Trend
Vehicle electrification – trends in high-voltage connection systems
By Dermot Byrne, Industry Marketing Director, Transportation, TTI A
s the European Union implements its Green Deal goal to be carbon neutral by 2050, governments and envi- ronmental groups are
demanding cleaner cities and a reduction in greenhouse gases and other pollutants. To stimulate demand, European countries are increasing subsidies to vehicle owners to encourage them to invest in electric vehicles as a reliable and alternative clean method of transportation. Tis change is in turn driving manufacturers of vehicles as diverse as e-bikes, cars, vans, buses and agriculture and construction equipment to rethink their designs and adopt electric and hybrid transmissions to increase the efficiency of their powertrains whilst elimi- nating exhaust gases and pollutants. For the engineers developing these
next-generation systems, selecting the right high-voltage connection system can be a daunting task. Should they use shielded or unshielded connection systems, plastic or metal connectors, flat blade or circular contacts, PCB or busbar-mounted connection systems? How will they meet their sealing performance, vibration and latching requirements? How can they reduce system costs, and are there second- source suppliers available? These challenges are becoming
increasingly difficult as manufacturers introduce second- and third-generation versions of their high-voltage connection systems. In automotive applications, where
production volumes are usually high, engineers are trying to find a balance between performance, reliability and cost. Connection systems are usually manufactured in plastic housings and feature HVIL contacts, TPA and CPA
Selecting the right high-voltage connection system can be a daunting task
components as standard. Most connectors support voltage levels to 800V, with many German OEMs insisting that these connectors are designed and tested according to LV214 and LV215 standards whilst other OEMs require validation according to USCAR or even an OEM- specific standard. Many connectors feature flat-blade contact systems that both increase the current-carrying capability and enable reliable crimp termination whilst remaining competitive. Examples include TE Connectivity’s PCON12 terminal system, which is used in the new HVA1200 AK Class 2/3 product family that supports currents to 100A for auxiliary device applications. Cost is another critical topic and some
OEMs are demanding second sources for their connection systems. Suppliers like Aptiv are therefore now offering products that are 100% intermateable with other AK Class 1, AK Class 2, AK Class 4 and AK plastic pass-through connection systems, whilst simultaneously improving the connector sealing and vibration performance. Aptiv has also developed its new HV RCS 800/890 Direct Mate connection system, where the cable plug connects directly to metal device housing, again reducing the overall interface cost. An associated trend is that vehicle
manufacturers are reverting back to using lower-cost unshielded cables and
04 November/December 2020
www.electronicsworld.co.uk
connection systems in combination with EMI filters to reduce costs and weight of their systems. In line with this trend, other OEMs are evaluating moving from copper HV cable to an aluminium option in the mid-range amperage and voltage ranges. In heavy equipment and commercial
vehicle applications, designers are focusing on the challenges of meeting the higher power required by these vehicles. Whereas truck and bus OEMs still tend to prefer plastic connection systems, agriculture and construction vehicle OEMs often prefer metal connector systems for increased ruggedness and reliability. Voltage specifications to 1000V are
considered standard, and levels above 500A are becoming more common. Tis requires customers to use thicker 70mm2 95mm2
or 120mm2 cables, which can
be both heavy and expensive. Finding a reliable contact system that allows users to limit cable sizes can help further optimise costs. A final design consideration for
engineers is the high-voltage cable assembly strategy. High-voltage cables are challenging to assemble, and the required crimping and testing equipment can be expensive, so not all traditional harness makers will be able to produce these cables. Particularly for small-volume OEMs, engineers must consider up front if they should build cables in-house, source from a local cable harness maker or distributor, or if their volumes can be supplied directly by a connector manufacturer. Finding the right local partner or
distributor during the development phase can make sourcing a lot simpler when the vehicle is ready to go into full production.
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