# US 2019/0173379 A1 · Power converter

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- Number: US 2019/0173379 A1
- Document ID: US20190173379A1
- Status: Published application
- Kind: A1
- Application number: 16/266,210
- Filed: 2019-02-04
- Published: 2019-06-06
- Earliest claimed: 2016-09-30
- Assignees: Panasonic Intellectual Property Management Co., Ltd.
- Applicants: Panasonic Intellectual Property Management Co., Ltd.
- Inventors: Yusuke IWAMATSU; Naoaki FUJII
- Web page: https://patentgrep.com/patent/US20190173379A1

## CPC

- H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators
- G05F 1/67: to the maximum power available from a generator, e.g. from solar cell
- 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 3/381: {Dispersed generators}
- H02M 7/44: by static converters
- H02M 7/53871: {with automatic control of output voltage or current}
- H02J 2101/25: {involving maximum power point tracking control for photovoltaic sources}
- H02M 1/0003: {Details of control, feedback or regulation circuits}
- H02M 1/007: {Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826)}
- Y02E 10/56: Power conversion systems, e.g. maximum power point trackers
- 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)
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- 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 first controller controls the DC-DC converter to perform a step-up operation when a voltage on the DC bus is lower than a first reference voltage and controls the DC-DC converter to suspend the step-up operation when the voltage is equal to or higher than the first reference voltage. A second controller controls the inverter to maintain the voltage on the DC bus constant when the voltage on the DC bus is lower than a second reference voltage and controls the inverter to maximize an output power of the inverter when the voltage is equal to or higher than the second reference voltage.

## Claims

### Claim 1

A power conversion system comprising:
a DC-DC converter that converts a DC power supplied from a solar cell into a DC power of a different voltage and outputs the DC power to a DC bus;
an inverter that converts the DC power input from the DC bus into an AC power and outputs the AC power to a system;
a first controller that controls the DC-DC converter to perform a step-up operation when a voltage on the DC bus is lower than a first reference voltage and controls the DC-DC converter to suspend the step-up operation when the voltage is equal to or higher than the first reference voltage; and
a second controller that controls the inverter to maintain the voltage on the DC bus constant when the voltage on the DC bus is lower than a second reference voltage and controls the inverter to maximize an output power of the inverter when the voltage is equal to or higher than the second reference voltage.

### Claim 2 (depends on 1)

The power conversion system according to claim 1, wherein
the first reference voltage and the second reference voltage are set to be higher than a peak value of a system voltage.

### Claim 3 (depends on 1)

The power conversion system according to claim 1, wherein
the first reference voltage is set to be lower than the second reference voltage.

### Claim 4 (depends on 3)

The power conversion system according to claim 3, wherein
a difference is provided between a speed of power control of the DC-DC converter by the first controller and a speed of power control of the inverter by the second controller.

### Claim 5 (depends on 1)

The power conversion system according to claim 1, further comprising:
a communication line provided for control between the first controller and the second controller, wherein
one of: the process of communicating a result of comparing the voltage on the DC bus with the first reference voltage from the first controller to the second controller via the communication line; and the process of communicating a result of comparing the voltage on the DC bus with the second reference voltage from the second controller to the first controller via the communication line is executed.

### Claim 6 (depends on 1)

The power conversion system according to claim 1, wherein
hysteresis is introduced in the first reference voltage and the second reference voltage.

### Claim 7 (depends on 1)

The power conversion system according to claim 1, wherein
the first reference voltage and the second reference voltage are set to be higher than a peak value of a system voltage and the maximum power point voltage of the solar cell, and
the second controller controls the voltage on the DC bus to be maintained at a voltage lower than the first reference voltage and the second reference voltage and higher than the peak value of the system voltage and the maximum power point voltage of the solar cell.

### Claim 8 (depends on 1)

The power conversion system according to claim 1, wherein
the first controller progressively lowers an output power of the DC-DC converter when the voltage on the DC bus becomes equal to or higher than the first reference voltage and progressively raises the output power of the DC-DC converter when the voltage on the DC bus becomes lower than the first reference voltage.

### Claim 9 (depends on 1)

The power conversion system according to claim 1, wherein
the first power controller forces suspension of an operation of the DC-DC converter when the voltage on the DC bus is equal to or higher than a third reference voltage higher than the first reference voltage.

### Claim 10 (depends on 1)

The power conversion system according to claim 1, wherein
when an output power of the solar cell is restricted, the second controller controls the inverter such that the voltage on the DC bus is equal to or higher than the first reference voltage.

### Claim 11

A power converter comprising:
a DC-DC converter that converts a DC power supplied from a solar cell into a DC power of a different voltage and outputs the DC power to a DC bus; and
a first controller that controls the DC-DC converter to perform a step-up operation when a voltage on the DC bus is lower than a first reference voltage and controls the DC-DC converter to suspend the step-up operation when the voltage is equal to or higher than the first reference voltage,
the power converter being connected to a further power converter including:
an inverter that converts the DC power input from the DC bus into an AC power and outputs the AC power to a system; and a second controller that controls the inverter to maintain the voltage on the DC bus constant when the voltage on the DC bus is lower than a second reference voltage and controls the inverter to maximize an output power of the inverter when the voltage is equal to or higher than the second reference voltage.

### Claim 12

A power converter connected to a further power converter including:
a DC-DC converter that converts a DC power supplied from a solar cell into a DC power of a different voltage and outputs the DC power to a DC bus; and a first controller that controls the DC-DC converter to perform a step-up operation when a voltage on the DC bus is lower than a first reference voltage and controls the DC-DC converter to suspend the step-up operation when the voltage is equal to or higher than the first reference voltage,
the power converter comprising:
an inverter that converts the DC power input from the DC bus into an AC power and outputs the AC power to a system; and
a second controller that controls the inverter to maintain the voltage on the DC bus constant when the voltage on the DC bus is lower than a second reference voltage and controls the inverter to maximize an output power of the inverter when the voltage is equal to or higher than the second reference voltage.