Conference papers (KEV)
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Item Synchronous Generator Active and Reactive Power Oscilations Reduction by BESS(IEEE, 2022) Dragoun, Jaroslav; Vinš, Martin; Sirový, Martin
Item Design of universal H-bridge converter for cascaded multilevel topologies(University of West Bohemia, 2021) Kehl, Zdeněk; Glasberger, Tomáš; Streit, LubošItem Integration of battery energy storage in thermal power plant(IEEE, 2020) Vinš, Martin; Dragoun, Jaroslav; Sirový, Martin
Item Optimization of reluctance motor with printed rotor(IEEE, 2019) Kaska, Jan; Orosz, Tamás; Karban, Pavel; Doležel, Ivo; Pechánek, Roman; Pánek, DavidItem Comparison of two types of cooling of axial flux permanent magnet machines by CFD simulation(IEEE, 2019) Veg, Lukáš; Laksar, JanThis paper is focused on the comparison of two types of possible cooling of the stator of the axial synchronous machine with permanent magnets. The main contribution is the specification of basic issues of the cooling of axial machines. This comparable study is presented the evaluation of suitability as a comparison of two axial flux machine configurations for specific duty cycle. The CFD analysis of the flowing coolant is used to determine the wall heat transfer coefficient.Item Impact of electrical machine structural parts on its modal and vibration behavior(IEEE, 2019) Šobra, Jan; Byrtus, MiroslavIn the paper, authors deal with the case study of an impact of stator frame and vertical mounting on modal and vibration behavior of a squirrel-cage induction machine. The study is performed using finite element analysis where resulting magnetic forces from magnetic transient analysis are set as an excitation in the analysis of harmonic response. Modal analysis is carried out to identify the modes and natural frequencies of the modeled structures and their possible effect on vibration spectra. Resulting vibration spectra are compared to the analysis of a solely stator lamination and to the experimental results on the full machine assembly.Item Adaptive control of LCL filter with time-varying parameters using reinforcement learning(IEEE, 2019) Dragoun, Jaroslav; Šmídl, VáclavTwo main aspects of a LQ control of a single-phase converter with a LCL filter are studied in this paper. First, the choice of a penalization structure that prevents instability of the closed loop caused by input saturation due to limited voltage of the DC link. We show that all tested variants of the penalization can achieve stable performance of the system. Second, adaptation of the controller gains to a change of parameter of the LCL filter. We compare adaptation rules based on the classical Riccati equation and on the reinforcement learning method of the temporal difference gradient descent. The latter method has lower computational cost and the potential to be more extensible to non-linear systems. We show that the standard approach with a constant learning rate is inefficient and better results can be achievd using adaptive learning rate. Performance of the method with adaptive learning rate is tested in simulation of current tracking after step change of the output inductance.Item Identification of thermal model of power module using expectation-maximization algorithm(IEEE, 2019) Ševčík, Jakub; Šmídl, Václav; Votava, MartinPrediction of junction temperatures in power semiconductor modules is essential to improve reliability of the device and prevent module failures due to thermal stress. Lumped parameter network is a popular approach for temperature modeling. Calibration of the thermal model is based on thermal measurements of the junction temperatures that are difficult to obtain. We aim to combine the knowledge of internal model structure and as little measurements as possible. Specifically, we use a state space thermal model with structure determined by the module layout, and propose to use the Expectation-Maximization algorithm from that can utilize data from different incomplete experiments. The identification procedure is introduced in detail in this paper and the applicability of the proposed approach is demonstrated on simulated and experimental data.Item Using CFD analysis to improve the pasive cooling of the high speed electrical machines body(IEEE, 2019) Veg, Lukáš; Laksar, JanThis paper is focused on the modification and improvement of the passive cooling system of the high speed electrical machines body. In the paper are described, compared, and evaluated variants of cooling rib shapes. For each shape is created the fluid CFD model and used the model boundary condition for steady state and transient thermal model. The contribution of the paper is possibilities for relatively cheap modification of the shape of the machine housing to get better values of the continuously working temperature.Item Influence of machine geometry to the PMSM mathematical model(IEEE, 2019) Laksar, Jan; Hruška, Karel; Veg, LukášThe paper is focused on the evaluation of the time dependency of the equivalent circuit (EC) parameters. In the machine control theory, these parameters are supposed to be constant. But especially in the permanent magnet synchronous machines (PMSM) with fractional slot concentrated windings, time dependency of EC parameters can be very significant. Therefore the mathematical model of the generator operation is created including the time dependency of EC parameters.Item Rack mounted low-profile indirect frequency converter(University of West Bohemia, 2019) Glasberger, Tomáš; Košan, Tomáš; Molnár, JanA new indirect frequency converter is introduced in this paper. The main goal of the new proposal is to simplify installation and running as supply unit for industrial applications. It fulfills minimum dimensions requirement and also enables parallel connection and full energy recuperation mode. The proper function of the designed converter has been performed on a prototype of linear actuator for a 6DOF motion platform.Item Converter power losses computation by FPGA-based HIL simulator(University of West Bohemia, 2019) Dragoun, Jaroslav; Talla, Jakub; Košan, TomášConverter losses play a crucial role in the process of power converter design. Especially semiconductor components and heat sink selection are strongly dependent on the total power converter losses and thus affect the power converter size and its price. The most popular techniques for determination of the losses are based on the computer simulation of the power converter. These kinds of simulations could be very time consuming, because on one side, the simulation needs very short