Showing papers on "Filter capacitor published in 1971"

Theoretical performance of voltage multiplier circuits

Abstract: An expression for the equivalent source resistance of the capacitor diode voltage multiplier circuit is derived. The source resistance is found to increase as the cube of the multiplication factor, explaining the poor regulation observed with large multiplication. The distribution of capacitors that minimizes source resistance is presented. Good regulation is shown to be necessary for high efficiency, and to require relatively larger capacitors than needed for ripple filtering.

Induction motor regenerative braking system

Abstract: A controlled slip AC induction motor system is provided with normal and regenerative braking modes of operation. During normal operation, voltage from a source of alternating voltage is rectified by a full-wave bridge rectifier and supplied to the input of an inverter connected with the winding of the motor. A filter capacitor is interposed between the bridge rectifier and the inverter to filter the DC input voltage to the inverter. A feedback control regulates the switching repetition rate of controlled rectifiers in the inverter to maintain a preselected slip frequency for the voltage supplied the motor. During regenerative braking, an auxiliary power source is selectively connected with the motor phase windings to excite the motor to enable it to operate as a generator. The feedback control loop used during normal operation is used during periods of regeneration to regulate the frequency of the excitation voltage; this control provides a preselected negative slip frequency for operating the motor as a generator. The power feed inverter used in normal operation functions as a bridge rectifier transferring power from the motor to the filter capacitor during braking. The effective load impedance provided by the capacitor is electronically controlled by periodically discharging the capacitor a predetermined amount through the full-wave bridge rectifier used in normal operation (functioning as an inverter during regeneration) to the source of alternating voltage. Flexible electronic control of regeneration by the induction motor is obtained by this system.

Wide range regulated power supply utilizing optimized energy storage

Abstract: A fly-back type power supply includes a transformer, the primary winding of which is periodically connected to a DC source to establish current through such winding. When this current increases to a predetermined optimum value, the current flow through the primary winding is interrupted for producing collapse of the transformer''s magnetic field and generation of an output in the transformer''s secondary windings. The frequency at which the primary is periodically connected to the DC source is controlled by a secondary output voltage such that the frequency is increased when such output voltage tends to decrease. A plurality of secondary windings are each connected to a rectifier and filter capacitor combination, wherein the filter capacitors are coupled in series for production of a high voltage output.

Power supplies with output voltage taps from input filter choke

Abstract: A power supply circuit which provides a simple means for obtaining several output voltages bearing a fixed ratio to each other. The circuit utilizes a multiple tapped choke which is connected to a source of D.C. voltage by a chopper or switch which provides a pulsating current at a repetition frequency greater than the L.C. resonant frequency of the choke and the filter capacitor at the D.C. output terminals. Several variations of the circuit are disclosed wherein the multiply-tapped choke, or equivalently several magnetically coupled windings, are connected in series with a free-wheeling diode which is always in the state of conduction except during the duration of an input pulse of current through the input chopper or switch so that there is always current in the inductive choke. Additional switching means such as a diode is connected from the taps on the choke to output terminals and is disposed to conduct during the free-wheeling period to extract the several output voltages, each bearing a fixed ratio to the other. To reduce output voltage ripple, capacitors are connected across the output taps to maintain the output voltages substantially constant during the entire cycle.

Capacitor overcharge protection circuit

Abstract: Photo flash apparatus having two storage capacitors connected in series. Normally both capacitors are charged by a voltage doubling circuit connected to an alternating current supply, to a predetermined direct current voltage across both capacitors in series. To prevent overcharging and possible breakdwon of one capacitor in case the charge on the other capacitor decreases as a result of leakage current, the invention provides a safety circuit having two resistors in series with each other and in parallel with the respective capacitors, the safety circuit having a central connection from the junction between the two resistors to the junction between the two capacitors, the central connection containing an impulse transformer which operates when the charges on the two capacitors differ by more than a predetermined amount. The output of the impulse transformer can be used to give an indication of fault or to interrupt automatically the charging of the capacitors.

Charge regulating circuit for flash lamp storage capacitor

Abstract: A flash lamp for photographic exposures discharges from one or more high voltage storage capacitors charged from an alternating current source under the control of a charge regulating circuit. The regulating circuit comprises a bridge rectifier charging a regulator capacitor to the threshold voltage of an SBS-triac combination connecting the AC source to a step up transformer whose rectified output charges the flash lamp storage capacitors. A neon lamp sensing the voltage on the storage capacitors is transformer coupled to an SCR which shunts the regulating capacitor preventing the regulating capacitor from applying threshold voltage to the SBS and triac and stopping charge of the storage capacitors.

