Control Scheme and Power Electronics Architecture for a Wirelessly Distributed and Enabled Battery Energy Storage System

Abstract

This paper presents and evaluates a control scheme and a power electronics architecture for a Wirelessly Enabled and Distributed Battery Energy Storage (WEDES) system. It includes several independent battery modules (WEDES-MX modules) that transfer both power and information wirelessly to an On-Board Unit (OBU). Using wirelessly communicated State-Of-Charge (SOC) information from the WEDES-MX modules, the OBU part of the WEDES controller generates control commands and send them back to the WEDES-MX modules in order to control the amount of power/energy drawn from each WEDES-MX module and achieve SOC balancing. The presented controller also allows the WEDES system to maintain operation with a regulated bus voltage even if one or more WEDES-MX modules are removed or fail and under both balanced and unbalanced SOC conditions. The WEDES system with the presented WEDES controller when utilized in Electric Vehicle (EV) application, can allow for fast and safe exchange/swapping of WEDES-MX modules at an exchange station, home, or work and therefore potentially eliminating the range (mileage) anxiety issue that is associated with EVs’ range and the needed recharging time. The main objective of this paper is to present and evaluate the WEDES discharging controller for the WEDES system and present preliminary proof-of-concept scaled-down experimental prototype results.

Small-Signal Modeling and Analysis for a Wirelessly Distributed and Enabled Battery Energy Storage System of Electric Vehicles

“…To realize the functionalities of SOC balancing, bus voltage regulation, and battery module current/voltage regulation, the WEDES controller consists of three different control loops: the SOC balancing control loop (referred to be by the SOC balancing loop), battery module voltage control loop (referred to be by the module voltage loop) and bus voltage control loop (referred to be by the bus voltage loop). Figure 2 shows In the WEDES controller, the SOC balancing loop is used to generate multipliers αMX1 through αMXN to realize SOC balancing between multiple battery modules, as given by Equation (1)…”

“…Battery energy storage systems (BESS) have been widely used in various applications, such as electric vehicles (EVs), consumer electronics, medical devices, smart grid, energy backup in data centers, and among others [1][2][3][4][5][6][7][8][9][10]. For EV applications, what is referred to be as "range anxiety" is one of the major reasons that prohibit or slows down the adoption of EVs [9][10][11][12][13][14].…”

“…Among these methods, the battery swapping concept is a good candidate to reduce recharging time and extend the driving range with low infrastructure cost. To deal with the challenges in the conventional battery swapping concept, a new distributed and enabled battery energy storage (WEDES) system and WEDES controller for EVs are presented in [1], which allows for fast and safe exchange/swapping of smaller and lighter battery modules with wireless power transfer (WPT) technology [18,19].…”

“…These couplings make the analysis and design of the WEDES controller complex and critical. While the initial concept of the distributed WEDES battery system is discussed in [1], the small-signal modeling and controller design analysis are not focused on.…”

“…Illustration diagrams of battery system for electric vehicle (EV) application. (a) The conventional battery pack and electrics drive system in EVs, (b) the wireless distributed and enabled battery energy storage (WEDES) battery system in EVs, and (c) example circuit diagram of the WEDES system[1].…”