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Energy saving system and method for devices with rotating or reciprocating masses

  • US 9,716,449 B2
  • Filed: 04/01/2014
  • Issued: 07/25/2017
  • Est. Priority Date: 09/14/2007
  • Status: Expired due to Fees
First Claim
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1. A method of saving energy for an electric motor coupled to a rotating mass, the method comprising:

  • detecting a line voltage and a current supplied to the electric motor;

    observing a phase angle between the line voltage and the current;

    comparing the observed phase angle with a target phase angle;

    switching-off the line voltage to the electric motor when the observed phase angle is greater than the target phase angle;

    monitoring a motor voltage generated at the electric motor while the line voltage is switched off;

    determining a period of the voltage generated at the electric motor;

    determining a period of the line voltage;

    determining a line zero crossing point corresponding to the line voltage;

    determining a motor zero crossing point corresponding to the voltage generated at the electric motor; and

    switching-on the line voltage to the electric motor when;

    the period of the voltage generated at the electric motor is substantially equal to the period of the line voltage; and

    the line zero crossing point substantially matches the motor zero crossing point.

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