Abstract: A phase loss detection device, a compressor including the same, and a phase loss detection method are disclosed. The phase loss detection device may include a signal converting circuit and a processor. The signal converting circuit is configured to convert voltage signals corresponding to respective phases of multiphase alternating current (AC) power monitored from a motor. The processor is configured to receive the converted voltage signals from the signal converting circuit, and configured to calculate, based on the converted voltage signals, one or more phase angles between the respective voltage signals. The processor is configured to determine that phase loss occurs if any one or more of the calculated phase angles deviate from a nominal value of a corresponding phase angle of the multiphase AC power by a value higher than a predetermined threshold. The phase loss detection can be performed in a convenient, effective and reliable way.

Abstract: This disclosure describes electrically powered fluid (liquid) pumps having an electric motor or actuator attached to a power source with a power sensor configured to measure the power draw of the motor while the pump is operating.

Abstract: An electrical power conversion apparatus is obtained in which its devices constituting a DC/DC converter are not required to be large-sized, and a DC capacitor connected between an AC/DC converter and the DC/DC converter can be small-sized. The electrical power conversion apparatus includes a DC capacitor connected between an AC/DC converter and a DC/DC converter, and a control circuit for controlling the AC/DC converter and the DC/DC converter, wherein the control circuit generates an output current instruction of the DC/DC converter by performing superposition of an alternating current instruction on a direct current instruction, and determines an amplitude of the alternating current instruction in accordance with temperature information obtained from a DC-capacitor's temperature acquisition means.

Abstract: This disclosure describes electrically powered fluid (liquid) pumps having an electric motor or actuator attached to a power source with a power sensor configured to measure the power draw of the motor while the pump is operating.

Abstract: An electrical connector includes a male electrical plug, a female socket, a housing, and a control system. The male electrical plug, which is supplied with power, is electrically connected to the female socket. The housing contains the male electrical plug, the female socket, and a control system. The control system includes a temperature sensor and a transceiver with the temperature sensor sensing a temperature at a location within the housing and the transceiver transmitting a signal representative of the temperature to an alarm device remotely located from the electrical connector. The electrical connector can include one or more switches that are remotely controllable by the alarm device to interrupt the electrical connection between the male plug and the female socket.

Abstract: An integrated circuit includes a signal output circuit configured to output a timing signal indicating first and second timings of respectively switching first and second switching devices, first and second hold circuits respectively configured to receive first and second voltages corresponding to temperatures of the first and second switching devices, hold the first and second voltages for first and second time periods, and output the received first and second voltages in response to the first and second time periods having elapsed, and first and second control circuits respectively configured to control switching of the first and second switching devices with first and second driving capabilities corresponding to the temperatures of the first and second switching devices, based on the first and second voltages outputted from the first and second hold circuits and first and second driving signals for driving the first and second switching device.

Abstract: A method for determining information (Info) about a state (Z) of a drive motor system (2) and/or of a drive battery pack (11) of a gardening, forestry and/or construction device (1), includes the steps of: acquiring at least one sensor temperature (TS) of at least one temperature component (3) of the drive motor system (2) and/or of the drive battery pack (11) by way of at least one component temperature sensor (4) at the same time as and/or at a time after operation of the drive motor system (2) and/or of the drive battery pack (11) and/or of a heater (300) and/or of a cooler (310) and/or of a fan (320) for heating and/or for cooling the drive battery pack (11), wherein the temperature component (3) heats up or cools down due to the operation; ascertaining operating data (BD) of the operation, wherein the operating data (BD) are of a different kind than the sensor temperature (TS); comparing the acquired sensor temperature (TS) or a variable based on the sensor temperature and the ascertained operating data

Abstract: A stator for an AC motor, includes windings of a first layer, which extend over a first region of the stator and are connectable to a first phase, and windings of a second layer, which extend over a second region of the stator and are connectable to a second phase, wherein the first region is offset relative to the second region and at least one overlap region is formed which is smaller than the individual regions, and wherein a temperature detection unit is arranged in the overlap region and is designed to measure the temperature of the windings in the overlap region.

