Abstract: In one embodiment, in a power converter system having a load, a method is provided for varying the type of modulation employed for a pulse width modulation (PWM) signal. The method includes the following: monitoring the load of the power converter system; using leading edge modulation for the PWM signal under light load condition; and using trailing edge modulation for the PWM signal under heavy load condition; thereby optimizing operation of the power converter system.

Abstract: In the PWM circuit of the present invention, a PWM counter counts clock signals. A reference value setting register sets a comparative reference value for determining a duty ratio of a PWM signal. A comparator generates the PWM signals based on a comparative result of the comparative reference value and a count value of the PWM counter. A delay device delays the PWM signal. A switching device switchably outputs the output of the comparator and the output of the delay device in order of time sequence. Thereby, the pulse phase of the PWM signal can be adjusted.

Abstract: Enhancement of the power conversion efficiency and reduction of switching noise of a power supply circuit are achieved. The power supply circuit includes, on the primary side, a composite resonance type converter formed from a current resonance type converter and a partial voltage resonance circuit in combination, and is configured so as to produce a plurality of secondary side DC output voltages. A particular one of the plural secondary side DC output voltages is controlled to a constant voltage by variably controlling the switching frequency of a primary side switching converter. Each of the remaining secondary side DC output voltages is controlled to a constant voltage by adjusting the level of control current to be supplied to a controlling winding of a control transformer in response to the level of the secondary side DC output voltage to adjust the inductance of a controlling winding of the control transformer inserted in a rectification current path.

Abstract: A frequency modulation controller for use in controlling a switched mode power supply including an input terminal for receiving an input voltage and at least one switch selectively turned on and off to control the output voltage of the power supply in accordance with an embodiment of the present invention includes an analog to digital converter operable to convert a feedback signal indicative of the present output voltage into digital data, a digital conditioning unit operable to provide an error signal based on the digital data from the digital to analog converter for use in generating the frequency modulation signal and a digital to analog converter operable to provide the frequency modulation signal based on the error signal, wherein the frequency modulation signal indicates a desired duty cycle of the at least one switch to maintain a desired output voltage such that the at least one switch of the switched mode power supply is turned on and off in accordance with the desired duty cycle.

Abstract: To provide a switching power supply apparatus which can achieve the followings simultaneously in high levels: the voltage waveform capable of reducing switching noise to the least is in a sine-waveform; capable of providing an output of stable voltage without a control, and a simple response; and capable of corresponding to instantaneous peak current without having saturation of the core. It relates to an improvement of a resonance-type Royer converter with less switching noise as a base, which is directed to be used for audio equipment. A second inductor is inserted to the primary side inductor between a rectifier circuit and a smoothing means, which is coupled to the primary-side inductor in a same magnetic circuit in a direction of canceling a DC magnetic flux. Moreover, timing of the next cycle is determined by applying a center tap voltage of a transformer to a synchronous signal input terminal of a control IC. Thereby, a self-excited oscillating action is actually stabled.

Abstract: A programmable AC/DC power converter receives a plurality of input voltages and outputs a single voltage from an input voltage system. A transformer receives the single voltage. One of the plurality of input voltages is provided at a center tap of a secondary winding of the transformer. A transformed voltage is output. A rectifier receives the transformed voltage and outputs a DC voltage. A buck regulator receives a DC voltage, creates a regulated voltage, and outputs the regulated voltage and a regulated current to a portable appliance. A error correction system receives a programming signal and regulated signals and verifies that the regulated signal to programming signal ratio is within an acceptable range.

Abstract: First and second semiconductor switches which are activated alternately are provided between ends of a primary winding and a common potential point, wherein a DC power supply voltage is supplied to a center tap. An electric current flowing into a load is fed back to thereby subject the semiconductor switches to PWM control. Series circuits consisting of capacitors and semiconductor switches are connected between the center tap of the primary winding and the ends of the same. The semiconductor switches are activated in synchronism with the first and second semiconductor switches, thereby preventing occurrence of an anomalous high voltage, which would otherwise be caused at the time of switching operation.

