Sertac Bayhan

Model Predictive Control of Quasi-Z-Source Four-Leg Inverter

This paper presents a model predictive control (MPC) scheme for quasi-Z-source (qZS) three-phase four-leg inverter. In order to cope with the drawbacks of traditional voltage source inverters (VSIs), a qZS three-phase four-leg inverter topology is proposed. This topology features a wide range of voltage gain which is suitable for applications in renewable energy-based power systems, where the output of the renewable energy sources varies widely with operating conditions such as wind speed, temperature, and solar irradiation. To improve the capability of the controller, an MPC scheme is used which implements a discrete-time model of the system. The controller handles each phase current independently, which adds flexibility to the system. Simulation and experimental studies verify the performances of the proposed control strategy under balanced and unbalanced load conditions as well as single-phase open-circuit fault condition.

Z-Source Matrix Converter: An Overview

Conventional matrix converters (MCs) have limited voltage gain that is less than 0.866, whether for direct MC (DMC) or indirect MC (IMC). The Z-source MCs (ZSMCs) overcome the voltage gain limitation of the traditional MC and achieve buck and boost operation with reduced switches count, thereby achieving low cost, high efficiency, and reliability, compared to the back-to-back converter. Furthermore, it will leads to more MC industrial applications. This paper presents an up-to-date comprehensive overview of the different ZSMC topologies and their configurations, circuit analyses, modulation schemes, and applications. This study offers a comprehensive and systematic reference for the future development of the ZSMCs.

Model predictive sensorless control of standalone doubly fed induction generator

This paper presents a model predictive control technique for standalone doubly fed induction generators (DFIGs) without using position sensor. The technique uses a discrete-time model of the system to predict the future value of the rotor current for all possible voltage vectors generated by the rotor side converter (RSC). In this study, due to computational simplicity, the absolute error is selected as a quality function. Also, rotor position phase locked loop (RP-PLL) algorithm is used to achieve sensorless operation. The proposed MPC with RP-PLL sensorless algorithm is designed and simulated in Matlab &Simulink. Simulation results, including constant speed and load changes, and also variable rotor speed and constant load, are presented. The simulation results have proven excellent performance of the proposed MPC with RP-PLL sensorless algorithm, both of load and speed changes conditions.

Medium-Voltage Drives: Challenges and existing technology

This article presents an overview of state-of-art solutions, advances, and design and research trends in medium-voltage (MV) drive technologies-and also discusses the challenges and requirements associated with the use of such drives. The choice and deployment of MV drives in industries are associated with numerous requirements related to the front-end converter (grid side) and inverter (machine side). The focus is on solutions that present high efficiency; low price, size, and weight; minimum harmonic distortion; reduction in dv/dt; mitigation of common-mode (CM) voltage; avoiding torsional vibration; transformerless solutions; fault detection capability; and condition monitoring.

Model predictive control of quasi-Z source three-phase four-leg inverter

This paper presents a model predictive control (MPC) scheme for quasi-Z source (qZS) three-phase four-leg inverters. In order to cope with drawbacks of the traditional voltage source inverters (VSI)s, the qZS three-phase four-leg inverter topology is proposed in this study. To improve control capability of the controller, the MPC scheme is used. The proposed MPC is based mainly on the discrete-time model of the whole system. The proposed controller handles each phase current independently. As a result of this, the proposed qZS four-leg inverter has fault tolerant capability, for example if one leg fails the others can work normally. Simulation studies were performed to verify the steady-state and transient-state performances of the proposed control strategy under balanced/unbalanced reference currents and load conditions.

An effective Model Predictive Control for grid connected Packed U Cells multilevel inverter

This paper presents a Model Predictive Control (MPC) for grid-tied Packed U Cells (PUC) multilevel inverter. The system under study consists of a single-phase 3-cell PUC inverter connected to the grid through filtering inductor. The proposed topology allows the generation of 7-level output voltage with reduction of passive and active components compared to the conventional multilevel inverters. The aim of the proposed MPC technique is to achieve grid-tied current injection, low Total Harmonic Distortion (THD) of the current, unity power factor, while balancing the capacitor voltages at maximum power point (MPP). The feasibility of this strategy is validated by simulation using Matlab/Simulink environment.

Model Predictive Control of Z-Source four-leg inverter for standalone Photovoltaic system with unbalanced load

In this paper, Z-Source (ZS) four-leg inverter equipped with a Model Predictive Control (MPC) strategy for standalone Photovoltaic (PV) system under various load conditions is presented. The inverter is aimed to supply simultaneously three-phase and single-phase AC loads with balanced voltage and constant frequency. In this topology, a simple LC (Z) network is used instead of the boost converter to obtain single stage power conversion system. The MPC scheme is developed to control output currents of the inverter and ZS network current and voltage. Hardware-In-The-Loop (HIL) tests have been performed to verify steady-state and transient performances of the proposed system under balance/unbalanced load and/or reference current conditions.

Three-phase multilevel grid interactive inverter for PV systems with reactive power support capability

This paper presents a novel photovoltaic (PV) based three-phase three-level grid-interactive inverter. The proposed system consist of a DC/DC converter, and a three-phase three-level inverter. In order to ensure maximum power point tracking, incremental conductance (IC) technique is used. In addition, to meet international standards for all operating modes, three-phase three-level inverter has been designed and controlled by PI plus grid voltage feed-forward control technique. The proposed system can also operate in various modes to meet smart grids requirements: (1) active power mode in a day time, (2) active and reactive power mode in a day time, (3) reactive power mode at night. To support grid voltage regulation during the day, Mode 1 and Mode 2 are used. These three operation modes bring some benefits such as efficient operation, and reactive power support capability. The proposed system is designed and simulated in Matlab&Simulink software. The simulation results show that the proposed system has an excellent performance under different operating modes.

Internet based virtual electric machine lab: Switched reluctance motor

In this study, distance accessed virtual laboratory for an electric machine was established. For this purpose a switched reluctance motor (SRM) was chosen as an example. Simulation of a SRM was achieved with using Matlab&Simulink package program. A LabVIEW program was used to build an Interface between internets and the simulation program. Any student or user is able to access these educational tools from any place having an internet connection and can change necessary parameters of SRM and also see behavior of SRM with help of graphics on screen.

Lyapunov-function based control approach with cascaded PR controllers for single-phase grid-tied LCL-filtered quasi-Z-source inverters

This paper presents a Lyapunov-function based control approach with cascaded proportional-resonant (PR) controller for single-phase grid-tied LCL-filtered quasi-Z-source inverter (qZSI). The proposed control approach guarantees the global stability of the closed-loop system and zero steady-state error in the grid current. The reference values for the inverter current and capacitor voltage are generated by using cascaded connected PR controllers. As a consequence of using PR controllers, the need for performing derivative operations and estimating grid side inductance and capacitance is eliminated which, in turn, achieves zero steady-state error in the grid current. The shoot through control of the qZSI is achieved by the simple boost control technique. Computer simulations are conducted to show that the proposed control approach provides a good steady-state and dynamic performance in achieving the required control objectives.