Abstract: In a method of operating and controlling hysteresis motors energized by a three-phase power supply and individually monitored by an operating monitoring system, whereby the effective power output of the individual motors is determined and the three-phase voltage is changed if the effective power output deviates from a predetermined range, the hysteresis motors are first energized at an intermediate range voltage until they reach nominal speed and are then running at synchronous speed, the supply voltage is then increased to an upper range, where the remanent magnet pole strength is impressed on the armature and then reduced to a lower range for continuous operation of the motors, the power output of the individual motors is monitored and, if it drops below a threshold indicating a switch to asynchronous operation, the operating voltage is again increased to the intermediate range for renewed synchronization.

Abstract: A motor control system 16 for use within an electric vehicle 10 having an induction motor 12. Control system 16 utilizes a torque control module 18, a vector control module 20 and a space vector PWM module 22 to efficiently and accurately control the torque provided by motor 12.

Abstract: The method consists in determining the angular positions of the rotor, which are useful for switching the phase currents, by deducing them from the sampled reading of the phase voltages, and in measuring the current of each phase by deriving it from the detection of the voltage that is present across a shunt resistor inserted on the negative power supply conductor of the three-phase star bridge of the driving inverter that generates the set of three phase voltages supplied to the motor.

Abstract: An apparatus and method for controlling an induction motor having a variable frequency drive in a blower system so that the blower system provides a specific fluid flow. A start-up program causes the motor to ramp up to approximately a predetermined steady state speed. A required blower torque is calculated by operating on a table of blower constants, a selected flow rate and a motor speed which is read from a speed sensor in the motor/blower system. A developed motor torque is calculated by operating on a table of motor specific constants, a voltage-frequency index and the motor speed taken from the speed sensor. The calculated required blower torque is repeatedly compared with the calculated developed motor torque. The voltage-frequency index to the variable frequency drive is modified to force the developed motor torque to converge with the required blower torque in a steady state.

Abstract: An apparatus and method for controlling an induction motor having a variable frequency drive in a blower system so that the blower system provides a specific fluid flow. A start-up program causes the motor to ramp up to approximately a predetermined steady state speed. A required blower torque is calculated by operating on a table of blower constants, a selected flow rate and a motor speed. The motor speed is calculated by operating on a table of motor specific constants, a voltage-frequency index and a measured direct current bus current. A developed motor torque is calculated by operating on a table of motor specific constants, a voltage-frequency index and the calculated motor speed. The calculated required blower torque is repeatedly compared with the calculated developed motor torque. The voltage-frequency index to the variable frequency drive is modified to force the developed motor torque to converge with the required blower torque in a steady state.

Abstract: A polyphase induction motor is operated by an inverter drive system comprising a logic level controller. A number, preferably twelve or more, of independently driven phases causes harmonic fields, up to a number equal to the number of phases, to oscillate in synchrony with the fundamental oscillating field. A pulse-width modulation (“PWM”) carrier is used by the logic level controller to synthesize a desired drive alternating current, in which the pulsing distortion produced by the pulse width modulation produces a synchronous oscillating field in the driven polyphase induction motor.

Abstract: The present invention concerns a device (20) for controlling an electric motor (1) including a rotor (6) and at least three stator coils (2, 3, 4) connected between three connection terminals, means (5) for providing three control signals (Ua, Ub, Uc) to said connection terminals, and means (22) for dectecting said rotor angular postion. Said dectecting means include measuring means (24) designed to be connected to the motor, such that the means form with said coils at least two oscillating circuits supplying two respective signals (U1, U2) at two measurement frequencies respectively which are themselves periodic functions of said rotor angular position, and means (26) for calculating a single value corresponding to the two measurement frequencies, this value being the desired angular position.

Abstract: A method of controlling a variable speed draft inducer motor and fan in a gas furnace. The method comprises the steps of: detecting a first fault driving the motor to a maximum operating range; detecting a second fault forcing the motor to operate towards a minimum operating range; and generating a fault signal if both faults are detected substantially simultaneously.