Abstract: A pulse width modulation inverter circuit is provided. The circuit includes a power switch driver, a power switch, a transformer unit, a feedback detector unit, and a voltage control oscillator. The circuit is electrically coupled to the DC power source to drive a load. The circuit adjusts the pulse width of the signal outputted from the power switch driver according to the voltage inputted to the DC power source. Accordingly, the circuit can maintain a fixed input voltage received by the fluorescent tube. Thus, the high input voltage but low output phenomenon can be avoided.

Abstract: A wide-range compatible voltage resonant converter provides high efficiency and allows use of low-breakdown-voltage products for a circuit. The voltage resonant converter is provided with a secondary-side parallel resonant circuit and a secondary-side series resonant circuit, and a loose coupling state is established in which the coupling coefficient of an isolation converter transformer is about 0.7 or less. Thus, a constant-voltage control characteristic is obtained as a sharp unimodal characteristic, which narrows the switching frequency control region required for stabilization of an output voltage. In addition, a primary-side parallel resonant frequency, a secondary-side parallel resonant frequency and a secondary-side series resonant frequency are set so that a favorable power conversion efficiency is obtained. Moreover, an active clamp circuit is provided to suppress the peak level of a resonant voltage pulse to thereby allow use of low-breakdown-voltage products for a switching element and so on.

Abstract: A low power, high voltage power supply system includes a high voltage power supply stage and a preregulator for programming the power supply stage so as to produce an output voltage which is a predetermined fraction of a desired voltage level. The power supply stage includes a high voltage, voltage doubler stage connected to receive the output voltage from the preregulator and for, when activated, providing amplification of the output voltage to the desired voltage level. A first feedback loop is connected between the output of the preregulator and an input of the preregulator while a second feedback loop is connected between the output of the power supply stage and the input of the preregulator.

Abstract: A programmable AC/DC power converter receives a plurality of input voltages and outputs a single voltage from an input voltage system. A transformer receives the single voltage. One of the plurality of input voltages is provided at a center tap of a secondary winding of the transformer. A transformed voltage is output. A rectifier receives the transformed voltage and outputs a DC voltage. A buck regulator receives a DC voltage, creates a regulated voltage, and outputs the regulated voltage and a regulated current to a portable appliance. A error correction system receives a programming signal and regulated signals and verifies that the regulated signal to programming signal ratio is within an acceptable range.

Abstract: A multiple axis servo control implements a multi-tasking PWM control unit to provide PWM signals for multiple axes in a single unit. A time slice mechanism provides axis selection signals based on a system clock signal to permit control parameters of the selected axis to be processed to control the selected motor drive axis. The single unit PWM control mechanism eliminates complex and costly multiple axis networks typically associated with independent servo motor controls for each axis in a multi-axis system. A single PWM unit implementation also permits the reduction of components for closed loop current control and closed loop velocity control in the multi-axis servo control system.

Abstract: First and second semiconductor switches which are activated alternately are provided between ends of a primary winding and a common potential point, wherein a DC power supply voltage is supplied to a center tap. An electric current flowing into a load is fed back to thereby subject the semiconductor switches to PWM control. Series circuits consisting of capacitors and semiconductor switches are connected between the center tap of the primary winding and the ends of the same. The semiconductor switches are activated in synchronism with the first and second semiconductor switches, thereby preventing occurrence of an anomalous high voltage, which would otherwise be caused at the time of switching operation.

Abstract: The invention relates to a system for controlling the speed of a motor (1) of an electric fan unit comprising a field-effect transistor (3) that controls the motor (1) using pulse-width modulation, the field-effect transistor (3) being connected to a circuit (5) comprising a voltage source (7) and a resistive element (9) in series, the circuit (5) is connected between the gate (G) of the field-effect transistor (3) and a second source (S2) that is connected to a first source (S1) of the field-effect transistor (3), via an inductor (11) in order to allow a reduction in the slope of the current as the field-effect transistor (3) switches.

Abstract: First and second semiconductor switches which are activated alternately are provided between ends of a primary winding and a common potential point, wherein a DC power supply voltage is supplied to a center tap. An electric current flowing into a load is fed back to thereby subject the semiconductor switches to PWM control. Series circuits consisting of capacitors and semiconductor switches are connected between the center tap of the primary winding and the ends of the same. The semiconductor switches are activated in synchronism with the first and second semiconductor switches, thereby preventing occurrence of an anomalous high voltage, which would otherwise be caused at the time of switching operation.

