Abstract: A system for controlling a brushless dc motor includes a motor driver circuit that outputs a drive current to the motor and a power supply that provides power to the motor driver circuit. Feedback circuits provide signals indicative of: a speed of rotation of the motor and at least one of: a level of the supply voltage provided by the power supply, and the output current from the motor driver circuit. A processor analyzes the feedback signals and determines if a required change in drive current to the motor will result in a saturation or near saturation condition. If such a saturation or near saturation condition is anticipated, the processor initially determines if a change in commutation angle will avoid the saturation or near saturation condition and if yes, outputs a control signal to alter the commutation angle.

Abstract: A method for controlling the starting, stopping and operation of an AC motor is provided. Each winding of the AC motor is interconnected to an AC source by a thyristor switch and a bypass contactor for providing voltage and current to the AC motor. The method includes a steps of sequently firing a pair of tyristor switches to bring the AC motor to full operating speed. Once at operating speed, the bypass contactors are closed. Upon detection of a voltage drop across a thyristor switch, the thyristor switch is fired immediately to transfer motor current from the bypass contactor to the thyristor switch in order to maintain voltage and current to the AC motor.

Abstract: A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is squared. The squared outputs associated with each winding are combined, with the square root being taken of such combination, to produce a DC output proportional only to the rate of rotation of the motor's shaft.

Abstract: A DC motor driven power steering system for a motor vehicle includes a motor current detection circuit for detecting a motor current flowing through the DC motor, a power supply voltage detection circuit for detecting a power supply voltage applied to the bridge commutation circuit, a motor voltage estimating unit for estimating a voltage applied across the DC motor on the basis of the power supply voltage applied to the bridge commutation circuit and the pulse-width modulated control signals used for controlling the bridge commutation circuit, and a motor rotation detecting means for detecting the rotation state of the DC motor on the basis of the motor current and the estimated motor voltage applied to the DC motor. High reliability can be ensured for detection of the rotation state of the DC motor.

Abstract: A device for controlling a synchronous electric motor with a permanent magnet rotor. The device comprises a stator including a winding disposed around a stack of laminations and with which is associated a permanent magnet rotor. Controlled conductor devices are connected to the stator winding and to an AC source. One or more position sensors determine the application to the control inputs of the said controlled conductor devices of electrical control signals having to states which vary as a function of the angular position of the rotor. The arrangement is such that the current is caused to flow in the stator winding in a direction which depends only on the polarity of the voltage of the source and the instantaneous position of the rotor.

Abstract: A method for controlling an asynchronous machine which is operated below a cutoff frequency in the base speed region with variable magnetization current and above a cutoff frequency in a field control speed region is provided. The maximum possible fundamental oscillation of a stator voltage is determined from a existing intermediate circuit voltage or battery voltage and a stator current is defined as a setpoint and impressed onto the asynchronous machine. A calculation is made of a rotor frequency needed, with that definition of the stator voltage to impress the current setpoint. A rotor frequency which corresponds to the current setpoint is compared via a control characteristic curve to the calculated rotor frequency and that rotor frequency value which is the greater of the two is used to determine the current setpoint. The method is advantageously performed with a microprocessor, with which the calculation algorithm may be executed rapidly, effectively, and contemporaneously.

Abstract: The invention includes: a random number generating unit which outputs a random number in driving of an AC motor by a voltage source inverter, a maximum/minimum triangular wave frequency setting unit which calculates a maximum triangular wave frequency and minimum triangular wave frequency using the inverter frequency, a triangular wave frequency calculating unit which calculates a triangular wave frequency from the random number, the maximum/minimum triangular wave frequency, and a triangular wave peak pulse, a triangular wave generating unit which calculates a triangular wave in accordance with this triangular wave frequency and outputs a triangular wave peak pulse, a voltage reference generating unit which inputs inverter current references and the motor revolution frequency, and which calculates the inverter frequency and voltage references of each phase of the inverter, and a PWM pulse generating unit which inputs the voltage references and triangular wave of each phase which are calculated and outputs a

