Power factor correction circuit and driving method thereof
View Patent ↗A power factor correction circuit corrects a filter current flowing through a filter capacitor asymmetrically based on a peak of an input voltage by controlling a switching operation of a power switch, thereby correcting distortion of an input current.
1. A power factor correction circuit comprising:
a filter capacitor; and
a primary side winding connected to the filter capacitor;
a power switch connected to the primary side winding to convert an input voltage into a secondary side output;
an adjustment signal generator to generate an adjustment signal based on an input detection voltage corresponding to a full-wave waveform of an input voltage to the power factor correction circuit, wherein the adjustment signal is asymmetric with respect to a peak of the full-wave waveform of the input voltage; and
a duty generator to control a switching operation of the power switch to correct a filter current flowing through the filter capacitor utilizing the adjustment signal,
wherein the adjustment signal generator comprises:
a reference signal generator to generate an adjustment reference signal synchronized with the input voltage; and
a multiplier to generate the adjustment signal by multiplying an input peak voltage corresponding to the peak of the full-wave waveform of the input voltage by the adjustment reference signal,
wherein the adjustment reference signal has a waveform for correcting distortion of an input current by the filter current.
2. The power factor correction circuit according to claim 1 , wherein the duty generator is to generate an error voltage by correcting a difference between a voltage corresponding to an output voltage and a predetermined reference voltage, and generate a feedback signal by adding the adjustment signal to the error voltage.
3. The power factor correction circuit according to claim 2 , wherein the duty generator is to generate a sawtooth wave signal increasing with a predetermined slope in synchronization with a switching cycle of the power switch and turn off the power switch at a time point in which the sawtooth wave signal reaches the feedback signal.
4. The power factor correction circuit according to claim 1 , wherein the duty generator is synchronized with a switching cycle of the power switch and is to generate a sawtooth wave signal increasing with the controlled slope by controlling variation in slope in a direction reverse to a variation direction of the adjustment signal.
5. The power factor correction circuit according to claim 1 , wherein the duty generator is synchronized with the switching cycle of the power switch and is to generate a sawtooth wave signal increasing with a controlled beginning level by controlling variation in the beginning level in a direction reverse to a variation direction of the adjustment signal.
6. The power factor correction circuit according to claim 1 , wherein the duty generator is to determine a compensation period based on the adjustment signal and control an on-period of the power switch corresponding to the compensation period.
7. The power factor correction circuit according to claim 6 , wherein the duty generator is to calculate the compensation period by dividing a value, obtained by multiplying the adjustment signal by the switching cycle of the power switch, by a value obtained by multiplying the input voltage by the on-period of the power switch.
8. The power factor correction circuit according to claim 7 , wherein the duty generator is to generate a compensation control output by delaying a control output, based on a result of comparison between the feedback signal corresponding to the output voltage and a sawtooth wave signal, by a period corresponding to the sum of at least one switching cycle and the compensation period.
9. The power factor correction circuit according to claim 1 , wherein the duty generator is to generate the feedback signal by controlling a reference voltage according to the adjustment signal and control a switching operation of the power switch based on a result of comparison between a sensing voltage corresponding to a current flowing through the power switch and the feedback signal.
10. The power factor correction circuit according to claim 1 , wherein the duty generator is to generate a compensation sensing voltage by controlling variation in slope of a sensing voltage in a direction reverse to a variation direction of the adjustment signal, and control a switching operation of the power switch based on a result of comparison between the compensation sensing voltage and a reference voltage,
wherein the sensing voltage is a voltage corresponding to a current flowing through the power switch.
11. The power factor correction circuit according to claim 1 , wherein the duty generator is to generate a compensation sensing voltage by controlling variation in a beginning level of the sensing voltage in a direction reverse to a variation direction of the adjustment signal, and control a switching operation of the power switch based on a result of comparison between the compensation sensing voltage and a reference voltage,
wherein the sensing voltage is a voltage corresponding to a current flowing through the power switch.
12. The power factor correction circuit according to claim 1 , wherein the duty generator is to generate a feedback signal based on a result of multiplication of the sum of a reference voltage and the adjustment signal by the switching cycle of the power switch, generate a sensing voltage based on the total amount of a switch current for one switching cycle of the power switch, and turn off the power switch based on a result of comparison between the sensing voltage and the feedback signal.
13. A power factor correction circuit comprising:
a filter capacitor;
an adjustment signal generator to generate an adjustment signal based on an input detection voltage corresponding to a full-wave waveform of an input voltage to the power factor correction circuit, wherein the adjustment signal is asymmetric with respect to a peak of the full-wave waveform of the input voltage; and
a power supply comprising a power switch electrically connected to the filter capacitor and converting an input voltage into output power using the power switch,
wherein the power factor correction circuit is to control a switching operation of the power switch to correct a filter current flowing through the filter capacitor utilizing the adjustment signal,
wherein the adjustment signal generator comprises:
a reference signal generator to generate an adjustment reference signal synchronized with the input voltage; and
a multiplier to generate the adjustment signal by multiplying an input peak voltage corresponding to the peak of the full-wave waveform of the input voltage by the adjustment reference signal,
wherein the adjustment reference signal has a waveform for correcting distortion of an input current by the filter current.
14. The power factor correction circuit according to claim 13 , further comprising
a duty generator to generate an error voltage by correcting a difference between a voltage corresponding to an output voltage and a predetermined reference voltage, and generate a feedback signal by adding the adjustment signal to the error voltage.
15. A method for driving a power factor correction circuit comprising a power supply electrically connected to a filter capacitor, the method comprising:
generating an adjustment signal based on an input detection voltage corresponding to a full-wave waveform of an input voltage of the power supply, wherein the adjustment signal is asymmetric with respect to a peak of the full-wave waveform of the input voltage; and
correcting a filter current flowing through the filter capacitor by controlling a switching operation of a power switch of the power supply utilizing the adjustment signal,
wherein generating the adjustment signal comprises: generating an adjustment reference signal synchronized with the input voltage, and multiplying an input peak voltage corresponding to the peak of the full-wave waveform of the input voltage by the adjustment reference signal to generate the adjustment signal, wherein the adjustment reference signal has a waveform for correcting distortion of an input current by the filter current.
16. The method according to claim 15 , wherein correcting the filter current comprises:
correcting at least one of feedback information and a control signal according to the adjustment signal; and
turning off the power switch according to a control output based on a result of comparison between the compensated one of the feedback information and the control signal, and the other thereof.
17. The method according to claim 15 , wherein correcting the filter current comprises:
generating a control output based on a result of comparison between a feedback information and a control signal;
correcting the control output according to an adjustment signal; and
turning off the power switch according the compensated control output.