Systems and methods for constant voltage mode and constant current mode in flyback power converters with primary-side sensing and regulation

• US 10,277,132 B2
• Filed: 05/11/2016
• Issued: 04/30/2019
• Est. Priority Date: 10/21/2008
• Status: Active Grant

• Current Assignee: On-Bright Electronics (Shanghai) Co., Ltd. (Orthosie Investment Holdings Ltd.)
• Original Assignee: On-Bright Electronics (Shanghai) Co., Ltd. (Orthosie Investment Holdings Ltd.)
• Inventors: Zhang, Yunchao, Cao, Yaming, Huang, Xiaomin, Zhang, Xiuhong, Fang, Lieyi
• Primary Examiner(s): Nash, Gary A
• Application Number:
  US15/152,362
• Publication Number:
  US 20160329821A1
• Time in Patent Office: 1,084 Days
• Field of Search: 363 2113, 363 2116- 2118, 363 50, 363 55, 363 5601, 363 5609- 5611
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33515 with digital control
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

System and method for regulating a power converter. The system includes a first signal generator configured to receive a first sensed signal and generate an output signal associated with demagnetization. The first sensed signal is related to a first winding coupled to a secondary winding for a power converter, and the secondary winding is associated with at least an output current for the power converter. Additionally, the system includes a ramping signal generator configured to receive the output signal and generate a ramping signal, and a first comparator configured to receive the ramping signal and a first threshold signal and generate a first comparison signal based on at least information associated with the ramping signal and the first threshold signal. Moreover, the system includes a second comparator configured to receive a second sensed signal and a second threshold signal and generate a second comparison signal.

Claims

1. A system for regulating a power converter, the system comprising:

a ramping signal generator configured to receive a demagnetization signal and generate a ramping signal;

a first comparator configured to receive the ramping signal and a first threshold signal and generate a first comparison signal based at least in part on the ramping signal and the first threshold signal;

a second comparator configured to receive a sensed signal and a second threshold signal and generate a second comparison signal, the sensed signal being associated with a current flowing through a primary winding of the power converter;

a drive signal generator configured to receive at least the first comparison signal and the second comparison signal and output a drive signal to a switch, the switch being configured to affect the current flowing through the primary winding;

wherein;

the demagnetization signal is associated with a demagnetization duration;

the drive signal is associated with a switching period; and

the system is further configured to keep a ratio of the demagnetization duration to the switching period constant.

2. The system of claim 1 is further configured to keep a peak of the sensed signal constant in magnitude.

3. The system of claim 2 is further configured to keep an output current associated with a secondary winding constant, the secondary winding being coupled to the primary winding of the power converter.

4. The system of claim 1 wherein the drive signal generator includes a flip-flop.

5. A system for regulating a power converter, the system comprising:

an oscillator configured to receive a first control signal based at least in part on a demagnetization signal and generate a clock signal based at least in part on the first control signal; and

a drive signal generator configured to receive the clock signal and a second control signal based at least in part on a first sensed signal, the first sensed signal being associated with a current flowing through a primary winding for a power converter, and output a drive signal to a switch, the switch being configured to affect the current flowing through the primary winding;

wherein;

the demagnetization signal is associated with a demagnetization duration; and

the drive signal is associated with a switching period;

wherein the system is further configured to;

keep a ratio of the demagnetization duration to the switching period constant; and

keep a peak of the first sensed signal constant in magnitude.

6. The system of claim 5, and further comprising:

a compensator configured to generate a compensation signal; and

a signal generator configured to receive an input signal and generate the demagnetization signal, the input signal being related to an output current for the power converter;

wherein;

the input signal is a combination of the compensation signal and a second sensed signal,

the second sensed signal is associated with a first winding coupled to a secondary winding for the power converter; and

the secondary winding is related to the output current for the power converter.