Abstract: There is provided a type of luminous hand including a part made of moulded transparent material that forms a circular head (28, 35) and a body (28, 34) of a hand. In order to direct a portion of a light beam parallel to the axis (15) of the hand towards the interior of the body, the head includes a plurality of reflectors (40, 41) distributed around the axis and formed by dihedron shaped hollows. This improves the intensity and uniformity of the light in the hand body. Inclined light-diffusing surfaces, covered with a light coloured paint, are arranged on the bottom face of the hand. In a display device with several coaxial hands (11,12) such as that of a watch, the reflectors of the superposed heads (29, 35) of the hands are located at respective distances from the axis which are different from one hand to another, such that they never completely cover each other. The light source preferably includes three light-emitting diodes (23) located under the dial (10).

Abstract: In a switching power supply and a control method for the same in accordance with the present invention, a first error amplifier generates a first error signal by comparing the output signals of a plurality of converters with a reference voltage, an arithmetic unit generates a single output signal by adding the currents output from the rectifying means of the plurality of converters, a second error amplifier generates a second error signal by comparing the single output signal with the output of the first error amplifier, and PWM signal generators generate PWM signals on the basis of the output signal of the second error amplifier to PWM control each of a plurality of switching devices.

Abstract: A synchronous rectifier circuit, comprising a power transformer which has a primary side, including first and second primary winding sections, and a secondary side, including first and second secondary winding sections, a rectifier circuit at the secondary side of the power transformer, which rectifier circuit comprises first and second MOSFETs associated with the first and second secondary winding sections, respectively, first and second current transforming means associated with the first and second secondary winding sections, respectively, and first and second drive circuits for the first and second MOSFETs, respectively, each current transforming means generating first and second currents which are dependent on the current of the associated secondary winding section of the power transformer, and each drive circuit comprising first and second branches to receive the first and second currents, respectively, generated by the current transforming means, and the first branch comprising a diode and a transcondu

Abstract: A compact high-power pure-sinewave inverter amenable to mass manufacturing techniques. Methods for increasing the power rating, power density and/or power conversion efficiency of a sinewave-modulated pulse-width-modulated (PWM) inverter having a either half-bridge or full-bridge topology, including minimizing uncoupled inductances and loop inductances in the primary winding(s) by employing either ribbon-like conductors having a high crossectional aspect ratio or litz-wire. A compact linear heatsink adapted to cool a row of semiconductor devices (such as inverter switches) mounted on a high-current printed circuit board. Methods for inexpensive manufacture of a fluid-cooled linear heat sink. A transformer including a filter inductor core.

Abstract: A bootstrap capacitor charging circuit comprising first and second power switching transistors arranged in a half bridge arrangement such that the first and second transistors are disposed between a high side potential and a low side potential, a driver circuit for driving the first and second transistors, a bootstrap capacitor adapted to be charged from a potential source and for providing a voltage source to power an electronic circuit, a charging circuit providing a charging path from one of the high and low side potentials to the bootstrap capacitor, first and second series connected switches arranged between a common node of the first and second transistors and one of the high and low side potential, the bootstrap capacitor having a first terminal coupled to be charged by the charging circuit and a second terminal coupled to a common node between the first and second series connected switches; and a control circuit operating in first and second modes, wherein in a first mode when the first and second pow

Abstract: A high power inverter using toroidal transformer with a first end and a second end. A first and second switch for switching the first end and the second end of the transformer primary alternately to ground during alternate half cycles for first and second on-time intervals. a pulse-width modulator and driver circuit for driving the first and second switch into conduction and for modulating the first and second on time intervals. A non-conductive interval is interposed between switch on-times. A control circuit for sensing the output voltage to maintain the output voltage within a predetermined range. An acoustic reference for a clock circuit, the clock circuit controlling the start of each power cycle. A current sense circuit for signaling overload when the on-voltage across the switching means exceeds a predetermined threshold. A switch for connecting the first and second ends of the transformer primary together between on-times.

