On-board characteristics of rechargeable lithium ion batteries for improving energy regenerative efficiency

Abstract

Although other methods have been studied recently, the regenerative brake system has been contributing to reduced energy consumption on electric railway vehicles for over 30 years. However, there are a lot of problems associated with the system, such as regeneration being cancelled out by wheel slide and trolley voltage conditions, decreases in electric braking force in the higher speed ranges, and restrictions on regenerative power determined by power supply circuit impedance. In order to utilize and recycle braking energy and secure a steady regenerative load, we selected lithium ion batteries to store electric energy and developed a rechargeable lithium ion battery (600 V system) for use on electric railway vehicles as one of the prominent alternatives. In this paper, we report on an energy recycling contact-wire-less tramcar that uses the rechargeable lithium ion batteries and show the tramcar's performance and characteristics of the battery as developed. The battery under development has demonstrated excellent performance in terms of energy and power density, efficiency, 500 A charge and discharge current, internal resistance and maintenance work.