induction cooker circuit, design, theory, must watch

This video explain the physics, circuit and firmware design of commercial induction cookers. Ampere's Law, Maxwell Faraday Equation, eddy current, Lenz law are used to explained the details of the induction process.
schematic diagram:
drive.google.com/file/d/18yf9...
drive.google.com/file/d/1kQxF...

[@paradiselost9946]

thankyou for taking the effort to narrate this in english rather than simply resort to a bot. it makes it so much more enjoyable.

[@SiliconSoup]

Thank you. Sometimes I wonder whether I should use bot to replace my 2nd language, and with your encouragement, I know the effort is worthwhile.

[@jacobpetersen5662]

GREAT video! Thank you.... 99% of reviews and regular folks thing the advertised coils of burners are a lie. They do the water boil test and see a smaller coil where the boiling appears more aggressive. So they conclude it's a smaller coil than advertised. They simply do not know it's supposed to work this way. Thanks for explaining.

[@WesYarber]

Awesome video! Love the way you went through the schematic and broke it all down. I hope more people see this so I’m commenting to feed the algorithm!

[@SiliconSoup]

Nowadays it is harder to make popular video, and your help to influence the algorithm is very much appreciated.

[@BaneWilliams]

I always get frustrated that induction cooker have very big gaps between their settings. But the only good cooker that doesn't is $1,300!!! So expensive! I wondered why they don't just use a potentiometer, and this video helped explained why in most ones this is not the case.

[@ramchillarege1658]

Excellent rendition. Thank you. I am a EE from way back and now into CS.. but follow this stuff completely. Built many circuits in my time.. I like the comment about running at 75% power. Did not know that. Just got a Duxtop to play around with and was quite impressed by its performance today.

[@JA-vu1qt]

Great video! Recognise that SG accent immediately! ;) Thank you for the wonderful explanation.

[@SiliconSoup]

Hahaha, you are right.

[@jimhouse9961]

Thanks for the in depth explanation.

[@SiliconSoup]

Thank you for liking it

[@Egzoset]

Well, i was hoping to find a video about some « drop-wave control method » that reminds me of the former NTSC video signal: Holtek (Republic of China) "Low power continuous heating single IGBT induction cooker" 2023-Feb-1 Too bad it's got to go through such long path only to come back and get treated as hacker stuff. But this is actually a comforting read giving me hope for my specific kind of mission, in any case, so now that i found mention of a paper titled 'Holtek Application Note AN0591' it's clear to me what i want to search next!

[@MegaBanannaman]

Very nice 🎉

[@ianuragaggarwal]

Great video!

[@copernicofelinis]

Nice video. And LOL for the little stab at the end ;-)

[@SiliconSoup]

😁, armchair Theorist

[@josiasvandermerwe3710]

Awesome work!

[@SiliconSoup]

Thank you for appreciating it.

[@user-ce5kd1bs9o]

Thanks prof iam indonesian people very respect foru

[@SiliconSoup]

Thank you.

[@hariharasudhan3670]

Great Video

[@SiliconSoup]

I appreciate that you like it. Thanks

[@dwarakanathv2347]

Thanks very nice explanation

[@SiliconSoup]

I'm glad that you like it.

[@marcfruchtman9473]

Really great video. Thank you for making it! I would love to hear some of your commercial Induction cooker ideas!

[@SiliconSoup]

It is quite tough to manufacture induction cooker and compete with imports from China. This is because the entire supply chain is in China. Only those countries with tariff for import and low labor cost can make use of my design service to make profit.

[@marcfruchtman9473]

@@SiliconSoup Ah, I guess I need to become a manufacturer first then... sigh.

[@SiliconSoup]

@@marcfruchtman9473 You don't need to become a manufacturer, because China, South East Asia has many factories to manufacturer for you. What you need is the sales channels and sales track record to convince the factories to produce for you. And the factories will come to me for design :)

[@marcfruchtman9473]

@@SiliconSoup Well, I prefer having the design, and then presenting it to a manufacturer. But, I always want to make sure the prototype is good as well. As far as sales, I have a decent sales connection. Should I send you a business inquiry?