Abstract: In vector control apparatus and method for a three-phase multiplex winding motor, a plurality of inverters are installed, each inverter operatively driving a corresponding one of multiplex windings of the motor and a plurality of inverter controllers are installed whose number corresponds to that of the inverters. Each controller includes: a decoupling voltage calculator for calculating d-axis and q-axis voltage setting values V.sub.1 d* and V.sub.1 q* on the basis of an excitation instruction value Io*, a torque instruction value I.sub.T *, d-axis-and-q-axis current instruction values i.sub.1 d* and i.sub.1 q* which are quotients of the excitation instruction value Io* and the torque instruction value I.sub.T * divided respectively by the multiplex number N of the windings of the motor, and a power supply frequency .omega. which is an addition of a slip frequency .omega.s to a rotor revolution frequency .omega.

Abstract: In a process for controlling a rotating machine having n phases powered by a voltage inverter defining m.sup.n states of the stator phase voltage vector the electromagnetic torque .GAMMA. and the stator flux .vertline..phi..sub.s .vertline. of the machine are servocontrolled. A calculator calculates a succession of n states of the phase voltage vector to move the torque .GAMMA. and the flux .vertline..phi..sub.s .vertline. towards the set points .GAMMA..sub.ref, .vertline..phi..sub.s .vertline..sub.ref. On each sampling, the calculator calculates the remaining application time of the current state and the updated application times of the future states of the phase vector. Asynchronously with the sampling times and the calculation times, the calculator sends SPmLL switch control signals to switch from the current state to the next state.

Abstract: The present invention propose a driving apparatus for an image processing system. A DC motor with a feedback controlling system is utilized as the driving apparatus. With the design of the present invention, the accuracy of the position control can be increased and the prior art problem of missing steps and unequalled steps can be eliminated. The driving apparatus of the present invention includes a DC motor, a position detecting device, an error counter, a controlling circuit, and a driving circuit. The position detecting device is employed for detecting positions of the DC motor in order to generate feedback signals. The error counter is responsive to input signals and the feedback signals for generating error signals. The controlling circuit is responsive to the error signals for controlling the DC motor. The driving circuit is responsive to the controlling circuit for driving the DC motor.

Abstract: An electric motor control circuit that prevents lowering of a motor's rotation speed when a load is applied in the case where a rotation speed is adjusted within a range that doesn't exceed a predetermined upper limit of rotation speed. When a base current of a transistor Q1 starts to flow in response to operation of a trigger switch 3, transistor Q1 turns on and a setting signal output from a switch S2 which sets the upper limit rotation of a motor M is bypassed via a bypass way 22 by transistor Q1. Thus, a signal level of the setting signal inputted to an operational amplifier 7 is changed, and output timing of a pulse signal output from a phase control circuit 5 to a gate pulse output circuit 9 is changed and a conducting angle of a triac Q2 is controlled. Because the trigger switch 3 does not adjust an output level of operational amplifier 7, the rotation speed of motor M does not decrease when the load is applied.

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: A method for the field-oriented control of an induction motor (2) by means of a frequency converter (1) is disclosed, in which method a transformation angle (.delta.) is determined by estimation and is corrected in dependence on a rotational speed (.omega..sub.mR) of a rotor flux vector (i.sub.mR) or of the induction motor (2) and/or in dependence on a delay time (T.sub.del). In this connection it is desirable to improve the control behavior. To that end, the transformation angle (.delta.) is corrected a second time to compensate for a phase shift in the frequency converter (1).

Abstract: A method for controlling the operation of a brushless DC fan for cooling heat generating components of a system is provided. The method includes providing a system temperature signal indicative of a system temperature and providing an intelligent shutdown enable signal. The system temperature signal is compared with a shutdown temperature signal if the intelligent shutdown enable signal has a first value. The shutdown temperature signal is representative of a shutdown temperature value. The fan is operated at a generally temperature proportional speed after comparing the system temperature signal with the shutdown temperature signal if the system temperature as indicated by the system temperature signal is greater than the shutdown temperature value as indicated by the shutdown temperature signal.

