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Induction Cooker Modification

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riccardo

Member
Hi,

I have some common induction cookers that I would like to modify to keep running while no pan is on the coil. This is so I can have the large field present and just heat a small object somewhere within it.

Attached is part of the schematic and description of a typical cooker.

The normal operation involves it pulsing the coil and measuring the ringing voltage to determine if a pan is present or not. If so, it then powers the coil fully. If the pan is removed, it powers off the coil and returns to pinging it every 500ms or so.

I am thinking if I just alter some of the resistors that divide the coil voltage (IGBT Vce), then I can trick the microcontroller into thinking it it has a pan present. Now, this of course might lead to excess voltage on the IGBT, but I can change the IGBT or add some other protection to accommodate this hopefully.

Could anyone offer any feedback on this idea or alternatives?


induction_cooker2.png
"4.9.4 Over-driving and cookware-removed detection
When cooking is in progress, the voltage of IGBT Vce will become higher and exceed the limit if the IGBT is over driving (PWM pulse width is too large) or the cookware is removed. This error condition is shown in Figure 16. To monitor this situation, ADC ISR continuously compares the IGBT Vce voltage with the set threshold and updates the status instantly. The Fire Control task checks the status in a 500 ms period, and will stop firing and then restart the fire control process if an error condition is confirmed."
induction_cooker.png
 

shortbus=

Well-Known Member
Most Helpful Member
Not really up on this so probably wrong. But doesn't the presence of a pan also act somewhat like a heat sink for the induction coils? Wouldn't they overheat if a smaller or no object was present for any amount of time? For smaller objects wouldn't a smaller coil area be needed?
 

riccardo

Member
No. It does not work like that.
A smaller coil is generally better to heat small things but that is not exactly what I am trying to do.
 
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