A Smart Cell Monitoring System Based on Power Line Communication—Optimization of Instrumentation and Acquisition for Smart Battery Management

Abstract

Energy density of current generation battery packs is insufficient for next generation electric vehicles nor the electrification of the aerospace industry. Currently, approximately a third of energy density is lost due to ancillary demands (e.g., cooling and instrumentation) within a pack, relative to cell energy density. Smart cells, instrumented cells with sensors and circuitry, offer a means to monitor cell performance (e.g. temperature, voltage, current data). Uniquely here we demonstrate our 21700 cells instrumented with internal thermistor sensing arrays with custom miniature interface circuitry including data acquisition and communication components. This circuitry including a power line communication (PLC) system, enables sensor data to be collected and transmitted to a master controller without requiring additional wiring, and can achieve an excellent <0.005 % message error rate. The control and communication system includes the use of adaptive sampling algorithms (during identified periods of low demand, through temperature and current measurements) the cells transmit data at 0.2 Hz, increasing to 5 Hz (normal operation) or 10 Hz (beyond operating limits). This method was demonstrated via drive cycling and external heating to alert the master controller to abnormal operating conditions (rapidly, to avoid missing key features) while saving 65 % volume of data during a 90 minute experiment.

Battery Cell Temperature Sensing Towards Smart Sodium-Ion Cells for Energy Storage Applications

“…Capacity measurements were taken by performing the RPT every 20 cycles, with all experiments performed within a climatic chamber (25 °C constant). This extends our previous studies [14,29], where the cells were tested for periods of <50 cycles, without capacity measurement. The sensor reliability and possible impact on the cell performance were not comprehensively assessed.…”

“…2 (b); the cell is installed in a test rig (c), which is allows battery cycler channel cables to be connected for the ageing cycling experiments. In addition to the internal thermistor sensing, a prototype bus-bar current sensor is installed for each cell (detailed in previous works [14,29]). A concept smart cell (an intermediary design, incorporating the flexible PCB and interface PCB secured in a cap) is shown in Fig.…”

“…2 (d). The interface PCB, detailed previously [14,29], incorporates a 16-bit ADC (TI ADS114s08), and a microcontroller (SAMD21E) to allow data logging via a USB connection, without requiring additional apparatus. The PCB also incorporates a powerline communication (PLC) modem to allow data to be transferred at high frequency along the cell bus-bars; this feature is not tested here.…”

“…The PCB also incorporates a powerline communication (PLC) modem to allow data to be transferred at high frequency along the cell bus-bars; this feature is not tested here. A detailed description of its design and verification can be found in our previous work [29]. Each cell is connected singly to a cycler channel, thereby PLC data would need to be extracted from each pair of bus-bars individually, involving greater complexity of cabling compared to using a traditional wired cable.…”

Impact of Battery State of Charge on In-Situ Power Line Communication Within an Intelligent Electric Vehicle

“…A power line communication (PLC) system enables the power network to be additionally used as a communication channel. It therefore eliminates the need for a specific wiring harness for communication, as the existing power bus bar within the battery pack is utilised [9], [10]. Existing research on the effectiveness and limitations of in-situ PLC within a Li-ion battery pack and its dependence on SoC is limited.…”