Claims
- 1. A power converter for delivering power from a source to a load, comprising:
a switch; a pulse modulating controller producing power pulses for cycling the switch ON and OFF, wherein if a switch is cycled ON and OFF according to a cycle of a power pulse, power is transferred from the source to the load; and a comparator for comparing an output voltage feedback signal to a reference, wherein the pulse modulating controller controls the turn ON and turn OFF times of the switch in response to an output of the comparator, the controller sampling the comparator output at one or more determined times during a cycling of the switch.
- 2. The power converter of claim 1, wherein the comparator is one of a binary comparator, a ternary comparator, and a signed digital comparator.
- 3. The power converter of claim 1, wherein the controller takes into account comparator outputs from one or more previous switch cycles in determining the turn ON and turn OFF times of the switch in response to a present comparator output.
- 4. The power converter of claim 1, wherein the determined sample times are determined for each cycling of the switch.
- 5. The power converter of claim 1, wherein one determined sample time is an instant at which the output voltage feedback signal corresponds to the output voltage plus a small, substantially constant voltage drop measured from cycle to cycle of the switch.
- 6. The power converter of claim 1, wherein the converter is transformer-coupled having its output coupled to the load through a rectifying element, the output voltage feedback signal originating from the primary side of the converter.
- 7. The power converter of claim 6, wherein one determined sample time is an instant at which current flowing through the rectifying element is small and substantially constant from cycle to cycle of the switch.
- 8. The power converter of claim 6, wherein the converter is a flyback converter having a transformer flux reset point, the output voltage feedback signal is a reflected flyback voltage signal, and wherein one determined sample time is a fixed backward offset time from the transformer flux reset point.
- 9. The power converter of claim 8, wherein the transformer flux reset point is determined using a measured or calculated value of the period of resonant oscillation of the reflected flyback voltage signal.
- 10. The power converter of claim 8, wherein the transformer flux reset point is determined using a point at which the voltage across an auxiliary transformer winding is approximately zero.
- 11. The power converter of claim 8, wherein the transformer flux reset point is determined using a point at which the voltage across the primary winding of the power transformer is approximately zero.
- 12. The power converter of claim 6, wherein the converter is a forward converter having an-output inductor, the output voltage feedback signal is a reflected voltage across an auxiliary winding coupled to the output inductor, and wherein one determined sample time is a fixed backward offset time from a point of output inductor flux reset.
- 13. The power converter of claim 1, wherein the converter is a direct-coupled boost converter, the output voltage feedback signal corresponds to a voltage across the switch during its OFF time, and wherein one determined sample time is an instant at which current through a rectifying element is small and substantially constant from cycle to cycle of the switch.
- 14. The power converter of claim 4, wherein the converter is a direct-coupled buck converter, the output voltage feedback signal corresponds to a differential voltage across an output inductor during the OFF time of the switch, and wherein one determined sample time is an instant at which current through a rectifying element is small and substantially constant from cycle to cycle of the switch.
- 15. The power converter of claim 1, wherein the pulse modulating controller comprises pulse generation circuitry.
- 16. The power converter of claim 1, wherein the pulse modulating controller comprises a state machine.
- 17. The power converter of claim 1, wherein the pulse modulating controller is implemented as software on a programmable processor.
- 18. A power converter for delivering power from a source to a load, comprising:
a switch; pulse generation circuitry producing a drive signal for cycling the switch ON and OFF, wherein if the switch is cycled ON and OFF according to a cycle of a drive signal, power is transferred from the source to the load; a comparator for comparing an output voltage feedback signal to a reference; and a pulse modulating controller coupled to the pulse generation circuitry for controlling the turn ON and turn OFF times of the switch in response to an output of the comparator to maintain output voltage regulation, wherein the pulse modulating controller samples the comparator output at an instant in which current flowing through a secondary rectifying element is substantially constant from cycle to cycle of the switch.
- 19. The power converter of claim 18, wherein the comparator is selected from a group comprising a binary comparator, a ternary comparator, and a signed digital comparator.
- 20. The power converter of claim 18, wherein the pulse modulating controller takes into account comparator outputs from one or more previous switch cycles in determining the turn ON and turn OFF times of the switch in response to a present comparator output.
- 21. The power converter of claim 18, wherein the power converter is a transformer-coupled power converter having its output coupled through a rectifying element, the feedback signal originating from the primary side of the converter.
- 22. The power converter of claim 21, wherein the converter is a flyback converter, the feedback signal is a reflected flyback voltage signal, and the instant at which the comparator is sampled is a fixed backward offset time from a transformer flux reset point during a switch cycle.
- 23. The power converter of claim 22, wherein the transformer flux reset point is determined using a measured or calculated value of the period of resonant oscillation of the reflected flyback voltage signal.