Abstract: A power corresponding to an A/C voltage command id1* is applied in the d-axis direction of rotational coordinates of a stopped synchronous motor via a current control unit, a three-phase converting unit, and a power converter. Further, by using “an amplitude value of a current iq′ in the q-axis direction of the rotational coordinates generated in response to the A/C voltage command id1*” which is fed back and detected via a current detector and a dq converting unit, a field pole position estimation value &thgr;{circumflex over ( )} is converged. The field pole position is estimated by using the converged field pole position estimation value &thgr;{circumflex over ( )} as a true value of the field pole position &thgr; of the synchronous motor.

Abstract: A speed sensorless controller for an induction motor with rotor resistance estimation, using stator currents and voltages. The rotor resistance and speed estimation are obtained as a solution of a linear algebraic system with pseudo current and voltage signals and their observable derivatives as inputs. The proposed scheme provides accurate, real-time estimation of the speed and rotor time constants in all motor operational modes. It can also be used for real-time motor tuning if a speed signal is available.

Abstract: Provided to the motor controller is means which can alter a conversion ratio with which a current value detected by a current detector is converted into a unit (such as voltage) easily usable in motor current control. According to the maximum current value of the motor and the demagnetization limit current of the motor, an optimum conversion ratio is selected and switched over. By making it possible to select and preset a conversion ratio, a plurality of motors can be controlled by one motor controller. Therefore, restrictions imposed on the combination of the motor controller and the motor are lightened.

Abstract: A driving control circuit of a hood motor, including: a hood motor section rotatably driven for ventilating the inner portion of a system; a rectifier circuit section for supplying direct current power to the hood motor by rectifying alternating current power, a controlling section for generating a control signal for controlling the operation of the hood motor; and a driving circuit section for controlling the operation of the hood motor according to the control signal from the controlling section.

Abstract: A magnetic bearing apparatus for the journalling of a body (3), in particular of a rotor (3), comprises a stator (2) with a control winding (22) having at least three loops (22a, 22b, 22c) for the production of a magnetic control field by means of which the position of the body (3) relative to the stator (2) can be regulated, with each loop (22a, 22b, 22c) belonging to a different electrical phase, and a control device (4) which in a first operating mode supplies each loop (22a, 22b, 22c) with in each case a phase current (Ia, Ib, Ic) or in each case a phase voltage (Ua, Ub, Uc) as a control parameter. Means are provided in order to regulate the control parameter for each loop (22a, 22b, 22c) independently of the control parameter for the other loops (22a, 22b, 22c) as well as a monitoring unit (5) which can switch the bearing apparatus into a second operating mode in which a reduced number of phases, which is at least two, produces the magnetic control field.

Abstract: An apparatus for eliminating variable offset values of current detecting signals and its method having a current detector for detecting feedback current from a three-phase AC motor and for converting the feedback current into voltage detecting signals containing offset elements, differential amplifiers for differentially operating a feedback analog offset signal and the voltage detecting signals, output amplifiers for amplifying the differentially operated voltage detecting signals to fit within the input range for controlling, an analog/digital converter for converting the amplified signals into digital signals, a control part for adding up the digital signals to a digital offset value and for comparing the digital offset value with a predetermined offset command and for applying a proportional plus integral function to the compared result and for outputting a digital offset signal of a pulse-width modulation waveform, and a digital/analog converter for converting the digital offset signal into the analog of

Abstract: A controller for electric vehicles comprising a vector control inverter for controlling motors, which drive wheels of the electric vehicles, by dividing the primary current of the motors into an exciting current component and a torque current component, and controlling respective of the current components based on a respectively designated command, characterized in further comprising a dectector for detecting a wheel velocity (including a rotor frequency of the motor proportional to the wheel velocity), a detector for detecting slipping and skidding of the wheel based on a differential value (a changing rate with time) of the detected wheel velocity, a dectector for detecting re-adhesion of the wheel based on the differential value and a twice differential value of the detected wheel velocity, and an adjuster for adjusting the designated command for the torque current component in response to the detectors.

