Motor control device having life prediction unit of smoothing capacitor

{
  "publication_number": "US9812947B2",
  "country": "US",
  "kind": "B2",
  "title": "Motor control device having life prediction unit of smoothing capacitor",
  "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.",
  "claims": [
    "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."
  ],
  "description_excerpt": "1. Field of the Invention\n\nThe present invention relates to a motor control device that converts AC power supplied from a three-phase AC input side into DC power and outputs the DC power to a DC link, and then converts the DC power into AC power for driving a motor and supplies the AC power to the motor, and in particular, relates to a motor control device having a life prediction unit for predicting a life of a smoothing capacitor provided in a DC link.\n\n2. Description of the Related Art\n\nIn motor control devices that drive motors in working machines, industrial machines, forging press machines, injection molding machines, or various robots, AC power inputted from a side of an AC power source is converted into DC power by a converter, and then, the DC power is converted into AC power by an inverter, and the AC power is used as driving power of a motor.\n\nFIG. 4 is a diagram illustrating a configuration of a general motor control device. A motor control device 100 includes a converter 101 that converts AC power from a commercial three-phase AC power source (hereinafter, referred to as just “AC power source”) 103 into DC power and an inverter 102 that converts the DC power outputted from the converter 101 into AC power having a desired frequency, which is to be supplied as driving power of a motor 104, or converts AC power regenerated from the motor 104 into DC power, and controls the speed, the torque, or the position of a rotator of the motor 104 connected to an AC side of the inverter 102. The converter 101 and the inverter 102 are connected via a DC link.",
  "cpc": [
    "H02M 1/32",
    "G01R 27/2605",
    "G01R 31/00",
    "H02M 5/4585",
    "H02P 27/06"
  ],
  "ipc": [
    "H02P 27/06",
    "G01R 23/09",
    "G01R 31/00",
    "H02M 1/32"
  ],
  "assignees": [
    "Fanuc Corp"
  ],
  "inventors": [
    "Kenta Yamamoto",
    "Tadashi Okita"
  ],
  "filing_date": "2016-03-23",
  "publication_date": "2017-11-07",
  "grant_date": "2017-11-07",
  "priority_date": "2015-04-27",
  "application_number": "US-201615078078-A",
  "family_id": "57110629",
  "cited_by_count": 4,
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}