Abstract: A digitally controlled rectifying system used for driving a d.c. motor through antiparallel connected forward and reverse converters. The firing phase angle of the converters is shifted by 180.degree. at a time of gate switching operation for the converters so that the load current is formed to become zero, and after the gate switching operation the firing phase angle is shifted to a position at which the load current is substantially zero, whereby the time lag of control occurring at the switching operation of the converters can be minimized irrespective of the load condition.

Abstract: A special control circuit for a golf cart or like vehicle powered by a plurality of storage batteries. The batteries are connected circuitwise to a DC motor by speed control contactors to select battery connections in parallel, parallel/series and series for motor speed control. The speed control contactors are arranged so that their solenoids are de-energized at series battery connection and in parallel battery connection charges are normalized across the batteries. Moreover, the circuit provides different sets of parallel/series batteries for intermediate speed to equalize battery change levels. A safety circuit feature prevents the motor in reverse directional operation from being shifted from the low speed settings. Discharge of any battery below minimum operating voltage de-energizes the solenoids of the contactors to stop the vehicle.

Abstract: In a motor control system for a DC motor, a modulation circuit provides a plurality of pulse width modulated signals to control the current applied to the motor. The motor is coupled to a current sensing resistor and a plurality of switches responsive to the pulse width modulated control signals. The output of the current sensing resistor is summed with an input current command to provide an error signal. A modulation circuit which includes a waveform generator generates a plurality of interposed triangular waves adjustably offset by a predetermined amount. The triangular waves are compared to the error signal to provide pulse width modulated control signals which cause a "dither" current to be applied to the motor when there is substantially no input command and currents having substantially decreasing form factors to be applied as the input command increases.

Abstract: The trackside control includes a trackside d.c. power supply applied initially at low voltage (of selectable polarity, to determine the direction of vehicle motion along the track) and then increased (preferably with constant voltage-increase rate) to maximum supply voltage, and a trackside electrical braking load (preferably capable of forcing down at constant rate the voltage applied to it from the vehicle motor).The motor has series and (separately excited) shunt field windings, and on-board sensing and switching circuitry which (a) in motoring, either forward or reverse, sets full series field in flux addition to limited shunt field (b) in coasting, maintains field winding switch settings, and (c) in electrical braking, sets full shunt field and reduces the now decompounding series field.

Abstract: The disclosure provides an electronic motor control circuit which switches and amplifies to control a bi-directional electric motor, using a symmetrical circuit, each half of which consists of five transistors. The circuit has a logic level input and motor driving power output using, for control in each direction: an input transistor; a control transistor turned on and off by the input transistor; two matched, complementary motor drive transistors (at opposite terminals of the motor) turned on and off simultaneously by the control transistor; and a lockout transistor, also actuated by the control transistor, which is operatively connected to one of the motor drive transistors in the other half of the system to prevent short circuiting.

Abstract: Herein disclosed is a drive system for a servomotor for use with the carriage of a serial printer, comprising a source of a variable command signal representative of the speed at which the servomotor is to operate, detecting means for detecting the output speed of the servomotor and producing a signal representative of the detected servomotor output speed, and first and second voltage sources respectively operative to supply predetermined voltages, the voltage from the first voltage source being higher than the voltage from the second voltage source.

Abstract: By using the fly-wheel current effectively, the d.c. servo motor current can be rapidly decreased when the circuit becomes non-driving state or the driving polarity is changed, and the inexpensive circuit of the high performance driving circuit, in which the form factor of the driving signal is improved, can be obtained.

Abstract: A frequency-voltage converting system has a first sampler for sampling the input signal at a predetermined time interval, a second sampler for sampling the input signal after elapse of a predetermined time period from said predetermined sampling time, and comparator for comparing the sampled values obtained respectively from said first and second samplers and providing the difference of said sampled values as a value proportional to the frequency of said input signal.

Abstract: A control circuit for use in controlling both the speed and direction of an AC energized DC motor in a linear relationship to the magnitude and polarity of a DC reference signal. This is accomplished with a triggerable bidirectional current conducting device, such as a triac, which is connected in series with a DC motor across an AC power supply source. A control circuit serves to trigger the bidirectional current conducting device into conduction at a selected firing angle during the positive or negative half cycle of the AC source in such a way that the firing angle is linearly related to the magnitude and polarity of a DC reference signal.

