This work presents a three-phase harmonics measurement method based on the mSDFT (Modulated Slidi... more This work presents a three-phase harmonics measurement method based on the mSDFT (Modulated Sliding Discrete Fourier Transform) and a variable sampling period technique. The proposal allows measuring the harmonic components of a three-phase signal and computes the corresponding imbalance by estimating its positive, negative and zero sequence. In addition, an adaptive variable sampling period is used in order to obtain a sampling frequency multiple of the main frequency. mSDFT high rejection to distortions in the electrical network and flexibility of proposed method makes it an interesting alternative for the design of grid power monitors.
2017 XVII Workshop on Information Processing and Control (RPIC)
OFDM (Orthogonal Frequency-Division Multiplexing) is one of the most used digital schemes at the ... more OFDM (Orthogonal Frequency-Division Multiplexing) is one of the most used digital schemes at the moment. Conventionaly, OFDM uses inverse Fast Fourier transforms and Fast Fourier Transforms (IFFT/FFT) at the transmitter and receiver to modulate and demodulate data. This work analyses different alternatives to the use of these IFFT/FFT of OFDM systems by replacing them with Discrete Cosine Transform (DCT) blocks. This results in lower computational requirements, mainly due to the use of real arithmetic operations instead of complex operations, and higher information rates, shown in simulations.
2017 XVII Workshop on Information Processing and Control (RPIC)
A new type of linear-programming based Model Predictive Control (LP-MPC) is presented in this wor... more A new type of linear-programming based Model Predictive Control (LP-MPC) is presented in this work. The MPC optimization process is reformulated as a linear programming problem and solved using the Simplex method. The optimization result is the duty cycle of a fixed-frequency pulse width modulator (PWM) which switches the transistors of a three-phase grid-connected voltage source inverter. In opposition to other LP-MPC formulations, the optimization is carried out online. In order to validate the proposal, a comparison with a Generalized Predictive Control (GPC) algorithm is made through simulations. Results show a better performance of the proposed strategy in different non ideal scenarios.
Abstract Almost all synchronization methods that can be found in the literature are based on a fi... more Abstract Almost all synchronization methods that can be found in the literature are based on a fixed sampling period approach and implemented by the addition of filter stages to the conventional Synchronous Reference Frame Phase Locked Loop (SRF-PLL) structure. A less common approach is the variable sampling period (VSP), used in methods like VSP-PLL. These methods allow implementing a synchronous sampling period which automatically adapts the monitoring and control systems to the grid voltage and current, improving their processing performance. Notwithstanding the advantages of the synchronous sampling period approach, this operation principle is not commonly adopted in the literature since a proper design is required to avoid implementation problems and possible conflicts with other modules. This manuscript reviews the advantages of VSP approach, unveils similarities between VSP-PLL and SRF-PLL that allow improving the understanding of the former by comparing it to the latter, and provides guidelines for a proper implementation of a synchronous sampling method. In addition, a Hybrid Sampling Period (HSP) approach that combines the advantages of SRF-PLL and VSP-PLL is proposed. The three approaches are compared, the advantages of hybrid methods are discussed and the methodology for adopting the VSP and HSP approach in most fixed sampling period method is presented. Finally, the proposal is verified by experimental implementation.
2016 IEEE Biennial Congress of Argentina (ARGENCON), 2016
In the context of broadband Power Line Communications (PLC), this work proposes an estimation and... more In the context of broadband Power Line Communications (PLC), this work proposes an estimation and equalization method for block-pilot OFDM systems. The proposal is based on the correlation properties of Complementary Sequences (CS), performing all the operations in the frequency domain, which allows to reduce communication errors and the overall computational effort. The performance of the method is compared with other approaches, as the Least-Squares (LS) and Linear Minimum Mean-Square Error (LMMSE). Simulations were performed by using two realistic PLC channels, as well as additive white Gaussian noise (AWGN) and diverse configurations of impulse noise (IN) modeled by Middleton Class A distribution (MCA). Results are reported as Bit Error-Rate (BER) graphs, showing that the proposal produces better results than LS, approaching to the good performance of LMMSE but with lower computational requirements.
