The increasing demand of electrical power in recent automotive developments is a result of various additional electrical aggregates commonly subsumed under the term x-by-wire technology. In some applications x-by-wire is not only used for additional service aggregates but also for the active propulsion or deceleration of the car. The increased demand in electrical power as well as in electrical energy for the x-by-wire technology and hybrid propulsion technology systems requires new battery technologies as the regulär SLI Lead Acid batteries are not covering all the demands like e.g. high cycle life, deep discharge capability, high recharge recuperation power. Nickel-Metal Hydride and Lithium-Ion Systems are currently considered to be very promising electrochemical systems to cover the demands. As the specific power and energy values of these systems are remarkably high, the energy throughput may be large. Even though the average energy efficiency of these systems is relatively high, the losses, typically in the range of 10 % to 20% depending on power profile will lead to increased thermal strain of the electrochemical system. High power Nickel-Metal Hydride as well as Lithium-Ion Battery systems therefore require a thermal management which has to be carefully designed as part of the overall safety management of these battery systems. DC voltages above 15 V require precautions to be taken as electrical arcing becomes a problem. DC voltages of several hundreds of volts in hybrid car applications require even more an electrically safe management with electric isolation control and short circuit detection and prevention. To fully use the capabilities of these new battery systems the determination of the actual condition of the battery, like e.g. the state of charge, the state of health or the state of functionality is required. Knowing these data the central vehicle control system can control the power and energy flow in the automobile to optimise the overall performance. A sophisticated Battery Management System (BMS 5.P) was developed to control the electrical and thermal management of 42 V batteries as well as of higher voltage NiMH batteries. Based on voltage, current and temperature data the BMS 5.P determines necessary parameters (e.g. SOC, SOH) to ensure the safe performance of the battery systems. Concerted communication between a central vehicle control unit and the battery management system is done via CAN communications line. Various kinds of NiMH batteries ranging from 5 Ah to 60 Ah and 42 V to 350 V controlled by the BMS 5.P are in service and have shown the operational readiness of the system.
New battery systems and battery management for automotive applications
2003
9 Seiten, 8 Bilder, 5 Quellen
Conference paper
English
Fahrzeugelektrik , Metallhydridbatterie , Lithiumionenbatterie , Batteriekapazität , Batteriebetrieb , Energiemanagement , galvanische Batterie , Wärmespannung , Gleichspannung , elektrische Ladung , Kapazität (galvanisches Element) , Trend (Entwicklung) , Datennetz , CAN (Controller Area Network) , Stand der Technik
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