Systems and methods for constant current control with primary-side sensing and regulation in various operation modes

摘要

System and method for regulating a power converter. The system includes a first signal processing component configured to receive at least a sensed signal and generate a first signal. The sensed signal is associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter. Additionally, the system includes a second signal processing component configured to generate a second signal, an integrator component configured to receive the first signal and the second signal and generate a third signal, and a comparator configured to process information associated with the third signal and the sensed signal and generate a comparison signal based on at least information associated with the third signal and the sensed signal.

主权项

1. A system for regulating a power converter, the system comprising:
a first sampling-and-holding and voltage-to-current-conversion component configured to receive at least a sensed signal and generate a first current signal, the sensed signal being associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter; a second sampling-and-holding and voltage-to-current-conversion component configured to receive at least the sensed signal and generate a second current signal; a current-signal generator configured to generate a third current signal; a capacitor coupled to the current-signal generator and coupled, through a switch, to the first sampling-and-holding and voltage-to-current-conversion component and the second sampling-and-holding and voltage-to-current-conversion component, the capacitor being configured to generate a voltage signal; a comparator configured to process information associated with the voltage signal and the sensed signal and generate a comparison signal based on at least information associated with the voltage signal and the sensed signal; a modulation-signal generator configured to receive at least the comparison signal and generate a modulation signal; and a gate driver configured to receive the modulation signal and output a drive signal to a switch, the switch being configured to affect the primary current flowing through the primary winding; wherein:
the drive signal is associated with at least one or more switching periods, each switching period of the one or more switching periods including at least an on-time period for the switch and a demagnetization period for a demagnetization process;the first current signal represents the primary current at the beginning of the on-time period; andthe second current signal represents the primary current at the end of the on-time period; wherein for each switching period of the one or more switching periods,
the first current signal and the second current signal discharge or charge the capacitor during only the demagnetization period;the third current signal charges or discharges the capacitor during the switching period; andthe switching period multiplied by the third current signal is equal to the demagnetization period multiplied by a sum of the first current signal and the second current signal in magnitude.