Actual vs textbook transformers

2021 ◽  
Vol 57 (2) ◽  
pp. 023003
Author(s):  
Rod Cross
Keyword(s):  
Total Flux ◽  
Secondary Coil ◽  
Primary Coil

Abstract The current in the secondary coil of a transformer acts to oppose the flux generated by current in the primary coil, by Lenz’s law. According to most physics textbooks, the total flux is then zero, so transformers should stop working. Something is missing in the textbook accounts.

Analysis of the Influence and Number of Turns on the Smartphone Wireless Charger on the Output Power of the Wireless Charger

2020 ◽  
Vol 10 (1) ◽  
pp. 20-25
Author(s):  
Donny Firmansyah
Keyword(s):  
Output Power ◽  
Magnetic Induction ◽  
Secondary Coil ◽  
Wireless Charging ◽  
Transmitted Power ◽  
Primary Coil ◽  
Power Test ◽  
Transmission Distance ◽  
Coil Diameter

Charging the smartphone battery can be done via powerbank or default charger from the smartphone still using the cable for charging the electricity. Charging using a cable certainly limits the use of the smartphone when it is charging. Smartphone users can not be far from the electric socket which of course is troublesome if this happens in the middle of a room that has a few electrical sockets. To solve this problem, now many wireless charging smartphones or smartphones have been developed wireless charger. Behind the benefits obtained from a wireless charger, it also has disadvantages, namely the transmission distance is short, even there is no distance and the transmitted power is unstable. Wireless chargers are based on the principle of magnetic induction in which electricity is transferred between two objects through a coil. Wireless charger consists of the primary coil as a charger (usually in the form of a thin board or cylinder), and the secondary coil is located on the back of the cellphone. Based on the results, the output power is obtained. The largest wireless charger is 0.027W with a coil diameter of 8cm in all the number of primary coils, namely 40 turns, 50 turns, and 60 turns at a primary and secondary coil distance of 0cm to 1cm. The farthest distance from the wireless charger output power test is 6cm as well as the 8cm coil diameter for all the number of primary coil turns, namely 40 turns, 50 turns, and 60 turns.

Study on Measuring the Resonant Frequency of Air Core Transformer on Mass Spectrometer with a Test Coil

2014 ◽  
Vol 568-570 ◽  
pp. 395-400
Author(s):  
Kai Ni ◽  
Xiang Yan ◽  
Quan Yu ◽  
Zu Hua Shi ◽  
Xin Qiong Lu ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Real Time ◽  
Mass Spectrometer ◽  
High Sensitivity ◽  
Secondary Coil ◽  
Primary Coil ◽  
Load Effect ◽  
Air Core ◽  
Impedance System ◽  
The Right

Air core transformer is an essential part of mass spectrometer. Test coil is often used to measure its resonant frequency with the advantages of easy installation and high sensitivity. However, the influence of test coil while it is installed close to the working coils on the transformer is not studied before. To reveal the influence of test coil and determine the right position to install, two experiments using test coil and opened probe respectively for the measurement are conducted. Since the opened probe has little load effect on the original transformer impedance system, it can be used to validate the influence of test coil. By comparing the two experimental results, we find that the right position to install the test coil is on the further side of the primary coil to the secondary coil. This work allows us to integrate the test coil with the air core transformer to monitor the resonant frequency in real-time.

scholarly journals IV. Note on the excitation of the surface of the cerebral hemispheres by induced currents

1874 ◽  
Vol 22 (148-155) ◽  
pp. 368-370 ◽  
Keyword(s):  
Royal Society ◽  
Copper Wire ◽  
The Body ◽  
Secondary Coil ◽  
Living Tissue ◽  
Primary Coil ◽  
Accurate Definition ◽  
Combined Movements ◽  
Induced Currents ◽  
The Brain

In a paper recently communicated to the Royal Society by Dr. Ferrier (Proceedings, No. 151) it is shown that when two ends of copper wire distant from each other not more than a couple of millimetres, and in metallic communication with the terminals of the secondary coil of a Du Bois’s induction-apparatus in action, are applied to certain spots of the surface of either hemisphere, and great intensity is given to the induced currents thereby directed through the living tissue, by previously bringing the secondary coil into such a position that it is very close to the primary coil or even partially covers it, characteristic combined movements of the opposite side of the body are produced. With reference to these effects, it was observed by Dr. Ferrier (1) that excitation of the same spot always produces the same movement in the same animal, (2) that the area of excitability for any given movement (or, as it may be called for shortness, active spot ) is extremely small and admits of very accurate definition, and (3) that in different animals excitations of anatomically corresponding spots produce similar or corresponding results. From these remarkable facts and from others similar to them relating to other parts of the brain to which I do not now advert, it was inferred that, at the surface of the hemispheres, certain “centres” are to be found, of which it is the function to originate combined or even purposive movements.