Abstract: The specification discloses a two-directional switched driver for use either independently or in a method of controlling production processes and apparatus therefor. The driver, whether used independently or in a process controller, utilizes polarity signals and a retriggerable timer to produce separate forward and reverse output signals which may be used to drive reversible motors or two-directional actuators by way of standard switching techniques. Examples of such uses are the use of most any reversible motor, or two-directional actuators to control mechanical, pneumatic or hydraulic circuits, such actuators operated by the driver may be rotational or non-rotational in nature.

Abstract: The regulation range of a conventional bang-bang current regulator is extended by altering the current command or feedback signals to cause the feedback signal to exceed the command signal sooner in time than it otherwise would and fall below the command signal later in time than it otherwise would. For relatively low command signal values, the current is regulated in a discontinuous series of reduced peak excursion pulses, enabling the average value of current to be regulated down to a lower value than possible without the alteration.

Abstract: In this control box, a first switching device (R-1) is actuated when the operator acts on a selector (1) whereby he can choose, on one hand, the direction of the driving of the motor (9) and, on the other hand, by means of a brief or prolonged action, the driving speed of this motor. If the action is prolonged, the switching device (R-1) is inhibited by a second switching device (R-2) controlled by a timing circuit (27) which was initiated at the start of the action. This second switching device then supplies power to the motor (9) through a series resistor (18) so long as the selector (1) is actuated. Application in an electric window raiser of an automobile vehicle.

Abstract: A MOSFET "H" switch circuit for providing bidirectional control to a DC motor. The power MOSFET's employed have significant advantages over bipolar and darlington power transistors and allow for microcomputer interfacing for providing bidirectional rotational control as well as motor speed control by pulse width modulation.

Abstract: An elevator system including an elevator car and a drive machine having a DC drive motor, a dual converter, and a phase controller for providing gate drive signals for the dual converter. A reference signal relates to the desired motor armature current is developed in response to the operation of the elevator system. The reference signal indicates when the current source should be switched from one converter bank to the other converter bank. The switching is accomplished by a method which includes retarding the firing angle of the gate drive signals applied to the operative converter, until current is extinguished, applying the gate drive signals to the other converter bank, and advancing the firing angle towards rectification to initiate current flow in the on-coming converter. The rate at which the firing angle is advanced towards rectification is a function of the control signal.

Abstract: A circuit for controlling a ceiling-type fan includes a switch or relay for controlling the fan, connectable to the fan. A logic circuit produces an output signal for controlling the switch or relay from an input signal generated by momentarily interrupting the power applied to an input to the logic circuit. A diode and capacitor isolate the power supply connections of the circuit to maintain the supply voltage during the momentary power interruptions.In one embodiment the control circuit controls the on-and-off switching of the fan, as well as its speed, together with on-and-off switching of a light associated with the fan. In one embodiment the forward and reverse directions of the fan are controlled as well.

Abstract: A method and apparatus for controlling the rotational speed of an electronically controlled power tool in both the forward and reverse direction. When the reversing switch is placed in the reverse direction, the electronic speed control circuit automatically limits the speed of the motor to a predetermined maximum value. The speed control circuit also is adapted to sense a change in the state of the reversing switch and remove power to the motor until it coasts down to a relatively slow speed or to zero before reapplying power in the opposite direction. The speed control circuit monitors the rotational speed of the motor by means of a tachogenerator comprising a ring magnet mounted on the rearward end of the rotor shaft of the motor outboard of the commutator-end bearings and a Hall effect device mounted to the peripheral flange of a carrier which encircles the ring magnet so that the ring magnet and Hall effect device are separated by a small radially extending gap.

Abstract: A mechanism for controlling the speed and direction of a self-propelled machine, such as, for example, a floor cleaning machine, or the like. A rotatable control handle is provided and includes a speed control cam which moves a variable resistor slide member by means of a speed control arm connected to the cam follower. The variable resistor is connected between a battery power source and a propulsion motor to control the voltage to a speed control. The handle has a neutral position at which the machine is stationary, and rotation of the handle about its own axis in either direction will cause the motor to move the machine, the direction of rotation determining the direction of movement. The control handle carries a series of direction control cams which operate switches to control the direction of flow of current to the motor and thereby the direction in which the machine moves.

Abstract: A transistor having an emitter collector path connected in series with a d.c. power supply and a d.c. motor that derives a back emf as a function of motor speed is controlled so current selectively flows from the power supply through the transistor emitter collector path to the motor to drive the motor at differing speeds. The back emf of the motor has a tendency to become excessive for the transistor emitter collector path as the motor speed increases. The voltage of the supply is increased as the back emf increases to prevent the back emf from becoming excessive for the emitter collector path. A control source for the back emf is programmed in accordance with known speed and back emf characteristics of the motor as a function of time. The power supply voltage is increased and decreased in steps in response to variations of the programmed control source being above or below a threshold.

