THE DEVELOPMENT OF TURBOCHARGER ACCELERATOR MOTORS AND DRIVES AND THEIR INTEGRATION INTO VEHICLE ELECTRICAL SYSTEMS

摘要

When the speed or load of a turbo-charged IC engine changes, the turbocharger speed also changes. During the transient period, the incorrect combustion conditions lead to wasted energy and additional pollutant emissions. At times of high power operation, the exhaust gas stream contains more energy than is required by the turbine and a waste gate opens to bypass the excess. For large turbo-charged diesel engines (350-400kW) this excess energy can be of the order 50 to 60 kW. The paper describes the development of a high-speed induction motor drive intended first to act as an accelerator to reduce the transient period, "turbo lag", and secondly to act as a generator to extract some of the energy that would otherwise be wasted during high power operation. The extracted energy can be returned as useful electrical power into the vehicle electrical system, thereby avoiding some of the engine load at the alternator. The physical layout with the motor placed between the turbine and the compressor is illustrated in Figure 1. At high speed and load the turbine can provide too much torque and, if left to run unchecked, the turbocharger unit would over-speed. To prevent this, turbochargers use waste-gates to bypass some of the exhaust gas and so limit the over-speed. Another alternative is to operate the turbo-assist motor as a generator and return this excess energy to the vehicle electrical system. The authors are members of a consortium (ELEGT, ELEctric Exhaust Gas Turbocharger) part funded by the EU Framework V programme that aims to develop a suitable accelerator motor and drive and to integrate them into the overall electrical system of diesel powered goods vehicle.