Abstract: A microcomputer calculates an internal resistance value of a motor, and subsequently calculates an internal resistance value of a switching element of a motor drive circuit. When the internal resistance value of the motor is a semi-abnormal value, the microcomputer sets an upper limit current. When the internal resistance value of the motor drive circuit is a semi-abnormal value, the microcomputer sets an upper limit current. The microcomputer sets a smaller one of the upper limit current and the upper limit current as an upper limit current of the motor. In this manner, the progress of degradation of the motor and the motor drive circuit can be suppressed.

Abstract: An electric vehicle includes a motor unit to drive a wheel. The electric vehicle also includes a control system that controls the motor unit. The control system includes an inverter. The electric vehicle also includes a temperature sensor to sense temperature Tmc of the motor coils of the motor unit or a temperature sensor to sense temperature Tic of the inverter. The electric vehicle also includes a limiter to, if the temperature Tmc sensed by the sensor exceeds a motor coils temperature threshold, reduce a motor current of the unit until a derivative dTmc/dt of the sensed temperature Tmc with time t drops to zero or below, or to, if the temperature Tic sensed by the sensor exceeds an inverter temperature threshold, limit a current command to the inverter until a derivative dTic/dt of the sensed temperature Tic with time t drops to zero or below.

Abstract: A method of controlling a current flowing through a component of a drive comprising the steps of: estimating the current flowing through a component; estimating the temperature of the component; comparing the estimated temperature with a desired maximum temperature for the component; and adjusting the current flowing through the component based on the result of the comparing step.

Abstract: In a vehicle, a control apparatus controls a power converter supplying a rotary machine which can operate as a drive motor of the vehicle, and controls a cooling apparatus for circulating a coolant fluid through the rotary machine and the power converter. When a temporary condition occurs immediately after commencement of the circulation, whereby the temperatures of the coolant fluid and of switching elements in the power converter are judged to concurrently exceed respective specified temperature thresholds, the control apparatus limits the maximum power that can be supplied from the power converter to a lower value than is normally available. When the temperature of the coolant fluid is judged to no longer exceed the corresponding temperature threshold, the limiting is released.

Abstract: A controller controls switching of IGBT devices of an inverter according to the desired output of the permanent magnet motor. The controller includes: a magnet temperature detection device that detects the magnet temperature of the permanent magnet motor based on the output of a temperature sensor; a setting device that sets a threshold value of the magnet temperature corresponding to the desired output of the permanent magnet motor, based on a predetermined relation between the output from the permanent magnet motor and a critical temperature, up to which demagnetization in the permanent magnet motor is not caused; and a carrier frequency control device that, when the magnet temperature detected by the magnet temperature detection device exceeds the threshold value, changes the carrier frequency, at which the IGBT devices are switched, such that a ripple current superimposed on a motor current that flows through the permanent magnet motor is reduced.

Abstract: A motor controller controlling a rotational speed of a motor and including a thermal detector, a capacitor, an operational amplifier (OP), a charging/discharging circuit, a flip-flop and a logic circuit. The thermal detector detects environmental temperature of the motor to set a first reference voltage. The capacitor has one terminal coupled to a second reference voltage while another terminal thereof is charged/discharged by the charging/discharging circuit, controlled by a pulse width modulation (PWM) signal, to provide a third reference voltage. The OP compares the first and third reference voltages and outputs the comparison result to a ‘set’ terminal of the flip-flop. The flip-flop further uses a ‘reset’ terminal to receive a clock signal and the output signal thereof is utilized in generating the PWM signal. The PWM signal is further provided to the logic circuit for setting a duty cycle of a driving current of the motor.

Abstract: A technique for providing a user with effective information in performing an operation is provided in a power tool having a speed change mechanism. A power tool has a speed change mechanism that switches a tool bit 113 from first drive mode in which the tool bit is driven at high speed and low torque to second drive mode in which the tool bit is driven at low speed and high torque, according to load on the tool bit 113. The power tool includes detecting and indicating device 161, 163, 167 that detect a predetermined status condition of the first drive mode and indicate switching from the first drive mode to the second drive mode before switching to the second drive mode.

