A method of determining an offset between an angular position indicated by a rotary position sensor assembly secured directly or indirectly to the rotor of a multi-phase permanent magnet AC motor and an actual electrical position of the motor rotor, includes the steps of: applying a voltage vector to the motor, which is aligned with a known angular position of the motor; waiting for the motor rotor to move to a location in which the vector when considered in the dq frame of reference is centered on the d-axis; measuring the angular position of the rotor indicated by the position sensor, and determining the offset from the difference between the measured angular position and the known actual position of the vector.

Provided is a method of controlling a sensorless motor for an air compressor. The method controls early driving of a sensorless motor for an air compressor, overcomes related-art problems, and improves control response. A position of a rotor of the motor, finally estimated by a sensorless control logic at a point in time at which the motor is determined to be in the stopped state, is determined to be an alignment target position. An alignment start position is determined from the alignment target position in accordance with a predetermined alignment offset angle. The position of the rotor of the motor is controlled to change from the determined alignment start position to the alignment target position.

Provides are a control device for a three-phase synchronous motor in which a position detection accuracy of a rotor can be improved when one three-phase synchronous motor is driven by a plurality of inverters, and an electric power steering device using the same. A control device for a three-phase synchronous motor includes: a three-phase synchronous motor including a first three-phase winding and a second three-phase winding; a first inverter connected to the first three-phase winding; a second inverter connected to the second three-phase winding; a first control device that controls the first inverter on the basis of a rotor position of the three-phase synchronous motor; and a second control device that controls the second inverter on the basis of the rotor position of the three-phase synchronous motor. The first control device estimates the rotor position on a basis of a neutral point potential of the first three-phase winding and a neutral point potential of the second three-phase winding.

Provides are a control device for a three-phase synchronous motor in which a position detection accuracy of a rotor can be improved when one three-phase synchronous motor is driven by a plurality of inverters, and an electric power steering device using the same. A control device for a three-phase synchronous motor includes: a three-phase synchronous motor including a first three-phase winding and a second three-phase winding; a first inverter connected to the first three-phase winding; a second inverter connected to the second three-phase winding; a first control device that controls the first inverter on the basis of a rotor position of the three-phase synchronous motor; and a second control device that controls the second inverter on the basis of the rotor position of the three-phase synchronous motor. The first control device estimates the rotor position on a basis of a neutral point potential of the first three-phase winding and a neutral point potential of the second three-phase winding.

A device for estimating inductances of an electric machine having a salient-pole rotor is presented. The device comprises a processing system that controls stator voltages to constitute a balanced multi-phase alternating voltage when the rotor is stationary. The processing system estimates a position of the rotor based on a negative sequence component of stator currents. To estimate the quadrature-axis inductance, the processing system controls direct-axis current to be direct current and quadrature-axis voltage to be alternating voltage. The quadrature-axis inductance is estimated based on the quadrature-axis alternating voltage and on quadrature-axis alternating current. To estimate the direct-axis inductance, the processing system controls direct-axis voltage to be alternating voltage and the quadrature-axis voltage to be zero. The direct-axis inductance is estimated based on the direct-axis alternating voltage and on direct-axis alternating current.

A low cost and efficient method and apparatus for calibrating high performance internal permanent magnet motors that involves starting from an initial estimation of the rotor position and improving the estimation incrementally by successively commanding various current vectors and making adjustments to the estimated initial position according to the rotor's physical reaction to such current vectors.

A motor controller includes current measurement circuitry and estimation circuitry. The current measurement circuitry is adapted to be coupled to a motor, and configured to measure current in the motor. The estimation circuitry is coupled to the current measurement circuitry, and includes a memory, current computation circuitry, and summation circuitry. The memory stores coefficients of a function for estimating current related to variation of inductance of the motor. The current computation circuitry is coupled to the memory, and is configured to compute a compensation current value based on the coefficients. The summation circuitry is coupled to the current compensation circuitry, and is configured to generate a position error signal by subtracting the compensation current value from a measured current value generated by the current measurement circuitry.

A motor controller includes current measurement circuitry and estimation circuitry. The current measurement circuitry is adapted to be coupled to a motor, and configured to measure current in the motor. The estimation circuitry is coupled to the current measurement circuitry, and includes a memory, current computation circuitry, and summation circuitry. The memory stores coefficients of a function for estimating current related to variation of inductance of the motor. The current computation circuitry is coupled to the memory, and is configured to compute a compensation current value based on the coefficients. The summation circuitry is coupled to the current compensation circuitry, and is configured to generate a position error signal by subtracting the compensation current value from a measured current value generated by the current measurement circuitry.

A method and apparatus are provided for controlling a sensorless multi-phase permanent magnet (PM) motor by sensing induced motor terminal voltages from the PM motor while the rotor is spinning, generating an input voltage vector signal from the plurality of induced motor terminal voltages, projecting the input voltage vector signal to a transformed voltage vector signal which does not include DC-offset components by using a Clarke transformation without a zero component that is applied to the input voltage vector signal, and estimating an initial rotor position of the rotor from the transformed voltage vector signal, wherein said sensing, projecting, and estimating are performed while a power converter for the sensorless multi-phase PM motor is disabled.

A method and apparatus are provided for controlling a sensorless multi-phase permanent magnet (PM) motor by sensing induced motor terminal voltages from the PM motor while the rotor is spinning, generating an input voltage vector signal from the plurality of induced motor terminal voltages, projecting the input voltage vector signal to a transformed voltage vector signal which does not include DC-offset components by using a Clarke transformation without a zero component that is applied to the input voltage vector signal, and estimating an initial rotor position of the rotor from the transformed voltage vector signal, wherein said sensing, projecting, and estimating are performed while a power converter for the sensorless multi-phase PM motor is disabled.