[@SiliconSoup]

How to establish communication if I don't wish to reveal my email publicly here, do you know?

[@doit.20]

wow about driving the induction coil with half bridge topology like inverter welding machine?

[@arnotecchannel7583]

Good to find you.. i love this video... But my induction cooker display error E0 and i tested all component except the one between the coil though is the same as the one at the IGPT terminal.. is look like a diode like.. i dont know, i need your help🙌

[@abhinavc91]

Loved your video!! Thank you so much for it. I’m interested to understand how the master board that takes user input communicates with the power board? Can we use arduino to talk to the power board instead of the touch pads?

[@SiliconSoup]

The master board communicates with the power board by i2c. Yes, you can use Arduino to control the power board, but you must know the format of data as they are proprietary .

[@Appregator]

Thanks. I was wondering if I could modify the detection circuit a bit. My induction cooker works fine until the smallest diameter pot (which is made for induction cooking) but it produces the E0 error, that means it is detecting no metal on the secondary side. I wondered where one would adjust the sensitivity as I think it only needs a slight sensitivity adjustment to be able to detect the smallest pot. Kind regards.

[@SiliconSoup]

I wouldn't recommend you to modify the detection circuit to fool the MCU. The smaller pot doesn't have enough load resistance, so if you manage to fool the MCU to do the induction, the feedback loop of power control may cause the back-emf to exceed the design value, and that may damage the IGBT (unless the protection is very robust).

[@shidongxu3410]

What is the maximum temperature of induction coil body ? Are the coils able to work at temperatures up to 200°C

[@user-jt3hx9hk7q]

Hi, really good video but I have a question please. I have an induction cooker but the power setting 400 or the temp setting 176F is too high for my cooking and burns the food. I want to adjust the duty cycle of the coil. how would you recommend I go about that?

[@SiliconSoup]

There are two types of low-power cooking, one is intermittent cooking, e.g. turn ON 4 seconds of 1000W and rest for 6 seconds to achieve an average of 400W, the other is continuous cooking, turn on 4 rectified half-sin-wave and turn off 6 rectified half-sin-wave. In either case, the close-loop algorithm ensures the 1000W is accurate, and the duty cycle of 4/10 is open-loop control. How do you want to adjust the duty cycle? Do you have access to the firmware and the necessary tool for modification?

[@kahgyt9491]

What is the purpose of commercial PIC's that have two or more IGBTs?

[@smferreiro2610]

Great video! I may need help designing one for a special project. Do you design for a cost?

[@SiliconSoup]

Yes I do, but only to those who are already in the appliance business.

[@willydarmawan1978]

This is awesome. I have one question, can we skip altogether the AC input and use DC instead? If we can, is it posible to modify off the shelf board to do it?

[@SiliconSoup]

If the DC is 325V, then yes, you can skip the AC altogether. But if the DC is 12V, then the coil inductance and resistance must be much smaller to achieve the same current by the lower switching voltage. Many component values must change.

[@francoisgervais1]

Is the schematic suitable for using « low power continuous heating » as seen in Holtek AN0591EN?

[@SiliconSoup]

No, the schematics are not the same. The version I presented uses HT45F0057 whereas the the low power continuous cooking uses HT45F0059. HT45F0059 has the low-power continuous cooking related registers. The external circuit to monitor temperature, voltage, current, surge for HT45F0057 and HT45F0059 are roughly the same though.

[@hoyw25]

Is the 300V DC rectified from the the diode bridge directly apply to the coil?

[@SiliconSoup]

At 5:00 is the schematic. There is a LC filter between the rectified voltage and the coil.

[@NextBigTrader]

Great video!! I am doing EE and I want to do low cost low energy consumption or higher efficient induction stove for my fyp, I just have started to look for the resoources, would you suggest me a good start??

[@SiliconSoup]

You can get information from www.holtek.com/page/applications/detail/WAS-21A1. I think this project is a bit too hard for FYP, because it involves high voltage, high current, embedded coding. Moreover, induction cooker is a non-isolated device, so it can't be connected to your PC directly for emulation, unless you modify the circuit and add a isolation transformer.

