IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0433696
(2000-12-29)
|
우선권정보 |
WO-PCT/GB00/04977(2000-12-22) |
국제출원번호 |
PCT/GB00/005011
(2000-12-29)
|
§371/§102 date |
20031030
(20031030)
|
국제공개번호 |
WO02/052710
(2002-07-04)
|
발명자
/ 주소 |
- Chadwick,David
- Harris,Martyn R.
- Lyons,John A.
- Mortimer,Jeremy
|
출원인 / 주소 |
|
대리인 / 주소 |
Price, Heneveld, Cooper, DeWitt &
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인용정보 |
피인용 횟수 :
4 인용 특허 :
10 |
초록
▼
An apparatus for the improvement of AC waveform comprising means for applying a demand input waveform at an input of a circuit for power conditioning (including an inverter PWMVC or BBHCC) that is operable to provide an output waveform at an output; a feedback loop between the input and output, the
An apparatus for the improvement of AC waveform comprising means for applying a demand input waveform at an input of a circuit for power conditioning (including an inverter PWMVC or BBHCC) that is operable to provide an output waveform at an output; a feedback loop between the input and output, the feedback loop including means for sampling the output waveform (ADC1), means for subtracting a required waveform (RW) from the output waveform to produce an error waveform, means for processing the error waveform in a pre-defined manner to produce a processed error waveform (Clip 1, Disc1, Att 1), means for adding or subtracting the processed error waveform from Th. demand waveform to produce a revised demand waveform, and means for applying the revised demand waveform to the input of the power conditioning circuit at a subsequent time as an input demand waveform to produce a new AC output waveform at the output.
대표청구항
▼
What is claimed is: 1. An apparatus for the improvement of waveform comprising: means for applying a demand input waveform at an input of a circuit for power conditioning that is operable to provide an output waveform at an output, a feedback loop between the input and output, the feedback loop inc
What is claimed is: 1. An apparatus for the improvement of waveform comprising: means for applying a demand input waveform at an input of a circuit for power conditioning that is operable to provide an output waveform at an output, a feedback loop between the input and output, the feedback loop including: means for sampling the output waveform, means for subtracting the sampled output waveform from a pre-determined required waveform to produce an error waveform, means for processing the error waveform in a pre-defined manner to produce a processed error waveform, means for adding or subtracting the processed error waveform from the demand waveform to produce a revised demand waveform, and means for applying the revised demand waveform to the input at a subsequent time as an input demand waveform to produce a new AC output waveform at the output. 2. The apparatus according to claim 1 further comprising: means for summing previous processed error waveforms; means for processing the sum of previous processed error waveforms to produce a processed cumulative sum of processed error waveforms, and means for adding the processed error waveform to the processed cumulative sum of processed error waveforms to produce a new cumulative sum of processed error waveforms, wherein the means for subtracting are operable to subtract the new cumulative sum of processed error waveforms from the required waveform instead of subtracting the processed error waveform from the demand waveform to produce the revised demand waveform. 3. The apparatus according to claim 2 further comprising means for providing a pre-determined degree of time shift, preferably advance, of the new cumulative sum of processed error waveforms relative to the output waveform, wherein the means for subtracting is operable to subtract the time shifted new cumulative sum of processed error waveforms from the required waveform to produce the revised waveform. 4. The apparatus according to claim 1, wherein the means for processing the error waveform comprise means for clipping the error waveform so that sampled magnitudes above a selected threshold are reduced to a pre-determined maximum value. 5. The apparatus according to claim 1, wherein the means for processing the error waveform comprise means for a discarding process in the error waveform so that changes in sampled signal magnitude below a selected threshold do not cause any change in the error waveform. 6. The apparatus according to claim 1, wherein the means for processing the error waveform comprise means for attenuating the error waveform. 7. The apparatus according to claim 2, wherein the means for processing the sum of previous error waveforms comprise means for clipping the sum of previous error waveforms so that magnitudes above a selected threshold are reduced to a pre-determined maximum value. 8. The apparatus according to claim 2, wherein the means for processing the sum of previous error waveforms comprise means for discretising the error waveform so that changes in sampled magnitude below a selected threshold do not cause any change in the sum of previous error waveforms. 9. The apparatus according to claim 2, wherein the means for processing the sum of previous error waveforms comprise means for attenuating the sum of previous error waveforms. 