Feature: Automotive
This new BMS architecture combines the advantages of both technologies
low-voltage systems like infotainment or ADAS is optical, then they are isolated from the high-voltage/high-energy/ high-risk events, thus preserving their reliability.
Fault protection In mixed 48/12V energy systems, 48V serves power-hungry electric modules like starters, alternators and battery modules, whereas 12V are reserved for the less power-hungry electronic modules like infotainment or ADAS processing units; both domains share the same ground – the car chassis. T e ECU in the 48V domain has components sized for such voltages, typically rated to over 70V, whereas the 12V ECUs are designed to withstand to about 60V. In case of an event like loss of ground in a 48V ECU, and if there are non- isolated links between the 48V and the 12V domains, the electric path between the two will expose the 12V ECUs and their components to high voltages, in turn causing failure or reducing service life.
48V jump-start parasitic high- energy pulse 48V-based energy networks or mixed 12-48V topologies are and will keep being the mainstream powertrains of HEVs and plug-in hybrid electric vehicles (PHEVs). T e electric ground, which is connected to the vehicle chassis and common to both high- and low-voltage ECUs, creates problems on start-up events that frequently take place in such powertrains. For example, the infotainment system shares the electric ground with the energy- generation and control systems. T e high return currents fl owing through the chassis on start-up couple into the infotainment low-voltage system through the cable shielding, which shares the same ground as other systems in the vehicle. Copper cable shielding provides a parallel return path (alternative to the chassis) for the currents of the various ECUs. Due to this, currents higher than 8A can be measured in the cable shielding during a typical jump-start, as reported by some carmakers. If communications between ECUs in the
Optical ports pass EMI and EMS much more easily than copper
EMC compliance EMC qualifi cation is one of the critical steps of platform validation by OEMs. Copper links for communication rates above 100Mb/s need sophisticated and expensive solutions to comply with stringent OEM EMC specs, such as high- quality shielding, controlled pair twisting, complex in-line connectors, and more. Optical ports can pass both EMI and EMS much more easily. T is directly impacts the cost of the harness and the connectors, not to mention the engineering resources assigned to the development and debugging stages.
Demonstrating 50Gb/s automotive Ethernet with datacom component leveraging
32 September 2021
www.electronicsworld.co.uk
Outlook T e key advantages of the optical solution using multi-gigabit speeds with in-vehicle connectivity are, among others, lower EMC thanks to the inherent galvanic isolation, low weight and low cost. Applications from carmakers in Europe and the US validate the comprehensive features and benefi ts of optical network technology. Key optoelectronic, connector and wire-harness vendors
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