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Showing papers on "Rectifier published in 1984"


Patent
17 Apr 1984
TL;DR: In this article, a rectifier circuit is added at the output of a Class E dc/ac power inverter to shape the waveforms of switch voltage and current so that the transitions of those two waveforms are displaced in time from each other.
Abstract: A Class E switching-mode dc/dc power converter is obtained by adding a rectifier circuit at the output of a Class E dc/ac power inverter. It can operate at high efficiency at high switching frequencies. Further, the power switch is not subjected to high power dissipation or high second-breakdown stress while it is switching between the "on" and "off" states, even if the dc load on the power converter varies over a very wide range, e.g., from open-circuit to short-circuit. The high efficiency is achieved by shaping the waveforms of switch voltage and switch current so that the transitions of those two waveforms are displaced in time from each other. Then the power switch does not experience simultaneously high voltage and high current while switching. High efficiency and low stress on the switch are achieved under all load conditions by interposing a matching network between the output of the Class E dc/ac inverter and the input of the rectifier circuit. That matching network transforms the rectifier input impedance in such a way that the impedance presented to the output of the Class E dc/ac inverter is always in the range which generates switch voltage and current waveforms that yield low power dissipation and low second-breakdown stress during switching, for any value of dc load resistance at the output of the rectifier.

56 citations


Patent
09 Jul 1984
TL;DR: In this paper, a controller for providing PWM drive to an inductive load incorporating an input rectifier bridge (24) the output of which is filtered by capacitors (106, 108) and which includes input impedance (116, 118) for limiting start-up current surges.
Abstract: A controller for providing PWM drive to an inductive load incorporating an input rectifier bridge (24) the output of which is filtered by capacitors (106, 108) and which includes input impedance (116, 118) for limiting start-up current surges. A by-pass network (124) controlled from a high voltage sensor circuit (32) controls the by-pass network. The sensor circuit also provides an enablement signal (40) to a pulse width modulation circuit (42). A low voltage power supply (36) is coupled with the output (26) of the rectifier and filter function (24) to supply isolated power to the discrete driver networks of a driver circuit (48). The driver networks are controlled from the pulse width modulation circuit which, in turn, is controlled from a microprocessor (68). The drivers provide drive to three, phase designated transistor pairs of an inverter switching bridge (50) which is supplied power from the rectifier and filter circuit (24).

50 citations


Patent
24 Jul 1984
TL;DR: In this paper, a rectifier and a comparator for comparing the rectified current and a threshold value (s) and making, in the case of overshoot, a new comparison after a time equal to and 1/2T+ΔT, T being the nominal period of the AC current and ΔT a fraction of T of the order of a tenth, after overshoot.
Abstract: The device, for AC operation, is applicable more especially to the protection of very high tension installations. It comprises a rectifier (12), a comparator for comparing the rectified current and a threshold value (s) and for making, in the case of overshoot, a new comparison after a time equal to and 1/2T+ΔT, T being the nominal period of the AC current and ΔT a fraction of T of the order of a tenth, after overshoot. The new comparison is made with a circuit comprising a memory (22), a timer (24) and a circuit (34) including two inverters and an AND gate. Tripping is produced if overshoot occurs during the new comparison.

40 citations


Patent
26 Apr 1984
TL;DR: In this paper, a multivoltage electrical system for a motor vehicle that has a pair of storage batteries which, in a first charging mode, are charged in series from the direct voltage output terminals of a bridge rectifier connected to an alternating current generator.
Abstract: A multivoltage electrical system for a motor vehicle that has a pair of storage batteries which, in a first charging mode are charged in series from the direct voltage output terminals of a bridge rectifier connected to an alternating current generator. In a second charging mode, only one of the batteries is charged and this takes place when a plurality of controlled rectifiers connecting the generator and a common junction of the batteries are gated conductive. The switching between modes is a function of the voltage of one of the batteries and the voltage of a triangular voltage waveform generator operating at a fixed frequency. The system is maintained in the second mode when generator speed is below a predetermined value.

