Abstract: An active filter provides ripple cancellation in a DC-DC converter. The feedforward filter applies to any converter with an output filter inductor. The filter is inherently stable, performs in both continuous and discontinuous conduction modes, and applies to resonant converters. A suitable linear amplifier, combined with a current transformer, results in a low loss implementation. An adaptive tuning scheme compensates for inductance variation and drift. The filter is usable with buck, push-pull, and boost converter topologies. The result is output ripple below 10 mV.sub.RMS. The filter is effective on converters with outputs as low as 2 V and currents beyond 30 A.

Abstract: A power converter and a method of operating a power converter. The power converter includes: (1) a transformer for receiving bipolar electrical input power from a power source, the power substantially free of dead time and (2) a hybridge rectifier coupled to the transformer and including first and second output inductors of independently selectable, differing inductance, the hybridge rectifier receiving the input power from the transformer and rectifying the input power to produce an output power substantially free of ripple current at a predetermined duty cycle operating point of the converter, the first and second output inductors being of independently selectable, differing inductance thereby to allow the predetermined duty cycle operating point to be adjustable.

Abstract: An electrical power converter system having a power factor correction circuit and a switching power converter. The power factor correction circuit converts the AC line voltage into an unregulated DC voltage referred to as the PFC voltage, which supplies an unregulated DC input voltage to the switching power converter. The switching power converter converts the unregulated DC input voltage into one or more regulated DC output voltages. The PFC voltage automatically adjusts to an appropriate value for achieving the desired power factor correction, converter efficiency, and converter temperature. In a preferred embodiment, the value of the PFC voltage is adjustable in response to a control signal produced by a PFC control circuit. The PFC control circuit measures the peak value of the input line current to determine whether the power factor is acceptable. If the power factor is acceptable, the PFC voltage will be maintained at a relatively low value.

Abstract: A digital signal processor implemented monitoring circuit for detecting phase and magnitude disruptions in multi-phase alternating current input signals. A phase lock loop receives multi-phase alternating current input signals and provides one set of alternating current output signals in phase with a time average of the multi-phase alternating current input signals and provides a second set of alternating current output signals phase shifted in relation to the first set of output signals. In a three phase system the phase lock loop provides six alternating current signals. A demodulation circuit multiplies the first set of output signals from the phase lock loop circuit with the multi-phase input signals to produce demodulated sets of signals. An output circuit coupled to the demodulation circuit sums the first set of demodulated signals to provide a first source quality signal. The second set of demodulated signals is also summed to provide a second source quality signal.

Abstract: A circuit arrangement which is provided with an up-converter (3) which comprises at least an inductive device (31), a switch (32), and a capacitive device (34) which in the operational state is periodically charged with a charging current in dependence on periodic switching of the switch. The switch is switched to the conducting state periodically during a substantially constant time t.sub.on. The circuit arrangement is provided with detection circuitry (I) for direct detection of the charging current. As a result, a load current which has a sinusoidal shape by good approximation is drawn from a connected AC voltage supply source by the circuit arrangement.

Abstract: This invention measures the total line current in a power cord which is used to energize both a power factor corrected system and non-power factor corrected AC loads. The power factor control loop of the power factor corrected system is then driven to correct the power factor of total line current in the power cord ideally to approach unity.

Abstract: A power factor correction circuit for use with a power supply. The power supply has an input for receiving an AC input signal, a rectifier for producing a rectified AC signal and an output stage for outputting a DC output signal for driving a load coupled to the output stage. The power factor correction circuit comprises an input port coupled to the rectifier for receiving the rectified AC signal; and an inductor coupled to the input port for storing energy in response to excitation by the rectified AC signal. The excitation of the inductor is controlled through the opening and closing of a switch by a controller. A capacitor is coupled to the inductor and charged by the energy stored in the inductor when the switch is opened to produce the DC output signal. The power factor correction circuit includes a diode for blocking the charge path between the input port and the capacitor and also allowing the controller to boost the charge level on the capacitor.

