DSpace Collection:
http://hdl.handle.net/2117/3834
Mon, 01 Sep 2014 13:21:20 GMT2014-09-01T13:21:20Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoA modified voltage balancing sorting algorithm for the modular multilevel converter: Evaluation for staircase and phase-disposition PWM
http://hdl.handle.net/2117/23161
Title: A modified voltage balancing sorting algorithm for the modular multilevel converter: Evaluation for staircase and phase-disposition PWM
Authors: Darus, Rosheila; Pou Félix, Josep; Konstantinou, Georgios; Ceballos Recio, Salvador; Agelidis, Vassilios
Abstract: This paper introduces a low complexity implementation of the voltage balancing sorting algorithm to reduce the switching frequency of the power devices in modular multilevel converters (MMCs). Two modulation techniques are evaluated; staircase modulation and phase-disposition pulse-width modulation (PD-PWM) under the conventional and the proposed algorithm. Using a circulating current controller in an MMC with 12 sub-modules per arm, PD-PWM yields better results compared to the staircase modulation technique. The test condition for this comparison is such that the power devices operate at a similar switching frequency and produce similar amplitudes to the capacitor voltage ripples in both modulation techniques. The results are verified through extensive simulations and experimentally using a phase-leg MMC laboratory prototype.Thu, 05 Jun 2014 09:20:58 GMThttp://hdl.handle.net/2117/231612014-06-05T09:20:58ZDarus, Rosheila; Pou Félix, Josep; Konstantinou, Georgios; Ceballos Recio, Salvador; Agelidis, VassiliosnoCapacitor voltage balancing, Modular multilevel converter, Modulation technique, Pulse-width modulationThis paper introduces a low complexity implementation of the voltage balancing sorting algorithm to reduce the switching frequency of the power devices in modular multilevel converters (MMCs). Two modulation techniques are evaluated; staircase modulation and phase-disposition pulse-width modulation (PD-PWM) under the conventional and the proposed algorithm. Using a circulating current controller in an MMC with 12 sub-modules per arm, PD-PWM yields better results compared to the staircase modulation technique. The test condition for this comparison is such that the power devices operate at a similar switching frequency and produce similar amplitudes to the capacitor voltage ripples in both modulation techniques. The results are verified through extensive simulations and experimentally using a phase-leg MMC laboratory prototype.Operators to calculate the derivative of digital signals
http://hdl.handle.net/2117/22001
Title: Operators to calculate the derivative of digital signals
Authors: Ferrer Arnau, Luis Jorge; Mon González, Juan; Parisi Baradad, Vicenç
Abstract: This paper presents an FIR operator with a very low computational cost for calculating the first derivative of discrete band-limited signals. The basic idea is to use cubic spline polynomials for interpolating
among the samples and estimate the derivative of the discrete signal as a derivative of the polynomial. This method also allows estimating the derivative at the points between samples. The main contribution of this work is to develop a highly efficient FIR operator with only 9 coefficients for implementing the derivative operator algorithm. The resulting filter can be easily implemented in a microcontroller or an FPGA since only 5 additions and 3 fixed-point multiplications are necessary. If the frequency range of the input signal is between 0 and 0.2 times the sampling frequency (taking 5 samples per cycle), the maximum error in calculating the derivative does not exceed 1.03 %.Wed, 12 Mar 2014 11:22:00 GMThttp://hdl.handle.net/2117/220012014-03-12T11:22:00ZFerrer Arnau, Luis Jorge; Mon González, Juan; Parisi Baradad, VicençnoFirst derivative operator, cubic B-splines, FIR filters, low computational cost, detecting singular points of a discrete signal, DA conversionThis paper presents an FIR operator with a very low computational cost for calculating the first derivative of discrete band-limited signals. The basic idea is to use cubic spline polynomials for interpolating
among the samples and estimate the derivative of the discrete signal as a derivative of the polynomial. This method also allows estimating the derivative at the points between samples. The main contribution of this work is to develop a highly efficient FIR operator with only 9 coefficients for implementing the derivative operator algorithm. The resulting filter can be easily implemented in a microcontroller or an FPGA since only 5 additions and 3 fixed-point multiplications are necessary. If the frequency range of the input signal is between 0 and 0.2 times the sampling frequency (taking 5 samples per cycle), the maximum error in calculating the derivative does not exceed 1.03 %.Decimator filter based on B-splines