Abstract: The use of low permeability magnetic material (NSME) with the disclosed design strategies form a two-stage isolated output converter system with the distinct advantages of superior density, efficiency, thermal operating bandwidth, service life, transient survival, and form factor flexibility over the prior art. These improvements are realized by, optimized application of NSME, efficient rectifying flyback management techniques, inclusion of switching buffers that substantially reduce switching losses. The instant invention provides power factor correction, output regulation, inrush limiting, over voltage, over current, over temperature, and transient protection, multi-converter load sharing, hot swapability, and fault signals. The disclosed system is designed, specified, and certified to function from ?40 deg. C. to +65 deg. C. from a 180 vac to 264 vac 50/60 Hz input line and supports 1000 watts of output or 600 watts from 90 vac to 120 vac 50/60 Hz line input at greater then 0.

Abstract: Modulation control circuitry modulates the equivalent output resistance of a power converter, for example a Sine Amplitude Converter, by varying the ON resistance of the primary switches in the converter. The modulation control circuitry may be used to “soft-start” the converter, perform output current limiting, and to improve current sharing between converters in a power sharing array. Soft-start may be achieved by controlling the rate of rise of the peak voltage applied to the gate control inputs of the primary switches. As the gate voltage passes through a range near the threshold voltage of the primary switches, the ON resistance of the switches, and the equivalent output resistance of the converter, will vary smoothly from a relatively high value to a relatively low value. Current limiting may be accomplished by measuring the output current of the converter and controlling the gate voltages of the main switches in order to keep the current at or below a predetermined level.

Abstract: A Factorized Power Architecture (“FPA”) includes a power regulator providing controlled DC bus voltages distributed and converted to load voltages, at the load, using DC voltage transformation modules (“VTMs”) having fixed transformation ratios. Optional feedback from the load improves regulation. A Sine Amplitude Converter (“SAC”) VTM locks the conversion frequency to resonance of a resonant circuit including a transformer, uses complementary primary switches, balanced switching, and a high conversion duty cycle, and may use primary ZVS and secondary ZVS and ZCS, low Q, and a low profile core structure, and may exhibit greater than 400 Watts/cubic-inch power density and 95% efficiency. Common-source gate-control topologies efficiently drive switches higher than 1 MHz. Symmetrical power trains reduce common-mode noise. Modulated converter output resistance controls Vout, limits Iout, or improves current sharing. Gate drive circuitry recycles energy from the transformer magnetizing inductance.

Abstract: A PWM circuit is provided that is capable of PWM control with duties in a range of 0-100%, and that is also capable of high-speed responses.

Abstract: A current detection method for an electric motor which detects phase currents of the electric motor driven by a power converter that provides ON/OFF control of bridge-connected switching elements, based on a pulse-width modulation excitation pattern, to convert a direct current into poly-phase alternating currents. The method includes connecting a current detecting element which produces a signal corresponding to a current value at the direct current side of the power converter and changing the pulse-width modulation excitation pattern by executing a shift of time of any of the phases of the pulse-width modulation excitation pattern so that a signal directly or indirectly corresponding to the phase currents is produced at the current detecting element. The method also includes detecting the phase currents of the electric motor based on the signal produced at the current detecting element and the excitation pattern which has been changed.

Abstract: A drive circuit for a synchronous rectifier of a switch mode power converter is disclosed. The switch mode power converter may include a main power transformer and a primary switch for cyclically coupling the main power transformer to an input source. The drive circuit may comprise a turn-on switch, a turn-off switch, a charge pump and a pulse transformer. The charge pump may be coupled to a secondary winding of the main power transformer. The turn-on switch is for turning on the synchronous rectifier and may be coupled to the charge pump. The pulse transformer may include primary and secondary windings, wherein the primary winding is responsive to a control signal supplied to the primary switch. The turn-off switch is for turning off the synchronous rectifier and may include a control terminal coupled to the secondary winding of the pulse transformer.

Abstract: The voltage applied to a first grid electrode 71 of an X-ray tube 11 by a grid voltage control section 110 is controlled with reference to a predetermined negative voltage from a negative voltage generating section 112 when an object 5 to be inspected does not exist in an imaging area (irradiation area of an X-ray from an X-ray source 1) so that the pulse outputted from a pulse generator 105 is in its OFF state, and is controlled with reference to a reference positive voltage from a reference voltage generating section 115 when the object 5 to be inspected exists in the imaging area in the X-ray image intensifier 2 (irradiation area of the X-ray from the X-ray source 1) so that the pulse outputted from the pulse generator 105 is in its ON state, whereby both of the cutoff voltage and grid operating voltage are applied in a stable state.

