Method and apparatus for power conversion with maximum power point tracking and burst mode capability

• US 20090079383A1
• Filed: 09/25/2008
• Published: 03/26/2009
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Fornage, Martin, Hassan-Ali, Mudhafar
• Granted Patent: US 7,986,122 B2
• Time in Patent Office: Days
• US Class Current: 320/101
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• 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 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02M 1/0035 using burst mode control
• 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

An apparatus and method for converting a DC input power to a DC output power. The apparatus comprises an energy storage module and a burst mode controller. The burst mode controller causes energy to be stored in the energy storage module during at least one storage period, and further causes the energy to be drawn from the energy storage module during at least one burst period. During the at least one burst period, the DC output power is greater than the DC input power. Additionally, the burst mode controller employs a maximum power point tracking (MPPT) technique for operating a device providing the DC input power proximate a maximum power point (MPP).

Claims

1. An apparatus for converting DC input power to AC output power, comprising:

an energy storage module; and

a burst mode controller for (i) causing energy to be stored in the energy storage module during at least one storage period and the energy to be drawn from the energy storage module during at least one burst period, wherein the AC output power is greater than the DC input power during the at least one burst period, and (ii) employing a maximum power point tracking (MPPT) technique for operating a device providing the DC input power proximate a maximum power point (MPP).

2. The apparatus of claim 1, wherein the MPPT technique comprises computing a change in output power from the device with respect to a change in operating voltage of the device and utilizing a result of the computing to drive the device to the MPP.

3. The apparatus of claim 2, wherein the result of the computing indicates an AC current output must be decreased to reach the MPP when the result is positive and the AC current output must be increased to reach the MPP when the result is negative.

4. The apparatus of claim 2, wherein the burst mode controller comprises an MPPT module for receiving measures of an output current of the device and the operating voltage and performing the computing in accordance with the measures.

5. The apparatus of claim 4, wherein the at least one storage period begins when a voltage of the energy storage module satisfies a first threshold, and wherein the at least one burst period begins when the voltage satisfies a second threshold.

6. The apparatus of claim 5, wherein the burst mode controller determines the first and the second thresholds in accordance with the measures.

7. The apparatus of claim 6, further comprising a burst activation controller for determining when the first and second thresholds are satisfied.

8. The apparatus of claim 1, further comprising a burst current controller, wherein the burst current controller causes the AC output power to be greater than the DC input power.

9. The apparatus of claim 1, wherein the at least one storage period and the at least one burst period occur when the DC input power satisfies an operating power threshold.

10. The apparatus of claim 9, wherein the operating power threshold is 30% of a power rating of the device.

11. The apparatus of claim 1, wherein the energy storage module comprises at least one capacitor.

12. A method for converting DC input power to AC output power, comprising:

storing energy in an energy storage module during at least one storage period;

drawing energy from the energy storage module during at least one burst period, wherein the AC output power is greater than the DC input power during the at least one burst period; and

employing a maximum power point tracking (MPPT) technique for operating a device providing the DC input power proximate a maximum power point (MPP).

13. The method of claim 12, wherein the MMPT technique comprises computing a change in output power from the device with respect to a change in operating voltage of the device and utilizing a result of the computing to drive the device to the MPP.

14. The method of claim 13 wherein the result of the computing indicates an AC current output must be decreased to reach the MPP when the result is positive and the AC current output must be increased to reach the MPP when the result is negative.

15. The method of claim 13, further comprising receiving measures of an output current of the device and the operating voltage and performing the computing in accordance with the measures.

16. The method of claim 15, wherein the at least one storage period begins when a voltage of the energy storage module satisfies a first threshold, and wherein the at least one burst period begins when the voltage satisfies a second threshold.

17. The method of claim 16, further comprising determining the first and the second thresholds in accordance with the measures.

18. The method of claim 12, wherein the storing energy and the drawing energy occur when the DC input power satisfies an operating power threshold.

19. The method of claim 18, wherein the operating power threshold is 30% of a power rating of the device.

20. A system for power conversion, comprising:

at least one photovoltaic (PV) module;

at least one DC to AC inverter, wherein the at least one DC to AC inverter converts DC input power to AC output power;

at least one energy storage module; and

at least one burst mode controller for (i) causing energy to be stored in the at least one energy storage module during at least one storage period and the energy to be drawn from the at least one energy storage module during at least one burst period, wherein the AC output power of the at least one DC to AC inverter is greater than the DC input power of the at least one DC to AC inverter during the at least one burst period, and (ii) employing a maximum power point tracking (MPPT) technique for operating the at least one PV module proximate a maximum power point (MPP).

21. The system of claim 20, wherein the MPPT technique comprises computing a change in output power from the at least one PV module with respect to a change in operating voltage of the at least one PV module and utilizing a result of the computing to drive the at least one PV module to the MPP.