Abstract: Methods and apparatus for a dc-dc converter for operating at substantially fixed switching frequency, the converter including a rectifier, and a resonant inverter coupled to the rectifier, the resonant inverter including a switch and a reactive network having first, second, third and fourth energy storage elements, wherein an impedance magnitude at the output of the switch due to the reactive network has minima at dc and at a frequency near a second harmonic of the switching frequency.

Abstract: A control unit controls cascaded PFC and LLC converters, the LLC converter having an input coupled to an output, of the PFC converter and providing an output voltage that decreases with increasing switching frequency. The control unit produces a sawtooth waveform with a linear ramp for controlling the LLC converter switching frequency, and hence its output voltage, in dependence upon a feedback signal. It also produces for the PFC converter a PWM signal with a frequency that is the same as or an integer fraction of the LLC converter switching frequency, by comparing two thresholds with the linear ramp in respective different cycles of the sawtooth waveform to turn on and off a switch of the PFC converter during these different cycles. Logic circuits prevent PFC converter switch transitions from occurring simultaneously with switching transitions of the LLC converter.

Abstract: A voltage-regulating circuit according to the present invention includes a power conversion circuit, an input voltage detecting circuit and a feedback circuit. The power conversion circuit includes at least one switch element, wherein during operation of the at least one switch element, an input voltage is converted into a transition voltage. The input voltage detecting circuit is connected to the power conversion circuit for outputting a detected voltage signal corresponding to the input voltage. The feedback circuit is connected to the power conversion circuit and the input voltage detecting circuit for generating a feedback control signal. In such way, as the input voltage is changed, the feedback circuit will adjust to make the transition voltage changed as with the change of the detected voltage signal corresponding to the input voltage.

Abstract: A frequency limitation method used in quasi-resonant control of a switching regulator is disclosed. The switching frequency is limited through setting a minimum time limit, such as a minimum switching period or a minimum OFF time. The minimum time limit may be a first time limit or a second time limit. The minimum time limit is changed into another value if the minimum voltage point approaches the minimum time limit point, so as to eliminate the audible noise.

Abstract: A multi-phase switching power conversion circuit has at least three phases and includes a plurality of switching circuits, a plurality of transformers, a plurality of output rectifier circuits, a resonant network and a control circuit. The resonant network includes a plurality of symmetrical terminals and a plurality of phase branches, which are connected in a multi-phase symmetrical relationship. Each of the symmetrical terminals is connected to the output side of respective switching circuits. The phase branches are connected to a resonant common terminal such that the phase branches are in a star connection. The resonant common terminal is different from the positive terminal and the first reference terminal of the input voltage source. The control circuit is connected to an output terminal of the multi-phase switching power conversion circuit and a plurality of the control terminals of the plurality of switching circuits.

Abstract: The present invention discloses a resonance circuit for use in an H-bridge DC-DC converter, the resonance circuit comprising: an H-bridge converter, capable of converting unstable DC power into stable DC power; a first resonance circuit, disposed on a buck side of the H-bridge converter for reducing the turn-off loss of a first active switching element; and a second resonance circuit, disposed on a boost side of the H-bridge converter for reducing the turn-on loss of a second active switching element. The H-bridge converter comprises: a first active switching element and a second active switching element; a coupled inductor with dual windings capable of storing energy; and a first passive switching element and a second passive switching element.

Abstract: A method of operating a resonant power converter(1, 2), having a high side switch(3) and a low side switch(4), is disclosed in which the switching is controlled to allow for improved operation at low power levels. The method involved an interruption to the part of the switching cycle in which the low side switch (4) is normally closed, by opening the switch at a particular moment in the cycle which allows the energy to be store in the resonance capacitor (5). Since, as a result, the energy is largely not resonating but stored in a single component, the time quantisation of the mode of operation is significantly reduced or eliminated.

Abstract: A resonant power converter including synchronous rectifiers adapted to operate with an overlapping conduction phase and a fixed frequency.

Abstract: The present invention relates to an electronic power converter comprising a piezoelectric transformer, a drive circuit arranged to generate and provide an input voltage signal to the piezoelectric transformer, said input voltage signal comprising a burst frequency and a substantially constant excitation frequency, and a rectifier module. According to the present invention the excitation frequency is selected among a plurality of excitation frequencies in such a way that an equivalent load resistance, Req, is matched to an output impedance of the piezoelectric transformer so as to minimize power losses in the piezoelectric transformer. Moreover, the present invention relates to a method for configuring an electronic power converter.

