A temperature monitoring device for protecting the winding of an electronically commutated electric motor from being heated over a specified limit temperature T.sub.G regardless of the rotational speed includes a phase current detection device for detecting the phase current I.sub.Winding for the motor windings, an overcurrent switch-off device for switching off the electric motor if a maximum permissible phase current I.sub.Shutdown is exceeded, and an overcurrent monitoring device, which is connected to the overcurrent switch-off device, in order to transmit to it a switch-off signal if the detected phase current I.sub.Winding exceeds the maximum permissible phase current I.sub.Shutdown ascertained by a detection and computing device, wherein an algorithm in which the measured ambient temperature T.sub.U is incorporated is used when ascertaining the maximum permissible phase current I.sub.Shutdown.

A current measurement apparatus for a three-phase inverter, according to one embodiment of the present invention, comprises: a current detection element connected to a lower end of one of three lower switches constituting the inverter; a current measurement unit measuring currents by using the current detection element and the two lower switches that are not connected to the current detection element; and a current correction unit for correcting, on the basis of the relationship between a first current value measured by means of the current detection element and second and third current values measured by means of the two lower switches, the second and third current values.

A commutation error compensation method for an electric motor includes: when a rotor, that has not been corrected, in an electric motor rotates in a set direction, collecting a position signal and a three-phase current signal of the rotor, wherein the position signal of the rotor represents the rotation angle of the rotor; filtering processing on the three-phase current signal to obtain a fundamental component of the three-phase current signal, and determining a position error compensation signal of the electric motor on the basis of the fundamental component of the three-phase current signal; determining an ideal phase interval of the rotor according to the position error compensation signal and the position signal of the rotor; and determining an adjustment method for the rotor of the electric motor according to the ideal phase interval of the rotor, and commutating the rotor of the electric motor according to the adjustment method.

An electric tool includes a drive structure, a motor, a driver circuit, and a controller. The controller is configured to output a first control signal to control the motor to drive the drive structure to operate in a first operation mode for a preset period of time in response to receiving a start instruction. After the preset period of time, the controller will output a second control signal to control the motor to drive the drive structure to operate in a second operation mode to a preset state. The first operation mode and the second operation mode are two opposite operation modes.

A system for controlling a motor includes a controller module comprising a controller portion, a regulator portion and an integrator portion. The regulator portion includes a set of regulator modules communicatively coupled in a sequence. Each regulator module configured to receive a respective input signal, indicative of a target or selected value, from the controller portion or the immediately preceding regulator module in the sequence, determine a respective selectable value; select one of the respective selectable value and the value indicated by the received input signal; and provide the selected value as an output signal to the next regulator module in the sequence or the integrator module. The integrator module is configured to receive the output signal from the last regulator module in the sequence, calculate a final demand value based on the received signal, and provide an output signal indicative of the final demand value.

A system for controlling a motor includes a controller module comprising a controller portion, a regulator portion and an integrator portion. The regulator portion includes a set of regulator modules communicatively coupled in a sequence. Each regulator module configured to receive a respective input signal, indicative of a target or selected value, from the controller portion or the immediately preceding regulator module in the sequence, determine a respective selectable value; select one of the respective selectable value and the value indicated by the received input signal; and provide the selected value as an output signal to the next regulator module in the sequence or the integrator module. The integrator module is configured to receive the output signal from the last regulator module in the sequence, calculate a final demand value based on the received signal, and provide an output signal indicative of the final demand value.

To provide a rotational angle detection apparatus which can determine abnormality of the rotational angle detection apparatus only by detection information of the rotational angle detection apparatus even when the rotational speed is low. A rotational angle detection apparatus totals sensor output values of N-1 pieces of the rotation detection sensors other than the diagnosis object sensor; calculates a value obtained by inverting positive/negative of a total value, as an estimation value of sensor output value of the diagnosis object sensor; calculates an estimation difference which is a difference between a sensor output value of the diagnosis object sensor, and the estimation value of sensor output value of the diagnosis object sensor; and determines that abnormality occurred in the diagnosis object sensor, when the estimation difference is out of a determination range for estimation difference.

To provide a rotational angle detection apparatus which can determine abnormality of the rotational angle detection apparatus only by detection information of the rotational angle detection apparatus even when the rotational speed is low. A rotational angle detection apparatus totals sensor output values of N-1 pieces of the rotation detection sensors other than the diagnosis object sensor; calculates a value obtained by inverting positive/negative of a total value, as an estimation value of sensor output value of the diagnosis object sensor; calculates an estimation difference which is a difference between a sensor output value of the diagnosis object sensor, and the estimation value of sensor output value of the diagnosis object sensor; and determines that abnormality occurred in the diagnosis object sensor, when the estimation difference is out of a determination range for estimation difference.

Systems and methods for determining proper phase rotation in a linear motor that may be used in an ESP system, where the phase rotations associated with power and return strokes are initially unknown. The method includes providing power to the motor for multiple cycles and monitoring the load (e.g., by monitoring current drawn by the motor) on the motor to determine in which direction (phase rotation) the load on the motor increases. This direction corresponds to the power stroke of the motor. The direction of increasing load is then associated with the power stroke and the motor is operated normally.

Systems and methods for determining proper phase rotation in a linear motor that may be used in an ESP system, where the phase rotations associated with power and return strokes are initially unknown. The method includes providing power to the motor for multiple cycles and monitoring the load (e.g., by monitoring current drawn by the motor) on the motor to determine in which direction (phase rotation) the load on the motor increases. This direction corresponds to the power stroke of the motor. The direction of increasing load is then associated with the power stroke and the motor is operated normally.