Abstract: A flash double-temperature linkage temperature controller has an arrangement that enables contacts of two movable contact sheet sets and two static contact sheet sets to sequentially operate at different temperatures, and a desired fixed temperature difference is obtained. The two movable contact sheet sets are respectively connected to the two static contact sheet sets to control two electric heating tubes, so that the effect whereby two electric heating tubes (high power) work during water heating and a single electric heating tube (low power) works during heat preservation heating is achieved, and the working frequency of the high-power contact sets is greatly reduced.

Abstract: An electric wire protection device includes a voltage adjusting unit that adjusts voltage of a power source side and supplies the resulting voltage to a load, and a controller that includes a calculation unit configured to compute temperature information of an electric wire connecting the power source and the load from a value of an electric current flowing through the voltage adjusting unit, and that is configured to make the voltage adjusting unit into a shutoff state of shutting off the power source and the load on the basis of the temperature information.

Abstract: A system and method of controlling regenerative braking of an eco-friendly vehicle are provided. The system eliminates a motor over-temperature state during regenerative braking, effectively prevents a chattering phenomenon in which regenerative braking torque is repeatedly increased and reduced after the motor over-temperature state, and consequently, improves the braking safety and operability of the vehicle. A torque output rate for motor regenerative braking torque limitation is determined from a current motor load and motor temperature using setting information when a motor over-temperature state is detected. Then, a final regenerative braking torque is determined by multiplying a motor regenerative braking torque, calculated from information including battery chargeable power and a driver braking operation value, by the determined torque output rate. Thereafter, regenerative braking of a motor is adjusted based on the determined final regenerative braking torque.

Abstract: A protector for an electricity supply circuit includes: a power switch for switching between connection and disconnection of the electricity supply circuit; a controller configured to output a switching command signal to the power switch in accordance with an input signal; and a current detector for detecting current flowing to the electricity supply circuit. The controller includes: a lower limit threshold determination unit configured to determine whether or not an estimated temperature of a power line has dropped below a lower limit threshold; a timer for counting the time that passes after a load has been turned off, when the load is turned off by the power switch; and a mode switching unit configured to switch the controller to a sleep mode when a predetermined time is counted by the timer and the lower limit threshold determination unit determines that the estimated temperature has dropped below the lower limit threshold.

Abstract: The invention relates to a method for heating a device driven with a brushless direct current motor, in which method a voltage is applied to stator coils of the brushless direct current motor during a heating phase. The invention further relates to a device for carrying out said method. According to the invention, the stator coils are series-connected during the heating phase. The series connection of the stator coils increases the resistance by a factor of 4.5 compared to a parallel connection of a stator coil with a series connection of two stator coils, as occurs in a brushless direct current motor wired according to the prior art. The heating power is therefore also higher by a factor of 4.5 with the same operating current.

Abstract: A terminal protection method that is applied to a terminal is provided. In the method, an air pressure change value collected by an air pressure sensor is obtained; the air pressure change value is compared with a preset air pressure change threshold; and when the air pressure change value exceeds the preset air pressure change threshold, a break instruction is generated, where the break instruction is used to break a power supply circuit of a mainboard circuit of the terminal. According to the terminal protection method provided in the present invention, the power supply circuit of the mainboard circuit of the terminal can be timely broken when the terminal falls into water, thereby solving a problem of a short circuit that occurs on the mainboard circuit of the terminal after the terminal falls into water.

Abstract: A system and method for controlling engine idle stop in a hybrid vehicle that uses predictive information to schedule engine stops with relatively longer stop duration time to gain more fuel savings and extend life of starter motor. More specifically, predictive information may be used to determine potential vehicle stop events, along with corresponding stop duration times, within a time window. An engine stop scheduler and/or controller may be configured to schedule stops of longer duration for optimal total engine stop time. Similarly, taking into account constraints imposed by the thermal limits of the motor, engine stop may be inhibited for predicted short events to allow engine stop at later longer stop events.

Abstract: Provided is an electric power steering control device which can realize a more appropriate countermeasure against heat in accordance with a thermal characteristic of a component used to supply a motor current. The electric power steering control device for assisting a steering force of a steering wheel of a vehicle including a control unit (10).

