Abstract: A method of detecting a rotor bar fault of an electrical machine, said method comprising, acquiring a set of online signals from the electrical machine over a period, said set of online signals comprising at least one vibration signal, and a summed signal of magnetic flux signals, each magnetic flux signal obtained from a respective flux sensor positioned on an external surface of the electrical machine; extracting an online anomaly indicator value from the set of online signals; comparing the online anomaly indicator value with a baseline anomaly indicator value of a corresponding loading condition; and determining presence of the broken or cracked rotor when the online anomaly indicator value deviates from the baseline anomaly indicator value by a threshold.

Abstract: Embodiments are presented herein of an open-loop test system for testing vertical-cavity surface-emitting lasers (VCSELs). A high-speed pulse generator may be used to produce nanoseconds pulses provided to the VCSEL device. A high-speed oscilloscope may be used to measure the resultant nanoseconds pulses across the VCSEL device. The VCSEL device voltage and VCSEL device current may be obtained from the measured nanosecond pulses according to compensation data derived from the system. A pre-test compensation procedure may be used to obtain the compensation data, which may include representative characteristics of each system component.

Abstract: Provided herein are approaches for determining a status of a fuse or relay. In some embodiments, a system may include a first fuse or relay connected between a first input and a first output, and an optocoupler electrically connected with the first fuse or relay, wherein the optocoupler is operable to monitor a differential voltage of the first input or the first output. The system may further include an input/output (IO) expander receiving a status signal representing a state of the first fuse or relay, wherein only a single input port of the IO expander receives the status signal representing the state of the first fuse or relay.

Abstract: An electric powertrain system includes an electric machine having a rotor and stator. The stator has multiple phase legs, each respective one of which includes a single phase lead connected to two or more parallel stator windings. The stator thus has multiple phase leads collectively conducting phase currents. A rotary output member is connected to the rotor and connectable to a load. A traction power inverter module (TPIM) is electrically connected to the phase legs. Current sensors collectively measure the phase currents. Each respective current sensor is connected to a different phase lead. A controller in communication with the current sensors and the TPIM, in response to a commanded current and the measured phase currents, detects a threshold variation in the measured phase currents indicative of a phase current imbalance fault, and selectively changes a thermodynamic state of the electrified powertrain in response to the fault.

Abstract: Disclosed is a method for determining a rotor temperature value TRot for an electric machine, such as an electric motor. In one example, the method includes calculating a support value Pcu2_Trot using a rotor temperature value Trot that is determined with a temperature model and a motor current value Isdq. An auxiliary value Pcu2_Ref can be determined using a motor torque Trq and a motor slip value ?slip. The support value Pcu2_Trot can be linked with the auxiliary value Pcu2_Ref in order to obtain a corrected rotor temperature value DeltaTrot. Furthermore, the temperature model can be modified using the corrected rotor temperature value DeltaTrot in order to obtain a corrected temperature model. Finally, the rotor temperature value TRot can be determined using the corrected temperature model.

Abstract: A hairpin type stator inspection apparatus is provided for testing performance of a stator wound with hairpin type stator coils. The hairpin type stator inspection apparatus includes: a conveyor provided on a frame for transferring the stator including a plurality of stator terminals along a predetermined path: a plurality of clamp terminals, which are installed to be movable to the frame by a driver in up and down, front and rear, and left and right directions in order to clamp the stator terminals: a controller that applies a driving control signal to the driver to change a position of the clamp terminals according to a position of the stator terminals; and an inspection portion that applies power to the stator terminals through the clamp terminals and inspects the electrical circuit of the stator.

Abstract: Systems and methods relate to electric propulsor fault detection. An exemplary system includes at least a first inverter configured to accept a direct current and produce an alternating current, a first propulsor, a first motor operatively connected with the first propulsor and powered by the alternating current, and at least a noise monitoring circuit electrically connected with the direct current and configured to detect electromagnetic noise and disengage the at least an inverter as a function of the electromagnetic noise.

