Abstract: A VHF switching power converter comprising one or more VHF switching frequency resonant synchronous rectifiers receives an output from an inverter and delivers a DC output to a load. The power converter includes a controller for controlling at least one of the one or more VHF switching frequency resonant synchronous rectifiers based on feedback derived from a waveform of at least one of the rectifiers. The controller controls a phase angle of at least one of the rectifiers with a delay locked loop. The power converter delivers a regulated DC output via adjustment of a phase shift between at least one of the one or more rectifiers and the inverter.

Abstract: The invention relates to a switch control circuit, a power supply including the same, and a method for driving the power supply. The power supply includes: a first switch; a second switch coupled in series to the first switch; a transistor coupled to a node where the first switch and the second switch are coupled; a resonance capacitor coupled between the transformer and a primary side ground and to which a resonance current flows; a sense circuit generating a first sense voltage that depends on the resonance current when the resonance current is a positive current; and a switch control circuit detecting a zero voltage switching failure by sensing the resonance current using the first sense voltage at a turn-off time of the first switch for every switching cycle of the first and second switches.

Abstract: A resonant power converter draws current from a source that provides a supply current. Multiple quasi-resonant converters are interleaved and each quasi-resonant converter receives the supply current and forms a phase-shifted current according to drive signals supplied by a controller. Each phase-shifted current includes a dead-time delay and is phase-shifted relative to the other phase-shifted currents. The dead-time delay is determined as a time value within a calculated dead-time delay range having a dead-time delay minimum and a dead-time delay maximum. The outputs of each quasi-resonant converter are added together thereby reducing the AC components of current. Two, three, or four quasi-resonant power converters can be interleaved, each forming phase-shifted currents that are phase-shifted relative to the other phase-shifted currents.

Abstract: Inverter topologies for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform are disclosed. In some disclosed embodiments, an inverter may include a full bridge LLC resonant converter, a first boost converter, and a second boost converter. In such embodiments, the first and second boost converters operate in an interleaved manner. In other disclosed embodiments, the inverter may include a half-bridge inverter circuit, a resonant circuit, a capacitor divider circuit, and a transformer.

Abstract: In accordance with an embodiment, a method for controlling a circuit includes controlling pulse width modulation on a primary side of a quasi-resonant controller to achieve continuous current mode operation from a synchronous rectification controller on a secondary side.

Abstract: A DC to DC converter system, includes inverter circuitry having a first and a second switch, the inverter circuitry further configured to generate a first and a second gate control signal, the signals configured to open and close the first and second switch, respectively, and generate an AC signal from a DC input signal. The system further includes transformer circuitry configured to transform the AC signal into a sinusoidal AC signal, second stage circuitry configured to rectify the sinusoidal AC signal to a DC output signal, and hybrid control circuitry configured to modulate the first and second gate control signals, wherein the modulation comprises pulse frequency modulation (PFM) and pulse width modulation (PWM).

Abstract: A boost control section for controlling a converter includes a PI control section and a resonance suppression section. The PI control section calculates a basic command value based on a deviation between a drive voltage generated by the converter and a target voltage to equalize the drive voltage and the target voltage. The resonance suppression section calculates, based on the state of variation of the drive voltage, a correction value for correcting the basic command value to suppress the variation. The basic command value is corrected by adding the correction value. First and second drive pulses corresponding to the corrected command value are outputted to the converter.

Abstract: A control device for a resonant converter, the control device including a first circuit to integrate at least one signal indicating a half wave of a current circulating in a primary winding of a transformer; the first circuit is structured to generate at least a control signal of the switching circuit depending on the integrated signal. The control device includes a second circuit to impose the equality of a switching-on time period of the first and second switches.

Abstract: In a DC power supply in which a DC power source and a transformer are connected via a power conversion circuit and a secondary winding of the transformer is connected to a load via a rectifier diode bridge and a filter circuit to supply power to the load, a resonance reactor is provided on an output side of the transformer, a resonant switch circuit including a parallel circuit of a diode and a semiconductor switch and a resonant capacitor is connected in parallel to the rectifier diode bridge and a snubber circuit including a snubber capacitor, a snubber diode and a diode for discharge is connected to a serial resonant circuit including the resonance reactor and the resonant capacitor in the resonant switch circuit to absorb a surge voltage.

Abstract: A control device for a switching circuit of a resonant converter having a direct current at the output, the switching circuit having at least one half bridge of at least first and second transistors connected between an input voltage and a reference voltage. The half bridge is adapted to generate a periodic square wave voltage to drive the resonant circuit of the resonant converter; The control device has a circuit to proportionally generate a first voltage to a switching period, and a circuit adapted to limit the voltage at the ends of a capacitor between a reference voltage and the first voltage, and a further circuit structured to control the switching off of a first or second transistor at the time instant in which the voltage across the capacitor has reached the first voltage.

