Determining rotor position in sensorless switched reluctance motors
AssigneeMelexis Technologies SA
InventorsSandro Purfuerst, Thomas Freitag, Veit Zöppig, Tom Ströhla
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Abstract
A method for determining the position of a moving rotor in a switched reluctance motor includes the steps of applying a voltage to a phase winding of the reluctance motor, sampling a signal representative of the current magnitude in this phase winding, detecting a feature of the second temporal derivative of the signal, and determining the position of the moving rotor taking into account the occurrence of this feature. Apparatus for carrying out the method is described.
Claims11
A device configured to determine the position of a moving rotor in a switched reluctance motor, comprising:
- a current sensor that samples a signal representative of the current magnitude in a phase winding of said switched reluctance motor while a voltage is applied to said phase winding,
- a feature detection unit that detects a feature of a second temporal derivative of said signal, and
- a processing unit that determines the position of the moving rotor taking into account an occurrence of said feature,
- wherein said occurrence of said feature corresponds to an unaligned or an aligned rotor position,
- wherein said feature detection unit comprises a zero-crossing detector arranged to detect said feature, said feature being a zero-crossing event of the second temporal derivative of said signal,
- wherein said determining of the position of the moving rotor comprises determining the sign of a third temporal derivative of said signal when the occurrence of said feature has been detected, wherein a positive sign of the third temporal derivative of said signal corresponds to an aligned rotor position, wherein said aligned rotor position corresponds to a position of minimum reluctance of the motor.
A method for determining the position of a moving rotor in a switched reluctance motor comprising:
- applying a voltage to a phase winding of the switched reluctance motor,
- sampling a signal representative of the current magnitude in said phase winding by using a current sensor,
- detecting a feature of a second temporal derivative of said signal by using a feature detection unit, wherein said feature comprises a zero crossing point of the second temporal derivative of said signal, and
- determining the position of the moving rotor taking into account an occurrence of said feature using a processing unit, wherein an occurrence of said feature corresponds to an unaligned or an aligned rotor position,
- wherein said determining of the position of the moving rotor comprises determining the sign of a third temporal derivative of said signal when the occurrence of said feature has been detected, wherein a positive sign of the third temporal derivative of said signal corresponds to an aligned rotor position, wherein said aligned rotor position corresponds to a position of minimum reluctance of the motor.
Dependencies are inferred from the claim text.