Power converter with demand pulse isolation

Abstract

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

What is claimed is: 
     
       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 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.   
     
     
       2. The apparatus of  claim 1 , further comprising:
 a source configured to provide a reference signal; and   comparison circuitry configured to compare the output port voltage or current to the reference signal wherein frequency of the demand pulses is responsive to the comparison between 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:
 a fast oscillator configured to initiate the generation of the demand pulses; and   logic circuitry configured to provide gating of 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 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.   
     
     
       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 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 pulses to control the switch to continue the power conversion after being started by the first pulse source circuitry.   
     
     
       11. The apparatus of  claim 10 , wherein the frequency of pulses generated by the second pulse source circuitry is different from the frequency of pulses generated by the first pulse source circuitry. 
     
     
       12. The apparatus of  claim 11 , wherein the frequency of pulses generated by the second pulse source circuitry is greater than the frequency of pulses generated by the first pulse source circuitry. 
     
     
       13. The apparatus of  claim 10 , wherein the frequency of pulses generated by the first pulse source circuitry is about 1 KHz or smaller. 
     
     
       14. The apparatus of  claim 13 , wherein the frequency of 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.   
     
     
       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. Circuitry for controlling a flyback converter, the flyback converter comprising:
 an input port;   an output port galvanically isolated from the input port such that:
 the input port is on a converter primary side of the flyback converter; and 
 the output port is on a converter secondary side of the flyback converter; and 
   a power transformer configured to transfer input power received at the input port to provide output power at the output port, wherein:
 the converter primary side further comprises a primary-side switch configured to selectively transfer the input power at the input port via the power transformer to the output power at the output port; 
 the circuitry comprises first circuitry and second circuitry, wherein, when the circuitry is connected to control the flyback converter, (i) the first circuitry is on the converter primary side and (ii) the second circuitry is on the converter secondary side; 
 the second circuitry (i) determines when to turn on the primary-side switch based on output port voltage or current at the output port and (ii) generates corresponding demand pulses; 
 the converter secondary side is configured to transmit the demand pulses to the converter primary side; 
 the first circuitry is configured to turn on the primary-side switch in response to the demand pulses conveyed from the converter secondary side to the converter primary side, wherein the first circuitry, and not the second circuitry, originates the determination of when to turn off the primary-side switch; 
 frequency with which the primary-side switch is turned on is the frequency of the demand pulses conveyed from the converter secondary side to the converter primary side to regulate the output port voltage or current; 
 the first circuitry is configured to determine when to turn off the switch independent of the duration of the demand pulses; 
 the second circuitry is configured to generate the demand pulses when a feedback signal based on the output port voltage or current is smaller in magnitude than a reference signal; and 
 the circuitry is configured to regulate the output port by driving the feedback signal to match the reference signal. 
   
     
     
       19. The circuitry of claim 18, wherein the second circuitry is powered by energy transferred from the primary side to the secondary side during both forward and flyback pulses of the flyback converter. 
     
     
       20. The circuitry of claim 18, wherein:
 the converter primary side further comprises a primary-side magnetically coupled conductor;   the converter secondary side further comprises a secondary-side magnetically coupled conductor configured to be magnetically coupled to the primary-side magnetically coupled conductor to convey the demand pulses from the converter secondary side to the converter primary side;   the power transformer has a primary-side winding and a secondary-side winding;   the primary-side switch is connected in series with the primary-side winding of the power transformer;   the secondary-side winding of the power transformer is connected to the output port;   the primary-side magnetically coupled conductor is different from the primary-side winding of the power transformer; and   the secondary-side magnetically coupled conductor is different from the secondary-side winding of the power transformer.   
     
     
       21. The circuitry of claim 19, wherein the primary-side and secondary-side magnetically coupled conductors are part of a pulse transformer separate from the power transformer. 
     