Abstract: A DC/DC converter interconnecting a first DC voltage source having a first potential and a second DC voltage source having a second potential and having a stepup/stepdown transformer coupled between the two voltage sources; a controlled switching circuit coupled to the transformer for switching pulsed direct current through the transformer between the voltage sources; and a controller controlling a switching operation of the switching circuit to allow the pulsed direct current to flow between the two voltage sources, whereby current flows between the two voltage sources in dependence on load demands imposed on respective ones of the two voltage sources.

Abstract: A method and apparatus for generating an AC voltage in a system frequency range from a DC input voltage. Two opposite-pole, pulse-width modulated (PWM) rectangular pulses having a high switching rate are applied to the primary winding of a transformer. Every pulse is modulated to correspond to a half-wave of the AC voltage to be generated. On the secondary side of the transformer, the impulses of both PWM pulse trains are rectified to create a pulse train of a single polarity, the pulse width modulation of which corresponds to subsequent half-waves of the AC voltage to be generated. The pulse train so obtained is periodically commutated at double the frequency of the AC voltage to be generated so that a PWM signal representative of the AC output voltage is obtained with respect to amplitude, frequency, and polarity.

Abstract: Disclosed is a circuit for regulating a power supply. In one embodiment, the circuit includes a signal generator for generating a square wave signal that varies in magnitude between a first voltage and a second voltage, and a voltage regulation circuit. A duty cycle of the square wave generated by the signal generator varies according to a signal provided to the signal generator. The voltage regulation circuit, coupled to the signal generator, outputs a DC voltage in response to the circuit receiving the square wave signal. The magnitude of the DC voltage varies between the first voltage and a third voltage, wherein the third voltage is greater than the second voltage, and wherein the magnitude of the DC voltage varies directly with the duty cycle of the square wave signal.

Abstract: The use of low permeability magnetic material (NSME) with the disclosed design strategies form a two-stage isolated output converter system with the distinct advantages of superior density, efficiency, thermal operating bandwidth, service life, transient survival, and form factor flexibility over the prior art. These improvements are realized by, optimized application of NSME, efficient rectifying flyback management techniques, inclusion of switching buffers that substantially reduce switching losses. The instant invention provides power factor correction, output regulation, inrush limiting, over voltage, over current, over temperature, and transient protection, multi-converter load sharing, hot swapability, and fault signals.

Abstract: A power source with an arrangement for restricting short-circuit current includes at least a primary-side switch block, a transformer unit and a rectifier. The rectifier includes switching transistors for rectifying the secondary side of the transformer. Operation of the rectifier depends on a control from a pulse-forming part of the primary-side switch block. Control for the switching transistors in the rectifier is interrupted when the output current of the rectifier exceeds a limit value. At least one other switch element is arranged parallel to each of the switching transistors in the rectifier to realize a secondary-side rectification in an overload situation.

Abstract: The speed of a fan motor is controlled by varying a DC voltage to the fan motor. A series pass transistor is used to vary the DC voltage to the fan motor. A power management controller sets the fan motor speed by outputting pulses to a pulse-to-DC voltage converter that changes the pulses to a proportional DC control voltage for controlling the series pass transistor. A tachometer output amplifier circuit is used to remove DC components and amplify to useful logic levels a low level tachometer output signal from the fan motor. The amplified tachometer signal is used by the power management controller in controlling the rotational speed of the fan motor.

Abstract: A novel gate driver apparatus in which an energy recovery circuitry is incorporated in a square-wave gate driver. The energy recovery circuitry has a first loop circuit for discharging the energy from the gate capacitor to an inductor when the gate driver is turned off, and a second loop circuit for discharging the energy from the inductor to the power supply. Thus, the energy of the gate capacitor is transferred to the power source when the gate driver is turned off, and the gate driver apparatus still maintains its operating flexibility as the square-wave driver and is independent of switching frequency.

Abstract: A power converter circuit is disclosed. The power converter circuit comprises an oscillator for receiving an input wherein the oscillator operates with a fixed frequency and a resonant circuit coupled to the oscillator, wherein the resonant circuit is adjusted to minimize switching losses. Through the use the power converter circuit in accordance with the present invention, high switching losses are avoided thereby resulting in an increase in the overall efficiency of the power converter circuit.

