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Simulation of a wireless power system
Posted 16.04.2013, 09:11 GMT-4 Low-Frequency Electromagnetics Version 4.3a 11 Replies
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I am trying to simulate a wireless power system between two coils. The transmitting coil is connected parallel to a electric circuit consisting of a capacitor and a voltage source in parallel. I think this part is working.
The receiver coil is connected to another electric circuit consisting of a capacitor and a resistor.
I want to simulate the transmitted power, transfer efficiency, mutual inductance, resonance frequency. But I am not sure how to do this. Any help would be appreciated.
An other issue I came across is the current in the transmitting coil seem way to low. The voltage source is 50V AC and the current is only about 1A and the coil resistance is really low.
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Hi,
I had a look into your model. A hand calculation shows that the transmission coil has an inductance of 345 nH, this translates to a reactance of roughly 22 Ohms at 10 MHz. And you have to consider the skin effect at that frequency.
Cheers
Edgar
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Edgar J. Kaiser
www.emphys.com
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The transmission is suppose to be driven at resonance where the inductance and capacitance cancel out leaving just the ac resistance in the coil. I realized that I did not have the right resonance frequency so the problem with the low current is fixed.
Does Comsol take consideration of the skin effect automatically? Or do you have to put it in manually?
I have updated my model is the efficiency plot (1D plot group) made properly?
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The efficiency plot looks ok. The skin effect is considered, but you must take care about the meshing. You need a couple of elements across the skin depth. If the skin depth is too small to resolve it (probably the case with Cu at 10 MHz) by the mesh you can apply an impedance BC.
Cheers
Edgar
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Edgar J. Kaiser
www.emphys.com
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I tried to expand my model with multiple turn coils, using multiple turn coil domains. But I get an error I can't figure out. New model attached.
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You haven't assigned any materials.
With the Impedance BC you can avoid to mesh the interior of a conductor, but I am not sure if it is consistent with the multiturn coil domain.
Cheers
Edgar
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Edgar J. Kaiser
www.emphys.com
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Even with materials assigned I get the following error:
Circular variable dependency detected.
- Variable: mod1.mf.VCoil_2
- Geometry: 1
- Domain: 3
And I can't see why.
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it could be a variable name conflict, if you have not set up explicitely a circular dependence. If you have a non linear model that loops around, often to "open the circular reference" is to adda dependent variable for thsi variable and use that in the moeling
More on this in the Forum, try a search, and in the KB (knowledge Base)
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Good luck
Ivar
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Then I change the geometry a bit and put multi- turn coil domains, when i compute it i get the circular dependence error.
I tried the coil group domain and draw the geometry for each turn, but I didn't get the resonance frequency I was expecting.
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it looks like some issue with multiple circs and multiple coils, I would suggest that you send it over to "support" to see if they can have a closer look
Another point, for your coil circles, try to add a little air in-between, and do not have the two "just" adjacent with a point contact
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Good luck
Ivar
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But I get a uniform current distribution in all coils and that can't be true.
Does anyone know where this comes from?
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