Abstract: A power converter is disclosed including a switching converter having a switching node, a first quasi-resonant multiplier stage having a resonant input coupled to the switching node, and a second quasi-resonant multiplier stage having a resonant input coupled to the switching node. In another embodiment, a power converter includes a switching converter having a switching node, a first quasi-resonant multiplier stage having a boost input coupled to the switching node, and a first clamp coupled to the first multiplier stage.

Abstract: A converter includes a transformer including a primary winding and a secondary winding, a primary-side circuit connected to first and second input terminals and to the primary winding and including a switching circuit connected to the primary winding and a parallel resonant tank circuit including the primary winding and a resonant capacitor connected in parallel with the primary winding, a secondary-side circuit connected to the secondary winding and to first and second output terminals and including a rectifier circuit connected to the secondary winding, and an inductor including a primary inductor winding connected to the first input terminal and the primary winding and a secondary inductor winding connected to the secondary winding and the first output terminal.

Abstract: An LLC resonant power regulator system includes a transformer having a primary inductor and a secondary inductor and an input resonant tank including an input resonant capacitor, an input leakage inductor, and the primary inductor connected in series. The system also includes an input stage having a plurality of switches that are controlled in response to a respective plurality of switching signals sweeping frequency to supply an input resonant current to the input resonant tank. Each of the respective plurality of switching signals can have a fixed duty cycle and a sweeping frequency. The system further includes an output resonant tank that includes an output resonant capacitor, an output leakage inductor, and the secondary inductor connected in series. The output resonant tank can be configured to generate an oscillating output resonant current at an output.

Abstract: In one embodiment, a power supply controller is configured to adjust a peak value of a primary current through a power switch responsively to a difference between a demagnetization time and a discharge time of the parasitic leakage inductance of a transformer.

Abstract: A control device for a resonant converter includes a first circuit structured to rectify a signal indicating the current circulating in the primary winding, a second circuit adapted to integrate at least the rectified signal and structured to generate at least a control signal of the switching circuit according to the integrated signal, and a third circuit adapted to send a reset command to the second circuit so as to inhibit the operation over a time period between the instant when the integrated signal reaches or exceeds a first signal and the instant of the next zero crossing of the signal, indicating the current circulating in the primary winding.

Abstract: A power converter includes an output unit, a first transformer, a switch unit, and a processing unit. The first transformer includes a primary winding and a secondary winding. The primary winding is coupled between an input voltage and a first node. The switch unit is coupled between the first node and a second node. The processing unit is coupled between the input voltage and the first node. When the switch unit is in an OFF state, the processing unit is used to receive a first sensing voltage and store a sensing power of the first sensing voltage through a first path, isolate the first sensing voltage from feeding in through a second path different from the first path simultaneously, and then release the stored sensing power through the second path. The first sensing voltage is generated as the switch unit switches from an ON state to the OFF state.

Abstract: The voltage at a spurious frequency is decreased while maintaining as much as possible the voltage at a resonance frequency of a piezoelectric transformer, thus controlling a wide voltage range with a comparatively low cost configuration. A high-voltage power supply apparatus includes a piezoelectric transformer that outputs a highest voltage at a predetermined resonance frequency, and a generating unit that generates a signal that oscillates at a drive frequency that drives the piezoelectric transformer, throughout a frequency range that includes the resonance frequency. Furthermore, the high-voltage power supply apparatus includes an output terminal connected to the piezoelectric transformer, and a constant-voltage element inserted in a path that couples the piezoelectric transformer and the output terminal.

Abstract: Methods, systems, and devices are described for an adjustment module that interacts with a parameter detection module to provide a threshold value for initiating switching of a switching module in a cyclical electronic system. Aspects of the present disclosure provide a switching module used in conjunction with an inductor that is coupled with the switching module. The threshold voltage for switching the switching module may be adjusted to provide switching at substantially zero volts while maintaining sufficient energy in the inductor to drive the voltage at a switching element in the switching module to zero volts. Such auto-adjustment circuits may allow for enhanced efficiency in cyclical electronic systems. The output of an up/down counter may be used to set another parameter that effects the performance of the cyclical electronic system in order to enhance the performance of the cyclical electronic system.

