Abstract: An inductor in a series path of a DC converter having a buck or boost configuration is constituted by a transformer with windings in series with switches of the converter. A transformer turns ratio facilitates matching switch voltage and current stresses to characteristics of MOSFETs forming the switches. A high side MOSFET can have its source at a constant voltage to facilitate driving this switch. One switch can be replaced by a diode. A transformer leakage energy removal circuit can provide an auxiliary output voltage, greater than the input voltage for a buck configuration.

Abstract: An integrated circuit controls a power converter that includes single stage buck-boost converter and a switching full bridge that may be used to drive an HID lamp. The single stage buck-boost converter reduces the complexity and parts count of the power converter, or electronic ballast, while permitting PFC and DC bus voltage regulation under control of the integrated circuit. The integrated circuit also provides all the drive signals to operate the switching full bridge circuit to maintain constant power on the HID lamp. A wait timer provides an interval of time between restart attempts for the HID lamp to permit the lamp to cool so that high hot restart voltages are avoided. The integrated circuit simplifies the design of power converters and electronic ballasts in particular, while contributing to reducing part count, complexity and cost in conjunction with the single stage buck-boost converter.

Abstract: A power supply method and apparatus of a line interactive UPS utilizes a bi-directional AC/AC power converter in association with the AC delta control concept. When the line voltage coupled to the AC/AC power convert exceeds high/low statuses, the UPS is operated in a line voltage conversion mode, wherein the AC/AC power converter supplies a voltage to compensated the line voltage based on the stability of the line voltage, and then the compensated stable voltage is further provided to the load so as to perform the voltage boost (step-up) and/or voltage buck (step-down).

Abstract: The invention relates to a buck converter comprising: a pair P—0 of switches SB, SH in series and connected to an input terminal B of the converter by the switch SB, K other additional pairs P—1, P—2, . . . , P_i, . . . P_K?1, P_K of switches in series between another input terminal A and the switch SH of the pair P—0, with i=1, 2, . . . K?1, K, the two switches of the same additional pair P_i are connected in series via an energy recovery inductor Lr_i; K input groups, Gin—1, Gin—2, . . . Gin_i, . . . Gin_K?1, Gin_K, of Ni capacitors C each in series; K output groups, Gout—1, Gout—2, . . . Gout_i, . . . Gout_K?1, Gout_K, of Mi capacitors C each in series. The switches P—0 and the K additional pairs are simultaneously controlled by first and second complementary control signals.

Abstract: The objective of this invention is to reduce the current flowing through the inductance element in a step-up/step-down DC—DC converter and to control the ripple in the output voltage. In the DC—DC converter, four states, that is, the first state [1] of (M1, M2)=(off, on) and (M3, M4)=(on, off), the second state [2] of (M1, M2)=(on, off) and (M3, M4)=(off, on), the third state [3] of (M1, M2)=(on, off) and (M3, M4)=(on, off), and the fourth state [4] of (M1, M2)=(off, on) and (M3, M4)=(off, on) are repeated in a prescribed order, preferably in the order . . . [1]?[4]?[2]?[3]?[1] . . . or . . . [1]?[3]?[2]?[4]?[1] . . . .

Abstract: A plurality of constant ON-time buck converters are coupled to a common load. The output of each buck converter is coupled to a common load via a series sense resistor. The regulated output voltage across the common load is compared to a reference voltage to generate a start signal. The start signal is alternately coupled to the controller on each buck converter. The ON-time of a master buck converter is terminated when a ramp signal generated from the regulator input voltage exceeds the reference voltage. All other slave converters have an ON-time pulse started by the start signal and stopped by comparing a sense voltage corresponding to their output current during their ON-time pulse to the peak current in the master converter during its ON-time. A counting circuit with an output corresponding to each of the plurality of buck converters is used to select which buck converter receives the start signal.

Abstract: In accordance with an embodiment of the disclosed matter, a voltage regulator may supply power to a component within a computer system. A timer may be provided. The voltage regulator may operate synchronously, and when the timer expires the voltage regulator may operate non-synchronously. For one embodiment, the voltage regulator may operate non-synchronously when the timer expires and the component is in a sleep state.

