Power converter with demand pulse isolation

• US RE47,031 E1
• Filed: 04/05/2016
• Issued: 09/04/2018
• Est. Priority Date: 07/03/2012
• Status: Active Grant

• Current Assignee: Visroboro, LLC
• Original Assignee: CogniPower, LLC
• Inventors: Morong, William H., Lawson, Thomas E.
• Primary Examiner(s): Jastrzab, Jeffrey R
• Application Number:
  US15/090,929
• Time in Patent Office: 882 Days
• Field of Search: None
• 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: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

The present invention provides a switched-mode power converter with regulation demand pulses sent across a galvanic isolation barrier.

Claims

1. Apparatus configured to provide switched-mode power conversion, the apparatus comprising:

an input port configured to receive input power;

a switch configured to commutate the input power;

galvanic isolation circuitry configured to provide galvanic isolation between the input port and an output port, wherein the galvanic isolation circuitry comprises a transformer comprising (i) a primary winding arranged in circuit with the input port and the switch and (ii) a secondary winding arranged in circuit with a first rectifier and the output port, wherein the transformer is configured to transfer power from the input port to supply voltage or current to a load connected to the output port;

and

a demand pulse generator galvanically connected to the secondary winding and configured to generate demand pulses applied via the galvanic isolation circuitry to the switch to adjust a frequency of the commutation of the input power to supply a desired amount of voltage or current to the load; and

a capacitor and a second rectifier both galvanically connected to the secondary winding, wherein;

the second rectifier is different from the first rectifier and is poled to charge the capacitor during forward pulses of the apparatus; and

the demand pulse generator is powered by energy stored in the capacitor to generate the demand pulses.

2. The apparatus of claim 1, further comprising:

a source configured to provide a reference signal; and

comparison circuitry configured to compare a feedback signal based on the output port voltage or current to the reference signal wherein frequency of the demand pulses is responsive to the comparison between the feedback signal based on the output port voltage or current and the reference signal.

3. The apparatus of claim 1, further comprising input-side blocking oscillator circuitry configured to drive the switch.

4. The apparatus of claim 3, wherein the demand pulse generator comprises output-side blocking oscillator circuitry configured to generate the demand pulses.

5. The apparatus of claim 1, further comprising wherein the demand pulse generator comprises:

a fastan oscillator configured to initiate the generation of the demandgenerate oscillator pulses; and

logic circuitry configured to provide gating of selectively gate the oscillator pulses to generate the demand pulses applied to the galvanic isolation circuitry.

6. The apparatus of claim 1, wherein the galvanic isolation circuitry further comprises dedicated circuitry configured to convey the demand pulses across the galvanic isolation.

7. The apparatus of claim 1, wherein the demand pulses are conveyed from the demand pulse generator to the switch across the galvanic isolation via the transformer.

8. The apparatus of claim 1, wherein:

the galvanic isolation circuitry divides the apparatus into (i) an input side corresponding to the primary winding of the transformer and (ii) an output side corresponding to the secondary winding of the transformer; and

the demand pulse generator is located on the output side of the apparatus.

9. The apparatus of claim 1, further comprising a capacitor and a diode both galvanically connected to the secondary winding, wherein:

the diode is different from the rectifier and is poled to charge the capacitor during forward pulses of the apparatus; and

the demand pulse generator is powered by energy stored in the capacitor to generate the demand pulses.

36. The apparatus of claim 6, wherein the dedicated circuitry comprises:

an input-side coupled inductor connected in circuit to the switch; and

an output-side coupled inductor connected in circuit to the demand pulse generator.

37. The apparatus of claim 1, wherein, unless gated by an input-side controller, each demand pulse results in the switch being turned on, wherein the input-side controller determines when to turn off the switch.

38. The apparatus of claim 1, wherein the switch is turned on for a duration that is independent of duration of the demand pulses.

39. The apparatus of claim 1, wherein, at power up, an input-side oscillator and input-side logic circuitry are configured to turn on the switch in order to transfer input power via the transformer to energize the capacitor in order to power the demand pulse generator to generate the demand pulses.

40. The apparatus of claim 1, wherein signals generated on an output side of the apparatus do not instruct an input-side controller to turn off the switch.

41. The apparatus of claim 1, wherein an input-side controller avoids premature turnoff of the switch due to capacitive charging of the switch.

42. The apparatus of claim 1, wherein an input-side controller is configured to establish a maximum duration for which the switch is allowed to stay on.

43. The apparatus of claim 1, further comprising the load.

44. The apparatus of claim 1, wherein an input-side controller is configured to determine when to turn off the switch based on current flowing through the switch.

45. The apparatus of claim 1, wherein a leading edge of a single demand pulse will turn on the switch independent of other demand pulses.

