Pub Date : 2024-02-12DOI: 10.1109/OJIES.2024.3361167
Tomas Salvadores;Javier Pereda;Félix Rojas
The modular multilevel converter (MMC) can integrate distributed energy systems (DES), such as a battery energy storage system, to expand its functionalities and carry out multiple simultaneous tasks. However, a DES induces power imbalances within the MMC, which affects the operating currents and voltages of the converter. This phenomenon has been partially covered in recent works, but an analytical analysis has not yet been carried out to see the behavior and implications in different MMC-DES applications. This article introduces a novel analytical analysis of the power imbalances between MMC clusters. It pioneers the development of general equations and imbalance capability metrics, enabling the assessment of maximum currents and voltages supported by the MMC clusters. The developed tools allow the evaluation of any MMC-DES application regarding the current and voltage rating requirements of MMC clusters. The analysis shows that the MMC operating mode can substantially restrain or enlarge its imbalance capacity, affecting its suitability for different DES applications. While it needs around 33% current overrating in the worst imbalances, under some operating modes it can reach most imbalances without requiring current overrating. The ac compensation mode is much more capable of achieving imbalances than the dc compensation mode, reaching 88.37% and 16.74% of the imbalance points, respectively, without requiring any overrating.
{"title":"Power Imbalance Analysis of Modular Multilevel Converter With Distributed Energy Systems","authors":"Tomas Salvadores;Javier Pereda;Félix Rojas","doi":"10.1109/OJIES.2024.3361167","DOIUrl":"10.1109/OJIES.2024.3361167","url":null,"abstract":"The modular multilevel converter (MMC) can integrate distributed energy systems (DES), such as a battery energy storage system, to expand its functionalities and carry out multiple simultaneous tasks. However, a DES induces power imbalances within the MMC, which affects the operating currents and voltages of the converter. This phenomenon has been partially covered in recent works, but an analytical analysis has not yet been carried out to see the behavior and implications in different MMC-DES applications. This article introduces a novel analytical analysis of the power imbalances between MMC clusters. It pioneers the development of general equations and imbalance capability metrics, enabling the assessment of maximum currents and voltages supported by the MMC clusters. The developed tools allow the evaluation of any MMC-DES application regarding the current and voltage rating requirements of MMC clusters. The analysis shows that the MMC operating mode can substantially restrain or enlarge its imbalance capacity, affecting its suitability for different DES applications. While it needs around 33% current overrating in the worst imbalances, under some operating modes it can reach most imbalances without requiring current overrating. The ac compensation mode is much more capable of achieving imbalances than the dc compensation mode, reaching 88.37% and 16.74% of the imbalance points, respectively, without requiring any overrating.","PeriodicalId":52675,"journal":{"name":"IEEE Open Journal of the Industrial Electronics Society","volume":"5 ","pages":"109-121"},"PeriodicalIF":8.5,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10433267","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139947272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1109/OJIES.2024.3363500
Hoa Thi Nguyen;Roland Olsson;Øystein Haugen
Analyzing time series data in industrial settings demands domain knowledge and computer science expertise to develop effective algorithms. AutoML approaches aim to automate this process, reducing human bias and improving accuracy and cost-effectiveness. This article applies an evolutionary algorithm to synthesize recurrent neurons optimized for specific datasets. This adds another layer to the AutoML framework, targeting the internal structure of neurons. We developed an imitation learning control system for an industry CNC machine to enhance operators' productivity. We specifically examine two recorded operator actions: adjusting the engagement rates for linear feed rate and spindle velocity. We compare the performance of our evolved neurons with support vector machine and four well-established neural network models commonly used for time series data: simple recurrent neural networks, long-short-term-memory, independently recurrent neural networks, and transformers. The results demonstrate that the neurons evolved via the evolutionary approach exhibit lower syntactic complexity than LSTMs and achieve lower error rates than other networks. They yield error rates 270% lower for the first operation action, while the error rates are 20% lower for the second action. We also show that our evolutionary algorithm is capable of creating skip-connections and gating mechanisms adapted to the specific characteristics of our dataset.
