Abstract: A method for starting an internal combustion engine (ICE) having a crankshaft and an electric turning machine (ETM) operatively connected to the crankshaft comprises energizing an absolute position sensor adapted for providing an indication of an angular position of a rotor of the ETM and applying a current to the ETM to generate a sufficient torque to rotate the crankshaft.

Abstract: Disclosed herein is an intelligent washing machine includes: an inner tub in which laundry is placed; a motor transferring a rotational force to the inner tub; an image obtaining unit obtaining an image of the laundry placed in the inner tub after a washing process; and a controller obtaining a laundry classification information reflecting water content percentage information of the laundry from the image of the laundry, learning the laundry classification information to predict a degree of vibration of the inner tub that occurs in a spin-drying process, and varying a revolutions per minute (RPM) of the motor in the spin-drying process according to the predicted degree of vibration of the inner tub. The washing machine may be associated with an artificial intelligence (AI) module, an unmanned aerial vehicle (UAV) (or drone), a robot, an augmented reality (AR) device, a virtual reality (VR) device, and a device related to a 5G service.

Abstract: A control system may include: a motor configured to power a driven object; and circuitry configured to: generate a first driving force command to drive the motor during a first control; estimate a first force acting on the motor during the first control based, at least in part, on the first driving force command; generate a second driving force command to drive the motor during a second control after the first control; estimate a second force acting on the motor during the second control based, at least in part, on the second driving force command; and estimate an external force acting on the driven object during the second control based, at least in part, on a comparison between the first force and the second force.

Abstract: Examples of methods and systems for compensating for the timing delay caused by the winding impedance of the motor coils and/or for non-ideal rotor magnet shapes and positions are disclosed. The example methods and systems may include generating a synthesized commutation signal compensating for non-ideal magnet shapes and positions (e.g., asymmetrical magnet positions) on a rotor and/or compensates for the timing delay caused by the winding impedance of the motor coils.

Abstract: A method for starting an internal combustion engine (ICE) having a crankshaft and an electric turning machine (ETM) operatively connected to the crankshaft comprises energizing an absolute position sensor adapted for providing an indication of an angular position of a rotor of the ETM and applying a current to the ETM to generate a sufficient torque to rotate the crankshaft.

Abstract: A method for controlling an electric vehicle having a field winding type synchronous motor for providing a driving force, the field winding type synchronous motor that has a rotor having a rotor winding and a stator having a stator winding, by controlling a stator current flowing in the stator winding and a rotor current flowing in the rotor winding is provided.

Abstract: A method for correcting an angle sensor is applied to a step motor including an angle sensor, where the angle sensor rotates with the step motor, and the method for correcting an angle sensor includes the following steps: rotating the step motor by a preset angle to a first position; reading a first voltage of the angle sensor when the angle sensor is rotated to the first position; determining whether the first voltage deviates from a preset voltage curve; if yes, recording a first offset of the first voltage relative to the preset voltage curve; and compensating for a sensing angle of the angle sensor according to the first offset. A device for correcting an angle sensor is further provided.

Abstract: Disclosed herein are a method for controlling a medium-voltage inverter, and a system including the same. The system includes a motor, a medium-voltage inverter driving the motor, a control unit configured to control an output voltage from the medium-voltage inverter, and an output voltage measuring unit configured to measure counter electromotive force data of the motor including a voltage and a frequency of the counter electromotive force, and transmitting it to the control unit. The control unit generates the output voltage based on the measured counter electromotive force data to re-drive the motor when the output voltage measuring unit completes the measurement of the counter electromotive force data.

Abstract: A pulse motor driving circuit includes a first switch having a terminal connected with a positive terminal of a power source; a second switch having a terminal connected with a negative terminal of the power source; and a capacitor having another terminal connected with positive terminal of the power source and having another terminal of the first switch and another terminal of the second switch. The second switch is a transistor, and is capable of limiting a current flowing from the power source to the capacitor. The first switch is turned on and the second switch is turned off in a current application start period while the current starts to be applied to a pulse motor phase excitation part for exciting the pulse motor. The first switch is turned off and the second switch is turned on in a period other than the current application start period.

Abstract: A pulse motor driving circuit for driving a pulse motor includes a first switch having a terminal that is connected with a positive terminal of a power source; a second switch having a terminal that is connected with a negative terminal of the power source; and a capacitor having a terminal connected with a limit element and having another terminal connected with another terminal of the first switch and another terminal of the second switch, wherein the limit element is provided between the positive terminal and the capacitor and limits a current, wherein the first switch is turned on and the second switch is turned off in a current application start period while the current starts to be applied, wherein the first switch is turned off and the second switch is turned on in a period other than the current application start period.

