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Method and system for controlling an electric motor with compensation for time delay in position determination

  • US 8,723,460 B2
  • Filed: 06/27/2011
  • Issued: 05/13/2014
  • Est. Priority Date: 02/23/2011
  • Status: Active Grant
First Claim
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1. A method for controlling a motor, the method comprising:

  • detecting, by a sensor, position data for a rotor of the motor at a first time;

    receiving, by a data processor, the detected position data associated with a first time delay;

    sensing, by a sensing circuit, an analog phase current at the motor by operating during a second time delay;

    converting, by an analog-to-digital converter, the analog current to a digital current data during a third time delay;

    detecting a fourth time delay between an actual current reading instant and a position reading instant in a data processor;

    transforming the digital current data into measured direct and quadrature axes control current data based on synchronization or temporal alignment of the position data with the actual measured analog current at the starting time by compensating the position data by a sum of the second time delay, the third time delay and the fourth time delay, where the first time delay is subtracted from the sum, wherein the first time delay comprises a time period associated with transmission of a sensor signal from the sensor and receipt of the sensor signal at the data processor;

    the second time delay comprises a time period when the sensing circuit senses an analog control current at motor windings of the motor via the sensor signal;

    the third time delay comprises a time period associated with the analog-to-digital conversion and storage process in the analog-to-digital converter; and

    the fourth time delay comprises a time period or offset from a phase current reading to a position data reading and determination in the data processor.

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