Showing papers on "Rectifier published in 1975"

Dynamic braking in controlled current motor drive systems

Abstract: A current source power converter for an electric motor is comprised by a combined controlled rectifier and chopper which is coupled to a controlled-current inverter by a dc reactor. In the motoring mode the combined rectifier and chopper functions as a phase controlled rectifier to control the current magnitude. In the dynamic braking mode a line switch is opened and a braking resistor placed across the rectifier output, and the combined rectifier and chopper is operated as a chopper to control the average voltage across the braking resistor and thus the current magnitude during braking.

Lamp ballast circuit

Abstract: A highly efficient tuned oscillator ballast circuit especially suitable for a fluorescent lamp load includes an oscillator circuit coupled to a pulsed DC potential source and having a tuned output circuit coupled to a load circuit, to a drive circuit for the oscillator which is dependent upon current flow in the load circuit and to a rectifier and charge storage and isolation and applying network coupled to the pulsed DC potential source and providing energy thereto whenever the potential decreases below a given reference level. A transient compensating circuit to protect the oscillator components from initial or "start up" transients is also included.

Alternator-rectifier unit with phase winding and rectifier sets subject to series-parallel switching

Abstract: Separate three-phase windings are connected to individual rectifiers arranged for series-parallel switching to improve the current-voltage output characteristic. The common exciter winding is fed through a voltage regulator. The switching of the rectifiers is controllable in response to alternator frequency, output current, temperature or efficiency and may be provided with a manual override switch.

Series parallel transition for power supply

Abstract: An AC generator or other AC source has two identical output sections which are connected through corresponding rectifiers to drive a DC load such as a group of DC traction motors connected in parallel for driving a locomotive. The rectifiers are selectively placed in parallel to provide a high current low voltage mode and in series to provide a low current high voltage mode, thus furnishing a wide range of voltage and current at a given power level to satisfy a broad range of motor requirements with a power source of limited size and capability. To effect smooth transition, one of the rectifiers includes SCR's to modulate the rectifier output voltage. During transition that rectifier is phase back to zero voltage, allowing the other rectifier to supply the full load requirements and then the rectifiers are switched from series to parallel or vice versa whereupon the modulated rectifier is returned to its full voltage. Whenever the rectifiers are in series, the modulation of the one rectifier is accomplished gradually to allow the other rectifier time to take on added voltage.

Controlled capacitive filter for active loads

Abstract: A single phase controlled capacitive filter with a smaller, more efficiently used filter capacitor than conventional capacitive filters is connected between rectifier terminals and supplies voltage to an active load producing dc output voltage. The charge and discharge intervals of the filter capacitor are controlled by gate controlled thyristors or other devices such that discharge occurs when the instantaneous rectified line voltage falls below the dc output voltage. The filter capacitor during discharge is placed in series with the load or can remain in parallel with the load in a simpler arrangement.

Full wave rectifier

Abstract: PURPOSE: A full wave rectifier for use with automotive vehicles or the likes of a simplified structure, with excellent workability, having high vibration resistance and mechanical strength and suffering from no stress on semiconductor devices during fabrication. COPYRIGHT: (C)1977,JPO&Japio

Storage battery charging system fault indicating circuit

Abstract: A circuit for indicating faults in a storage battery charging system of the type including an alternator having a field winding and a rectifier circuit having respective battery charging and alternator field winding energizing output circuit terminals. A differential amplifier circuit, to which is applied normally equal reference sensing potentials which become unbalanced with alternator faults, produces a first fault indicating signal in the event of an alternator malfunction and a transistor having the control electrode connected to the rectifier circuit field winding energizing output circuit terminal produces a second fault indicating signal in the event of a failure of one of the diodes in the rectifier field winding energizing output circuit. These fault indicating signals trigger a transistor conductive to complete an energizing circuit for a fault indicating device.

High power factor ac to dc converter circuit

Abstract: A high power factor AC to DC converter circuit includes a rectifier circuit coupled to an AC potential source and providing a full-wave rectified pulsating DC potential to a switching regulator circuit with a radio frequency current filter connected in circuit with the rectifier and switching regulator circuits to provide a pulsating DC current in phase with and of at least 50% duration of said pulsating DC potential whereby a power factor of at least 90% is effected.