Abstract: A PWM controlled multi-phase resonant voltage converter may include a plurality of primary windings powered through respective half-bridges, and as many secondary windings connected to an output terminal of the converter and magnetically coupled to the respective primary windings. The primary or secondary windings may be connected such that a real or virtual neutral point is floating.

Abstract: A converter includes a control unit configured to turn ON, when an output voltage is set to a low voltage, a switching element according to a pulse voltage induced in a first auxiliary winding of a transformer. The control unit operates based on a direct current voltage output by rectifying and smoothing a pulse voltage induced in a second auxiliary winding of the transformer.

Abstract: A bi-directional DC-DC converter has a transformer for connecting a voltage type full bridge circuit connected to a first power source and a current type switching circuit connected to a second power source. A voltage clamping circuit constructed by switching elements and a clamping capacitor is connected to the current type switching circuit. The converter has a control circuit for cooperatively making switching elements operative so as to control a current flowing in a resonance reactor.

Abstract: A synchronous rectifier type SRC for operating in an intermittence mode, which includes: an input power for supplying an input DC voltage; an input-side switching unit; a transformer with a primary winding and a secondary winding; an output-side switching unit for switching; and a gate driving circuit for detecting. According to the synchronous rectifier type SRC, a no-load characteristic can be controlled with an easy scheme and a simple construction. In addition, a simple resistor is added, and thus dead time can be generated. Consequently, it is possible to simply reduce switching loss that may occur in zero voltage switching.

Abstract: Provided is a resonance converting apparatus. The resonance converting apparatus preferably includes a resonant circuit, a bridge-type converter, and a synchronous rectification circuit. In which the resonant circuit has a transformer. The bridge-type converter connects with a primary side of the transformer, and operates open or close according to a switching signal. The synchronous rectification circuit further includes a pair of rectification transistors and driving circuits. The driving circuits correspondingly connect with channels to the rectification transistors, and respectively examine the current passing through the rectification transistors. A sensing signal is then generated. In accordance with the switching signal and the sensing signal, a driving signal is generated for driving the rectification transistor. Consequently the apparatus can raise the efficiency of the resonance converting apparatus.

Abstract: A power supply apparatus and method of regulating is provided. A converter circuit includes a primary switching element and an auxiliary switching element. The auxiliary switching element is for transferring a reflected voltage signal. A transformer includes a primary and a secondary, the primary is coupled with the converter circuit. The primary and the secondary each comprise a single winding. An output rectifier circuit is coupled with the secondary of the transformer. A resonant circuit is included in the converter circuit and is coupled with the primary. The resonant circuit includes one or more resonance capacitors that are configured for providing a transformer resonance. The transformer resonance comprises the reflected voltage signal, the capacitance of the one or more resonance capacitors and a parasitic capacitance of the transformer. The reflected voltage signal is reflected from the secondary to the primary. A current feedback circuit is coupled between the primary and a controller.

Abstract: A power supply power supply (30) comprising a DC voltage supply, a control unit and a plurality of high voltage channels (33a-33d) is suggested. Each high voltage channel (33) includes an inverter (IKTV), a resonance circuit, a transformer (TR), and a rectifier (RECT). The resonance circuit cooperates with the inverter (INV). The inverter (INV) is formed by a first switching unit and a second switching unit whereby a voltage of a first polarity can be applied to the resonance circuit in a first switching state, whereas a voltage of a second polarity can be applied to the resonance circuit in a second switching state. The switching states can be switched by the control unit in such a manner that in a first mode of an operation for high output power, the output power can be adjusted by changing the switching frequency in the range of the resonance frequency.

Abstract: A boost device boosts an input voltage to an output voltage across an output capacitor, and includes an output diode coupled to the output capacitor, and a transformer coupled to a first switch, a clamp circuit and a boost circuit. The clamp circuit is coupled across a first winding of the transformer, and includes a clamp capacitor coupled in series to a second switch. The output capacitor is capable of being charged through the output diode with an induced voltage across a second winding of the transformer. The boost circuit is capable of being charged with the induced voltage across the second winding, and of charging the output capacitor so as to boost the output voltage across the output capacitor.