2016 IEEE Biennial Congress of Argentina (ARGENCON), 2016
This paper presents a self tuning robust predictive current controller that can be applied to bot... more This paper presents a self tuning robust predictive current controller that can be applied to both single and three phase grid tie voltage source inverters. Due to its adaptive capability, this control has a great robustness to paremetric variations, presents low steady-state current error and lowers dead time distortion in contrast with its nonadaptive variant (RPCC). Both simulation and experimental results were carried out in order to asses the proposed technique.
2016 Argentine Conference of Micro-Nanoelectronics, Technology and Applications (CAMTA), 2016
Power converters that operate in Discontinuous Conduction Mode (DCM) are able to reduce switching... more Power converters that operate in Discontinuous Conduction Mode (DCM) are able to reduce switching losses, when compared to Continuous Conduction Mode (CCM) operation. This reduction is mainly due to zero current commutation and the reduction of the reverse recovery losses. However, DCM operation in high power converters is limited due to the increment in current ripple, which increases losses and volume in the differential mode (DM) filter. Multiphase DCM power converters can reduce total ripple by dividing total current among N phases and interleaving its ripples. Nevertheless, magnitude of ripple reduction as a function of the system parameters has not yet been completely determined. This information would be an important performance indicator and a useful tool for aiding in the design of key converter features, such as the number of phases and DM filter design, in order to meet total ripple, losses or electromagnetic interference specifications. In this sense, this paper proposes a methodology for the steady state characterization of input and output ripple in both buck and boost converters operating in DCM. Experimental tests on a 4-phase buck converter validate the proposal.
IEEE Transactions on Instrumentation and Measurement, 2016
This paper presents a three-phase harmonic and sequence components measurement method based on mo... more This paper presents a three-phase harmonic and sequence components measurement method based on modulated sliding discrete Fourier transform (mSDFT) and a variable sampling period technique. The proposal allows measuring the harmonic components of a three-phase signal and computes the corresponding imbalance by estimating the instantaneous symmetrical components. In addition, an adaptive variable sampling period is used to obtain a sampling frequency multiple of the main frequency. By doing so, DFT typical errors, known as spectral leakage and picket-fence effect, are mitigated in steady state. The proposal is tested with different disturbances by simulation and experimental results. Some results obtained with a power quality monitor implemented with the proposed system are also presented. The high rejection to distortion in the electrical network, frequency adaptability, flexibility, and good performance in power quality monitor application render the proposed method a promising alternative for signal processing from the mains.
2015 XVI Workshop on Information Processing and Control (RPIC), 2015
This work presents a topology for a pulsed current power supply suitable for particle accelerator... more This work presents a topology for a pulsed current power supply suitable for particle accelerator applications. The current pulse is generated from the energy provided by a structure tied to the electrical network and by one connected to a capacitor bank; which is used as local energy storage. By using both structures, disturbances on the electrical network are minimized, since the power obtained from the grid is limited to the average active power of the load; while the management of the reactive power lies on the energy storage structure. A control scheme for the power management of both structures is presented, and simulations are carried out taking into account the parameters of a particle accelerator transfer line.
2015 XVI Workshop on Information Processing and Control (RPIC), 2015
Multicarrier schemes, like OFDM, provide several advantages for channel estimation and equalizati... more Multicarrier schemes, like OFDM, provide several advantages for channel estimation and equalization in many communication systems. Channel estimators, like LMMSE (linear minimum mean-square error) have proven to be very effective, however, they are not feasible to be implemented in real time due to its computational requirements. This work proposes a Power Line Communication (PLC) channel estimator based on the mathematical properties of Complementary Sequences (CS). The proposal is implemented on a BPSK-OFDM scheme, and all the signal processing is made on the frequency domain. Simulations were performed by using two characteristic PLC channels with Additive White Gaussian Noise (AWGN) as well as impulse noises. Results, reported as Mean Square Error (MSE) and Bit Error-rate (BER) shows that the proposal provide best results than least squares (LS) method and a similar performance than the observed in LMMSE, mainly under impulse noises, with the main advantage of using least computational resources.
