Abstract: An apparatus for protecting a motor includes two or more motor overloads, within a motor overload enclosure, protecting two or more motors. Each motor overload includes one or more current sensors where each current sensor includes a magnetic core and each current sensor includes a conductor positioned within the magnetic core where the conductor providing power to a motor protected by the two or more motor overloads (“protected motor”). Each motor overload includes a motor trip module that stops current flow to the protected motor in response determining that a thermal state of the protected motor has reached a thermal limit. Determining that the protected motor has reached a thermal limit includes using a current signal from at least one current sensor of the one or more current sensors that senses current of the protected motor to determine a thermal state of the protected motor.

Abstract: A implantable pump system comprises an implantable pump motor and an external unit. An inverter comprises respective phases with redundant legs connected in parallel, and respective current sensors in series with each leg generating a respective measured current. A cable redundantly couples the inverter to the motor. The cable includes a respective conductor coupling each redundant leg to a respective phase of the motor. The controller receives the measured currents, monitors for a fault in the conductors by comparing the measured currents in the respective redundant legs. A fault in a pair of redundant conductors is detected if a ratio of the respective measured currents is not within a predetermined range.

Abstract: System and methods for protecting motors of a vehicle are provided. A system includes a current transformer device for each phase of the three-phase power received by each protected motor. Each current transformer device includes a switch that is normally in a first position and is configured to monitor an output current of fuse through which the power is transmitted, compare the output current to a threshold current level, and, when the output current is below the threshold current level, change the switch to a second position. The system also includes a processing circuit configured to control operation of the one or more motors of the vehicle. The processing circuit is configured to determine whether one or more of the switches of the plurality of current transformer devices is in the second position and, if so, activate a fault condition.

Abstract: A method and system for detecting a fault of a serial coil type permanent magnet motor includes driving the motor based on a predefined current reference value, detecting a phase current vector of the motor, and calculating a current compensation value for removing a negative sequence component of the motor based on the phase current vector. The current compensation value is provided to a negative sequence current controller for calculating a faulty phase and a degree of a fault of the motor using the output of the negative sequence current controller and a fault model to which induced magnetic flux variations in a specific slot of a specific faulty phase of the motor and other slots of the same phase as the specific phase are applied, and applying a current reference value to which the calculated faulty phase and degree of fault are applied.

Abstract: A motor control device for controlling a three-phase brushless motor that has a rotor and field coils includes: a load range determining unit that determines a rotor rotation angle range, in which the three-phase brushless motor becomes a load, as a load range when a short-circuit fault occurs in one of a plurality of switching elements. The load range determining unit determines a rotor rotation angle range, in which load current is presumed to flow through a closed circuit formed of the short-circuit switching element and any one of regenerative diodes connected in parallel with the respective normal switching elements when the rotor is rotated in a state where all the switching elements other than the short-circuit switching element are turned off, as the load range.

Abstract: A motor controller with a reverse-bias preventing mechanism includes a pre-charging unit, a protection unit, a conversion unit and a control unit. The pre-charging unit receives a power signal through a first electric-conduction path, and converts the power signal into a pre-charging signal according to a control signal. The protection unit receives the power signal through a second electric-conduction path, and determines whether to output the power signal, according to the polarity of the power signal. The conversion unit, coupled to the protection unit, receives the power signal outputted by the protection unit, and converts the power signal into a work voltage. The control unit, coupled to the conversion unit and the pre-charging unit, receives the work voltage to generate the control signal. The current of the power signal flowing through second electric-conduction path is smaller than the current flowing through first electric-conduction path.

Abstract: The present invention is a method and system for monitoring the continuous flow of power delivered by multiple DC Direct current operated starter motors used to start engine driven electrical generators. The method and system comprise the closing of a starter battery system and an associated starter control switch, causing the starter battery system to discharge through a shunt whereby current is fed into a starter motor. The shunt is optionally provided as a precision resistor with a pre-calibrated voltage drop in millivolts DC proportional to a current passing through it. The shunt directs current to a meter relay, which is calibrated by establishing two set points, or desired trigger ranges, for the meter relay. If the current falls outside a range established by the two set points, then a meter relay alarm output is activated; and, if the current remains within the range, then the meter relay alarm output is not activated.

Abstract: In an electric motor control apparatus, an electric motor driving unit includes: a current detection unit configured to detect a current flowing through a current detection place in the electric motor driving unit. A control unit includes a current calculation unit configured to calculate a current value of a current flowing through an electric motor from an offset correction value obtained based on a first detection value detected at a time when a current flows through the current detection place and a second detection value detected at a time when a current does not flow through the current detection place. The offset correction value includes: a first offset correction value stored in nonvolatile memory of the control unit at a time of assembling the electric motor control apparatus; and a second offset correction value computed by the control unit while the electric motor is driven.

