More progress on the high-voltage impulse generator....

More progress on the high-voltage impulse generator. The huge capacitors, resistors and inductors for pulse shaping are now installed for testing. They mostly work. But this test uncovered a serious problem - each time the circuit fires, I can hear an arcing noise, the oscilloscope also shows a weird glitch, likely caused by arcing. The generator is supposed to destroy the device-under-test, not itself! Now my suspect is the isolated DC-DC module. Just ordered a better one for another try... #electronics

Photo of the same circuit board, now with huge capacitors, inductors, resistors, and huge banana socket connector installed.

Like 8 Nov 2022 at 12:46 | Open on mk.absturztau.be

2 comments

niconiconi replied to niconiconi

Problem solved. The "arcing" sound during the impulse current discharge is NOT a fault. It's actually a common phenomenon in all high-current pulse circuits. The "snap" noise was caused by sudden physical deformations of the circuit board itself, due to Lorentz force from the intense current. #electronics

14 Nov 2022 at 21:16 | Open on mk.absturztau.be

niconiconi replied to niconiconi

Success! My first circuit board prototype of the IEC 61000-4-5 Combination Wave Generator (aka Lightning Surge Generator, aka Impulse Generator) is working after a month of development. This PCB has greatly improved safety and usability compared to the original perfboard. #electronics

Surge waveforms are compliant to IEC 61000-4-5's 1.2/50 μs & 8/20 μs requirements.
⚡ Open-Circuit Voltage:
- 1.02 kV, Front time: 1.33 μs, Duration: 53.60 μs
⚡ Short-Circuit Current:
- 484 A, Front time: 7.53 μs, Duration: 21.51 μs

Photo of the PCB prototype.

On the left there's a 120x160 LCD screen, four pushbuttons. USB power connector, a debug header, a microcontroller.

At the middle there's an isolation barrier, separating the low-voltage side and high-voltage side by a few centimeters for reinforced isolation. An isolated optocoupler and a isolation transformer are used for signal and power transmissions.

On the right there are various subcircuits. Most visible ones are a thyristor, massive capacitors, resistors, two toroidal inductors, and two large banana connector / binding post. Other supporting components includes a microcontroller, a flyback high-voltage power supply, a normally-on high-voltage SiC FET transistor for safety discharge, a floating high-side gate driver, among other things.

Oscilloscope screenshot of the output voltage and current waveform, showing the device is in conformance to the IEC 61000-4-5 requirements.

Comparison of the old and crude hand-built perfboard prototype and the new fancy PCB prototype.

14 Nov 2022 at 21:39 | Open on mk.absturztau.be