The invention relates to the real-time determination of the forces applied by waves incident upon the moving part (2) of a wave-energy system (1). The method according to the invention is based on the construction of a model of the radiation force applied to the moving part (2) and a model of the dynamics of the wave-energy system (1). The invention uses only measurements of the kinematics of the moving part (2) and the force applied by the conversion machine (3) to the moving part (2).

Provided is a power grid adjustment method based on a load of a variable frequency air conditioner. The method includes: establishing a mathematical simulation model of a virtual synchronous motor in a variable frequency air conditioner controller; establishing a virtual inertia control segment and a droop control segment of power grid adjustment according to the mathematical simulation model; obtaining a reference value of rotation speed variation of a compressor by the virtual inertia control segment; obtaining a reference value .sub.ref of rotational angular frequency of the compressor by the droop control segment; and inputting a sum of the reference value .sub.ref of rotational angular frequency of the compressor and the reference value of rotation speed variation of the compressor into a field-oriented controller (FOC) to control rotation of a motor.

Provided is a power grid adjustment method based on a load of a variable frequency air conditioner. The method includes: establishing a mathematical simulation model of a virtual synchronous motor in a variable frequency air conditioner controller; establishing a virtual inertia control segment and a droop control segment of power grid adjustment according to the mathematical simulation model; obtaining a reference value of rotation speed variation of a compressor by the virtual inertia control segment; obtaining a reference value .sub.ref of rotational angular frequency of the compressor by the droop control segment; and inputting a sum of the reference value .sub.ref of rotational angular frequency of the compressor and the reference value of rotation speed variation of the compressor into a field-oriented controller (FOC) to control rotation of a motor.

A motor control device includes output command calculation circuitry and inertial load value calculation circuitry. The output command calculation circuitry is configured to calculate a motor output command, based on a motor acceleration command and an inertial load value indicative of a magnitude of inertia of a load on a motor. The inertial load value calculation circuitry is configured to calculate an estimated inertial load value with an adaptive observer, based on the motor output command and a motor actual output to be output from the motor, and configured to calculate the inertial load value, based on the estimated inertial load value.

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 includes output command calculation circuitry and inertial load value calculation circuitry. The output command calculation circuitry is configured to calculate a motor output command, based on a motor acceleration command and an inertial load value indicative of a magnitude of inertia of a load on a motor. The inertial load value calculation circuitry is configured to calculate an estimated inertial load value with an adaptive observer, based on the motor output command and a motor actual output to be output from the motor, and configured to calculate the inertial load value, based on the estimated inertial load value.

The invention relates to the real-time determination of the forces applied by waves incident upon the moving part (2) of a wave-energy system (1). The method according to the invention is based on the construction of a model of the radiation force applied to the moving part (2) and a model of the dynamics of the wave-energy system (1). The invention uses only measurements of the kinematics of the moving part (2) and the force applied by the conversion machine (3) to the moving part (2).

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, and wherein the control unit (110) is arranged to electromagnetically brake the electric motor (130) in response to detecting a kickback condition.

A motor control system includes a control processing unit to generate a torque command based on a command signal for controlling a motor that drives a mechanical load, a detection signal output from a detector provided in the motor, and a control gain, and to control the motor based on the torque command, a parameter setting unit to perform parameter setting for setting a limit value of the torque command and the control gain, and an inertia estimating unit to estimate inertia of the motor based on the detection signal and the torque command. The inertia estimating unit estimates the inertia in a state where self-excited vibration occurs in the motor due to the parameter setting.

A method for operating a controller apparatus for controlling a drive apparatus having a load moment and a moment of inertia, includes determining an estimated load value of the load moment by a load moment estimator during a constant-running phase, when a drive speed of the drive apparatus is kept to a constant setpoint value by the controller apparatus, using a model to describe an association between the moment of inertia and the load moment and generating an estimated inertia value of the moment of inertia as a pilot control of the moment of inertia based on the model during the constant-running phase. Further disclosed are a controller apparatus and a drive apparatus designed to carry out the method.