I bought a solar controller for my 192V solar system that did not work as advertised (instead of MPPT, works with ON-OFF cycles - Chinese ripoff - but that is offtopic).I want to redesign the control and power stage to make it a real PWM controller. I came up with the following schematic:
The PV array has a maximum voltage of 340V and maximum point at 270V. The actual controller connects the PV directly to the battery until the voltage reaches 232V. Then it cuts the connection until the voltage drops to 216V when it connects the PV back. Cycle repeats. That is not fully charging the battery. By using a variable duty cycle (generated with an Arduino), I want to reproduce the 3 stage battery charging method.
Now be gentle with me, this is my first project and all the help is apreciated. Let's jump over the "WARNING: High Voltage message". Is taken into account :)
The snubber from the IGBT is made after the ones my controller has. The only difference is the controller has no gate resistors/diodes, no resistors between gate and source and has a big 1uF/450V capacitor between the PV+ and B+.
Regarding IR2110, I know using it as High Side driver requires a bootstrap circuit. Since in the first stage, the IGBTs will be continuously closed (100% Duty Cycle), I want to use an isolated dual power supply (B1 - powered from the 192V battery) to power the Arduino (5V) and IR2110 (5V/12V).
The frequency I tested the circuit with is around 100Khz. It works good until I apply a big load (I applied 24V on the PV side and 2 halogen car light bulbs in series on the output, with a variable duty so the output is around 13V), moment when, randomly, the Arduino controller either resets or locks. I am stumped ! I have no idea why this happens. If the load is smaller (like trying to charge a 12V battery), the circuit works without any issues.
Seems the resets/locks of the uC happened because of high ground bounce. I was getting between PV- and B- a potential of over 1000V (going over the scale on my digital voltmeter). I added C2 and things calmed down.
I have a strange reading on my oscilloscope, between point A and B, that I have no idea what it means. Is this reading OK ? Happens when Duty Cycle is under 20-30%. Frequency 100Khz.
Thank you !