Abstract: A direction reversing apparatus for a rotary motor of a microcassette tape transport includes a motor (14) having substantially the same characteristic for the forward and reverse motor rotation directions for driving a recording tape, and a motor controller (12) for setting a motor speed to a given speed. The reversing apparatus further includes a switch (16) coupled between the motor (14) and the motor controller (12) for reversing the direction of rotation of the motor (14).

Abstract: An H-switch driver circuit includes two pairs of opposed drive transistors each pair being selectively energized to control the polarity of power applied to a load. Each pair of transistors is energized by a power current mirror that includes an NPN transistor that supplies base drive current to the remaining transistors in the power current mirror. The emitter of the NPN transistor is coupled to the load. The NPN transistor is biased off to inhibit base drive current to the circuit transistors in the event of a short to plus fault at one of the load terminals.

Abstract: An electronic control system for controlling the operation of electromotive apparatus utilizes a capacitive sensor for sensing human touch and producing a command signal whose magnitude corresponds to the contact area of the contact. The sensor command signal is applied to an oscillator which produces a series of output width pulses having a frequency corresponding with the magnitude of the sensor command signal. A discriminator detects the trailing edge of the oscillator pulses and produces a series of fixed width pulses and an integrator produces a D.C. voltage signal corresponding to the discriminator output, which voltage signal corresponds to the area in proximity to and thereby stimulated by the human body. A comparator is employed to produce a pulse-width modulated rectangular pulse output whose duty cycle corresponds to the integrator D.C. voltage by comparing the integrator D.C. voltage with a reference triangular waveform.

Abstract: An antenna control system employing a d.c. motor for extending and retracting a telescoping antenna for use on a vehicle. The control system comprises a polarity responsive timer, a polarity reversal switch, and a switching device. In one position of the switching device, a d.c. voltage of a polarity determined by the position of the polarity reversal switch is connected across the motor for an interval of time determined by the timer to extend or retract the antenna. In the other position of the switch, the vehicle operator controls the motor and therefore the antenna position.

Abstract: A system for controlling rotational direction switchover and for variably controlling the rotational speed of a motor comprises a circuit for switching over the rotational direction of the motor, a circuit for supplying rotation driving voltage to the motor thereby to drive it at a speed depending on the rotation driving voltage, a single voltage varying unit for varying voltage continuously, and a control signal generation circuit which receives variable voltage from the voltage varying means to generate a rotational control signal for the rotation driving voltage supplying circuit and further to generate a rotational direction switchover control signal for the switchover circuit. The voltage of the rotation control signal produced by the control signal generation circuit decreasing as the variable voltage approaches a predetermined value, reaching a minimum when the variable voltage coincides with the predetermined voltage, and increasing as the variable voltage goes beyond the predetermined value.

Abstract: The polarity of the desired speed voltage of a speed control device and the commutation sequence of the current flowing in the stator windings are reversed for reversing an electronically commutated D.C. motor. A voltage, proportional to the EMF ad obtained from the motor voltage by I.times.R compensation, is used as the actual speed voltage for the speed control device, the polarity of the voltage proportional to the EMF being reversed when the direction of rotation signal changes.

Abstract: A vehicle power seat adjuster control system that provides for the pulsed reversal of rotation of the armature of the operating motor of a vehicle power seat adjuster mechanism each time the operating motor is deenergized at the conclusion of each seat adjusting operation.

Abstract: Converter apparatus including a power converter having controlled rectifier devices connected, and gated in a predetermined sequence, to interchange electrical power between a source of alternating potential and a direct current load circuit, a phase controller for controlling the conduction angle of the controlled rectifier devices, and circuitry for maintaining synchronous operation between the phase controller and the power converter. The circuitry for maintaining synchronous operation constrains the conduction angle between predetermined end stops by logically combining first and second logic signals developed for each controlled rectifier device from the source of alternating potential, with a logic signal associated with the immediately preceding controlled rectifier device in the gating sequence.

