DEVELOPMENT TRENDS IN THE ELECTRIC MOBILITY

Transcription

1 Zeszyty problemowe Maszyny Elektryczne Nr 00/203 cz. II 43 Anré Fischer Patrick Seibt Institute of Electrical Drives an Mechatronics, Electrical Engineering Department, TU Dortmun University, Dortmun, DEVELOPMENT TRENDS IN THE ELECTRIC MOBILITY Abstract: The goal of the German Government is to bring one million electrical vehicles on German streets until For this reason in Dortmun the center of excellence TIE-IN (Technology platform for interoperable electro mobility, Infrastructure an Gris) is foune. In this paper concepts for the evelopment of electrical rive chains are escribe. One research approach for testing electrical vehicles is the use of a special power absorption roller, which is able to emulate up an ownhill rives for testing the vehicle ynamics an the recuperation ability. Another concept for testing electrical rives is the use of a test station for the automotive rive chain. With this test bench the behavior of single components like the electrical machine or power electronics an their coaction are analyze. Simultaneously a simulation library for electrical vehicles is evelope. With this library it is possible to simulate single components, the electrical rive chain or the whole electric car in avance. The comparison with the test station allows efining higher graes of simulation moels. Keywors: electric vehicle/car, electrical machines, electrical rive chains, moeling, simulation. Introuction As in current stuies escribe [] the market penetration of electrical vehicles is highly epening on customer acceptance influence by battery cost an range. Therefore, researchers at TU Dortmun are eveloping further strategies to increase the efficiency over a wie operating area of rive chain. In this context our research group at the Institute of Electrical Drives an Mechatronics aims to optimize interaction between motor, power electronics an batteries to increase holistic machine efficiency. The next step is to reuce power requirement of electric vehicles by using the maximum recuperation potential, supporte by kinetic energy, to increase operating range of battery cars. To investigate these goals, in the framework Project TIE-IN, a special concept of power absorption roller for electrical riven motorcars is use. The ifferences between the requirements of conventional motor power testing stations an power absorption rollers are the result of motor characteristics. Compare to combustion engines, electrical rive systems are able to provie a high torque at low spee. Concurrently they have got lower moments of inertia at the rive shaft than combustion engines. In the rive chain of the vehicle, reliable cooling not only has to be ensure uring emulation of long uphill rives. By constructing cooling systems for electrical rive chains in automotive there has to be consiere, that a quantity of heat is converte by recuperating process on ownhill rives. When the temperature in traction motor rises above a critical limit, e.g. permanent magnets of synchronous machine will be estroye irretrievable. An avantage of power absorption rollers is, to emulate interaction between components of electrical rive chains uner consistent laboratory conitions. This approach provies an objective benchmarking of ifferent cooling strategies. In [2] the possibility of a consistent evaluation environment is escribe, to use it in every step of evelopment. To esign components cost an time-effective the approach of frontloaing is pursue. Necessary changes can be etecte at an early instant of time. This approach provies manageability of evelopment costs an number of prototypes. To permute frontloaing, a 00 % correlation between ynamometer results an complete chain of evelopment is necessary. For this reason the gaine results o not only have to be reproucible, but only close to reality riving resistances are emulate by a polynomial approximation by power absorption roller. Driving resistances of vehicles are calculate by concentrate loas. These are: resistance of rolling F roll, air resistance F air,

