Electric vehicle ultra-fast battery chargers: A boost for power system stability?

As a consequence of the exponential growth of the electric vehicle (EV) market, DC fast-charging infrastructure is being rapidly deployed all around the world. Ultra-fast charging (UFC) stations are starting to pose serious challenges to the electric power system operation, mostly due to their high peak power demand and unregulated discontinuous operation. To address these issues, local energy storage can be installed, ensuring a smoother grid power absorption profile and allowing to provide grid-supporting features. In this work, a control solution for the grid-side AC/DC converter of next-generation EV UFC stations is proposed. A virtual synchronous compensator (VSC) control algorithm is implemented, in order to lessen the impact of the charging station on the utility and to provide the full spectrum of grid ancillary services (i.e., frequency regulation, reactive power compensation, harmonic reduction, short circuit current generation, etc.). The proposed control strategy is verified experimentally on a downscaled 15 kVA three-phase inverter, emulating the grid front-end of the charging station

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Decoupled and Modular Torque Control of Multi-Three-Phase Induction Motor Drives

In recent years, the development of multi-three-phase drives for both energy production and transportation electrification has gained growing attention. An essential feature of the multi-three-phase drives is their modularity since they can be configured as three-phase units operating in parallel and with a modular control scheme. The so-called multi-stator modeling approach represents a suitable solution for the implementation of modular control strategies able to deal with several three-phase units. Nevertheless, the use of the multi-stator approach leads to relevant coupling terms in the resulting set of equations. To solve this issue, a new decoupling transformation for the decoupled torque control of multi-three-phase induction motor drives is proposed. The experimental validation has been carried out with a modular power converter feeding a 12-phase induction machine prototype (10 kW, 6000 r/min) using a quadruple three-phase stator winding configuration

Role of parasitic capacitances in power MOSFET turn-on switching speed limits: A SiC case study

This paper describes the effect of MOSFET internal capacitances on the channel current during the turn-on switching transition: an intrinsic theoretical switching speed limit is found and detailed mathematically. The set of analytical equations is solved and the effect of the displacement currents is highlighted with ideal simulated waveforms. A laboratory experiment is thus performed, in order to prove the theoretical predictions: a 25 mΩ SiC CREE power MOSFET is turned on in a no-load condition (zero drain current), starting from different drain-source voltage values. Finally, a LTSpice equivalent circuit model is also built, to better simulate the experimental behavior of the device, adding circuit strain components and other non-idealities to the overall model. A good match between measurements and simulations is observed, mostly validating either the theoretical assumptions and the presented model

Decoupled Torque Control of Multiple Three-Phase Induction Motor Drives

In recent years, the development of multiple three-phase drives for both energy production and transportation electrification has gained a growing attention. An important feature of the multiple three-phase drives is their modularity since they can be configured as three-phase units operating in parallel and using a modular control scheme. The multi-stator modelling approach represents a suitable solution for the implementation of modular control strategies able to deal with several three-phase units. Nevertheless, the use of the multi-stator approach leads to relevant coupling terms in the resulting set of equations. To solve this problem, a new decoupling transformation able to deal with a decoupled torque control of multiple three-phase induction motor drives is proposed. The experimental validation has been carried out with a modular power converter feeding a twelve-phase induction machine prototype (10 kW, 6000 rpm) using a quadruple three-phase stator winding configuration

Design and Testing of an Automotive Compliant 800V 550 kVA SiC Traction Inverter with Full-Ceramic DC-Link and EMI Filter

The traction inverter represents a crucial component of an electric vehicle (EV) powertrain. Efficiency, power density and overall integration are the primary targets of the inverter design process, which represents an active research and development topic for both industry and academia. The great majority of published EV inverter designs only focus on the DC/AC converter power stage (i.e., power modules and DC-link capacitor), disregarding fundamental elements for the correct operation of the system and/or for its compliance with automotive standards (e.g., control board, current measurement, EMI filter, case integration, etc.). Therefore, this paper focuses on the design and testing of a complete drive inverter system for a high-performance, 800 V 550 kVA, EV traction application. In particular, the inverter design includes state-of-the-art direct cooled SiC power modules, a full-ceramic DC-link capacitor and an EMI filter including an inductor concept providing both differential-mode and common-mode filtering actions

Oldie but Goodie: Is Technetium-99m Still a Treasure Trove of Innovation for Medicine? A Patents Analysis (2000-2022)

Technetium-99m is the workhorse of diagnostic nuclear medicine. The aim of the work is to analyze the technetium-99m patents since 2000 to photograph its innovation. QUESTEL’s ORBIT Intelligence system was used for the collection of technetium inventions disclosed in patents and patent applications in more than 96 countries in the period 2000-2022; 2768 patent documents were analyzed. Patent counting and analysis have shown that SPECT imaging using technetium-99m radiopharmaceuticals is still robust. The introduction of new technetium-99m radiopharmaceuticals into clinical routine goes beyond successful trials. In eastern economies, such as China and other emerging markets, patent applications are on the rise, while those in developed western countries are stagnating, with some exceptions for the United States. But despite the difficulties, academic and industrial research on these tracers remains essential for the development of nuclear medicine

Assessment of left ventricular volume and function by integration of simplified 3D echocardiography, tissue harmonic imaging and automated extraction of endocardial borders

Background: Quantitative three-dimensional echocardiography (3DEcho) of left ventricle (LV) is still limited because of the need for manually tracing endocardial borders: this can increase obseerver variability depending on the quality of fundamental (FUND) 2D images