Analog control of induction cooktops. Any one know of one or more products?

Home & Living
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About 5 months ago I purchased a portable 240VAC induction cook top to evaluate this type of cooking.
A lot of the hype about induction heating seems to be about how fast it can heat up.

Cooking water for a cuppa or a big mass rice serving, this could be big or small advantage depending on personalities? I’m not a person who needs an immediate response. Energy efficiency is my priority, not quick response times.

Observing what happens if I put some water in an induction compatible container and opt for temperature control and select 100 deg C, I see (and hear from relay clicking) that it always starts at full power and when the temperature is reached it boils, stops, boils again with resultant on off relay audible feedback on this appliance.

With a 1000W element, selecting 200W it is obvious that PWM (Pulse Width Modulation) control is being used in both power and temperature modes.

The problem with PWM is if the target mass is small it doesn’t always work.

I live alone and on my gas stove I can cook a single serve of rice, say 1/3 cup with 1/2 cup water on a gas stove in absorption mode, no problems.

On the Induction cooker, with the same saucepan, same portions on 200W (minimum power someone decided I should have) the rice is burnt on to the bottom of the saucepan before I can do not much. Bugger to clean up,

Have the same problems with pancakes on a 16cm skillet, just depends when in the PWM cycle you happen to pour it in.Power off when pouring in, no problems. Power on when pouring in, burnt on the bottom.

So PWM control of induction cooking is not for me.

Having gone PV solar and battery, I’m wondering what the pulse requirement on the inverter and battery are going to be long term for any PWM induction hardware.

I am also trying to live on solar off grid. Not there yet, but with a PWM induction bursts and reliability, 'm still pondering…

I’m an amateur radio hobbyist, I know that analog control of magnetic and electric fields is possible. I do this with my radios all the time with no reliability problems.

Which induction cook top manufacturer if any provides this level of control.
To compete with gas or resistive electric you will have to do it?

Speed is not the only goal. Give your customers analog control not incremental company/model specific fixed intervals. Life is analog, changes must take time!

Hers Hoping Paul

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Welcome to the community, @Pamal!

Good quality induction cooktops should have sufficiently fine PWM control that a small or large pan (set on the right sized burner) can simmer gently and constantly. It’s one of the things I’ve most appreciated about induction cooking in the ~11 years since I first got an induction cooktop. I never could achieve consistent simmering on any gas or electric cooktop I had before then.

However, the portable induction hobs often don’t have fine temperature / power control, and this sort of problem can result. In CHOICE’s latest portable induction hobs review,

you’ll see a fair bit of member feedback on the issue, even with hobs that got a high CHOICE expert rating.

In this thread on houzz, the posts by jwvideo cover the topic pretty thoroughly.

Eg, mentioning rice cooking:

There is another aspect, as well, and it particularly impacts fine heat adjustments on cheap portable units (a/k/a “portable induction cookers” or “PIC”). It also affects some ranges and full size cooktops, too. That aspect is how fine the pulse width modulation (“PWM”) is. PWM is the frequency with which the power is cycled on and off to produce lower heat settings. Induction hobs simulate lower power/lower heat by cycling the power on and off. With a high frequency of switching, the power goes on and off many times a second. The higher the frequency, the more stable the heat setting. With high frequency PWM, your simmering liquid is very still. OTOH, inexpensive PICs generally have very crude PWM. On them, the low setting will give you a couple of seconds of no power and a couple of seconds of full-on OMG hot boil, followed by totally off stillness for a couple of seconds, them back to OMG hot, etc. IME, that crude PWM has been the biggest problem I have had with cooking rice on cheap PICs.

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I have had two built in induction stoves. I have no idea if they were using PWM or not. I cannot tell you if the control was digital or analog.

Both were excellent for fast heating and fine control. In both the power on each burner had numerical one to ten plus boost. In both boost was very powerful (taking into account the size of the burner) and they could be turned down very low. In both I could do small pots of rice by absorption method and turn out perfect or turn something down so low it was only warm. You can melt chocolate easily at whatever rate you decide.

I am pretty sure neither had a minimum power anything like 200w but quite a bit less. In neither was there any mention of setting a given temperature, it is a given power setting and the temperature it reaches depends in what you are doing. If I am doing egg custard I can allow it to reach the correct temperature of (say) 85c or if frying steak it can hit 210c with no trouble, this is measured with an IR thermometer.

I have made pancakes many times and when the temperature was right it was up to me to pour, toss and remove at a constant speed to get correct cooking, I never had the problem of erratic or cycling temperature.