Abstract: Method for commutation of a brushless motor being supplied with electrical energy from a DC intermediary circuit via a multi-phase inverter, by which a first current and a second current value are determined and the length of a commutation interval is set in dependence of these current values. With motors being exposed to heavily varying load torques during one rotation, e.g. motors driving a compressor, a stable operation must be reached. For this purpose a correction value is added to the pre-set commutation interval determined by the speed of the motor, said correction value being the result of the difference of the actual value of the intermediary circuit current and a filtered and delayed value of the intermediary circuit current, multiplied by a weighting factor.

Abstract: Method of controlling torque of a multi-phase induction motor (10) includes estimating rotor speed as a rational function of filtered stator current i.sub.s0 and voltage u.sub.0 and first and second order derivatives of the filtered stator current and first order derivative of the filtered stator voltage, estimating rotor flux from said estimated rotor speed, estimating rotor flux angle from said estimated rotor flux, and using the estimated rotor flux angle to control motor torque.

Abstract: The present invention addresses a problem as to how to provide a motor control apparatus which has a magnetic pole position inferring means capable of inferring the position of a magnetic pole of a synchronous motor by adopting a simple method in a short period of time with a high degree of accuracy. In order to solve this problem, a signal id1* for inference use is applied and a peak value iqh of a response current iq' is detected by an iq' peak detecting unit. The peak value iqh is then supplied to a magnetic pole position inferring unit for inferring the position of the magnetic pole of the synchronous motor by carrying out multiplication processing.

Abstract: A motor control device controls an electric 3-phase brushless d.c. motor (10) having a magnetic rotor (15) and three windings (11, 12, 13). The motor control device includes a detection unit (20) adapted to generate a commutation signal (21) on the basis of the back-emf voltage produced in the windings (11, 12 and 13). The motor control device further includes an output stage (30) having a first terminal (31) and a second terminal (32) for the connection of a power-supply source, outputs (33, 34, 35) for the connection of the windings (11, 12 and 13) and a number of semiconductor elements (36) for selectively coupling the terminals (31, 32) to the outputs (33, 34, 35) in dependence upon the commutation signal (21). The motor control device further includes a phase detector (40) adapted to generate a phase-error signal (43) which is representative of the phase difference between a sensor signal and a reference signal.

Abstract: A controller for variable speed three-phase AC squirrel-cage induction motors in accordance with a volts-per-hertz control method is disclosed. Direct current ("DC") link current is employed to compensate for rotor slip. In particular, rotor slip is estimated and added to a speed reference command to compensate for changing loads. A direction input and speed reference command provide complete control over the induction motor.

Abstract: A d-phase current in the direction of a magnetic flux generated by a field system and a q-phase current in a direction perpendicular thereto are obtained from a driving current and a rotor phase of an AC servomotor by d-q conversion. DC-mode current control is carried out with this d-phase current adjusted to zero and using the q-phase current as a current command. In this DC-mode current control, the influence of magnetic saturation is restrained to lessen torque reduction by advancing the phase of the q-phase current command, which is effective component of the current command, in case of magnetic saturation.

Abstract: When an induction motor is variable-speed-controlled via an electric power converting circuit, the magnetic flux of the induction motor is modulated by adding an alternating current signal to, for example, a magnetizing current command. For example, the component depending on the slip frequency of the induction motor is extracted by an extracting means from at least one of the amounts of changes of the voltage, the electric current, and the magnetic flux, which are caused by the modulation of the magnetic flux. The amount of the voltage or the electric current supplied to the motor, etc. is controlled based on the extracted component via an adjusting unit and a control means, thereby implementing superior control of the induction motor.

Abstract: The circuit for speed regulation of a three-phase motor incorporates a drive connected directly to a three-phase mains (R,S,T) which allows through mains voltage directly to the motor windings controlled by a pulse-width modulated signal produced by a control circuit controlled by the motor speed and fed to the drive stage via circuits for galvanic (d.c.) separation of the control circuit and the drive stage. The galvanic separation is produced with solar cell components.

