Current sharing method and apparatus for alternately controlling parallel connected boost PFC circuits

A control circuit for alternately controlling parallel-connected first and second boost circuits of a dual boost PFC circuit to achieve a current-sharing of said first and said second boost circuits, comprising:

• a first control circuit having a first current control loop for employing an output voltage of said PFC circuit, a feed-forward voltage, and an input reference voltage to generate a current reference, and sending said current reference to an input terminal of said first current control loop to generate a first PWM signal to drive said first boost circuit accordingly;
• a second control circuit having a second current control loop for receiving said current reference through an input terminal of said second current control loop to generate a second PWM signal to drive said second boost circuit accordingly;
• and
• a synchronous pulse signal generator for providing sychronously alternating signals, a first and a second saw-tooth wave signals, to said first and said second control circuits to produce a phase-shift having a certain degree value;
• wherein said first and said second current control loops are alternately controlled with said phase-shift of said certain degree value for obtaining an alternate double frequency so as to accomplish said current-sharing of said first and said second boost circuits, and said synchronous pulse signal generator employs two oscillating voltage signals with an equal frequency and two digital pulse signals having said phase-shift of said certain degree value added and synchronized to said two oscillating voltage signals, respectively, to generate said first and said second saw-tooth wave signals having said phase-shift of said certain degree value for use as period signals of said first and said second control circuits, respectively.