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Laundering apparatus, method of operating a laundry machine, control system for an electronically commutated motor, method of operating an electronically commutated motor, and circuit

  • US 4,390,826 A
  • Filed: 04/17/1980
  • Issued: 06/28/1983
  • Est. Priority Date: 06/24/1974
  • Status: Expired due to Term
First Claim
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1. A circuit for controlling the energization of an electrical load from an AC source comprising:

  • a pair of DC lines;

    means for rectifying the AC output of the source to apply a DC voltage across said DC lines in the form of a full wave rectified sinusoidal signal;

    means connected between said DC lines and the load for chopping the full wave rectified sinusoidal signal to provide pulses at a frequency which is high with respect to the frequency of the full wave rectified sinusoidal signal;

    means responsive to an externally derived signal representative of the desired energization of the load for modulating the width of the pulses;

    means responsive to current in said DC lines for modifying the externally derived signal to maintain the amplitude of the DC line current below a predetermined level;

    means for detecting zero crossovers of the full wave rectified sinusoidal signal; and

    means responsive to said detecting means for applying the pulses only during a predetermined time interval in each half cycle of the full wave rectified sinusoidal signal, the initiating and terminating points of each of the time intervals being spaced substantially equal phase angles away from the initiating and terminating zero crossovers that define the corresponding half cycle of the full wave rectified sinusoidal signal, respectively;

    whereby the load presents a high power factor to the AC source.

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