1. Derivation of analytical expressions for fast calculation of resistance spot welding system currentsRobert Brezovnik, Jožef Ritonja, 2024, original scientific article Abstract: The paper deals with the dynamics of a resistance spot welding system. At the core of this system is a transformer, which is powered on the primary side by a pulse-width modulated inverter and has a full-wave output rectifier on the secondary side that provides a direct welding current. The entire system is nonlinear, due to magnetic hysteresis and electronics. The electronics prevent the current from flowing in all parts of the welding transformer at separate time intervals during the voltage supply period; therefore, not all the parameters affect the dynamic of currents and voltages all the time so the system is also time-variant. To design a high-performance welding system and to predict the maximum possible welding current at a specific load, it is necessary to know the welding and primary currents. The leakage inductances of the system can reduce the maximum welding current significantly at higher frequencies and the same load. There are several methods to determine these currents, each with its drawbacks. Measurements are time-consuming, using professional software is expensive and requires time to learn and free open-source software has many limitations and does not guarantee the correctness of the results. The article presents a new, fourth option—a theoretical derivation of analytical expressions that facilitate straightforward and rapid calculation of the welding and primary currents of the resistance spot welding system with symmetrical secondary branches. The derivation of the mathematical expressions is based on the equivalent circuits that describe the system in different operating states. The results of the numerical simulations confirmed the derived expressions completely.
Keywords: DC–DC converters, pulse width modulation (PWM), welding transformers, center-tapped transformers, full-wave rectifier, resistance spot welding (RSW), leakage inductance, analytical modeling, time-variant system, equivalent circuit
Published in DKUM: 08.08.2024; Views: 77; Downloads: 28
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2. Human threat circuits : threats of pain, aggressive conspecific, and predator elicit distinct BOLD activations in the amygdala and hypothalamusTeresa Bertram, Daniel Hoffmann Ayala, Eva Maria Huber, Felix Brandl, Georg Starke, Christian Sorg, Satja Mulej Bratec, 2023, original scientific article Abstract: Threat processing, enabled by threat circuits, is supported by a remarkably conserved neural architecture across mammals. Threatening stimuli relevant for most species include the threat of being attacked by a predator or an aggressive conspecific and the threat of pain. Extensive studies in rodents have associated the threats of pain, predator attack and aggressive conspecific attack with distinct neural circuits in subregions of the amygdala, the hypothalamus and the periaqueductal gray. Bearing in mind the considerable conservation of both the anatomy of these regions and defensive behaviors across mammalian species, we hypothesized that distinct brain activity corresponding to the threats of pain, predator attack and aggressive conspecific attack would also exist in human subcortical brain regions.
Keywords: human, threat responses, translational neuroscience, threat conditioning, threat types, MRI, threat circuit
Published in DKUM: 12.04.2024; Views: 380; Downloads: 286
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3. Method for Determining Battery HealthSlavko Brečko, Dalibor Igrec, Aleš Breznik, Amor Chowdhury, Miran Rodič, 2019, published scientific conference contribution Abstract: This paper presents a method for automatic state of health estimation for lithium ion batteries. A pulse method for determining battery characteristics using a specially developed electronic measuring device is presented. Measurement results show characteristics of several measured batteries exhibiting different states of health with estimation possible even with a protection circuit present on the battery.
Keywords: Li-ion, state of health, battery testing, measurement circuit, estimation method
Published in DKUM: 04.12.2023; Views: 341; Downloads: 29
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4. Measurement device for testing printed circuit board assemblies coming off the production lineNejc Friškovec, Manja Obreza, Sebastijan Seme, Klemen Sredenšek, 2022, original scientific article Abstract: The paper presents an efficient way to evaluate and determine the quality of an assembled printed circuit board coming off the production line. A printed circuit board assembly consists of electronic devices soldered to the printed circuit board, which provides the electrical connections. After assembling the printed circuit board, a function test needs to be performed to guarantee the quality of the product. Usually, the assembly lines are equipped with cameras that detect inaccuracies such as missing components. This level of quality assurance is sometimes not enough, and we need to add another degree of precaution. In addition to camera inspections, electronic measurements must be conducted. The process needs to be automated to provide repeatability and speed. The paper evaluates such a device and presents its advantages, disadvantages, and complexity. The device includes an electrical part that performs the measurements, a mechanical part that consists of a housing and a mounting nest, and a program that supervises the process.
Keywords: electrical measurement, printed circuit board, testing device, automation, intelligent measuring system
Published in DKUM: 30.10.2023; Views: 385; Downloads: 10
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5. Analysis of the influence of parameters when charging and discharging a capacitor using differential equationsMatic Krašovic, Peter Virtič, 2022, original scientific article Abstract: Two different electrical circuits were analysed in this paper. The first was an RC circuit consisting of a resistor R, a capacitor C, and a DC voltage u, while the second was an RLC circuit consisting of a resistor R, a capacitor C, a DC voltage u and an inductor L. Both circuits were described using the state space mathematical model and, on this basis, graphs for charging and discharging a capacitor were plotted. Both circuits were described using differential equations for electrical current through a capacitor and voltage over a capacitor. Finally, different values of the R (resistance), L (inductance) and C (capacitance) parameters were taken, and graphs were plotted for voltage over capacitor. The purpose of the study was to explore how different values of parameters influence capacitor charging and discharging.
Keywords: RC circuit, RLC circuit, state space, transfer function, differential equations, parameters R, L, C, damping
Published in DKUM: 30.10.2023; Views: 278; Downloads: 13
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6. High resolution switching mode inductance-to-frequency converter with temperature compensationVojko Matko, Miro Milanovič, 2014, original scientific article Abstract: This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystalʼs natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85-100 nH to 2-560 kHz.
Keywords: inductance-to-frequency, switching methods, dynamic temperature compensation of circuit elements, precision metrology
Published in DKUM: 22.06.2017; Views: 1075; Downloads: 348
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7. Universal decomposition rule for OBDD, OFDD, and 0-sup-BDDRobert Meolic, Zmago Brezočnik, 2016 Abstract: Binary decision diagram (BDD) is a very successful data structure for
representation and manipulation of Boolean functions. Various BDD types
have been proposed. In this paper relations between OBDD, OFDD, and
0-sup-BDD are shown in a new way. An universal decomposition rule for them
is introduced. Using this rule a set of 288 BDD types is defined
together with their minimization rules.
NOTE: This is a revisited and translated version of the paper: "Splošno razčlenitveno pravilo za OBDD, OFDD in 0-sup-BDD". In Proceedings of the Fifth Electrotechnical and Computer Science Conference ERK'96, Portorož, Slovenia, volume B, pages 11-14, September 1996.
Keywords: Binary Decision Diagram, Shannon's expansion, Reed–Muller expansion, Davio expansion, Digital Circuit Design
Published in DKUM: 12.10.2016; Views: 2500; Downloads: 87
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8. Merjenje faznih napetosti pri pulznoširinsko moduliranih pogonih : diplomsko delo univerzitetnega študijskega programaValentin Kranjec, 2004, undergraduate thesis Keywords: asinhronski motorji, pretvorniški mostič, merilno vezje, merjenje faznih napetosti, fazne napetosti, dvojni preklopni integrator, induction machine, inverter bridge, speed sensrless control, measuring circuit, dual switched integrator
Published in DKUM: 26.07.2007; Views: 2455; Downloads: 0 |