Abstract: A DC—DC converter that receives input of a direct current voltage such as a battery and supplies a controlled direct current voltage to a load is simplified. It comprises a voltage step-down converter section consisting of a first switch 2, a first rectifying means 3 and an inductor 4, a voltage step-up converter section consisting of an inductor 4, a second switch 5 and a second rectifying means 6, and a control section consisting of an output capacitor 7, an error amplifying circuit 10, an oscillation circuit 11 and a pulse width control circuit 12. An oscillation voltage Vt from the oscillation circuit 11 is compared with an error voltage Ve from the error amplifying circuit 10 and a duty ratio of each switch is adjusted to control the operation of voltage step-down, voltage step-up and step-down, and voltage step-up.

Abstract: A power converter having a two stage boost circuit and a small boost converter. The main power flow for the power converter is via the two stage booster circuit having a single switch. The voltage spike of the switch is clamped by a diode and a capacitor. The energy at the capacitor is transferred to the power converter's output terminals by the small boost converter. The two stage boost converter topology enables the use of much lower voltage and Rdson MOSFET switches so as to reduce cost, switch conduction loss and turn on loss.

Abstract: When a switching element (33) changes from ON state into OFF state, a capacitor (35) is charged. The rising of the voltage of the switching element becomes dull relative to the falling of the current flowing in the switching element. When the switching element changes from OFF state into ON state, because a diode (34) has been in ON state, switching of the switching element is zero-voltage switching. When an auxiliary switching element (39) changes from ON state into OFF state, an auxiliary capacitor (41) is charged. The rising of the voltage of the auxiliary switching element becomes dull relative to the failing of the current flowing in the auxiliary switching element. When the auxiliary switching element changes from OFF state into ON state, because an auxiliary diode (40) has been in ON state, switching of the auxiliary switching element is zero-voltage switching.

Abstract: Circuit apparatus for interconnection between an electric power source of expected variability and an recreation vehicle requiring a known fixed range of voltage change. A voltage sensor (18) for producing signals representative of corresponding source voltage variation ranges. A transformer (60) with tapped primary (56,58) is selectively switched to provide low boost or high boost to compensate two low ranges of the source voltage connected by a relay (54) energized by the voltage sensor signals (18). If the source voltage exceeds the low boost range, a further relay (28) energized by a sensor signal connects the source voltage to output terminals (40,42) for ultimate use.

Abstract: The invention relates to an auxiliary switching circuit (10) for a chopping converter comprising a first inductive element (L0) for serial energy storage with a free-wheel diode (DL) and a switch (K), in addition to a second inductive element (L) for di/dt control when the switch is closed, the auxialiary switching circuit comprising a magnetic circuit (11) whereby a main winding thereof is formed at least partially by the first inductive element (L0), also comprising means (L1, D1, L2, D2) for discharging the second inductive element when the switch is opened or closed, and means (L2, D2) for transferring the energy corresponding to the closure vis a vis said main winding.

Abstract: A system for electronically actuating valves in an engine. The system includes first and second voltage sources, and a plurality of valve actuator subsystems coupled therebetween. Each valve actuator subsystem has a valve actuator and a switch configured to selectively control application of voltage to the valve actuator to thereby selectively control energization of the valve actuator. The system also includes a dissipation switch operatively coupled with the valve actuator subsystems, the dissipation switch being selectively operable to control dissipation of energy from any of the valve actuators.

Abstract: The invention relates to a unitary magnetic coupler including a first inductor (Lp) consisting of a first winding of phase ? and having a number N of turns between the two ends of the first winding and, magnetically coupled to the first inductor (Lp), a second inductor (Ls) consisting of a second winding of the same phase ? and having the same number N of turns between the two ends of the second winding, where the ends of the first and second windings of the unitary magnetic coupler are interconnected using links consisting of capacitors (C1, C2) of equal value.

