# US 12,184,201 B2 · Power converter, photovoltaic power generation system, method, and apparatus

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- Number: US 12,184,201 B2
- Document ID: US12184201B2
- Status: Granted
- Kind: B2
- Application number: 18/175,583
- Filed: 2023-02-28
- Published: 2023-06-29
- Granted: 2024-12-31
- Earliest claimed: 2020-09-02
- Assignees: Huawei Digital Power Technologies Co., Ltd.
- Applicants: Huawei Digital Power Technologies Co., Ltd.
- Inventors: Yongbing Gao; Yunyu Tang; Lei Shi
- Web page: https://patentgrep.com/patent/US12184201B2

## CPC

- H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode
- H02J 3/381: {Dispersed generators}
- H02M 1/0048: {Circuits or arrangements for reducing losses (using snubbers H02M1/34)}
- H02M 1/0058: {by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826)}
- H02M 1/083: {for the ignition at the zero crossing of the voltage or the current}
- H02M 1/32: Means for protecting converters other than automatic disconnection
- H02M 3/04: by static converters
- H02M 7/487: Neutral point clamped inverters
- H02S 40/32: comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
- H02S 40/36: characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection
- H02J 3/32: using batteries or super capacitors with converting means
- H02J 2101/24: Photovoltaics
- Y02E 10/56: Power conversion systems, e.g. maximum power point trackers
- Y02E 70/30: Systems combining energy storage with energy generation of non-fossil origin
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A converter includes a power conversion circuit, a switching device, and a controller, and includes N phases, where N is 2 or 3. An input end of the power conversion circuit is connected to a direct current power supply, and the power conversion circuit converts a direct current output by the direct current power supply into an alternating current. The switching device includes at least the following two stages: a first-stage switching device and a second-stage switching device. The first-stage switching device and the second-stage switching device separately include N switches, and the N switches are connected in series to the N phases respectively. An output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series.

## Claims

### Claim 1

A power converter, comprising:
a power conversion circuit, wherein the power converter comprises N phases and N is either 2 or 3;
a switching device,
and a controller, wherein
an input end of the power conversion circuit is configured to connect to a direct current power supply, and the power conversion circuit is configured to convert a direct current output by the direct current power supply into an alternating current;
the switching device comprises at least the following two stages: a first-stage switching device and a second-stage switching device, wherein the first-stage switching device and the second-stage switching device separately comprise N switches, and the N switches are connected in series to the N phases respectively;
an output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series; and
the controller is configured to:
when the power conversion circuit is connected to the alternating current power grid, first control the N switches in the second-stage switching device to be simultaneously turned on, and then sequentially control the N switches in the first-stage switching device to be turned on one by one.

### Claim 2 (depends on 1)

The power converter according to claim 1, wherein the controller is further configured to:
output a first turn-on signal to control the N switches in the second-stage switching device to be simultaneously turned on and then sequentially
output a second turn-on signal to an (N+1)th turn-on signal to control the N switches in the first-stage switching device to be turned on one by one.

### Claim 3 (depends on 1)

The power converter according to claim 1, wherein,
when the power conversion circuit is connected to the alternating current power grid, the controller is further configured to change a sequence of turning on the N switches in the first-stage switching device one by one.

### Claim 4 (depends on 1)

The power converter according to claim 1, wherein the controller is further configured to:
when the power conversion circuit is disconnected from the alternating current power grid, first control, respectively based on output currents in the N phases of the power conversion circuit, the N switches in the first-stage switching device to be turned off one by one, and then control the N switches in the second-stage switching device to be simultaneously turned off.

### Claim 5 (depends on 4)

The power converter according to claim 4, wherein the controller is further configured to:
sequentially output a first turn-off signal to an Nth turn-off signal to control respectively the N switches in the first-stage switching device to be turned off one by one, and then
output an (N+1)th turn-off signal to control the N switches in the second-stage switching device to be simultaneously turned off.

### Claim 6 (depends on 5)

The power converter according to claim 5, wherein the controller is further configured to:
at a zero-crossing moment of a current in an ith phase in the output currents in the N phases of the power conversion circuit, control a switch in the ith phase in the first-stage switching device to be turned off, wherein i is a positive integer less than or equal to N.

### Claim 7 (depends on 6)

The power converter according to claim 6, wherein the controller is further configured to:
output, based on a preset turn-off delay time for the first-stage switching device and the zero-crossing moment of the current in the ith phase, a turn-off signal to the switch in the ith phase in the first-stage switching device, wherein the turn-off signal is used to turn off the switch in the ith phase.

### Claim 8 (depends on 4)

The power converter according to claim 4, wherein the controller is further configured to:
when it is determined that a short circuit fault occurs at the input end or the output end of the power conversion circuit, control the power conversion circuit to be disconnected from the alternating current power grid.

