Abstract: An electric tool includes a housing, a motor, a tool interface, a control circuit, a master switch, and a protection circuit. The tool interface is configured to connect to a power supply to supply power to the motor. The master switch is disposed on a current path formed by the tool interface and the control circuit. The master switch has an on state in which electric connection between the tool interface and the control circuit is on and an off state in which the electric connection between the tool interface and the control circuit is off. The protection circuit is connected between the master switch and the control circuit and is configured to disconnect connection between the tool interface and the control circuit in response to the master switch being in the on state before the tool interface connects to the power supply.

Abstract: Described are, among other things, methods and devices for providing a learning procedure in a yarn feeding arrangement (12). The learning procedure aims at providing control data to the controller (32) about system components and behavior of system components of the yarn feeding arrangement beforehand, such that the controller has knowledge of the system components before the weaving machine (10) is started to operate at full operational speed.

Abstract: A stapling end effector includes an anvil assembly having a distal end and defining a plurality of staple forming pockets, and a cartridge assembly pivotal relative to the anvil assembly such that the end effector is movable between open and clamped positions. The anvil assembly supports a plurality of staples corresponding to the plurality of staple forming pockets. The surgical stapling instrument further includes a sensing tip disposed on a distal end of the end effector. The sensing tip is formed of a flexible material and includes at least one sensor for measuring at least one mechanical property. The mechanical property may include force, pressure or torque.

Abstract: A control system is provided for an electric motor configured to drive a fluid moving apparatus to generate a fluid-flow. The control system includes a drive circuit configured to regulate power supplied to a stator of the motor to turn a rotor and generate the fluid-flow, and a processor that computes a value proportional to at least one of a system resistance or a static pressure for the fluid moving apparatus based on a fixed set point for a first control parameter and a feedback parameter. The processor receives a fluid-flow rate demand and computes an operating set point for a second control parameter based on the fluid-flow rate demand and the value proportional to the system resistance or the static pressure. The processor controls the drive circuit based on the operating set point to supply power to the motor and operate the fluid moving apparatus to generate the fluid-flow.

Abstract: A method of mitigating liquid-refrigerant migration includes comparing a requested compressor speed of a variable-speed compressor to a pre-defined threshold and, responsive to a determination that the requested compressor speed is greater than the pre-defined threshold, operating the variable-speed compressor at a first compressor speed that is less than the requested compressor speed.

Abstract: A dual motor system includes a first motor providing a lower speed range and a second motor providing a higher speed range, wherein the motors are coaxially arranged and aligned on and drive a common shaft, and a motor control system controlling the speed of the first motor and engaging the second motor as needed. The first motor is a variable speed motor providing a lower two-thirds of a full speed range, and the second motor is an induction motor providing the upper one-third in the form of one or more discrete fixed speeds. The system may include a transformer including a first winding tap which provides a first higher speed, and a second winding tap which provides a second higher speed. The system may also include a flow control system for automatically controlling the speed of the motors for particular applications, such as flow control in a pool.

Abstract: Disclosed are a motor control apparatus and method in an electric power steering (EPS) system for a vehicle. The motor control apparatus of an EPS system for a vehicle includes a temperature sensing unit configured to sense a temperature of a motor controller for controlling the motor in the EPS system and an output control module configured to adjust a motor current, applied from a steering control module of the EPS system to the motor, based on the motor current and the temperature of the motor controller sensed by the temperature sensing unit.

Abstract: A method of mitigating liquid-refrigerant migration includes comparing a requested compressor speed of a variable-speed compressor to a pre-defined threshold and, responsive to a determination that the requested compressor speed is greater than the pre-defined threshold, operating the variable-speed compressor at a first compressor speed that is less than the requested compressor speed.

Abstract: A motor driven power steering (MDPS) may include: a vehicle speed sensor configured to sense vehicle speed; a temperature sensor configured to sense a temperature of a power pack; a current sensor configured to sense an amount of current applied to the MDPS; a storage unit configured to store a thermal resistance value based on the vehicle speed with respect to the temperature of the power pack; and a control unit configured to calculate an estimated temperature by reflecting the thermal resistance value based on the vehicle speed with respect to the temperature of the power pack and the current amount applied to the MDPS into a temperature estimation function, and drive a motor according to the calculated estimated temperature.

