Systems and methods for output current regulation in power conversion systems

• US 10,003,268 B2
• Filed: 06/29/2015
• Issued: 06/19/2018
• Est. Priority Date: 05/15/2015
• 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: Fang, Qian, Zhai, Xiangkun, Fang, Lieyi
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): Quddus, Nusrat
• Application Number:
  US14/753,079
• Publication Number:
  US 20160336864A1
• Time in Patent Office: 1,086 Days
• Field of Search: 363 2112- 2118, 363 52, 363 53, 363125-127
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33515 with digital control
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Systems and methods are provided for regulating power conversion systems. A system controller includes: a first controller terminal configured to receive a first signal related to an input signal for a primary winding of a power conversation system; and a second controller terminal configured to output a drive signal to a switch to affect a current flowing through the primary winding, the drive signal being associated with a switching period including an on-time period and an off-time period. The switch is closed (e.g., being turned on) in response to the drive signal during the on-time period. The switch is opened (e.g., being turned off) in response to the drive signal during the off-time period. A duty cycle is equal to a duration of the on-time period divided by a duration of the switching period. The system controller is configured to keep a multiplication product of the duty cycle and the duration of the on-time period approximately constant.

Claims

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

a first controller terminal configured to receive a first signal related to an input signal for a primary winding of a power conversation system; and

a second controller terminal configured to output a drive signal to a switch to affect a first current flowing through the primary winding of the power conversion system, the drive signal being associated with a switching period including an on-time period and an off-time period;

wherein;

the switch is closed in response to the drive signal during the on-time period;

the switch is opened in response to the drive signal during the off-time period; and

a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;

wherein;

the system controller is configured to keep a multiplication product of the duty cycle and the duration of the on-time period approximately constant; and

the system controller is further configured to keep the multiplication product of the duty cycle and the duration of the on-time period approximately constant so that an average of the first current during one or more switching periods increases in magnitude with the increasing input signal over time and decreases in magnitude with the decreasing input signal over time.

2. The system controller of claim 1 wherein the system controller is further configured to keep the multiplication product of the duty cycle and the duration of the on-time period constant.

3. The system controller of claim 1, further comprising:

a ramp-current generator configured to receive a modulation signal and generate a ramp current based at least in part on the modulation signal;

a ramp-signal generator configured to receive the ramp current and generate a ramping signal based at least in part on the ramp current;

a modulation component configured to receive the ramping signal and generate the modulation signal based at least in part on the ramping signal; and

a driving component configured to receive the modulation signal and output the drive signal.

4. The system controller of claim 3 wherein the ramp-current generator includes:

an amplifier configured to generate an amplified signal based at least in part on the modulation signal;

a low-pass filter configured to receive the amplified signal and generate a filtered signal based at least in part on the amplified signal; and

a voltage-to-current converter configured to receive the filtered signal and generate the ramp current based at least in part on the filtered signal.

5. The system controller of claim 4 wherein the amplifier is further configured to:

in response to the modulation signal being at a first logic level, receive a reference signal and generate the amplified signal based at least in part on the reference signal; and

in response to the modulation signal being at a second logic level, receive a ground voltage and generate the amplified signal based at least in part on the ground voltage.

6. The system controller of claim 5 wherein the ramp-current generator further includes:

a first switch coupled to the amplifier and configured to be closed to pass the reference signal in response to the modulation signal being at the first logic level; and

a second switch coupled to the amplifier and configured to be closed to pass the ground voltage in response to the modulation signal being at the second logic level.

7. The system controller of claim 3, further comprising:

a demagnetization detector configured to receive a feedback signal associated with an output signal of the power conversion system and generate a trigger signal based at least in part on the feedback signal, the trigger signal indicating an end of a demagnetization process of the power conversion system; and

a logic controller configured to receive the trigger signal and generate a second signal based at least in part on the trigger signal to affect the drive signal.

8. The system controller of claim 7, further comprising:

an error amplifier configured to receive a reference signal and generate a third signal based at least in part on the reference signal.

9. The system controller of claim 8 wherein:

the error amplifier is further configured to generate the third signal to charge or discharge a capacitor to generate a compensation signal; and

the modulation component is further configured to receive the compensation signal and generate the modulation signal based at least in part on the compensation signal and the ramping signal.

10. The system controller of claim 3 wherein the ramping signal increases in magnitude at a ramping slope during the on-time period.

