System and method for power factor correction frequency tracking and reference generation

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

a period determination module that determines a period of an input alternating current (AC) line signal based on a time between rising edges of the input AC line signal;

a frequency generation module that generates a frequency based on the period;

an angle generation module that generates an angle based on the frequency;

a signal generation module that generates a sinusoidal reference signal based on the frequency and an adjusted angle; and

an angle correction module that generates the adjusted angle based on the angle and based on a comparison of a falling edge of the sinusoidal reference signal, the period, and a rising edge of the input AC line signal.

2. The PFC system of claim 1 , further comprising a rising edge module that determines first and second timestamps corresponding to the rising edges of the input AC line signal, wherein the period determination module determines the period of the input AC line signal based on a difference between the first and second timestamps.

3. The PFC system of claim 1 , further comprising an elapsed time module that measures an elapsed time since a rising edge of the input AC line signal, wherein the period determination module determines the period of the input AC line signal based on the elapsed time when a rising edge of the input AC line signal is detected, and wherein the period determination module discards the determined period when the determined period is greater than a predetermined threshold.

4. The PFC system of claim 1 , wherein the angle correction module:

generates an angle adjustment based on an error;

determines the error based on a difference between a time of a falling edge of the sinusoidal reference signal and a time half of the period after a rising edge of the input AC line signal; and

generates the adjusted angle by adding the angle adjustment to the angle.

5. The PFC system of claim 4 , wherein the angle correction module includes a phase error determination module that determines the error based on at least one of

a difference between (i) a time of a falling edge of the sinusoidal reference signal and (ii) a time of a rising edge of the input AC line signal plus half of the period; and

a difference between, at a time of a falling edge of the sinusoidal reference signal, (i) half of the period and (ii) the value of an elapsed time since a rising edge of the input AC line signal.

6. The PFC system of claim 4 , wherein the angle correction module further includes:

a gain module that generates a first output by applying a gain to the error;

a saturation module that generates a second output by selectively applying at least one of an upper limit and a lower limit to the first output;

an integrator module that generates the angle adjustment based on an integration of the second output; and

a hold module that prevents the integrator module from integrating the second output when the second output is outside of a predetermined range of acceptable values.

7. The PFC system of claim 6 wherein the hold module replaces the second output received by the integrator module with a zero value when the second output is outside of the predetermined range of acceptable values.

8. The PFC system of claim 6 wherein the hold module disables integration action of the integrator module when the second output is outside of the predetermined range of acceptable values.

9. The PFC system of claim 1 , wherein the signal generation module generates the sinusoidal reference signal based on a first trigonometric function having arguments of the frequency and the adjusted angle.

10. The PFC system of claim 9 , wherein the signal generation module generates:

a gradient of the sinusoidal reference signal based on a second trigonometric function of the frequency and the adjusted angle; and

a scaled reference signal and a scaled gradient signal based on multiplying the sinusoidal reference signal and the gradient, respectively, by a scaling factor,

wherein the scaling factor includes a product of a trigonometric constant and a statistical measure of the input AC line signal.

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

determining a period of an input alternating current (AC) line signal based on a time between rising edges of the input AC line signal;

generating a frequency based on the period;

generating an angle based on the frequency;

generating a sinusoidal reference signal based on the frequency and an adjusted angle; and

generating the adjusted angle based on the angle and based on a comparison of a falling edge of the sinusoidal reference signal, the period, and a rising edge of the input AC line signal.

12. The method of claim 11 , further comprising:

determining first and second timestamps corresponding to the rising edges of the input AC line signal; and

determining the period of the input AC line signal based on a difference between the first and second timestamps.

13. The method of claim 11 , further comprising:

measuring an elapsed time since a rising edge of the input AC line signal;

determining the period of the input AC line signal based on the elapsed time when a rising edge of the input AC line signal is detected; and

discarding the determined period when the determined period is greater than a predetermined threshold.

14. The method of claim 11 , further comprising:

generating an angle adjustment based on an error;

determining the error based on a difference between a time of a falling edge of the sinusoidal reference signal and a time half of the period after a rising edge of the input AC line signal; and

generating the adjusted angle by adding the angle adjustment to the angle.

15. The method of claim 14 , further comprising determining the error based on at least one of

a difference between (i) a time of a falling edge of the sinusoidal reference signal and (ii) a time of a rising edge of the input AC line signal plus half of the period; and

a difference between, at a time of a falling edge of the sinusoidal reference signal, (i) half of the period and (ii) the value of an elapsed time since a rising edge of the input AC line signal.

16. The method of claim 14 , further comprising:

generating a first output by applying a gain to the error;

generating a second output by selectively applying at least one of an upper limit and a lower limit to the first output;

generating the angle adjustment based on an integration of the second output; and

preventing the integrating of the second output when the second output is outside of a predetermined range of acceptable values.

17. The method of claim 16 , further comprising when the second output is outside of the predetermined range of acceptable values, at least one of (i) replacing the second output with a zero value and (ii) disabling the integrating.

18. The method of claim 11 , further comprising generating the sinusoidal reference signal based on a first trigonometric function having arguments of the frequency and the adjusted angle.

19. The method of claim 18 , further comprising:

generating a gradient of the sinusoidal reference signal based on a second trigonometric function of the frequency and the adjusted angle; and

generating a scaled reference signal and a scaled gradient signal based on multiplying the sinusoidal reference signal and the gradient, respectively, by a scaling factor,

wherein the scaling factor includes a product of a trigonometric constant and a statistical measure of the input AC line signal.

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

receiving an input alternating current (AC) line signal;

determining a period of the input AC line signal based on a time between rising edges of the input AC line signal;

generating a frequency based on the period;

generating an angle based on the frequency;

generating a sinusoidal reference signal based on a first trigonometric function having arguments of the frequency and an adjusted angle;

generating a gradient of the sinusoidal reference signal based on a second trigonometric function of the frequency and the adjusted angle;

scaling at least one of the sinusoidal reference signal and the gradient by multiplying the at least one of the sinusoidal reference signal and the gradient by a scaling factor;

determining an error based on a difference between a time of a falling edge of the sinusoidal reference signal and a time half of the period after a rising edge of the input AC line signal;

generating a first output by applying a gain to the error;

generating a second output by selectively applying at least one of an upper limit and a lower limit to the first output;

generating an angle adjustment based on an integration of the second output;

preventing the integration of the second output when the second output is outside of a predetermined range of acceptable values; and

generating the adjusted angle by adding the angle adjustment to the angle.