Abstract: Temperature protection device for use in an electrical power circuit for protecting said electrical power circuit against heating, comprising a first contact element and a second contact element, which are connected to one another by the ends thereof, and are designed in such a way that the ends of said first and said second contact elements that are connected to one another separate from one another when a limit temperature is exceeded because of a mechanical pretension between the two ends, thereby interrupting the electrical circuit, wherein at least the ends of the contact elements have a material with a higher recrystallization temperature than pure copper.

Abstract: An electric motor (100) having a motor control system (400) including: —a current measuring means (402) for directly or indirectly measuring the electric current in the rotor windings (7) providing a rotor current value/s, —an ambient temperature measuring/estimation means (404) for measuring or estimating the ambient air temperature providing an air temperature value/s, —a rotor temperature estimation means (406, 407, 408, 409, 410, 411) for estimating a rotor temperature at least based on the rotor current value/s and the air temperature value/s, and—a current limiting means (405) for preventing overheating/burning of the rotor assembly (3) by limiting the electric current to the rotor windings (7) when the estimated rotor temperature exceeds a predetermined overheating threshold (412).

Abstract: A system includes a refrigerant compressor including an electric motor, a current sensor that measures current flow to the electric motor, a switching device configured to close and open to allow and prevent current flow to the electric motor, respectively, a maximum continuous current (MCC) device that includes a resistance corresponding to a maximum continuous current for the electric motor, and a motor protection module. The motor protection module communicates with the MCC device, the current sensor, and the switching device and determines a first MCC value for the electric motor as a function of the resistance of the MCC device. The motor protection module also selectively sets a predetermined MCC to the first MCC and controls the switching device based on a comparison of the current flow to the electric motor and the predetermined MCC.

Abstract: Method for diagnosing a fan, in particular in a cooling circuit of an internal combustion engine, a current driving the fan being ascertained. The fan is triggered by a defined trigger signal, and depending on the ascertained current, a diagnosis of whether the fan is defective is performed.

Abstract: A method and system are provided to eliminate the risk of over temperature concerns associated with electrical heating devices, which if undetected may result in an electrical over temperature condition. The electrical heating system may be applied to the detection and control structure of other automotive electrical loads where thermal concerns may exist. The electrical heating system combines several layers of fault detection strategies, to form a unique comprehensive approach to prevent and detect potential electrical fault conditions, which if undetected and/or controlled may result in an electrical over temperature condition.

Abstract: Provided is an electric power steering control device which can realize a more appropriate countermeasure against heat in accordance with a thermal characteristic of a component used to supply a motor current. The electric power steering control device for assisting a steering force of a steering wheel of a vehicle including a control unit (10).

Abstract: There is provided an electronic device that includes a heatsink and a set of IGBTs coupled to the heatsink and configured to deliver power to a field exciter and a battery. The electronic device also includes a temperature sensor disposed in the heatsink and a controller. The controller is configured to receive a temperature reading from the temperature sensor and, based on the temperature reading, determine a junction temperature for at least one of the IGBTs of the set of IGBTs. The controller is also configured to de-rate an output power provided by each of the IGBTs based, at least in part, on the junction temperature.

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 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: The motor monitoring system of the present disclosure uses several calculated monitoring values to determine a status of a motor and take a predetermined action when a threshold corresponding with the monitoring value is exceeded. The threshold may be calculated by an intelligent electronic device (IED) monitoring the motor. The predetermined action may include further monitoring of the motor. The predetermined action may include monitoring equipment not directly monitored by the IED.

Abstract: A motor control circuit 1 for controlling driving of a plurality of motors is provided with a plurality of motor driver circuits 7 and 8 for controlling driving of the plurality of motors 3 and 4, a plurality of excess current detection circuits 39 and 40 each for detecting an excess current flowing through corresponding one of the plurality of motors 3 and 4 to determine which motor driver circuit among the plurality of motor driver circuits 7 and 7 caused the excess current. The motor control circuit further includes a nonvolatile memory 46 configured to receive detection results from the plurality of excess current detection circuits 39 and 40 and store information on which motor driver circuit among the plurality of motor driver circuits 7 and 8 caused the excess current.