Abstract: An indirect and passive method for AC/DC converter power factor correction is disclosed. The correction is achieved by stabilizing the input impedance of the converter with keeping the inversely proportional dependence between the current iconv(t) and voltage uconv(t) of the output smoothing filter (3). The necessary dependence is achieved by natural characteristics of circuit with passive components. An uncontrolled converter (6) with alternation of parallel and series resonance is used as such circuit. To increase the operating frequency of this converter, a chopper or an inverter is used. The resonant converter decreases the commutation current of the switches. Output voltage is easy to control by pulse width modulation of chopper or inverter. Passive power factor correction results in the total harmonic distortion of main current THDi=10 to 40 per cent. All currents of the converter are limited naturally in all operating modes.

Abstract: A resonant dc-dc converter converts dc input voltage to a dc output voltage. The converter includes switching, switching driving, conversion, and disabling circuits. The switching circuit receives the input voltage and generates a square wave voltage oscillating between the input voltage and a low value, at a frequency with a duty cycle. The switching driving circuit drives the switching circuit and includes a timing circuit for setting the frequency and the duty cycle. The timing circuit sets the value of the duty cycle to about 50% when the converter operates in steady state. The conversion circuit generates the output voltage from the square wave voltage based on the frequency and the duty cycle. The disabling circuit temporarily halts the timing circuit after a power on in such a way to temporarily vary the duty cycle of the square wave voltage during a period of the square wave voltage.

Abstract: A control circuit of the resonant power converter according to the present invention comprises a frequency modulation circuit modulating a switching frequency of a switching signal in response to a feedback signal in a first operation range. A phase-shift circuit performs a phase-shift modulation to the switching signal in response to the feedback signal in a second operation range. A burst circuit performs a burst modulation to the switching signal in response to the feedback signal in a third operation range. The control circuit is operated in the first operation range when the feedback signal is higher than a first threshold. The control circuit is operated in the second operation range when the feedback signal is lower than the first threshold and higher than a second threshold. The control circuit is operated in the third operation range when the feedback signal is lower than the second threshold.

Abstract: A DC-DC converter apparatus comprising half or full bridge, two-stage resonant converter, which may include series resonant (inductor, capacitor) devices. An isolated transformer having primary and secondary winding supplies current to full-wave secondary stage-bridge through the use of primary winding resonant devices employing primary stage-bridge. The magnetizing of said devices employs zero-current, zero-voltage resonant-transition switching technology, which reduces switching losses at all switching frequencies to almost zero. The regulation of output voltage at all loads and input voltages achieved by the control of the switching frequency and the phase between signals for primary and secondary stages. The proper intermittent of the frequency and the phase allows achieving the value of efficiency up to 97%.

Abstract: The present invention discloses a half-bridge LLC resonant converter with self-driven synchronous rectifiers, which utilizes a primary IC controller and a gate driver to drive the secondary synchronous rectifiers. In correspondence with the gate drive output voltages of the primary IC controller to the primary switch transistors, the gate driver for the secondary synchronous rectifiers comprises a differential transformer if the primary IC controller outputs two ground-referenced gate drive voltages, which cannot directly drive the primary switch transistors but can be imposed on the differential transformer; or comprises a DC shifter, a DC restorer and a differential transformer if the primary IC controller outputs two gate-source voltages, which can directly drive the primary switch transistors but cannot be imposed on the differential transformer. The drive voltages of the primary switch transistors are unipolar; however the drive voltage of the secondary synchronous rectifiers can be bipolar or unipolar.

Abstract: A switching mode power supply (SMPS) device includes a power converting part that converts an input voltage into an output voltage according to a switching signal, and outputs a primitive switching signal for use in varying a frequency of the switching signal based on power drawn by a load receiving the output voltage; a resonant circuit that changes a duty ratio of the primitive switching signal using a variable resonant frequency in accordance with a variance of an impedance of the load; and a signal controlling part that compares a voltage of the primitive switching signal, resonated in accordance with the variable resonant frequency, with a reference voltage, and varies the frequency of the switching signal and outputs the switching signal having the varied frequency when the voltage of the primitive switching signal is maintained below the reference voltage for longer than a reference time.

