Ivo Pazdera

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.

Measurement of Power Transistors Dynamic Parameters

This article deals with analysis of switching processes of power transistor as well as with description of performed measurement methods of these dynamic processes. The results are demonstrated on power IGBT transistor, nevertheless the measurement methods are valid for all power devices in general. Due to the fact, that the extremely dynamic and power processes have to be analyzed, then the special measuring laboratory workplace (MLW) was developed for proper oscillographic measurement of these processes. Further, the current sensor with ultra-wide bandwidth has to be developed. Description of the MLW is presented in this paper together with its development process. This paper gives the complex methodology for analysis of power devices switching processes.

Speed Estimator for Low Speed PMSM Aerospace Application

The paper is focused on development of low speed PMSM direct drive application. The high resolution of position setting (18 bits per revolution) is demanded at very low speed about 10 RPM. The quantization of speed controller error cause unaccepted torque ripple. The digital filters reduce dynamic of speed control loop therefore, the speed estimator has to be employed to reduce torque ripples without reduction of speed control performance. The application is intended for demanded aerospace application. The paper describes design of speed estimator with cooperation of vector controlled PMSM motor. The Simulink model is realized to verify the proper operation of whole drive application and simulation results are presented in this paper.

Induction Machine Models and Equivalent Circuits Based on Hybrid Parameters of Two-Port Network

The paper is focused on development of induction machine (IM) model based on general two-port network theory, which is elemental theory well-known for all electrical engineers. Since the theory of IM is more specialized and known for engineers with some expertise in the field of electrical machines and drives. Application of the two-port network theory on IM can clarify the development process of IM model or eventually equivalent circuit for wide area of electrical engineers. The whole building process is also based on analogy with transformer and the theory of rotational coordinates is also employed. The models and equivalent circuits are then more suitable for understanding physical principles of IM from macroscopic point of view.

Dynamic Model of Wye Connected Induction Machine

The paper deals with a derivation of a dynamic model of induction machines with wye connected stator and rotor windings. The mathematical modeling of any electric machine is an inseparable part of the knowledge of any future/present engineers involved in the control of the electric drives. In the paper, several models of the induction machines are derived in a comprehensible way with an emphasis on structural and parameter integrity of all models. Derived dynamic model with line-to-line stator voltages presents a simple substitution to more general but also more complicated natural model of induction machines.

The New Stepper Driver for Low-Cost Arduino Based 3D Printer with Dynamic Stepper Control

The article deals with design of a new stepper driver for axis control of Arduino based 3D printer. The driver was designed because of the ineligible conception of mostly used ones plug and play modules based on A4988 or similar and because there is still a gap in open source drivers available on the marker. It is based on integrated stepper driver with much higher power and in much better mechanical conception. Also, a big emphasis was placed on the PCB design, which is proved in final testing comparing quality of power chips supply. In combination with innovated control system, this driver allows using Dynamic Stepper Control ability, which allows affecting stepper motor parameters like phase cur-rent and micro-stepping level in real time on demand by control software.

Winding reconstruction based on magnetic flux density in air-gap of IM

This paper deals with a reconstruction of a three-phase winding based on the knowledge of a course of magnetic flux density in the air-gap of an induction motor. The paper is divided in two main parts. The first part deals with introduction of measured motor and comparison of measured courses of speed and stator currents with simulated results. The second part deals with analysis of magnetic flux in the air-gap and reconstruction of the winding. There is derived an equation for calculation of a total number of winding conductors based on the magnetic flux density in the air-gap.

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.