Abstract: In an abnormality diagnosing system for first and second current sensors for measuring a current, an obtaining unit obtains at least one pair of measured values of the first and second current sensors. The at least one pair of measured values is measured by the first and second current sensors at a substantially same timing. A diagnosing unit diagnoses whether there is an abnormality in at least one of the first and second current sensors based on a function defining a relationship between the at least one pair of measured values of the first and second current sensors.

Abstract: An electrical switching apparatus is for another apparatus including a number of insulators, a number of temperature sensors operatively associated with the number of insulators, and a number of conductors operatively associated with the number of insulators. The electrical switching apparatus includes a number of separable contacts, an operating mechanism structured to open and close the separable contacts, a number of sensors structured to sense a number of currents flowing through the separable contacts and through the conductors, a processor structured to input the sensed currents from the sensors, and an output. The processor calculates at least one of: (a) a thermal age of the other apparatus from a number of sensed temperatures from the temperature sensors, and (b) the thermal age of the other apparatus from the sensed currents. The output includes the thermal age of the other apparatus.

Abstract: A solid state relay has independent charge pumps isolating each gate of a full bridge to achieve faster and proper gate turn on. The low side MOSFETs of the bridge are the current sensing device reducing loss and allowing a device controlled by the relay to achieve peak performance. Dynamic braking is achieved by the two low side MOSFETs being fully conducted and applying a load across the DC motor. Addition of a microprocessor to the device provides undervoltage sensing, current vs time readings, motor stall sensing, and motor temperature sensing. Motor temperature is detected by checking impedance of the motor at microsecond pulses to see if the motor is getting hot.

Abstract: In a steering control unit, a U-phase feed line branches into paired branch feed lines, phase-open MOSFETs are provided in middle portions of the branch feed lines, phase-open MOSFETs are provided in middle portions of a V-phase feed line and a W-phase feed line, and the phase-open MOSFETs are arranged in such a manner that parasitic diodes are in the same orientation with respect to a motor. When an abnormality occurs, all the phase-open MOSFETs are turned off. Then, a closed circuit, which includes phase coils and through which electric currents flow, is no longer present.

Abstract: A system for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the system including a single-phase line break protector, a first current sensor, and a control module. The single-phase line break protector disconnects the motor from the first phase in response to a temperature being greater than a predetermined temperature threshold. The first current sensor measures a current through the single-phase line break protector. The control module determines a current value based on the measured current, and disconnects the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold.

Abstract: Provided is a power branching system for driving a plurality of motors by use of a single servo driver, the power branching system capable of protecting each of the motors. The power branching system of the present invention has power lines 15 branched at some midpoint to connect the plural motors 5 and the servo driver 12; a plurality of current sensors 21 provided at branched power lines 15b for detecting currents supplied to the respective motors 5; and controlling means 22 for receiving current data detected by the plural current sensors 21, determining whether or not the detected currents are balanced and generating an alarm signal when the currents are unbalanced.

Abstract: A coolant flow reduction monitoring system for a rotary electric machine having stator coils within a plurality of slots of a stator thereof is provided. The stator coils are cooled by a coolant flowing in a plurality of passages provided in the stator coils. The system includes an outlet temperature sensor for measuring a coolant outlet temperature of the coolant in an outlet of at least one of the plurality of passages, a slot temperature sensor for measuring a temperature in at least one slot at a location along a length of each slot and outside of the stator coils, and an inlet temperature sensor for measuring a coolant inlet temperature of the coolant. A coolant flow reduction monitor generates an alarm indicating a coolant flow reduction based on the at least one coolant outlet temperature, the at least one slot temperature and the coolant inlet temperature.

Abstract: A drive system for a multi-phase electric machine with a permanent magnet rotor, the drive system may comprise conduction paths for each phase. Detectors on each of the conduction paths may determine electrical condition of the conduction path. At least one selectable interconnection path may be present between all of the conduction paths and at least one selectable interconnection path may be operable to connect all of the conduction paths together responsively to at least one of the detectors determining that the electrical condition of its respective electrical path is representative of a predetermined electrical fault condition so that heating of the rotor during continued rotation of the rotor is prevented.

