Wednesday, 4 March 2015

Application Of Mutual Induction


Principle of inductive coupling, with the Description field (A) and as a network model (B)
In the scope of the electromagnetic compatibility (EMC) is the mutual inductance referred to as magnetic coupling or inductive coupling, and describes the undesirable as a rule, magnetic coupling of adjacent electrical circuits. Caused by the current in a circuit magnetic flux, like the adjacent circuit diagram example of the circuit consisting of the AC voltage source U1, caused by magnetic coupling in the second circuit, shown with the AC voltage source U2, an additional induced source voltage, which in this circuit as an undesirable disturbance may occur.

The modeling can be implemented as appropriate as a field model (A) with the variable magnetic field, or equivalent to take place in the field of network theory by means of the mutual inductance M's, as shown in the right figure in case (B). The induced voltage against Ug_ {2} in the second conductor loop, which is due to the current i_ 1 from the first conductor loop is:

Ug_ {2} = M_ {s} \ cdot \ frac {\ mathrm {d} i_ 1} {\ mathrm {d} t}
Due to the symmetry of a mutual inductance Ms is a reciprocal four-terminal network.

Due to the higher energy density of the magnetic field as compared to the electric field, a relatively high power transmission may be achieved at intermediate frequencies by means of inductive coupling. This fact is exploited in transformers or electrical drive systems such as the gap motor.

In the field of communications, the inductive coupling is utilized as part of the inductive transmission, for example in the contactless signal transmission between the sensor signal of a sensor and display device or contactless chip cards, so-called RFID.