Digital firing pulse generator with pulse suppression

Abstract: A digital firing pulse generator for thyristor rectifiers in a power converter system uses a time dependent waveform to trigger a one-shot multivibrator for generating a hard pulse of minimum duration and includes a free running oscillator generating a train of picket fence pulses applied to the thyristor rectifier after the hard pulse in order to insure extended conduction. A pulse suppressor actuated upon an emergency prevents the initiation of a hard pulse but does not shorten the duration of any initiated hard pulse, and suppresses the picket fence pulses. Provision for end stops on the picket fence pulses exist and the generation of a separate hard pulse is digitally controlled when a hard pulse is missing after the selection of a rectifier next to be fired.

Capacitor discharge ignition system

Abstract: A capacitor discharge ignition system including a DC to AC inverter circuit for converting a battery voltage to high voltage AC, and a rectifier for rectifying the high voltage to DC. A power capacitor and the primary winding of the ignition coil are serially coupled across the output of the rectifier. A silicon controlled rectifier is also coupled across the output of the rectifier and has its trigger element coupled to a trigger circuit which provides a trigger signal to turn on the silicon controlled rectifier in response to opening of breaker points thus causing the power capacitor to discharge through the primary winding of the ignition coil thereby to provide the requisite high voltage in the secondary winding to provide the spark at the respective spark plug. A ring capacitor is coupled across the primary winding of the ignition coil and is proportioned to provide a damped oscillatory current in the primary winding when the silicon controlled rectifier is turned off thereby limiting the rate of flux decay by clamping or ringing-out the remaining flux thus effectively clamping the secondary winding to a limited peak output voltage so as to inhibit misfiring.

Controlled rectifier motor drive system including d.c. fault detection and commutation means

Abstract: A motor control system of the type employing phase controlled rectifiers for controlling the power supplied from a polyphase alternating current source to a direct current motor includes circuitry to detect the existence of a rectifier which is conducting at an improper time and to provide appropriate corrective action to terminate such improper conduction.

Automotive alternator rectifier bridges

Abstract: An automotive alternator rectifier bridge comprising a pair of generally flat heat-conducting laminated bases each having a central layer of aluminum with layers of copper bonded to the opposite surfaces thereof. A plurality of first diodes have their cathodes solder-connected to one surface of one of the bases. The anodes of a plurality of second diodes are solder-connected to one surface of the other of these bases. Each diode is constituted by a discrete semiconductor chip having a metallic layer in ohmic contact with one face thereof and each diode is secured to one of the bases by having its metallic layer soldered to the laminated base. Electrical conductors are solder-connected to the anodes of the first diodes and to the cathodes of said second diodes and extend generally parallel to the bases for connection to automotive alternator terminals. Methods of fabricating these bridges are also described.

Microwave oven including apparatus for varying power level

Abstract: Apparatus for varying microwave power level is included in a microwave oven. The microwave oven includes a magnetron for producing microwaves used for heating and a half-wave voltage doubler for supplying half-wave pulsating DC voltage to the magnetron. In order to vary voltage and thus power output of the magnetron, the charging of the capacitor in the half-wave voltage doubler is controlled by a variable resistance connected in series with the rectifier in the otherwise conventional half-wave voltage doubler.

Induction heating apparatus with protective circuit arrangement

Abstract: An induction heating apparatus is provided with protective circuit arrangements which ensure against surge currents caused by inappropriately timed gating-on of a gate controlled rectifier or by erroneous use of a load material such as non-magnetic or ferromagnetic material. The timed gating of the gate-controlled rectifier is accomplished by means of a delay circuit which serves to count timing after a rectified excitation potential drops to the zero voltage point. A coincidence circuit is provided to detect coincidence of two signals, one is a pulse having a predetermined width and the other is a signal derived when the periodic cycle of the energization currents departs from the predetermined cycle period.

