Jan Molnar

Single-phase current-source active rectifier for traction applications: new control strategy based on phase shift controller

This research has been motivated by industrial demand for single-phase current-source active rectifier (CSAR) dedicated for reconstruction of older types of dc machine locomotives operating on both ac catenary voltages of 25 kV/50 Hz and 15 kV/16 2/3 Hz. This contribution presents new control strategy of CSAR using controller of phase shift angle (phi) between trolley wire voltage and current. Regarding possible interaction with railway control signalling and due to the low switching frequency, the designed converter employs synchronous PWM. This paper describes in detail proposed converter control and presents simulation results of the laboratory prototype. The simulation results and theoretical conclusions are verified by experiments performed on designed low power laboratory prototype of traction CSAR with rated power of 7 kVA.

Control of traction single-phase current-source active rectifier under distorted power supply voltage

This research has been motivated by industrial demand for single-phase current-source active rectifier (CSAR) dedicated for reconstruction of older types of dc machine locomotives. This contribution presents new control strategy of CSAR using controller of phase shift angle (phi) between trolley wire voltage and current supplemented by compensation of trolley wire current waveform under supply voltage distortion. This control is able to keep the trolley wire current in demanded phase shift against supply voltage and preserve sinusoidal waveform of consumed current even under distorted trolley wire voltage. Simulation results and theoretical conclusions are verified on designed laboratory prototype of 7 kVA.

Control of primary voltage source active rectifiers for traction converter with medium-frequency transformer

This paper deals with the new configuration of the traction converter with medium-frequency transformer intended for AC trolley wire fed locomotives. The main attention is paid to the primary serially connected single-phase voltage-source active rectifiers, which are directly connected to the trolley wire. This paper describes the control of the primary active rectifiers, presents simulation results as well as experimental evidence of designed low-voltage laboratory prototype of loco converter of rated power of 12 kW.

Design of new diesel-electric power supply unit for military vehicles

This paper introduces a new designed diesel-electric power-supply unit developed for military purposes. The power-supply unit is divided to two main electric parts, (i) input part which is composed of a sensorless controlled active voltage source rectifier supplied by a permanent magnet synchronous generator, and (ii) output part which is composed of a four-leg three-phase voltage source inverter with a sinusoidal LC filter with the output voltage controlled by a proportional-resonant controllers bank. The proper function of both parts of the supply unit has been verified by simulations as well as on laboratory prototypes of the devices.

Comparison of 3D-SVPWM and Carrier-Based PWM of three-phase four-leg voltage source inverter

This paper deals with design of a new control system for a diesel-electric power supply unit, which output part is composed of a three-phase four-leg voltage source inverter. The main emphasis is given in this paper on employed modulation techniques. We are introducing two modulation strategies: 1) three- dimensional space vector PWM (3D-SVPWM) and 2) improved carrier-based PWM (CBPWM), which employs control of voltage offset via control of the fourth inverter leg. Further, control algorithms enabling operation of the supply unit under arbitrary load conditions (linear, non-linear, symmetrical, unsymmetrical etc.) in any case with sinusoidal voltages at the converter output are described. Behaviour of the designed control system with both 3D-SVPWM and CBPWM strategies has been verified on a laboratory prototype of the power supply unit with rated power of 18 kVA.

Control of primary voltage-source active rectifiers of traction converter with medium-frequency transformer: Advantages of control unit combining DSP and FPGA

This paper investigates traction converter with medium-frequency transformer intended for modern suburban units. It describes proposed control of primary voltage-source active rectifiers with PR-controller completed by harmonic compensator. Developed control was implemented in control unit combining DSP and FPGA. Proposed control system properties are analyzed by experiments made on developed down-scale traction converter.

Variable speed pumping in thermal and nuclear power plants: Frequency converter versus hydrodynamic coupling

In this paper, a comprehensive case study analysis of flow control methods and appropriate technical implementations for high-power pump systems employed in thermal and nuclear power plants or heating plants will be presented. The main attention is focused on a comparison of two advanced variable speed control strategies employing VSD with frequency converter and VSD with hydrodynamic coupling.

Complete design of down-scale prototype of mining machine converter based on four-level voltage-source converter with flying capacitors

This contribution describes complete design of a three-phase four-level voltage-source converter for a new mining machine drive. Particularly, it is focused on development of a down-scale laboratory prototype of a converter with rated power of 30kVA. Moreover, the control system called REMCS which has been designed for control of the final full power prototype is also introduced. The proper function of the developed converter prototype is verified by selected experiments.

Sophisticated software for design and optimization of VSDs for high-power pumps: Variable speed drive with frequency converter

This paper deals with a developed software for design and optimization of variable speed drives (VSDs) for high-power water pumps and fans in power and heating plants. The paper presents the physical background of modeling and proposed models of a variable speed drive with frequency converter.

Active suppression of low-frequency disturbances on AC side of traction active current-source rectifier

This paper deals with traction active current-source rectifier (ACSR) developed within the research into a new generation of main traction converters employing medium-frequency transformer dedicated for suburban units operating on both ac electrification systems of 25kV/50 Hz and 15kV/16⅔ Hz. The new control strategy able to operate under distorted trolley-wire voltage and actively suppress (i) low-frequency disturbances in trolley-wire current caused by distorted trolley-wire voltage, and (ii) input LC filter oscillations is presented. Proper function of proposed control strategy has been verified by simulations and large experimental study made on designed small-scale prototype of ACSR of rated power of 7kVA.