Abstract: A dynamic braking system for a motorized lifting mechanism such as a crane, hoist or the like allows the load to be lowered at a controlled rate during a power failure. An auxiliary power source is activated to apply an excitation current to the stator windings, creating a static magnetic field. When the brake is released the rotor rotates in the static magnetic field, generating an A.C. voltage that is rectified and applied to the stator, thereby increasing the strength of the static magnetic field. An equilibrium is reached, and the load is lowered at a controlled rate. In the preferred embodiment the A.C. voltage is supplied through an adjustable resistor, allowing the lowering rate to be selectively controlled.

Abstract: A hand held battery powered tool having a motor with a rotor within a stator having stator windings and a motor control trigger operably movable between off and enable positions with means for sensing the trigger position and proving an output signal indicating trigger movement to the off position and means responsive to the output signal for shorting the motor windings and dissipating the kinetic energy of the rotating rotor as heat. A method of retarding rotation of the rotor of the motor comprising the steps of sensation of motor operation command and shorting the motor windings upon sensing the motor operation command while continuing electronic commutation of the motor windings is also provided.

Abstract: The present invention relates to a brake device with a combination of power-generating and eddy-current magnetic resistance having an outer ]-shaped fly wheel fastened on a central axle of a frame and fitted with a permanent magnet on the inner circular edge to form a rotor type, and the fly wheel is connected with a stator core fastened on the frame; moreover, one end of the central axle is stretching out of the frame and fitted with a belt wheel; the front end of the frame is fitted with a brake core adjacent to the outer edge of the fly wheel to supply a planned eddy current magnetic resistance to the fly wheel; in accordance with such design, the device generates power by means of the exercise force of users to drive the fly wheel to rotate, after passing through a DC power supply, it provides display & controlling gage with power source so that the power-generating and the eddy current magnetic resistance are integrated to reach the effect of reducing the volume and the producing cost.

Abstract: Converter-powered electric motors are often braked by electrical means. For this purpose the electronic converter that powers the motor is so controlled that the motor, when in generational operation, sends energy by way of the converter into an electrical braking resistor additionally connected to the converter, and this energy is there converted to heat. In order to avoid overloading the electrical braking resistor, an additional electronic or thermo-mechanical protective device is customarily provided. To simplify the arrangement, it is proposed in the present invention to provide as an electric braking resistor one made of a resistive material with a conductance that decreases progressively as the temperature rises through a certain range below the maximal acceptable operating temperature of the braking resistor. As a result, the power that can be accepted by the electrical braking resistor is made self-limiting, so that the braking resistor is protected against overheating.

Abstract: A circuit for operating an electric motor (10) has a triac (24) that is parallel to the electric motor (10). The triac (24) is acted upon by a first control signal (28) that is dependent on the voltage present at a first connection (11) of the electric motor (10). The triac (24) is further acted on by a second control signal (22) that is emitted as a braking signal by a motor-control circuit (19). The circuit of the invention, which includes a semiconductor component (24), permits both a braking of the electric motor (10) and the damping of an inductive voltage peak during the switch-off process of the electric motor (10). The damping of the inductive voltage peak is also assured after the separation of the voltage from an energy source (16).

Abstract: A method for reducing audible monotonic noise in a power conversion system (10) using one or more controllable converters (20, 120, 26, and 136) includes generating a set of pulse width modulated (PWM) signals so that each converter has a different average switching frequency, and randomly varying successive cycle time intervals of the generated signals so that a respective instantaneous frequency shift relative to the respective average switching frequency of the converters is achieved over each of the time intervals.

Abstract: A braking circuit for braking an electric motor having an armature and run and brake windings, which includes a switching circuit disposed between a source of electrical power and the run winding, this circuit being operable to disconnect the run winding from the source of electrical power. The braking circuit further includes a switching mechanism operable to connect the brake winding in order to brake the electric motor. The switching mechanism preferably connects the brake winding after a predetermined period of time has elapsed from the disconnection of the run winding. This braking circuit can be used in a saw for braking the saw's blade.