Abstract: A control scheme for a synchronous rectifier converter that avoids disabling the synchronous rectifiers entirely. Rather than disable the synchronous rectifier altogether to stop the flow of reverse current in light-load, startup, or shutdown conditions, the duty cycle of the synchronous rectifier is modified such that forward current is always allowed to flow through the synchronous rectifier, but the synchronous rectifier is turned off before the reverse current flow reaches a pre-determined level. This is accomplished by operating the converter in a partially synchronous mode of operation during light-load, startup, or shutdown conditions. Whether the circuit is in a light-load, startup, or shutdown condition is determined by a circuit characteristic of the converter that is sensed by the controller, such as average output current. The desired changeover point from fully-synchronous mode to the partially synchronous mode is set to a predetermined level of output current for the converter.

Abstract: A high magnitude potential supply comprises a first circuit for generating a first signal related to a desired output high magnitude potential across a pair of output terminals of the supply, a second circuit for generating a second signal related to an output current from the high magnitude potential supply, and a third circuit for supplying an operating potential to the high magnitude potential supply so that it can produce the high magnitude operating potential. The third circuit has a control terminal. A fourth circuit is coupled to the first and second circuits and to the control terminal. The fourth circuit receives the first and second signals from the first and second circuits and controls the operating potential supplied to the high magnitude potential supply by the third circuit. A fifth circuit is provided for disabling the supply of operating potential to the high magnitude potential supply in certain conditions so that no high magnitude operating potential can be supplied by it.

Abstract: The switching power supply comprises a main circuit having a switching circuit for converting a DC input voltage to an AC voltage and an output circuit for rectifying the AC voltage to generate a DC output voltage, a control circuit for controlling the operation of the main circuit, and an abrupt load change detector circuit for detecting an abrupt change in the load current supplied from the main circuit, characterized in that the abrupt load change detector circuit comprises a first filter and a second filter for receiving the output voltage and detection signal generating means for generating an abrupt load change detection signal based on the outputs of the first filter and the second filter. This eliminates a power loss or operation delay caused when a resistor or a current transformer is used to directly detect the output current. Proper use of an abrupt load change detection signal allows dramatic improvement in transient response.

Abstract: A high magnitude potential supply comprises a first circuit for generating a first signal related to a desired output high magnitude potential across a pair of output terminals of the supply, a second circuit for generating a second signal related to an output current from the high magnitude potential supply, and a third circuit for supplying an operating potential to the high magnitude potential supply so that it can produce the high magnitude operating potential. The third circuit has a control terminal. A fourth circuit is coupled to the first and second circuits and to the control terminal. The fourth circuit receives the first and second signals from the first and second circuits and controls the operating potential supplied to the high magnitude potential supply by the third circuit. A fifth circuit is provided for disabling the supply of operating potential to the high magnitude potential supply in certain conditions so that no high magnitude operating potential can be supplied by it.

Abstract: Universal switched power converter having a transformer that comprises a first winding (11-3) divided into two parts and having an intermediate tap (11-3-1), and a second winding (11-9) connected in cascade with rectifier means (12) and filter means (13), so that a first current flows through the part of said first winding (11-3) comprised between the end of the primary winding (11-3) connected to a first input terminal (11-1) and the intermediate tap (11-3-1) and through a second switching element (11-6) connected to the intermediate tap (11-3-1) and to a second input terminal (11-2), when the input voltage applied across the input terminals (11-1, 11-2) is close to a first predetermined voltage value and the second switching element (11-6) is in a conducting state.

Abstract: A high magnitude potential supply comprises a first circuit for generating a first signal related to a desired output high magnitude potential across a pair of output terminals of the supply, a second circuit for generating a second signal related to an output current from the high magnitude potential supply, and a third circuit for supplying an operating potential to the high magnitude potential supply so that it can produce the high magnitude operating potential. The third circuit has a control terminal. A fourth circuit is coupled to the first and second circuits and to the control terminal. The fourth circuit receives the first and second signals from the first and second circuits and controls the operating potential supplied to the high magnitude potential supply by the third circuit. A fifth circuit is provided for disabling the supply of operating potential to the high magnitude potential supply in certain conditions so that no high magnitude operating potential can be supplied by it.

