Power conversion device and three-phase alternating current power supply device

Patent metadata

Field	Value
Publication number	US-2016336873-A1
Application number	US-201515110510-A
Country	US
Kind code	A1
Filing date	Jan 5, 2015
Priority date	Jan 10, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

Provided is a power conversion device including: a conversion device for each phase which converts DC voltage inputted from a DC power supply, to voltage having an AC waveform to be outputted to each phase with respect to a neutral point of three-phase AC; and a control unit which controls these conversion devices. Each conversion device includes: a first converter which has a DC/DC converter including an isolation transformer, and a capacitor, and which converts the inputted DC voltage to voltage containing a pulsating DC voltage waveform corresponding to the absolute value of the AC waveform to be outputted; and a second converter which is provided at a stage subsequent to the first converter and has a full-bridge inverter, and which inverts the polarity of the voltage containing the pulsating DC voltage waveform, per one cycle, thereby converting the voltage to voltage having the AC waveform.

First claim

1 . A power conversion device for converting DC voltage inputted from a DC power supply, to three-phase AC voltage, the power conversion device comprising:
a first-phase conversion device configured to convert the DC voltage inputted from the DC power supply, to voltage having an AC waveform to be outputted to a first phase with respect to a neutral point of three-phase AC; a second-phase conversion device configured to convert the DC voltage inputted from the DC power supply, to voltage having an AC waveform to be outputted to a second phase with respect to the neutral point; a third-phase conversion device configured to convert the DC voltage inputted from the DC power supply, to voltage having an AC waveform to be outputted to a third phase with respect to the neutral point; and a control unit configured to control the first-phase conversion device, the second-phase conversion device, and the third-phase conversion device, wherein each of the first-phase conversion device, the second-phase conversion device, and the third-phase conversion device includes: a first converter having a DC/DC converter including an isolation transformer, and a smoothing capacitor, the first converter converting, by the DC/DC converter controlled by the control unit, the inputted DC voltage to voltage containing a pulsating DC voltage waveform corresponding to an absolute value of the AC waveform to be outputted; and a second converter provided at a stage subsequent to the first converter and having a full-bridge inverter, the second converter inverting, by the full-bridge inverter controlled by the control unit, a polarity of the voltage containing the pulsating DC voltage waveform, per one cycle, thereby converting the voltage to voltage having the AC waveform.

2 . The power conversion device according to claim 1 , wherein
the first converter converts the DC voltage to voltage having the consecutive pulsating DC voltage waveform.

3 . The power conversion device according to claim 1 , wherein
during a period in which the voltage outputted from the first converter is equal to or lower than a predetermined proportion of a wave crest value of the pulsating DC voltage waveform, the control unit causes the full-bridge inverter to perform inverter operation at a high frequency, thereby generating voltage having the AC waveform in the period.

4 . The power conversion device according to claim 3 , wherein
the predetermined proportion is 18% to 35%.

5 . The power conversion device according to claim 1 , wherein
the capacitor has such a capacitance that allows high-frequency voltage variation due to switching in the first converter to be smoothed but does not allow the pulsating DC voltage waveform to be smoothed.

6 . A three-phase AC power supply device comprising:
a first-phase conversion device configured to convert DC voltage inputted from the DC power supply, to voltage having an AC waveform to be outputted to a first phase with respect to a neutral point of three-phase AC; a second-phase conversion device configured to convert DC voltage inputted from the DC power supply, to voltage having an AC waveform to be outputted to a second phase with respect to the neutral point; a third-phase conversion device configured to convert DC voltage inputted from the DC power supply, to voltage having an AC waveform to be outputted to a third phase with respect to the neutral point; and a control unit configured to control the first-phase conversion device, the second-phase conversion device, and the third-phase conversion device, wherein each of the first-phase conversion device, the second-phase conversion device, and the third-phase conversion device includes: a first converter having a DC/DC converter including an isolation transformer, and a smoothing capacitor, the first converter converting, by the DC/DC converter controlled by the control unit, the inputted DC voltage to voltage containing a pulsating DC voltage waveform corresponding to an absolute value of the AC waveform to be outputted; and a second converter provided at a stage subsequent to the first converter and having a full-bridge inverter, the second converter inverting, by the full-bridge inverter controlled by the control unit, a polarity of the voltage containing the pulsating DC voltage waveform, per one cycle, thereby converting the voltage to voltage having the AC waveform.

7 . The power conversion device according to claim 2 , wherein
the capacitor has such a capacitance that allows high-frequency voltage variation due to switching in the first converter to be smoothed but does not allow the pulsating DC voltage waveform to be smoothed.

8 . The power conversion device according to claim 3 , wherein
the capacitor has such a capacitance that allows high-frequency voltage variation due to switching in the first converter to be smoothed but does not allow the pulsating DC voltage waveform to be smoothed.

9 . The power conversion device according to claim 4 , wherein
the capacitor has such a capacitance that allows high-frequency voltage variation due to switching in the first converter to be smoothed but does not allow the pulsating DC voltage waveform to be smoothed.

Assignees

• Sumitomo Electric Industries

Inventors

• Ayai Naoki

Classifications

• H02M1/12

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02M2001/0083

  Electricity · mapped topic

• H02M7/5387 Primary

  in a bridge configuration · CPC title

• H02M1/0083

  Converters characterised by their input or output configuration · 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