given y dv kmm = F Fw (6) dt x he vehicle gloal inertia moment in the motor referential is given y J = JW + JV 1 R JV = m (1 λ) i III. EV RACION MOOR AND GEAR RAIO DESIGN (11) A. raction Motor Characteristics For EVs propulsion, the cage induction motor seems to e candidate that etter fulfils the major aove-mentioned features []. Figure shows the induction motor drive characteristics that should e dealt with when used as the EV propulsion [4-5]. B. ractive Force and ransmission Requirement he induction motor developed force on the EV driven wheels is expressed y F N m m =η t (1) R where N m is the induction motor speed. he transmission gear ratio i is designed such that the EV reaches its maximum speed at the maximum induction motor speed. Power he net force (F - F w ), accelerates the vehicle (or decelerates when F w exceeds F). ) Motor ratings and transmission. he power required to drive a vehicle has to compensate the road load F w. P v = VF (7) w he mechanical equation (in the motor referential) used to descrie each wheel drive is expressed y dω + + = (8) dt m J B L m he following equation is derived due to the use of a reduction gear. ωm ω Wheel = and Wheel = miη t (9) i he load torque in the motor referential is given y. R i LWheel L = = Fω (10) i orque Base Maximum speed speed Constant torque region Constant power region (a) Electric traction. Power orque Speed () ractive effort versus speed. Fig.. EV typical characteristics. Speed

4 πnm _maxr i = (13) 30V max A high value of this ratio has the advantage of allowing the use of high-speed motors which have a etter power density, ut with the disadvantage of more volume and then higher cost. A good compromise is generally not to exceed a value of i = 10. Moreover, if the induction motor has a wide constant power region, a single-gear transmission would e sufficient for a high-tractive force at low speeds. IV. HE INDUCION MOOR PRESIZING Basic vehicle performance includes maximum cruising speed, gradeaility, and acceleration. he induction motor power presizing (P m ) is done for the following case/vehicle: Acceleration 0-50 km/h in 10 sec on ground level; vehicle mass 1500 kg; rolling resistance coefficient 0.015; aerodynamic drag coefficient 0.3; front area 0.8 m ; maximum speed 10 km/h; maximum speed of the induction motor 3500 rpm; wheel radius m (175/80R14); transmission efficiency (single-gear + differential) 90%; and zero head-wind velocity. In this first presizing stage, the EV operation consists of three main segments: initial acceleration, cruising at the vehicle speed maximum and cruising at maximum gradeaility. A. Initial Acceleration In the case of initial acceleration, the induction motor presizing is ased on two steps: he first one is done under simplifying assumptions (null aerodynamic force). he second one takes into account all EV resistance forces. he solution of (6) uses the ase speed (V ) and the power found in the first step. he oundary conditions of (6) are: at t = 0, V = 0 and at t = t f, V = V cr, where V cr is the cruising speed. Using (6), the EV acceleration time is defined y t a V f k1 = dv (14) 0 F ( kv + k3) Fig. 3. Necessary power: Acceleration from 0 to 50 km/h in 10 sec on ground level. On the other hand, the acceleration force tends to consideraly increase. his will lead to increased propulsion motor size (the torque is an important dimensioning parameter in terms of size and weight). In this case, the first EV ase parameters are the ase speed (V = 0.4V cr = 0 km/h) and the ase power (P = 0.11 kw). Using these ase values, the presizing second step consist in finding (6) numerical solution including all the resistance forces. In this case, the otained initial acceleration time is larger than that specified in the desired performance. he correction of the ase power and speed values are done using an iterative procedure comining analytical numerical solutions. he new value is then: P = 1.06 kw, as illustrated y Fig. 4. B. Cruising at Maximum Vehicle Speed on Ground Level o validate the ase power and speed choices, it is mandatory to evaluate the induction motor power and torque in different operation mode and in particular at maximum vehicle speed (V max ). where V f is the final speed; k 1, k et k 3 are constants values: k 1 = k m m; k = 0.5ξC w A f ; k 3 = mg(sinα + f r cosα). his expression can reformulated as ta k α k = +α log + k 1 τ α k α 1 (15) P V kmvcr with α =, k =, τ = : P is the ase power. kmgv V kg 3 cr cr 3 he analytical solution of (15) is shown y Fig. 3. It illustrates the necessary power-speed profile for the EV initial acceleration in order to otain the induction motor optimal power and ase speed. Figure 4 shows that elow V = 0.4V cr it is not interesting to decrease V ecause the necessary power does not greatly decrease. Fig. 4. Induction motor power: Step 1 (green) and step (lue).