http://hdl.handle.net/2117/21852
Title: Decimator filter based on B-splines
Authors: Ferrer Arnau, Luis Jorge; Roset Juan, Francesc Xavier; Mon González, Juan; Parisi Baradad, Vicenç
Abstract: The cascaded integrator-comb (CIC) filters are widely used as decimators in many applications, such
as in delta sigma AD converters to decimate the sampled signal on its output. One problem with these filters is that by increasing its order to improve the signal attenuation in the stop band, worsens the passband response. In this paper we propose a so-called least-squares filters (LSF) based on B-splines to improve that response, compensating for CIC filter drop and flattening the magnitude response of the pass band. We also study the relationship between the CIC filters, otherwise called moving average, and the B-splines expanded by an integer factor. We show that the least-squares filters based on B-splines can be decomposed in CIC filters, with a higher order than the splines used, plus a compensator filter. Another important contribution of this work are the FIR approximations of anti-causal IIR filters needed to implement LSFs.Tue, 04 Mar 2014 16:18:35 GMThttp://hdl.handle.net/2117/218522014-03-04T16:18:35ZFerrer Arnau, Luis Jorge; Roset Juan, Francesc Xavier; Mon González, Juan; Parisi Baradad, VicençnoDecimator filters, Cubic B-splines, Least squares filters, Cascaded integrator-comb filters, AD Sigma delta convertersThe cascaded integrator-comb (CIC) filters are widely used as decimators in many applications, such
as in delta sigma AD converters to decimate the sampled signal on its output. One problem with these filters is that by increasing its order to improve the signal attenuation in the stop band, worsens the passband response. In this paper we propose a so-called least-squares filters (LSF) based on B-splines to improve that response, compensating for CIC filter drop and flattening the magnitude response of the pass band. We also study the relationship between the CIC filters, otherwise called moving average, and the B-splines expanded by an integer factor. We show that the least-squares filters based on B-splines can be decomposed in CIC filters, with a higher order than the splines used, plus a compensator filter. Another important contribution of this work are the FIR approximations of anti-causal IIR filters needed to implement LSFs.A new method to improve the total efficiency of parallel converters
http://hdl.handle.net/2117/21717
Title: A new method to improve the total efficiency of parallel converters
Authors: Hoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José Renes
Abstract: This paper proposes a new methodology for
efficiency optimization in systems composed by parallel
converters. The proposed methodology takes into account
the individual efficiency curves and determines the
optimum operating point for each converter such that
the maximum efficiency of the arrangement is achieved
for the entire load range. Due to the nonlinearity of the
problem and the complexity of the solution hyperplane,
the optimization process is divided into stages of global
optimization, local optimization and ambiguity resolutio
n.
This latter verifies the existence of multiple global
minima and selects the most appropriate in function of
previous power distributions. Case studies demonstrates
the validity of the proposed methodology for different
systems configurations.Mon, 24 Feb 2014 10:41:24 GMThttp://hdl.handle.net/2117/217172014-02-24T10:41:24ZHoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José RenesnoParallel converters
supervisory control
efficiency maximization
photovoltaic systemsThis paper proposes a new methodology for
efficiency optimization in systems composed by parallel
converters. The proposed methodology takes into account
the individual efficiency curves and determines the
optimum operating point for each converter such that
the maximum efficiency of the arrangement is achieved
for the entire load range. Due to the nonlinearity of the
problem and the complexity of the solution hyperplane,
the optimization process is divided into stages of global
optimization, local optimization and ambiguity resolutio
n.