32 citations


Patent
23 Jan 1984
TL;DR: In this paper, a system for converting three-phase AC to DC voltage employs three separate converter circuits having their outputs connected in parallel to reduce current harmonics, each converter circuit includes a full wave rectifier feeding a pulse width current modulator which modulates the DC current flow to the load in a manner to maintain the magnitude of the current proportional to the instantaneous magnitude of DC voltage.
Abstract: A system for converting three-phase AC to DC voltage employs three separate converter circuits having their outputs connected in parallel to reduce current harmonics. Each converter circuit includes a full wave rectifier feeding a pulse width current modulator which modulates the DC current flow to the load in a manner to maintain the magnitude of the DC current proportional to the instantaneous magnitude of the DC voltage. The current modulators act as substantially resistive loads to reduce source current harmonics and correct the power factor. The modulators include a pair of transistors connected in a push-pull circuit which are controlled by an oscillator circuit to modulate the DC current at a frequency which is many orders of magnitude greater than the line frequency of the AC source. The DC current outputs of the modulators are coupled through DC/DC isolation transformers to the load.

31 citations


Patent
01 Jun 1984
TL;DR: In this paper, a device for eliminating inrush-current, comprising a power switch, pair of diode in reverse parallel, a resistance, a rectifier, a time constant circuit and a thyristor, was presented.
Abstract: The present invention provides a device for eliminating inrush-current, comprising connecting a power switch, pair of diode in reverse parallel, a resistance, a rectifier, a time constant circuit and a thyristor in a manner such that an ac current is supplied to a load through the resistance for a period, determined by the time constant circuit, after switching-on of the power switch, and that the rated current is supplied to the load after lapse of the period by allowing the thyristor both to conduct and to short the resistance.

31 citations



Journal ArticleDOI
TL;DR: In this paper, the design and performance of a unique concentrated winding machine specifically designed for operation with a static power converter is described, and the potential of such a machine operating as a motor is also described.
Abstract: The design and performance of a unique concentrated winding machine specifically designed for operation with a static power converter is described. When operating in tonjunction with a converter supply, the machine is theoretically capable of 15 percent more power output for the same active copper and iron than a conventionally designed synchronous machine of the same rating. The performance of the machine operating as a generator feeding a rectifier load is described, the theoretical predictions are compared with test. The potential of such a machine operating as a motor is also described.

29 citations


Patent
08 Nov 1984
TL;DR: In this article, a battery charger adapted for connection to a standard 12 volt vehicle battery through a cigarette lighter socket includes a transistorized saturable-transformer DC to AC inverter and an AC to DC rectifier for generating a potential higher than the potential from the vehicle battery.
Abstract: A battery charger adapted for connection to a standard 12 volt vehicle battery through a cigarette lighter socket includes a transistorized saturable-transformer DC to AC inverter and an AC to DC rectifier for generating a potential higher than the potential from said 12 volt vehicle battery. An integrated circuit pulse width modulated current control is used to control charging current flow to a second battery to be charged and to maintain charging current at a safe level.

27 citations


Patent
30 Apr 1984
TL;DR: In this paper, a speed control for an AC motor varies the frequency and amplitude of the motor by comparing a triangular wave from the oscillator with the DC input level, and the enabling pulses are provided to an amplitude switch which is cycled to vary the DC rail voltage.
Abstract: A speed control for an AC motor varies the frequency and amplitude. The speed control includes a rectifier which converts the AC power supplied to negative and positive DC. A switch connects each power conductor leading to the motor with one of the DC voltages. The switches are switched on and off to provide alternately positive and negative voltage. Controls for the switches include an oscillator which provides pulses of frequency that can be varied. A binary counter counts the pulses from the oscillator and provides binary outputs. A memory unit provides a programmed output to the switches for each binary output received. In one embodiment, the amplitude is varied by comparing a triangular wave from the oscillator with the DC input level. Enabling pulses equal to the excess of the triangular wave over the DC input enable the memory unit. In another embodiment, the enabling pulses are provided to an amplitude switch which is cycled to vary the DC rail voltage.

