Leader: Assoc. Prof. Petr Toman

Group website: http://www.cvvoze.cz/en/cvvozepowerlab

The CVVOZE PowerLab group operates two laboratories: One dedicated to high-current and short-circuit testing, allowing the generation of alternating currents up to 150 kA at 250 V and direct currents up to 50 kA at 1,000 V, and the other being a shielded room for high-voltage assessment centered on dielectrics and electrical equipment insulation. The open access research infrastructure is available to non-commercial specialists worldwide (see www.cvvoze.cz/en/cvvozepowerlab/open-access/).

Major 4-year outputs:

• Contract research into the design-specific testing of diverse types of machinery and equipment, including, for example, switching apparatuses, switchboards, transformers, insulators, power cables, and rotating machines.
• Investigation into the behavior of electric arcs in switching processes.
• Analysis of the disturbance that accompanies the switching of large currents.
• Precise diagnostics of solid and liquid dielectrics.
• Investigation into interference; measurement methodology; and EMC testing.
• Development activities in power cable insulation diagnostics.

Leader: Jiří Valenta, Ph.D.

The group studies the behavior of electric arcs to implement the findings within the in-house research and development of switching and protective devices for low- and high-voltage applications. A short-circuit lab equipped with a synchronous surge generator and related accessories enables the researchers to simulate short circuit events in power grids; in view of this purpose, the generator is employed especially for testing new instruments or devices designed and fabricated jointly by the group’s specialists and industry-based partners. The results of the experiments are compared with those obtained through theoretical simulations carried out by using advanced diagnostic systems.

Major 4-year outputs:

• A model of operation-induced temperature rise in electrical instruments.
• Optimization of the parameters of radiation transfer in plasma.
• A system for magnetizing and demagnetizing a short-circuit transformer.
• An endurance tester for switching devices.
• Supporting documents and data for industrial plants developing new types of low-voltage circuit breakers.

Leader: Petr Procházka, Ph.D.

Our experts engineer and fabricate prototypes of electronic and electromechanical systems where the electric power flow is feedback-controlled or converted to mechanical power. Typically, we perform such assignments as developing electric traction structures or simulating dynamic systems and designing relevant means of control; the algorithms are then most often implemented via microprocessors. The scope of the group‘s activities, however, includes also investigating problems and aspects relevant to operational diagnostics on individual components of a system. Generally, our aim is to increase the efficiency of all the applied subsystems on a continuous basis.

Major 4-year outputs:

• An electric locomotive drive (4 x 1 MW) with energy recovery into the AC grid.
• Electrically powered aircraft VUT 051 RAY.
• An electromechanical strut for jet aircraft handling gear.
• A two-ton, battery-powered mini excavator.
• A hybrid forwarder with trailer.
• A hybrid harvester.

Leader: Assoc. Prof. Pavel Vorel

We pursue a multi-faceted research program, with the main interests being as follows: Designing and developing switched-mode power supplies and special-purpose converters for various industrial and experimental applications; fabricating power supply units that have power output up to hundreds of kWs and exhibit non-traditional output parameters (a high current or voltage); and engineering high-frequency and pulsed-output supplies. Moreover, our researchers design and develop electronic circuits and printed circuit boards, including the mounting and activation, and they compute electromagnetic circuits of choke coils and transformers.

Major 4-year outputs:

• An mains-powered 480 V, 100 A quick charger for the Super-El electromobile
• A high voltage power supply for galvanizing purposes (15 V 2,500 A).
• A high-voltage pulsed power supply to facilitate medical experiments.
• A 2.5 kW wireless power transfer apparatus.
• A system for the induction heating of components in metallurgy.
• An instrument to measure lithium accumulator capacity at 400 A.

Leader: Assoc. Prof. Ondřej Vítek

The group focuses on studying and developing electrical machines with non-standard parameters (such as a very high speed or high efficiency) as well as standard ones. The magnetic circuits of the machines are optimized by using computational systems that exploit finite element methods and artificial intelligence. The engineering process includes also thermal analyses, and the properties of the machines and drives are examined in a dedicated dynamometer laboratory.

Major 4-year outputs:

• A rotating high-speed motor for woodworking machinery.
• A rotating high-speed motor with 120,000 rpm to operate in a helium turbo-circulator.
• Optimization of small-sized asynchronous machines.
• Synchronous high-efficiency reluctance and assisted reluctance machines.
• A synchronous 10 MW generator.
• Resolver, a shaft position sensing device.
• A hybrid pump drive.

Leader: Karel Katovský, Ph.D.

The group comprises two teams: One investigates the safety of current advanced nuclear installations (including the evaluation and computation of the active zone; thermo-hydraulic, thermo-mechanical, and fuel parameters; and fuel rods near the boiling crisis of the first kind), and the other performs research into advanced, 4th generation reactors cooled by molten salt, lead, or Pb/Bi eutectic alloy. By extension, our experts also concentrate on the following subdomains and problems: the neutron spectrum; fission product yield determination; effective cross-sectional area measurement; validation and verification of computational models; and optimization of systems with an accelerator-driven source of neutrons.

Major 4-year outputs:

• Contract research (computational and experimental) within safety evalution analysis focused on partial components of VVER nuclear installations.
• Research of activation detectors for use in high energy neutron systems (TACR).
• Study of fast neutron-induced reaction cross-sections relevant to nuclear data needs for advanced reactor design (with MSU Baroda).
• Monitoring of fast energy neutron field using threshols activation detectors and temperature monitors (with JINR Dubna).

