Motor control device having life prediction unit of smoothing capacitor

Patent metadata

Field	Value
Publication number	US-9812947-B2
Application number	US-201615078078-A
Country	US
Kind code	B2
Filing date	Mar 23, 2016
Priority date	Apr 27, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A motor control device includes a converter that converts AC power into DC power, a smoothing capacitor provided in a DC link, an inverter that converts the DC power in the DC link into AC power for a motor, a capacitor capacity measurement unit that measures a capacity of the smoothing capacitor, a data record unit that records a plurality of pieces of data composed of a measurement value of the capacity of the smoothing capacitor and a date or both a date and time when the measurement has been performed, a deterioration characteristic calculation unit that calculates a deterioration characteristic line indicating a change of the capacity of the smoothing capacitor with respect to elapsed time, on the basis of the recorded data, and a life prediction unit that predicts a period when a life of the smoothing capacitor ends, on the basis of the deterioration characteristic line.

First claim

What is claimed is:

1. A motor control device comprising:
a converter that converts AC power supplied from a side of an AC power source into DC power;
a smoothing capacitor provided in a DC link on a DC side of the converter;
an inverter that performs mutual power conversion between the DC power in the DC link and AC power that is driving power or regenerative power of a motor;
a capacitor capacity measurement unit that measures a capacity of the smoothing capacitor, on the basis of the DC voltage applied to the smoothing capacitor at a point after an initial charging operation is complete;
a data record unit that records a plurality of pieces of data composed of a measurement value of the capacity of the smoothing capacitor measured by the capacitor capacity measurement unit and a date or both a date and time when the measurement has been performed;
a deterioration characteristic calculation unit that calculates a deterioration characteristic line indicating a change of the capacity of the smoothing capacitor with respect to elapsed time, on the basis of the plurality of pieces of data recorded in the data record unit; and
a life prediction unit that predicts a period when a life of the smoothing capacitor ends, on the basis of the deterioration characteristic line calculated by the deterioration characteristic calculation unit.

2. The motor control device according to claim 1 , wherein
the life prediction unit calculates a date or both a date and time when the deterioration characteristic line is a predetermined deterioration determination level or less, and determines the date or both the date and time as the period when the life of the smoothing capacitor ends.

3. The motor control device according to claim 2 , wherein
the deterioration characteristic calculation unit calculates the deterioration characteristic line as an n-th degree function expression, where n is a natural number, on the basis of the plurality of pieces of data recorded in the data record unit.

4. The motor control device according to claim 3 , wherein
the deterioration characteristic calculation unit calculates the deterioration characteristic line using the least square method, on the basis of the plurality of pieces of data recorded in the data record unit.

5. The motor control device according to claim 4 , wherein
the capacitor capacity measurement unit measures the capacity of the smoothing capacitor, on the basis of a DC voltage applied to the smoothing capacitor, and a current inputted to the converter or a current outputted from the converter.

Assignees

• Fanuc Corp

Inventors

• Yamamoto Kenta
• Okita Tadashi

Classifications

• G01R31/00

  Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere ({measuring superconductive properties G01R33/1238;} testing line transmission systems H04B3/46; testing or measuring semiconductors or solid state devices during manufacture {H10P74/00}) · CPC title

• H02M5/4585

  having a rectifier with controlled elements · CPC title

• G01R27/2605

  Measuring capacitance (capacitive sensors G01D5/24) · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02P27/06 Primary

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title