Helo dier community! I got a 400 Hz broken Power Inverter and reverse-engineered the circuit just for the simplicity of repairing it. Then I got deeper in and started to understand the engineering principle of the circuit. But I em stuck on this Op-Amp integrator build in and his role in this circuit. It would be nice if you could help me to understand his role. If you need some Voltage references I can provide it. The circuit is a simulation in Multisim and fully running.
- the integrator output on p10 ought to be near 0V if the NPN PNP gains are matched with transients expected on start/stop of loads in order to balance the primary coil from saturation. it does this by balancing the input voltage drop to the transformer input R+impedance. A saturated core presents a very low impedance. This occurs on startup often.
Record all the DC voltages and compare with simulation and paste results on schematic if you cannot debug.
The integrator ensures minimal DC current through the output transformer T1. The Vos of the OP-07 is maximum 150uV so the DC current will be less than 150uV/0.01 ohms or 15mA.
The output amplifier is DC-coupled so this is necessary to keep the transformer from saturating.