24 citations


Patent
24 Dec 1984
TL;DR: In this article, a circuit for detecting the occurence of a shorted diode in the rotating rectifier of a brushless alternator is presented, where the rectifier is responsive to the direction of current flow through the exciter field winding.
Abstract: A circuit for detecting the occurence of a shorted diode in the rotating rectifier (12) of a brushless alternator (10, 11, 12, 13, 14). A sensing circuit (30) is responsive to the direction (25, 26) of current flow through the exciter field winding (10). A reversal of the current indicates that there is a shorted rectifier diode.

Patent
11 Feb 1984
TL;DR: In this paper, the main battery charger is used for charging an electrical storage road vehicle from an a.c. mains while the vehicle is stationary, the intention being to take a sinusoidal current with a power factor of 1 from the mains.
Abstract: The on-board battery charger is used for charging the main battery of an electrical-storage road vehicle from an a.c. mains while the vehicle is stationary, the intention being to take a sinusoidal current with a power factor of 1 from the mains. Provided for this purpose are a mains-side radio-frequency filter (1), a mains rectifier (2), a step-up d.c. converter (3), a capacitive buffer store (4), an invertor (5), a battery rectifier (6) and a battery-side radio- frequency filter (7). The invertor (5) contains preferably two push- pull connected power transistors (T2, T3), operated at high frequency. In order to supply the vehicle on-board power system from the main battery while driving, the main battery is connected directly to the capacitive buffer store. An autotransformer can be connected between the invertor (5) and the battery rectifier (6) for voltage matching.

Patent
03 Feb 1984
TL;DR: An electric power source for use in an electrostatic precipitator includes a first high voltage DC source having an output terminal adapted to be connected to discharge electrodes of the electrostatic precitator as discussed by the authors.
Abstract: An electric power source for use in an electrostatic precipitator includes a first high voltage DC source having an output terminal adapted to be connected to discharge electrodes of the electrostatic precipitator An inductor is connected at its one end through a coupling capacitor to the output terminal A controlled rectifier is connected at its an anode to the other end of the inductor and has a grounded cathode A diode is connected in a reversed parallel to the controlled rectifier There is also provided a second high voltage DC source having a high output impedance and connected to the inductor, and the controlled rectifier is turned on and off by a controller

Patent
07 Apr 1984
TL;DR: In this paper, a drive inverter is used as a charger for a battery driven vehicle without exclusively providing a charger such as a rectifier by operating it as a regenerative mode.
Abstract: PURPOSE:To construct a compact battery driven vehicle without exclusively providing a charger such as a rectifier by using as a charger for the vehicle a drive inverter as it is and operating it as a regenerative mode. CONSTITUTION:A DC power of a battery 1 is converted by an inverter 2 into AC in a normal drive state, a switch 3 is closed by a command of a control circuit 7 to drive an induction motor 4. At this time a power source is not connected to a commercial power terminal 6. In the charging state, the switch 3 is opened by the control circuit 7 in the state that the commercial power source is connected to the terminal 6, and transistors of phases U and V are pulse-width modulation controlled to operate the inverter 2 in the regenerative mode.

Patent
12 Jul 1984
TL;DR: In this article, a rectifier circuit with both a voltage-multiplying rectification function and a non-voltage-multiplicative rectification (NVM) function is presented.
Abstract: An electric power unit capable of operating from different AC input power source voltages in which changes in the AC input voltage are compensated for automatically and rapidly. The power unit includes a rectifier circuit having both a voltage-multiplying rectification function and a non-voltage-multiplying rectification function. A switching circuit is provided for selecting as the operating rectification function one of the voltage-multiplying rectification function and the non-voltage-multiplying rectification function. A switching control circuit, operating with the AC input to the rectifier circuit as a reference potential, controls the switching circuit according to the value of the AC input voltage. An auxiliary power source establishes a voltage for powering the switching control circuit before the operation of the switching control circuit to select the rectification function is effected.

