Abstract: A method for operating a brushless electric motor, the windings being energized by an inverter with the aid of six switches. A detection unit for detecting defective switches, a unit for measuring voltage at the outputs of the inverter, and a microcontroller for controlling the switch and for generating a pulse width modulated voltage supply for the windings are provided. A short-circuited switch causes a torque in the electric motor opposite the actuating direction of the electric motor. The method proposes that after detecting a short-circuited switch, the windings (U. V. W) are energized to generate a motor torque that is, on the whole, positive. An actuating period of the electric motor is divided into a plurality of sectors, wherein, in accordance with the defective switch, individual sectors are deactivated for the actuation of the windings (U, V, W), while other sectors are used to actuate the windings (V, W).

Abstract: The system has a driving circuit for the motor of the electric fan, coupled to the electrical system of a motor vehicle and having a plurality of controlled electronic switches, and an electronic control unit arranged to control the driving circuit in such a way as to cause the flow in the motor of a variable average current capable of producing a required speed of rotation, in accordance with a predetermined relationship or function. The control unit is designed to store a predetermined threshold of rotation speed, and to control the motor through the associated driving circuit in such a way that when the rotational speed of the motor exceeds the threshold the driving circuit causes electrical braking of the motor.

Abstract: A motor drive circuit comprising: a drive circuit configured to supply a drive current to a drive coil of a motor; a control circuit configured to control an operation of the drive circuit; a locking protection circuit configured to control an operation of the control circuit so that the drive circuit stops supplying the drive current to the drive coil, if a rotation signal, indicating rotation of the motor, is not generated during a predetermined time period although the drive circuit is supplying the drive current to the drive coil; and a prohibition circuit configured to prohibit the locking protection circuit from controlling the control circuit.

Abstract: When an earth faulting has occurred in a driving device for driving a motor, a high voltage noise enters a high voltage detector through a connection node of the Y capacitor constituted by a pair of capacitors in DC/DC converter. A controller of the DC/DC converter limits the duty of switching elements constituting a full-bridge circuit on a primary side, in the case where a defect due to an earth faulting of the driving device is detected by a detection value of high voltage detector.

Abstract: A Variable Frequency Drive (VFD) supplies power to rotate a motor, controlling both the speed and direction. The method normally used for this power conversion by the VFD results in energy losses and line harmonics. When the motor is driven by the VFD to be rotating at the same speed and direction as if the motor was straight across the incoming AC power, a transfer in power supply to the motor can be made using contactors to bypass the VFD. When in this bypass mode, the energy losses of the VFD are greatly reduced, and the line harmonics due to the VFD are greatly reduced. When it is subsequently recognized that the speed reference has deviated from being the same speed and direction as if the motor was straight across the incoming AC power, a transfer in power supply can be made from using contactors to once again drive the motor from the VFD.

Abstract: A vehicle high voltage system may include contactors/relays, wires, a traction battery, electrical components, and at least one controller. The at least one controller may open the contactors to interrupt current flow to the components if anyone of a plurality of amp?hour measurement associated with the traction battery exceeds a corresponding predetermined threshold value.

Abstract: Disclosed herein are a motor protection device, a motor protection method, and a motor control system using the same. According to the present invention, the motor protection device including: a rotation speed change sensing unit that senses and outputs pulse widths of a pulse signal outputted from a rotation sensor installed in a motor; an abnormality determining unit that outputs abnormality-occurrence signal if the pulse widths of the pulse signal outputted from the rotation speed change sensing unit increase beyond a predetermined value; and a stopping unit that stops operation of a motor control system if the abnormality-occurrence signal is outputted from the abnormality determining unit, the motor protection method, and the motor control system using the same are provided.

