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 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 operable to deliver power to the motor. A primary controller is interfaced with the power unit to output drive signals to drive the phases of the motor over a series of sectors of the rotor rotation. The primary controller measures a back-electromotive force voltage of the motor and transitions motor commutation from the present sector to the next sector based in relation to the back-EMF voltage. A second controller is provided to receive at least one of the drive signals, calculate a speed and/or direction of rotation of the motor from the drive signals, and take corrective action to cut off supply of power to the motor if it detects an overspeed condition or incorrect direction of rotation.

A permanent-magnet synchronous motor includes an inverter power circuit that converts direct-current power to three-phase alternating-current power, a motor bodydriven by the three-phase alternating-current power, a current detector that calculates an excitation current value and a torque current value from motor stator current values and an estimated value of a magnetic pole position of the rotor, a magnetic pole position detector that determines, for output to the current detector, the estimated value from the excitation current value, the torque current value, and supply voltage information, a voltage calculation unit that calculates, by means of the excitation current value, the torque current value, and an angular velocity calculated from the estimated value, the supply voltage information that causes the torque current value to approximate a torque current command value, and an inverter controller that controls the inverter power circuit on a basis of the supply voltage information and the estimated value.

A motor driving device includes an OPEN driving mode in which a driving waveform is generated without using detection information of a rotational position of a rotor and the rotor is rotated, and a CLOSE driving mode in which a phase of a rotational position and a phase of a driving waveform are synchronized using the detection information of the rotational position of the rotor, a desired phase difference is set between the rotational position and the driving waveform, and the rotor is rotated. The CPU controls rotation of the rotor using the OPEN driving mode, instructs a driving waveform generating circuit to set a phase difference for generating a torque in a reversing direction when rotation of the rotor is reversed, switches to the CLOSE driving mode, and then switches to the OPEN driving mode again when reversing has been completed.

A system according to the present disclosure includes a motor driver module and a motor position determination module. The motor driver module is configured to measure current supplied to a motor. The motor position determination module is configured to determine a first position of the motor at a first time when power supply to the motor is initially discontinued based on ripples in the current supplied to the motor during a first period before the first time. The motor position determination module is configured to determine a second position of the motor at a second time when the motor stops rotating after power supply to the motor is discontinued based on the first position of the motor and a rotational speed of the motor at the first time.

A system includes a motor control module and an occupant weight classification module. The motor control module is configured to supply power to a motor to move a seat in a first direction from a first position to a second position when the seat is unoccupied and supply power to the motor to move the seat in a second direction from a third position to a fourth position when an occupant is in the seat. The occupant weight classification module is configured to measure a first frequency of ripples in current supplied to the motor as the seat is moved from the first position to the second position, measure a second frequency of ripples in the current supplied to the motor as the seat is moved from the third position to the fourth position, and determine a weight of the occupant based on the first and second frequencies.

A control system for a power generation system includes a generator coupled to a turbine via a shaft. The control system includes a memory storing instructions. The control system also includes a processor coupled to the memory and configured to execute the instructions. When the instructions are executed it causes the processor to receive a direct current (DC)-link voltage from an automatic voltage regulator (AVR), wherein the AVR is configured to control voltage characteristics of the generator, and to determine a speed of the generator based on the DC-link voltage.

A motor module includes a motor including a commutator, and an apparatus that is attached to the motor and obtains information on rotation of the motor. The apparatus includes a rotation angle calculator that calculates a rotation angle of the motor based on a voltage between terminals of the motor and an electric current flowing through the motor, a first signal generator that generates a first signal based on a ripple component included in the electric current flowing through the motor, a second signal generator that generates a second signal indicating that the motor has rotated by a predetermined angle based on the first signal and the rotation angle, and a rotation information calculator that calculates the information on the rotation of the motor based on an output from the second signal generator.

A variable speed drive comprises an output for delivering a drive voltage to an electric motor, power inverter, a drive controller, and a current sensor. The drive controller includes a PWM generator, a control law module, and a state variable estimator for estimating a state variable of the electric motor. The module computes a target voltage signal based on state variable estimates provided by the estimator and outputs the target voltage signal to the PWM generator. The generator approximates the target voltage signal with a PWM control signal, controls the inverter using the control signal, computes, based on the deviation between the control signal and the target voltage signal, an estimation support signal, and outputs the estimation support signal to the estimator. The estimator estimates a state variable of the motor based on the estimation support signal and the drive current, and outputs the estimate to the module.

A permanent-magnet synchronous motor includes an inverter power circuit that converts direct-current power to three-phase alternating-current power, a motor bodydriven by the three-phase alternating-current power, a current detector that calculates an excitation current value and a torque current value from motor stator current values and an estimated value of a magnetic pole position of the rotor, a magnetic pole position detector that determines, for output to the current detector, the estimated value from the excitation current value, the torque current value, and supply voltage information, a voltage calculation unit that calculates, by means of the excitation current value, the torque current value, and an angular velocity calculated from the estimated value, the supply voltage information that causes the torque current value to approximate a torque current command value, and an inverter controller that controls the inverter power circuit on a basis of the supply voltage information and the estimated value.