Abstract: In a power conversion apparatus that is configured to cool switching elements by using a boiling-refrigerant-type cooling device that uses a boiling phenomenon of a refrigerant included therein, an inverter control unit that controls the switching elements (Su to Sz) by generating a gate command capable of stabilizing boiling of the refrigerant includes a modulation-mode selection unit that determines stability of the cooling device based on an element-temperature estimation value that is an estimated temperature of the switching elements (Su to Sz), and that decides and selects a modulation mode PM for controlling the switching elements (Su to Sz) based on a determination result, and a gate-command generation unit that generates a gate command G based on the modulation mode PM selected by the modulation-mode selection unit.

Abstract: Linear actuator device, comprising a housing (102,202), a piston rod (109,209), an electrical motor (116,216) and a transmission means (105,106,305,307) adapted to transfer the rotation of the electrical motor to a linear movement of the piston rod, where the linear actuator device comprises an integrated electrical interface having two signal inputs adapted to extend and retract the piston rod and two signal outputs adapted to indicate a retracted end position (122) and an extended end position (121) of the piston rod.

Abstract: A semiconductor circuit device includes a semiconductor circuit including a switching element, a temperature monitoring unit, and a control unit. The temperature monitoring unit detects or estimates a temperature of a component connected to an inside or an outside of the semiconductor circuit. Here, the temperature of the component changes in accordance with a frequency of a current flowing through the component, and the frequency of the current flowing through the component changes in accordance with a switching frequency of the switching element. The control unit adjusts the switching frequency of the switching element such that the temperature of the component is equal to a target temperature.

Abstract: A load drive control device includes a driver that drives a load which is operable by a DC drive and a pulse modulation drive, a protecting section that detects an electric current flowing in the driver, a temperature detecting section that detects a high temperature state of the driver, and a control section that determines whether the load is operated by the DC drive or the pulse modulation drive, based on outputs from the protecting section and the temperature detecting section. The control section switches the driver in the DC drive and measures the electric current flowing in the driver when a temperature equal to or higher than a predetermined temperature is detected during the pulse modulation drive.

Abstract: A temperature estimation controller and methods are provided for estimating stator winding temperature over a full range of motor operating speeds. In one implementation, the angular velocity of a motor is determined along with a total power loss for each phase of said motor. The total power loss in each phase comprises stator winding power loss and a core power loss. Stator winding temperatures for each phase of motor can then estimated based on the total power loss in that phase, and a combined thermal impedance for that phase. The combined thermal impedance comprises a first thermal impedance between the stator winding and the stator core, and a second thermal impedance between the stator core and the motor coolant.

Abstract: A power conversion device includes a printed circuit board, whose mounting surface is opposite to an annular surface formed by an annular stator that constitutes a motor, arranged to be separated from the annular surface with a predetermined distance, and mounted with a Hall element that detects a rotation position of a rotor of the motor on a mounting surface on a side of the stator; an inverter IC that is mounted on the mounting surface on the side of the stator of the printed circuit board to supply a high-frequency current to the stator; and an overheat detection unit that is mounted on the mounting surface on the side of the stator of the printed circuit board and detects an overheated state of the inverter IC. When the overheat detection unit detects an overheated state, the inverter IC restricts or stops a current to be supplied to the stator.

Abstract: An electric compressor capable of following temperature changes of a power element even if a temperature measurement unit is disposed separately from the power element. In the electric compressor, the temperature measurement unit (34) measures the temperature of a substrate (36) on which the power element (31) is disposed. A rotational speed detection unit (35) detects the rotational speed of a motor. A control unit (33) estimates the temperature of the power element (31) on the basis of the rotational speed of the motor detected by the rotational speed detection unit (35) and the temperature measured by the temperature measurement unit (34).

Abstract: A method and device for protecting a power switching semiconductor inverter from thermal cycling is disclosed. The method compares the actual frequency of the inverter to a low fundamental frequency of the inverter and compares the actual current of the inverter to a continuous current rating of the inverter. A thermal cycling condition is detected if both (a) the actual frequency is lower than the low fundamental frequency and (b) the actual current is higher than the continuous current rating. A thermal cycling fault condition is detected when the inverter has been in the thermal cycling operating condition for a sufficient period of time to cause its present stress factor to exceed a predetermined rated stress factor.