Abstract: A method and device for controlling an electric motor, in particular a machine tool drive, wherein during a sensorless open-loop control mode of operation of the electric motor the speed and the torque are determined from the motor current and the motor voltage, and the moment of inertia of the electric motor torque are determined from the determined motor current and the determined motor voltage, wherefrom then a control torque is determined, which is then associated with an open-loop torque control value and supplied as the torque setpoint value to a control element for setting the motor current and/or the motor voltage in the open-loop mode of operation. As long as the speed is below a minimum speed, the control element receives as input variable a control or pilot control torque generated from a predefined moment of inertia for a sensorless closed-loop control mode of operation of the electric motor.

Abstract: A system and process includes continuously determining an applied armature voltage supplied to a polyphase synchronous machine for which a maximum mechanical load is characterized by a pull-out torque. The armature voltage is supplied from a power source via one of many taps of a regulating transformer. The armature voltage being supplied from the power source to the machine is changed by selecting one of the voltage levels from the taps of the regulating transformer. The tap voltage levels are selected based on the determined applied armature voltage to minimize power consumption of the machine while ensuring based on a predetermined confidence level that the pull-out torque of the machine will not be exceeded.

Abstract: Disclosed is a circuit arrangement for electrically controlling and/or regulating the movement of an electrically driven unit (2), especially a window lifter or sliding roof of a motor vehicle, and to a method for operating said circuit arrangement. According to the invention, a jamming protection System is characterized in that a correlation variable (K) for the adjusting force of the unit (2) is measured and the adjusting movement is stopped or reversed in order to prevent jamming if the correlation variable (K) for the adjusting force exceeds a threshold value that corresponding to a predetermined jamming force. A filter (140) is used for temporally filtering the correlation variable (K) for the adjusting force of the unit. The invention is characterized in that the filter parameters (142, 143), especially the cutoff frequency (fg) and/or the order of the filter (140), can be controlled.

Abstract: In order to stabilize a performance of a pump employed for processing in an inkjet printing apparatus such as sucking ink from a printing head with a low cost configuration and without the need of using any specific detecting unit, the following configuration is employed. Namely, a tube pump having a member with a curved surface aligned with a flexible tube for supporting the tube and a roller which moves while pressing (squeezing) the flexible tube is driven with a DC motor. To keep revolutions always constant, a current PWM control is employed for changing a power applied to the motor according to load fluctuations, and a phase of the roller is determined based on the current PWM value to manage a pressure generated by the pump and a discharge rate.

Abstract: The invention relates to an electric power tool having a control and/or regulating device for an electric motor. It is provided that the control and/or regulating device (4) is assigned an electronic memory element (5) for at least one operating state of the electric motor (1).

Abstract: Systems and methods of detecting an overload condition. In one embodiment, a method of monitoring a load of a DC motor includes intermittently de-energizing the motor; monitoring a first voltage; and measuring a first interval of time between a starting time and an ending time, wherein the starting time comprises the time at which the motor is de-energized and the ending time comprises a time at which the first voltage and a reference voltage have substantially similar values.

Abstract: An eletrical device derives power from an incoming power source to produce output plower to drive the device. The device includes circuitry that determines at lehst one characteristic of the incoming power source, and adjusts the output power used to drive the device based on the characteristic or characteristics of the incoming power source.

Abstract: A method for determining the mass moment of inertia of an electric motor drive system of a machine, having a drive motor and further drive elements arranged downstream of the drive motor. The method includes a) determining a compensation current, which compensates losses occurring at a constant speed of the motor, so that a motor speed of the drive motor remains constant and b) determining an acceleration current, which generates a defined acceleration of the drive motor when the losses occurring at the constant speed of the drive motor are compensated. The method further entails c) calculating a mass moment of inertia of the electric motor drive system based on the determined acceleration current.

Abstract: A method of reducing torque ripple and noise for an brushless DC machine comprising: determining a control frequency for the electric machine, the control frequency indicative of an existing current command to and a rotational velocity of the electric machine; multiplying the control frequency by a selected multiple and forming a modulating signal responsive thereto; and formulating a modified command profile. The method also includes: correlating and synchronizing the modified command profile with the existing current command and a rotor position for the electric machine; and generating a modulated current command to the electric machine.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck. The control circuit for the power tool is operable in a ratcheting or pulse mode that causes the output spindle to rotate in discrete incremental amounts. Corresponding methods for controlling the operation of the electric motor of a power tool are also disclosed.

