Pablo Correa | Technical University of Kosice (original) (raw)

Papers by Pablo Correa

Research paper thumbnail of The Effect of Vaccination with the PAV-250 Strain Classical Swine Fever(CSF) Virus on the Airborne Transmission of CSF Virus

Journal of Veterinary Medical Science, 2001

The airborne transmission of Classical Swine Fever (CSF) virus to susceptible pigs, as well as th... more The airborne transmission of Classical Swine Fever (CSF) virus to susceptible pigs, as well as the effect of vaccination with the CSF virus PAV-250 strain was investigated on this mode of transmission. Experiment I: four pigs were inoculated with the ALD CSFV strain (10(4.3) 50% TCID) by the intramuscular route, and at the onset of fever, they were introduced into an enclosed chamber. At the end of the experiment surviving pigs were sedated, anesthetized and euthanatized. Experiment II: four pigs were previously vaccinated with the CSF virus PAV-250 strain, and at 14 days post-vaccination they were challenged with the CSF virus ALD strain. In both experiments, four susceptible pigs were exposed to infectious aerosols by placing them in a chamber connected by a duct to the adjacent pen containing the infected animals and were kept there for 86 hs. In Experiment I, pigs exposed to contaminated air died as a result of infection with CSF virus on days 14, 21 and 28 post-inhalation. These four pigs seroconverted from day 12 post-inhalation. CSF virus was isolated from these animals, and the fluorescent antibody test on tonsils was positive. In Experiment II, a vaccinated pig exposed to contaminated air did not seroconvert, nor was CSF virus isolated from lymphoid tissues. However, mild fluorescence in tonsil sections from these pigs was observed. In conclusion, CSF virus was shown to be transmitted by air at a distance of 1 m to susceptible pigs. Vaccination with the PAV-250 CSF virus strain protected the pigs from clinical disease under the same conditions.

Research paper thumbnail of Modulation Strategies for Fault-Tolerant Operation of H-Bridge Multilevel Inverters

The operation of the H-bridge multilevel inverter under fault conditions is examined in this pape... more The operation of the H-bridge multilevel inverter under fault conditions is examined in this paper. In the event of a fault, the cell with problems can be bypassed to enable the operation of the inverter with fewer cells. This approach could result in an unbalanced inverter configuration which can be corrected by modifying the modulation scheme. Two different approaches based on the phase shift-PWM (PS-PWM) and the space phasor modulation (SPM) are considered to compensate the voltage unbalance. Aspects such as the firing pulses generation and the use of optimal sequences are also discussed. The feasibility of the method is demonstrated using simulated as well as experimental results in a 5-level H-bridge multilevel inverter

Research paper thumbnail of A vector control technique for medium-voltage multilevel inverters

IEEE Transactions on Industrial Electronics, 2002

Research paper thumbnail of A vector control technique for medium voltage multilevel inverters

This paper presents a switching strategy for multilevel cascade inverters, based on the space vec... more This paper presents a switching strategy for multilevel cascade inverters, based on the space vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel PWM techniques considering the following aspects: (i) voltage and current THD, (ii) range of linear operation, and iii) number of commutations

Research paper thumbnail of Predictive Torque Control for Inverter-Fed Induction Machines

IEEE Transactions on Industrial Electronics, 2007

Research paper thumbnail of Direct torque control with imposed switching frequency in an 11-level cascaded inverter

IEEE Transactions on Industrial Electronics, 2004

Research paper thumbnail of A Predictive Control Scheme for Current-Source Rectifiers

IEEE Transactions on Industrial Electronics, 2009

Research paper thumbnail of Predictive control of the Indirect Matrix Converter with active damping

Research paper thumbnail of A high-performance vector control of an 11-level inverter

IEEE Transactions on Industrial Electronics, 2003

Research paper thumbnail of Fault‐tolerant operation of multicell‐inverters with a space phasor modulator

European Transactions on Electrical Power, 2008

This paper presents a new space phasor modulation (SPM) scheme for the operation of the H-bridge ... more This paper presents a new space phasor modulation (SPM) scheme for the operation of the H-bridge multicell inverter under fault conditions. The topology of this inverter consists of several single-phase H-bridge inverters which can be independently bypassed if a fault is detected. As this action may result in an asymmetrical inverter topology, a new method based on the SPM is proposed to avoid voltage unbalances. Simulations and experimental results obtained in a five-level multicell inverter prototype validate the proposed fault-tolerant method. Copyright © 2007 John Wiley & Sons, Ltd.

