Abstract: An SCR bridge of an elevator speed control apparatus is connected between an induction motor 5 and two (R, S) of the three-phase power supply terminals. Two diagonally opposite legs of the bridge comprise single SCR's 25, 26, and the other two legs each comprise a pair of parallel, reverse polarity SCR's 21, 22; 23, 24. The third power supply terminal is connected directly to the motor through a single switch contact 8. By appropriately controlling the switch contact and the SCR.varies.s in accordance with the difference between the actual and commanded elevator speeds, the bridge can be configured to implement three phase running during acceleration and constant speed modes, single phase running during a transitional slow down mode, and D.C. braking during a deceleration mode.

Abstract: A driving and braking system having solid state switches for use with an electric motor. A first switch in series with a motor armature carries current from a power supply to the motor during the driving operation. A second switch couples a voltage from the motor armature to the first switch to render the first switch nonconductive and place the motor in a braking mode in response to a braking signal. The first switch provides armature current and couples a voltage from the motor armature to the second switch to render the second switch nonconductive and place the motor in a driving mode in response to a driving signal. The motor can be switched between the braking mode and the driving mode without bringing the motor to a stop.

Abstract: A control circuit for a DC capstan motor used for driving a tape having control signals thereon is adapted for accurate stopping of the tape during intermittent-motion operation. A frequency generator coupled to the motor generates a frequency signal whose frequency is proportional to the motor's speed. A position signal generating circuit generates a position value that increments by steps upon occurrences of the frequency signal. A clamp circuit clamps the position value to a clamping level upon detection of the control signals. A brake start signal generator provides a brake start pulse signal when the position value exceeds a predetermined threshold, and this brake start pulse signal is used to commence braking of the motor. In order to permit accurate stopping in both forward and reverse directions, the clamping circuit provides one clamping level when a forward mode is selected and another clamping level when a reverse mode is selected.

Abstract: A power fail circuit provides protection for tape such as used in the tape transport apparatus of a video recorder in the event of a failure of the external power supply. The tape transport apparatus includes as a feature the provision of an electrical error signal used to govern drive motors to maintain substantially constant tape tension when the system is operating normally. After power failure occurs, the power fail circuit continues to respond to the error signal by coupling current from the drive motors to provide dynamic braking. Further, current taken from the drive motors selectively is coupled to an energy storage device operatively associated with the system power supply, to provide augmenting energy from the kinetic energy of the motors for continued control of the power fail circuit as the drive motors are caused to decelerate under control to stop.

Abstract: An electrical braking control circuit for use in a control system for a direct current traction motor which may be employed, for example, to propel an electrically driven vehicle. The electrical braking controller of the invention initiates electrical braking in a plug mode of braking and then, when conditions are suitable for regenerative braking, causes a transition to regenerative braking, followed by return to a plug mode of braking whenever regenerative braking can no longer be efficiently achieved, all of which is carried out smoothly and efficiently without unduly wasting regenerative power.

Abstract: A motor control apparatus operative with a voltage source and including thyristor switch devices arranged in a bridge circuit for selectively determining forward and reverse operation of a DC series motor coupled with a vehicle, said control apparatus having provision for regenerative braking of the motor to provide current back into the voltage source.

Abstract: A plug current regulator for a dc electric traction motor propelled vehicle, implemented using a microcomputer for controlling a time-ratio switching regulator, provides a substantially smooth electrical braking function by applying relatively short time duration current pulses to build up braking current, followed by a relatively long time duration in which current pulses are inhibited. Current regulation is provided by comparing motor current to a desired braking current and generating an update signal when actual current drops below desired current. Filtering is minimized by sampling motor current at a time interval occurring relatively long after a current pulse is supplied to the motor.

