This paper describes the design, modeling and implementation of a single-phase inverter connected... more This paper describes the design, modeling and implementation of a single-phase inverter connected to the grid from renewable energy sources. We study the model in small signal to be below the control loops design it. In order to control the injection of energy into the grid from renewable is proposed for average current control (ACC). Drivers are obtained through the analysis applied to the small signal model obtained from the PWM switch model and the approach of the investor to a Buck converter. Finally, simulations and experimental tests conducted to validate the transient response and steady-state investor.
Proceedings of the IEEE International Symposium on Industrial Electronics, 2005. ISIE 2005., 2005
A robust control technique for power factor correction rectifiers with average current mode contr... more A robust control technique for power factor correction rectifiers with average current mode control is proposed in this paper. By adding a load current loop to the conventional current mode scheme, the output voltage response to load steps is much faster and therefore the typical voltage over-shoots that this kind of converters presents are reduced. Although the load current injection
Proceedings of the IEEE International Symposium on Industrial Electronics, 2005. ISIE 2005., 2005
... Abstract A robust model-following regulator for Boost dc-dc converters with Average Current ... more ... Abstract A robust model-following regulator for Boost dc-dc converters with Average Current Mode Control is proposed in this paper. The aim of the proposed circuit is to reduce the closed loop output impedance and audiosusceptibility ...
ISIE '99. Proceedings of the IEEE International Symposium on Industrial Electronics (Cat. No.99TH8465), 1999
Shunt active power filters are used to eliminate the current harmonics and to improve the power f... more Shunt active power filters are used to eliminate the current harmonics and to improve the power factor in systems with nonlinear loads. At the present time, different methods exist to control active power filters. Some of them are based on instantaneous reactive power theory and others are based on the synchronous reference frame using Park's transformation. The purpose of this
ISIE '99. Proceedings of the IEEE International Symposium on Industrial Electronics (Cat. No.99TH8465), 1999
The purpose of this paper is to present a drastic improvement in the conventional ACC (average cu... more The purpose of this paper is to present a drastic improvement in the conventional ACC (average current mode control) of switching DC-DC power converters, consisting of the addition of an auxiliary controller in the control loop, besides the current and voltage regulators. The model-based auxiliary controller preserves the closed loop small-signal bandwidth (including loop gain crossover frequency and stability margins)
IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02, 2002
A robust scheme for duty ratio control of DC-DC switching converters is presented. The proposed m... more A robust scheme for duty ratio control of DC-DC switching converters is presented. The proposed method adds a high gain robust loop with two controllers to the conventional single loop, achieving an analog adaptive scheme in which the voltage loop gain is not very sensitive to the changing power stage parameters: input voltage, load and component tolerances. The proposed loop
PESC Record. 27th Annual IEEE Power Electronics Specialists Conference, 1996
The purpose of the article is the description, considerations of design and presentation of exper... more The purpose of the article is the description, considerations of design and presentation of experimental results of a high current (1000 A) and low voltage (up to 15 V) converter for the excitement of superconducting corrector magnets in particle accelerators. The power source, which is based on a ZVT converter, presents high efficiency, small output ripple, excellent regulation of line,
ABSTRACT This paper presents the design, analysis and implementation of two control Schemes (Repe... more ABSTRACT This paper presents the design, analysis and implementation of two control Schemes (Repetitive Two-Degrees of Freedom (R2DOF) control and A PI-P+Resonant controller) with the aim of reducing the Total Harmonic Distortion in Voltage (THDv). When the inverter is working as a voltage source these schemes are useful in island mode operation. The purpose is to keep the output voltage waveform, frequency and amplitude according to the standard IEEE 519, when nonlinear loads are feed. A comparative analysis derived from inverter simulations with nonlinear loads is realized in order to validate those control techniques.
2007 IEEE International Symposium on Industrial Electronics, 2007
The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inver... more The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inverters for distributed power generation. The main issues regarding the design of the control stage are outlined, including a small signal model of the photovoltaic cells for control purposes and the influence of high order grid filters on the system stability. Experimental results carried out
Robust parametric control theory is a powerful tool for the research of linear control systems ro... more Robust parametric control theory is a powerful tool for the research of linear control systems robustness against simultaneous changes in the parameters that define the plant and controller transfer functions. The purpose of this paper is to show how those techniques can be applied to the comparative performance study of conventional average current mode control (ACC) of DC-DC converters and
This work presents a new robust control technique for boost based high power factor rectifiers. T... more This work presents a new robust control technique for boost based high power factor rectifiers. The proposed control scheme improves significantly the dynamic response of the converter without the need of high crossover frequencies in the voltage loop. Therefore, the harmonic distortion components of the input current are easily reduced. Experimental measurements on a 250 W low harmonic rectifier have
ABSTRACT The purpose of this paper is to analyze the stability of closed loop switching power amp... more ABSTRACT The purpose of this paper is to analyze the stability of closed loop switching power amplifiers using an accurate model of a loudspeaker installed in a commonly used bass reflex enclosure instead of the purely resistive model that can be used with a Zobel network. The model takes into account the electrical-mechanical-acoustical parameters of the transducer as well as the voice-coil loudspeaker's non-linear behavior, avoiding stability problems when trying to compensate for the output filter stage, thus obtaining better THD figures. This model has been experimentally tested and then used to design a regulator for Voltage-Mode Control method by means of MATLAB software. The regulator has been simulated using a full-bridge power converter along with the proposed model of the transducer.
