# Questions tagged [mutual-inductance]

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### Why are inverter bus bars made overlapping?

A lot of literature on bus bar design suggests that bus bars should be made to overlap or have equal area such as this. The reason they mention is the total stray inductance falls due to increase in ...
2k views

### What precisely is the numerical (or any) meaning of mutual inductance and, is it useful, representative (of something) or important?

When we consider two inductors that are magnetically coupled, we sometimes talk about mutual inductance. As an example, consider two inductors (such as 9 μH and 4 μH) that are 100% coupled and produce ...
29 views

### How will a PWM controlled relay affect a 800VA transformer on the primary side compared to the secondary side?

Application: A machine that seals boxes with plastic wrapping. The box is sealed by applying a heating element to the plastic for a few seconds. I have a 800VA (220VAC to 54VAC) transformer connected ...
211 views

### Mutual Inductance Practical Explanation

I can't understand why the Mutual Inductance is measured in Henry. The self inductance of a coil is the abillity that has a coil to create a magnetic field that produses a voltage on itself so to ...
62 views

### The function 'ddt' in LTspice frequency simulation

I have previously used the time derivative defined by LTspice in a time domain simulation, and I was wondering if this function could be used in frequency domain. If yes, what does it do exactly? I ...
51 views

### Taking into account the mutual inductive coupling analytically in LTSPICE

I am trying to take into account the mutual inductive coupling between three turns in LTspice differently. Instead of defining the inductive coupling coefficient K, I am using the analytical ...
21 views

### Mutual inductance and coupling coefficient

I need to know how I calculate the coupling coefficient and mutual inductance in series-parallel (SP) topology in wireless power transfer system work at a resonant frequency of 6.78 Mhz
54 views

### Can someone explain the dependence of coupling coefficient to inductance value to me? It seems counter intuitive

According to the formula $K=M/\sqrt{L_1 L_2}$, it seems that k is inversely proportional to the inductance values of the two coils. However, it seems to me that a coupling between two 2uH inductor ...
28 views

### Coupled inductors current equations

We have this circuit for homework and we must write down the equations of current for each loop and calculate currents i1 and i2. simulate this circuit – Schematic created using CircuitLab The ...
60 views

### Constructing Coupled Inductors with Particular Coupling Coefficient

I'm curious about the design of RF transformers with purposely designed non-unity coupling coefficient. I can see how this would be done in an IC, but how feasible is it at the discrete component ...
129 views

### Common-mode choke on LTSpice

Can someone suggest to me how to select a three-phase common-mode choke with self and mutual inductance in LTSpice?
109 views

### Confusion in modelling of total loop inductance of a rectangular loop

I was reading an article about partial and total loop inductances from this site and in a section where for calculation of total inductance of a rectangular loop is given as: In each portion of the ...
39 views

### Regarding Magnetic coupled circuit

Here, all the initial conditions are : i1(0-)=0A and i2(0-)=0A When t≥0, the current i1(t) and i2(t) starts flowing. From my assumption, steady state value of i1(t) is 10A but what happens to i2(t)? ...
46 views

### Magnetic coupled circuit

I am solving this circuit and according to the dot convension,the j6 ohm and j8 ohm have opposite polarities. Applying kvl to both loops, I got, 10 = j5I1 - j3I2 + j3I2 Or, I1 = -j2 A But I am stuck ...
57 views

### Electrical conductivity circuit help, with two solenoids

I have a project im working on but cant seem to figure out the basic of the circuit. The principal of the circuit is two solenoids wrapped around a chemistry glass making a magnetic field. The purpose ...
91 views

### Why does LTSpice take so long to solve this circuit?

Using a technique to model transformers for a wide frequency range, I got at a circuit like this one: https://1drv.ms/u/s!AhR86nrv-ZA7ivoz9BZIoXfs4GwXIQ?e=L6mcKd LTSpice takes a long time to solve ...
52 views

### Calculating inductance using PEEC Model

I'm learning of how inductance is modeled in wires by breaking them down into smaller filaments. I don't understand how the different inductances add up. Say we want to calculate the total inductance ...
53 views

### Why Doesn't the Current in a Transformer Diverge?

I just started learning about mutual inductance and transformers, and I haven't been able to find the answer to this question. I suspect it's really basic, and that I'm just missing some understanding....
70 views

### Understanding of coupling coefficient and power transfer efficiency

I am a bit confused about my derivation to get power efficiency from the coupling coefficient. The coupling coefficient $k=M/\sqrt{L_1L_2}$.  V_2=M\frac{dI_1}{dt}=L_2\frac{dI_2}{dt}\\ V_1=M\frac{...
111 views

### Analysis of three phase star star connected transformer

What is going on this circuit(below) and what would be current measured by ammeter(zero or non zero)? Description- These two transformers winding are star star connected and a balance sinusoidal ...
55 views

### Loop inside a loop, where is the mutual inductance greatest?

I had a question while working a problem as to where the mutual inductance of a circular loop inside a rectangular loop is greatest. Is it at the center, because the magnetic field of all four wire ...
65 views

### Mutual inductive coupling and proximity effects

I am struggling a bit to differentiate between proximity effect and mutual inductive coupling. Proximity effect: if a conductor is carrying an alternative current the nearby conductors will witness an ...
83 views

### Why did the designer of this flyback circuit choose to set the oscillation frequency as high as possible with the smallest resistor tolerated?

This circuit uses a current mode controller with an oscillation frequency response of: In the circuit, the designer chose to use a 10nF cap, with a 680 ohm timing resistor, which according to the ...
83 views

### Wirless Power Tansfer Circuit

Hello so my university is closed because of covid. I am allowed one day into their labs to build and test my WPT device. My Tx is very large compared to my Rx. I have tested their inductance with a ...
184 views

### 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 ...
417 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 ...
597 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 ...
233 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 ...
86 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 ...
155 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 ...
333 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?
917 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 ...
298 views

### Autotransformer vs Inductive Divider

Which is the advantage of using an autotransformer instead of a simple inductive divider?
55 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: ...
84 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 ...
129 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 ...
95 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 ...
320 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 ...
90 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 ...
82 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 ...
124 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 ...
2k 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 ...
265 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 ...
61 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 ...
806 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.
155 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. ...
762 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 ...
145 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 ...