Patent
Toru Tanahashi1
20 Nov 1984
TL;DR: In this article, a power rectifier and a power inverter were used to control an AC electric motor IM that drives the cage, by using a voltage detector 26 that detects the voltage of the AC power source, and a minimum value select circuit 27 that receives the output of said voltage detector as a first input, that receives output instruction signal as a second input, and that compares these inputs, that produces a signal of the same level as the signal of lower level.
Abstract: The invention controls an AC electric motor IM that drives the cage 9, by using a power rectifier 2 made up of thyristors and a power inverter 4 made up of a transistor and a diode. A speed instruction 11 for the cage is compared at 12 with a detected speed from 6 to produce an output instruction signal voltage 12a for said power rectifier and a slip frequency instruction signal voltage 12b for said power inverter. The control circuit controls the phase of said power rectifier relying upon the output instruction signal and controls the pulse-width modulation of said power inverter relying upon said slip frequency instruction signal, the control circuit comprises a voltage detector 26 that detects the voltage of the AC power source, and a minimum value select circuit 27 that receives the output of said voltage detector as a first input, that receives said output instruction signal as a second input, that compares these inputs, and that produces a signal of the same level as the signal of the lower level. The output of said minimum value select circuit is produced as a corrected output instruction signal to control the phase of said power rectifier. The inverter is controlled so that its output voltage measured at 17 equals the sum of the actual speed voltage and the slip frequency voltage.

Patent
Walter Schwob1
13 Jun 1984
TL;DR: In this paper, a DC-DC converter includes an inductor having a first terminal connected to a source of DC voltage to be converted, a power transistor is connected to the other terminal of the inductor and controls the passage of current therethrough.
Abstract: A DC-DC converter includes an inductor having a first terminal connected to a source of DC voltage to be converted. A power transistor is connected to the other terminal of the inductor and controls the passage of current therethrough. A rectifier has an input connected to the inductor and has an output which comprises the output of the converter. A capacitor has a first electrode connected to the output of the rectifier and a second electrode connected to the emitter of the power transistor, the collector of the power transistor being connected to the inductor. A comparator is connected to the power transistor for controlling the operation thereof in accordance with the capacitor voltage so as to produce a desired converter output voltage. The comparator has a first input connected to receive a first reference potential and a second input coupled to the second electrode of the capacitor. The output of the comparator is coupled to the base of the power transistor. A voltage sensing device is coupled between a second reference voltage and (a) the second electrode of the capacitor, (b) the emitter of the power transistor, and (c) the second input of the comparator.

Patent
17 Jul 1984
TL;DR: In this paper, a GTO bridge-connected inverter is used to generate commutation surge voltage from an inductive load whenever each GTO is turned off, and the surge voltage is stored in a capacitor (C 1 ) through a diode surge voltage rectifier (5) and then restored to the DC source terminals (3A, 3B) through a pair of other GTOs (G 7, G 8 ) turned on during steady state intervals of inverter commutation.
Abstract: In a current type GTO inverter, commutation surge voltage is inevitably generated from an inductive load whenever each GTO is turned off. The commutation surge voltage thus generated is once stored in a capacitor (C 1 ) through a diode surge voltage rectifier (5) and then restored to the DC source terminals (3A, 3B) of the GTO bridge-connected inverter (3) through a pair of other GTOs (G 7 , G 8 ) turned on during steady state intervals of inverter commutation. Magnetic energy stored in a reactor (Lr 1 , Lr 2 ) in motor-driving operation is recharged to the capacitor (C 1 ) through the diode surge voltage rectifier (5) after the GTOs (G 7 , G 8 ) have been turned off; the motor kinetic energy stored in the capacitor (C 1 ) through diodes (D 8 , D 9 ) in motor-braking operation is regenerated to the AC source side of the inverter (3) through a pair of other GTOs (G 9 , G 10 ) when the voltage across the capacitor (C 1 ) exceeds a predetermined value, and magnetic energy stored in the reactor (Lr 1 , Lr 2 ) in motor-braking operation is recharged to the capacitor (C 1 ) through diodes (D 12 , D 13 ) after the GTOs (G 9 , G 10 ) have been turned off. The circuit operation is stable at higher frequency range because no vibration circuits are provided, and the energy conversion efficiency is high because every energy loss is effectively restored to the inverter or the power source side.