Research paper thumbnail of Predictive control with active damping in a Direct Matrix Converter

This paper presents a control scheme applied to the Direct Matrix Converter (DMC), which combines... more This paper presents a control scheme applied to the Direct Matrix Converter (DMC), which combines the advantages of the predictive control and active damping to reduce the resonance of the input filter. A discrete-time model of the converter and the load is used to predict the behavior of the input reactive power in the supply side and the output currents for each valid commutation state. The approach selects the best switching state according to an optimizing algorithm based in a cost function in order to generate unity input power factor and output currents with a low error respect to a reference. In addition, the predictive controller is enhanced by including active damping in order to mitigate the potential resonances in the input filter. Simulation results confirm the good performance of the strategy, allowing for controlling the converter in a simple and intuitive manner.

Research paper thumbnail of A new modulation method to reduce common-mode voltages in multilevel inverters

IEEE Transactions on Industrial Electronics, 2004

Research paper thumbnail of Predictive Current Control of a Voltage Source Inverter

IEEE Transactions on Industrial Electronics, 2007

Research paper thumbnail of Predictive control of an indirect matrix converter

This paper presents a predictive control scheme for an indirect matrix converter. The control sch... more This paper presents a predictive control scheme for an indirect matrix converter. The control scheme consists basically on selecting the switching state that minimizes the reactive power and the error in the output currents respects its reference. This is accomplished by using a prediction horizon of one sample time and a very intuitive control law. Experimental results are provided in order to validate the proposed control scheme. It is shown that the idea of controlling this converter topology with a predictive approach can be implemented in a simple way and a good performance can be obtained.

Research paper thumbnail of Control of a Single-Phase Cascaded H-Bridge Multilevel Inverter for Grid-Connected Photovoltaic Systems

IEEE Transactions on Industrial Electronics, 2009

Research paper thumbnail of Control of a single phase H-Bridge multilevel inverter for grid-connected PV applications

This paper proposes a control scheme for a single phase H-bridge multilevel converter for photovo... more This paper proposes a control scheme for a single phase H-bridge multilevel converter for photovoltaic applications. This control approach permits each H-bridge module supply different power levels, allowing an independent maximum power point tracking of each photovoltaic (PV) panel. Since no intermediate stages such boost DC-DC converters are needed, a high efficient solution is obtained compared to the standard PV converter systems. Additionally, this topology offers other advantages such as the operation at lower switching frequency and low current ripple. Simulation results of a two series connected H-bridge rectifier with maximum power point tracking for different conditions are presented.

Research paper thumbnail of A predictive control scheme for current source rectifiers

Research paper thumbnail of Predictive Control of an Indirect Matrix Converter

IEEE Transactions on Industrial Electronics, 2009

Research paper thumbnail of Control Strategy Reconfiguration for a Multilevel Inverter Operating with Bypassed Cells

Abstract This paper analyzes the fault-tolerant operation of a Series Connected H-Bridge inverter... more Abstract This paper analyzes the fault-tolerant operation of a Series Connected H-Bridge inverter topology (SCHB) supplying an induction machine. The standard approach considers a bypass of the faulty cells by means of a contactor and it carries out a reconfiguration of the modulator in order to generate balanced phase output voltages. The price that must be paid for this emergency operating mode is a reduction of the maximum voltage that the inverter can supply to the machine., therefore the limits for the torque and ...

Research paper thumbnail of Control of a cascaded H-bridge multilevel converter for grid connection of photovoltaic systems

In this paper a control method for cascaded H-bridge multilevel converters for grid connection of... more In this paper a control method for cascaded H-bridge multilevel converters for grid connection of photovoltaic systems is analyzed. The use of the multilevel converter introduces a series of advantages: improved power quality (lower current ripple), smaller filters, reduced switching frequency, no need of boost dc-dc stage and possible elimination of step-up transformer, all of which have a positive impact on the system efficiency. However it requires a more sophisticated control method specially due to dc-link voltage drifts produced by circulating power in the converter. The proposed control method is based on traditional voltage oriented control with a cascaded dc-link voltage control and grid current control loop. Two extra stages are added to this traditional control scheme, one to introduce maximum power point tracking for each module or string, and another to control the dc-link voltages drift due to circulating power in the converter. The latter is performed by the addition of a simple feedforward control strategy directly in the modulation stage. The proposed control method is modular and easy to adapt for any number of converters in series. Simulation results are presented to support the theoretical analysis.

