Noisy induction cooktop when on inverter power

DIY
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1

An induction cooktop makes allot more noise when running on the Multiplus inverter compared to the grid. What could be causing this?

2

Inverter’s way of generating the sinewave.
It seems that the cooktop doesn’t like the inverter’s PWM frequency range, its harmonics and THD.
Of course, these must be subject of inverter’s certification, but one can only guess…

The inverter is using a square wave with different duty cycle to generate the sine wave and, as our physics teacher used to said, a square wave can be considered to be a sine wave with an infinity of harmonics that fill up the entire space under the wave graph, up until it’s square… :wink:

If it’s really annoying for you, try to insert an additional low pass filter on the inverter’s output, correctly tuned for 50Hz (or 60Hz, depending on your setting) and maximum current the inverter is capable of supplying, that will filter out the high frequency noise.

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3

Alex is correct, but he doesn’t need me to say that :slight_smile: I’m joining the conversation to simply add my two induction cooktops (hobs) in my RV are happy with the output of my 24/5000. No noise or weirdness. Maybe try using a different brand.

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4

Would you be able to list the ones you have that don’t make for a noisy inverter?

5

I also used at some point an induction cooktop, which didn’t made any strange sound.
But I have a Multi RS and the Multi RS is having that low pass LC filter by design, because of its high frequency hardware topology.

The Multiplus is not having an LC filter and the big chunky transformer inside is somehow taking its place. :slight_smile:
The transformer and that small inductor put in series with the transformer’s primary winding.
But that small inductor’s main purpose is another one, but nevertheless it helps, but not that much and therefore that noise shortcoming.

6

Some of my clients use induction hobs, but no one has ever complained.
If my memory serves me right, they have Siemens, AEG, Electrolux.

What kind of hob do you have, tell us?

UPD:
*Note: Only the power of their systems is 4-6 times more than the power of the hob.