Ales Havel

Modern instruments for increasing the efficiency of the energy transfer in electric vehicles

This paper describes the high efficiency drive unit for an EV, which is designed with accessible solutions for the efficiency increasing. Synchronous utilization of ultracapacitors and three-level inverter brings considerable power savings and enhancement longevity for a lithium battery pack. The total loss and EMI comparison between the two-level and three-level inverter and power measurements on the EV drive unit are presented at the conclusion part of this paper.

Real-Time Estimation of Induction Motor Parameters Based on the Genetic Algorithm

This article shows one of many ways how to identify the parameters of the IM in real time. There is used the theory of genetic algorithms for IM parameters identification. The introduction describes why the problem is discussed. Next chapters show induction motor’s dynamic model and the principle and way how to implement the IM’s parameters identification. Theory of used genetic algorithm and experimental results are demonstrated in the end of this article. The conclusion describes the potential use of this method and discusses further development in the field of real time estimation of induction motor’s parameters.

The control system of electrical energy accumulation

Control of electrical power systems with attached units of accumulation represents a relatively complex problem, both in terms of technical equipment and in terms of the measurement and the control algorithms. In order to control system dynamically from the viewpoint of energy flows, so particularly with regard to increasing quality of electrical energy, all processes must be processed with relatively high frequency of sampling. The paper describes the elements of electrical energy accumulation control system, which was implemented in the Technology Centre of VřB - Technical University of Ostrava. This system uses originally developed analog measuring logger, which performs data collection from the entire system, processes the data and generates the desired quantity of them for semiconductor converters control. These converters perform control of energy flows throughout the accumulation system.

The design and operation of a liquid cooled voltage inverter for an accumulation unit

This paper deals with the power design and operation of an 80kW, high efficient reversible voltage inverter (RVI) for electric energy accumulation based systems. The energy converter is characterized by its dynamic responses on desired energy flow direction changes and is built as a liquid cooled system. The theoretical part of this paper describes the power design of IGBT transistors and DC link capacitors, as well as the application of the 3D CAD and 3D FEM systems, which have been used for constructional arrangement designing and thermal/CFX analyses. The ripple current and thermal dimensioning of the capacitor battery was simulated in the OrCAD PSpice electronic circuit simulator. The practical part of this paper shows the utilization of whole energy converter in the accumulator switchboard, as well as the examples of converters operation in cases of battery charging and discharging to the grid. The main practical utilization possibilities of presented device are in the renewable energy plants, active charging stations or smart grid systems targeted on the electric energy accumulation.

Control methods of modern systems utilizing accumulation of electrical energy

Trend of increasing the share of electricity production from the renewable energy sources will surely continue the in the upcoming time period. This paper outlines multiple solutions of accumulation of energy, especially electricity, in the Technology Center of Ostrava (TCO). It presents solutions for storage of electrical energy into the batteries with use of power converters with an additional function of active power filtering. The paper aims primarily to familiarize the reader with the methods of controlling power converters at the basic level. It deals with the current and power regulation of individual inverters and their concepts, but not on their superior management, decision-making and control processes around the technology center.

Power converters for coupling hydrogen-based technologies with lead-acid and LiFePO 4 batteries

This paper deals with power semiconductor converter technology used for coupling the hydrogen-based technologies like electrolyzers and fuel cells with different types of the accumulators. The current control methods for two-phase buck-boost converter are further presented in this paper. The function of the coupling converter has been proven in both directions of current/power flow in the experimental results section.

ZCS concept of single-phase traction supply converters

At the present time the major part of traction systems uses single-phase 25kV/50Hz or 15kV/16,66Hz circuitry to traction vehicles supply. The supply stations of traction systems were made in different ways like rotary converters, cycloconverters and actually DC-link converters. The paper compares the static converter features and introduces the new concept of current-type soft switching DC-link frequency converter. This concept uses the three-phase zero current switch pulse rectifier, current-type, as a modern input unit of current indirect frequency converters including soft switching. The converter has many advantages e.g. the low emissions of harmonic components into the mains, the controlled power factor, the convenient current control in the DC link and low switching losses. This type of converter solves some problems of EMC and can control the converter power factor on the mains side. The suitable delta modulation of the converter is also described in the paper. The measured results were done in the application of the realized pulse rectifier as the input unit of the zero current switching indirect frequency converter with the series resonant DC link.

The boost converter with air core coil

This paper deals about the possibility of using air coils in boost converters, which is useful within the range of frequencies from 200kHz to 1MHz when the transmitted power is in hundreds of kilowatts. The article also analyzes the activity of boost converter - it deals with the demands placed on the converters coil magnetic circuit and the consequences of an increased switching frequency on its constructional solution. It considers the influence of air coils on the constructional solution of the converter and its efficiency or EMC properties. The design and practical realization of the boost converter with SiC MOSFET is described in the conclusion part of this paper, as well as the simulation results and measurements of the laboratory model. The designed converter operates with high switching frequencies over 200kHz.