Abstract: A nonlinear ripple feedback circuit for use with a current-sourced rectifier system with an inductor input filter. The nonlinear ripple feedback circuit eliminates the oscillation of the rectifiers and improves the line-current waveform by sensing of and compensating for any amplitude of ripple appearing in the DC-side current. A sample of the rectified line voltage is multiplied by the product of a voltage feedback control signal times the ripple feedback signal ratio to form the input to the pulse-width modulator which produces the gating waveform for the converter of the rectifier system such that the oscillation and sensitivity of the converter system is reduced, and the AC line current waveform has low distortion, regardless of the DC-side ripple current levels.

Abstract: A switching power source apparatus for producing power signals. The apparatus includes a rectification circuit for rectifying received alternating voltage signals, a smoothing circuit for smoothing the rectified signals and a switching power supply circuit for producing the power signals. The apparatus may include a circuit for extracting low voltage signals from the switching power supply circuit and for superposing such low voltage signals on the smoothed rectified signals so as to reduce a ripple component present in the smoother rectified signals. The smoothing circuit and the switching power supply circuit may utilize a common switching device and/or a common frequency switching signal.

Abstract: An AC/DC converter is provided for connecting to conductors of a multi-phased alternating current generator or network, which is built redundantly for protection against a total loss and which loads the AC generator essentially without non-linear distortion and where several power factor correction circuits, arranged in parallel with one another, are provided. A number of rectifier circuits are included which are independent of each other and equal to the number of phases of the generator. Each rectifier circuit has six rectifier elements which are connected in pairs to terminals of the generator and, by the formation of bridges, are commonly connected to the output conductors of the rectifier circuits. Each rectifier circuit is connected to a one phase power correction circuit. At least one switch is provided for each rectifier circuit.

Abstract: A half bridge power converter utilizes two oppositely phased power switches operated with unequal duty cycles. A magnetic arrangement with two inductance values having a ratio equal to the ratio of the unequal duty cycles is included in the converter to compensate for the unequal duty cycles.

Abstract: The present invention provides an active power line conditioner (APLC) which has improved peak voltage regulation capability when compared with similarly-sized devices constructed according to current teachings. The invention utilizes a control function which, when the AC input voltage is not within a given sinusoidal regulation range of the APLC, superimposes selected harmonics of the fundamental frequency on the reference voltage signal used to control voltage regulation action. This causes the AC output voltage of the APLC to have a nonsinusoidal, but peaking waveform shape. The magnitude of the harmonics are preferably controlled to increase as the amount by which the AC input voltage falls outside the linear regulation range of the active power-line conditioner. In presently preferred embodiments, the chosen harmonic frequency is preferably an odd harmonic of the fundamental frequency, with third or fifth harmonics believed to be particularly useful.

Abstract: An electronic device for effectively preventing time-varying current from passing through an electro-chemical cell or battery is disclosed. Time-varying current flowing in a circuit which includes the cell/battery is sensed externally to the cell/battery with a magnetically-coupled ac current probe thereby producing an induced time-varying signal. This induced signal is amplified to the level of the original time-varying current and applied to the cell/battery's terminals in phase-opposition to the original current. As a result, the component of time-varying current flowing in the cell/battery's external leads assumes an alternate path around the cell/battery and is effectively canceled within the cell/battery itself. Time-varying voltage across the cell/battery, which would normally result from time-varying current passing through its internal impedance, is likewise eliminated.

Abstract: A differential charging circuit comprising an active switch device controlled by a differential trigger circuit and a current impedance device to charge a storage battery through an intermediate storage capacitor. A capacitor and commutating inductance are also connected in series with the output to reduce ripple. The differential active switch device is controlled based on a reference potential developed across the current impedance device, and this enables frequency-controlled charging of the storage battery through the commutating type inductance.

