Abstract: An actuator control system 1 includes a controlling controller 2 and one or more driving controllers 3 connected to the controlling controller 2 via a power line 9, wherein the controlling controller 2 generates a serial signal that composites a power-supply voltage to be supplied to an actuator 30 and a command signal generated in order to control driving of the actuator 30 and transmits the generated serial signal to the driving controllers 3 via the power line 9, and the driving controllers 3 separate and retrieve the power-supply voltage and the control signal. Due to the configuration described above, the driving controllers 3 supply a drive voltage and a drive control signal to actuators 30 connected thereto. Accordingly, an actuator control system can be provided whose amount of installed wiring has been significantly reduced.

Abstract: A first and a second drive current for an electrical drive are generated as a function of a nominal value for a movement variable, such as drive torque or rotational speed. An alternating magnetic field is generated in the drive by the drive currents. The alternating magnetic field causes movement of the drive. A first measurement signal and a second measurement signal are determined by a measurement device. The two measurement signals represent the first drive current and the second drive current. A field-producing direct-axis current component and a torque-producing quadrature-axis current component are determined as a function of the first and second measurement signals. In addition, an actual value of the movement variable is determined as a function of the measurement signals. At least one of the drive currents is generated with a variable test current component which forms a test pattern for checking the measurement device.

Abstract: A method, system and computer program product for monitoring health of a synchronous machine is provided. The method includes receiving a plurality of phase voltage values and a plurality of phase current values. The method then computes a negative sequence voltage (Vn) based on the plurality of phase voltage values. The method also computes one or more operating parameters based on at least one of the plurality of phase voltage values and the plurality of phase current values. The method retrieves from a data store, one or more known Vn based on the one or more operating parameters. The method then computes a machine health indicator based on the computed Vn and the one or more known Vn, and raises an alarm based on the machine health indicator.

Abstract: The present invention is a positioning work stop for use with a machine tool for and having a signaling means that operates as a placement indicator effective for providing a signal if the work piece to be machined is in its proper position for machining or for signaling if the work piece has shifted out of position for machining. In a preferred embodiment of the invention the positioning work stop comprises a stop member having a stop surface, a switch element, a signaling means, and a power supply that are electrically coupled such that the signaling means activates when the work piece makes contact with the stop surface and operates as a placement indicator effective for providing a signal if the work piece to be machined is in its proper position for machining or for signaling if the work piece has shifted out of position for machining.

Abstract: An electrical switching apparatus includes a plurality of poles each having a Rogowski coil and a conductor passing through an opening thereof, and a processor circuit including a sensor circuit including a plurality of inputs each electrically interconnected with an output of the Rogowski coil of a corresponding pole. The sensor circuit further includes a number of outputs having values each corresponding to current flowing through the conductor, a memory including for each corresponding pole an offset value and a gain correction factor for the sensor circuit, and a gain correction factor for the Rogowski coil, a number of routines, and a processor cooperating with the sensor circuit and the routines to provide for each pole a corrected current value as a function of a corresponding one of the values, the sensor circuit offset value and gain correction factor, and the Rogowski coil gain correction factor.

Abstract: A system and method for a motor management system includes a computer readable storage medium and a processing unit. The processing unit configured to determine a voltage value of a voltage input to an alternating current (AC) motor, determine a frequency value of at least one of a voltage input and a current input to the AC motor, determine a load value from the AC motor, and access a set of motor nameplate data, where the set of motor nameplate data includes a rated power, a rated speed, a rated frequency, and a rated voltage of the AC motor. The processing unit is also configured to estimate a motor speed based on the voltage value, the frequency value, the load value, and the set of nameplate data and also store the motor speed on the computer readable storage medium.

Abstract: A first duty ratio of a drive command signal is computed by comparing a level of the drive command signal with a first threshold value at a motor controller of a blower motor apparatus. A second duty ratio of the drive command signal is computed by comparing the level of the drive command signal with a second threshold value at the motor controller. A control signal is generated based on the first duty ratio and the second duty ratio in the motor controller and is used to drive a blower motor of the blower motor apparatus.

Abstract: Systems, devices, and methods for controlling a motor are disclosed. A method may include determining a rotational direction of a motor from a pair of quadrature signals sent to a microprocessor. The method further includes adjusting an internal count stored in the microprocessor at each edge of each of the pair of quadrature signals. The method further includes adjusting an external count stored in the microprocessor and transmitting an interrupt to a main controller after the first phase signal and the second phase signal have transitioned through each combinational logic state in one of a forward rotational direction and a reverse rotational direction. The method further includes transmitting a signal comprising the rotational direction of the motor and the external count from the microprocessor to a main controller.