{"title":"Automatic Synthesis of Recurrent Neurons for Imitation Learning From CNC Machine Operators","authors":"Hoa Thi Nguyen;Roland Olsson;Øystein Haugen","doi":"10.1109/OJIES.2024.3363500","DOIUrl":"https://doi.org/10.1109/OJIES.2024.3363500","url":null,"abstract":"Analyzing time series data in industrial settings demands domain knowledge and computer science expertise to develop effective algorithms. AutoML approaches aim to automate this process, reducing human bias and improving accuracy and cost-effectiveness. This article applies an evolutionary algorithm to synthesize recurrent neurons optimized for specific datasets. This adds another layer to the AutoML framework, targeting the internal structure of neurons. We developed an imitation learning control system for an industry CNC machine to enhance operators' productivity. We specifically examine two recorded operator actions: adjusting the engagement rates for linear feed rate and spindle velocity. We compare the performance of our evolved neurons with support vector machine and four well-established neural network models commonly used for time series data: simple recurrent neural networks, long-short-term-memory, independently recurrent neural networks, and transformers. The results demonstrate that the neurons evolved via the evolutionary approach exhibit lower syntactic complexity than LSTMs and achieve lower error rates than other networks. They yield error rates 270% lower for the first operation action, while the error rates are 20% lower for the second action. We also show that our evolutionary algorithm is capable of creating skip-connections and gating mechanisms adapted to the specific characteristics of our dataset.","PeriodicalId":52675,"journal":{"name":"IEEE Open Journal of the Industrial Electronics Society","volume":"5 ","pages":"91-108"},"PeriodicalIF":8.5,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10423805","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139937098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-06DOI: 10.1109/OJIES.2024.3363093
Aswani Radhakrishnan;Jushnah Palliyalil;Sreeja Babu;Anuar Dorzhigulov;Alex James
The hardware implementation of neuromorphic system requires energy and area-efficient hardware. Memristor-based hardware architectures is a promising approach that naturally mimics the switching behavior of the neuron models. However, to build complex neural systems, it is a tedious process to select the right memristor models and architectures that are suitable to be used in a range of realistic conditions. To simplify the design and development of neuromemristive architectures, we present a web-based graphical user interface (GUI) called “PyMem” that uses Keras Python to implement multiple memristor models on multiple neural architectures that can be used to analyze their working under a wide range of hardware variability. Without the need for programming, the GUI provides options for adding variability to the memristors and observing the neural network behavior under realistic conditions. The tool has options to characterize the ideal (software) and nonideal (hardware) for performance analysis including accuracy, precision, recall, and relative current error values.
神经形态系统的硬件实现需要高能效和高面积效率的硬件。基于忆阻器的硬件架构是一种很有前途的方法,它能自然地模拟神经元模型的开关行为。然而,要构建复杂的神经系统,选择适合在各种现实条件下使用的正确忆阻器模型和架构是一个繁琐的过程。为了简化神经忆阻器架构的设计和开发,我们提出了一个名为 "PyMem "的基于网络的图形用户界面(GUI),它使用 Keras Python 在多个神经架构上实现多个忆阻器模型,可用于分析它们在各种硬件变化条件下的工作情况。无需编程,图形用户界面就能为忆阻器提供添加可变性的选项,并观察神经网络在现实条件下的行为。该工具还提供了一些选项,用于描述理想(软件)和非理想(硬件)的性能分析,包括准确度、精确度、召回率和相对电流误差值。
{"title":"PyMem: A Graphical User Interface Tool for Neuromemristive Hardware–Software Co-Design","authors":"Aswani Radhakrishnan;Jushnah Palliyalil;Sreeja Babu;Anuar Dorzhigulov;Alex James","doi":"10.1109/OJIES.2024.3363093","DOIUrl":"https://doi.org/10.1109/OJIES.2024.3363093","url":null,"abstract":"The hardware implementation of neuromorphic system requires energy and area-efficient hardware. Memristor-based hardware architectures is a promising approach that naturally mimics the switching behavior of the neuron models. However, to build complex neural systems, it is a tedious process to select the right memristor models and architectures that are suitable to be used in a range of realistic conditions. To simplify the design and development of neuromemristive architectures, we present a web-based graphical user interface (GUI) called “PyMem” that uses Keras Python to implement multiple memristor models on multiple neural architectures that can be used to analyze their working under a wide range of hardware variability. Without the need for programming, the GUI provides options for adding variability to the memristors and observing the neural network behavior under realistic conditions. The tool has options to characterize the ideal (software) and nonideal (hardware) for performance analysis including accuracy, precision, recall, and relative current error values.","PeriodicalId":52675,"journal":{"name":"IEEE Open Journal of the Industrial Electronics Society","volume":"5 ","pages":"81-90"},"PeriodicalIF":8.5,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10423246","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139916626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-31DOI: 10.1109/OJIES.2024.3360509
Awungabeh Flavis Akawung;Besong John Ebot;Yasutaka Fujimoto
High power-density electric machines present the benefits of high torque and speed. However, this generally comes with heating problems characterized by high temperatures that affect performance. Conventional approaches to address overheating are to include cooling fans or jackets within the stator core of the machine. This approach is challenging to implement in small-size high power-density machines. In this article, a cooling mechanism integrated in the rotor of a high power-density permanent magnet motor is proposed. It comprises a set of six holes, shrouded within a hollow shaft. The mechanism is based on conditioning air due to a centrifugal force that is produced by the rotational speed of the rotor from the inlet. A theoretical model based on flow resistance network is proposed to analyze the airflow rate. An analytical thermal model based on lumped parameter thermal network is developed to analyze the effect of the flow rate on the temperature distribution in the motor. Also, a simulation analysis model was conducted using computational fluid dynamics to analyze the effect of air flowing in the motor. An experimental prototype is developed to verify, validate, and evaluate the proposed cooling model. The cooling system is effective in reducing temperatures from speeds above 6000 min −1