CONICET Resumen— En este trabajo se investiga el uso de muestreo caótico para adquirir s nales de... more CONICET Resumen— En este trabajo se investiga el uso de muestreo caótico para adquirir s nales de baja frecuencia inmersas en ruido de alta frecuencia. El método reduce el aliasing sin utilizar los típicos filtros antialiasing. Se realizan simulaciones con varios ma-pas caóticos que poseen diferente función densidad de probabilidad invariante (IPDF) y diferente constante de tiempo de evolución en el espacio de las funciones densidad de probabilidad (PDF). Se reportan resulta-dos con diferentes tipos de filtros de respuesta finita al impulso (FIR) y se los compara con los obtenidos en trabajos previos con muestreo aleatorio. P alabras Clave— caos, mapas iterados, gener-adores pseudoaleatorios, jitter random sampling. I. INTRODUCC ON Varios autores han tratado el tema del muestreo no periódico como por ejemplo Beutler (1970); Bilinskis y Mikelsons (1992); Carrica et al. (2001, 2007); Balakr-ishnan (1962); Tarczynski (2001); Mirri et al. (1998); DaDalt et al. (2002). En especial el mue...
This work presents a new approach for teaching power converters through the use of power inverter... more This work presents a new approach for teaching power converters through the use of power inverter example experiments. This scheme is based on a custom-designed hardware and a software platform based on several open-source tools. The platform is controlled by a 32-bit microprocessor which gives the student the possibility to modify the experiments through the control firmware. All the required hardware and software necessary to design and implement the control is open-source.
En este trabajo se propone un método para reducir el ripple en sistemas de potencia que utilicen ... more En este trabajo se propone un método para reducir el ripple en sistemas de potencia que utilicen PWM aleatorio. El controlador feedforward propuesto sigue la composición de la secuencia de conmutación para establecer una óptima secuencia según una cota pre-establecida para el ciclo de trabajo. Se muestran resultados de simulación los que son contrastados con las contribuciones de otros autores, verificándose una importante reducción en los niveles de ripple. newline Abstract: (English): In this work a new method is proposed to reduce ripple in power systems that use random PWM. The feedforward controller proposed tracks the commutation sequence in order to produce an optimal sequence according to a pre-established delta level for the current duty cycle. Simulation results are then obtained and contrasted with other authors contributions; an important reduction in the ripple level is obtained using the controller.
This paper proposes a novel stepper motor controller based on Field Programable Gate Arrays, show... more This paper proposes a novel stepper motor controller based on Field Programable Gate Arrays, showing a remarkable performance. The system provides a combination between a novel algorithm developed by the authors in a previous work and programmable logic to achieve both high speed and high precision on a compact hardware.
This work presents a three-phase harmonics measurement method based on the mSDFT (Modulated Slidi... more This work presents a three-phase harmonics measurement method based on the mSDFT (Modulated Sliding Discrete Fourier Transform) and a variable sampling period technique. The proposal allows measuring the harmonic components of a three-phase signal and computes the corresponding imbalance by estimating its positive, negative and zero sequence. In addition, an adaptive variable sampling period is used in order to obtain a sampling frequency multiple of the main frequency. mSDFT high rejection to distortions in the electrical network and flexibility of proposed method makes it an interesting alternative for the design of grid power monitors.
2017 XVII Workshop on Information Processing and Control (RPIC)
OFDM (Orthogonal Frequency-Division Multiplexing) is one of the most used digital schemes at the ... more OFDM (Orthogonal Frequency-Division Multiplexing) is one of the most used digital schemes at the moment. Conventionaly, OFDM uses inverse Fast Fourier transforms and Fast Fourier Transforms (IFFT/FFT) at the transmitter and receiver to modulate and demodulate data. This work analyses different alternatives to the use of these IFFT/FFT of OFDM systems by replacing them with Discrete Cosine Transform (DCT) blocks. This results in lower computational requirements, mainly due to the use of real arithmetic operations instead of complex operations, and higher information rates, shown in simulations.
2017 XVII Workshop on Information Processing and Control (RPIC)
A new type of linear-programming based Model Predictive Control (LP-MPC) is presented in this wor... more A new type of linear-programming based Model Predictive Control (LP-MPC) is presented in this work. The MPC optimization process is reformulated as a linear programming problem and solved using the Simplex method. The optimization result is the duty cycle of a fixed-frequency pulse width modulator (PWM) which switches the transistors of a three-phase grid-connected voltage source inverter. In opposition to other LP-MPC formulations, the optimization is carried out online. In order to validate the proposal, a comparison with a Generalized Predictive Control (GPC) algorithm is made through simulations. Results show a better performance of the proposed strategy in different non ideal scenarios.
