Abstract: An apparatus and method for controlling a brushless direct current motor having a pulse width modulated 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 commutation Hall sensor in the motor. A developed motor torque is calculated by operating on a table of motor specific constants, a modulation index and the motor speed taken from the commutation Hall sensor. The calculated required blower torque is repeatedly compared with the calculated developed motor torque. The modulation index to the pulse width modulated variable frequency drive is modified to force the developed motor torque to converge with the required blower torque in a steady state.

Abstract: A disk drive is connectable to a power supply having a fixed DC voltage. The disk drive includes a voice coil motor and a spindle motor. A DC to DC voltage converter converts the fixed DC voltage to an increased DC voltage greater than the fixed DC voltage. A voice coil motor driver has switching elements which are controllable to supply the increased DC voltage to the voice coil motor. A spindle motor driver has switching elements which are controllable to supply the increased DC voltage to the spindle motor. The increased VCM voltage allows faster access times and more efficient VCM operation. The increased spindle motor voltage allows for more efficient spindle motor operation.

Abstract: An actuator for a driving mode shifting device. A motor having a motor shaft which outputs rotational torque according to electrified electric current. An output member, which is moved by the rotational torque, shifts drive modes according to positions thereof. A torque transmitting mechanism transmits the rotational torque from the motor shaft to the output member. A control mechanism selects drive modes and controls the electric current to energize the motor so as to provide the selected drive mode. A one-way rotational mechanism is disposed between the motor shaft and the torque transmitting mechanism for preventing the motor shaft rotating against the motor. A rotational torque absorption mechanism is disposed between the one-way rotational mechanism and the torque transmitting mechanism for absorbing the rotational torque, when the motor shaft is rotated and the output member can not be moved. A rotational angle detecting means detects the rotational angle of the motor shaft.

Abstract: A control system for determining a control function for a control device on the basis of a transfer function of an object to be controlled and for adjusting an operation quantity of an object to be controlled in accordance with the determined control operation function, wherein an control function of a first control device is determined so that a closed-loop transfer function of a control system including the object to be controlled and the first control device coincides with a predetermined first transfer function, an control function of a second control device is determined, in a closed loop control system including the control system and the first control device, so that a transfer function from a disturbance applied to the object to be controlled to a state variable of a point at which the disturbance is applied to the object to be controlled, and a sum signal indicative of a sum of outputs of the first and second control devices is used as an operation quantity of the object to be controlled.

Abstract: The transmission includes a planetary gearing mechanism including an input member adapted for connection to an engine, a member connected to a first electric machine operable as a motor or a generator, a member connected to a second electric machine operable as a motor or a generator, and an output member, the first and second electric machines and the members connected thereto being respectively rotatable for controlling a torque acting on the output member. The present control and associated method includes a first controller for controlling the rotation of the first electric machine and a second controller for controlling the rotation of the second electric machine, the first and second controllers being connected in electrical communication by a conductive link and controllable by first and second torque command signals, respectively.

Abstract: A diagnostic system for electric motors, such as those used in automotive applications. The system comprises a controller for supplying a desired command current to said electric motor, a sensor for measuring the rotational speed of the motor, a sensor for measuring the actual current supplied to the motor by the controller, a diagnostic control unit adapted to receive the measured rotational speed, measured supplied voltage, and a command current level value as inputs. The diagnostic control unit further comprises circuitry to calculate an estimated actual current drawn by the motor and to signal an error condition if the estimated actual current is not within a calculated valid range.

Abstract: A motor-driven power steering apparatus comprises: a torque sensor for detecting a steering torque; an assist indicator for outputting an indication signal which indicates the direction and magnitude of an output torque of a motor power-assisting a steering mechanism; a dither signal generator for outputting a high-frequency dither signal; and a control circuit for controlling a current supplied to the motor according to the indication signal provided by the assist indicator and the dither signal provided by the dither signal generator.

Abstract: A device for controlling load on a first motor whose load is affected by a second motor, comprises a controller having a first input for being connected to a horsepower transducer connected to the first motor being monitored and an output for being connected to the second motor; and a program configured to receive the first input and generate the output responsive to the input.

Abstract: The present invention relates to a method and a device for executing phase compensation in a control system of a motor-driven vehicle, in which the time derivative for an output signal (y) from a circuit (1) contained in the control system is limited relative to the time derivative for an input signal (u) to the circuit (1) if the time derivative for the input signal (u) exceeds a predetermined value. An error signal (&egr;) is formed between the output signal (y) and the signal (x) present in the circuit (1), the time derivative of which is not limited in relation to the time derivative for the input signal (u). The error signal (&egr;) is filtered via an asymptotically stable filter (3) to form a signal (&dgr;), which is fed back and subtracted from the input signal (u) of the circuit (1) to form the signal (x). A conventional rate limiter may be used to form the output signal (y) from the signal (x).

