# Questions tagged [magnetic-flux]

The sum normal component of a magnetic field passing through a surface.

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### Calculation of transformer inductance value

I am trying to find a way to calculate the primary and secondary inductance of transformer. I learned that it is changing from one topology to another. My topology is Phase-Shifted Full-Bridge ...
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### Does hysteresis still occur if saturation is not achieved in a core?

When looking at a BH curve, what happens if the H field is raised to some level below saturation. For example we apply an H field that is only half way to saturation. On a BH plot this will trace a ...
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### Can a slanted magnetic field be created with this insulated stranded wire arrangement?

I am considering building a small-scale experimental coil gun because I have an idea of how a magnetized projectile could be rotated while it is traveling through the coil(s), similar to how a bullet ...
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### Can the formula for magnetic field intensity be used for cores with varying cross sectional area?

Can the formula H = NI/l be used for cores with varying cross sectional areas?
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### Equivalent inductance seen from a winding

I would be having a little trouble understanding how to do this problem of magnetic circuits. It asks me to calculate the equivalent inductance seen from winding N2. I know how to calculate the ...
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### High magnetic permeability material at 100MHz

I'm doing experiments as a hobby and was trying to find a material with good (very good) magnetic permeability at least at 100 MHz (higher frequencies are even better). Ideally the material would have ...
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### Magnetic lines geometry inside a dc motor

How are the magnetic lines of the armature and stator field distributed? Are they always perpendicular to each other or do they align in every half cycle (while the rotor is rotating)? I suppose that ...
91 views

### Magnetic Force Equation

Is there any equation where I can take a metal with a given volume/mass, with a certain amount of magnetic flux in it (in teslas) and find out how much force (in newtons) it exerts a given distance ...
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### Example problem of induced emf in a 100 turn coil by a 100 turn coil which has 90kHz sin wave input voltage

Main Question: Let's say there are two coils each 100 turn and diameter 30 mm, And the second coil is perpendicular to the first coil's magnetic field (placed both coils next to each other; we can see ...
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### If I have two magnets repelling each other, will they always form a peak in the middle?

If I have two identical magnets, aligned so they repel each other a distance of X apart and at a height of Z I have Hall effect sensor, the peak of the magnetic field sensed will be at the distance X/...
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### Example problem of induced emf in a coil travelling with some velocity and perpendicular to the earth's magnetic field

I have a example problem which I created myself just out of curiosity, Question: Let's say a copper wire coil(20mm dimeter(r=10mm)) of 3 turns(N=3) is moving along the surface(Note-coil is not ...
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### Magnetic field generated by a current-carrying wire

When dealing with the magnetic field generated by a current-carrying wire, the formula for the magnetic flux density is B = μi/2π·d, but what if the point is located on the wire it self? In this case ...
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### Identifying and designing coils for generating parallel magnetic fields with smooth gradients

What is this coil called (see image) (blue line is field, blue circle is clockwise oriented coil, red circle is counter-clockwise oriented coil), and are there any tools that help design it? ...
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### What is the consideration when installing or replacing the shaft of an induction motor?

Here are two picture of my washing machine's motor. I am not sure whether you still have such that machine in your country. It is a top loading washing machine's washing motor (a another smaller one ...
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### Direction of magnetic flux in magnetic circuit

In the first picture attached,we see a ring shaped magnetic circuit with two magnetomotive forces. Now,in the solution to this problem,it was said that the two sources generate flux in the same ...
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### Would a electromagnet be used to detect the presence of a permanent magnet?

I was wondering if there is any way I could use an electromagnet to detect the presence of a permanent magnet. I am specifically thinking of using a planar type small coil. Maybe use a core or ...
1 vote
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### How do steel laminations reduce eddy current losses in a transformer?

All online materials I have read so far state that laminations reduce eddy currents but how is this so? I mean why would currents be smaller this way than having a big block of unlaminated iron core ...
282 views

### How to measure flux in transformer in LTspice?

I wish to check the flux through a transformer core in my LTspice simulation. I have set up a push-pull converter simulation using a transformer with a turns ratio of 1 : 1.1, a supply voltage of 12 V ...
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### Problem acquiring B-H curve

I'm trying to acquire the BH curve of a toroidal current transformer in saturation, having the primary and secondary current. The formulas I am using are: B = (1/NsS) Integral(Vs(t)dt) H = (Ip*Np)/l \$...
1 vote
396 views

### Is ferrite core inductance similar to iron?

My 0.5" (1/2 inch) iron core inductor did not have a high inductance due to (I assume) eddy currents. Theory seems to suggest that ferrite cores are the ticket to increase inductance. I ordered ...
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### Magnetic interaction between resolver & motor windings?

Scenario: Synchronous electric motor whose rotor position is measured by a resolver. Won't the magnetic field created by the motor stator & rotor, link with the primary & secondary windings ...
141 views

### Expression vectorial to magnetic field $\vec{H}$ in infinite semi-plane conductor

I have some difficult to figure out the second expression about the contribution of magnetic field as you see below: Problem: A wire conductor, infinite long (Z axis), conduct a current constant equal ...
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### Does continuity equation applies for magnetic charge and magnetic current?

I wonder if, since we are capable of defining a charge and some magnetic currents, we can apply the continuity equation to them in such a way that: \frac{\partial \rho_{\text{mag}}}{\...
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### PMSM Motor Permanent Magnet Flux Linkage

I want to know the Permanent Magnet Flux Linkage of my PMSM motor. I need that to implement a Speed control for my motor. Without this value I cannot do the necessary calculations to make the motor ...
1 vote
205 views

### How is the holding force of this electromagnet so large?

I am designing a system that uses the magnetic force to fix an object in its place. I plan to connect an I-core to my object and fix it to a fixed C-core by letting a magnetic flux flow through both ...
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### Why are induction motor cores laminated to prevent eddy currents?

