Phase current measurement diagnostic
AssigneeSteering Solutions IP Holding Corporation
InventorsSiddharth Ballal, Timothy A. Klinesmith, Dennis B. Skellenger
Life of this patent
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Abstract
A method of controlling a motor of a power steering system is provided. The method generates a direct-axis voltage command and a quadrature-axis voltage command based on a current measurement signal received from the motor. The method transforms the direct-axis voltage command and the quadrature-axis voltage command into an alpha voltage command and a beta voltage command. The method determines an offset error in the phase current measurement based on the alpha and beta voltage commands.
Claims18
A method of controlling a motor of a power steering system, the method comprising:
- generating a direct-axis voltage command and a quadrature-axis voltage command in a rotor reference frame based on a phase current measurement signal received from the motor;
- transforming the direct-axis voltage command and the quadrature-axis voltage command into an alpha voltage command and a beta voltage command in a stator reference frame;
- and
- determining an offset error in phase current measurement based on a voltage command in the stator reference frame, by:
- determining a delta alpha voltage command by computing a difference between an expected alpha voltage command and the alpha voltage command, the expected alpha voltage command being a predetermined alpha voltage command in case of no offset error in the current measurement;
- determining a delta beta voltage command by computing a difference between an expected beta voltage command and the beta voltage command, the expected beta voltage command being a predetermined beta voltage command in case of no offset error in the current measurement;
- and
- determining that the phase current measurement has the offset error in response to determining that either a magnitude of the delta alpha voltage command or a magnitude of the delta beta voltage command is greater than a threshold magnitude.
A motor control system, comprising:
- a motor;
- a motor current sensor for measuring motor current from the motor;
- a torque control module configure to:
- generate a direct-axis voltage command and a quadrature-axis voltage command in a rotor reference frame based on a phase current measurement signal received from the motor;
- transform the direct-axis voltage command and the quadrature-axis voltage command into an alpha voltage command and a beta voltage command in a stator reference frame;
- and
- determine an offset error in the phase current measurement based on the alpha and beta voltage commands, by:
- determining a delta alpha voltage command by computing a difference between an expected alpha voltage command and the alpha voltage command, the expected alpha voltage command being a predetermined alpha voltage command in case of no offset error in the current measurement;
- determining a delta beta voltage command by computing a difference between an expected beta voltage command and the beta voltage command, the expected beta voltage command being a predetermined beta voltage command in case of no offset error in the current measurement;
- and
- determining that the phase current measurement has the offset error in response to determining that either a magnitude of the delta alpha voltage command or a magnitude of the delta beta voltage command is greater than a threshold magnitude.
Dependencies are inferred from the claim text.