Method and apparatus for multi-phase power conversion having modified burst current

• US 9,774,189 B2
• Filed: 07/18/2011
• Issued: 09/26/2017
• Est. Priority Date: 07/18/2011
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Fornage, Martin
• Primary Examiner(s): Torres-Rivera, Alex
• Application Number:
  US13/185,422
• Publication Number:
  US 20130021006A1
• Time in Patent Office: 2,262 Days
• Field of Search: 363 71, 363 72, 363 74, 363 95, 363 98, 363131, 363120, 363132, 323906
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/48 Controlling the sharing of the in-phase component
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

A method and apparatus for power conversion. In one embodiment, an apparatus includes a power conversion module for converting a first current to a second current, where the first current or the second current is an AC current having at least two phases. The apparatus also includes a waveform modification module, coupled to the power conversion module, for modifying the AC current to generate a modified AC current, where each phase of the modified AC current has a value of zero at the beginning of an AC line cycle.

Claims

1. A power conversion apparatus, comprising:

a power conversion module converting a DC current to an AC current having multiple phases; and

a waveform modification module, coupled to the power conversion module, modifying, while operating during a burst period of a burst operating mode, the AC current to generate a modified AC current, the modified AC current having a same number of phases as the AC current, wherein all phases of the multiple phases of the modified AC current;

(i) simultaneously have a value of zero at a beginning of an AC line cycle of a particular phase of a multi-phase AC line coupled to the power conversion module, and (ii) are applied concurrently to the multi-phase AC line, and wherein the burst period is immediately preceded by a storage period during which the power conversion module stores received power, while generating no output power, for a predetermined number of AC cycles.

2. The apparatus of claim 1, wherein the waveform modification module multiplies the AC current by a modification waveform to generate the modified AC current.

3. The apparatus of claim 2, wherein the modification waveform is symmetric across at least one AC line cycle.

4. The apparatus of claim 3, wherein the modification waveform increases from zero to a stable value during an attack period, remains at the stable value during a stable period, and decays from the stable value to zero during a decay period.

5. The apparatus of claim 4, wherein the attack period spans a first third of the at least one AC line cycle, the stable period spans a second third of the at least one AC line cycle, and the decay period spans a remaining third of the at least one AC line cycle.

6. The apparatus of claim 1, wherein the modified AC current is synchronized to a master phase and the master phase corresponds to the particular phase.

7. The apparatus of claim 6, wherein the master phase is determined based on a unique identification number corresponding to the power conversion module.

8. The apparatus of claim 1, wherein each phase of the modified AC current has a slope of zero at the beginning of the AC line cycle.

9. A power conversion method, comprising:

converting, by a power conversion module, a DC current to an AC current having multiple phases; and

modifying, while operating during a burst period of a burst operating mode, the AC current to generate a modified AC current, the modified AC current having a same number of phases as the AC current, wherein all phases of the multiple phases of the modified AC current;

(i) simultaneously have a value of zero at a beginning of an AC line cycle of a particular phase of a multi-phase AC line coupled to the power conversion module, and (ii) are applied concurrently to the multi-phase AC line; and

wherein the burst period is immediately preceded by a storage period during which the power conversion module stores received power, while generating no output power, for a predetermined number of AC cycles.

10. The method of claim 9, wherein modifying the AC current comprises multiplying the AC current by a modification waveform.

11. The method of claim 10, wherein the modification waveform is symmetric across at least one AC line cycle.

12. The method of claim 11, wherein the modification waveform increases from zero to a stable value during an attack period, remains at the stable value during a stable period, and decays from the stable value to zero during a decay period.

13. The method of claim 12, wherein the attack period spans a first third of the at least one AC line cycle, the stable period spans a second third of the at least one AC line cycle, and the decay period spans a remaining third of the at least one AC line cycle.

14. The method of claim 9, wherein the particular phase corresponds to a master phase and the modified AC current is synchronized to the master phase.

15. The method of claim 14, further comprising determining the master phase based on a unique identification number corresponding to the power conversion module.

16. The method of claim 9, wherein each phase of the modified AC current has a slope of zero at the beginning of the AC line cycle.

17. A power conversion system, comprising:

a plurality of power conversion modules, wherein each power conversion module of the plurality of power conversion modules converts a DC current to an AC current having multiple phases; and

a plurality of waveform modification modules coupled to the plurality of power conversion modules in a one-to-one correspondence, wherein each waveform modification module modifies, while operating during a burst period of a burst operating mode, the AC current to generate a modified AC current, wherein all phases of the multiple phases of the modified AC current;

(i) simultaneously have a value of zero at a beginning of an AC line cycle of a particular phase of a multi-phase AC line coupled to a corresponding power conversion module, and (ii) are applied concurrently to the multi-phase AC line; and

wherein the burst period is immediately preceded by a storage period during which the corresponding power conversion module stores received power, while generating no output power, for a predetermined number of AC cycles.

18. The system of claim 17, wherein (i) for a first subset of power conversion modules in the plurality of power conversion modules, the modified AC current from each power conversion module of the first subset is synchronized to a first master phase, (ii) for a second subset of power conversion modules in the plurality of power conversion modules, the modified AC current from each power conversion module of the second subset is synchronized to a second master phase, and (iii) for a third subset of power conversion modules in the plurality of power conversion modules, the modified AC current from each power conversion module of the third subset is synchronized to a third master phase.

19. The system of claim 18, wherein assignment of the first, the second, and the third master phase among the plurality of power conversion modules is randomly distributed.

20. The system of claim 18, wherein each waveform modification module multiplies the AC current by a modification waveform to generate the modified AC current.