[@NextBigTrader]

​ @SiliconSoup Thanks for the feedback, I am not doing it just for grades but its a need of an hr in 3rd world countries, we have seen gas loadshading first time in our lives, its time ppl get better alternates to those expensive and high energy consumption stoves, if you could provide anymore help it would be appreciated

[@richardhayman4868]

So, it is an electrical interaction with the cookware (i.e., current resulting from a moving magnetic field), rather than the oscillating magnetic field itself interacting with the cookware. If that's the case, then it seems that the only requirement for my cookware would be that it resists electrical current, not that it is magnetic. What am I missing?

[@SiliconSoup]

Thank you for this good question.The magnetic field above the glass top attenuates quickly because of free-space permeability. The flux going into the cookware is weak and it cannot induce much current. If the cookware is made of magnetic material with high relative permeability, the flux gets multiplied and there induces more current for heating. In other words, the magnetic cookware enhances the coupling and increases the mutual inductance.

[@user-gb9jj6rg7v]

Hello, thanks for your detail explanation. please can i have that circuit you were explaining?

[@SiliconSoup]

I added the link under the description of the video.

[@user-gb9jj6rg7v]

@@SiliconSoup OK thanks

[@Logan880121]

Your video is very informative. Can you help to make the circuit ignore that is no cookware on it and still stay on, like yours on the video? Thanks.

[@SiliconSoup]

In my design/video, the controller sends out a single pulse to test the presence of the cookware, once every second. It doesn't ignore the absence of the cookware. This firmware is designed to produce the induction power according to the user setting. If the user sets 1600W, the close-loop algorithm makes sure the average VxI is 1600W. If I ignore the absence of the cookware, there is no load to absorb the power, and the close loop algorithm will attempt to push the current higher until the heat dissipated at the coil resistance is 1600W. But in the process, the back EMF will overshoot and trigger the protective mechanism for the IGBT. Therefore, even if I ignore the absence of cookware, the induction will stop.

[@Logan880121]

@@SiliconSoup in my case if I put not big enough cookware the controller goes to a fault mode and does not send power to the coil just for very short time. How can I overcome this problem?

[@SiliconSoup]

@@Logan880121 I want to be sure we are on the same page. Are you using HT45F0057, and do you have access to the source code and the ability to modify the source code? Or is this a general discussion? If you don't put enough cookware, the test pulse oscillates and sustain long, telling the firmware that no cookware is present; the firmware will not start the induction. On the other hand, during the cooking, if the cookware is removed suddenly, due to transformer effect, the current on the primary side will drop suddenly, and once the firmware detect the sudden drop in the current, it will stop the induction.

[@Logan880121]

@@SiliconSoup I don't have the firmware or the tools to flash the soc and it don't even has a marking on it. I am asking is there a way to trick the circuitry and modify the amprage sensing maybe make it adjustable. It seems to me you know every aspect of the circuit so maybe you can think a way to do this. I can use an arduino to modify the pot sensing. Thank you for you willingness to help.

[@SiliconSoup]

@@Logan880121 if you change the current sensing resistor, you may fool the controller. If you reduce the sensing resistor value to half, the control will be fooled to think the induction power is half of the actual power.

[@hoyw25]

The Resonance cirucit can drive the 300V DC up to 700V?

[@SiliconSoup]

At 8:00, the waveform shoots up above 1000V. The rating of the IGBT is above 1kV too.

[@IMPPump]

Could you pytell me Coil top white paper name and details please.. very nice and important video thanks

[@mikeb6389]

A single circular magnetic field results in unevenly heating the pan’s cooking surface with it being too hot in the center and too cool around the parameter. This condition causes the pan bottom to warp. There is a need for multiple overlapping wedge shaped magnetic fields arranged in a circle to evenly induce pan heating.

[@SiliconSoup]

Thanks for the info. When making the video, I was hoping to capture the water boiling starts from the centre of the pan first and then spread out to the circumference, but I was not able to capture that. So you are probably right, the coil is compensated to heat evenly.