Abstract: A system for controlling fan speed, wherein fans are employed to dissipate heat generated by a plurality of hard disk drives divided into groups, includes a temperature sensor detecting an overall temperature where the hard disk drives are arranged, a control unit obtaining a number of operating hard disk drives in each group, and a baseboard management controller (BMC) storing ratios corresponding to different temperatures and different numbers of operating hard disk drives in each group. The BMC obtains the temperature from the temperature sensor and the number of operating hard disk drives in a group, and obtains a ratio from a preset table according to the temperature and the number of operating hard disk drives in the group, to adjust the speed of the fan.

Abstract: A pulse width modulation (PWM) fan controller includes a sensor, a generator, a selector, and a multiplexer. The sensor is configured for sensing a current temperature of an electronic device. The generator is configured for generating different PWM signals, each of which is suitable for regulating the rotational speed of a fan for dissipating heat for the electronic device of a corresponding temperature. The selector is configured for generating a selection control signal based upon the current temperature of the electronic device. The selection control signal is used for selecting a PWM signal corresponding to the current temperature of the electronic device from the PWM signals from the generator. The multiplexer is configured for performing the selection of the PWM signal.

Abstract: Exemplary surface debris removal systems and methods are operable to remove debris from a signal transmitting/receiving surface. An embodiment provides power to, and then removes power from, a conductive memory wire that is secured to a moveable portion of a two-position snap spring. In response to providing the power to the conductive memory wire, a length of the conductive memory wire decreases so that the moveable portion of the two-position snap spring is pulled from an extended position to a retracted position. When power is removed from the conductive memory wire, the moveable portion of the two-position snap spring moves from the retracted position to the extended position. In response to the moving of the moveable portion of the two-position snap spring from the retracted position to the extended position, an energy is generated and transferred to the surface that dislodges the debris from the surface.

Abstract: A temperature rise of a semiconductor switching element, which is part of a power conversion device such as an inverter, is estimated by an extremely simple method to assess the degradation and remaining lifetime of the semiconductor switching element. In a heat generation amount calculation unit 12 in a calculation processor 3, current command values Id* and Iq* and voltage command values vu*, vv* and vw* are used to calculate a chip loss. First, current values iu*, iv* and iw* of all output phases are estimated from the current command values. The ON/OFF loss of the chip is represented by a function of an estimated value for a current flowing in each output phase, and the loss can be derived by integration with a PWM carrier frequency f. In addition, with respect to a conduction loss, it is necessary to integrate a conduction time with the estimated current value and a saturation voltage, which is a function of the estimated current value.

Abstract: A fan speed control circuit for controlling the rotation speed of a fan motor unit. The speed control circuit includes a resistor, a voltage stabilizing unit, a transistor and a thermal resistor. The resistor is connected to a power source of the fan motor unit, the voltage stabilizing unit is connected between the resistor and ground. The collector of the transistor is connected to the fan motor unit, the base is connected to a node between the resistor and the voltage stabilizing unit. The thermal resistor is connected between an emitter of the transistor and ground.

Abstract: An aircraft engine starting system may comprise a starter motor, a start controller for controlling the starter motor to operate with a desired torque output, and a processor for determining torque profiles for the starter motor. The processor may provide an initial torque profile responsively to ambient condition of the engine. The processor may also provide modifications to the initial torque profile responsively to temperature of the start controller.

Abstract: A motor driving circuit receives a control pulse signal pulse-width modulated according to a target rotational speed, and drives a fan motor. A start pulse signal generating unit generates a start pulse signal having a predetermined duty ratio. A driving unit drives the fan motor by pulse width modulation according to the driving pulse signal received from a control unit. When the duty ratio of the control pulse signal is switched from zero to a nonzero value when the fan motor is in the stopped state, the control unit commences the driving operation for the fan motor. The control unit outputs, as the driving pulse signal, the start pulse signal, in a predetermined start period Ts from the commencement of the driving operation. After the start period elapses, the control unit outputs the control pulse signal as the driving pulse signal.

Abstract: A fan control circuit includes a first switch element, a second switch element, and a fan connector. A first control terminal of the first switch element is connected to a fan control terminal to receive a pulse width modulation signal. A first terminal of the first switch element is connected to a first voltage source. A second control terminal of the second switch element is connected to the first terminal of the first switch element. A fourth terminal of the second switch is connected to a second voltage source via a NTC resistor. A first pin of the fan connector is connected to ground. A second pin of the fan connector is connected to a third terminal of the second switch element. A third pin of the fan connector is connected to a signal receiving terminal. The third pin is configured to receive a feedback signal indicating a rotating speeding of the fan.