Abstract: A steer-by-wire control system comprising a master control system, a road wheel system, and a hand wheel system is disclosed. The road wheel system is connected to the master control system and includes a road wheel position sensor and a rack force sensor. The hand wheel system is connected to the master control system and the road wheel system and includes a hand wheel position sensor and a torque sensor. The steer-by-wire system also includes a vehicle speed sensor for producing a vehicle speed signal. In addition a hand wheel actuator configured to receive commands from the hand wheel system and a road wheel actuator configured to receive commands from the road wheel system are utilized. The hand wheel system and road wheel system each include a configurable control topology.

Abstract: A method and apparatus for controlling the output function of a permanent magnet brushless DC motor (20), by sensing an input current to the motor (20), by computing an output torque generated by the motor (20) as a function of the input current to the motor (20), by computing an output pressure for a pump (22) in response to the output torque, by reading a set point pressure, and by comparing the set point pressure to the output pressure, and in response thereto controlling on-off operation of the motor (20). The apparatus includes a sensing circuit (28) and a microelectronic processor (30) for performing these functions.

Abstract: A method and apparatus for achieving constant air flow rate economically utilizes an induction blower motor with control settings determining the motor excitation voltage. A memory stores, for a variety of motor speeds, a graph of the speeds plotted against a proportionality constant of flow rate to fan speed for the selected motor system on one axis and motor control settings on the other axis. The only monitoring necessary to achieve the constant flow rate is thus the sensing of fan rotational speed. The measured fan speed is compared against the proportionality constant needed for the selected constant air flow rate and a motor excitation voltage is derived to achieve that proportionality constant. When the system load changes significantly, thereby causing significant fan speed change, a cascaded control loop is used whereby the speed changed induced by each control voltage adjustment is monitored until the desired constant flow rate is again attained at the new load level.

Abstract: An available input of to a motor controller is used to measure the motor power supply voltage. Typically, a scaled down version of the voltage is sensed. The microprocessor is used to calculate the motor control current, in that case, is then calculated from the scaled down version. A scale factor that depends upon the sensitivity of the motor current to the motor supply voltage is calculated by the microprocessor. Driving parameters in the controller are then adjusted to account for the scale factor. In a preferred embodiment, the driving parameters are PWM parameters, and the microprocessor multiplies the measured power supply voltage to obtain a scale factor that can then be multiplied by the nominal PWM values to obtain the new PWM values.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck and has associated therewith a degree of looseness which must be taken up before torque from the motor is applied to the tool bit. The control circuit for the power tool increases the effective torque output of the tool after a predetermined torque level is attained, by alternately turning the motor on and off, with the duration of the off-time sufficient to permit the gear train to relax, thus giving the motor a “running start” when power is reapplied. Various alternative schemes for transitioning to this ratcheting mode of operation are disclosed including the sensing of a predetermined threshold current, a predetermined increase in motor current, and a predetermined rate of deceleration in motor speed.

Abstract: In an electric hand, a cam member 12 mounted to a drive shaft 3a of an electric motor 3 is provided with a pair of cam grooves 15 and 15, a pair of jaw members 2 and 2 for grasping a workpiece are provided with drive pins 13 fitted to the cam grooves 15 and 15, and a normal or reverse rotation motion of the drive shaft 3a is converted into an opening or closing motion of the jaw members 2 and 2 by the cam member 12 and the drive pins 13. A torque limiter 6 having a friction plate 19 for connecting by a frictional force the drive shaft 3a of the electric motor 3 and the cam member 12 is provided between the drive shaft 3a and the cam member 12, and a torque of the drive shaft 3a transmitted to the cam member 12 is limited by this torque limiter 6.

Abstract: A pump motor control apparatus is adapted to control a pump motor of a forklift truck by using a driving transistor connected between a battery and the pump motor. The pump motor control apparatus includes a current detection circuit for detecting a current flowing through the pump motor to generate a current detection signal representing the current. A controller is employed to determine the load condition based on the current detection signal to thereby generate a control signal for use in the control of the driving transistor. The control signal is a pulse width modulation signal whose on-duty ratio is controlled depending on the load condition so as to decrease the torque and speed of the pump motor during the unloaded condition but to increase the torque and speed of the pump motor during the loaded condition.

Abstract: An electric power steering apparatus includes a control unit for controlling a motor drive circuit which drives an electric motor on the basis of a steering torque signal supplied from a steering torque sensor. The control unit includes a center value compensating circuit for compensating for the offset of a center value of the steering torque sensor, and a direction inhibiting circuit for inhibiting supply of a motor control signal to the motor drive circuit on the basis of the steering torque signal. The direction inhibiting circuit has a reference value changing section for changing operation reference values in left and right directions of the steering torque in response to the offset of the center value. The reference value changing section generates left and right operation reference values corresponding to a center value signal supplied from the center value compensating circuit.