Abstract: A motor controller is provided. The motor controller includes a motor drive unit that drives a plurality of motors; a thermal shutdown unit that is provided in the motor drive unit and that stops the plurality of motors in the case of an overload; a lock signal generation unit that generates a lock signal corresponding to a respective one of the plurality of motors when a rotational speed of the respective motor reaches a threshold speed set for the respective motor; and an operation determination unit which, when the lock signal generation unit interrupts lock signals for all of the plurality of motors, determines that thermal shutdown unit has operated.

Abstract: A modular control assembly is provided for on-machine control of a desired machine. One embodiment has a machine mountable base and a replaceable control unit, wherein the machine mountable base has a machine protection device. In various embodiments of the machine mountable base, the machine protection device may have a short-circuit protective device and a disconnect device. In addition, various embodiments of the replaceable control unit may have a variable frequency drive, a soft start device, or an adjustable overload protection device.

Abstract: A method of providing overload and short-circuit protection for a Switched Mode Power Supply (SMPS). The method may rely upon sensing a temperature change rate for a component of the SMPS and implementing a protection scheme when the temperature change rate exceeds a desired temperature change rate. The implementation scheme may include permanently or temporarily shutting-off the component.

Abstract: A control apparatus for controlling a fuel pump includes: an electronic switch provided in a circuit for connecting a power supply to a motor for driving the fuel pump; a current detector which detects a current which flows through the motor; and a controller which controls the electronic switch in a first PWM mode of a first frequency and a first duty ratio in a normal operation; and change a PWM mode to control the electronic switch in a second PWM mode of a second frequency lower than the first frequency and a second duty ratio lower than the first duty ratio when the current flowing through the motor exceeds a threshold current value in the normal operation.

Abstract: A combination spray and cold plate thermal management system for effectively thermally managing a heat producing device during startup. The combination spray and cold plate thermal management system includes a spray unit thermally managing a heat producing device and a coolant reservoir thermally connected to the heat producing device. The coolant reservoir includes a porous media with coolant channels for storing a volume of the waste coolant after spraying of coolant has terminated. The coolant reservoir is fluidly connected to the spray chamber within the spray unit to receive the waste coolant.

Abstract: A first terminal of a protection element of a control unit is connected to a wire between a motor and a switching element, and a second terminal is directly connected to a ground-side wire shared by a controller and the switching element. The protection element has a normal-condition-OFF-type switch including a movable contact and a fixed contact. When an overheating caused by the switching element attains a predetermined temperature or higher, the movable contact and the fixed contact are closed to short-circuit the first terminal and the second terminal, and an electric current is branched to the protection element side to reduce an electric current flowing into the switching element, and the control unit is shifted to a temperature range safe from the overheating caused by the switching element without stopping a cooling system.

Abstract: An inverter system having a semiconductor device, and a railway vehicle using this inverter, provide a more accurate determination of whether an abnormal heat generation from the inverter is associated with an error of the inverter system or is due to other causes, by use of a plurality of temperature detecting elements at a plurality of sites associated with the semiconductor device. An error detection section applies inputs from the temperature detecting elements, captures a trend of the differential value based on the plurality of temperature inputs using period sampling wherein an error associated with the semiconductor device, and not from some other condition such as outside environment temperature, is determined based on differences from, or a change in, the initial trend.

Abstract: A brushless direct current motor, includes a rotor which comprises a permanent magnet, a stator which comprises coils associated with a plurality of phases which form an electrical field for generating a torque by interaction with a magnetic field which is generated by the permanent magnet, and a load prevention part which is disposed inside the stator to electrically connect and disconnect the coils of the plurality of phases according to a temperature variation.

Abstract: At least one embodiment of the invention relates to a protective circuit for protection of an appliance, in particular of an electric motor, against thermal overloading. In at least one embodiment, the protective circuit includes a first and a second terminal for connecting a temperature detection element; a detection unit for detecting whether a resistance value of the temperature detector element which is connected between the first and the second terminals, is in a first or a second resistance range; a short-circuit detector for identifying whether there is a short circuit between the first and the second terminals; signaling outputs for emitting signal messages to an evaluation unit when the detected resistance value is in the second resistance range and/or when a short circuit has been identified by the short-circuit detector; and a third terminal, which is connected to the second terminal via a predetermined resistance.