The permeable iron alloy cores of induction motor rotors are formed from thin laminated sheets, designed to prevent eddy current flow and thus "reduce losses", but isn't the whole point of ...
125 views

### Does operating an iron core near its saturation field reduce performance?

I am sizing an iron core for an electromagnet, and I am uncertain if there are disadvantages to operating close to the saturation flux density. If the saturation field is X, would it be better (more ...
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### Why we use constant value of magnetic flux in transformers

I have a confusion regarding the formulas of the transformer. I have seen in many places people using a constant value of the flux B in the transformer equation: turns per volt=1/(1.44 x Bmax x A x f)...
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### How Far Should Mu Metal Be From An Inductor to Leave Its Internal Behavior Unchanged?

I have an air core inductor. Since its magnetic field will be large, and it will turn on and off rapidly, I assume it will make a lot of noise. I don't want that noise to disturb the PCB's nearby, so ...
1 vote
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### Use nickel as a flux ring

I'm designing an outrunner for a specific application. Rather than use steel to hold the magnets in the flux ring, can pure nickel be used? Nickel is a magnetic material, but has decent oxidation ...
1k views

### Calculate motor flux of a PMSM

I am struggling with the calculation of the motor flux for a RPX22-042V24 PMSM. I know back EMF, Torque constant and several other values from the datasheet. But I found different ways to calculate ...
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### Want someone to review my Helmholtz coil design to see if I am missing something obvious before I fabricate it?

I am planning to construct a Helmholtz coil and wanted electrical engineers to take a look just so I know I am not overlooking anything. The max field strength I am looking for is 200 Gauss. I ran ...
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### What role does permanent magnet strength play in BLDC/PMSM performance?

It seems to me like stronger permanent magnets are preferred by motor designers, but my current understanding of what role they play in performance is fuzzy at best. I would assume that stronger ...
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### Selection of the utilization factor for the calculation of the transformer for the DAB converter

DAB Converter: When calculating the parameters of a transformer, it is necessary to know the utilization factor of the transformer (Ku). Here it is 0.3. The utilization factor of the transformer ...
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### flux density value in a transformer

I am working on making a simple step-down transformer whose input will be 220V and output will be 12 V. The formula I have seen for calculating the turns per volt being calculated by the following ...
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### Understanding voltage in simple electromagnet and DC motors

I made a simple electromagnet with enameled copper wire wrapped many times around a metal allen wrench. I attached the electromagnet to my PSU and it works great, but I do not understand the voltage ...
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### How can the magnetic field produced by the shading ring of a solenoid valve be 90° out of phase compared to the coil magnetic field?

I am trying to understand how the shading ring in solenoid valves is able to produce a 90° out phase magnetic field compared to the coil's magnetic field. The logic seems different from a shaded pole ...
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1 vote
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### Parallel magnetic circuit with 2 air gaps

I have the following ferromagnetic core. N = 300 core thickness = 5 cm relative permeability = 2000 the air gap's efective area rises 5%. 1 A going through the coil I need to know the flux going ...
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### EMF Sensors - Tri-axial Inductors vs Tri-axial Magnetometers

I took apart a bunch of EMF sensors (such as this one) and found that almost all of them instead of having a magnetometer inside, have usually three inductors. In the case I just shared, it has 3 33mH ...
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### Equation relating alternating magnetic field strength to induced voltage in search coil

I have a search coil (loop area A, N turns) placed normal to an alternating magnetic field with equation B(t)=Bp.sin(2.pi.f.t), B=field strength at time t, Bp=peak field strength, f=frequency, t=time. ...
1 vote
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### How can a constant flux machine store varying amounts of energy in its magnetic field?

A transformer is said to be a constant (i.e., constant RMS) flux machine. If load currents increase, how can the transformer store more energy in its magnetic field if it cannot accomodate a higher ...
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### Induced current on secondary winding in transformer reinduce current in primary winding?

I am trying to understand what happens when PCB lines are magnetically coupled and form transformers and affect currents or distort voltages that is carried over them. I know if primary side in ...
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### About the I1N1 = I2N2 equation

I have a silly question about this equation which is very frequently used in ideal transformer relations. If I draw the electrical equivalent circuit of the core, then the MMFs of 2 coils N1I1 would ...
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### Ideal transformers - why doesn't voltage drop for primary winding account for secondary current?

The first figure below from Power Systems Analysis (Grainger/Stevenson/Chang) shows an ideal transformer. The authors write v1 as shown. Later on in the same chapter, however, the authors write v1 as ...
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### Is power dissipation constant for a given mass of copper generating a given magnetic field?

What I mean, is that for a given field and a given mass of copper coil, power dissipation is independent of the form of that copper, whether thick wires or thin. Is it true?
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### Does infinite magnetic permeability (e.g. for an ideal transformer) violate conservation of energy?

The ideal transformer is supposed to have infinite magnetic permeability. Creating infinite magnetic field lines from a finite applied field sounds like... a violation of conservation of energy or ...
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### Geometry of magnetic flux in EM induction

Image of surface, shown in blue, through which magnetic flux passes, indicating the boundary in red, in motion at velocity v: In the Wikipedia article on Magnetic Flux, it is said that an EMF is ...
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### What could be the reason behind the variation in coil size inside Apple's Magic Trackpad 2 haptic motor?

**Disclaimer: This is a speculative question looking for electromagnetic coil advice, using Apple construction decisions as the talking point. Looking through iFixit's teardown of the Apple Magic ...
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