Researchers at Vito sought to combine the advantages of both series and parallel hybrid powertrains while minimizing the drawbacks. Series hybrids allow performance to be independant of road load, and therefore a more optimal engine operation while parallel hybrids suffer lower conversion losses due to the mechanical link of the engine to the wheels. While studying several systems, we found an alternative concept with a planetary gearbox that seemed to address the demands. In this concept a combination of ICE with a motor/generator drives the ring while a second motor/generator drives the sun. The drive shaft is linked with the planet carrier. Due to the existing experience at Vito with a 9 m series hybrid city bus and its conventional counterpart, the concept was subjected to basic simulations for this type of vehicle. Initial simulations of the concept on a real speed-distance profile showed a substantial reduction of the fuel consumption. This is mainly due to the optimized engine use while also considering reduced emissions. This allowed down sizing of the engine from 100 kW peak power in the series hybrid bus to 23 kW continuous power in the new concept. Furthermore, the simulations reveal how the different components as used in this application behave. The choice of the system parameters, like gear ratios of the planetary system and the engine speed, has a substantial effect on the component behaviour and the system efficiency. Once the optimal parameter set is defined, the components can be sized and more advanced simulations can be elaborated.
An alternative hybrid powertrain topology
2001
7 Seiten, 10 Bilder, 1 Tabelle, 5 Quellen
Aufsatz (Konferenz)
Englisch