Abstract: A control circuit for a resonant power converter and a control method thereof are disclosed. The control circuit comprises a first transistor and a second transistor switching a transformer through a resonant tank. A controller receives a feedback signal for generating a first switching signal and a second switching signal coupled to drive the first transistor and the second transistor respectively. The feedback signal is correlated to an output of the resonant power converter. A diode is coupled to the second transistor for detecting the state of the second transistor for the controller. The first switching signal and the second switching signal are modulated to achieve a zero voltage switching (ZVS) for the second transistor.

Abstract: A valley-detection device for quasi-resonance switching and a method using the same is disclosed, which uses first and second capacitors to connect with a comparator, and the comparator connects with an NMOSFET connecting to a transformer. When the NMOSFET is turned off, the energy stored in the transformer is discharged and a resonant signal across the source and the drain is generated, and a first constant current charges the first capacitor at a start time point of the resonant signal until a voltage of the resonant signal first reaches to a crossing voltage. Then, a second constant current charges the second capacitor when the voltage of the resonant signal equals to the crossing voltage while the voltage of the resonant signal varies from high to low. Finally, the comparator turns on the NMOSFET when a voltage of the second capacitor equals to a voltage of the first capacitor.

Abstract: A control circuit of a resonant power converter is disclosed. The control circuit comprises a first transistor and a second transistor for switching a transformer and a resonant tank comprising a capacitor and an inductor. A controller is configured to receive a feedback signal correlated to the output of the power converter for generating a first switching signal and a second switching signal to drive the first transistor and the second transistor, respectively. A diode coupled to the first transistor and the resonant tank for detecting the state of the first transistor and generating a detection signal for the controller. The detection signal indicates if the transistors are in a zero voltage switching (ZVS) state. If the transistors are not in the ZVS state, the switching frequency of the transistors will be increased.

Abstract: A resonant converter system includes a first stage having inverter circuitry and resonant tank circuitry configured to generate an AC signal from a DC input signal, a transformer configured to transform the AC signal, and a second stage. The second stage features synchronous rectifier (SR) circuitry including a plurality of SR switches each having a body diode and SR control circuitry. SR control circuitry is configured to generate gate control signals to control the conduction state of the SR switches so that the body diode conduction time is minimized and a negative current across the SR switches is reduced or eliminated. The method includes controlling the conduction state of SR switches to conduct as the body diode associated with the switch begins to conduct and controlling the SR switch to turn off as the current through the switch approaches a zero crossing.

Abstract: A power voltage required to operate the switch control device is generated by using full-wave current rectification voltage generated by rectifying an AC input. A zero cross-point is detected when a full-wave rectification voltage is zero voltage by using the power voltage. A reference signal synchronized to the full-wave rectification voltage is generated by using the detected zero cross-point. A switching operation of a power switch is controlled by comparing a reference signal with current that flows on the power switch.

Abstract: In a switching power supply apparatus, a comparator outputs a first determination criterion signal based on a saw-tooth wave signal whose level fluctuates with a constant period and a detection voltage signal. An inverter subjects the first determination criterion signal to reverse processing, and outputs a second determination criterion signal. The comparator outputs a first switching judgment-use signal from a monitor signal and a threshold value, and the comparator outputs a second switching judgment-use signal from the monitor signal and the threshold value. An AND circuit outputs the first switching control signal from the first determination criterion signal and the first switching judgment-use signal, and the AND circuit outputs the second switching control signal from the second determination criterion signal and the second switching judgment-use signal.

Abstract: A quasi-resonant device for a switching power, a quasi-resonant system for a switching power, and a method for a quasi-resonant control of a switching power are provided. The quasi-resonant device includes: a degaussing time sampling module, configured to sample a degaussing time Tds of a secondary coil of the transformer according to a feedback signal output by the switching power after the switching tube is turned off; a valley sampling module, configured to sample a resonant valley signal of the quasi-resonant module according to the feedback signal; a time producing module, configured to produce a time T with a predetermined ratio D by processing the degaussing time Tds; and a logic processing module, configured to obtain a first valley signal after the time T, and the first valley signal works as a switching signal T? to turn on the switching tube.

Abstract: A winding voltage arising in a first winding on the primary side of a transformer is detected in a winding voltage detector unit formed of a second winding, and current flowing through a resonant circuit is detected in a resonant current detector unit formed of an auxiliary capacitor and a resistor. The timing at which the polarity of the detected winding voltage is inverted is detected in a control and drive unit, and the time at which the polarity of the resonant current, whose phase is delayed with respect to that of the winding voltage, will be inverted is determined in advance. In the event that there is a switch in an on-state when the timing immediately before the inversion of the polarity of the resonant current is detected from the output of the resonant current detector unit, the control and drive unit forcibly turns off the switch.