     
       22. Circuitry for controlling a flyback converter, the flyback converter comprising:
 an input port;   an output port galvanically isolated from the input port such that:
 the input port is on a converter primary side; and 
 the output port is on a converter secondary side; and 
   a power transformer configured to transfer input power received at the input port to provide output power at the output port, wherein:
 the converter primary side further comprises a primary-side switch configured to selectively transfer the input power at the input port via the power transformer to the output power at the output port; 
 the circuitry comprises first circuitry and second circuitry, wherein, when the circuitry is connected to control the flyback converter, (i) the first circuitry is on the converter primary side and (ii) the second circuitry is on the converter secondary side; 
 when the output port is in regulation, the second circuitry (i) determines when to turn on the primary-side switch based on output port voltage or current at the output port and (ii) generates corresponding demand pulses; 
 the converter secondary side is configured to transmit the demand pulses to the converter primary side; 
 the first circuitry is configured to turn on the primary-side switch in response to the demand pulses conveyed from the converter secondary side to the converter primary side, wherein, when the output port is in regulation, the first circuitry, and not the second circuitry, originates the determination of when to turn off the primary-side switch; 
 frequency with which the primary-side switch is turned on is the frequency of the demand pulses conveyed from the converter secondary side to the converter primary side to regulate the output port voltage or current; 
 the first circuitry is configured to determine when to turn off the switch independent of the duration of the demand pulses; 
 the second circuitry is configured to generate the demand pulses when a feedback signal based on the output port voltage or current is smaller in magnitude than a reference signal; 
 the circuitry is configured to regulate the output port by driving the feedback signal to match the reference signal; 
 when the output port is in regulation, the determination of when to turn off the primary-side switch is always originated on the converter primary side and never on the converter secondary side; 
 feedback from the converter secondary side to the converter primary side for regulating the output port voltage or current is provided solely by the demand pulses generated by the second circuitry; and 
 the second circuitry is configured to generate one or more demand pulses whenever a magnitude of the output port voltage or current is below a magnitude of the output port's regulation voltage or current. 
   
     
     
       23. The circuitry of claim 22, wherein the second circuitry is powered by energy transferred from the primary side to the secondary side during both forward and flyback pulses of the flyback converter. 
     
     
       24. The circuitry of claim 22, wherein the second circuitry comprises:
 an oscillator configured to generate oscillator pulses; and   logic circuitry configured to selectively block certain oscillator pulses in generating the demand pulses.   
     
     
       25. The circuitry of claim 23, wherein the logic circuitry is configured to selectively block the certain oscillator pulses from becoming demand pulses that would otherwise result in the primary-side switch being turned on, while selectively allowing other oscillator pulses to become the demand pulses that do result in the primary-side switch being turned on. 
     
     
       26. The circuitry of claim 23, wherein the second circuitry is configured to process, based on a comparator output, an output-side stream of oscillator pulses to generate the demand pulses. 
     
     
       27. The circuitry of claim 22, wherein the second circuitry comprises:
 a comparator configured to generate a comparator output based on a comparison between the feedback signal and the reference signal;   an oscillator configured to generate a stream of oscillator pulses independent of the comparator output; and   logic circuitry configured to (i) receive the comparator output and the stream of oscillator pulses and (ii) process, based on the comparator output, the stream of oscillator pulses to generate the demand pulses.   
     
     
       28. The circuitry of claim 22, wherein:
 the converter primary side further comprises a primary-side magnetically coupled conductor;   the converter secondary side further comprises a secondary-side magnetically coupled conductor configured to be magnetically coupled to the primary-side magnetically coupled conductor to convey the demand pulses from the converter secondary side to the converter primary side;   the power transformer has a primary-side winding and a secondary-side winding;   the primary-side switch is connected in series with the primary-side winding of the power transformer;   the secondary-side winding of the power transformer is connected to the output port;   the primary-side magnetically coupled conductor is different from the primary-side winding of the power transformer; and   the secondary-side magnetically coupled conductor is different from the secondary-side winding of the power transformer.   
     
     
       29. The circuitry of claim 28, wherein the primary-side and secondary-side magnetically coupled conductors are part of a pulse transformer separate from the power transformer. 
     
     
       30. An article of manufacture comprising a flyback converter, the flyback converter comprising:
 an input port;   an output port galvanically isolated from the input port such that:
 the input port is on a primary side of the flyback converter; and 
 the output port is on a secondary side of the flyback converter; and 
   a power transformer configured to transfer input power received at the input port to provide output power at the output port, wherein:
 the primary side further comprises a primary-side switch configured to selectively enable the input power at the input port to be transferred via the power transformer to the output power at the output port; 
 the secondary side further comprises a demand pulse generator that (i) determines when to turn on the primary-side switch based on output voltage or output current at the output port and (ii) generates corresponding demand pulses; 
 the primary side comprises a primary-side magnetically coupled conductor; 
 the secondary side comprises a secondary-side magnetically coupled conductor configured to be magnetically coupled to the primary-side magnetically coupled conductor to convey the demand pulses from the secondary side to the primary side; 
 the primary-side switch is turned on in response to the demand pulses conveyed from the secondary side to the primary side, wherein the determination of when to turn off the primary-side switch is originated on the primary side and not on the secondary side; 
 frequency with which the primary-side switch is turned on is the frequency of the demand pulses conveyed from the secondary side to the primary side to regulate the output voltage or the output current at the output port; 
 the primary side is configured to determine when to turn off the switch independent of the duration of the demand pulses; 
 the demand pulse generator is configured to generate the demand pulses when a feedback signal based on the output port voltage or current is smaller in magnitude than a reference signal; and 
 the flyback converter is configured to regulate the output port by driving the feedback signal to match the reference signal. 
   
