Note: This is not a alternative to the wiseguy initial setup and test procedure for newly assembled Inverter boards.
When building the WG Inverter, or after any mods etc, once the controller board has passed it's pre-flight tests and the power board isolated supplies and wave forms have been checked, or after changing anything or making Inverter modifications:
My final pre-launch check is made with a small 1k resistor connected between a 14Vdc supply and power board B+ T1. Terminal T2 is common, The power supply supply current trip is set to 300ma and voltage set to 14Vdc.
With no power applied, the controller in Test mode, and a small value CAP board
fully discharged, the power board is connected to the toroid, a CRO or DSO is connected across the AC output of the toroid, any low cost small DSO will do.
The basic power board, isolated supplies and SPWM drive and FETS, along with any obvious Toroid faults/errors shorts and AC output filter and wiring errors can have a final check here.
With 14v applied to the controller, total current draw should be Less than 270mA for around 16vac P-P sine wave output, it depends on your turns ratio and toroid design voltage, do not place any load on the output.
NOTE: You will need to temporarily adjust the "Nano Menu" Item 2 "Capacitor Calibrate" voltage above Item 1 (Battery DC calibrate voltage), as the supply voltage to the FETS is via a 1K resistor, I normally enter 50V in Item 2 to stop the AC sine wave rising and falling, you do this with the test setup running.
The AC output will be rising and falling as PWM ramps up and down due to the small cap bank, which is unable hold the voltage constant as AC starts to generate, the voltage drops quickly across the FETS, the Nano detects this and ramps PWM down, rinse and repeat, this will not hurt anything. Once Item 2 is set high enough, the AC output will hold still.
There are no really high value caps or high DC voltages to destroy things, so if you missed something in the test setup, and you have set the power supply correctly, the maximum current should be limited to around 300mA, just a few watts, and whatever a very physically small sized cap can supply from 14V, which is also very little.
Do not go above 14V for this test.
NOTE: The test cap boards combined
total capacitance must be NO more than a
small size 1000uf 47v cap, small = less than 20mm high and 15mm across, this is important as these normally have a poor/high ESR.
If you made a mistake with FET mounting, or have any shorts or incorrect SPWM drive, the current will increase and voltage will drop and-or the AC output will fall way below 16vP-P.
Obviously you won't get this waveform and AC voltage if the SPWM drive connections are wrong, or there are shorts on the board, or there is a Toroid or wiring problem.
The AC output should look like the following, an AC output filter is not connected in this bench test setup, the DSO probe is connected across a 3uf to 4uf 400vac SPWM filter CAP which should be wired permanently across the secondary of the Toriod, the secondary being the AC output.
FYI Below: The Controller SPWM HI-LO output switching on J5, referenced to common (GND)A test plug with flying leads is simple to make to plug into J5, solder short leads to pins 1 to 4, these connect to the DSO probe/s, in my case the 4 channels of the DSO are connected to these pins.
Solder a short ground lead to Pin 8 of J5 for the DSO probe earth clips.
Finally a 1k resistor will need to be connected between pin 5 of J5 and the DC input if you are using my Code.
Pin 7 of J5 has +12v on it, it's not used here and should be cover with heat shrink tube.
Make sure all pins on the plug are covered with heat shrink, especially Pins 5, 6 and 7.
Obviously the Controller board is not connected to the Power board:
Controller board setup:
The LCD is connected.
DC input: 12V
Current limit: 100ma
When running:
Current draw: 82ma
Power: 986mW
EDITED: Added missing info.
Edited 2026-03-30 08:53 by KeepIS