Abstract: A ripple feedback circuit for use with a current-sourced rectifier system with a resonant load balancing filter. The ripple feedback circuit eliminates the oscillation of the rectifiers and improves the line-current waveform by sensing the low frequency AC components of the output current and by combining such AC components with the control voltage at the input to the multiplier of the pulse width modulator of the rectifier system. A sample of the rectified line voltage is multiplied by the control voltage less ripple feedback to form the input to the pulse-width modulator which produces the gating waveform for the converter of the rectifier system.

Abstract: In a power-factor-corrected electronic ballast, an AC/DC converter comprises a half-bridge electronic self-oscillating inverter powered from non-filtered full-wave-rectified 120 Volt/60 HZ power line voltage, and its resulting amplitude-modulated 30 kHz output voltage is applied to a series-resonant L-C circuit. The 30 kHz voltage developing across the tank capacitor of this L-C circuit is rectified and applied as direct current to an energy-storing capacitor, from which a DC supply voltage is provided to a frequency-converting ballast which, in turn, provides a substantially non-modulated high-frequency AC output voltage used for powering a gas discharge lamp via a current-limiting inductor. Trigger pulses are provided to trigger the inverter into self-oscillation at the beginning of each pulse of DC voltage provided by the unfiltered rectified power line voltage. As soon as the magnitude of the DC voltage across the energy-storing capacitor exceeds a first level, the trigger pulses cease to be provided.

Abstract: The invention relates to an AC to DC converter having an improved power factor achieved by combining boost converter operation at the beginning and ending of each half wave of the AC input waveform, with passive operation at the middle portion of each half wave. The timing of the operation is based on comparing the instantaneous voltage with a stored average voltage, which has the effect of making boost converter operation go off at a fixed angle after the beginning of each half wave and go on at a fixed angle before the ending of each half wave, the angles being independent of the average AC voltage. The converter increases the power factor to a value between 90 and 97% and reduces the current waveform distortion to between 15 and 29%.

Abstract: A control for a DC link power conversion system including a brushless generator having a main generator portion including an armature winding and a rectifier coupled to the armature winding of the main generator portion which converts AC power developed therein into DC power on a DC link comprises a circuit for sensing a parameter of the DC power, a circuit coupled to the sensing circuit for generating an alternating current waveform having a harmonic content dependent upon the sensed DC power parameter and a circuit coupled to the generating circuit for modifying the AC power developed in the main generator armature winding with the alternating current waveform so that the DC power has a certain AC component superimposed thereon.

Abstract: A ripple reduction circuit includes a controllable switch, an impedance coupled to one of a pair of main current path electrodes of the controllable switch whereby the impedance and the switch are coupled between first and second DC conductors and gating circuitry coupled between one of the conductors and a control electrode of the controllable switch for closing the switch when AC ripple power is carried by the conductors whereby at least a portion of the AC ripple power is removed from the conductors and delivered to the impedance.

Abstract: A circuit for providing current to a laser tube permits high current, high output voltage, and high frequency modulation response (e.g., up to about 1 MHz, in one embodiment) with low power dissipation. This is accomplished by combining the output current from two current sources, one of which is a high amplitude low frequency current mode switched mode power supply, while the other current source is a low amplitude, high frequency current source.

Abstract: The invention relates to a converter which can operate as a rectifier to rectify alternating current into direct current running in one direction (for example to charge batteries) or a converter where DC (from the batteries) can be converted to AC and supplement AC power, for example to supplement an alternator output in peak load conditions. The converter comprises a uni-directional electrical energy source (battery) and a bi-directional energy source (small battery bank connected for reverse direction current flow, capacitor or fuel cell) which is capable of initiating an alternating current when controlled by thyristors fired in sequence and with such periods that a sine wave can be simulated. The switches are controlled by a thyristor trigger logic current control unit which may for example be a micro processor.