Abstract: Continuous monitoring and fault diagnosis of rotating machinery during variable speed operation is performed using only a position feedback signal. The position sensor generates a periodic waveform having multiple pulses per revolution of the machine. A circuit is included to detect, for example, a zero crossing or edge of the periodic waveform. At each detected zero crossing or edge, the time and position of the event is stored in memory. Other data, such as the current in the motor, may also be sampled and stored in memory. Because the sampled data is triggered by repeated feature of the position feedback signal, the sampled data is in a stationary reference frame in the position domain. Frequency analysis is performed on the sampled data, and the frequency components present in either the sampled signal are analyzed to identify the presence of a fault in the rotating machinery.

Abstract: A drive device for an electric motor is provided. The drive device decides based on signals it receives from outside whether it is monitoring an actual value of the electric motor with respect to the adherence to an actual value condition (monitoring operation). During monitoring operation, the drive device causes the motor to be disconnected from a power supply if the actual value does not adhere to the actual value condition. Via a communication connection, the drive device provides a drive control unit with first information, which reveals whether the drive device is in the monitoring operating mode. The drive device provides the drive control unit with second information, which reveals what the actual value condition is. Based on the first information, the drive control unit examines whether the drive device is in the monitoring operating mode. If this is the case, the drive control unit, based on the second information, determines what the actual value condition is.

Abstract: A method for counting the number of revolutions of a burr of a coffee mill driven in rotation by an electric motor. According to the method: at least one electrical parameter Pi of the motor that varies in proportion to the speed of said motor is measured in a regular time interval Ti; the speed Vi in each time interval Ti is calculated from the parameter Pi based on an experimentally obtained relation; and the number of revolutions Ni made by the burr in each time interval Ti is calculated from the speed Vi determined.

Abstract: An electric vehicle includes a control unit having overcurrent generation judgment unit, inverter selection unit, and inverter drive control unit. The overcurrent generation judgment unit judges whether an overcurrent is generated in an inverter for generation or an inverter for travel. When an overcurrent is generated in one of the inverters, the inverter selection unit selects the other inverter to be driven. The inverter drive control unit stops the driving of the one inverter and drives the other inverter to drive a travel motor or a generator.

Abstract: A method of detecting an angular position of a rotor of a motor includes detecting switching ripple peaks and armature current disturbance peaks using a peak detector configured to generate a square wave having edges coinciding with detected peaks. The method further includes filtering the square wave in a time domain by generating an integration ramp, toward a set value, of an estimated ripple frequency for an interval of time based on the estimated ripple frequency. An enablement range is established to reset the integration ramp by setting a threshold below and above the set value and a time window centered on an end time of each period of the estimated ripple frequency. The method further includes resetting the integration ramp, and updating the estimated ripple frequency based upon a period determined by a time of the resetting, if an edge of the square wave is within the time window.

Abstract: Methods and systems are provided for detecting loss of isolation of a motor, connections, or phase cables while an AC motor is operating. The system includes a power supply that is substantially isolated from the ground or chassis having a power supply voltage, and a power inverter electrically coupled to the power supply. The power inverter is configured to provide AC current from the power supply in an AC phase at an AC terminal, with the phase having current at a fundamental frequency that controls the motor speed. An electric motor is electrically coupled to the AC terminal of the power inverter and has a chassis that is substantially electrically isolated from the AC terminal of the power inverter under normal operating conditions. A processor is configured to control the AC current provided by the power inverter. The processor is configured to receive a first voltage signal related to current flowing through a motor chassis.

Abstract: A method for detecting a regulating variable of a mechanically commutated DC motor in a positioning device for a motor vehicle is provided. The DC motor has a standard ripple pattern, which contains per engine cycle or semi-cycle at least one index ripple, which is classified with regard to amplitude, duration and/or time position. The counter-electromotoric power is calculated from a measured motor current and the measured motor voltage by a motor model. An alternating element corresponding to the current ripples is extracted from the counter-electromotoric power, which in turn is used to determine the current ripples. Further, in at least one engine cycle or engine semi-cycle the index ripple is identified and the total identified current ripples are counted. The result of the count is hereby corrected when the index ripple is not counted at the expected position.