Abstract: A method of controlling a variable speed draft inducer motor and fan in a gas furnace. The method comprises the steps of: detecting a first fault driving the motor to a maximum operating range; detecting a second fault forcing the motor to operate towards a minimum operating range; and generating a fault signal if both faults are detected substantially simultaneously.

Abstract: An AC to DC to AC converter has an input to receive input AC, a rectifier to rectify the input AC to DC, and an inverter to invert the DC to output AC. A load sensor senses load on the AC to DC to AC converter. A fan directs a cooling fluid to the AC to DC to AC converter. A fan control has an input coupled to the AC to DC to AC converter so as to receive DC therefrom, an input coupled to the load sensor, and an output coupled to the fan. The fan control controls the fan at a variable speed in response to load on the AC to DC to AC converter so as to vary the cooling fluid delivered by the fan to the AC to DC to AC converter.

Abstract: A software logic controller using flowchart programming includes exception handling elements for handling exception conditions in a manufacturing process. Exception handling is programmed using a Begin Exception element to start monitoring the occurrence of a specific exception condition and an End Exception element to stop the monitoring process. Monitoring is conducted once during every scan cycle of the computer as long as the Begin Exception element is still active.

Abstract: A distributed diagnostic system in which a plurality of local monitoring devices collect local information concerning various machines and process that information, according to redefined diagnostic parameters, for diagnostic purposes. The local information collected by the plurality of local monitoring devices is provided to a global processor that globally processes the collected information to provide updated diagnostic parameters to the local monitoring devices.

Abstract: An apparatus for controlling an actuator in response to a target speed voltage signal, the actuator having a moveable member and having a coil that influences movement of the member. A first summing node is provided having a control output voltage, for summing or subtracting voltages applied thereto, as the case may be and receiving the target speed voltage signal at a first, summing input thereto. A proportional compensation unit is provided, receiving the control output voltage and providing as an output a proportionally compensated output signal. An integral compensation unit is provided, receiving the control output voltage and providing as an output an integrally compensated output signal. An inverse compensation unit is provided, receiving the target speed voltage signal as an input and providing an inversely compensated output signal having a voltage corresponding to the voltage of the target speed voltage signal multiplied by the inverse of a predetermined amplification factor.

Abstract: An electrical control system for an induction motor for achieving optimum efficiency at both full and partial loads at markedly reduced electrical components costs while maximizing reliability over the range of load, and for achieving a two step motor power output in a greatly simplified manner, the circuit having an electrical induction motor adapted for connection to line electrical power at maximum motor operating frequency, and to a second source of electrical power at approximately one half of the maximum operating frequency, wherein an electrical switch is provided for selectively connecting each power source to the motor, wherein the second source is a reduced frequency wave form generator for producing a reduced frequency wave form.

Abstract: In an injection molding machine whose movable part is driven by an AC servo motor, d-phase current in a direction of magnetic flux produced by a field system and q-phase current orthogonal to the d-phase current are obtained through d-q conversion on the basis of drive current of the AC servo motor and a phase of a rotor. Control of current is made in DC mode on condition that the d-phase current is set to zero, and the q-phase current is adapted for a current command. Control of current in the DC mode as described above is designed to advance the phase of the q-phase current command, which is an effective component of a current command at the time of the occurrence of magnetic saturation, thereby preventing, the influence of magnetic saturation to lessen the fall of torque.