Abstract: The present invention relates to a quasi-resonant converter. In the quasi-resonant converter according to the present invention, a predetermined first period and a second period following to the first period are set. In the second period, a switch is turned on at a time point where voltages at both ends of the switch fall to the minimum if the second period includes the time point, and the switch is turned on at the end of the second period if the second period does not include the time point. Therefore, the switching frequency of the switch can be restricted within a predetermined range.

Abstract: A non-contact power transmission device, which is capable of efficiently reducing the device size and reducing unnecessary radiation of a harmonic component from a primary side coil, is provided. The non-contact power transmission device which includes a primary side unit and a secondary side unit which house a primary side and a secondary side of a coupling transformer individually and can be separated from each other, a capacitor C1 which resonates with a primary side coil L1 is connected to the primary side coil L1 in series so that a primary side series resonance circuit is formed, an L-shaped resonance circuit which has a coil L3 and a capacitor C7 resonating with the coil L3 is inserted between the primary side series resonance circuit and a driving circuit, and the L-shaped resonance circuit is connected to the primary side series resonance circuit in series.

Abstract: In a switching power supply apparatus, an inductor, a transformer, a first switching circuit, a second switching circuit, and a capacitor are connected to each other so that a first switching element and a second switching element can be alternately turned on and off, an output can be obtained from a secondary winding of the transformer, and an output voltage can be controlled by controlling the ON period of the first switching element. The secondary winding of the transformer is connected to a first rectifying and smoothing circuit. A first control circuit is configured to operate using a DC voltage supplied from a second rectifying and smoothing circuit. After the second switching element has been turned on, the second switching element is forcefully turned off at a predetermined time set by a turn-off circuit included in a second control circuit that operates using an AC voltage.

Abstract: A resonant power converter is provided and includes a capacitor, an inductive device, a first transistor, a second transistor, and a control circuit. The capacitor and the inductive device develop a resonant tank. The first transistor and the second transistor are coupled to switch the resonant tank. The control circuit generates a first signal and a second signal to control the first transistor and the second transistor respectively. Frequencies of the first signal and the second signal are changed for regulating output of the resonant power converter. The control circuit is further coupled to detect an input voltage of the resonant power converter. A pulse width of the second signal is modulated in response to change of the input voltage.

Abstract: A light emitting diode (LED) driving device includes a power factor correction (PFC) circuit, a bridge switch circuit, a resonant circuit, a transformer and a feedback circuit. The PFC circuit adjusts an output signal thereof based on a feedback signal. The bridge switch circuit transforms the output signal of the PFC circuit into a pulse signal. The resonant circuit resonates and outputs a sinusoidal signal to a primary-side of the transformer based on the pulse signal. The feedback circuit outputs the feedback signal to the PFC circuit in response to a primary-side current of the transformer. Therefore, an output current of the LED driving device is adjusted through modulating the feedback circuit.

Abstract: A DC power source device is provided which comprises conduction detectors 17, 18 for producing detection signals VP1, VP2 during the detective period of rectification MOS-FETs 15, 16 and timer circuits 19, 20 connected to polarity detectors 17, 18. Timer circuits 19, 20 count output time of detection signal VP1, VP2 from polarity detectors 17, 18 until electric current through one of rectification MOS-FETs 15, 16 comes to zero, and turns the other of rectification MOS-FETs 15, 16 off immediately before termination of the counted time so that timer circuits 19, 20 can reliably turn rectification MOS-FETs 15, 16 off during the conductive period of forward current flow for efficient synchronous rectification.

Abstract: An exemplary DC to DC converter (200) includes a first DC input (210) connected to a first DC power supply; a second DC input (220) connected to a second DC power supply; a transformer (230) including a primary winding (231), a sub-primary winding (232), and a secondary winding (233) for outputting a AC voltage; a pulse reverse circuit (260) including an input for receiving a square pulse and an output for providing the reverse square pulse; a first switch transistor (240) including a source connected to ground, a drain connected to the first DC input via the primary winding, and a gate connected to the output of the pulse reverse circuit; a second switch transistor (250) including a source connected to ground, a drain connected to ground via the sub-primary winding and a capacitor in series, and a gate connected to the output of the pulse reverse circuit.