Abstract: A drive apparatus for a washing machine includes an electric motor, a drive shaft connected to the electric motor for rotary drive purposes and electronics for controlling operation of the electric motor. In order to achieve a compact construction, the electric motor and the electronics are integrated in a common unit. In order to increase operational reliability of the drive apparatus together with a simple construction, the common unit has a wall which is thermally coupled both to the electric motor and to the electronics and serves to dissipate heat. The electronics have a temperature sensor for detecting the temperature of the wall. Both the temperature of the electric motor and the temperature of the electronics can be monitored with this one temperature sensor.

Abstract: A control device for controlling a recovery from a locking of a motor includes: a switching unit which supplies a motor current from a current supplying unit to the motor; and a driving control unit which supplies a PWM control signal to the switching unit to control a driving of the switching unit. The driving control unit supplies the PWM control signal with a low duty ratio lower than a regular duty ratio to the switching unit when the locking of the motor is detected depending on a variation in temperature of the switching unit. The driving control unit supplies the PWM control signal with the regular duty ratio to the switching unit when a cancel of the locking of the motor is detected depending on a variation in inter-terminal voltage of the motor.

Abstract: A temperature estimation controller and methods are provided for controlling a torque command to prevent overheating of one or more of a plurality of phases of a permanent magnet motor. The temperature estimation controller includes a low speed temperature estimation module, a transition module and a temperature dependent torque command derater block. The low speed temperature estimation module determines a stator temperature of each of a plurality of phases of the permanent magnet motor in response to first thermal impedances measured for each of the plurality of phases with respect to a thermal neutral. The transition module is coupled to the low speed temperature estimation module and outputs the stator temperature of each of a plurality of phases of the permanent magnet motor as determined by the low speed temperature estimation module when a detected speed of the permanent magnet motor is less than a first predetermined speed.

Abstract: Provision is made for a switch-state monitoring device that not only monitors the state of a switch but also prevents a motor burnout. A switch-state monitoring device for a switch that opens and closes a main circuit by use of a motor is provided with an operating time measuring unit for detecting an operating time for the motor when the switch is opened or closed; a first determination unit for comparing an operating time for the motor detected by the operating time measuring unit with an continuous-operating-capable setting time for the motor and determining whether or not the operating time for the motor has exceeded the continuous-operating-capable setting time; a protection device for halting energization of the motor in the case where, based on an output of the first determination unit, it is determined that the operating time for the motor has exceeded the continuous-operating-capable setting time.

Abstract: Motor start circuit for an induction motor, particularly a single-phase AC induction motor, with a main winding (4) and an auxiliary winding (5), which are supplied with current, particularly alternating current, via current supply connections (24, 25), and with a start switching device (15) serving the purpose of interrupting the current flow through the auxiliary winding (5) after the start of the motor, the start switching device (15) being connected to a control device (20) via a connector (18), the control device (20) being connected between the current supply connections (24, 25), and with a winding protection switch (28), which is normally closed and which opens on the occurrence of a fault. The invention is characterized in that the control device (20) is connected to the winding protection switch (28) via at least one further connector (22, 17), preferably via at least one further connector (22, 17) and the auxiliary winding (5).

Abstract: The present invention provides an apparatus and a method for accurately detecting abnormal conditions of a motor. A ?Tc/Tj detector detects a difference (?Tc) between an environment temperature and a temperature of a field-effect transistor (FET) which turns on and off electric power supplied to a DC motor. A diagnosis control unit detects abnormal conditions such as a motor lock and a short circuit of the DC motor based upon the obtained difference. When the motor lock has been detected, the diagnosis control unit controls a pulse width modulation (PWM) control unit and a PWM oscillator (PWMOSC) and makes a frequency and duty cycle of a PWM signal lower. When the short circuit has been detected, the diagnosis control unit controls a gate driver and turns off the FET.