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I am new to electronics So I need help to understand the working of the induction cooker circuit. I searched on the google but could not find the simple answer. Below is the attached circuit commonly found in home based induction stoves but it seems to be totally different from the theoratical circuit on the internet. In this circuit, as per my understanding, the ac supply is passed to rectifier that converts it to pulsating DC C2 capacitor is used to smooth the voltage and then this voltage is injected to the mosfet where low voltage signal can be used to control the mosfet(switch). If the switch is on then the induction coil starts. So its all the process is to convert AC to DC and then using the switch to on off the circuit. enter image description here

My quetions are.

  1. What are the purpose of capcitor C1 and C3 and inductor L1 in this circuit?
  2. Does the induction cooker main coil is operated on DC Voltage?
  3. Why the fuse blows when I directly provide the AC voltage to Main induction coil L2. Shouldn't Magnectic field arround the coil provide some resistance for the current flowing through it.

If I am getting something wrong, please correct me. Would be greatful for any help. Thanks in advance.

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  • \$\begingroup\$ There are no component part numbers on your schematic. \$\endgroup\$ – Transistor Dec 12 '19 at 12:19
  • \$\begingroup\$ The coil doesn't operate at DC. If it did it wouldn't induce into the pan on the cooker top. the signal line will be a high frequency square wave of probably tens of kHz. \$\endgroup\$ – Andy aka Dec 12 '19 at 12:36
  • \$\begingroup\$ It is a concept drawing. I think he gets at least 1/2 gold star for including reference designators for the components in question. \$\endgroup\$ – AnalogKid Dec 12 '19 at 12:46
  • \$\begingroup\$ electronicsforu.com/resources/induction-cooker-working/2 \$\endgroup\$ – Andy aka Dec 12 '19 at 12:47
  • \$\begingroup\$ May I suggest, that if you are new to electronics, you "start at the beginning" with Tony Kuphaldt's Lessons in Electric Circuits. There is much to learn before tackling something as complex as an induction heater. \$\endgroup\$ – rdtsc Dec 12 '19 at 13:15
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C1 is a noise filter.

L1 C2 helping with smoothing DC.

C3 & L2(Transformer Primary) builds oscillations required for Induction. (LC oscillator tank)

MOSFET / IGBT can be used as a switch, how fast its gate is switched decides frequency.

combination of c3, L2 & solid-state switch produces High-frequency AC.

Metallic cookware placed on L2 (with some gap) acts as a secondary, this produces eddy current which is responsible for heat generation.

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C1 is a noise filter.

C3 forms a resonant circuit with L2.

L2 ("the main coil") runs on high frequency AC. The MOSFET is not a simple DC switch. It is driven by the controller with a high frequency square wave. Popular Mechanics magazine says typical operating frequencies are in the 20 kHz - 75 kHz range.

https://www.popularmechanics.com/home/how-to/a5965/how-induction-stoves-work-elements-of-the-cooktop/

Yes, the impedance of L2 limits the current through it, but at 60 Hz that impedance is very low so the current can be very high.

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  • \$\begingroup\$ "The IGBT chops up the electric current's wavelengths" - nobody's getting any fraction of a gold star for that line, I hope! \$\endgroup\$ – Finbarr Dec 12 '19 at 14:50
  • \$\begingroup\$ @AnalogKid, First of all thank you very much for clearly answering my each question. Yes, it is just a concept drawing and missing other detailed info about each component. But I am just curious about electronics gadget's working. So I was only concerned about the purpose of each component in the circuit. Thanks again for your time. :) \$\endgroup\$ – Amanjot Singh Dec 12 '19 at 14:57

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