Abstract: A circuit for controlling fans of a server computer includes a temperature sensing module configured to sense a temperature inside the server computer and a complex programmable logic device (CPLD) connected to the temperature sensing module. The CPLD includes a pulse width modulation (PWM) module connected to the fans. The PWM module is configured to output a plurality of PWM signals having different duty cycle values to control a rotating speed of each of the fans. The CPLD is configured to determine whether the temperature exceeds a tolerable value.

Abstract: A rechargeable electric power tool includes a motor driven by a secondary battery, a switching element for regulating power distribution to the motor, a motor control unit for controlling rotation of the motor through the switching element, a lead wire for supplying a drive current to the motor therethrough and a trigger switch changed over by a user for turning on or off the drive current supplied to the motor through the lead wire. In the rechargeable electric power tool, upon changeover of the trigger switch, a microcomputer determines a magnitude relation between a detected temperature outputted from a first thermistor and a first temperature threshold value. If the detected temperature is determined to be greater than the first temperature threshold value, the microcomputer is set in a limited operation mode in which a revolution number of the motor is limited to a predetermined value or less.

Abstract: A method for controlling a motor comprises steps of: first, determining whether a switch of a motor control circuit in an electronic system is in a first state; then, operating the motor at a fanless operation mode when a temperature inside an enclosure of the electronic system is higher than zero and lower than a first threshold temperature, wherein the rotation speed of the motor is zero rpm; operating the motor at a silent operation mode when the temperature is higher than the first threshold temperature and lower than a second threshold temperature, wherein the rotation speed of the motor is a constant rotation speed; and operating the motor at a cooling operation mode when the temperature is higher than the second threshold temperature, wherein the rotation speed of the motor is a function of the temperature and varies between the constant rotation speed and a maximum rotation speed.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The rotation rate control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The rotation rate control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The rotation rate control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The rotation rate control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A method of controlling an electrical machine. The electrical machine includes a stator having a core and a plurality of windings, and a rotor disposed adjacent to the stator to interact with the stator. The method includes detecting a movement of the rotor, generating a three phase alternating current (AC) voltage signal by all phases of the electrical machine, monitoring for a transfer speed of the electrical machine, discontinuing the three phase AC voltage signal when the transfer speed is traversed, and switching to a back electromotive force (BEMF) control mode after discontinuing the three phase AC voltage signal.

Abstract: A fan speed control circuit for controlling the rotation speed of a fan motor unit. The speed control circuit includes a resistor, a voltage stabilizing unit, a transistor and a thermal resistor. The resistor is connected to a power source of the fan motor unit, the voltage stabilizing unit is connected between the resistor and ground. The collector of the transistor is connected to the fan motor unit, the base is connected to a node between the resistor and the voltage stabilizing unit. The thermal resistor is connected between an emitter of the transistor and ground.

Abstract: A pulse width modulation (PWM) fan controller is used for an electronic device. The PWM fan controller includes a number of PWM signal generators, a number of PWM signal output elements, and a control unit. The control unit includes a number of outputs. An input of each PWM signal generator is electrically connected to a corresponding output of the control unit. An input of each PWM signal output element is electrically connected to an output of a corresponding PWM signal generator. An output of each PWM signal output element is electrically connected to a corresponding fan of the electronic device. The control unit is configured to control the PWM signal generators to sequentially generate a PWM signal to drive a corresponding fan to rotate in a preset time.

Abstract: The invention relates to improvements in compressors and, in particular, to an improvement in a method of controlling variable speed dynamic compressors to avoid ‘motor overload as a result of choking.1 The invention therefore comprises a method of controlling a compressor to provide compressed gas at a target delivery pressure (Pt) and prevent excessive motor power consumption, the compressor being driven by a variable speed motor which has motor windings, wherein the gas inlet temperature (Tin), gas output delivery pressure (Pd), motor speed (Vm) and the motor winding temperature (Tmw) are continuously measured during operation of the compressor. The gas inlet temperature (Tin) is used to determine a predetermined maximum motor winding temperature (Tmwmax) limit. The maximum motor winding temperature (Tmwmax) is used (to set a maximum motor speed (Vmmax) limit.