Abstract: An apparatus and a method for converting power from a power input to an DC output voltage or current, which apparatus has a serial resonance converter, where a first feedback circuit is connected from the output terminal to an error amplifier, where the apparatus further has a second feedback circuit with at least one first resistor that is connected to a coil and to ground, which second feed back circuit connects the line between the first resistor and the coil and towards an inverting integrator, the output of which is connected through a second capacitor to a second input at a control circuit. As a result, the oscillating frequency is under influence of a signal that depends on the voltage generated in the resistor connected in serial to the coil or transformer.

Abstract: A power converter includes a transformer, a primary switch, an auxiliary switch, first and second resonance capacitors, and a secondary side rectification means. A switch mode power supply is formed to use reflected voltage and parasitic capacitance as an energy source for a transformer resonance. The auxiliary switch effectively exchanges energy between the primary inductance of the transformer and the first and second resonant capacitors. The auxiliary switch effectively switches the transformer resonance between two distinct frequencies. In one embodiment of the invention, the power converter can be, but is not limited to, a flyback converter and further includes a comparator and a driver. The comparator is for detecting the voltage across the second resonance capacitor and the driver is configured to drive the auxiliary switch based on the output state of the comparator. The resonant nature of the converter provides zero voltage (ZVS) for the primary switch as well as for the auxiliary switch.

Abstract: A plurality of power supply circuits Z1? are provided according to a load capacity. The power supply circuits Z1? have sides connected in parallel on the side of a direct current input Vi and have sides connected in series on the sides of alternating current outputs Ao. A rectifying circuit DC1 is connected via a resonance circuit Z2 across a combined output of the serially connected sides of the power supply circuits Z1? on the sides of the alternating current outputs Ao. Switching frequencies are simultaneously controlled by a single control signal outputted from a control circuit S1 based on a direct current output voltage detected from the rectifying circuit DC1 through a detection resistor R5.

Abstract: The present invention provides a switching circuit to regulate an output voltage and a maximum output current at the primary side of a resonant power converter. The switching circuit includes a pair of switching devices and a controller. The controller is coupled to a transformer to sample a voltage signal thereof and generates switching signals to control the switching devices. The switching frequency of the switching signals is increased in response to the decrease of the output voltage. The increase of the switching frequency of the switching signals decreases the power delivered to the output of the resonant power converter. The output current is therefore regulated.

Abstract: A resonant converter equipped with a phase shifting output circuit includes a resonant circuit to receive input power and regulate to become at least one resonant power, a switch unit to switch an ON period for the input power to pass through the resonant circuit and a power transformation circuit to regulate the resonant power and output a transformed power. The resonant converter further has a primary output circuit and at least one secondary output circuit. The primary output circuit regulates the transformed power to become a primary output power. A resonant control unit captures a feedback signal from the primary output circuit and generates a resonant control signal. A phase shifting control unit receives the resonant control signal and regulate to become a phase shifting driving signal. The secondary output circuit is controlled by the phase shifting driving signal and provides a secondary output power.

Abstract: A power supply apparatus and method of regulating is provided. A converter circuit includes a primary switching element and an auxiliary switching element. The auxiliary switching element is for transferring a reflected voltage signal. A transformer includes a primary and a secondary, the primary is coupled with the converter circuit. The primary and secondary each include a single winding. An output rectifier circuit is coupled with the secondary of the transformer. A resonant circuit is included in the converter circuit and is coupled with the primary. The resonant circuit includes one or more resonance capacitors that are configured for providing a transformer resonance. The transformer resonance comprises the reflected voltage signal, the capacitance of the one or more resonance capacitors and a parasitic capacitance of the transformer. The reflected voltage signal is reflected from the secondary to the primary.

Abstract: To provide a power supply circuit which can be applied worldwide without using a high withstand voltage switching element and can supply a load device with stable power. A charging section is arranged between a turn-off capacitor and a load coil. The charging section has the anode connected to the positive terminal of a feedback coil and the cathode connected to the cathode of a zener diode. Thus, when a voltage of a commercial power supply is high, the charging section operates, the turn-off capacitor is quickly charged, an on-period of a transistor is shortened, and an excessive voltage is prevented from being applied between the drain and the source of the transistor. At the same time, an output characteristic indicating relationship between the voltage of the commercial power supply and a current flowing in the load device is permitted to be flat.

