3-5kW ZVS Induction Heater?

[Jadeit]

What do you think of these Chinese toys?

3000W 55A ZVS or 5000W ZVS or 3000W ZVS kit​

A
At first glance, it is an ever-repeating design that can generate frequencies above 60kHz in one channel at approx. 48V approx. 2500W.

What is my point?
Yes, it is related to my question about the PID and the furnace.
The heated form from the furnace enters the vacuum chamber, where the molten metal must be poured into it.
Induction heating is probably the only way to realize vacuum melting. I would probably get cooling water and a sufficiently strong HF wire into the vacuum chamber, the others can remain outside.
On the other hand, we know the Chinese, they are incredible magicians with numbers

 

[Jadeit]

5000W/5KW ZVS Induction Heater ​

something tells me that it will be 3 or 6 in parallel

 

[asrock70]

A beautiful example of the Chinese ability to extract the maximum from the minimum.
Without thinking about it, I was struck by the possibility of parallel ordering.
I would expect the necessity of some given ratio between the inductance of the heating coil and the parallel capacitor bank.
I see, the Chinese use capacitors 0.33uF MKPH HF 1200V
IRFP250 RDSOn 85mOhm maybe a better transistor could be found.
In any case, an interesting solution