Abstract: A cooling system is provided with a motor drive device, a fan motor, and a Hall element. The motor drive device includes a lock protection circuit and a lock controller. When a control signal instructing rotation of the fan motor that is to be driven instructs stoppage of the motor for a predetermined time-period or longer, the lock controller has the lock protection circuit inactive. At an occasion when the control signal has continued to instruct stoppage of the fan motor for a first time-period or longer, a standby controller starts time measurement, and after a further predetermined second time-period has elapsed, makes at least a part of the motor drive device transition to a standby mode.

Abstract: A cooling system includes a cooling duct extending between a first component and a second component of a machine. A motor powered fan in the cooling duct creates an airflow in the duct. First and second temperature sensors are disposed to measure, respectively, first and second temperatures, which are associated with first and second temperature limits in first and second components. An electronic controller provides a motor command signal, receives the first and second temperatures, calculates first and second temperature differences to generate first and second blower commands based on the respective temperature differences, and calculates a feed-forward blower motor command based on a machine load factor. The electronic controller selects the greater of the first blower command, the second blower command, and the feed-forward blower command to be a maximum command, and determines and provides the motor command signal to the motor based on the maximum command.

Abstract: A pulse width modulation (PWM) fan controller includes a sensor, a generator, a selector, and a multiplexer. The sensor is configured for sensing a current temperature of an electronic device. The generator is configured for generating different PWM signals, each of which is suitable for regulating the rotational speed of a fan for dissipating heat for the electronic device of a corresponding temperature. The selector is configured for generating a selection control signal based upon the current temperature of the electronic device. The selection control signal is used for selecting a PWM signal corresponding to the current temperature of the electronic device from the PWM signals from the generator. The multiplexer is configured for performing the selection of the PWM signal.

Abstract: A method for controlling fan speed is disclosed. Firstly, a number of temperature ranges are defined. Each temperature range is associated with a corresponding fan speed. Each two adjacent temperature ranges overlap. The temperature of an electronic system is measured and is compared with the defined temperature ranges to determine whether it enters into a new range. If the measured temperature exceeds any one of the limits of a temperature range associated with the current fan speed, it enters into a new temperature range. The fan speed is adjusted to which is associated with the new entered temperature range. The overlap of each two adjacent temperature ranges covers the fluctuation of the temperature of the electronic system caused solely by the adjustment of fan speed caused by the traversing of the measured temperature between the two adjacent temperature ranges.

Abstract: A fan duty cycle controlling system and method are implemented by a computing device. The fan duty cycle controlling system obtains an optimum duty cycle range of a fan around a central processing unit (CPU), and controls the fan to operate at the optimum duty cycle range. By implementing the system and method, the computing device can obtain an optimum cooling efficiency of the computer system, and reduce system noise generated by the fan when the fan operates at the optimum duty cycle range.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The rotation rate control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The rotation rate control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The rotation rate control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The rotation rate control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A fan delay controlling apparatus includes a connector connected to a fan of an electronic device, a power supplying module connected to the connector, and a power controlling module connected to the power supplying module. The power supplying module is connected to a fan power source and a stand-by power source. The power controlling module controls the power supplying module supply power to the fan when the electronic device including the fan powers off until an ambient temperature is lower than a predetermined value.

Abstract: A motor control system for heating, ventilation, and air conditioning (HVAC) applications is described. The motor control system includes a thermostat and an electronically commutated motor (ECM) coupled to the thermostat. The ECM is configured to retrofit an existing non-ECM electric motor included in an HVAC application and to operate in one of a plurality of HVAC modes. The HVAC modes include at least one of a heating mode, a cooling mode, and a continuous fan mode. The HVAC mode is determined based at least partially on outputs provided by the thermostat.

Abstract: A fan speed control circuit includes a voltage input terminal, a thyristor, a thermistor, and first and second switches. The terminal is grounded through a first resistor and the thermistor, connected to an anode of the thyristor, and connected to a second terminal of the second switch through a second resistor. A node between the resistor and the thermistor is connected to a control terminal of the first switch. A second terminal of the first switch is grounded. A first terminal of the first switch is connected to a control terminal of the thyristor through a third resistor. A fourth resistor is connected between the anode and control terminal of the thyristor. A control terminal of the second switch is connected to the control terminal of the thyristor. A first terminal of the second switch is connected to a cathode of the thyristor and a voltage pin of a fan.