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: A drive for controlling the speed of an AC induction motor from an inverter. The inverter applies a voltage to the stator winding of the motor in accordance with the magnitude of a first input signal. The inverter causes the voltage to be applied at a frequency determined by the magnitude of a second input signal to the inverter. The drive includes motor speed sensor and a motor speed reference signal source coupled to a speed regulating amplifier. A slip detector determines the slip of the motor from the speed of the rotor and the energization frequency of the stator winding. A slip regulating amplifier receives the output signal from the speed regulating amplifier and the slip signal and provides an output to a summing amplifier. The summing amplifier also receives a motor speed signal and provides an output. The output comprises the second input signal to the inverter. The output may be supplied through an absolute value circuit as the first input signal to the inverter.

Abstract: In an inverter controlling method for an induction motor, the slip of the motor is detected and an optimum slip which is dependent on the motor constant and the frequency supplied to the motor providing the highest efficiency is calculated, and a voltage manipulated variable is determined from a comparison of the optimum slip and the slip of the motor, and then the voltage manipulated variable is used to form an output voltage instruction or a magnetic flux instruction so that running of the induction motor is controlled with the slip with which the highest efficiency is provided with respect to load variation and frequency variation.

Abstract: A motor control processor controls motor spin-up in a disk drive by detecting environmental temperature at the spindle motor of the disk drive, controlling commutation phase advance to generate substantially maximum torque if the detected environmental temperature indicates that maximum torque is needed, and adjusts the commutation phase advance for optimal efficiency after the maximum torque is no longer needed. Following motor start and reaching operational speed, the motor is operated in a steady-state maximum operating efficiency mode unless sensed environmental temperature indicates that maximum torque, rather than maximum efficiency, is needed. The system determines that the need for maximum torque has passed either when a predetermined time interval after motor start expires or by repeatedly polling motor temperature information.

Abstract: An electric motor (12) has multiple phase inputs (22, 24, 26). Each phase input can be coupled to a supply voltage (VM) by a high side driver transistor (40, 46, 52), or can be coupled to ground by a low side driver transistor (42, 48 54). A control circuit (30) turns each of the high and low side driver transistors on and off according to a predetermined sequence. As each of the low side driver transistors is turned off, another low side driver transistor is turned on in a manner so that a current through the low side driver transistor which is being turned off decreases at a linear rate, and so that a current through the low side driver transistor which is being turned on simultaneously increases at the same linear rate.

Abstract: A display system using red, green, blue, and white light. The system derives data for the white portion of a color wheel or a white device from the red, green and blue data. The white portion of the color wheel is controlled as if it were another primary color on the wheel. Errors are prevented by a correction applied if the unfiltered light from the source has a different color temperature than the white light produced using the red, green and blue segments of the color wheel, or the devices for those colors. Analysis is performed on the data to determine if white light is necessary to be added to each frame of data.

Abstract: An apparatus for controlling an actuator having a moveable member and having a coil that influences movement of the member, by provision of a drive current to the coil in response to a target speed voltage signal. The invention includes an up/down counter, counting at a predetermined count rate and providing a count output. A control unit is provided for controlling the direction of count of the up/down counter depending on whether the voltage across the coil, sensed periodically a first predetermined interval after the drive current to the coil is interrupted, is greater than, or less than, a reference voltage having a predetermined relationship to the target speed voltage. A digital-to-analog converter is provided, responsive to the count output to provide a compensated voltage signal having a voltage corresponding to the count output.

Abstract: A system for electrical braking and the storage for reuse of the braking energy is disclosed using alternating current (AC) rather than direct current (DC) generators coupled to the wheels of the vehicle to be braked. Upon braking, the AC generators feed the primary coil of a transformer whose secondary coil can be tapped at one of a number of different turns. Means are provided for changing the tap points so as to increase the number of turns in the secondary as the speed of the braked wheel declines. The output from the secondary is fed to a rectifier and thereafter the direct current is fed to a battery energy storage device. By increasing the turns of the secondary as the wheel speed drops, more energy can be fed and stored in the battery and the range of effective braking by the alternating current generator can be extended to lower speeds.