Abstract: A device for outputting a suitable rotation torque relative to a load torque or actual torque exerted on a stepper-motor when the stepper-motor is used as a drive of an image processing device. The output torque of the stepper-motor depends on a supply current to the stepper-motor. CPU determines a suitable supply current using a table in ROM so that the stepper-motor is able to rotate at an optimum rotation torque. To this end, CPU sends a particular signal to the motor driver so that an appropriate supply current is supplied to the excitation phases A/B of the stepper-motor. The CPU determines the load torque based on an integrated current fed to the stepper-motor during a particular period. The CPU calculates difference between the load torque and rotation torque and determines the signal to be applied to the motor driver based on the torque difference.

Abstract: Air handling apparatus (10) delivers a volume of air at a generally constant flow rate regardless of changes in the operating conditions of a system with which the apparatus is used. A blower (12) pushes air from one point to another. The blower is operated by a blower motor (14). A switch (16) controls application of power to the motor. Sensors (20) are used to sense the current drawn by the motor and the motor's operating speed. A flow controller (22) establishes a desired air flow rate to be provided by the blower. A processor (18) is responsive to the sensed current (I), motor speed (S), an input (C) from the flow controller, and constants (K1-K4) related to performance characteristics of the blower to determine a torque required by the motor to produce a predetermined air flow rate. The torque value is determined as a function of the combined motor speed input from the sensor and an input from the flow controller.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck and has associated therewith a degree of looseness which must be taken up before torque from the motor is applied to the tool bit. The control circuit for the power tool increases the effective torque output of the tool after a predetermined torque level is attained, by alternately turning the motor on and off, with the duration of the off-time sufficient to permit the gear train to relax, thus giving the motor a "running start" when power is reapplied. Various alternative schemes for transitioning to this ratcheting mode of operation are disclosed including the sensing of a predetermined threshold current, a predetermined increase in motor current, and a predetermined rate of deceleration in motor speed.

Abstract: A powered medical instrument includes a manually operable foot switch coupled to a motor control unit which in turn is coupled to an autoclavable handpiece containing a brushless sensorless electric motor driving a tool. The motor control arrangement includes a control panel through which a user can select a maximum torque value for the motor, and includes a torque limit circuit which limits the motor torque to the torque limit value selected by the user. The control panel also provides a digital display of actual motor speed and allows the user to digitally specify a maximum motor speed. The output of the foot switch is adjusted by a transfer function and then used to control motor speed, and the transfer function is adjusted as necessary to precisely conform the actual motor speed and thus the displayed speed to the selected maximum speed.

Abstract: A method for calculating a speed estimated value in a speed control system, comprises the steps of: (a) storing the number of speed detection pulses obtained at each interval of a speed control process and time that the speed detection pulse was obtained; (b) calculating a detection speed from the number of latest speed detection pulses and its detection time, and the number of the previously stored speed detection pulses and its detection time; (c) executing an averaging process of motor model output corresponding to time that the detection speed was obtained; (d) obtaining a difference between an output obtained at said step (c) and the detection speed; (e) executing a calculation of a load torque estimation by multiplying the difference of the step (d) by an observer gain; (f) executing an estimation of a motor speed for next processing from the difference of the step (d) and a difference between the detection speed and the motor model output; (g) calculating an output of a speed amplifier by constituting

Abstract: A speed estimation observer for a motor control system outputs a motor speed estimate in a motor speed control system upon receiving a torque command and an averaged motor speed value. The speed estimation observer includes a time lag correction value calculating block for implementing a correction of a model output speed estimate. Therefore, the accuracy and stability of the speed estimation are improved, and the control system keeps the stability in a speed range of low to high speed and ensures the disturbance suppressing effect in a high speed range.

Abstract: A control arrangement for an electric assist steering system having a variable reluctance motor (26) includes sensing (54) motor position and sensing (110) applied steering torque. A controller determines a desired motor torque assist value in response to the applied steering torque. A plurality of look-up tables are provided having a plurality of motor current values versus motor position values stored therein. The stored motor current values are functionally related to motor position values. The controller selects a first (T1) and second (T2) torque look-up table from the plurality of look-up tables. The first look-up table corresponds to a torque value less than the desired motor torque assist value. The second look-up table corresponds to a torque value greater than the desired motor torque assist value. A first motor current value (I1) is determined by interpolating between two current values corresponding to two motor positions stored in the first look-up table closest to the sensed motor position.