Abstract: In a motor control device that drives a plurality of motors with one DC power supply, detection of a short circuit fault occurring in the motors is realized with an inexpensive configuration. In order to drive the plurality of motors (105, 106), a current detection resistor (404, 405) is arranged between a connection point on positive terminal sides of a plurality of electric power converters (401, 402) connected in parallel to a DC power supply (403) and a positive terminal of the DC power supply, or also between a connection point on negative terminal sides of the plurality of electric power converters and a negative terminal (ground) of the DC power supply, to thereby detect the short circuit fault based on a voltage of the current detection resistor.

Abstract: The present invention provides a new and unique method and apparatus for monitoring a device, such as a pump. The device may also include a fan, compressor, turbine or other rotating or reciprocating piece of machinery. In one embodiment, the method features sensing in a first device both a start-up vibration at a start-up time after the first device is affixed to a second device to be monitored and a subsequent vibration level at a subsequent time after the start-up time, and providing both a start-up vibration level signal containing information about the start-up vibration level of the second device, and a subsequent vibration level signal containing information about the subsequent vibration level of the second device; and monitoring in the first device the condition of operation of the second device based on a comparison of the start-up vibration level signal in relation to the subsequent vibration level signal.

Abstract: Motor drives and switch driver power systems are presented in which high frequency AC current (IHF) is provided through one or more cables (202) magnetically coupled with local driver current transformers (240), and the transformer secondary currents are converted to provide DC power to switch drivers of an active power converter stage (110a, 110b) in the motor drive.

Abstract: An electric power tool is provided that includes a motor as a driving source, a first operation switch, a first semiconductor switch, and a second semiconductor switch. The first operation switch is operated by a user to be turned ON/OFF. The first semiconductor switch, provided on a current path from the power source to the motor, includes at least one semiconductor switching device. When the first operation switch is OFF, the first semiconductor switch is turned OFF to interrupt the current path. When the first operation switch is ON, the first semiconductor switch is turned ON to close the current path. The second semiconductor switch is provided on the current path in series with the first semiconductor switch and includes at least one semiconductor switching device. The second semiconductor switch closes/interrupts the current path by being turned ON/OFF in accordance with an input control signal.

Abstract: An image forming apparatus includes at least one image bearing member unit including an image bearing member and a motor including an output shaft coupled with the image bearing member to rotary-drive the image bearing member. The output shaft of the motor includes rotation speed detecting means to detect a rotation speed of the output shaft, the rotation speed detecting means being disposed in a vicinity of a node of a torsion resonance mode of the output shaft of the motor.

Abstract: A method and a system for determining deterioration of permanent magnets of an electric apparatus to be inspected that facilitate determination without the need to remove the electric apparatus from a facility where it is installed. If the electric apparatus to be inspected is a three-phase linear motor, a current detector is used to acquire currents. A three-phase/two-phase conversion section converts the acquired currents into an ?-axis current command and a ?-axis current command. A locus of a current vector is computed based on the ?-axis current command and the ?-axis current command. A comparing and determining section compares the computed locus with a standard upper limit value stored in a storage means. If the number of times that the locus of the current vector exceeds the standard upper limit value exceeds a predetermined value, it is determined that the permanent magnets have been deteriorated.

Abstract: A system and method are provided for correction of parameters used in determination of stator turn faults of an induction motor. An embodiment may include determining a residual impedance and/or a residual voltage of the motor, and correcting a normalized cross-coupled impedance based on the residual impedance and residual voltage. Additional embodiments may include measuring an operating temperature of the motor and determining a negative sequence impedance of the motor based on the temperature. Another embodiment may include measuring voltages and currents of the motor and determining phasors for the voltages and currents using compensation for variations from a nominal frequency of the motor.

Abstract: A system and method for identifying turn faults in a stator of a motor are provided. The method includes determining a normalized cross-coupled impedance from the symmetrical components of measured voltages and currents of the motor. Additionally, the normalized cross-coupled impedance may be normalized to a negative sequence impedance. The negative sequence impedance may be determined through a regression analysis using parameters of the motor, such as line-to-line voltage, horsepower, and number of poles. A system is provided that includes a device having a memory and processor configured to determine a normalized cross-coupled impedance, compare the normalized cross-coupled impedance to one or more thresholds, and trigger and alarm and/or trip the motor.

