METHODS AND SYSTEMS FOR OPERATING A BI-DIRECTIONAL MICRO INVERTER

• US 20140211529A1
• Filed: 01/28/2013
• Published: 07/31/2014
• Est. Priority Date: 01/28/2013
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Keeramthode, Remesh Kumar, Srighakollapu, NVS Kumar, Kandasamy, Jeyaprakash
• Application Number:
  US13/751,704
• Publication Number:
  US 20140211529A1
• Time in Patent Office: Days
• US Class Current: 363/131
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• 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 3/1835 with stepless control
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02M 7/4807 having a high frequency intermediate AC stage
• CPC Class Codes: H02M 7/797 using semiconductor devices only
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 40/30 Reactive power compensation

Abstract

A micro inverter includes a synchronous bi-directional power converter and a controller communicatively coupled to the synchronous bi-directional power converter. The controller is configured to operate the micro inverter in a forward conduction mode when photovoltaic (PV) power is available and operate the micro inverter in at least one of a reverse conduction mode and a reactive power compensation mode when PV power is unavailable.

Claims

1. A micro inverter comprising:

a synchronous bi-directional power converter; and

a controller coupled to said synchronous bi-directional power converter, said controller configured to;

operate said micro inverter in a forward conduction mode when photovoltaic (PV) power is available; and

operate said micro inverter in at least one of a reverse conduction mode and a reactive power compensation mode when PV power is unavailable.

2. A micro inverter in accordance with claim 1, wherein said synchronous bi-directional power converter is configured to:

convert DC power to alternating current (AC) during the forward conduction mode; and

convert AC power to DC power during the reverse conduction mode.

3. A micro inverter in accordance with claim 2, wherein the DC power is applied to at least one of a reactive power compensator and a battery during the reverse conduction mode.

4. A micro inverter in accordance with claim 1, wherein said synchronous bi-directional power converter comprises:

a synchronous bi-directional DC to DC converter configured to receive power; and

a synchronous bi-directional DC to AC inverter coupled downstream from said bi-directional DC to DC converter.

5. A micro inverter in accordance with claim 4, wherein said controller is configured to generate pulse width modulation signals to control operation of said synchronous bi-directional DC to DC converter and said synchronous bi-directional DC to AC inverter.

6. A micro inverter in accordance with claim 4, wherein said synchronous bi-directional DC to DC converter comprises a DC to DC boost converter.

7. A micro inverter in accordance with claim 6, wherein said DC to DC boost converter is configured to output a ripple current to said synchronous bi-directional DC to AC inverter.

8. A micro inverter in accordance with claim 6, wherein said synchronous bi-directional DC to DC converter comprises:

a boost inductor;

a main boost switch coupled to said boost inductor; and

a synchronous boost switch coupled to said boost inductor.

9. A micro inverter in accordance with claim 8 wherein said main boost switch and said synchronous boost switch each comprise one of a metal-oxide-semiconductor field-effect transistor and an insulated-gate bipolar transistor.

10. A micro inverter in accordance with claim 4, wherein said synchronous bi-directional DC to AC inverter comprises a DC to AC flyback inverter.

11. A micro inverter in accordance with claim 10, wherein said synchronous bi-directional DC to AC inverter comprises:

a transformer having a primary winding and first and second secondary windings;

a primary flyback switch coupled to said primary winding;

a first secondary flyback switch coupled to said first secondary winding;

a first synchronous flyback switch coupled to said second secondary winding;

a second secondary flyback switch coupled downstream from said first synchronous flyback switch; and

a second synchronous flyback switch coupled downstream from said first secondary flyback switch.

12. A method of operating a micro inverter having a synchronous bi-directional power converter coupled to a direct current (DC) power source and to an electrical grid, said method comprising:

synchronously operating, using a controller, the micro inverter in a forward conduction mode when photovoltaic (PV) power is available from the DC power source; and

synchronously operating, using the controller, the micro inverter in at least one of a reverse conduction mode and a reactive power compensation mode when PV power is unavailable.

13. A method in accordance with claim 12, further comprising providing single phase AC power to the electrical grid.

14. A method in accordance with claim 12, further comprising providing reactive power compensation to the micro inverter during the reverse conduction mode.

15. A method in accordance with claim 12, further comprising charging a battery coupled to the micro inverter to the micro inverter during the reverse conduction mode.

16. A method in accordance with claim 12, further comprising:

converting DC power received from the DC power source to alternating current (AC) for delivery to the electrical grid during the forward conduction mode; and

converting AC power received from the electrical grid to DC power during the reverse conduction mode.

17. A controller for use in controlling a micro inverter, said controller configured to:

operate the micro inverter in a forward conduction mode when photovoltaic (PV) power is available; and

operate the micro inverter in at least one of a reverse conduction mode and a reactive power compensation mode when PV power is unavailable.

18. A controller in accordance with claim 17, further configured to:

convert DC power received from a DC power source to alternating current (AC) for delivery to an electrical grid during the forward conduction mode; and

convert AC power received from the electrical grid to DC power during the reverse conduction mode.

19. A controller in accordance with claim 18, wherein the DC power is applied to at least one of a reactive power compensator and a battery during the reverse conduction mode.

20. A controller in accordance with claim 17, wherein the micro inverter includes a synchronous bi-directional DC to DC converter and a synchronous bi-directional DC to AC inverter, said controller is further configured to generate pulse width modulation signals to control operation of the synchronous bi-directional DC to DC converter and the synchronous bi-directional DC to AC inverter.