Abstract: A system for electronically actuating valves in an engine. The system includes a first voltage source, a second voltage source, and plural valve actuator subsystems coupled between the first voltage source and the second voltage source. Each valve actuator subsystem has a valve actuator and a switch. One of the actuator subsystems is configured so that current flows from the first voltage source through the valve actuator of the subsystem when the switch is in a first position, and when the switch is in a second position, current is permitted to flow from the valve actuator toward the second voltage source. Another of the valve actuator subsystems is configured so that current flows from the second voltage source through the valve actuator of the subsystem when the switch is in a first position, and when the switch is in a second position, current is permitted to flow from the valve actuator toward the first voltage source.

Abstract: Apparatus operates at a power level within a range of power levels that includes a rated maximum power level of the apparatus. The apparatus includes circuit elements to deliver power at an output voltage to a load from a source at an input voltage using an inductor selectively connected between the source and the load during a power conversion cycle. The inductor conducts a current having an average positive value during the power conversion cycle. A first switching device is interposed between the source and a first terminal of the inductor. A second switching device is interposed between a second terminal of the inductor and the load. A switch controller turns ON the first switching device during a time interval within the power conversion cycle during which the current is negative.

Abstract: Voltage regulation, transient response and efficiency of a voltage regulator module (VRM) is improved where short duty cycles are necessitated by large differentials of input and output voltage by including at least one clamping of a tap of an inductance in series with an output of each of a plurality of parallel branches or phases which are switched in a complementary fashion or providing coupling between inductors of respective phases. Such coupling between inductors is achieved in a small module with an integrated magnetic structure. Reduced component counts are achieved while deriving built-in input and output filters. Principals of the invention can be extended to isolation applications and push-pull forward converts, in particular. A lossless clamping circuit is also provided allowing spike currents to be suppressed while returning power to the output of the VRM.

Abstract: A system and a method are provided for bi-directional power conversion in a portable device. The system uses a single inductor to perform both buck and boost power conversion operations and a controller to supply signals to two switches, enabling electric current paths. The system includes a battery connected to ground and to an inductor terminal. The first switch has a terminal connected to a portable device power bus, a second terminal connected to a second inductor terminal, and an input to accept a control signal. The second switch has a terminal connected to the second inductor terminal, a second terminal connected to a portable device ground, and an input to accept a control signal. Controller inputs accept the bus voltage and the battery voltage and outputs supply power conversion control signals to the switches in response to evaluating the bus and battery voltages.

Abstract: A DC/DC up/down converter (30), comprising inductive energy storage means (L), switching means (S1, S2, S3) and control means (40). The control means (40) are arranged for operatively controlling the switching means (S1, S2, S3) for transferring electrical energy to a first output (Vout1) of the DC/DC converter (30) in a down-conversion mode and for transferring electrical energy from the first output (Vout1) to a second output (Vout2) of the DC/DC converter (30) in an up-conversion mode.

Abstract: A low-ripple power supply includes a storage capacitor coupled across load terminals, and an inductor connected to a source of voltage including a varying or pulsatory component and a direct component, for causing a flow of current to said capacitor through the inductor. The varying component of the inductor current flowing in the capacitor results in ripple across the load. A winding is coupled to the inductor for generating a surrogate of the varying inductor current. The surrogate current is added to the inductor current to cancel or reduce the magnitude of the varying current component. This cancellation effectively reduces the varying current component flowing in the storage capacitor, which in turn reduces the ripple appearing across the load terminals.

Abstract: Apparatus operates at a power level within a range of power levels that includes a rated maximum power level of the apparatus. The apparatus includes circuit elements to deliver power at an output voltage to a load from a source at an input voltage using an inductor selectively connected between the source and the load during a power conversion cycle. The inductor conducts a current having an average positive value during the power conversion cycle. A first switching device is interposed between the source and a first terminal of the inductor. A second switching device is interposed between a second terminal of the inductor and the load. A switch controller turns ON the first switching device during a time interval within the power conversion cycle during which the current is negative.

