THREE PORT CONVERTER WITH DUAL INDEPENDENT MAXIMUM POWER POINT TRACKING AND DUAL OPERATING MODES

• US 20140183953A1
• Filed: 12/24/2013
• Published: 07/03/2014
• Est. Priority Date: 12/30/2012
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Harrison, Michael J.
• Granted Patent: US 9,866,144 B2
• Time in Patent Office: Days
• US Class Current: 307/52
• 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 5/00 Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• 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 a three port converter with independent dual input comprising: a first DC port for coupling a first half-bridge circuit of the three-port converter to a first external DC line, a second DC port for coupling a second half-bridge circuit of the three-port converter to a second external DC line, wherein the second half-bridge circuit is decoupled from the first half-bridge circuit, and an AC port for coupling to an external AC line, wherein (i) the first half-bridge circuit and the second half-bridge circuit are operated as a full H-bridge during a full-bridge operating mode, and (ii) the first half-bridge circuit or the second half-bridge circuit is operated as a half H-bridge during a half-bridge operating mode.

Claims

1. Apparatus for power conversion, comprising:

a three-port converter comprising;

a first DC port for coupling a first half-bridge circuit of the three-port converter to a first external DC line;

a second DC port for coupling a second half-bridge circuit of the three-port converter to a second external DC line, wherein the second half-bridge circuit is decoupled from the first half-bridge circuit; and

an AC port for coupling to an external AC line, wherein (i) the first half-bridge circuit and the second half-bridge circuit are operated as a full H-bridge during a full-bridge operating mode, and (ii) the first half-bridge circuit or the second half-bridge circuit is operated as a half H-bridge during a half-bridge operating mode.

2. The apparatus of claim 1, wherein the three-port converter operates in the full-bridge operating mode when an AC line voltage on the external AC line is proximate peak values, and wherein the three-port converter operates in the half-bridge operating mode when the AC line voltage is proximate zero-crossings.

3. The apparatus of claim 2, wherein the first half-bridge circuit and the second half-bridge circuit are alternately utilized each time the half-bridge operating mode is employed.

4. The apparatus of claim 1, wherein the three-port converter is a DC-AC converter and converts DC power received via the first and the second DC ports to AC output power.

5. The apparatus of claim 4, wherein the three-port converter adjusts an operating voltage for each of a first DC source coupled to the first DC port and a second DC source coupled to the second DC port to drive the first DC source and the second DC source toward their respective maximum power points (MPPs), wherein the operating voltages for each of the first DC source and the second DC source are independent of one another.

6. The apparatus of claim 4, wherein, for half-bridge operating mode, an amount of time for operating the first half-bridge circuit versus the second half-bridge circuit is apportioned based on an amount of power to be drawn from each of the first and the second DC sources.

7. The apparatus of claim 4, wherein, for full-bridge operating mode, duty cycles for diagonal switch pairs are apportioned based on an amount of power to be drawn from each of the first and the second DC sources.

8. The apparatus of claim 1, wherein the three-port converter is an AC-DC converter and converts AC power received at the AC port to DC output at at least one of the first DC port or the second DC port.

9. A method for operating a three-port converter, comprising:

operating, during a first plurality of time periods, the three-port converter in a full-bridge operating mode, wherein first and second half-bridge circuits of the three-port converter are operated as a full H-bridge during the full-bridge operating mode; and

operating, during a second plurality of time periods interleaved with the first plurality of time periods, the three-port converter in a half-bridge operating mode, wherein the first half-bridge circuit or the second half-bridge circuit is operated as a half H-bridge during the half-bridge operating mode, wherein (i) the three-port converter comprises a first DC port for coupling the first half-bridge circuit to a first external DC line, a second DC port for coupling the second half-bridge circuit to a second external DC line, and an AC port for coupling to an external AC line, and (ii) the second half-bridge circuit is decoupled from the first half-bridge circuit.

10. The method of claim 9, wherein the first plurality of time periods occur when an AC line voltage on the external AC line is proximate peak values, and wherein the second plurality of time periods occur when the AC line voltage is proximate zero-crossings.

11. The method of claim 10, wherein the first half-bridge circuit and the second half-bridge circuit are alternately utilized during each time period of the second plurality of time periods.

12. The method of claim 9, wherein the three-port converter is a DC-AC converter and converts DC power received via the first and the second DC ports to AC output power.

13. The method of claim 12, further comprising adjusting an operating voltage, for each of a first DC source coupled to the first DC port and a second DC source coupled to the second DC port, to drive the first DC source and the second DC source toward their respective maximum power points (MPPs), wherein the operating voltages for each of the first DC source and the second DC source are independent of one another.

14. The method of claim 12, further comprising apportioning, based on an amount of power to be drawn from each of the first and the second DC sources, an amount of time for operating the first half-bridge circuit versus the second half-bridge circuit during the half-bridge operating mode.

15. The method of claim 9, wherein operation of the first half-bridge circuit and the second half-bridge circuit independently control the power input and output by the first DC port, the second DC port, and the AC port.

16. The method of claim 12, further comprising apportioning, based on an amount of power to be drawn from each of the first and the second DC sources, duty cycles for diagonal switch pairs that are switched during the full-bridge operating mode.

17. The method of claim 9, wherein the three-port converter is an AC-DC converter and converts AC power received at the AC port to DC output at at least one of the first DC port or the second DC port.

18. A system for power conversion, comprising:

a first photovoltaic (PV) module;

a second PV module;

a three-port converter comprising;

a first DC port for coupling a first half-bridge circuit of the three-port converter to the first PV module;

a second DC port for coupling a second half-bridge circuit of the three-port converter to the second PV module, wherein the second half-bridge circuit is decoupled from the first half-bridge circuit; and

an AC port for coupling to an external AC line, wherein (i) the first half-bridge circuit and the second half-bridge circuit are operated as a full H-bridge during a full-bridge operating mode, and (ii) the first half-bridge circuit or the second half-bridge circuit is operated as a half H-bridge during a half-bridge operating mode.

19. The system of claim 18, wherein the three-port converter operates in the full-bridge operating mode when an AC line voltage on the external AC line is proximate peak values, and wherein the three-port converter operates in the half-bridge operating mode when the AC line voltage is proximate zero-crossings.

20. The system of claim 19, wherein the first half-bridge circuit and the second half-bridge circuit are alternately utilized each time the half-bridge operating mode is employed.