Research paper thumbnail of The Effect of Vaccination with the PAV-250 Strain Classical Swine Fever(CSF) Virus on the Airborne Transmission of CSF Virus

Journal of Veterinary Medical Science, 2001

The airborne transmission of Classical Swine Fever (CSF) virus to susceptible pigs, as well as th... more The airborne transmission of Classical Swine Fever (CSF) virus to susceptible pigs, as well as the effect of vaccination with the CSF virus PAV-250 strain was investigated on this mode of transmission. Experiment I: four pigs were inoculated with the ALD CSFV strain (10(4.3) 50% TCID) by the intramuscular route, and at the onset of fever, they were introduced into an enclosed chamber. At the end of the experiment surviving pigs were sedated, anesthetized and euthanatized. Experiment II: four pigs were previously vaccinated with the CSF virus PAV-250 strain, and at 14 days post-vaccination they were challenged with the CSF virus ALD strain. In both experiments, four susceptible pigs were exposed to infectious aerosols by placing them in a chamber connected by a duct to the adjacent pen containing the infected animals and were kept there for 86 hs. In Experiment I, pigs exposed to contaminated air died as a result of infection with CSF virus on days 14, 21 and 28 post-inhalation. These four pigs seroconverted from day 12 post-inhalation. CSF virus was isolated from these animals, and the fluorescent antibody test on tonsils was positive. In Experiment II, a vaccinated pig exposed to contaminated air did not seroconvert, nor was CSF virus isolated from lymphoid tissues. However, mild fluorescence in tonsil sections from these pigs was observed. In conclusion, CSF virus was shown to be transmitted by air at a distance of 1 m to susceptible pigs. Vaccination with the PAV-250 CSF virus strain protected the pigs from clinical disease under the same conditions.

Research paper thumbnail of Modulation Strategies for Fault-Tolerant Operation of H-Bridge Multilevel Inverters

The operation of the H-bridge multilevel inverter under fault conditions is examined in this pape... more The operation of the H-bridge multilevel inverter under fault conditions is examined in this paper. In the event of a fault, the cell with problems can be bypassed to enable the operation of the inverter with fewer cells. This approach could result in an unbalanced inverter configuration which can be corrected by modifying the modulation scheme. Two different approaches based on the phase shift-PWM (PS-PWM) and the space phasor modulation (SPM) are considered to compensate the voltage unbalance. Aspects such as the firing pulses generation and the use of optimal sequences are also discussed. The feasibility of the method is demonstrated using simulated as well as experimental results in a 5-level H-bridge multilevel inverter

Research paper thumbnail of A vector control technique for medium-voltage multilevel inverters

IEEE Transactions on Industrial Electronics, 2002

Research paper thumbnail of A vector control technique for medium voltage multilevel inverters

This paper presents a switching strategy for multilevel cascade inverters, based on the space vec... more This paper presents a switching strategy for multilevel cascade inverters, based on the space vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel PWM techniques considering the following aspects: (i) voltage and current THD, (ii) range of linear operation, and iii) number of commutations

Research paper thumbnail of Predictive Torque Control for Inverter-Fed Induction Machines

IEEE Transactions on Industrial Electronics, 2007

Research paper thumbnail of Direct torque control with imposed switching frequency in an 11-level cascaded inverter

IEEE Transactions on Industrial Electronics, 2004

Research paper thumbnail of A Predictive Control Scheme for Current-Source Rectifiers

IEEE Transactions on Industrial Electronics, 2009

Research paper thumbnail of Predictive control of the Indirect Matrix Converter with active damping

Research paper thumbnail of A high-performance vector control of an 11-level inverter

IEEE Transactions on Industrial Electronics, 2003

Research paper thumbnail of Fault‐tolerant operation of multicell‐inverters with a space phasor modulator

European Transactions on Electrical Power, 2008

This paper presents a new space phasor modulation (SPM) scheme for the operation of the H-bridge ... more This paper presents a new space phasor modulation (SPM) scheme for the operation of the H-bridge multicell inverter under fault conditions. The topology of this inverter consists of several single-phase H-bridge inverters which can be independently bypassed if a fault is detected. As this action may result in an asymmetrical inverter topology, a new method based on the SPM is proposed to avoid voltage unbalances. Simulations and experimental results obtained in a five-level multicell inverter prototype validate the proposed fault-tolerant method. Copyright © 2007 John Wiley & Sons, Ltd.

