P.C. Cortizo

Federal University of Minas Gerais, Cidade de Minas, Minas Gerais, Brazil

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Publications (45)22.79 Total impact

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    ABSTRACT: The modulation index control is used in this work to control the lamp power supply permitting the removal of the output transformer out of the inverter-resonant filter setup. The Acoustic resonance in HPS lamps can be avoided by using a controlled PWM inverter and third harmonic injection. Experimental and simulation results are shown for the control of the inverter power subject to variation in the input voltage. Results for different DC bus voltages are also provided which attest the transformer removal and avoid the acoustic resonance with different modulation indexes. An ignitor for high-intensity discharge lamps, based on forced oscillation via an external periodic voltage square wave, supplied by a digitally controlled inverter, is also presented. The crest factor of the current can also be reduced by this approach.
    Eletrônica de Potência. 01/2013; 18:815-822.
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    ABSTRACT: One seeks, in this paper, to develop and compare the performances of four different models for HPS lamps operating with harmonic injection. Simulation results of the models studied are compared with experimental results for the lamp fed with sine waveform voltage due to LC network connected between the inverter and the load. The behavior of incremental impedance is observed in simulation by the variation in the imposed current to the lamp. From this comparison one chooses the model presenting the best performance rates at both low and high frequencies.
    Industrial Electronics Society, IECON 2013 - 39th Annual Conference of the IEEE; 01/2013
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    ABSTRACT: The modular multilevel converter (MMC) is based on the cascaded interconnection of half-bridge switching sub-modules. It features modular characteristics that allow its expandability while providing high quality voltage and current output waveforms and removing the need for bulky passive filters. This paper proposes a control technique and two modulation techniques for the modular multilevel converter. For the first time a multiple cuts ellipsoidal algorithm is used in order to find the switching angles for the selective harmonic elimination (SHE PWM).
    Industrial Electronics Society, IECON 2013 - 39th Annual Conference of the IEEE; 01/2013
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    ABSTRACT: This paper presents the design and implementation of an intelligent lighting system using power LEDs. The developed system is able to operate under normal power supply through power grid, as well as in the absence of supply, consisting in the emergency mode. The choice of power LEDs as light source is mainly due to long lifetime and high luminous efficiency of these components, features highly desirable in lighting systems, especially in emergency lighting systems. The system is provided with intelligence implemented in a microcontroller, and is capable of decision making and energy consumption optimization. The system has wireless communication with a remote device via Bluetooth® specification. Through this wireless link, it is possible to have total control of the light intensity, as well as obtaining information about the battery status and the duration of interruptions.
    IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society; 01/2012
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    ABSTRACT: This study addresses the control of boost converters applied for power-factor correction in universal-line applications, using adaptive non-linear control based in passivity. The controller design is independent of the operating point and the gains of the control law have a clear physical interpretation. Discussion of the control approach with unknown load is provided. Robustness analysis of the proposed approach and comparison with standard approaches are made. The performance of the proposed power factor correction (PFC) rectifier was evaluated on an experimental 630 W universal-line PFC prototype.
    IET Control Theory and Applications 01/2012; 6(14):2168-2178. · 1.72 Impact Factor
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    ABSTRACT: In the context that involves low and medium powers, boost-type converters have high performance and is therefore strongly recommended to work in regulated sources. However, without adequate control such converters eventually provide high levels of THD (Total Harmonic Distortion) and low power factor (pf). In this way, different authors validated the passivity-based control (PBC) applied to static converters. However, through these studies it was observed that the quality of results is associated with the input signal voltage. Thus, the insertion of the PLL (Phase-Locked Loop) is justified by the poor quality of networks in general. That is usually the power supply voltages are not purely sinusoidal and have very harmonic content. Thus, lower THD levels can be obtained by adding the PLL for imposing a sinusoidal reference signal to the input voltage.
    Industry Applications (INDUSCON), 2012 10th IEEE/IAS International Conference on; 01/2012
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    ABSTRACT: A generic recursive algorithm for n-level multi point clamped converter is proposed. The multilevel space vector is reduced to several smaller space vectors till the three nearest vector are found. Based in the αß stationary coordinates the algorithm present a generalization of overmodulation methods for a linear n-step operation mode.