### Claim 9 (depends on 1)

The power converter according to claim 1, wherein the N switches in the second-stage switching device are integrated in one housing; and
the N switches in the first-stage switching device are separately disposed.

### Claim 10 (depends on 1)

The power converter according to claim 1, further comprising:
a DC-DC conversion circuit, wherein
an input end of the DC-DC conversion circuit is connected to the direct current power supply; and
an output end of the DC-DC conversion circuit is connected to the input end of the power conversion circuit.

### Claim 11

A photovoltaic power generation system, comprising:
a photovoltaic array; and
a power converter comprising a power conversion circuit, a switching device, and a controller, wherein
the power converter comprises N phases, wherein N is 2 or 3;
an input end of the power conversion circuit is configured to connect to a direct current power supply, and the power conversion circuit is configured to convert a direct current output by the direct current power supply into an alternating current;
the switching device comprises at least the following two stages: a first-stage switching device and a second-stage switching device, wherein the first-stage switching device and the second-stage switching device separately comprise N switches, and the N switches are connected in series to the N phases respectively;
an output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series; and
the controller is configured to:
when the power conversion circuit is connected to the alternating current power grid, first control the N switches in the second-stage switching device to be simultaneously turned on, and then sequentially control the N switches in the first-stage switching device to be turned on one by one;
wherein the photovoltaic array is connected to an input end of the power converter.

### Claim 12 (depends on 11)

The power converter according to claim 11, wherein the controller is further configured to:
output a first turn-on signal to control the N switches in the second-stage switching device to be simultaneously turned on and then sequentially
output a second turn-on signal to an (N+1)th turn-on signal to control the N switches in the first-stage switching device to be turned on one by one.

### Claim 13 (depends on 11)

The power converter according to claim 11, wherein when the power conversion circuit is connected to the alternating current power grid, the controller is further configured to:
change a sequence of turning on the N switches in the first-stage switching device one by one.

### Claim 14 (depends on 11)

The power converter according to claim 11, wherein the controller is further configured to:
when the power conversion circuit is disconnected from the alternating current power grid, first control, respectively based on output currents in the N phases of the power conversion circuit, the N switches in the first-stage switching device to be turned off one by one, and then
control the N switches in the second-stage switching device to be simultaneously turned off.

### Claim 15

A method for controlling an action of a switching device, applied to a power converter, wherein the power converter comprises a power conversion circuit and a switching device; the switching device comprises at least a first-stage switching device and a second-stage switching device; the power converter comprises N phases, wherein N is 2 or 3; an output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series; and the first-stage switching device and the second-stage switching device separately comprise N switches; and
the method comprises:
when the power conversion circuit is connected to the alternating current power grid, first controlling the N switches in the second-stage switching device to be simultaneously turned on; and
then sequentially controlling the N switches in the first-stage switching device to be turned on one by one.

### Claim 16 (depends on 15)

The method for controlling an action of a switching device according to claim 15, wherein sequentially controlling the N switches in the first-stage switching device to be turned on one by one further comprises:
when the power conversion circuit is connected to the alternating current power grid, changing a sequence of turning on the N switches in the first-stage switching device one by one.

### Claim 17 (depends on 15)

The method for controlling an action of a switching device according to claim 15, further comprising:
when the power conversion circuit is disconnected from the alternating current power grid, first sequentially controlling, based on output currents in the N phases of the power conversion circuit, the N switches in the first-stage switching device to be turned off one by one, and then controlling the N switches in the second-stage switching device to be simultaneously turned off.

### Claim 18 (depends on 17)

The method for controlling an action of a switching device according to claim 17, wherein sequentially controlling the N switches in the first-stage switching device to be turned off one by one further comprises:
at a zero-crossing moment of a current in an ith phase in the output currents in the N phases of the power conversion circuit, controlling a switch in the ith phase in the first-stage switching device to be turned off, wherein i is a positive integer less than or equal to N.

### Claim 19 (depends on 18)

The method for controlling an action of a switching device according to claim 18, wherein controlling the switch in the ith phase in the first-stage switching device to be turned off further comprises:
based on a preset turn-off delay time for the first-stage switching device and the zero-crossing moment of the current in the ith phase, outputting a turn-off signal to the switch in the ith phase in the first-stage switching device, wherein the turn-off signal is used to turn off the switch in the ith phase.

### Claim 20 (depends on 17)

The method for controlling an action of a switching device according to claim 17, further comprising:
determining whether a short circuit fault occurs at an input end or the output end of the power conversion circuit; and if a short circuit fault occurs at the input end or the output end of the power conversion circuit, controlling the power conversion circuit to be disconnected from the alternating current power grid.