Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005128
Silviu S. Craciunas, Ramon Serna Oliver, Valentin Ecker
Mixed-criticality and high availability distributed systems, like those on large industrial deployments, strongly rely on deterministic communication in order to guarantee the realtime behavior. The time-triggered paradigm-as in TTEthernet-guarantees the deterministic delivery of messages with fixed latency and limited jitter. We look closely at industrial deployments in which production as well as consumption of messages is carried out within software tasks running on distributed embedded nodes (i.e. end-systems). We present an approach to minimize the end-to-end latency of such tasks, respecting their precedence constraints as well as the scheduled communication in an underlying switched TTEthernet network. The approach is based on and validated by a large industrial use-case for which we analyze a test bed implementing our solution.
{"title":"Optimal static scheduling of real-time tasks on distributed time-triggered networked systems","authors":"Silviu S. Craciunas, Ramon Serna Oliver, Valentin Ecker","doi":"10.1109/ETFA.2014.7005128","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005128","url":null,"abstract":"Mixed-criticality and high availability distributed systems, like those on large industrial deployments, strongly rely on deterministic communication in order to guarantee the realtime behavior. The time-triggered paradigm-as in TTEthernet-guarantees the deterministic delivery of messages with fixed latency and limited jitter. We look closely at industrial deployments in which production as well as consumption of messages is carried out within software tasks running on distributed embedded nodes (i.e. end-systems). We present an approach to minimize the end-to-end latency of such tasks, respecting their precedence constraints as well as the scheduled communication in an underlying switched TTEthernet network. The approach is based on and validated by a large industrial use-case for which we analyze a test bed implementing our solution.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"6 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81452265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005032
C. Hadjicostis, Christoforos Keroglou
In many emerging security applications, a property of a system, that may reveal important details about its behaviour, needs to be kept secret (opaque) to outside observers (intruders). Motivated by such applications, several authors have formalized, analyzed, and described methods to verify notions of opacity in discrete event systems of interest. This paper offers a review of various definitions of opacity, along with methodologies for their verification and complexity analysis. We review state-based notions of opacity (namely, current-state opacity and initial-state opacity) in non-deterministic finite automata, as well as their extensions to stochastic settings. Specifically, we discuss these notions of opacity and methods to verify them in discrete event systems modeled by non-deterministic finite automata (NFA's) or probabilistic finite automata (PFA's).
{"title":"Opacity formulations and verification in discrete event systems","authors":"C. Hadjicostis, Christoforos Keroglou","doi":"10.1109/ETFA.2014.7005032","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005032","url":null,"abstract":"In many emerging security applications, a property of a system, that may reveal important details about its behaviour, needs to be kept secret (opaque) to outside observers (intruders). Motivated by such applications, several authors have formalized, analyzed, and described methods to verify notions of opacity in discrete event systems of interest. This paper offers a review of various definitions of opacity, along with methodologies for their verification and complexity analysis. We review state-based notions of opacity (namely, current-state opacity and initial-state opacity) in non-deterministic finite automata, as well as their extensions to stochastic settings. Specifically, we discuss these notions of opacity and methods to verify them in discrete event systems modeled by non-deterministic finite automata (NFA's) or probabilistic finite automata (PFA's).","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"51 1","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86155199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005211
S. Biffl, D. Winkler, Richard Mordinyi, Stefan Scheiber, G. Holl
In a multi-disciplinary engineering project, such as the parallel engineering of industrial production plants, domain experts want to efficiently monitor project-level constraints that depend on technical parameter values in local engineering models. However, the heterogeneous representations of constraint parameters in these engineering models make the automation of constraint monitoring difficult. In this paper, we introduce the Multi-Model Dashboard (MMD) process providing semantically integrated values of parameters and of constraints to domain experts, as parameter values in various local models change during the project. The tool-supported MMD process guides the definition and monitoring of MMD parameters and constraints. We evaluate the effectiveness and efficiency of the MMD process in a feasibility study with requirements and data from real-world use cases at industry partners. Major results are that the MMD process was effective and efficient in eliciting relevant project constraints and model dependencies and in providing data for change impact analysis.