7. A system for regulating a power converter, the system comprising:

a first comparator configured to receive a first ramping signal based at least in part on a demagnetization signal and a first threshold signal and generate a first comparison signal based at least in part on the first ramping signal and the first threshold signal;

a peak detector configured to receive a drive signal and a sensed signal and generate a peak signal, the sensed signal being associated with a current flowing through a primary winding of a power converter;

an amplifier configured to receive the peak signal and a second threshold signal and generate an output signal with a capacitor;

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

a drive signal generator configured to receive the first comparison signal and the second comparison signal and output the drive signal to the peak detector and a switch, the switch being configured to affect the current flowing through the primary winding.

8. The system of claim 7 wherein:

the demagnetization signal is associated with a demagnetization duration;

the drive signal is associated with a switching period; and

the system is further configured to keep a ratio of the demagnetization duration to the switching period constant.

9. The system of claim 7 is further configured to keep an average magnitude of the peak signal over a first duration constant.

10. The system of claim 9 is further configured to keep an output current associated with a secondary winding of the power converter constant, the secondary winding being coupled to the primary winding of the power converter.

11. The system of claim 7 wherein the peak signal represents a peak magnitude of the sensed signal within each switching period of the drive signal.

12. The system of claim 7 wherein the drive signal generator includes a flip-flop.

13. A system for regulating a power converter, the system comprising:

a peak detector configured to receive a drive signal and a sensed signal and generate a peak signal, the sensed signal being associated with a current flowing through a primary winding of a power converter;

a signal generator configured to receive the peak signal and a demagnetization signal and generate a modulation signal; and

a drive signal generator configured to receive the modulation signal and output the drive signal to the peak detector and a switch, the switch being configured to affect the current flowing through the primary winding;

wherein;

the demagnetization signal is associated with a demagnetization duration; and

the drive signal is associated with a switching period;

wherein the system is further configured to;

keep a ratio of the demagnetization duration to the switching period constant;

or

keep an average magnitude of the peak signal over a first duration constant.

14. The system of claim 13 is further configured to keep an output current associated with a secondary winding of the power converter constant, the secondary winding being coupled to the primary winding of the power converter.

15. A system for regulating a power converter, the system comprising:

a first signal generator configured to receive a drive signal and a peak signal based at least in part on the drive signal and a sensed signal, the sensed signal being associated with a current flowing through a primary winding of a power converter, and generate a first output signal;

an amplifier configured to receive the first output signal and a threshold signal and generate a second output signal with a capacitor;

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

a second signal generator configured to receive the comparison signal and a clock signal and generate a modulation signal; and

a drive signal generator configured to receive the modulation signal and output the drive signal to a peak detector, the first signal generator and a switch, the switch being configured to affect the current flowing through the primary winding.

16. The system of claim 15 wherein:

the drive signal is associated with a switching period; and

the system is further configured to keep the switching period constant.

17. The system of claim 16 wherein:

the first signal generator is further configured to receive a demagnetization signal associated with a demagnetization duration;

the demagnetization duration multiplied by the peak signal in magnitude is equal to a demagnetization peak value; and

the system is further configured to keep an average magnitude of the demagnetization peak value over a first duration constant.

18. The system of claim 17 wherein the first output signal is proportional to the demagnetization duration multiplied by the peak signal in magnitude.

19. The system of claim 17 is further configured to keep an output current associated with a secondary winding of the power converter constant, the secondary winding being coupled to the primary winding of the power converter.

20. The system of claim 15 is further configured to keep a power factor associated with the power converter substantially equal to 1.

21. The system of claim 15 wherein the second signal generator includes a flip-flop coupled to an AND gate.

22. The system of claim 15 wherein the peak signal represents a peak magnitude of the sensed signal within a switching period of the drive signal.

23. The system of claim 15 wherein the first signal generator includes a cycle-by-cycle integrator, the cycle-by-cycle integrator being reset for each switching period.

