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. 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;   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 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. 
   
     
     
       19. The apparatus of claim 18, wherein:
 the demand pulses instruct input-side circuitry of the apparatus to turn on the switch;   the input-side circuitry is configured to determine when to turn off the switch independent 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 lower in magnitude than a reference signal;   the apparatus is configured to regulate the output port by driving the feedback signal to match the reference signal;   feedback from an output side of the apparatus to an input side of the apparatus for regulating the output port voltage or current is provided solely by the demand pulses generated by the demand pulse generator;   each demand pulse conveyed from the output side of the apparatus to the input side of the apparatus has a leading edge;   when a particular demand pulse results in a particular occurrence of the switch turning on, the particular occurrence of the switch turning on is in response to detecting the leading edge of the particular demand pulse independent of any other demand pulses conveyed from the output side to the input side and independent of any other pulse edges appearing on the input side; and   the demand pulse generator is configured to generate a demand pulse whenever a magnitude of the output port voltage or current is below a magnitude of the output port's regulation voltage or current.   
     
     
       20. The apparatus of claim 18, wherein the demand pulse generator comprises:
 an oscillator configured to generate oscillator pulses; and   logic circuitry configured to selectively block certain oscillator pulses in generating the demand pulses.   
     
     
       21. The apparatus of claim 20, wherein the logic circuitry is configured to selectively block the certain oscillator pulses from becoming demand pulses that would otherwise result in the switch being turned on, while selectively allowing other oscillator pulses to become the demand pulses that do result in the switch being turned on. 
     
     
       22. The apparatus of claim 18, wherein the demand pulse generator is configured to process, based on a comparator output, an output-side stream of oscillator pulses to generate the demand pulses. 
     
     
       23. The apparatus of claim 18, wherein the demand pulse generator comprises:
 a comparator configured to generate a comparator output based on a comparison between (i) a feedback signal based on the output port voltage or current and (ii) a 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.   
     
     
       24. The apparatus of claim 18, wherein, when the output port is in regulation, the determination of when to turn off the switch is always originated on an input side of the apparatus and never on an output side of the apparatus. 
     
     
       25. The apparatus of claim 18, wherein the galvanic isolation circuitry further comprises a pulse transformer, separate from the transformer, configured to transmit the demand pulses from an output side of the apparatus to an input side of the apparatus. 
     
     
       26. The apparatus of claim 18, wherein the apparatus comprises the load. 
     
     
       27. 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 single 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;   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; and   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. 
   
     
     
       28. The apparatus of claim 27, wherein:
 the pulses generated by the second pulse source circuitry are demand pulses;   the demand pulses instruct input-side circuitry of the apparatus to turn on the switch;   the input-side circuitry is configured to determine when to turn off the switch independent of the demand pulses;   the second pulse source circuitry is configured to generate the demand pulses when a feedback signal based on the output port voltage or current is lower in magnitude than a reference signal;   the apparatus is configured to regulate the output port by driving the feedback signal to match the reference signal;   feedback from the output side of the apparatus to the input side of the apparatus for regulating the output port voltage or current is provided solely by the demand pulses generated by the second pulse source circuitry;   each demand pulse conveyed from the output side of the apparatus to the input side of the apparatus has a leading edge;   when a particular demand pulse results in a particular occurrence of the switch turning on, the particular occurrence of the switch turning on is in response to detecting the leading edge of the particular demand pulse independent of any other demand pulses conveyed from the output side to the input side and independent of any other pulse edges appearing on the input side; and   the second pulse source circuitry is configured to generate a demand pulse whenever a magnitude of the output port voltage or current is below a magnitude of the output port's regulation voltage or current.   
     
     
       29. The apparatus of claim 27, wherein the second pulse source circuitry comprises:
 an oscillator that generates oscillator pulses; and   logic circuitry that selectively blocks certain oscillator pulses in generating the pulses conveyed from the output side of the apparatus to the input side of the apparatus.   
     
     
       30. The apparatus of claim 29, wherein the logic circuitry is configured to selectively block the certain oscillator pulses from becoming pulses that would otherwise result in the switch being turned on, while selectively allowing other oscillator pulses to become the pulses that do result in the switch being turned on. 
     
     
       31. The apparatus of claim 27, wherein the second pulse source circuitry is configured to process, based on a comparator output, an output-side stream of oscillator pulses to generate the pulses conveyed from the output side of the apparatus to the input side of the apparatus. 
     
     
       32. The apparatus of claim 27, wherein the second pulse source circuitry comprises:
 a comparator configured to generate a comparator output based on a comparison between (i) a feedback signal based on the output port voltage or current and (ii) a 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 pulses conveyed from the output side of the apparatus to the input side of the apparatus.   
     
     
       33. The apparatus of claim 27, wherein, when the output port is in regulation, the determination of when to turn off the switch is always originated on the input side of the apparatus and never on the output side of the apparatus. 
     
     
       34. The apparatus of claim 27, wherein the apparatus further comprises a pulse transformer, separate from the transformer, configured to transmit the pulses generated by the second pulse source circuitry from the output side of the apparatus to the input side of the apparatus. 
     
     
       35. The apparatus of claim 27, wherein the apparatus comprises the load. 
     
     
       36. 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, 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. 
   
     
     
       37. The method of claim 36, wherein:
 the demand pulses instruct input-side circuitry of the power converter to turn on a switch on the input-port side;   the input-side circuitry determines when to turn off the switch independent of the demand pulses;   the demand pulses are generated when a feedback signal based on the output port voltage or current is lower in magnitude than a reference signal;   the output port is regulated by driving the feedback to match the reference signal;   feedback from the output-port side to the input-port side for regulating the output port voltage or current is provided solely by the demand pulses;   each demand pulse conveyed from the output-port side to the input-port side has a leading edge;   when a particular demand pulse results in a particular occurrence of the switch turning on, the particular occurrence of the switch turning on is in response to detecting the leading edge of the particular demand pulse independent of any other demand pulses conveyed from the output-port side to the input-port side and independent of any other pulse edges appearing on the input-port side; and   step (b) comprises generating a demand pulse whenever a magnitude of the output port voltage or current is below a magnitude of the output port's regulation voltage or current.   
     
     
       38. The method of claim 36, wherein step (b) comprises:
 (b1) generating oscillator pulses; and   (b2) selectively blocking certain oscillator pulses in generating the demand pulses.   
     
     
       39. The method of claim 38, wherein step (b2) comprises selectively blocking the certain oscillator pulses from becoming demand pulses that would otherwise result in the switch being turned on, while selectively allowing other oscillator pulses to become the demand pulses that do result in the switch being turned on. 
     
     
       40. The method of claim 36, wherein step (b) comprises processing, based on the comparison of step (a), an output-side stream of oscillator pulses to generate the demand pulses. 
     
     
       41. The method of claim 36, wherein step (b) comprises:
 (b1) generating a stream of oscillator pulses independent of the comparison of step (a); and   (b2) processing, based on the comparison of step (a), the stream of oscillator pulses to generate the demand pulses.   
     
     
       42. The method of claim 36, wherein, when the output port is in regulation, the determination of when to turn off the switch is always originated on the input-port side and never on the output-port side. 
     
     
       43. The method of claim 36, wherein the galvanic isolation circuitry comprises:
 a power transformer that transmits power from the input port to the output port; and   a pulse transformer, separate from the power transformer, that transmits the demand pulses from the output-port side to the input-port side.