ABSTRACT This paper encompasses the study of modelling and design of WECS, using a wind turbine w... more ABSTRACT This paper encompasses the study of modelling and design of WECS, using a wind turbine with known dynamic characteristics and a permanent magnet synchronous generator driven by a back to back power converter topology. The dynamic modeling allows to know the response of the turbine generator system in the whole range of operation. In this study, it is proposed a variable structure control scheme with two different kind of operation, namely maximum power point tracking (MPPT) and constant power (CP). In the CP region, it is demonstrated that the system is controllable with the speed control loop while that using torque control an unstable control loop results.
International Journal of Electrical Power & Energy Systems, 2009
This paper presents a robust control technique applied to a three-phase shunt active filter based... more This paper presents a robust control technique applied to a three-phase shunt active filter based on an NPC inverter, showing the modelling procedure needed to carry out the proposed control. The transfer functions for the control of the currents injected by the active filter are derived. The modelling is based on the abc/dq Park transformation of the AC system variables. The currents injected by the active filter are controlled in the synchronous orthogonal dq reference frame. The proposed robust current control technique is compared to a conventional PI controller in the dq frame, and to a PIS controller in the dq frame, consisting of a PI and resonant controllers synchronized to the frequencies of the nonlinear load current harmonics. On one hand, it is shown that the proposed technique improves the current harmonics compensation obtained by conventional PI control. On the other hand, it is found that the PIS controller is the best suited for current harmonics compensation among the controllers under study. Nevertheless, the RMF controller results in a simpler implementation than the PIS controller. Moreover, the proposed robust control has been applied to the DC-link voltage regulation, and it has been compared to a PI controller. It is shown that the robust control technique improves the dynamic response of the inverter to load steps without the need of a high crossover frequency of the DC-link voltage loop.
ABSTRACT This paper presents a comparison between of two type of current control to reduce the TH... more ABSTRACT This paper presents a comparison between of two type of current control to reduce the THDi and increase the PF in a Three-Phase Boost Rectifier driving a small wind turbine. The two types of current controls are peak current mode control and average current mode control It is used as the input stage of small wind turbines with permanent magnet synchronous generators operating at variable speed. The Boost Rectifier output is connected to an inverter which injects the energy to a distribution power grid. The operation in discontinuous conduction mode allows significantly reducing the Total Harmonic Distortion of the current in the small wind turbine. However, it is necessary to add an input filter so that the switching ripple doesn't affect the turbine. The results demonstrate that it is better the peak current mode control, because it is achieved a smaller THDi and a higher PF in all over the operating range of the generator.
Proceedings of the IEEE International Symposium on Industrial Electronics ISIE-02, 2002
The purpose of this paper is to present an analog and robust voltage-mode control loop of buck de... more The purpose of this paper is to present an analog and robust voltage-mode control loop of buck derived converters, which maintains the crossover frequency and the phase margin of the loop gain much closer to the design goals than the conventional loop, even with large variations of the power stage elements. Furthermore, the proposed scheme can achieve that the power
2007 European Conference on Power Electronics and Applications, 2007
The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inver... more The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inverters for distributed power generation. The main issues regarding the design of the control stage are outlined, including a small signal model of the photovoltaic cells for control purposes and the influence of high order grid filters on the system stability. Experimental results carried out on a 100 kW inverter are presented to validate the analytical results. The experimental inverter generates a balanced set of currents with a distortion lower than 3%.
2007 European Conference on Power Electronics and Applications, 2007
ABSTRACT A robust control technique applied to modular UPS inverters operating in parallel is pre... more ABSTRACT A robust control technique applied to modular UPS inverters operating in parallel is presented. When compared to conventional PI control, the proposed technique improves the response of the output voltage to load steps and to high distorted output currents, achieving an excellent distribution of currents between modules. The crossover frequency of the different loop gains involved is moderate, so that robustness to variations of the operation point and to tolerances of the output LC filter components values is achieved. Experimental results on a 1 kVA modular UPS system confirm the viability of the proposed scheme.