Abstract: A power generating system (10) in accordance with the present invention includes a converter (14) for producing an AC output (16) including a fundamental and at least one harmonic of the fundamental; a frequency analyzer (18), having at least one input coupled to the AC output, for providing an analysis of a frequency spectrum of the AC output; a processor (36), coupled to the frequency analyzer, for calculating at least one switching frequency, each switching frequency being used for transforming a different harmonic within the AC output back to the fundamental; a controller (34), responsive to the at least one calculated switching frequency, for producing control signals at the at least one calculated frequency for transforming the at least one harmonic back to the fundamental; a separating filter (24), coupled to the AC output, for separating the fundamental and that at least one harmonic; at least one converter (30 and 32), coupled to the at least one harmonic from the converter and to the controller, eac

Abstract: A converter circuit includes three-phase unit converters connected in cascade in two stages for supplying electric power to a load. In a region in which the converter output voltage ratio is small, the firing phases of both converters are so set that a phase difference of 120.degree. makes appearance therebetween, while in a region in which the converter output voltage ratio is large, the firing phases are so set as to have a phase difference of 60.degree. therebetween, whereby an angular difference of 90.degree. to 30.degree. is caused to occur constantly between the phases of voltage ripple components of the unit converters. Power factor of a power supply source is improved while ripple in the output voltage of the converter circuit is reduced.

Abstract: An A.C. to D.C. power conditioner, which draws sinusoidal input current utilizes digital proportional-integral control to provide output voltage regulation by adjusting the gain of a current program loop. The current program loop controls the state of a power switch to force the instantaneous average current in an inductor to follow the instantaneous rectified line voltage. Variable hysteresis control provides noise immunity by increasing the ripple current in an iron-cored filter inductor when the instantaneous input voltage is high. Digital proportional-integral (PI) control provides output voltage regulation by adjusting, in discrete steps, the gain of the current program loop. A multiplying digital-to-analog converter serves as an interface between the voltage regulation loop and the current program loop. The sampling rate of the PI controller is determined by the input line frequency, which allows good transient response to be obtained.

Abstract: A ripple reducing circuit wherein ripple voltages across the output terminals of a voltage source are coupled through a ripple sensing circuit to an amplifier. The sensed ripple is amplified and phase reversed to provide signals in phase opposition to the ripple signals. These phase opposition signals are coupled via an anti-ripple element to the output terminals of the voltage source for effecting ripple level reduction.

Abstract: A protective triggering system protects the thyristor switch element of a pulse generator circuit controlling a pulse operated electrostatic precipitator. The protective triggering is initiated for every pulse in the area around passage of the pulse current from positive to negative, its object being to supplement the spark-over released retriggering system so as to ensure that spark-overs occurring immediately after the current passage across zero do not cause renewed thyristor current in the absence of a triggering signal.

Abstract: A radar transmitter includes a ripple and droop reduction circuit to reduce the ripple and droop of the beam (power) supply. A beam supply filter capacitor is connected to the source of power and an operational amplifier has its balanced input ac connected across the beam supply capacitor. A transistorized amplifier stage inverts the signal from the operational amplifier and amplifies its absolute value up to the same level appearing across the beam supply filter capacitor. A transistorized follower stage is connected to the transistorized amplifier stage for receiving the inverted signal and producing a low impedance output for insertion in series with the beam supply filter capacitor for ripple and droop cancellation. A traveling-wave-tube is connected to the supply power capacitor which receives the ripple and droop free capacitor output and produces substantially consistent pulses for transmission.

Abstract: A system is provided for alleviating harmonic distortion in a power supply having an AC input, a full wave rectifier and filter capacitors. The rectified voltage is chopped at a frequency that is higher than the frequency of the original AC waveform. The higher frequency cycle is provided by timing means coupled to the gate of a FET. The chopped and rectified voltage is stored in an inductor device during one portion of the higher frequency cycle and the energy from the inductor device is transferred to the filter capacitors during another portion of the higher frequency cycle. A reverse protection diode, and a capacitor for delivering high frequency energy to the FET are connected across the output of the full wave rectifier.

Abstract: A noise reduction circuit for a DC power supply in which the input of a high pass filter is coupled to the output circuit of the supply so as to receive a noise signal, the output of the high pass filter is coupled to the primary winding of a transformer via an amplifier, and the secondary winding of the transformer is coupled to the output circuit of the supply so as to reduce the noise therein.

