Lukas Vavra

Mr. Lukas Vavra


Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 August 2024 in Energies
Verified
Journal Article
Open access
PDF file
NRNarayanamoorthi Rajamanickam
Narayanamoorthi Rajamanickam
Yuvaraja ShanmugamYuvaraja Shanmugam
Yuvaraja Shanmugam
RJRahulkumar Jayaraman
Rahulkumar Jayaraman
JPJan Petrov
Jan Petrov
LVLukas Vavra
Lukas Vavra
Radomir GonoRadomir Gono
Radomir Gono
The increasing demand for wireless power transfer (WPT) systems for electric vehicles (EVs) has necessitated advancements in charging solutions, with a particular focus on speed and efficiency. However, power transfer efficiency is the major concern in static and dynamic wireless charging (DWC) design. Design consideration and improvements in all functional units are necessary for an increase in overall efficiency of the system. Recently, different research works have been presented regarding DWC at the power converter, coil structure and compensators. This paper provides a comprehensive review of power converters incorporating high-order compensation topologies, demonstrating their benefits in enhancing the DWC of EVs. The review also delves into the coupling coil structure and magnetic material architecture, pivotal in enhancing power transfer efficiency and capability. Moreover, the high-order compensation topologies used to effectively mitigate low-frequency ripple, improve voltage regulation, and facilitate a more compact and portable design are discussed. Furthermore, optimal coupling and different techniques to achieve maximum power transfer efficiency are discussed to boost magnetic interactions, thereby reducing power loss. Finally, this paper highlights the essential role of these components in developing efficient and reliable DWC systems for EVs, emphasizing their contribution to achieving high-power transfer efficiency and stability.

16 August 2024 in Sustainability
Verified
Journal Article
Open access
PDF file
FJFRANKLIN J
FRANKLIN J
RPR.K. Pongiannan
R.K. Pongiannan
NRNarayanamoorthi Rajamanickam
Narayanamoorthi Rajamanickam
LVLukas Vavra
Lukas Vavra
JPJan Petrov
Jan Petrov
VKVladimir Kral
Vladimir Kral
The recent developments in electric vehicle (EV) necessities the requirement of a human intervention free charging system for safe and reliable operation. Wireless power transfer (WPT) technology shows promising options to automate the charging process with user convenience. However, the operation of the WPT system is designed to operate at a high-frequency (HF) range, which requires proper control and modulation technique to improve the performance of power electronic modules. This paper proposes a dead-time (DT) integrated Pulse Density Modulation (PDM) technique to provide better control with minimal voltage and current ripples at the switches. The proposed technique is investigated using a LCC-LCL compensated WPT system, which predominantly affects the high-frequency voltage and current ripples. The performance analysis is studied at different density conditions to explore the impact of the integrated PDM approach. Moreover, the PDM technique gives better control over the power transfer at different levels of load requirement. The simulation and experimental analysis was performed for a 3.7 kW WPT prototype test system under different modes of operation of the high-frequency power converters. Both the simulated and experimental results demonstrate that the proposed PDM technique effectively enhances the efficiency of the HF inverter while significantly reducing output current ripples, power dissipation and improving the overall WPT system efficiency to 92%, and leading to a reduction in the power loss in the range of 10% to 20%. This leads to improved overall system control and performance.

15 May 2024
Verified
Conference Paper
Closed access
TGTomas Gono
Tomas Gono
LVLukas Vavra
Lukas Vavra
PKPetr Krejci
Petr Krejci
Michał JasińskiMichał Jasiński
Michał Jasiński
BSBretislav Stacho
Bretislav Stacho
This paper focuses on the pivotal role of Harmonic Filters (HFs) in mitigating harmonic distortion within electrical systems to enhance power quality and efficiency. Harmonic distortion, characterized by deviations from the ideal sinusoidal waveform of electrical power, can cause equipment malfunctions, overheating, and a reduced lifespan of infrastructure. HFs, known for their cost-effectiveness and simplicity, employ inductors, capacitors, and resistors to selectively reduce specific harmonic frequencies, thereby improving system reliability and performance. The document explores traditional design methodologies of harmonic filter design, emphasizing criteria and considerations critical for effective harmonic mitigation. It highlights the use of advanced simulation tools, such as MATLAB/Simulink and PF DigSilent, which enable precise analysis and optimization of filter designs to meet specific system requirements. Moreover, it discusses the significance of designing filters with adequate margins to ensure system safety and reliability, considering the variability of loads and the presence of other harmonic sources. Driven by the necessity to enhance harmonic filter design in the face of increasingly complex electrical infrastructures, this paper advocates for leveraging recent advances in simulation tools.


29 January 2025 in Water
Verified
Journal Article
Open access
PDF file
LVLukas Vavra
Lukas Vavra
MGMiroslava Goňo
Miroslava Goňo
IKIwona Klosok-Bazan
Iwona Klosok-Bazan
HŠHana Švehláková
Hana Švehláková
This study evaluates the feasibility of using pretreated domestic wastewater (PDW) for food production in a hydroponic system. In the face of increasing water shortage problems and rising fertilizer costs, PDW combined with a limited amount of fertilizer is evaluated for its effects on plant growth, biomass yield, and product safety. The results showed that lettuce grown with PDW and mineral fertilizers reached a fresh weight of 116, while the use of organic fertilizers increased the yield to 127 g, compared to only 54 g with raw water. Nitrate concentration (NO3) was higher in lettuce grown with organic fertilizers (1044.33 ± 144.04 mg/kg) than with mineral fertilizers (623.33 ± 85.62 mg/kg), but the values remained well below the acceptable limit of 5000 mg/kg for safe consumption. Analysis of heavy metals confirmed that levels of arsenic, cadmium, mercury, and lead were significantly lower than the maximum permissible values set by FAO and EU regulations. In addition, no phthalates were detected in the lettuce biomass, confirming the safety of the materials used in the hydroponic system. The use of PDW in hydroponic crops significantly reduces dependence on potable water and synthetic fertilizers, contributing to sustainable resource management. This approach not only reduces production costs, but also reduces the water footprint of crops, which is crucial in the context of global water availability problems. The findings support the validity of using PDW in decentralized food production as a sustainable solution for regions facing water and fertilizer shortages. Further research will focus on optimizing nutrient management and environmental conditions to increase system efficiency and food safety.

8 June 2022
Verified
Conference Paper
Closed access
LVLukas Vavra
Lukas Vavra
BSBretislav Stacho
Bretislav Stacho
JVJan Veleba
Jan Veleba
This paper describes the DC arc flash analysis, existing calculation models and arc flash methodology for networks with constant DC voltage sources. For the examined 110V DC UPS system, the main goal was to evaluate DC arc flash conditions and to determine respective PPE categories. The overview of several commercial softwares which currently cover the DC arc flash analysis is also provided.