A rotor (1) for an electric machine (2) includes a rotor body with multiple poles. Multiple flux barriers (6.1, 6.2, 6.3, 6.4) are formed in the interior of the rotor body. The rotor (1) further includes at least one sensor element (3) configured for detecting at least one condition variable of the rotor (1), a signal processing unit (4) connected to the at least one sensor element (3) and configured for generating measured data from the detected condition variable of the rotor (1) and transmitting the measured data to a control device (5), and at least one induction coil (7) that includes at least one electrical conductor (8), is arranged in at least one flux barrier (6.1) of the rotor (1), and is configured for generating electrical energy from a leakage magnetic field in this flux barrier (6.1).

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.

An impact power tool includes a housing, a motor, a controller, an output member configured to be rotated when the motor is energized, and an impact mechanism configured to rotationally drive the output member. The impact mechanism is configured to selectively apply rotational impacts to the output member when a torque on the output member exceeds a torque threshold. The controller is configured to control the motor during a first phase of operation with open loop control and a baseline conduction band and advance angle setting when a sensed tool operation parameter is one of above or below a threshold value. The controller is configured to control the motor during a second phase of operation with closed speed loop control and an increased conduction band and advance angle setting when the sensed tool operation parameter is the other of above or below the threshold value.

An impact power tool includes a housing, a motor, a controller, an impact mechanism configured to be driven by the motor, and an output spindle configured to receive rotational impacts from the impact mechanism to rotate the output spindle. The controller is configured to detect a first impact of the rotational impacts or to detect when the motor speed drops below a speed threshold value. The controller is configured to control the motor to have a first non-zero target rotational speed using closed loop control for a predetermined time period after the first impact is detected or when the motor speed dropping below the speed threshold value is detected. The controller is configured to control the motor to have a second non-zero target rotational speed using the closed loop control after the predetermined time period. The first non-zero target rotational speed is less than the second non-zero target rotational speed.

Provided are a method and system for controlling an electric motor, and a controller. The method comprises: controlling an electric motor to operate in an open-loop manner; determining whether a rotational speed of the electric motor reaches a preset rotational speed; if so, determining whether the absolute value of an angle difference between an open-loop angle and a calculated position angle of the electric motor is greater than a preset angle; and if the absolute value of the angle difference is less than or equal to the preset angle, controlling the electric motor to operate in a closed-loop manner so as to avoid the situation where the electric motor cannot operate stably due to problems such as electric motor speed vibration caused by too large an angle difference between the open-loop angle and the position angle.

Provided are a method and system for controlling an electric motor, and a controller. The method comprises: controlling an electric motor to operate in an open-loop manner; determining whether a rotational speed of the electric motor reaches a preset rotational speed; if so, determining whether the absolute value of an angle difference between an open-loop angle and a calculated position angle of the electric motor is greater than a preset angle; and if the absolute value of the angle difference is less than or equal to the preset angle, controlling the electric motor to operate in a closed-loop manner so as to avoid the situation where the electric motor cannot operate stably due to problems such as electric motor speed vibration caused by too large an angle difference between the open-loop angle and the position angle.

At time of startup, a rotation controlling section for controlling a rotor of a brushless motor supplies power to an excitation coil of one phase among excitation coils of three phases limitedly for a predetermined time. An induced voltage measurement section measures an induced voltage generated in another excitation coil than the excitation coil to which the power was supplied and based on the result of this measurement, possibility/impossibility of startup is decided. Based on the result of this decision, an excitation coil of one phase among the excitation coils of three phases is set as a supply starting coil to which power is to be supplied first and forced commutation is carried out.

The present invention addresses the problem of providing a method which makes it possible to simply evaluate an output of an initial position detection signal for a permanent magnetic field, along with providing a method for correcting errors that occur in the initial position detection signal. As a means for solving said problem, an MPU (51) obtains a correction value in which an offset error has been corrected by multiplying a first measurement value or a second measurement value, which are measured for each conduction pattern when an offset error occurs during position detection of a permanent magnetic field, by a correction coefficient A and estimates the position of the permanent magnetic field on the basis of the correction value.

The present invention addresses the problem of providing a method which makes it possible to simply evaluate an output of an initial position detection signal for a permanent magnetic field, along with providing a method for correcting errors that occur in the initial position detection signal. As a means for solving said problem, an MPU (51) obtains a correction value in which an offset error has been corrected by multiplying a first measurement value or a second measurement value, which are measured for each conduction pattern when an offset error occurs during position detection of a permanent magnetic field, by a correction coefficient A and estimates the position of the permanent magnetic field on the basis of the correction value.

A method for determining a rotor position of a BLDC motor with a magnetic rotor and stator having at least one exciter coil to which an exciter voltage is applied in accordance with a commutation process, comprises: interrupting the exciter voltage applied to the exciter coil, wherein the exciter voltage has a profile with at least one first section in which the profile of the exciter voltage has a non-vanishing finite gradient, wherein the exciter voltage in the first section is interrupted, and wherein at the time of interruption the exciter voltage has a value different from zero; capturing a voltage induced in the exciter coil by the magnetic rotor; restoring the exciter voltage to a value different from zero; and determining a rotor position of the rotor with respect to the exciter coil on the basis of the captured induced voltage.