Improving fuel economy of a Hybrid Electric Powertrain by Downsizing

Abstract

This paper aims at the development of a hybrid electric powertrain which is focused on grater fuel economy by downsizing when compared with present and future developed powertrains. In this work, the proposed hybrid vehicle is powered by four systems, a rule based system (RBS) which mainly explores the engine efficiency; a Speed Control System (SCS) which is focused on the speed control of Traction Motor and individual Front Wheel Motors; a Powertrain Feedback System (PFS) which mainly monitors the powertrain efficiency so as to maintain vehicle dynamics appropriately and a Selective Perpetual Motion System (SPMS) through which power management is achieved. The system is preset to work under three driving cycles, an economy mode where the vehicle is operated typically at low speeds or in traffic; a power mode where the vehicle is in steady state driving; a super power mode where more torque and power required to drive the vehicle under heavy load conditions or in hill climbing. The vehicle is designed to work under different configurations of power, torque and voltage to achieve the mode of drive cycle. The current supplied to the motor(s) is kept constant and nominal in rating. In this manner, a brief study about the transient analysis of the proposed vehicle is done, suffering no performance disadvantages to the conventional vehicles.