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Design of a current data logger for LPWA sensors
Mikulášek, Michal ; Možný, Radek (referee) ; Štůsek, Martin (advisor)
This Master thesis deals with the design and construction of a measuring device for measuring and the current consumption logging of sensors using LPWAN (Low Power Wide Area Network) technology. The theoretical part of the thesis firstly summarizes selected LPWAN technologies. Selected technologies, namely: LoRaWAN, Sigfox and Narrowband IoT (NB-IoT), are described more in detail. Further, the current measurement techniques are briefly discussed. The main focus is given to the current shunt measuring methods. The second half of thesis describes procedures conducted during the design and construction of a measuring device. The current measuring is based on the current shunt circuit complemented by the voltage amplification circuit, whose output is subsquently converted into digital form using an AD converter. The thesis describes in great detail the procedures for selecting individual components and important processes used in design of printed circuit boards. An integral part of the measuring device implementation is the design and implementation of control software, which is described in detail and supplemented by workflow charts underlining the entire description. The implementation of the entire measuring device is completed by the design and implementation of the cover box using 3D printing technology. Finally, the specifications of designed device are briefly discussed based on the limits of the used components.
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High resolution ammeter
Honek, Marek ; Roubal, Zdeněk (referee) ; Steinbauer, Miloslav (advisor)
A transmission electron microscope is a device operating on a similar principle as an optical microscope. The fact that electrons wavelength is much shorter than the wavelength of photons is used to obtain huge magnifications. Glass lenses commonly used in the optical microscope are therefore replaced by magnetic coils in the electron microscopes. A magnetic field is directly proportional to the current passing through these coils. It is important to the current supplied to the coils to be as stable as possible to achieve high resolution. The goal of this thesis is to analyze usable current measurement methods and to design a current stable measuring device with a resolution of 1 ppm.
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Power Inverter Online Diagnostics
Knobloch, Jan ; Chlebiš,, Petr (referee) ; Drábek,, Pavel (referee) ; Klíma, Bohumil (advisor)
This doctoral thesis focuses on the problems of IGBT failure prediction in pulse converters using measurable changes of selected parameters (so--called trending variables) being influenced of transistor degradation during aging. Firstly the state--of--the--art in this field is presented in the dizertation. The description of designed and constructed automated measurement stand follows, enabling monitoring and recording of switching processes during accelerated aging. Further the problems of high--bandwidth measurement of electrical quantities during IGBT switching are described. Especially the problems of current sensing are analyzed and the most suitable sensor is selected. The data recorded using the developed apparatus served to identify potential trending variables allowing the failure prediction. Here the dependence of trending variables on aging and on parasitic influences (current, temperature, voltage) had to be distinguished. Finally the evaluation of trending variables is performed. Their insignificant sensitivity on accelerated aging is shown which complicates their practical implementation for the purpose of failure prediction.
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Draft sources 1000A AC current sensors for calibration
Klimeš, Jan ; Vetiška, Vojtěch (referee) ; Dohnal, Petr (advisor)
This bachelor thesis deals with design and construction of device for precise measurement of 1000 A alternate current. This thesis theoretically discusses the possibilities of conventional solutions, such as current transformers, as well as modern methods in the form of current sensors. The output of this thesis is a solution of problems with accuracy and discussion of other possible ways to reduce systematic error. The thesis discusses structure of the current transformer, the digitalizing of the signal and its usage as an input for engineering units. The device is then tested for final accuracy.
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Contactless Wiegand Effect DC and AC current sensor
Štefánek, Martin ; Szabó, Zoltán (referee) ; Kubásek, Radek (advisor)
The paper describes the types of magnetic sensors, which are used for measuring magnetic fields. The document is divided into chapters, which describe Wiegandův sensor and its implementation into the magnetic sensor in this document is designed magnetic circuit design for this sensor. The work evaluates the progress in the design of contactless ammeter that measures AC and DC current via Wiegand effect. Experimental verification principle and its function for DC current is described in the penultimate chapter.
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Measuring and recordes electrical electrical quantities
Vít, Tomáš ; Čejka, Miloslav (referee) ; Havlíková, Marie (advisor)
The aim of this Bachelor's thesis is the design and realisation of a device able to measure and record electrical quantities - voltage, current and resistance. The part of design is a theoretical description of measurement methods with the selection of suitable components. Based on these components is designed hardware design of the device, followed by its practical assembly. The final device is able to be measured electric variables at centain intervals, which are then stored on the SD card. The final element is the CSV file containing the measured data and time of each measurement.
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Dual channel bench power supply
Stehlík, Ota ; Brančík, Lubomír (referee) ; Kubíček, Michal (advisor)
The aim of this thesis is to design and construct a two-channel bench power supply with variable output voltage in range from 0 V to 25 V with a maximum output current of 2 A. At the beginning of the thesis a general principles of power supplies are summarized. In the following section a detailed design description and simulation results of the main power supply are given. Afterwards, the design and description of auxiliary power supply with electronically controlled fan is presented. Finally, measured characteristics of the bench power supply are given.
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Current sensing with Hall-effect sensors
Štindl, Daniel ; Kovář, Jan (referee) ; Šotner, Roman (advisor)
This master's thesis deals with integrated Hall-effect current sensors. The thesis contains summary of manufacturers of current sensors suitable for low current measurement and comparison of their important parameters. Next objective of the thesis is a design of test board used for evaluation of temperature depedent accuracy of several sensors simultaneously. The device can be connected with PC through USB interface for saving measured values or automated control with other instruments.
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Coaxial multiplexer for automatic measurement of AC current
Boštík, Ondřej ; Klusáček, Stanislav (referee) ; Havlíková, Marie (advisor)
Master’s thesis in the theoretical part deals with literature review on the topic of measurement errors and measurement uncertainties. The practical part deals with the simulation of additional capacitive and resistive load on the amplitude and phase error during shunts based measurement. For this simulation is used mathematical apparatus of cascade matrix of two-ports and their connections. For the actual simulation is used script for MATLAB. Furthermore, the work deals with the design of voltage follower to eliminate simulated errors and its practical realization. The last part deals with the design of the coaxial multiplexer for switching current shunts developed in the Czech Metrological Institute in Brno.
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Operating amplifier tester
Zápeca, Jan ; Khateb, Fabian (referee) ; Vávra, Jiří (advisor)
The bachelor's thesis tries to describe the evolution of the device designated for testing of the operational amplifier 1458. The evolution is associated with theoretical preparation useful for future application of obtained knowledge. This knowledge is presented by measuring methods which are suitably chosen and by choice of parts. Consequently, particular coplexes join together and the conception of future operational amplifier 1458 tester is created. The conception of tester in logically connected blocs form leads to creation of electrical scheme and also to smooth transition from theoretical part to practical application of knowledge. The tester is designed as a digital device. The microcontroller becomes the principal control component. The microcontroller defines accurately the final function of device. Tha last part of bachelor's thesis describes the tester manufacturing. The conclusion respresents the summary of knowledge and results of bachelor´s thesis. Functional device, which is the result of bachelor´s thesis, detects the operational amplifier defect in 2 levels - the gain fault and the defect of overcurrents. The tester identifies explicitly whether tested operational amplifier 1458 is defective.
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