Abstract: The invention relates to a process for estimating an instantaneous resistance in a phase winding in a reluctance machine. The process comprises the steps of: receiving a signal indicating a voltage across at least one phase winding; receiving a signal indicating a current through the phase winding; estimating a magnetic flux in response to the voltage signal and the current signal; estimating an instantaneous resistance in the phase winding in according with a phase relation between the current signal and the magnetic flux signal. The invention also relates to a method for controlling an electrical machine and a drive system for performing the method.

Abstract: A control unit for an electrically retractable door mirror includes a motor to drive rotationally a door mirror to a stored position or a normal position, a change-over switch, and first and second control circuits. The first and second control circuits include electronic switches respectively that are capable of switching on/off depending on the polarity of an electrical signal switched by the change-over switch. Excess current detecting devices, whose electrical resistances grow with an increase in a current, are connected to the electronic switches in series respectively. And, shutoff switches switch off the electronic switches respectively when a voltage generated in the excess current detecting devices exceeds a predetermined value.

Abstract: A thermal control variable-speed circuit without switching noise is connected with a driving circuit, which controls the rotation speed of a fan motor using a driving voltage. The thermal control variable-speed circuit includes a reference voltage output circuit and a driving voltage control circuit. The reference voltage output circuit outputs a corresponding reference voltage signal according to ambient temperature changes. The reference voltage output circuit has one end connected to a first resistor in series and to a second resistor in parallel. The driving voltage control circuit outputs a corresponding driving voltage according to the magnitude of the reference voltage signal.

Abstract: Available torque output from a battery-powered traction motor system in a vehicle is estimated, wherein the system includes a high-voltage battery coupled to a traction motor by an inverter, wherein the inverter is controlled in response to a torque/speed command within an inverter controller, and wherein the system further includes a DC-to-DC converter coupled to the high-voltage battery to provide a reduced voltage to charge a low-voltage battery. Battery operating conditions of the high-voltage battery are determined including available battery power and battery voltage. Traction motor operating conditions including a flux linkage and other electrical parameters are determined. The battery information including voltage, current, and internal resistance is transformed into synchronous coordinates. An available quadrature current corresponding to the maximum available torque is determined in response to the traction motor operating conditions and the battery voltage in the synchronous coordinates.

Abstract: A drive circuit including a motor for positioning a damper from a rest position to a stalled position and protect the drive mechanism from damage due to increased current to the drive motor when the damper stalls by including a current limiter to prevent the current in the motor from exceeding a predetermined value.

Abstract: An electric motor vehicle includes a battery that serves as a driving source for generating electric power, a pair of positive and negative electrode portions respectively connected to a positive electrode and a negative electrode of the battery, a resistor formed of a resistive material, and a first and a second contact portions connected to the resistor. The first and the second contact portion face the positive electrode portion and the negative electrode portion, respectively. The resistor is kept insulated from the battery in a normal operation state of the electric motor vehicle. At least one of the positive electrode, the first contact portion, the negative electrode and the second contact portion is displaced owing to an external force applied to the electric motor in an abnormal operation state such that the electrodes are in contact with their respective contact portions and the positive electrode and the negative electrode are short circuited in an abnormal operation state.

Abstract: An apparatus for controlling a rotational speed of a motor, coupled to a sensing unit capable of outputting a sensing signal. The apparatus includes a controlling unit, coupled to the sensing unit, for outputting a controlling signal according to the sensing signal and independently of the rotational speed of the motor. The controlling signal is a square wave and has a duty ratio that is determined by the sensing signal. The apparatus also includes a driving unit, coupled to the controlling unit, for outputting a driving signal to a motor rotor according to the duty ratio of the controlling signal. The driving signal also is a square wave. The rotational speed of the motor rotor is determined by the duty ratio of the driving signal.

Abstract: A movable barrier operator includes an automatic force incrementing system for adjusting the maximal opening and closing force to be placed upon the movable barrier during a learn operation. The movable barrier operator also includes a control unit with an ambient temperature detector which controls the motor to move at a specified force and is used to inhibit motor operation depending on the motor temperature derived from the temperatur detected by the temperature detector.

Abstract: A driving apparatus having driving device and a driven portion to be driven by the driving device, is provided with: an information obtaining device which obtains at least one of temperature information inside or around the apparatus, humidity information inside or around the apparatus, or voltage information inside the apparatus; an action amount monitoring device which monitors an action amount of the driven portion; and an error detection device which refers to a different action amount error detection value according to a value related to the obtained information and detecting an action amount error of the driven portion based on the action amount error detection value.