Abstract: The system and method disclose for the controlling of motor switching. The system includes a controller unit having a control signal generator, a memory device, a processing unit, a signal acquisition device, and an analog-to-digital converter. A power stage has a plurality of switches and receives a control signal from the control signal generator and a power signal from a power source. The power stage drives two windings of the set of three stator windings with a multi-state pulse and leaves one stator of the three stator windings undriven. The processing unit acquires a demodulated measured voltage on the undriven winding. The processing unit communicates with the power stage to change which two windings of the three stator windings are driven when the demodulated measured voltage surpasses a threshold.

Abstract: An image forming apparatus includes an engine portion configured to perform image forming, a direct current (DC) motor configured to mechanically operate the engine portion, a driver including a resistor to measure current that flows to the DC motor according to the measured current and configured to provide a predetermined voltage to the DC motor, and a drive controller configured to measure a driving speed of the DC motor based on a voltage value of the resistor and to control the driver to provide a voltage that corresponds to the measured driving speed to the driver.

Abstract: Systems, methods, and other embodiments associated with back-EMF detection for motor control are described. In an embodiment, an apparatus includes a drive circuit configured to apply excitation signals to respective inputs of a motor, a signal inhibit circuit configured to convey a signal to inhibit application of the excitation signals during an interval, and a measuring circuit configured to measure a back-electromotive force (EMF) signal crossing a reference signal during the interval.

Abstract: In order to realize, without inviting cost increase, a control for maintaining a pressure of fluid delivered from a pump at a target value, a pump control unit is provided with a driver control unit controlling a rotational speed of a hydraulic pump through adjustment of a duty ratio of a PWM signal driving excitation coils of an electric motor. Further, the pump control unit is provided also with a signal correction circuit configured to convert a current flowing in the excitation coils to a voltage signal with using a shunt resistor and to divide the voltage signal with using a voltage division ratio setting circuit and to shorten an ON signal of the PWM signal by increasing the divided voltage. The voltage division ratio setting circuit has a characteristics of setting the divided voltage higher, the longer an ON period of the PWM signal.

Abstract: A method for detecting blockages of unipolar stepper motors by analyzing the motor current supply, comprising impressing a current into one or more motor windings using a controllable switch, wherein the switch selectively connects a respective motor winding connection to a supply voltage connection and wherein the connections of each motor winding lying at a common potential are permanently connected to a second supply voltage connection, wherein a current feed variant has phases between the switching of the motor windings, in which phases the motor winding connections are switched with high resistance; detecting the voltage at a motor winding connection at least for the high-resistance phase and comparing the voltage to a threshold; detecting a time interval for which the voltage is greater than the threshold; comparing interval lengths for several motor winding connections, and detecting a blockage based on the comparisons of interval lengths.

Abstract: A household appliance including a fan speed controller, and a method of controlling fan speed of a household appliance, are provided. The system includes a fan speed controller that cut a voltage to the fan motor, measures an electromotive force (EMF) of the fan motor at a predetermined time after the cutting of the voltage to the fan motor, and compares the measured electromotive force (EMF) to a table.

Abstract: A method for controlling a specific electric machine includes receiving with a controller a back electromotive force (BEMF) coefficient for the specific electric machine. The controller is configured to control operation of an inverter coupled to the electric machine where the inverter is configured to provide or receive multi-phase electricity to or from the electric machine in motor mode or generator mode, respectively. The method further includes receiving with the controller an input related to a selected torque to be applied by or a selected power to be removed from the electric machine. The method further includes determining a first electrical parameter the inverter is to apply to in motor mode or a second electrical parameter the inverter is to convert power to in generator mode using the BEMF coefficient, and applying the first electrical parameter to the electric machine or converting the received power to the second electrical parameter.

Abstract: A motor driving device, which controls a rotation number of a brushed motor by outputting a command signal to a motor controller placed in a current supply path, includes: a noise detecting unit including at least one of: a high voltage side noise detecting unit which detects high voltage side noise from brush noise included in the monitor voltage, based on whether a monitor voltage is larger than a first threshold voltage; and a low voltage side noise detecting unit which detects low voltage side noise from the brush noise included in the monitor voltage, based on whether the monitor voltage is smaller than a second threshold voltage; and a calculating unit which outputs the command signal to the motor controller to control the rotation number of the motor to reduce a occurrence number of the brush noise, based on at least one of the occurrence numbers.