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: An electric vehicle is proposed which can achieve early detection of abnormal short-circuit of motor coils, thus avoiding various driving problems. The electric vehicle includes a motor unit configured to drive a wheel. The motor unit includes a synchronous motor with three-phase motor coils. The three-phase motor coils include a first motor coil, a second motor coil and a third motor coil of different phases. One end of the first motor coil, one end of the second motor coil and one end of the third motor coil are connected with each other at a neutral point in a star connection. The electric vehicle also includes an abnormal short-circuit monitor configured to detect an abnormal short-circuit of the motor coils, and also includes an abnormalities-responsive disconnection unit configured to electrically disconnect the motor coils from the neutral point.

Abstract: In an electric motor control apparatus, an electric motor driving unit includes: a current detection unit configured to detect a current flowing through a current detection place in the electric motor driving unit. A control unit includes a current calculation unit configured to calculate a current value of a current flowing through an electric motor from an offset correction value obtained based on a first detection value detected at a time when a current flows through the current detection place and a second detection value detected at a time when a current does not flow through the current detection place. The offset correction value includes: a first offset correction value stored in nonvolatile memory of the control unit at a time of assembling the electric motor control apparatus; and a second offset correction value computed by the control unit while the electric motor is driven.

Abstract: A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.

Abstract: The invention concerns a monitoring method and system for monitoring an electric motor, comprising: modelling means (5) for modelling a circle diagram (31) based on current intensities of said electric motor, calculating means (7) for calculating at least one operational parameter by using said circle diagram, said operational parameter being anyone out of the following operational parameters: torque, resistive loss, rotor resistance, slip, and motor yield, monitoring means (9) for monitoring said electric motor (3) based on said operational parameter.

Abstract: A controller for switching an inverter includes a current detecting unit, an overcurrent level determining unit which determines an overcurrent level for stopping the inverter in accordance with a value corresponding to the number of revolutions of a motor, a current comparing unit which compares a detected output current value of the inverter with the overcurrent level, and a gate signal generating unit which generates a signal for turning off all semiconductor switching devices of the inverter when the current comparing unit makes a determination that the detected output current value has reached the overcurrent level. The overcurrent level is lowered as the number of revolutions of the motor increases.

Abstract: In the field of motor protection for industrial automation systems, HVAC systems, pumping systems, and/or similar implementations, improved motor starters and overload electronics can be configured to offer substantially automatic levels of protection for motors, independent of such starters and/or overload electronics first being calibrated for, or properly calibrated for, the motor.

Abstract: In the field of variable-speed motor control, a bypass circuit and corresponding bypass electronics can be integrated advantageously with a variable-frequency drive (“VFD”) circuit and corresponding electronics. Such an integrated bypass can be disposed within a single unitary enclosure housing the VFD. Some advantages of the integrated bypass include reduced size, cost, and/or complexity in the combined VFD/bypass assembly, the ability to manage airflow in bypass without running a fan motor full time, and support for integrated power metering.

Abstract: A feed chain (16) has M feed outputs (31) for supplying a synchronous electric machine (14) with M phases. The feed chain comprises: a converter (22) for converting a direct input current into a polyphase alternating current; a storage bank; a detector (30) for detecting a short-circuit outside or inside the electric machine (14), a device (26) for insulating the electric machine (14) from overvoltages and/or overcurrents of the polyphase alternating current, and a controller (28) for controlling the converter (22) and the insulating device (26). The feed chain (16) includes short-circuiting device (27) capable of connecting the M power supply outputs (31) to each other, the controller (28) being capable of commanding the short-circuiting device (27) to perform that operation.

Abstract: A protection relay for an electrical switching apparatus for a load includes a number of voltage sensors structured to sense voltage applied to the load, a number of current sensors structured to sense current flowing to the load, and a processor cooperating with the number of voltage sensors and the number of current sensors. The processor determines a fault current available at the load. An output cooperates with the processor. The output is structured to output the determined fault current and a number of: incident energy at the electrical switching apparatus, and a personal protective equipment level operatively associated with the electrical switching apparatus. The processor determines from the determined fault current the number of: the incident energy at the electrical switching apparatus, and the personal protective equipment level operatively associated with the electrical switching apparatus.

