Patent ID: 8559152

Claim:
A system for protecting a power converter, the system comprising: a duty-cycle detection component configured to receive a modulation signal, determine a first duty cycle corresponding to a first period of the modulation signal, compare the first duty cycle with a threshold duty cycle, and generate a duty-cycle comparison signal; a threshold generator configured to receive the duty-cycle comparison signal and generate a threshold signal corresponding to a second period of the modulation signal, the second period being after the first period; a comparator component configured to receive the threshold signal and a first signal and to generate a first comparison signal, the first signal being associated with an input current for a power converter; and a pulse-width-modulation component configured to receive the first comparison signal and generate the modulation signal for adjusting the input current for the power converter based on at least information associated with the first comparison signal; wherein: the threshold signal is associated with a threshold magnitude corresponding to the second period of the modulation signal; if the first duty cycle is determined to be smaller than the threshold duty cycle, the threshold magnitude equals a first magnitude at the beginning of the second period and changes from the first magnitude to a second magnitude within the second period; and if the first duty cycle is determined to be larger than the threshold duty cycle, the threshold magnitude equals a third magnitude at the beginning of the second period, the third magnitude being larger than the first magnitude.