Abstract: A circuit for controlling a rotation speed of a computer fan includes a control chip, a conversion circuit, a fan header, a first switch, and a second switch. When a first terminal of the first switch is connected to a second terminal of the first switch, and a first terminal of the second switch is connected to a second terminal of the second switch, the conversion circuit converts a control signal received from the control chip to a voltage signal, and outputs the voltage signal to a power pin of the fan header. When the first terminal of the first switch is connected to a third terminal of the first switch, and the first terminal of the second switch is connected to a third terminal of the second switch, a control pin of the fan header receives the control signal, the power pin receives power from a first power supply.

Abstract: A load drive control device includes a driver that drives a load which is operable by a DC drive and a pulse modulation drive, a protecting section that detects an electric current flowing in the driver, a temperature detecting section that detects a high temperature state of the driver, and a control section that determines whether the load is operated by the DC drive or the pulse modulation drive, based on outputs from the protecting section and the temperature detecting section. The control section switches the driver in the DC drive and measures the electric current flowing in the driver when a temperature equal to or higher than a predetermined temperature is detected during the pulse modulation drive.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A motor controller controlling a rotational speed of a motor and including a thermal detector, a capacitor, an operational amplifier (OP), a charging/discharging circuit, a flip-flop and a logic circuit. The thermal detector detects environmental temperature of the motor to set a first reference voltage. The capacitor has one terminal coupled to a second reference voltage while another terminal thereof is charged/discharged by the charging/discharging circuit, controlled by a pulse width modulation (PWM) signal, to provide a third reference voltage. The OP compares the first and third reference voltages and outputs the comparison result to a ‘set’ terminal of the flip-flop. The flip-flop further uses a ‘reset’ terminal to receive a clock signal and the output signal thereof is utilized in generating the PWM signal. The PWM signal is further provided to the logic circuit for setting a duty cycle of a driving current of the motor.

Abstract: A rotation direction control method of a cooling fan is disclosed. The rotation direction control method includes a detection step, a determination step and a driving step. The detection step receives a temperature control signal from a temperature detection unit by a rotation direction control unit when a predetermined dust-expelling time period begins. The determination step determines whether a detected temperature is higher than a predetermined value based on the temperature control signal by the rotation direction control unit. The driving step controls the rotation direction control unit to keep outputting a cooling signal so as to drive a motor of the cooling fan for a cooling operation when the determination of the determination step is positive.

Abstract: An apparatus and method controls a speed of a fan in a computer. The apparatus includes a signal generator, a signal buffer, a signal switch, and an integrated baseboard management controller (IBMC). The IBMC includes a general purpose input output (GIPO) pin and a signal output port. The IBMC determines whether the IBMC operates normally by detecting a voltage status of the GIPO pin. The signal generator generates a first pulse width modulation (PWM) signal according to a system temperature of the computer when the IBMC does not operate normally. The IBMC generates a second PWM signal to according to the system temperature of the computer when the IBMC operates normally. The signal switch controls the speed of the fan according to the first PWM signal or the second PWM signal.

Abstract: A fan drive circuit for driving a fan used in an electronic device to rotate includes a heat detector, a control unit, an integrating circuit, a regulating circuit; and a power supply. The power supply cooperates with the regulating circuit to drive the fan to rotate, the control unit detects the temperature of the one or more components of the electronic device using the heat detector and cooperates with the integrating circuit to generate a speed control voltage that changes with change of the temperature, and the speed control voltage is input to the regulating circuit to regulate a rotation rate of the fan.

Abstract: A fan system includes a pulse signal generation portion and a plurality of fans. Each of the plurality of fans preferably includes a motor portion; an impeller arranged to be rotated by the motor portion; a drive circuit arranged to drive the motor portion; a rotation detection portion arranged to detect rotation of the motor portion; and a rotation rate control circuit arranged to, based on a reference pulse signal supplied from the pulse signal generation portion and an actual rotation pulse signal supplied from the rotation detection portion, exercise feedback control on a rotation rate of the motor portion in accordance with a period of the reference pulse signal.