Abstract Almost all synchronization methods that can be found in the literature are based on a fi... more Abstract Almost all synchronization methods that can be found in the literature are based on a fixed sampling period approach and implemented by the addition of filter stages to the conventional Synchronous Reference Frame Phase Locked Loop (SRF-PLL) structure. A less common approach is the variable sampling period (VSP), used in methods like VSP-PLL. These methods allow implementing a synchronous sampling period which automatically adapts the monitoring and control systems to the grid voltage and current, improving their processing performance. Notwithstanding the advantages of the synchronous sampling period approach, this operation principle is not commonly adopted in the literature since a proper design is required to avoid implementation problems and possible conflicts with other modules. This manuscript reviews the advantages of VSP approach, unveils similarities between VSP-PLL and SRF-PLL that allow improving the understanding of the former by comparing it to the latter, and provides guidelines for a proper implementation of a synchronous sampling method. In addition, a Hybrid Sampling Period (HSP) approach that combines the advantages of SRF-PLL and VSP-PLL is proposed. The three approaches are compared, the advantages of hybrid methods are discussed and the methodology for adopting the VSP and HSP approach in most fixed sampling period method is presented. Finally, the proposal is verified by experimental implementation.
2016 IEEE Biennial Congress of Argentina (ARGENCON), 2016
In the context of broadband Power Line Communications (PLC), this work proposes an estimation and... more In the context of broadband Power Line Communications (PLC), this work proposes an estimation and equalization method for block-pilot OFDM systems. The proposal is based on the correlation properties of Complementary Sequences (CS), performing all the operations in the frequency domain, which allows to reduce communication errors and the overall computational effort. The performance of the method is compared with other approaches, as the Least-Squares (LS) and Linear Minimum Mean-Square Error (LMMSE). Simulations were performed by using two realistic PLC channels, as well as additive white Gaussian noise (AWGN) and diverse configurations of impulse noise (IN) modeled by Middleton Class A distribution (MCA). Results are reported as Bit Error-Rate (BER) graphs, showing that the proposal produces better results than LS, approaching to the good performance of LMMSE but with lower computational requirements.
2016 IEEE Biennial Congress of Argentina (ARGENCON), 2016
This paper presents a self tuning robust predictive current controller that can be applied to bot... more This paper presents a self tuning robust predictive current controller that can be applied to both single and three phase grid tie voltage source inverters. Due to its adaptive capability, this control has a great robustness to paremetric variations, presents low steady-state current error and lowers dead time distortion in contrast with its nonadaptive variant (RPCC). Both simulation and experimental results were carried out in order to asses the proposed technique.
2016 Argentine Conference of Micro-Nanoelectronics, Technology and Applications (CAMTA), 2016
Power converters that operate in Discontinuous Conduction Mode (DCM) are able to reduce switching... more Power converters that operate in Discontinuous Conduction Mode (DCM) are able to reduce switching losses, when compared to Continuous Conduction Mode (CCM) operation. This reduction is mainly due to zero current commutation and the reduction of the reverse recovery losses. However, DCM operation in high power converters is limited due to the increment in current ripple, which increases losses and volume in the differential mode (DM) filter. Multiphase DCM power converters can reduce total ripple by dividing total current among N phases and interleaving its ripples. Nevertheless, magnitude of ripple reduction as a function of the system parameters has not yet been completely determined. This information would be an important performance indicator and a useful tool for aiding in the design of key converter features, such as the number of phases and DM filter design, in order to meet total ripple, losses or electromagnetic interference specifications. In this sense, this paper proposes a methodology for the steady state characterization of input and output ripple in both buck and boost converters operating in DCM. Experimental tests on a 4-phase buck converter validate the proposal.
IEEE Transactions on Instrumentation and Measurement, 2016
This paper presents a three-phase harmonic and sequence components measurement method based on mo... more This paper presents a three-phase harmonic and sequence components measurement method based on modulated sliding discrete Fourier transform (mSDFT) and a variable sampling period technique. The proposal allows measuring the harmonic components of a three-phase signal and computes the corresponding imbalance by estimating the instantaneous symmetrical components. In addition, an adaptive variable sampling period is used to obtain a sampling frequency multiple of the main frequency. By doing so, DFT typical errors, known as spectral leakage and picket-fence effect, are mitigated in steady state. The proposal is tested with different disturbances by simulation and experimental results. Some results obtained with a power quality monitor implemented with the proposed system are also presented. The high rejection to distortion in the electrical network, frequency adaptability, flexibility, and good performance in power quality monitor application render the proposed method a promising alternative for signal processing from the mains.