Abstract: A motor demagnetization detection method includes the following steps. The speed of a motor is calculated according to the rotation angle of the motor. When determining that the motor respectively maintains a first and second steady state according to the speed, the three-phase current values of the motor are received to obtain first and second steady-state data. An equivalent magnetic flux is calculated according to the first and second steady-state data. The motor is repeatedly driven to maintain the first and second steady states, the first and second steady-state data are updated according to the three-phase current values, and the equivalent magnetic flux is again calculated to generate equivalent magnetic fluxes. A magnetic flux change is calculated according to equivalent magnetic fluxes. A demagnetization warning is issued according to a comparison of the magnetic flux change and a demagnetization warning value.

Abstract: An insulation resistance detection circuit and method are disclosed. The circuit includes a controller configured to: open a first relay, and close second relays, or switch an on/off status of at least one of the second relays; determine, based on a first measurement value between a positive input terminal of an inverter circuit and an earthing point, whether the positive input terminal of the inverter circuit is short-circuited or has low resistance to protective earthing; and determine, based on a second measurement value between a negative input terminal of the inverter circuit and the earthing point, whether the negative input terminal of the inverter circuit is short-circuited or has low resistance to protective earthing, where the first relay is one of in M relays and is connected to at least one impedor in parallel, and the second relays are relays other than the first relay in the M relays.

Abstract: A torque-limiting safety circuit servo drive for AC permanent magnet motors including a three-phase inverter bridge, a first current sensor in series with a first motor phase, a second current sensor in series with a second motor phase, a third current sensor in series with the DC bus, and a drive control circuit that controls the six pulse-width modulated gate drive signals for the three-phase inverter bridge. The drive circuit has first and second safety channel STO inputs whereby either channel can shut down the three-phase inverter bridge, emits a signal set to represent the switching state of the three-phase inverter bridge, and modifies the switching pattern of the PWM to ensure the dwell times of PWM is sufficiently long to allow a valid measurement of phase current using the bus current sensor. First and second safety processors controls the first and second safety channel STO inputs, respectively.

Abstract: A system for monitoring operation of rotating electrical machinery including electrical industrial machinery. The system comprises analog sensors configured to measure electrical signals corresponding to the voltage and the current of the rotating electrical machinery. A remote processor identifies the frequency components of the measured electrical signals. Based on the frequency components, the system is monitored and controlled. This may help allow electrical faults, mechanical faults and process faults to be predicted and/or prevented.

Abstract: A system for evaluating an electromagnetic performance of a permanent magnet (PM) motor. Parameters update an electromagnetic analytical (EA) model. Each component of the PM motor is associated with regions, and assumptions of the EA model include a relative permeability of regions associated with a rotor core modeled as finite. Calculate a general solution to a governing equation to each region which include unknown coefficients to be determined. Define a set of boundary and interface (B&I) conditions for two neighboring regions, each B&I condition is defined through a set of Maxwell equations using the two neighboring regions sets of assumptions, geometries of the PM motor and electrical and magnetic properties associated with the two neighboring regions. All the unknown coefficients in the general solutions in all regions are solved with a linear system of equations obtained from the B&I conditions between the regions, to solve for a magnetic vector potential.

Abstract: A method and a wind turbine are provided. The wind turbine includes a gearless generator that is a synchronous generator and includes a stator and a generator rotor. The wind turbine includes a generator filter with modifiable filter properties that is coupled to the stator and configured to filter a stator current. The wind turbine includes a filter controller configured to control the generator filter.

Abstract: An electronic determination device is configured for determining at least one characteristic parameter of an electric machine with P phases, P?3, connected to an electric starter and including at least P-1 switching arms, each switching arm being connected to a respective phase of the electric machine. The determination device comprises a control module configured to control respective switching arm(s) to close and the other switching arm(s) to open, so as to generate a current injection on two phases of the electric machine; an acquisition module configured to acquire measurements of respective current(s) and voltage(s) for said two phases, further to the generation of the current injection; and a calculation module configured to calculate at least one characteristic parameter of the electric machine according to the respective current(s) and voltage(s) measurements.