Abstract: A feedback circuit prevents clipping of the inverter drive signals for a polyphase induction motor. The circuit senses the electromotive force (e.m.f.) of the motor and regulates the slip frequency as a function of the difference between the sensed motor e.m.f. and the DC power supply voltage. When the motor e.m.f. approaches the supply voltage, a voltage controlled oscillator adjusts the slip frequency to reduce the motor e.m.f. and thereby ensure that the motor drive waveforms are not distorted.

Abstract: In a motor with permanent magnets and a motor system, the value .alpha. produced by dividing, by the induced voltage constant ke, the product of the inductance Lm of the motor itself or the inductance Ls of the motor system in the d-q coordinate system is selected to meet a predetermined condition. The range of rotational speeds in which the motor can be operated while maintaining a predetermined output under field weakening control can be widened. If a condition is established to determine a ratio by which the rated rotational speed under normal operating conditions is multiplied into a rotational speed under field weakening control, then conditions for a motor or a motor system that can be used can be determined.

Abstract: A computer-based system and method for ascertaining anomalies in an electric motor, includes computing and processing a set of Fast Fourier Transforms (FFT's) of the supply current waveforms for a motor known to be in a normal condition to create a feature set of input vectors. The input vector assignments for all possible cluster groupings 1 through n are derived using Ward's method. The method includes computing the Approximate Weight of Evidence (AWE) for each cluster grouping then selecting that count associated with a maximum AWE and designating this count as s. For each cluster in each grouping 1 through s, the method finds the member vector farthest from the cluster's centroid and defines this as the cluster's radius.

Abstract: A power corresponding to an A/C voltage command id1* is applied in the d-axis direction of rotational coordinates of a stopped synchronous motor via a current control unit, a three-phase converting unit, and a power converter. Further, by using "an amplitude value of a current iq' in the q-axis direction of the rotational coordinates generated in response to the A/C voltage command id1*" which is fed back and detected via a current detector and a dq converting unit, a field pole position estimation value .theta. is converged. The field pole position is estimated by using the converged field pole position estimation value .theta. as a true value of the field pole position .theta. of the synchronous motor.

Abstract: In a motor control system and method controlled by a d-axis current command value i.sub.ds and a q-axis current command value i.sub.qs, a d-axis voltage command value V.sub.d * and a q-axis voltage command value v.sub.q * are computed on the basis of d-axis current deviation .DELTA.i.sub.d of d-axis current value i.sub.d from the d-axis current command value i.sub.ds and q-axis current deviation .DELTA.i.sub.q of q-axis current value i.sub.q from the q-axis current command value i.sub.qs and on the basis of q-axis inductance value L.sub.q and d-axis inductance value L.sub.d wherein the inductance values L.sub.q and L.sub.d are tuned or adjusted so that the d-axis current deviation .DELTA.i.sub.d and q-axis current deviation .DELTA.i.sub.q approach zero.

Abstract: An excitation circuit is disclosed for balancing the phase voltages in a two phase motor. The excitation circuit includes a first and second switch and a port for receiving a signal to drive the switches. The excitation circuit also includes additional electrical circuitry which can be designed to adjust the speed and timing of the first and second switches and balance the phase voltages in the two phase motor.

Abstract: The present application discloses a system and associated method for lowering heat dissipation created by running a motor. The system comprises a voltage regulator, the motor, and a controller. The voltage regulator is connected to a supply voltage and has an output voltage with an associated output current dependent upon impedance of the system. The motor, which may be AC or DC, is driven by the output voltage and an output current at a current running speed. The controller controls the supply of the output voltage and associated output current to the motor toward varying the current running speed of the motor while minimizing the power dissipated throughout the system.

Abstract: A normalization circuit for a phase energization controller receives a rotor position value from a position encoder, and the normalization circuit obtains a normalized rotor position for each phase of a switched reluctance machine. Accordingly, the normalization circuit simplifies the detection of commutation positions for all the machine phases by reducing the commutation position determination to that of a single phase. Also, an initialization circuit for the phase energization controller energizes one or more phases of the switched reluctance motor to set the rotor of the switched reluctance motor to a preferred position to determine an offset value.