Abstract: A ventilator having a muting device includes a central processing unit, and a fan motor. The fan motor is connected to a start capacitor which is electrically connected to a temperature sensing circuit which is electrically connected to the central processing unit, so that the start capacitor can indicate a signal on a panel of the ventilator, so as to control a rotational speed of the fan motor. Thus, the operation state of each part of the ventilator is indicated on the panel of the ventilator clearly to facilitate inspection of the user, so that the user can control the rotational speed of the fan motor to a proper value, thereby reducing the noise during operation, so as to achieve a muting effect.

Abstract: A temperature sensor (33) detects the temperature of a MOS transistor (7), and a current detecting circuit (35) detects current flowing in the MOS transistor (7). When the voltage corresponding to the detected temperature or the voltage corresponding to the detected current is increased to a threshold value or more, an overheat state detecting signal and further switching signal is set to a high level. As a result, a switch circuit in a driving circuit (17) is turned on, and the gate resistance value becomes the parallel value of a resistor (25), and the PWM frequency in the PWM control circuit is lowered, whereby the switching loss of the MOS transistor (7) can be reduced under the state that the motor (2) is rotated.

Abstract: A method for controlling heat dissipation of an electronic device, such as a central processing unit, by controlling rotational speed of a fan and supplying a clock signal with slower clock frequency to the electronic device is disclosed. The fan rotates at a speed in proportion to the temperature of the electronic device when the temperature of the electronic device is below a maximum reference temperature. The fan rotates at a maximum rotational speed when the temperature of the electronic device is beyond the maximum reference temperature. The fan rotates at a maximum rotational speed and a clock signal with slower clock frequency is supplied to the electronic device when the temperature of the electronic device is beyond both the maximum reference temperature and a slowing-clock starting reference temperature, until the temperature of the electronic device drops below a slowing-clock ending reference temperature.

Abstract: The invention relates to a regulating device (1) for a motor, comprising a housing (2) which can be associated with said motor and in which a control unit (5) and an actuator (6) are arranged. Due to heat-related reasons, said device can only be used in an encapsulated manner, for example close to a motor. In order to solve this problem, the actuator (6) comprises an electromagnetic switching element (8a,8b) and the control signal (7) for the same is designed as a timing signal which is measured—taking into consideration at least one heat source inside or optionally outside the housing (2)—in such a way that the operating temperature of the electromagnetic switching element (8a,8b) is below an upper authorised limiting value.

Abstract: Temperature of the disk drive is measured using components of the disk drive without the need of including a separate temperature sensor to optimize performance of the spindle motor during startup. To measure temperature, the resistance of the VCM winding is measured and used to estimate the spindle bearing temperature. Back emf is measured from VCM windings and used during startup to accurately determine actuator position. Because the VCM coil resistance varies significantly with temperature, coil resistance variations with temperature are determined to enable compensation for inaccuracies in determination of actuator velocity. This inferred temperature is then used to optimize the start up procedure for the spindle motor to accommodate the increased frictional loading of the spindle bearing. In this way an improved performance in the reliability and spin up operation time can be realized without the addition of a separate temperature measurement hardware element.

Abstract: Temperature of the disk drive is measured using components of the disk drive without the need of including a separate temperature sensor to optimize performance of the spindle motor during startup. To measure temperature, the resistance of the VCM winding is measured and used to estimate the spindle bearing temperature. Back emf is measured from VCM windings and used during startup to accurately determine actuator position. Because the VCM coil resistance varies significantly with temperature, coil resistance variations with temperature are determined to enable compensation for inaccuracies in determination of actuator velocity. This inferred temperature is then used to optimize the start up procedure for the spindle motor to accommodate the increased frictional loading of the spindle bearing. In this way an improved performance in the reliability and spin up operation time can be realized without the addition of a separate temperature measurement hardware element.

Abstract: A method and apparatus for providing an obstacle detection system for a vehicle having an automated door or moveable panel, the detection system having a sensing system including a plurality of emitters and detectors disposed proximate to the automated moveable panel or door of the vehicle and a detection circuit in communication with the sensing system, the detecting detection circuit generating an output signal when an object is detected by the sensing system, the output signal is received by a motor control unit of the moveable panel or door and movement of the moveable panel or door is prevented when the output signal is received.

