Electronics: Stop fusing, start managing – The future of electronics in wiring systems
15. OCT 2019
An older colleague recently told me about a time in the 1980s when one of the turn signals in his first car went dead. He pulled over and, because he had no circuit diagram or tester, simply pulled out each fuse until he found the culprit. Since he always kept spare fuses in his glove compartment, the problem was solved in no time. His car was powered by a small gasoline engine, and the only intelligent thing on board was the driver. Turning our gaze from the past to the future, in only a few years it will be perfectly natural for many people on the highway to take their hands off the steering wheel completely. This level of automated driving is known as “Level 2+” and will be available, at least as a special option, in many vehicle classes in the coming years. Onboard electrical power is also being increasingly used not only to provide energy to the vehicle’s comfort and safety equipment, but also as the primary source of propulsive power in hybrid and full-electric vehicles. This means that whether or not current is flowing becomes a question of existential importance, quite aside from the fact that protecting against unwanted current flow is highly relevant for the functional safety in high-voltage propulsion systems.
With that in mind, I will be at the Wiring Systems Forum at “Bayern Innovativ” at the end of October 2019 to discuss the proposition that the car of the future cannot be created without electronic energy management in the wiring system. This involves not only physically replacing passive electromechanical fuses and relays with actively controllable semiconductor-based fuses, but also designing the entire onboard energy management function as a system. The following points are important here:
Controlling energy instead of switching it off
The higher the level of automation when driving, the longer a vehicle must be kept in a safe state, even without driver intervention, or restored to a safe state even more quickly as soon as an error occurs. The probability of electrical error increases with the number of sensors being used. Whereas about ten sensors are still sufficient for Level 2+, this number increases to about 22 for a Level 4 vehicle, which permits highly automated driving over long distances without driver supervision, and even as many as 25 sensors for fully autonomous, i.e. driverless, driving. These sensors and their corresponding actuators require a reliable power supply. Redundancy in the power supply makes sense only if it can be electronically switched with sufficient speed. Electronic energy management also permits a wide variety of diagnostic possibilities.
A higher level of system automation goes hand-in-hand with a rising number of sensors and increased need for a redundant power supply
Energy management requires system expertise
As a development partner for automotive manufacturers, we regularly perform full vehicle measurement and benchmarking. In the process, we have also tested many vehicles equipped with an “autopilot.” Based upon these measurements, LEONI has developed a test set that can be used to check the stability of the power wiring system and system behavior at the vehicle level. Using targeted error injection, we can discover and eliminate weak points in safety-relevant functions and the associated power and data supply. This methodology is also suitable for checking redundant safety-relevant systems, such as the availability of steering and braking.
The findings demonstrate the importance of a systematic understanding of the entire wiring system when power flows are controlled by software. This is why, in addition to its wiring system know-how, LEONI has also very deliberately developed further expertise in software development and functional safety in recent years.
Full vehicle measurements by LEONI specialists help when designing fail-safe systems
Intelligent energy management is ready for the road
In principle, the idea of controlling power flows using semiconductors is no longer new – they are used in all modern power electronics. This is why our first approach was to use electronic components to recreate a relay-based power distribution unit. We have since expanded this solution by adding an electronic controller, which allows information exchange with other vehicle control devices via communication protocols as LIN or CAN FD. This ready-to-install LEONI solution also includes a housing and connectors. We have already subjected our intelligent power management system to a number of internal tests, and are working with an external partner in SMT manufacturing to prepare for serial production. In other words, we are available for serial development and are already participating in the first request-for-quotations by well-known automotive manufacturers.
Steps in the evolution of LEONI power distribution units, from electromechanical to intelligent devices (with controller and software)
Reducing complexity is part of the solution
Even though I am convinced that electronics know-how is the decisive factor in designing the wiring systems of the future, there is another important aspect: a continuation of “evolved” vehicle wiring system structures, which already have variants of up to 1030 within one model series, simply isn’t practical. That is why future wiring systems will have “zone architectures”. Instead of one large wiring harness connecting innumerable individual actuators, sensors, and control devices, vehicles will instead have distributed wiring harness modules that radiate in a star shape from one high-performance computer. Simplifying the wiring system structure also allows for highly automated production of these wiring harnesses. This will both increase quality and help to achieve functional safety goals for highly automated driving.
Zone architecture: an important feature in wiring systems of the future
The trend toward simplification also includes high-voltage wiring harnesses in electric vehicles. An increasing number of electronic components are already being combined and this will continue to be the case in the future, which will reduce the complexity of high-voltage wiring harnesses. LEONI is planning additional capabilities for its future wiring systems, however, since our goal in the high-voltage segment is to offer not only battery wiring, but also electronic solutions.
The best way to find an optimal solution for a particular vehicle platforms through dialogue. As a system partner for all aspects of vehicle power distribution systems, we are happy to support you!