Systems and methods for load compensation with primary-side sensing and regulation for flyback power converters

1. A system for regulating an output voltage of a power conversion system, the system comprising:

a sampling component located on a chip configured to receive an input voltage through a terminal, the sampling component being configured to sample the input voltage and generate a sampled voltage;

an error amplifier configured to process information associated with the sampled voltage and a threshold voltage and generate a first output signal;

a first signal generator configured to generate a second output signal and one or more third output signals;

a comparator configured to receive the first output signal and the second output signal and generate a comparison signal;

a gate driver directly or indirectly coupled to the comparator and configured to generate a drive signal based on at least information associated with the comparison signal; and

a current generator configured to receive at least the one or more third output signals and generate a compensation current flowing out of the chip through the terminal;

wherein:

the gate driver is further coupled to a first switch configured to receive the drive signal and affect a first current flowing through a primary winding coupled to a secondary winding;

the secondary winding is associated with at least an output voltage of a power conversion system, the power conversion system including at least the primary winding, the secondary winding, and an auxiliary winding, the auxiliary winding being coupled to the secondary winding; and

the input voltage is associated with at least the auxiliary winding and depends on at least the output voltage and the compensation current;

wherein:

the second output signal starts to increase from a first magnitude at a first time;

the one or more third output signals represent a first time period since the first time during which the second output signal increases in magnitude; and

the compensation current decreases in magnitude if a second time period increases, the second time period starting from the first time and ending at a second time when the second output signal becomes equal to the first output signal in magnitude.

2. The system of claim 1 wherein the second output signal increases exponentially with time during the first time period.

3. The system of claim 1 wherein the second output signal increases exponentially with time during the second time period.

4. The system of claim 1 wherein:

the drive signal is associated with a switching period; and

the compensation current is approximately inversely proportional to the switching period in magnitude, each of the first time period and the second time period being a part of the switching period.

5. The system of claim 4 wherein the current generator is configured to perform a segmented curve fitting process so that the compensation current is approximately inversely proportional to the switching period in magnitude.

6. The system of claim 1 wherein:

the first signal generator is further configured to receive at least an input clock signal with an input clock period;

the one or more third output signals include one or more output clock signals corresponding to one or more output clock periods respectively; and

each of the one or more output clock periods is equal to the input clock period multiplied by an integer larger than 1.

7. The system of claim 1 wherein:

the current generator includes at least an encoding component, one or more current sinks, and one or more second switches;

the encoding component is further configured to receive the drive signal, process information associated with the drive signal and the one or more third output signals, and generate one or more control signals based on at least information associated with the one or more third output signals and the drive signal;

the one or more second switches are configured to be controlled by the one or more control signals respectively; and

each of the one or more current sinks is coupled to a corresponding switch selected from the one or more second switches and is configured to affect the compensation current if the corresponding switch is closed.

8. The system of claim 7 wherein the current generator further includes a signal filter, the signal filter including a resistor and a capacitor.

9. The system of claim 8 wherein both the resistor and the capacitor are located on the chip.

10. The system of claim 8 wherein the resistor is located on the chip, and the capacitor is not located on the chip.

11. The system of claim 8 wherein:

the current generator further includes a second signal generator and a third switch;

the second signal generator configured to receive the drive signal and generate a fourth output signal based on at least information associated with the drive signal to control the third switch; and

the third switch is coupled to the signal filter.

12. The system of claim 11 wherein the fourth output signal is associated with a predetermined pulse width.

13. The system of claim 1 wherein the gate driver is indirectly coupled to the comparator.

14. The system of claim 1 wherein the first switch includes one selected from a group consisting of a MOS transistor and a bipolar transistor.

15. A system for regulating an output voltage of a power conversion system, the system comprising:

a sampling component located on a chip configured to receive an input voltage through a terminal, the sampling component being configured to sample the input voltage and generate a sampled voltage;

an error amplifier configured to process information associated with the sampled voltage and a threshold voltage and generate a first output signal;

a signal generator configured to receive at least an input clock signal with an input clock period and generate a second output signal and one or more output clock signals corresponding to one or more output clock periods respectively, each of the one or more output clock periods being equal to the input clock period multiplied by an integer larger than 1;

a comparator configured to receive the first output signal and the second output signal and generate a comparison signal;

a gate driver directly or indirectly coupled to the comparator and configured to generate a drive signal based on at least information associated with the comparison signal; and

a current generator configured to receive at least the one or more output clock signals and generate a compensation current flowing out of the chip through the terminal based on at least information associated with the one or more output clock signals;

wherein:

the gate driver is further coupled to a first switch configured to receive the drive signal and affect a first current flowing through a primary winding coupled to a secondary winding;

the secondary winding is associated with at least an output voltage of a power conversion system, the power conversion system including at least the primary winding, the secondary winding, and an auxiliary winding, the auxiliary winding being coupled to the secondary winding; and

the input voltage is associated with at least the auxiliary winding and depends on at least the output voltage and the compensation current.