Abstract: The object of the present invention is to provide a method for limiting the hydraulic maximum pressure of a power-assisted steering system, which permits effective pressure limitation and thus protects the individual elements of the power-assisted steering system, i.e., a pressure limitation not far above the desired maximum operating pressure, but on the other hand does not require an overdimensioning of the individual segments of the power-assisted steering system.

Abstract: A torque command Tc is restricted to a torque limit value Tm′ by torque limiting means and delivered to current restricting means for a motor. The torque limit value Tm′ is derived by adding a torque limit correction value &Dgr;Tm as calculated by torque limit correction value calculating means to a torque limit value Tm corresponding to the target pressing force F. The torque limit correction value &Dgr;Tm is supplied in accordance with the acceleration value when the motor is accelerated or decelerated. This acceleration is calculated from the feedback velocity Vf from the velocity detector, or the command velocity Vc. Alternatively, it may be derived from the output of an observer which inputs the torque command Tc′ supplied to the current control means of the motor, and the feedback velocity Vf.

Abstract: When torque control is performed for suppressing speed change within one rotation using a synchronous motor (6) controlled by an inverter (5) for a load having cyclic torque changing, an arrangement is employed which includes inverter control means (8) (10) for controlling the inverter (5) so as to superpose a changing amount upon an amplitude and phase of a current waveform or voltage waveform, so that torque control is realized for reducing low speed vibration of a cyclic intermittent load with maximum efficiency condition and with practical arrangement.

Abstract: The task of the invention comprises reliably acquiring documents from an output device with variable output speed without impermissible tractive forces being exerted onto the documents. For this purpose the rotational speed of the transport system of the acquisition unit is determined under no-load condition and the torque of the drive is reduced, for example by current imitation, until the transport rate of the acquisition unit is just above the maximum occurring transport rate of the output device. The torque value thus determined, which represents the torque requirement for overcoming the friction of the system, is stored and set as the nominal value during the document acquisition. As a drive motor can be used DC current motors as well as also load-controlled electronically commutated motors.

Abstract: An electric motor actuator used in an environment of varying loads for varying time periods is efficiently designed to a predetermined specification in terms of both motor load and time and operated up to but not exceeding this specification over the full expected operating range. A motor load signal is low pass filtered with a plurality of time constants spanning a range of expected motor operation to generate a plurality of filtered motor load signals each associated with one of the time constants. Each of these filtered motor load signals is compared with a predetermined reference value corresponding to the associated time constant. If one or more of the filtered motor load signals exceeds the predetermined reference value with which it is compared, the one that so exceeds by the greatest margin is selected. A command current limit factor is derived from the selected filtered motor load signal and used to limit the commanded motor current.

Abstract: A surface-mounted permanent magnet synchronous machine drive 10 and a method 30 of controlling the machine drive. Flux weakening and current regulating loops 70, 60 cooperate to provide automatic transition to the flux weakening mode (operation above base speed), regardless of DC bus voltage, load or other operating conditions. This feature provides significant performance improvement. No look-up tables are used in the flux weakening loop. The on-set point for flux weakening is automatically adjusted, and may be changed through software. An appropriate d-axis current component is injected over the entire speed range, providing the maximum available torque (which corresponds to the q-axis current component). The control method works with fixed frequency current compensators.

Abstract: An electric power steering control system reducing steering torque without making a driver feel uncomfortable torque oscillation, including a rotation speed observer for estimating the rotation speed of a motor based on the output of a torque sensor high pass filter (HPF) and the output of a drive current HPF obtained by removing a steering frequency component from a drive current detection value.

Abstract: An electric power steering control for a motor vehicle reduces motor torque ripple and road generated disturbances communicated to the vehicle handwheel while promoting system stability. In deriving an output command torque signal to the EPS motor, the control (1) derives an electric motor speed signal, (2) differentiates the electric motor speed signal, (3) stores a schedule of gain as an increasing function of electric motor torque, (4) modifies the differentiated estimated electric motor speed signal in response to the gain to provide a damping correction value and (5) derives the output command signal responsive to the damping correction.

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: An electric power steering apparatus comprises a control unit for drive-controlling a motor to apply an assist torque to a steering system based on signals from various sensors. The control unit comprises a slip angle difference predicting section for predicting a difference between a slip angle of front wheels and a slip angle of rear wheels, and a correcting section for correcting, based on an angle difference signal outputted from the slip angle difference predicting section, a target torque signal supplied to the motor. Behavior of a vehicle is predicted from the angle difference signal and the target torque signal is corrected by a correction amount corresponding to the angle difference signal so that the motor can be drives controlled with the influence of a change in a road surface reaction force taken into consideration.

