Abstract: A protection circuit is configured to change control modes in a drive control process of a drive circuit for a motor when overvoltage is applied to a power source line while the motor is driven. With overvoltage applied, the control process is changed to a control mode to perform forced commutation control. When a predetermined time period passes after the voltage of the power source line returns to a predetermined level, the control process is changed to a sensorless control mode using a position detection circuit. This configuration can provide a motor drive apparatus capable of performing an overvoltage protection operation appropriately even when the sensorless control mode is adopted.

Abstract: A specially designed rotation speed controller for fans, in addition to basic components like variable resistor, the controller has also been equipped with special components such as TRIAC, micro limit switch, and glass tube fuse, which allows said controller to precisely control the on/off status and the rotation speed of the fan, and the controller also provides power-off protection against power overload.

Abstract: A method for applying power to an electronically commutated motor (ECM) is described. The method includes connecting an AC voltage source to an input of a rectification circuit, connecting a DC voltage source to an output of the rectification circuit, and electrically connecting the DC voltage source and rectification circuit output to operational components of the ECM. The DC voltage source is capable of providing a voltage equal to or greater than a rectified voltage originating from the AC voltage source, and the DC voltage source is connected in parallel with the output of the rectification circuit.

Abstract: A load dump protection system is operable to provide protection for power transistors used to drive a blower motor of a vehicle. The load dump protection system includes circuitry for detecting an over-voltage transient. The circuitry adjusts a drive transistor into a saturation mode in response to a detection of an over-voltage transient. The circuitry lowers the power dissipated by the drive transistor when the drive transistor is in the saturation mode.

Abstract: An electric cutoff circuit for preventing overheating of a load. The current shutoff circuit includes an FET connected to a motor circuit. A relay fault detection circuit is connected to the motor circuit to detect potential at the motor circuit. A CPU sends a control signal to a relay. The CPU determines whether a fault has occurred in the relay based on the control signal sent to the relay and the detection of the relay fault detection circuit. When determining that a fault has occurred in the relay, the CPU opens the FET to configure an open circuit with the motor circuit.

Abstract: A system and method in accordance with the present technique for protecting motor drives from damage due to misconfiguration while coupled to a common DC bus, comprises sensing electrical operating parameters of the motor drives, automatically determining whether each of the drives is actually installed as a common bus leader or a common bus follower, and comparing the actual installation of the motor drives to a respective stored configuration of each of the motor drives as either a common bus leader or a common bus follower.

Abstract: A motor control system for detecting motor run condition comprises power switches for connection to an AC line for controlling application of AC power to the motor. An input receives a motor start command. A controller is connected to the input and controls operation of the switches responsive to a motor start command. The controller includes a counter and a timer and is operable to disable the power switches if number of starts during a select interval exceeds a first threshold and to disable the power switches if motor run time after a motor start command exceeds a second threshold.

Abstract: An adjustable lectern includes a base portion having a tubular upstanding base member and a tubular upstanding tower member that is mounted in a telescoping arrangement with respect to the base member. The base member and the tower member are each respectively formed as rigid tubes or channels by a single, unitary piece of material such as sheet metal. The lectern further includes a work platform that is positioned at an upper end of the tower portion. The work platform is both vertically and horizontally adjustable with respect to the base portion, so that both users who will be standing behind the lectern making a presentation and users who will be sitting behind the adjustable lectern in a wheelchair when making a presentation may be accommodated. Both the work platform and the base member include industry-standard rackmount structure for facilitating integration of electronic components.

Abstract: A method and associated apparatus for operating an electrical machine includes providing a brushless excitation system including at least one rectifier having at least one diode. The method also includes providing at least one voltage amplitude limiter assembly including at least one resistor and at least one transient voltage suppressor (TVS) electrically coupled with the at least one resistor to form at least one voltage suppression unit. The method further includes transmitting an electrical signal having a current and a voltage to each voltage suppression unit, the voltage having an amplitude. The method also includes electrically coupling the at least one voltage amplitude limiter assembly to the at least one diode. The method further includes transmitting the electrical signal through the rectifier and the voltage suppression unit such that voltage amplitude excursions of the electrical signal are facilitated to be reduced.

