Cooking food with fire is arguably the technology that propelled humans to become the dominant species on Earth. It’s pretty straightforward to achieve, just requiring a fuel source, a supply of oxygen from the air, and a way to initiate the reaction; then it self-sustains. You wouldn’t think there’s much to improve, but what about cooking with plasma? [Jay] from the plasma channel is no stranger here, and he thinks that there may be something in this idea, certainly enough to actually build something.
Now, let’s be straight with you, this isn’t a new concept, and you can buy a plasma-based cooking appliance right now. But they are all AC-powered devices. What if you want to go camping? [Jay] attempts (and succeeds) in building a portable, rechargeable 600W plasma cooking device that can actually cook food, but it was not all plain sailing.
The existing off-the-shelf ZVS driver modules available were a bit weak and unreliable, and the required flyback coils were hard to find with the right specs, so he needed to get down to work building custom parts. First off, the coils. Custom formers were resin-printed and machine-wound with 4000 turns of fine wire, and then resin-sealed into the former. [Jay] takes care to explain that it is crucial to get all the air out of the windings, or else local flashover breakdown will occur and wreck the coil in a short time. We reckon the resulting coils look amazing in their own right!
We do love a nicely wound coil. Oooh!
Next, the ZVS drivers on hand had low-quality capacitors (well, not enough capacitance anyway) and cheap driver transistors, so both were upgraded. The initial plan was to have four driver/coil pairs, each driving a single pair of electrodes, with a common ground ring connecting them all. It turns out this was a terrible idea: the drivers were not synchronised, so they were pulling on each other, causing catastrophic damage to the PCBs in a very short time. The solution was more complicated wiring, to give each coil secondary output a dedicated electrode pair, so there was no direct electrical connection between neighbouring coils and no coupling between them. A clever electrode arrangement meant that a pan would sit on top of a ring of electrodes, causing plasma discharges to jump directly to the pan, thereby concentrating localised heating there. We were wondering how this new direct connection (the pan is now a common connection!) didn’t also cause backfeeding and kill the ZVS drivers again, but it didn’t seem to happen.
Bang, smell, oops. The copper is supposed to be stuck to the PCB.
Anyway, [Jay] demonstrates what is possibly the world’s first rechargeable, portable plasma cooker capable of making breakfast. Which we think is very important in its own right, however, we would like a plasma-based solution to making toast next, perhaps a plasma knife that cooks the bread as you slice it?
If this plasma cooking lark rings a bell, yes, we did touch upon this way back in 2017. And whilst not strictly plasma cooking, you can make an amazing microwave plasma in this ridiculously upgraded appliance. Definitely do not try that one at home.
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