Patent ID: 8335095

Claim:
A one cycle control method for power factor correction based on a boost circuit and a main control chip of system, the boost circuit comprising an AC input, a rectifying circuit, an inductor, fast recovery diodes, a capacitor, a DC output, an inductive current sampling circuit, an output voltage sampling circuit, a switch transistor and a driving circuit of the switch transistor; the control method comprises the steps of: (1) Determining whether soft-start ends or not; if the soft-start ends, processing step (2) directly, if not, increasing reference value U ref of output voltage and then processing step (2); (2) Reading sampling output voltage U o and sampling inductive current i g according to A/D sampling triggering instant; (3) Calculating as follows duty ratio of PWM signal for driving the switch transistor: Calculating u 1 and u 2 according to Equation of { u 1 ⁡ ( t ) = i g ⁡ ( nT ) ⁢ R s u m ⁡ ( nT ) u 2 ⁡ ( t ) = 1 T ⁢ ∫ 0 t ⁢ 1 ⁢ ⁢ ⅆ τ ⁢ ⁢ 0 ≤ t ≤ T ⁢ ⁢ 0 ≤ τ ≤ t in which R s is an equivalent current detection resistance, u m is an output of a PI regulator by regulating difference between the reference value U ref of the output voltage and the sampling output voltage U o ; obtaining the duty ratio of PWM signal ; (4) Outputting PWM signal; (5) Calculating the next A/D sampling triggering instant according to the duty ratio of PWM signal; (6) Returning to step (2).