Abstract: The present invention relates to a sensor for verifying that a motor has stopped rotating including rotation due to inertia.Respective signal input lines are connected to three power supply lines of a three phase AC motor. A high frequency signal current is supplied to one of the power supply lines, and the difference in the current flowing in the other two power supply lines is sampled from the signal input lines connected to the two power supply lines, and made an output from a sensor section. The sensor output is subjected to a threshold value operation in a signal processing circuit, and the resultant threshold operation output is output from an on-delay circuit as a motor rotation presence judgment output.

Abstract: The invention relates to a single-phase induction motor comprising a main winding, an auxiliary winding which is arranged so that an electrical angle of the auxiliary winding is different from that of the main winding, a plurality of driving capacitors which are connected to the auxiliary winding, a relay for controlling on/off of the driving capacitor in response to the driving load, and a rotor having apertures on the gap side of the slots. The invention further relates to a rotor assembling apparatus comprising a bush to which a rotor core assembly is inserted for die-casting, wherein a clearance between said bush and said rotor core assembly is narrower to the extent that said rotor core assembly can be taken out after die casting; and a core band having a clearance between the core band and the bush in the circumferential direction of said bush, said core band is engaged into said bush so that movement in the axis direction is restricted.

Abstract: An induction motor controlling device realizes precise and discretional revolutional speed vector control without requiring a speed detector using an algorithm which is suitable for a system including a microcomputer.A three-phase-to-two-phase converter detects a torque current inside a motor as a DC quantity based on instantaneous values of motor currents. A slip frequency is estimated using the torque current, and the slip estimation is used to obtain a motor's revolutional speed. An error in revolutional speed estimation is compensated by a compensation value which is obtained by amplifying an excitation current common phase voltage command.

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 induction synchronous motor comprises: a unitary rotor having a first and a second rotor core; a first and a second stator mounted surroundingly facing the first and the second rotor core; a voltage phase shifting means for producing a first and a second phase differences; a static magnetic field around each of the first and second rotor cores; and a rotor magnetizing means having diodes for rectifying alternating voltages and for having the resultant direct current produce magnetic poles in the first and second rotor cores. The motor is caused to initiate its operation as an induction motor based on the first phase difference produced by the voltage phase shifting means, to have the first phase difference shifted to the second phase difference produced by the phase shifting means operated, and to have the first and second rotor cores produce the magnetic poles attracted by the rotating magnetic field produced by the first and second stators, resulting in the synchronous operation of the motor.

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: Apparatus and method for controlling the electromagnetic torque of an asynchronous machine. The apparatus includes a corrector which controls the electromagnetic torque of an asynchronous machine by regulating the magnetic flux and by controlling the electromagnetic torque C.sub.m, the corrector including a regulator circuit (3) for regulating the rotor magnetic flux .phi..sub.r , having non-linear control using input/output linearization by static looping and whose output controls the d-component of the stator current i.sub.s, a first linear corrector (1) of the proportional, integral type whose output v is the input to the regulator circuit, and a second linear corrector (2) of the proportional, integral type whose output controls the angular frequency of the rotor currents .omega..sub.s1.

Abstract: A detector 1, with its object of detection having operation characteristics that include a shift from a first state to a second state, outputs a signal e1 that corresponds to the operation characteristics of the object of detection. A first state detection circuit 2 generates a first output signal SA corresponding to the first state based upon the signal e1 provided by the detector 1. A second state detection circuit 3 generates a second output signal SB corresponding to the second state based upon the signal provided by the detector 1. The second output signal SB is generated only when the object of detection shifts from the first state to the second state in a normal manner while the first output signal SA is being generated. A state judgement circuit 4 generates a state judgement output signal Z on condition that there has been a period of time during which the first output signal SA and the second output signal SB have been both at high.

Abstract: The invention relates to a method for positioning a pen in a recording device for recording the time profile of a measurement signal which can be connected. In order to implement the highest possible mapping accuracy of the measurement signal onto the recording signal at a low cost and with DC isolation between the measurement signal and drive means of the pen, it is proposed that the positioning error (300) be phase-width modulated, the pulse-width-modulated positioning error (400) be transmitted in a floating manner to a signal converter (70), and a control voltage for the electric motor (90) be determined using the signal converter (70) from the pulse-width-modulated positioning error (400) by normalizing the difference between the pulse duration and the pulse-pause duration, via the sum of the pulse duration and the pulse-pause duration.

