ARC fault protection for power conversion
View Patent ↗An apparatus and system for arc fault protection during power conversion. In one embodiment, the apparatus comprises a power converter comprising a first and a second pair of DC input terminals, coupled in series, for coupling to a first and a second DC source, respectively; an input bridge; an inductor; a first and a second arc fault protection capacitor, wherein (i) the series combination of the first and the second pair of DC input terminals is coupled across the input bridge, (ii) a first terminal of the inductor is coupled between the first and the second pair of DC input terminals, (iii) a second terminal of the inductor is coupled between switches on one leg of the input bridge, and (iv) the first and the second arc fault protection capacitors are coupled across the first and the second pair of DC input terminals, respectively.
1. An apparatus for arc fault protection during power conversion, comprising:
a power converter comprising:
a first pair of DC input terminals for coupling to a first DC source;
a second pair of DC input terminals, coupled in series to the first pair of DC input terminals, for coupling to a second DC source;
an input bridge;
an inductor;
a first arc fault protection capacitor; and
a second arc fault protection capacitor, wherein (i) the series combination of the first and the second pair of DC input terminals is coupled across the input bridge, (ii) a first terminal of the inductor is coupled between the first pair of DC input terminals and the second pair of DC input terminals, (iii) a second terminal of the inductor is coupled between switches on one leg of the input bridge, (iv) the first arc fault protection capacitor is coupled across the first pair of DC input terminals, and (v) the second arc fault protection capacitor is coupled across the second pair of DC input terminals.
2. The apparatus of claim 1 , wherein the power converter is a DC-AC inverter.
3. The apparatus of claim 1 , wherein the power converter is a DC-DC converter.
4. The apparatus of claim 1 , wherein the first and the second arc fault protection capacitors are sized based on an (a) expected inherent inductance in a circuit between the first and the second DC sources and the power converter, and (b) an expected amount of current.
5. The apparatus of claim 1 wherein each of the first and the second arc fault protection capacitors is on the order of tens to hundreds of nanofarads.
6. The apparatus of claim 1 , wherein the power converter further comprises an arc fault protection module for determining whether a voltage at a midpoint junction between the first and the second DC sources exhibits an arc fault signature and, when the voltage exhibits the arc fault signature, commanding the power converter to halt drawing power from the first and the second DC sources.
7. A system for arc fault protection during power conversion, comprising:
a first DC source;
a second DC source;
a power converter comprising:
a first pair of DC input terminals coupled in series to a second pair of DC input terminals, wherein the first pair of DC input terminals are coupled to the first DC source and the second pair of DC input terminals are coupled to the second DC source;
an input bridge coupled across the series combination of the first and the second pair of DC input terminals; and
an inductor wherein a first terminal of the inductor is coupled between the first and the second pair of DC input terminals, and a second terminal of the inductor is coupled between switches on one leg of the input bridge;
a first arc fault protection capacitor; and
a second arc fault protection capacitor, wherein the first arc fault protection capacitor is coupled across the first pair of DC input terminals, and the second arc fault protection capacitor is coupled across the second pair of DC input terminals.
8. The system of claim 7 , wherein the power converter is a DC-AC inverter.
9. The system of claim 7 , wherein the power converter is a DC-DC converter.
10. The system of claim 7 , wherein the first and the second arc fault protection capacitors are sized based on an (a) expected inherent inductance in a circuit between the first and the second DC sources and the power converter, and (b) an expected amount of current.
11. The system of claim 7 , wherein each of the first and the second arc fault protection capacitors is on the order of tens to hundreds of nanofarads.
12. The system of claim 7 , wherein the first and the second arc fault protection capacitors are within the power converter.
13. The system of claim 7 , wherein the first and the second arc fault protection capacitors are external to the power converter.
14. The system of claim 7 , wherein the first and the second arc fault protection capacitors are coupled across the first and the second DC sources, respectively, at the first and the second DC sources.
15. The system of claim 7 , wherein the first and the second DC sources are photovoltaic (PV) modules.
16. The system of claim 15 , wherein the first arc fault protection capacitor is within a PV module junction box of the first DC source, and the second arc fault protection capacitor is within a PV module junction box of the second DC source.
17. The system of claim 7 , wherein the power converter is a centralized power converter in a distributed generator (DG).
18. The system of claim 17 , wherein the DG comprises a PV array coupled to the power converter.
19. The system of claim 7 , wherein the power converter is coupled to a first string of DC sources and to a second string of DC sources, wherein the first string of DC sources comprises the first DC source, and wherein the second string of DC sources comprises the second DC source.
20. The system of claim 7 , wherein the power converter further comprises an arc fault protection module for determining whether a voltage at a midpoint junction between the first and the second DC sources exhibits an arc fault signature and, when the voltage exhibits the arc fault signature, commanding the power converter to halt drawing power from the first and the second DC sources.