Investigation of direct matrix converter working as a versatile converter (AC/AC, AC/DC, DC/AC, DC/DC conversion) with predictive control

© 2017 IEEE. The three-phase direct matrix converter has been researched exclusively as a direct AC/AC converter, being a competitive alternative to the conventional AC/DC/AC converter. Other possibilities of the matrix converter such as AC/DC, DC/AC and DC/DC conversion still remain unexplored. This paper firstly explores these possibilities and puts forward a concept of the versatile converter. With one matrix converter, different conversion purposes can be accomplished as required. The matrix converter based conversion has some advantages compared with other converters. Model predictive control (MPC) is applied in this work to control the matrix converter to perform the required conversion goals. A generalized model is obtained for all types of conversion in this work. With MPC, different objectives and constraints can be easily included in the control scheme. In addition, the observers are used to reduce the number of voltage and current sensors. Simulation results verify the effectiveness and feasibility of AC/DC, DC/AC and DC/DC conversion with the matrix converter

Predictive voltage control of direct matrix converter with reduced number of sensors for the renewable energy and microgrid applications

© 2017 IEEE. This work proposes and investigates a renewable energy distributed generation system involving a matrix converter with an output filter working as a stable voltage supply. This is especially relevant for the stand-alone operation of a renewable energy microgrid where a stable sinusoidal voltage with prescribed amplitude and frequency under various load conditions is the main control objective. A controllable input power factor is preferred. In this paper, the model predictive control is employed to regulate the matrix converter output voltages which in turn are the supply for systems of the following stage. To reduce the number of required measurements and sensors, the work designs observers and makes use of the switch matrix. In addition to the regulation of the sinusoidal output voltages and input power factor, the control scheme deals with the common-mode voltage. The switching frequency is also considered in the controller to reduce the switching losses and keep the average switching frequency constant. In addition, the voltage transfer ratio can be improved at the cost of input current distortion. Supplying DC loads is feasible with this proposed control method. The controller is tested under various conditions including non-linear loads, DC loads and unbalanced input conditions to show it is effective, simple and easy to implement. Simulation results corroborate the effectiveness of the proposed controller and applications

Investigation of Grid-Connected and Islanded Direct Matrix Converter for Renewable Microgrid Applications with Model Predictive Control

© 2018 IEEE. The direct matrix converter has been proposed for many potential applications. However, it remains unexplored within the context of microgrids and distributed generation. This paper investigates the application of the direct matrix converter to these areas. Both the grid-connected and islanded operation modes are explored. Model predictive control is employed to achieve flexible active and reactive power regulation in the grid-connected mode, and stable sinusoidal voltage control in the islanded mode. It is also used to achieve grid voltage synchronization prior to grid connection. Simulation and experimental results verify the feasibility and effectiveness of the direct matrix converter when used in grid-connected and islanded microgrids. When used in the matrix converter-connected microgrid, model predictive control is effective in regulating the voltage and the power exchange with the grid