11. A system controller for regulating a power conversion system, the system controller comprising:

a ramp-current generator configured to receive a modulation signal and generate a ramp current based at least in part on the modulation signal;

a ramp-signal generator configured to receive the ramp current and generate a ramping signal based at least in part on the ramp current;

a modulation component configured to receive the ramping signal and generate the modulation signal based at least in part on the ramping signal; and

a driving component configured to receive the modulation signal and output a drive signal to a switch to affect a current flowing through a primary winding of a power conversion system, the drive signal being associated with a switching period including an on-time period and an off-time period;

wherein;

the switch is closed in response to the drive signal during the on-time period;

the switch is opened in response to the drive signal during the off-time period; and

a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;

wherein the ramp-current generator is further configured to generate the ramp current approximately proportional to the duty cycle in magnitude.

12. The system controller of claim 11 is configured to keep a multiplication product of the duty cycle and the duration of the on-time period approximately constant in response to the ramp current being approximately proportional to the duty cycle in magnitude.

13. The system controller of claim 11 wherein the ramp-current generator is further configured to generate the ramp current proportional to the duty cycle in magnitude.

14. The system controller of claim 13 is configured to keep a multiplication product of the duty cycle and the duration of the on-time period constant in response to the ramp current being proportional to the duty cycle in magnitude.

15. The system controller of claim 11 wherein the ramp-current generator includes:

an amplifier configured to generate an amplified signal based at least in part on the modulation signal;

a low-pass filter configured to receive the amplified signal and generate a filtered signal based at least in part on the amplified signal; and

a voltage-to-current converter configured to receive the filtered signal and generate the ramp current based at least in part on the filtered signal.

16. The system controller of claim 15 wherein the amplifier is further configured to:

in response to the modulation signal being at a first logic level, receive a reference signal and generate the amplified signal based at least in part on the reference signal; and

in response to the modulation signal being at a second logic level, receive a ground voltage and generate the amplified signal based at least in part on the ground voltage.

17. The system controller of claim 16 wherein the ramp-current generator further includes:

a first switch coupled to the amplifier and configured to be closed to pass the reference signal in response to the modulation signal being at the first logic level; and

a second switch coupled to the amplifier and configured to be closed to pass the ground voltage in response to the modulation signal being at the second logic level.

18. The system controller of claim 11, further comprising:

a demagnetization detector configured to receive a feedback signal associated with an output signal of the power conversion system and generate a trigger signal based at least in part on the feedback signal, the trigger signal indicating an end of a demagnetization process of the power conversion system; and

a logic controller configured to receive the trigger signal and generate a second signal based at least in part on the trigger signal to affect the drive signal.

19. The system controller of claim 18, further comprising:

an error amplifier configured to receive a reference signal and generate a third signal based at least in part on the reference signal.

20. The system controller of claim 19 wherein:

the error amplifier is further configured to generate the third signal to charge a capacitor to generate a compensation signal; and

the modulation component is further configured to receive the compensation signal and generate the modulation signal based at least in part on the compensation signal and the ramping signal.

21. The system controller of claim 11 wherein the ramping signal increases in magnitude at a ramping slope during the on-time period.

22. A system controller for regulating a power conversion system, the system controller comprising:

a first controller terminal configured to provide a compensation signal based on at least information associated with a first current flowing through a primary winding of a power conversion system;

a ramp-current generator configured to receive a modulation signal, the compensation signal and a first reference signal and generate a ramp current based at least in part on the modulation signal, the compensation signal and the first reference signal;

a ramp-signal generator configured to receive the ramp current and generate a ramping signal based at least in part on the ramp current;

a modulation component configured to receive the ramping signal and the compensation signal and generate the modulation signal based at least in part on the ramping signal and the compensation signal; and

a driving component configured to receive the modulation signal and output a drive signal to a switch to affect the first current, the drive signal being associated with a switching period including an on-time period and an off-time period;

wherein;

the switch is closed in response to the drive signal during the on-time period;

the switch is opened in response to the drive signal during the off-time period; and

a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;

wherein the ramp-current generator is further configured to generate the ramp current approximately proportional in magnitude to a multiplication product of the duty cycle and a difference, the difference representing the first reference signal minus the compensation signal in magnitude.

23. The system controller of claim 22 is configured to keep a multiplication product of the duty cycle and the duration of the on-time period approximately constant in response to the ramp current being approximately proportional in magnitude to the multiplication product of the duty cycle and the difference.

24. The system controller of claim 22 wherein the ramp-current generator is further configured to generate the ramp current proportional in magnitude to the multiplication product of the duty cycle and the difference.

25. The system controller of claim 24 is configured to keep a multiplication product of the duty cycle and the duration of the on-time period constant in response to the ramp current being proportional in magnitude to the multiplication product of the duty cycle and the difference.

26. The system controller of claim 22 wherein the ramp-current generator includes:

an amplifier configured to generate an amplified signal based at least in part on the modulation signal;

a low-pass filter configured to receive the amplified signal and generate a filtered signal based at least in part on the amplified signal; and

a voltage-to-current converter configured to receive the filtered signal and generate the ramp current based at least in part on the filtered signal.