46. The apparatus of claim 1, the transformer comprises only one secondary winding.

47. The apparatus of claim 1, further comprising:

a source configured to provide a reference signal; and

comparison circuitry configured to compare a feedback signal based the output port voltage or current to the reference signal wherein frequency of the demand pulses is responsive to the comparison between the feedback signal and the reference signal, wherein;

unless gated by an input-side controller, each demand pulse results in the switch being turned on, wherein the input-side controller determines when to turn off the switch;

the switch is turned on for a duration that is independent of duration of the demand pulses;

signals generated on an output side of the apparatus do not instruct the input-side controller to turn off the switch;

the input-side controller avoids premature turnoff of the switch due to capacitive charging of the switch; and

a leading edge of a single demand pulse will turn on the switch independent of other demand pulses.

48. The method of claim 47, wherein one or more of A, B, C, D, E, and F as follows:

A;

the demand pulse generator comprises;

an oscillator that generates oscillator pulses; and

logic circuitry that selectively gates the oscillator pulses to generate the demand pulses applied to the galvanic isolation circuitry;

B;

the galvanic isolation circuitry comprises dedicated circuitry that conveys the demand pulses, wherein the dedicated circuitry comprises;

an input-side coupled inductor connected in circuit to the switch; and

an output-side coupled inductor connected in circuit to the demand pulse generator;

C;

at power up, an input-side oscillator and input-side logic circuitry are configured to turn on the switch in order to transfer input power via the transformer to energize the capacitor in order to power the demand pulse generator to generate the demand pulses;

D;

the input-side controller is configured to establish a maximum duration for which the switch is allowed to stay on;

E;

the input-side controller is configured to determine when to turn off the switch based on current flowing through the switch; and

F;

the transformer comprises only one secondary winding.

10. Apparatus configured to provide galvanically isolated switched-mode power conversion, the apparatus comprising:

an input port configured to receive input power;

a switch configured to commutate the input power;

a transformer comprising (i) a primary winding arranged in circuit with the input port and the switch and (ii) a secondary winding arranged in circuit with a first rectifier and an output port, wherein the transformer is configured to supply power from the input port to a load connected to the output port; and

a first pulse source circuitry located on an input side of the apparatus and configured to generate pulses to control the switch to start the power conversion;

and

a second pulse source circuitry located on an output side of the apparatus and configured to generate demand pulses to control the switch to continue the power conversion after being started by the first pulse source circuitry; and

a capacitor and a second rectifier both galvanically connected to the secondary winding, wherein;

the second rectifier is different from the first rectifier and is poled to charge the capacitor during forward pulses of the apparatus; and

the second pulse source circuitry is powered by energy stored in the capacitor to generate the demand pulses.

11. The apparatus of claim 10, wherein the frequency of the demand pulses generated by the second pulse source circuitry is different from the frequency of the pulses generated by the first pulse source circuitry.

12. The apparatus of claim 11, wherein the frequency of the demand pulses generated by the second pulse source circuitry is greater than the frequency of the pulses generated by the first pulse source circuitry.

13. The apparatus of claim 10, wherein the frequency of the pulses generated by the first pulse source circuitry is about 1 KHz or smaller.

14. The apparatus of claim 13, wherein the frequency of the demand pulses generated by the second pulse source circuitry is about 60 KHz or greater.

15. The apparatus of claim 10, further comprising a capacitor and a diode both galvanically connected to the secondary winding, wherein:

the diode is different from the rectifier and is poled to charge the capacitor during forward pulses of the apparatus; and

the second pulse source circuitry is powered by energy stored in the capacitor to generate the pulses.

49. The apparatus of claim 10, further comprising:

a source configured to provide a reference signal; and

comparison circuitry configured to compare a feedback signal based the output port voltage or current to the reference signal wherein frequency of the demand pulses is responsive to the comparison between the feedback signal and the reference signal.

50. The apparatus of claim 10, wherein the second pulse source circuitry comprises:

an oscillator configured to generate oscillator pulses; and

logic circuitry configured to selectively gate the oscillator pulses to generate the demand pulses.

51. The apparatus of claim 10, further comprising dedicated circuitry configured to convey the demand pulses from the output side to the input side of the apparatus, wherein the dedicated circuitry comprises:

an input-side coupled inductor connected in circuit to the switch; and

an output-side coupled inductor connected in circuit to the second pulse source circuitry.

52. The apparatus of claim 10, wherein, unless gated by an input-side controller, each demand pulse results in the switch being turned on, wherein the input-side controller determines when to turn off the switch.

53. The apparatus of claim 10, wherein the switch is turned on for a duration that is independent of duration of the demand pulses.

