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Frequency converter device which adaptively responds to a power failure

  • US 5,705,904 A
  • Filed: 10/25/1996
  • Issued: 01/06/1998
  • Est. Priority Date: 03/28/1996
  • Status: Expired due to Term
First Claim
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1. A frequency converter device, comprising:

  • a first converter in a pulse-width modulation system for converting an AC voltage into a DC voltage;

    a second converter in a pulse-width modulation system for supplying an AC voltage with a variable voltage and a variable frequency to a motor;

    a capacitor connected between an output side of said first converter and an input side of said second converter;

    a current suppressing circuit connected to the input side of said first converter and consisting of a resistor and a short-circuiting means;

    a detection circuit for detecting the presence or absence of a power supply inputted to said first converter;

    a circuit for measuring the voltage across said capacitor;

    a drive control circuit for stopping the conversion of said first converter when power failure of the input power supply occurs and when the voltage across the capacitor is not smaller than a prescribed value, continuing the drive state of the short-circuiting means in said current suppressing circuit and said second converter, thereby continuing an output.

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