Physical layer and multi-carrier analysis for power line communication networks in Li-ion batteries for electric and hybrid vehicles

Power line communication (PLC) in automotive traction batteries is an innovative technology for next-generation lithium-ion (Li-ion) battery packs. PLC avoids a dedicated wire harness for communication in Li-ion battery packs and helps to reduce weight and production costs. Moreover, PLC enables higher data rates than currently used communication systems, such as the controller area network. The additional data rate is mainly assigned to safety purposes, since Li-ion batteries are potentially harmful for users and the environment. Thus, a fast communication system with low latency must be developed, which works reliably in an unusual environment. Despite the short distances between receiver and transmitter in a battery, the channel shows high attenuation and several resonances. A suitable frequency range must be found in order to ensure a reliable communication link. For this purpose, we analyzed the PLC channel inside a traction battery. We determined the coherence bandwidth and a similarity factor between positions in the battery pack. These results show that a center frequency of 500 MHz is appropriate. In order to verify this, we performed bit error rate (BER) simulations with an orthogonal frequency division multiplexing (OFDM) system for different positions in the battery pack. The results suggest that the relation of energy per bit to spectral noise power density must be 9 dB to satisfy all system requirements.