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Pulse frequency density modulation full bridge for induction preheating application of stainless-steel welding

Chakkuchan P., Chudjuarjeen S., Phankong N.

Archives of Materials Science and Engineering

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2024

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Vol. 127, nr 1

23--31

EN

Purpose: The paper shows the problem of surface cracks from welding (TIG welding) to welding stainless steel pipe (heat-affected zone: HAZ). The study is an experiment of preparing welding with non-heating workpieces and preheating the workpiece using the principle of induction, heating with a fluid inverter circuit that can adjust power by frequency control, pulse frequency density modulation (PFDM) to maintain temperature for industrial. Design/methodology/approach: The control circuit is responsible for regulating the functioning of different devices and the speed of operation of the switch device. It divides the control into two closed loops: phase-angle feedback and current feedback. The phase-angle feedback loop ensures frequency tracking during the phase check angle, enabling the inverter to operate at frequencies higher than the resonant frequency throughout its operation. The process of arc welding was employed in the fusion of stainless-steel materials. Preheating is a crucial step in the welding process, as it serves to uphold the integrity of the weld and mitigate the occurrence of undesirable outcomes such as cracking and the subsequent requirement for rework. The Welding Process Specification (WPS) about the task at hand will delineate the lower and upper limits of preheating temperatures and the requisite period for preheating. High-quality products should be devoid of these imperfections and possess comprehensive welding reinforcement. Additional welding certifications encompassed a tensile testing procedure, a microhardness testing procedure, and a comprehensive microstructure analysis. Findings: Applying an alternating voltage to an induction coil generates an alternating current (AC) within the coil circuit. The induced currents exhibit a frequency identical to that of the coil current, although they possess an opposite direction to the coil current. These currents facilitate heat generation through the phenomenon known as the Joule effect. The temperature range of 250°C-400°C can be effectively regulated for preheating stainless steel by using high-frequency electric process heating in induction welding, hence achieving the desired welding preheat. There are two primary classifications for inverters: voltage-source inverters and current-source inverters. Research limitations/implications: The main research limitation is comparing preheat and non-preheat. The size of the heat-affected zones is influenced by the rate of heating and cooling brought on by machining processes. By influencing the microstructural changes in that area, precise control of the variables can impact the integrity of the weld zones. The microstructural characteristics of the metal are different from the rest of the subject because welding heats the metal. The topic is heated up beforehand to ensure smooth welding and structural integrity. Because there is less of a temperature difference between the weld zone and the base material, preheating during welding results in less shrinkage stress. Distortions and crack flaws might result from higher shrinkage stress. Practical implications: NDT, or non-destructive testing, is a weld integrity test to find defects that occur in the weld without damaging that welding line and continuing to use it safely. For the welding line to be strong according to the design of that welding line (conformance to design), the test will use the principles of physical properties, such as light, X or gamma rays, magnetic fields, and high-frequency sound waves. Originality/value: In the research, stainless steel was successfully welded to preheat using induction heating (IH).

2

Traction power supply with three paralleled single phase voltage source inverters

Płatek Tadeusz, Osypinski Tomasz, Chłodnicki Zdziaław

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 2

art. no. e136733

EN

Installation and operation of rail vehicles powered by multiple system voltages forces the construction of multi-system traction substation. The article describes a traction substation power supply with 15 kV output voltage and frequency Hz and 25 kV at 50 Hz. The topology of the power electronics system and the control structure of the power supply enables parallel connection of several power supplies. The selected topology and control structure ensures minimizing the rms value of the LCRL filter capacitor current used at the output of the inverters. The article analyses the influence of harmonics consumed by the active front end (AFE) rectifier used in traction vehicles on the rms current of the LCRL filter capacitor.

3

Space vector modulation techniques for improved stator flux trajectory in direct torque control of induction motor

Rafajlovski Goran, Digalovski Mihail, Cvetkovski Goga

Przegląd Elektrotechniczny

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2019

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R. 95, nr 5

14--17

EN

In direct torque vector control systems, voltage source inverter is described in discrete mode as a source of constant amplitude voltage sources with strictly controlled direction, time duration and limited sample frequency. The dynamic state of the inverter is discrete both in time and quantity. In this paper, therefore, the basic characteristics of stator flux space vector will be analysed in such a control concept for two different types of space vector modulation (SVM) techniques one is full block space vector modulation and second is called pulse edge space vector modulation.

PL

W układach bezpośredniego sterowania wektorami momentu obrotowego, falownik źródła napięcia jest opisany w trybie dyskretnym jako źródło stałych źródeł napięcia o amplitudzie ze ściśle kontrolowaną polaryzacją, czasem trwania i ograniczoną częstotliwością próbkowania. Stan dynamiczny falownika opisywany jest w sposób dyskretny zarówno pod względem czasu jak i wartości. W przedstawionym artykule została przeanalizowana podstawowa charakterystyka wektora przestrzennego strumienia stojana w koncepcji sterowania dla dwóch różnych sposobów modulacji wektora przestrzennego (SVM). Jedna jest modulacją wektora przestrzennego obszaru pracy blokowej, a druga jest nazywana dyskretną modulacją wektora przestrzennego.

4

A comparative study between load and No-load condition of Brushless DC Motor drives by using MATLAB

Das U., Biswas P. K., Debnath S.

Journal of Power Technologies

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2018

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Vol. 98, nr 3

281--286

EN

In this paper an extensive comparative performance study is carried out between No-load and load condition of an open loop model of a Brushless Direct Current (BLDC) Motor drive fed from a two-level voltage source inverter (VSI) under 120-degree conduction mode, using simulations in a MATLAB based software environment. BLDC motors are currently growing in popularity and replacing the brush motor in many applications, as they can be used in both low and high-speed vehicle systems and also in servo drives. The high reliability, torque to inertia ratio, high efficiency, high power density, ease of control and mainly the brushless operation make BLDC motors superior to others. It has a permanent magnet as a rotor with a balanced 3-phase armature in its stator. The armature winding is driven by a power electronics inverter which is switched in synchronism with the rotor position, sensed by an optical encoder or a Hall Effect sensor. It is found that torque ripple can be minimized by tuning the value of rotor position, no load condition and trapezoidal armature phase current. The different performance parameters for no-load and load condition of the BLDC motor such as phase voltages, phase currents, speed, electromagnetic torque, d and q axis current and rotor position etc. are determined in MATLAB environment.