Abstract: A motor controller is provided with: an estimated temperature calculating means that calculates an estimated temperature of a motor; and a control unit that can perform a driving control of the motor only when the estimated temperature is not larger than a predetermined value. A mode switching means switches the control unit and the estimated temperature calculating means between in a normal operation mode in which they can drive the motor and in a sleep mode in which electric power consumption thereof is smaller than in the normal operation mode in accordance with a predetermined condition while the motor is stationary. An activating means activates the estimated temperature calculating means in the sleep mode for a predetermined active time every time a predetermined sleep time is elapsed.

Abstract: A controller is operable in one of a plurality of operational modes, which include an estimated temperature computation performing mode for performing computing of an estimated temperature of the motor and an estimated temperature computation non-performing mode for stopping the computing of the estimated temperature of the motor. An operational mode of the controller is changed from the estimated temperature computation performing mode to the estimated temperature computation non-performing mode according to a predetermined condition in a stopped state of the motor.

Abstract: A system and method for protecting a motor drive unit from an associated motor includes a motor drive unit protection system. The motor drive unit protection system includes at least one switch configured to be connected between a motor drive unit and a plurality of motor leads of the motor driven by the motor drive unit. The motor drive unit protection system also includes a controller configured to monitor the motor drive unit or the motor to determine a fault condition indicative of the motor potentially operating as a generator. Upon determining the fault condition, the controller is configured to cause the at least one switch to connect the plurality of motor leads together to protect the motor drive unit from the motor when the motor is operating as a generator.

Abstract: A heating value calculation part obtains a substantial heating value based on the difference between a heating value and a radiating value attributed to a motor supply current. The radiating value is obtained by a difference between a motor estimation temperature Td and an ambient temperature Tm. The heating value is cumulated in the heating value calculation part and the cumulated value is inputted to a cumulated buffer. A cumulated value TS which is obtained by adding an initial temperature T0 to the cumulated value Td is inputted to a target current value ratio map and a target current value upper limit map. One of the target current values is selected and the selected target current value is inputted to a current feedback control part. The current feedback control part controls a motor output part such that the motor supply current is converged to the target current value.

Abstract: The arrangement as overload protection for the mains voltage (U) comprises an electric motor (1), a compression unit having a compressor (2), a mains voltage-monitoring unit (3), a device for reducing the load on the motor (1) and a control arrangement (4). The control arrangement (4) is connected to the mains voltage-monitoring unit (3) and to the device for reducing the load on the motor (1) such that the motor (1) is disconnected from the load as soon as the mains voltage (U) falls below a predetermined, first threshold value. The load on the motor (1) comes from the pressure difference between the inlet (E) and the outlet (A) of the compressor (2), which is driven by the motor (1).

Abstract: A method and an arrangement for protecting a frequency converter in a system comprising a motor and a frequency converter supplying it via a bipolar or multipolar supply connection, the arrangement comprising first connecting means adapted to couple poles of the supply connection mutually substantially into short-circuit in response to a detection of a fault in the frequency converter.

Abstract: Control of an induction motor is carried out to limit damaging arcing stress and mechanical stresses placed on the control contactor assembly and the induction motor resulting from the simultaneous or synchronous breaking and making of contactors employed to connect the windings of the motor to a power supply. Asynchronously connecting the windings to the power supply via the asynchronous or non-simultaneous closing of the contactors of a modular contactor assembly reduces the potentially damaging transient current, the associated torque oscillations, and mechanical stresses. The present invention is particularly applicable to delta motors that are started with its windings in a star or wye configuration followed by the reconnection of the windings in a delta configuration when the motor is at normal running speed.

Abstract: The present invention is a brushless DC fan motor driving circuit, comprising a control unit, a Hall element, a temperature sensor with negative temperature coefficient, and a motor, as tied in with a plurality of resistors, capacitors, diodes and transistors. Accordingly, through sensing environment temperature by the temperature sensor and feeding back the temperature sensed to the motor to control the resolving speed, the ambient temperature of the system is maintained.

