Future-ready Wire Harness: Page 2 of 4

April 29, 2019 //By Óscar Ciordia, KDPOF
Future-ready Wire Harness
In the cars of the future with their pronounced dependence on the safe functioning of electronic circuits, electromagnetic interference fields represent a real challenge. But there are strategies and techniques that promise to remedy the situation.

Smart Antenna Modules

Integrated Smart Antenna (ISA) Modules consist of several antennas for signal reception, an Antenna Hub, and an Ethernet connection to the consumers of the antenna signals such as a radio device. If each of the several antennas in a car is routed to its respective ECU with its own cable, the complexity soon becomes unacceptable. The Antenna Hub routes all signals from each antenna to an Ethernet network connected to all receptors of the signals. Gigabit Ethernet over POF is ideally suited for an Ethernet connection due to its natural EMC-free property and supports the rates required by technologies such as LTE-A. In conventional systems, if the roof is not metallic, or has openings, an immense amount of energy is radiated by the coaxial cable that is coupled back into the ISA. This seriously degrades the ISA performance. Replacing the coaxial cable with POF completely solves this issue.

Battery Management Systems

Propulsion batteries in EV or HEVs are grouped into clusters that need to be controlled. Responsible for this control is the so-called Battery Management System (BMS). The BMS communicates with each battery cluster in order to gather information relevant for control, such as state of charge or cell temperature. The BMS in turn sends control commands to the local ECUs inside each cluster.

Although the amount of data moving back and forth between the clusters and the control module is not very high (typically below 100 Mbps), the communication between the BMS control module and the individual clusters is crucial and needs to be very reliable. These BMS links are critical to avoid battery damage, and must be suitable in emergency situations like crashes or fires.


Fig. 1: Galvanic Isolation

 

Optical links between the BMS control module and the battery clusters are the best means to ensure the high reliability needed. Copper-based communications create parasitic loops, which, in the case of emergency events, may translate into dangerous conditions for the driver and occupants. A dielectric medium such as plastic optical fiber reduces to zero the contribution of the data cables to the conducted emissions and conducted immunity. Radiated emissions and radiated immunity can be optimized to pass with ample margin all the OEM specs with high-quality reference designs from the optical PHY vendor.

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