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: According to the present invention, an overcurrent fault detection device includes: an inverter converting DC current to three-phase AC currents for driving a motor; a DC voltage detector; phase current detectors; a rotational position detector that detects a rotational angle of the motor; a control circuit that controls a gate drive circuit, which controls the inverter at every predetermined cycle, based upon the phase current values, a motor rotational angle detection value, and a speed command or a torque command from a higher-order control device; and a first decision-making circuit that detects an overcurrent based upon the phase current values at every predetermined cycle, wherein: the first decision-making circuit determines whether or not the phase current values exceed a predetermined amplitude threshold value by frequency detection for any of the phase current values exceeding the predetermined amplitude threshold value, and determines that an overcurrent has occurred upon detecting the frequency.

Abstract: The apparatus for preventing a secondary accident by short of sensing lines in a high voltage battery using a fuse, includes: a plurality of battery modules provided with a plurality of battery cells; a battery pack including a plurality of battery modules; a battery management system (BMS) for monitoring and controlling voltage of each battery cell provided in each battery pack to monitor the status of each battery cell; sensing lines connected between the battery module and the battery management system to sense voltage of each battery cell of each battery pack; and a passive safety device to be connected in series to a terminal of each battery cell provided in each battery pack when a short accident that a closed circuit is formed in the sensing line occurs.

Abstract: A soft start circuit for a forward/reverse rotation fan includes a forward/reverse switch unit, a soft start activation unit, a soft start control unit, a Hall IC and a driver IC, wherein the soft start activation unit comprises a first signal transmission loop and a second signal transmission loop. The soft start circuit activates the soft start control unit via a first instantaneous signal outputted by the first signal transmission loop or a second instantaneous signal outputted by the second signal transmission loop to make the soft start control unit output a control signal to a speed control terminal. When the rotating direction of fan is switched from one direction into another, the fan starts rotation in a soft start mode owing to high level of the control signal transmitted from the soft start control unit to the speed control terminal during initial rotation of the fan.

Abstract: A fault tolerant electrical machine including: a plurality of phases; a detector arranged to detect a fault in at least one of the phases; and a controller arranged to intentionally cause a fault in at least one other of the phases such that the vector sum of the second harmonic power vectors of the remaining phases is zero.

Abstract: A steering control apparatus includes a direct current power source, a three-phase alternating current motor, and a motor driving circuit. An emergency switching element is provided on at least two phases of a three-phase power supply line connected to the three-phase alternating current motor within the motor driving circuit, and the emergency switching element is turned off when an abnormality occurs such that the motor driving circuit is disconnected from the three-phase alternating current motor. The emergency switching element is a MOSFET, and the MOSFETs are provided in pairs in each of the two phases of the three-phase power supply line. Further, parasitic diodes of the pairs of MOSFETs are disposed in opposite orientations to each other.

Abstract: A robotic catheter control system includes a plurality of electric motors. Diagnostic logic automatically detects motor runaway fault conditions based on the current motor position, the target motor position and a predetermined tolerance parameter. Fault conditions include overshoot, movement in the a non-prescribed direction, exceeding a prescribed maximum motor speed and exceeding a prescribed maximum motor acceleration. The diagnostic logic terminates operating power to the electric motor when a fault condition is detected for any one of the motor. An error message is generated to notify the operator of the fault.

Abstract: A protection circuit includes a protection module and a fan electrically connected to the protection module. The protection module includes a control chip, an inverter, and an electronic switch. An input terminal of the inverter is electrically connected to a voltage output terminal and the fan, and further electrically connected to a clear pin of the control chip. An output terminal of the inverter is electrically connected to a preparation pin of the control chip. A first terminal of the electronic switch is electrically connected to an output pin of the control chip.

Abstract: An electronic control unit mounted on a vehicle includes: a capacitor that smoothes voltage of a DC power source electrically isolated from a body of the vehicle; a resistor circuit including a plurality of resistors connected in series, which is connected in parallel to the capacitor to discharge electric charge stored in the capacitor; and a fault judging circuit that judges whether or not the resistor circuit is in a fault condition by comparing the voltage across the resistor included in the resistor circuit with a fault threshold value. The fault judging circuit is adapted to change the fault threshold value based on the voltage of the DC power source.

