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The thermal behavior of wires within the electrical distribution system (EDS) has a strong impact on the conductor cross section, the type of insulation, the derating, and the fusing system, and therefore on weight, cost, and reliability. Consequently, significant efforts have been made to develop sound static and dynamic thermal models for single wires and wire bundles. However, these models are based on the simplifying assumption that the object is completely surrounded by air, where, with the exception of free convection, airflow can be neglected, and where no interaction with other objects is considered. The approach presented in this paper takes into account the actual environment and routing within a vehicle, where some objects such as metal sheets can be considered as heat sinks and other objects, e.g. a motor block, as heat sources.

Within the scope of the development of autonomous vehicles, the mandatory reliability requirements of the electrical power supply, and consequently of the electrical distribution system (EDS), are increased considerably. In addition, the overall rising number of electrical functions leads to significantly higher electrical power demands, while strict cost, weight and packaging constraints must be upheld. Current developments focus on adding redundancies, enhancing physical robustness, or dimensioning critical components. New approaches address predictive power management, better diagnostic capabilities, and, the subject of this paper, alternative topologies and architectures [1]. These are derivations of the conventional tree structure, as well as ring- or linear-bus-based zonal architectures, which feature in part distributed storage devices or semiconductor switches that rearrange the power paths in case of a fault [2,3].

The reduction of engine-out emissions and increase of the total efficiency is a fundamental approach to reduce the fuel consumption and thus emissions of vehicles driven by combustion engines. Conventional passenger cars are operated mainly in lower part loads for most of their lifetime. Under these conditions, oil temperatures are far below the maximum temperature allowed and dominate inside the journal bearings. Therefore, the objective of this research was to investigate possible potentials of friction reduction by optimizing the combustion engine’s thermal management of the oil circuit. Within the engine investigations, it was shown that especially the friction of the main and connecting rod bearings could be reduced with an increase of the oil supply temperature. Furthermore, on a journal bearing test rig, it was shown that no excessive wear of the bearings is to be expected in case of load increase and simultaneous supply of cooler oil.

Both the rising number of electrical systems and the electrical part of the powertrain are considerably increasing the electrical power requirements of vehicles. As a consequence, multiple voltage supply levels have been introduced. However, even if only the 12V/48V configuration is considered, as in this paper, the number of possible electrical distribution system (EDS) architectures is greatly enlarged. Additional degrees of freedom are the allocation of the loads to the voltage levels, the dimensioning of new components, and the control strategy. Hence, the optimization of such architectures must be based on simulation, which allows the evaluation of a multitude of variants and test scenarios within an acceptable time frame. While strict cost, weight, and quality constraints must be upheld, the stability of the voltage supply is a major focus because a significant part of future electrical systems is highly safety-critical.

Both the integration of safety-critical electrical systems and the increasing power requirements in vehicles present a challenge for electrical distribution systems in terms of reliability, packaging, weight, and cost. In this regard, the wire protection device is a key element, as it determines the reliability of the short circuit detection, the immunity against false tripping, and the wire diameters. Currently, in most cases, thermal fuses are used, due to their low cost and robust design. However, the description of their tripping behavior based only on steady-state currents is insufficient for the increasingly complex current profiles in vehicles. Thus, to achieve an optimum dimensioning of a fuse-wire combination, a profound understanding of the thermal behavior of both components under dynamic load conditions is mandatory. However, the FEM tools used for the thermal design of fuses are relatively slow, require huge calculation resources, and must be well-parameterized.

Currently, circuit breakers and, in most cases, thermal fuses are used for wire protection due to their low cost and robust design. As an alternative, solid state switches are being considered within future electrical distribution systems (EDS) for several reasons, e.g. resetability, diagnosis, smaller tolerances, and reduced dependencies on ambient temperature or arcing. Particularely if combined with benefits on the system level, such an application can be advantageous. The new approach presented in this paper uses a thermal model of the wire instead of only an emulation of the thermal fuse behavior. This allows, based on the electrical current profile, the calculation of the wire temperature and thus a robust and precise protection of the wire. In addition, it minimizes the probability of faulty switching, which is of particular importance with regard to safety-critical electrical functions.

The topology of an EDS, defined by the routing paths and by the location of the distribution boxes and the inline connectors, has a strong impact on weight and required amount of material, especially of copper, as well as on the manufacturing- and assembly time. Although a good part of the routing and packaging is fixed due to technical reasons and carry-over situations, in general there are enough optional paths and locations to allow up to several thousand alternative topologies. For these reasons, an optimization is possible as well as important. For such an optimization, in this paper a method is presented to concurrently minimize predefined criteria, e.g. the required copper, length of the wires, and the overall length of the wire bundles. It is based on designated algorithms for the variation of the topology, the routing, and the calculation of the optimization criteria as mentioned above.

The power requirements of future vehicle electrical distribution systems will increase considerably. Consequently, electrical energy has a major impact on the overall vehicle energy balance, so its generation and storage must be as efficient as possible. The presented concept is based on a voltage-controlled alternator in combination with super capacitors and a corresponding energy management system. The focus is energy efficiency, recuperation, and the use of standard components. A specific hardware in the loop based test set-up was built that allows the control and monitoring of the mechanical and electrical energy flows. Besides the theoretical description, the paper presents first experimental data and results followed by a discussion of the next steps and future potentials.

The integration of safety-critical and major power-consuming electrical systems presents a challenge for the development of future vehicle power nets. Reliability and performance of the electrical network must be enhanced in order to guarantee the power supply to essential electrical consumers at a sufficient degree of power quality. This paper presents a test bench for automotive electrical networks based on a hardware-in-the-loop (HiL) platform. The test bench is used to assess the power and temperature behavior of the wiring harness and the connected power consumers. This characterisation facilitates the development of new tailored automotive electrical networks to meet the increased requirements while efficiently using the available resources.