Analysis and Modelling of Power-Dependent Harmonic Characteristics of Modern PE Devices in LV Networks

This paper presents results of experimental and analytical evaluation of power-dependent harmonic emission of three common types of modern low-voltage (LV) power-electronic (PE) devices. After a detailed analysis of comprehensive test results, based on both existing and new waveform distortion indices, the development of component-based models of PE devices is discussed. This paper demonstrates the importance of including PE devices' controls for accurate modelling of their characteristics over the entire range of operating powers. Most of the analyzed PE devices exhibit strong power-dependent changes of characteristics, additionally influenced by supply-voltage conditions, which are important for the analysis of both existing networks and future 'smart grids'

Direct usage of photovoltaic solar panels to supply a freezer motor with variable DC input voltage

In this paper, a single-phase photovoltaic (PV) inverter fed by a boost converter to supply a freezer motor with variable DC input is investigated. The proposed circuit has two stages. Firstly, the DC output of the PV panel that varies between 150 and 300 V will be applied to the boost converter. The boost converter will boost the input voltage to a fixed 300 V DC. Next, this voltage is supplied to the single-phase full-bridge inverter to obtain 230 V AC. In the end, The output of the inverter will feed a freezer motor. The PV panels can be stand-alone or grid-connected. The grid-connected PV is divided into two categories, such as with a transformer and without a transformer, a transformer type has galvanic isolation resulting in increasing the security and also provides no further DC current toward the grid, but it is expensive, heavy and bulky. The transformerless type holds high efficiency and it is cheaper, but it suffers from leakage current between PV and the grid. This paper proposes a stand-alone direct use of PV to supply a freezer; therefore, no grid connection will result in no leakage current between the PV and Grid. The proposed circuit has some features such as no filtering circuit at the output of the inverter, no battery in the system, DC-link instead of AC link that reduces no-loads, having a higher efficiency, and holding enough energy in the DC-link capacitor to get the motor started. The circuit uses no transformers, thus, it is cheaper and has a smaller size. In addition, the system does not require a complex pulse width modulation (PWM) technique, because the motor can operate with a pulsed waveform. The control strategy uses the PWM signal with the desired timing. With this type of square wave, the harmonics (5th and 7th) of the voltage are reduced. The experimental and simulation results are presented to verify the feasibility of the proposed strategy

Free Level Threshold Zone (FLTZ) Logic For Mixed Analog-Digital Closed Loop Circuitry [TK7887.6. N335 2008 f rb].

Para penyelidik sentiasa mencari cara-cara penambahbaikan kaedah antara muka antara domain Analog dan Digital. Researchers have always look for ways to improve the interfacing method between the Analog and Digital domain

디지털 엑스선 장비의 고압 케이블과 인접 신호 케이블간 Crosstalk 원인 및 대책

학위논문 (석사) -- 서울대학교 대학원 : 공학전문대학원 응용공학과, 2021. 2. 남상욱.The term medical equipment refers to the devices used for disease prevention, diagnosis, and treatment of humans or animals. These types of equipment are different from general electronic devices in terms of their intended purposes of use. This means that it is more important to diagnose and treat accurately and quickly rather than use superior performance or cutting-edge technologies. Clearly, the application of the latest technologies that emerge following advancements in the information technology industry cannot be ignored, but the stability and reliability of products are separate issues. Digital radiography (DR) is a system that consists of numerous circuits, cables, and electronic components. Because of its large scale and very complex structure, DR can potentially degrade the performance or damage other electronic devices owing to electromagnetic interference (EMI). In particular, noise mixed in high-voltage pulses for X-ray sources generated by the high-voltage generator (HVG) will propagates throughout the system, and cause EMI problems and malfunctions. Therefore, electromagnetic compatibility (EMC) for medical equipment products is a field directly related to product reliability. This study analyzes the causes of noise generated by the HVG used in DR systems. In addition, we suggest a solution for EMI noise reduction. This EMI noise couples with an adjacent cable through a high-voltage cable. Most of the EMI noise is reduced because the high-voltage cable in the DR system is shielded and has a high-optical coverage of 95\%. However, as the amplitude of the X-ray pulse reaches several tens of kV and the receptors load impedance is high enough in these typed of applications, it can be coupled to the adjacent signal cable and cause system malfunction. Therefore, in this study, we analyze the mechanism of coupling in the shielded cable, and determine the cause of the noise source and the type of coupling using equivalent circuit analysis. As a countermeasure to noise, we propose a method that satisfies both low cost and high reliability.의료기기는 사람이나 동물에게 단독 또는 조합하여 사용되는 장치를 말하며 질병 예방, 진단 및 치료에 목적을 두고 있다는 점에서 타 전자제품과는 차이가 있다. 이 말은 단순히 성능적으로 우수하고 다양한 최신 기술이 적용되는 것이 중요한 게 아니라 얼마나 정확하고 신속히 진단을 내리고 치료를 할 수 있느냐가 핵심이라는 것이다. 물론 IT 업계에서 매년 쏟아져 나오는 최신 기술을 적용하는 것도 무시할 수 없지만 제품의 안정성, 신뢰성과는 또 다른 이야기이다. Digital Radiography(DR)는 수많은 회로와 cable, 전장부품들로 이루어진 시스템으로 규모가 크고 구조가 매우 복잡하여 전자기 장애(EMI)로 인한 성능 저하나 타 전자기기에 피해를 줄 가능성을 많이 내포하고 있다. 특히 X-ray source 역할을 하는 high-voltage generator(HVG)로부터 발생하는 고전압 pulse는 DR 장비 전체로 퍼져 나가며 EMI 문제를 일으키고 오동작을 유발하곤 한다. 따라서 의료기기 제품에 있어 전자파 적합성(EMC)은 곧 제품의 신뢰성과 직결된 분야이다. 본 프로젝트 리포트는 DR 시스템에 사용되는 HVG에서 발생하는 noise의 원인과 high-voltage cable을 경로로 인접 cable까지 coupling 되는 EMI noise에 대한 정도 및 저감 대책을 분석하였다. High-voltage cable은 약 95%의 높은 Optical coverage로 shielding 처리가 되어 있어 상당 부분의 EMI noise가 저감된다. 그러나 X-ray pulse의 크기는 수십 kV에 달하고 noise의 주파수 또한 낮지 않기 때문에 인접한 signal cable로 시스템 오동작을 유발할 만큼 충분한 수준으로 noise가 유입될 수 있다. 따라서 본 프로젝트 리포트에서는 먼저 shielded cable에서 coupling이 발생하는 mechanism을 살펴보고 noise source의 경로 및 발생 원인, 그리고 등가회로 분석을 통한 coupling의 종류를 알아본다. 마지막으로 이에 대한 noise 저감 대책은 비용과 신뢰성 모두를 만족하게 할 방법을 제안한다.Abstract i Contents iii List of Tables v List of Figures vi 1 INTRODUCTION 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.1 Digital Radiography System . . . . . . . . . . . . . . . . . . 2 1.1.2 High-voltage Generator . . . . . . . . . . . . . . . . . . . . 3 1.1.3 High-voltage Cable . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 THEORETICAL BACKGROUND 7 2.1 Coupling Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1 Capacitive Coupling . . . . . . . . . . . . . . . . . . . . . . 7 2.1.2 Inductive Coupling . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Effect of Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.1 Structure of the Braided Shield . . . . . . . . . . . . . . . . . 13 2.2.2 Transfer Parameter . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.3 Effect of the Shielding Condition . . . . . . . . . . . . . . . 20 2.3 Conduction Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.3.1 Common-mode Noise . . . . . . . . . . . . . . . . . . . . . 29 2.3.2 Rectifier Diode Noise . . . . . . . . . . . . . . . . . . . . . . 30 3 ANALYSIS 33 3.1 Equivalent Circuit of Capacitive Coupling . . . . . . . . . . . . . . . 38 3.2 Equivalent Circuit of Inductive Coupling . . . . . . . . . . . . . . . . 38 3.3 Equivalent Circuit of Shield Interruption . . . . . . . . . . . . . . . . 41 4 EVALUATION 47 4.1 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.1.1 Coupling Noise . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.1.2 Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.2 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 5 CONCLUSION 67 Abstract (In Korean) 71 Acknowlegement 73Maste