Abstract: A turbogenerator/motor control system having a plurality of proportional integral control loops including a fuel command control loop and a current command control loop. The exhaust gas temperature of the gas turbine of the turbogenerator/motor is maintained at a constant value with stability is achieved by varying the sampling times of the different proportional integral controls within the control loops.

Abstract: A braking circuit for a universal motor is proposed, in which, during braking, the at least one field winding is connected in series with the armature by means of a semi-conductor switch, preferably a field effect transistor or a thyristor. Since the semiconductor switch can also be switched intermittently and with a time delay, not only is it possible to regulate the braking current simply, but there is also a reduced formation of sparks at the collector. The reduction in the contact erosion lengthens the service life and increases the reliability of the motor.

Abstract: A control apparatus by which a duty ratio in consideration of how energy stored in storage cells is consumed is set to ensure a steady traveling feeling, a regeneration brake which can produce stable braking forces regardless of how storage cells are consumed, and a protective device by which a plurality of operation stop levels are set to be able to cancel the stop operation effected for the first time and to ensure reliable alarming, are provided. In the first and second embodiments, a chopper duty ratio is compensated depending on how storage cells are consumed, to provide a steady agreeable traveling feeling. In the third embodiment, regenerated electric power is consumed by a motor driving circuit to stabilize operation of a regeneration brake regardless of how storage cells are consumed, and improve performance thereof.

Abstract: A power down brake latch circuit for dynamically braking a spindle motor in a disk drive system is disclosed. The power down brake latch circuit includes a reservoir capacitor, a smoothing capacitor, a timing circuit, and a logic circuit. The timing circuit includes a voltage divider and a bandgap comparator. The smoothing capacitor absorbs a BEMF voltage from the spindle motor as it rotates after losing power. The timing circuit generates a first signal when a voltage on the smoothing capacitor falls below a threshold. The logic circuit brakes the spindle motor in response to the loss of power and the generation of the first signal.

Abstract: In one embodiment of the present invention, a system for ride-through of an adjustable speed drive for voltage sags is provided. The system comprises an adjustable speed drive including a three phase electric utility, a diode rectifier, a dc-link, an inverter, and a motor. Coupled to the adjustable speed drive is a ride-through circuit which includes a controller having a first input and a second input, the first input operable to receive the voltage from each phase of the three phase electric utility and determine the magnitude and phase of the voltage sag, and the second input operable to receive the dc-link voltage to ensure that the rated dc-link voltage is not exceeded. Also included is an IGBT coupled to an output of the controller and operable to switch on and off rapidly based on the amount of voltage sag. An inductor associated with the IGBT and operable to store energy when the IGBT is switched on and to transfer energy to the dc-link when the IGBT is off is also included.

Abstract: A controlled stop system for an AC electric locomotive includes a braking effort control circuit responsive to a braking command regulating braking effort produced by AC traction motors coupled in driving relationship to wheels of the locomotive. The control circuit is responsive to a vehicle speed signal for adjusting motor operation to maintain braking effort to about zero speed. A filter processes the speed signal before application to the braking effort control circuit such that the control circuit operates as a speed regulator at zero speed to maintain the vehicle in a stopped condition.

Abstract: In a series-wound motor with electric brake, which comprises an armature provided with an armature winding and at least two exciter coils mounted on pole shoes as well as switchgear which, in the operative phase of the motor, serially connect the exciter coils with the armature winding and connect the serial connection to terminal clamps for the operating voltage and which, in the braking phase, interrupt the connection to the terminal clamps and short-circuit the armature winding by the parallel connection of a winding, an independent optimization of the braking behavior is made possible in that at least one of the exciter coils is subdivided into two part windings and in that, when braking, one of the part windings has its polarity changed and is short-circuited with the armature winding.

Abstract: An emergency stop circuit for an elevator drive includes an emergency stop control (7) that selectively varies the current flowing in a field winding (4) of a direct current drive motor (M). During an emergency stop, the motor (M) operates as a generator and has an armature winding (1) loaded with a braking resistor (9) to apply a voltage, depending on the direction of movement of the elevator car, either by a first switch (10) and a second switch (11), or by a third switch (12) and a fourth switch (13). The switches (10, 11, 12, 13) are connected as an H-bridge between the windings (1, 4) and are controlled by the emergency stop control (7) depending on the deceleration required by the elevator car, for example by pulse operation depending based upon a preset deceleration value and a measured deceleration value from a deceleration sensor (14) mounted on the car.

