Design of a Low Voltage Active Electric Accumulator with integrated dc-dc converters for control and protection

Abstract

Emerging batteries based on Lithium ion (Li-ion) cells are of significant interest for aerospace, automotive and utility energy storage systems in terms of high energy density, reducing overall weight, volume, and maintenance but suffer from safety concerns such as fire, smoke and toxic emissions. Major issues with these batteries include: a) single point failure, b) complex and costly battery management system (BMS), c) varying output voltage, d) no self-protection, e) costly and ineffective cell balancing, and f) poor energy efficiency. The main objective of this thesis is to investigate a 'Self-Regulated Low Voltage Active Electric Accumulator (LV-AEA)' as an alternative approach for the design of a Li-ion batteries and compare its benefits and limitations to the existing battery technologies. The analysis and design of LV-AEA for a 7kW Auxiliary Power Unit start application in a starter/generator system of a typical aircraft is presented. Computer simulation results using PSIM have been presented to help understand various working principles of the proposed approach and validate its feasibility. Finally, a small scale technology demonstrator using commercial off- the shelf dc-dc converters is tested to verify the presented approach and get experimental results.