Abstract: A motor control system uses predictive signal processing techniques to estimate the value of the next motor torque request or command from a controller within a brake-by-wire system, then adjusts the control of the electric motor that applies pressure to actuate the brake calipers.

Abstract: A current flowing to a motor 8 for generating a steering assist force for a steering mechanism is detected by a motor current detecting circuit 24 to be inputted to a controller 10 as a motor current detection value IMS. The controller 10 arithmetically determines deviation between the motor current detection value IMS and a desired motor current value IMT preset on the basis of a vehicle speed and a detected steering assist torque value and decides abnormality of the motor current detecting circuit 24 when the deviation indicates an abnormal value over a period equal to or longer than a predetermined time.

Abstract: Power electronic based power and propulsion systems are used in a wide variety of applications including locomotives, hybrid electric vehicles, aircraft, spacecraft, and ships. In general, the power electronic loads in such systems have tightly regulated outputs which causes them to behave as constant power loads exhibiting negative input impedances in a small signal sense. Such systems can be prone to negative impedance instability. The present invention mitigates negative impedance instability without the introduction of any passive or active devices into the system by providing nonlinear modulation of the power into the power electronic load.

Abstract: A machine tool has a spindle with a tooling body mounted thereon, a detector for detecting an acceleration time for the tooling body to reach from a rotation start to a predetermined rpm, a controller for controlling an rpm of the spindle under a lowered limit when the acceleration time is longer than a reference time. Another detector detects an asymmetricity of radial forces acting on the spindle, and the controller controls the rpm of the spindle under a lowered limit when the asymmetricity of radial forces exceeds a reference degree.

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: An electronically assisted power steering system (10) for providing assist in response to a steering control signal includes a steering torque sensor (30) operatively connected to a vehicle hand wheel (12) for providing a torque signal indicative of applied steering torque. An electric motor control module (50) is connected to the torque sensor (30) and to an electric motor (32). The electric motor control module (50) includes an outer loop controller for generating a desired torque signal responsive to the applied steering torque. The outer loop controller includes a phase lag network in series with a second order network for compensating the desired torque signal. The electric motor control module (50) also includes an inner loop controller for generating a motor drive signal responsive to the desired torque signal output from the outer loop controller. The inner loop applies a motor drive signal to the electric motor to generate the required assistive torque.

Abstract: In an armature current limit value calculator section, limitation is applied to a pre-limitation torque command ST in correspondence with a presently detected speed SPD, to calculate a torque command STC. Meanwhile, in a field current calculator section 12, a pre-correction field current command value SF is decreased in correspondence with the detected speed SPD when the speed is large. In addition, a coefficient K.tau. which increases when the torque command is large is calculated on the basis of the pre-limitation torque command ST at this time. Further, a field current command is calculated from an equation SFC=K.tau.*SF. A current command calculator section 3 prepares a current command on the basis of the torque command STC and the field current command SFC supplied, and drives an electric motor 5 via a current control section 4.

Abstract: A control command value map is formed with a voltage applied to a motor and an output torque as an output command value from a driver being taken on axes of coordinates, so that an output command value suitable for a power source voltage is easily and rapidly provided regardless of a variation in voltage of a motor driving power source by applying an output command value determined from the control command value map from an output command value determining means to a driving means. The motor can be driven based on such output command value.

Abstract: Described are control apparatus and method for a motor applicable to an electric vehicle in which a motor drive circuit having a plurality of arms, each arm including same series-connected semiconductor switching devices for controllably switching a voltage applied thereacross from a DC power supply so as to apply an AC power to the motor, is associated with the motor, switching operations of the respective semiconductor switching devices so as to regulate a driving of the motor according to a torque instruction inputted thereto are controlled, a temperature having a correlation to a junction temperature of at least one semiconductor switching device is detected, the detected temperature is read, the junction temperature of the semiconductor switching device from the detected temperature is estimated, a determination is made whether the estimated junction temperature is above an allowable limit of the junction temperature, and an output of the motor drive circuit to the motor is adjusted so that the estimated

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 bypass circuit conducts electrical current around a motor starter to a current limiting switch assembly upon initiation of a flow of excessive electrical current to an electric motor to protect the motor starter against excessive current flow. Upon initiation of excessive current flow to the electric motor, the current limiting switch assembly opens a main circuit to interrupt current flow through the motor starter. The current limiting switch assembly includes a conductor or contact carrier which is movable from an initial position to an actuated position under the combined influence of current flow through a coil and opposition between magnetic fields from portions of an electrical circuit through which current flows in opposite directions.