Control strategies and applications of three-phase direct matrix converters

University of Technology Sydney. Faculty of Engineering and Information Technology.AC-to-AC converters have been widely used in various areas in the real world. In industrial applications, the AC-to-AC power conversion is usually accomplished by indirect converters. In these traditional converters, AC power is firstly converted into DC power by a rectifier, and then the DC power is converted into AC power by an inverter. The rectifier and inverter are usually connected via an intermediate bulky DC-link capacitor. The use of the DC-link capacitor in these converters makes the equipment volume bulky, reduces the lifetime, increases the design complexity and decreases the system efficiency. Therefore, it is of great benefit to remove the bulky DC-link capacitor or propose new converter topologies. A matrix converter (MC) does not require large energy storage elements and it has emerged as a potential solution to AC-to-AC conversion. A three-phase direct MC comprises nine bidirectional semiconductor switches arranged in a 3×3 matrix form to realize the direct AC-to-AC conversion. Thanks to benefits such as bidirectional power flow, compact volume, controllable input power factor and sinusoidal waveform, MCs have attracted research interests and plenty of projects on MC have been reported. MC is also regarded as an all-silicon converter. However, there are some drawbacks associated with MCs and they have very limited industrial applications. These drawbacks include low voltage transfer ratio (VTR), sensitivity to the grid variations and complex modulation. Some MC application areas need more exploration. The work in this thesis is carried out to contribute to possible solutions to some of the above issues by investigating some control strategies and applications of MCs. The main contributions included in this work are summarized as follows: (1) A simple decoupling controller is designed for the MC-based unified power flow controller (UPFC) (MC-UPFC) to regulate the power flow in a transmission system. The controllable regions of the MC-UPFC are also analyzed. A design procedure for the closed-loop controller in the MC-UPFC is presented. (2) A modified PI controller is proposed for the improvement of the steady-state performance by including a current feedforward path. More control flexibility is provided because of the feedforward controller. A PR controller is designed for the MC and this has good performance. (3) A hysteresis current controller is proposed for the MC to drive AC motors. Both fixed-band and sinusoidal-band hysteresis controllers are investigated, and their performance is compared. The hysteresis controller is a very simple and practical controller for the MC. For the MC-based motor drive, a direct torque control (DTC) technique is also investigated. (4) Model predictive control (MPC) is investigated to control the MC. This scheme is used in an MC-based microgrid. In the islanded mode, predictive voltage control is employed to regulate the MC output voltages to supply various loads. An improved VTR is observed. When the microgrid is connected to the utility grid, power flow is the main objective. The performance of the controller is tested under various conditions including input disturbance and different loads. (5) An MC prototype is built to support the research. The prototype hardware includes main circuit, drives, supplies, analog to digital conversion (ADC) conditioning circuits, and sensor board. The algorithm is implemented in Matlab Simulink with C2000 hardware support packages for TI DSP processors. Various experimental tests are carried out to support the proposed strategies

Predictive Voltage Control of Direct Matrix Converters with Improved Output Voltage for Renewable Distributed Generation

© 2013 IEEE. This paper proposes a predictive voltage control strategy for a direct matrix converter used in a renewable energy distributed generation (DG) system. A direct matrix converter with LC filters is controlled in order to work as a stable voltage supply for loads. This is especially relevant for the stand-alone operation of a renewable DG where a stable sinusoidal voltage, with desired amplitude and frequency under various load conditions, is the main control objective. The model predictive control is employed to regulate the matrix converter so that it produces stable sinusoidal voltages for different loads. With predictive control, many other control objectives, e.g., input power factor, common-mode voltage, and switching frequency, can be achieved depending on the application. To reduce the number of required measurements and sensors, this paper utilizes observers and makes the use of the switch matrices. In addition, the voltage transfer ratio can be improved with the proposed strategy. The controller is tested under various conditions including intermittent disturbance, nonlinear loads, and unbalanced loads. The proposed controller is effective, simple, and easy to implement. The simulation and experimental results verify the effectiveness of the proposed scheme and control strategy. This proposed scheme can be potentially used in microgrid applications

Implementación de una celda de un convertidor multiphase buck.

Implementar un convertidor multiphase buck de tres celdas; para la reducción de pérdidas de conducción mediante el análisis de convertidores multiphase buck.En los últimos años la producción de energía eléctrica, por medio de energías renovables ha ido avanzando mucho, apareciendo así conmutadores de estado sólido y equipos de conversión de energía esto con la intención de disminuir el consumo de combustibles fósiles y mitigar la producción de gases de efecto invernadero. Una de las ramas más beneficiadas con el desarrollo de tecnología es la electrónica de potencia materia la cual permite realizar el control de corriente y tensión de diferentes equipos. Los convertidores DC-DC tienen por objetivo tener una tensión de salida regulada según los requerimientos independientemente; existen tres tipos de tipologías dentro de estos convertidores que van variando según la necesidad y estos son: convertidor buck, convertidor boost y convertidor buck-boost. En este trabajo de grado nos enfocaremos en el convertidor Buck ya que es el tema principal de nuestra investigación y practica; básicamente este tipo de convertidor tiene como objetivo principal la obtención de una tensión de salida de menor valor con respecto a la tensión de entrada por medio de conmutadores controlados, los cuales se conmutan periódicamente por ancho de pulsos es importante mencionar también que este tipo de convertidor trabajar con una corriente de salida elevada. Uno de los principales obstáculos para el montaje de estos convertidores es el elevado costo y en ciertos casos las pérdidas de conmutación que son producidas por los semiconductores, es por esto que investigadores han desarrollado nuevas topologías y técnicas de modulación convenientes para el correcto funcionamiento de los semiconductores a altas corrientes y niveles elevados de tensión.Ingenierí