Power conversion device and control method for power conversion device

Patent metadata

Field	Value
Publication number	US-10917022-B2
Application number	US-201716314043-A
Country	US
Kind code	B2
Filing date	Jun 6, 2017
Priority date	Jul 15, 2016
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

This power conversion device includes: a power conversion unit 20 provided between a DC power supply 2 and an AC electric path 3 and configured to perform DC/AC power conversion; and a control unit 14 configured to control the power conversion unit 20 . The control unit 14 includes a determination unit 25 configured to determine whether or not a starting current has flowed through the AC electric path 3 , and an adjustment unit 26 configured to adjust an AC voltage generated by the power conversion unit 20 , on the basis of a result of the determination by the determination unit 25.

First claim

The invention claimed is:

1. A power conversion device comprising:
a power conversion unit provided between a DC power supply and an AC electric path and configured to perform DC/AC power conversion; and
a control unit configured to control the power conversion unit, wherein
the control unit includes
a determination unit configured to compare a value of a current flowing through the AC electric path with a predetermined starting current threshold value set at a value larger than a rated current value of the power conversion device, and to determine whether or not a starting current has flowed through the AC electric path on the basis of a comparison result of the value of a current flowing and the starting current threshold value, the starting current being a current that temporarily flows and being larger than the rated current value, and
an adjustment unit configured to adjust an AC voltage generated by the power conversion unit, on the basis of a result of the determination by the determination unit, wherein

the adjustment unit adjusts to decrease the AC voltage when the result of the determination indicates that the starting current flows through the AC electric path.

2. The power conversion device according to claim 1 , wherein
the power conversion unit includes
a DC/DC converter provided between the DC power supply and a DC bus and configured to boost a DC voltage of the DC power supply to a predetermined intermediate voltage, and
an inverter connected between the DC bus and the AC electric path and configured to convert the intermediate voltage to an AC voltage waveform, and

the adjustment unit adjusts a voltage for the DC bus generated by the DC/DC converter and the AC voltage, on the basis of a result of the determination by the determination unit.

3. The power conversion device according to claim 1 , wherein
the adjustment unit adjusts a voltage command value for adjusting the AC voltage in a vicinity of zero cross of an AC waveform of the AC voltage.

4. The power conversion device according to claim 1 , wherein
the control unit compares the value of the current flowing through the AC electric path with a predetermined overcurrent protection threshold value being a value between the rated current value and the starting current threshold value, and
the adjustment unit adjusts the AC voltage generated by the power conversion unit, on the basis of a result of the determination by the determination unit and a result of comparison between the value of the current flowing through the AC electric path and the predetermined overcurrent protection threshold value.

5. The power conversion device according to claim 2 , wherein
the control unit controls the power conversion unit such that, for generating the AC voltage from the DC voltage, a first period during which the DC/DC converter boosts the DC voltage and the inverter performs one of polarity non-inversion passing and polarity inversion passing, and a second period during which the DC/DC converter is stopped and the inverter performs step-down operation and one of polarity non-inversion passing and polarity inversion passing, arise alternately in one AC cycle.

6. A control method for a power conversion device including a power conversion unit provided between a DC power supply and an AC electric path and configured to perform DC/AC power conversion, the control method comprising:
a determination step of comparing a value of a current flowing through the AC electric path with a predetermined starting current threshold value set at a value larger than a rated current value of the power conversion device, and determining whether or not a starting current has flowed through the AC electric path on the basis of a comparison result of the value of a current flowing and the starting current threshold value, the starting current being a current that temporarily flows and being larger than the rated current value, and
an adjustment step of adjusting an AC voltage generated by the power conversion unit, on the basis of a result of the determination in the determination step, wherein
in the adjustment step, the AC voltage is decreased by adjusting when the result of the determination indicates that the starting current flows through the AC electric path.

Assignees

• Sumitomo Electric Industries

Inventors

• Akita Tetsuo
• Shimizu Yusuke
• Ayai Naoki

Classifications

• H02M3/156 Primary

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• H02M1/007

  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) · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02M7/53871 Primary

  with automatic control of output voltage or current · CPC title