Power conversion device, rotating machine system, and diagnosis method

Patent metadata

Field	Value
Publication number	US-12061236-B2
Application number	US-201917417453-A
Country	US
Kind code	B2
Filing date	Nov 28, 2019
Priority date	Jan 10, 2019
Publication date	Aug 13, 2024
Grant date	Aug 13, 2024

Abstract

This power conversion device has: a current measurement unit for measuring phase current; a current vector calculation unit for calculating a current vector by performing 3-phase to 2-phase conversion on the phase current; an amount-to-be-analyzed calculation unit for calculating, on the basis of the current vector, an amount to be analyzed; and a feature amount waveform extraction unit for extracting a waveform in a specific frequency range on the basis of the amount to be analyzed.

First claim

The invention claimed is:

1. A power conversion device, comprising:
a current sensor configured to detect a phase current; and
a microcomputer configured to
measure the phase current;
calculate a current vector by performing 3-phase to 2-phase conversion on the phase current;
calculate an amount-to-be-analyzed, on the basis of the current vector, wherein the amount-to-be-analyzed is a current vector norm;
extract a waveform in a specific frequency range, on the basis of the amount-to-be-analyzed;
remove a direct current component of the amount-to-be-analyzed;
calculate a first abnormality degree after removing the direct current component;
remove a rotation frequency component of the amount-to-be-analyzed; and
calculate a second abnormality degree after removing the rotation frequency component.

2. The power conversion device according to claim 1 ,
wherein the power conversion device is connected to a rotating machine, and
the microcomputer is further configured to estimate a rotation frequency of the rotating machine.

3. The power conversion device according to claim 1 ,
wherein the specific frequency range is a frequency range between zero and a rotation frequency.

4. The power conversion device according to claim 1 ,
wherein the microcomputer performs sampling on the phase current at a frequency less than twice a rotation frequency.

5. The power conversion device according to claim 2 ,
wherein the microcomputer changes a frequency range to be extracted, on the basis of the estimated rotation frequency.

6. The power conversion device according to claim 1 ,
wherein the microcomputer sets the first abnormality degree by combining an absolute value or a square value of the waveform extracted for a given length of time.

7. The power conversion device according to claim 1 ,
wherein the microcomputer standardizes the first abnormality degree with an amplitude of a basic wave frequency component of the phase current or a direct current component extracted from the amount-to-be-analyzed.

8. The power conversion device according to claim 1 ,
wherein the microcomputer extracts the waveform in the specific frequency range by a filter selected from a highpass filter, a lowpass filter, and a bandpass filter.

9. The power conversion device according to claim 8 ,
wherein the microcomputer includes a notch filter attenuating a basic wave frequency component.

10. The power conversion device according to claim 1 , further comprising a calculator configured to determine the first abnormality degree and the second abnormality degree;
wherein the calculator is provided outside the power conversion device.

11. A diagnosis method of diagnosing a system provided with a power conversion device that includes a current sensor and a microcomputer, the method comprising:
detecting, by the current sensor, a phase current;
measuring, by the microcomputer, the phase current;
calculating, by the microcomputer, a current vector by performing 3-phase to 2-phase conversion on the phase current;
calculating, by the microcomputer, an amount-to-be-analyzed, on the basis of the current vector, wherein the amount-to-be-analyzed is a current vector norm;
extracting, by the microcomputer, a waveform in a specific frequency range, on the basis of the amount-to-be-analyzed;
removing a direct current component of the amount-to-be-analyzed;
calculating a first abnormality degree after removing the direct current component;
removing a rotation frequency component of the amount-to-be-analyzed; and
calculating a second abnormality degree after removing the rotation frequency component.

Assignees

• Hitachi Industry Equipment Systems Co Ltd

Inventors

• Maki Kohji
• Iwaji Yoshitaka
• Ohashi Hironori
• Nakamura Atsuhiko

Classifications

• H02H5/041

  additionally responsive to excess current (H02H5/048 takes precedence) · CPC title

• H02M1/0009 Primary

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

• H02P29/0241

  the fault being an overvoltage · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• H02P29/024

  Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load · CPC title