PESC Research Papers - Academia.edu (original) (raw)

This paper proposes a multilevel power conversion concept based on the combination of neutral-point-clamped (NPC) and floating capacitor converters. In the proposed scheme, the voltage balancing across the floating capacitors is achieved... more

This paper proposes a multilevel power conversion concept based on the combination of neutral-point-clamped (NPC) and floating capacitor converters. In the proposed scheme, the voltage balancing across the floating capacitors is achieved by using a proper selection of redundant switching states, and the neutral-point voltage is controlled by the classical dc offset injection. Experimental results are illustrated in the paper to demonstrate the system operation

Fulfilling the new grid codes constitutes one of the main challenges for the wind power industry, that is specially concerned about the new fault-ride-through requirements. Enhancing the operation of wind-turbines in front of grid faults... more

Fulfilling the new grid codes constitutes one of the main challenges for the wind power industry, that is specially concerned about the new fault-ride-through requirements. Enhancing the operation of wind-turbines in front of grid faults is not only an important issue for new wind farms, but also for the existing ones, as, at the present time, the classical squirrel cage

New and stronger power quality requirements are issued due to the increase amount of photovoltaic (PV) installations. In this paper different methods are used for continuous grid monitoring. By injecting a noncharacteristic harmonic... more

New and stronger power quality requirements are issued due to the increase amount of photovoltaic (PV) installations. In this paper different methods are used for continuous grid monitoring. By injecting a noncharacteristic harmonic current and measuring the grid voltage response it is possible to evaluate the grid impedance directly by the PV-inverter, providing a fast and low cost implementation. This principle theoretically provides a correct result of the grid impedance but when using it into the context of PV integration, different implementation issues strongly affect the quality of the results. This paper presents a new impedance estimation method including typical implementation problems encountered and it also presents adopted solutions for on-line grid impedance measurement. Practical tests on an existing PV-inverter validate the chosen solutions.

In this paper a single-switch power supply based on the shunt class E amplifier is presented. A simple and easy method to analyze the complete system is proposed and one way to provide compensation to parameter's variation of the ozone... more

In this paper a single-switch power supply based on the shunt class E amplifier is presented. A simple and easy method to analyze the complete system is proposed and one way to provide compensation to parameter's variation of the ozone generator and to reduce the size of the resonant inductor is proposed and studied too. The selected topology offers a low-cost and high-power density source that efficiently supplied the system. Experimental results are congruent with the specifications and a high ozone concentration is obtained.

The output voltage of PWM power inverters shows harmonic distortion due to several causes; the main ones are the modulation algorithm, nonlinearities due to the output filter, dead times, voltage drops across the switches and modulation... more

The output voltage of PWM power inverters shows harmonic distortion due to several causes; the main ones are the modulation algorithm, nonlinearities due to the output filter, dead times, voltage drops across the switches and modulation of the dc bus voltage. The distortion is more evident when using low dc bus voltages. As a result, motors driven by these inverters have important torque pulsations. This work proposes to reduce the distortion produced by dead times and voltage drops across the switches, using a simple algorithm that recalculates the width of each PWM pulse, preserving the ideal area. The algorithm takes advantage of the fact that the dead times are not always necessary, but only when the load current changes its sign. By simulation, the THD was reduced from 18% to 0.29% in a single-phase inverter. The proposed algorithm only needs products and sums, so it is suitable for being implemented on a DSP with low processing load. Experimental results were obtained from a non-optimized laboratory prototype, showing a reduction of the THD from 17.9% to 0.59%.

This paper deals with a flexible production system modeled by re-entrant C; a system decomposed into two fundamental multi-productive stations and three classes, a part follows the route fixed by the system, where each one is processed... more

This paper deals with a flexible production system modeled by re-entrant C; a system decomposed into two fundamental multi-productive stations and three classes, a part follows the route fixed by the system, where each one is processed first by station 1 for the first step, then by station 2 for the second step, and again by the first station for third and last step before leaving the system. We assume that there is an infinite supply of work available, so that there are always parts ready for processing step 1, and that the first station gives preemptive priority to buffer 3. Several performance measures have been used to evaluate the system performances considering two scenarios; high priority with service conservation and high priority with loss of parts. So, performances due to varying its parameters are investigated through expanded Monte Carlo simulations.

In this paper a single-switch voltage regulator is presented. The converter processes the power less than once, resulting in an efficient design. Although the current is not sinusoidal, the proposed converter complies with the Standard... more

In this paper a single-switch voltage regulator is presented. The converter processes the power less than once, resulting in an efficient design. Although the current is not sinusoidal, the proposed converter complies with the Standard IEC 1000-3-2 about low frequency harmonics for a medium power stage. Additionally a fast regulation at the output voltage is obtained due to the fact that sliding mode control is used. Analysis, simulation and experimental results of the converter are presented

The aim of this paper is to propose a current control of VSCs connected to the grid through an LCL-filter. The proposed algorithm controls the grid current using only two sensors. Other variables are obtained with a state estimator, and... more

The aim of this paper is to propose a current control of VSCs connected to the grid through an LCL-filter. The proposed algorithm controls the grid current using only two sensors. Other variables are obtained with a state estimator, and the possible disturbances of the system are attenuated with active damping. The control algorithm has been proved for different disturbances, such as temporal variations in the components of the model and perturbations in the grid, and also with the linear and nonlinear models.

The aim of this paper is to propose a current control of VSCs connected to the grid through an LCL-filter. The proposed algorithm controls the grid current using only two sensors. Other variables are obtained with a state estimator, and... more

The aim of this paper is to propose a current control of VSCs connected to the grid through an LCL-filter. The proposed algorithm controls the grid current using only two sensors. Other variables are obtained with a state estimator, and the possible disturbances of the system are attenuated with active damping. The control algorithm has been proved for different disturbances, such as temporal variations in the components of the model and perturbations in the grid, and also with the linear and nonlinear models.

In this paper a single-switch power supply based on the shunt class E amplifier is presented. A simple and easy method to analyze the complete system is proposed and one way to provide compensation to parameter's variation of the ozone... more

In this paper a single-switch power supply based on the shunt class E amplifier is presented. A simple and easy method to analyze the complete system is proposed and one way to provide compensation to parameter's variation of the ozone generator and to reduce the size of the resonant inductor is proposed and studied too. The selected topology offers a low-cost and high-power density source that efficiently supplied the system. Experimental results are congruent with the specifications and a high ozone concentration is obtained.