Abstract: A method and a circuit for protecting an electric motor and/or its trigger circuit against overload in the emergency-operation mode in a motor vehicle direct-current fan motor operated by means of pulse width modulation, in which the trigger circuit is designed as an emergency-operation controller, with a microcontroller preceding the motor end stage and with a comparator assembly for detecting overvoltages. Overload protection is assured at elevated battery voltage and at the same time when the emergency-operation controller is activated in response to malfunctions in the normal triggering of the electric motor. To that end, at least one overvoltage threshold (Us1, Us2) is defined; when it is exceeded, the power supplied to the motor is reduced or switched off.

Abstract: The present invention is a driving circuit for a two-phase DC brushless fan motor comprises a control unit, a Hall element, a motor and a motor protection circuit, an MOS element, a reverse protection circuit and a temperature control circuit. By sensing the running temperature of the motor by the temperature sensor and feeding it back to the motor and offering proper current as tied in with a current limiting resistor, thermal shutdown will not happen.

Abstract: A method for averting damage that may be caused by a transient energy surge during a load dump event, the method including detecting the load dump event and in response causing the consumption of transient excess energy due to the load dump event.

Abstract: Dynamic thresholds for power circuit switch operation are calculated in real-time using instantaneous operating parameter measurements. The dynamic thresholds are self-adapting and are used to provide shutdown criteria independent of switch control systems. A characteristics field containing information related to operation parameters is used to make overload evaluations in real-time. These dynamic overload evaluations allow complete protection against thermal overload for entire power circuits in addition to power components. Reserve load capacity can also be determined based on well known component characteristics, which permits the power circuit to be driven at optimal efficiency. The power circuit output profile can also be modified in response to dynamic overload evaluation, thus preventing overload shutdown or damage to components, while operating at optimal efficiency.

Abstract: A motor controller comprises a plurality of solid state switches each for connection between an AC line and a motor winding terminal for controlling application of AC power to the motor. A plurality of voltage sensors, each associated with one of the solid state switches, sense voltage for an associated motor winding. A control circuit controls operation of the solid state switches. The control circuit adjusts firing to one of the solid state switches if the sensed voltage for the associated winding varies from a threshold voltage by a select amount.

Abstract: A switch assembly including a switch (e.g., an electronic switch) and a controller connected to the switch to control the switch. The switch assembly can also include a power supply connectable to a power source and connected to the controller. The power supply is configured to receive power from the power source and controllably power the controller. The switch assembly can also include a generator and decision logic. The switch assembly can be used in an electric machine (e.g., a motor).

Abstract: A method and a circuit arrangement suitable for performing the method are provided for protecting an electric motor (10) and/or its trigger circuit (12) against overload in the emergency-operation mode. The method of the invention and the associated circuit arrangement serve in particular to protect a motor vehicle direct-current fan motor operated by means of pulse width modulation, in which the trigger circuit is designed as an emergency-operation controller, with a microcontroller (16) preceding the motor end stage (22) and with a comparator assembly (14) for detecting overvoltages. The provisions according to the invention assure overload protection at elevated battery voltage and at the same time when the emergency-operation controller is activated in response to malfunctions in the normal triggering (12) of the electric motor (10). To that end, at least one overvoltage threshold (Us1, Us2) is defined; when it is exceeded, the power supplied to the motor is reduced or switched off.

Abstract: The invention relates to a method of detecting the blocking of a three-phase stepper motor featuring three coils, characterised in that, with the stepper motor having its coils connected in star mode, with a common terminal (P), it implements a detection of a said blocking of the rotor of the motor, by supplying two of the said coils (A, B) with electricity in such a way that they are traversed by a current, and by measuring the voltage at an end terminal of the third coil (C). A comparison of the measured voltage is carried out with at least one given threshold.

