The previous post explained the fundamental secrets behind developing a low cost yet effective induction cooktop at home, in this article we will see how this can be implemented by specifically calculating its crucial parameters such the resonance of its tuned LC circuit and the correct dimension of the coil wire for ensuring an optimal current handling capacity.
What is Resonance in Induction Heater LC Circuit
the capacitor within a tuned LC circuit is momentarily charged, the
capacitor tries to discharge and dump the accumulated charge over the
coil, the coil accepts the charge and stores the charge in the form of
magnetic field. But as soon as the capacitor has discharged in the
process, the coil develops an almost equivalent amount of charge in the
form of magnetic field and it now tries to force this back inside the
capacitor, although with an opposite polarity.
capacitor is again forced to charge but this time in the opposite
direction, and as soon as it's fully charged, it yet again tries to
empty itself across the coil, and this results in a back and forth
sharing of charge in the form of an oscillating current across the LC
The frequency of this oscillating current becomes the resonance frequency of the tuned LC circuit.
due to inherent losses the above oscillations eventually die out in the
course of time, and the frequency, the charge all come to an end after
But if the frequency is allowed to sustain
through an external frequency input, tuned at the same resonance level,
then that could ensure a permanent resonance effect being induced across
the LC circuit.
At resonance frequency we can expect the amplitude of the voltage oscillating across the LC circuit to be at the maximum level, resulting in the most efficient induction.
Therefore we can assume that to
implement a perfect resonance within an LC network for an induction
heater design we need to ensure the following crucial parameters:
1) A tuned LC circuit
2) And a matching frequency to sustain the LC circuit resonance.
This can be calculated using the following simple formula:
where L is in Henry and C is in Farad
If you don't want to go through the hassles of
calculating the resonance of the coil LC tank through formula, a much simpler option could
be to use the following software:
Calculating Wire Size for Induction Heater Work Coil
you have calculated the optimized values of L and C for the tank
circuit of the induction heater and evaluated the exact compatible frequency for the driver circuit, it's time
to calculate and fix the current handling capacity of the work coil and
Since the current involved within an
induction heater design could be substantially large, this parameter
cannot be ignored and must be correctly assigned to the LC circuit.
formulas for calculating wire sizes for an Induction wire size may be a
little difficult especially for the newcomers, and that's exactly why a
special software for the same has been enabled in this site, which any
interested hobbyist can use to dimension the right size wire for your induction cooktop circuit.