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: An electric stapler is provided with current in multiple pulses in order to penetrate a thick stack of paper. The stapler is provided with current sufficient to staple a thin stack of paper. If the stapler does not complete its staple function after a time period corresponding to anticipated completion of the cycle, the current is interrupted. The current is then reapplied after the load on the stapler has attenuated. The reapplication of current results in a hammering action. This permits a thicker stack of paper to be stapled with a stapler which is optimized for the thin stack.

Abstract: An arrangement for driving a consumer in a vehicle is suggested. The arrangement has at least two switch elements for influencing the current flow through the consumer. For each switch element, the current flowing through this switch element is monitored and evaluated for detecting a short circuit.

Abstract: A brushless motor includes a stationary member; a rotating member rotatably supported with respect to the stationary member; a stator provided in the stationary member and provided with a stator coil for generating current magnetic field under an exciting state; and a rotor magnet provided in the rotating member for obtaining a revolutionary power due to an electromagnetic mutual effect with the current magnet field of the stator coil. The rotor magnet is formed such that segment-shaped magnets are placed annularly with predetermined gaps circumferentially. The gaps are filled with a magnetic resin material.

Abstract: An exercise machine which can independently vary the force and the speed at the user end is developed. The exercise machine includes a constant torque, variable speed reversible motor, a temperature controlled magnetic particle clutch, a gear reducer, a controller, and a suitable lever mechanism. The motor, clutch and gear reducer are chosen in a combination in order to achieve a predetermined output so that any combination of isotonic, isokinetic, isometric, isotonic/isokinetic, constant, variable, active, passive, uni-directional or bi-directional exercise routines can be performed with the exercise machine. With suitable lever modifications, the resistance providing unit can be successfully modified to emulate a shoulder press, bench press, leg exercise machine, arm exercise machine, etc. The output parameters, user force and user speed, are controlled in real time to maintain accuracy. This is made possible by the use of a PC-based controller interfaced to off-the-shelf motor and clutch control boards.

Abstract: A tool life management system for managing a tool life. The system includes a load torque measuring device for measuring an initial load torque of a spindle attached to a tool during an initial machining operation and for measuring an actual load torque of the spindle attached to the tool during a subsequent actual machining operation, a torque calculating device for calculating a tool wear detection torque based on a reference load torque, and for calculating a tool breakage detection torque based on a tool diameter, the reference load torque being the initial load torque of the spindle, a memory for storing the reference load torque, the tool wear detection torque and the tool breakage detection torque, a torque comparing device for comparing the actual load torque of the spindle with each of the tool wear detection torque and the tool breakage detection torque, and for outputting a result of the comparison, and a tool control device for controlling the tool in accordance with the result of the comparison.

Abstract: For enabling discrimination of whether or not a blower motor is in a locked state to be conducted promptly and reliably irrespective of the motor speed, a blower system comprises a discrimination circuit for discriminating whether or not the blower motor is in a locked state based on change in the position of the rotor of the motor, and the discriminating time period between motor locking and output of a discrimination signal is determined to be shorter for a higher set rotational speed of the motor in response to the speed setting operation of a motor speed setting device.

Abstract: A method and device for controlling the torque of a brushless DC motor used in an electric motorcycle, in which a single current loop is employed to obtain a feedback current by a current detector from a DC bus which simplifies the construction of the circuit scheme. The device of this invention operates by two input signals; one of them is a torque command signal to generate a positive torque of the motor, and the other is brake command signal to generate a negative torque of the motor so as to operate a control brake command and to store the energy generated during a braking operation into a battery of the motorcycle, as well as to stop the rotation of the brushless DC motor within 120.degree. of its electrical angle of reversed rotation.

Abstract: A steering assist system (10) providing assist in response to a steering control signal includes a vehicle speed sensor (56) for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed and a torque sensor (44) operatively connected to a vehicle hand wheel (12) for providing a torque signal indicative of applied steering torque. A blending filter (70, 71) is connected to the torque sensor and provides a blended filtered torque signal having a non-linear characteristic at torque frequencies less than a blending frequency and a linear characteristic at torque frequencies greater than the blending frequency. The blending filter establishing the blending frequency at a value functionally related to vehicle speed. Steering assist motor (28) provides steering assist in response to a control signal. The control signal is provided in response to the blended filtered torque signal.

