Theses

Theses

Ongoing theses are listed below.

PhD Theses


Mesut Uğur-INTEGRATED MODULAR MOTOR DRIVE (IMMD)

  • Integrated modular motor drive (IMMD) has been a popular technology for several years which aims to combine the motor and the power electronics drive into a single package. Higher power densities can be achieved by this integration. Furthermore, the requirement of drive panels and connection cables are eliminated which contributes to loss and EMI reduction. However, integrating the motor and its drive brings several problems such as the requirement of passive component size reduction and thermal management issues. In this research work, an IMMD system is proposed for use in railway traction systems. Several motor drive topologies are investigated and the most suitable ones are compared in terms of efficiency and power density. To reduce size and to ease thermal management, new generation wide band gap (WBG) power semiconductor devices are aimed to be used in this work such as, Gallium Nitride Field Effect Transistors (GaN FETs) and Silicon Carbide Metal Oxide Semiconductor Field Effect Transistors (SiC MOSFETs) which usually yield a better power density, higher efficiency and more convenient cooling. The proposed IMMD is to be manufactured and tested in the laboratory to verify the analysis experimentally.

Supervised by Ozan Keysan

MSc Theses


Doğa Ceylan – RAILGUN
  • Railgun is a launcher which uses the energy of electromagnetic forces instead of conventional gunpowder. Railguns have a number of potential practical applications like launch or launch assist of a spacecraft or in the aircraft carriers. High amount of energy is released in a short amount of time from impulse generator module to rails. This high current in the rails and mature creates an electromagnetic force which moves the projectile in the forward direction. In this study, the finite element analysis (FEA) for railgun problem is used for optimizing some critical parameters of the electromagnetic launcher system. Working principles of the electromagnetic launcher, modelling the dimensions of the rails, modelling the geometry and dimensions of the projectile, its firing circuitry, current density on the rails and armature, created magnetic field, Lorenz force on the armature, inductance variation of the system, material properties of the projectile and rails including heating and melting properties under the effect of the high currents will be analyzed by the use of the finite element analysis methods. Comsol Multiphysics Modeling Software will be used as the main simulation tool for this purpose.

Supervised by Ozan Keysan

Onur Tek -SILICON-CARBIDE(SIC) CONVERTERS FOR WIND TURBINES

  • Wind energy is the most promising renewable energy type. Power converters are the most critical subsystem in wind turbine systems. Power converters are used to regulate the generated power from the wind turbines and also used as an ancillary services to the grid. In these power converters IGBT modules, press-packed IGBT’s and press-packed IGCT’s are used as switching devices. Recent develeopments in semiconductor technology shown that the Silicon-Carbide(SiC) devices have better switching characteristics and lower power losses than Silicon based devices. Lower power loss means increase in the efficiency of wind turbine system and lower volume and weight for heatsinks. In this thesis, two 10 kW back to back converters will be designed by using SiC devices and the effects of these devices to the wind turbine system will be investigated. Also designed converters will be operated as parallel and the results of paralllel operation will be investigated.

Supervised by Ozan Keysan

Lütfi Boyacı -Design and Application of Reaction Wheel motor (BLDC) drive for satellites.

  • Comparison of GANFETs and MOSFETs as a switching elements in the drive in terms of switching performances, losses, efficiency, drive requirements, radiation performances etc. Aim is to reduce switching losses and improve efficiency, to decrease filter sizes and PCB dimensions by using GANFETs for volumetric and massic gain.

Supervised by Ozan Keysan