It can be just that simply your stainless steel cookware simply is not magnetic as opposed to having aluminium bottom, as about half of all stainless steel alloys are in fact not magnetic.
On the other hand it infuriates me that the cookware has to be magnetic in the first place. It should suffice that the cookware is conductive. I suspect that the only reason why it has to be magnetic is that the stove uses the magnetic properties to detect that there is some cookware. (In fact in industrial practice induction heating is mostly used to heat non-magnetic and often even “questionably conductive” materials)
Magnets stick to the top of the pan but not the bottom, i've checked. There's a dividing line across the middle of the pan separating the bottom from the top. From what i've read, they'll make the bottom of some steel pans aluminum because it'll help the pan heat up quicker than steel alone.
>I suspect that the only reason why it has to be magnetic is that the stove uses the magnetic properties to detect that there is some cookware.
I could see this. My main experience with an induction burner is with a single burner hot plate, but it seems to be pretty heavily safety oriented. It defaults to a timed mode when you turn it on unless you select otherwise, you can't leave it on high heat for longer than a certain time or it'll shut off automatically regardless of the setting, and it shuts off after about 30 seconds when you take the pan off or when you put non-magnetic cookware on. For something that produces no heat itself and seems to lack many of the fire hazards of normal burners it sure seems designed to ensure you're going to burn your house down.
The reason why you cannot keep induction stove indefinitely on the highest power setting usually is that the cooling solution of internal electronics is not designed to reliably dissipate the maximum power loss continuously (it is similar idea as turboboost of current intel CPUs, some stove vendors even market it as turbosomething(TM)). As for maximum power most european (ie. 230V) induction stoves are designed to be powered from two distinct AC phases and the electronics can distinguish between two distinct phases and both power inputs shorted together and limit maximum total power accordingly.
Induction stoves mostly run at 30kHz or so; at such a low frequency, your skin depth for non-ferrous metals is measured in centimeters to decimeters. Industrial induction heating sometimes benefits from such a deep skin depth, depending on the application, but it's a drag when you're cooking. Industrial induction heating that wants a thinner skin depth on non-ferrous metals uses higher frequencies, sometimes up to the MHz.
Induction heating does not heat up questionably conductive materials, unless you mean graphite.
On the other hand it infuriates me that the cookware has to be magnetic in the first place. It should suffice that the cookware is conductive. I suspect that the only reason why it has to be magnetic is that the stove uses the magnetic properties to detect that there is some cookware. (In fact in industrial practice induction heating is mostly used to heat non-magnetic and often even “questionably conductive” materials)