A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to apply a drive signal to the power switch circuit to control the supply of power to the brushless motor. The controller is configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor within a variable speed range of zero to at least 15,000 rotations-per-minute (RPM), and control the drive signal based on the detected angular position of the rotor to electronically commutate the motor within a power output of zero to at least 1500 watts.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. The controller detects an initial sector within which the rotor is located at start-up, apply the drive signal so as to rotate the motor to a parking angle associated with the detected initial sector, and control a commutation sequence to drive the motor beginning at the parking angle.

A system for the resilience of an electric submersible pumping system to a transient power interruption includes a power backup connected to the variable speed drive of the pumping system. A method for controlling the electric submersible pump during the transient power interruption includes connecting a variable speed drive to a power source, charging one or more rechargeable batteries within the power backup, and connecting the power backup to the variable speed drive. The method continues with the steps of operating the motor with the variable speed drive, detecting a disruption in AC power from the power source to the variable speed drive, and applying power from the power backup to the variable speed drive to operate the motor during the transient interruption in electrical power.

A motor control actuator configured to drive a permanent magnet synchronous motor (PMSM) with sensorless Field Oriented Control (FOC) includes: a sampling circuit configured to measure a counter electro motive force (CEMF) or a back electro motive force (BEMF) of the PMSM, while the PMSM rotates, and generate a measurement signal based on the measured CEMF or the measured BEMF; a motor controller including a current controller configured to generate control signals for driving the PMSM, the current controller configured to receive the measurement signal and perform a catch spin sequence for restarting the PMSM while rotating based on the measurement signal; and a multi-phase inverter configured to supply multiple phase voltages to the PMSM based on the control signals. The motor controller is configured to match an output voltage of the multi-phase inverter to the measured CEMF or the measured BEMF during the catch spin sequence.

A method is described for controlling an electric motor having a rotor. The method is carried out after a shutdown of the motor has been initiated. The method includes starting a timer in a motor controller, performing regenerative braking to recapture kinetic energy from the rotor as electrical energy, and using the recaptured electrical energy from the regenerative braking to power the motor controller. If the timer in the motor controller exceeds a predetermined timer value, a flag is set in memory in the motor controller to indicate that the motor has stopped.

A method is described for controlling an electric motor having a rotor. The method is carried out after a shutdown of the motor has been initiated. The method includes starting a timer in a motor controller, performing regenerative braking to recapture kinetic energy from the rotor as electrical energy, and using the recaptured electrical energy from the regenerative braking to power the motor controller. If the timer in the motor controller exceeds a predetermined timer value, a flag is set in memory in the motor controller to indicate that the motor has stopped.

A power tool includes a housing, a brushless motor disposed inside the housing, and a controller. The controller is configured to receive power-off signals and power-on signals. Upon receiving a power-on signal, the controller is further configured to receive a time signal indicative of a time interval from the last power-off signal to the current power-on signal. The controller is further configured to determine whether the time interval is greater than or equal to a first time threshold and less than a second time threshold, and brake the motor before start-up if the time interval is greater than or equal to the first time threshold and less than the second time threshold.

A device for estimating a rotation speed and/or a direction of rotation of an induction machine is presented. The device controls stator voltages (uu, uv, uw) of the induction machine so that a voltage space-vector constituted by the stator voltages has a fixed direction and a current space-vector constituted by stator currents (iu, iv, iw) of the induction machine has a pre-determined length or a predetermined d-component. The rotation speed and/or the direction of rotation is/are estimated based on a waveform of a q-component of the current space-vector, where the d-component of the current space-vector is parallel with the voltage space-vector and the q-component of the current space-vector is perpendicular to the voltage space-vector. The device is usable when the induction machine does not have enough magnetic flux for flux-based determination of the rotation speed and/or the direction of rotation.

The invention relates to a method for determining the position (O.sub.R) and the rotational speed (n.sub.R) of a rotor of an electrical machine during an active short circuit and a rotor-state determining device (10) designed to carry out the method. The method comprises the steps of determining the short circuit currents (I.sub.u, I.sub.v, I.sub.w) resulting during the short circuit, determining a total current (I.sub.α, I.sub.β) resulting from the short circuit currents (I.sub.u, I.sub.v, I.sub.w), determining a stator current angle (ψ.sub.l) of the total current (I.sub.α, I.sub.β) with respect to a stator coordinate system (α, β), determining a rotor current angle (φ.sub.l) of the total current (I.sub.α, I.sub.β) with respect to a flux direction (d.sub.R) of the rotor, this step comprising the steps of calculating an amount variable (I) of the total current (I.sub.α, I.sub.β), determining the rotor current angle (φ.sub.l) on the basis of a characteristic dependence between the amount variable (I) and a rotor current angle (φ.sub.l), which dependence is created for the electrical machine, the rotor position (θ.sub.R) corresponding to a sum of the stator current angle (ψ.sub.l) and the rotor current angle (φ.sub.l), and the rotor rotational speed (n.sub.R) resulting from monitoring of the rotor position (θ.sub.R).

A motor control device includes: a first communication unit that transmits or receives data to or from a motor; a communication disconnection determination unit that determines that the motor and the motor control device are in a disconnection state based on a fact that there is no reply from the motor within a prescribed period, and that determines that the motor and the motor control device have been restored to a connection state based on a fact that a reply from the motor to the motor control device has been restarted; and a replacement determination unit that obtains identification information from an identification information storage of the motor via the first communication unit and determines that the motor has been replaced, when it is determined that the motor and the motor control device have been restored to the connection state.