Tarık Erfidan

Design and implementation of flyback converters

In switch mode power supplies(SMPS), flyback converters are very popular because of, design simplicity, low cost, multiple isolated outputs, high output voltages and high efficiency. They are preferred especially for low power applications (150W). In this work, flyback converters are analyzed, mathematical modeled, designed with given parameters, tested with simulation software and practically results.

New software implementation of the space vector modulation

A new software implementation of the space vector modulation (SVM) on the vector controlled induction machine is proposed. The conventional SVM requires square root and arctangent computations. New SVM algorithm is develop to determine directly conducting times without square root and arctangent computations.

A simple and efficient implemantation of interleaved boost converter

Recently, DC-DC boost converters are usually required in many applications which has low output voltage, such as renewable energy sources. The interleaved boost converters consists of several identical boost converters connected in parallel and controlled by the interleaved method which has the same switching frequency and phase shift. The advantages of interleaved boost converters include increased efficiency, reduced size and improved reliability. This paper presents, simple design and implementation of a two phase interleaved boost converter.

Artificial neural network based hysteresis current controller for single-phase inverter

Single-phase inverters are specially used in the power supplies of computer units which placed in Telecom centrals. Being the voltage produced in an inverter is harmonically composed, causes a problem. In this study, in order to make the voltage on the load constant hysteresis current control was made by using the ability of learning and guessing the Neural Networks. The necessary simulations and harmonic analysis were made by using Matlab Simulink packet program.

A new ZVT–ZCT quasi-resonant DC link for soft switching inverters

In this article, the new ZVT–ZCT Quasi-Resonant DC Link, which ensures zero crossings at any time required for soft switching (SS) and provides zero voltage transition (ZVT) turn-on and zero current transition (ZCT) turn-off together for the main switch of active snubber cell in pulse width modulated or space vector modulated operation of inverter is presented. The new circuit combines the most desirable features of the circuits presented previously and overcomes most drawbacks of these circuits by using only one auxiliary switch with fewer other components. Consequently, new ZVT–ZCT Quasi-Resonant DC Link, which is verified by a prototype of a 1.2 kW and 50 kHz circuit, is analysed in detail. All semiconductor devices operate under SS, the main switch is subjected to no additional voltage and current stresses, and the stress on the auxiliary switch is very low in the proposed new inverter.

Low cost microcontroller based implementation of modulation techniques for three-phase inverter applications

Sinusoidal and space vector pulse width modulation (SPWM-SVPWM) techniques have been extensively used to build inverters, which generate AC voltage from DC voltage. The main application of this type of inverters is for variable speed induction motor drives. With the popularity of microprocessors, the implementations of these techniques are being used widely in inverters. This paper describes the procedures for the implementation of these two modulation techniques on a low-cost high speed microcontroller.

Low cost implementation of artificial neural network based space vector modulation

This paper presents a neural network based implementation of space vector modulation (SVM) of a voltage-fed inverter that only includes the under-modulation region. SVM has recently grown as a very popular pulse width modulation (PWM) method for voltage-fed converter ac drives because of its superior harmonic quality and extended linear range of operation. However, a difficulty of SVM is that it requires complex on-line computation that usually limits its operation up to several kHz of switching frequency. Switching frequency can be extended by using high-speed digital signal processing (DSP) card and simplifying computations by using look-up tables. In our work a low cost microcontroller was used instead of DSP card. The performances of the drive with artificial neural network (ANN) based sector selected SVM are faster than conventional SVM. The performances of the drive with ANN based SVM are excellent.

New phenemenon on power transformers and fault identification using artificial neural networks

In this paper voltage recovery after voltage dip that cause magnetizing inrush current which is a new phenomenon in power transformers are discussed and a new technique is proposed to distinquish internal fault conditions from no-fault conditions that is also containing these new phenomenons. The proposed differential algorithm is based on Artificial Neural Network (ANN). The training and testing data sets are obtained using SIMPOW-STRI power system simulation program and laboratory transformer. A novel neural network is designed and trained using back-propagation algorithm. It is seen that the proposed network is well trained and able to discriminate no-fault examples from fault examples with high accuracy.

Seasonal based energy performance analyzes of Cd-Te and c-Si photovoltaic modules

This paper presents a seasonal based comparative study about energy performances of c-Si and Cd-Te solar panels under same real weather conditions. For this purpose, two on-grid photovoltaic power systems (PPS) were installed on the different metal construction with same tilt angle and monitored between December 2013 and November 2014. Energy performance comparison has been carried out by using performance ratio (PR) and mean array efficiency (MAE) and energy performance index specified in IEC 61724, normalized energy and capacity factor (CF). It is shown that since temperature coefficient of power in Cd-Te is lower than that of c-Si, Cd-Te array performs better than another array. Some key result of this study can be summarized as follows: Generated energy of Cd-Te is higher than that of c-Si array by rate of 9.2%-10.8 within measurement period. In addition, due to the low dependency on temperature, PR, MAE and CF result in higher value than c-Si array as indicated in literature.

Microcontroller based soft-switched buck converter

In this paper, a universal auxiliary circuit named Zero Current and Zero Voltage Transition (ZCZVT) commutation cell applied to buck converter is presented. The operation of the proposed ZCZVT commutation cell applied to buck converter is theoretically analyzed. With the use of the proposed commutation cell, which is activated only during the switching transitions, full load range soft switching for all power semiconductor devices is achieved.