Current feedback solid state tesla coil


This SSTC is much more like most SSTCs than my DRSSTC :-P It operates much like Steve Ward's miniSSTC, but the electronics is somewhat different. The secondary current is fed through a current transformer and the output is rectified and provides the signal and power for the gate drive circuitry.


Initial power is supplied by leaking a few milliamps through resistors from the + rail to the + rail on the highside MOSFET gate drive power supply. The lower rail for the high side gate driver leaks some current to the + rail for the low side MOSFET gate drive power supply. The oscillation is started by the flip of a switch. This switch shorts pin 2 and 6 of the 555 to the 15v rail. When the switch is opened, the 555 is allowed to oscillate. The output (pin 3) of the 555 goes directly to the enable pin of the low side gate driver. The input is held low (10k resistor), and it is an inverting chip, so when the enable goes high, the output goes high. This turns on the bottom MOSFET, and starts oscillation.


Since the current transformer is isolated, a gate drive transformer isn't needed. The signal from the transformer is fed through an RCD network dealy to give dead time, if needed. This goes directly to the input of the gate drive chips.


This project is awaiting PCB etching. My previous attempt failed due to shoot through. I tried to use 2 non inverting chips, but with imperfect signals, there was overlap in the drive signals. Using an inverting chip should fix this.


I will hopefully get around to making a schematic soon.