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AUTOMATIC GUIDED FUTURE VEHICLES Abstract :Four technologies, combining mainly innovative solutions, offer the possibility of clean and flexible vehicles, all using only electricity. The main common components are contact-free energy transmission, storage on super-capacitors, holonome axles integrating wheel-motors and automatic guiding. Moreover, the complete energetic chain is managed by power electronics. Their applications are mainly in the field of public and industrial transportation. Several applications are described: electric busses, automatic guided vehicles for container handling, automatic people movers and automatic surveillance vehicles. applications are described: electric busses, automatic guided vehicles for container handling, automatic people movers and automatic surveillance vehicles. Fig. 1. From Swissmetro project to specific technologies Fig. 2. Contact-free energy transmission - Principle III.CONTACT-FREE ELECTRICAL ENERGY TRANSFER A. Principle This technique [2-7] offers the possibility to transfer electrical energy from a fixed coil on or in the ground to Moving coil linked to the vehicle Fixed coil in the ground an other coil placed under a vehicle. I. The process is realized without iron magnetic circuit, in the air. On INTRODUCTION Figure 2 the principle is illustrated. In order to reach this ironless A new generation of vehicles, mainly based on 4 different magnetic coupling, a high frequency is necessary (>>50 Hz). technologies, is presently in development for good or passenger Effectively, from the back-EMF equation it is possible to write: transportation or special applications.These technologies are Ui=d/dt =back EMF - Contact-freeenergy transmission =total flux = N - Wheel-motor with an external rotor N = coil number of turns - Energy storage on super-capacitances B = magnetic flux density -The use of an energy chain based on power electronics and control, Sair= magnetic air section from the ground to the motors. So the back-EMF equation becomes : The main applications are : Ui N.f.B.Sair - An automatic guided vehicle (AGV) for container transportation By increasing the frequency and the magnetic section, it is possible to and handling reduce the flux density B and the copper volume by reducing the - An automatic people mover at 15 km/h number of turns N. Thus, it is possible to suppress the iron magnetic - An automatic safety and control vehicle circuit, using air instead. An optimisation software, aiming to reduce - An electric city bus the copper volume, to reach a transmission efficiency > 98 % and to II. AIM minimise the electromagnetic radiation has been developed and Starting from different technologies developed for the high speed applied. A system for a total power of 120 kW (Fig 3) has been Maglev Swissmetro (Fig 1 ) , the approach of technology transfer designed and built with the corresponding power electronic to has been to apply one or several components to innovative vehicles generate the high frequency and a controlled rectifier on the vehicle . ,responding to specific constraints and criteria: A global maximum efficiency of 95 % has been measured at 110 kW. - High flexibility of exploitation - Clean, quiet and sustainable ; - High automation and control with or without driver; - Low investment in infrastructure; - Low maintenance costs. In order to reach these goals, specifically in the range of speeds between 10 and 100 km/h, one more device had to be implemented : the direct drive wheel-motor with external rotor, also developed at EPFL. Fig.3. Contact-free energy transmission – 120 kW test facility B. Magnetic field A specific problem of inductive energy transfer is the magnetic field radiation, limited by normalization, according to the frequency. The solution to reduce the intensity of radiation for passengers in the vehicle and nearby is to design the system using 3 safety elements: - To switch on the primary coil only when the secondary coil (i.e. the vehicle) is correctly positioned. - To place a magnetic shield on the vehicle floor (a thin lamination) - To impose the same current volume for the primary and the secondary coils This last condition has been applied to an Fig.6. Relative flux density distribution on a level of 1.2 m energy transfer system corresponding to the following above the conditions: IV. ENERGY STORAGE ON SUPERCAPACITORS - Power transferred : 108 kW Energy transfer can be done continuously from the ground to - Coil sizes : 4*2 m a vehicle, using a continuous succession of coils (Fig.7) . This - Distance d : 0.115 m presents two drawbacks: the investment cost and the absence - Primary voltage: 500 V of track flexibility. - Floor level above primary coil : 0.3 m With current volume opposition, the magnetic field levels without shielding are represented on graphics, in relative values, referred to the earth magnetic field. On Fig. 4, the relative flux density is calculated above the middle of the coils, on a vertical axis (yy), from the vehicle floor level (0.3 m) up to 2 m. On the vehicle floor, the relative amplitude is 0.3. Fig.7.Continuous coil track As a variant, contact-free energy transmission with intermediate fast storage on ultra-capacitors [8,9] is a very interesting solution. It allows an autonomy of track with a reduced investment. This solution requires an autonomy in the Fig.4. Relative flux density distribution above the coil centre, range of 2.5 to three times the distance between two loading on a stations. On Fig.8, the global electrical scheme of such a On Fig.5, the same relative flux density is represented on the solution is presented, including the energy transmission floor level (yy= 0.3m) on an horizontal axis, from the coil system and ultra-capacitor loading control. The rapid loading centre laterally up to 2m; xx = 1 m corresponds to the coil operation requires an important peak power. Thus, an side level. The peak value is 0.75 above the coils. interesting solution is to equip a station also with an ultra- capacitor intermediate storage, such as to have the possibility to smooth