There are several threads here about induction stoves and none of the problems you have mentioned have come up, nor as far as I recall in any Choice review of them.

I strongly doubt that the behaviour you are getting is typical of induction stoves. My guess is you picked a bad example to try out the technology and it is not evaluating what you will get in any reasonable built in stove.

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Sounds like not enough water. Once the water starts to boil the rice is mostly suspended in the turbulent water. I cook rice on my induction hob a few times per week, and don’t suffer any burnt rice, even in the smallest saucepan. Generally you need to add a depth of water to twice the depth of the rice.
Bring it to boil, then let it simmer on lowest power setting, ie 1, for 10 mins, then let it sit for 10 mins with no power.
Times can vary depending on type of rice and how cooked you want it.

You could make twice as much as you need immediately, store the remainder in the fridge for use in the next few days.

Both my induction hobs have PWM controllers (on-off-on-off etc), and while inverter tech (always on at set power level, as used in modern air conditioners) would be better, PWM works well enough.

I’ve been off-grid for over 30 years, and induction is a great alternative to gas, which has become unnecessary except for one job- my large pressure cooker for sterilising jam jars etc is Aluminium and wont work on induction. I have tried steel plates under it, but thermal contact isn’t good enough.

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What make and model was it?

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Slightly off topic but I make rice using the microwave in a pyrex casserole (with lid) - Absorption method: 1 cup rice, 2 cups of hot stock.
I also have a portable induction hob which I use instead of the gas and have not had any issues (although I would prefer if it changed the power instead of turning on/off to simmer).

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Had the same problem with pancakes and Induction cooktop (new, changed from gas). Possibly lowering the heat after cooking one, then pouring in for a second pancake, might be a fix. I put it down to trial and error just as with a mocha pot setting which is a change from gas of course. But now works without problem for perfect coffee.

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That is making work for yourself. A better approach is to adjust the heating level after each one is done until you get it right then leave it and remember that setting for next time.

The pan needs to be fairly hot (butter smoking just slightly) when you pour and roll the batter, it should hiss and splutter a little as you pour. When the batter has set (the top goes matt) turn over. The first side ought to be browned nearly all over. When the second side is browned remove and start another. Do not go away and do something else at that point or the pan will get too hot, pour the next fairly quickly.

If it darkens too quickly before the batter is set turn down one notch. If it takes ages to brown turn it up one.

The idea is that the rate you heat the pan overall should match the rate required as you pour and turn. This is not the steady state of temperature the pan reaches if left empty but a dynamic rise and fall as each pour cools the pan that then heats up as the moisture partially evaporates.

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Sounds OK but I use no butter/oil and I do use the method you suggest for coffee making, saucepan cooking, etc. No extra work in lowering heat before pouring…and add in I am now using a crepe pan that is lighter than my previous gas-compatible fail-proof one, so it behaves a bit differently too. I am still working it out for best results. One burnt pancake does not a problem make! :grinning:

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If @Pamal is still with us, or for those considering a portable induction burner Choice has some warnings about which to avoid. It seems that quite a few portables fail the turn-down and/or the low heat test. OTOH few built in cooktops do. [member content]

Depending on which model Pamal tried there may be an answer there.

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Are you able to explain in a little more detail how this is working?

Is it possible there is some other explanation? IE is there is a fault or defect with your appliance and the audible switching sound a protective device operating? Using too small a pan/pot or a pot with too little ferromagnetic component can cause a malfunction. The coil and power electronics also generate heat and require adequate cooling.

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@isopeda Which print issue of Choice has these test results please?

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Welcome to the Community, @Kemmett!

I don’t get the print issue, so I don’t know when that portable induction cooktop review was first published. The online review says it was last updated in October 2023, but the original review (that would’ve been published in the print issue) could have been any time earlier.

If you have back issues of the magazine, you could check the index - which, if I remember correctly, is published at the end of each year, and covers just that year.

Or - @ScottOKeefe - can you answer Kemmett’s question?

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The last portable induction cooktop review is in the November 2021 Magazine. This is the ToC from this edition:

Screenshot_2023-11-26-20-06-17-564
Screenshot_2023-11-26-20-06-17-5641129×934 227 KB

The last full sized induction cooktops was April 2023. ToC of this edition is:

Screenshot_2023-11-26-20-08-55-489
Screenshot_2023-11-26-20-08-55-4891080×756 194 KB

Choice’s online content for portable and full sized cooktops was last updated in October 2023.

Portable induction cooktop:

(Link to reviews is on this page)

Full sized induction cooktops:

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The December 2023 edition of Choice Magazine has an updated review of portable induction cooktops.

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