steptime for differential equations calculation to model power converter switching. On the other side, the temperature dynamics of heat sink are commonly slow and depend on power cycles of converter. With the help of FPGAbased hardware in the loop (HIL), the simulation could run real-time and it is possible to test different scenarios, different modulation techniques and see their influences on converter losses. This approach can lead to reduction of losses to the state, when it is possible to reduce the size of converter. Furthermore, the HIL simulation could be used for testing and developing control algorithm in real time conditions. It also offers flexibility in the easy change of model parameters and monitoring values which are not or hardly obtainable in real machine. This paper presents the FPGA-based HIL simulator of induction motor drive with three phase voltage source inverter based on Semikron IGBT modules.Item A novel ZCS/ZVS bidirectional DC-DC converter for energy storage applications(University of West Bohemia, 2019) Bhajana, V.V.Subrahman. Kumar; Drábek, PavelIn this paper, a new soft-switched non-isolated bidirectional converter is proposed. This proposed converter is operated with soft-switching (zero current switching / zero voltage switching). It is implemented during the turn-on of main switching devices, with the addition of auxiliary resonant circuit that consists of an auxiliary switch, diode, capacitor and an inductor. The switching losses are significantly reduced due to soft-switching operation of the main switches. Therefore, the efficiency of this topology is improved. The additional benefit of this topology is that the auxiliary switches are also operated with soft-switching. The proposed topology observes ZCS turn-on for boost mode and ZVS turn-on for buck mode operations. The principles of operation, design analysis and simulation verifications are discussed in detail. The soft-switching capabilities are obtained from design simulations on the 150V/250V/500W converter system.Item A vehicle device tailored for hybrid trolleybuses and overhead wires implementation in SUMO(EasyChair, 2019) Ševčík, Jakub; Přikryl, JanThe electrification of transport is one of the key parts of the present aim to reduce undesirable vehicular emissions in the atmosphere. While the full electrification of personal vehicles is mostly associated with employing a big battery pack on the board and charging on (static) charging stations, another interesting possibility appears in the case of public transport – dynamic drawing of the power from overhead wires. Regarding vehicles moving on the road, this concept is used by trolleybuses or hybrid trolleybuses, i.e. vehicles combining power from the overhead wires and batteries. A replacement of classic buses (with a combustion engine) with (hybrid) trolleybuses is hardly possible without an appropriate adjustment of public transport lines and the necessary infrastructure. For this purpose, a simulation of the adjusted public transport service may be used to identify weaknesses of the proposed solution. This paper presents a new vehicle device and a new additional part of road infrastructure in SUMO. It introduces device.elecHybrid based on existing device.battery, extending its functionality and tailoring it for the needs of hybrid trolleybuses. In addition, overhead wires and traction substations are implemented. As the voltage and electric cur- rents in the overhead wires depend on traffic, the overhead wire parameters are optionally evaluated by a built-in electric circuit solver using Kirchhoff’s laws. The proposed changes allow us to simulate hybrid trolleybus in-motion charging under the overhead wire. The extensions can be immediately used in micro-simulations or even (in a simplified version) in the meso-simulation mode.Item A comprehensive approach to calculation of permanent magnet losses(IEEE, 2019) Hruška, Karel; Laksar, JanThe permanent magnet losses are a problem related to all types of permanent magnet machines – permanent magnet synchronous machines, brushless direct current machines as well as flux-switching permanent magnet machines. These losses arise from time-variable magnetic field acting together with elf permanent magnet field. The results are eddy eddy currents flowing through the volume of permanent magnets causing resistive losses and heating the permanent magnets. This paper describes a possibility of analytical calculation of permanent magnet losses arising both from geometry of the machine and from the power supply for the purpose of accurate determination of heat generated in the rotor volume.Item Sodium-sulfur batteries for energy storage applications(IEEE, 2019) Vinš, Martin; Sirový, MartinThis paper is focused on sodium-sulfur (NaS) batteries for energy storage applications, their position within state competitive energy storage technologies and on the modeling. At first, a brief review of state of the art technologies for energy storage applications is presented. Next, the focus is paid on sodium-sulfur batteries, including their technical layouts and evaluation. It is introduced the equivalent circuit model of the battery cell. At the end, there are presented the results from simulation model which was developed in Simulink to verify the proper function.Item Current sensor with low inductance(IEEE, 2019) Skala, Bohumil; Kindl, Vladimír; Drtina, Rene; Lokvenc, JaroslavThis paper deals with design of current sensor introducing low inductance. The sensor is designed for a current up to 500 A and 120 kHz. Since the market offers several types of sensors suitable for the targeted application, they usually have problems with measured signal postprocessing. This paper describes the principle of operation and includes simulation results and measurement made on the laboratory prototype of the proposed sensor.Item Parallel winding of a synchronous generator(IEEE, 2019) Skala, Bohumil; Hruška, KarelThe paper deals with the design of seven times parallel synchronous generator winding. The parallel winding is not commonly used for synchronous generators because it could be a possible source of difficulties, especially compensatory currents. The paper mentions the design, simulations, manufacturing and results of a measurement performed in a power plant.Item Minimum infinity norm-based PWM for three-phase four-leg converters(IEEE, 2019) Komrska, Tomáš; Glasberger, Tomáš; Peroutka, ZdeněkItem Finite control set model predictive control of static compensator(IEEE, 2019) Kehl, Zdeněk; Glasberger, Tomáš; Peroutka, Zdeněk
