# US 9,520,721 B2 · Solar photovoltaic three-phase micro-inverter and solar photovoltaic power generation system

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- Number: US 9,520,721 B2
- Document ID: US9520721B2
- Status: Granted
- Kind: B2
- Application number: 13/973,705
- Filed: 2013-08-22
- Published: 2013-12-19
- Granted: 2016-12-13
- Earliest claimed: 2011-02-23
- Assignees: Altenergy Power System Inc.
- Applicants: Yuhao Luo
- Inventors: Yuhao Luo
- Web page: https://patentgrep.com/patent/US9520721B2

## CPC

- H02J 3/381: {Dispersed generators}
- H02J 3/38: Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
- H02J 2101/24: Photovoltaics
- Y02E 10/56: Power conversion systems, e.g. maximum power point trackers
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A solar photovoltaic three-phase micro-inverter comprises: DC terminals, coupled with three DC photovoltaic assemblies adjacent to each other; three single-phase inverter circuits having input terminals coupled respectively with the three DC photovoltaic assemblies via the DC terminals, for converting the DC currents generated by the three DC photovoltaic assemblies to AC currents, respectively; AC terminals coupled with a three-phase AC power grid; wherein output terminals of each single-phase inverter circuit are coupled respectively with a neutral wire and one of the three phases of the three-phase AC power grid. A solar photovoltaic power generation system is also provided. The three single-phase inverter circuits can be integrated as above Because the three DC photovoltaic assemblies on one three-phase micro-inverter are disposed adjacently and have similar environment conditions, such as illumination, temperature, etc., the three-phase AC current can be well balanced.

## Claims

### Claim 1

A solar photovoltaic three-phase micro-inverter, comprising:
DC terminals, coupled with three DC photovoltaic assemblies which are adjacent to each other, for receiving DC currents generated by the DC photovoltaic assemblies;
three single-phase inverter circuits having input terminals coupled respectively with the three DC photovoltaic assemblies via the DC terminals, for converting the DC currents generated by the three DC photovoltaic assemblies to AC currents, respectively, wherein the three single-phase inverter circuits share a comparison circuit, a control circuit, and a communication circuit externally, wherein the comparison circuit is configured to compare an input/output current and voltage of the three single-phase inverter circuits respectively, and wherein the control circuit is configured to adjust the power conversion of the three single-phase inverter circuits if unbalance between the three phases is found;
AC terminals coupled with a three-phase AC power grid, for grid-connectedly outputting the AC currents generated by the three single-phase inverter circuits;
wherein output terminals of each single-phase inverter circuit are coupled respectively with a neutral wire and one of the three phases of the three-phase AC power grid.

### Claim 2 (depends on 1)

The three-phase micro-inverter of claim 1, wherein the three single-phase inverter circuits are the same.

### Claim 3 (depends on 2)

The three-phase micro-inverter of claim 2, wherein the single-phase inverter circuit comprises a DC-AC conversion circuit, a DC voltage and current detection circuit, an AC voltage and current detection circuit, and a filter circuit.

### Claim 4

A solar photovoltaic power generation system, comprising a plurality of solar photovoltaic three-phase micro-inverters, the plurality of three-phase micro-inverters having AC terminals coupled with the respective phases and neutral wire of a three-phase AC power grid respectively, wherein each three-phase micro-inverter comprises:
DC terminals, coupled with three DC photovoltaic assemblies which are adjacent to each other, for receiving DC currents generated by the DC photovoltaic assemblies;
three single-phase inverter circuits having input terminals coupled respectively with the three DC photovoltaic assemblies via the DC terminals, for converting the DC currents generated by the three DC photovoltaic assemblies to AC currents, respectively, wherein the three single-phase inverter circuits share a comparison circuit, a control circuit, and a communication circuit externally, wherein the comparison circuit is configured to compare an input/output current and voltage of the three single-phase inverter circuits respectively, and wherein the control circuit is configured to adjust the power conversion of the three single-phase inverter circuits if unbalance between the three phases is found;
AC terminals coupled with the three-phase AC power grid, for grid-connectedly outputting the AC currents generated by the three single-phase inverter circuits;
wherein output terminals of each single-phase inverter circuit are coupled respectively with a neutral wire and one of the three phases of the three-phase AC power grid.

### Claim 5 (depends on 4)

The solar photovoltaic power generation system of claim 4, wherein the AC terminals of the plurality of three-phase micro-inverters are coupled with each other first to form a three-phase micro-inverter string, which is then coupled with the three-phase AC power grid.

### Claim 6 (depends on 5)

The solar photovoltaic power generation system of claim 5, wherein the three single-phase inverter circuits in each three-phase micro-inverter are the same.

### Claim 7 (depends on 6)

The solar photovoltaic power generation system of claim 6, wherein the single-phase inverter circuit comprises a DC-AC conversion circuit, a DC voltage and current detection circuit, an AC voltage and current detection circuit, and a filter circuit.

### Claim 8 (depends on 4)

The solar photovoltaic power generation system of claim 4, wherein the plurality of three-phase micro-inverters are independent from each other, and have their AC terminals coupled with the respective phases and neutral wire of the three-phase AC power grid, respectively.

### Claim 9 (depends on 8)

The solar photovoltaic power generation system of claim 8, wherein the three single-phase inverter circuits in each three-phase micro-inverter are the same.

### Claim 10 (depends on 9)

The solar photovoltaic power generation system of claim 9, wherein the single-phase inverter circuit comprises a DC-AC conversion circuit, a DC voltage and current detection circuit, an AC voltage and current detection circuit, and a filter circuit.

### Claim 11 (depends on 4)

The solar photovoltaic power generation system of claim 4, wherein the three single-phase inverter circuits in each three-phase micro-inverter are the same.

### Claim 12 (depends on 11)

The solar photovoltaic power generation system of claim 11, wherein the single-phase inverter circuit comprises a DC-AC conversion circuit, a DC voltage and current detection circuit, an AC voltage and current detection circuit, and a filter circuit.