Mehmet Uçar

The Design and Implementation of a Shunt Active Power Filter based on Source Current Measurement

In this study, design and implementation of a shunt active power filter (APF) based on a simplified control method is given without load and filter current measurement. The proposed simplified control method is based on instantaneous reactive power theory (IRP) and requires only measuring the source currents to reduce the number of current sensors (CSs) required in the conventional control approach. The source currents are exactly in phase with the line voltages and approximately in sinusoidal waveform after reactive power and harmonic compensation. The proposed control technique has been tested under different load conditions using Matlab/Simulink simulations and validated with a 10 kVA/380 V experimental prototype based on digital signal processor (DSP) TMS320F2812. Both simulation and experimental test results demonstrate that the proposed method is feasible in meeting the IEEE 519-1992 recommended harmonic standard limits.

A Simplified Control Algorithm for Shunt Active Power Filter Without Load and Filter Current Measurement

In this study, a new control algorithm for three-phase shunt active power filter (APF) is proposed without load and filter current measurement. The proposed control method, based on instantaneous reactive power (IRP) theory, requires only measuring the source currents in order to reduce the number of current sensors (CSs) required in the conventional control approach. The source currents are exactly in phase with the line voltages and approximately sinusoidal waveform after compensation. The proposed control technique has been simulated Matlab/Simulink and tested under thyristor bridge rectifier load condition, and validated with a 10 kVA/380 V experimental prototype based on digital signal processor (DSP) TMS320F2812. Both simulation and experimental test results demonstrate viability of the proposed method, successful in meeting the IEEE 519-1992 recommended harmonic standard limits

A Methodology for Cutting Force Prediction in Side Milling

This article describes a methodology based on force distributions for predicting cutting forces in side milling 7075-T651 aluminum. The methodology includes a practical mechanism for gathering experimental data. Milling forces on each disc are measured by experimentally dividing the cutter into discs for determining the milling coefficients. Force distributions are characterized as functions of cutting and edge forces, including cutter geometry and cutting parameter effects. In contrast to previous researches, the coefficients are determined considering relations between load and shear. Owing to its high performance, this methodology can be effectively used to improve machining accuracy in side milling.

An analysis of three-phase four-wire active power filter for harmonic elimination reactive power compensation and load balancing under nonideal mains voltage

This paper presents a new control algorithm for a three-phase four-wire active power filter (APF) to eliminate harmonics, to compensate reactive power and neutral currents and to balance load currents of mixing single-phase and three-phase diode rectifier under non-ideal mains voltage conditions. Three-phase four-wire APF is composed of a conventional three-leg voltage-source inverter (VSI) and split DC link capacitors with a hysteresis-band PWM current controller. MATLAB/SIMULINK power system toolbox is used to simulate the proposed system. The proposed methods performance is compared with conventional instantaneous power (p-q) theory. The simulation results are presented and discussed showing the effectiveness of the control algorithm. The proposed control algorithm is found quite satisfactory to compensate reactive power and neutral current while eliminating harmonics with load balancing under non-ideal mains voltage conditions.

Thermal and mechanical properties of composite nanofiber webs and films containing cellulose nanowhiskers

In this study, nanocomposites reinforced with cellulose nanowhiskers (CNWs) were prepared by employing three different fabrication methods. These methods include electrospinning of nanofiber webs using a single-component nozzle, electrospinning of nanofiber webs using a coaxial bi-component nozzle, and film casting followed by compression molding. Maleic anhydride grafted elastomeric polymer was used as the polymer matrix. Nanocomposite samples obtained from these three different systems were characterized in terms of morphology, and mechanical and thermal properties. The processing–structure–property relationships of the nanocomposites are discussed in this paper.

A combined series-parallel active filter system implementation using generalized non-active power theory

In this paper, a generalized non-active power theory based control strategy is implemented in a 3-phase 4-wire combined series-parallel active filter (CSPAF) system for periodic and non-periodic waveforms compensation. The CSPAF system consists of a series active filter (SAF) and a parallel active filter (PAF) combination connected a common dc-link. The generalized non-active power theory is valid for singlephase and multi-phase systems, as well as periodic and non-periodic waveforms. The theory was applied in previous studies for current control in the PAF. In this study the theory is used for current and voltage control in the CSPAF system. The CSPAF system is simulated in Matlab/Simulink and an experimental setup is also built, so that different cases can be studied in simulations or experiments. The simulation and experimental results verify that the generalized non-active power theory is suitable for periodic and non-periodic current and voltage waveforms compensation in the CSPAF system.

