System and method for reducing line current distortion

1. A power factor correction (PFC) system, comprising:

an adjustment module that generates N time advances based on N predetermined time advances and (N−1) time advance adjustments, wherein N is an integer greater than zero;

a compensation module that generates N compensated versions of an input alternating current (AC) line signal by predicting ahead of the input AC line signal using a gradient of a sinusoidal reference signal and the N time advances, respectively, wherein the sinusoidal reference signal is synchronized with the input AC line signal in phase and frequency; and

a duty cycle control module that generates PFC duty cycles based on the N compensated versions of the input AC line signal.

2. The PFC system of claim 1 , further comprising:

a predicted zero-crossing detection module that generates an inversion signal based on predicted zero-crossings of the input AC line signal,

wherein the predicted zero-crossing detection module predicts the zero-crossings based on the input AC line signal,

wherein the PFC duty cycles are inverted based on the inversion signal.

3. The PFC system of claim 2 , wherein:

full inversion of the PFC duty cycles occurs over a first length of time,

the predicted zero-crossing detection module switches a state of the inversion signal based on a predicted zero-crossing of an advanced version of the input AC line signal,

the predicted zero-crossing detection module generates the advanced version of the input AC line signal by predicting ahead by a time advance, and

the time advance is based on a sum of a control system delay of the PFC system and half of the first length of time.

4. The PFC system of claim 3 , wherein the predicted zero-crossing detection module generates the advanced version of the input AC line signal by extrapolating a present value of the input AC line signal by the time advance along a present gradient of the sinusoidal reference signal.

5. The PFC system of claim 2 , further comprising:

a notch filter that generates a filtered AC signal by filtering out a predetermined frequency of the input AC line signal, wherein the predetermined frequency is based on a control system delay of the PFC system, wherein the compensation module generates the N compensated versions of the input AC line signal by predicting ahead of the filtered AC signal, and wherein the predicted zero-crossing detection module predicts the zero-crossings based on the filtered AC signal.

6. The PFC system of claim 1 , further comprising:

a notch filter that generates a filtered AC signal by filtering out a predetermined frequency of the input AC line signal, wherein the predetermined frequency is based on a control system delay of the PFC system, and wherein the compensation module generates the N compensated versions of the input AC line signal by predicting ahead of the filtered AC signal.

7. The PFC system of claim 1 , wherein for each version of the N compensated versions of the input AC line signal, the compensation module generates the version by extrapolating a present value of the input AC line signal by a corresponding one of the N time advances along a present gradient of the sinusoidal reference signal.

8. The PFC system of claim 1 , wherein the (N−1) time advance adjustments are based on differences between N measured currents having different phases, wherein N is an integer greater than one.

9. The PFC system of claim 1 , wherein the N predetermined time advances are set at design time.

10. A method for power factor correction (PFC), comprising:

generating N time advances based on N predetermined time advances and (N−1) time advance adjustments, wherein N is an integer greater than zero;

generating N compensated versions of an input alternating current (AC) line signal by predicting ahead of the input AC line signal using a gradient of a sinusoidal reference signal and the N time advances, respectively, wherein the sinusoidal reference signal is synchronized with the input AC line signal in phase and frequency; and

generating PFC duty cycles based on the N compensated versions of the input AC line signal.

11. The method of claim 10 , further comprising:

generating an inversion signal based on predicted zero-crossings of the input AC line signal;

predicting the zero-crossings based on the input AC line signal; and

inverting the PFC duty cycles based on the inversion signal.

12. The method of claim 11 , wherein:

full inversion of the PFC duty cycles occurs over a first length of time;

switching a state of the inversion signal based on a predicted zero-crossing of an advanced version of the input AC line signal; and

generating the advanced version of the input AC line signal by predicting ahead by a time advance, wherein the time advance is based on a sum of a control system delay of a PFC system and half of the first length of time.

13. The method of claim 12 , further comprising generating the advanced version of the input AC line signal by extrapolating a present value of the input AC line signal by the time advance along a present gradient of the sinusoidal reference signal.

14. The method of claim 11 , further comprising:

generating a filtered AC signal by filtering out a predetermined frequency of the input AC line signal using a notch filter, wherein the predetermined frequency is based on a control system delay of a PFC system.

15. The method of claim 14 , further comprising:

generating the N compensated versions of the input AC line signal by predicting ahead of the filtered AC signal; and

predicting the zero-crossings based on the filtered AC signal.

16. The method of claim 10 , further comprising:

generates a filtered AC signal by filtering out a predetermined frequency of the input AC line signal using a notch filter, wherein the predetermined frequency is based on a control system delay of a PFC system; and

generating the N compensated versions of the input AC line signal by predicting ahead of the filtered AC signal.

17. The method of claim 10 , further comprising for each version of the N compensated versions of the input AC line signal, generating the version by extrapolating a present value of the input AC line signal by a corresponding one of the N time advances along a present gradient of the sinusoidal reference signal.

18. The method of claim 10 , wherein the (N−1) time advance adjustments are based on differences between N measured currents having different phases, wherein N is an integer greater than one.

19. The method of claim 10 , wherein the N predetermined time advances are set at design time.

20. A method for power factor correction (PFC), comprising:

receiving an input alternating current (AC) line signal;

generating a filtered AC signal by filtering out a predetermined frequency of the input AC line signal using a notch filter, wherein the predetermined frequency is based on a control system delay of a PFC system;

generating a sinusoidal reference signal that is synchronized with the input AC line signal in phase and frequency;

generating N time advances based on N predetermined time advances and (N−1) time advance adjustments, wherein N is an integer greater than zero;

for each of N compensated versions of the input AC line signal, generating the version by extrapolating a present value of the filtered AC line signal by a corresponding one of the N time advances along a present gradient of the sinusoidal reference signal;

generating PFC duty cycles based on the N compensated versions of the input AC line signal;

predicting zero-crossings based on the filtered AC line signal;

generating an inversion signal based on predicted zero-crossings of the filtered AC line signal;

inverting the PFC duty cycles based on the inversion signal;

generating an advanced version of the filtered AC line signal by predicting ahead by a time advance that includes a sum of a control system delay of a PFC system and half of a time for full inversion of the PFC duty cycles; and

switching a state of the inversion signal based on a predicted zero-crossing of the advanced version of the filtered AC line signal.