Abstract: The present invention quickly stops rotation of an electric compressor while preventing damage to switching elements. An electric compressor 1 comprises a motor drive circuit 52 having multiple switching elements IGBT Q1 to Q6, a control unit 53 that controls driving of the multiple switching elements IGBT Q1 to Q6 and drives a motor 4, and a current detection unit 54 that detects a current flowing through the motor drive circuit 52. The control unit 53 performs stop control that stops rotation of the compression mechanism 3 by performing braking control that controls drive of predetermined switching elements IGBT (Q2, Q4, Q6 and the like) among the multiple switching elements IGBT Q1 to Q6.

Abstract: A data compression process reduces the amount of machine spectral data transmitted over a network while maintaining the details of spectral peaks used for machine health analysis. The data compression process also provides for the calculation of various types of spectral parameters, such as spectral band parameters, with negligible loss of accuracy.

Abstract: A system for detecting a fault in a polyphase electrical network, characterized by the fact that it comprises a plurality of sensors distributed over the electrical network and suitable for measuring a parameter representative of the positive sequence voltage and/or the negative sequence voltage at each respective sensor and analyzing means suitable for analyzing the signals coming from the different sensors representative of the positive sequence voltage and/or the negative sequence voltage at each respective sensor, by searching for an extremum from among the signals coming from the sensors and for locating a fault at the sensor corresponding to this extremum.

Abstract: A testability method for the in-flight testing of an operating state of an electronic power chain having at least one power converter intended for driving an electric motor that actuates at least one aircraft component includes controlling actuation of the converter, transmitting a test signal, collecting at least one measurement signal, and determining an operating state.

Abstract: A current sensor integrated circuit to sense a current through a resistor includes a substrate, a tub disposed in the substrate, an analog front end disposed in the tub and comprising an amplifier having inputs coupled across the resistor and a charging circuit configured to bias the analog front end and the tub to a bias voltage that is a predetermined offset voltage greater than a common mode voltage associated with the resistor. In embodiments, the analog front end is biased to a first bias voltage and the tub is biased to a second, different bias voltage.

Abstract: A shaft torque control device includes a feedback control system having: a generalized plant P including a nominal plant model N representing the input/output characteristic of a test system including a tandem dynamometer system; and a controller K for applying a first and second control inputs u1, u2 to the generalized plant P on the basis of a first observed output y1 and second observed output y2. The controller K has been designed using a computer so as to satisfy a prescribed design condition. For the generalized plant P, defined are: a first control amount output z1 resulting from weighting the first observed output y1 using a weighting function Ge(s); a second control amount output z2 resulting from weighting a front transmission torque t1 using a weighting function Gt1(s); and a third control amount output z3 resulting from weighting a rear transmission torque t2 using a weighting function Gt2(s).

Abstract: A motor monitoring system includes a motor unit, a plurality of sensors, and a motor controller. The motor unit includes a motor housing and a motor arranged within the motor housing. The motor includes a stator with a plurality of stator poles each having a corresponding phase coil. The plurality of sensors are arranged within the motor housing and are configured to: measure a first characteristic related to partial discharges that occur at one or more phase coils, and generate sensor data based on the measured first characteristic. The motor controller is configured to generate a plurality of pulse width modulation (PWM) control signals for controlling phase voltages of the motor, detect the partial discharges at at least one of the phase coils based on the sensor data, and adjust at least one PWM control signal of the plurality of PWM control signals based on the detected partial discharges.

