Abstract
Electric RaceAbout (E-RA) is Metropolia UAS’s student project. It is a road legal battery electric vehicle, which has been fully designed and build by the students. The number of electrical components in vehicles are increasing fast and it is not modern to design a car’s electrical system without benefiting current management system and data bus technologies. We chose to apply Intelligent Wiring System (IWS) in E-RA’s 12V electrical system. IWS-system is distributed current management and prioritization system. Thanks to the IWS - system we were able to reduce the number of wires. All the system components can be located near the actuators. At the same time it lightens wire harness, makes it easier to design and assemble the electrical system. Malfunctions are decreased and the system is easier to repair.
The system consists of a main ECU called Junction center (JuCe) and smaller ECUs called Nodes. Communication between components is executed via CAN bus. The system has a bus of its own but it’s also easy to connect and get working with an external bus. JuCe provides power for the Nodes via four separate power lines. The lines are separated from other wires. JuCe includes an interface for the computer and connectors for inputs.
JuCe’s operating voltage is 8–32V, so it fits straight into almost any vehicle. It is possible to shut down power lines one by one in order to cut down current consumption. This property is beneficial, for example when the vehicle is inactive. Nodes feed power to actuators. There are four different types of Nodes. The number and type of outputs and inputs vary, but the basic function is same in every Node. The system contains an over current protection so fuses are not needed. The protection is realized with electronics. Each output in JuCe and Node contains a smartfet which measures current and shuts down output if current rises too high. For example if a short circuit or a malfunction is taking place. The higher current rises, the faster it’s switched off. The function of the actuators can be programmed individually with a state machine which is a relatively simple task even if the functions are complex.
The system also contains a service tool. With the service tool it is possible to track status of the system: bus traffic, battery voltage, current consumption and status of inputs and outputs. IWS system is also easy to expand if needed and easy to modificate for current needs.
The system is modern, simple and lightweight. It gives us opportunity to track our system status, battery voltage, current consumption and log errors and malfunctions. It’s also fully tested and in operation.
Keywords: Electric vehicle, Electrical system, Intelligent wiring, IWS, E-RA