Apparatus and method for reducing effective inductance in a dynamic braking circuit

Abstract: A method and apparatus are disclosed for reducing effective inductance and providing balanced line-to-line voltages in induction machine dynamic braking circuits which utilize braking resistors to substantially increase the full torque braking range of the machine. The current phase lag caused by the inductive property of conventional braking resistors, is substantially reduced by rectifying the current provided to the braking resistor through a three-phase rectifier bridge. This reduction of the current phase lag permits a reduction in the capacitance required to compensate for the effective inductance in the dynamic braking circuit. Furthermore, because the braking currents flow through a common braking resistor, the line-to-line stator motor voltages are inherently balanced. If the prior art braking impedance control is also employed, the rectifier bridge need carry current only if dynamic braking is required when motor voltage is greater than the maximum voltage of the inverter supplying the machine. Where the braking resistor may be varied in a step-wise manner, the amount of dynamic braking capacitance needed for inductive compensation is reduced below the substantial reduction realized for a non-variable resistor. Depending upon the required degree of performance and the allowable complexity of the braking circuit, the prior art braking impedance control may be eliminated and the effective impedance of the common braking resistor may be varied in either a continuous or a step-wise manner.

Regulated high voltage ac power supply with regulated d.c. bias current

Abstract: A circuit for concurrently producing regulated high voltage a.c. current and bias d.c. current on one output line, where all regulation is accomplished in low voltge circuits, power supply being particularly useful as the power source for copier and duplicator corotrons. The basic wave shape is a rectangular wave which is amplified and regulated for application as the a.c. input to a corotron. The corotron itself is used as the rectifier for the d.c. bias current, with this current being variable in either the positive or negative direction by varying the symmetry of the a.c. rectangular wave. Since the part of the wave which has the shorter duration must have the higher amplitude, and current in the corotron increases with voltage, a feedback loop which controls the rectangular wave duty cycle will regulate the d.c. bias current as well.

Ignition system for an internal combustion engine with automatic timing shift

Abstract: A timing pulse generator supplies the control current circuit of an electronically controlled switching element in the main current circuit of the ignition system over a full wave rectifier of which one half-wave branch includes a Zener diode preventing rectification unless the voltage exceeds its threshold value. The timing pulse generator provides a pair of succeeding pulses of opposite polarity at the end of each spark timing interval, the second pulse being of smaller amplitude. The Zener diode blocks the first pulse from the output of the rectifier at low engine speeds, so that the second pulse controls the timing. At intermediate engine speeds the first pulse overcomes the Zener diode voltage and takes over control of the timing, producing a jump advance of the spark timing. At high engine speeds a parallel combination of a capacitor and a resistor prevents the second pulse produced by the timing generator from interfering with the prompt quenching of the electronically controlled switching element in the main current circuit of the ignition system, because during the short timing interval the capacitor does not discharge fully through the resistor. By means of a switch, the first timing pulse can be loaded down to transfer the timing to the second pulse at high speeds during conditions when more complete combustion can thus be provided without sacrifice of needed power.

Multi-phase rectifier system

Abstract: Disclosed is a multi-source rectifier system for providing DC power to a load from a plurality of high impedance AC electrical sources connected to a multi-source high voltage transmission system. The system comprises a parallel arrangement of high impedance AC current sources each connected in series with a respective bridge rectifier, the positive output terminals of all bridge rectifiers are connected in parallel to the positive side of a load. The negative output terminals of all bridge rectifiers are connected in parallel to the low side of the load. The individual high impedance AC current sources are completely isolated from one another through their series connected bridge rectifiers, making it possible to simultaneously supply current from more than one high impedance AC current source to the load without significant circulating currents among the sources. The parallel arrangement of high impedance AC current sources connected through bridge rectifiers to the load provides direct current electrical power to the load notwithstanding phase differences between various high impedance AC current sources. A multisource rectifier arrangement when connected to a high impedance AC current source, will yield a level of DC output power greater than what at first might be expected. Only one rectifier may conduct at any given time when voltage sources are used and when the load is resistive, for example, the rectifier conduction angle cannot exceed 120° (60° per half cycle). This is the result of forced commutation of the rectifier by the voltage source. When a current source, e.g. a high impedance AC current source, is used however, the conduction angle with a resistive load, for example, can increase theoretically to 360° (180° per half cycle) and several rectifiers can conduct simultaneously. Further, the failure of any number fewer than all of the high impedance AC current sources will not interrupt power to the load.