Abstract: When an operation switch of a motor control circuit is switched on or when the operation switch and an automatic operation switch are simultaneously switched on, a switching device is switched on to energize a relay winding and a contact in the relay is switched to drive a motor. When an overcurrent is passed to a current detecting resistor and a temperature rise in the current detecting resistor is detected by the temperature dependent resistor and/or when a rise in a voltage across terminals of the current detecting resistor is detected by an overvoltage detecting circuit, the switching device is switched off via the bias circuit to thereby stop the driving of the motor.

Abstract: A protection system for an integrated circuit is disclosed. A detection system detects an overvoltage condition and provides an overvoltage condition signal to indicate a condition in which overvoltage protection may be desired. In response to the overvoltage condition signal, one or more variable resistance devices in the system, such as power devices of associated driver circuitry, are controlled to limit the voltage across such devices.

Abstract: In the invention, pairs of output transistors are provided. An actuator having an inductance is connected to nodes formed between the pairs of output transistors. A drive circuit for the actuator is arranged such that the actuator is driven by causing a drive current to flow into the inductance. The drive circuit has an overvoltage detection circuit for detecting whether or not a voltage appearing at the nodes of the output transistor pairs exceeds a supply voltage by a first predetermined level and whether or not the voltage becomes lower than a ground level by a second predetermined level. Output transistors connected to the nodes are activated by an output from the overvoltage detection circuit.

Abstract: In a voltage converter with a high-side short-circuit protection before an input voltage provided by a high-voltage power supply reaches a first threshold, a driver detects the input voltage and the output voltage of the converter to turn on the low-side transistor of the converter and turn off the high-voltage power supply when the input voltage ranges between the first threshold and a second threshold and the output voltage reaches a third threshold, to thereby avoid damages to the circuit connected to the output node of the converter. The driver comprises a front-end drive circuit to switch the high-side and low-side transistors and a low-voltage logic control circuit for the turning-on of the low-side transistor.

Abstract: A system and method for sensing current and/or voltage in a utility system including a plurality of power lines. In particular, a central controller is in communication with and enables a phase-to-phase relationship among current and voltage sensing units for a plurality of different power lines.

Abstract: Electronic circuitry provides protection for refrigeration machines by continuously monitoring supply voltage conditions and various other conditions. Information regarding abnormalities detected in the refrigeration machines or supply voltage is stored in a memory. The stored information may then be downloaded from the memory by a service technician. The electronic circuitry is universal and can therefore be used with various refrigeration machines. Further, the efficiency of a low temperature storage cabinet is enhanced by cycling the evaporator motor in comparison to a compressor percentage run time. Other factors are also considered in the running of the reach-in cabinet evaporator fan.

Abstract: A wiring board includes a signal transmission circuit designed as a distributed constant circuit. The signal transmission circuit includes a first transmission line connecting a first electric component and a second electric component, and a second transmission line connecting the second electric component to a terminator resistor of the distributed constant circuit. At least the first transmission line includes a plurality of signal lines arranged in parallel, which transmit a signal in parallel.

Abstract: Disclosed is a motor control circuit having a motor protective circuit of a simple configuration having a small number of cheap component parts. A motor control circuit has: a current detecting resistor connected to a motor in series; a series circuit of an operation switch, a switching device, and a relay winding connected between a power source and a reference potential point; a bias circuit including a temperature dependent resistor for supplying a bias voltage to the switching device; a switching state self-holding circuit including an automatic operation switch; and an overvoltage detecting circuit. When the operation switch is switched on or when the operation switch and the automatic operation switch are simultaneously switched on, the switching device is switched on to energize the relay winding and a contact in the relay is switched to drive the motor.

Abstract: A safety circuit system for a DC driven device for use with a fluid delivery system includes a first voltage potential DC power line, a second voltage potential DC power line, a controller and a safety circuit. The first voltage potential DC power line is coupled to provide a first voltage potential to the DC driven device, and the second voltage potential DC power line is coupled to provide a second voltage potential to the DC driven device such that the second voltage potential is different relative to the first potential. The controller controls at least the first voltage potential on the first voltage potential DC power line. The safety circuit has an enable state and a disable state, in which the default state is the disable state. The safety circuit is coupled to the controller, and the controller controls the safety circuit to place the safety circuit in the enable state independently of controlling the first voltage potential on the first voltage potential DC power line.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A motor protection circuit for an electric motor driven by a pulse width modulated amplifier. It has a capacitor and a first conduction path connected to a first terminal of the capacitor and connectable to a first conductor. It also has a second conduction path connected to the second capacitor terminal and connectable to a second conductor. There is a DC voltage difference between the first conductor and the second conductor. There is a third conduction path between the first terminal and the second terminal. The third conduction path having a resistance which is lower than the resistance of the first conduction path plus the resistance of the second conduction path. The third conduction path passes through a switch which has an input connection to be opened and closed thereby.