Abstract: A circuit for controlled power supply devices, particularly for autoconverters, for suppressing the oscillatory tendency in such device has an input filter forming a parallel oscillator circuit, which can be excited to oscillations on the basis of a partially negative input impedance of the autoconverter. A series oscillator circuit is connected to the parallel oscillating circuit and is tuned to the resonant frequency thereof, such that an impedance minimum occurs at the resonant frequency, whereas the parallel resonant maximums of the impedance, which appear at a lower and at a higher frequency, can be damped by a comparatively small ohmic resistance, such that unwanted oscillations are prevented. The circuit represents a low capacitive load to the feed network, and exhibits low dissipated power through the ohmic resistor, making the circuit particularly adapted for high output power packs which are operated by a three-phase network.

Abstract: An apparatus for improving the transient response of a power supply system having an alternator for developing AC power and a rectifier for converting the alternator output into primary DC power includes a second rectifier for rectifying the alternating current power from the alternator to derive supplemental DC power and means responsive to a parameter of the primary DC power for coupling the supplemental DC power to the primary DC power when the parameter drops to a particular value so as to minimize the effect of load changes on the system. The purpose of the disclosed system is to allow the alternator to be sized for minimum electromagnetic weight while at the same time providing a simple means of reducing load application transients.

Abstract: A rectifier circuit for receiving an A.C. electrical power signal at a pair of circuit input terminals and for providing a rectified, D.C. electrical power signal at a pair of circuit output terminals includes a primary transformer winding connected to receive the A.C. electrical power signal, a plurality of secondary transformer windings, and a semi-conductor rectifying and switching circuit which supplies a D.C. electrical power signal to a storage capacitor connected across the circuit output terminals. A control circuit sequentially actuates the semi-conductor switches such that differing combinations of the secondary transformer windings are sequentially connected across the storage capacitor during each successive half cycle of the A.C. electrical power signal. By this arrangement, the charging current supplied to the capacitor and the charging potential across the capacitor fluctuate minimally during most of each half cycle and the A.C.

Abstract: According to the present invention, an induction heating apparatus comprises a rectifying circuit for rectifying an AC voltage from an AC power source, an inverter circuit for converting a DC output from the rectifying circuit to a high frequency current and supplying it to a heating coil, a circuit for detecting a fluctuation in the AC power source through a low voltage converting section coupled to the AC power source, this detecting circuit having a detection characteristic which can hold the detecting state for at least a constant time, and a controlling circuit for controlling the inverter circuit in the stopped state or driving state in accordance with the presence or absence of a detection output from the circuit for detecting the fluctuation in the AC power source voltage.

Abstract: A ripple and noise filter for high voltage DC converters or power supplies. The filter includes a common terminal, an input terminal and an output terminal. A voltage sensing circuit is connected between the output and common terminals of the filter and is adapted to produce a sense signal which is proportional to the output voltage at the output terminal. An active filtering circuit, preferably an amplifier having a frequency operating range which covers the frequency spectrum of the ripple and noise voltages, includes an input for receiving the sense signal and an output at which a correction signal is generated. The correction signal has a magnitude and waveform such that coupling the correction signal onto the output terminal of the filter eliminates or reduces the ripple and noise. A passive coupling element, preferably a capacitor, isolates the amplifier from the output terminal and couples the correction signal thereto.

Abstract: Various circuit embodiments for reducing the electromagnetic interference (EMI) typically created by a ballast circuit for an improved lighting unit is disclosed. The EMI reducing circuit adapts the operation of the source of the EMI of the ballast circuit to the conductive states of the rectifier means of the improved lighting unit.

Abstract: A two-wire electronic dimming ballast arrangement for one or more gas discharge lamps is disclosed which includes an inverter driven by a variable pulse width electric power and a control system for modulating the pulse width of the variable pulse width square wave electric power driving the inverter. A unique distortion suppression system is provided for suppressing current abberations and achieving substantially a unity power factor.