Abstract: An electric motor control system compensates torque ripples to control the rotation of an electric motor more accurately. Compensated current amplitudes corresponding to the torques, speeds and rotational positions in the electric motor are stored in a memory 61. Address setting unit 91 prepares a read address AD.sub.1 in the memory 61 from the torque command T, speed information VL and rotational motor position P. The prepared read address AD.sub.1 is then used to read a torque error compensation data MD.sub.1 from the memory 61. An adder 12 adds the torque error compensation data MD.sub.1 thus prepared to the torque command T to determine current amplitudes AM in the electric motor. Three-phase current setting unit 10 sets three-phase AC current commands CU, CV and CW based on the current amplitudes AM and rotational motor position P. Thus, the rotation of the electric motor can be accurately controlled.

Abstract: A dc motor wherein a driving force thereof can be used effectively with a simple and compact mechanical construction and a motor controlling system which can control such a dc motor to be driven efficiently. The motor comprises at least two coils, and change-over means for changing electric connection of the coils to change over the motor, when power is selectively supplied to the coils, between a first mode in which the torque produced is relatively high and the rotational frequency is relatively low and a second mode in which the torque is relatively low and the rotational frequency is relatively high. The motor controlling system includes selecting means for automatically selecting one of the first and second modes to control the change-over means in response to a given condition of the motor.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck and has associated therewith a degree of looseness which must be taken up before torque from the motor is applied to the tool bit. The control circuit for the power tool increases the effective torque output of the tool after a predetermined torque level is attained, by alternately turning the motor on and off, with the duration of the off-time sufficient to permit the gear train to relax, thus giving the motor a "running start" when power is reapplied. Various alternative schemes for transitioning to this ratcheting mode of operation are disclosed including the sensing of a predetermined threshold current, a predetermined increase in motor current, and a predetermined rate of deceleration in motor speed.

Abstract: A solid state, electric motor control circuit is provided in conjunction with a solid state throttle and vehicle sensor circuit that together incorporate; a Hall Effect throttle position sensor circuit, a throttle position signal amplifier circuit, a vehicle reverse condition circuit, a vehicle operation inhibit circuit, a pulse width modulation circuit, and inverting MOSFET driver circuit, a plurality of power MOSFET devices, a voltage regulator circuit, and a current delivery circuit associated with an external DC electric motor. These circuit elements combine to translate a mechanical throttle position into a voltage level signal that can be converted by pulse width modulation circuitry into a pulsed wave form signal that suitably drives a bank of MOSFET, solid state switches so as to control the flow of current through a DC electric motor.

Abstract: Herein disclosed are a method and an apparatus for suppressing a torsional vibration in an electric motor speed control system including a mechanism for transmitting a drive torque from an electric motor to a load through a drive shaft having a torsional spring system. Generally speaking, the signal of a speed detector (3) of an electric motor is a pulsating signal of high frequency. Even if this speed detecting signal is differentiated, it is impossible to obtain a signal proportional to the changing rate of the motor speed. By computing an average value of the signals of the motor speed detector (3) for every predetermined period, however, the pulsating value of the speed signal can be reduced to compute the changing rate of the motor speed from that signal.

Abstract: The pulse width modulated DC motor speed control circuit indirectly senses motor current using sense MOSFETs and a peak detector circuit with storage capacitor for deriving an average motor current signal. The average motor current signal is used both in the feedback loop of the pulse width modulated speed control circuit and also in the motor shutoff or clutch circuit. The clutch circuit shuts off power to the motor when a user-settable torque is reached. The motor speed control circuit is therefore adapted for use in hand-held DC power tools such as screwdrivers and nutdrivers which stop rotation at a predefined torque.

Abstract: A closed-loop feedback control system is disclosed for controlling an operation of a load. An actual operation signal is subtracted from a reference operation signal to produce a resultant signal which is used to control the operation of the load. A filter unit, such as a notch filter, operates to suppress any machine resonance frequencies found in the operation signal due to load fluctuations, machine variations, operating environment changes, deterioration with age, etc. A filter coefficient of the filter unit is adjusted so that any fluctuation in the resonance frequency can be suppressed effectively.

Abstract: A speed controller for a DC motor minimizes speed droop and load droop through pulse width or frequency modulation. The controller provides an extra power increase upon engine starting or whenever a heavier load is temporarily encountered. The control circuit also has a current limiter, overload indicators, and a battery recharger. The controller is very inexpensive, primarily because all of the timing components are contained on a single integrated circuit timer chip such as a 556 timer. The controller contains other features, including a circuit for limiting the pulse width of the control signal from the pulse width modulator.