Research paper thumbnail of Predictive control with active damping in a Direct Matrix Converter

This paper presents a control scheme applied to the Direct Matrix Converter (DMC), which combines... more This paper presents a control scheme applied to the Direct Matrix Converter (DMC), which combines the advantages of the predictive control and active damping to reduce the resonance of the input filter. A discrete-time model of the converter and the load is used to predict the behavior of the input reactive power in the supply side and the output currents for each valid commutation state. The approach selects the best switching state according to an optimizing algorithm based in a cost function in order to generate unity input power factor and output currents with a low error respect to a reference. In addition, the predictive controller is enhanced by including active damping in order to mitigate the potential resonances in the input filter. Simulation results confirm the good performance of the strategy, allowing for controlling the converter in a simple and intuitive manner.

Research paper thumbnail of A new modulation method to reduce common-mode voltages in multilevel inverters

IEEE Transactions on Industrial Electronics, 2004

Research paper thumbnail of Predictive Current Control of a Voltage Source Inverter

IEEE Transactions on Industrial Electronics, 2007

Research paper thumbnail of Predictive control of an indirect matrix converter

This paper presents a predictive control scheme for an indirect matrix converter. The control sch... more This paper presents a predictive control scheme for an indirect matrix converter. The control scheme consists basically on selecting the switching state that minimizes the reactive power and the error in the output currents respects its reference. This is accomplished by using a prediction horizon of one sample time and a very intuitive control law. Experimental results are provided in order to validate the proposed control scheme. It is shown that the idea of controlling this converter topology with a predictive approach can be implemented in a simple way and a good performance can be obtained.

Research paper thumbnail of Control of a Single-Phase Cascaded H-Bridge Multilevel Inverter for Grid-Connected Photovoltaic Systems

IEEE Transactions on Industrial Electronics, 2009

Research paper thumbnail of Control of a single phase H-Bridge multilevel inverter for grid-connected PV applications

This paper proposes a control scheme for a single phase H-bridge multilevel converter for photovo... more This paper proposes a control scheme for a single phase H-bridge multilevel converter for photovoltaic applications. This control approach permits each H-bridge module supply different power levels, allowing an independent maximum power point tracking of each photovoltaic (PV) panel. Since no intermediate stages such boost DC-DC converters are needed, a high efficient solution is obtained compared to the standard PV converter systems. Additionally, this topology offers other advantages such as the operation at lower switching frequency and low current ripple. Simulation results of a two series connected H-bridge rectifier with maximum power point tracking for different conditions are presented.

Research paper thumbnail of A predictive control scheme for current source rectifiers

Research paper thumbnail of Predictive Control of an Indirect Matrix Converter

IEEE Transactions on Industrial Electronics, 2009

Research paper thumbnail of Control Strategy Reconfiguration for a Multilevel Inverter Operating with Bypassed Cells

Abstract This paper analyzes the fault-tolerant operation of a Series Connected H-Bridge inverter... more Abstract This paper analyzes the fault-tolerant operation of a Series Connected H-Bridge inverter topology (SCHB) supplying an induction machine. The standard approach considers a bypass of the faulty cells by means of a contactor and it carries out a reconfiguration of the modulator in order to generate balanced phase output voltages. The price that must be paid for this emergency operating mode is a reduction of the maximum voltage that the inverter can supply to the machine., therefore the limits for the torque and ...

Research paper thumbnail of Control of a cascaded H-bridge multilevel converter for grid connection of photovoltaic systems

In this paper a control method for cascaded H-bridge multilevel converters for grid connection of... more In this paper a control method for cascaded H-bridge multilevel converters for grid connection of photovoltaic systems is analyzed. The use of the multilevel converter introduces a series of advantages: improved power quality (lower current ripple), smaller filters, reduced switching frequency, no need of boost dc-dc stage and possible elimination of step-up transformer, all of which have a positive impact on the system efficiency. However it requires a more sophisticated control method specially due to dc-link voltage drifts produced by circulating power in the converter. The proposed control method is based on traditional voltage oriented control with a cascaded dc-link voltage control and grid current control loop. Two extra stages are added to this traditional control scheme, one to introduce maximum power point tracking for each module or string, and another to control the dc-link voltages drift due to circulating power in the converter. The latter is performed by the addition of a simple feedforward control strategy directly in the modulation stage. The proposed control method is modular and easy to adapt for any number of converters in series. Simulation results are presented to support the theoretical analysis.