Senior Member
Joined: 10/02/2015
Location: United KingdomPosts: 199
| Posted: 06:58pm 27 Jul 2023 |
Ok, I've finally started looking at inductors: I've reprogrammed the nano with the 24x2 lcd to do pwm. It works from about 6uS up to 1023uS and runs at about 100Hz to allow the inductor current to fall.
Using an 06CN10L (60v 100A to220) mosfet along with one of the 200v schottkys that will be going into the MPPT unit.
Testing the inductor setup with a little torroidal inductor
Tried my big ferrite that i wound a while ago with 11 turns of 25mm2 . I originally made this with an inverter build in mind, but that was before i learned that it would saturate at too low a current to be useful.
Depending on wether i have 0.5mm or 1mm of cardboard in the gap it's either 55uH and 30A saturation or 42uH and 50A from memory (didn't write it down), but 25mm2 is overkill so I thought if i can get more turns of something smaller in there, and a bigger gap it might work for the MPPT.
I want to run 4 panels in series, vmmp 130v, into a 24v battery. Using this online calculator:
http://schmidt-walter-schaltnetzteile.de/smps_e/abw_smps_e.html
i reckon i need 100uH and that would give me a ripple of 10A at 20kHz.
So, with 24turns of test wire i get these results:
1.5mm gap (three card layers)
Thats about 30A, and i calculate 145uH (scope reading 'current' using 0.1ohm shunt resistor; 30.5v supply).
2mm gap, 4 cards
35A, 121uH
2.5mm gap, 5 cards
40A, 106uH
Saturation peak
Turned back to below saturation
5 cards in the gap
Edited 2023-07-28 05:03 by mab1