# US 9,882,508 B2 · High-frequency switching type conversion device

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- Number: US 9,882,508 B2
- Document ID: US9882508B2
- Status: Granted
- Kind: B2
- Application number: 15/032,197
- Filed: 2014-12-19
- Published: 2016-09-15
- Granted: 2018-01-30
- Earliest claimed: 2014-01-10
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Industries, Ltd.
- Inventors: Naoki Ayai; Tetsuo Akita; Toshiaki Okumura; Kenji Abiru
- Web page: https://patentgrep.com/patent/US9882508B2

## CPC

- H02M 7/44: by static converters
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 1/42: Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators
- H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M 1/0009: {Devices or circuits for detecting current in a converter}
- 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)}
- H02M 3/04: by static converters
- 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)

## Abstract

Provided is a conversion device that converts DC power provided from a DC power supply, to AC power and supplies the AC power to a load, the conversion device including: a filter circuit connected to the load and including an AC reactor and a first capacitor; a DC/AC inverter connected to the load via the filter circuit; a DC/DC converter provided between the DC power supply and the DC/AC inverter; a second capacitor provided between the DC/AC inverter and the DC/DC converter; and a control unit configured to set a current target value for the DC/DC converter to thereby be synchronized with current of the AC power, based on voltage of the AC power, voltage variation due to current flowing through the AC reactor and an impedance thereof, reactive currents respectively flowing through the first capacitor and the second capacitor, and voltage of the DC power.

## Claims

### Claim 1

A high-frequency switching type conversion device that converts DC power provided from a DC power supply, to AC power and supplies the AC power to a load, the conversion device comprising:
a filter circuit connected to the load and including an AC reactor and a first capacitor;
a DC/AC inverter connected to the load via the filter circuit;
a DC/DC converter provided between the DC power supply and the DC/AC inverter;
a second capacitor provided between the DC/AC inverter and the DC/DC converter; and
a control unit configured to control the DC/DC converter and the DC/AC inverter to alternately have a stop period of high-frequency switching, the control unit being configured to set a current target value for the DC/DC converter to thereby be synchronized with current of the AC power, based on voltage of the AC power, voltage variation due to current flowing through the AC reactor and an impedance of the AC reactor, reactive currents respectively flowing through the first capacitor and the second capacitor, and voltage of the DC power,
wherein, in a case where an output current target value for the load is Ia*, an electrostatic capacitance of the first capacitor is Ca, a voltage value of the AC power is Va, voltage on the DC power supply side is VDC, and a Laplace operator is s, the control unit sets an AC output current target value Iinv* for the DC/AC inverter at a circuit connection point between the filter circuit and the DC/AC inverter.

### Claim 2 (depends on 1)

The conversion device according to claim 1, wherein in a case where an output current target value for the load is Ia*, an electrostatic capacitance of the first capacitor is Ca, a voltage value of the AC power is Va, voltage on the DC power supply side is VDC, and an Laplace operator is s, the control unit sets an AC output current target value Iinv* for the DC/AC inverter at a circuit connection point between the filter circuit and the DC/AC inverter, as follows “this should be” in the case where the output current target value for the load is Ia*, the electrostatic capacitance of the first capacitor is Ca, the voltage value of the AC power is Va, voltage on the DC power supply side is VDC, and the Laplace operator is s, the control unit sets the AC output current target value Iinv* for the DC/AC inverter at the circuit connection point between the filter circuit and the DC/AC inverter, as follows
Iinv*=Ia*+sCaVa,
in a case where an impedance of the AC reactor is Za, the control unit sets an AC output voltage target value Vinv* for the DC/AC inverter at the circuit connection point, as follows:
Vinv*=Va+ZaIinv*,
the control unit sets the greater one of the voltage VDC and an absolute value of the AC output voltage target value Vinv* for the DC/AC inverter, as an output voltage target value Vo* for the DC/DC converter, and
in a case where an electrostatic capacitance of the second capacitor is C, the control unit sets a current target value Iin* for the DC/DC converter, as follows:
Iin*={(Iinv*×Vinv*)+(sCVo*)×Vo*}/VDC.

### Claim 3 (depends on 2)

The conversion device according to claim 2, wherein the DC/DC converter includes a DC reactor, and in a case where voltage of the DC power supply is Vg, an impedance of the DC reactor is Z, and a current value of the DC/DC converter is Iin, (Vg−ZIin) is used as the voltage VDC.

### Claim 4 (depends on 3)

The conversion device according to claim 3, wherein the current value Iin of the DC/DC converter is set to a detection value of a current sensor or a calculation value obtained by Iinv*×Vinv*/Vg.

### Claim 5 (depends on 1)

The conversion device according to claim 1, wherein
the DC/AC inverter is controlled based on comparison between a reference value based on a target value and a detection value of AC output current of the DC/AC inverter, and
an output voltage target value for the DC/DC converter, and the DC/DC converter is controlled based on comparison between a reference value based on a current target value and a detection value of the DC/DC converter, and the output voltage target value for the DC/DC converter.

### Claim 6 (depends on 1)

The conversion device according to claim 1, wherein
the load is a commercial power system.

### Claim 7 (depends on 1)

The conversion device according to claim 1, wherein the DC power supply is a DC load, and the load is an AC power supply, and power is supplied from the AC power supply to the DC load.

### Claim 8 (depends on 1)

The conversion device according to claim 1, wherein
a SiC element is used for at least one of semiconductor switching elements included in the DC/DC converter and the DC/AC inverter.

### Claim 9 (depends on 2)

The conversion device according to claim 2, wherein
the DC/AC inverter is controlled based on comparison between a reference value based on a target value and a detection value of AC output current of the DC/AC inverter, and an output voltage target value for the DC/DC converter, and
the DC/DC converter is controlled based on comparison between a reference value based on a current target value and a detection value of the DC/DC converter, and the output voltage target value for the DC/DC converter.

### Claim 10 (depends on 3)

The conversion device according to claim 3, wherein
the DC/AC inverter is controlled based on comparison between a reference value based on a target value and a detection value of AC output current of the DC/AC inverter, and an output voltage target value for the DC/DC converter, and
the DC/DC converter is controlled based on comparison between a reference value based on a current target value and a detection value of the DC/DC converter, and the output voltage target value for the DC/DC converter.

### Claim 11 (depends on 4)

The conversion device according to claim 4, wherein
the DC/AC inverter is controlled based on comparison between a reference value based on a target value and a detection value of AC output current of the DC/AC inverter, and an output voltage target value for the DC/DC converter, and
the DC/DC converter is controlled based on comparison between a reference value based on a current target value and a detection value of the DC/DC converter, and the output voltage target value for the DC/DC converter.