DEVELOPMENT OF A COMPACT HYBRID VEHICLE WITH A FORESIGHTED ENERGY MANAGEMENT SYSTEM

摘要

Facing the continuously increasing traffic density and number of vehicle registrations, a reduction of CO_2 emissions is indispensable. Improved engine technologies arc one possibility to reduce the fuel consumption. Other possibilities to lower the energy demand of a vehicle arc i.e. lightweight materials, improved aerodynamics, low resistance tires and more efficient gearboxes. With the market launch of vehicles with hybrid drive this drive concept has been set in the focus of public discussions as an additional promising technology to reduce fuel consumption. General advantages of hybrid vehicles arc e.g. an optimised operating strategy of the combustion engine during stopping phases and the possibility of energy recuperation while braking. So an urban traffic situation with a dynamic driving profile offers a high fuel saving potential. However, higher speed levels reduce the possible fuel saving. In general, hybrid vehicles have only a limited fuel saving potential towards conventionally driven vehicles in highway traffic.Thus hybrid vehicles need an adaptation of the driving style to the characteristics of the drive train (8). The complete saving potential of a hybrid vehicle is only open to a foresighted and anticipatory driver. The aims of the forcsightcd energy management for hybrid drive systems arc to reduce fuel consumption as well as exhaust emissions, to optimise aggregate stress and battery lifetime. A new operating strategy is necessary that considers additional information about the current and following traffic situation. One important question is how the forcsightcd driving effects fuel consumption, driving comfort and how drivers will accept this technology. A necessary condition for forcsightcd driving is the information about the future traffic situation. Vehicle mounted sensors like radar or lidar systems can give dynamic information about the surrounding traffic situation while the digital map of the navigation system offers static information about the street conditions (e.g. inclination, curvature, speed limit). This information will be included in the next generation of digital maps. The energy management uses all available information to drive the hybrid vehicle in the most economical way.This is the main topic of the presented project. Based on the latest drive train concepts a forcsightcd energy management will be developed for a full-hybrid vehicle and demonstrated in a subcompact vehicle. The build up of the vehicle has been finished by the end of the year 2007 and from the beginning of 2008 driving tests with different test persons started to show the fuel saving potential in real traffic. These tests show on the one hand the saving potential of the hybridisation of the vehicle and on the other hand the additional saving potential of the hybrid vehicle in combination with the forcsightcd driving strategy.The presentation explains the build-up of the hybrid drive train including the necessary components like the electric engine and the high voltage battery. In addition the traffic prediction system is described and how it influences the operating strategy of the hybrid drive train.