2015 XVI Workshop on Information Processing and Control (RPIC), 2015
This work presents a topology for a pulsed current power supply suitable for particle accelerator... more This work presents a topology for a pulsed current power supply suitable for particle accelerator applications. The current pulse is generated from the energy provided by a structure tied to the electrical network and by one connected to a capacitor bank; which is used as local energy storage. By using both structures, disturbances on the electrical network are minimized, since the power obtained from the grid is limited to the average active power of the load; while the management of the reactive power lies on the energy storage structure. A control scheme for the power management of both structures is presented, and simulations are carried out taking into account the parameters of a particle accelerator transfer line.
2015 XVI Workshop on Information Processing and Control (RPIC), 2015
Multicarrier schemes, like OFDM, provide several advantages for channel estimation and equalizati... more Multicarrier schemes, like OFDM, provide several advantages for channel estimation and equalization in many communication systems. Channel estimators, like LMMSE (linear minimum mean-square error) have proven to be very effective, however, they are not feasible to be implemented in real time due to its computational requirements. This work proposes a Power Line Communication (PLC) channel estimator based on the mathematical properties of Complementary Sequences (CS). The proposal is implemented on a BPSK-OFDM scheme, and all the signal processing is made on the frequency domain. Simulations were performed by using two characteristic PLC channels with Additive White Gaussian Noise (AWGN) as well as impulse noises. Results, reported as Mean Square Error (MSE) and Bit Error-rate (BER) shows that the proposal provide best results than least squares (LS) method and a similar performance than the observed in LMMSE, mainly under impulse noises, with the main advantage of using least computational resources.
CONICET Resumen— En este trabajo se investiga el uso de muestreo caótico para adquirir s nales de... more CONICET Resumen— En este trabajo se investiga el uso de muestreo caótico para adquirir s nales de baja frecuencia inmersas en ruido de alta frecuencia. El método reduce el aliasing sin utilizar los típicos filtros antialiasing. Se realizan simulaciones con varios ma-pas caóticos que poseen diferente función densidad de probabilidad invariante (IPDF) y diferente constante de tiempo de evolución en el espacio de las funciones densidad de probabilidad (PDF). Se reportan resulta-dos con diferentes tipos de filtros de respuesta finita al impulso (FIR) y se los compara con los obtenidos en trabajos previos con muestreo aleatorio. P alabras Clave— caos, mapas iterados, gener-adores pseudoaleatorios, jitter random sampling. I. INTRODUCC ON Varios autores han tratado el tema del muestreo no periódico como por ejemplo Beutler (1970); Bilinskis y Mikelsons (1992); Carrica et al. (2001, 2007); Balakr-ishnan (1962); Tarczynski (2001); Mirri et al. (1998); DaDalt et al. (2002). En especial el mue...
This work presents a new approach for teaching power converters through the use of power inverter... more This work presents a new approach for teaching power converters through the use of power inverter example experiments. This scheme is based on a custom-designed hardware and a software platform based on several open-source tools. The platform is controlled by a 32-bit microprocessor which gives the student the possibility to modify the experiments through the control firmware. All the required hardware and software necessary to design and implement the control is open-source.
En este trabajo se propone un método para reducir el ripple en sistemas de potencia que utilicen ... more En este trabajo se propone un método para reducir el ripple en sistemas de potencia que utilicen PWM aleatorio. El controlador feedforward propuesto sigue la composición de la secuencia de conmutación para establecer una óptima secuencia según una cota pre-establecida para el ciclo de trabajo. Se muestran resultados de simulación los que son contrastados con las contribuciones de otros autores, verificándose una importante reducción en los niveles de ripple. newline Abstract: (English): In this work a new method is proposed to reduce ripple in power systems that use random PWM. The feedforward controller proposed tracks the commutation sequence in order to produce an optimal sequence according to a pre-established delta level for the current duty cycle. Simulation results are then obtained and contrasted with other authors contributions; an important reduction in the ripple level is obtained using the controller.
This paper proposes a novel stepper motor controller based on Field Programable Gate Arrays, show... more This paper proposes a novel stepper motor controller based on Field Programable Gate Arrays, showing a remarkable performance. The system provides a combination between a novel algorithm developed by the authors in a previous work and programmable logic to achieve both high speed and high precision on a compact hardware.
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