Abstract: A variable-speed control apparatus computes the leakage inductance of an AC motor, correctly compensates the leakage inductance, and controls the variable speed of the AC motor. The variable-speed control apparatus has an AC signal generation circuit for generating an AC signal, and obtains a leakage inductance calculation value of the AC motor based on the AC signal and the measured actual current value. The differential value of the summation of a current command value and the AC signal is multiplied by the leakage inductance calculation value to generate a signal for use in compensating the voltage drop caused by the leakage inductance, and added to a voltage command value to cancel the deviation between the actual current value and the M-axis current command value and to obtain the second voltage command value. The second voltage command value is converted into a 3-phase voltage command value and used in controlling the AC motor, and the voltage drop caused by the leakage inductance can be compensated.

Abstract: A sensorless brushless motor driving circuit for a motor having three phases includes a position detecting circuit for detecting the position of the rotor from the terminal voltages of the motor, a commutation switching circuit for generating commutation switching signals based on a position signal from the position detecting circuit, a motor driving transistor circuit for supplying a motor driving currents to the motor in response to driving signals, a buffer circuit for supplying the driving signals according to the commutation switching signals, and a neutral feedback amplifier for detecting a neutral potential of terminal voltages of the motor, comparing the neutral potential with a reference voltage, outputting a first output to the buffer circuit when the neutral potential of the terminal voltages of the motor is higher than the reference voltage and outputting a second output to the buffer circuit when the neutral potential of the terminal voltages of the motor is lower than the reference voltage.

Abstract: An electric vehicle propulsion system having a motor with first and second electrically isolated windings and a system control unit for controlling the motor, wherein the system control unit includes a first power bridge for driving the first windings and a second power bridge for driving the second windings.

Abstract: A system for controlling circulating currents in a motor. A power supply link having upper and lower rails supplied by a power supply provides power to the motor windings. The power supply link also has power switches responsive to a motor control signal for selectively connecting the rails to the windings in alternating on and off intervals. The system includes a first resistive shunt in the upper rail of the power supply link between the power supply and the power switches and a second resistive shunt in the lower rail of the power supply link between the power supply and the power switches. The power supply link routes current circulating in the power supply link and windings through either the first or second resistive shunt for continuously sensing current in the rails. The system also includes a current regulation circuit which generates an overcurrent signal as a function of the current sensed in either the first or second resistive shunt exceeding a maximum current level.

Abstract: A commutation control strategy for eliminating torque ripple and noise from a brushless motor which has a plurality of motor phases connected in a bridge, each phase having a top switching device provided between a phase winding and a positive voltage supply and a bottom switching device provided between the phase winding and a less positive voltage supply in which following commutations of the motor, when the current flowing in a first phase is decaying towards zero and the current in a second phase is rising from zero, the switching devices are operative between a state in which the current flowing in the first phase is caused to decay at a first rate, and another state in which the current flowing in the first phase is caused to decay at a second rate which is lower than the first rate so that the rate of decay of the current in the first phase substantially matches the rate of rise of the current in the second phase.

Abstract: An electric current compensation circuit for use with a multiple-phase burshless motor to reduce ripples in the output torque is disclosed. It contains a plurality of electric current compensation loops each for a respective phase winding and each of the electric compensation loops contains: (a) a first input for receiving a line current from the driver; (b) a second input for receiving the compensation current from the motor sensor; (c) a forward rectifying circuit for forwardly rectifying the line current and the compensation current; (d) a reverse rectifying circuit for reversely rectifying the line current and the compensation current; and (e) a summation circuit for summing the forwardly rectified compensation current and the reversely rectified compensation current and outputting a synthetic current to a phase winding of the motor.