This paper describes the design, modeling and implementation of a single-phase inverter connected... more This paper describes the design, modeling and implementation of a single-phase inverter connected to the grid from renewable energy sources. We study the model in small signal to be below the control loops design it. In order to control the injection of energy into the grid from renewable is proposed for average current control (ACC). Drivers are obtained through the analysis applied to the small signal model obtained from the PWM switch model and the approach of the investor to a Buck converter. Finally, simulations and experimental tests conducted to validate the transient response and steady-state investor.
Proceedings of the IEEE International Symposium on Industrial Electronics, 2005. ISIE 2005., 2005
A robust control technique for power factor correction rectifiers with average current mode contr... more A robust control technique for power factor correction rectifiers with average current mode control is proposed in this paper. By adding a load current loop to the conventional current mode scheme, the output voltage response to load steps is much faster and therefore the typical voltage over-shoots that this kind of converters presents are reduced. Although the load current injection
Proceedings of the IEEE International Symposium on Industrial Electronics, 2005. ISIE 2005., 2005
... Abstract A robust model-following regulator for Boost dc-dc converters with Average Current ... more ... Abstract A robust model-following regulator for Boost dc-dc converters with Average Current Mode Control is proposed in this paper. The aim of the proposed circuit is to reduce the closed loop output impedance and audiosusceptibility ...
ISIE '99. Proceedings of the IEEE International Symposium on Industrial Electronics (Cat. No.99TH8465), 1999
Shunt active power filters are used to eliminate the current harmonics and to improve the power f... more Shunt active power filters are used to eliminate the current harmonics and to improve the power factor in systems with nonlinear loads. At the present time, different methods exist to control active power filters. Some of them are based on instantaneous reactive power theory and others are based on the synchronous reference frame using Park's transformation. The purpose of this
ISIE '99. Proceedings of the IEEE International Symposium on Industrial Electronics (Cat. No.99TH8465), 1999
The purpose of this paper is to present a drastic improvement in the conventional ACC (average cu... more The purpose of this paper is to present a drastic improvement in the conventional ACC (average current mode control) of switching DC-DC power converters, consisting of the addition of an auxiliary controller in the control loop, besides the current and voltage regulators. The model-based auxiliary controller preserves the closed loop small-signal bandwidth (including loop gain crossover frequency and stability margins)
IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02, 2002
A robust scheme for duty ratio control of DC-DC switching converters is presented. The proposed m... more A robust scheme for duty ratio control of DC-DC switching converters is presented. The proposed method adds a high gain robust loop with two controllers to the conventional single loop, achieving an analog adaptive scheme in which the voltage loop gain is not very sensitive to the changing power stage parameters: input voltage, load and component tolerances. The proposed loop
PESC Record. 27th Annual IEEE Power Electronics Specialists Conference, 1996
The purpose of the article is the description, considerations of design and presentation of exper... more The purpose of the article is the description, considerations of design and presentation of experimental results of a high current (1000 A) and low voltage (up to 15 V) converter for the excitement of superconducting corrector magnets in particle accelerators. The power source, which is based on a ZVT converter, presents high efficiency, small output ripple, excellent regulation of line,
ABSTRACT This paper presents the design, analysis and implementation of two control Schemes (Repe... more ABSTRACT This paper presents the design, analysis and implementation of two control Schemes (Repetitive Two-Degrees of Freedom (R2DOF) control and A PI-P+Resonant controller) with the aim of reducing the Total Harmonic Distortion in Voltage (THDv). When the inverter is working as a voltage source these schemes are useful in island mode operation. The purpose is to keep the output voltage waveform, frequency and amplitude according to the standard IEEE 519, when nonlinear loads are feed. A comparative analysis derived from inverter simulations with nonlinear loads is realized in order to validate those control techniques.
2007 IEEE International Symposium on Industrial Electronics, 2007
The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inver... more The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inverters for distributed power generation. The main issues regarding the design of the control stage are outlined, including a small signal model of the photovoltaic cells for control purposes and the influence of high order grid filters on the system stability. Experimental results carried out
Robust parametric control theory is a powerful tool for the research of linear control systems ro... more Robust parametric control theory is a powerful tool for the research of linear control systems robustness against simultaneous changes in the parameters that define the plant and controller transfer functions. The purpose of this paper is to show how those techniques can be applied to the comparative performance study of conventional average current mode control (ACC) of DC-DC converters and
This work presents a new robust control technique for boost based high power factor rectifiers. T... more This work presents a new robust control technique for boost based high power factor rectifiers. The proposed control scheme improves significantly the dynamic response of the converter without the need of high crossover frequencies in the voltage loop. Therefore, the harmonic distortion components of the input current are easily reduced. Experimental measurements on a 250 W low harmonic rectifier have
ABSTRACT The purpose of this paper is to analyze the stability of closed loop switching power amp... more ABSTRACT The purpose of this paper is to analyze the stability of closed loop switching power amplifiers using an accurate model of a loudspeaker installed in a commonly used bass reflex enclosure instead of the purely resistive model that can be used with a Zobel network. The model takes into account the electrical-mechanical-acoustical parameters of the transducer as well as the voice-coil loudspeaker's non-linear behavior, avoiding stability problems when trying to compensate for the output filter stage, thus obtaining better THD figures. This model has been experimentally tested and then used to design a regulator for Voltage-Mode Control method by means of MATLAB software. The regulator has been simulated using a full-bridge power converter along with the proposed model of the transducer.