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: An integrated drive motor (IDM) power distribution architecture utilizes an IDM power interface module (IPIM) to create a control voltage that is distributed to all the IDMs in a network. This power distribution may be accomplished along a hybrid cable, for example, that includes both signal conductors and power conductors. The IPIM is capable of detecting short circuits and/or overload conditions and disabling the power supply to the IDMs. Additionally, a second power supply may be utilized in the IPIM such that when the power supply to the IDMs is deactivated, the IPIM may remain functional, for example, to report one or more fault conditions to the user. Additionally, this reporting of fault status may be accomplished via a user display integrated with or coupled to the IPIM.

Abstract: A relay module includes a case forming an exterior of the relay module, a Positive Temperature Coefficient (PTC) device configured to control the supply of power to the compressor, a holder mounted at the case and configured to accommodate the PTC device, a start capacitor electrically connected to the PTC device, a first connecting terminal having a first PTC connecting terminal connected to the PTC device and a first capacitor connecting terminal connected to the start capacitor, and a second connecting terminal having a second PTC connecting terminal connected to the PTC device and a second capacitor connecting terminal connected to the start capacitor. The first capacitor connecting terminal and the second capacitor connecting terminal are spaced apart a predetermined distance from a bottom surface of the case.

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 circuit for controlling a load current through a coil is connected to an output port of a transistor H-bridge that includes two low side transistors and two high side transistors. A current sense circuit is coupled to the H-bridge and configured to provide a representation of the load current provided by the output port. A current regulator is configured to generate a modulated signal dependent on the representation of the load current and a current set-point. The modulated signal has a duty-cycle. A gate control logic drives the individual transistors of the H-bridge on and off in accordance with the modulated signal. A direction signal provides the load current to the coil. The direction signal determines the direction of the load current. An over current detection circuit is coupled to each individual transistor and is configured to signal an over-current by providing an active over-current failure signal when a transistor current through the respective transistor exceeds a respective maximum value.

Abstract: A protective circuit arranged on a Printed Circuit Board (PCB) has two conductor loops. At least one supply voltage track, at least one semiconductor switch and at least one control component are arranged on the PCB. A first terminal of the control component and a first terminal of the semiconductor switch are connected electrically. A first conductor loop of the protective circuit is arranged on the PCB so that it surrounds an electrically conducting connection between the supply voltage track and the semiconductor switch and/or the control component. A second conductor loop is arranged on the PCB so that it surrounds the electrically conducting connection between the first terminal of the control component and the first terminal of the semiconductor switch, and thereby screens the same from the semiconductor switch and at least from those regions of the control component that are also connected to the supply voltage track.

Abstract: Methods and apparatus are provided for detecting a phase current sensor fault in a multi-phase electrical motor. The method comprises, receiving an input torque command T* and measuring a set of feedback signals of the motor including a phase current Ix for each of the phases of the motor, generating direct and quadrature command phase currents Id*, Iq* for the motor corresponding to a value of the input torque command T*, determining a total command current Is=[(Iq*)2+(Id*)2]½, generating a negative sequence current Ineg, where for three phases Ineg=(?)[Ia+(?2)Ib+(?)Ic], where ?=ej2?/3, combining Ineg and Is to provide a normalized negative sequence current Inn=Ineg/Is, comparing the normalized negative sequence current Inn to a predetermined threshold value INN* to determine the presence of a phase current sensor fault, and executing a control action when Inn>INN*.

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: A digital thermal model for compensating for error in a current transformer used in a solid-state overload relay. The thermal model implements a difference equation that determines using a low-pass filter two parameters corresponding to calibration points along an overload trip curve. The trip curve is adjusted at an ultimate trip current (one calibration point) independently of a trip time at a locked rotor current (another calibration point) of a motor protected by the overload relay. The ultimate trip current and trip time can be adjusted based on a motor full load current set by a user. Large CT error will cause the thermal model to adjust the trip time at the locked rotor current, increasing the range of acceptable CT error, allowing the overload relay to have a wider adjustment range.

Abstract: An over-current protection device for multiple high-voltage motive devices is provided. The over-current protection device includes a comparison module and a logic operation module. The comparison module receives a plurality of voltages generated from a plurality of operating currents of a plurality of high-voltage motive devices and respectively compares the voltages with at least one reference voltage to generate a plurality of comparison results, wherein the high-voltage motive devices are solenoids, electronic clutches, or a combination of solenoids and electronic clutches. The logic operation module receives the comparison results and generates at least one control signal for a plurality of high-voltage motive device driving circuits according to the comparison results. The high-voltage motive device driving circuits respectively drive the high-voltage motive devices according to the control signal.

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

Abstract: An over current protection system includes a current sensing member configured and disposed to output an electrical rate of change signal that is indicative of a rate of change of an electrical current being in excess of a predetermined value, at least one micro electro-mechanical switch (MEMS) device operatively connected to the current sensing member, and a controller electrically coupled to each of the current sensing member and the at least one MEMS device. The controller is configured and disposed to open the at least one MEMS device in response the electrical rate of change signal.