Multi-mode detector circuit

Abstract: A multi-band wave-signal receiver incorporates a novel detector circuit for demodulating AM, FM and NBFM signals at two widely divergent IF frequencies. The detector employs a novel splitwinding resonant input circuit which allows FM signals at 10.7 MHz and NBFM signals at 455 kHz to be alternately demodulated by a single ratio detector without bandswitching the input circuit. Provision is made for disconnecting the ratio detector filter capacitor to permit detection of 455 kHz AM signals, and for generating appropriate AGC signals in all three operating modes.

Short circuit protection means for power circuits

Abstract: A SOLID STATE POWER CIRCUIT, SUCH AS A POLYPHASE INVERTER OF ENERGIZING AN A-C MOTOR IN AN A-C ADJUSTABLE SPEED DRIVE SYSTEM, INCLUDES TWO OR MORE PARALLEL CONNECTED SERIES CIRCUITS EACH INCLUDING A PAIR OF ALTERNATELY CONDUCTIVE THYRISTORS IN SERIES INDICTIVE MEANS AND A FILTER NETWORK INCLUDING AT LEAST TWO L-C STAGES FOR SUPPLYING D-C ELECTRIC POWER TO THE SERIES CIRCUITS FROM A SOURCE OF ELECTRIC POTENTIAL. WHEN A SHORT CIRCUIT OR SHOOTTHROUGH IN THE POWER CIRCUIT HAS OCCURRED OR, UNDER SOME CONDITIONS, IS ABOUT TO OCCUR, THE RESULTING HIGH CURRENT FLOW TO THE SERIES CIRCUITS FROM THE FILTER NETWORK IS DETECTED AND ALL OF THE THYRISTORS OF AT LEAST TWO OF THE SERIES CIRCUITS ARE TURNED ON SIMULTANEOUSLY IN RESPONSE TO THE DETECTED CURRENT SUCH THAT THE FILTER CAPACITOR OF THE L-C STAGE ADJACENT THE SERIES CIRCUITS WILL RESONATE WITH THE TOTAL EFFECTIVE PARALLEL INDUCTANCE IN THE SERIES CIRCUITS TO PROVIDE SUFFICIENT REVERSE VOLTAGE TO TURN OFF ALL OF THE TYRISTORS. TO RESPOND TO INCREASED CURRENT FLOW RESULTING FROM A WIDE RANGE OF FAULT CONDITIONS IN AN EFFECTIVE AND ECONOMICAL MANNER, THE DETECTION MEANS IS RESPONSIVE TO THE CAPACITIVE CURRENT FLOW IN AT LEAST TWO OF THE L-C STAGES INCLUDING THE TWO STAGES ADJACENT THE SERIES CIRCUITS. A DIODE OR SIMILAR RECITIFER IS PROVIDED ACROSS THE FILTER INDUCTOR OF THE L-C STAGE ADJACENT THE SERIES CIRCUITS TO PREVENT EXCESSIVE VOLTAGE ON THE RESONATING CAPACITOR, TO CONTROL RIPLE VOLTAGE, AND TO PREVENT UNDAMPED OSCILLATIONS IN THE FILTER NETWORK D R A W I N G

Multifunction active RC circuit with grounded capacitors

Abstract: A new active RC circuit with grounded capacitors is proposed, which can perform as any one of the following devices: noninverting differentiator, inverting differentiator, capacitance bridge, inductance simulator, bandpass filter and oscillator.

Preliminary Study of a Nonbridge Method for Precision Measurement of Capacitors at Low Frequencies Using Operational Amplifiers and Resistance Standards

Abstract: High-precision measurements of capacitance and dissipation factor can be made without capacitor standards using active circuits known as gyrators, which are constructed with high-gain operational amplifiers and precision resistors. A theoretical analysis of the technique is carried out here using one particular gyrator circuit. A preliminary experimental study yielded values of dissipation factor, which agreed with measurements made by the manufacturer of the precision capacitors tested to within four parts per million. The theory suggests that with a more carefully engineered instrument, capacitors of 0.01-1 ??F in the 10-1000 Hz range may be measured with an accuracy of the order of 1-2 ppm. The accuracy appears to be determined primarily by the precision of two critical resistors in the gyrator.

High energy density discharge capacitors

Abstract: An extensive evaluation of available dielectric materials was undertaken as part of a development program sponsored by the US Army Electronic Command The best dielectric system for light weight, high energy density, discharge capacitors was determined to be metallized, coated polyethylene pterapthalate As a result, the following improved energy storage capacitors were developed