Method and apparatus for improved burst mode during power conversion
View Patent ↗A method and apparatus for power conversion. In one embodiment, the apparatus comprises a DC-AC conversion stage; an intermediate capacitor coupled across the DC-AC conversion stage; and a burst mode controller coupled to the intermediate capacitor and the DC-AC conversion stage, wherein the burst mode controller (i) maintains a voltage of the intermediate capacitor below a preset limit during a storage period and (ii) drives the DC-AC conversion stage to convert DC input to AC output during a burst period, wherein the storage and burst periods occur during a burst mode operation.
1. An apparatus for power conversion, comprising:
a DC-AC conversion stage;
an intermediate capacitor coupled across the DC-AC conversion stage; and
a burst mode controller coupled to the intermediate capacitor and the DC-AC conversion stage, wherein the burst mode controller (i) maintains a voltage of the intermediate capacitor below a preset limit during a storage period and (ii) drives the DC-AC conversion stage to convert DC input to AC output during a burst period, wherein the storage and burst periods occur during a burst mode operation.
2. The apparatus of claim 1 , wherein the DC input results from a DC input current and energy stored in the intermediate capacitor.
3. The apparatus of claim 2 , further comprising a DC-DC conversion stage coupled across the intermediate capacitor, wherein the DC-DC conversion stage provides the DC input current.
4. The apparatus of claim 2 , wherein the energy is stored during the storage period and the storage period is at least one AC grid voltage cycle.
5. The apparatus of claim 1 , wherein the DC-AC conversion stage is disabled during the storage period.
6. The apparatus of claim 1 , wherein the preset limit is 10% of an average voltage from a DC source.
7. The apparatus of claim 1 , wherein the burst mode operation occurs when input power from a DC source is below a burst mode threshold.
8. The apparatus of claim 7 , further comprising a maximum power point tracking (MPPT) controller for biasing the DC source proximate a maximum power point (MPP).
9. The apparatus of claim 1 , wherein the AC output is synchronous with an AC grid voltage.
10. The apparatus of claim 1 , wherein the storage period ends and the burst period begins based on the voltage.
11. A method for power conversion, comprising:
storing energy during a storage period, wherein a voltage of an intermediate capacitor across a DC-AC conversion stage is maintained below a preset limit during the storage period; and
driving a DC-AC conversion stage to convert DC input to AC output during a burst period, wherein the storage and burst periods occur during a burst mode operation.
12. The method of claim 11 , wherein the DC input results from a DC input current and the energy stored in the intermediate capacitor.
13. The method of claim 12 , wherein the DC input current is provided by a DC-DC conversion stage coupled across the intermediate capacitor.
14. The method of claim 12 , wherein the storage period is at least one AC grid voltage cycle.
15. The method of claim 11 , further comprising disabling the DC-AC conversion stage during the storage period.
16. The method of claim 11 , wherein the preset limit is 10% of an average voltage from a DC source.
17. The method of claim 11 , wherein the burst mode operation occurs when input power from a DC source is below a burst mode threshold.
18. The method of claim 17 , further comprising biasing the DC source proximate a maximum power point (MPP).
19. The method of claim 11 , wherein the AC output is synchronous with an AC grid voltage.
20. The method of claim 11 , wherein the storage period ends and the burst period begins based on the voltage.