Conflicting results in Transient analysis
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A coul and magnet are modelled the same as transient translational motion problem 7.3 v15. One model has a north facing pole and another model has a south facing pole. The coil has a terminal and the excitation is an external with a winding, resistor and earth. When modelled with the coil terminal current in the same direction as the current density it is noted that the phase relationship between current and induced voltage is 180° out of phase with the north facing magnet and in phase with the south facing magnet. According to the Curl rule then the current and current density are defined. Initially the magnet is approaching the coil. In the case of the north or south facing magnet an induced current is created causing the magnetic field in opposition to the approaching magnet. In the expected result we would find that phase relationship between induced voltage and current according to Maxwell's law would be 180° out and in relationship to Lenz's law it would be in phase. We cannot find any indications as to whether Maxwell or Lenz's law is used to determine the induced voltage and we take it that J is conventional current which is the movement of the positive charge carriers. Because of the results of the north and south approaching magnet being different we cannot determine any further. Please provide assistance. You could inform us that:
1) J is positive charge carriers or negative
2) Whether the induced current uses Lenz's law or not
If you require drawings please do not hesitate to notify us. As we have noted that you don't open any attachments. Then please let us know how to provide.
Hi @igorgordeev I don't have access to the problem 7.3 V15 you are talking about. Please provide some screenshots of the problem to interpret it better.
Provide some screenshots of your model aswell.
Please use the image option and not the Attachment option while sharing the screenshots.
Regards
Navya
Magnet moving upward with velocity through a coil
This is the external circuit for the project
I and J are in the same direction
North facing upwards
This is the result. It due to J is positive and induced voltage is negative. I and J are in the same direction
This time the magnet direction is south pole upwards and I and J are in the same direction
This is the result. It(current) due to J is in the same direction as the voltage.
The expected result is that the direction of I and J for the north versus the south pole would be opposite and that the induced voltage would be opposite of the current in both instances. This would then follow Faraday's law
Cannot determine by the conflicting results of the induced voltage, I and J whether the Ansys Electronics program is using Faraday's law or Lenz's law. Can you help to determine this please
For current and voltage the meter indicates electron flow. The current and voltage are in the same direction. This behaviour should be represented in Ansys. In the results for south pole upward facing the current due to J (field calculator) is in the same direction as the voltage and the current through the coil winding (external circuit) is 180┬░ out of phase.
Here is some information.
1).Induced current direction
Please see below. The induced current follows the LentzÔÇÖs law exactly. Please use right-hand rule to determine the current direction and for either of north pole or south pole moving of this simulation, the magnetic field created by the induced current opposes changes in the initial magnetic field.
2). CoilTerminal direction
We use ÔÇ£externalÔÇØ as winding type and it presents the BackEMF direction (voltage direction), not for current, because we use external circuit.
3). Power generation in the simulation
In this simulation, we calculate induced current and voltage with magnet motion, and it is generating operation. Thus, the direction of the induced current is always opposite to the voltage direction to present the power generation. This current is generating and conventional internal current.
Thanks
HDLI
Please note within the text "...assign the coil terminal excitation by specifying the orientation of the current with respect to the coil terminal..." (page 2931 Maxwell Help)
Hello could you also graph current due to current density(field calculator). Please consider the following....the coil terminal is a thin section removed from the coil and a resistance is placed there so there is still a closed loop. The magnet is moving upward and is producing a force on the electrons which cause a depletion on one side of the section and excess electrons on the other. A field E is created across the resistor which is from positive to the excess of negative electrons and a voltage which is from excess negative electrons to positive. The reason that this occurs is because the magnet is moving and continues while a force on the magnet is maintained causing the movement of electrons. The reason to have Lenz law (voltage opposite to the sign of the voltage due to Faraday law) is so that current and voltage are in phase ....if this were not so then generators would not work. Please refer to the drawing of the coil magnet and circuit submitted earlier. I connect a meter (set for DC) to a coil and bring a magnet towards it...the sign of both current and voltage are the same if they were 180 degrees apart then the signs would be opposite ......please try it.
When this formula is used particularly for south pole facing upwards then the induced current due to J and current do not match.
I have considered your comments and believe this is what you are trying to say. As the coil is not a closed loop then electric field and voltage can be determined across the windings. The best indicator of the correct notation is still by using a voltmeter. This method determined that the sign of current and voltage must be the same and not opposite (180┬░ phase difference).
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