Abstract: A phase monitor for a short-circuited asynchronous three-phase motor comprises a first and a second sensing unit, both of which are connected to a supply voltage line to the motor in order to sense the voltage conditions on the line, and a control switch which is controlled by the two sensing units and connected in a control circuit for a supply voltage switch for the motor, connected in the supply voltage line. When the supply voltage line is connected to a supply voltage source, the first sensing unit causes an immediate switching-on operation of the control circuit if the voltage conditions on the supply voltage line sensed by the first sensing unit at that moment are acceptable.

Abstract: Emergency shut-down circuit is provided for a multiplexed circuit. The emergency shut-down circuit includes a plurality of contacts arrayed in parallel to each other and which are synchronously opened and closed. A plurality of electromagnetic contactors are operated according to a open or closed state of each of the plurality of emergency shut-down switches and are connected in series to a main circuit power circuit for a motor.

Abstract: Device for controlling the stopping of a shrouding product driven by an asynchronous motor having a phase-shifting capacitor (1) stopping the motor when the shrouding product encounters an abutment or an obstacle and utilizing for this purpose at least one operating parameter of the motor so as to detect the appearance of a resisting overtorque. This device furthermore comprises means (4) for detecting a dip in the supply voltage of the local network and means for disabling the control of stoppage when the supply voltage falls below a specified value and for as long as this voltage remains below this specified value.

Abstract: In a motor drive apparatus, a motor drive circuit includes an H bridge circuit composed of four field effect transistors or FETs, and resistors each having electrical resistance sufficiently higher than that of each of the FETs which would be presented when the FET has an ON-state trouble. These resistors are connected in parallel to the respective FETs. To perform a ON-state trouble detecting test on the individual FETs, an OFF signal is fed to all the FETs. If all the EFTS are free of the ON-state trouble, electric potential, representing a result of higher potential of a battery being divided by the resistors, appears at two input terminals of an electric motor connected to the motor drive circuit. If two of the FETs, having their drains connected to a higher-potential electrode of the battery, have the ON-state trouble, the higher potential of the battery appears at the two terminals of the electric motor.

Abstract: The present invention relates to an apparatus for detecting an anomalous condition of a cooling motor fan to be mounted on a vehicle. The anomalous condition detecting apparatus includes a detector for detecting a pair of positive and negative terminals of a motor of the motor fan and a decision circuit for deciding whether an anomalous condition exists or not based on a voltage detected between the terminals. For example, an external resistor is provided between the positive terminal of the motor and the power source, the negative terminal of the motor is earthed, a voltage between the terminals of the motor is detected as a potential of the positive terminal, and the decision circuit decides that an anomalous condition exists when the potential of the positive terminal is smaller than a predetermined value in a state that a drive signal of the motor fan is being output. Accordingly, it is possible to detect an anomalous condition of the motor fan at low cost.

Abstract: An electric vehicle control device controls an induction motor with a VVVF inverter. A first calculation means calculates a rotor-resistance correction value of the induction motor based on a torque current instruction value for vector control of the induction motor and an actual torque current value. A second calculation means calculates a corrected rotor-resistance value based on the rotor-resistance correction value and a reference rotor-resistance value. A third calculation means calculates an estimated rotor temperature of the induction motor based on the corrected rotor-resistance value, the reference rotor-resistance value, and a temperature coefficient determined by a material of a rotor. The thermal condition of the induction motor is thus monitored in real time without installing a temperature sensor on the induction motor.

