An electric machine assembly includes an electric machine having a stator and a rotor. The stator has stator windings at a stator winding temperature (t.sub.S) and the rotor is configured to rotate at a rotor speed (). A controller is operatively connected to the electric machine and has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for determining stator winding resistance. The controller is configured to determine a high-speed resistance factor (r.sub.H) which is based at least partially on the torque command (T*), the stator winding temperature (t.sub.S), the rotor speed (), a characterized torque error and the number of pole pairs (P). The controller may determine a total resistance value (R) based on a weighting factor (k), the high-speed resistance factor (r.sub.H) and the low-speed resistance factor (r.sub.L).

By providing a configuration for calculating motor control constants to be set in a motor control apparatus automatically on the basis of a target response time constant obtained from a target response time constant input unit, waveform parameters obtained from a waveform parameter input unit, a normalized time constant obtained from a normalized time constant calculation unit, and a motor load inertia obtained from a motor load inertia input unit, it is possible to obtain a motor control constant calculation device that can determine appropriate motor control constants for obtaining a desired response characteristic by automatic calculation while avoiding variation and an increase in the number of steps due to differences in the abilities of users.

A control device for an AC rotating machine includes: a current detection unit; a command generation unit for generating a voltage command, using a moment of inertia J; a speed estimation unit for calculating an estimated speed 0 on the basis of the voltage command and detected current; an output torque computing unit for calculating output torque on the basis of the detected current; and an inertia moment computing unit for calculating the moment of inertia J. The output torque computing unit gives a delay characteristic corresponding to an estimation delay of the estimated speed 0, to the output torque, and the inertia moment computing unit calculates the moment of inertia J on the basis of the estimated speed 0 and the output torque having the delay characteristic.

A motor control device that controls a machine comprising an identification part estimating moment of inertia and viscous friction, a speed command generation part generating a speed command obtained by integrating an acceleration command, a difference signal calculation part calculating a difference signal from the acceleration command with time difference, and an identification interval judgment part determining a valid interval for operate the identification part based on the difference signal, and operating the identification part in the valid interval and driving the motor based on the speed command generated by the speed command generating part, wherein the identification part estimates the moment of inertia and the viscous friction.

A method for estimating operation parameters of a servomotor is described. The method includes the steps of: driving the servomotor to rotate stably at an initial angular velocity; computing d- and q-axis components of an initial voltage when the servomotor rotates at the initial angular velocity; accelerating the servomotor to a predetermined angular velocity according to the initial voltage; and computing at least one operation parameter of the servomotor after the servomotor rotates at the predetermined angular velocity.

Provided is a motor control device, including an acceleration command calculation unit configured to calculate an acceleration command directed to a motor, a torque command calculation unit configured to calculate a torque command directed to the motor based on the acceleration command and a predetermined moment-of-inertia value, a torque correction value calculation unit configured to estimate disturbance of the motor based on the torque command and at least one of a motor position or a motor speed, to thereby calculate a torque correction value for the torque command, and a moment-of-inertia value change unit configured to change the predetermined moment-of-inertia value based on an estimated moment-of-inertia ratio, which is a ratio of the torque correction value to the torque command.

A hand-held electrically powered cut-off tool (100) for cutting concrete and stone by a rotatable cutting disc (105), the cut-off tool (100) comprising an electric motor (130) arranged to be controlled by a control unit (110) via a motor control interface (120), wherein the control unit (110) is arranged to obtain data indicative of an angular velocity of the cutting disc (105), and to detect a kickback condition based on a decrease in angular velocity, wherein the control unit (110) is arranged to control an electromagnetic braking of the electric motor (130) in response to detecting a kickback condition, wherein the control unit (110) is arranged to determine an angular acceleration associated with the electric motor (130), and to detect the kickback condition based on a comparison between the determined angular acceleration and a configurable detection threshold.