[@mikeb6389]

@@SiliconSoup Sure, induction can boil water but it can’t sauté evenly multiple items in the pan like caramelizing onions.

[@philipgrice1026]

@@mikeb6389 Yes it can. You just need a well engineered, good quality induction range and compatible steel or iron saute pans. When you heat with gas you still need to preheat, or at least allow time for the heat to spread evenly across the pan bottom. You can do the same with steel or iron pans just by allowing time for the heat to migrate. the better the pan heat conductivity the easier this is, just the same as when heating with gas. My experience using 50 year old triple layer stainless steel RenaWare pans on both gas and induction hobs is that the induction heating is faster, has more accurate temperature control and does not turn on the automatic heat sensing fan over the range as it does not put waste heat into the air over the stove. Finally, induction hobs are much easier to keep clean than any gas range, and as my dear old Mum would say, cleanliness is next to godliness.

[@djoakeydoakey1076]

@@philipgrice1026 I got a kitchen that has a 3kw curved wok induction. We tried taste testing between using this and takeaway from Wok to Walk where they using large flame woks. Couldn't taste any difference.

[@mikemajoz4886]

Hello nice information , someone please explain at which point does the rectified AC input voltage gets inverted to AC back before been supplied to the Coil, I understand the coil uses AC

[@SiliconSoup]

The switching of IGBT invert the DC to AC. When the IGBT is on, current flows through the coil to the ground. When the IGBT is off, the current continue to flow and charge up the capacitor. Some point later the charged capacitor will discharge and the current reverse direction. So there is an alternating current in the coil.

[@mikemajoz4886]

@@SiliconSoup lemmi get to learn about IGBT switching and its inversion ability maybe i will understand better

[@sundararajann6007]

Why the power variation is in steps? Is it not possible to vary the power smoothly and continuously?

[@SiliconSoup]

Technically it is possible to vary the power smoothly. Maybe a smaller step of 50W is ok, but smaller than will become impractical to the user; to many presses are needed to reach the target power.

[@IMPPump]

Could you please tell me Coil top white paper name and details please.. very nice and important video thanks

[@SiliconSoup]

Sorry I use the induction coil as a component and don't know the details of the material.

[@woodcoast5026]

Actually the term EMF here is an arcane concept. The time varying current in the coil actually causes an Electric Field around and along the coil due to self inductance in units of volts per meter, that is the Maxwell Faraday law. The International Electro Technical commission has regulated the term EMF to the status of deprecated.

[@SiliconSoup]

You got the cause and effect wrong. Electric field causes charges to move (current), not the other way round. Maxwell Faraday equation is curl of E = - dB/dt.

[@woodcoast5026]

@@SiliconSoup You just wrote it there yourself curl of E = - dB/dt. The term - dB/dt is caused by the current. The current is caused by the the applied electric field and as a consequence there is an apposing electric field.

[@SiliconSoup]

To say that "The current is caused by the applied electric field", and "The time-varying current in the coil actually causes an Electric Field around and along the coil due to self-inductance in units of volts per meter" over-simply the whole induction process. How does the cookware contribute to the circuit behavior? The induction process is very complicated and therefore I devoted 0:50 to 3:30 to explain exactly what happens when various current and B-field interact with each other. If you are implying that all these can be summarized by Maxell Faraday law, then I disagree.

[@woodcoast5026]

@@SiliconSoup What I am identifying is that the video uses the term EMF, but the correct term is electric field.

[@SiliconSoup]

I am pretty sure I used EMF correctly. By the way, electric field and EMF are not the same thing.

