Regenerative Braking System for Series Hybrid Electric City Bus

Abstract

Regenerative Braking Systems (RBS) provide an efficient method to assist hybrid electric buses achieve better fuel economy while lowering exhaust emissions. This paper describes the design and testing of three regenerative braking systems, one of which is a series regenerative braking system and two of which are parallel regenerative braking systems. The existing friction based Adjustable Braking System (ABS) on the bus is integrated with each of the new braking systems in order to ensure bus safety and stability. The design of the RBS is facilitated by Simulink [1] which is used to build an interactive, multi-domain simulator that is allows parametric variation of vehicle speed, State of Charge (SOC) for the batteries, and the maximum current to be allowed to the batteries from the RBS. The required braking forces as a function of wheel speed are modeled using dSpace[2]. A Hardwire-in-the-Loop (HIL) experimental setup is used for component testing, followed by road testing using the Chinese Urban Bus Driving Cycle. Results indicate that all three braking systems provide some energy recovery, with the serial RBS providing the best combination of energy recovery with acceptable drivability, safety and stability. Overall results confirm that regenerative braking systems can recover significant braking energy while operating in a safe and predictable manner.

Electric vehicles’ energy consumption measurement and estimation

“…One of the most advanced features of an EV, compared to conventional ICE vehicles, is its ability to capture and store energy through the regenerative braking system (RBS) (Clegg, 1996;Xu et al, 2011;Zhang et al, 2008). RBS uses the electric motor to recharge the battery by applying negative torque to the drive wheels and converting kinetic energy to electrical energy.…”

Braking force decoupling control without pressure sensor for a novel series regenerative brake system

“…8 Many previous literatures focus on SRB, in which an electrohydraulic brake system is an important device to implement the desired hydraulic braking torque. 9–11…”

“…8 Many previous literatures focus on SRB, in which an electrohydraulic brake system is an important device to implement the desired hydraulic braking torque. [9][10][11] There are several ways to achieve electrohydraulic braking. In some applications, the hydraulic control unit (HCU) of anti-lock brake system (ABS) is used to adjust wheel cylinder pressure (WCP) for regenerative braking demand.…”

Performance evaluation of regenerative braking systems

“…continuous driving without braking renders even an efficient RBS ineffective at improving system efficiency, performance and range. 20,31,[38][39][40] In another example, the design and performance of an electro-mechanical RBS integrated with an ABS on an electric bus, was investigated by Zhang et al 41 The testing was conducted according to the Chinese Urban Bus Drive Cycle and the efficiency of regeneration from real road braking was considerable 2 up to 66% depending on the RBS design.…”