Abstract: The present invention comprises an isolated dual power supply having an internal feedback loop. The dual power supply comprises a modulated switched power converter generating an internal regulated voltage output coupled to an alternating current tank. The alternating current tank has a first and a second power switch that are alternately switched ON at a 50% duty cycle. When the first switch is ON, the internal regulated voltage output is coupled to a storage capacitor and a primary winding of a transformer in the alternating current tank wherein the storage capacitor is charged and a current flows in a first direction through the primary winding. Alternatively, when the second switch is ON, the charged storage capacitor discharges and a current flows in a second direction opposite to the first direction through the primary winding. In this fashion, the transformer becomes a linear device, allowing the use of internal feedback to control the external output of the transformer.

Abstract: The present invention comprises an isolated dual power supply having an internal feedback loop. The dual power supply comprises power converter responsive to an error signal for generating a DC internal regulated output voltage coupled to a DC/AC switching power converter having a transformer. The primary winding of the transformer is coupled to the DC internal output voltage and to one or more power switches. A control circuit drives the one or more power switches such that an alternating current having substantially a constant duty cycle flows through the primary winding. An error amplifier produces a control signal proportional to the difference of an output voltage at a load coupled to the secondary winding and a reference voltage equal to the maximum expected voltage losses at the load. The error signal is formed from a combination of the control signal and a signal proportional to the internal voltage output.

Abstract: A coupling circuit for charging a pulse forming network (PFN) or capacitor load to a precise voltage is disclosed. The coupling circuit is connected to a DC input voltage source. The circuit includes a charging transformer, having an input winding connected in series with a switch circuit and the DC voltage source. The output winding of the charging transformer is connected to the PFN or capacitor load. A charging inductor is placed in series with the output winding. A control circuit monitors and calculates the total amount of energy present at the load and the charging inductor, and causes the switch circuit to open when the total charge reaches a predefined level, thereby allowing charge stored in the inductor to be transferred to the PFN or capacitor load.

Abstract: An output voltage regulation system allows independent output regulation of multi-output dc-dc switched-mode power converters. The channel resistance of MOSFET synchronous output rectifiers are controlled to obtain the voltage drop required to keep the respective output between predetermined limits concurrent with wide excursions in output load. A typical circuit has a transformer with an input winding coupled to a dc source. A transformer has at least a first and second output winding. A switched-mode regulator means samples a portion of the first output voltage and provides at least a first pulse-width modulated drive voltage having a first state and a second state to a first input semiconductor switch control terminal. The drive voltage first state turns the input semiconductor switch on and the drive voltage second state turns the input semiconductor switch off.

Abstract: An AC active clamp, a method of operating the same and a power factor corrector employing the AC active clamp or the method. The power factor corrector has a primary switching circuit coupled to a primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. The primary switching circuit has first and second power switches configured to receive unrectified AC power. In one embodiment, the AC active clamp includes a switching circuit having first and second clamping switches series coupled in opposition and a capacitor coupled to the switching circuit. The switching circuit and the capacitor are coupled across at least a portion of the primary winding and are configured to mitigate adverse effects of a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of the first and second power switches of the primary switching circuit.

Abstract: A power conversion system configured for converting electrical power at an input voltage to an output voltage by means of synchronous rectification includes a first pulse width modulator for receiving the input voltage and a synchronization signal to produce a digital error signal, and a second pulse width modulator for receiving the digital error signal at a synchronization port. The pulse width modulators produce respective digital signals which are converted into output analog power signals by transformer and rectifier sections. An error detector compare the voltage of the output power to a predetermined voltage level and produce an analog error feedback signal for transmission to the first pulse width modulator.

Abstract: A power supply (500) with vertical field effect transistor synchronous rectifiers (VFET1 and VFET2) having drivers (VFET Driver1 and VFET Driver2) which provide bipolar mode of operation by diode clamping an inductor overshoot which forwards biases the gate-source junction. The rectifiers have low on resistance useful in low output voltage power supplies.

Abstract: A DC to DC converter that uses three switching devices and processes power in such a way that it can operate very efficiently. The converter only processes that portion of the input power that is required to provide regulation. In addition, by judiciously selecting magnetic components and turns ratios, the converter can be optimized for narrow input voltage ranges or for wide input voltage ranges. The converter operates in such a way that it can add or subtract energy on the primary side of the converter to achieve regulation.