Big Coil (DRSSTC v2)

Big Coil has been an ongoing long term project, with a bit of recent research into the optimal ways to get phase lead compensated feedback working within a half cycle at the start of each pulse. It is trivial to get a phase leading signal a cycle or two from start, but it has proven relatively difficult to get it immediately.

The project has also gone through a number of gate drive revisions. I’m currently using optically signaled drivers on each brick with a 60hz iron isolation transformer powering the board. It pulls the gate +20V/-5V, capable of about 30nS switch time with minimal gate resistance, although I put an ohm or two in to help limit any ringing that could occur both on the gate, and more importantly voltage spikes that could form from emitter to collector.

Machining bus-plates

Bridge assembly

Resonant tank capacitor (CDE942 array)

Logic controller

Realtime tuning inductor with stepper motor

Primary current waveform with secondary in place at tuned resonance.