Abstract: A ground fault sensing device for a drive system that converts direct current electrical power from a direct current power supply into alternating current electrical power and drives an electric motor with that alternating current electrical power, comprises: an extraction circuit that is connected to a power supply line of the direct current power supply via a coupling capacitor, that detects an amplitude wave that is generated when an alternating current side including the electric motor is suffering a ground fault, and that extracts the envelope of the amplitude wave; a measurement circuit that measures the voltage level of the envelope; and a determination circuit that makes a decision as to whether or not a ground fault has occurred on the alternating current side by comparing together the voltage level measured by the measurement circuit and a ground fault decision value.

Abstract: A supervision and protection device for an electric capstan that is able to provide an alarm, has good reliability and a long life time, and only requires a short period of time to recover to use after overloading. The supervision and protection device may include an overload signal collection module, a central processing module and an executing module. The overload signal collection module includes a current diverter, one end of which is electrically connected to the negative pole of the DC electrical motor of the electric capstan and the central processing module, and the other end of which is grounded. The executing module includes a sound alert unit and an electrical motor ON/OFF control unit, and the electrical motor ON/OFF control unit is provided to control the start/stop of the ON/OFF unit which is in series connected to the input circuit of the DC electrical motor. The central processing module is also electrically connected to the sound alert unit and the electrical motor ON/OFF control unit.

Abstract: A protection circuit for brushed DC motors connected between an AC power supply input and a rectifier circuit, including a power supply line, a power supply circuit, an AC detection circuit, a rectifier/filter voltage-stabilizing circuit, a microprocessor, a drive circuit, and a switching unit. The switching unit is connected to the power supply line in series. An input terminal of the power supply circuit is connected with the AC power supply input. The AC detection circuit receives current signals from the power supply line. The current signals are processed by the rectifier/filter voltage-stabilizing circuit and sent to the microprocessor. An output terminal of the microprocessor is connected to an input terminal of the drive circuit, and the drive circuit controls the switching unit to connect or disconnect the power supply circuit.

Abstract: A motor detecting and protecting apparatus electrically connected with a motor. The motor detecting and protecting apparatus includes a detecting unit, an error determining unit, a controlling unit and a driving unit. The detecting unit detects a state of the motor and outputs at least one first detecting signal and at least one second detecting signal to the error determining unit. The error determining unit has a first predetermined value, wherein the error determining unit outputs a warning signal to the controlling unit while a variation value between the first detecting signal and the second detecting signal exceeds the first predetermined value. And the controlling unit will control the motor to stop operating by the driving unit in accordance with the warning signal. And a motor detecting and protecting method is also disclosed.

Abstract: An electric machine assembly with fail-safe arrangement is described. The assembly comprises a stator including a plurality of windings and a cooperating rotor including at least one permanent magnet; a detector configured to detect DC current in at least one of the windings of the stator; and a bypass circuit configured to be activated upon detection of the DC current by the detector and to prevent at least some of the DC current from flowing into the at least one of the windings of the stator.

Abstract: Systems and methods for providing overcurrent circuit protection are disclosed. A method of providing overcurrent circuit protection may include setting a threshold current value according to an operational state of a motor and sensing an amount of current being supplied to the motor. The method may further include electrically isolating the motor from a current source if the sensed current amount is greater than the threshold current value.

Abstract: A drive apparatus includes a magnet rotor having a plurality of magnetic poles that are magnetized, a stator having a magnetic pole portion that opposes each pole of the magnet rotor, a coil configured to excite the magnetic pole portion, a position detector configured to detect a position of the magnet rotor, a first driver configured to switch an electrification state of the coil in accordance with a preset time interval, a second driver configured to switch an electrification state of the coil in accordance with an output of the position detector, and a controller configured to select the first driver when the output of the position detector is less than a first threshold, and to select the second driver when the output of the position detector is equal to or larger than the first threshold.

Abstract: An apparatus for detecting and controlling current. A current detector for generating a first value that represents an amount of current being delivered to a device. A current limit circuit for generating a second value that represents a maximum permitted current level from a current source. A current controller for controlling the amount of current drawn by the device if the first value exceeds the second value.

Abstract: The inverter device includes an IGBT bridge circuit, a drive block which has an upper arm photocoupler and a lower arm photocoupler, and a control block including a CPU which generates gate signals and supplies them to the photocouplers. The control block includes an upper arm shutdown circuit and lower arm shutdown circuit which individually shutdown the gate signals of the upper arm and lower arm IGBTs in accordance with shutdown signals input from the exterior, and the shutdown circuits carry out a shutdown operation in accordance with the shutdown signals, which have mutually inverted logics.