Abstract: An alternator produces current that has an average component and a ripple component. The alternator testing apparatus produces one voltage representative of the magnitude of the peak-to-peak amplitude of the ripple component and a second voltage representative of the sum of the average component and the peak-to-peak amplitude of the ripple component. A series of comparators each have their signal inputs coupled to receive the first voltage and their control inputs coupled to a divider network which is in turn coupled to receive the second voltage. Indicators are coupled to the comparators.

Abstract: A discharging circuit for a power source device with a rectifier circuit used in an power source for driving a motor in which when the alternating current power source is turned off and the load is electrically separated, the voltage of a time constant selection circuit (22, 23) falls rapidly, the voltage across a diode (25) rises, a Schmitt circuit (24) is activated, the circuit consisted of a transistor (27) and a resistor (26) is conducted, and a smoothing capacitor (28) is discharged, and hence the heat generation at the resistor is decreased and the concern over unsafety due to delayed discharge of the capacitor is eliminated.

Abstract: A failure detection device for a convertor which converts alternating current into a direct current through a plurality of rectifying thyristors. The waveform of the output direct current of the convertor is detected and is supplied to a band-pass filter which selectively passes the harmonic component which has a frequency corresponding to that of the AC voltage source for the convertor. The existence of the component of this frequency is characteristic of an occurrence of a failure within convertor. The amplitude of the component passing through the filter is then detected by a zener diode, and a failure signal is generated when the amplitude exceeds a predetermined level.

Abstract: In a thyristor-controlled converter system the non-canonical harmonics are minimized by active filtering through control of the firing angle of the thyristors in accordance with the undesired harmonic component.

Abstract: An electronic device that converts alternating current to direct current with high efficiency. This is accomplished by constructing the device in such a manner that the device turns itself on slowly so that a surge resistor is not needed.In common power supplies of this type the surge resistor accounts for a large part of the power loss. In making the surge resistor not necessary power is saved.

Abstract: In circuits such as voltage regulators and the like where parasitic currents may be generated as a result of high frequency ripple on the supply line, means are provided to cancel the effects of the parasitic current. A capacitor having a capacitance substantially equal to the parasitic capacitance is adapted to receive the supply voltage excursions and generate a current substantially equal to the parasitic current. A current mirror circuit or the like is employed to either divert this second current from the base of the output transistors or to reduce the drive current to the base of the output transistors by an amount equal to the second current.

Abstract: A circuit for use in a multiphase regulated supply to provide regulation of the ripple current contained in the filtered d.c. output signal of the supply. The supply regulates its output voltage and/or current by controlling the conduction time of the switching elements contained in the rectifier portion of the supply. The switching element conduction time is controlled by controlling the generation of firing pulses to the switching elements as a function of an error control signal which is equal to a first error signal. This signal is equal to the amount by which the actual value of said voltage and/or current deviates from a reference value of said parameter. When the ripple regulation circuit is included in the supply, a second error signal is generated which represents the deviation of the d.c. value of the ripple from a predetermined reference.

Abstract: A switching regulator circuit for utilization with power supplies supplying a high DC output current including a plurality of control rectifiers and inductive reactors with sequential gating of the rectifiers at regular intervals for providing overlapped output current pulses from the reactors. An output circuit receives the rippled current comprised of the overlapped output current pulses for reducing the ripple therein. The output circuit includes a choke in series with the output which induces phase shift between the rippled current and the output current. A sensing winding associated with the choke eliminates the phase shift voltage for forming a feedback signal as an input to a control circuit. The control circuit utilizes the feedback signal to control the rate at which the rectifiers are gated sequentially.

Abstract: The DC to DC voltage converter consists of two single ended pulse width modulated converters with a single voltage control loop, a power balancing control loop and overload protection circuitry. The converters which share the same input and output filters are staggered in time so as to reduce the pulse current in the input filter capacitor and the ripple current in the output filter capacitor thereby permitting a reduction in the size of the input and output filters.