This paper presents a systematic design methodology for split hybrid vehicles using a single planetary gearset (PG) as the transmission. The design methodology consists of four steps: 1) analyze clutch locations on the PG and operation
INTRODUCTIONThe power-split configurations have dominated the hybrid electric vehicles (HEVs) markets in the US and in the worldmore than 90% of the hybrid vehicles sold in 2010 are powersplit type [1,2]. Currently, most of the production models use a single planetary gearset (PG) as the transmission, including the Toyota Prius and the Chevy Volt. However, these two vehicles are very different; the Prius is an input-split HEV (an electric machine is connected to the output shaft) with only one operation mode and no clutch is used. The Volt, on the other hand, is an output-split HEV (an electric machine is connected to the engine) with three clutches to allow four operation modes. These differences indicate that there are many design decisions to be made even when only one PG is used. Earlier studies have shown that when two PGs are used, there are 1,152 possible configurations [3], and when one PG is used, there are 12 possible configurations [4]. Adding clutches on the PG allows the same configuration to have multiple operation modes; it has found that a 1-PG configuration can have as many as four useful modes by adding three clutches [4]. When the basic configurations are determined, vehicle performance, such as the speed/torque characteristics of the powetrain components, vehicle weight, driving patterns, vehicle acceleration performance and fuel economy, must be