{"title":"Efficient monitoring of multi-disciplinary engineering constraints with semantic data integration in the Multi-Model Dashboard process","authors":"S. Biffl, D. Winkler, Richard Mordinyi, Stefan Scheiber, G. Holl","doi":"10.1109/ETFA.2014.7005211","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005211","url":null,"abstract":"In a multi-disciplinary engineering project, such as the parallel engineering of industrial production plants, domain experts want to efficiently monitor project-level constraints that depend on technical parameter values in local engineering models. However, the heterogeneous representations of constraint parameters in these engineering models make the automation of constraint monitoring difficult. In this paper, we introduce the Multi-Model Dashboard (MMD) process providing semantically integrated values of parameters and of constraints to domain experts, as parameter values in various local models change during the project. The tool-supported MMD process guides the definition and monitoring of MMD parameters and constraints. We evaluate the effectiveness and efficiency of the MMD process in a feasibility study with requirements and data from real-world use cases at industry partners. Major results are that the MMD process was effective and efficient in eliciting relevant project constraints and model dependencies and in providing data for change impact analysis.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"42 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86302759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005101
Thomas Glatzl, H. Steiner, F. Kohl, T. Sauter, F. Keplinger
The characterization and optimization of a low-cost thermal flow sensor optimized for the use in heating ventilating and air conditioning (HVAC) systems is presented. The fabrication of the transducer is exclusively based on printed circuit board technology to keep costs low and allow for easy handling and replacement. The measurement principle utilizes a calorimetric principle with thermoresistive heat transfer. The thermistors form a Wheatstone bridge while the heating element is supplied with a constant current. The AC bridge output voltage is a function of the flow offering adequate sensitivity and a suitable measurement range for HVAC systems. The main experiments focus on flow measurements with a Lock-In amplifier technique to evaluate the measurement range and sensitivity. Based on prior results for time constants, output voltage, sensitivity, etc., the sensor design has been optimized.
{"title":"Characterization and optimization of a thermal flow sensor on circuit board level","authors":"Thomas Glatzl, H. Steiner, F. Kohl, T. Sauter, F. Keplinger","doi":"10.1109/ETFA.2014.7005101","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005101","url":null,"abstract":"The characterization and optimization of a low-cost thermal flow sensor optimized for the use in heating ventilating and air conditioning (HVAC) systems is presented. The fabrication of the transducer is exclusively based on printed circuit board technology to keep costs low and allow for easy handling and replacement. The measurement principle utilizes a calorimetric principle with thermoresistive heat transfer. The thermistors form a Wheatstone bridge while the heating element is supplied with a constant current. The AC bridge output voltage is a function of the flow offering adequate sensitivity and a suitable measurement range for HVAC systems. The main experiments focus on flow measurements with a Lock-In amplifier technique to evaluate the measurement range and sensitivity. Based on prior results for time constants, output voltage, sensitivity, etc., the sensor design has been optimized.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"77 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83902615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005118
G. Gracioli, A. A. Fröhlich
Modern multicore platforms feature multiple levels of cache memory placed between the processor and main memory to hide the latency of ordinary memory systems. The primary goal of this cache hierarchy is to improve average execution time (at the cost of predictability). The uncontrolled use of the cache hierarchy by real-time tasks may impact the estimation of their worst-case execution times (WCET). Software cache partitioning through page coloring has been considered a promising approach to isolate task workloads and thus improve WCET estimation. However, when real-time tasks share cache partitions due to false or true sharing, the inter-core delay caused by the cache coherence protocol may cause deadline losses. In this paper, we propose a Color-Aware task Partitioning (CAP) algorithm that assigns tasks to cores respecting their usage of cache partitions (i.e., colors). Tasks that share one or more colors are grouped together and the whole group is assigned to the same processor. Thus, it is possible to avoid inter-core interference. We compared the deadline miss ratio of several generated task sets partitioned by the CAP algorithm and by the worst-fit decreasing heuristic. We executed the partitioned task sets in a modern 8-core processor with shared L3-cache using a real-time operating system. Our results indicate that a color-aware task partitioning algorithm can avoid deadline misses in a multicore processor with shared cache.