Abstract: A control system to selectively control the operation of the compressor of a mini-split air conditioning system including at least one remote evaporator operatively coupled to the compressor to receive refrigerant therethrough, a sensor to monitor the operation of the evaporator and to generate an operating control signal to turn-off the compressor when a predetermined operating condition is sensed at the evaporator and a condensate drain pan to receive or catch condensate from the evaporator, the control system comprising a condensate sensor disposed to sense condensate in the condensate drain pan at a predetermined level and to generate a condensate level signal fed to a battery powered control device including an isolated solid state relay coupled to the sensor by a control coupling device to generate a condensate level control signal fed to the sensor causing the sensor to generate the operating control signal fed to turn off the compressor when condensate within the condensate drain pan reaches the prede

Abstract: A fan failure detector means for detecting whether a fan is locked comprising a drive IC, a coil and an inspection circuit, the drive IC means for outputting a pulse signal, the coil is electrically connected to the drive IC and being driven by the drive IC, the inspection circuit is electrically connected to the drive IC and the coil, the inspection circuit comprises an RC charge/discharge circuit, a diode, a second capacitor, a voltage divider and a transistor having an output terminal, wherein the RC charge/discharge circuit, the diode, the voltage divider and the transistor are sequentially connected in series, the second capacitor is electrically connected with the diode and the voltage divider, when the fan operates normally, the output terminal provides a low voltage signal, when the fan locks, the output terminal provides a high voltage signal to avoid a wrong judgment that the fan still operates normally.

Abstract: Methods and systems are provided for diagnosing faults of a rotor of an electric motor. A current is obtained for an inverter using a sensor. A preliminary angle is determined by a control unit or processor using a resolver angle of the rotor. A transformation is conducted by the control unit or processor using a transformation angle that is equal to a multiplier multiplied by the preliminary angle. A fault condition is identified via the control unit or processor using the transformation.

Abstract: An electric power conversion apparatus converts electric power supplied to a motor having a winding set formed of coils corresponding to a plurality of phases. An inverter part has a plurality of FETs forming switching element pairs, each of which corresponds to each phase of the winding set. Pull-up resistors are provided between the coils and a high-potential side of a battery, respectively. A neutral point voltage detection part detects a neutral point voltage of the winding set. A microcomputer detects abnormality based on the neutral point voltage.

Abstract: Apparatus to exercise electrical motor drivers by electrically simulating a geared electric or electrical motor by providing an electronic load for the power signals that are applied to it. Current levels in the load are monitored in real-time using gate array logic and digital signal processing (DSP) algorithms to determine torque, acceleration, velocity and/or position data of the motor and gear train. Motor and gear train positional signals are generated and fed back to the motor driver device to close the servo loop. Control algorithms within the gate array and DSP accurately simulate the motor inertia and act to simulate a physical motor under varying load conditions. A control interface modifies critical motor parameters such as inertia, losses, gear ratio, and loading.

Abstract: A technique is provided for verifying the proper selection, installation, communication and operability of components in power electronic systems, such as motor drives. A processing circuit is coupled to multiple components or subsystems that identify themselves to the processing system. An identification code is stored that is compared to a similar code built based upon the information reported by the components at the time of commissioning, operation or servicing. If the comparison indicates that all components are properly installed, and communicating and operative, operation may continue. The technique may be applied in parallel motor drives at a power layer level to allow separate and parallel verification of component and component operation in the parallel drives.

Abstract: Systems and methods are provided for performing diagnostic testing for multiple motor drives operating in parallel. In one embodiment, the diagnostic testing may involve determining which of the multiple motor drives are in operation and communicating the active configuration of motor drives to testing circuitry. The testing circuitry generates an enable input signal transmitted to the transistor gates in each of the active motor drives. The testing circuitry also generates a power supply input signal transmitted to a DC to DC converter in each of the active motor drives. The responses to the enable input signal and the power supply input signal are measured to determine safety compliance.

Abstract: An electric power tool is provided that includes a motor as a driving source, a first operation switch, a first semiconductor switch, and a second semiconductor switch. The first operation switch is operated by a user to be turned ON/OFF. The first semiconductor switch, provided on a current path from the power source to the motor, includes at least one semiconductor switching device. When the first operation switch is OFF, the first semiconductor switch is turned OFF to interrupt the current path. When the first operation switch is ON, the first semiconductor switch is turned ON to close the current path. The second semiconductor switch is provided on the current path in series with the first semiconductor switch and includes at least one semiconductor switching device. The second semiconductor switch closes/interrupts the current path by being turned ON/OFF in accordance with an input control signal.

