A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.

An information related to the position of an actuator coupled to a cable which is coupled to a motor is received. A filter is used to provide an input to a motor controller coupled to the motor, to adjust torque on the motor such that a strength curve is implemented relative to the position of the actuator.

An information related to the position of an actuator coupled to a cable which is coupled to a motor is received. A filter is used to provide an input to a motor controller coupled to the motor, to adjust torque on the motor such that a strength curve is implemented relative to the position of the actuator.

Methods and power tools for sensorless motor control. One embodiment provides a method for automatic control switching for driving a sensorless motor (150) of a power tool (100). The method includes determining, using a motor controller (224), a first load point based on user inputs (232) and determining, using the motor controller (224), a first motor control technique corresponding to the first load point. The method also includes driving the motor (150) based on the first motor control technique. The method further includes determining, using the motor controller (224), a change from the first load point to a second load point and determining, using the motor controller (224), a second motor control technique corresponding to the second load point. The method includes driving the motor (150) based on the second motor control technique.

A power tool is provided including a brushless motor having a stator defining a plurality of phases and a rotor. A power unit is provided including power switches and a control unit outputs a drive signal to the motor switches to drive the phases of the motor using a trapezoidal control scheme over a series of sectors. The control unit sets a conduction band within which each phase is commutated to a baseline value that is greater than 120 degrees, sets at least one commutation transition point as a function of the set conduction band, and within each sector, monitors an open-phase voltage of the motor to detect a back electromotive force (back-EMF) voltage of the motor and control commutation of at least one phase based on the open-phase voltage of the motor in relation to the at least one commutation transition point.

A motor controller estimates an initial position of a magnetic pole of a rotor of a brushless DC motor in an inductive sensing scheme. The motor controller controls a drive circuit to apply an AC voltage to a stator winding at a first energization angle, and subsequently to apply an AC voltage to the stator winding at a second energization angle before a residual current flowing through the stator winding returns to zero. At each energization angle, the motor controller corrects a peak value of a current in the stator winding based on the residual current detected immediately before a voltage is applied to the stator winding or at a time when voltage application to the stator winding is started. Based on the corrected peak value, the control circuit estimates the initial position of the magnetic pole of the rotor.

A motor system can include a motor, the motor including at least a rotor, and a controller configured to operate the motor. The controller can be configured to perform operations for operating the motor. The operations can include determining an initial estimated rotor angle, determining one or more estimated currents defined by an estimated rotating reference frame based at least in part on the estimated rotor angle, obtaining one or more current measurements of one or more measured currents respective to the one or more estimated currents, determining one or more current errors based at least in part on a subtractive combination of the one or more estimated currents and the one or more measured currents, determining one or more rotor flux estimates based at least in part on the one or more current errors, the one or more rotor flux estimates comprising at least an estimated δ-directed rotor flux vector, and determining an estimated rotor speed based at least in part on an integral of the estimated δ-directed rotor flux vector.

An information related to the position of an actuator coupled to a cable which is coupled to a motor is received. A filter is used to provide an input to a motor controller coupled to the motor, to adjust torque on the motor such that a strength curve is implemented relative to the position of the actuator.

A method for determining a rotation variable of a rotatably mounted rotor of a mechanically commutated electric motor, having a motor current path formed between two brush elements of the electric motor, and leading via the commutator bars contacted by the brush elements, and via coil windings of the rotor electrically connected to said commutator bars, wherein an oscillating input signal is fed into the motor current path and the rotation variable is determined with the aid of a ripple of a resultant output signal, said ripple being due to the mechanical commutation of the motor current path.

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.