Title: Variable frequency power converter for ac motor drive

Abstract: In a variable frequency power converter of a current type for driving an AC motor including a rectifier, an inverter, and a smoothing reactor disposed on a DC transmission line between the rectifier and the inverter, there are provided a series circuit having a switching circuit and a smoothing capacitor on the DC input side of the inverter and a feedback circuit having controlled rectifier elements and commutation reactors for feeding back the reactive power of the AC motor. The power converter operates as a current type converter until the output frequency of the converter reaches a predetermined value under the condition that the switching circuit and the controlled rectifier elements are non-conductive, and operates as a voltage type converter when the output frequency has reached the predetermined value under the condition that the switching circuit and the controlled rectifier elements are conductive.

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Inventors: Maeda, Takeo (Hitachi, JA)

Application Number: 462534
Filing Date: 1974-04-19
Publication_date: 1976-02-17
Assignee: Hitachi, Ltd. (JA)
Primary Class(es): 318/805 363/37
Other Classes:
US Patent Ref:

3600658	Aug, 1971	Kuniyoshi	321/45.
3854078	Dec, 1974	Hubner	318/227.

Other Refs:
Primary Examiner: Shoop, William M.
Assistant Examiner:
Attorney: Craig & Antonelli