Abstract: A turbogenerator/motor controller with a microprocessor based inverter having multiple modes of operation. To start the turbine, the inverter connects to and supplies fixed current, variable voltage, variable frequency, AC power to the permanent magnet turbogenerator/motor, driving the permanent magnet turbogenerator/motor as a motor to accelerate the gas turbine. During this acceleration, spark and fuel are introduced in the correct sequence, and self-sustaining gas turbine operating conditions are reached. The inverter is then disconnected from the permanent magnet generator/motor, reconfigured to a controlled 60 hertz mode, and then either supplies regulated 60 hertz three phase voltage to a stand alone load or phase locks to the utility, or to other like controllers, to operate as a supplement to the utility. In this mode of operation, the power for the inverter is derived from the permanent magnet generator/motor via high frequency rectifier bridges.

Abstract: A control circuit (10) is provided for an electric motor brake (12) having an electromagnetic brake coil (14) energizable to actuate the brake to a released condition permitting rotation of an electric motor (16), and de-energizable to enable actuation of the brake setting the brake to a braking condition stopping rotation of the motor. The control circuit includes a switch (102) having an on state energizing the brake coil, and an off state de-energizing the brake coil.

Abstract: A positive locking device is provided in order to prevent a motor from rotating after power has been removed. The positive locking device has a plate mounted on the motor which engages a disk or hub on the shaft of the motor. In another aspect of the invention, solid state circuitry for switching a permanent magnet motor and providing dynamic braking thereto is provided. The circuitry allows the back EMF generated by the armature coils of a permanent magnet motor to cause a current to flow through the motor when power is removed. This back EMF may be used to help produce smooth engagement of the locking device. In another aspect of the invention, a dynamic braking circuit for a dual armature permanent magnet motor is provided. By applying current to one or the other of two oppositely wound armature coils the motor is made to rotate in either direction. When power is removed from the active armature, this armature is short-circuited through a diode.

Abstract: The invention relates to a method and an apparatus for braking a synchronous motor (2) magnetized with permanent magnets. According to the invention, there is connected to the input connectors (38,40,42) of the synchronous motor a non-linear braking resistor (60) by means of which the stator windings of the synchronous motor (2) are closed.

Abstract: A motor system having a stationary assembly including a winding and a rotatable assembly in magnetic coupling relation to the stationary assembly. A power supply link having upper and lower rails supplied by a power supply provides power to the motor winding. The power supply link has power switches responsive to a motor control signal for selectively connecting the rails to the winding to energize the winding with a motor current whereby an electromagnetic field is produced for rotating the rotatable assembly. The power switches include a set of upper power switches and a set of lower power switches. Each of the power switches has a conducting state and a nonconducting state. The system includes a disable circuit for selectively generating a disable signal and a control circuit for generating the motor control signal to control the power switches.

Abstract: A method and apparatus for slowing back spin of a rod string of a progressing cavity pump powered by an electric motor when power is lost. Pulse direct current voltage into the windings of the electric motor powering the progressing cavity pump to magnetize a stator of the electric motor thereby reducing the rotational speed of a rotor of the electric motor and consequently the rotational speed of the back spinning rod string of the progressing cavity pump.

Abstract: A sled motor sliding prevention circuit prevents the sled motor from sliding during track tracing so as to enable the optical disk driving apparatus to perform high speed accessing. The inverse electromotive force occurring when the sled motor stops is removed by selectively grounding each terminal of the sled motor, so that the motor does not continue to be driven by the inverse electromotive force. Therefore, high speed access in an optical disk driving apparatus can be accomplished.

Abstract: An electric motor with an electrodynamic braking means, where the same power controller is used in both motor operation and in braking. Therefore, the field current with the separately excited electric motor can be controlled or regulated by the power controller. It is also possible to preset a certain braking time. A measure of the braking current is obtained by sensing the voltage at a braking resistor, so the braking current can also be regulated on the basis of the field current.