The design and implementation of rain sensitive triggering system for windshield wiper motor

Automotive windshield wiper systems have three main components, which are wiper arms, connection mechanism and an electric motor that drives this mechanism. A windshield wiper motor must be operated when rainsqualls obscure the drivers sight area. Currently, windshield wiper motor systems are controlled in two different ways: in the first, the driving of motor is realized with predetermined constant time intervals using time relays. Secondly, the wiper motor system can also be controlled by the principle based on the infrared light reflection from the windshield. In this work, a new system is designed to drive a wiper motor using sensors that detect the wetness and rainsquall concentration on the windshield. The sensors are located on the windshield and are operated based on the feature of the rainsqualls weak electric conductivity. The system structure can be designed as controllable by single or multiple sensors. The experimental results based on a single sensor show the reliability of the system.

A Novel Failure Diagnosis System Design for Automotive Timing Belts

In this study, a novel failure diagnostic system for timing belts was developed in order to prevent a catastrophic belt failure. These failures may occur before running out the nominal belt life and lead to an extensive engine damage, thereby resulting costly repairs. Timing belt failures are generally resulted from three reasons, that is, lack of a tooth, fiber separation on belt sides, and teeth splitting. Three optical sensors with laser beam whose diameter is 0.6 mm was located on suitable positions and it is used to produce error signal resulted from disturbance of laser beam flows due to failure. The error signal is processed by the processor, which is independent from the electronic control unit (ECU) to alert the driver or ECU, directly. Experimental apparatus which consists of two camshaft pulleys and an idler pulley with belt tensioner has been set up to simulate real engine conditions. Experimental results show that the optical monitoring technique is reliable to determine timing belt failure types simultaneously in the range of 500–7000 rpm engine speed and it is also easier, low cost and more applicable than other methods such as vibration monitoring.

The Effects of Mechanical Properties on Fatigue Behavior of ECAPed AA7075

Abstract In this study, the effects of equal channel angular pressing (ECAP) on high-cycle fatigue and fatigue surface morphology of AA7075 have been investigated at a constant temperature (483 K) and the “C” route for four passes at ECAP process. ECAPed and as-received specimens were tested by four-point bending fatigue device. Fatigue tests were carried out by using 100, 120 and 140 MPa strength values. ECAPed specimens were characterized for each pass with optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectroscope (EDS), transmission electron microscope (TEM), selected area electron diffraction (SAED) and hardness measurements. Fracture surfaces of the specimens were also characterized with SEM. The results show that the highest hardness values (137 HV) and the best fatigue life (5.4 × 107 for 100 MPa) were measured in ECAPed four-pass sample. For this reason hardness values and fatigue life were increased with increasing number of severe plastic deformation (SPD) process.

SRF Based Output Voltage Control of 3-Level 3-Phase 4-Leg AT-NPC Inverter

This paper proposes a synchronous reference frame (SRF) based high performance output voltage controller for the 3-level 3-phase 4-leg (3P4L) advanced T-type neutral point clamped (AT-NPC) inverter operated in stand-alone mode. 3-phase inverters for stand-alone operation are required to provide 3-phase balanced nominal voltage under different load types such as unbalanced linear and non-linear loads. 3P4L inverters working with these types of load allow controlling zero sequence voltage by additional fourth leg. The main contribution of this work is the control of the 3-level 3P4L AT-NPC inverter with an LC-type filter modeled based on the output voltage and capacitor current feedback in the synchronous coordinate system. According to obtained capacitor current decoupled model, double loop PI controller is adopted to control the output voltage of the inverter. An inner capacitor current feedback loop is employed to provide fast dynamic response and active damping of the capacitor current. Finally, transient and steady state operation performance of the controller have been tested with PSIM simulation studies considering different load types. Simulation results validate that the proposed SRF based double loop PI controller ensure high dynamic response and high quality output voltage with less than 3% total harmonic distortion (THD) value for the 3-level 3P4L AT-NPC inverter.