Control circuit with high power factor and AC/DC converter

A high power factor control circuit used in an AC/DC converter, the AC/DC converter comprising a rectifier, a converter coupled to the rectifier and a load driven by the converter, the rectifier configured to receive AC power and to rectify the AC power into a DC current, the converter configured to convert the DC current to drive power as desired by the load and to provide the drive power to the load, wherein the converter comprises an inductive element and a switching element coupled to the inductive element, the switching element configured to regulate a current flowing through the load, wherein the current flowing have ripples relative with the AC power, the high power factor control circuit comprising:

• a peak limiting signal generator configured to receive a reference signal and a sample signal, the sample signal indicating the current flowing through the load, and to output at least one peak limiting signal indicating a peak current according to the reference signal and the sample signal;
• a switching element control module coupled to the switching element, the switching element control module configured to control the switching element on and off, wherein the switching element control module controls the state of switching element according to the peak limiting signal and a sensed signal indicating a current flowing through the inductive element so that, within at least half a line-frequency period, a value of the ripples in the current flowing through the load is not greater than a limit value;
• and
• a feedback unit, wherein the feedback unit comprises a sample circuit coupled to the switching element, the sample circuit configured to sample the current though the load and to output the sample signal.