Provided is an electric tool capable of continuing work by making the electrical advance angle of a brushless motor changeable even when a load is heavy. The electric tool is provided with: a brushless motor; a controller for controlling the drive of the brushless motor; and an inverter circuit supplied with a pulsation voltage obtained by rectifying an AC power supply input in a full-wave manner and electrifying the brushless motor 1 according to a control signal of the controller. The controller can change the electrical advance angle of the brushless motor. The controller detects the motor current flowing through the brushless motor and increases the electrical advance angle when the motor current reaches a predetermined threshold value.

Provided is a method for controlling a brushless motor (101) in a power tool system. The brushless motor (101) includes multiple phase windings (u, v, w). The control method includes: operating the brushless motor (101) in each driving state for a period of time separately; measuring a voltage of a higher-voltage one of two phase input ends to which a driving voltage is applied and defining this voltage as a higher-voltage end voltage; measuring a voltage of a phase input end of one of the multiple phase windings which is kept floating when the driving voltage is applied and defining this voltage as a floating end voltage; determining whether values of the higher-voltage end voltage and the floating end voltage meet a preset condition; and when the values of the higher-voltage end voltage and the floating end voltage meet the preset condition, using any one of the multiple phase windings not serving as the current floating phase as a next floating phase. This method helps improve the running efficiency of the brushless motor (101).

A motor drive device includes a single-phase inverter that converts a direct-current voltage output from a power supply which is a battery, into an alternating-current voltage. The inverter outputs the alternating-current voltage as an applied voltage to be applied to a motor. The applied voltage is lower when the direct-current voltage is a second voltage lower than a first voltage than when the direct-current voltage is the first voltage. Consequently, a discharge current of the battery is reduced, and the motor drive device capable of reducing an increase in battery temperature can be obtained.

An electric tool includes a motor, a drive circuit, a power supply and a controller. The motor includes a rotor and first, second, and third phase windings. The drive circuit is electrically connected to the first, second, and third phase windings and drives the motor to output power. The power supply is electrically connected to the drive circuit and supplies power to the first, second, and third phase windings through the drive circuit. The controller is connected to the drive circuit and outputs a control signal to control the drive circuit. The controller controls the drive circuit according to a rotation position of the rotor when a voltage of the power supply is less than or equal to a preset voltage threshold so that the first, second, and third phase windings are simultaneously connected to the power supply.

A power tool and a control method of the power tool are provided. The power tool includes a rotor and a stator having a first phase winding, a second phase winding and a third phase winding; a power supply module configured to power the motor; a drive circuit configured to electrically connecting the power module to at least two of the first phase winding, the second winding, and the third phase winding; a controller configured to control the drive circuit to connect the first phase winding, the second phase winding, and the third phase winding to the power supply module according to a rotational position of the rotor.

A motor control apparatus includes: a motor drive control section that controls driving of a motor using a predetermined phase; a rotation position detecting section that, at every 180 degrees of an electrical angle of the motor, outputs two kinds of detection signals according to the rotation position of the rotor of the motor; a stopped position estimating section that estimates the stopped position at the start of rotation of the rotor using an elapsed time from when rotation the rotor starts until the kind of the detection signal outputted from the rotation position detecting section switches; a rotational speed estimating section that estimates the rotational speed of the rotor using the elapsed time and the stopped position; and an estimated phase calculating section that calculates an estimated phase as the aforementioned predetermined phase using the rotational speed.

An actuator controller that is capable of drivingly controlling an actuator, such as a motor, with a sufficient accuracy in spite of a simple configuration while preventing an incorrect detection of switching of a magnetic pole. The actuator controller drivingly controls an actuator having a driving element and a stator. A driver supplies an electric current to a coil provided in the stator so as to drive the driving element. A sensor detects a magnetic field of the driving element so as to detect a position of the driving element. A processor exclusively controls a timing at which the sensor detects the magnetic field and a timing at which the driver supplies the electric current to the coil.

A motor driving circuit for driving a motor is provided. The motor driving circuit includes a plurality of inverter circuits, a driving signal look-up table module, a driving signal generating unit, a duty cycle command detector, and a protection control circuit. The driving signal look-up table module performs a table lookup on an input driving signal to generate a driving waveform pattern signal while outputting a positive period indication signal. The duty cycle command detector generates a first protection start signal when a duty cycle corresponding to the input driving signal changes by more than a predetermined amount of change. The protection control circuit outputs a forced disable signal in a positive period interval in response to receiving the first protection start signal to control the lower bridge switch of one phase of the inverter circuits to be turned off.

A motor driving device includes a first hysteresis comparator, a second hysteresis comparator, a logic circuit, a control unit, and an inverter circuit. The logic circuit receives a start signal or a start completion signal to output the first output signal as a commutation signal according to the start signal, or to output the second output signal as the commutation signal according to the start completion signal, clamps the second output signal by the first output signal, stops outputting the commutation signal after the potential state of the commutation signal is changed, and unclamps the second output signal with the first output signal and outputs the commutation signal in response to a difference voltage between the first input signal and the second input signal being greater than a positive value of the first hysteresis voltage or less than a negative value of the first hysteresis voltage.

A motor driving circuit for driving a motor is provided. The motor driving circuit includes a plurality of inverter circuits, a driving signal look-up table module, a driving signal generating unit, a duty cycle command detector, and a protection control circuit. The driving signal look-up table module performs a table lookup on an input driving signal to generate a driving waveform pattern signal while outputting a positive period indication signal. The duty cycle command detector generates a first protection start signal when a duty cycle corresponding to the input driving signal changes by more than a predetermined amount of change. The protection control circuit outputs a forced disable signal in a positive period interval in response to receiving the first protection start signal to control the lower bridge switch of one phase of the inverter circuits to be turned off.