The present invention includes a phase angle detection unit generating a phase angle signal switched at a timing at which a cogging torque generated with the rotation of a rotor of a brushless DC motor reaches near a peak on a negative side hindering the rotation of the rotor, an inverter circuit energizing coils of respective phases of the brushless DC motor by switching elements according to an input of a driving signal, an energization period calculation unit calculating an energization period Tw from a target rotation speed set for the brushless DC motor, and a drive control unit energizing the coils sequentially by outputting the driving signal to the respective switching elements for each energization period, gradually increasing a duty of the driving signals to the switching elements at a start of each energization period, and decreasing the duty after the phase angle signal is switched.

A motor includes a stator coil, a rotor and a driving unit. The stator coil is configured to be electrified to generate a magnetic force. The rotor is rotatably coupled with the stator coil and includes a magnetic member facing the stator coil. The driving unit is electrically connected to the stator coil and outputs a driving signal to the stator coil. An electrical characteristic value of the driving signal increases in a gradual manner. The rotor outputs a motive power that is gradually increased during a process the rotor rotates from an electric angle back to a same electric angle. In addition, an activation control method for the motor and a fan are also disclosed.

A commutation control method, a device for a brushless direct current motor, and a storage medium are described. The method includes performing detection on a position of a rotor in a brushless direct current motor. The detection is further configured to be triggered by commutation of the brushless direct current motor. The method includes determining, for the brushless direct current motor, a first drive scheme corresponding to the detected position of the rotor, the first drive scheme indicates a manner in which a three-phase full-bridge circuit of the brushless direct current motor operates; updating a pulse width modulation (PWM) drive signal, the updating is performed on the basis of the first drive scheme; and using the updated PWM drive signal to control the brushless direct current motor to perform commutation.

A power tool includes a multi-phase BLDC motor, a plurality of switches, an input unit, and a controller. For each phase, the controller operates to vary power output to the motor between a first power and a second power by varying a duty cycle of a PWM signal from 0% to 100% while keeping a conduction band (CB) of corresponding motor switches and/or an advance angle (AA) at a predetermined value when the input unit moves between a first position and a predetermined position between the first and a second position. For each phase, the controller operates to increase the power output by the motor to greater than the second power by increasing the CB/AA to greater than the predetermined value while keeping the duty cycle of the PWM signal at 100% when the input unit moves between the predetermined position and the second position.

A power tool includes a multi-phase BLDC motor, a plurality of switches, an input unit, and a controller. For each phase, the controller operates to vary power output to the motor between a first power and a second power by varying a duty cycle of a PWM signal from 0% to 100% while keeping a conduction band (CB) of corresponding motor switches and/or an advance angle (AA) at a predetermined value when the input unit moves between a first position and a predetermined position between the first and a second position. For each phase, the controller operates to increase the power output by the motor to greater than the second power by increasing the CB/AA to greater than the predetermined value while keeping the duty cycle of the PWM signal at 100% when the input unit moves between the predetermined position and the second position.

A drive control device for a motor includes an input terminal, an output terminal, an inverter circuit, a first switch unit, a capacitor, a diode, a rectifier circuit, a photo coupler, a second switch unit, and a voltage detector. The inverter circuit converts a direct current voltage into an alternating current voltage, and outputs the alternating current voltage to the output terminal. The first switch unit shorts the output terminal based on a control signal. The capacitor is connected to the input terminal, and is charged by a direct current voltage. The diode is connected between the input terminal and the capacitor. The diode limits a direction where a charge current for charging the capacitor flows. The rectifier circuit rectifies an induced voltage, which is generated in the motor, and outputs a rectified voltage. The photo coupler converts the rectified voltage into an optical signal, and thereafter, converts the optical signal into a converted signal. The second switch unit outputs the control signal based on the converted signal. The voltage detector detects whether the direct current voltage is input to the input terminal, and determines whether to negate the control signal.

A system, in some embodiments, comprises: an analog-to-digital converter (ADC) configured to receive a discrete analog voltage and to generate a digital bit value representing said analog voltage; control logic, coupled to the ADC, configured to identify a target intercept and a target slope for a lead angle curve based on the digital bit value; and a motor, coupled to the control logic, configured to operate based on a lead angle identified using said lead angle curve, wherein the ADC receives the analog voltage via a single integrated circuit pin.

A device for sensing a rotational position of a rotatable element for a household appliance includes: a stator having a plurality of capacitive sensor surfaces spaced apart from one another in a plane of extension of the stator; and a rotor rotatably positionable or disposed relative to the stator and having an electrically conductive section and a dielectric non-conductive section, the conductive section being larger in area than the non-conductive section, the rotor being disposed opposite the plane of extension of the stator in a rotatable condition relative to the stator, and the rotor being couplable or coupled to the rotatable element.

A sensorless commutation error compensation system for a brushless motor, comprises: a brushless motor (200) and a commutation logic module circuit (100). The commutation logic module circuit (100) is connected to three virtual Hall signal output ends of the brushless motor (200), and used for receiving three virtual Hall signals output by the brushless motor (200), obtaining three error compensation angle signals on the basis of the three virtual Hall signals, respectively superimposing the three error compensation angle signals and the three virtual Hall signals to form superposition results, and controlling the brushless motor (200) to adjust commutation timing on the basis of the superposition results, so as to achieve commutation error compensation. The system controls commutation errors on the basis of currents and counter-electromotive forces of three phases, instead of controlling the commutation errors on the basis of the current and the counter-electromotive force of one of the three phases, so that a torque ripple of a brushless direct-current motor can be reduced and a working efficiency of the motor can be improved.

A filter for use with a brushless DC motor to filter a signal received from a floating terminal of the brushless DC motor, wherein the filter is configured such that a time delay introduced by the filter to the signal received from the floating terminal is equal to the time taken for a rotor of the motor to rotate through an angle equal to half of a commutation step of the motor.