Measurements on Rogowski coils as coupling elements for power line communication in traction lithium-ion batteries

Abstract

We propose Rogowski coils as coupling elements for Power Line Communication (PLC) in lithium-ion batteries for electric and hybrid vehicles. Current battery management systems use standard CAN busses for the communication between the battery control unit (BCU) and battery modules, which comprise lithium-ion cells. In contrast, in next-generation batteries the BCU should communicate with each lithium-ion cell in a battery pack to make them safer and increase their performance. However, this can lead to data rates up to 2 MBit/s, which cannot be handled by a standard CAN bus. Furthermore, connecting battery modules by CAN bus wires increase costs and bulk. We are investigating new data bus concepts in order to make lithium-ion batteries safer, with less cost, and less bulk. The Power Line Communication is one way to reach this goal. Using a battery pack as a power-line network, however, requires a different coupler system than in mains electricity. This is because of high direct currents up to 1000 A, which could easily lead to saturation in an iron-cored coupler. Rogowski coils are air-cored coils with no saturation effects, no matter how high the current. In this paper, we show some experimental measurements, such as measurements of the impedance and the transfer function of Rogowski coils. The results show that Rogowski coils are a viable approach as coupler for PLC in lithium-ion battery packs.