Abstract: A circuit is arranged control the acceleration of a fan by limiting the rate of change in fan speed control signals. The control system includes an acceleration controller that low pass filters a target fan speed control signal. The low pass filtering signal minimizes abrupt changes in the fan speed. A sudden change in the speed of the fan often results in an audible noise that is undesirably distracting. Filtering the fan speed control signal advantageously slows the rate of the fan speed changes without having to change device drivers for controlling the fan.

Abstract: A driving apparatus of a motor capable of operating a motor of a reciprocating compressor stably by using a simple power voltage control unit. The apparatus includes a power voltage control unit for maintaining a power voltage supplied from a power supply unit as a certain value when a motor is operated, outputting the certain power voltage or cutting off the power voltage after a certain time has passed; and a capacitor for applying the power voltage supplied from the power supply unit to the motor when the power voltage control unit cuts off the power voltage.

Abstract: A simple and economical mechanism providing automatic motor control. The mechanism includes a motor-rated relay directly connected to line voltage and the input terminal of a motor winding, and receiving a signal from a sensing device connected to line voltage and to a signal input on the relay. The relay and sensing device may be housed within a waterproof enclosure, or may be separately housed within a connection enclosure and a separate sensing device enclosure remote from the connection enclosure, the two enclosures being connected by a cable. The sensing device triggers the relay to control the supply of current to the motor winding.

Abstract: An electronically commutatable motor, in particular for a fluid pump, includes excitation windings that may be connected to and disconnected from a DC supply voltage via semiconductor switches that are controlled by control signals of a commutation device. Additional closed- and/or open-loop control of the output of the motor, is obtained with a temperature protection system in that the control signals of the commutation device are clocked by pulse width modulatable output signals of a PWM generator and in that the pulse width ratio of the output signals of the PWM generator may additionally be modified as a function of the output signal of the temperature sensor.

Abstract: A control circuit of a fan having an accessory lamp includes a lamp, a lamp circuit, a fan motor, a fan circuit, and a capacitor. The capacitor is mounted between the lamp and the fan motor. By using the relationship of the impedance of the capacitor, the lamp and the fan motor, operation of the lamp may start the fan motor automatically, and operation of the fan motor will not start the lamp.

Abstract: A fan motor speed control system for controlling the fan motor speed of an air conditioning system includes a power output circuit including a power triac which is turned on and off by an opto-isolator connected to a pulse generator circuit for varying an AC voltage waveform imposed on the fan motor. The pulse generator circuit is connected to heating and cooling ramp circuits and a minimum speed circuit to provide a variable voltage signal imposed on the pulse generator circuit corresponding to the temperature difference sensed by a return air sensor and a heating or cooling sensor or by separate heating and cooling sensors disposed adjacent respective heating and cooling heat exchangers of the air conditioning system. An adjustable minimum speed circuit and a cutoff circuit are provided to control motor minimum speed or motor shutoff when a predetermined minimum speed is reached to prevent motor bearing failure or overheating.

Abstract: A forced air heating and/or cooling system utilizing an induction type fan motor is controlled by a controller circuit which is operable to continuously vary the speed of the fan motor during a start-up phase and a shut-down phase of the heating and/or cooling cycle. The controller circuit includes terminals for connection to the source of electrical energy for the heating and/or cooling system and for connection to the system controls without altering the control function or circuitry thereof. The controller circuit includes temperature sensors which are operable to control start-up and shutdown of the fan motor over continuously variable speed operating cycles in response to sensed temperature of the air being circulated by the fan.

Abstract: A fan speed control system (200) for an electronic equipment enclosure comprises means for determining temperature (201, 202, 203, 210, 211) at a plurality of locations within the enclosure, means for determining operating parameters (201, 202, 203, 212) for the fan control system, means for setting operating speed (201) of at least one cooling fan, and means for exchanging information signals (205, 217, 218) relating to fan speed control system operation with an external controller. A method is also provided for controlling fan speed for an electronic equipment enclosure comprising the steps of determining temperature at a plurality of locations within the enclosure, determining operating parameters for the fan control system, setting operating speed of at least one cooling fan, and exchanging information signals relating to fan speed control system operation with an external controller.

Abstract: A motor monitoring system including a control chip and a motor is disclosed. The control chip could be a chipset or a monitoring chip able to control the rotational speed of the motor. The control chip is used to receive a temperature reading and output a control signal according to the temperature reading. The motor receives the control signal and automatically adjusts the speed of its own accordingly. Hence, the configuration of the monitoring system is simplified, the R&D flow is shortened, and the cost of R&D and manufacturing are greatly reduced.