54. The apparatus of claim 10, wherein signals responsive to the demand pulses are applied to the switch to adjust a frequency of switching of input power from the input port to supply a desired amount of voltage or current to the load.

55. The apparatus of claim 10, wherein signals generated by an output-side controller do not instruct an input-side controller to turn off the switch.

56. The apparatus of claim 10, wherein an input-side controller avoids premature turnoff of the switch due to capacitive charging of the switch.

57. The apparatus of claim 10, wherein an input-side controller is configured to establish a maximum duration for which the switch is allowed to stay on.

58. The apparatus of claim 10, further comprising the load.

59. The apparatus of claim 10, wherein an input-side controller is configured to determine when to turn off the switch based on current flowing through the switch.

60. The apparatus of claim 10, wherein a leading edge of a single demand pulse will turn on the switch independent of other demand pulses.

61. The apparatus of claim 10, wherein the transformer comprises only one secondary winding.

62. The apparatus of claim 10, further comprising:

a source configured to provide a reference signal; and

comparison circuitry configured to compare a feedback signal based the output port voltage or current to the reference signal wherein frequency of the demand pulses is responsive to the comparison between the feedback signal and the reference signal, wherein;

unless gated by an input-side controller, each demand pulse results in the switch being turned on, wherein the input-side controller determines when to turn off the switch;

the switch is turned on for a duration that is independent of duration of the demand pulses;

signals responsive to the demand pulses are applied to the switch to adjust a frequency of switching of input power from the input port to supply a desired amount of voltage or current to the load;

signals generated by an output-side controller do not instruct the input-side controller to turn off the switch;

the input-side controller avoids premature turnoff of the switch due to capacitive charging of the switch; and

a leading edge of a single demand pulse will turn on the switch independent of other demand pulses.

63. The apparatus of claim 62, wherein at least one of A, B, C, D, and E as follows:

A;

the second pulse source circuitry comprises;

an oscillator configured to generate oscillator pulses; and

logic circuitry configured to selectively gate the oscillator pulses to generate the demand pulses;

B;

further comprising dedicated circuitry configured to convey the demand pulses from the output side to the input side of the apparatus, wherein the dedicated circuitry comprises;

an input-side coupled inductor connected in circuit to the switch; and

an output-side coupled inductor connected in circuit to the second pulse source circuitry;

C;

the input-side controller is configured to establish a maximum duration for which the switch is allowed to stay on;

D;

the input-side controller is configured to determine when to turn off the switch based on current flowing through the switch; and

E;

the transformer comprises only one secondary winding.

16. In an isolated switched-mode power converter having an input port and an output port, a method of regulation comprising:

(a) comparing a voltage or current at the output port with a reference that is galvanically associated therewith;

(b) generating or gating demand pulses responsive to that comparison;

(c) applying the demand pulses to an output-port side of galvanic isolation circuitry;

(d) receiving replicas of the demand pulses from an input-port side of the galvanic isolation circuitry; and

(e) adjusting commutation frequency of the converter responsive to the demand pulses to cause the voltage or current at the output port to attain a desired value.

17. The method of claim 16, wherein step (b) comprises:

(b1) using a diode to charge a capacitor during forward pulses of the power converter, wherein the diode and the capacitor are galvanically connected within the output-port side of the galvanic isolation circuitry; and

(b2) generating or gating the demand pulses using energy stored in the capacitor.

18. In an isolated switched-mode power converter having an input port and an output port, a method of regulation comprising:

(a) comparing a feedback signal based on a voltage or current at the output port with a reference signal that is galvanically associated therewith;

(b) generating demand pulses responsive to that comparison;

(c) applying the demand pulses to an output-port side of galvanic isolation circuitry;

(d) receiving the demand pulses at an input-port side of the galvanic isolation circuitry; and

(e) controlling the converter responsive to the demand pulses to supply the voltage or current at the output port, wherein step (b) comprises;

(b1) using a rectifier to charge a capacitor during forward pulses of the power converter, wherein the rectifier and the capacitor are connected in circuit with the output-port side of the galvanic isolation circuitry; and

(b2) generating the demand pulses using energy stored in the capacitor.

19. The method of claim 18, wherein:

step (b2) comprises;

(b2i) generating a stream of output-side pulses using an output-side free-running oscillator; and

(b2ii) gating the stream of output-side pulses using output-side logic circuitry to generate the demand pulses;

step (e) comprises;

(e1) generating a stream of input-side pulses using an input-side free-running oscillator; and

(e2) gating the stream of input-side pulses and the demand pulses using input-side logic circuitry to generate control signals for the switch.

20. The method of claim 19, wherein, unless gated by the input-side logic circuitry, each demand pulse results in an input-side commutating switch being turned on, wherein the input-side logic circuitry determines when to turn off the input-side commutating switch.