2 44 Zeszyty problemowe Maszyny Elektryczne Nr 00/203 cz. II acceleration resistance F acc an the resistance of slope F sl (Fig. ). Fig.. Driving resistances at simulation of realistic ambient conitions Fres Froll Fair Facc Fsl (5) 2. Test station concept for components The test station is built as a moular concept for analyzing electrical an electromechanical vehicle components. It is possible to analyze single components e.g. the power electronics or electrical machines just like the whole electrical rive chain at any operation point. The structure of an electrical vehicle rive chain, as seen in Fig. 2, consists of a battery pack, DC/DC- an DC/AC-Converters an at least one electrical machine. The mechanical parts are particularly gearboxes, ifferentials an wheels. For the test station the battery pack an the DC/DC-Converter are both replace by one High Voltage DC- Source. The resistance of rolling F mgc cos roll () epens on the vehicle-mass m, the resistance coefficient c an the angle of elevation. A first approximation for air resistance is: Fair cw AF v v a ² (2) 2 where cw means air coefficient, air ensity, A F effective face of vehicle, v velocity of vehicle an air velocity v a. The engine also has to get overcome the resistance by accelerating the car n J i v Fa cc m N, 2 (3) i rw t with mass moment of Inertia J i of rotating vehicle components, wheel raius r w an gear transmission ratio N. When riving up or ownhill the slope resistance also has to be taken into account F mg sin, (4) sl In aition of concentrate loa resulte loa is: Fig.. Drive chain vs. test station Because the research focus lies on the electrical an electromechanical components all mechanical parts are emulate by a loa machine. The amount of torque, prepare by the electrical machine, epens on the riving resistance at the local operation point. 2. Loa machine The loa machine has to comply with the high requirements of the testing environment. These are e.g. constant torque about a large area of spee an a small moment of inertia to gain fast ynamics. To fulfill all of these nees the test station is equippe with an interior permanent magnet synchronous machine (IPMSM), by a rate power of 94 kw. The loa machine is able to provie a constant torque of 200 Nm from

3 Zeszyty problemowe Maszyny Elektryczne Nr 00/203 cz. II 45 zero to the rate spee of 4500 rpm. At higher spee the machine reaches the fiel weakening area an can be accelerate to a maximum of rpm Controlling the test station The test station is operate by a control- an observing unit. This processor is hanling an saving the ifferent types of measure signals, like currents, temperature, motor torque or rotation spee an is simultaneously etecting critical operation points. The necessary software is evelope in Matlab an will be continuously enlarge for ifferent types of testing scenarios. The setup for the testing process, like control parameters or evelopment of user-efine riving cycles is also manage by the test station-software. The test station for components of electrical vehicles is also a platform for comparing simulation moels. 500 V 00 A DC AC 3 ~ AC 3 ~ AC AC DC ω* ω, T ω*, T* Voltage, Current Voltage, Current This synergistic effect of the test station an the simulation library provies a goo concept for a evelopment platform. 3. Simulation of rive chains The simulation library is evelope within the context of the project TIE-IN, with the cooperation of ifferent institutes of the faculty of Electrical Engineering an Information Technology. The Institute of Electrical Drives an Mechatronics is focuse on the electrical machine. Toay the majority of E-Mobiles are equippe with a permanent magnetic synchronous machine, with rare earth magnet material. The avantage of these machines is a high power ensity, which is perfect for the use in automobiles. Inuction machines are also use in the electrical automotive engineering, e.g. the Tesla Roaster with an engine output of 225 kw. These types of machine are robust an much cheaper than permanent magnetic synchronous machines with their expansive magnets. Both types of machines are inclue insie the simulation library for ifferent levels of etail. 3.. Moeling the IPMSM The simplest moel bases on linear magnetic conitions an a sinusoial air-gap fiel. In this case the permanent magnetic synchronous machine can be moele in the rotor static /qcoorinates [5]. U Ri Li plqiq (6) t Uq Riq Lqiq p Li p p (7) t Fig. 3: Structure of the control system At the Institute of Electrical Drives an Mechatronics a simulation library for moels of the electric rive chain is built. These simulation moels are evelope in the simulation environment Matlab/Simulink. With this library it is possible to simulate single components, the electrical rive chain or the whole electric car in avance. The comparison with the test station allows efining higher graes of simulation moels, for example parasitic effects within electrical machines. Fig. 4: /q- system of an IPMSM