Abstract: A stop control circuit for a DC motor causes the motor to stop precisely by purely electrical action. A DC motor is provided with a bidirectional driving circuit, a servo circuit for controlling the driving circuit, and a rotation detector associated with the motor shaft to provide a phase signal that depends, in magnitude and polarity, on the particular rotational angle of the shaft, regardless whether the motor is turning. A stop control circuit then includes an amplifier whose output varies according to the phase signal, and a switch that normally provides the servo signal to the driving circuit, but, upon command, switches over to provide thereto the output of the amplifier as a brake signal. Alternatively the rotation detector can include two sensor elements separated by .pi./2, and the stop control circuit can include an inverting amplifier, a non-inverting amplifier coupled to one of the sensor elements, and a switch circuit with inputs coupled respectively to these amplifiers.

Abstract: A DC motor control apparatus is disclosed comprising a first pair of switching elements coupled respectively with oppositely poled ends of the DC motor. A first actuating means is provided for actuating one of a first pair of switching elements in response to an input signal of a first predetermined logic content. The other of the first pair of switching elements is provided to respond to an input signal of a second predetermined logic content. Also provided, are means for applying a driving potential to the oppositely poled end of a motor simultaneously with the actuation of each of the first pair of switching elements, thereby establishing a current path for forward direction and reverse direction operation of said DC motor, respectively. A second pair of switching elements are respectively connected to oppositely poled ends of the DC motor.

Abstract: A rotation stopping apparatus for a motor comprises a frequency signal generating circuit for generating a signal having a frequency according to a rotational speed of a motor, a voltage forming circuit for forming a voltage according to the frequency of the frequency signal from the frequency signal generating circuit, a motor driving circuit for supplying a forward direction current to the motor upon rotation of the motor and supplying a reverse direction current to the motor when the rotation of the motor is stopped to perform a damping operation with respect to the rotation of the motor, a detecting circuit for detecting that a voltage from the voltage forming circuit has become below a predetermined threshold voltage, and an interrupting circuit for interrupting the supply of the reverse direction current to the motor by the motor driving circuit according to the detected result obtained from the detecting circuit.

Abstract: A reversible electric drive with bidirectional back-current brakes fed by a rectifier supplied from a pair of A.C. power lines for a D.C. motor having two directions of rotation and two poles, comprises a control rectifier bridge for each direction of rotation, each bridge having two branches each containing a diode which is common to both bridges, a shunt resistor for each direction of rotation which is identical with a braking resistor for each other direction of rotation connected in series with the motor for each bridge, each bridge having two other branches each containing a rectifier thyristor with cathodes of each rectifier thyristor connected to a common point. The common point of each bridge is connected to one of the poles of the motor with a control thyristor connected to each common point in series with each respective shunt resistor of each bridge and connected to each other by a connecting point.

Abstract: An electric vehicle control device is disclosed which includes a main circuit for supplying power from a d.c. power supply to a driving motor through a chopper, a phase shifter for controlling the conduction ratio of the chopper in such a manner that a current flowing through the driving motor is proportional to an instruction value determined by how much an accelerator pedal is trodden, a circuit for instructing a regenerative braking operation, and a changeover switch for changing over the main circuit between a power running state and a regenerative braking state. The changeover switch is changed over in the regenerative braking state when another power running state in the direction opposite to the current running direction is instructed in a predetermined time after the stop of a power running state where the chopper had a conduction ratio greater than a preset value.

Abstract: A feature of this invention is the provision of a reversible, D.C. shunt field motor having an armature and two separate field windings, each field winding being capable of producing rated field flux. The motor is capable of bidirectional rotation having one field energizable for CW rotation and the other field energizable for CCW rotation. A servo system couples the two field windings and has only one active control element in the high current armature circuit to control the magnitude of the armature current, and two low power amplifiers, each low power amplifier having an active control element and each controlling the magnitude of the field flux (and thereby the magnitude of armature current under certain circumstances) in a given respective direction.