Abstract: A non-inverting dual voltage regulation set point power supply for a restraint control module is disclosed that includes a main power source. A regulated voltage generation circuit connected with said main power source for generating a regulated output voltage having an upper set point and a lower set point. A buck switch connected to said main power source and said regulated voltage generation circuit for bucking the regulated output voltage generated by said regulated voltage generation circuit to said upper set point if said voltage supplied from said main power source is greater than said upper set point. A boost switch connected with said regulated voltage generation circuit for boosting the regulated output voltage generated by said regulated voltage generation circuit to said lower set point if said voltage supplied from said main power source is less than said lower set point.

Abstract: A symmetrical DC/DC converter selects an energy transferring direction and a step-up or a step-down operation as well as a desired step-up or a step-down ratio. The converter includes a single inductor with a pair of switching devices connected to its terminals in a symmetrical arrangement with respect to the inductor. The converter is operable as a step-up converter and a step-down converter in a manner such that one and the other of the switching devices are used as an input switch and an output switch, respectively, and that one and the other of the switching devices are conversely used as an output switch and an input switch, respectively.

Abstract: A zero voltage, zero current switching power factor correction converter includes a boost unit including a first switch, a second switch and a resonant circuit at least having two energy storage elements, wherein the resonant unit is operatively configured to alternatively discharge electric energy from one of the energy storage elements to a load, a boost unit having a boost choke for receiving an AC voltage, a rectifying circuit coupled between the boost choke and the resonant unit, a third switch and a fourth switch respectively connected across one of the energy storage elements, and a power factor correction controller for respectively enabling the first switch and the second switch to turn on and off when a current flowing through the first switch is zero and a current flowing through the second switch is zero, and respectively enabling the third switch and the fourth switch to turn on and off when a voltage across the third switch is zero and a voltage across the fourth switch is zero.

Abstract: A boosting and step-down switching regulator includes one error amplifying circuit, and an output of the error amplifying circuit is compared with a triangular wave for boosting and a triangular wave for step-down different in voltage level from each other but synchronous with each other in comparison circuits, respectively, to switch the boosting operation and the step-down operation over to each other. Thus, the boosting operation and the step-down operation can be readily switched over to each other irrespective of an input voltage and an output voltage.

Abstract: A novel monolithic step-down dc-dc buck converter that uses two or more (“n”) parallel slices to achieve a high output current with a small filter capacitor is provided. Each of the n slices may be operated with a phase difference of 360°/n. Each of the converter slices may be based on a synchronous rectifier topology to avoid the excessive power losses introduced by the diode component of conventional step-down buck converters. Hysteretic control may be used (with or without pulse-width modulation and pulse-frequency modulation) to provide an internal gate-drive waveform without the need to provide a dedicated clock signal or oscillator circuit.

Abstract: A direct current voltage converter in accordance with the invention includes a substantially static direct current voltage source, an inductor; a current-control switch coupled with, and between, the voltage source and the inductor, a step-up switch coupled with the inductor, and a current sense device coupled in series with the step-up switch and electrical ground. The converter also includes a capacitor for storing converted voltage that is coupled with, and between, electrical ground, and the inductor and the step-up switch through a device for controlling current flow direction. The converter further includes a first control circuit, which opens and closes the current-control switch based, at least in part, on an electrical current conducted through the current sense device, and a second control circuit, which opens and closes the step-up switch based, at least in part, on a voltage potential across the electrical load.

Abstract: A direct current voltage boost converter includes a substantially static direct current voltage source coupled with an inductor. The converter also includes a step-up switch coupled with the inductor, and a capacitor coupled with, and between, electrical ground, and the inductor and the step-up switch via a switching device for controlling current flow direction. The converter further includes a single control circuit coupled with the step-up switch, the switching device and an output terminal of the boost converter, wherein the control circuit opens and closes the step-up switch and the switching device substantially out of phase with each other. This out of phase switching effects voltage conversion and regulation based, at least in part, on a desired output voltage and an output voltage present on the output terminal of the boost converter.