Abstract: The motor-generator circuitry of a flywheel energy conversion device can be utilized to preheat the rotor of the flywheel device. It may be desirable to preheat the rotor prior to normal operation because a rotor operating in cold temperature may be more susceptible to brittle fracture or other damage than a rotor operating at a specified operating temperature. The present invention may utilize the principle of induction heating to preheat the rotor. In preferred embodiments, high frequency current may be passed through armature windings of the motor-generating circuitry to induce surface currents into the periphery of the rotor. Heat may then be generated in portions of the rotor receiving the induced currents and then radiate from those portions to raise the rotor temperature to a desired level.

Abstract: A method and system of controlling a cooling fan of a computer system including a power supply unit. The method includes sensing a power load of the power supply unit. A reference air temperature of the computer system is also sensed. Finally, a fan setting is determined based upon the sensed power load and the sensed reference air temperature. By basing the fan setting on both reference temperature and actual power supply load, the method and system effectively minimizes cooling fan operation, and thus resulting acoustic noise, when a computer system is operating at less than full capacity. In one preferred embodiment, a look-up table is provided in which a plurality of fan settings are included, each fan setting being based upon a correlation of power supply load and reference temperature. The method and system of the present invention is particularly useful with high-end, server-type computer systems being used for low-end applications, and is readily applied to multiple platforms.

Abstract: An electric motor control unit mounted in an automotive vehicle has a motor (3) that is variable in its rotational speed. A temperature sensing element (18s) is arranged to contact a busbar so that relays (15b) and (15c) permit switching operation in response to detection of abnormal heat generation. This controls an electrical power supply to the motor to decrease the rotational speed of the motor without complete stopping of the motor. The rotational speed of the motor returns to a normal speed from the decreased speed by switching operation of the relays (15b) and (15c) with diminishing of the abnormal heat generation.

Abstract: The invention relates to a motor control circuit for a computer system fan motor, comprising a temperature sensor, a sensor amplifier, a fan command for applying a voltage to the fan motor according to the output of the sensor amplifier, and feedback control means. The circuit of claim also comprises means for stopping the supply of voltage across the fan motor terminals, irrespective of the output of the temperature measuring means. The sensor amplifier allows easy setting of the parameters of the voltage according to the temperature measured by the temperature sensor.

Abstract: A fan speed control system (200) for an electronic equipment enclosure comprises means for determining temperature (201, 202, 203, 210, 211) at a plurality of locations within the enclosure, means for determining operating parameters (201, 202, 203, 212) for the fan control system, means for setting operating speed (201) of at least one cooling fan, and means for exchanging information signals (205, 217, 218) relating to fan speed control system operation with an external controller. A method is also provided for controlling fan speed for an electronic equipment enclosure comprising the steps of determining temperature at a plurality of locations within the enclosure, determining operating parameters for the fan control system, setting operating speed of at least one cooling fan, and exchanging information signals relating to fan speed control system operation with an external controller.

Abstract: A drive circuit including a motor for positioning a damper from a rest position to a stalled position and protect the drive mechanism from damage due to increased current to the drive motor when the damper stalls by including a current limiter to prevent the current in the motor from exceeding a predetermined value.

Abstract: When air passing through a condenser and a radiator passes through a cooling fan in a state where a driving circuit controls a voltage applied to a motor to be constant in accordance with a motor application voltage instructed by a control signal Sa, a motor current Im decreases. A comparator compares the motor current Im with a reference current set on the basis of a motor voltage Vm. When the motor current Im decreases to a value equal to or lower than the reference current, a switching circuit is switched to select an output signal of an operational amplifier. The operational amplifier performs a feedback control so that the motor voltage Vm coincides with a minimum application voltage VL.

Abstract: A drive circuit including a motor for positioning a damper from a rest position to a stalled position and protect the drive mechanism from damage due to increased current to the drive motor when the damper stalls by including a current limiter to prevent the current in the motor from exceeding a predetermined value.

Abstract: A computer system or other electronic system includes a plurality of cooling fans configured to operate in parallel. The cooling fans are operated in a manner to decrease the operating time of a fan. The cooling fans can alternate in operation. Thus, operating time is more equally divided between the two cooling fans and the hours of operation and number of rotations of the fans is more nearly equal. In an embodiment to reduce noise, two fans run at a lower speed instead of one fan at a higher speed. In an embodiment, a fan operates with a reduced speed which maintains a desired operating temperature. In an embodiment a thermal table is stored in BIOS (basic/input output system).

