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| General Motors Fuel Cell Activities; Mainz-Kastel (Germany) | | The Future on the Test Bench | Siemens testing technology helps hydrogen technology on its way to series maturity
In the immediate neighborhood of the Opel headquarters in Ruesselsheim - in Mainz-Kastel - Opel and GM engineers from GM FCA (General Motors Fuel Cell Activities) have been developing emission-free fuel cell drives since 1998. The ambitious goal: To develop a competitive fuel cell propulsion system by 2010 which is comparable in performance, durability and costs with today's combustion engine powertrains in large quantities. The powertrain modules for the fuel cell automobile from General Motors are being tested on two Siemens test benches since 2004.
General Motors and its German subsidiary Opel are working on new powertrain concepts for private vehicles at their sites in Mainz-Kastel, Rochester (New York) and Warren (Michigan) in the USA. The aim of the approximately 600 engineers employed at the international research center GM FCA (General Motors Fuel Cell Activities) is to develop fuel cell vehicles with market maturity. GM and Opel have invested a total of one billion Dollars in the research and want to develop a fuel cell powertrain system which is comparable with today's combustion engines in terms of performance, durability and costs by 2010.In the course of the development, the engineers have succeeded in doing away with more and more components. The most prominent component which could be omitted in the HydroGen3 was the high-performance buffer battery. This energy store served in HydroGen1 to cover performance peaks of the powertrain, but has now become superfluous, because the GM FCA engineers have dynamically optimized the fuel cell system so that it can provide the load requirements immediately under its own power. This progress has meant a weight saving of almost 100 kilograms and also has the advantage that the storage area of the hydrogen Zafira now corresponds to the level of the series model. The full space of the five-seater Zafira model is therefore available in the current test model, the HydroGen3. As a side effect, the vehicle weight has been reduced in the direction of the target value of 1,590 kilograms.Powertrain module increasingly compactThe electric traction system (ETS) has also been developed further and become more compact. The complete module consisting of inverter, electric motor and gear with parking lock and differential, positioned between the DC transformer and the drive shaft as interfaces, now weighs a total of 92 kilograms. It can be mounted on the existing bearing points of the Zafira which represents another step towards series production. The powertrain unit PDU (Propulsion Dress-Up) consisting of 15 main modules is pre-assembled like the elements of a conventional combustion engine powertrain and then installed and bolted into the body from below.Digitally on the test benchIn order to achieve the intended series production, General Motors needs not only the necessary technology know-how but also partners who can supply the necessary equipment for the development. Since 2004, the PDU modules are being tested on two Siemens test benches which are controlled by the CAT STC2000 (Computer Aided Test System) developed by Siemens. This is a fully digital control system which is integrated in a Simatic industrial PC as a plug-in card. The system contains control software modules based on the simulation and regulating software Matlab/Simulink which is also used at many universities. The modules have been developed specially for the high demands of high dynamic engine and gear test benches. The general control tasks are taken over by a Simatic S7-300 PLC.Reliable drive for alternative powertrainsThe mechanical connection of the test unit and the drive machine is made by the original vehicle shafts. 1PL6 motors in connection with Simovert Masterdrives frequency converter serve as a drive device. The PDU test benches specially designed for the GM FCS Research Center are based on two asynchronous motors of the 1PL6226 type with 70 kilowatts power and a torque of 1337 newtonmeters. The robust, low-maintenance three-phase current motors of the 1PL6 system series with high balance quality are specially designed for use in test benches with their high dynamic and the possibility of energy recovery. Another advantage: The unit can be operated in both motor and generator mode.The motors are fed by a Simovert Masterdrives VC AFE (Active Front End) converter via voltage link. The AFE converter cubicle for the four-quadrant drive consists of a termination panel with main switch, main contactor and fuse. The self-commutated, pulsed AFE infeed/feedback unit in IGBT technology (Insulated Gate Bipolar Transistor) and clean power filter ensure a low reactive current on the mains side. On the motor side, two inverters in IGBT technology are used. The infeed of the DC link with the self-commutated, pulsed AFE rectifier unit improves the torque quality because of the highly dynamic voltage control. Additionally, it is very constant and virtually independent of the supply line. Since the voltage peaks and commutation notches are almost completely filtered out by the clean power filter, conventional low-voltage cables could be used for the mains feed.
Move Up 3 / 2006 | |
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