Hey, I've tried to build an Induction-heating-circuit, but it doesnt draw any current from my adjustable Transformer, no matter which voltage i give it. I planned to run it from mains-voltage(230V-50Hz). The Inductance of my Work-coil is around 100µH, the Work-Cap is around 330nF which gives me a resonant frequency of 28500hz. I adjusted my Driver-IC to output me this, and it works great. But my adjustable Transformer just shows me 0A current. I am sure that this measurement is right, because the IGBTs also dont get hot. Please help me!
I think you dont need L1 and L2...only the work coil and the resonant tank cap in series or parallel. You have a series oscillatinc circuit.
the gate resistors are a bit too high...acc. to the datasheet, they use a 10 Ohm Gate resistor for the given switching times. I also suggest to use a gate driver with more power, 160 mA is too less. You want to switch the IGBT´s fast which results in less switching losses for IGBT´s. For my induction heater, i use a STM32 for controlling and a MCP14E10 for gate driving with a GDT. The MCP14E10 can deliver up to 3 A.
Joel wrote: > But my adjustable Transformer just shows me 0A current. With what load? Where should the energy go to?
The energy will wasted in the LC circuit with no load (iron, etc.) in the coil.
at idle (no load in the coil) and control with resonant frequency, a series resonant circuit pulls the most power, where a parallel resonant circuit will pull at least power at resonant frequency.