This latter verifies the existence of multiple global
minima and selects the most appropriate in function of
previous power distributions. Case studies demonstrates
the validity of the proposed methodology for different
systems configurations.A simple control strategy to increase the total efficiency of multi-converter systems
http://hdl.handle.net/2117/21712
Title: A simple control strategy to increase the total efficiency of multi-converter systems
Authors: Hoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José Renes
Abstract: This paper presents a simple control
strategy that is employed together with an optimization
methodology to achieve optimal efficiency in systems
composed by multiple parallel converters. An external
loop is responsible for regulating the dc bus voltage
and providing a current reference that is weighted in
function of the power processed by the system, and then
generating optimal current references for each converter.
This enable the system to operate with optimal efficiency
for all its load range. Experimental results demonstrate th
e
superior performance of the proposed strategy, improving
the efficiency of the system in almost
10
% under light load
operation in comparison with the conventional strategy of
equal power sharing among convertersMon, 24 Feb 2014 09:57:49 GMThttp://hdl.handle.net/2117/217122014-02-24T09:57:49ZHoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José RenesnoParallel converters, digital control
efficiency maximization
supervisory control
active
current sharing
photovoltaic systemsThis paper presents a simple control
strategy that is employed together with an optimization
methodology to achieve optimal efficiency in systems
composed by multiple parallel converters. An external
loop is responsible for regulating the dc bus voltage
and providing a current reference that is weighted in
function of the power processed by the system, and then
generating optimal current references for each converter.
This enable the system to operate with optimal efficiency
for all its load range. Experimental results demonstrate th
e
superior performance of the proposed strategy, improving
the efficiency of the system in almost
10
% under light load
operation in comparison with the conventional strategy of
equal power sharing among convertersAnalysis of a voltage balancing technique with reduced switching transitions in a flying capacitor multilevel converter
http://hdl.handle.net/2117/21711
Title: Analysis of a voltage balancing technique with reduced switching transitions in a flying capacitor multilevel converter
Authors: Ghias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, M.
Abstract: This paper reports the analysis of a voltage balancing technique based on optimal switching transitions for a flying capacitor (FC) multilevel converter using phase disposition pulse-width modulation. Since multiple switching transitions between two consecutive voltage levels may be available, such a redundancy is used to regulate the FC voltages at their desired levels. For the selection of the transitions, two techniques are studied and compared in terms of capacitor voltage ripples and switching frequencies. In the first technique, called optimum transition voltage balancing technique, the transitions between two consecutive voltage levels that produce high switching frequencies are avoided. On the other hand, all the transitions between consecutive levels are considered in the second technique. It is therefore called unrestricted voltage balancing technique. Study analyses are conducted by simulation considering all the possible modulation indices and load power factors.Mon, 24 Feb 2014 09:39:05 GMThttp://hdl.handle.net/2117/217112014-02-24T09:39:05ZGhias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, M.noFlying capacitor converter
Multilevel converter
Pulse-width modulation
Switching transition
Voltage controlThis paper reports the analysis of a voltage balancing technique based on optimal switching transitions for a flying capacitor (FC) multilevel converter using phase disposition pulse-width modulation. Since multiple switching transitions between two consecutive voltage levels may be available, such a redundancy is used to regulate the FC voltages at their desired levels. For the selection of the transitions, two techniques are studied and compared in terms of capacitor voltage ripples and switching frequencies. In the first technique, called optimum transition voltage balancing technique, the transitions between two consecutive voltage levels that produce high switching frequencies are avoided. On the other hand, all the transitions between consecutive levels are considered in the second technique. It is therefore called unrestricted voltage balancing technique. Study analyses are conducted by simulation considering all the possible modulation indices and load power factors.Positive- and negative-sequence control of grid-connected photovoltaic systems under unbalanced voltage conditions