Abstract: A control apparatus and a control method for an AC electric motor detect DC bus current plural times at predetermined intervals during first and second predetermined periods and multiply vectors having integrated values of detected values during respective periods as elements by an inverse matrix of a matrix having integrated values during respective periods of sine and cosine functions of output voltage phase of an inverter at the moment that detection is made as elements to thereby estimate reactive and active currents.

Abstract: A system and method for detecting a rotor fault condition in an AC induction machine is disclosed. The system includes a processor programmed to receive voltage and current data from an AC induction machine, generate a current frequency spectrum from the current data, and identify rotor-fault related harmonics in the current frequency spectrum. The processor is also programmed to calculate a fault severity indicator using the voltage and current data, identified rotor-fault related harmonics, and motor specifications, analyze the fault severity indicator to determine a possibility of rotor fault. The processor generates an alert based on the possibility of rotor fault.

Abstract: When an inverter or a coil set of one system fails in a motor drive apparatus having two power supply systems, a power supply relay of a failing system is turned off. In this case, while a travel speed detection value is less than a predetermined threshold value, current supply to a motor by the other system operating normally is stopped to thereby stop driving of the motor and generate no steering assist torque. Thus, a driver will be caused to surely notice occurrence of failure.

Abstract: When failure of an inverter or a coil set of one system of a motor drive apparatus having two systems, is detected, a power supply relay of the failing system is interrupted. At the same time, a control circuit sets a same maximum current limitation value as set before detection of failure. When an IG switch is in an ON-state and a steering toque detection value exceeds a predetermined threshold value thereafter, a vibration component, which has a predetermined amplitude and frequency, is added to a current command value so that a steering wheel is vibrated in a direction of rotation so that a driver is cautioned to notice the failure surely.

Abstract: Detection of, among other things, seal leakage(s) and/or seal oil contamination for a gas cooled generator are provided. Detectors according to some embodiments of the invention provide mechanisms of early detection of cooling gas, e.g., hydrogen, leakage through leakage sources as well as low purity and high cooling gas consumption problems in a gas cooled generator.

Abstract: A method for protecting an electronic apparatus driven by a DC motor and a detection circuit for detecting positioning signals thereof. The electronic device includes an optical encoder, a code strip, and a DC motor. While moves along the code strip, the optical encoder outputs a first positioning signal and a second positioning signal for the control of the DC motor. The method includes the steps described below. First, states of the first and second positioning signals are detected. If the states of the first and second positioning signals are normal, the DC motor is controlled according to the first and second positioning signals. If the first positioning signal or the second positioning signal is abnormal, a preventive method is performed.

Abstract: The motor position controller inputs a command pulse signal and a desired pulse form setting, and drives a motor based on the command pulse signal. The motor position controller includes a position command generating device configured to generate a position command signal from the command pulse signal in accordance with the inputted desired pulse form setting, a motor controlling part configured to supply power to the motor based on the position command signal, and a first conformity determination device configured to determine the conformity of the desired pulse form setting and the command pulse signal.

Abstract: A method of controlling a washing machine and a motor determines whether a BLDC motor is in a normal state in software without hardware and a user is notified of an abnormal state of the BLDC motor if the BLDC motor is in an abnormal state, thereby ensuring safety. When the motor is rotated, the state of the motor is determined by applying harmonics to a voltage that is applied to a motor and analyzing an output frequency characteristic. When the motor is stopped, the state of the motor is determined by estimating the temperature of the motor.

Abstract: A motor drive apparatus includes a control circuit, which determines that a wire connecting a battery to a first power supply relay and a second power supply relay is broken, and not failure of the power supply relays, if power is not supplied to a motor from the power supply relays when the power supply relays are controlled to turn on. The location of failure can thus be specified accurately. It is only necessary in this case to replace the wire. The motor drive apparatus need not be disassembled or investigated in detail. Man-power for specifying the failure location can be reduced.

Abstract: The motor driving device includes a first function of supplying power to a motor so that the motor generates a driving force to drive a driven member, a second function of detecting a current flowing through the motor, a third function of performing a power supply control in order that a value of the current detected by the second function is maintained within a target range, a fourth function of performing a power supply operation in which the motor is supplied with power for a predetermined time period which is short enough to avoid the driven member from being driven by the motor, before the third function performs the power supply control, and a fifth function of making a judgment on a state of each of the first to third functions on the basis of the value of the current detected by the second function during the predetermined time period.

