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Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
If you're considering a buck-converter, notice that the 'input' to a zvs is the dc-link inductor - which may also be the buck-converter output inductor, if configured for current feedback not voltage feedback. The switching frequency of the buck-converter should of course be much higher than the zvs switching frequency - preferably a fixed multiple.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
The sg3525 has a maximum frequency of 500khz, but I still have no clue ho to use the chip. I know ho to adjust the pwm, but not a clue how to supply it with output voltage feedback.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Alight, I've decided to use the arduino for the buck converter. This will allow me to use an LCD and stuff.
The arduino's PWM is only about 970Hz by default, but I figured out that I could change the timer's prescaler to speed that up. Putting "TCCR0B = 0x01;" in the setup loop gives me a 62.5kHz PWM on pin 5. Although that's a little low I can still use it for a buck converter. Just need a good smoothing cap.
Using an analog input and a voltage divider I can easily make a regulated SMPS with digital control. I'd like to see an SG3525 do that.
Edit: Damn, this also messes with the delay function. 1000ms becomes 16ms. hmm...
Edit: Ok, changing TCCR1B gives me 31.37khz on pins 9 & 10. It doesn't affect delay(). Oh well, bigger smoothing cap I suppose.
I also decided to run the AC FBT @ 75khz. Don't know what cap value to use on the zvs for that, but that's what an oscilloscope is for I suppose.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
Hello Radhoo,
I like your HV power supply. I'm working on something similar.
I would like the flexibility to configure it either for -50 kv, +50 kv or +/- 25 kv, with respect to ground. Can you do that with your power supply?
radhoo wrote ...
I built a variable 50KV supply (can be extended): - one LM317 + high power transistors to adjust the low voltage 0..30V (schematics here: - a ZVS driver and a flyback chosen that the discharge starts at minimum 1 cm (some of my flybacks are giving very low voltages only, you should start with at least 10kv) . Funny this was a low power flyback. - the multiplier, to reduce the ripple effect I've split it in two parts, a negative multiplier and a positive multiplier.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Think this will work (did I do the error compensation correctly)? It uses 2 sg3525s, one for the regulator and one to drive the FBT. The second one could possibly be used to regulate the HV out via some big resistors.
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
I don't see a compensation network for the synchronous buck converter. It's not really my field of expertise, but I found an example of a compensation network for a synchronous buck converter in this application note. It might give you some ideas.
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Designing a variable HT PSU