Abstract: Method for detecting rail switches degradation and failures, the method having the steps of applying a Discrete Wavelet Transform to stored measurement data relative to a switch move to be analysed and obtaining a feature vector associated with said switch move and including Discrete Wavelet Transform coefficients delivered by the applied Discrete Wavelet Transform; comparing the obtained feature vector with feature vectors associated with rail switch moves previously obtained and associating each to a respective health class among several given health classes; and determining a health class for the said switch move to be analyzed by selecting one of the health classes associated with the previously obtained feature vectors based upon the comparison step.

Abstract: A short detection apparatus configured to detect a layer short in a motor in which a plurality of sets of multi-phase windings are independently disposed in a stator includes an acquisition unit configured to acquire electricity information corresponding to windings of individual phases in the sets of the multi-phase windings; and a determination unit configured to determine, based on the electricity information which the acquisition unit acquires with respect to windings of a mutually identical phase in the sets of the multi-phase windings, whether a layer short occurs in any one of the windings of the mutually identical phase.

Abstract: One embodiment can provide a method and a system for diagnosing faults in a physical system. During operation, the system obtains a time-domain model of the physical system and converts the time-domain model to the frequency domain to obtain a frequency-domain model of the physical system. The time-domain model can include one or more model parameters having known values. The system also obtains time-domain input and output signals and converts the time-domain input and output signals to the frequency domain to obtain frequency-domain input and output signals. The system identifies at least one model parameter having an expected value that is different from a known value of the at least one model parameter based on the frequency-domain model and the frequency-domain input and output signals, and generates a diagnostic output indicating at least one component within the physical system being faulty based on the identified at least one model parameter.

Abstract: A rotating electric machine apparatus including: a rotating electric machine (REM) including a rotor and a stator; an inverter device including an inverter circuit (IC) for driving the REM and an inverter control unit (ICU) for controlling the IC; a detector, in which a first antenna is connected to a resonance circuitry, which is mounted to the REM and has a resonance characteristic that changes depending on a change in a physical quantity; and a detection processor receiving a response radio wave indicating a detection result of the change in the physical quantity from the first antenna while transmitting a transmission radio wave at a set carrier frequency from a second antenna, and comparing the detection result and the set value, to thereby obtain an abnormal state in the REM. The ICU controls output of the IC in accordance with an abnormal state signal from the detection processor.

Abstract: To provide a numerical controller and a machine learning device that predict an abnormality, based on machine learning with perception of temporal change in data. The numerical controller includes the machine learning device provided with a learning unit that conducts machine learning of trends in operation of a machine on occasions of occurrence of abnormalities in the machine, based on time-series data acquired by a data logger device and relating to the operation of the machine and abnormality information relating to the abnormalities which have occurred in the machine and a prediction unit that predicts an abnormality which will occur in the machine, based on results of the machine learning in the learning unit and time-series data acquired by the data logger device and relating to current operation of the machine.

Abstract: A method is for a machine having an alternating current (AC) power source with a first side (L1) and a second side (L2), two or more pairs of power switches, and one or more windings. The method comprises closing one pair of power switches by a control circuit to cause current to flow from a first side of the AC power source, through the one or more windings, and to the second side of the AC power source and closing another pair of power switches by the control circuit to cause current to flow from the second side of the AC power source, through the one or more windings, and to the first side of the AC power source.

Abstract: The present invention relates to a method for determining a state of a bearing of a three phase electric machine, the electric machine having a rotor, which is supported by the bearing, the electric machine being connected to a three phase inverter for supplying the electric machine with electric power, the three phase inverter being controlled to apply a pulse width modulation with a predefined scheme to create three phase currents, the method comprises: —determining a first phase current provided to the electric machine; —determining a second phase current provided to the electric machine, the second phase current being different to the first phase current; —determining the power spectral density of the park's vector based on the first phase current and the second phase current; —determining an amplitude of the power at a predefined frequency of the power spectral density, wherein the predefined frequency depends on the rotational speed of the rotor and the scheme of the pulse width modulation; —comparing t

Abstract: According to an embodiment, an inspection device comprises a moving body that includes; a moving main body which moves in contact with a first structure; arms attached to the moving main body; an arm driver to drive the arms; and a detector attached to the moving main body or the arms to inspect the second structure. The arms each can selectively take a pressed position and a detached position. When the moving body is moved, at least one of the arms are in the pressed position and pressed to the second structure, and the moving body is supported by the first and second structures.