Abstract: A drive force distribution control apparatus in which if a relay output voltage (Vah) detected by relay-output-voltage detecting means (30) is lower than a first threshold, the relay is repeatedly and successively turned on and off multiple times, and then if the relay output voltage (Vah) detected later by the relay-output-voltage detecting means (30) while an engine speed (Er) is higher than a second threshold and an ignition switch (IG) is on is still lower than the first threshold, it is determined that there is an abnormality that keeps the relay stuck open, and then control for switching the drive mode from a four-wheel-drive mode to a two-wheel-drive mode is executed.

Abstract: An electric protective switching device is configured as a modular system and includes a switching device base module including first mechanical guide elements and an installation space with electric contacts. A control module including control electronics, first mechanical elements and electric counter-contact elements is installable into the installation space. A communication module including second mechanical elements is configured as an interface between the control electronics and an electronic bus system. The control module and the communication module are connectable mechanically and electrically to the switching device base module.

Abstract: An electric circuit, including an electric load operable from an operating current; an energy storage system providing the operating current at both a first mode and a second mode with the first mode having a first current in a first range of zero to a first particular current value and with the second mode having a second current in a second range of the first particular current value to a second particular current value; and an active protection coupled to the energy storage system, the active protection dynamically reconfigurable between a first mode and a second mode, the first mode applying a first overcurrent protection rating to the operating current when the operating current is operating in the first mode and the second mode applying a second overcurrent protection rating to the operating current when the operating current is operating in the second mode.

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 suppression circuit may be added to a motor driver circuit, which suppresses offset voltage and ringing in the output signal. The suppression circuit may include an RC circuit filter connected to a pin of a microchip providing a gating reference signal and a junction between high and low side MOSFETS connected to the microchip.

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

Abstract: A drive circuit for delivering high-level power to a load, and method of stopping a high power load from operating, are disclosed. The drive circuit includes a high power circuit capable of being coupled to the load and delivering the high level power thereto, and a to power circuit that controls the high power circuit. The low power circuit includes a first circuit portion that provides at least one control signal that is at least indirectly communicated to the high power circuit and that controls the delivering of the high level power by the high power circuit, and a second circuit portions coupled to the first circuit portion. The second circuit portion is capable of disabling the first circuit portion so that the at least one control signal avoids taking on values that would result in the high power circuit delivering the high level power to the load.

Abstract: An electrical stepper motor comprises a magnetical rotor and at least two electromagnetical driving coils for causing rotation of the rotator. A method of detecting an operating condition of the as e.g. a stall state of the electrical stepper motor comprises the steps of connecting one contact pin (P, M) of at least one of the electromagnetical driving coils via a high-impedance resistor (R1, R2) to a defined voltage source during a non-activated state of the driving coil, detecting a voltage induced at the driving coil during the non-activated state and converting the detected voltage into a digital signal, and digitally analyzing the digital signal and deriving an operating condition of the rotor by evaluation of the signal waveform including positive and negative components of the signal.

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: A pulse signal output unit sends three-phase pulse signals according to movement of the movable member. A counter unit adds a first predetermined value or a second predetermined value to a count value or subtracts the first predetermined value or the second predetermined value from the count value, according to a combination of the pulse signals appearing when all the pulse signals are normal and a combination of the pulse signals appearing when one of the pulse signals malfunctions. A position detection unit detects the position of the movable member according to the count value.

Abstract: A traction motor drive system may include a plurality of armatures arranged in parallel with each other. The traction motor drive system may also include a plurality of field circuits arranged in series with one another, where each field circuit is associated with a respective one of the armatures. The plurality of field circuits may be arranged in parallel with the plurality of armatures. The traction motor drive system may also include a field isolation system. The field isolation system may include a shunt circuit associated with at least one of the field circuits. The shunt circuit may have a first and second shunt terminal. The field isolation system may also include a first field switch arranged in series with the plurality of field circuits. The first field switch may be configured to switch between the first shunt terminal of the shunt circuit and a first field terminal of at least one of the field circuits.