Abstract: Disclosed is a method of controlling an internal combustion engine driven electric vehicle in power operation of the vehicle, in which control is made so that a voltage of a DC intermediate circuit is maintained to a first constant DC voltage in a first speed range of from a zero vehicle speed to a first vehicle speed, the voltage of the DC intermediate circuit is changed in proportion to the vehicle speed in the second speed range of from the first vehicle speed to a second vehicle speed, and the voltage of the DC intermediate circuit is made to be a second constant DC voltage in the third speed range not lower than the second vehicle speed, and control is further made so that an AC output of the second power converter is made to have a variable voltage and a variable frequency in the first and second speed ranges, while the AC output of the second power converter is made to have a constant voltage and a variable frequency in the third speed range.

Abstract: A motor actuator for preventing a motor from drawing excess current for longer than a predetermined time delay period including dynamic brakes for simultaneously braking motor rotation when motor operation is terminated for any reason. Source voltage supplies an input to a voltage regulator which in turn supplies a regulated voltage to the motor. The actuator includes a comparator circuit that has one input connected to motor supplied regulated voltage and a second input connected to the source voltage with the voltage level from source voltage adjusted to a level that is equal to the regulated motor voltage level under normal motor operational loads. When the motor draws excessive current the voltages on the comparator inputs become unequal which causes the comparator to have an output voltage. An RC circuit from the comparator output to ground potential delays the comparator output voltage for a predetermined time.

Abstract: A single-motor drive for an open-end spinning machine, the motor being in the form of an axial field motor with a magnet/gas bearing supporting the rotor with a gas cushion, includes a gas monitoring arrangement which will detect a disruption in the gas supply, and responsive to the gas disruption, a device for braking the rotor is connected with the circuit via a switch. The braking device, which includes a ballast resistor, is set for reducing the rotational speed of the rotor in a manner whereby when the rotor bearing surface lands on the stator bearing surface due to the collapse of the air cushion, its rotational speed is less than that which would result in damage to the bearing surfaces.

Abstract: An electric brake circuit (10) for bringing an alternating current (AC) motor (12) to a rapid halt. When the AC motor is turned on, a braking capacitor (C1) is charged to a preselected voltage. A shunt regulator (18) prevents the braking capacitor from overcharging by shunting charging current to ground once the braking capacitor reaches the preselected voltage. In a preferred embodiment, a limit circuit (20) turns off the charging current on the subsequent positive phase of the AC line voltage powering the electric brake. By shutting off current flow to the circuit when the preselected voltage on the capacitor is reached, power consumption and size of the circuit are minimized.

Abstract: A locomotive throttle controller having a central processor unit which generates an analog signal for control of dynamic braking and includes an analog output driver which supplies the dynamic brake reference voltage. Such analog output driver includes a device for receiving an analog signal from the central processor unit and for converting such analog signal into an analog voltage signal. The analog output driver provides an arrangement for using such analog voltage signal to provide a regulated voltage output to a trainline which controls the dynamic braking. Incorporated into the output driver is a protection arrangement to protect it from reverse voltages on such trainline and an arrangement for protecting such output driver from excess current demand of the trainline.

Abstract: A series motor for an appliance or tool, such as a circular saw, includes a regenerative braking circuit having brake windings in addition to the run windings. One of the brushholder assemblies includes a push-away feature for separating one of the brushes from the commutator prior to the time the brush could wear to an extent that direct current reversal might not be available to achieve the desired braking action.

Abstract: A regenerative braking control system consumes energy generated in a period corresponding to an angle .theta..sub.1 which starts in a half of a period of an AC voltage produced in a drive motor during the braking of the drive motor. The regenerative braking control system also consumes energy generated in a period corresponding to an angle .theta..sub.2 that ends at the end of a half of a period of the AC voltage. The regenerative rate of braking control system utilizes a current induced in the driving coils of the drive motor at the end of the period corresponding to the angle .theta..sub.1 to recharge a battery. By utilizing two periods to carry out the regenerative braking process, the recharging energy and the braking force can be controlled individually. Moreover, a controller monitors the electric control system to determine whether a malfunction is present. If a malfunction is detected, an electrical brake electrically brakes the drive motor.