27. The system controller of claim 26 wherein the amplifier is further configured to:

in response to the modulation signal being at a first logic level, receive a differential signal indicating a difference between the first reference signal and the compensation signal and generate the amplified signal based at least in part on the differential signal; and

in response to the modulation signal being at a second logic level, receive a ground voltage and generate the amplified signal based at least in part on the ground voltage.

28. The system controller of claim 27 wherein the ramp-current generator further includes:

a first switch coupled to the amplifier and configured to be closed to pass the differential signal in response to the modulation signal being at the first logic level; and

a second switch coupled to the amplifier and configured to be closed to pass the ground voltage in response to the modulation signal being at the second logic level.

29. The system controller of claim 27, further comprising an error amplifier configured to receive a second reference signal and generate a second signal based at least in part on the second reference signal to charge a capacitor to generate the compensation signal.

30. The system controller of claim 22, further comprising:

a demagnetization detector configured to receive a feedback signal associated with an output signal of the power conversion system and generate a trigger signal based at least in part on the feedback signal, the trigger signal indicating an end of a demagnetization process of the power conversion system; and

a logic controller configured to receive the trigger signal and generate a second signal based at least in part on the trigger signal to affect the drive signal.

31. The system controller of claim 22 wherein the ramping signal increases in magnitude at a ramping slope during the on-time period.

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

receiving a first signal related to an input signal for a primary winding of a power conversion system;

generating a drive signal associated with a switching period including an on-time period and an off-time period; and

outputting the drive signal to a switch to affect a current flowing through the primary winding of the power conversion system;

wherein the outputting the drive signal to the switch to affect the current includes;

outputting the drive signal to close the switch during the on-time period; and

outputting the drive signal to open the switch during the off-time period;

wherein a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;

wherein the generating the drive signal associated with the switching period includes keeping a multiplication product of the duty cycle and the duration of the on-time period approximately constant so that an average of the current during one or more switching periods increases in magnitude with the increasing input signal over time and decreases in magnitude with the decreasing input signal over time.

33. The method of claim 32 wherein the keeping the multiplication product of the duty cycle and the duration of the on-time period approximately constant includes keeping the multiplication product of the duty cycle and the duration of the on-time period constant.

34. A method for regulating a power conversion system, the method comprising:

receiving a modulation signal;

generating a ramp current based at least in part on the modulation signal;

receiving the ramp current;

generating a ramping signal based at least in part on the ramp current;

receiving the ramping signal;

generating the modulation signal based at least in part on the ramping signal;

receiving the modulation signal;

generating a drive signal based at least in part on the modulation signal, the drive signal being associated with a switching period including an on-time period and an off-time period; and

outputting the drive signal to a switch to affect a first current flowing through a primary winding of a power conversion system;

wherein the outputting the drive signal to the switch to affect the first current includes;

outputting the drive signal to close the switch during the on-time period; and

outputting the drive signal to open the switch during the off-time period;

wherein a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;

wherein the generating the ramp current based at least in part on the modulation signal includes generating the ramp current approximately proportional to the duty cycle in magnitude.

35. The method of claim 34 wherein the generating the ramp current approximately proportional to the duty cycle in magnitude includes generating the ramp current proportional to the duty cycle in magnitude.

36. A method for regulating a power conversion system, the method comprising:

providing a compensation signal based on at least information associated with a first current flowing through a primary winding of a power conversion system;

receiving a modulation signal, the compensation signal and a reference signal;

generating a ramp current based at least in part on the modulation signal, the compensation signal and the reference signal;

receiving the ramp current;

generating a ramping signal based at least in part on the ramp current;

receiving the ramping signal and the compensation signal;

generating the modulation signal based at least in part on the ramping signal and the compensation signal;

receiving the modulation signal; and

outputting a drive signal to a switch to affect the first current, the drive signal being associated with a switching period including an on-time period and an off-time period;

wherein the outputting the drive signal to the switch to affect the first current includes;

outputting the drive signal to close the switch during the on-time period; and

outputting the drive signal to open the switch during the off-time period;

wherein a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;

wherein the generating the ramp current based at least in part on the modulation signal, the compensation signal and the reference signal includes generating the ramp current approximately proportional in magnitude to a multiplication product of the duty cycle and a difference, the difference representing the reference signal minus the compensation signal in magnitude.

37. The method of claim 36 wherein the generating the ramp current approximately proportional in magnitude to the multiplication product of the duty cycle and the difference includes generating the ramp current proportional in magnitude to the multiplication product of the duty cycle and the difference.