Granted Patent B2

US 12,627,158 · App. 17/948,878 · Granted May 12, 2026

Inventors: Alexander W. Au (Oakland, CA); Yang Liu (Mountain View, CA)

Assignee: NEXTPOWER LLC

H02J7/35H02J1/102H02J3/32H02J3/381H02J3/388H02J3/46H02J7/0013H02S40/32H02S40/36H02S40/38H02J1/106H02J2300/26

Abstract

Claims (39)

1 . A distributed direct current (DC) power system comprising:

a common DC bus;

an inverter configured to invert DC power to alternating current (AC) power coupled to the common DC bus;

a plurality of tracking controllers coupled to a plurality of photovoltaic (PV) strings and coupled to the common DC bus, the plurality of tracking controllers configured to maximize solar power production of the plurality of PV strings and minimize mismatch between the plurality of PV strings;

a plurality of DC-DC battery converters (DCBCs) coupled to a plurality of batteries and to the common DC bus, the plurality of DCBCs configured to;

manage charge and discharge of the plurality of batteries;

enable interconnection of the plurality of PV strings and the plurality of batteries via the common DC bus; and

maintain a constant DC voltage to at the inverter via the common DC bus;

wherein the common DC bus connects the plurality of tracking controllers and the plurality of DCBCs to each other and connects the plurality of tracking controllers and the plurality of DCBCs to the inverter.

2 . The distributed DC power system of claim 1 , further comprising a plurality of battery management controllers coupled between the plurality of batteries and the plurality of DCBCs, respectively, the plurality of battery management controllers configured to start up the plurality of DCBCs.

3 . The distributed DC power system of claim 1 , wherein the plurality of batteries is a plurality of flow battery stacks,

further comprising a battery management controller coupled between at least one flow battery stack of the plurality of flow battery stacks and a DCBC of the plurality of DCBCs.

4 . The distributed DC power system of claim 1 , wherein the plurality of batteries are vanadium flow batteries.

5 . The distributed DC power system of claim 1 , further comprising a PV combiner coupled to the plurality of PV strings and including a plurality of disconnect switches and an arc fault detector coupled to outputs of the plurality of disconnect switches.

6 . The distributed DC power system of claim 5 , further comprising a plurality of fuses coupled between the plurality of PV strings and the plurality of disconnect switches, respectively.

7 . The distributed DC power system of claim 1 , further comprising:

a plurality of disconnect switches coupled to outputs of the plurality of PV strings, respectively; and

a plurality of arc fault detectors coupled to outputs of the plurality of disconnect switches, respectively,

wherein the plurality of tracking controllers are coupled to outputs of a plurality of arc fault detectors, respectively.

8 . The distributed DC power system of claim 1 , wherein the inverter includes a plurality of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs).

9 . The distributed DC power system of claim 1 , wherein the inverter is a single-stage inverter.

10 . The distributed DC power system of claim 1 , wherein the plurality of tracking controllers includes a plurality of maximum power point tracking (MPPT) converters, respectively.

11 . The distributed DC power system of claim 1 , further comprising a network control unit (NCU) in communication with each of the plurality of tracking controllers and each of the plurality of DCBCs, the NCU configured to control the plurality of DCBCs to maintain the constant DC voltage at the inverter.

12 . A method of controlling a distributed direct current (DC) power system, the method comprising:

maintaining a constant predetermined DC voltage on a DC bus connected to an inverter;

operating a plurality of DC-DC battery converters (DCBCs) in a constant voltage mode, each of the plurality of DCBCs being coupled to one or more batteries and coupled to the DC bus;

charging the one or more batteries coupled to each DCBC to an initial charge;

in response to the one or more batteries being charged to the initial charge, operating the plurality of DCBCs in a constant power mode, the constant power mode being distinct from the constant voltage mode; and

in response to a reduction of charge or discharge current of the one or more batteries, operating the plurality of DCBCs in the constant voltage mode.

13 . The method of claim 12 , further comprising exporting, by a plurality of maximum power point tracking (MPPT) converters, power to a DC distribution bus.

14 . The method of claim 12 , wherein the constant predetermined voltage is between 1200 V and 1600 V.

15 . The method of claim 12 , wherein operating the plurality of DCBCs in a constant power mode comprises controlling the plurality of DCBCs to charge the one or more batteries coupled to each DCBC at a constant power.

16 . A method of controlling a distributed direct current (DC) power system, the method comprising:

exporting, by a plurality of maximum power point tracking (MPPT) converters, power to a DC bus, the DC bus connected as an input to an inverter;

maintaining a constant predetermined DC voltage on the DC bus;

operating a plurality of DC-DC battery converters (DCBCs) in a constant voltage mode, each of the DCBCs being coupled to one or more batteries and coupled to the DC bus;

charging the one or more batteries coupled to each DCBC to an initial charge;

in response to the one or more batteries being charged to the initial charge, operating the plurality of DCBCs in a constant power mode; and

in response to a reduction of charge or discharge current of the one or more batteries, operating the plurality of DCBCs in the constant voltage mode.

Assignments (3)

Continuity (4)

References Cited (62)