Patent
13 Jan 1984
TL;DR: In this article, a monolithically integrated rectifier bridge circuit is proposed to ensure that none of the substrate diodes which are formed between the circuit elements acting as a rectifier and the semiconductor body becomes conductive.
Abstract: A monolithically integrated rectifier bridge circuit, in which it is ensured that, when the supply AC voltage changes its mathematical sign, none of the substrate diodes which are formed between the circuit elements acting as a rectifier and the semiconductor body becomes conductive. This is achieved in that the four rectifying elements of the bridge are formed by bipolar transistors connected as rectifiers, NPN-transistors connected as rectifiers being located in each case between an AC voltage input and the negative terminal of the bridge, and the negative terminal of the bridge being connected to the substrate of the integrated circuit. It is also possible to design the four rectifying elements of the bridge by means of field-effect transistors, which are connected as rectifiers and are constructed using CMOS technology, P-channel transistors connected as rectifiers then being located in each case between one AC voltage input and the negative terminal of the bridge, N-channel transistors connected as rectifiers being located in each case between one AC voltage input and the positive terminal of the bridge, and the positive terminal of the bridge being connected to the substrate of the integrated circuit.

Patent
03 Jul 1984
TL;DR: In this article, an inverter circuit for a power train has a rectifier for rectifying a three phase AC input and a filter comprising an inductor and capacitor to produce a filtered DC signal for application to the inverter.
Abstract: An inverter circuit for a power train has a rectifier for rectifying a three phase AC input and a filter comprising an inductor and capacitor to produce a filtered DC signal for application to the inverter. A high to low voltage transducer receives the filtered DC signal to produce a low voltage output representation thereof. A leading phase shifter shifts the low voltage signal in phase. A sample and hold amplifier receives shifted signal, and a pulse generator generates timing pulses applied to the sample and volt amplifier, whereby the sample and hold amplifier produces an output signal amplitude corresponding to the amplitude of the shifted signal during periods indicated by the pulse generator output. A triangle wave generator provides a triangle wave output to a pulse width modulator, which also receives the output from the sample and hold amplifier to produce an output pulse indicative of the signal level of the filtered DC output. Finally, a decoder receives the width modulated pulses, and an inverter switching circuit receives the decoded pulse width signals to produce a three phase output having reduced modulation.

Patent
21 Sep 1984
TL;DR: In this paper, a voltage monitoring system for mounting on a test point in an AC power distribution system provides an output when the voltage level on a conductor is above a predetermined minimum level.
Abstract: A voltage monitoring system for mounting on a test point in an AC power distribution system provides an output when the voltage level on a conductor is above a predetermined minimum level. Within a sensing unit mounted on the test point a rectifier circuit develops from a capacitive coupling to the monitored conductor a voltage dependent on the voltage level of the conductor. A potentiometer applies a portion of the voltage to the gate of a MOSFET transistor, which actuates a reed-contact relay to control external switching circuitry. The potentiometer is user-adjustable from the front of the sensing unit to enable the minimum threshold level to be set.

Patent
02 Nov 1984
TL;DR: In this article, the authors use a full-wave rectifier for providing both half-cycles of the source AC signal waveform, transformed to have a common preselected polarity, with a first DC level to obtain zero crossing information for determining the start of switching device conduction.
Abstract: Multiplexing apparatus interconnects at least one power switching device, itself connected to a load for controlling of flow of current through that load from an AC source, with a control circuit for controlling conduction of the switching device(s). The multiplexing apparatus uses a full-wave rectifier for providing both half-cycles of the source AC signal waveform, transformed to have a common preselected polarity, with a first DC level to obtain zero crossing information for determining the start of switching device conduction. The same comparator is utilized with a level switch, now providing a second DC level, and a resistive divider for attenuating the voltage across the conducting switching device by a known factor, for monitoring the switching device saturation voltage during conduction. The apparatus may also include a power supply subcircuit, for providing an operating potential to a completely integrated semiconductor circuit containing this apparatus.

