Power and energy management of multiple energy storage systems in electric vehicles

摘要

This dissertation contributes to the problem description of managing power and energy ofmultiple energy sources for electric vehicle power system architectures. The area of powerand energy management in the application domain of electric vehicles is relatively new and encompasses several different disciplines. Primarily, the challenges in electric vehicles having multiple energy storage systems lies in managing the energy expenditure, determining the proportional power splits and establishing methods to interface between the energy systemsso as to meet the demands of the vehicle propulsion and auxiliary load requirements.In this work, an attempt has been made to provide a new perspective to the problemdescription of electric vehicle power and energy management. The overall approach to the problem borrows from the basic principles found in conventional managementmethodology. The analogy between well-known hierarchical management concepts andpower and energy management under timing constraints in a general task-graph is exploited to form a well-defined modular power and energy management implementation structure.The proposed methodology permits this multidisciplinary problem to be approachedsystematically. The thesis introduces a modular power and energy management system (MPEMS). Operation of the M-PEMS is structured as tri-level hierarchical process shells. An Energy Management Shell (EMS) handles the long-term decisions of energy usage in relation to the longitudinal dynamics of the vehicle while processes within a Power Management Shell (PMS) handles the fast decisions to determine power split ratios between multipleenergy sources. Finally, a Power Electronics Shell (PES) encompasses the essential powerinterfacing circuitry as well as the generation of low-level switching functions.This novel framework is demonstrated with the implementation of a power andenergy management system for a dual-source electric vehicle powered by lead acid batteries and ultracapacitors. A series of macro simulations of the energy systems validated against practical tests were performed to establish salient operating parameters. These parameters were then applied to the M-PEMS design of a demonstrator vehicle to determine both thegeneral effectiveness of a power and energy management scheme and to support the validityof the new framework. Implementation of the modular blocks that composes the entiresystem architecture is described with emphasis given to the power electronics shellinfrastructure design. The modular structure approach is design-implementation oriented,with the objective of contributing towards a more unified description of the electric vehicle power and energy management problem.