Abstract: A motor control system for controlling the speed and direction at which a motor operates. A drive circuit is provided for supplying a drive current to the motor, the magnitude of the drive current being determinative of the speed at which the motor operates. A direction-determining circuit determines the direction at which the motor operates and, for example, may comprise a steering circuit for steering the drive current to the motor in first and second current paths. A potentiometer having a resistance connected between first and second terminals and an adjustable wiper which is settable along the resistance is used to determine the desired speed and direction of operation of the motor. The setting of the wiper includes a predetermined zero speed setting which, preferably, is at some intermediate point along the resistance. A power supply having a power terminal and a reference terminal produces an operating potential across these terminals.

Abstract: A motor circuit of a tape recorder comprises a mechanical switch in which a movable contact is connected to a first contact in response to the depression of a recording or reproduction button, and also to a second contact in response to the depression of a fast feeding or rewinding button. A motor control circuit is connected to a D.C. power source through the first contact of the mechanical switch to provide a motor speed suitable for the recording or reproduction. An output terminal of a constant voltage circuit connected to the D.C. power source is connected to the motor through a switching transistor. The switching transistor is rendered conducting in response to the closing of the second contact of the mechanical switch, causing an output from the constant voltage circuit to be supplied to the motor to rotate the motor at a high speed suitable for the fast feeding or rewinding.

Abstract: An improved hoist control system wherein a D.C. motor is employed to drive the hoist, and a remote hand-held control is utilized to vary the motor speed and direction of rotation. The hand control comprises an A.C. to D.C. variable transformer which is controllable by a trigger mechanism, a three-pole double throw switch for up-off-down control of the motor, circuit on-off switches, a meter for reading the hoist load, and an interlock device for limiting the actuation of the motor control switch if the trigger is depressed.

Abstract: A linear servo circuit for A.C. motors is disclosed. The servo circuitry is used in a magnetic tape transport to control the motor which operates a tape reel on which the magnetic tape is stored. The servo circuitry develops two complimentary saw-tooth voltage waveforms synchronized to the sinusoidal A.C. line voltage. One saw-tooth waveform is used to control the motor in the forward direction and the other saw-tooth waveform is used to control the motor in the reverse direction. Comparator circuitry compares the saw-tooth waveforms to a D.C. control voltage which is proportional to the angular position of an arm that controls the tension of the magnetic tape. The comparator circuitry provides a control pulse to a photodiode when the saw-tooth waveform exceeds the D.C. control voltage. Light pulses from the photodiode impinge on a light sensitive SCR which in turn triggers a triac to apply power in the forward or reverse direction to the A.C. tape reel motor.

Abstract: An industrial robot for spray painting workpieces carried by a conveyor is provided with a control to allow the programmed robot sequence to proceed synchronously with conveyor movement so long as the conveyor maintains a normal speed. When, however, the conveyor stops, the control maintains robot operation until the spray gun is moved to a safe stopping place to avoid excessive paint application to a portion of a workpiece. Upon conveyor start-up, the robot remains stationary until the workpiece approaches normal speed and moves into a position synchronous with the robot position.

Abstract: Variable pulsing of a dc source without change of polarity is used for lossless control of the speed of a compound dc motor. The pulsed dc supply is fed in series through the series field winding, armature and reversing switch system and the shunt field winding has one terminal connected to the pulsed dc source and its other terminal connected respectively through two conductively poled diodes to the opposite terminals of the armature winding. Two anti-kickback devices are also provided, one of which operates during reverse-current braking. The reversing switch system has two independently actuatable single-pole double-throw switches of which the respective arm contacts are connected to the ends of the armature winding, one fixed contact of each of these reversing switches being connected to the series field winding and the other pair, likewise connected together, being connected to one terminal of the dc supply.

Abstract: Electrically operable switching circuitry is effective to energize, in response to the application of a control signal, a commutated electrical motor in a first direction for driving a member driven thereby through a travel stroke and to energize, in response to the removal of the control signal, the motor in a second direction for driving the member driven thereby through another opposite travel stroke and an electrical signal produced while the motor is in the run mode is effective to maintain the switching circuitry operated for motor energization. Upon motor stall when the member driven thereby has reached the end of a travel stroke, the electrical signal produced while the motor is in the "Run" mode terminates and the switching circuitry then operates to deenergize the motor.

Abstract: A control circuit for use with a shuttle car used in mining operations and circuitry associated therewith. The control circuit generally comprises a chopper circuit in series with a reversing circuit and a traction motor which drives the shuttle car. The chopper circuit essentially comprises two separate current paths each through a separate set of silicon controlled rectifiers or SCRs and a common capacitor. A logic circuit controlled by the operator alternately gates the sets of SCRs thereby placing voltage across the traction motor. The magnitude of this voltage and hence the speed of the motor are directly proportional to the frequency of the gating pulses. The reversing section also employs two sets of SCRs and a common field inductance. The operator, through the logic circuit, triggers one set of SCRs and current flows through the field inductance in a forward direction causing the traction motor to operate in a forward mode.

