A virtual voltage injection-based speed sensor-less driving control method for an induction motor is provided. First, a virtual voltage signal is injected into a motor flux linkage and rotating speed observer so that there is a difference between an input of the motor flux linkage and rotating speed observer and a command input of the motor. Then, based on any type of the motor flux linkage and rotating speed observer, a motor flux linkage rotation angle and a motor rotor speed are estimated, and the induction motor is driven to run normally with a certain control strategy (such as vector control). Then, based on a signal designed according to this method and injected only into the motor flux linkage and rotating speed observer, the induction motor driven by a speed sensor-less control system for the induction motor may be ensured to output 150% of a rated torque when running at a motor low synchronous rotating speed and a motor zero synchronous rotating speed, and the stability thereof may be kept for a long time.

A virtual voltage injection-based speed sensor-less driving control method for an induction motor is provided. First, a virtual voltage signal is injected into a motor flux linkage and rotating speed observer so that there is a difference between an input of the motor flux linkage and rotating speed observer and a command input of the motor. Then, based on any type of the motor flux linkage and rotating speed observer, a motor flux linkage rotation angle and a motor rotor speed are estimated, and the induction motor is driven to run normally with a certain control strategy (such as vector control). Then, based on a signal designed according to this method and injected only into the motor flux linkage and rotating speed observer, the induction motor driven by a speed sensor-less control system for the induction motor may be ensured to output 150% of a rated torque when running at a motor low synchronous rotating speed and a motor zero synchronous rotating speed, and the stability thereof may be kept for a long time.

A control device and a control method for an induction motor. The control device comprises: a magnetizing current adjusting unit used for calculating a magnetizing voltage instruction; a torque current adjusting unit used for calculating a torque voltage instruction; a flux linkage instruction angle generating unit calculating a flux linkage instruction angle according to a lower limit ω.sub.1th of a preset stator frequency, a stator frequency ω.sub.1, and a flux linkage estimation angle; and a motor stator voltage instruction calculating unit calculating, according to the magnetizing voltage instruction, the torque voltage instruction, and the flux linkage instruction angle, a stator voltage instruction for controlling a stator of the motor. The control system can be run outside an unstable area, and the stability of control by the control device is improved.

A method and a device for assigning the inductance or admittance to the rotor position of a synchronous machine having a stator and a rotor with or without permanent magnets. In operation, the synchronous machine is activated by way of timed terminal voltages and the inductance or admittance is calculated from the terminal voltages and the measured current response. In this case, the variation of the inductance or admittance over the rotor rotation under the boundary condition of an at least two-dimensional current vector that is unchanged in stator coordinates, is used as key information for the positional assignment.

A system for controlling a motor may include an alternating current (AC) bus configured to transmit an AC power signal to a set of stator windings, where the AC power signal produces a first rotating magnetic flux at the set of stator windings. The system may also include a high frequency contactless transformer configured to transmit an excitation signal to a set of rotor windings, where the excitation signal produces a second rotating magnetic flux at the rotor. The system may also include electrical circuitry configured to determine a rotor voltage and a rotor current associated with the excitation signal, determine a rotor flux magnitude estimate and a rotor flux angle estimate based on the rotor voltage and the rotor current, and determine an inverter control signal operable to generate the excitation signal based at least partially on the rotor flux magnitude estimate and the rotor flux angle estimate.

A system for controlling a motor may include an alternating current (AC) bus configured to transmit an AC power signal to a set of stator windings, where the AC power signal produces a first rotating magnetic flux at the set of stator windings. The system may also include a high frequency contactless transformer configured to transmit an excitation signal to a set of rotor windings, where the excitation signal produces a second rotating magnetic flux at the rotor. The system may also include electrical circuitry configured to determine a rotor voltage and a rotor current associated with the excitation signal, determine a rotor flux magnitude estimate and a rotor flux angle estimate based on the rotor voltage and the rotor current, and determine an inverter control signal operable to generate the excitation signal based at least partially on the rotor flux magnitude estimate and the rotor flux angle estimate.

A virtual voltage injection-based speed sensor-less driving control method for an induction motor is provided. First, a virtual voltage signal is injected into a motor flux linkage and rotating speed observer so that there is a difference between an input of the motor flux linkage and rotating speed observer and a command input of the motor. Then, based on any type of the motor flux linkage and rotating speed observer, a motor flux linkage rotation angle and a motor rotor speed are estimated, and the induction motor is driven to run normally with a certain control strategy (such as vector control). Then, based on a signal designed according to this method and injected only into the motor flux linkage and rotating speed observer, the induction motor driven by a speed sensor-less control system for the induction motor may be ensured to output 150% of a rated torque when running at a motor low synchronous rotating speed and a motor zero synchronous rotating speed, and the stability thereof may be kept for a long time.

A virtual voltage injection-based speed sensor-less driving control method for an induction motor is provided. First, a virtual voltage signal is injected into a motor flux linkage and rotating speed observer so that there is a difference between an input of the motor flux linkage and rotating speed observer and a command input of the motor. Then, based on any type of the motor flux linkage and rotating speed observer, a motor flux linkage rotation angle and a motor rotor speed are estimated, and the induction motor is driven to run normally with a certain control strategy (such as vector control). Then, based on a signal designed according to this method and injected only into the motor flux linkage and rotating speed observer, the induction motor driven by a speed sensor-less control system for the induction motor may be ensured to output 150% of a rated torque when running at a motor low synchronous rotating speed and a motor zero synchronous rotating speed, and the stability thereof may be kept for a long time.

A motor controller includes: a rotation speed estimating unit that estimates a rotation speed of a motor based on current information and primary frequency information of the motor; a proximity switch that outputs an ON signal when a portion of a rotating body of the motor is in proximity and that outputs an OFF signal when a portion of the rotating body of the motor is not in proximity; a rotation speed calculating unit that calculates a rotation speed of the motor based on the ON signal and the OFF signal output from the proximity switch; a speed command compensating unit that compensates a speed command value such that an error between the speed command value and a rotation speed calculation value becomes smaller; and a speed control system that perform the speed control on the motor based on the compensated speed command value and the rotation speed estimation value.

A control circuit of a motor control device estimates an initial magnetic pole position of a rotor using an inductive sensing scheme. When estimating the initial magnetic pole position, a drive circuit applies a voltage to a stator winding at each of L electrical angles (L5) while changing the L electrical angles. An absolute value of an electrical angle difference of the voltage applied to the stator winding between an i-th time (2iL) and an i1st time is 180360/L degrees or more and 180+360/L degrees or less. An absolute value of an electrical angle difference of the voltage applied to the stator winding between a 1st time for initial position estimation and a last time before starting initial position estimation is 180360/L degrees or more and 180+360/L degrees or less.