Power conversion device

Patent metadata

Field	Value
Publication number	US-12308763-B2
Application number	US-201917774990-A
Country	US
Kind code	B2
Filing date	Dec 2, 2019
Priority date	Dec 2, 2019
Publication date	May 20, 2025
Grant date	May 20, 2025

Abstract

A voltage evaluation value generator receives voltage detection values of power storage elements of all of converter cells included in a power converter and generates a first voltage evaluation value of each power storage element of all of the converter cells and a second voltage evaluation value of each power storage element in a plurality of converter cells included in each of a plurality of groups obtained by classifying all of the converter cells in advance, without using a mean value of voltage detection values. A voltage macro controller uses the voltage evaluation value to calculate a control value set in common to at least the converter cells in the same group for controlling deficiency and excess of stored energy in all of the converter cells and the converter cells in each group.

First claim

The invention claimed is:

1. A power conversion device comprising:
a power converter including at least one leg circuit including arms each having multiple converter cells cascaded to each other;
a current detector arranged for each arm; and
a control device to control the power converter,
each of the converter cells including
a pair of input and output terminals,
a plurality of switching elements,
a power storage element electrically connected to the input and output terminals through the switching elements, and
a voltage detector to detect a voltage of the power storage element,

the control device including
a voltage macro controller to control at least one of: deficiency and excess of stored energy of the power storage elements by all of the converter cells that constitute the power converter; and deficiency and excess of stored energy of the power storage elements by a plurality of converter cells included in each of a plurality of groups obtained by classifying the all of the converter cells in advance, and
a voltage evaluation value generator to calculate at least one of: a voltage evaluation value of each power storage element different from a mean value of respective voltage detection values of the power storage elements, for the all of the converter cells; and a voltage evaluation value of the each power storage element different from a mean value of respective voltage detection values of the power storage elements, for the plurality of converter cells in each of the groups,

wherein the voltage macro controller calculates a circulating current command value set in common to at least the plurality of converter cells for controlling deficiency and excess of the stored energy, based on the voltage evaluation value from the voltage evaluation value generator, and wherein
the control device further includes:
a circulating current calculator to calculate a circulating current value of the leg circuit by using arm current detected by the current detector; and
a circulating current controller to generate a circulating control command value for perform control such that the circulating current value follows the circulating current command value, and

the circulating control command value is reflected in an AC voltage command value set for each arm, and
in each of the converter cells, ON and OFF of the switching elements is controlled in accordance with the AC voltage command.

2. The power conversion device according to claim 1 , wherein
the voltage evaluation value generator includes an evaluation value calculator to calculate at least the voltage evaluation value for each of the groups,
the evaluation value calculator includes
a maximum value extractor to receive a plurality of voltage detection values by the voltage detectors of the plurality of converter cells included in a same group among the groups and extract a maximum value of the voltage detection values, and

the voltage evaluation value generator outputs the maximum value extracted by the maximum value extractor as the voltage evaluation value to the voltage macro controller.

3. The power conversion device according to claim 2 , wherein
the voltage evaluation value generator includes
an abnormal value eliminator to receive the voltage detection values and eliminate an abnormal value from the voltage detection values, and

the voltage detection values processed by the abnormal value eliminator are input to the evaluation value calculator.

4. The power conversion device according to claim 2 , wherein
the voltage evaluation value generator further includes
a filter to allow an output value of the evaluation value calculator to pass through,

the filter has a characteristic of averaging the output value, and
the voltage evaluation value generator outputs an output value of the filter as the voltage evaluation value to the voltage macro controller.

5. The power conversion device according to claim 1 , wherein
the voltage evaluation value generator includes an evaluation value calculator to calculate at least the voltage evaluation value for each of the groups,
the evaluation value calculator includes
a minimum value extractor to receive a plurality of voltage detection values by the voltage detectors of the plurality of converter cells included in a same group among the groups and extract a minimum value of the voltage detection values, and

the voltage evaluation value generator outputs the minimum value extracted by the minimum value extractor as the voltage evaluation value to the voltage macro controller.

6. The power conversion device according to claim 1 , wherein
the voltage evaluation value generator includes an evaluation value calculator to calculate at least the voltage evaluation value for each of the groups,
the evaluation value calculator includes
a maximum value extractor to receive a plurality of voltage detection values by the voltage detectors of the plurality of converter cells included in a same group among the groups and extract a maximum value of the voltage detection values,
a minimum value extractor to receive the voltage detection values in common to the maximum value extractor and extract a minimum value of the voltage detection values, and
a mean value calculator to calculate a mean value of the maximum value extracted by the maximum value extractor and the minimum value extracted by the minimum value extractor, and

the voltage evaluation value generator outputs the mean value calculated by the mean value calculator as the voltage evaluation value to the voltage macro controller.

7. The power conversion device according to claim 1 , wherein
the voltage evaluation value generator includes an evaluation value calculator to calculate at least the voltage evaluation value for each of the groups,
the evaluation value calculator includes
a mode extractor to receive a plurality of voltage detection values by the voltage detectors of the plurality of converter cells included in a same group among the groups and extract a mode of the voltage detection values, and

the voltage evaluation value generator outputs the mode extracted by the mode extractor as the voltage evaluation value to the voltage macro controller.

8. The power conversion device according to claim 1 , wherein
the voltage evaluation value generator includes an evaluation value calculator to calculate at least the voltage evaluation value for each of the groups,
the evaluation value calculator includes
a representative value extractor to receive a plurality of voltage detection values by the voltage detectors of the plurality of converter cells included in a same group among the groups, and
a select switch to switch a select signal for selecting one of the voltage detection values in accordance with a random number generated in certain cycles or a count value counted up in certain cycles,

the representative value extractor extracts one voltage detection value of the voltage detection values as a representative value in accordance with the select signal from the select switch, and
the voltage evaluation value generator outputs the representative value extracted by the representative value extractor as the voltage evaluation value to the voltage macro controller.

9. The power conversion device according to claim 1 ,
wherein
in each of the converter cells, ON and OFF of the switching elements is controlled in accordance with pulse width modulation control based on comparison between the AC voltage command value set for each the arm and a periodical carrier signal,
the voltage evaluation value generator includes an evaluation value calculator to calculate the voltage evaluation value for each of the groups,
the group corres

Assignees

• Mitsubishi Electric Corp

Inventors

• Fujiwara Shuhei
• Kono Yoshiyuki
• Uda Ryosuke
• KAJIYAMA Takuya
• Fujii Toshiyuki
• Hayashi Shigeo

Classifications

• H02M7/4835 Primary

  comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage · CPC title

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title

• H02M1/0006

  Arrangements for supplying an adequate voltage to the control circuit of converters · 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

• H02M1/0043

  Converters switched with a phase shift, i.e. interleaved (non-isolated DC/DC converters H02M3/1586) · CPC title