Abstract: Example embodiments disclose a drive system including a machine including a plurality of phases and configured to generate power based on a plurality of phase currents, each respectively associated with the plurality of phases and a direct current (DC) bus, operatively connected to the machine. The DC bus includes a high-side line, a low-side line, and an inverter including a plurality of switching systems, operatively connected between the high-side line and the low-side line, the plurality of switching systems, each configured to output a respective one of the plurality of phase currents. The drive system also includes a controller, operatively connected to the DC bus and the machine, the controller configured to determine if a failure exists in the drive system based on the plurality of phase currents and a DC bus voltage, the DC bus voltage being a voltage across the high-side line and the low-side line.

Abstract: High-power synchronous motors are commonly used in mining operations, for example, in gearless draglines, gearless conveyor drives, and gearless mill drives. Substantial electromagnetic energy is stored in the inductive field windings. In the event of a system fault, such as a short in the direct current power source exciting the field windings, the electromagnetic energy needs to be discharged from the field windings. This electromagnetic energy is typically dissipated as waste heat through a resistor. Disclosed is a field discharge system in which the electromagnetic energy is captured and stored as electrical energy in a capacitor. If an ultracapacitor bank is used for storage, the charged ultracapacitor bank can be used as a backup or auxiliary power source for mining operations. The discharge time is sufficiently small that high speed circuit breakers are not needed to disconnect stator windings from the alternating current power source when a fault occurs.

Abstract: Systems and methods for safely powering an appliance user interface without external power are provided. One exemplary method includes receiving power generated by rotation of a rotor. The method further includes monitoring for the presence of a safety condition and disabling passive braking of the rotor when the safety condition is present such that the user interface of an appliance is powered. An exemplary washing machine can include a basket and a motor which includes a rotor, the motor being configured to rotate the basket by rotating the rotor. The washing machine can further include a user interface and a motor control circuit configured to drive the motor. The motor control circuit can be further configured to receive power generated by rotation of the rotor, monitor for the presence of a safety condition, and disable passive braking of the rotor when the safety condition is present.

Abstract: A unit for recording operating information of an electronically commutated motor (ECM) is described. The unit includes a system controller communicatively coupled to an ECM. The system controller includes a processing device configured to control the unit. The unit also includes a memory device communicatively coupled to the system controller. The memory device is configured to receive and store ECM operating information provided by the processing device.

Abstract: A disconnection detecting device that can be applied to a control system of a motor-generator is provided. A disconnection detecting section judges whether logical conjunction (i.e. AND operation) of a condition that both current sensors are operating normally and a condition that the designated torque is equal to or more than a specified torque is true or not. In the event that the disconnection detecting section has determined YES, the disconnection detecting section judges whether the logical conjunction of a condition that the absolute value of the phase current is equal to or less than a specified current (>0) and a condition that the absolute value of the current change rate is equal to or less than a specified value (>0) is true or not. In the event that the disconnection detecting section has determined YES, the disconnection detecting section has determines that the disconnection has occurred.

Abstract: A fault detection system for an over-speed protection system of a rotating machine includes a first speed sensor, second speed sensor, and third speed sensor sensing a speed of a shaft of the rotating machine. The system includes a first input configured to receive a first pulse train from the first speed sensor, a second input configured to receive a second pulse train from the second speed sensor, a third input configured to receive a third pulse train from the third speed sensor, and a processor configured to generate a shutdown signal for the rotating machine based on the first pulse train, the second pulse train, and the third pulse train.

