Modulated predictive control for indirect matrix converter

Finite State Model Predictive Control (MPC) has been recently applied to several converter topologies as it can provide many advantages over other MPC techniques. The advantages of MPC include fast dynamics, multi-target control capability and relatively easy implementation on digital control platforms. However, its inherent variable switching frequency and lower steady state waveform quality, with respect to standard control which includes an appropriate modulation technique, represent a limitation to its applicability. Modulated Model Predictive Control (M2PC) combines all the advantages of MPC with the fixed switching frequency characteristic of PWM algorithms. The work presented in this paper focuses on the Indirect Matrix Converter (IMC), where the tight coupling between rectifier stage and inverter stage has to be taken into account in the M2PC design. This paper proposes an M2PC solution, suitable for IMC, with a switching pattern which emulates the desired waveform quality features of Space Vector Modulation (SVM) for matrix converters. The switching sequences of the rectifier stage and inverter stage are rearranged in order to always achieve zero-current switching on the rectifier stage, thus simplifying the current commutation strategy

Predictive control for active split DC-bus 4-leg inverters

This paper proposes a Predictive Control, formally Dead-Beat (DBC), for a four-leg inverter having an Active Split DC-bus on the fourth leg and LC filters on phase-to-neutral outputs. Such a configuration permits to reduce the voltage ripple on the neutral point connected to inverter grounding. As only few control techniques have been investigated for Active Split DC-bus, the paper proposes to investigate the performance of DBC, which has been widely used for other power electronics applications. The main advantage of DBC over the classical PI or Resonant controller is that no tuning is required for control loop, while obtaining very fast transient response as well it can handle general constrained nonlinear systems with multiple inputs and outputs in a unified and clear manner. These features are highly valuable in power electronic converters used to supply the electrical utility loads in micro-grids. However, one of the main drawback of the DBC is the limited capabilities on harmonics compensations required when supplying unbalanced and non-linear loads. The paper presents continuous-time and discrete-time models of DBC applied to a four-leg VSI with Active Split DC-bus, highlighting the performance through simulation results as well as experimental tests

Torque Ripple Minimization for a Permanent Magnet Synchronous Motor Using a Modified Quasi-Z-Source Inverter

This paper presents a torque ripple minimization method for a permanent magnet synchronous motor (PMSM) drive system that utilizes a modified quasi-Z-source (qZS) inverter. The proposed modified qZS network is designed by adding an extra switching device to the conventional qZS topology and provides a wider range of capabilities for inverter input voltage control, e.g., both step-up and step-down operations. It also allows for modification of the traditional switching sequence selection scheme when using the space vector modulation (SVM) for switching. The provided flexibilities are leveraged to develop a control system that minimizes the torque ripples during PMSM operation while satisfying conventional control objectives such as shaft speed control. The control system is comprised of an input voltage optimization subsystem with the goal of torque ripple minimization, which provides the reference for a cascaded modulated model predictive control subsystem for the modified qZS network control, and a motor side predictive control subsystem. The control system employs a new switching sequence selection scheme for SVM modulation to further reduce PMSM torque ripples. Experimental results are provided to validate the theoretical outcomes

Predictive power control strategy for a Grid-Connected 2L-VSI with fixed switching frequency

In the recent years, model predictive control has been consolidated as a design strategy and an attractive alternative for the control of power electronic devices. This paper proposes an active and reactive power control strategy based on predictive control approach applied to grid-connected renewable energy systems. To accomplish this, a three-phase two-level voltage source inverter based topology is used in combination with a simple and efficient fixed-frequency modulation technique. Results based on a MATLAB/Simulink simulation environment are discussed and the most relevant characteristics of the proposed fixed-frequency predictive control approach are highlighted considering the total harmonic distortion as a figure of merit.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Design of a hysteresis predictive control strategy with engineering application cases

