Showing papers by "Patricio Cortes published in 2011"

Finite States Model Predictive Control for Shunt Active Filters

Abstract: This paper investigates the application of Model Predictive control to Shunt Active Power Filter (SAF). The converter topology, its analytical modeling and its control implementation are described. To compensate the inherent delay of digital control systems, prediction of relevant variables and reference calculation is performed two steps forward. The proposed approach provides a straightforward and effective single loop solution, with excellent dynamic performance, not requiring grid synchronization or PWM schemes. Significant simulation results are finally reported and commented.

Model predictive control of a three-to-five phase matrix converter

Abstract: The paper proposes model predictive control strategy to control active and reactive power simultaneously in addition to the source and load current using predictive approach for a three-phase input to five-phase output matrix converter. The proposed method selects the actuation states of the matrix converter according to the optimization algorithm of the cost function. The proposed cost function considers the active and reactive input power control to facilitate the control of source side power factor. Additionally source and load side currents are controlled to be sinusoidal. The proposed control approach offer good tracking of the reference and actual source and load current and can control the source side power factor to any value. The analytical and simulation approach is adopted in the paper.

Predictive current control with reduction of switching frequency for three phase voltage source inverters

Abstract: In order to improve the performance at steady state of a three-phase drive system, numerous works have been focused in reducing the current and torque ripple. Predictive current control allows the improvement of the performance by increasing the sampling frequency, but the resulting switching frequency can generate semiconductors operating point out of their thermal limits. The ripple of current using conventional linear current control with pulse width modulation is reduced by increasing the carrier frequency, however, the upper limit of the switching frequency is limited also by the semiconductors thermal rates. In this paper a predictive current control modification is proposed for reducing the switching frequency by decoupling it from the sampling time, thus the performance of the system is improved but the switching frequency is kept bellow its limits. A comparison between the proposed method and linear current control with PWM of a three phase voltage source inverter operating at steady state is presented.

A comparative study of predictive current control for three-phase voltage source inverters based on switching frequency and current error

Abstract: Conventional linear current control with pulse width modulation and predictive current control for a three phase voltage source inverter are compared in this paper based on the ripple of current for a range of switching frequencies. Predictive current control allows to improve the performance by increasing the sampling frequency, but the resulting switching frequency can also make the semiconductors to operate out of their thermal limits. Behavior of the predictive control scheme for a range of switching frequencies is presented. A modification of the predictive current control is presented for decoupling the switching frequency from the sampling frequency, thus the performance of the system is improved and the switching frequency is kept controlled.

Predictive control of a grid-connected cascaded H-bridge multilevel converter

Abstract: A predictive control scheme for a three-phase cascaded h-bridge rectifier is presented. The main objectives of this control scheme is to minimize the error between the input active and reactive power and their references, and to balance the dc-link capacitor voltages. These objectives are expressed as a cost function to be minimized. A model of the converter is used for calculation of the predicted value of the controlled variables for a set of switching states. The switching state that minimizes the cost function is selected and applied. In order to reduce the number of calculations needed to select the optimal state, a method for reduction of the evaluated switching states is also proposed. Results show that the proposed control scheme achieves fast control of the active and reactive power and keeps the capacitor voltages balanced.