Abstract: The invention provides a switching power supply device which can detect a light load state on a pulse-by-pulse basis without worsening power efficiency. In a synchronous control circuit, for each timing of the turning-on of main switching elements, the delay time Tdif of the conduction timing of internal diodes Ds determined according to the magnitude of the load LD is detected by a comparator, a reference time pulse Tsrs having a prescribed time width is generated by a load judgment circuit, and the logical product of the two is generated by an AND circuit. By this means, the load is regarded as being a light load when the delay time Tdif is longer than the reference time pulse Tsrs, and the synchronous rectification MOSFETs Qs are not turned on.

Abstract: A synchronous rectifier circuit of a switching power converter is provided and includes first and second power transistors and first and second diodes connected to a transformer and an output of the power converter for rectifying. An arbiter circuit generates a lock signal to prevent the second power transistor from being turned on when the first diode the first power transistor is turned on. A controller generates a drive signal to control the first power transistor according to an on signal and an off signal. A phase-lock circuit generates the off signal according to the on signal. The on signal is enabled once the first diode is forward biased. The one signal enables the drive signal for turning on the first power transistor. The off signal disables the drive signal for turning off the first power transistor. The off signal is enabled before the disabling of the on signal.

Abstract: This invention relates to control techniques and controllers for resonant discontinuous forward power converters (RDFCs). A controller for a resonant discontinuous forward converter (RDFC), said converter including a transformer with primary and secondary matched polarity windings and a switch to, in operation, cyclically switch DC power to said primary winding of said transformer, said converter further having a DC output coupled to said secondary winding of said converter, said controller having a primary sense input to sense a primary winding signal, said primary winding signal representing a voltage across said primary winding or across an additional winding coupled to said primary winding, and wherein said controller is configured to switch on said switch in response to detection of a reduction in a rate of change of said primary winding signal below a threshold, adjacent a substantially minimum value in an operational cycle of said sensed primary winding signal to convey power to said DC output.

Abstract: A universal input switching power supply has the rectifier, a signal detecting unit detecting a voltage of an external AC power and outputting a detecting signal, a PFC circuit converts a first DC power from the rectifier to a second DC power with different voltage according to the detecting signal; and a parallel and serial type DC to DC converter converting the second DC power with different voltage to a constant voltage of the third DC power. The parallel and serial type DC to DC converter has a transformer having a primary and secondary coils and physically changes a turn ratio of the primary and secondary coils of a transformer thereof according to a voltage ratio of the second DC power and the third DC power. Accordingly, the universal input switching power supply has good transforming efficiency at different AC power source conditions.

Abstract: Disclosed is a bi-directional battery power inverter (1) comprising a DC-DC converter circuit element (3) to which the battery (2) can be connected in order to generate an AC output voltage from a battery (2) voltage in a discharging mode while charging the battery (2) in a charging mode. The inverter (1) further comprises an HF transformer which forms a resonant circuit along with a resonant capacitor (6). In order to increase the efficiency of said battery power inverter, the transformer is provided with two windings (11, 12) with a center tap (20) on the primary side, said center tap (20) being connected to a power electronic center-tap connection with semiconductor switches (21, 31) while a winding (13) to which the resonant capacitor (6) is serially connected provided on the secondary side.

Abstract: This invention relates to control techniques and controllers for resonant discontinuous forward power converters (RDFCs). We describe a controller for a resonant discontinuous forward converter (RDFC), said forward converter including a transformer with first and second matched polarity windings and a switch to switch dc power to said first winding of said transformer, said converter further having a dc output coupled to said second winding of said transformer, and wherein said controller has two modes, a first operational mode during which said switch is controlled to switch said dc power at a frequency which substantially coincides with a resonant frequency of operation of said RDFC such that said RDFC supplies power from said dc output, and a second, reduced power operational mode during which a drive to said switch is controlled to increase a proportion of time during which said switch is off.

Abstract: A switching power source device which has main switch elements which switch a current path of the series resonant circuit, and a transformer which induces a current to a secondary side, controls the main switch elements on a primary side. Synchronous rectification switch elements are turned ON and OFF in response to one of the main switch elements. A synchronous control circuit which turns the synchronous rectification switch element ON in synchronization with an ON timing of the main switch element, or a conduction timing of internal diodes in the synchronous rectification switch elements detected by an inter-terminal voltage signal of the synchronous rectification switch element, whichever timing is later, determines a maximum ON width of the synchronous rectification switch element in accordance with a delay time of the conduction timing of the internal diodes with respect to the ON timing of the main switch element.