Abstract: A steering assist system (10) providing assist in response to a steering control signal includes a vehicle speed sensor (56) for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed and a torque sensor (44) operatively connected to a vehicle hand wheel (12) for providing a torque signal indicative of applied steering torque. A controller is connected to the vehicle speed sensor (56) and to the torque sensor (44). The controller includes an adaptive torque filter (80) that maintains a selectable system bandwidth independent of gain changes and vehicle speed changes. The adaptive filter (80) recovers any gain reduction by increasing the frequency of a filter pole.

Abstract: A motor current detection circuit in which a level for detecting an overload state is varied when motor drive voltage varies so as to prevent erroneous detection due to variation in-motor current which occurs when the drive voltage varies.

Abstract: A torque oscillation compensation system and torque estimator that uses torque emulator/observer feedback derived from an electric vehicle motor drive train. The present torque oscillation compensation system is adapted for use with an electric vehicle comprising a source of torque command signals and an electric motor that is controlled by a power switching circuit. The power switching circuit is responsive to the torque command signals and provides pulse width modulated signals for driving the motor. The system comprises a torque estimator that is coupled to received pulse width modulated signals provided by the power switching circuit, and motor currents and speed, for providing estimated torque feedback signals derived therefrom.

Abstract: A method for regulating a motor current in phase windings of a brushless d.c. motor, wherein current is applied to the phase windings individually via an electronically controllable, d.c.-voltage intermediate-circuit converter with switchable semiconductor valves and respective freewheeling diodes connected in parallel with each thereof in individual bridge arms, and an actual value of the motor current is measured exclusively in the d.c.-voltage intermediate circuit, includes switching off, in a motor mode of operation, only one switchable semiconductor valve of the energized bridge arms for a period of time dependent upon the rotational speed of the motor when a reference value of the motor current is reached.

Abstract: A control system for an electric vehicle comprises a motor speed detector and a sensor for detecting an accelerator angle and outputting a motor speed error command based on the difference between motor speed and a speed required by the present accelerator angle. A motor speed command is generated based on the error command and the detected motor speed. A feedback control portion outputs a torque command based on the motor speed command and the detected motor speed and the driving force of the motor is controlled based on the torque command.

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: Control method and apparatus for a moveable control member with n observed states, the apparatus incorporating a sliding mode control system, operable to maintain the state point of the moveable member on a predetermined hyperplane having n-1 dimensions, and comprising digital processor means operable to reference, at a first frequency, n-1 low order observed states to the predetermined hyperplane to establish a desired value of the highest order observed state, the control system further comprising comparator means operable to compare, at a second frequency, said desired value with the observed highest order state, the first frequency being less than the second frequency, and means responsive to the comparator means and operable to implement the control action necessary to maintain the state point on the predetermined hyperplane.

Abstract: A method for assisting the steering forces to be produced in a vehicle by means of an electric motor acting on the steering column is proposed. This method is characterized in that the additional torque produced by the electric motor is controlled in dependence upon the steering torque to be produced for actuating the steering and upon the steering torque supplied overall. The additional torque is thus dependent on the torque which is produced at the steering wheel by the driver and, in addition, on the torque which is supplied by the steering arrangement on the wheels to be steered. The electric motor is controlled by a controller 5 via an actuator 6, an additional torque M*.sub.R, which is dependent on the vehicle speed, being input into the controller. As characteristic shaper, the controller has a dead-time element by which the control intervenes only from a certain limit value of the torque M*.sub.R input into the controller 5.

Abstract: Apparatus for fitting a motor vehicle tire on a disc wheel comprises a tire fitting tool mounted rotatably about an axis, an electric drive motor to drive the tire fitting tool about the axis, a current supply means for the drive motor, and a torque limiting means to terminate the rotary drive to the motor when a predetermined torque transmitted to the tire fitting tool is exceeded, thereby to protect the tire from overloading in the fitting operation.

Abstract: A motor control for a multi-phase compressor motor. The control responds to a speed control signal to cause the motor speed to track the speed control signal without changing the motor torque. This is accomplished by pulse width modulating motor speed signals in a sinusoidal manner to maintain the volts/hertz applied to the motor constant regardless of motor speed.

Abstract: A motor control circuit for controlling supply of electric power from a power source to an electric motor, in particular for use in electric power tools, comprising: an output power device for controlling supply of current to the motor according to a duty ratio of a control input signal supplied thereto; current detecting means for detecting an amplitude of an electric current supplied to the electric motor; and feedback means for supplying the control input signal to the output power device, the duty ratio of the input control signal being increased with an increase in the electric current supplied to the electric motor as detected by the current detecting means. Since the torque otuput of the motor is increased when such a need arises, the need for more a complex and expensive continually variable speed control system is eliminated.