Abstract: Five circuit synthesis methods, for forming new power conversion circuits with enhanced electromagnetic compatibility and improved AC performance from old circuits with AC performance and/or electromagnetic compatibility deficiencies, are revealed. The new synthesis methods achieve performance improvements without requiring the addition of magnetic cores. In all cases a simple toroidal magnetic core structure is not precluded. In all cases splitting or adding magnetic windings is required, and, in many cases, additional capacitors are required. Many new circuits formed by applying the synthesis methods are revealed. The results achieved by application of the synthesis methods include zero ripple current at all terminals without adding magnetic cores or requiring a complex magnetic circuit element, cancellation of common mode currents, improved control loop bandwidth, and faster transient response.

Abstract: A tapped-inductor step-down converter and method for clamping same with a clamping capacitor so that MOSFETs can be employed to improve circuit efficiency. The converter includes a tapped-inductor and clamping capacitor uniquely arranged to eliminate resonance between the leakage energy of the leaky inductance and the clamping capacitor. Moreover, such arrangement provides for the recycling or recovering of the leakage energy from a leaky inductance of the tapped-inductor to further improve circuit efficiency.

Abstract: A swinging inductor is used to achieve zero-current switching in a resonant buck-type voltage converter. The swinging inductor exhibits the property of a relatively high inductance at zero current and low current, but it swings back to the original resonant inductance value at high current. In this way the high and medium regions of the current sine wave remain effectively unchanged. Upon circuit power application, the current rises slowly due to the high swinging inductance value, but this is an innocuous parasitic effect. Using the swinging inductance placed in series with a switching device to control the transfer of energy from the input source to the output load allows for a very efficient transfer of energy and it also prevents the current from becoming negative. Moreover, the efficiency level is sustainable over a wide range of input and output voltage requirements.

Abstract: A fuel dispenser system is provided in a standard configuration based upon a single supply voltage requirement that is independent of the available local power supply sources. A supply voltage apparatus integrally coupled to the standard dispenser configuration employs a transformer to adapt the field supply voltage from the local power supply to the voltage level needed by the dispenser devices such as the power supplies.

Abstract: A computer system includes a chassis, electronic circuitry, a plurality of removable power supply units, and a power distribution mechanism to which the power supply units are connectable. The chassis includes at least one connector for effecting a connection to a first, chassis, ground potential. The electrical circuitry is connected to a second, logic, ground potential. Each of the power supply units is provided with a separate removable grounding plate for selectively coupling chassis ground to logic ground. The use of a power distribution mechanism with a plurality of removable power supply units enables redundancy for the power supply units, whereby the system can remain powered when one of the power supply units fail. The use of the grounding plates for each of the power supply units enables reliable connection of the electrical and chassis grounds can be effected, even when one of the power supply units and/or its connecting cable is faulty.

Abstract: Five circuit synthesis methods, for forming new power conversion circuits with enhanced electromagnetic compatibility and improved AC performance from old circuits with AC performance and/or electromagnetic compatibility deficiencies, are revealed. The new synthesis methods achieve performance improvements without requiring the addition of magnetic cores. In all cases a simple toroidal magnetic core structure is not precluded. In all cases splitting or adding magnetic windings is required, and, in many cases, additional capacitors are required. Many new circuits formed by applying the synthesis methods are revealed. The results achieved by application of the synthesis methods include zero ripple current at all terminals without adding magnetic cores or requiring a complex magnetic circuit element, cancellation of common mode currents, improved control loop bandwidth, and faster transient response.

Abstract: Voltage regulation, transient response and efficiency of a voltage regulator module (VRM) is improved where short duty cycles are necessitated by large differentials of input and output voltage by including at least one clamping of a tap of an inductance in series with an output of each of a plurality of parallel branches or phases which are switched in a complementary fashion or providing coupling between inductors of respective phases. Such coupling between inductors is achieved in a small module with an integrated magnetic structure. Reduced component counts are achieved while deriving built-in input and output filters. Principals of the invention can be extended to isolation applications and push-pull forward converts, in particular. A lossless clamping circuit is also provided allowing spike currents to be suppressed while returning power to the output of the VRM.