- 24. The power converter of claim 22, wherein the transformer flux reset point is determined using a point at which the voltage across an auxiliary transformer winding is approximately zero.
- 25. The power converter of claim 22, wherein the transformer flux reset point is determined using a point at which the voltage across the primary winding of the power transformer is approximately zero.
- 26. The power converter of claim 21, wherein the converter is a forward converter having an output inductor, the output voltage feedback signal is a reflected voltage across an auxiliary winding coupled to the output inductor, and the instant at which the comparator is sampled is a fixed backward offset time from an output inductor flux reset point.
- 27. The power converter of claim 18, wherein the converter is a direct-coupled boost converter, the output voltage feedback signal corresponds to a voltage across the switch during its OFF time, and the instant at which the comparator is sampled is a time at which current through a rectifying element is small and substantially constant from cycle to cycle of the switch.
- 28. The power converter of claim 18, wherein the converter is a direct-coupled buck converter, the output voltage feedback signal corresponds to a differential voltage across an output inductor during the OFF time of the switch, and the instant at which the comparator is sampled is a time at which current through a rectifying element is small and substantially constant from cycle to cycle of the switch.
- 29. A power converter for delivering power from a source to a load, comprising:
a switch; pulse control circuitry producing a drive signal for cycling the switch ON and OFF, wherein if the switch is cycled ON and OFF according to a cycle of the drive signal, power is transferred from the source to the load; and an early/late detector for detecting a crossover time relative to an expected crossover time of an output voltage feedback signal with a reference, the pulse control circuitry controlling the turn ON and turn OFF times of the switch in response to an output of the detector.
- 30. The power converter of claim 29, wherein the detector is one of a binary detector, a ternary detector, and a signed digital detector.
- 31. The power converter of claim 30, wherein the pulse control circuitry takes into account detector outputs from one or more previous switch cycles in determining the turn ON and turn OFF times of the switch in response to a present detector output.
- 32. The power converter of claim 29, wherein the expected crossover time is determined for each cycling of the switch.
- 33. The power converter of claim 29, wherein the expected crossover time is an instant at which the output voltage feedback signal corresponds to the output voltage plus a small, substantially constant voltage drop measured from cycle to cycle of the switch.
- 34. The power converter of claim 29, wherein the expected crossover time is an instant at which current flowing through a secondary rectifying element is small and substantially constant from cycle to cycle of the switch.
- 35. The power converter of claim 29, wherein the converter is a flyback converter having a transformer flux reset point, the output voltage feedback signal is a reflected flyback voltage signal, and the expected crossover time is at a fixed backward offset time from the transformer flux reset point.
- 36. The power converter of claim 29, wherein the converter is a forward converter having an output inductor, the output voltage feedback signal is a reflected voltage across an auxiliary winding coupled to the output inductor, and the expected crossover time is a fixed backward offset time from a point of output inductor flux reset.
- 37. The power converter of claim 29, wherein the converter is a direct-coupled boost converter, the output voltage feedback signal corresponds to a voltage across the switch during its OFF time, and the expected crossover time is an instant at which current through a rectifying element is small and substantially constant from cycle to cycle of the switch.
- 38. The power converter of claim 29, wherein the converter is a direct-coupled buck converter, the output voltage feedback signal corresponds to a differential voltage across an output inductor during the OFF time of the switch, and the expected crossover time is at an instant at which current through a rectifying element is small and substantially constant from cycle to cycle of the switch.
- 39. The power converter of claim 29, wherein the pulse control circuitry is implemented as software on a programmable processor.
- 40. The power converter of claim 29, wherein the pulse control circuitry is implemented as software on a programmable processor.
- 41. The power converter of claim 1, wherein the switch turn ON times are controlled to coincide with instants at which the voltage across the switch is a minimum.
- 42. The power converter of claim 41, wherein the converter is a flyback converter and the output voltage feedback signal is a reflected flyback voltage signal.
- 43. The power converter of claim 41, wherein the converter is a forward converter and the output voltage feedback signal is a reflected voltage across an auxiliary winding coupled to an output inductor.
- 44. The power converter of claim 41, wherein the converter is a direct-coupled boost converter and the output voltage feedback signal corresponds to a voltage across the switch during its OFF time.
- 45. The power converter of claim 42, wherein switch turn ON times are determined at least in part using a point at which voltage across an auxiliary transformer winding is approximately zero.
- 46. The power converter of claim 42, wherein switch turn ON times are determined at least in part using a point at which voltage across a primary transformer winding is approximately zero.
- 47. The power converter of claim 42, wherein switch turn ON times are determined at least in part using a measured or calculated value of the period of resonant oscillation of the reflected flyback voltage signal.
RELATED APPLICATION DATA
[0001] This application claims priority to provisional application Serial No. 60/335,723, filed Nov. 29, 2001, which is fully incorporated herein by reference.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60335723 |
Nov 2001 |
US |