Abstract: A controller 43 turns on a semiconductor switch 41 in a normal mode, and turns off the semiconductor switch 41 in a sleep mode. A bypass resistor 5 is connected in parallel to the semiconductor switch 41. A resistance value of the bypass resister 5 is so large as that in the sleep mode, a dark current is supplied to an electronic device 3 via the bypass resistor 5, and if an electric wire downstream of the bypass resistor is short-circuited, an electric current more than a permissive current is prevented from flowing to the electric wire.

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: A controller that controls ON/OFF of switching elements and opening/closing of an opening/closing unit based on currents detected by current detectors. The controller includes a fault detector that detects whether any of the switching elements has a short-circuit fault and outputs a signal indicating a detection result, an ON/OFF controller that sets one of the switching elements that constitutes a phase other than a first phase that involves the short-circuit fault to an ON operation state and outputs a signal for opening the opening/closing unit, and an opening/closing controller that opens an opening/closing unit connected to a third phase other than the first phase and the second phase in which one of the switching elements is set to the ON operation state by the ON/OFF controller.

Abstract: Disclosed herein are various embodiments of devices and related methods for detecting an electrical arc event using a motor management relay and for suppressing the electrical arc event. The motor management relay may incorporate an optical arc-flash sensor configured to detect an optical event. Control logic may analyze the optical event and determine whether the optical event corresponds to an electrical arc event. When an electrical arc event is detected an instruction may be issued via a control port in communication with the control logic to implement a protective action. According to various embodiments, a plurality of sensors for monitoring electrical characteristics of a motor may also be in communication with the control logic. Input from the sensors may be analyzed in order to determine whether the optical event corresponds to an electrical arc event.

Abstract: A circuit assembly for an alternating current contactor has an excitation coil, wherein the excitation coil has at least one first winding for generating a pick-up and/or release current. A method for producing a power supply unit of an electric load includes using an excitation coil of an alternating current contactor having at least one first winding for generating a pick-up and/or release current.

Abstract: An electric motor and a control unit are juxtaposed in a speed reduction gear box. A terminal block is provided at an outer circumference of a flange proximate to a control unit of the electric motor. Terminal block surfaces of the terminal block are provided so that a plane direction faces a direction vertical to a shaft line of the electric motor. A motor side connecting terminal is held on the terminal block surface. The unit side connecting terminals provided at a position proximate to the electric motor of the control unit are arranged so as to overlap with the motor side connecting terminal on the terminal block surface to couple by a coupling portion (fixing screw).

Abstract: In a motor driving device, a driving switching element is connected in series with a motor between a power source and a ground, and operated by a PWM signal outputted from a control circuit. A return current path forming unit is connected in parallel with the motor to allow a return current when the driving switching element is turned off. A series circuit of a current flow restriction element and a switch is connected in parallel with the return current path forming unit. A disconnection determination unit prohibits output of the PWM signal and closes the switch of the series circuit when a voltage applied to the motor does not fluctuate according to the PWM signal, and determines the disconnection of the motor on condition that the voltage detected in that state indicates a change across a second threshold.

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 process for detecting an alarm in an operating machine (1), so that an operator (7) is able to interact with such a machine (1) determining a connection between the machine and the ground, comprising the steps of: determining a current value of a main parameter representative of an electric interaction between said operator (7) and said operating machine (1) under a condition of normal operation of said machine (1); comparing said determined current value with a main reference value; activating an alarm procedure as a function of said comparison.

Abstract: An intelligent electronic device (IED) may be configured to detect arc flash events within a power system using stimulus measurements acquired by detection devices communicatively coupled to the power system. An arc flash event may be detected using a time-intensity comparison metric, such as an inverse time-over-stimulus metric, a cumulative stimulus metric, or the like. The stimulus may include electro-optical (EO) radiation produced in the vicinity of the power system, current measurements, or the like. The IED may detect an arc flash event if one or more of the stimulus types are indicative of an arc flash event. Responsive to detecting an arc flash event, the IED, or other protective element, may take one or more protective actions, such as issuing trip commands, or the like.