http://hdl.handle.net/2117/21710
Title: Positive- and negative-sequence control of grid-connected photovoltaic systems under unbalanced voltage conditions
Authors: Mirhosseini, Mitra; Pou Félix, Josep; Karanayil, Baburaj; Agelidis, Vassilios
Abstract: This paper discusses the control of the positive- and negative-sequence components of a large-scale grid-connected photovoltaic system (GCPS) under unbalanced voltage sag conditions in the grid. Some issues regarding stability and dynamic performance of the system occur when applying PI controllers in the current control loops. The reason is the delay that the filtering method imposes when extracting the current/voltage sequences. Because of such a delay, the dynamic response of the system becomes slower compared with the case when no filtering technique is needed. Furthermore, there is a strong restriction on choosing suitable parameters for the current/voltage loop controllers without compromising system stability. All these issues are discussed in this paper on a 1-MVA GCPV system using MATLAB/Simulink software.Mon, 24 Feb 2014 09:16:51 GMThttp://hdl.handle.net/2117/217102014-02-24T09:16:51ZMirhosseini, Mitra; Pou Félix, Josep; Karanayil, Baburaj; Agelidis, VassiliosnoMoving average filter
Photovoltaic system
Power system dynamics
Power system faultsThis paper discusses the control of the positive- and negative-sequence components of a large-scale grid-connected photovoltaic system (GCPS) under unbalanced voltage sag conditions in the grid. Some issues regarding stability and dynamic performance of the system occur when applying PI controllers in the current control loops. The reason is the delay that the filtering method imposes when extracting the current/voltage sequences. Because of such a delay, the dynamic response of the system becomes slower compared with the case when no filtering technique is needed. Furthermore, there is a strong restriction on choosing suitable parameters for the current/voltage loop controllers without compromising system stability. All these issues are discussed in this paper on a 1-MVA GCPV system using MATLAB/Simulink software.Characterization of conducted emission at high frequency under different temperature
http://hdl.handle.net/2117/21690
Title: Characterization of conducted emission at high frequency under different temperature
Authors: Berbel Artal, Néstor; Fernández García, Raúl; Gil Galí, Ignacio
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In this paper, the characterization of the EMC conducted emissions of integrated circuits under different temperature stress condition, up to 3 GHz is presented. The impact of high temperature has been measured on the input impedance of propagation paths of the electromagnetic conducted emissions, as well as on the electromagnetic noise of a clock generator.Fri, 21 Feb 2014 13:00:35 GMThttp://hdl.handle.net/2117/216902014-02-21T13:00:35ZBerbel Artal, Néstor; Fernández García, Raúl; Gil Galí, IgnacionoEMC, Integrated circuit, conducted emission, switching noise, temperature impactDownload Citation
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In this paper, the characterization of the EMC conducted emissions of integrated circuits under different temperature stress condition, up to 3 GHz is presented. The impact of high temperature has been measured on the input impedance of propagation paths of the electromagnetic conducted emissions, as well as on the electromagnetic noise of a clock generator.PWM algorithm with adaptive offset for three-level multi-phase neutral-point-clamped converters
http://hdl.handle.net/2117/21364
Title: PWM algorithm with adaptive offset for three-level multi-phase neutral-point-clamped converters
Authors: López, Iraide; Ceballos Recio, Salvador; Andreu, Jon; Kortabarria, Iñigo; Pou Félix, Josep
