Ilhami Colak

Fault Detection and Protection of Induction Motors Using Sensors

Protection of an induction motor (IM) against possible problems, such as overvoltage, overcurrent, overload, overtemperature, and undervoltage, occurring in the course of its operation is very important, because it is used intensively in industry as an actuator. IMs can be protected using some components, such as timers, contactors, voltage, and current relays. This method is known as the classical method that is very basic and involves mechanical dynamic parts. Computer and programmable integrated circuit (PIC) based protection methods have eliminated most of the mechanical components. However, the computer-based protection method requires an analog-to-digital conversion (ADC) card, and the PIC-based protection method does not visualize the electrical parameters measured. In this study, for IMs, a new protection method based on a programmable logic controller (PLC) has been introduced. In this method, all contactors, timers, relays, and the conversion card are eliminated. Moreover, the voltages, the currents, the speed, and the temperature values of the motor, and the problems occurred in the system, are monitored and warning messages are shown on the computer screen. Experimental results show that the PLC-based protection method developed costs less, provides higher accuracy as well as safe and visual environment compared with the classical, the computer, and the PIC-based protection systems.

A novel web-based laboratory for DC motor experiments

This article introduces a novel web‐based DC motor laboratory, called NeTRe‐LAB, to support teaching electrical machines. The NeTRe‐LAB includes favorable animations to facilitate understanding characteristics of the DC motor, interactive DC motor models for instructive simulations, and web‐based experiments with online monitoring features. To illustrate the current operations, remote access to an experimental setup of a DC motor has been provided and the speed control of it has been realized over Internet. The evaluation results have shown that the NeTRe‐LAB presented in this study provides encouraging aspects, services, and support system for higher education.

A Remote Laboratory Experiment for 4-Quadrant Control of a DC Motor

This study presents development of the system architecture to perform laboratory experiments over the Internet for electrical engineering education. Design and implementation of four‐quadrant speed control experiment for a direct current (DC) motor is given in the article as a sample remote experimental study. The system designed consists of four main parts as a client, a server, a data acquisition unit and an experimental set with a control unit. MATLAB web server (MWS) is used to send and receive data or graphics over the Internet. While the experiment is being operated, the real experimental set placed in the laboratory can be monitored by the remote user. Evaluation results show that the system designed accelerates the learning period, increases the concentration on the experiment and provides a safe environment for four‐quadrant speed control experiment of a DC motor.

The design and analysis of a 5-level cascaded voltage source inverter with low THD

Multilevel inverters have been important devices developed in recent years, owing to their capability to increase the voltage and power delivered to the load. Researches done based on basic inverter topologies show that, multilevel inverters have many advantages such as low power dissipation on power switches, low harmonic and low electromagnetic interference (EMI) outputs. A modified Sinusoidal Pulse Width Modulation (SPWM) modulator that reduces output harmonics is presented in this paper. The proposed modulation technique can be easily applied to any multilevel inverter topology carrying out the necessary calculations. The most common multilevel inverter topologies have been studied to define the best topology for SPWM modulation strategy. It is seen that cascaded H-bridges are the most convenient solution. The cascaded H-bridge cells have been constituted by IGBT semiconductors, and switched by the proposed 24-channel SPWM modulator to obtain 5-level output at the back-end of the 3-phase voltage source inverter (VSI). The designed H-bridge cells have a strong switching bandwidth up to 40 KHz, owing to its robustly designed modulator block. The proposed VSI in this paper also has a Total Harmonic Distortion ratio of output current (THDi) around at 0.1% without requiring any filtering circuit. The harmonic analysis of proposed design has been executed under several working conditions such as various switching frequencies and modulation indexes. The detailed comparisons have been performed to determine the best working conditions of VSI and presented in this paper.

Reactive power compensation using a fuzzy logic controlled synchronous motor

This paper introduces the use of a fuzzy logic controlled synchronous motor for reactive power compensation. The fuzzy logic controlled synchronous motor can give a very fast response to the reactive power required by the load. Therefore, the over or under compensation and time delay are eliminated in this system. It is concluded that the reactive power compensation system with a fuzzy logic controlled synchronous motor is reliable, sensitive, economical, faster and more efficient than an other one with capacitor groups.

