Hacking the IKEA 2000 Watt induction stove (5 parts)

[Mads Barnkob]

What do you guys think? Should I give it a try considering there the topology provides enough time for switching or look around for thinner copper tubing?

The only experience I have is with the "1000 Watt ZVS" Royer oscillator type of induction heater.
The resonant frequency  always drops when I insert a workpiece.  I wonder if the same is true for this "induction stove", even though it appears to be of a pll design.

1. What is your end goal for the size of coil that you describe?

2. I wonder how much the resonant frequency changes on the original induction stove when it is fully loaded.  Have you done any tests with and without a load to see how much it changes?

3.  If you do make the 100mm diameter coil that you describe,  how much change in frequency do you expect when it is fully loaded with a work piece?

Pete Stanaitis
---------------

1. I was hoping that it could be converted into a cheap induction heater for knife making, but the size of the work coil is much more dependant on having a inductance that matches the original cooking work coil, in order to make a 1:1 switchover between the coils.

2. The cooking coil resonates at 33 kHz in theory as seen above, and up in my first post you can see that it is measured to 22-25kHz at load, so assuming that it drops about 1/3 under load, the induction heater coil would resonate at 33 kHz, however that is a wishful scenario as it would have much lower coupling to the work piece than the cooking coil has to the pan.

3. No idea, depends on coupling and if it is a knife, that will not be very much but for practicality and survivability, it also needs a certain size to fit some insulating material there as the coil caries lethal currents not isolated from the supply.

[chjarup]

Hi,

I have measured on the Ikea hot plate for the purpose of external controlling the power. I identified Pin3 as 24Khz the pulse source for the power. And can control it via a relay. However the plate do a check if the pot is present or not, this is a problem when externally turned off (no pulses to hot plate) it will go into error (no pot present).

I can see from schematic that probably pin 1-2 is used for checking this pulse. So my plan is to try a constant voltage to bypass this check.

I have added the measurements (excel) I have done with my Picolog scope (1 channel).

Let me know if anyone can contribute to find out how it works, and howto bypass the pot check.

My ultimate goal is to external control the power, so it can be used for beer-brewing by regulating temperature in the pot

Br Carsten

Measurements.zip

[Mads Barnkob]

Hi Carsten and welcome to the forum

It is a shame that all those nice tables and oscilloscope shots are hidden inside that excel file, you should post them as pictures instead

But great job with mapping out the voltage during different programs and load conditions.

I have dusted off my unit and dragged it out from the corner of the work bench, as you can see on my previous post I am contemplating rebuilding it for induction heating for black smithing.

I fear the pot check is done with a single piece of code and current feedback, so that is it a part running outside of the main control loop and that there is no way to override it, but that is only my initial impression, takes some more experimenting and measurements to find out.

I approve of your idea to use it for beer brewing

[chjarup]

Thanks Mads.

My best guess for the "pot check" is that pin 1 or 2 (or differential voltage Pin1-2) is read by uControler.
I suspect that it is simply a digital input. So just require over a certain level to confirm the current pulse sent to the induction plate.
Altenatively it requires a transition from low to high (schmitt trigger input), just after the pulse is sent.
If so i guess 24Khz could be routed to pin 1 or 2 so there is always transitions available  .


Or maybe a constant HI voltage on pin 1 or 2 can do the trick around 2,5V (from pulse i measured on pin1)

Hopefully time in the christmas holidays to play with it.

[chjarup]

Tried constant 1V to pin1, this worked a while then took auto relay. so taking a look at IGBT 

Have now given up using the stove loop to control it.
I have made 20khz clock source and will try controlling it directly without any user interface on the stove. And just use a switch to use either manual mode or Auto controlled mode.

I will post results when available.

[petespaco]

I don't understand what the 3 recent pictures are intended to portray.
Are they components that have failed?

What does "then took auto relay" mean?

Pete Stanaiits

[Nelari]

I would like to make the TILLREDA programmable (I brew beer at home.) The idea is to hack the touch buttons so as to control the power with them – a Raspberry Pi or ESP8266 would simulate the touches.

So how does one open the case? Unscrewing the two visible screws on the bottom is not enough. Is there a third one under the sticker, and if yes, will unscrewing that one be enough?

Thank you in advance!

[Mads Barnkob]

I would like to make the TILLREDA programmable (I brew beer at home.) The idea is to hack the touch buttons so as to control the power with them – a Raspberry Pi or ESP8266 would simulate the touches.

So how does one open the case? Unscrewing the two visible screws on the bottom is not enough. Is there a third one under the sticker, and if yes, will unscrewing that one be enough?

Thank you in advance!

Hi Nelari

Either you can emulate the touch points directly, if you can get that to work, or instead look at the wires from the touch panel to the controller and reverse-engineer that and replace it directly with a new input controller.

There is 2 visible screws, 1 under the sticker and 4 screws hidden under the rubber feet.

Looking forward to hear about your results

[aq62386238]

is there still have any upload??

[Mads Barnkob]

is there still have any upload??

The following parts 3, 4 and 5 have been on hold due to moving to a new house, which included packing down all electronics and setting up a new lab. Check out my youtube channel to follow the progress on that

[aq62386238]

which website is Reply #18 that calculater

[Mads Barnkob]

which website is Reply #18 that calculater

These are from my website: http://kaizerpowerelectronics.dk/calculators/

Helical coil calculator: http://kaizerpowerelectronics.dk/calculators/helical-coil-calculator/

Spiral coil calculator: http://kaizerpowerelectronics.dk/calculators/spiral-coil-calculator/

[aq62386238]

thanks and when will you upload the rest of part i have wait so long 

[Mads Barnkob]

thanks and when will you upload the rest of part i have wait so long 

It not just a ready package to upload, I have to do the actual experiments first

I have been delayed by moving to a house and getting it in shape. My work desk is not far from having all the instruments on it again and wiring it all up and getting some storage/sorting in place around it, then you will see some smoking soldering irons and exploding silicon again

[aq62386238]

do you know how much is the Frequency of the igbt gate way 

[Mads Barnkob]

do you know how much is the Frequency of the igbt gate way

I have measured it to 22-25kHz at load from 1 to 9.

[aq62386238]

that means period is about 40u and how about the period width

[Mads Barnkob]

that means period is about 40u and how about the period width

You can read that out of the oscilloscope screenshots in the first post of this thread: https://highvoltageforum.net/index.php?topic=104.0

[aq62386238]

last question if i don't have1300V Tektronix P5200 and Tektronix A6909
can i  directly measure without this two have1300V Tektronix P5200 and Tektronix A6909

[Mads Barnkob]

Those instruments are differential probes and is just one way of measuring on a high voltage circuit without creating a dangerous fault loop to ground.

You should see this episode of EEVBlog on how not to blow up your oscilloscope: http://www.eevblog.com/2012/05/18/eevblog-279-how-not-to-blow-up-your-oscilloscope/