@inproceedings{ReindlWetzelNiemetzetal., author = {Reindl, Andrea and Wetzel, Daniel and Niemetz, Michael and Meier, Hans}, title = {Leader Election in a Distributed CAN-Based Multi-Microcontroller System}, series = {2023 3rd International Conference on Electrical, Computer, Communications and Mechatronics Engineering (ICECCME), 19-21 July 2023, Tenerife, Canary Islands, Spain}, booktitle = {2023 3rd International Conference on Electrical, Computer, Communications and Mechatronics Engineering (ICECCME), 19-21 July 2023, Tenerife, Canary Islands, Spain}, publisher = {IEEE}, address = {Piscataway, NJ, USA}, isbn = {979-8-3503-2297-2}, doi = {10.1109/ICECCME57830.2023.10252250}, pages = {1 -- 8}, abstract = {In a distributed system, functionally equivalent nodes work together to form a system with improved availability, reliability and fault tolerance. Thereby, the purpose is to achieve a common control objective. As multiple components cooperate to accomplish tasks, coordination between them is required. Electing a node as the temporary leader can be a possible solution to perform coordination. This work presents a self-stabilizing algorithm for the election of a leader in dynamically reconfigurable bus topology-based broadcast systems with a message and time complexity of O(1). The election is performed dynamically, i.e., not only when the leader node fails, and is criterion-based. The criterion used is a performance related value which evaluates the properties of the node regarding the ability to perform the tasks of the leader. The increased demands on the leader are taken into account and a re-election is started when the criterion value drops below a predefined level. The goal here is to distribute the load more evenly and to reduce the probability of failure due to overload of individual nodes. For improved system availability and reduced fault rates, a management level consisting of leader, assistant and co-assistant is introduced. This reduces the number of required messages and the duration in case of non-initial election. For further reduction of required messages to uniquely determine a leader, the CAN protocol is exploited. The proposed algorithm selects a node with an improved failure rate and a reduced message and hence time complexity while satisfying the safety and termination constraints. The operation of the algorithm is validated using a hardware test setup.}, language = {en} } @inproceedings{ReindlLausserErikssonetal., author = {Reindl, Andrea and Lausser, Florian and Eriksson, Lars and Park, Sangyoung and Niemetz, Michael and Meier, Hans}, title = {Control Oriented Mathematical Modeling of a Bidirectional DC-DC Converter - Part 1: Buck Mode}, series = {28th International Conference on Applied Electronics (AE) 2023, Pilsen, 6-7 September 2023}, booktitle = {28th International Conference on Applied Electronics (AE) 2023, Pilsen, 6-7 September 2023}, editor = {Pinker, Jiř{\´i}}, publisher = {University of West Bohemia}, address = {Pilsen}, isbn = {979-8-3503-3554-5}, doi = {10.1109/AE58099.2023.10274168}, pages = {1 -- 7}, abstract = {Parallel connection of different batteries equipped with bidirectional DC-DC converters offers an increase of the total storage capacity, the provision of higher currents and an improvement of reliability and system availability. To share the load current among the DC-DC converters while maintaining the safe operating range of the batteries, appropriate controllers are needed. The basis for the design of these control approaches requires knowledge of both the static and dynamic characteristics of the DC-DC converter used. In this paper, the small signal analysis of a DC-DC converter in buck mode is shown using the circuit averaging technique. The paper gives an overview of all required transfer functions:. The control and line to output transfer functions for CCM and DCM relevant for average current mode control as well as for voltage control are derived and their poles and zeros are determined. This provides the basis for stability consideration, analysis of the overall control structure and controller design.}, language = {en} } @inproceedings{ReindlLangerMeieretal., author = {Reindl, Andrea and Langer, Tobias and Meier, Hans and Niemetz, Michael}, title = {Comparative Reliability Analysis for Single and Dual CAN (FD) Systems}, series = {27th 2022 International Conference on Applied Electronics (AE): 6-7 September 2022, Pilsen, Czech Republic}, booktitle = {27th 2022 International Conference on Applied Electronics (AE): 6-7 September 2022, Pilsen, Czech Republic}, publisher = {IEEE}, isbn = {9781665494816}, doi = {10.1109/AE54730.2022.9920078}, pages = {1 -- 6}, abstract = {Modern cyber-physical systems, such as autonomous vehicles, advanced driver assistance systems, automation systems and battery management systems, result in extended communication requirements regarding the reliability and the availability. The Controller Area Network (CAN) is a broadcast-based protocol which is still used as a standard for serial communication between individual microcontrollers due to its reliability and low power consumption. In addition, it provides mechanisms for detecting transmission errors and retransmitting messages in the event of an error. The enhancement CAN Flexible Data-Rate (CAN FD) offers increased data rates and transmission rates in order to meet the data throughput requirements. In this paper, the mechanisms for reliable data transmission in a CAN FD network are analyzed. To improve reliability, a second identical CAN-FD network is added to the system, using the additional CAN interface already available on common microcontrollers. The redundant communication network is examined in terms of failure rates and the mean time to failure. The reliability over the operation time is calculated for the single and the redundant version of the CAN FD network using the failure rate limits of the ASIL levels.}, language = {en} } @inproceedings{ReindlLangNiemetzetal., author = {Reindl, Andrea and Lang, Andreas and Niemetz, Michael and Meier, Hans}, title = {Switching and Averaging Models of a Bidirectional, Half-Bridge Based DC-DC converter with Load Distribution}, series = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, booktitle = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, publisher = {OJS}, doi = {10.3384/ecp204683}, abstract = {Batteries are used in numerous applications such as mobile devices, electric vehicles, home storage systems and islanded microgrids. Bidirectional DC-DC converters are vital for the integration of batteries, for the power conversion during (dis)charge and the battery management. Modeling of these is helpful, especially for the design of larger, more complex systems consisting of multiple DC-DC converters in parallel. Due to the high switching frequencies, the simulation of DC-DC converters is associated with increased computational time and effort. In this paper, three models of different complexity and accuracy are proposed for a bidirectional DC-DC converter consisting of two phase-shifted half-bridges. Two switching models, which differ mainly in the way the mosfets are driven, account for the individual switching operations and exhibit high accuracy. An averaging model replaces the switching elements with current and voltage sources providing the mean values. It is particularly suitable for multiple components and longer simulation durations. The dynamic behavior of the models is analyzed using the step responses of the load current. For validation, these are compared with the theoretical transfer function. The three models are analyzed comparatively in terms of computational time and effort. The calculation time of the averaging model has been reduced by two thirds compared to the strictly complementary switching model and by 96\% relative to the model with diode emulation mode. The averaging model requires only one third of the computation time of the complementary switching model and only 3.5\% of that of the model with diode emulation. Recommendations for the use of the models are given and a possible use case is shown. Two parallel connected DC-DC converters with load current sharing between them are simulated using the averaging model.}, language = {en} }