Efficient management through monitoring of Li-ion batteries is critical to the progress of electro-mobility and energy storage globally, since the technology can be hazardous if pushed beyond its safety boundaries. Battery management systems (BMSs) are being actively improved to reduce size, weight, and cost while increasing their capabilities. Using power line communication, wireless monitoring, or hybrid data links are one of the most advanced research directions today. In this work, we propose the use of radio frequency (RF) transceivers as a communication unit that can deliver both wired and wireless services, through their superior analog and digital signal processing capability compared to PLC technology. To validate our approach computational simulation and empirical evaluation was conducted to examine the possibility of using RF transceivers on a direct current (DC) bus for wired BMS. A key advantage of this study is that it proposes a flexible and tested system for communication across a variety of network scenarios, where wireless data links over disrupted connections may be enabled by using this technology in short-range wired modes. This investigation demonstrates that the IEEE 802.15.4-compliant transceivers with operating frequencies of 868 MHz and 2.4 GHz can establish stable data links on a DC bus via capacitive coupling at high data rates.

As the RF communication on 18650 Li-ion cell level has not been reported due to its challenges and constrains, in this work, a valid wireless data link is demonstrated in an enclosed empty metal shell at 868 MHz and 2.4 GHz based on the IEEE 802.15.4 standard. The experimental tests are carried out using two generic unturned radiative structures, a wire loop fitted inside a cell shell, and an open terminal sub miniature version A (SMA), subsequently oriented vertically and horizontally relative to the ground plane. Based on signal strength indicator, bit error rate, and packet error rate, the test characterized a payload of 120 bytes at the highest speed of 150 kbps and 250 kbps supported by the IEEE 802.15.4 for the two communication frequencies. A MATLAB simulation is used in parallel to determine the three-dimensional radiative pattern of the two structures, whereas a three-ray model for multipath range propagation is implemented to complete the empirical experiments. It was demonstrated through testing communication of up to 10 m for both operating frequencies, proving the concept of wireless cell communication within short ranges, an essential feature for monitoring the health of each cell inside future electric vehicles (EVs).

Schottky-type p-GaN gate Gallium Nitride High Electron Mobility Transistors (GaN-HEMTs) suffer from threshold voltage ( ${V_{\mathsf {th}}}$ ) instability phenomenon. Both positive and negative ${V_{\mathsf {th}}}$ shifts are reported when device undertakes the voltage bias, but the impact of this ${V_{\mathsf {th}}}$ instability phenomenon on device switching behaviors is less investigated. In this study, the drain-source voltage ( ${V_{\mathsf {ds}}}$ ) induced bidirectional ${V_{\mathsf {th}}}$ shift in hard-switching condition is characterized and decoupled by an H-bridge based double-pulse test (DPT). Subsequently, the influence of ${V_{\mathsf {th}}}$ shift on switching behaviors is theoretically analyzed and demonstrated through SPICE simulation and experiment, showing how a positive shifted ${V_{\mathsf {th}}}$ can reduce the device turn-on commutation speed and increase the switching losses, and vice versa. The results suggest that the ${V_{\mathsf {th}}}$ instability phenomenon should be considered in accurate switching modeling.

In anticipation of the hybrid utilisation of the radio frequency (RF) wireless transceiver technology embedded in future smart Li-ion battery cells to deliver hybrid links based on power line communication (PLC) and wireless connections, herein we present an empirical high-frequency investigation of the direct current (DC) bus. The focus is to determine, via statistical tools including correlation coefficient (CC), root mean squared error (RMSE) and feature selective validation (FSV) method, the impedance and signal change impact on a possible communication link when fully charged cells are present or completely missing from the bus. Moreover, to establish if technological differences may be accounted for during the empirical experiments, Li-ion cells from two different manufacturers were selected and connected via three subsequent capacitive couplings of 1 µF, 1 nF and 1 pF. According to a methodical comparison by employing CC, RMSE, and FSV over the measured impedance and signal attenuation, this study has shown that the physical DC network is the dominant impedance at high frequencies and that the signal attenuation on the DC line supports communication in the investigated spectrum. The reported findings are critical for in situ hybrid PLC and wireless communication implementation of BMS for Li-ion systems supported through only one RF transceiver.

Updating the road infrastructure requires the potential mass adoption of the road studs currently used in car detection, speed monitoring, and path marking. Road studs commonly include RF transceivers connecting the buried sensors to an offsite base station for centralized data management. Since traffic monitoring experiments through buried sensors are resource expensive and difficult, the literature detailing it is insufficient and inaccessible due to various strategic reasons. Moreover, as the main RF frequencies adopted for stud communication are either 868/915 MHz or 2.4 GHz, the radio coverage differs, and it is not readily predictable due to the low-power communication in the near proximity of the ground. This work delivers a reference study on low-power RF communication ranging for the two above frequencies up to 60 m. The experimental setup employs successive measurements and repositioning of a base station at three different heights of 0.5, 1 and 1.5 m, and is accompanied by an extensive theoretical analysis of propagation, including line of sight, diffraction, and wall reflection. Enhancing the tutorial value of this work, a correlation analysis using Pearson’s coefficient and root mean square error is performed between the field test and simulation results.

Thanks to the recent advancements in the automotive industry, in smart city infrastructure and in electronics miniaturization, low-power wireless sensors are becoming a reference sensing technology connecting the internet of things (IoT) with the conventional world. This study provides an empirical solution to the modern radio location problem of inside-outside position discrimination for a mobile radio frequency (RF) source. The solution is delivered by a detection system that is fully enclosed inside a modern vehicle cabin, whereas the RF ranging is based solely on the received signal strength indicator (RSSI) and the individual sensor’s directivity achieved through shielding. The RF detection system is provided through a low-power wireless sensing network as a complete 2.4 GHz IEEE 802.15.4 solution, anticipating the future integration of this technology in the next generation of smartphones. The RSSI fingerprinting database, which is derived from empirical outdoor measurements for a range up to 5 m, delivers a consistent performance inside the highly RF-reflective vehicle cabin by exploiting the sensor position and directivity, focused on the front of each seat to avoid future human interference. Moreover, a theoretical propagation model based on Friis’ transmission equation constructed on system parameters shows a high correlation with the RSSI fingerprinting experimental model, supporting the consistency of the empirical model, and demonstrating a similar high inside-outside discrimination. The decision algorithm logics used for inside-outside discrimination illustrate a strong example for sensor group decision based on two spatial thresholds: maximum detection range for outside discrimination and the cabin width for inside discrimination. This study’s location system design creates exploitation possibilities beyond the vehicle environment. Various applications that require complete sensor encasement, such as road flushed traffic sensors or underground systems for parking space occupancy detection may benefit from this work’s findings.