    01/2011;
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    ABSTRACT: The present paper deals with the study of the harmonic injection technique, with the objective of avoiding acoustics resonance, in high-pressure sodium lamps (HPS) of 70 W, when supplied by electronic ballast. A prototype of a three level full bridge PWM electronic ballast was developed which allows the injection of harmonics in the voltage supplied to the 70 W HPS lamp. The design procedure and results of the inverter used in ballast are then presented. The dimensioning of the resonant circuit for the lamp ignition, based on the voltage beating technique is made. These techniques allow the control of the current crest factor other than rejecting the AR.
    Power Electronics Conference (COBEP), 2011 Brazilian; 01/2011
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    ABSTRACT: The present paper deals with the study of the harmonic injection technique, with the objective of avoiding acoustics resonance, in high-pressure sodium lamps (HPS) of 70 W, when supplied by electronic ballast. A prototype of a three level full bridge PWM electronic ballast was developed which allows the injection of harmonics in the voltage supplied to the 70 W HPS lamp. The design procedure and results of the inverter used in ballast are then presented. The dimensioning of the resonant circuit for the lamp ignition, based on the voltage beating technique is made. These techniques allow the control of the current crest factor other than rejecting the AR.
    IECON 2011 - 37th Annual Conference on IEEE Industrial Electronics Society; 01/2011
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    ABSTRACT: This paper presents a procedure for high-level programming of a microcontroller using passivity-based control implemented in PFC (Power Factor Correction) boost converters. This is a non-conventional approach, where libraries are used to directly interface with the Texas's DSP 2812. Initially, the block diagrams that contain the control equations are constructed. Then, the codes are generated automatically. The advantages provided by the proposed method are: economy of development cycle time, easy understanding of the control process and programming, standardization and concurrent simulation. The other contribution of the paper refers to the development of a regulated source with high power factor and low THD using a boost converter controlled via passivity-based method. The approach based on passivity has been studied recently due to clear advantages in view of disturbances in the operation conditions of the system. The purpose of this technique is to improve the converter efficiency in applications of low and medium power, and improve the quality of the energy in the grid. Finally, in a new and satisfactory way, this nonlinear control technique has been validated experimentally for boost converters.
    Power Electronics Conference (COBEP), 2011 Brazilian; 01/2011
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    ABSTRACT: Light emitting diodes (LEDs) have many features that make them very attractive for use in lighting. The main features that stand out is its small size compared to incandescent and fluorescent lamps. Also, they have high luminous efficiency, long lifetime and are resistant to shocks and vibrations, which contributes to increasing their reliability. This paper presents a current source for Power LEDs. As the luminous intensity of LEDs is directly related to the direct current flowing through them, this source must have characteristics of current source. Two methods of dimming LEDs are analyzed: continuous variation of current and pulse width modulation (PWM). These methods are implemented, tested and compared. A current loop to control the current through the LEDs is designed to keep the current in the LEDs always constant, so that the luminous flux emitted by them does not change.
    Power Electronics Conference (COBEP), 2011 Brazilian; 01/2011
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    ABSTRACT: The control of the current distribution in a two leg interleaved inverter is analyzed in this paper. Feedback is used in order to control the current distribution on the inverter legs, avoiding the use of bulky and costly passive solutions. Low THD in the output voltage is ensured by a PI compensator and a repetitive controller. The design of the current compensators was accomplished by approximating the system to two SISO systems. It is shown that this method is feasible if the output voltage is decoupled by using output voltage decoupling. Good experimental results were achieved in a two leg 4kVA inverter operating at 7680Hz. They showed that the benefits of interleaving are not highly affected by using distinct modulator signals provided that the differences between the legs parameters are small.
    IECON 2010 - 36th Annual Conference on IEEE Industrial Electronics Society; 12/2010
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    ABSTRACT: This paper presents a methodology for choosing the most suitable Maximum Power Point Tracking - MPPT for charging the batteries of an autonomous photovoltaic energy supply system. Experimental results are provided.
