Paper Number

Hybrid drive train technology has demonstrated high potentials to reduce fuel consumption in the transportation sector. In hybrid vehicles energy is saved by regenerating kinetic energy while braking, by operating the internal combustion engine in a more efficient speed and torque region and by turning the engine off when unused. Hybrid architectures on the market can be categorized into three groups, namely the parallel, series and power-split drive trains. Power-split architecture has the flexibility for full engine management and efficient power transmission. With this flexibility however, the control of the power train operation becomes more complex. Drive train sizing and system operation in a power-split hybrid vehicle are critical to optimize system efficiency. This paper proposes a procedure for determining the optimal operation of a power-split drive train. A method for sizing components, and a modal operation in which components are selectively shut-off are proposed to improve fuel economy. Significant improvements in fuel economy are observed with these procedures.