A Novel Integrated Web Based Learning System for Electrical Machines Education

This study introduces a novel web based learning tool for electrical machines education. The tool developed consists of the real time experiments remotely accessible via internet in addition to thereotical presentations with animations and simulations on mathematical models of the electrical machines. The system is based on server/client architecture. All operation steps are executed by the server. So, clients do not need any additional software rather than internet connection and an internet browser. A DC motor course is given as an example to illustrate the novel tool developed. The remotely located users can learn the therotical information about the DC motor by means of using interactive web pages. All thereotical presentations supported with favorable animations to facilitate the understanding. Also, users can use the simulation models over the web to observe the motors dynamic behaviours under the different parameters. Moreover, they can remotely access a DC motor experimental set via internet to perform real time experiments such as speed control and generator operation of DC motor. During the conducting real time experiments over the web, the experimental set can be monitored with a webcam. Experimental results show that the integrated web based learning system developed is user-friendly and can be used for electrical machines education successfully.

Design and analysis of a 7-level cascaded multilevel inverter with dual SDCSs

Multilevel inverters with a large number of steps can generate high quality voltage waveforms, good enough to be considered as suitable voltage source generators. A modified Sinusoidal Pulse Width Modulation (SPWM) modulator with phase disposition that increases output waveform up to 7-level while reducing output harmonics is presented in this paper. The proposed modulation technique can easily be applied to any multilevel inverter topology carrying out the necessary calculations. The modulator block is designed to control multilevel inverter that is constituted using dual H-bridge cells with IGBTs on each phase legs. The supply voltages of cells are defined at Vdc÷2Vdc ratio to obtain an asymmetrical output. The output waveform of asymmetrical topology is increased up to 7-level by using dual separate DC sources (SDCSs). The DC supply requirement of asymmetrical cascaded topology is solved using dual sources instead of 6 SDCSs. The cascaded multilevel inverter is switched by the proposed 24-channel SPWM modulator. The harmonic analysis of proposed inverter has been performed under several working conditions such as various switching frequencies and modulation indexes. The detailed comparisons are performed to determine the best working conditions of voltage source inverters (VSI) and presented in this paper.

Implementation of Energy-efficient Inverter for Renewable Energy Sources

Abstract Switching losses that occur in inverters are one of the most important issues to be considered to improve the efficiency of any inverter. High-frequency resonant DC-link inverters are proposed to reduce switching losses in regular pulse-width modulation control according to conventional voltage source inverters. On the other hand, switching losses cause deficit efficiency in solar and wind energy conversion systems. In this study, a full-bridge Class D resonant inverter is modeled with Simulink (The MathWorks, Natick, Massachusetts, USA) and controlled with unipolar sinusoidal pulse-width modulation to minimize the switching power losses. The feed-forward control of resonance circuitry is realized with zero voltage switching that detects zero crossing points of the capacitor voltage. The performed analyses have shown that the control scheme is more convenient to reduce switching power losses according to antecedent studies.

Parallel DC-AC conversion system based on separate solar farms with MPPT control

Three separate solar farms that provide 15 kW power for each farm are modelled using Matlab Simulink real-time analysis software in this study. Each solar farm models are constituted by connecting 170W photovoltaic (PV) panels and energy conversion is performed with maximum power point tracking (MPPT) algorithms in each converter. The MPPT algorithm utilized in the control step of converters is developed using Perturb and Observe (P&O) structure. The converters used in the solar farms are designed in boost converter topology while output voltages are collected in DC busbar with parallel connection of converters. The converters are connected to busbar over interphase transformers (IPT). The DC busbar voltage is applied to a full bridge inverter to generate 3-phase AC voltages at the output of inverter. The three-phase inverter is controlled with sinusoidal pulse width modulation (SPWM) scheme, which is developed with phase shifted carrier signals. The load of inverter is set to an adjustable load, which is capable to be increased up to 50 kW. The measurement points seen in the Simulink design are analysed in detail. Each measurement points definition and screen captures are also evaluated in the study.

A modified harmonic mitigation analysis using Third Harmonic Injection PWM in a multilevel inverter control

A modified Third Harmonic Injection PWM (THI-PWM) modulator that reduces output harmonics has been presented in this paper. The modulator is combined with harmonic injection and phase shifting parts in Simulink design. The harmonic injection ratios have been analysed according to harmonic amplitude ratio of third harmonic to fundamental amplitude. The designed modulator is capable to minimize the injected harmonic ratio in order to increase the modulation index over 1.15 limit of regular THI-PWM control scheme. The proposed VSI in this paper supplies 7-level line voltages and 0.25% THDi ratio at 5 kHz while the modulation index is 1.2.