Three phase a.c. motor drive system

Abstract: A system for controlling the speed, torque and power of three phase a.c. motor. A binary logic circuit generates a variable frequency three phase signal which controls three driver pairs in an inverter to selectively apply either the positive voltage or the negative voltage of a direct current power source to each of the three motor phases. The three phase binary driver control signal is pulse frequency modulated below 60 cycles per second to operate the motor in a constant torque mode without varying the rectifier output voltage. The logic control signal also includes a delay to protect the drivers by assuring that one driver of a pair is "off" prior to turning the other driver "on". In addition the system comprises high response voltage and current limiting circuits to protect the system and to reduce the overcapacity requirement of the components. An accelerator/decelerator circuit achieves a nearly linear characteristic through the use of switching transistors to permit substantial cost savings.

Conveyor belt monitoring circuit - is supplied from external stationary emitter and has receiver and rectifier

Abstract: Electrically-conductive inserts, forming a circuit included an emitter, are incorporated at intervals in the conveyor belt and extend virtually over its entire width, acting on a stationary external receiver, and the natural frequency of the circuit is different from that of the emitter. The circuit also incorporates a further receiver and a rectifier. Outside the belt there is a further stationary emitter supplying power to the receiver. The circuit can be of the open type. Power can thus be delivered to the circuit from outside by radio waves, without affecting the stationary external receiver.

Nuclear reactor fail-safe unit having the function of control relay and current regulation

Abstract: An electronic unit for controlling the safety absorbers of a nuclear reactor comprises a self-supplied AND1 circuit for performing logical multiplication of input signals each capable of assuming one out of two values, series-connected modules each constituted by a dc/ac converter, the output of the last module being coupled to the first converter and to a regulator input at which is obtained a logical ac signal whose value corresponds to the result of multiplication of the different input signals, a static intensity regulator with negative current feedback for modulating the width of the square waves delivered by an isolation transformer, a rectifier for delivering a constant current to a load impedance

Arrangement for detecting ground leaks in the rotor circuit of a brushless synchronous machine excited by rotating rectifiers

Abstract: The invention is directed to an arrangement for detecting ground leaks and includes two identical synchronous machines coupled to the rotor of a brushlessly excited synchronous machine. One of the identical machines is built as an outer-pole machine and the other as an inner-pole machine. The stator winding of the outer-pole machine is supplied with a constant direct current and its rotor winding is connected through a rectifier bridge to be between ground and the neutral point of the rotor of the brushlessly excited synchronous machine. The rectifier feeds the rotor winding of the inner-pole machine, and the voltage measured at the stator winding of the latter is a measure of the insulation resistance in the rotor circuit of the brushless synchronous machine.

Protected voltage meter

Abstract: An electronic meter circuitry for use in detecting an electrical signal vage in an ordnance firing circuit for providing an unidirectional signal to an indicator which shows the presence of the signal voltage. The circuitry utilizes a first limiter to reduce the amplitude of the detected signal to a predetermined level, a bridge rectifier to provide a unidirectional signal and a second limiter to prevent overloading the indicator. A self contained test circuit utilizing a current source and two current limiting resistors is supplied so proper operation of the meter circuitry prior to use may be readily ascertained.

Voltage and temperature compensated linear rectifier

Abstract: An improved circuit for compensating for temperature and current variationsn rectifier circuits used for converting alternating current to a proportional direct current, particularly at low voltages. A separate rectifier to be used as a circuit standard is maintained in close thermal proximity to other rectifiers as part of the conversion circuit. A voltage proportional to that across the standard is applied as a bias to a terminal of the circuit rectifiers to automatically compensate for temperature and current changes in the circuit and thereby provide a more accurate rectification of an input voltage.

