Smart Battery Cell Monitoring with Contactless Data Transmission

Abstract

The market breakthrough of electric vehicles is mainly delayed by the still too high costs of the battery system. The smart battery cell monitoring presented in this article enables further cost reduction. It consists of battery cells integrating the monitoring electronics together with a data transfer interface for communicating in a bidirectional way with the battery management system. The data transfer interface presented in this paper is based on a differential contactless data transmission bus using galvanically isolated capacitive coupled links to each single smart battery cell. Since neither galvanic contacts nor connectors are needed, the proposed concept provides simultaneously a very high level of reliability and robustness, and a highly cost-efficient manufacturing process, thus allowing a significant reduction of the final battery pack costs. This paper describes a possible implementation of such a differential contactless data transmission for monitoring and managing battery cells in electric vehicles. State-of-the-Art in Battery SystemsDespite the great efforts that have been made during the last years to promote electric mobility, the electrical vehicle still has not had its final breakthrough. An important reason for the lack of broad acceptance is the cost of electric vehicles (EV) that is still too high. Especially the battery system is and will remain a major cost factor in the near future. This article describes a novel approach to the battery system, which is aimed to significantly reduce the component costs, the development time and the manufacturing costs of the battery system, while increasing its flexibility and reliability.

High-voltage battery management systems (BMS) for electric vehicles

“…The master/slave concept with separate CMU for each cell is more flexible and less complex than the centralized BMS topology, but still has a low maintainability and is complex to handle during assembly of the battery pack due to the number of connections that have to be made at voltages increasing with each added cell. The slave can also be integrated into the cell directly; this concept is called smart BMS or smart cell in the literature, e.g., Lorentz et al (2012). Figure 11.3 shows a schematic illustration of the master/slave BMS with separate CMU for each cell.…”

“…1 Comparison of current sensing methods(Koon, 2002, andDrafts, 1996); resistive shunt measurement preferred for EV battery pack use in providing communication interfaces and galvanic isolation of all the individual CMUs Lorentz et al (2012). investigated a contactless communication solution for smart cell BMS and list the advantages of smart cells, e.g., increased modularity, shorter development time, protection against counterfeit batteries, cell history storage, and reduced cabling effort (if wireless communication is used).…”

Galvanically isolated differential data transmission using capacitive coupling and a modified Manchester algorithm for smart power converters

“…An adapted version of the signal conditioning circuit described in [4] and [5] was applied to ensure a robust and reliable transmission of signals with minimal delay. This signal conditioning is illustrated in Fig.…”

Critical Review of Intelligent Battery Systems: Challenges, Implementation, and Potential for Electric Vehicles

“…This is depicted in Figure 2 where schematically the switches for reconfiguration as well as possible sensor implementation and the necessary communication or Battery Management System (BMS) integration is shown. First, concepts combining several of the above functions with corresponding hardware and system approaches can be found in the literature presented as "intelligent" or "smart" batteries [7][8][9][10]. In addition, in the multitude of patents that arise in this field, different aspects are in the focus addressing smart or intelligent battery devices: Intel focuses on integrated sensing [11], Bosch is patenting a device for regulating the system voltage adaptively [12] and Audi outlines an integral smart battery cell with sensing, communication, and integrated reconfiguration functionality [13,14].…”

“…Schneider et al [8] use an intelligent battery with a cell individual current and temperature sensor and reconfiguration functionality for an improved online parameter estimation. Lorentz et al [9] focus on contactless data transmission to realize smart battery cell monitoring, where each cell is equipped with its own monitoring circuit board, and all boards exchange information among each other. In contrast, Kim et al [10] denominate their battery system as smart battery, where the ordinary battery system is augmented by a switching circuit board which allows activation and bypassing of each cell.…”