Abstract: An electric motor monitoring circuit apparatus for an electric motor has a three phase electric motor having an electric motor starter circuit. An insulation monitoring circuit is coupled to the electric motor and monitors insulation leakage of the electric motor and inhibits activation of the electric motor starter circuit when an insulation leakage exceeds a preselected threshold. A three phase monitor circuit is coupled to the electric motor for monitoring phase sequence in voltage amplitude for the electric motor.

Abstract: A control system (100) for a five-phase brushless DC motor (102) including a stator having five windings and a rotor (116) mounted for rotation relative to the windings (114). The windings (114) are adapted to be electronically commutated in response to the rotary position of the rotor (116). The control system (100) includes a sensing circuit (106) to sense the rotary position of the rotor (116) using an optical or magnetic sensor or the back electromotive force voltages in the windings (114). Electronic switches (112) control the flow of current through the windings (114) in response to control signals generated by a control circuit (110) in response to the rotary position of the rotor (116). The control circuit (110) includes start-up logic to start the motor (102).

Abstract: A method for estimating rotor shaft velocity includes adding two counter rotating signal components to a fundamental motor control signal to provide a combined control signal; sensing at least one motor phase signal; determining an extracted portion of the motor phase signal representative of the two counter rotating signal components; and using the extracted portion to estimate rotor shaft velocity. The step of adding two counter rotating signal components may include either adding a single phase signal in a reference frame synchronous to the fundamental motor control signal or adding two separate signals.

Abstract: A power tool has a variable speed control circuit that comprises a user switch, a motor and a silicon controlled rectifier (SCR) connected in series between a pair of power supply terminals. A manually variable resistor is connected between a first electrode of the SCR and a circuit node. A capacitor is coupled between the circuit node and a second SCR electrode. A bleed-off resistor is connected between second electrode of the SCR and the circuit node to provide a path for discharging the capacitor when the user switch is open. A zener diode couples the circuit node to the SCR gate electrode. The circuit configuration ensures that the capacitor charges from substantially the same voltage level at the start of each half-cycle during which the SCR is to be turned on.

Abstract: The motor speed control apparatus according to the present invention controls the rotation speed of a motor to be constant in a state where a disturbance torque is present. The motor speed control apparatus includes a disturbance torque observer 1. The disturbance torque observer 1 estimates a disturbance torque .tau..sub.d based on a detected speed signal v detected by a speed detector 105 and a drive signal D supplied to a drive circuit 150, and cuts off high-frequency components thereof by means of filters 13 and 2 so as to output an estimated disturbance signal d. A comparator 130 outputs a speed error signal .DELTA.v, which is a difference between the detected speed signal v and a desired speed signal v.sub.r. An arithmetic unit 140 outputs a control signal c in accordance with the speed error signal .DELTA.v. A torque correction unit 3 corrects the control signal c by using the estimated disturbance signal d so as to output the drive signal D.

Abstract: A quiet motor speed controller is disclosed which varies an amplitude of an AC voltage signal provided from an AC source to drive an AC motor. The controller includes a first impedance in series connection between the source and the motor. A second impedance is electrically connectable with the first impedance in accordance with settings of a switch such that the total impedance interposed between the source and the load is varied by switching. The first and second impedances are substantially defined by first and second capacitive values, preferably including resistive elements to limit current flow at charging and discharging.