10. The apparatus according to claim 1 further comprising means for modifying a total phase lag from input to output so that it is approximately proportional to the frequency of the signal transmitted round the feedback loop over at least part of a pre-determined frequency spectrum. 11. The apparatus according to claim 10, wherein the pre-determined frequency spectrum extends over a substantial part of a range up to the sample frequency of the means for sampling in the feedback loop. 12. The apparatus according to claim 10, wherein the power conditioning circuit is operable in a switched mode and the pre-determined frequency is a maximum switching frequency of switched-mode operation of the power conditioning circuit. 13. The apparatus according to claim 10, wherein an approximation to proportionality between phase and frequency is represented by a phase deviation that is below plus/minus 90째. 14. The apparatus according to claim 1 further comprising an output filter that is connected to the output line. 15. The apparatus according to claim 14, wherein the output filter is an inductor-capacitor low-pass output filter. 16. The apparatus according to claim 15 further comprising an active damping feedback loop comprising a sensor for sensing current in or voltage across the capacitor, means for multiplying the sensed voltage or current by a coefficient G to provide a damping signal, and means for feeding back the damping signal to an input. 17. The apparatus according to claim 1, wherein the power conditioning circuit is of a voltage-drive form. 18. The apparatus according to claim 1, wherein the power conditioning circuit is of a current-drive form. 19. The apparatus according to claim 1 further comprising n phases with n output lines, the n lines providing n-phase outputs, each of which is separately sampled and processed to determine a revised demand waveform for each line. 20. The apparatus according to claim 19 further comprising a neutral output line that is actively controlled by electronic means. 21. The apparatus according to claim 20, wherein the output signal from the neutral output line is sampled and processed to determine the revised output waveform, the required waveform preferably being set to substantially zero. 22. The apparatus according to claim 1, wherein the means for sampling the output waveform are operable to sample the waveform over one complete AC cycle. 23. The apparatus according to claim 1, wherein more than one AC cycle is sampled and signal processing carried out over that number of cycles. 24. The apparatus according to claim 1, wherein the revised demand waveform is used in the next AC cycle of the output waveform. 25. The apparatus according to claim 1, wherein the revised demand waveform is not used in the next AC cycle but in a cycle after the next AC cycle. 26. The apparatus according to claim 1, wherein a part of one AC cycle is sampled. 27. The apparatus according to claim 1, wherein the means for sampling and processing are operable to operate in a continuous cyclic manner. 28. A method for improving a waveform comprising: applying a demand input waveform at an input of a circuit for power conditioning that is operable to provide an output waveform at an output, sampling the output waveform in a feedback loop between the input and output, subtracting the sampled output waveform from a pre-determined required waveform to produce an error waveform, processing the error waveform in a pre-defined manner to produce a processed error waveform, adding or subtracting the processed error waveform from the demand waveform to produce a revised demand waveform, and applying the revised demand waveform to the input at a subsequent time as an input demand waveform to produce a new AC output waveform at the output. 29. The method according to claim 28 further comprising: summing previous processed error waveforms; processing the sum of previous processed error waveforms to produce a processed cumulative sum of processed error waveforms, and adding the processed error waveform to the processed cumulative sum of processed error waveforms to produce a new cumulative sum of processed error waveforms, wherein the step of subtracting subtracts the new cumulative sum of processed error waveforms from the required waveform instead of subtracting the processed error waveform from the demand waveform to produce the revised demand waveform. 30. The method according to claim 2 further comprising means for providing a pre-determined degree of time shift, preferably advance, of the new cumulative sum of processed error waveforms relative to the output waveform, wherein the means for subtracting is operable to subtract the time shifted new cumulative sum of processed error waveforms from the required waveform to produce the revised waveform. 31. The method according to claim 28, wherein the step of processing the error waveform comprises clipping the error waveform so that sampled magnitudes above a selected threshold are reduced to a pre-determined maximum value. 32. The method according to claim 28, wherein the step of processing the error waveform comprises discretising the error waveform so that changes in sampled magnitude below a selected threshold do not cause any change in the error waveform. 33. The method according to claim 28, wherein the step of processing the error waveform comprises attenuating the error waveform. 