Abstract: A digital servo control system for a d.c. motor to achieve stepping motor precision and a wider speed control range than either a conventional d.c. motor or a stepping motor, as may be typically utilized in an IV syringe pump. Motor position and direction sensing, as well as motor advance signals at the desired motor rate, condition motor advance and retard logic which, in turn, effects a unique counter-controlled motor drive subsystem to cause the d.c. motor to move forward, reverse, coast or slow down over a 1,000 to 1 speed control range.

Abstract: A low cost power control circuit which achieves variable speed, quasi four-quadrant motor control well suited to the requirements of a direct drive clothes washing machine. For handling relatively low frequency motor direction control signals (one or two Hertz), four relatively inexpensive, low frequency thyristors are employed in a four-leg bridge circuit arrangement. For handling relatively high frequency chopper duty cycle control signals (10 kHz), a single high frequency power transistor is employed. To provide quasi four-quadrant control entirely suitable for clothes washing, a fifth thyristor and a series dissipation resistor are connected across the motor terminals and switched ON during agitation just prior to each motor reversal when motor velocity is decreasing and motor back emf exceeds applied emf. A feedback servomechanism is employed to control motor rotational velocity via chopper pulse width modulation.

Abstract: A direct-current motor is energized through a diode in the emitter-base network of a transistor and through the emitter-collector network of another transistor which is held conductive by the driving current but which automatically limits the current flow through the motor. When the circuit is de-energized, a self-braking effect is established by the circuit which is substantially symmetrical for reversing operation of the motor.

Abstract: Improved logic circuitry combined with an efficient and economical motor controller which enables a DC motor to reverse the direction of a vehicle and to maintain the speed of the vehicle within narrow speed boundaries during acceleration, deceleration and constant speed conditions.

Abstract: A direct current motor control circuit in which the armature is arranged for reversible connection in a main path for current to flow from a first supply terminal to a second supply terminal through the armature and a current chopper. A pair of switches between which the armature is connected are controllable to effect this reversible connection in the drive mode and to connect the armature across a bridge to permit return current to flow from the second terminal, in either direction through the armature toward the chopper in a regenerative mode, one or more diodes being provided for completing a return path for the return current to flow to the first terminal.

Abstract: A door operator includes a motor-driven mechanism to move a door between an open position and a closed position in response to activation of an improved control circuit. The improved control circuit includes circuitry to initialize the sequence of operation of the motor upon connection of power after installation of the door operator or upon restoration of power after a power outage. Obstruction detection circuitry is also included in the control circuit to stop or reverse the motor if the door encounters an obstacle during movement between the open and closed positions. Time delay circuitry cooperates with the obstruction detection circuitry so as to prevent stopping or reversing the motor due to the inertia of the door and of the drive mechanism as the door starts to open or close upon activation of the control circuit. During the time delay period, however, further manual activation of the control circuit is operative to stop and/or reverse movement of the door.

Abstract: A single pickup head generates an alternating signal proportional to the rotational speed of a DC motor which can be rotated in either of two directions, and such alternating signal is employed by speed and/or phase control circuits to control the motor speed relative to a reference speed in a selected one of the two directions. An overspeed sensing circuit detects speed runaway, which can occur when the motor is rapidly rotated in the direction opposite to the selected direction, and the overspeed sensing circuit then interrupts the motor drive voltage until the motor speed decreases to below its normal speed. At and below normal speed in the undesired direction, the normal torque acts in the selected direction to rapidly reverse the direction and to accelerate the motor to normal speed in the selected direction.

Abstract: The normally provided manually operable switch lever on an electrically drive wheelchair incorporates pairs of switch arms so that additional circuitry can be provided for interconnection with the normally provided left and right wheel drive motors. This additional circuitry comprises electrical resistances arranged to be connected across the motor leads by the manually operable switch when in an unactuated position for the particular motor in question. The provision of these resistances across the motor leads when the motors are unenergized results in absorption of back voltage spikes to thereby avoid burning out the switch means, dynamic braking when the motors acts as generators as a result of the wheelchair coasting, easier steering control when only one of the motors is energized to effect a turn, and permits the use of permanent magnet type d.c. motors for the left and right wheel drive motors.