Abstract: This paper proposes a PWM based modulation strategy particularly useful for three-level multi-phase Neutral-Point-Clamped Converters. It achieves similar results to those obtained with the space vector modulation but allowing a very fast and simple implementation in a digital controller. The proposed algorithm is able to maintain the neutral-point voltage under control by the addition of a zero-sequence voltage component to the modulation signals. A simple and efficient methodology to calculate the most appropriate zero-sequence component is described. In addition the modulation strategy is completely general, regardless the number of phases of the converter, and therefore it is easy extendible to n-phase converters.Mon, 27 Jan 2014 08:17:56 GMThttp://hdl.handle.net/2117/213642014-01-27T08:17:56ZLópez, Iraide; Ceballos Recio, Salvador; Andreu, Jon; Kortabarria, Iñigo; Pou Félix, JosepnoThis paper proposes a PWM based modulation strategy particularly useful for three-level multi-phase Neutral-Point-Clamped Converters. It achieves similar results to those obtained with the space vector modulation but allowing a very fast and simple implementation in a digital controller. The proposed algorithm is able to maintain the neutral-point voltage under control by the addition of a zero-sequence voltage component to the modulation signals. A simple and efficient methodology to calculate the most appropriate zero-sequence component is described. In addition the modulation strategy is completely general, regardless the number of phases of the converter, and therefore it is easy extendible to n-phase converters.Interleaved selective harmonic elimination PWM for single-phase rectifiers in traction applications
http://hdl.handle.net/2117/21363
Title: Interleaved selective harmonic elimination PWM for single-phase rectifiers in traction applications
Authors: Konstantinou, Georgios; Agelidis, Vassilios; Pou Félix, Josep
Abstract: Interleaved four-quadrant, single-phase rectifiers are widely used in traction applications as part of an AC-DC-AC conversion system. This paper presents selective harmonic elimination pulse-width modulation (SHE-PWM) patterns for single-phase interleaved PWM rectifiers based on both H-bridges and full-bridge NPCs (H-NPCs). SHE-PWM waveforms are defined so that the low-order harmonics of the combined voltage and input currents on the primary of the supply transformer are eliminated. The formulation of the problem and the acquisition of solutions becomes more challenging as the number of levels in the voltage waveform increases. Solutions based on reduced eliminated harmonics are proposed in order to increase the number of solutions as well as their continuity. It is shown that the proposed formulation improves the available solution space with minimal effect to the output. The theoretical analysis are verified through simulation studies.Mon, 27 Jan 2014 08:10:24 GMThttp://hdl.handle.net/2117/213632014-01-27T08:10:24ZKonstantinou, Georgios; Agelidis, Vassilios; Pou Félix, JosepnoInterleaved converters, multilevel converters, pulse-width modulation (PWM), PWM rectifiers, selective harmonic
elimination (SHE), traction applicationsInterleaved four-quadrant, single-phase rectifiers are widely used in traction applications as part of an AC-DC-AC conversion system. This paper presents selective harmonic elimination pulse-width modulation (SHE-PWM) patterns for single-phase interleaved PWM rectifiers based on both H-bridges and full-bridge NPCs (H-NPCs). SHE-PWM waveforms are defined so that the low-order harmonics of the combined voltage and input currents on the primary of the supply transformer are eliminated. The formulation of the problem and the acquisition of solutions becomes more challenging as the number of levels in the voltage waveform increases. Solutions based on reduced eliminated harmonics are proposed in order to increase the number of solutions as well as their continuity. It is shown that the proposed formulation improves the available solution space with minimal effect to the output. The theoretical analysis are verified through simulation studies.Single-stage inverter-based grid-connected photovoltaic system with ride-through capability over different types of grid faults
http://hdl.handle.net/2117/21358
Title: Single-stage inverter-based grid-connected photovoltaic system with ride-through capability over different types of grid faults
Authors: Mirhosseini, Mitra; Pou Félix, Josep; Agelidis, Vassilios