Abstract: A method, system and computer program product for monitoring health of a synchronous machine is provided. The method includes receiving a plurality of phase voltage values and a plurality of phase current values. The method then computes a negative sequence voltage (Vn) based on the plurality of phase voltage values. The method also computes one or more operating parameters based on at least one of the plurality of phase voltage values and the plurality of phase current values. The method retrieves from a data store, one or more known Vn based on the one or more operating parameters. The method then computes a machine health indicator based on the computed Vn and the one or more known Vn, and raises an alarm based on the machine health indicator.

Abstract: A switching element is switched off after having been switched on for only a short time interval called a first predetermined time interval, and a determination is made, based on a mode of a change in a contact point potential (a regeneration voltage) between an electric motor and the switching element when the switching element as switched off, as to whether or not one of the electric motor and the switching element has failed. Next, the switching element is switched on for a time interval called a second predetermined time interval, which is longer than the first predetermined time interval, and a determination is made, based on the magnitude of the contact point potential at that time, as to which one of the electric motor and the switching element has failed. It is thus possible for a failure of the switching element and electric motor to be detected.

Abstract: An electronically commutated one-phase motor (20) has a stator having at least one winding strand (30, 32) and a permanent-magnet rotor (22). The rotor, as it rotates, induces a voltage (uind) in the at least one winding strand (30, 32). The motor has an electronic calculation device (26), preferably a microcontroller ?C, which is configured to execute, during operation, the steps of a) sensing the value of the instantaneous operating voltage (Ub); (b) using the operating voltage value (Ub) and optionally further parameters, adjusting a time duration (TON) of a switch-on current pulse (i30) for the motor, in order to apply a consistent amount of electrical energy to the windings during start-up attempts, thereby maximizing the probability of successful start-up, regardless of possible fluctuations in motor operating voltage and related operating parameters. The switch-on current pulse duration (TON) can be adjusted longer or shorter, as a function of operating experience.

Abstract: In a drive control circuit of a linear vibration motor, the drive signal generating unit generates a drive signal whose phase is opposite to that of the drive signal generated during the motor running, after the running of the linear vibration motor has terminated; this drive signal of opposite phase includes a high impedance period during which the driver unit is controlled to a high impedance state. An induced voltage detector detects an induced voltage occurring in the coil. A comparator has a function as a hysteresis comparator in which the output level does not vary in a predetermined dead band, and the comparator outputs a high-level signal or a low-level signal during the high impedance period. When an in-phase signal is consecutively outputted from the comparator during the consecutive high-impedance periods, the drive signal generating unit determines that the linear vibration motor has come to a stop.

Abstract: According to one embodiment, a motor control apparatus includes a timer to measure a period in which a job is not executed, a sensor to detect a temperature of a physical object, an acquisition part to acquire time information measured by the timer and temperature information detected by the sensor, and a drive control part that determines a current value of a motor provided in the physical object based on the time information and the temperature information acquired by the acquisition part, and controls the motor current value by applying a voltage level corresponding to the determined current value to a drive element of the motor.

Abstract: To achieve peak acoustic and power performance, the coil or applied current should be in phase or substantially aligned with the back electromotive force (back-EMF) voltage. However, there are generally phase differences between the applied current and back-EMF voltage that are induced by the impedance of the brushless DC motor (which can vary based on conditions, such as temperature and motor speed). Traditionally, compensation for these phase differences was provided manually and on an as-needed basis. Here, however, a system and method are provided that automatically perform a commutation advance by incrementally adjusting a drive signal over successive commutation cycles when the applied current and back-EMF voltage are misaligned.

Abstract: A management apparatus is described of a rotating motor and a load during power loss; the apparatus comprises a first switching circuit coupled with the rotating motor and a controller of said first switching circuit. The controller is configured to drive the first switching circuit so as to convert a back-electromotive force voltage developed in the rotating motor into a power supply voltage for the load. The first switching circuit is driven in accordance with a first duty cycle. The apparatus comprises a second switching circuit coupled with the load and driven in accordance with a second duty cycle. The controller is configured to vary said first and said second duty cycles to keep the power supply voltage for the load above or equal to a threshold voltage.