16. The system of claim 15 wherein the second output signal increases exponentially with time during a time period.

17. The system of claim 16 wherein:

the drive signal is associated with a switching period; and

the compensation current is approximately inversely proportional to the switching period in magnitude, the time period being a part of the switching period.

18. A method for regulating an output voltage of a power conversion system, the method comprising:

receiving an input voltage through a terminal of a chip;

sampling the input voltage;

generating a sampled voltage based on at least information associated with the input voltage;

processing information associated with the sampled voltage and a threshold voltage;

generating a first output signal based on at least information associated with the sampled voltage and the threshold voltage;

generating a second output signal and one or more third output signals;

receiving the first output signal and the second output signal;

generating a comparison signal based on at least information associated with the first output signal and the second output signal;

receiving the comparison signal;

process information associated with the comparison signal;

generating a drive signal based on at least information associated with the comparison signal to affect a first current flowing through a primary winding coupled to a secondary winding, the secondary winding being associated with at least an output voltage of a power conversion system and coupled to an auxiliary winding of the power conversion system;

receiving at least the one or more third output signals;

processing information associated with the one or more third output signals; and

generating a compensation current flowing out of the chip through the terminal based on at least information associated with the one or more third output signals;

wherein:

the input voltage depends on at least the output voltage and the compensation current;

the second output signal starts to increase from a first magnitude at a first time;

the one or more third output signals represent a first time period since the first time during which the second output signal increases in magnitude; and

the compensation current decreases in magnitude if a second time period increases, the second time period starting from the first time and ending at a second time when the second output signal becomes equal to the first output signal in magnitude.

19. The method of claim 18 wherein the second output signal increases exponentially with time during the first time period.

20. The method of claim 18 wherein the second output signal increases exponentially with time during the second time period.

21. The method of claim 18 wherein:

the drive signal is associated with a switching period; and

the compensation current is approximately inversely proportional to the switching period in magnitude, each of the first time period and the second time period being a part of the switching period.

22. The method of claim 21 wherein the process for generating a compensation current flowing out of the chip through the terminal includes performing a segmented curve fitting process so that the compensation current is approximately inversely proportional to the switching period in magnitude.

23. The method of claim 18 wherein the process for generating a second output signal and one or more third output signals includes:

receiving at least an input clock signal with an input clock period; and

generating one or more output clock signals corresponding to one or more output clock periods respectively, the one or more output clock signals being the one or more third output signals respectively, each of the one or more output clock periods being equal to the input clock period multiplied by an integer larger than 1.

24. The method of claim 18 , and further comprising:

receiving the drive signal; and

processing information associated with the drive signal;

wherein the process for generating a compensation current flowing out of the chip through the terminal includes:

generating one or more control signals based on at least information associated with the one or more third output signals and the drive signal;

processing information associated with the one or more control signals; and

generating the compensation current based on at least information associated with the one or more control signals.

25. The method of claim 24 wherein the process for generating the compensation current based on at least information associated with the one or more control signals includes:

generating a second current based on at least information associated with the one or more control signals;

processing information associated with the second current;

generating a filtered signal based on at least information associated with the second current;

processing information associated with the filtered signal; and

generating the compensation current based on at least information associated with the filtered signal.

26. The method of claim 25 wherein the process for generating a filtered signal based on at least information associated with the second current includes:

receiving the drive signal;

generating a fourth output signal based on at least information associated with the drive signal;

processing information associated with the fourth output signal; and

generating the filtered signal based on at least information associated with the second current and the fourth output signal.

27. The method of claim 26 wherein the fourth output signal is associated with a predetermined pulse width.

28. A method for regulating an output voltage of a power conversion system, the method comprising:

receiving an input voltage through a terminal of a chip;

sampling the input voltage;

generating a sampled voltage based on at least information associated with the input voltage;

processing information associated with the sampled voltage and a threshold voltage;

generating a first output signal based on at least information associated with the sampled voltage and the threshold voltage;

receiving at least an input clock signal with an input clock period;

generating a second output signal and one or more output clock signals based on at least information associated with the input clock signal, the one or more output clock signals corresponding to one or more output clock periods respectively, each of the one or more output clock periods being equal to the input clock period multiplied by an integer larger than 1;

receiving the first output signal and the second output signal;

generating a comparison signal based on at least information associated with the first output signal and the second output signal;

receiving the comparison signal;

process information associated with the comparison signal;

generating a drive signal based on at least information associated with the comparison signal to affect a first current flowing through a primary winding coupled to a secondary winding, the secondary winding being associated with at least an output voltage of a power conversion system and coupled to an auxiliary winding of the power conversion system;

receiving at least the one or more output clock signals;

processing information associated with the one or more output clock signals; and

generating a compensation current flowing out of the chip through the terminal based on at least information associated with the one or more output clock signals;

wherein the input voltage depends on at least the output voltage and the compensation current.

29. The method of claim 28 wherein the second output signal increases exponentially with time during a time period.

30. The method of claim 28 wherein:

the drive signal is associated with a switching period; and

the compensation current is approximately inversely proportional to the switching period in magnitude, the time period being a part of the switching period.