    Industrial Technology (ICIT), 2010 IEEE International Conference on; 04/2010
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    ABSTRACT: In this paper, small-signal stability issues of low-voltage parallel-connected voltage source inverters without control interconnections are addressed by means of dynamic analysis and experimentations. The studies performed showed that the parallel system damping is severely reduced when the traditional droop method is employed and the cabling is long. This paper proposes the application of the PSS (Power System Stabilizer) action to the control of parallel inverters in order to increase the stability range concerning the connection impedance composition R/X. It is shown that the PSS action can significantly improve the system damping. Experimental results for two 1kVA inverters in parallel sharing a common load are presented and corroborate the presented ideas.
    01/2010;
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    ABSTRACT: The low frequency ripple in single-phase power factor correction (PFC) boost converters dramatically limits the bandwidth in standard control strategies, deteriorating the overall system performance. This paper presents the study and the implementation of a phase-locked loop (PLL)-based repetitive controller in order to improve the dynamics and the input current distortion in a PFC boost converter. The repetitive control applied to the PFC presents a straightforward implementation with satisfactory results when compared to other techniques, as described in the paper. Experimental results validate this claim.
    Power Electronics Conference, 2009. COBEP '09. Brazilian; 11/2009
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    ABSTRACT: Acoustic resonance in HPS lamps can be avoided by using a controlled PWM inverter and third harmonic injection. The crest factor can also be reduced by harmonic injection. This paper proposes to use of the modulation index adjustment as a method of eliminating the transformer at the output of the ballast as well as maintaining the lamp nominal power during its lifetime. An ignitor for high-intensity discharge lamps based on forced oscillation via an external periodic voltage square wave supplied by a digitally controlled inverter is also presented.
    Power Electronics and Applications, 2009. EPE '09. 13th European Conference on; 10/2009
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    ABSTRACT: In this paper, small-signal stability issues of parallel-connected voltage source inverters without control interconnections are addressed by means of a multivariable approach. The performed small-signal dynamic analysis showed that the system stability margin is reduced when the composition of the inverter connection impedance is neither purely inductive nor purely resistive, which are two common approximations found in the literature. Based on a multivariable approach, this paper proposes the application of decoupling to the control of parallel inverters in order to increase stability range concerning the connection impedance composition R/X. It is shown that decoupling can lead to good results even without precise knowledge of actual connection impedance R/X. Experimental results are presented and corroborate the presented ideas.
    01/2009;
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    ABSTRACT: The low frequency ripple in single-phase power factor correction (PFC) boost converters dramatically limits the bandwidth in standard control strategies, deteriorating the overall system performance. This paper presents the study and the implementation of a Phase-Locked Loop (PLL)-based repetitive controller in order to improve the dynamics and the input current distortion in a PFC boost converter. The repetitive control applied to the PFC presents a straightforward implementation with satisfactory results when compared to other techniques, as described in the paper. Experimental results validate this claim.
    Industrial Electronics, 2009. IECON '09. 35th Annual Conference of IEEE; 01/2009
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    ABSTRACT: A passivity based control scheme is applied to a buck converter operating as an active power factor corrector. The converter is modeled via an Euler-Lagrange (energy) approach and two control laws are derived from this non linear model: a direct control (using the voltage in the capacitor) and an indirect control (via the current in the inductance current). The resistive load impedance is estimated using an adaptive approach. There is no need to consider the small signal condition as in the case of linearized models. The control laws satisfy a wide range of operation of the converter.
    Control and Modeling for Power Electronics, 2008. COMPEL 2008. 11th Workshop on; 09/2008
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    ABSTRACT: In this paper, the performance assessment of three software single-phase phase-locked loop (PLL) algorithms is carried out by means of dynamic analysis and experimental results. Several line disturbances such as phase-angle jump, voltage sag, frequency step, and harmonics are generated by a DSP together with a D/A converter and applied to each PLL. The actual minus the estimated phase-angle values are displayed, providing a refined method for performance evaluation and comparison. Guidelines for parameters adjustments are also presented. In addition, practical implementation issues such as computational delay effects, ride-through, and computational load are addressed. The developed models proved to accurately represent the PLLs under real test conditions.
    IEEE Transactions on Industrial Electronics 09/2008; · 6.50 Impact Factor