{"title":"CAP: Color-aware task partitioning for multicore real-time applications","authors":"G. Gracioli, A. A. Fröhlich","doi":"10.1109/ETFA.2014.7005118","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005118","url":null,"abstract":"Modern multicore platforms feature multiple levels of cache memory placed between the processor and main memory to hide the latency of ordinary memory systems. The primary goal of this cache hierarchy is to improve average execution time (at the cost of predictability). The uncontrolled use of the cache hierarchy by real-time tasks may impact the estimation of their worst-case execution times (WCET). Software cache partitioning through page coloring has been considered a promising approach to isolate task workloads and thus improve WCET estimation. However, when real-time tasks share cache partitions due to false or true sharing, the inter-core delay caused by the cache coherence protocol may cause deadline losses. In this paper, we propose a Color-Aware task Partitioning (CAP) algorithm that assigns tasks to cores respecting their usage of cache partitions (i.e., colors). Tasks that share one or more colors are grouped together and the whole group is assigned to the same processor. Thus, it is possible to avoid inter-core interference. We compared the deadline miss ratio of several generated task sets partitioned by the CAP algorithm and by the worst-fit decreasing heuristic. We executed the partitioned task sets in a modern 8-core processor with shared L3-cache using a real-time operating system. Our results indicate that a color-aware task partitioning algorithm can avoid deadline misses in a multicore processor with shared cache.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"73 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82876432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005159
M. Obst, Anna Hahn, L. Urbas
The integration of package units in a SCADA or DCS involves considerable manual effort. Various aspects of automation such as faceplates, states of sequences or interlocks have to be reproduced for the visualization and management of the package unit in the master control system. The integration effort can be reduced using existing technologies, which could also be extended to a modular plug-and-produce methodology. An essential precondition for this is a uniform formal quantitative description of various aspects of the package unit and tool chains based on the formal descriptions. This paper will present an approach using the description language EDDL, which is established in the field of field device integration.
{"title":"Package unit integration for process industry — A new description approach","authors":"M. Obst, Anna Hahn, L. Urbas","doi":"10.1109/ETFA.2014.7005159","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005159","url":null,"abstract":"The integration of package units in a SCADA or DCS involves considerable manual effort. Various aspects of automation such as faceplates, states of sequences or interlocks have to be reproduced for the visualization and management of the package unit in the master control system. The integration effort can be reduced using existing technologies, which could also be extended to a modular plug-and-produce methodology. An essential precondition for this is a uniform formal quantitative description of various aspects of the package unit and tool chains based on the formal descriptions. This paper will present an approach using the description language EDDL, which is established in the field of field device integration.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"1 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82830906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005141
David Hästbacka, L. Barna, M. Karaila, Yiqing Liang, P. Tuominen, S. Kuikka
Condition monitoring and maintenance of devices and equipment is an important aspect of operating a production facility affecting the availability of production systems. Modern production environments can consist of thousands of devices that each need to be monitored so that maintenance can be performed when necessary to sustain a cost-effective state of production. Today operation and maintenance (O&M) is typically outsourced, and equipment and device manufacturers have also entered the service business. This brings challenges in managing a multitude of different devices using different protocols as well as in the varying needs for utilizing this information in enterprise functions and services. Based on OPC Unified Architecture (UA) a scalable architecture is developed for providing device status information of heterogeneous field devices and sensors to enterprise level applications and services. A proof of concept implementation of this architecture is presented and its envisioned adoption in a mine environment is discussed.
{"title":"Device status information service architecture for condition monitoring using OPC UA","authors":"David Hästbacka, L. Barna, M. Karaila, Yiqing Liang, P. Tuominen, S. Kuikka","doi":"10.1109/ETFA.2014.7005141","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005141","url":null,"abstract":"Condition monitoring and maintenance of devices and equipment is an important aspect of operating a production facility affecting the availability of production systems. Modern production environments can consist of thousands of devices that each need to be monitored so that maintenance can be performed when necessary to sustain a cost-effective state of production. Today operation and maintenance (O&M) is typically outsourced, and equipment and device manufacturers have also entered the service business. This brings challenges in managing a multitude of different devices using different protocols as well as in the varying needs for utilizing this information in enterprise functions and services. Based on OPC Unified Architecture (UA) a scalable architecture is developed for providing device status information of heterogeneous field devices and sensors to enterprise level applications and services. A proof of concept implementation of this architecture is presented and its envisioned adoption in a mine environment is discussed.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"73 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90341964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005340
A. Betzler, Carles Gomez, I. Demirkol, Matthias Kovatsch
The Constrained Application Protocol (CoAP) is a new Web protocol for the Internet of Things that allows to connect IoT devices directly to services hosted in the cloud. CoAP is based on UDP to better fit the requirements of constrained environments with resource-constrained nodes and low-power communication links. Being an Internet protocol, CoAP must still adhere to congestion control, primarily to keep the backbone network stable. Thus, the base specification uses conservative parameter values for the number of open requests, the retransmission timers, and the overall message rate. More powerful CoAP nodes, however, can use metrics to optimize these parameters to achieve a better quality of service. For this, the IETF CoRE working group is designing an advanced congestion control mechanism for CoAP called CoCoA. This paper presents first evaluation results for a mechanism that improves the communication between cloud services and resource-constrained IoT devices. We implement CoCoA for the Californium (Cf) CoAP framework and evaluate its performance on a wireless sensor network testbed that runs IPv6. Our results show that CoCoA can better utilize the available network capacity and can increase throughput by 19-112%.