4 46 Zeszyty problemowe Maszyny Elektryczne Nr 00/203 cz. II U an U q are the transforme voltages an i, i q the transforme currents. The inuctance in the irect axe is L an in the quarature axe L q. The flux linkage of the permanent magnets is escribe by p an p is the number of pole pairs. The electromagnetic torque of an IPMSM is given by: 3 T p pq i LLqiq i 2 (8) 3.2. Moeling the inuction machine The moel of the linear magnetic inuction machine is base on the space vector moulation. The avantage of this metho is the possibility to freely choose the coorinates system. k k k k u Ri jp k t (9) 0 Ri k k k jp k r 2 t (0) k k k m m 2 L L i L i () k k k 2 2 m 2 m L L i L i (2) frequency of the coorinate system. The torque is given by 3 k k* T pim i (4) 2 For both types of machines the equation for the rotor ynamics is vali. J T Tloa (5) t 3.3. Simulation structure in Matlab The behavior of the electrical rive chain is affecte by all components an many internal an external factors. So there is a nee to moel other components, like power electronics an controlling structures, as etaile as require. Every component of the same type has got the same interfaces, so there is the possibility to exchange single components, for example synchronous an asynchronous machines. The goal is to compare the operating behavior of the simulation moels with the test station for electrical rive chains. The easiest way to o this is with a velocity profile. In this case there must be a spee regulation for the electrical machine. One option to o this is the vector control or fiel oriente control [7]. Fig. 5: moel of inuction machine in k-system For example moeling the machine in rotorflux oriente coorinates f k 2 (3) p creates similar conitions just like permanent magnetic synchronous machine. The stator- an k k rotor flux linkage are escribe by an 2, with the main inuctance L m an the mutual inuctances L an L 2. The angular velocity r represantes the spee of the shaft an k can be chosen freely. It iscribes the rotation Fig. 6: Example for an IPMSM rive chain Within this metho the ifferential equations for the electrical rive are moele in the rotor flux oriente coorinates system. The results of this are ientical magnitues for the transforme voltages an currents, which can be regulate by simple PI controllers. Fig. 6 shows the structure for the simulation of a

5 Zeszyty problemowe Maszyny Elektryczne Nr 00/203 cz. II 47 velocity profile in Matlab/Simulink. The electrical machine is supplie by a pulsecontrolle inverter, an regulate by a vector control structure. The motor spee is given to a moel of riving ynamics, which generates the riving resistances. The riving resistances are converte to an equivalent torque at the shaft of the machine. Fig. 7 an Fig. 8 are showing the results of the simulation. Fig. 7: riving cycle velocity profile simulation moels are giving the answer of the behavior of electric cars before constructing them. All three techniques together are representing a very goo concept for eveloping new technologies in the context of electro mobility. 5. Bibliography []. Peters, A., Hoffmann, J.: Nutzerakzeptanz von Elektromobilität, 20, Fraunhofer ISI, Karlsruhe, [2]. Hochmann G., Kammerer, C., Schmit, R.: Durchgängige Entwicklungsplattform für Motorenun Fahrzeugversuch, ATZ Automobiltechnische Zeitschrift No, 2009, Wiesbaen, pp [3]. Brauner G., Geringer B., Schröl M.: Forschungsbearf für as Elektroauto er Zukunft. Elektro- un Informationstechnik No 29, 202, Wien, Austria pp. 0-7 [4]. Brabetz L., Ayeb, M., Lachmann, M. Walmann, T.: Prüfstanskonzept für Elektro- un Hybriantriebe. ATZ Extra, 202, Kassel, pp [5]. Kulig S.: Ausgleichsvorgänge in elektrischen Antrieben. TU Dortmun, 20, Dortmun, [6]. Müller G., Ponick, B.: Theorie elektrischer Maschinen. 2009, Wiley-VCH Verlag, Weinheim, [7]. Schröer D.: Elektrische Antriebe Regelung von Antriebssystemen, Springer Verlag, München, Fig. 8: Motor Torque at the artemis roa cycle 4. Conclusion The paper shows three ifferent techniques for the research an evelopment of the electrical rive chain. With a power-absorption-roller there is the possibility to test the whole electric vehicle uner reproucible conitions. The test bench for components allows the testing of new components an their characteristics insie the whole electrical rive chain. Highly etaile Authors Dipl.-Ing. Anré Fischer, Institute of Electrical Drives an Mechatronics, Electrical Engineering Department, TU Dortmun University, Dortmun,, anre.fischer@tu-ortmun.e. Patrick Seibt, M.Sc., Institute of Electrical Drives an Mechatronics, Electrical Engineering Department, TU Dortmun University, Dortmun,, patrick.seibt@tu-ortmun.e. Reviewer prof. r hab. inż. Mieczysław Ronkowski

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