Abstract: A control device for operating a wiper motor (10) which utilizes the typical path of the wiper motor current (Im) with cyclically recurring minima during the detection of an overload of the wiper motor (10) caused by blockage or tightness of the wiper. During this process, a storage element (C) that integrates the motor current (Im) is short-circuited at least twice within a wiping cycle (Tw) during normal operation so that the transfer of the admissible overload from a half of a wiping cycle (Tw/2) to the following half of the wiping cycle (Tw/2) is prevented and the limit value (G) for the shut-down of the wiper motor (10) is not reached through accumulation of the admissible overload.

Abstract: A protection apparatus used in a brushless motor is arranged by a brushless motor; a commutation signal detecting unit for detecting a position of a movable member of the brushless motor; a speed detecting unit for detecting a rotation speed of the movable member of the brushless motor, involving a rotation direction thereof, in response to the detection signal outputted from the commutation signal detecting unit; and a drive circuit for producing a commutation signal used to drive the movable member of the brushless motor in response to the detection signal outputted from the commutation signal detecting unit and for driving the brushless motor based upon the commutation signal.

Abstract: A method and control circuit for an electronic switch, and more particularly the high side switch in a bridge circuit. Control is established by continuous and/or the combination of continuous and pulsed signals. Fail safe undervoltage protection is provided for the high side switch based on the adequacy of both high side and low side control voltages.

Abstract: The present invention involves a control system for a motor having a main winding and an auxiliary winding disposed on a stator. A microprocessor determines the phase difference between the line voltage and the voltage between the main winding and the auxiliary winding to determine the rotational status of the rotor. In a moving rotor, a measurable phase difference exists. This phase difference can be measured by monitoring the zero crossings of the respective voltages. One method of measuring the phase difference is to check the logic state corresponding to the voltage between the main and auxiliary windings when a predetermined time period has elapsed after a zero crossing of the line voltage. Another method measures the time delay between the zero crossings of the two voltages. The control system of the present invention is particularly adapted for use with single phase AC motors having a main winding and an auxiliary winding disposed electrically out of phase on the stator.

Abstract: A hybrid vehicle utilizes a power unit to store and convert power between a turbine alternator, flywheel and traction motor. The power unit includes a water cooled heater exchanger for cooling power transistors used to switch stored and generated power between the peripheral machines. A pump control system for pumping fluid through the heat exchanger includes a fluid pump, a control circuit connected to the fluid pump for operating same, and a power source having a nominal operating range and transients. The control circuit includes a shut off circuit for sensing power level on the power source and turning off the fluid pump when the transients are above a first predetermined level and turning on the fluid pump when the transients return below a second predetermined level.

Abstract: Between one end of a motor coil and the ground, a drive transistor is connected. When the drive transistor is turned off, and in particular at the moment when a current flowing through the motor coil drops to zero, a back electromotive force is induced at said one end of the motor coil. The back electromotive force is clamped by a pnp-type transistor with its base supplied with a constant voltage and its emitter connected to said one end of the motor coil.

Abstract: A three-phase alternator protection component is associated with a rectifying bridge. Three Shockley diodes and an avalanche diode are interconnected through three electrodes, of a first polarity, of the Shockley diodes, and the electrode, of the opposite polarity, of the avalanche diode to a common terminal that is connected to the output terminal, having a first polarity, of the rectifier. Each second electrode of the Shockley diodes is connected to each output of the alternator, and the second terminal of the avalanche diode is connected to the second output terminal of the rectifier.

Abstract: An adjustable undervoltage trip fault interrupt circuit is used to prevent "nuisance" undervoltage fault trips caused by instantaneous sags in the AC power lines of less than a selectable time. The interrupt circuit includes a time delay circuit (IC4) responsive to a detected signal for generating a pulse signal having a selectable duration. A gating circuit (IC3) is responsive to the detected signal and the pulse signal for generating a fault trip signal only when the detected signal is longer than the selected duration of the pulse signal. In this manner, instantaneous line sags shorter than the selected duration of the pulse signal are eliminated from causing the "nuisance" interruption of a variable frequency drive controller.