Abstract: A diagnostic system for a compressor is provided. The compressor includes a compression mechanism and a motor. The diagnostic system includes processing circuitry and memory and may be operable to differentiate between a low-side fault and a high-side fault by monitoring a rate of current rise drawn by the motor for a first predetermined time period following compressor startup. The diagnostic system may be operable to predict a severity level of a compressor condition based on a fault history stored in the memory.

Abstract: The present application provides a method of evaluating valve spindle vibration in a turbine by a data acquisition system. The method may include the steps of receiving a number of operating parameters from a number of sensors, wherein the operating parameters may include valve spindle vibration, comparing the valve spindle vibration to a predetermined value, and altering one or more of the operating parameters if the valve spindle vibration exceeds the predetermined value.

Abstract: A method for estimating an insulation resistance between a point of a high-voltage circuit including a high-voltage motor vehicle battery and a ground of the vehicle includes measuring a voltage value at terminals of a measurement circuit that includes a capacitive element connected to the battery and calculating a standard deviation value based on the measured voltage value and based on a theoretical voltage value estimated from a model of the measurement circuit. The model is a function of a capacitance value of the capacitive element. The method also includes calculating an averaged deviation value from the standard deviation value and previous deviation values and estimating an updated insulation resistance value in accordance with the averaged deviation value.

Abstract: A controller for driving a motor includes a multiphase driver, an analog-to-digital converter (ADC), impedance estimation circuitry, and fault detection circuitry. The multiphase driver is configured to generate drive signals for energizing each motor phase winding. The ADC is configured to digitize voltage and current from each motor phase winding. The impedance estimation circuitry is configured to determine a phasor value for the digitized voltages and for the digitized currents at a predetermined harmonic frequency, and to determine a sequence impedance value based on the phasor values. The fault detection circuitry is configured to identify a fault in the windings of the motor based on the sequence impedance value.

Abstract: A electromagnetic machine system includes a rotor and a stator positioned about the rotor. A current injection mechanism is coupled with windings of the stator and structured to inject electrical currents therein so as to change a flux distribution of a magnetic field produced by the stator. The injected currents may be harmonic currents. The rotor further includes an inductor positioned to interact with the magnetic field when the flux distribution is changed, to produce an electrical excitation current for exciting windings in the rotor. The machine system may be a synchronous motor or generator, and may be brushless. Applications of the current injection strategy to direct torque control and vector control are also disclosed.

Abstract: A multispeed alternating current (AC) machine circuit is for an AC power source having a first side and a second side. The AC machine circuit includes two or more pairs of power switches, one or more windings, and a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source.

Abstract: A system and method to detect an onset of motor rotation for an induction motor. The system and method involves monitoring a power supplied to a motor via a sensor, determining a power quantity based on the power monitored by the sensor, detecting an envelope of the power quantity, detecting an onset of rotation of the motor when an amplitude of the envelope has increased, and inhibiting power flow to the motor when the onset of rotation does not occur within a predetermined time period or logging a first time period of the detected onset of rotation of the motor for use in monitoring the condition of the motor. The power quantity can be a current vector magnitude or an instantaneous power corresponding to the supplied power.

Abstract: One embodiment includes a system including an actuation system of a gas turbine system including an actuator, a positioner including one or more sensors, a motor, and a controller communicably coupled to the positioner and the motor. The actuator is coupled to one or more inlet guide vanes (IGVs) or variable stator vanes (VSVs) and configured to move the IGVs or VSVs, the positioner is configured to position the actuator so that the actuator moves the IGVs or VSVs to a desired angle, the motor is configured to drive the actuator, and the controller is configured to establish one or more baselines for one or more types of data obtained by the sensors at initialization of the gas turbine system, derive a deviation from the baselines, and perform a preventative action if a deviation that meets or exceeds a threshold is derived.