21. The method of claim 19, wherein an input-side commutating switch is turned on for a duration that is independent of duration of the demand pulses.

22. The method of claim 19, wherein step (b2i) comprises generating the stream of output-side pulses independent of any pulses received from the input side of the power converter.

23. The method of claim 18, wherein a demand pulse generator comprises:

an oscillator that generates oscillator pulses; and

logic circuitry that selectively gates the oscillator pulses to generate the demand pulses applied to the galvanic isolation circuitry.

24. The method of claim 18, wherein the galvanic isolation circuitry comprises dedicated circuitry that conveys the demand pulses, wherein the dedicated circuitry comprises:

an input-side coupled inductor connected in circuit to an input-side commutating switch; and

an output-side coupled inductor connected in circuit to a demand pulse generator.

25. The method of claim 18, wherein signals responsive to the demand pulses are applied to an input-side commutating switch to adjust a frequency of switching of input power from the input port to supply a desired amount of voltage or current to a load connected to the output port.

26. The method of claim 18, wherein, at power up, an input-side oscillator and input-side logic circuitry turn on an input-side commutating switch in order to transfer input power to an output side of the power converter via a power transformer to energize the capacitor in order to power an output-side oscillator and output-side logic circuitry to generate the demand pulses.

27. The method of claim 18, wherein signals generated on an output side of the power converter do not instruct an input-side controller to turn off an input-side commutating switch.

28. The method of claim 18, wherein an input-side controller avoids premature turnoff of an input-side commutating switch due to capacitive charging of the input-side commutating switch.

29. The method of claim 18, wherein an input-side controller establishes a maximum duration for which an input-side commutating switch is allowed to stay on.

30. The method of claim 18, wherein a load is connected to the output port and powered by the power converter.

31. The method of claim 18, wherein an input-side controller determines when to turn off an input-side commutating switch based on current flowing through the input-side commutating switch.

32. The method of claim 18, wherein a leading edge of a single demand pulse will turn on an input-side commutating switch independent of other demand pulses.

33. The method of claim 18, wherein the power converter comprises a power transformer having only one secondary winding.

34. The method of claim 18, wherein:

unless gated by an input-side controller, each demand pulse results in an input-side commutating switch being turned on, wherein the input-side controller determines when to turn off the input-side commutating switch;

the input-side commutating switch is turned on for a duration that is independent of duration of the demand pulses;

signals responsive to the demand pulses are applied to the input-side commutating switch to adjust a frequency of switching of input power from the input port to supply a desired amount of voltage or current to a load connected to the output port;

signals generated on the output side of the power converter do not instruct the input-side controller to turn off the input-side commutating switch;

the input-side controller avoids premature turnoff of the input-side commutating switch due to capacitive charging of the input-side commutating switch; and

a leading edge of a single demand pulse will turn on the input-side commutating switch independent of other demand pulses.

35. The method of claim 34, wherein one or more of A, B, C, D, E, and F as follows:

A;

a demand pulse generator comprises;

an oscillator that generates oscillator pulses; and

logic circuitry that selectively gates the oscillator pulses to generate the demand pulses applied to the galvanic isolation circuitry;

B;

the galvanic isolation circuitry comprises dedicated circuitry that conveys the demand pulses, wherein the dedicated circuitry comprises;

an input-side coupled inductor connected in circuit to the input-side commutating switch; and

an output-side coupled inductor connected in circuit to the demand pulse generator;

C;

at power up, an input-side oscillator and input-side logic circuitry turn on the input-side commutating switch in order to transfer input power to the output side of the power converter via a power transformer to energize the capacitor in order to power the demand pulse generator to generate the demand pulses;

D;

the input-side controller establishes a maximum duration for which the input-side commutating switch is allowed to stay on;

E;

the input-side controller determines when to turn off the input-side commutating switch based on current flowing through the input-side commutating switch; and

F;

the power transformer comprises only one secondary winding.

64. Apparatus configured to provide galvanically isolated switched-mode power conversion, the apparatus comprising:

an input port configured to receive input power;

a switch configured to commutate the input power;

a transformer comprising (i) a primary winding arranged in circuit with the input port and the switch and (ii) a secondary winding arranged in circuit with a rectifier and an output port, wherein the transformer is configured to supply power from the input port to a load connected to the output port;

a first pulse source circuitry located on an input side of the apparatus and configured to generate pulses to control the switch to start the power conversion; and

a second pulse source circuitry located on an output side of the apparatus and configured to generate demand pulses to control the switch to continue the power conversion after being started by the first pulse source circuitry, wherein the frequency of the demand pulses generated by the second pulse source circuitry is greater than the frequency of the pulses generated by the first pulse source circuitry.