5 he power requirement to cruise at the EV maximum speed can e otained y: 1 PV = ξ C ( ) max wafvmax + mg cos α+ fr sin α Vmax (16) he necessary power at different speed in ground level is illustrated y Fig. 5. he result is otained under a specified gear ratio value and the motor maximum speed. he ase power found in the previous section is then replaced y the new otained one. he new ase speed is otained y the same previous iterative procedure (Fig. 5). he carried out computations illustrate that the needed power motor at 10 km/h is aout.9 kw, in which transmission losses are taken into account. C. Gradeaility Checking he power found in the previous section is ale to propel the EV at a regular highway speed (10 km/h) on a flat road. Using the induction motor torque and speed profiles, the necessary power on a 15% and 10% graded road can e evaluated. Figure 6 indicates that the motor aove calculated power of.9 kw can propel the EV at km/h and km/h on a 15% and 10% graded road, respectively. V. HE NECESSARY POWER USING DRIVING CYCLES Another consideration in the induction motor power presizing is the average power when driving with some typical stop-and-go driving patterns. he average power can e otained y average = r + ξ w f + m 0 0 dv P mgf C A V Vdt k m dt dt (17) It is difficult to descrie the road load and vehicle speed variations in all actual traffic environments accurately and quantitatively. However, some representative driving cycles have een developed to emulate typical traffic environments. Among them, the European Elementary uran cycle (ECE), the su-uran cycle (EUDC) and su-uran cycle for lowpowered vehicles (EUDCL) (Fig. 7) [5]. Figure 8 shows then the EV induction motor necessary power in the case of the European driving cycle with and without regenerative raking. Compared to the needed power shown in Fig. 8, the optimal power found in the previous section is greater and can therefore meet the power requirement in these driving cycles. Fig. 5. he induction motor necessary power for EV maximum speed. Fig. 7. he European ECE + EUDC driving cycle. Fig. 6. he induction motor necessary power for gradeaility. Fig. 8. he induction motor necessary power for the ECE + EUDC driving cycle.

6 VI. EV CONROL ESS USING A PRESIZED INDUCION MOOR he aim of this section is to check the induction motorased EV performance under road load, especially the climing resistance, and then choose the induction motor necessary power to propel the EV in normal driving cycles. For that purpose a sliding mode approach has een adopted to carry-out control tests on three induction motors for different graded road [6]. he acceleration and the corresponding time are defined y the European driving cycle (Fig. 7). Figure 9 shows then the EV acceleration in this driving cycle. Simulations are carried-out on different induction motors with different power ratings. hese simulations use the EV parameters given in section IV. he main ojective here is to find the minimum motor weight, volume and cost that will meet the design constraints with minimum power under the European ECE and EUDC driving cycles. After the average power calculation, the control use standard motors: 15 kw, 37 kw and 75kW. In this case the control is implemented in the extended constant power range. he maximum gradeaility of each motor is otained y an iterative procedure using the EV model as indicated y Fig. 10. his Figure also shows necessary instantaneous and average powers to propel the EV. For the validation of the otained maximum gradeaility, Fig. 11 illustrates the sliding mode control performances of the 37 kw induction motor-ased EV including the 15.6% graded road. As clearly shown y the EV dynamics (Fig. 11.a), the developed torque variations are as large as are the variations of the accelerator pedal and the road profile. Moreover, very speed tracking performances are achieved. his was also the case of the 15 and 75 kw induction motorased EV: he otained results clearly validate the proposed design methodology. VII. CONCLUSIONS A methodology for presizing the induction motor propulsion of an EV was presented. Based on the EV desired performances, the induction motor optimal power can e evaluated. (a) 15 kw induction motor. () 37 kw induction motor. (c) 75 kw induction motor. Fig. 9. EV acceleration in normal driving cycle (ECE + EUDC). Fig. 10. Maximum gradeaility and necessary instantaneous and average powers.

7 APPENDIX RAED DAA OF HE 15 KW INDUCION MOOR 15 kw, 1480 rpm, p = R s = Ω, R r = 0.05 Ω L s = H, L r = H, M = H J = 0.10 kgm², k f = Nms RAED DAA OF HE 37 KW INDUCION MOOR 37 kw, 1480 rpm, p = R s = Ω, R r = Ω L s = H, L r = H, M = H, J = 0.37kg.m², k f = Nm.s RAED DAA OF HE 75 KW INDUCION MOOR (a) the induction motor torque. 37 kw, 1480 rpm, p = R s = Ω, R r = 0.009Ω L s = H, L r = H, M = H J = 1.5 kgm², k f = Nms () Reference and the induction motor speed. Fig. 11. he 37 kw induction motor-ased EV control performances. he main ojective ehind is to find its minimum weight, volume, and cost that meet the design constraints with minimum power under a desired driving cycle (the European one in our case). he presizing methodology has een validated through extensive simulations for different induction motor-ased EVs using a well-estalished advance control technique (the sliding mode). REFERENCES [1] C.C. Chan, he state of the art of electric and hyrid vehicles, Proceedings of the IEEE, vol. 90, n, pp , Feruary 00. [] M. Zeraoulia, M.E.H. Benouzid and D. Diallo, Electric motor drive selection issues for HEV propulsion systems: A comparative study, IEEE rans. Vehicular echnology, vol. 55, n 6, pp , Novemer 006. [3] A. Haddoun, M.E.H. Benouzid and D. Diallo, A loss-minimization DC scheme for EV induction motors, IEEE rans. Vehicular echnology, vol. 56, n 1, pp , January 007. [4] M. Ehsani, K.M. Rahman and H.A. oliyat, Propulsion system design of electric and hyrid vehicles, IEEE rans. Industrial Electronics, vol. 44, n 1, pp. 19-7, Feruary [5] M. Ehsani, Y. Gao, S.E. Gay, A. Emadi, Modern Electric, Hyrid Electric, and Fuel Cell Vehicles: Fundamentals, heory, and Design, CRC Press, 004. [6] M.E.H. Benouzid, D. Diallo, and M. Zeraoulia, Advanced faulttolerant control of induction-motor drives for EV/HEV traction applications: From conventional to modern and intelligent control techniques, IEEE rans. Vehicular echnology, vol. 56, n, pp , March 007.