Abstract: A motor control device and a motor control method are disclosed herein, where the motor control device includes a signal conversion unit, a frequency multiplication unit, a profile generation circuit and a frequency converter unit. The signal conversion unit receives a rotation speed signal from a motor and converts the rotation speed signal into a digital signal. The frequency multiplication unit generates a frequency multiplication signal based on the digital signal. The profile generation circuit performs frequency division on the frequency multiplication signal to get a profile signal. The frequency converter unit generates a reference signal and compares the reference signal with the profile signal to output a motor control signal.

Abstract: An embodiment of the invention provides an AC motor that is driven by an AC voltage. The AC motor includes a motor coil, a switch circuit, a position detector and a controller. The motor coil receives the AC voltage to drive an axis of the motor. The switch circuit is coupled to the motor coil and controls a current passing through the motor coil. The position detector detects the position of a motor rotor to output a polarity signal. The controller controls the switch circuit according to the polarity signal and the AC voltage to make the current to be a first current with a first direction or a second current with a second direction.

Abstract: A signal generating circuit for generating a fan driving signal includes a phase adjusting circuit, a direct digital frequency synthesizer, a first operating circuit, a driving signal generator and a second operating circuit. The phase adjusting circuit receives a hall signal and adjusts a phase of the hall signal to generate a synchronization signal. The direct digital frequency synthesizer generates a modulating signal according to the synchronization signal. The first operating circuit receives a load current and generates a modulated signal according to the load current. The driving signal generator generates an original driving signal according to the synchronization signal. The second operating circuit generates a control signal according to the modulating signal and the modulated signal. The original driving signal is selectively outputted as the fan driving signal in response to the control signal.

Abstract: A power-protection apparatus is provided.

Abstract: An alerting method for fan failure first reads a target value of rotating speed of a fan motor. Predetermining values of each parameters of the fan motor is calculated according to the target value of rotating speed of the fan motor. If a current value of rotating speed of the fan motor is lower than the target value of rotating speed of the fan motor, the failure recorded in a counter is added one time. If a current peak value of the fan motor is higher than a first predetermining current value, the failure recorded in the counter is added one time. If the duration of the current which is higher than a second predetermining current value of the fan motor is higher than a predetermining duration, the failure recorded in the counter is added one time. An alarm signal is sent if the failure recorded in the counter is larger than a predetermining time.

Abstract: A signal generating circuit for generating a fan driving signal includes a phase adjusting circuit, a direct digital frequency synthesizer, a first operating circuit, a driving signal generator and a second operating circuit. The phase adjusting circuit receives a hall signal and adjusts a phase of the hall signal to generate a synchronization signal. The direct digital frequency synthesizer generates a modulating signal according to the synchronization signal. The first operating circuit receives a load current and generates a modulated signal according to the load current. The driving signal generator generates an original driving signal according to the synchronization signal. The second operating circuit generates a control signal according to the modulating signal and the modulated signal. The original driving signal is selectively outputted as the fan driving signal in response to the control signal.

Abstract: A brushless direct current (DC) motor includes a rotor, a stator and a driving unit. The rotor includes a plurality of magnetic poles. The stator includes a plurality of upper pole arms and a plurality of lower pole arms. The driving unit includes at least two coils wound on the upper pole arms and the lower pole arms respectively, and the driving unit generates an alternating magnetic field on the stator for driving the rotor.

Abstract: A motor control device and a motor control method are disclosed herein, where the motor control device includes a signal conversion unit, a frequency multiplication unit, a profile generation circuit and a frequency converter unit. The signal conversion unit receives a rotation speed signal from a motor and converts the rotation speed signal into a digital signal. The frequency multiplication unit generates a frequency multiplication signal based on the digital signal. The profile generation circuit performs frequency division on the frequency multiplication signal to get a profile signal. The frequency converter unit generates a reference signal and compares the reference signal with the profile signal to output a motor control signal.

Abstract: A fan control method includes the steps of: acquiring a control factor; determining whether the control factor is located in a first range or a second range; executing a first dust removing mode if the control factor is located in the first range; executing a second dust removing mode if the control factor is located in the second range; and executing a normal mode if the control factor is not located in the first range and the second range.

Abstract: An embodiment of the invention provides an AC motor that is driven by an AC voltage. The AC motor includes a motor coil, a switch circuit, a position detector and a controller. The motor coil receives the AC voltage to drive an axis of the motor. The switch circuit is coupled to the motor coil and controls a current passing through the motor coil. The position detector detects the position of a motor rotor to output a polarity signal. The controller controls the switch circuit according to the polarity signal and the AC voltage to make the current to be a first current with a first direction or a second current with a second direction.