Abstract: A movable barrier operator includes a wall control switch module having a learn switch thereon. The switch module is connectable to a control unit positioned in a head of a garage movable barrier operator. The head unit also contains an electric motor which is connected to a transmission for opening and closing a movable barrier such as a garage door. The switch module includes a plurality of switches coupled to capacitors which, when closed, have varying charge and discharge times to enable which switch has been closed. The control unit includes an automatic force incrementing system for adjusting the maximal opening and closing force to be placed upon the movable barrier during a learn operation. Likewise, end of travel limits can also be set during a learn operation upon installation of the unit.

Abstract: A device to protect fans from overheating and overloading with driving current. The fan protection device of the present invention monitors the temperature and current change of the operating fan. When the temperature or the current float surpasses a predetermined value, the protection device cuts off the fan's power supply and avoids damage to the unit.

Abstract: In the actuator device, there are provided the control means to control the rotation of the rotor axis via the driving means in the housing, the rotor axis rotation displacement detection means for detecting the rotation displacement of the rotor axis in the housing, the rotor axis supported rotation-free, the permanent magnet integrated concentrically with said rotor axis, the magnetic field generation means to generate the magnetic field that makes the permanent magnet generate the rotating power, and a temperature sensor for detecting the temperature of the permanent magnet.

Abstract: There is suggested a simple, cost-effective and secure method for the protection of an electrical motor against thermal overload. For this purpose, a motor equation combining at least one temperature dependent motor parameter and at least one motor characteristic quantity is defined in connection with a motor model for the electrical motor. The presently existing values of the at least one motor characteristic quantity are determined in at least two successive measuring times of a measuring process. The value of the at least one temperature dependent motor parameter is determined in connection with the motor equations for the measuring times of a measuring process. The absolute value of the temperature of the electrical motor is determined in connection with motor equations derived in the measuring times of a measuring process while taking into account the functional relationship between the at least one temperature dependent motor parameter and the temperature.

Abstract: A motor overload coil control is disclosed for use in a motor starter/relay contactor. The control includes an 8-bit, 8-pin microcontroller that together with an I/O reduction circuit, is capable of functioning 13 I/O's with only 5 I/O pins on the microcontroller. Three remote signals are prioritized and reduced on one input line to the microcontroller. The control includes three-phase current measurement from three Hall effect current sensors positioned one on each leg. The system includes current integration to provide a single current input to the microcontroller. A full load amperage (FLA) adjustment allows use on a wide range of motors. The microcontroller uses the FLA adjustment and the current signal to find an appropriate I2t value for real-time monitoring of the operating temperature of the motor. A status indicator is provided having an LED output to show the status of the system and indicate the motor temperature, when appropriate.

Abstract: A head gear apparatus (10) is provided that moves air to cool a caregiver's head. The head gear apparatus (10) includes a helmet (12) that has a shell (114) configured to rest upon a head of a user and a fan housing (120) movably coupled to shell (114), a fan (122) is positioned to lie within fan housing (120) and moves with fan housing (120) relative to shell (114), and a garment (14) selectively coupled to helmet (12). Garment (14) includes a face shield (20).

Abstract: A motor for moving a flap for distributing a flow of air in a duct of a heating, ventilation and/or air conditioning installation is supplied with voltage. A power-regulation module is mounted in series with the motor, and includes at least one positive-temperature-coefficient resistor, so that, when the flap reaches an open or closed position, the motor is blocked. This results in an increase in the current strength in the circuit, causing an increase in the value of the resistance, and this results in a reduction in the current strength and in the voltage at the terminals of the motor.

Abstract: The present invention provides a fan installation for a cooling system of a motor vehicle, comprising at least two fans which respectively have an electric fan motor arranged in a separate housing and a fan wheel which can be driven by the fan motor. The fan installation also comprises a control unit for operating the fan motors. The invention provides for an improved fan installation with a simple and cost-effective design, which is achieved by arranging the control unit in the housing of one of the fans for operating both fan motors.

