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1. Electric Drives with Wide Bandgap Devices for Two-Phase Very Low Inductance Machines

   Zhang, Y.; Lawhorn, D. L.; Han, P.; Cramer, A. M.; Ionel, D. M. (October 2020, Proceedings, 2020 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI)

   Slotless and coreless machines with low inductance and low core losses are attractive for high speed and high power density applications. With the increase in fundamental frequency, typical drive implementations using conventional silicon-based devices are performance limited and also produce large current and torque ripples. This paper presents a systematic study of proposed drive configurations implemented with wide bandgap (WBG) devices in order to mitigate such issues for 2-phase very low inductance machines. Two inverter topologies, i.e., a dual H-bridge inverter with maximum redundancy and survivability and a 3-leg inverter for reduced cost, are considered. Feasible modulation schemes are derived based on theoretical analysis and the associated maximum output voltages are identified. Simulation and experimental results are provided to validate the feasibility of drive systems and the effectiveness of analysis. 

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2. Machine Learning-Based Protection and Fault Identification of 100% Inverter-Based Microgrids

   https://doi.org/10.1109/ISIE54533.2024.10595742  

   Beikbabaei, Milad; Lindemann, Michael; Kapourchali, Mohammad Heidari; Mehrizi-Sani, Ali (June 2024, IEEE)

   100% inverter-based renewable units are becoming more prevalent, introducing new challenges in the protection of microgrids that incorporate these resources. This is particularly due to low fault currents and bidirectional flows. Previous work has studied the protection of microgrids with high penetration of inverter-interfaced distributed generators; however, very few have studied the protection of a 100% inverter-based microgrid. This work proposes machine learning (ML)–based protection solutions using local electrical measurements that consider implementation challenges and effectively combine short-circuit fault detection and type identification. A decision tree method is used to analyze a wide range of fault scenarios. PSCAD/EMTDC simulation environment is used to create a dataset for training and testing the proposed method. The effectiveness of the proposed methods is examined under seven distinct fault types, each featuring varying fault resistance, in a 100% inverter-based microgrid consisting of four inverters. 

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3. Improved Lifetime of GaN-Based Single Phase PV Inverter Using Dynamic Hardware Allocation

   https://doi.org/10.1109/ECCE47101.2021.9595850  

   Sabi, Kamal; Costinett, Daniel (October 2021, 2021 IEEE Energy Conversion Congress and Exposition (ECCE))

   Power electronic inverters for photovoltaic (PV) systems over the years have trended towards high efficiency and power density. However, reliability improvements of inverters have received less attention. Inverters are one of the lifetime-limiting elements in most PV systems. Their failures increase system operation and maintenance costs, contributing to an increased lifetime energy cost of the PV system. Opportunities exist to increase inverter reliability through design for reliability techniques and the use of new modular topologies, semiconductor devices, and energy buffering schemes. This paper presents the implementation and design for reliability for a GaN-based single-phase residential string inverter using a new topological and control scheme that allows dynamic hardware allocation (DHA). In the proposed inverter architecture, a range of identical modules and control schemes are used to dispatch hardware resources within the inverter to variably deliver power to the load or filter the second harmonic current on the DC side. This new approach more than triples the lifetime of GaN-based inverters, reducing system repair/replacement costs, and increasing the PV system lifetime energy production. 

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4. Impact of Solar Inverter Dynamics during Grid Restoration Period on Protection Schemes Based on Negative-Sequence Components

   https://doi.org/10.3390/en15124360  

   Ekic, Almir; Wu, Di; Jiang, John N. (June 2022, Energies)

   The growing penetration of renewable resources such as wind and solar into the electric power grid through power electronic inverters is challenging grid protection. Due to the advanced inverter control algorithms, the inverter-based resources present fault responses different from conventional generators, which can fundamentally affect the way that the power grid is protected. This paper studied solar inverter dynamics focused on negative-sequence quantities during the restoration period following a grid disturbance by using a real-time digital simulator. It was found that solar inverters can act as negative-sequence sources to inject negative-sequence currents into the grid during the restoration period. The negative-sequence current can be affected by different operating conditions such as the number of inverters in service, grid strength, and grid fault types. Such negative-sequence responses can adversely impact the performance of protection schemes based on negative-sequence components and potentially cause relay maloperations during the grid restoration period, thus making system protection less secure and reliable. 

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5. A low-cost shutter driver and arbitrary waveform generator for optical switching using a programmable system-on-chip (PSoC) device

   https://doi.org/10.1063/5.0105884  

   Craven, J. M.; Meeks, E.; Delich, G.; Ayars, E.; Pechkis, H. K.; Pechkis, J. A. (November 2022, Review of Scientific Instruments)

   We have developed a low-cost mechanical shutter driver with integrated arbitrary waveform generation for optical switching and control using a programmable system-on-chip device. This microcontroller-based device with configurable digital and analog blocks is readily programmed using free software, allowing for easy customization for a variety of applications. Additional digital and analog outputs with arbitrary timings can be used to control a variety of devices, such as additional shutters, acousto-optical modulators, or camera trigger pulses, for complete control and imaging of laser light. Utilizing logic-level control signals, this device can be readily integrated into existing computer control and data acquisition systems for expanded hardware capabilities. 

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