Patent
14 Dec 1984
TL;DR: In this article, a microcomputer implemented apparatus and method for detecting the occurence of a shorted diode in the rotating rectifier of a brushless alternator is presented.
Abstract: A microcomputer implemented apparatus and method for detecting the occurence of a shorted diode in the rotating rectifier (16) of a brushless alternator (10, 11, 12, 13, 14). The alternator current (IA, IB, IC), voltage (VA, VB, VC) and power output (KW) and the alternator temperature (TGenerator) are measured. The anticipated exciter field current (ICalculated) is determined for the alternator output and operating conditions and compared with the actual exciter field current (if actual). An actual exciter field current in excess of the anticipated current indicates a rectifier fault.

Patent
19 Sep 1984
TL;DR: In this paper, a half-bridge inverter (Q1 and Q2) is connected across a filter capacitor (C3?) of a filtered, rectified supply, which is effectively isolated from the rectifier (D1-D4) at mains frequency by isolating diodes (D5, D6) which are reverse biased for the majority of the mains-frequency cycle, when the filter capacitor is fully charged.
Abstract: A converter which converts mains frequency electrical power into a higher frequency power, which is more desirable for driving gas discharge lamps. The converter comprises a half-bridge inverter (Q1 and Q2) connected across a filter capacitor (C3?) of a filtered, rectified supply, which is effectively isolated from the rectifier (D1-D4) at mains frequency by isolating diodes (D5, D6) which are reverse biased for the majority of the mains frequency cycle, when the filter capacitor (C3?) is fully charged. The isolation diodes (D5, D6) are bypassed by capacitors (C4?, C5?) at the switching frequency of the inverter such that a proportion of the inverter output current is drawn directly from the supply rather than from the filter capacitor (C3?). The return path for the inverter output current is via the AC divider network (C1?, C2?). An inductance L1? is provided to limit current to the lamp (P), while a capacitor (C6?) is provided in series with the heaters of the lamp (P) to provide a heating current during starting. According to another feature of the invention, a switching regulator is provided wherein a switching regulator control circuit (SRCC) drives the Switching element (Q2) of a switching regulator circuit and the frequency of the output of the Switching Regulator Control Circuit (SRCC) is controlled to maintain the output voltage (M) of the switching regulator at a substantially constant level, while the pulse width of the output from the Switching Regulator Control Circuit (SRCC) is controlled in response to the instantaneous rectified supply voltage (N) such that the current (I) drawn by the regulator is substantially sinusoidal.

Patent
Toshihiro Onodera1
26 Sep 1984
TL;DR: A high voltage generator comprises a voltage resonance switching circuit which consists of a transformer (1), a GTO thyristor switching element (5) connected between the primary winding (2) of the transformer and a DC source (4), and a voltage resonant capacitor (7) connected in parallel to the switching element as mentioned in this paper.
Abstract: A high voltage generator comprises a voltage resonance switching circuit which consists of a transformer (1), a GTO thyristor switching element (5) connected between the primary winding (2) of the transformer (1) and a DC source (4), and a voltage resonance capacitor (7) connected in parallel to the switching element (5) The transformer (1) is the coreless type A rectifier circuit (9) is connected to the secondary winding (3) of the transformer (1) to rectify an output current from the rectifier circuit (9)