Abstract: An alerting method for fan failure first reads a target value of rotating speed of a fan motor. Predetermining values of each parameters of the fan motor is calculated according to the target value of rotating speed of the fan motor. If a current value of rotating speed of the fan motor is lower than the target value of rotating speed of the fan motor, the failure recorded in a counter is added one time. If a current peak value of the fan motor is higher than a first predetermining current value, the failure recorded in the counter is added one time. If the duration of the current which is higher than a second predetermining current value of the fan motor is higher than a predetermining duration, the failure recorded in the counter is added one time. An alarm signal is sent if the failure recorded in the counter is larger than a predetermining time.

Abstract: A control method of a fan rotation speed, which controls the operation of a fan set including fans connected in series, is disclosed. The control method includes the steps of acquiring a control factor; judging whether the control factor is less than a first threshold value; executing a first control procedure when the control factor is less than the first threshold value; judging whether the control factor is greater than a second threshold value when the control factor is greater than the first threshold; executing a second control procedure when the control factor is greater than the second threshold value; and executing a third control procedure when the control factor is less than the second threshold value.

Abstract: A motor driving circuit includes a detecting unit, a signal control unit, a comparing unit and a driving unit. The detecting unit detects a rotation speed of a motor and thus outputs a detecting signal. The signal control unit generates a reference signal. The comparing unit electrically connected with the detecting unit and the signal control unit, and receives the detecting signal and the reference signal and thus outputs a comparing signal. The driving unit electrically connected with the comparing unit, and receives the comparing signal and thus outputs a driving signal to drive the motor.

Abstract: A fan system including a motor, a driving unit, and a detector is disclosed. The driving unit is electrically connected to the motor and generates a driving signal to drive the motor and a detection signal. The detector is electrically connected to an output terminal of the driving unit and receives a voltage signal and the detection signal. When the motor operates normally, the detector outputs an examined signal to the output terminal of the driving unit. When the motor operates abnormally, the driving unit asserts the detection signal, and the detector is controlled by the asserted detection signal to transform the examined signal to an alarm signal according to the voltage signal to detect the abnormal state.

Abstract: A driving apparatus for fan motors, electrically connected between a pulse width modulation (PWM) signal generator and a controller, includes a converter electrically connected to the PWM signal generator, generating a first reference voltage according to the duty cycle of a PWM signal generated by the PWM signal generator; a reference voltage generator electrically connected to an external power source, generating a second reference voltage according to the external power source; and a comparator having a first and second input terminal and an output terminal; wherein the first input terminal is electrically connected to the converter, the second input terminal is connected to the reference voltage generator and the output terminal is connected to the controller, and when the first reference voltage is greater than the second reference voltage, a driving signal is output from the output terminal to the controller to control the rotation speed of the fan motor.

Abstract: A fan system comprising a first switch, a second switch, a coil, and a drive device. The drive device comprises a third switch and a fourth switch. The third switch, the fourth switch, the first switch, the second switch and the coil form a bridge connection.

Abstract: A brushless direct current (DC) motor includes a rotor, a stator and a driving unit. The rotor includes a plurality of magnetic poles. The stator includes a plurality of upper pole arms and a plurality of lower pole arms. The driving unit includes at least two coils wound on the upper pole arms and the lower pole arms respectively, and the driving unit generates an alternating magnetic field on the stator for driving the rotor.

Abstract: A circuit board adapted to a fan comprises a circuit region and a heat-dissipative film. The circuit region is provided on a first surface of the circuit board and comprises at least one heat-generating component thereon. The heat-dissipative film is coated on an edge portion of the first surface and is in contact with the heat-generating component. A plurality of openings through the heat-dissipative film, a protrusion of the circuit board, a cutout in the protrusion to expose the heat-generating component to airflow, etc., have been disclosed and claimed for enhancing the efficiency in heat dissipation. A heat sink may also be provided on a second surface opposite to the first surface of the circuit board. The heat sink is connected to the heat-dissipative film to help dissipate the heat generated by the operation of the fan.

Abstract: A fan system includes a driving device, a speed detecting device and a logic device. The driving device generates a speed detecting signal and a predetermined alarm signal. The speed detecting device, which is electrically connected with the driving device, receives the speed detecting signal, and generates a low speed signal when the speed detecting signal is lower than a reference signal. The logic device is respectively electrically connected with the driving device and the speed detecting device, and generates an alarm signal when the logic device receives the predetermined alarm signal or the low speed signal.

Abstract: A heat dissipation device for cooling an electronic device. The heat dissipation device comprises a fan, a controller connected to the fan and coupled to the electronic device and a sensor connected to the controller and sending a first signal to the controller by detecting a temperature variation in the electronic device. The electronic device sends a second signal to the controller, the controller changes the speed of the fan according to either the first signal or the second signal.