{"title":"Congestion control for CoAP cloud services","authors":"A. Betzler, Carles Gomez, I. Demirkol, Matthias Kovatsch","doi":"10.1109/ETFA.2014.7005340","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005340","url":null,"abstract":"The Constrained Application Protocol (CoAP) is a new Web protocol for the Internet of Things that allows to connect IoT devices directly to services hosted in the cloud. CoAP is based on UDP to better fit the requirements of constrained environments with resource-constrained nodes and low-power communication links. Being an Internet protocol, CoAP must still adhere to congestion control, primarily to keep the backbone network stable. Thus, the base specification uses conservative parameter values for the number of open requests, the retransmission timers, and the overall message rate. More powerful CoAP nodes, however, can use metrics to optimize these parameters to achieve a better quality of service. For this, the IETF CoRE working group is designing an advanced congestion control mechanism for CoAP called CoCoA. This paper presents first evaluation results for a mechanism that improves the communication between cloud services and resource-constrained IoT devices. We implement CoCoA for the Californium (Cf) CoAP framework and evaluate its performance on a wireless sensor network testbed that runs IPv6. Our results show that CoCoA can better utilize the available network capacity and can increase throughput by 19-112%.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"11 2 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83661643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005187
O. Niggemann, Bjorn Kroll
The efficient handling of complex production systems and the implementation of more flexible and adaptable production lies at the heart of cyber-physical production systems and its german equivalent Industry 4.0. Such scenarios currently face one main difficulty: the creation, configuration and maintenance of the corresponding automation software is time-consuming and error-prone. Two main solutions exist for this problem: (i) model-based software development and (ii) intelligent automation, i.e. the usage of new knowledge-based solution approaches. This article compares these different solutions by applying them to three phases of the life-cycle: the planning phase, the operation phase and the plant modification phase.
{"title":"On the applicability of model based software development to cyber physical production systems","authors":"O. Niggemann, Bjorn Kroll","doi":"10.1109/ETFA.2014.7005187","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005187","url":null,"abstract":"The efficient handling of complex production systems and the implementation of more flexible and adaptable production lies at the heart of cyber-physical production systems and its german equivalent Industry 4.0. Such scenarios currently face one main difficulty: the creation, configuration and maintenance of the corresponding automation software is time-consuming and error-prone. Two main solutions exist for this problem: (i) model-based software development and (ii) intelligent automation, i.e. the usage of new knowledge-based solution approaches. This article compares these different solutions by applying them to three phases of the life-cycle: the planning phase, the operation phase and the plant modification phase.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"4 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83166687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/ETFA.2014.7005314
H. Martínez, A. Grau-Saldes
Linear-assisted DC/DC converters (or linear-switching hybrid DC/DC converters) consist of a voltage linear regulator (classic NPN or nMOS topologies and LDO) connected in parallel with a switching DC/DC converter. In order to control these hybrid structures, different strategies exist, allowing to fix the switching frequency as a function of some parameters of the linear regulator. This article compares two control strategies that, although can be applied to the same circuital structure of linear-assisted converter, are sensibly different. The first one, reported in previous literature, cancels completely the average current through the linear regulator in steady state to achieve a reduction of the losses. Thus the efficiency of the whole system increases and almost equals the one of the standalone switching converter. The proposed approach, in spite of a slightly increment of linear regulator's losses, reduces the output ripple due to the crossover distortion of linear regulator output stage.
{"title":"Capacitorless DC-DC converter","authors":"H. Martínez, A. Grau-Saldes","doi":"10.1109/ETFA.2014.7005314","DOIUrl":"https://doi.org/10.1109/ETFA.2014.7005314","url":null,"abstract":"Linear-assisted DC/DC converters (or linear-switching hybrid DC/DC converters) consist of a voltage linear regulator (classic NPN or nMOS topologies and LDO) connected in parallel with a switching DC/DC converter. In order to control these hybrid structures, different strategies exist, allowing to fix the switching frequency as a function of some parameters of the linear regulator. This article compares two control strategies that, although can be applied to the same circuital structure of linear-assisted converter, are sensibly different. The first one, reported in previous literature, cancels completely the average current through the linear regulator in steady state to achieve a reduction of the losses. Thus the efficiency of the whole system increases and almost equals the one of the standalone switching converter. The proposed approach, in spite of a slightly increment of linear regulator's losses, reduces the output ripple due to the crossover distortion of linear regulator output stage.","PeriodicalId":20477,"journal":{"name":"Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA)","volume":"1 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90931802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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