Could this have been a Westinghouse invention?
Having lived in Pittsburgh we always heard about something from them. Electrolux/Frigidaire appliances today are based on Westinghouse appliances in the past (I think).
About 50 years ago I remember I was young and saw a news report on KDKA TV (because it was a Westinghouse Broadcasting station) about a new cooktop that used magnetic energy. It was white, like a Corning cooktop, and had "sliders" along the sides that adjusted the heat. The sliders were on the cooktop but not attached to it, you could lift them off.
I never saw one of those IRL or in a store so maybe it was experimental? If it was on the market it had to be expensive at the time and people were not into Viking, Wolf, or the expensive appliances then.
This was just before WH sold off appliances so maybe this technology ended up with Electrolux which is why Frigidaire now has it more than the others.