Abstract: A time delay compensated synchronous reference frame controller for a drive motor having a rotor and using an alternating current having a phase angle includes a low pass filter electrically connected to the drive motor for eliminating high frequency components of the alternating current, a coordinate transformer electrically connected to the low pass filter for receiving the alternating current and for defining a moving reference frame based on the phase of the alternating current, a controller electrically connected to the coordinate transformer for driving the alternating current to a proper phase relative to a flux of the rotor of the motor, an inverse coordinate transformer electrically connected to the compensator for receiving the alternating current and for transforming the moving reference frame to a stationary reference frame, and a reference frame shifter operatively connected to this coordinate transformer and the inverse coordinate transformer wherein the reference frame shifter defines a shift i

Abstract: A PWM generation block implements two-phase/three phase conversion of torque current and exciting current and, on the basis of the converted three-phase torque and exciting currents and a three-phase current for driving and controlling the drive motor, outputs a PWM signal. A torque current estimator receives the same three-phase current as that of the three-phase current input to the PWM generation block, and implement three-phase/two-phase conversion of a three-phase current, by using a phase angle output from the microcomputer to calculate and output estimation values of the torque and exciting currents. A first comparator compares the absolute value of amplitude and the phase angle of the motor primary current and the motor primary frequency which are respectively output from the microcomputer with those which are respectively output from a fail-safe control block. The first comparator outputs a fail-safe signal when it detects differences between the compared values.

Abstract: An input power control apparatus for use with an AC induction motor adjusts a firing angle to allow the motor to run at near a rated speed of the motor and then to find a minimum power point at some voltage level in a variation of the applied voltage.

Abstract: The present invention relates to an applied-voltage fuzzy control process for induction motors including the following steps: measuring a speed error by comparing the current speed of an electric motor with a reference speed; generating the derivative of this speed error; measuring a power error by comparing the power supplied to the motor with a reference power; applying a fuzzy control to the speed error, to the derivative of the speed error, and to the power error so as to generate the values of a drive voltage and a power supply pulse that are suitable to drive the electric motor. The fuzzy control is divided into two sections: a first one for motor speed control and a second one for motor power control.

Abstract: A switching arrangement for controlling the rpm constancy between idling and full power of universal motors in electric tools has a phase-shift control (IC) which, for setting the set value, is connected at an output via an adjusting resistor with a tap of a voltage divider, and whose trigger output controls an electronic power switch disposed in the electrical circuit of the motor. In order to obtain an optimal readjustment of the load in the entire provided rpm range by means of such a switching arrangement, it is provided that between the tap of the voltage divider and the one output of the phase-control circuit (IC) at least one further adjusting resistor is provided, with which a preferably electronic circuit device is switched in parallel, which is controlled from a point in the voltage divider.

Abstract: An asynchronous motor is supplied with power from an AC line voltage via a variable speed drive including a rectifier bridge connected to the AC line voltage, a DC voltage intermediate circuit including a capacitor and an inverter including switches and connected to the phase windings of the motor. A system for controlling the power supply to the motor includes a device for controlled resumption of motor speed after supply of power to the motor is interrupted.

Abstract: A lift truck has a tractive-power electric motor, an electric motor which actuates a pump for the hydraulic circuits, and batteries which supply the electric motors. In order to obtain a long working life as well as reliability and a high performance, the tractive-power motor or both motors are asynchronous and there are provided devices for sensing the angular positions and angular velocities of the motors and an electronic control unit connected to the sensor devices for controlling the power supplies to the motors in dependence on required velocities for the motors and on the basis of data provided by the sensor devices.

Abstract: The method and the arrangement for temperature monitoring of universal motors based upon a resistance measurement of a field winding, wherein a DC current component of low magnitude is superimposed upon the motor current for elimination of the complex values of the AC current impedance, and wherein the voltage drop in the field winding is amplified and freed from the AC voltage component and is compared as a DC voltage component proportional to the ohmic resistance of the field winding to a temperature independent DC voltage component, which is obtained in an analogous manner from a current measuring shunt, through which the motor AC current, including the superimposed DC current component, flows.

Abstract: In one embodiment of the present invention, a control method for an induction motor includes calculating a desired quadrature-axis voltage and a desired direct-axis voltage according to both current control and voltage control. Below a predetermined motor speed, the motor is controlled in accordance with current control only. Above that predetermined speed, the two desired quadrature-axis voltages are combined in relative proportions, with the influence of voltage control being greater with higher motor speed. The two desired direct-axis voltages are likewise combined. The influence of voltage control thus increases with increasing motor speed. Above a second motor speed threshold, the motor is controlled in accordance with voltage control only.