Abstract: Technical solutions are described for a motor control system that includes a feedforward control module to control an output torque generated by the motor. The feedforward controlling includes computing a first voltage command for the motor based on an input torque signal. Further, the feedforward controlling includes computing a second voltage command for the motor based on a brush drop voltage of the motor and a back-EMF drop voltage of the motor. Further, feedforward controlling includes computing a voltage command for the motor by summing the first voltage command and the second voltage command. Further yet, the feedforward controlling includes sending the voltage command to the motor for generating the output torque.

Abstract: This disclosure relates to systems and methods for electrical signature analysis of electrical rotating machines. In one embodiment of the disclosure, a method includes ascertaining initial information associated with an electrical rotating machine, assigning a plurality of operational conditions associated with the machine to a plurality of buckets, and recording the electrical data to obtain a pre-defined number of sets of learning data. The method further includes determining, based at least on the initial information and the learning data, that the machine is in a healthy condition, obtaining, based on the learning data, baseline data associated with at the at least one bucket, and generating, based on the baseline data, a threshold associated with the bucket and at least one fault frequency associated with the machine. The method further includes generating, based on the threshold and the baseline data, alarms concerning a state of the electrical rotating machine.

Abstract: A shaft grounding and monitoring system may include a grounding member slidingly engageable with a rotating shaft. An electrical sensor may be configured to be coupled with the grounding member in order to detect an electrical parameter that provides an indication of electricity flowing from the rotating shaft to ground through the grounding member. A processor may be operably coupled with the electrical sensor and may receive and analyze data from the electrical sensor. The processor may be configured to periodically analyze the data representing the electrical parameter from the electrical sensor at a sampling rate and for a sampling period that is related to a rotation speed of the rotating shaft. A memory may be operably coupled with the processor and may be configured to store data processed by the processor that is representative of the data provided by the electrical sensor.

Abstract: A method for detecting a short circuit (10) of a resolver exciter line (11, 12) comprising the steps of: measuring (31) the excitation voltage (U(ti) for the resolver (16) at a number of points in time during each excitation period; determining (32) the amplitude of the excitation voltage; starting a diagnostic mode (33) having the following steps (34 bis 37) if the amplitude of the excitation voltage does not reach a first threshold value; retrieving (34) the time-dependent voltage curves UH (ti) of the first and the second exciter line (H; 11) with respect to ground at the number of points in time; calculating (35) the amplitudes and the offset values of the time-dependent voltage curves; identifying (36) the exciter line that has a short circuit by determining that the calculated amplitudes do not exceed a second threshold value; identifying (37) the potential to which the short-circuited line (H or L) can be connected by comparing the offset values to third threshold values.

Abstract: A vehicle includes an electrically-driven motor configured to actuate a vehicle component and a power source configured to provide power to the motor over an electrical circuit. The vehicle also includes a controller programmed to monitor at least one signal indicative of motor output and store data indicative of a resistance in the circuit. The controller is also programmed to issue a resistance state of health signal in response to the resistance in the circuit exceeding a predetermined resistance threshold.

Abstract: Detection and protection against electric power generator stator ground fault conditions in multiple-generator high-impedance grounded installations is provided herein. In one embodiment, a generator protection element may block a determination of a fault using third harmonic voltages when the third harmonic voltage from the generator is less than a factor of the maximum third harmonic voltage from all of the generators on the common bus. A tripping subsystem may issue a trip command based upon detection of a stator ground fault condition.