scholarly journals ANALYSIS THE EFFECT OF PRIMARY COIL LENGTH OF TRANSFORMATOR TO THE RESULTED ELECTROMOTIF FORCE

2019 ◽  
Vol 4 (1) ◽  
pp. 31-38
Author(s):  
Bowo Eko Cahyono ◽  
Muhammad Syukron Ali ◽  
Supriyadi Supriyadi
Keyword(s):  
Output Voltage ◽  
Electrical Energy ◽  
Input Voltage ◽  
Secondary Coil ◽  
Length Variation ◽  
Primary Coil ◽  
Specific Level ◽  
Voltage Variation ◽  
Length Variant ◽  
Relationship Of

Transformator is an electrical device that uses a principle of solenoid wrapped in kern, and there are usually two or more coils. Each coil of the taranformator is electromagnetically connected. The transformator is made to fulfill the specific level of voltage required in the devices or systems that use alternating current electrical energy. For example, transformator tap change is design to have different number of primary turns to produce a fixed output voltage, in term there is a changing in the input voltage. This research tries to analyze the effect of the length of primary coil difference of transformator to the voltage resulted in the secondary coil. The objective of the study is producing a relationship of primary coil length variation to the resulting voltage. Variation of coil length is made from 1 cm to 15 cm with interval of 1 cm coil length. The length of the secondary coil is also varied imto 3 cm, 6 cm, and 9 cm. The test is performed by providing the same input voltage at each variation of the primary coil length and then measure the output voltage. The results show that the longer primary coil will produce the smaller output voltage in the secondary coil of tranformator. Based on the resulted graph, the relationship of the length variant of primary coil is linear to the voltage measured in the secondary coil.with determination coefficient (R2) of  0.9603, 0.9775, and 0.9822 respectively forlength of  3 cm, 6 cm, and 9 cm of the secondary coil.

scholarly journals Design of Wireless Power Transfer for Heart Assist Devices

2019 ◽  
Vol 8 (12S) ◽  
pp. 73-76
Keyword(s):  
Blood Flow ◽  
The Body ◽  
Secondary Coil ◽  
Power Transfer ◽  
Wireless Power ◽  
Primary Coil ◽  
Short Term ◽  
Assist Devices ◽  
Heart Pump ◽  
Heart Assist Devices

Heart assist devices are designed for helping damaged hearts maintain sufficient blood flow, for patients getting heart attack with short term and it is used for congestive heart failure patients. The frequency with which the patients are being operated to replace the battery of these devices can be aided and reduced by wirelessly transmitting power. The transcutaneous power transfer for the devices requires charges that move outside the body to induce charges to move inside the body which can ultimately be used to supply energy to the heart pump. WPT is a method of transmitting wireless power using an external primary coil to generate a magnetic field. It passes through the skin and induces current in an implanted secondary coil. The infection caused due to surgery is removed by WPT method. To monitor the charging level of the battery the Wi-fi module is used. It also monitors the corresponding blood flow and the pulse during this function.

The Impact of NiCuZn Ferrite Material on the Inductive Wireless Charging

2014 ◽  
Vol 670-671 ◽  
pp. 1462-1466
Author(s):  
Dong Yue Li ◽  
Di Fei Liang ◽  
Qing Zhao
Keyword(s):  
Electromagnetic Induction ◽  
Coupling Efficiency ◽  
Transmission Efficiency ◽  
Secondary Coil ◽  
Wireless Charging ◽  
Primary Coil ◽  
Charging System ◽  
Ferrite Material ◽  
Nicuzn Ferrite ◽  
The Impact

Based on the principle of electromagnetic induction coupling of the wireless charging system, the main factors of the transmission efficiency is the coupling efficiency between the primary coil and the secondary coil. In order to improve the charging efficiency, NiCuZn ferrite material can be added in the wireless charging system. Thus, the wireless charging system can obtain high flux, and improve the transmission efficiency.

scholarly journals Design of an Intrinsically Safe Series-Series Compensation WPT System for Automotive LiDAR

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 86 ◽  
Author(s):  
Luiz Cardoso ◽  
Vítor Monteiro ◽  
José Pinto ◽  
Miguel Nogueira ◽  
Adérito Abreu ◽  
...  
Keyword(s):  
Low Power ◽  
Design Procedure ◽  
Power Converter ◽  
Open Circuit ◽  
Secondary Coil ◽  
Primary Circuit ◽  
Power Transfer ◽  
Coupling Coefficients ◽  
Primary Coil ◽  
Resonant Condition

The earliest and simplest impedance compensation technique used in inductive wireless power transfer (WPT) design is the series-series (SS) compensation circuit, which uses capacitors in series with both primary and secondary coils of an air-gapped transformer. Despite of its simplicity at the resonant condition, this configuration exhibits a major sensitivity to variations of the load attached to the secondary, especially when higher coupling coefficients are used in the design. In the extreme situation that the secondary coil is left at open circuit, the current at the primary coil may increase above the safety limits for either the power converter driving the primary coil or the components in the primary circuit, including the coil itself. An approach often used to minimize this problem is detuning, but this also reduces the electrical efficiency of the power transfer. In low power, fixed-distance stationary WPT, a fair trade-off between efficiency and safety must be verified. This paper aims to consolidate a simple design procedure for such a SS-compensation, exemplifying its use in the prototype of a WPT system for automotive light detection and ranging (LiDAR) equipment. The guidelines herein provided should equally apply to other low power applications.