Abstract: In this paper the control of a single-stage grid-connected photovoltaic power plant (GCPPP) is developed to address the issue of inverter disconnection under various grid faults. There are three main reasons for inverter disconnection which are (i) excessive dc-link voltage, (ii) excessive ac currents and (iii) loss of grid-voltage synchronization. The control of the inverter incorporates reactive power support in the case of voltage sags based on grid code requirements to ride-through the faults and support the grid voltages. Accordingly, another requirement of the grid codes is to control the reactive current injection under unbalanced voltage sags so that the voltages in the non-faulty phases do not exceed the specified limitations. All these issues are discussed in this paper for a case study of 1-MVA GCPPP using MATLAB/Simulink. The results illustrate the capability of the developed GCPPP to ride-through different types of faults occurred on the grid side.Fri, 24 Jan 2014 11:36:54 GMThttp://hdl.handle.net/2117/213582014-01-24T11:36:54ZMirhosseini, Mitra; Pou Félix, Josep; Agelidis, VassiliosnoFault-ride-through, Large-scale systems, Photovoltaic systems, Power system faults, Reactive power supportIn this paper the control of a single-stage grid-connected photovoltaic power plant (GCPPP) is developed to address the issue of inverter disconnection under various grid faults. There are three main reasons for inverter disconnection which are (i) excessive dc-link voltage, (ii) excessive ac currents and (iii) loss of grid-voltage synchronization. The control of the inverter incorporates reactive power support in the case of voltage sags based on grid code requirements to ride-through the faults and support the grid voltages. Accordingly, another requirement of the grid codes is to control the reactive current injection under unbalanced voltage sags so that the voltages in the non-faulty phases do not exceed the specified limitations. All these issues are discussed in this paper for a case study of 1-MVA GCPPP using MATLAB/Simulink. The results illustrate the capability of the developed GCPPP to ride-through different types of faults occurred on the grid side.Voltage balancing method for a seven-level stacked multicell converter using minimum-switching transitions
http://hdl.handle.net/2117/21357
Title: Voltage balancing method for a seven-level stacked multicell converter using minimum-switching transitions
Authors: Ghias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, Mihai
Abstract: This paper presents a voltage balancing method for stacked multicell converters based on phase disposition pulse-width modulation. This method is based on minimizing a cost function to determine the optimum redundant state for capacitor voltage balance for each particular voltage level. The robustness of the proposed voltage balancing method is verified against static and dynamic unbalanced load conditions. Furthermore, a significant reduction in the switching frequencies of the power devices is achieved by using sawtooth carriers instead of standard triangular carriers without affecting the voltage balancing capability.Fri, 24 Jan 2014 11:21:50 GMThttp://hdl.handle.net/2117/213572014-01-24T11:21:50ZGhias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, MihainoMultilevel converter, Stacked multicell converter, Capacitor voltage balancing, Pulse-width modulation.This paper presents a voltage balancing method for stacked multicell converters based on phase disposition pulse-width modulation. This method is based on minimizing a cost function to determine the optimum redundant state for capacitor voltage balance for each particular voltage level. The robustness of the proposed voltage balancing method is verified against static and dynamic unbalanced load conditions. Furthermore, a significant reduction in the switching frequencies of the power devices is achieved by using sawtooth carriers instead of standard triangular carriers without affecting the voltage balancing capability.Optimum state voltage balancing method for stacked multicell converters
http://hdl.handle.net/2117/21356
Title: Optimum state voltage balancing method for stacked multicell converters
Authors: Ghias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, Mihai
Abstract: This paper presents a voltage balancing method for stacked multicell converters based on phase disposition pulse-width modulation. This method is based on minimizing a cost function to determine the optimum redundant state for capacitor voltage balance for each particular voltage level. The robustness of the proposed voltage balancing method is verified against static and dynamic unbalanced load conditions. Furthermore, a significant reduction in the switching frequencies of the power devices is achieved by using sawtooth carriers instead of standard triangular carriers without affecting the voltage balancing capability.Fri, 24 Jan 2014 11:14:00 GMThttp://hdl.handle.net/2117/213562014-01-24T11:14:00ZGhias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, MihainoMultilevel converter, Stacked multicell converter, Capacitor voltage balancing, Pulse-width modulationThis paper presents a voltage balancing method for stacked multicell converters based on phase disposition pulse-width modulation. This method is based on minimizing a cost function to determine the optimum redundant state for capacitor voltage balance for each particular voltage level. The robustness of the proposed voltage balancing method is verified against static and dynamic unbalanced load conditions. Furthermore, a significant reduction in the switching frequencies of the power devices is achieved by using sawtooth carriers instead of standard triangular carriers without affecting the voltage balancing capability.Voltage balancing method using phase-shifted PWM for stacked multicell converters