Abstract: The invention relates to an electric device (1) comprising an alternating current electric motor (3) and a control inverter (5) for controlling the phase or phases of the motor (3). The motor (3) comprises, on at least one winding of at least one phase (PA, PB, PC), a point (Ma, Mb, Mc) for measuring a voltage relative to a predefined potential (M), the measurement point (Ma, Mb, Mc) being chosen so that it divides the winding into a first (Za1; Zb1; Zc1) and a second (Za2; Zb2; Zc2) portion such that the electromotive forces (ea1, ea2) induced in the two portions are phase-shifted relative to one another and means (11A; 11B; 11C) for measuring the voltage between the measurement point and the predefined potential. The invention also relates to an associated method for measuring electromotive forces.

Abstract: A control device for an AC rotating machine having a current limiting function of protecting the AC rotating machine and a driving unit such as an inverter from over-current, in which the control device has the reliable current limiting function in driving the AC rotating machine with known or unknown electrical constant. In the control device, a frequency correction value arithmetic unit has an amplification gain computing element for computing an amplification gain based on an electrical constant of the AC rotating machine and an amplifier for computing a frequency correction arithmetic value based on the amplification gain computed by the amplification gain computing element and the current of the AC rotating machine, in which the frequency correction arithmetic value is outputted as a frequency correction value in a predetermined running state of the AC rotating machine.

Abstract: A control system controls a multiphase rotating machine by a 120° energization process and a PWM process. In the 120° energization process, respective ones of switching elements of a high side arm and switching elements of a low side arm of a power conversion circuit are turned on. In the PWM process, the switching elements of the power conversion circuit turn on/off so that two phases that are connected to the switching elements that are in the on-state are alternately rendered conductive to the high potential side input terminal and the low potential side input terminal of the power conversion circuit.

Abstract: A damper system for a vehicle including an electromagnetic damper, wherein the electromagnetic damper includes: (i) an electromagnetic motor; (ii) a motion converting mechanism; and (iii) an external circuit including (A) a first connection passage, (B) a second connection passage, (C) a first-connection-passage-current adjuster, and (D) a second-connection-passage-current adjuster, wherein the damper system comprises an external-circuit controller including: (a) a main-adjuster control portion configured to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as a main adjuster, a first control for mainly damping the relative vibration of the sprung portion and the unsprung portion; and (b) an auxiliary-adjuster control portion configured to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as an auxiliary adjuster, a second control for assisti

Abstract: First and second A/D converters perform analog/digital conversion of first and second signals of a Hall signal so as to generate third and fourth signals as digital signals. A differential conversion circuit generates a fifth signal as a single-ended signal that corresponds to the difference between the third and fourth signals. An offset correction circuit corrects offset of the fifth signal so as to generate a sixth signal. An amplitude control circuit stabilizes the amplitude of the sixth signal to a predetermined target value, and generates its absolute value, thus generating a seventh signal. A control signal generating unit generates a control signal based upon the seventh signal. A driver circuit drives a motor according to the control signal.

Abstract: The actuation system including a control system, an actuator comprising a drive part and a step motor comprising a rotor and a stator with at least one electric phase, an actuated system comprising a controlled element coupled to the drive part, and an elastic part capable of generating an elastic return force on the rotor of the motor or on the drive part. The control system comprises means for measuring an induced electric parameter on the phase of the stator after switching off the current of said at least one phase of the stator to detect a return of the rotor resulting from elastic return force when a mechanical clearance is overtaken.

Abstract: A control system controls a multiphase rotating machine by a 120° energization process and a PWM process. In the 120° energization process, respective ones of switching elements of a high side arm and switching elements of a low side arm of a power conversion circuit are turned on. In the PWM process, the switching elements of the power conversion circuit turn on/off so that two phases that are connected to the switching elements that are in the on-state are alternately rendered conductive to the high potential side input terminal and the low potential side input terminal of the power conversion circuit.

Abstract: An apparatus for controlling a boost converter is provided with: an operating device provided with a proportional element, an integral element and a derivative element, the derivative element being configured as a bandpass filter, the operating device calculating a PID controlled variable corresponding to an electric current command value of the boost converter; a controlling device for controlling the output voltage of the boost converter on the basis of the calculated PID controlled variable; a judging device for judging whether or not loss suppression on the direct current power supply is to be prioritized; and a switching device for switching an operation mode of the operating device from a variation suppression mode to a loss suppression mode if it is judged that the loss suppression is to be prioritized. In the loss suppression mode, a cutoff frequency of the bandpass filter is corrected to a lower frequency side at a lower rotational speed of the three-phase alternating current motor.

