Abstract: According to an aspect, there is provided an apparatus for a drive for driving an induction motor. The apparatus comprising means for performing the following. The apparatus obtains a stator current vector of the induction motor and estimates, using a state observer for the stator and/or rotor flux linkage vector of the induction motor, the stator and/or rotor flux linkage vector based on the stator current vector, a voltage reference vector and a stator angular frequency reference. The state observer is a speed-sensorless reduced-order state observer based on a mathematical model of the induction motor. The apparatus performs speed-sensorless state-feedback control based on the estimated stator and/or rotor flux linkage vector, the stator current vector, a stator flux linkage reference vector and the stator angular frequency reference for calculating the stator voltage reference vector. The apparatus applies the stator voltage reference vector to an inverter of the drive.

Abstract: According to an aspect, there is provided an apparatus for a drive for driving a synchronous motor. The apparatus includes means for performing the following. The apparatus obtains a stator current vector and estimates, using a state observer, a stator flux linkage vector based on the stator current vector, a voltage reference vector, a stator angular frequency reference and a control-rotor rotation angle estimated by the state observer and being defined as an angle between control and rotor coordinates. The state observer is a speed-sensorless back-electromotive-force-based state observer defined in the control coordinates and based on a mathematical model for the synchronous motor. The apparatus performs speed-sensorless state-feedback control based on the estimated stator flux linkage vector, the stator current vector, a stator flux linkage reference vector and the stator angular frequency reference for calculating the stator voltage reference vector.

Abstract: A method and apparatus for self-commissioning a bearingless-motor drive, which includes a bearingless motor and a control unit of the bearingless motor are disclosed. The motor includes at least one winding and at least one permanent magnet. The method includes generating a magnetic model, the magnetic model including a plurality of constant parameters; supplying, while the movable part remains standstill, to the at least one winding at least two unequal currents; measuring, with a magnetic sensor, flux linkages caused by said at least two unequal currents, respectively; calculating, with the magnetic model, flux linkages by inputting to the magnetic model current values equal to the currents supplied to the at least one winding; and fitting, with a least-squares fitting algorithm, at least one constant parameter in the magnetic model such that the difference between the measured and calculated flux linkages will be minimized.

Abstract: The invention refers to an electric linear motor comprising a longitudinal stator beam; at least one mover adapted to move along the stator beam; which stator beam comprises at least two side faces located at opposite sides of the stator beam, each of the side faces carrying ferromagnetic poles spaced apart by a pitch, and which mover comprises at least two counter-faces facing the respective side faces of the stator beam, wherein the at least two side faces, as well as the at least two counter-faces facing the respective side faces, are inclined or offset with respect to each other.

Abstract: The invention refers to an electric linear motor, control apparatus, transport system and a method. The electric linear motor comprises a longitudinal stator beam; at least one mover at least partially surrounding the stator beam and adapted to move along the stator beam; which stator beam comprises at least two side faces located at opposite sides of the stator beam, each of the side faces carrying ferromagnetic poles spaced apart by a pitch, and which mover comprises at least two counter-faces facing the respective side faces of the stator beam. The mover has in at least one of said counter-faces rotor units having at least one winding and at least one permanent magnet arranged to co-act with the ferromagnetic poles of the respective side faces of the stator beam.

Abstract: A method and apparatus for self-commissioning a bearingless-motor drive, which includes a bearingless motor and a control unit of the bearingless motor are disclosed. The motor includes at least one winding and at least one permanent magnet. The method includes generating a magnetic model, the magnetic model including a plurality of constant parameters; supplying, while the movable part remains standstill, to the at least one winding at least two unequal currents; measuring, with a magnetic sensor, flux linkages caused by said at least two unequal currents, respectively; calculating, with the magnetic model, flux linkages by inputting to the magnetic model current values equal to the currents supplied to the at least one winding; and fitting, with a least-squares fitting algorithm, at least one constant parameter in the magnetic model such that the difference between the measured and calculated flux linkages will be minimized.

Abstract: A method in connection with control of a grid connected converter and a converter. The control including forming a current reference for the converter, feeding the current reference to a current controller for producing a voltage reference for the converter. The method includes high-pass filtering the produced voltage reference or measured output voltage of the converter and modifying the current reference with the high-pass filtered voltage reference or measured output voltage of the converter.

Abstract: The invention refers to an electric linear motor, control apparatus, transport system and a method. The electric linear motor comprises a longitudinal stator beam; at least one mover at least partially surrounding the stator beam and adapted to move along the stator beam; which stator beam comprises at least two side faces located at opposite sides of the stator beam, each of the side faces carrying ferromagnetic poles spaced apart by a pitch, and which mover comprises at least two counter-faces facing the respective side faces of the stator beam. The mover has in at least one of said counter-faces rotor units having at least one winding and at least one permanent magnet arranged to co-act with the ferromagnetic poles of the respective side faces of the stator beam.

Abstract: A method for determining output currents of a three-phase frequency converter comprising a voltage intermediate circuit and three power switch pairs constituting an output of the frequency converter, wherein the power switches constituting a pair are coupled in series between a positive and a negative busbar of the voltage intermediate circuit so that a midpoint of each switch pair constitutes a phase output of the frequency converter.

Abstract: A method for the stabilization of full-order flux observers for speed-sensorless induction motors in the regenerative mode. The method comprises determining the current vector of the induction motor, determining the stator voltage vector of the induction motor, forming a full-order flux observer having a system matrix (A) and a gain matrix (L), the state-variable observer being augmented with a speed adaptation loop, and producing an estimated rotor flux linkage vector and an estimated stator current vector, determining an estimation error of the stator current vector, defining a correction angle, and forming a speed adapt-tion law based on the cross product of the estimation error of the stator current vector and the estimated rotor flux linkage vector, where the correction angle is used to turn the rotor flux linkage vector or the estimation error of the stator current vector in order to keep the observer stable.

Abstract: A method for determining output currents of a three-phase frequency converter comprising a voltage intermediate circuit and three power switch pairs constituting an output of the frequency converter, wherein the power switches constituting a pair are coupled in series between a positive and a negative busbar of the voltage intermediate circuit so that a midpoint of each switch pair constitutes a phase output of the frequency converter.

Abstract: A method for the stabilization of full-order flux observers for speed-sensorless induction motors in the regenerative mode. The method comprises determining the current vector of the induction motor, determining the stator voltage vector of the induction motor, forming a full-order flux observer having a system matrix (A) and a gain matrix (L), the state-variable observer being augmented with a speed adaptation loop, and producing an estimated rotor flux linkage vector and an estimated stator current vector, determining an estimation error of the stator current vector, defining a correction angle, and forming a speed adapt-tion law based on the cross product of the estimation error of the stator current vector and the estimated rotor flux linkage vector, where the correction angle is used to turn the rotor flux linkage vector or the estimation error of the stator current vector in order to keep the observer stable.