Aplicat embargament des de la data de defensa fins al 31 de juliol de 2022This doctoral thesis exposes the development of a redesigned Predictive Control strategy that uses hysteresis to improve the performance of the controlled systems in different fields of application. The approach may use one of the three hysteresis models presented in this thesis. Moreover, the hysteresis may be used as a modulation stage or as a reference trajectory generator. The first step in the methodology of this research will be to validate the hysteresis dynamic model that will be used within the control scheme. Due to the three exposed hysteresis models have the same constitution , it is assumed that the test of one is enough to guarantee the validation of the other two hysteresis systems. This validation consists on implementing the hysteresis model in an experimental platform to confirm that the model is indeed feasible. Later, it will be seen that this application is within the scope of renewable energies. Once the hysteresis model is validated, the proposed strategy is developed. This is an Adaptive-Predictive control scheme with a modulation stage for the control signal. This stage employs hysteresis to improve the functioning of the adaptive phase and in general the entire closed-loop performance. lt will be shown how the use of this modulation scenario salves the parametric drift problem commonly present in some adaptive based controlled systems. Additionally, a fault detection system within the Adaptive-Predictive control scheme is also proposed and validated through a numerical simulation. Furthermore, it will be seen how the hysteresis also can be used as a model to generate the reference trajectory needed to accomplish the control objective. Finally, the proposed strategy is implemented in a varied set of control systems to validate it. These control systems are: a nonlinear Van der Poi oscillator, a nonlinear base-isolated system, a DC-DC buck converter, and a single-phase inverter.Esta tesis doctoral expone el desarrollo de una estrategia de Control Predictivo rediseñada que utiliza histéresis para mejorar el rendimiento de los sistemas controlados en diferentes campos de aplicación. Este esquema de control puede utilizar uno de los tres sistemas de histéresis presentados en esta tesis. Además, la histéresis se puede utilizar como etapa de modulación o como generador de trayectorias de referencia. El primer paso en la metodología de esta investigación será validar el modelo dinámico de histéresis que se utilizará dentro del esquema de control. Debido a que los tres modelos de histéresis expuestos tienen la misma constitución, se asume que la prueba de uno es suficiente para garantizar la validación de los otros dos modelos de histéresis. Esta validación consiste en implementar el modelo de histéresis en una plataforma experimental para confirmar que este es realmente factible. Posteriormente, se verá que esta aplicación está dentro del ámbito de las energias renovables. Una vez validado el modelo de histéresis, se desarrolla la estrategia propuesta. Es decir, un esquema de control Adaptativo-Predictivo con una etapa de modulación para la señal de control. Esta etapa emplea histéresis para mejorar el funcionamiento de la fase adaptativa y, en general, de todo el rendimiento del sistema en lazo cerrado. Se mostrará cómo el uso de este etapa de modulación resuelve el problema de la deriva paramétrica comúnmente presente en algunos sistemas basados en control adaptativo. Adicionalmente, también se propone y valida un sistema de detección de fallos dentro del esquema de control Adaptativo-Predictivo mediante una simulación numérica. Además, se verá cómo la histéresis también se puede utilitzar como modelo para generar la trayectoria de referencia necesaria para lograr el objetivo de control. Finalmente, la estrategia propuesta se implementa en un conjunto variado de sistemas de control para validarla. Estos sistemes de control son: un oscilador Van der Poi no lineal, un sistema no lineal de base aisladora, un convertidor Buck DC-DC y un inversor monofásico.Postprint (published version

Multilevel Converters: An Enabling Technology for High-Power Applications

| Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.Ministerio de Ciencia y Tecnología DPI2001-3089Ministerio de Eduación y Ciencia d TEC2006-0386

Back-to-back Converter Control of Grid-connected Wind Turbine to Mitigate Voltage Drop Caused by Faults

Power electronic converters enable wind turbines, operating at variable speed, to generate electricity more efficiently. Among variable speed operating turbine generators, permanent magnetic synchronous generator (PMSG) has got more attentions due to low cost and maintenance requirements. In addition, the converter in a wind turbine with PMSG decouples the turbine from the power grid, which favors them for grid codes. In this paper, the performance of back-to-back (B2B) converter control of a wind turbine system with PMSG is investigated on a faulty grid. The switching strategy of the grid side converter is designed to improve voltage drop caused by the fault in the grid while the maximum available active power of wind turbine system is injected to the grid and the DC link voltage in the converter is regulated. The methodology of the converter control is elaborated in details and its performance on a sample faulty grid is assessed through simulation

Harmonics Mitigation and Non-Ideal Voltage Compensation Utilizing Active Power Filter Based On Predictive Current Control

It is well-known that the presence of non-linear loads in the distribution system can impair the power quality. The problem becomes worse in microgrids and power electronic-based power systems as the increasing penetration of single-phase distributed generation may result in a more unbalanced grid voltage. Shunt active power filters (SAPFs) are used for improving the power quality and compensating for the unbalance grid voltage. This study presents a modification of the classical control structure based on the finite control set model predictive control (FCS-MPC). The proposed control structure can retain all the advantages of FCS-MPC, while improving the input current quality. Furthermore, a computationally efficient cost function based on only a single objective is introduced, and its effect on reducing the current ripple is demonstrated. The presented solution provides a fast response to the transients as well as compensates for the unbalanced grid voltage conditions. A straightforward single loop controller is compared to the conventional way of realising the active power filters, which is based on space vector pulse width modulation. The simulation results have been obtained from MATLAB/SIMULINK environment, while the obtained experimental results, utilising a 15 kVA power converter, highlight the effective performance of the proposed control scheme and verifies the introduced MPC-based method as a viable control solution for SAPFs