# Questions tagged [mutual-inductance]

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### Two questions about an AC electric circuit: Have I interpreted the dots correctly and where does the negative sign come from?

I asked this question over at the Physics Stack Exchange (https://physics.stackexchange.com/q/549814/263454) and I thought that it might stand a better chance of being answered here. So I am looking ...
70 views

### Thevenin equivalent with mutual inductance

I was practicing for the exam I found a problem in the book as follow : I want to find the voltage Vth so here is what I did : When finding the Vth I didn't ignore the dependant voltage source in ...
77 views

### Mutually coupled inductor modelling in cadence

I used two methods to model two mutually coupled coils. Method: 1) Using 'mind' cell from analogLib. It basically lets you define a coupling coefficient k value. Method:2) Using 'Xfmr' cell from ...
28 views

### Finding effective mutual inductance between a parallel inductors and a separate inductor

The effective inductance of two parallel coupled inductors can be calculated as $L_{eff} =\frac{ L_{1}L_{2} - M_{12}^2}{L_{1} + L_{2} - 2M_{12}}$ where $L_{eff}$ is the effective inductance ...
175 views

### How to design wireless charging coils so they are resonant?

I am continuing from this question: What can I use to increase efficiency of inductive wireless energy transfer instead of factory manufactured ferrite plates? I am trying to make somewhat efficient ...
66 views

### What can I use to increase efficiency of inductive wireless energy transfer instead of factory manufactured ferrite plates?

The Context I am a hobbyist with no education in electrical engineering. I am working on a DIY project trying to make water resistant rechargeable bicycle lights. I am doing this as a hobby for fun ...
28 views

### Impedance Parameters of Two-Port with Mutual Inductance

I am trying to calculate the impedance parameters of the two port shown below. I have no problem doing it without the mutual inductance, but I don't know how to incorporate it into my equations. ...
52 views

### Equivalent Circuit of identical transformers connected in parallel or series

I'm trying to figure out how to solve the equivalent circuit for 2 identical transformers connected in series or parallel on the primary and secondary. Mainly I want to know what the equivalent ...
149 views

### Transformer's Primary and Secondary Voltages

In general, which is the phase relationship between the primary and secondary voltages of an ideal transformer? Does it depends on the dot convention?
553 views

### Dot convention meaning

I have two questions about dot convention for the ideal transformer. I have understood how to use them in writing the voltage drops on the coils, but I have some doubts: 1) Which is the physical ...
141 views

### Autotransformer vs Inductive Divider

Which is the advantage of using an autotransformer instead of a simple inductive divider?
46 views

### Total phase inductance of three phase reactor

Consider a three phase reactor (inductor) using E-I or E-E laminations with phase winding on each limbs. Now inductance of R phase is given by: Lr=Lrr+Mry+Mrb Lrr: Self inductance of R-phase Mry: ...
66 views

### Mutual inductance

I am confused about derivation of the next formula The question is about Cm term. We have coupled inductors. The voltage across first coil is And I am ok with it. I understand it. I know ...
73 views

### Resultant voltage function through two opposing coils with mutual inductance

So my question is about the type of relationship in a particular circuit. I would like to know if it is linear or something else like a power. The circuit in question is a pair of adjacent, mutually ...
84 views

### Individual Three Phase Potential Transformers vs Three Potential Transformers in one case

If I had to select between Individual Three Phase Potential Transformers vs Three Potential Transformers in one case for a 600V system (which doesn't require many inches of spacing between phases to ...
171 views

### mutual inductance of BLDC motor

I want to use BLDC motor for charging the E-rickshaw for that I need to find the parameters of the motor. I have measured the Resistance and self-inductance of the motor but I am facing difficulties ...
70 views

### transformer voltage analysis

I'm trying to figure out the voltage and current (and subsequently power) of the resistor R2 in this circuit: simulate this circuit – Schematic created using CircuitLab The circuit is in ...
34 views

### How to achive mutual inductance and CM choke simulation in CircuitLab?

This site is using CircuitLab. In some SPICE programs it is possible to simulate CM choke. For example: Mutual Inductance is designated in a SPICE netlist by beginning the first word (label) of a ...
92 views

### Inductance of planar (spiral) coil near solid copper surface

I'm working on a electromagnetic levitation system, consisting of a flat spiral (planar) inductor positioned above a solid copper surface. The planar coil is parallel to the copper surface. (Consider ...
1k views

### Mutual inductance vs coupling coefficient

Question regarding this and this question about mutual inductance and coupling coefficient. I'm trying to analyse a two coil system: It consists of two coils like in the picture with 2 cm air gap ...
261 views

### Dot convention inductors in series: equation confusion

So I'm really confused with mutual inductors and dot convention. If your answer is going to be a link to any website I can assure you I read them all and that only left me more confused. So here are ...
50 views

### Deriving currents of parallel mutual inductors

This is possibly just a math question, not sure. In Irwin's textbook "Basic Engineering Circuit Analysis," 7e, there's a quick derivation for current in parallel inductors I don't follow: The KVL ...
434 views

### Simulating a variable mutual inductance model

Can we simulate a time varying mutual inductance in Matlab Simulink (or any other simulation tool). Matlab Simulink has a variable inductor, but I could not find not mutual inductor.
119 views

### Can I use rectified AC current to heat an object inside a induction coil?

The reason why I would like to use rectified AC is because I want to keep the magnetic field inside the coil unidirectional. A changing magnetic field induces current in the coil and vice versa. ...
370 views