[@SteveT_IoW_UK]

Excellent work! Many low cost hobs Pulse the output ON &OFF to achieve a lower average cooking power..its rubbish ! Boil-off- boil- off, plus its useless if you have say limited AC from a 1kw battery inverter or say only 500W of PV solar excess in a grid tied solar setup. I am looking to make a fully adjustable power range cct (esp32 mcpwm etc) which I can dymamically adjusts to only consume whatever free export solar power is available . Holtek do a continuously adjustable 300-3kw custom ic. Have you any comments ideas or embedded code to achieve wide, non pulsing adjustment of power level? I.e an mppt induction hob. It would be great if there was a decent open source project for an inductive hob..attractive given world's climate challenges and attraction of Solar cooking. Cheers and well done. Steve

[@SiliconSoup]

Low duty cycle pwm cannot swing the collector voltage to the ground, and switching on the IGBT while the collector (and capacitor) retain some voltage is very damaging to the IGBT, as shown at 8:52. Therefore for low-power cooking, instead of reducing the pwm duty cycle further, many resort to intermittent cooking (boil-off-boil-off). Holtek low power continuous heating is to overcome this problem. Basically, in stead of controlling the IGBT 3-sec on, 7-sec off, it does 3-halfwave on, 7 halfwave off. Halfwave is the rectified AC waveform. The source code is open, but not easy to understand. I strongly suggest you use Holtek solution, because the MCU is designed specifically for the induction cooker. It has OpAmp built-in for the current measurement, comparator for monitoring the coil voltage and triggering the IGBT at the appropriate timing. The latest model even have the IGBT driver built-in. Induction cooker firmware design is not easy. Commercial induction cooker power supply is non-isolated type, so you have to isolate the power supply before you can hook it up to the PC for emulate and debug.

[@aufoslab]

do u design these for a factory?

[@SiliconSoup]

Yes. With minor customization, they are ready for mass production

[@aufoslab]

@@SiliconSoup wow!

[@mesiroy1234]

Tbh i didnt undsr all thr elctrix terma. But i challmge to you Add in thermostat so can control by in a few degrees °

[@SiliconSoup]

The design has thermistors to monitor the IGBT and cookware temperatures. I may have missed your point, please elaborate.

[@soupflood]

One thing i could never properly cook on the induction stove (granted, it was an economy one) was fried chips or eggs. I now guess it was due to poor (thin) laminated pans. Maybe cast Iron would've performed much better.

[@SiliconSoup]

Probably

[@abdul-q-khan]

How can we modify AC versions to run on low amps???

[@SiliconSoup]

to redesign for a lower power cooker, say for tea-pot, we have to choose a different coil, adjust the timing and protection threshold in the firmware. It is quite a complicated process.

[@abdul-q-khan]

@@SiliconSoup Indeed it will be redesign work

[@dbrophy]

I'd like to commission someone to design and build a small batch of portable induction cooktops that are powered by 48V DC, in the 3kw - 5kw power range. It seems this might not be too difficult since the incoming AC source is first rectified to DC... Do you know anyone who might be able to take on this project?

[@SiliconSoup]

The solution I presented is 2000W. The AC source 230V supplies 8.7A, and the induction coil withstand a current in that order. For 48V to deliver 3kW, the coil the IGBT would have to withstand some 63A. Induction cooker design is a quite challenging because of high voltage, high current, EMI and firmware development. Sorry that I don't know anyone who might be able to take up this project. Thank you for watching the video.

[@abdul-q-khan]

Why the AC versions need higher amps while the DC induction heater needs low amps and high volts?!

[@SiliconSoup]

The induction power depends on the "transformer" rating, i.e. the coil's current carrying capability, the coil resistance, the turn ratio and load resistance. The higher the turn ratio, the higher the load resistance appears to the coil (n-square), and i2R is the power delivered to the load. As a designer, this is how I consider the power capability, not so much related to whether the source is AC or DC. Maybe there is an indirect link but I'm not aware.

[@myvideos1982]

Hi Silicon Soup, Thanks for a detailed video on induction cooker. I would like to discuss with you a R&D concept for electric fan. Could you please send your contact details to chat with you. Thanks. Sujay Salvi

[@SiliconSoup]

I don't wish to reveal my contact to the public, do you have any suggestions?

[@myvideos1982]

@@SiliconSoup telegram?

[@SiliconSoup]

Yes

[@mukesh4984]

can i get your email to reach you?

[@SiliconSoup]

algorithm.embedded at gmail