Abstract: The present invention provides a modified buck regulator circuit capable of providing two output voltage levels. The circuit includes an inductive element connected between the input and output of the circuit. Further, the circuit includes an auto-transformer and two switches creating separate current paths with a load connected to the output of the circuit. In one mode, the switches are operated in parallel to provide a first voltage across the load. Because the switches are in parallel with respect to each other, the load current is divided between the two switches. In a second mode, the switches are operated in a push-pull mode. In this mode, the auto-transformer steps down the load voltage and also effectively steps down the current across each switch. As such, the buck regulator circuit of the present invention may provide two separate voltages, while also reducing the current across the switches of the buck regulator circuit.

Abstract: A buck or boost (BOB) power converter circuit. A buck converter is cascaded with a boost converter to form a buck or boost circuit (20). The BOB converter is controlled by a controller (26) such that only the buck or boost converter is operating at any given time. A reference signal Vref can be applied to the controller (26) such that the output voltage from the converter closely tracks the reference signal. Positive and negative ramp signals are generated and an error feedback signal is compared with the ramp signals to control the output in accord with Vref. This is useful in application of the output voltage as the power supply to an RF Power Amplifier (16) so that the reference signal can represent the envelope of a signal to be transmitted and the RF PA (16) can operate at high efficiency.

Abstract: Three terminal PWM DC to DC converter networks which accomplish both non-pulsating input and non-pulsating output currents using a single simple coupled inductor is revealed. The DC to DC converter networks accomplish buck, boost, buck boost (flyback), buck complement, boost complement, or flyback complement (SEPIC) conversion using a simple circuit requiring only two switches, one of which may be a simple diode rectifier, one or two capacitors, and three or four inductors, which may be co-located on a single common magnetic core. Also revealed are techniques to accomplish isolation, high order (quadrature) transfer functions, methodology for reducing current ripple to near zero levels at all terminals simultaneously, and methodology for generalizing the process of changing three terminal networks with pulsating terminal currents into three terminal networks with non-pulsating terminal currents.

Abstract: A bi-directional power converter apparatus and method of conversion is disclosed which comprises three active elements (output, primary, and auxiliary switches) and two passive components (primary and auxiliary energy storage elements) coupled so as to enable operation in any one of several different power conversion modes, including: a Non-Assisted Generation mode, a Super-Assisted Generation mode, a Super-Assisted Regeneration mode, an Auxiliary Generation mode, and an Output Regeneration mode. The individual components operate in a synergistic fashion to enable the free, bi-directional, transfer of power from primary and auxiliary energy sources to a load, and from the load to the primary and auxiliary energy sources. Further, the invention operates in such a way as to dramatically reduce the effective boost/buck ratios required for low voltage energy sources connected to a high voltage output power bus.

Abstract: A converter for converting an input voltage (Ui) into an output voltage (U0). The converter has several modes of operation. The converter can, for example, operate in an up-conversion mode, a down-conversion mode, or a window conversion mode. The converter has at least one switch (S1-S4) for controlling the converter so as to obtain a desired value of the output voltage (U0) in the up-conversion mode and in the down-conversion mode. This is achieved by changing the duty cycle of a binary signal (BS) which controls the switch (S1-S4). The converter further includes means (DMNS) for detecting the duty cycle of the binary signal (BS). This duty cycle is compared with a reference duty cycle (RFDCCL). The result of this comparison is used for deciding whether or not to change over from the up-conversion mode (or the down-conversion mode) to the window conversion mode. In the window conversion mode each switch (S1-S4) in the converter is permanently closed or open.

Abstract: A low power loss boost converter of the discontinuous conduction type includes an inductor coupled between the boost converter input and a junction, a current rectifier coupled between the junction and the converter output, a switch coupled between the junction and common, and a switch capacitor coupled in parallel with the switch, the inductor and an energy storage capacitance associated with the input. The switch is alternately opened and closed in switching cycles which alternately energize the inductor and transfer the energy to the output load. Power losses are reduced by providing switch closure at a near zero voltage and current switch conditions produced by a circuit resonance. The capacitor reduces voltage across the switch during the switch open transient condition.