Abstract: There is provided a method of detecting a stop of a transport apparatus which can quickly and easily detect and improve the throughput and the ratio of utilization without incurring an increase the number of parts. The apparatus is used which is provided with a drive motor and a transport arm one side of which is mounted on a rotary shaft of the drive motor. As the drive motor there is used one in which an induced electromotive force is generated when a force in the direction of rotation is applied to the rotary shaft. Then, an article S to be transported is held on the other side of the transport arm. When the drive motor is operated to drive the rotary shaft by a predetermined angle of rotation and then stopped, the above-described induced electromotive force to be generated due to the vibrations of the transport arm is detected.

Abstract: The invention relates to a method for obtaining a criterion for detecting obstacles in a closure movement of a motor-driven opening. The obtaining method includes the step of determining a speed of rotation of a motor shaft and the step of determining a quantity representative of a motor voltage. The detection criterion is then obtained by a step for calculating the criterion according to the speed of rotation of the motor shaft and the quantity representative of the motor voltage. This makes it possible to obtain a criterion, which is both robust and inexpensive, for detecting obstacles in a closure movement of a motor-driven opening.

Abstract: In a drive of a stepping motor, an electromotive force is generated on the coil of a motor with a sinusoidal wave having the same period as an energization period by smoothly rotating a rotor with microstep driving, and an induced power is stably detected by detecting the electromotive force at the zero cross of driving current. The detection around the current zero cross makes it possible to shorten a detection section, form a driving waveform with few distortions, and perform driving with a driving waveform as in an ordinary micro step. Thus a circuit is provided which is aimed at reducing noise, vibrations, and loss of synchronization, and increasing current consumption efficiency in the determination of stop.

Abstract: A controller calculates a total power fluctuation including a power fluctuation on a first unit and a power fluctuation on a second unit. The controller estimate a voltage fluctuation of the system voltage based on the total power fluctuation. Then, the controller calculates a control amount for a voltage converter by reflecting the estimated voltage fluctuation. The estimated voltage fluctuation can be used to correct a feed-forward control amount. As a result, a voltage stabilizing control is performed based on the estimated voltage fluctuation which could be occurred in response to the total power fluctuation if no stabilizing control is performed. Thereby, the stability of the system voltage can be improved without using a large size smoothing capacitor.

Abstract: In a motor driving device, a driving switching element is connected in series with a motor between a power source and a ground, and operated by a PWM signal outputted from a control circuit. A return current path forming unit is connected in parallel with the motor to allow a return current when the driving switching element is turned off. A series circuit of a current flow restriction element and a switch is connected in parallel with the return current path forming unit. A disconnection determination unit prohibits output of the PWM signal and closes the switch of the series circuit when a voltage applied to the motor does not fluctuate according to the PWM signal, and determines the disconnection of the motor on condition that the voltage detected in that state indicates a change across a second threshold.

Abstract: A system includes a power control module, a period determination module, and a control module. The power control module controls current through stator coils of a motor to rotate a rotor. The period determination module determines a first length of time between a first set of induced stator coil voltages and determines a second length of time between a second set of induced stator coil voltages. The control module determines whether an external disturbance disturbs rotation of the rotor based on a difference between the first and second lengths of time.

Abstract: A motor control system includes a power control module and a detection module. The power control module controls power applied to first and second stator coils of a motor to rotate a rotor. The rotor induces voltages in the first and second stator coils when the rotor is rotating. The detection module determines a first time when a first voltage is induced in the first stator coil and determines a second time when a second voltage is induced in the second stator coil after the first voltage is induced. The detection module determines a speed of the rotor based on a difference between the first and second time. The power control module applies current through the second stator coil a predetermined period after the second time. The power control module determines the predetermined period based on the speed of the rotor.

Abstract: A washing machine and a method for controlling the same are disclosed. The washing machine detects a back electromotive force of a washing motor, and controls output of an alarm sound by analyzing periodicity of a waveform period of the back electromotive force. The washing machine determines whether a child or pet is in a drum washing machine on the basis of the back electromotive force generated from the washing motor, and informs a user or guardian of the determined result.