down the main power (see Fig. 18). V. WHEEL-MOTOR For the different categories of vehicles presented hereafter, the electric drive solution has been focused on direct wheel motor drive characterized by: - No gear transmission - Brushless DC motors - External rotor Fig.5. Relative flux density distribution on the vehicle floor The absence of transmission leads to a heavier motor. But the level, from solution with external rotor  allows a better integration the centre to 2 m – 108 kW power – 4*2 m coils directly in the wheel and not laterally to the wheel (Fig 9) as On Fig.6, the same relative flux density is represented on the sometimes realized. Fig 10 shows a wheel motor according to on a level of yy=1.2m, on an horizontal axis, from the coil the proposed solution. An optimized design software leads to centre laterally up to 2m; xx = 1 m corresponds to the coil an acceptable mass with an important free volume at the side level. The peak value is 0.1m above the coil centre. inside. Fig.8.Electric scheme of energy transfer system and storage on ultracapacitors Fig.12.Vehicle axle with 2 wheel motors and a steering motor. The damping elements are integrated in the motor itself. Fig.9.Electric drive for wheel with classical gear transmission Fig 11 shows the stator (left) and the rotor (right) of such a motor for a rating torque of 4000 Nm. Based on such motors, vehicle axles with 2 wheels have been developed, with integrated steering motor allowing a very important angle of rotation until ± 90o (Fig 12). In this case, the damping devices have been integrated in the free space internal to the motors. Such an axle has been realized for the vehicle of Fig.14. Fig.13.Automatic Guided Vehicle for 40 T containers -120 kW powerat 25km/h. VI. VEHICLES INTEGRATING THE DIFFERENT TECHNOLOGIES Automatic guided vehicles for container handling: An automatic guided vehicle for container handling has been developed tire d integrating the following technologies: - Contact-free energy transmission - Motor wheel axles - Energy storage on super-capacitors - Automatic guiding The transportation capacity is designed for 40 T containers. Fig.10.wheel motor with external rotor The maximum power is 120 kW with a maximum speed of 25km/h. On Fig.13, a picture of the final vehicle is presented. On Fig 14, the first prototype vehicle is represented. It is supplied by the coil system of Fig.3. Fig.11.Stator (left) and rotor of a wheel motor of 4000 Nm Fig.14.Automatic Guided Vehicle for 40 T containers – First prototype A first series of such vehicles will be built and tested in a harbor at the end of 2008. Low floor electric bus : The same technology of energy transmission system and axles with wheel motors can be applied to busses with a very low floor, according to the integrated wheel realization . The possibility to move the wheels independently (but in coordination) offers the advantage to reduce the stop area length. A test realization is foreseen for 2009. Fig.18.Automatic people mover with energetic chain and loading station 1-Vehicle structure 2-Loading station with intermediate storage 3-Power electronics 4-Super-capacitors 5-Obstacle detection 6-Primary coil 7-Secondary coil Fig.15.Bus with independent wheel axles and very low floor Automatic surveillance vehicle: Many different installations or situations require safety Automatic people mover: surveillance and reconnaissance. They are generally known Automatic people mover (APM) are small vehicles with a under the name of Mobile Detection Assessment Response capacity of 8 to 10 people (1200 kg) with a speed of 15 km/h System (MDARS).Automatic systems based on the same (Fig 16). The rating power is 14 kW with a maximum slope of energetic chain as the APM system have the advantage of 16%. The peak power for the energy transfer is 50 kW. This reliability, absence of noise, insensitivity to any type of allows a loading time of maximum 10 seconds for an pollution and a smaller size. Such a vehicle has been designed autonomy of 1 km (Fig 17). In order to avoid such peak and will be equipped with devices such as radar, NBC energy consumption on the main, an intermediate energy sensors, IR camera, etc. Among the characteristic storage at each loading station is introdu ced (Fig 18). So the applications: airports, nuclear power plants, gas and fuel power request on the main is smoothed. Such transportation production, high or low temperature environment, catastrophe system can be applied to pedestrian streets, airports, large evaluation and rescue, military investigation, etc. Such a parking areas, exhibition centers, university campus, large vehicle, based on similar technologies as AGV and APM, factories, etc. Two test vehicles are in construction and a first have the advantage of no noise, no pollution and high pilot track is foreseen for 2009, in Lausanne. flexibility. A first prototype will be built soon. On Fig 19, the vehicle design is represented. VII. ENERGETIC CHAIN All these different vehicles use basically the same energetic chain, with powers from 10 kW to 250 kW. For these developments, power electronics is a key factor, mainly for the following functions: -High frequency supply generator for energy 53. transmission, with a high efficiency - Super-capacitors load and control - Propulsion and steering motor control and drive Fig.16.Automatic people mover vehicle Fig 20 describes the complete energetic chain. CONCLUSION : Infrastructure is an important determinant of transport costs, Fig.17.Automatic people mover system with loading stations especially for densely populated locked countries like India.. every Almost two-third of deaths in our country is due to road 400 m accidents. Obviously, many drawbacks of conventional mode of transportation in our country would be avoided, on implementing this idea We move for automation to dispel manual errors. Also we could create pollution free environment zone and safety mean of transportation. REFERENCE: “Theory of machines” Khurmi Gupta, “ Electrical machines “Nagarath & Kothari , www.numexia.com.
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