Abstract: An electrical monitoring device for monitoring an electrically powered device is provided. The monitoring device includes a frame for placement onto a conductor of the electrically powered device. A sensor is present for detecting the amount of current passing through the conductor. Also, a display may be provided for indicating to the user parameters of the electrically powered device that are indicative of the current passing through the conductor.

Abstract: A power conversion device includes: an inverter that drives an alternating-current motor by converting a direct-current voltage into an alternating-current voltage of an arbitrary frequency; an alternating current disconnecting switching unit connected between the inverter and the alternating-current motor; a current detector that detects an output current of the inverter; and a controller that performs on/off-control of the plural switching elements in the inverter and switching control with respect to the switching unit, based on at least a current detected by the current detector. The controller has a configuration to be able to interrupt a fault current by setting the fault current to a state of generating a current zero point, when the fault current containing a direct-current component is generated between the inverter and the alternating-current motor.

Abstract: A heat source apparatus in which a control device of the heat source apparatus can ascertain a stoppage of an inverter device and in which a stable operating time of the heat source apparatus can be extended is provided. The heat source apparatus includes an electric compressor that is driven by an inverter device and that compresses a refrigerant, the inverter device having a protective function that performs stoppage for device protection on the basis of a predetermined calculation by an inverter control portion, and a control device that controls cold output and/or heat output. The control device includes an inverter-protective-function estimating unit that estimates a calculation result of the protective function of the inverter control portion.

Abstract: Method and arrangement for connecting an AC electric motor (M1, M2, . . . MN) to an AC electricity network (L) in a system which comprises a frequency converter (FC), with which the motor is started, and contactors (S11, S12, S21, S22, SN1, SN2), in which method the supply source is changed by means of the contactors from the frequency converter to a direct network supply, in which method the frequency converter is stopped before changing the supply source, and in which method in connection with changing the supply source the control of the contactors is started before stopping the frequency converter.

Abstract: A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.

Abstract: An electrical power diagnostic system includes a system housing, a power saw management system, and a user interface. The system housing is electrically connected with the power unit of the power saw, wherein the system housing includes a control panel provided thereon for allowing a user to adjust an operational parameter through the control panel. The power saw management system includes a control processor mounted within the system housing to electrically communicate with the power saw, wherein the control processor is pre-programmed to manage operational parameters of the power saw and supervise actual operation of the power saw machine and the saw blade in such a manner that when abnormal operating condition of the power saw machine is detected, the control processor is adapted to selectively adjust the operational parameters of the power saw machine for stopping the abnormal operating condition from continuously happening.

Abstract: An electric power supply device capable of miniaturizing an FET and wiring and reducing the amount of heat generation even when a motor load goes into a lock state is provided. It is determined whether or not a lock current flows in a motor M1 by comparing various determination voltages with a voltage Vds between a drain and a source of a MOSFET (T1), and in the case of detecting that the lock current flows, an operation of turning off the MOSFET (T1) until a retry cycle to elapses after turning on the MOSFET (T1) for only energization time tb for which lock torque can be caused is repeatedly executed. Then, when a motor current ID becomes smaller than the lock current, control of returning the MOSFET (T1) to a normal operation is performed. Consequently, the lock current can be prevented from flowing continuously.

Abstract: A motor overload protecting method includes (a) detecting an instantaneous motor current value in real-time, calculating a current integral value in each of a corresponding integral period, and resetting the current integral value to 0 at an end of the integral period, (b) obtaining an overload coefficient according to the current integral value, which is greater than or equal to 0 and less than 1 when the current integral value is greater than or equal to a maximum motor current value, and is equal to 1 when the current integral value is less than the maximum motor current value, wherein the maximum motor current value is a maximum current integral value when the motor is in a non-overload condition; and (c) multiplying the instantaneous motor current value by the overload coefficient to obtain a new input current value, and operating the motor according to the new input current value.

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: An overload relay protects a motor or other device from an overload condition and a power supply unit supplies power to the overload relay. The overload relay has: shunt resistors, each being locatable in the current path of a respective supply line of a power supply for the motor or other device; and control mechanism connected to each shunt resistor and arranged to receive signals representative of current through each shunt resistor. The control mechanism produces a trip signal to interrupt the continuity of the power supply if it determines that an overload condition exists based on one or more of the signals. The power supply unit has: a rectifier producing a direct current from one or more supply lines of an AC power supply connected to the motor or other device; and at least one transformer coupling the power supply unit to the overload relay.

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.