scholarly journals Simulation Analysis of Wireless Power Transfer for Future Office Communication Systems

2019 ◽  
Vol 8 (9S) ◽  
pp. 533-538
Keyword(s):  
Output Power ◽  
Communication Systems ◽  
Wireless Power Transfer ◽  
Secondary Coil ◽  
Receiver Coil ◽  
Input Frequency ◽  
Power Transfer ◽  
Wireless Power ◽  
Primary Coil ◽  
Transmitter Coil

A Wireless Power Transfer system consists of a transmitter coil which is inductively coupled with secondary coil and is popular for wireless charging of future office communication system. Wireless power transfer is used in different applications ranging from mobile chargers to charging stations. In this paper simulation of Wireless Power Transfer for future office communication systems has been conducted over Maxwell 3d of Ansys electromagnetic suite. The input frequency of primary coil is varied from 1kHz -120kHz with respect to the change in resonant capacitance and observed that input frequency between 20kHz-30 kHz, the output power in secondary coil appears to be maximum at variable distances between transmitter coil and receiver coil. There is an improvement of 72% seen in the output power of secondary coil for 25kHz input frequency of primary coil as compared with 40kHz input frequency. This model can be helpful to design future Office Communication systems for charging the mobile phones, Laptops and to turn on the printer wirelessly.

Note on the Sensitiveness of the Skin to Weak Electric Currents, as compared with the Sensitiveness of a Telephone to the same Currents

1897 ◽  
Vol 21 ◽  
pp. 251-253
Author(s):  
John G. McKendrick
Keyword(s):  
Salt Solution ◽  
Induction Machine ◽  
Induction Coil ◽  
Secondary Coil ◽  
Primary Coil ◽  
Electric Currents ◽  
Current Passing ◽  
Variable Resistance ◽  
Electric Shocks ◽  
The Way

On 7th December last, I showed to the Society a method by which the skin might be stimulated by electric shocks from an induction coil corresponding in rhythm and intensity to the notes and chords of music given off by the phonograph. The pressures from the disk of the phonograph act on a variable resistance microphone transmitter. and the current passing through the latter also passes through the primary coil of an induction machine. From the secondary coil wires pass to two strips of platinum, immersed each in a beaker containing ·75 per cent. of salt solution. When the fingers are dipped into the salt solution, and the phonograph is set in motion, thrills are felt by the fingers corresponding to the intensity and rhythm of the music.Deeming it of interest to have some data regarding this experiment, I have modified it in the way shown in the diagram, and the E. M. F. of the battery employed and the resistances of the various pieces of the apparatus were measured. Into the circuit of the secondary coil, f, a resistance box, g, and a telephone, t, were introduced; and the circuit was completed when the fingers were immersed in the salt solution h, i. When the phonograph was in action and gave out a well-known military march, the thrills could be felt in the fingers, and at the same time the telephone, which was fixed in a stand at the level of the ear, gave out the music.

scholarly journals Non-Destructive Evaluation for Sectional Loss of External Tendon of Prestressed Concrete Structures Using Total Flux Leakage

2020 ◽  
Vol 10 (21) ◽  
pp. 7398
Author(s):  
Imjong Kwahk ◽  
Kwang-Yeun Park ◽  
Ji-Young Choi ◽  
Hungjoo Kwon ◽  
Changbin Joh
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Prestressed Concrete ◽  
Concrete Structures ◽  
Secondary Coil ◽  
Measured Signal ◽  
Level Energy ◽  
Primary Coil ◽  
Non Destructive Evaluation ◽  
Non Destructive

A non-destructive evaluation method is proposed to identify the sectional loss of the external tendon of prestressed concrete structures by detecting the change of the magnetic flux in the external tendon exposed to a magnetic field. The method uses a solenoid-shaped device with two coils: a primary coil for producing magnetic field and secondary coil for damage detection, wrapping the external tendon. A current applied to the primary coil in the device causes the magnetic field. Then, the change in the magnetic flux by the damage in the external tendon is detected by the variation of the voltage in the secondary coil in the device as the device moves along the tendon. An alternating current is applied to the primary coil to minimize the effect of the moving speed of the device. As a result, the damaged area can be detected with a low-level energy current. In addition, a wrapping solenoid-shaped device that is easy to disassemble and assemble was developed for in situ inspection. The measured signal from the secondary coil has a sinusoidal form with the same frequency as the applied current to the primary coil, and the peak curve of the measured signal provides enough information to detect the damage. It is shown that the proposed method can quantitatively identify one or multiple damaged-tendon locations as well as damages of at least 2 cm.

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