Abstract: Disclosed is a device for electronic direction control of trolling motors for maneuvering boats. The device includes a power supply, a steering mechanism including a motor for altering the direction of the trolling motor thrust, a direction control for generating a signal proportional to the desired direction of trolling motor thrust, and a direction sensor for generating a signal proportional to the actual direction of trolling motor thrust. Two electronic circuits are provided to process the desired and actual direction signals. The first circuit provides a pulse width modulated output signal which variably controls the angular velocity of the steering mechanism by controlling the operational state of a switching circuit having at least one transistor and thereby controlling the flow of current to the steering motor.

Abstract: A DC motor phase control system is provided in a system having a first controlled rectifier connected to an AC power supply and providing a positive rectified output and a second controlled rectifier providing a negative rectified output. A DC motor is controlled for forward and reverse rotation and is controlled in speed by the firing control of the rectifiers. The pulse indicating the zero point of the AC power supply voltage is delayed according to the actual speed of the motor and the delayed pulse is used as a reference pulse of the controlled firing pulses applied to the controlled rectifiers.

Abstract: A control box is provided having a control shaft which projects from the box and is adapted to be connected, directly or by linkage, to the accelerator pedal of a battery-operated motor vehicle. Connected to the inward end of the control shaft is the movable arm of a potentiometer which is moved angularly to change the circuit resistance when the accelerator pedal is depressed. Mounted on the control shaft are a pair of cams, the followers rollers of which actuate a pair of microswitches which control a solid-state control system which controls the current delivered by the battery to the traction motor of the vehicle.

Abstract: A reel motor drive system using a first and a second signal for comparing an error signal derived from a tape tension sensing transducer with a respective polarity of separate positive and negative repetitive ramp signals. Each comparator produces an output signal as a series of constant frequency, duty cycle modulated pulses having a duration equal to the time that the error signal is greater than the ramp signal being compared thereto. These pulses are used as drive signals to a reel motor through a motor power amplifier and are used to develop mutually exclusive steering signals for selecting a motor drive direction by means of a steering logic circuit. The steering signals are also applied to the motor power amplifier to select a current path through the reel motor corresponding to the desired motor drive direction.

Abstract: A simple and economical system for operating a dc. motor of the permanent magnet field type from an ac. supply, characterized in that the motor may be driven at an adjustable speed in a forward direction by energization through a controlled half wave rectifier (e.g., SCR) or at a fixed, high speed in the reverse direction by energization through a half wave diode rectifier.

Abstract: A threading and/or tapping device has a housing including a tubular portion and a chamber portion that provides a shelf for a motor. A shaft rotatably connected to a slide within the tubular portion extends downwardly through the chamber portion with a tool holder on its exposed end. The slide is movable by the operator to advance and retract the shaft and a gear train within the chamber includes a drive gear on the motor shaft and a driven gear through the axis of which the tool holder shaft extends to rotate therewith and to slide relative thereto as the operator advances or retracts the shaft. The housing includes means for detachably attaching it with the work holder shaft either normal to or axially aligned with a support.

Abstract: A pulse width modulated motor control system in which the power supplies for forward and reverse operation for the motor are provided to supply electric energy at different levels. The control signals for the motor are provided in such a manner that the average energy of unbalanced pulse periods is the same, but the potential level differs by a substantial amount. Energy storage may be provided for in conjunction with the lesser of the two power supplies to assist in a rapid reversal, stop or shaft positioning of the motor.

Abstract: Apparatus to control the direction of movement of a mechanism over a surface. The surface is provided with a plurality of substantially parallel strips of conductive material alternately connected to opposite terminals of a source of current supply. The mechanism has a plurality of conductive discs or wipers so disposed that at least two of the wipers contact a pair of the conductors which are each connected to oppositely disposed terminals. The mechanism also has driving means such as wheels for movement and a motor engaged through the wipers for propelling the wheels over the surface. The mechanism can move forwardly, rearwardly, laterally or in a zig-zag motion. Control means are provided between the motor and the driving means so that the direction of movement may be varied in response to the voltage across the alternate conductors engaged by the wipers.

