Estimation of actual torque in an electrical motor drive
AssigneeDanaher Motion Stockholm AB
InventorPer Rickard Johansson
Life of this patent
Estimating the term…
Abstract
It is presented a control device for driving an electric motor, wherein a drive control signal for the electric motor is arranged to be determined using a calculated rotor flux. A direct quadrature, dq, coordinate system relating to a rotor of the electric motor is used. The control device comprises a flux estimator arranged to determine the calculated rotor flux using a quadrature axis voltage, a measured direct axis current, a measured quadrature axis current, an angular velocity, stator resistance and a direct axis inductance and an actual torque calculator arranged to obtain an actual torque estimation using the calculated rotor flux, the measured direct axis current and the measured quadrature axis current. A corresponding method is also presented.
Claims7
A control device for driving an electric motor, wherein a drive control signal for the electric motor is arranged to be determined using a calculated rotor flux, wherein a direct quadrature (dq) coordinate system relates to a rotor of the electric motor, wherein the control device comprises:
- a flux estimator arranged to determine the calculated rotor flux using a quadrature axis voltage, a measured direct axis current, a measured quadrature axis current, an angular velocity, stator resistance and a direct axis inductance,
- an actual torque calculator arranged to obtain an actual torque estimation using the calculated rotor flux, the measured direct axis current and the measured quadrature axis current, the direct axis inductance and a quadrature axis inductance,
- a controller arranged to control the motor based on the actual torque estimation, and
- a reference torque calculator arranged to obtain an adjusted reference torque using the calculated rotor flux, a reference direct axis current and a reference quadrature axis current, wherein the adjusted reference torque is fed back to a reference torque adjuster to obtain improved correspondence between the actual torque estimation and an input torque to the control device.
A method for controlling an electric motor performed in a control device, wherein a direct quadrature (dq) coordinate system relates to a rotor of the electric motor, the method comprising the steps of:
- determining the calculated rotor flux using a quadrature axis voltage, a measured direct axis current, a measured quadrature axis current, an angular velocity, stator resistance and a direct axis inductance,
- obtaining, in an actual torque calculator, an actual torque estimation using the calculated rotor flux, the measured direct axis current, the measured quadrature axis current, the direct axis inductance and a quadrature axis inductance,
- controlling the motor based on the actual torque estimation, and
- obtaining, in a reference torque calculator, an adjusted reference torque using the calculated rotor flux, a reference direct axis current and a reference quadrature axis current, wherein the adjusted reference torque is fed back to a reference torque adjuster to obtain improved correspondence between the actual torque estimation and an input torque to the control device.
Dependencies are inferred from the claim text.