24. A system for regulating a power converter, the system comprising:

a first signal generator configured to receive a drive signal and a peak signal based at least in part on the drive signal and a sensed signal, the sensed signal being associated with a current flowing through a primary winding of a power converter, and generate a first output signal;

an amplifier configured to receive the first output signal and a threshold signal and generate a second output signal with a capacitor;

a second signal generator configured to receive the second output signal and a first input signal and generate a third output signal, the first input signal being proportional to a second input signal received by the primary winding;

a comparator configured to receive the third output signal and the sensed signal and generate a comparison signal;

a third signal generator configured to receive the comparison signal and a clock signal and generate a modulation signal; and

a drive signal generator configured to receive the modulation signal and output the drive signal to a peak detector, the first signal generator, and a switch, the switch being configured to affect the current flowing through the primary winding.

25. The system of claim 24 wherein the second signal generator includes a multiplier configured to generate the third output signal equal to the second output signal multiplied by the first input signal in magnitude.

26. The system of claim 24 wherein:

the drive signal is associated with a switching period; and

the system is further configured to keep the switching period constant.

27. The system of claim 24 wherein:

the first signal generator is configured to receive a demagnetization signal associated with a demagnetization duration;

the demagnetization duration multiplied by the peak signal in magnitude is equal to a demagnetization peak value; and

the system is further configured to keep an average magnitude of the demagnetization peak value over a first duration constant.

28. The system of claim 27 wherein the first output signal is proportional to the demagnetization duration multiplied by the peak signal in magnitude.

29. The system of claim 24 is further configured to keep a power factor associated with the power converter substantially equal to 1.

30. The system of claim 24 wherein the peak signal represents a peak magnitude of the sensed signal within each switching period of the drive signal.

31. The system of claim 24 wherein the first signal generator includes a cycle-by-cycle integrator, the cycle-by-cycle integrator being reset for each switching period.

32. A system for regulating a power converter, the system comprising:

a first signal generator configured to receive a drive signal and a peak signal based at least in part on the drive signal and a first sensed signal, the first sensed signal being associated with a current flowing through a primary winding of a power converter, and generate a first output signal;

an amplifier configured to receive the first output signal and a threshold signal and generate a second output signal with a capacitor;

a second signal generator configured to receive a second sensed signal, the second output signal and the drive signal and generate a third output signal;

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

a third signal generator configured to receive the comparison signal and a clock signal and generate a modulation signal; and

a drive signal generator configured to receive the modulation signal and output the drive signal to a peak detector, the first signal generator, the second signal generator, and a first switch, the first switch being configured to affect the current flowing through the primary winding.

33. The system of claim 32 wherein the second signal generator includes:

a second switch configured to receive the second sensed signal and the drive signal;

a multiplier configured to output the third output signal; and

an operational amplifier coupled to the second switch and the multiplier.

34. The system of claim 32 wherein:

the drive signal is associated with a switching period; and

the system is further configured to keep the switching period constant.

35. The system of claim 34 wherein:

the first signal generator is further configured to receive a demagnetization signal associated with a demagnetization duration;

the demagnetization duration multiplied by the peak signal in magnitude is equal to a demagnetization peak value; and

the system is further configured to keep an average magnitude of the demagnetization peak value over a first duration constant.

36. The system of claim 35 wherein the first output signal is proportional to the demagnetization duration multiplied by the peak signal in magnitude.

37. The system of claim 32 is further configured to keep a power factor associated with the power converter substantially equal to 1.

38. A system for regulating a power converter, the system comprising:

a signal generator configured to receive a peak signal and a demagnetization signal and generate a modulation signal; and

a drive signal generator configured to receive the modulation signal based at least in part on the peak signal and a demagnetization and output a drive signal to a peak detector and a switch, the switch being configured to affect a current flowing through a primary winding of a power converter;

wherein;

the peak signal is based at least in part on the drive signal and a sensed signal;

the sensed signal is associated with the current flowing through the primary winding of the power converter;

the drive signal is associated with a switching period;

the demagnetization signal is associated with a demagnetization duration; and

the demagnetization duration multiplied by the peak signal in magnitude is equal to a demagnetization peak value;

wherein the system is further configured to;

keep the switching period constant;

keep an average magnitude of the demagnetization peak value over a first duration constant; and

keep an output current associated with a secondary winding of the power converter constant.