Method and apparatus for generating single-phase power from a three-phase resonant power converter

• US 9,444,367 B2
• Filed: 05/25/2012
• Issued: 09/13/2016
• Est. Priority Date: 05/26/2011
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Fornage, Martin, Zimmanck, Donald Richard
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): LABOY ANDINO, IVAN A
• Application Number:
  US13/481,369
• Publication Number:
  US 20120300524A1
• Time in Patent Office: 1,572 Days
• Field of Search: 363/16, 363/17, 363/21.02, 363/21.03, 363/37, 363/123, 363/149, 363/157, 363/159, 363/161, 363163-165, 363/2, 363 8- 10, 363 97- 98, 363131-132
• US Class Current: 1/1
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• 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 5/297 for conversion of frequency
• CPC Class Codes: H02M 7/4807 having a high frequency intermediate AC stage
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A method and apparatus for providing AC power. In one embodiment, the apparatus comprises a cycloconverter controller for determining a DC value based on a reference waveform and a three-phase cycloconverter, coupled to the cycloconverter controller, for selectively coupling, based on the DC value, an alternating current to an AC line to generate a single-phase AC output.

Claims

1. An apparatus for providing AC power, comprising:

a three-phase cycloconverter, located on a secondary side of a transformer, coupled to a plurality of AC phase lines and to a neutral line;

a switch, located on the secondary side of the transformer, coupled across an input of the three-phase cycloconverter, wherein the switch is a fully bi-directional four-quadrant switch; and

a cycloconverter controller, coupled to the three-phase cycloconverter and to the switch for (i) determining a DC value that indicates a value of a reference waveform during a time window, and (ii) controlling, based on the DC value, the three-phase cycloconverter and the switch to selectively couple an alternating current, the alternating current generated by a resonant circuit, to an AC phase line of the plurality of AC phase lines and to the neutral line to generate only a single-phase AC output.

2. The apparatus of claim 1, wherein the reference waveform is synchronous with an AC voltage on the AC phase line.

3. The apparatus of claim 1, wherein the cycloconverter controller dynamically determines the DC value for each time window of a plurality of consecutive time windows.

4. The apparatus of claim 1, wherein the alternating current is selectively coupled to the AC phase line based on a polarity of the DC value.

5. The apparatus of claim 4, wherein selectively coupling the alternating current to the AC phase line comprises coupling, when the DC value is positive, a positive portion of the alternating current to the AC phase line and a negative portion of the alternating current to the neutral line.

6. The apparatus of claim 4, wherein selectively coupling the alternating current to the AC phase line comprises coupling, when the DC value is negative, a negative portion of the alternating current to the AC phase line and a positive portion of the alternating current to the neutral line.

7. A method for providing AC power, comprising:

determining a DC value that indicates a value of a reference waveform during a time window; and

operating, based on the DC value, a three-phase cycloconverter, located on a secondary side of a transformer, and a switch, located on the secondary side of the transformer and coupled across an input of the three-phase cycloconverter, to generate only a single-phase AC output by selectively coupling an alternating current, the alternating current generated by a resonant circuit, to (i) an AC phase line of a plurality of AC phase lines coupled to the three-phase cycloconverter and (ii) to a neutral line coupled to the three-phase cycloconverter, wherein the switch is a bi-directional four-quadrant switch.

8. The method of claim 7, further comprising generating the reference waveform synchronous with an AC voltage on the AC phase line.

9. The method of claim 7, further comprising dynamically determining the DC value for each time window of a plurality of consecutive time windows.

10. The method of claim 7, wherein the alternating current is selectively coupled to the AC phase line based on a polarity of the DC value.

11. The method of claim 10, further comprising coupling, when the DC value is positive, a positive portion of the alternating current to the AC phase line and a negative portion of the alternating current to the neutral line.

12. The method of claim 10, further comprising coupling, when the DC value is negative, a negative portion of the alternating current to the AC phase line and a positive portion of the alternating current to the neutral line.

13. A system for providing AC power, comprising:

a photovoltaic (PV) module; and

a resonant converter, coupled to the PV module and to a plurality of AC phase lines and to a neutral line, comprising;

a three-phase cycloconverter, located on a secondary side of a transformer, coupled to the plurality of AC phase lines and to the neutral line;

a switch, located on the secondary side of the transformer, coupled across an input of the three-phase cycloconverter, wherein the switch is a bi-directional four-quadrant switch; and

a cycloconverter controller, coupled to the three-phase cycloconverter and to the switch, for (i) determining a DC value that indicates a value of a reference waveform during a time window, and (ii) controlling, based on the DC value, the three-phase cycloconverter and the switch to selectively couple an alternating current, the alternating current generated by a resonant circuit, to an AC phase line of the plurality of AC phase lines and to the neutral line to generate only a single-phase AC output.

14. The system of claim 13, further comprising dynamically determining the DC value for each time window of a plurality of consecutive time windows.

15. The system of claim 13, wherein the alternating current is selectively coupled to the AC phase line based on a polarity of the DC value.

16. The system of claim 13, further comprising coupling, when the DC value is positive, a positive portion of the alternating current to the AC phase line and a negative portion of the alternating current to the neutral line.

17. The system of claim 13, further comprising coupling, when the DC value is negative, a negative portion of the alternating current to the AC phase line and a positive portion of the alternating current to the neutral line.