all home built solar system
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disco4now
Guru
Joined: 18/12/2014
Location: AustraliaPosts: 1094
Posted: 11:06pm 30 May 2021
poida said
picoverter BOM:
This will include both NTC thermistors, one attached
to the heat sink, one attached to the toroid,
and give over temp protection.
A DC-DC converter to give 15V.
I used this one from aliexpress
https://tinyurl.com/2uwe2bdf
and mount it vertically.
Whatever you choose needs to give 1Amp.
Arduino nano
IR2184 x2
LM358
LM7805
IC sockets for above 3 ICs and the nano
2 pin header 0.1" x6
1uf / 105 monolithic cap x6
0.1uf / 104 monolithic cap x6 (C22 is not needed)
10uf 25V electro x10
1uf 25V electro x2
4.7uf 25V electro x1
1N4007 diode x7
1N5231 5.1V zener x1
BAT46 diode x1
FR107 fast diode x2
LED x1
Resistors:
15K x3
4K7 x2
10K x3
100R x3
6K8 x1
1K x3
51K x1
10K NTC thermistor x2
9V AC small power transformer, taken from a wall wart,
for AC voltage feedback.
The 9V transformer is appropriate with a 1K for R2
The two fans:
MOSFET, logic level gate voltage, IRFZ44 or similar x2
2 pin header 0.1" x2
15K resistor x2
12V fans from the stack of junk, 0.4 Amp max
if using the LCD function:
3 pin header 0.1"
Build notes:
15V supply is used for the gate drive output.
The picoverter can drive both totem-pole type power boards
as well as Madness's 4kW direct drive power board.
Best results (i.e. a bullet proof inverter) are
with totem-pole gate drive type power boards.
R4 and R9 not important, use something >10K
IC orientation is to be carefully observed. I have inverted U1
compared with U2. Get it wrong and will cost you $6 for a new IR2184
Prior to connecting the picoverter to the power board,
move the trimpot all the way so that the wiper is
now zero Ohms with the cathode of D7 and the lower pin of R5.
This is the node where D7 and R11 are joined.
maybe use a trimpot with the vertical screw, I used what I had
in the box of spares.
In doing this, the AC voltage feedback will be at the maximum
and so the inverter will produce the smallest output voltage it can.
This is a safe way to start up the inverter when we have no idea
where to put the trimpot.
Later on, you can set the AC output voltage as required.
(should you not set the trimpot as above, there is a
high likelihood that the inverter will run to voltages
way over 240V, something like 280V, and draw a lot of current
due to the now well saturated toroid transformer. not good)
Edit the picoverter firmware to suit your needs.
Unedited code will work fine.
load the nano with the picoverter firmware.
The battery voltage sense resistor divider will be not
quite right and need calibration. The calibration value is
in the firmware and you change it thus:
load the special DC voltage calibration firmware into the nano.
Connect the picoverter, with this firmware loaded, to the power board.
connect to the serial monitor from the Arduino program.
It will print the measured DC voltage and the calibration value.
It will probably be a bit wrong.
At the top of the console, type the correct voltage.
It will then make a new calibration value and print
the voltage and the new cal value.
Eventually you will get it close enough. Note this calibration value.
Edit the picoverter firmware and replace the old DC cal. value with
this new one,
then load the firmware into the nano.
Now we are good to go with using the inverter.
We have set Vfb to a safe position and have correct DC voltage measurements.
bv cal firmware:
do not forget to set the serial monitor to 9600 baud
see below of post..
latest picoverter firmware, with smoother battery voltage display
pico_2_heavy_filter_bv.ino.zip
Current schematic, pcb pdf and gerber:
picoverter 30-5-2021.zip
bv cal firmware:
pico_bv_cal.ino.zip
1oz copper is fine for the picoverter board.
2oz is best for the power board.
copied from the
150V 45A MPPT - roll your own
thread
