The publish clarifies an easy arrangement which may be installed with all SG 3525/3524 inverter circuits for utilizing automatic PWM output voltage restrictions by the IC.
The section that's circled is a simple bridge rectifier with a potential divider level by using a 100k pot. It rectifies and directs a sample comments voltage from the inverter mains output to pin1 of the IC which detects this advice and consequently manages the PWM of the IC and manages it in order that the output from the inverter certainly not crosses a established limit as set by the 100k preset.
pin1 is the sensing input of the IC which reacts and produces the PWMs narrower the moment the fed voltage from the 100k pot crosses a specific certain limit.
Pin1 of IC SG3525/3524 actually forms one of the pinouts of the internal error amplifier opamp. The word error amplifier itself implies that the opamp is allocated to identify and examine a comments sample voltage (error signal) from the inverter output and correct the output PWM width suitably. This voltage is imagined as regards to the other pin of the IC (pin16) that could be internally fitted at a reference voltage of 5.1V.
Just in case an emerging response is determined, the potential at pin1 of the IC which happens to be the sensing input of the error amplifier relatively goes higher than the other complementing pin16 of the opamp developing a high at the output of the internal error opamp.
This high is employed internally to improve or slim down the PWM frequency which inturn provokes the mosfets to carry out with relatively lower current, as a result rectifying the output voltage of the inverter immediately with reference to the feedback signal.
Parts list for the above presented SG 3525 inverter circuit with auto PWM voltage control feature.