Patent
10 Dec 1984
TL;DR: In this article, the authors present a power unit for supplying a load either from a direct-current source or from an alternating current source, which is characterized in that it consists of a single conversion unit (CV) having unidirectional semi-conductor power components forming switches (I1, I2, I3, I4) controlled in appropriate fashion by a logic control in such a manner as to ensure the functioning of the conversion unit either in a chopper mode, or in a rectifier mode when the load functions to draw power, or to ensure energy
Abstract: The present invention relates to supplying a load either from a direct-current source or from an alternating-current source. The power unit, according to the invention, is characterized in that it consists of a single conversion unit (CV) having unidirectional semi-conductor power components forming switches (I1, I2, I3, I4) controlled in appropriate fashion by a logic control in such a manner as to ensure the functioning of the conversion unit (CV) either in a chopper mode, or in a rectifier mode when the load functions to draw power, or to ensure energy regeneration when the load functions in a generating mode. The present invention has application particularly for supplying direct-current motors used in dual-current railroad locomotives.

Patent
27 Dec 1984
TL;DR: In this paper, a starter circuit for metal halide discharge lamps in which a diode resistor rectifier network is provided between a conventional ballast and a spiral line generator to superimpose a D.C. voltage on the A.
Abstract: A starter circuit for metal halide discharge lamps in which a diode resistor rectifier network is provided between a conventional ballast and a spiral line generator to superimpose a D.C. voltage on the A.C. ballast voltage thereby to increase the peak instantaneous voltage to the spiral line generators and thus provide a larger breakdown voltage to the discharge lamp.

Patent
06 Aug 1984
TL;DR: In this article, a solid-state electronic control system for an electric motor which drives a pipe bending machine is described, where a machine operator's hand switch acts through a logic system to cause the motor to run in either direction, and negates control conflicts.
Abstract: A solid-state electronic control system for an electric motor which drives a pipe bending machine. A machine operator's hand switch acts through a logic system to cause the motor to run in either direction, and negates control conflicts. The logic system controls an SCR bridge system to select the direction of D.C. energization of the motor for forward or reverse drive. This bridge system is supplied from A.C. mains through a bridge rectifier comprising three diodes and one SCR. When motor drive is called for, this SCR is made conducting to provide full-wave rectification. When motor drive is terminated, this SCR is turned off so that the rectifier becomes half-wave, which facilitates turn-off of the motor reversing SCR's. A dynamic brake for the motor is turned on by a triac when motor energization is shut off.

Patent
13 Jan 1984
TL;DR: In this paper, a rectifier, a smoothing circuit with inductor means and smoothing capacitance, and an inverter with switching means 50, 51 for switching the input dc voltage from the rectifier to provide high frequency ac voltage output with a reduced ripple.
Abstract: The converter comprises a rectifier 3, a smoothing circuit 4 with inductor means 42 and a smoothing capacitor 41, and an inverter 5 having switching means 50, 51 for switching the input dc voltage from the rectifier to provide high frequency ac voltage output with a reduced ripple. The inductor means receives electromagnetic energy from the current therein when the switching means 50 is switched on and the electromagnetic energy is fed to the smoothing capacitor to charge the same when the switching means is switched off, the resulting voltage developed across the capacitor being applied to the inverter input. This enables the inductor means to be reduced to a smaller value while allowing it to retain a high power factor, and it can be readily incorporated in the converter without requiring any additional switching means and without undue increase in the component costs.

Patent
11 May 1984
TL;DR: In this article, a take-up machine is used in conjunction with the production of fiber or yarn, where the product yarn, as it is produced, is wound onto spools or tubes and a control is provided for varying the speed of an electric motor which drives a spindle on which the tube or spool is mounted.
Abstract: This invention relates to a take-up machine utilized in conjunction with the production of fiber or yarn wherein the product fiber or yarn, as it is produced, is wound onto spools or tubes. A control is provided for varying the speed of an electric motor which drives a spindle on which the tube or spool is mounted. This control is actuated by the position of a compensator arm which is connected to a core of a linear voltage differential transformer which, in turn, controls current flow through an NPN power transistor. The power transistor, in turn, controls current flow through a rectifier having one circuit for each of three windings of a three-phase AC motor, thereby controlling the speed of rotation of the motor.