Abstract: A method for determining gain of a back-electromotive force amplifier may include setting an electric motor into a tri-state function mode and storing a first quasi steady-state value for back-electromotive force from the difference signal, and forcing a reference current through the electric motor and determining a first value of the gain of the amplifier for equaling a difference signal to the first quasi steady-state value. The method may further include setting the electric motor into a tri-state function mode a second time and storing a second quasi steady-state value for back-electromotive force from the difference signal, and increasing the first value of the gain by an amount proportional to a difference between the second quasi steady-state value and the first quasi steady-state value.

Abstract: An information handling system includes a three phase brushless direct current motor and a motherboard which in turn includes a drive circuit. The three phase brushless direct current motor is configured to rotate a cooling fan in the information handling system based on a control signal. The drive circuit is connected to the three phase brushless direct current motor, and the drive circuit is configured to adjust the control signal sent to the three phase brushless direct current motor based on a back electromagnetic flux signal.

Abstract: A control method of a current limit of a DC motor includes generating a reference voltage according to a preset current limit value of a DC motor; comparing the reference voltage with the voltage drop of a power control switch which drives the DC motor to generate a compare result; and controlling the power delivered to the DC motor according to the compare result in order to limit the current of the DC motor.

Abstract: A system includes a power control module, a period determination module, and a control module. The power control module controls current through stator coils of a motor to rotate a rotor. The period determination module determines a first length of time between a first set of induced stator coil voltages and determines a second length of time between a second set of induced stator coil voltages. The control module determines whether an external disturbance disturbs rotation of the rotor based on a difference between the first and second lengths of time.

Abstract: A sensorless method for starting a three-phase brushless direct-current motor includes generating a start-up control signal, a start mode selection signal, and a control signal commutation period; switching to a start mode according to the start mode selection signal; implementing a position aligning procedure according to the start-up control signal and the control signal commutation period; detecting a zero crossing point of back electromotive forces during each control signal commutation period; outputting a sensorless mode selection signal while detecting the zero crossing points of the back electromotive forces during consecutive control signal commutation periods; switching to a sensorless mode according to the sensorless mode selection signal; and detecting a zero crossing point of back electromotive forces in the sensorless mode to determine a starting result of the three-phase brushless direct-current motor.

Abstract: A power conversion device includes a main circuit that has switches connecting each phase of a three-phase AC power supply to each output phase, an LC filter having a reactor and a capacitor connected between the three-phase AC power supply and each bidirectional switch, and a current detector detecting an input current or a load current, and a four-step commutation device generating four steps on the basis of the polarity of the load current. The four-step commutation device sets times between the steps to a value more than zero so as to inhibit open circuit between output phases and short circuit between power supply phases, and sets the times between the steps in accordance with the polarity of the load current so as to cancel a distortion of an output voltage due to four-step commutation during a PWM cycle.

Abstract: The invention relates to electric engineering, in particular to methods for controlling an ac electronic motor. The inventive control method consists in starting and rotating a rotor upon EMF signals in current-free sections of an armature winding, in converting the EMF signals into discrete logical level signals by a normalizer, in detecting switching points by means of a microcontroller and in displacing said points according to a load current quantity, the rotor speed of rotation and the inductance of the armature winding sections, wherein the switching points are calculated and displaced with respect to bridging times of the free sections EMF whose voltage levels are different from zero. The inventive device is characterized in that it comprises a reference level displacing unit (26), which is arranged in the normalizer between a divider 22 and a comparator unit (23) and which consists of a current sensor (27), a voltage sensor (27), two adders (29, 30) and an inverter (31).

Abstract: A method of driving a sensorless brushless motor in PWM mode includes tristating a winding during a time window for detecting a zero-cross of the back electromotive force induced in the winding by rotation of a rotor, monitoring voltage of the tristated winding during an unmasked portion of the time window, and detecting during the time window a zero-cross event of the induced back electromotive force. The method includes verifying whether the zero-cross event occurred during the unmasked portion, modifying for the next cycle the duration of the time window and/or of the unmasked portion thereof based upon the verification, defining a safety interval in the unmasked time window, modifying the duration of the time window and/or of the unmasked portion thereof depending on whether the zero-cross event has been detected during the safety interval.

Abstract: A brushless motor driven by a sensorless driving circuit includes a rotating body capable of being rotated about a center axis; a rotor magnet arranged coaxially with the rotating body; a stator disposed opposite the rotor magnet; and at least one coil wound around the stator. The brushless motor is driven according to a signal containing a third harmonic component relative to a fundamental wave component in an induced electromotive force. Further, an amplitude ratio of the third harmonic component to the fundamental wave component in the induced electromotive force generated in the coil preferably is about 1% or higher.