Abstract: A switching circuit has an operational amplifier connected between positive and negative supply lines and has its non-inverting input terminal connected through a resistor to an intermediate supply line. The inverting input terminal of the amplifier is fed with a signal the polarity of which varies with respect to the intermediate input terminal, and a capacitor and a resistor are connected in series between the output and non-inverting input terminal of the amplifier. The arrangement can be used in a control circuit for an electrically driven vehicle.

Abstract: A vehicle is driven by a traction motor energized by pulses of current from a battery conducted by a power switch and has forward and reverse contactors to control motor direction and a variable time-ratio control for regulating motor speed including an RC timing circuit in series with a bidirectional speed potentiometer whose resistance element is provided with a midtap for selectively varying time duration of the pulses. The speed potentiometer wiper is coupled to a manual speed and direction selecting lever having a neutral position wherein the speed potentiometer wiper engages the midtap so that duty cycle of the pulses is minimum and neither contactor is energized, and actuation of the lever in either direction from neutral increases the time duration of the pulses and also energizes the forward or the reverse contactors to thereby control direction of vehicle travel.

Abstract: An integral motor controller circuit for supplying variable speed, bidirectional drive to a motor as a function of variations of a sensed parameter includes an amplifier circuit which is responsive to an error signal indicative of deviations of the parameter from a set point to provide an output signal representing the direction and amount of the deviation. The amplifier output signal is applied to a first motor terminal and to an input of a two-level comparator circuit which is responsive to an increasing error signal exceeding a predetermined amount to connect an energizing potential of one polarity to a second motor terminal and responsive to a decreasing error signal in excess of the predetermined amount to connect an energizing potential of the opposite polarity to the second terminal of the motor, the speed of the motor being determined by the level of the amplifier output signal.

Abstract: A rheostatic control system for controlling the speed and the direction of rotation of a DC motor which is employed mainly for controlling the speed of an electric vehicle or the like. The system comprises a sliding-contact rheostatic unit which is provided between a DC power supply and a DC motor and which includes stationary contacts and speed controlling resistors, whereby the speed control of the DC motor is accomplished by means of the speed controlling resistors, and the rotation of the DC motor in either direction is controlled by changing the polarity of the voltage applied to the polarity changing terminals of the DC motor.

Abstract: A motor system and method of operation is disclosed which provides an electronically controlled motor operable from a single phase, AC power source, having adjustable unidirectional and reversing capabilities. The system includes a motor having a stator assembly and a rotor assembly. The stator assembly includes a core of stacked laminations constructed from magnetic material and a two phase winding constructed from a plurality of wire turns arranged in coils. The winding is placed in the stator assembly so that each edge of the individual coils, that is to say, the portion of the coil that extends longitudinally of the stator assembly, occupies a single slot of the stator core.

Abstract: A control circuit for an electrically driven vehicle has a switch with a central off position, and operative positions in which the motor of the vehicle drives the vehicle forwardly and rearwardly. Delay means is provided operable when the switch is in its central off position for maintaining energisation of the control circuit for a predetermined period of time, so that loads are not deenergised as the switch is moved through its off position to change the direction of operation of the truck. In the preferred form, movement of the switch to its off position reduces the demanded armature current to zero.

Abstract: A gate control for thyristor converters connected in opposition to reversibly drive a D.C. electric motor in which one of the thyristor converters operates as a rectifier and the other remains still when the motor runs forward, and vice versa. The gate control includes an operational amplifier to carry out current control for the converters and to generate an output therefrom which follows the motor armature voltage during the switchover between converters to prepare for reverse rotation of the motor. The other converter, which operates momentarily as an inverter to feed electric energy from the motor back to an A.C. electric voltage supply thereof to reduce the motor speed, is controlled to enable its inverter voltage to coincide substantially with the motor armature voltage so as not to cause excessive rushing current from the motor into the inverter at the instant of the switchover.

Abstract: A four-quadrant full-wave static converter having improved time response without current cross-over deadband. An alternating current wave is imposed on the direct current input signal, which generates gate pulses for appropriate thyristors at the desired firing angle. The applied alternating current signal can be of approximately the same magnitude as the converter deadband, so as the direct current signal varies from zero a portion of the control signal moves out of the deadband area. For fast response the magnitude of the alternating current signal can be greater than the deadband signal. As the magnitude of the direct current signal increases the relative magnitude of the alternating current signal is decreased, preventing a large DC component from being imposed on the supply during high current operations. Cycling of the imposed alternating current waves is synchronized with the firing angle point O to maintain system protection.