Leader: Assoc. Prof. Petr Mastný

We examine operational characteristics of renewable sources of energy, concentrating on their proper and effective system integration; such a task involves also the relevant evaluation, definition, and verification of required parameters. The group operates apparatuses for the testing of power inverters utilized in hybrid energy and photovoltaic systems equipped with or lacking accumulation; the researchers can also use devices enabling comprehensive analysis of photovoltaic systems (a PV analyzer, power analyzers, and a recorder of electrical power quality and transient processes).

Major 4-year outputs:

• Contract research on polyvalent sources of energy, including the design, computation, and diagnostics (jointly with corporate partners such as ČEZ, E.ON, Enkom, TZ pro, fgFORTE, SUNLUX, and Imos development).
• Utilizing accumulation in charging stations for electromobiles (with ČEZ, a.s.)
• A carbonless hybrid energy system with accumulation, operating as an active element of the electricity grid.
• Developing the EMS (Energy Management System), configuring the BMS (Battery Management System), and setting the control and communication systems for inverters.
• Testing P/U a Q/U regulation in PV inverters.

Leader: assoc. prof. Petr Drexler, Ph.D.

The Electrical Systems Safety Group deals with research on the issues of their diagnostics, protection against emergency conditions and also the prevention of accidents and fires. In the field of predictive diagnostics of power transformers, the group focuses on research into methods of detecting and locating partial discharges using monitoring their electromagnetic emission in the ultra-high-frequency (UHF) band. That covers mainly the design and construction of antenna sensors for pulsed signals, high-frequency electronics and the design of signal processing methods and the development of specialised software. The group also focuses on personal safety issues in electrical engineering and deals with teaching of university students in this filed. Moreover, it offers training on professional competence to perform activities in electrical engineering for individuals and companies. In the field of related research, the group deals with advanced numerical modelling methods in safety issues of electrical installations.

The most significant outputs achieved by the group in the last 4 years:

• Installation of a modernized system for detection and localization of partial discharges in block-transformers at the Dukovany power plant.
• Development of a demonstration panel to demonstrate the functions of electric shock protection and Arc Fault Detection Device (AFDD).
• Research, development and verification of a new type of sensor for detection of partial discharges outside transformers.

Leader: Ing. Tomáš Kříž, Ph.D.

We deal with modelling of electromagnetic fields in the low and high frequency region, we solve temperature problems including flow and coupled (electromagnetic + temperature) problems. In the low-frequency domain, we focus on solving problems in quasi-stationary or harmonic steady state (electromagnets, actuators, sensors or clamping systems) and also on solving transient processes in components or devices. In the high-frequency area, we focus on the design of planar structures, excitation coils used in spectroscopy or the design of saddle coils used in nuclear magnetic resonance. In thermal calculations, we deal with the heating of devices due to Joule or electromagnetic losses and their cooling, heat transfer from solid structures to liquids or gases (heat exchangers, water heaters).

The most important solved projects:

• EMC analysis and assessment of a multi-cell low-floor tramway 35T – Chemnitz, from 26. 3. 2018 to 14. 12. 2018
• GA17-00607S, Complex Artificial Electromagnetic Structures and Nanostructures, from 1. 1. 2017, to 31. 12. 2019

The most important publications:

• ZUKAL, J.; SZABÓ, Z.; KŘÍŽ, T.; KADLEC, R.; DĚDKOVÁ, J.; FIALA, P. A Robust Generator-Harvester for Independent Sensor Systems. Applied Sciences - Basel, 2024, vol. 14, no. 3, p. 1-16. ISSN: 2076-3417.
• DREXLER, P.; NEŠPOR, D.; KADLEC, R.; KŘÍŽ, T.; NEBOJSA, A. Simulation and Characterization of Nanostructured Electromagnetic Scatterers for Information Encoding. Electronics (MDPI), 2022, vol. 11, no. 20, p. 1-12. ISSN: 2079-9292.
• HANZELKA, M.; DAN, J.; FIALA, P.; DOHNAL, P. Human Psychophysiology Is Influenced by Low-Level Magnetic Fields: Solar Activity as the Cause. Atmosphere, 2021, vol. 12, no. 12, p. 1-10. ISSN: 2073-4433.
• DREXLER, P.; FIALA, P.; KADLEC, R.; LONDÁK, P.; MÁDROVÁ, T.; KLÍMA, M.; ZUKAL, J. Numerical modeling and experimental verification of a low fluid flow inductive flowmeter. FLOW MEASUREMENT AND INSTRUMENTATION, 2021, vol. 78, no. 1, p. 1-12. ISSN: 0955-5986.
• ZUKAL, J.; FIALA, P.; SZABÓ, Z.; DĚDKOVÁ, J.; PERNICA, R. Coupled Numerical Model of Vibration-Based Harvester. Applied Sciences - Basel, 2020, vol. 10, no. 8, p. 1-25. ISSN: 2076-3417.
• SZABÓ, Z.; FIALA, P.; ZUKAL, J.; DĚDKOVÁ, J.; DOHNAL, P. Optimal Structural Design of a Magnetic Circuit for Vibration Harvesters Applicable in MEMS. Symmetry, 2020, vol. 12, no. 1, p. 1-18. ISSN: 2073-8994.