Dalibor Cervinka

Design of small electric car

Paper deals with design of traction drive for small electric car where its primary energy source is realized by two hydrogen cells with nominal power 2 × 1,2 kW. Main attention is paid to find appropriate torque-velocity, resp. power-velocity dependences related to wheel of the small electric car. According to these characteristics an appropriate gear ratio is calculated. Finally, an appropriate traction motor is chosen.

Efficiency optimization of small hydro power plant in low power operation

This paper deals with a low power operation of small hydro power plants. It is typical for small hydro power plants on small rivers without reservoirs where the power in low season is less than one-third of nominal power. That is why the efficiency is decreased. The generator has low efficiency in this operation due to constant no load losses. The analysis of losses is presented and possible improvements are suggested. The last part of this paper presents a simple method of reducing no load losses, calculation of the power savings and experimental validation of this method.

Increasing the Efficiency of Induction Generator in Small Hydro Power Plant for Varying River Flow Rate

This paper deals with improving efficiency of a small hydro power plant that not operates in nominal power, but in lower power. Efficiency is lower in this low power operation than in nominal power operation since constant no-load losses. These no-load losses can be varied by changing stator voltage and it may produce higher efficiency. Relation between efficiency, power operation and stator voltage are presented and the highest possible efficiency is highlighted. This process is made for typical 15 kW small hydro power plant with horizontal Francis turbine. Finally, there is comparison between original efficiency of generator and improved efficiency with corresponding stator voltage and one year power savings.

The Novel Device for Irreversible Electroporation: Thermographic Comparison with Radiofrequency Ablation

Irreversible electroporation is a relatively new technique for minimal invasive non-thermal ablation treatment of solid tumors. This article describes basics of the method and presents comparative tissue temperature measurements of irreversible electroporation and radiofrequency ablation during and immediately after the procedure. The novel generator for irreversible electroporation was tested. All thermographs were generated by an infrared camera. The experiments were performed ex vivo on a porcine liver. The temperature rose by 3 K and 6 K during electroporation and by 20.7 K and 38.5 K in the case of radiofrequency ablation. This is a significant difference showing that the irreversible electroporation is capable of providing successful tissue ablation without thermal damage. This is advantageous especially in areas adjacent to sensitive structures such as blood vessels, biliary tract, nerves, bronchi etc.

High-Voltage Pulse Source for Cell Electroporation

Electroporation is a experimental non-thermal technique for treatment of tumors. The principle of the method lies in delivering of short high-voltage pulses into the treated tissue. The article is focused on development and test process of impulse power source for these purposes. At first, the property of electroporation device is defined and construction variants are discussed. Next, the used topology of power stage and control circuits is presented. Finally, the power source is tested and measured waveforms are presented.

Modular system of converters with interleaved structure

This article deals with modular system of DC-DC converters which contains more than one converter. It is possible to connect all converters in parallel for gain high output current, all converters in serial for high output voltage or various combinations to reach desired output voltage and current. The paper describes possible control structures for mentioned connections. This system is self-reconfigurable - whole system should immediately change internal connection according required output parameters. The forward converter with a transformer was chosen as a basic element of the system. The modular system is interleaved; it leads to output current and voltage ripple reduction and cheaper output filter.

Discrete and continuous fractional controllers

This article deals with a comparison of discrete and continuous fractional speed controller of DC motor with permanent magnets. The first part of this article deals with an introduction into fractional calculus with aim to software implementation of fractional controller. The discrete controller is based on direct use of Grunwald-Letnikov interpretation of fraction derivative. The continuous fractional controller is based on Oustaloups recursive approximation of fractional derivative. The second part deals with a comparison of both fractional controllers with a PI controller for DC motor with permanent magnets. Optimal parameters for all controllers are found by a genetic algorithm.

Universal test bench for AC traction motors 600V/500A

The paper describes design and realization of the universal test bench intended for testing of electric traction machines for electric pallet truck and forklifts. The extreme parameters (Output current up to 500A and max. output voltage up to 600V) are desired for possibility to test prototypes of the motors with wide range of voltages and currents. Another unconventional parameter of this test bench is availability to connect wide range of speed and positions sensors commonly used in motor applications (resolvers, sin/cos encoders, incremental encoders or others sensors with various digital interfaces). The paper describes design of power part of the test bench as well as its control and measurement structure with sensor data processing circuits. Significant part of the article is the example of use “reconfigurable topology amplifier” tool for adaptation of current sensor signal to analog-digital converter.

Communication and energy management system of small electric airplane

The paper deals with internal communication system in experimental fully electric airplane VUT 051 RAY which is controlling the whole drivetrain system. The complex drivetrain system consist of battery blocks, main computer, control system of the traction inverter, control and monitoring panel, several simple control and monitoring devices placed on pilot board and finally control system of fast charger. Communication interface is realized with CAN network with parallel analog backup structure. All operating conditions are indicated on Onboard monitoring Panel. Significant part of the data structure of the airplane is implemented data logger which is restoring all system events on all communications links. These data can be used for deep analysis of the parameters of energy flows in the airplane drivetrain. The occurred errors and nonstandard drivetrain states are saved too. Finally, the state of charge estimation is discussed.

Electric powered airplane VUT 051 RAY

The paper deals with a drive system of experimental fully electric airplane VUT 051 RAY with rated power 55 kW. The requirements on accumulator capacity and its weight were defined according to a precisely specified flight profile. The whole design process of traction inverter is presented. Drive train system of electric airplane was completely tested, before its final installation into fuselage of airplane. Measured parameters gained by testing are presented too. Finally, the results of first flight are presented.