### In an ideal transformer circuit, how is power transferred?

If I have a system of circuits like this: where Circuit 2 is providing power the Circuit 1, where does the energy come from? Do the inductors store energy? If not, how is power transferred from the ...
109 views

### How can I build my own wireless charger for my cellphone? [duplicate]

I am designing a wireless charger for my cellphone, Where my Primary coil is energised with 1.5V and 0.3A, Where I have used a transistor to turn it on and off at a frequency of 1Mhz. In the secondary ...
1k views

### A problem of ideal transformer

I am studying Fundamental of Electric Circuits by Alexander and Sadiku, and I am not able to solve a practice problem 13.9 about ideal transformer in Chapter 13 of the textbook. My answer is different ...
255 views

### Impedance matrix of a transmission line

I'm studying power systems and this question came up: if there are two transmission lines in series and I know the impedance matrix of each one (Zp is self-impedance and Zm is mutual impedance): ...
5k views

### Calculating Mutual Inductance in Parallel Wires

How would I calculate the mutual inductance (Lm) between parallel wires if I know the inductance per length of the wires and the separation between the wires?
1k views

### What happens when primary and secondary coil of an isolating(1:1) transformer are connected together(in parallel)?

I am considering the case of an isolating transformer because both the coils are identical. If we connect both of these in parallel, they will act as mutually linked inductors if they are connected in ...
98 views

### Mutual Inductance Between Two Same Axial Inductors

I was searching for few hours on this topic but I was unable to find any formula/research so I'm asking here. Please if this question is a duplicate let me know. Right now I do not have the equipment ...
177 views

### Coupling cofficient of coil in Resonant Series RLC Circuit

In the above diagram the circuit is in Series Resonance. Now we are asked to find the coupling coefficient K between coils L1 and L2. For which i first calculated L(equivalent) as follows : ...
374 views

### How to calculate the induced voltage of two electrically isolated coils (solenoids)?

Suppose I have the following setup: suppose then that: Self inductances L1,L2, the radius R, the number of windings (turns) N1, N2 are all given. V1 is given. The distance between the coils (...
101 views

### How to avoid mutual inductance at UHF frequencies?

I know that keeping inductors at right angles helps to avoid mutual inductance. But I can't find any information minimal spacing between inductors such that they have no mutual inductance. In my ...
168 views

### Finding equivalent impedance with ideal transformer

I'm working on finding the equivalent impedance of an ideal transformer. I want to derive the formula they are using in the book and lecture. Unfortunately when I try and get this equation by hand ...
282 views

### Total Inductance in transformer

Just a simple question, usually we can determine the sign of the mutual inductance M by seeing the position of the dots (as the current enters through it). But if you see the upper picture, we don't ...
1k views

### Equivalent Circuit for the RLC circuit to find the transfer function

I have a series RLC circuit with mutual inductance between the transmitter end and the receiver end. The circuit is I am trying to formulate a simple transfer function. I can formulate the ...
614 views

### Mutual inductance with open circuit, what's the voltage of the open circuit?

I'm currently struggling to solve this problem (problem below), I need to find U2(t) but I don't know how. I've only solved problems of this kind with closed circuit. Since the secondary loop is open ...
631 views

### Circuit feedback with mutual inductance on a toroid

I have been reviewing a circuit for the past few days and I am hoping to get some feedback to verify my thoughts as to how the circuit is working. This is a driving circuit for an ultrasonic cleaner ...
2k views

### If I used the primary coil as an inductor, does the secondary coil affect it?

I've read this question. It's about how to obtain the maximum inductance from a transformer: How do I use a transformer as an inductor? Now, I would like to use the primary coil only as an inductor ...
110 views

### Closed loop shapes with zero mutual inductance?

I have done numerous searches trying to find any mention of theory or experimentation done on determining closed current loop shapes that have zero mutual inductance and...no dice! Of course you can ...
168 views

### Calculate induced voltage in a wire due to mains wiring

I wish to calculate voltage induced in a short piece of wire of known length, due to mains household wiring carrying some current say 5 amps. My application is biomedical sensor wire and I can not use ...
2k views

### Induced voltages and flux within a transformer and their polarities

This is a multifaceted question, and is more to see if I understand what happens inside a transformer. I understand the general idea behind transformers: Alternating voltage that is applied to the ...
758 views

### Why is inductance negative in this triphase mutual inductor?

Suppose I have a threephase circuit with a mutual inductor on the first and second phase (V2 and V3). One way of solving the circuit (ie finding the phase currents) would be the following: convert the ...
363 views

### Does mutual inductance change individual inductances?

If I have two inductors, with inductances $L_1$ and $L_2$. I put them really close to each other to make a transformer. Are their individual inductances still $L_1$ and $L_2$? Or has the ...
331 views

### Dynamics of ideal transformers

Suppose I have the following ideal transformer circuit: According to the textbook that I was reading (Fundamentals of. Electric Circuits by Charles K. Alexander), V1/V2 = 1/n and I1/I2 = n. Does it ...
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### Sensing inductance change in high power (20 watts) wireless transmitter

First post here. I have a built a wireless power transmitter that consists of 2 flat spiral coils that transmit about 20 watts across a short distant to power a heating element. The coils inductance ...
1k views

### Trying to make a wireless charging circuit with an AC source

i'm making a project on wireless charging and according to my understanding if i attach a ac source with a coil and attach a voltmeter to an other coil i should get voltage on the voltmeter provided ...