Abstract: Systems, devices, methods, and techniques are disclosed for performing calibrated measurements of current through switches in an electronic control unit. In one example, a device includes a current sensor system; a controller, operably connected to the current sensor system; and one or more switches, operably connected to the controller. The current sensor system is configured to receive a measurement of current conducted through at least one switch of the one or more switches. The current sensor system is further configured to perform a measurement of calibrated total current for the one or more switches. The current sensor system is further configured to determine a calibrated value of current for the at least one switch, based at least in part on a comparison of the measurement of current conducted through the at least one switch and the measurement of calibrated total current for the one or more switches.

Abstract: For detecting a crack formed on a structure surface without erroneously, an information processing device that detects a crack on a structure, includes a change detection unit that detects a change in positions of at least two measurement points on the structure; and a crack detection unit that detects a crack based on the change in the positions of the measurement points detected by the change detection unit.

Abstract: A water-tree resistance evaluation material including: a material selection selecting a candidate insulation material; a test carrying out a water tree test on a test piece having electrode holes formed on a first surface; and a candidate insulation material evaluation evaluating characteristics of the candidate insulation material, including progress and speed of a water tree. The test includes: a system and condition setting for setting a test system; a voltage application for grounding a ground-side electrode that is immersed in the ground-side aqueous solution, while applying an AC voltage to an application-side electrode that is immersed in the application-side aqueous solution; a measurement step; and a period determination for determining whether a test period has exceeded a predetermined period.

Abstract: An electric power system for supplying power to a permanent magnet electric machine includes a high-voltage DC power source that is disposed to supply electric power to a front-end converter connected via a high-voltage DC bus to an electric inverter that is connected to the electric machine. A method for operating a control system includes monitoring the electric machine. Upon detecting a fault associated with the electric machine, a controller commands operation of the front-end converter to generate a voltage level on the high-voltage DC bus that is a maximum setpoint voltage level and monitors back-emf voltage level from the electric machine. The inverter is controlled to a three-phase open state when the back-emf voltage level is less than the maximum setpoint voltage level. The inverter is controlled to a three-phase short state when the back-emf voltage level is greater than the maximum setpoint voltage level.

Abstract: A system and method for detecting, localizing and quantifying stator winding faults in AC electrical machines is disclosed. A diagnostic system configured to detect a stator winding fault in an AC electrical machine includes a processor programmed to receive measurements of three-phase voltages and currents provided to the AC electrical machine from voltage and current sensors associated with the electrical distribution circuit, compute positive, negative and zero sequence components of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (FSI) based on at least a portion of the positive, negative and zero sequence components of voltage and current, wherein calculating the FSI further comprises identifying a voltage gain in one or more phases of the AC electrical machine due to a stator winding fault and localizing the stator winding fault to one or more phases in the AC electrical machine.

Abstract: An electric appliance monitor method and an monitor system are provided. The method includes the following steps. In a sampling period, data of an electric appliance is transmitted to a cloud server, and a load boundary is determined. The electric appliance is detected to obtain a measured power factor, a measured root-mean-square voltage and a measured power. Further, a supply frequency of an electric supply is recognized. Based on the measured data, a real part and an imaginary part of the load current related to a reflection coefficient of the electric appliance during the current usage state is calculated. On a real-imaginary current coordinate system, the load boundary and a coordinated point representing to the real part and imaginary part of the load current are displayed. Whether to execute a protection process is determined according to the load boundary, the real part and the imaginary part of the load current.

Abstract: A method to reduce acoustic noise in a cooling fan motor is disclosed. The method includes reducing the slew rate of a PWM (pulse width modulation) voltage waveform applied to energize a coil of the fan motor. This slew rate reduction results in lower mechanical vibrations and acoustic noise in the fan motor. In one embodiment, the slew rate reduction is performed during startup of the fan motor, when the motor is spinning slowly and there is little air flow noise. In another embodiment, the slew rate reduction is not performed during high speed operation of the fan motor, when the fan motor is spinning very fast and air flow noise masks the motor noise. In one embodiment, there is variable slew rate control depending on the speed of the fan motor.