Abstract: A method is provided for detecting an insufficient or missing phase current in a permanent magnet synchronous motor, and includes determining a composite vector position of a combined three-phase phase current with respect to a stationary portion of the motor, and assigning a sector to the position. The method includes comparing the phase current to a calibrated threshold current corresponding to the sector, and executing a response when the absolute value is less than the threshold. A vehicle includes an energy storage device (ESD), a motor/generator configured as a permanent magnet synchronous motor, a voltage inverter, and a bus for conducting DC current from the ESD to the inverter. A controller detects an insufficient phase current, determines a current vector position of the three-phase AC, assigns a sector to the position, and executes a response when an absolute value of the phase current is less than a calibrated threshold.

Abstract: A testing system for testing a temperature characteristic of a first motor includes a second motor, a controller, a driver, a load, a temperature sensor, and a temperature recorder. The controller provides a drive command for the driver to drive the second motor. The second motor drives the first motor via a coupling. A current of the first motor is determined by adjusting the resistance of the load. The temperature sensor senses the temperatures of the first motor every a determined time and sends the temperatures to the temperature recorder. The temperature recorder records and transmits the temperatures to the controller for the temperature characteristic test of the first motor.

Abstract: A vehicle drive apparatus includes a battery that is a direct current power source, a converter that increases the voltage of the battery, an inverter connected to a motor that drives the vehicle, an inverter connected to a motor generator that functions as a motor or generator, and a motor control device that controls the motor. The vehicle drive device is also provided with a voltmeter, non-energized state determination devices that determine a non-energized state of the inverters, and ammeters that detect currents applied to a motor from each phase arm of the inverters. Signals of these devices and a signal from the non-energized state determination device are sent to the motor control device.

Abstract: A rotation detecting apparatus for detecting a rotational state of a direct-current motor includes a driving device, a control device, an energization detecting device, an alternating-current component detecting device, and a rotational state detecting device. An impedance between brushes of the motor changes periodically in accordance with rotation of the motor. The alternating-current component detecting device detects change of an alternating-current component of electric current that is supplied to the motor based on an electrical quantity. The change of the alternating-current component is caused by change of the impedance caused in accordance with the rotation. The rotational state detecting device detects at least one of a rotation angle, a rotational direction, and a rotational speed of the motor based on a detection result of the alternating-current component detecting device.

Abstract: Provided are an apparatus and a method for diagnosing permanent magnet demagnetization of a permanent magnet synchronous motor. The apparatus includes a magnetic field generating unit, a stator current measuring unit, and a demagnetization diagnosing unit. The magnetic field generating unit generates magnetic fields of which directions are respectively parallel to a predetermined direction among a plurality of directions passing through a rotation axis of a rotor, on a plane vertical to the rotation axis of the rotor which is in a standstill. The stator current measuring unit measures currents which flow in a stator winding in correspondence with the respective generated magnetic fields.

Abstract: In a rotary electric system, a switch member includes at least one of a first switch and a second switch. The first switch is connected between a neutral point of multiphase stator windings and a high-side electrode of a direct current power source. The second switch is connected between the neutral point and a low-side electrode of the direct current power source. A controller works to turn the switch member off and on thereby switching control of the multiphase inverter between full-wave driving mode and half-wave driving mode. The full-wave driving mode allows the controller to drive all of the high-side and low-side switching elements per phase of the multiphase stator windings. The half-wave driving mode allows the controller to drive any one of the high-side switching element and the low-side switching element per phase of the multiphase stator windings.

Abstract: A circuit for speed monitoring of an electric motor comprises a circuit for generating a time-frame signal, a circuit for receiving a first signal from a chopper driver circuit designed to drive the electric motor, a circuit for detecting chopper pulses in the first signal, a pulse counter, and a circuit for at least one of outputting and evaluating a state of the pulse counter, after the inactive state of the time-frame has been indicated. The time-frame signal indicates when a time-frame of predefined length changes from an inactive state to an active state and indicates when the time-frame changes back from the active state to the inactive state. The pulse counter is designed to count the detected chopper pulses while the active state is indicated by the circuit for generating the time-frame signal.

Abstract: A motor driving apparatus capable of detecting during operation a ground fault and a phase-to-phase short circuit by distinguishing one from the other is provided while minimizing an increase in cost. The sum of three-phase AC currents supplied from a three-phase AC power supply to an AC/DC converter is detected by a current sensor. When overcurrent is detected by an overcurrent detector, if the sum of the currents detected by the current sensor is zero, it is determined that the fault is a phase-to-phase short circuit, but if the sum is not zero, it is determined that the fault is a ground fault.

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.