     
     
       31. The article of claim 30, wherein the demand pulse generator is powered by energy transferred from the primary side to the secondary side during both forward and flyback pulses of the flyback converter. 
     
     
       32. The article of claim 30, wherein:
 the power transformer has a primary-side winding and a secondary-side winding;   the primary-side switch is connected in series with the primary-side winding of the power transformer;   the secondary-side winding of the power transformer is connected to the output port;   the primary-side magnetically coupled conductor is different from the primary-side winding of the power transformer; and   the secondary-side magnetically coupled conductor is different from the secondary-side winding of the power transformer.   
     
     
       33. The article of claim 32, wherein the primary-side and secondary-side magnetically coupled conductors are part of a pulse transformer separate from the power transformer. 
     
     
       34. The article of claim 30, wherein the article comprises a load connected to the output port of the flyback converter and configured to be powered by the flyback converter. 
     
     
       35. An article of manufacture comprising a flyback converter, the flyback converter comprising:
 an input port;   an output port galvanically isolated from the input port such that:
 the input port is on a primary side of the flyback converter; and 
 the output port is on a secondary side of the flyback converter; and 
   a power transformer configured to transfer input power received at the input port to provide output power at the output port, wherein:
 the primary side further comprises a primary-side switch configured to selectively enable the input power at the input port to be transferred via the power transformer to the output power at the output port; 
 the secondary side further comprises a demand pulse generator that, when the output port is in regulation, (i) determines when to turn on the primary-side switch based on output voltage or output current at the output port and (ii) generates corresponding demand pulses; 
 the primary side comprises a primary-side magnetically coupled conductor; 
 the secondary side comprises a secondary-side magnetically coupled conductor configured to be magnetically coupled to the primary-side magnetically coupled conductor to convey the demand pulses from the secondary side to the primary side; 
 the primary-side switch is turned on in response to the demand pulses conveyed from the secondary side to the primary side, wherein, when the output port is in regulation, the determination of when to turn off the primary-side switch is originated on the primary side and not on the secondary side; 
 frequency with which the primary-side switch is turned on is the frequency of the demand pulses conveyed from the secondary side to the primary side to regulate the output voltage or the output current at the output port; 
 the primary side is configured to determine when to turn off the switch independent of the duration of the demand pulses; 
 the demand pulse generator is configured to generate the demand pulses when a feedback signal based on the output port voltage or current is smaller in magnitude than a reference signal; 
 the flyback converter is configured to regulate the output port by driving the feedback signal to match the reference signal; 
 when the output port is in regulation, the determination of when to turn off the primary-side switch is always originated on the primary side and never on the secondary side; 
 feedback from the secondary side to the primary side for regulating the output port voltage or current is provided solely by the demand pulses generated by the demand pulse generator; and 
 the demand pulse generator is configured to generate one or more demand pulses whenever a magnitude of the output port voltage or current is below a magnitude of the output port's regulation voltage or current. 
   
     
     
       36. The article of claim 35, wherein the demand pulse generator is powered by energy transferred from the primary side to the secondary side during both forward and flyback pulses of the flyback converter. 
     
     
       37. The article of claim 35, wherein the demand pulse generator comprises:
 an oscillator that generates oscillator pulses; and   logic circuitry that selectively blocks certain oscillator pulses in generating the demand pulses.   
     
     
       38. The article of claim 37, wherein the logic circuitry is configured to selectively block the certain oscillator pulses from becoming demand pulses that would otherwise result in the primary-side switch being turned on, while selectively allowing other oscillator pulses to become the demand pulses that do result in the primary-side switch being turned on. 
     
     
       39. The article of claim 35, wherein the demand pulse generator is configured to process, based on a comparator output, a secondary-side stream of oscillator pulses to generate the demand pulses. 
     
     
       40. The article of claim 35, wherein the demand pulse generator comprises:
 a comparator configured to generate a comparator output based on a comparison between the feedback signal and the reference signal;   an oscillator configured to generate a stream of oscillator pulses independent of the comparator output; and   logic circuitry configured to (i) receive the comparator output and the stream of oscillator pulses and (ii) process, based on the comparator output, the stream of oscillator pulses to generate the demand pulses.   
     
     
       41. The article of claim 35, wherein:
 the power transformer has a primary-side winding and a secondary-side winding;   the primary-side switch is connected in series with the primary-side winding of the power transformer;   the secondary-side winding of the power transformer is connected to the output port;   the primary-side magnetically coupled conductor is different from the primary-side winding of the power transformer; and   the secondary-side magnetically coupled conductor is different from the secondary-side winding of the power transformer.   
     
     
       42. The article of claim 41, wherein the primary-side and secondary-side magnetically coupled conductors are part of a pulse transformer separate from the power transformer. 
     
     
       43. The article of claim 35, wherein the article comprises a load connected to the output port of the flyback converter and configured to be powered by the flyback converter.