Abstract: Power handling circuits that may be packaged as power modules, and methods of operating semiconductor devices in such circuits and modules. An exemplary circuit comprises power terminals to receive electrical power, a first semiconductor device, a first drive circuitry, and a second drive circuitry. The first drive circuitry provides a drive signal to the first semiconductor device in accordance with a desired circuit function when the electrical power received at the power terminals has the positive polarity, and ceases providing the drive circuit when the electrical power received at the power terminals has the negative polarity. During the negative polarity condition, the second drive circuitry provides a drive signals to the first semiconductor device which causes its primary current conduction path to conduct, thereby reducing the power dissipation in the device's parasitic path, and optionally causing a fuse in the circuit providing power to the circuit to blow.

Abstract: A drive circuit for delivering high-level power to a load, and method of stopping a high power load from operating, are disclosed. The drive circuit includes a high power circuit capable of being coupled to the load and delivering the high level power thereto, and a low power circuit that controls the high power circuit. The low power circuit includes a first circuit portion that provides at least one control signal that is at least indirectly communicated to the high power circuit and that controls the delivering of the high level power by the high power circuit, and a second circuit portions coupled to the first circuit portion. The second circuit portion is capable of disabling the first circuit portion so that the at least one control signal avoids taking on values that would result in the high power circuit delivering the high level power to the load.

Abstract: Motor drives, signal conditioning systems and configurable circuit boards are presented in which diode blocking circuits are provided for contemporaneous opening of programming fuses in multiple programmable impedance circuits using a single configuration input signal during manufacturing and for mitigating interference between impedance circuits during system operation.

Abstract: An overcurrent protection apparatus for a secondary battery includes a main relay, an auxiliary relay connected in parallel with the main relay, a current limiting resistor connected in series with the auxiliary relay and a controller for detecting an overcurrent and protect the battery module. The controller turns on the main relay and turns off the auxiliary relay in a normal state where the battery module is recharged by the generator. When the overcurrent is detected, the controller turns on the auxiliary relay and turn off the main relay so that a limited current flows through the current limiting resistor.

Abstract: Embodiments of the present invention relate to methods, systems, a machine-readable medium operable in a controller, and apparatus for controlling a multi-phase inverter that drives a multi-phase electric machine. When a sensor fault is detected, a phase current angle is computed based on the feedback stator currents, and used to estimate an angular velocity and an angular position of a rotor of the multi-phase electric machine. When the estimated angular velocity of the multi-phase electric machine is less than a transition angular velocity threshold, an open-circuit response can be applied at the multi-phase inverter by controlling all switches in the multi-phase inverter drive to be open. By contrast, when the estimated angular velocity is greater than the transition angular velocity threshold, a short-circuit response can be applied at the multi-phase inverter by controlling selected switches in the multi-phase inverter drive to connect all phases of the multi-phase inverter to a single bus (e.g.

Abstract: The invention relates to a protective circuit (10) in a screen wiper drive (1), consisting of a parallel circuit having two circuit elements (16, 17), wherein one circuit element (16) consists of a capacitor (18) and the other circuit element (17) consists of a series-connection of a diode (19) and a Zener diode (20), wherein the forward direction of the diode (19) and the Zener diode (20) is different and the Zener diode (20) inhibits in the direction of a plus pole.

Abstract: A steering control apparatus includes a direct current power source, a three-phase alternating current motor, and a motor driving circuit. An emergency switching element is provided on at least two phases of a three-phase power supply line connected to the three-phase alternating current motor within the motor driving circuit, and the emergency switching element is turned off when an abnormality occurs such that the motor driving circuit is disconnected from the three-phase alternating current motor. The emergency switching element is a MOSFET, and the MOSFETs are provided in pairs in each of the two phases of the three-phase power supply line. Further, parasitic diodes of the pairs of MOSFETs are disposed in opposite orientations to each other.