Systems and methods for dynamic threshold adjustment with primary-side sensing and regulation for flyback power converters

摘要

System and method for adjusting a threshold of a power conversion system. The system includes a threshold generator configured to receive a first signal and generate a threshold signal based on at least information associated with the first signal, a comparator configured to receive the threshold signal and a second signal and generate a comparison signal, and a gate driver configured to generate a drive signal based on at least information associated with the comparison signal. The gate driver is coupled to at least a switch configured to receive the drive signal and affect a current flowing through a primary winding coupled to a secondary winding. If the second signal is larger than the threshold signal in magnitude, the drive signal causes the switch to open. The drive signal is associated with a switching frequency.

主权项

1. A system for adjusting a threshold of a power converter, the system comprising:
a threshold generator configured to receive a first signal modulated at a switching frequency, process information associated with the first signal, detect a magnitude of the switching frequency of the first signal, and generate a threshold signal based on at least information associated with the detected magnitude of the switching frequency of the first signal; a comparator configured to receive the threshold signal and a second signal and generate a comparison signal; and a gate driver configured to output a drive signal to a switch based on at least information associated with the comparison signal in order to affect a current flowing through a primary winding coupled to a secondary winding; wherein, if the second signal is larger than the threshold signal in magnitude, the drive signal causes the switch to open; wherein:
the drive signal is associated with the switching frequency;the second signal increases with the increasing current in magnitude and decreases with the decreasing current in magnitude; andthe threshold signal increases in response to the increasing switching frequency in magnitude and decreases in response to the decreasing switching frequency in magnitude.