Multilevel converter with energy storage
View Patent ↗A multilevel power converter includes at least one phase leg. The phase leg includes a plurality of cascaded chain link connected cells, each cell including a capacitor and two semiconductor switches in series, each with an anti-parallel connected diode. The plurality of cascaded chain link connected cells includes first and second cells which form a mirrored cell-pair such that the two semiconductor switches of each of the first and second cells are all connected in series with each other. The converter further includes an energy storage connected between the first and second cells.
1. A multilevel power converter comprising:
at least one phase leg, the at least one phase leg comprising a plurality of cascaded chain link connected cells and a plurality of switches, wherein the plurality of switches as a whole is connected to each of the plurality of cascaded chain link connected cells, each of the plurality of cascaded chain link connected cells comprises a capacitor and two semiconductor switches in series, and each of the two semiconductor switches is with an anti-parallel connected diode,
wherein the plurality of cascaded chain link connected cells comprises first and second cells forming a mirrored cell-pair such that the two semiconductor switches of each of the first and second cells are all connected in series with each other, and
wherein the converter further comprises a first energy storage connected to the plurality of switches to allow the first energy storage to selectively form a current path between the first energy storage and either one or both of the cell capacitors of the first and second cells by the plurality of switches.
2. A multilevel power converter comprising:
at least one phase leg, the at least one phase leg comprising a plurality of cascaded chain link connected cells, each of the plurality of cascaded chain link connected cells comprising a capacitor and two semiconductor switches in series, each with an anti-parallel connected diode,
wherein the plurality of cascaded chain link connected cells comprises first and second cells forming a mirrored cell-pair such that the two semiconductor switches of each of the first and second cells are all connected in series with each other, and
wherein the converter further comprises a first energy storage connected such as to allow the first energy storage to connect over either one or both of the cell capacitors of the first and second cells by switches,
wherein the first energy storage is connected via first and second switches such that when the first switch is turned on and the second switch is turned off, the first energy storage is connected over the capacitors of both first and second cells, and when the first switch is turned off and the second switch is turned on, the first energy storage is connected over the capacitor of the second cell but not over the capacitor of the first cell.
3. The converter of claim 2 , further comprising a distributed phase inductance connected between the first and second cells such that the distributed phase inductance is connected in series with the series connected semiconductor switches of the first and second cells, between the semiconductor switches of the first cell and the semiconductor switches of the second cell.
4. The converter of claim 3 , wherein the second switch is connected in series with the distributed phase inductance.
5. The converter of claim 3 , further comprising a bypass switch connected in series with the distributed phase inductance, for bypassing one of the first and second cells.
6. The converter of claim 1 , wherein the first energy storage is a battery or a supercapacitor.
7. The converter of claim 2 , wherein the first cell is a full-bridge cell and the first and second switches form part of the full-bridge configuration.
8. The converter of claim 1 , further comprising a second energy storage connected such as to allow the second energy storage to connect over either one or both of the cell capacitors of the first and second cells.
9. The converter of claim 8 , wherein the second energy storage is connected via first and second lower switches such that when the first lower switch is turned on and the second lower switch is turned off, the second energy storage is connected over the capacitors of both first and second cells, and when the first lower switch is turned off and the second lower switch is turned on, the second energy storage is connected over the capacitor of the first cell but not over the capacitor of the second cell.
10. The converter of claim 4 , further comprising a bypass switch connected in series with the distributed phase inductance, for bypassing one of the first and second cells.
11. The converter of claim 2 , wherein the first energy storage is a battery or a supercapacitor.
12. The converter of claim 3 , wherein the first energy storage is a battery or a supercapacitor.
13. The converter of claim 4 , wherein the first energy storage is a battery or a supercapacitor.
14. The converter of claim 5 , wherein the first energy storage is a battery or a supercapacitor.
15. The converter of claim 3 , wherein the first cell is a full-bridge cell and the first and second switches form part of the full-bridge configuration.
16. The converter of claim 4 , wherein the first cell is a full-bridge cell and the first and second switches form part of the full-bridge configuration.
17. The converter of claim 5 , wherein the first cell is a full-bridge cell and the first and second switches form part of the full-bridge configuration.
18. The converter of claim 6 , wherein the first cell is a full-bridge cell and the first and second switches form part of the full-bridge configuration.
19. The converter of claim 2 , further comprising a second energy storage connected such as to allow the second energy storage to connect over either one or both of the cell capacitors of the first and second cells.
20. The converter of claim 3 , further comprising a second energy storage connected such as to allow the second energy storage to connect over either one or both of the cell capacitors of the first and second cells.