Abstract: A control circuit for a switch unit of a clocked power supply circuit, the switch unit being designed to effect input-side excitation of a resonant transformer arrangement, comprises an input for receiving an auxiliary signal from the resonant transformer arrangement. The auxiliary signal exhibits an essentially fixed phase relation to a load alternating current flowing through a resonant circuit of the transformer arrangement. The control circuit further comprises a phase detector designed to detect reference crossing moments when the auxiliary signal crosses a predefined reference value, a driver controllable to switch the switch unit, and a synchronization means designed to synchronize a turn-on of the switch unit by the driver with regard to a phase position with the auxiliary signal so as to achieve a turn-on of the switch unit within a predetermined time interval around a zero crossing of a voltage present across the switch unit, or of a current flowing through the switch unit.

Abstract: A synchronous rectifier of a resonant switching power converter is provided to improve efficiency. The synchronous rectifier includes a power transistor and a diode connected to a transformer and an output of the resonant switching power converter for ratifications. A controller generates a drive signal to control the power transistor in response to an on signal and an off signal. A causal circuit is developed to generate the off signal in accordance with the on signal. The on signal is enabled once the diode is forward biased. The on signal is coupled to enable the drive signal for switching on the power transistor. The off signal is coupled to disable the drive signal for switching off the power transistor. The off signal is enabled before the on signal is disabled.

Abstract: A control device for a rectifier of a switching converter, the converter powered by an input voltage and suitable for providing an output current. The rectifier is suitable for rectifying an output current of the converter and includes at least one transistor. The control device is suitable for driving the at least one transistor. The control device has a first circuit suitable for identifying the start and the end of every converter switching half-cycle and measuring the duration thereof, a second circuit suitable for generating a signal for turning on the transistor after a given number of measured converter switching half-cycles and when the output current of the converter becomes greater than a reference current.

Abstract: The present invention provides a resonant converter with a synchronous rectification drive circuit. The resonant converter with the synchronous rectification drive circuit includes a switch circuit, a resonant circuit, a transformer, a full-wave-rectifier circuit and a synchronous rectification drive circuit, wherein the switch circuit at least includes a half-bridge circuit, the resonant circuit is coupled to the switch circuit and has a resonant frequency, the transformer has a primary side coupled to the resonant circuit, the full-wave-rectifier circuit is coupled to a secondary side of the transformer and includes two switches, the synchronous rectification drive circuit includes four voltage-clamped drive circuits having output terminals coupled to the switch circuit and the corresponding switch of the full-wave-rectifier circuit, and each voltage-clamped drive circuit includes a transmission/discharge circuit for reducing the turn-off period of the coupled switch during turning off the coupled switch.

Abstract: We describe a resonant discontinuous power converter including a magnetic energy storage device, and a bipolar junction transistor (BJT) switch having a collector terminal coupled to repetitively switch power from the input on and off to said magnetic energy storage device such that power is transferred from the input to the output. During an off-period of said BJT switch a voltage on said magnetic energy storage device and on said collector terminal of said BJT is at least partially resonant. The power converter includes a voltage clamping circuit to clamp a base voltage on a base terminal of said BJT during a resonant portion of said off-period to limit an excursion of a collector voltage on said collector terminal of said BJT towards or beyond an emitter voltage of said BJT during said resonant portion of said off-period, in particular to inhibit reverse bias of a base emitter junction of the transistor.

Abstract: A resonant switching power source device is provided which comprises first and second MOS-FETs 1 and 2 connected in series to a DC power source 3, a first transformer 5 which has a first primary winding 5a connected in parallel to first or second MOS-FET 1 or 2 and in series to a first capacitor 4, a first rectifying smoother 10 connected between a secondary winding 5b of first transformer 5 and first output terminals 11, 12, a second transformer 6 which has a primary winding 6a connected in parallel to primary winding 5a of first transformer 5, and a second rectifying smoother 20 and an output-regulatory MOS-FET 41 connected between a secondary winding 6b in second transformer 6 and second DC output terminals 21 and 22 to control peak current flowing through primary windings of transformers 5 and 6 and rectifying smoothers 10 and 20 in secondary sides for improvement in power conversion efficiency and to produce stable DC outputs of desired level from a plurality of output terminals 11, 12, 21 and 22.