Abstract: A start-up switch 50 for an electric motor 1 comprises a resistive element (54) which is so constituted as to be connectable to an electric current path (15) and which has such a characteristic that its resistance value increases by the heat generated by electric current that flows through the electric current path (15) and a thermostatic switch (60) which is connected in series with the resistive element (54). The thermostatic switch (60) has an actuation member (60) which is responsive to temperature so that upon reaching a preselected temperature, said member moves from a closed current path position to an open current path position. The thermostatic switch (60) is positioned to be in direct heat transfer relationship with the resistive element (54) so that the member will (66) rise in temperature as the resistive element (54) rises in temperature.

Abstract: An actuator for an HVAC system includes a motor coupled by a gear train to an output connector. A spring coupled to the gear train stores energy when the motor is driven in one direction and releases stored energy when the motor is driven in the opposite direction. The spring returns the output connector to a normal position in the event that electrical power is lost. A motor stall current threshold for the motor is determined dynamically in response to operation of the actuator. The position of the spring, direction of motion and the temperature are sensed. The motor stall current threshold value is selected from a table in response to the values of the sensed operating parameters. A determination is made that the motor has stalled when the electric current applied to the motor exceeds the selected motor stall current threshold value.

Abstract: The temperature (25, 33, 43) of solid state switching devices in variable speed motor drives (11, 18), such as elevator motor drives, are utilized to reduce the load on the drive, by reducing the switching frequency (50) or the commanded load (110). The choice between the preferred non-switching zero state and an alternative zero state is determined (60) by temperature (28, 34, 56) of the switched transistor's anti-parallel diode. The rate of recognizing reduced temperatures is limited (33, 34) to avoid motor speed and/or load variations. The temperature may either be measured (24, 27) or determined (70) from models utilizing manufacturer product specification and normalized thermal transient response from the transistor/diode package to a heat sink.

Abstract: In a machine tool controlled by using a numerical control device, a correction amount is determined for thermal displacement due to heat generation and heat conduction in a spindle motor and a feed shaft motor, in addition to thermal displacement due to heat generated by rotation of a spindle and a feed shaft. A tool position is corrected based on the correction amount. An entire stroke of the feed shaft is divided into a finite number of sections, and for each section, a correction amount for thermal displacement due to axial movement of the feed shaft is determined. The tool position is corrected based on the determined correction amount.

Abstract: An infant incubator of the type having an enclosure within which the infant is held and an air circulation system with a heater and a motor driven blower is disclosed. An adaptive motor speed controller having a sensor providing an indication of the stability of the temperature of the infant is coupled to the blower motor and controls the motor speed at least in part based on the stability of the temperature of the infant. While the infant's temperature is stable, the motor speed is reduced within limits.

Abstract: According to the present invention, it is possible to reduce the fan noise taking the human sense into consideration. Specifically, it is possible to ergonomically mitigate the discomfort due to the short-term variation of the working rate of the CPU by increasing the rotational frequency gradually and by decreasing the rotational frequency with the temperature fall taking the human sense of noise into account. The present invention reduces noise produced by a cooling fan by controlling the fan rotation to a minimum rotational frequency in accordance with the specification and performance of the heat source. Additionally, an embodiment of the present invention controls a cooling fan to a minimum allowable rotational frequency within a rated temperature range of the object to be cooled, thereby controlling the internal temperature of a computer system in such a way to minimize noise generation.

Abstract: An electric motor unit with continuous current containing a connection plate and a card that carries electronics for the control of the motor. The card also contains electronics to monitor the current in order to detect the blockage of the motor's rotor and electronics to control the power supply of the motor. The card and/or the plate carries devices to sense temperature. The electronics to control the power supply are linked to the device(s) sensing temperature, as well as to the electronics monitoring the current. The control electronics cuts off the power supply of the motor when blockage of the motor's rotor is detected and a temperature measured by at least one of the devices reaches a high threshold value and reestablishes the power supply of the motor when the temperature is at or below a low threshold value.

Abstract: A hybrid vehicle includes a power drive unit which is quickly stopped without increasing the load on a motor control apparatus should a short develop inside the power drive unit. The power drive unit contains a self-protection circuit, which shuts off the control signals to the switching elements for a given interval, when the temperature of the switching elements reaches a certain temperature value or when the current flowing in the power drive unit reaches a certain current value. The self-protection circuit outputs a shorting signal to indicate the state of the self-protection caused by the shut off. The motor control apparatus detects shorting signals from the self-protection circuit, and responds by stopping the output of control signals, when the self-protection state is reported, is greater than a predetermined number of times or the cumulative time in the self-protection state reaches a predetermined time.