Easy Technical Guide to Understand PC Motherboard, Troubleshoot Problems and Its Repair: PART-I

ABSTRACT : With the widespread use of computers in each and every field and with the technological advancement in semiconductor processing industries, it is required to evaluate the performance of the computer in a profound manner. This requires the thorough knowledge of personal computers. Motherboard is heart of any computer system. In a computer system in different parts, different faults may arises. In this paper details of motherboard is discussed. In the first part of this paper series different VRM circuit of motherboard is discussed in detail. Also, technical guide is suggested for troubleshooting of VRM circuit faults and its remedies

Off-Grid Inverter with Regulated Output Voltage Amplitude

The paper discusses the design, simulation, and implementation of a 60W, 115VAC, 60Hz off-grid power inverter. The off-grid inverter creates a mains-level voltage from a 12V lead-acid battery input without connection to a conventional electric grid. The inverter includes a low-voltage H-Bridge circuit that is controlled with 3-level Pulse Width Modulation (PWM), and uses a low frequency step up transformer from 12V to 115V. A feedback system based on IQ sampling and a Proportional, Integral, Derivative controller (PID) is implemented to maintain a constant output voltage amplitude over an input range of 10 to 15VDC. A microcontroller is used to generate PWM and implement the feedback loop. The inverter successfully powers small household loads such as a desktop fan and laptop

Design of a wireless monitoring system based on the ZigBee protocol for photovoltaic systems

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.This work deals with the possibility of using the promising technology of wireless sensor networks (WSN) in the field of photovoltaic (PV) plant supervising and monitoring. The knowledge of the status and good working condition of each PV module separately as well as of any component of the PV system will guide in a more efficient way of power management. This work will concentrate on monitoring and controlling as well as healthy operation control of PV panels separately. Data logging will be also available and can be used for reference or statistical purposes. The nature of wireless sensor networks (WSN) offers several advantages on monitoring and controlling applications over other traditional technologies including self-healing, self-organization, and flexibility. The versatility, ease of use, and reliability of a mesh network topology offered by the ZigBee technology that is based on the IEEE 802.15.4 standard, are used in this work to offer the maximum of its capabilities on the system being presented. A set of sensors attached on each PV panel are connected to a wireless ZigBee module. Each PV panel has its own ZigBee device located at its back side. All ZigBee devices forms a network with all the necessary devices of the ZigBee protocol included, such as end devises (RFD), a router (FFD), and a coordinator (COO). An extra ZigBee device might optionally be used to serve the whole system as an Ethernet gateway for making the system able to be connected to the internet. The factors that are being monitored are the panel‟s temperature, the output voltage, and output current. At the router device that operates as a parent for all the end devices, extra monitored factors are the air dust concentration, current irradiance and also the angle of the PV array (in the case of tracking system use).Two controlling outputs (relays) are located at the router device offering the capability of controlling the motors or the actuators of a tracking system