Abstract: The present invention provides a sputtering power supply apparatus which realizes stable sputtering at a pressure lower than the discharge start pressure, so that scattering of sputtering particles due to collision with sputtering inert gas can be reduced, thereby improving the step coverage and the denseness of the sputter film. According to the present invention, there is provided a sputtering power supply apparatus comprising a sputtering DC power source (A), a constant current circuit (B) connected to the DC power source, a sputtering source (21) connected to the constant current circuit (B), and a control unit (11) for controlling a current output from the constant current circuit (B) so as to be a constant current.

Abstract: For use with a boost converter having a boost inductor couplable to a source of electrical power, a rectifier coupled to the boost inductor and a boost switch coupled across the rectifier, the boost converter operable in discontinuous mode, a circuit for, and method of, providing a reduced output voltage from the boost converter. In one embodiment, the circuit includes an autotransformer, coupled across an output of the boost converter, having an intermediate tap that provides a reduced output voltage at the output.

Abstract: An AC voltage regulator provides a desired AC voltage to a load. The desired AC voltage is within a predetermined range above and below that of an AC voltage source. The AC voltage regulator has a transformer, the secondary winding of which is configured to be placed in series with the AC voltage source and the load. A plurality of switches is configured to direct current from the AC voltage source through the primary winding of the transformer. The switches are further configured to control the direction in which current flows through the primary winding of the transformer. A pulse width modulator controls the switches according to a desired cycle period.

Abstract: A resonance tapped transformer circuit in which the effective turns ratio of the transformer is dependent on the frequency of the input signal. The transformer selectively connects one or more primary coils of the transformer in series and/or in parallel where the connection type is dependent on the line frequency. This changes the transformation ratio of the transformer.

Abstract: A voltage compensation system for an A.C. power line supplying one or more air conditioners, a telephone system or other telecommunication system, a battery charger, or some other utilization system that should have an input voltage within a given normal range. The voltage compensation system includes a transformer unit containing a transformer having at least two windings coupled electromagnetically by a transformer core; one of those windings preferably is in two segments that are connectable in series or in parallel. One winding is connected to an input terminal and to an output terminal. The other winding adds to the A.C. line voltage when the line voltage drops below a low voltage threshold and/or subtracts from the line voltage when the A.C. line voltage exceeds a high voltage threshold. If the A.C. line voltage is in the range required by the utilization system, the other transformer winding is effectively shorted out or otherwise disconnected.

Abstract: In a partitioned power converter system having a central uninterruptible power supply ("UPS") stage couplable between a commercial power source and a peripheral stage, the central UPS stage including a primary converter that converts commercial power from the commercial power source to a distribution voltage; a battery boost converter, coupled to a battery reserve system, that boosts a battery voltage produced thereby to the distribution voltage; and mode switching circuitry that alternatively couples one of the primary converter and the battery boost converter to the peripheral stage, selective bypass circuitry and a method of increasing the efficiency of the power converter system.

Abstract: A power-factor-corrected switching power supply includes a power-factor-corrector cell followed by a current-fed dc/dc converter cell. Both cells operate in discontinuous current mode. A duty cycle modulator has its input coupled to the output of the current-fed dc/dc converter cell and its output coupled to the switch control inputs of both the PFC cell and the current-fed dc/dc converter cell so that both cells receive the same control signal.

Abstract: A voltage compensation device for a two-conductor A.C. power line supplying one or more air conditioners, a telephone system or other telecommunication system, or some other utilization system that requires an input voltage within a given range. The device includes a transformer having electromagnetically coupled primary and secondary windings with the primary and secondary each connected to at least one output terminal. One winding is connected to add voltage to the A.C. line voltage when the line voltage drops below a given low voltage threshold, and in bucking (subtractive) relation when the A.C. line voltage exceeds a given high voltage threshold. When the A.C. line voltage is in the range required by the utilization system, the one winding is effectively shorted out or otherwise disconnected. A sensor for the line voltage actuates one or more relays connected to the transformer to effect the desired compensation action.

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.