Design and analysis of a parallel hybrid electric vehicle for Indian conditions

Abstract

Hybrid Electric Vehicles (HEVs) are emerging as alternatives to the traditional Internal Combustion Engine (ICE) driven vehicles to meet stringent emission norms, environmental and energy concerns. A commonly seen HEV configuration is the Parallel Hybrid Electric Vehicle (PHEV), in which both the ICE and electric motor are mechanically coupled to drive the wheels. Depending on the level of hybridization, which is defined as the ratio of motor power to the total power of the drive train, the PHEV is further classified into Mild, Full, and Plug-in hybrid. Regenerative braking is a key feature in HEVs that improves the fuel economy. The amount of energy regenerated depends on the motor, battery specifications and the control strategy. The design and analysis of the drive system and the control strategy for a typical Indian vehicle is the key focus of this paper. This involves the determination of engine power, motor power, gear ratios of transmission and battery specification to meet the drive requirements such as acceleration, maximum speed and gradeability. Also, the control strategies for both traction and braking have been discussed in this paper. Further, by considering the Modified Indian Drive Cycle and a real time speed plot, numerical simulation has been performed to evaluate the benefits in terms of fuel economy, compared to the conventional ICE driven vehicle. The simulation results shows that, in a full hybrid configuration with regenerative braking, the vehicle fuel economy can be improved by up to 32% in Indian driving conditions compared to the conventional ICE drive. The fuel economy can be improved further in hybrid powertrain with the engine turned off while braking instead of operating at idle speed.