Abstract: The invention provides a control system for an electric motor arranged to drive a rope drum of a mine winder or a hoist system which includes a conveyance supported by a rope and which forms an oscillating system. The control system includes load sensor which monitors the load in the rope and a rope length sensor which monitors the length of rope paid out from the rope drum. A motor control unit is responsive to signals from the sensors and calculates setpoints for speed, acceleration and jerk of the oscillating system. The control unit generates a control signal which is related to a natural oscillation mode of the oscillating system so as to prevent the excitation of oscillations in the system, and controls a motor drive in accordance with the control signal.

Abstract: A load of an electronic sewing machine is self-diagonosed by a control system to cause a DC motor to be operated under control to drive upper and lower shafts of the sewing machine. The control system includes an evaluating device to which a voltage value applied to the DC motor and a rotating speed of the DC motor, both detected, are inputted for determining a current value supplied to the DC motor and a power loss of the DC motor. These data are supplied to a fuzzy inference unit for inferring an optimum rotating speed of the DC motor. A control command signal representing an excessive degree of the actual power loss in reference to the rated power loss is outputted from the fuzzy inference unit to the DC motor for the control of the electric power to be supplied thereto.

Abstract: A system and method for controlling the speed of a motor operating in an extremely low speed range and having a rotary pulse encoder which outputs a pulse whenever a rotation axle of the motor has rotated through a predetermined angle. The extremely low speed range is defined such that its pulse interval of the output pulses is longer than a speed control period of the system are disclosed, load torque estimated value observer is provided. The least order disturbance observer includes a first calculating block which calculates an estimated value of the motor speed n.sub.M ' (j) of a motor model on the basis of a torque command and a load torque estimated value: a second calculating block which calculates an average value of the motor speed at each pulse interval n.sub.M ' (j).

Abstract: A method for driving a weaving machine during slow motion includes the steps of carrying out the slow motion drive using the main drive motor, and controlling excitation of the main drive motor as a function of the load on the weaving machine parts which has been predetermined and stored in a memory as a function of weaving machine part positions. The required speed of the weaving machine parts to be driven may also be taken into account in controlling the main drive motor. A device for carrying out the method includes the main drive motor, a power phase controller for the main drive motor, detectors for detecting the positions of the weaving machine parts, and a comparator for comparing the positions with stored positions in order to take into account the load data which has been entered.

Abstract: Method and apparatus for operating a vacuum cleaner in which by detecting a rotational speed of a variable speed fan motor adapted to give a suction force to the cleaner and its change range, the choking state of the filter and the state of the cleaned surface are discriminated, and a speed command of the fan motor is corrected on the basis of the result of the discrimination, and the comfortable cleaning can be performed by the optimum suction force.

Abstract: A method and apparatus for torque equalization on the drive of a rolling stand, having a linear oscillatory movement driven via a crank drive, of a Pilger step-by-step rolling mill, particularly a cold Pilger rolling mill. In order to avoid the inefficient and/or expensive drive and to create a torque equalization system which avoids generator operation of the motor of the drive device of the mill and therefore torques acting in the direction of rotation of the motor on the motor, the variation of speed of rotation of the crank drive, determined mathematically from the kinematic parameters of the system, the masses moved and the external loads, is imparted to the crank drive as a desired variation of speed of rotation.

Abstract: A load driving circuit causes a driving current to flow through a load, such as a reel motor, an audio load or the like through the collector and emitter of a drive transistor. A load voltage which changes according to changes in the driving current is obtained at a point of connection between the drive transistor and the load. On the basis of the load voltage, an offset voltage having a predetermined constant value is generated in a power supplying circuit so as to cancel a change in the load voltage. The offset voltage is supplied as driving source output to the drive transistor so as to prevent the generation of excess heat in the drive transistor even if the driving current changes.

Abstract: A control for a d.c. motor having a d.c. thyristor power supply connected to a d.c. motor and a control circuit for selectively varying and controlling the level of the current provided by the thyristor power supply to the motor. The thyristor power supply provides a plurality of selected output current levels to the motor and the motor has a corresponding plurality of torque levels. The level of the output current supplied by the power supply to the motor is independent of the resistance in the motor circuit. The motor is rotatable in opposite directions and the thyristor power supply will provide output voltage at opposite pluralities corresponding to the rotational direction of the motor.