Connectors for electromobility
Small, lightweight, robust
Fortsetzung des Artikels von Teil 1
What a connector must do
Of course, the demands on connectors in electric vehicles depend very much on the particular application, notes Michael Singer. “Growing complexity plus safety standards call for solutions that are technically matured and tested. Components for xEV applications — and thus connectors too — must stand up to the specifications of directives like LV214, ISO 16750-4 test 7 for vibration, TS 16949, UL 94 V-0, VW Crimpnorm VW60330, or LV215 for high voltage.” It takes robust and reliable connectors to contact batteries and electromotors in electric hybrid vehicles. Robustness plus compactness are also needed for the tight confines in which they work.
“What’s expected of the battery management system, the BMS, that’s increased at a rapid pace — naturally in electric and hybrid vehicles”, judges Singer. The BMS is responsible for secure charging and discharging of batteries, and monitors battery cells. Normally it will not be incorporated direct in the high-voltage battery but instead connected over isolated bus systems like CAN. “Basically you want to cut the resistance on the charging input. That means connectors exhibiting as low a resistance as possible, one staying as constant as possible with increasing temperature.” That, he says, can be achieved by the right contact design.
When it comes to safety aspects, security of insertion is especially important in the BMS and inverters. “Failures through interrupted contacts or shorts can have fatal consequences. Work on the connectors should best not use tools.”
Given the trend to decentral automobile designs, components are often placed close to the engine. That might save connecting leads and weight, but the demands on the components increase when it comes to their resistance to vibration, shock, and temperature. “What’s more, all components on the way to a fully electric vehicle must handle higher voltages, like 1000 volts on a high-volt inverter”, resumes Singer. Erni has matched its product portfolio to tougher requirements, like with the MicroBridge cable connector series in a 1.27 mm pitch, which was developed for the automotive test standard LV214 and USCAR. “Matching present demands, we see ourselves well placed with our automotive product portfolio”, reckons Singer.
“Nevertheless we’ll continue to build, like in higher numbers of pins, and what high voltage means in confined space. The subject of flexible circuit boards is increasingly important in terms of electromobility, and we intend to address that too.” Ultimately, says the expert, all components must function securely and safely, but — for reasons of cost — need not be overspecified. “After all, the electromechanical components, including the connectors, account for about 15 percent of the cost of an inverter.”
Stäubli is approaching the demands on connectors through e-mobility with its Multilam technology, enabling very compact development. “When it comes to electromobility too, the connector lives in the shadows, and in the process of a new development isn’t thought of until the end. That adds technical demands, because very often — given the dimensions and design — you cannot just opt for a standard solution”, emphasizes Kauz. “We attempt to make our customers sensitive to the importance of these small, unremarkable components, and to show the consequences of using the wrong connector or one of lesser quality. We aim to start discussing with the customer as early as possible.”
China’s electric car quota
As of 2019, automakers that produce or import more than 30,000 vehicles annually must sell 10 percent as electric vehicles, and are rated by a points system. Depending on whether it is a purely electric or a hybrid vehicle, and depending on range, the producers are awarded more or fewer points.
The quota of 10 percent is to increase to 12 percent as of 2020. If a carmaker fails to meet the target, they must purchase credit points from another company, or pay a penalty.
- Small, lightweight, robust
- What a connector must do