Static capacitance type sensor

Abstract: A static capacitance type yarn denier sensing arrangement is provided which includes a high frequency current source and a sensing condenser which has a pair of opposing electrodes electrically coupled with both sides of the h.f. current source and representing a passage for passing a yarn under measurement. The high frequency current from said current source is subject to amplitude modulation in response to instant denier variation of the yarn. The arrangement further includes a half wave voltage doubler rectifier circuit which is electrically connected with the sensing condenser acting as an input condenser to be included therein and an amplifier adapted for amplifying the output from the rectifier circuit.

High-voltage a.c. power supply with automatically variable d.c. bias current

Abstract: A circuit for concurrently producing regulated high-voltage a.c. current and automatically varying d.c. current on one output line, where all adjustment and regulation is accomplished in low-voltage circuits, power supply being particularly useful as the power source for copier and duplicator corotrons. The basic wave shape is a rectangular wave which is amplified and regulated for application as the a.c. input to a corotron. The corotron itself is used as the rectifier for the d.c. bias current, and while the nominal d.c. bias is fixed by adjusting the duty cycle of the rectangular wave to a fixed value, the actual d.c. bias current will vary in accordance with atmospheric conditions and paper thickness, which is desirable for the proper operation of copier and duplicator corotrons. The adjusted duty cycle of the rectangular wave determines the nominal d.c. bias current. This is because the part of the corotron input wave shape which has the shorter duration must have the higher amplitude, and current in the corotron increases with voltage.

Gating signal control for a phase-controlled rectifier circuit

Abstract: A method and apparatus for controlling the phase retard time of a phase-controlled rectifier circuit in a power conversion system wherein a clock-pulse synchronized alternating voltage source is connected to supply power to the phase-controlled rectifier circuit. The clock pulses controlling the voltage source are detected and delayed for a predetermined time interval prior to their application to the voltage source. A ramp voltage generator synchronized to the clock pulses and a comparator circuit for comparing the ramp voltage signal level to a reference level provide a means for generating gate pulses to control the phase retard time of the phase-controlled rectifier circuit between maximum and minimum retard times. Maximum retard time is established at the occurrence of a clock pulse by applying a gating signal to the rectifier circuit if the rectifier circuit has not been triggered prior to detection of the clock pulse. Further gating signals are inhibited until the alternating voltage source has reversed polarity in response to the delayed clock pulses thus establishing a minimum retard time. The predetermined time interval between detection of the clock pulses and application of the delayed clock pulses to the alternating voltage source is selected to be at least sufficient to allow commutation and achievement of forward voltage blocking ability, by the components of the phase-controlled rectifier circuit.

Speed control means for AC motor

Abstract: An unbalanced switching circuit is connected with a bi-directional control rectifier in such a manner that variance of counter electro motive forces produced by rotation of an AC motor affects the lower switching voltage in the unbalanced switching circuit through diodes and a capacitor to increase or decrease the conduction angle of the bi-directional control rectifier.

Pulse interference blanking circuit for radio receivers

Abstract: After a preliminary differentiation, the demodulated signal is supplied in parallel to a peak rectifier and to a second differentiating network, the outputs of the latter two circuits being added in the input circuit of a switching transistor that controls the blanking gate of a receiver. The value of the resistor across the output capacitor of the peak rectifier, as well as the rectifier capacitor, is so chosen in value that periodically recurrent pulses that may be persistently present in the signal build up a blocking bias on the switching transistor reducing its sensitivity and preventing corresponding differentiated pulses from switching it on, whereas occasionally or irregularly appearing pulses develop a negligible bias through the rectifier, so that their twice differentiated derived pulses will switch on the transistor and produce blanking.

Circuit for generating synchronization signals

Abstract: A circuit for generating synchronization signals from a digital data pulse train having a bit period T and conveying pulses in non-return-to-zero form. The circuit comprising (i) a rectifier device arranged to fullwave rectify the digital data pulse train, (ii) an oscillatory circuit tuned to oscillate with period T and stimulated by the transitions of a waveform produced by the fullwave rectifier device and (iii) a peak detector arranged to produce a bias signal which is proportional to the amplitude of the output of the oscillatory circuit. The bias signal being active upon the fullwave rectifier device to stabilize the amplitude of the waveform produced by the oscillatory circuit.