Abstract: The pressing machine includes a pressing ram, a drive arrangement for moving the ram from a starting position to an end-of-stroke position and back to the starting position and includes an electric drive motor. A control arrangement establishes the end-of-stroke position for the ram. The control arrangement includes a direction-reversing circuit connected to the drive arrangement for reversing the direction in which the drive arrangement moves the ram and includes a direction-reversing relay arrangement having a current path for activating current. A controllable electronic switch is connected to the activating current path for controlling the activation of the direction-reversing relay arrangement. A control-signal-generating circuit controls the conductivity of the electronic switch by generating and applying to the control input of the electronic switch a control signal dependent at least upon the loading of the drive motor.

Abstract: A control circuit for an electrically driven vehicle which employs a separately excited motor. The armature is connected in series with a current control between two supply rails. The field winding is likewise connected between the rails, but has associated with it switch means for reversing the connection of the field winding. A diode arrangement is provided for recirculating current when the field circuit is interrupted and for establishing a recirculating path through the vehicle battery when the field connections are reversed, by the switch means.

Abstract: A regenerative motor control of the field reversing type includes an input amplifier, a field circuit for energizing the motor field, and an armature circuit for energizing the motor armature. An improved means for coordinating the operation of the field and armature circuit is operable in accordance with the magnitude and polarity of the field current for limiting the magnitude of the amplifier output signal and the armature current during portions of the transient period and under weak field conditions. During normal operation the armature circuit is not so restricted.

Abstract: A control circuit for an electrically driven vehicle has contactors for determining the direction of operation of the motor, but these contactors cannot be operated until the current flowing through the motor is below a predetermined level.

Abstract: An electrode feed motor control circuit for an automatic electric arc welder which gives improved starting. For cold starts, the electrode feed motor is instantaneously braked when the electrode first contacts the workpiece so that the electrode is lightly touching the workpiece and the electrode motor field is energized for pull back preparatory to the weld start. For hot and cold starts, the motor speed more rapidly responds to transitional meltoff requirements. The motor speed is automatically limited until the arc is fully established.

Abstract: In an electric propulsion control system for self-propelled traction vehicles having reversible, variable speed tractiOn motors, wherein the operation of a direction selector means overrides the normal speed controlling means and initiates a dynamic retardation operating mode so as automatically to decrease the speed of the traction motors, and means responsive to the motors subsequently decelerating to a predetermined relatively slow speed effects a reversal of motor energization so as to reverse the direction of the vehicle.

Abstract: A method and apparatus for sensing plugging of a DC electric motor comprising logic circuitry responsive to a direction change command for initiating a plugging signal and additional logic circuitry for maintaining said plugging signal as a function of the percentage on time of a variable time ratio switch supplying power to the motor. Inhibit circuitry is provided to override the plugging signal under operator selected conditions.

Abstract: A system for controlling a direct current series motor for driving an electric vehicle wherein a brake switch and an interlocking means prevent energization of the motor under certain conditions. The brake switch functions as a dead man's control to render the system inoperative whenever the operator leaves the vehicle unattended. If a direction controlling switch was previously left in a forward or reverse position, the interlocking means requires that the direction controlling switch be returned to a neutral position and then set in the desired forward or reverse position before energization of the motor occurs. The interlocking means, by necessitating return of the direction controlling switch to the neutral position before permitting energization of the motor, prevents the vehicle from moving unexpectedly in an undesired direction or at an excessive or dangerous rate of acceleration.

Abstract: A control circuit for an electrically driven vehicles has a traction motor the armature of which can be connected between positive and negative supplies lines in either sense to drive the vehicle in either direction. Also, the armature is connected through a diode to one of the supply lines to permit electrical braking.