{
  "$type": "site.standard.document",
  "coverImage": {
    "$type": "blob",
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  "description": "There is provided a power conversion apparatus including a power converter being so configured that an alternating-current switch constituted of a series connection of two valve devices each constituted of a semiconductor element and a diode connected in inverse parallel with the semiconductor…",
  "path": "/patents/989131",
  "publishedAt": "2013-07-03T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "H02J3/381",
    "TOSHIBA MITSUBISHI ELEC INC [JP]"
  ],
  "textContent": "There is provided a power conversion apparatus including a power converter being so configured that an alternating-current switch constituted of a series connection of two valve devices each constituted of a semiconductor element and a diode connected in inverse parallel with the semiconductor element is connected between a connection point of the valve devices and a connection point of the direct-current power supplies in each arm, and each of the alternating-current switches is turned on or off, thereby enabling the power converter to perform three-level operation or two-level operation. The power conversion apparatus includes a comparison circuit (9) which compares a determination element related to a loss in the power converter with a switching reference value and outputs a determination instruction when a difference has occurred between the determination element and the switching reference value, a determination circuit (11) which determines whether the determination element is greater or less than the switching reference value when having received a determination instruction from the comparison circuit (9), and outputs a two-level operation switching instruction when the determination element is greater than or equal to the switching reference value, and a switching circuit (12) which, when having received a two-level operation switching instruction from the determination circuit (11), turns off the alternating-current switch and turns on the valve devices in the arm sequentially, thereby bringing the power converter into a two-level operation state.",
  "title": "ELECTRICITY CONVERSION DEVICE"
}