I've got a small update. I finally finished the MOSFET driver boards and assembled the other discrete parts of the system. I just need to connect them together.   I assembled a 27.3nF capacitor from 4x 2000V 6.8pF silver mica Soviet capacitors.   I formed a low inductance, low resistance coil from 10mm copper pipe. This was my first copper pipe coil and I did it by filling it with salt and taping up the ends, before rolling it around a cardboard tube former. It turned out pretty well, although there is one small kink, but it shouldn't affect performance. The inductance is 140nH, but you can adjust it by moving the output connection point. I'm aiming for ~0.93nH, because when combined with a 27.3nF capacitor that gives a 1MHz resonant frequency which is the frequency that I'm aiming to run the system at.  I assembled the brain of the device using a Teensy 4.1 running Arduino.  I spent the best part of 2 days hacking together the PWM code using hardware PWM timers. There are a bunch of limitations around these timers that weren't super obvious initially. There are limitations to the pins used (some use the SD card pins, so aren't easily accessible), frequencies can't be different across sub-modules, different modules can't be easily synchronized etc. In the end I've nearly got there. I have 3 distinct PWM outputs operating at different frequencies and duty cycles. The first two are synchronized and have a 50ns dead time period between PWM1 fall & PWM2 rise and PWM2 fall & PWM1 rise to prevent both being turned on at the same time. They operate at 1MHz. The third one is the output stage and that runs at 50Hz.
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Author
Topic: William ENKI (Read 9069 times)