Abstract: Disclosed is a method of controlling an internal combustion engine driven electric vehicle in power operation of the vehicle, in which control is made so that a voltage of a DC intermediate circuit is maintained to a first constant DC voltage in a first speed range of from a zero vehicle speed to a first vehicle speed, the voltage of the DC intermediate circuit is changed in proportion to the vehicle speed in the second speed range of from the first vehicle speed to a second vehicle speed, end the voltage of the DC intermediate circuit is made to be a second constant DC voltage in the third speed range not lower than the second vehicle speed, and control is further made so that an AC output of the second power converter is made to have a variable voltage and a variable frequency in the first and second speed ranges, while the AC output of the second power converter is made to have a constant voltage and a variable frequency in the third speed range.

Abstract: A method and circuit for braking a forward rotation of a rotor of a polyphase DC motor. A commutation sequencer is incremented by several phases to produce an incremented commutation sequence to produce a magnetic flux vector that lags a magnetic pole of the motor. Driving currents are applied to coils of the motor in accordance with the incremented commutation sequence to brake the rotor. The method is implemented in a circuit that has a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate the rotor. A power stage to which the commutation signals are applied energizes the selected coils in accordance with the commutation signals. A circuit interrupts the energization of the selected coils and the commutation sequence is altered to produce a sequence that produces a negative torque on the rotor.

Abstract: A locomotive throttle controller having a CPU and output driver stage. Such CPU generates an analog voltage based on software logic and transmits to the output driver stage a signal indicative such analog voltage. Such output driver stage receives the signal from such CPU and uses it to provide an analog output voltage signal to a trainline which monitors and/or controls dynamic braking. The improvement therewith of an apparatus, for feeding back from such output driver stage to the CPU an analog signal indicating status of such trainline, comprising a device for obtaining a first analog voltage signal from a node which supplies current to such trainline. A voltage-divider for dividing the first analog voltage signal into a lower range to obtain a second analog voltage signal. A signal generating device connected to receive the second analog voltage signal and generate a third analog voltage signal.

Abstract: A locomotive traction motor control system includes a traction motor to propel a locomotive when it motors, and to slow the locomotive when it engages dynamic braking. A resistive element dissipates electrical energy generated during dynamic braking. A control element, operatively coupled to the resistive element, selectively isolates the resistive element from the tractor motor when the locomotive motors. The resistive grid isolation may be accomplished with a pair of isolation switches coupled in series between the traction motor and the resistive element and a controller which opens the isolation switches when the locomotive motors and closes the isolation switches when the locomotive engages dynamic braking.

Abstract: An automatic focusing apparatus having an object distance data detecting mechanism having an optical system which includes a focusing lens assembly which can be driven by a motor, and a mechanism for detecting an angular velocity of the motor. The optical system further includes a motor driving mechanism for driving the motor in a direction and at an angular velocity based on object distance data obtained by the object distance data detecting mechanism to move the focusing lens assembly, and a mechanism for controlling the motor. When the motor is instructed to be stopped, the angular velocity is reduced to a predetermined value. The controlling mechanism is effected in accordance with the angular velocity detected by the velocity detecting means.

Abstract: A drive control system for a centrifugal used in, for example, a sugar refining operation, optimizes the deceleration and plow-out phases of its operation based on the torque characteristics of its particular drive motor. This is achieved by providing a centrifugal having a pulse-width modulated (PWM) frequency-modulated drive controlled by a programmable logic controller (PLC) running a ladder logic program. The ladder logic program implements a regenerative braking loop which complements the dynamic braking characteristic curve of the drive motor, thereby obtaining an optimal amount of braking torque for the motor over a wide range of motor revolutions or frequencies. Preferably, the system also implements a dynamic plow-out control for the motor when in plow-out mode to enable the centrifugal to be plowed-out in a minimal amount of time.

Abstract: A dynamic braking system for the electric motors in an injection molding machine uses the electric heater bands on the barrel of the injection unit as resistors to dissipate the energy generated by the electric motors during an emergency stop. This system includes suitable switching circuitry to disconnect the heaters from their normal power source and connect them to the motor windings for the short term dynamic braking function.