34. The method according to claim 29, wherein the step of processing the sum of previous error waveforms comprises clipping the sum of previous error waveforms so that magnitudes above a selected threshold are reduced to a pre-determined maximum value. 35. The method according to claim 29, wherein the means for processing the sum of previous error waveforms comprise means for discretising the error waveform so that changes in sampled magnitude below a selected threshold do not cause any change in the sum of previous error waveforms. 36. The method according to claim 29, wherein the step of processing the sum of previous error waveforms comprises attenuating the sum of previous error waveforms. 37. The method according to claim 28 further comprising ensuring that a total phase lag from input to output so that it is approximately proportional to the frequency of the signal transmitted round the feedback loop over at least part of a pre-determined frequency spectrum. 38. The method according to claim 37, wherein the pre-determined frequency spectrum extends over a substantial part of a range up to the sample frequency of the means for sampling in the feedback loop. 39. The method according to claim 38, wherein the power conditioning circuit is operable in a switched mode and the pre-determined frequency is a maximum switching frequency of switched-mode operation of the power conditioning circuit. 40. The method according to claim 37, wherein an approximation to proportionality between phase and frequency is represented by a phase deviation that is below plus/minus 90째. 41. The method according to claim 28 further comprising sensing current in or voltage across the capacitor or voltage between one end of the capacitor and an effective neutral point, multiplying the sensed voltage or current by a coefficient G to provide a damping signal and feeding back the damping signal to an input. 42. The method according to claim 28, wherein the power conditioning circuit has n phases with n output lines, the n lines providing n-phase output and the method involves separately sampling and processing the signal in each line to produce a revised demand waveform for each line. 43. The method according to claim 28, wherein the step of sampling the output waveform is arranged to sample the waveform over one complete AC cycle. 44. The method according to claim 28, wherein more than one AC cycle is sampled and processing is carried out over that number of cycles. 45. The method according to claim 28, wherein the revised demand waveform is used in the next AC cycle of the output waveform. 46. The method according to claim 28, wherein the revised demand waveform is not used in the next AC cycle but in a later cycle. 47. The method according to claim 28, wherein a part of one AC cycle is sampled. 48. The method according to claim 28, wherein the steps of sampling and processing continuously carried out in a cyclic manner. 49. A micro-turbine-generator comprising: a gas turbine; a permanent-magnet alternator mechanically coupled to the gas turbine, the alternator having an output; and a power conditioning unit electrically coupled to the output of the alternator, the power conditioning unit comprising an apparatus for improving a waveform, said apparatus comprising: means for applying a demand input waveform at an input of the power conditioning unit that is operable to provide an output waveform at an output; and a feedback loop between the input and output, the feedback loop including: means for sampling the output waveform; means for subtracting the sampled output waveform from a predetermined required waveform to produce an error waveform; means for processing the error waveform in a pre-defined manner to produce a processed error waveform; means for adding or subtracting the processed error waveform from the demand waveform to produce a revised demand waveform; and means for applying the revised demand waveform to the input at a subsequent time as an input demand waveform to produce a new AC output waveform at the output. 50. The micro-turbine-generator according to claim 49, wherein the generator is transportable for use at user locations. 51. The micro-turbine-generator according to claim 50, wherein the generator is provided in a single transportable unit. 52. The apparatus according to claim 1, wherein the means for processing the error waveform comprise means for discretising the error waveform so as to make the sampled signal value assume one of a number of preset values. 53. The apparatus according to claim 10, wherein an approximation to proportionality between phase and frequency is represented by a phase deviation that is below plus/minus 60째. 54. The apparatus according to claim 10, wherein an approximation to proportionality between phase and frequency is represented by a phase deviation that is significantly below plus/minus 60째. 55. The apparatus according to claim 26, wherein half of one AC cycle is sampled. 56. The method according to claim 37, wherein an approximation to proportionality between phase and frequency is represented by a phase deviation that is below plus/minus 60째. 57. The method according to claim 37, wherein an approximation to proportionality between phase and frequency is represented by a phase deviation that is significantly below plus/minus 60째. 58. The method according to claim 47, wherein half of one AC cycle is sampled.
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