Overview
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The geometry of transformers used for power supply circuits, etc., gets
larger as the current flowing through the transformer gets larger. A sheet
coil transformer is a transformer that is made flat by winding the coil
with thin sheets of metal. One vital element required in the design of
transformers is the inductance. The product development stage can be streamlined
by obtaining the inductance in advance through a simulation.
This note presents the use of a magnetic field analysis to obtain the inductance
of a coil sheet transformer. |
Magnet Flux Density Distribution
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The magnetic flux density distribution used to calculate the self-inductance
is indicated in Fig. 1. The magnetic flux is concentrated at the center
of the core, as indicated in the figure. The magnetic flux produced by
the current flowing through the coil is split in two from the center core
because the magnetic flux flows around the outer circumference of the core
and then back to the center of the core.
The magnetic flux density is larger at the corners inside of the core than
the outside of the core because the magnetic flux flows through the shortest
route of the core. |
Inductance
| The inductance of the sheet coil transformer is indicated in Table 1. The
self-inductance is 30.13μH and the leakage inductance is 0.832 μH,
which can be obtain from the relationship between the magnetic flux and
current. |
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