Abstract: In an electric system for an electric vehicle, DC power of a main battery is converted into AC power by an inverter which has a power regenerative function. At startup, the system charges an input smoothing capacitor on the DC side of the inverter through an initial charging circuit with an initial charging switch and resistor. A main circuit switch that can stop current is connected between the main battery and the inverter. A rheostatic braking circuit with a rheostatic braking switch and a braking resistor is connected to the DC input side of the inverter for rheostatic breaking when required. Rheostatic braking takes over after regenerative braking when the main battery loses its power absorption capability, with the main circuit switch off. Semiconductors can be used as switches, and can be placed on a cooling body or modularized. Low-noise wires can be used to reduce noise.

Abstract: A device for precisely stopping an induction motor includes a current transformer for sampling a power level of an alternating current power source driving the motor during run time and an AC-DC converter/sample-and-hold circuit for generating a sampling voltage signal according to the sampling. Also included is circuitry responsive to the sampling voltage signal for determining an amount of direct current necessary to induce a static magnetic field to produce a torque within a stator winding of the motor sufficient to precisely stop the motor. A silicon controlled rectifier generates the determined amount of direct current and control circuitry causes the generated current to be injected into the stator winding. The induced static magnetic field static magnetic field is sufficient to precisely stop the motor regardless of the size of the load the motor is driving because it follows the sampling voltage signal.

Abstract: A method and circuit for braking a forward rotation of a rotor of a polyphase DC motor. A commutation sequencer is incremented by several phases to produce an incremented commutation sequence to produce a magnetic flux vector that lags a magnetic pole of the motor. Driving currents are applied to coils of the motor in accordance with the incremented commutation sequence to brake the rotor. The method is implemented in a circuit that has a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate the rotor. A power stage to which the commutation signals are applied energizes the selected coils in accordance with the commutation signals. A circuit interrupts the energization of the selected coils and the commutation sequence is altered to produce a sequence that produces a negative torque on the rotor.

Abstract: A braking circuit for an electric motor includes a braking device for being connected in a circuit for braking the electric motor, a braking switch including first and second changeover switches for switching between a motor mode and a braking mode, and a control device. Switching contacts of the first and second changeover switches are switched between a first position for contacting, respectively, first stationary contacts of the first and second changeover switches in the motor mode, and a second position for contacting, respectively, second stationary contacts of the first and second changeover switches in the braking mode.

Abstract: A snubber circuit for limiting an initial voltage applied to a semiconductor switching device during transition of the switching device from a conducting to a non-conducting state includes a first circuit having a serially connected first diode and first capacitor coupled in parallel with the switching device and a second circuit having a second capacitor having a second capacitor connected between a cathode terminal of the switching device and a voltage potential less than a potential switched through the switching device and further having a second diode and a serially connected inductor coupled between the anode terminal of the switching device and the lower voltage potential. The voltage appearing at the cathode terminal of the switching device in excess of the lower voltage potential will effect a current through the inductor to limit an initial voltage rise at the cathode terminal when switching the device to a non-conducting state.

Abstract: A method for dynamically braking a motor, the motor having a plurality of terminals and receiving an input alternating current voltage waveform, by detecting the zero crossing of the input alternating current voltage waveform and for a plurality of position of the input alternating current waveform: sampling a voltage waveform appearing at a terminal of the motor to develop a sampled value for the position, comparing the sampled value for the position to a reference value for the position and setting a flag if the reference value for the position matches the sampled value for the position, introducing a delay period and generating a gating pulse to fire a silicon controlled rectifier to provide a pulse of braking current to the alternating current motor and then halting the braking of the motor if the flags for each of the plurality of positions are set. Also an electronic dynamic brake assembly operable in a SLAVE mode, a PRE-STOP mode, a HOLDING mode and a MASTER mode.