Abstract: The invention concerns an improved system for windshield wipers in vehicles. An induction motor is used, in which speed is accurately controlled by controlling frequency of power supplied to the motor. The induction motor may be of the consequent-pole type, which ordinarily does not produce sufficient torque. Addition of (a) auxiliary tooth slotting and (b) skew has raised the torque produced to acceptable levels.The invention includes a control system, which senses excess load on the motor, which occurs as the windshield dries, and reduces motor speed, subject to a minimum, in response.

Abstract: A disk drive including firmware for overcoming stiction and breaking free the heads of a disk drive which may adhere to the disk surface when the disk is at rest. Upon start-up of the disk drive, if stiction at the head/disk interface occurs, the voltage to the spindle motor and/or actuator motor may be rapidly fluctuated so as to cause a pulsing of the spindle motor and/or actuator motor. Pulsing both the spindle motor and actuator motor creates forces in a plurality of radial directions to allow the head(s) to break free from the disk(s) in the direction of least resistance. Moreover, as the resonant frequency of the spindle motor varies depending on the number of heads that are stuck, the firmware pulses over a range of frequencies including the various resonant frequencies of the spindle motor corresponding to various numbers of heads stuck.

Abstract: An efficiency control system for an induction motor system includes an induction motor, a power transducer connected to the induction motor, and a detector adapted for separate real-time detection of a voltage signal, a current signal, and a frequency signal of electric power supplied from the power transducer to the induction motor so that an output of the induction motor during operation may be controlled by these signals in response to a load torque. The efficiency control system includes an actual slip signal processor for calculating an actual slip of the induction motor during operation on the basis of a motor constant and the voltage signal, current signal, and frequency signal of the electric power supplied from the power transducer to the induction motor. The efficiency control system further includes an optimum slip signal processor for calculating an optimum slip desired to obtain the maximum efficiency of the induction motor.

Abstract: In a motor drive circuit, the collector-emitter paths of two npn-type transistors are connected in series between a power line and ground, and the junction between the two transistors is connected to a motor coil. A control circuit feeds a control current to the base of the transistor connected to the power line so that this transistor supplies a drive current to the motor coil. A current mirror circuit is provided which is constituted of two pnp-type transistors whose emitters are connected to the power line, and the base and collector of the input-side transistor is connected to the control circuit through a diode. The base of another pnp-type transistor is connected to the cathode of the diode, and the emitter of this transistor is connected to the collector of the output-side transistor of the current mirror circuit and to the base of the transistor connected to the power line.

Abstract: The present invention relates to a method of supplying optimal power for an alternating current electric motor driven by a direct/alternating and alternating/direct/alternating static frequency converter, as well as a device implementing this method.This method of supplying optimal power for an inductive-type load coupled to an application, this load being driven by a static converter controlled by an electronic module, this power supply method constituting the electronic load control device which, at any instant, delivers to the load, by means of setting parameters applied to the controls of the converter, a voltage, by noting the direction of variation around an extreme, corresponding to a minimum power absorbed by the load, from one or more monitoring parameters (MP) which are weighted and/or combined together.The method of supplying optimal power, as well as the device implementing it according to the present invention, apply to all types of load of an inductive nature.

Abstract: A variable frequency motor drive incorporating a circuit interrupter includes a rectifying circuit for converting incoming AC power to DC power and an inverting circuit for converting the DC power to controlled AC power in response to control signals. A control circuit implements a preset control routine to control operation of the inverting circuit to drive a motor in accordance with desired operating parameters. A circuit interrupter is coupled between the source of AC power and the rectifying circuit and includes an actuator for interrupting power to the drive in response to interrupt command signals from the motor control circuit. The motor drive includes a switching circuit and a capacitive circuit for powering the circuit interrupter. The drive control circuitry monitors operation of the drive and the motor and when conditions require removal of power to the drive, the control circuitry commands the switching circuit to close, energizing the circuit interrupter and thereby removing power to the drive.