http://hdl.handle.net/2117/21355
Title: Voltage balancing method using phase-shifted PWM for stacked multicell converters
Authors: Ghias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, Mihai
Abstract: This paper proposes an active voltage balancing method for stacked multicell converters (SMC) using phase-shifted pulse-width modulation, which is easy to implement and extend to high number of levels. The proposed method balances the voltages of the capacitors by modifying the duty cycle of each switch of the SMC using a proportional controller. The crossed effect between capacitor currents and duty cycles is considered and is used for optimal capacitor voltage balance. The performance of the proposed voltage balancing method is verified by simulation for different operating conditions, such as unbalanced linear loads, non-linear loads and load transients.Fri, 24 Jan 2014 11:08:12 GMThttp://hdl.handle.net/2117/213552014-01-24T11:08:12ZGhias, Amer M.Y.M; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, MihainoMultilevel converter, Stacked multicell converter, Capacitor voltage balancing, Pulse-width modulation.This paper proposes an active voltage balancing method for stacked multicell converters (SMC) using phase-shifted pulse-width modulation, which is easy to implement and extend to high number of levels. The proposed method balances the voltages of the capacitors by modifying the duty cycle of each switch of the SMC using a proportional controller. The crossed effect between capacitor currents and duty cycles is considered and is used for optimal capacitor voltage balance. The performance of the proposed voltage balancing method is verified by simulation for different operating conditions, such as unbalanced linear loads, non-linear loads and load transients.Evaluation of DC-link decoupling using electrolytic or polypropylene film capacitors in three-phase grid-connected photovoltaic inverters
http://hdl.handle.net/2117/21354
Title: Evaluation of DC-link decoupling using electrolytic or polypropylene film capacitors in three-phase grid-connected photovoltaic inverters
Authors: Karanayil, Baburaj; Agelidis, Vassilios; Pou Félix, Josep
Abstract: The life expectancy and long term reliability of grid-connected three-phase photovoltaic (PV) inverters can be increased by replacing the conventional electrolytic film capacitors by metallized polypropylene film capacitors. This paper presents a detailed evaluation of a three-phase grid-connected PV inverter performance when replacing the electrolytic capacitor with a minimum value of metallized polypropylene film capacitor-one. The minimum dc bus capacitance leads to larger voltage ripples. However, such ripples were found to be within acceptable limits to run the inverter satisfactorily. Simulation results are presented for a 15-kW grid-connected inverter at nominal voltage of 700V dc and experimental results are provided for a 3.0-kW system at a nominal voltage of 400V dc, built in the laboratory.Fri, 24 Jan 2014 10:51:34 GMThttp://hdl.handle.net/2117/213542014-01-24T10:51:34ZKaranayil, Baburaj; Agelidis, Vassilios; Pou Félix, JosepnoPhotovoltaic systems, grid-connected
inverters, electrolytic capacitorThe life expectancy and long term reliability of grid-connected three-phase photovoltaic (PV) inverters can be increased by replacing the conventional electrolytic film capacitors by metallized polypropylene film capacitors. This paper presents a detailed evaluation of a three-phase grid-connected PV inverter performance when replacing the electrolytic capacitor with a minimum value of metallized polypropylene film capacitor-one. The minimum dc bus capacitance leads to larger voltage ripples. However, such ripples were found to be within acceptable limits to run the inverter satisfactorily. Simulation results are presented for a 15-kW grid-connected inverter at nominal voltage of 700V dc and experimental results are provided for a 3.0-kW system at a nominal voltage of 400V dc, built in the laboratory.