Abstract: An apparatus comprising, in combination, an AC motor, a solid state switch controlling the AC motor, the solid state switch switchable between an on state in which an electric current flows through the solid state switch and an off state in which electric current does not flow through the solid state switch, the solid state switch characterized by a turn off time such that, when the solid state switch is switched between the on state and the off state, at least a portion of the electric current flows through the solid state switch during the turn off time, a first switch circuit for switching off the solid state switch to prevent the electric current from flowing to the AC motor, a diode bridge coupled across the AC motor, a second switch circuit for controllably switching the diode bridge between an active state in which electric current may flow through the diode bridge and an inactive state in which electric current may not flow through the diode bridge, a control circuit for controlling the second switch

Abstract: A dynamic braking circuit for use with bi-directional conveyor systems and other equipment having a soft start/hard stop capability in both directions of movement. The circuit electrically brakes the rotation of a DC motor by short-circuiting the armature of the motor, thereby creating a reverse current and reverse magnetic field to oppose the motor's rotation. The circuit uses high-voltage, high-current SCR's to switch the motor running current (in both directions) and to brake the motor as quickly as is possible for a braking circuit that uses such reverse current. The circuit thereby operates without the use of any in-series braking resistors or "smoothing" inductors which lower the magnitude of the reverse current. The SCR's are gated "on" in pairs per each half-cycle of the AC power supply, which enhances noise immunity of the overall SCR control circuit.

Abstract: A system for braking a wheeled vehicle when it is attempted to be moved outside of a defined perimeter wherein at least one wheel of the vehicle is mechanically coupled to a shaft carrying means to create upon rotation of the shaft, through electromagnetic action an electric current at a pair of terminals; circuit means, responsive to a predetermined signal, to short said terminals, thereby creating a counter electromagnetic force to inhibit rotation of said shaft and wheel coupled thereto to brake the latter; means to generate said predetermined signal; and means to radiate said signal locally along said perimeter.

Abstract: A handheld low voltage machining tool with which any one or more of drilling, milling, and abrading operations can be safely performed even on densely populated, multilayer, circuit boards. Provisions are made for preventing electrical overstress by isolating the tip of the machining tool from the drive motor as well as for preventing abrupt starting of the tool which can cause jerking, jumping or skipping of the tool off of the target. Still further, dynamic braking of the tool bit is achieved, both upon release of an operator actuated control switch and due to a selected conductive layer being reached. For the latter effect, a probe is provided by which a low voltage can be delivered to a component or conductor on the board, and circuitry detects grounding of this voltage by contact with the grounded bit of the machining tool.

Abstract: A motorized golf cart circuit and apparatus capable of transporting various golf related items including a golf bag carrying golf clubs around a golf course under manual or automatic control is provided. The cart operator is provided with the option of operating the cart either manually by applying pressure to a switch located on the hand grip of the cart apparatus, or automatically in either a timer or a distance travel mode. The timer mode allows the cart operator to send the cart ahead automatically along a straight or curved path set by the operator for a predetermined period of time before the cart circuit automatically turns off. The distance mode of travel allows the cart operator to automatically send the cart ahead, following either a straight or curved path set by the operator for a distance of between 10 and 50 yards. Both the speed and the path of the cart may be varied by the cart operator by turning a balance control knob located on the control panel interface of the golf club cart.

Abstract: For the low-loss braking of an electrically driven vehicle with two electric motors connected in parallel and arranged one on each side of the vehicle and which are controlled by a pulse control, it is proposed, for one, to brake the vehicle above a prescribed rpm threshold value by useful-current braking, and below it by means of regenerative braking. Secondly, instead of an rpm threshold value, the battery current can also be used as the criterion for one of the two different braking types. A high heat generation in the motors is avoided and energy is saved by this braking process. An electric switching circuit for the conversion of this process is indicated.

Abstract: Motor control system for reversible series DC electric motor having improved dynamic braking performance for smoothly, rapidly, and consistently stopping the motor armature rotation so that any operated devices are similarly stopped at a predetermined location. The control system uses a bridge conformed like a full-wave rectifier together with a series of switches having open and closed positions to control the direction of current through the armature. The current through the motor field winding is always in the same direction. Provision is made to insure operation of a complete cycle once the system is initially energized and the switches which control the direction of current through the armature are protected from arcing upon opening.