ABSTRACT This paper encompasses the study of modelling and design of WECS, using a wind turbine w... more ABSTRACT This paper encompasses the study of modelling and design of WECS, using a wind turbine with known dynamic characteristics and a permanent magnet synchronous generator driven by a back to back power converter topology. The dynamic modeling allows to know the response of the turbine generator system in the whole range of operation. In this study, it is proposed a variable structure control scheme with two different kind of operation, namely maximum power point tracking (MPPT) and constant power (CP). In the CP region, it is demonstrated that the system is controllable with the speed control loop while that using torque control an unstable control loop results.
International Journal of Electrical Power & Energy Systems, 2009
This paper presents a robust control technique applied to a three-phase shunt active filter based... more This paper presents a robust control technique applied to a three-phase shunt active filter based on an NPC inverter, showing the modelling procedure needed to carry out the proposed control. The transfer functions for the control of the currents injected by the active filter are derived. The modelling is based on the abc/dq Park transformation of the AC system variables. The currents injected by the active filter are controlled in the synchronous orthogonal dq reference frame. The proposed robust current control technique is compared to a conventional PI controller in the dq frame, and to a PIS controller in the dq frame, consisting of a PI and resonant controllers synchronized to the frequencies of the nonlinear load current harmonics. On one hand, it is shown that the proposed technique improves the current harmonics compensation obtained by conventional PI control. On the other hand, it is found that the PIS controller is the best suited for current harmonics compensation among the controllers under study. Nevertheless, the RMF controller results in a simpler implementation than the PIS controller. Moreover, the proposed robust control has been applied to the DC-link voltage regulation, and it has been compared to a PI controller. It is shown that the robust control technique improves the dynamic response of the inverter to load steps without the need of a high crossover frequency of the DC-link voltage loop.
ABSTRACT This paper presents a comparison between of two type of current control to reduce the TH... more ABSTRACT This paper presents a comparison between of two type of current control to reduce the THDi and increase the PF in a Three-Phase Boost Rectifier driving a small wind turbine. The two types of current controls are peak current mode control and average current mode control It is used as the input stage of small wind turbines with permanent magnet synchronous generators operating at variable speed. The Boost Rectifier output is connected to an inverter which injects the energy to a distribution power grid. The operation in discontinuous conduction mode allows significantly reducing the Total Harmonic Distortion of the current in the small wind turbine. However, it is necessary to add an input filter so that the switching ripple doesn't affect the turbine. The results demonstrate that it is better the peak current mode control, because it is achieved a smaller THDi and a higher PF in all over the operating range of the generator.
Proceedings of the IEEE International Symposium on Industrial Electronics ISIE-02, 2002
The purpose of this paper is to present an analog and robust voltage-mode control loop of buck de... more The purpose of this paper is to present an analog and robust voltage-mode control loop of buck derived converters, which maintains the crossover frequency and the phase margin of the loop gain much closer to the design goals than the conventional loop, even with large variations of the power stage elements. Furthermore, the proposed scheme can achieve that the power
2007 European Conference on Power Electronics and Applications, 2007
The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inver... more The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inverters for distributed power generation. The main issues regarding the design of the control stage are outlined, including a small signal model of the photovoltaic cells for control purposes and the influence of high order grid filters on the system stability. Experimental results carried out on a 100 kW inverter are presented to validate the analytical results. The experimental inverter generates a balanced set of currents with a distortion lower than 3%.
2007 European Conference on Power Electronics and Applications, 2007
ABSTRACT A robust control technique applied to modular UPS inverters operating in parallel is pre... more ABSTRACT A robust control technique applied to modular UPS inverters operating in parallel is presented. When compared to conventional PI control, the proposed technique improves the response of the output voltage to load steps and to high distorted output currents, achieving an excellent distribution of currents between modules. The crossover frequency of the different loop gains involved is moderate, so that robustness to variations of the operation point and to tolerances of the output LC filter components values is achieved. Experimental results on a 1 kVA modular UPS system confirm the viability of the proposed scheme.
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Papers by G. Garcera