Abstract: A method for controlling a driving circuit. A first switch unit comprises a first switch and a second switch and a second switch unit comprises a third switch and a fourth switch. The first and second switch units are alternately turned on, and each switch is coupled to a blocking element in parallel. The first and second switches of the first switch unit are turned on simultaneously, and the first switch is then turned off. The second switch is turned off when the third and fourth switches are simultaneously turned on.

Abstract: An overvoltage protective device for DC motor is disclosed. The device includes a voltage-dividing circuit and a control unit, and is electrically connected to a DC motor in parallel. The voltage-dividing circuit has one end thereof electrically connected to an input voltage of the DC motor, and the other end thereof grounded. The control unit is electrically connected to a part of the voltage-dividing circuit for accessing a voltage level thereof and thereby driving the DC motor.

Abstract: Motors comprising stators and rotors having a plurality of north poles and south poles and methods of controlling the same. A first sensor and a second sensor are provided. The first and second sensors are disposed on the stator in a manner that the first and second sensors never simultaneously detect boundaries between the north and south poles during rotation of the rotor. If any one of the first and second sensors continuously detects a north pole or a south pole for a predetermined duration, the motor is shut off.

Abstract: A level-determining device of pulse width modulation (PWM) signal includes a PWM signal generating circuit, a reference voltage generating circuit and a determining circuit. The PWM signal generating circuit generates a first PWM signal. The reference voltage generating circuit generates a reference voltage signal. The determining circuit is respectively electrically connected to the PWM signal generating circuit and the reference voltage generating circuit for determining high level or low level of the first PWM signal in accordance with the reference voltage signal for generating a second PWM signal.

Abstract: A fan control system. The system includes a plurality of fans, each having a control device. One of the fans is designated as a master fan and others are served as slave fans according to a specific designation method, wherein the control device of the master fan actively monitors and controls the operating state of the slave fans according to the control device of the slave fans to amend the operating state of all fans.

Abstract: A fan control system. The system includes a plurality of fans, each having a control device. One of the fans is designated as a master fan and others are served as slave fans according to a specific designation method, wherein the control device of the master fan actively monitors and controls the operating state of the slave fans according to the control device of the slave fans to amend the operating state of all fans.

Abstract: A fan control system. The system includes a plurality of fans, each having a control device. One of the fans is designated as a master fan and others are served as slave fans according to a specific designation method, wherein the control device of the master fan actively monitors and controls the operating state of the slave fans according to the control device of the slave fans to amend the operating state of all fans.

Abstract: A fan control system. The system includes a plurality of fans, each having a control device. One of the fans is designated as a master fan and others are served as slave fans according to a specific designation method, wherein the control device of the master fan actively monitors and controls the operating state of the slave fans according to the control device of the slave fans to amend the operating state of all fans.

Abstract: A method for controlling a driving circuit. A first switch unit comprises a first switch and a second switch and a second switch unit comprises a third switch and a fourth switch. The first and second switch units are alternately turned on, and each switch is coupled to a blocking element in parallel. The first and second switches of the first switch unit are turned on simultaneously, and the first switch is then turned off. The second switch is turned off when the third and fourth switches are simultaneously turned on.

Abstract: Motors comprising stators and rotors having a plurality of north poles and south poles and methods of controlling the same. A first sensor and a second sensor are provided. The first and second sensors are disposed on the stator in a manner that the first and second sensors never simultaneously detect boundaries between the north and south poles during rotation of the rotor. If any one of the first and second sensors continuously detects a north pole or a south pole for a predetermined duration, the motor is shut off.

Abstract: A fan control system. The system includes a plurality of fans, each having a control device. One of the fans is designated as a master fan and others are served as slave fans according to a specific designation method, wherein the control device of the master fan actively monitors and controls the operating state of the slave fans according to the control device of the slave fans to amend the operating state of all fans.

Abstract: An overvoltage protective device for DC motor is disclosed. The device includes a voltage-dividing circuit and a control unit, and is electrically connected to a DC motor in parallel. The voltage-dividing circuit has one end thereof electrically connected to an input voltage of the DC motor, and the other end thereof grounded. The control unit is electrically connected to a part of the voltage-dividing circuit for accessing a voltage level thereof and thereby driving the DC motor.