German research organization Fraunhofer, together with partners from industry and the Fraunhofer IISB, developed an electronic disconnect device that is able to isolate and safeguard against failure of onboard systems in e-vehicles. This module has already been successfully tested in a BMW i3.
German motoring organization ADAC predicts that by 2050 70 % of all new vehicles will feature automated technology. However, safety, especially in the case of an emergency is a big concern. Currently, it is standard practice that areas affected by a fault are isolated by means of an overload protection system. The affected component is shut down completely in the event of a fault, which is only viable provided they are present in duplicate, increasing price and weight of the vehicle.
The goal of the HiBord project is to develop a disconnect device that shuts off faulty components in the onboard electrical system while still safeguarding the supply of power to safety-critical components. This guarantees safe driving without the need to install a duplicate onboard electrical system.
Phillip Arnold, research associate at Fraunhofer IZM, explains: “In conventional systems, any undervoltage while on the road can trigger a sudden and uncontrolled failure of the entire onboard electronics – including the braking and steering systems. This presents an unacceptable risk, particularly when traveling at high speeds. But with our new module, part of the onboard electrical system continues to function as before, so that a fully automated vehicle would still have enough time to convey passengers to safety – onto the emergency lane of the freeway, for example, or a parking lot.”
The device is equipped with 16 MOSFETs – field-effect transistors – to switch or block large electric currents. It is capable of switching up to 180 amperes of current. If this threshold value is exceeded – in the event of a short circuit, for example – the electrical switch opens and thereby shuts off the power. Moreover, given that the MOSFET switches are capable of handling up to 300 amperes and therefore operate well below their maximum permissible load, they have a significantly longer lifetime than conventional solutions.
Testing results showed that the module is capable of reliably isolating a current of up to 700 amperes without there being any propagation of the initial short circuit. There are also clear advantages over conventional systems in terms of switching speeds. While a conventional fuse takes some 20 milliseconds to trip, the disconnect device detects a fault within 10 microseconds and only requires a further 300 microseconds before tripping. This makes it more than 60 times faster than current fuse systems.
Source & Image: Fraunhofer | www.fraunhofer.de
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