Abstract: In a switching power supply device with reduced size and increased power conversion efficiency, a first resonant circuit including a series resonant inductor and a series resonant capacitor, and a second resonant circuit including a series resonant inductor and a series resonant capacitor, are caused to resonate with each other to cause sympathetic vibration of each resonant circuit, such that transmission is performed by utilizing both magnetic field coupling and electric field coupling between a primary winding and a secondary winding. Operation at a switching frequency higher than a specific resonant frequency of an overall multi-resonant circuit allows a ZVS operation to be performed, enabling a significant reduction in switching loss and high-efficiency operation.

Abstract: A resonant switching power converter having adaptive dead time control provides improved efficiency along with reduced EMI/audible noise and component stresses. A dead time between pulses generated by a switching circuit is adaptively set in conformity with a value of the input voltage to the resonant switching power converter and an indication of a magnitude of the current passing through inductive element of the resonant tank of the converter. The indication of the current magnitude may be the switching frequency of the converter, or a measure of line or load current levels. The dead time can be obtained from a look-up table or computed from the current magnitude and input voltage values.

Abstract: A power converter includes first and second circuit modules, a first capacitor, a second diode and a control module. The first circuit module includes a switching element in parallel with a first diode. The second circuit module includes a first inductor and the first circuit module. The inductor is in series with the first circuit module. The first capacitor is in parallel with the second circuit module. The second diode includes a first terminal and a second terminal, where the first terminal is in series with the second circuit module and the first capacitor, and the second terminal is coupled to a second power terminal. The control module varies one or more of the first capacitor and the first inductor based on at least one of a current of a load circuit or an input voltage. A resonating waveform is generated by a resonant circuit of the second circuit and is used by the control module to turn off the switching element under zero-current and zero-voltage conditions.

Abstract: A synchronous operating system for operating a plurality of discharge tube lighting apparatuses at the same frequency and same phase includes (1) an oscillator of a triangular wave signal whose inclination for charging a capacitor C2 and inclination for discharging the same are the same, (2) a signal generation part to generate, in a period shorter than a half period of the triangular wave signal, a first drive signal having a pulse width corresponding to a load current, and (3) a signal generation part of a second drive signal having a pulse width substantially equal to that of the first drive signal and a phase difference of about 180 degrees with respect to the same.

Abstract: An open loop half-bridge power converter is provided for effective zero volt switching during all operating conditions, the converter including: an oscillating inverter circuit having a pair of switches coupled to a load circuit; an inverter drive circuit effective to provide driver signals to the inverter circuit; and a control circuit for providing control signals to the drive circuit. The control circuit is configured to increase a switching frequency of the switching devices in response to a predetermined condition such as startup or short circuit conditions. The inverter as a result continues to operate at a full duty cycle in response to the increased switching frequency, and zero volt switching is ensured throughout the duration of the predetermined condition.

Abstract: There is provided a single-phase AC synchronized motor that does not need smooth of rectifier waves but stably performs shift from a starting operation to a synchronized operation. In the motor, based on detected signals of a position sensor, rectified current is reciprocally flowed to each direction of a single-phase coil which starts the motor. The motor includes a start-up operation circuit with a sensor starting period that increases a rotational speed until reaching to a first predetermined rotational speed; and a control device that controls operation of the motor as that shift to synchronized operation is performed when a rotational speed of a permanent magnetic rotor is reached to a second predetermined rotational speed nearby a synchronized rotational speed but not exceeding the synchronized rotational speed, and when the rise and fall of detected signals of the position sensor and the zero-cross point of AC current are approximately correspondent to each other.

Abstract: The disclosed switching regulator, including a controller for a switching regulator, is adaptable to supplying, or controlling the supply of, regulated current to a load that is isolated from a source of input power by a flyback transformer, and includes: (a) detecting, after transistor SWOFF, a zero crossing ZCD corresponding to a primary side switching node voltage VSW decreasing to the input voltage Vin, which occurs after a secondary current IS is substantially zero and before the next SWON; (c) establishing a time-integral window T-I_W with a leading edge corresponding to SWOFF and a trailing edge corresponding to ZCD; and (d) modulating at least the time SWOFF relative to SWON based on the primary peak current IPP at SWOFF and the time-integral window, such that a regulated load current is supplied to the load.

Abstract: A valley-detection device for quasi-resonance switching and a method using the same is disclosed, which uses first and second capacitors to connect with a comparator, and the comparator connects with an NMOSFET connecting to a transformer. When the NMOSFET is turned off, the energy stored in the transformer is discharged and a resonant signal across the source and the drain is generated, and a first constant current charges the first capacitor at a start time point of the resonant signal until a voltage of the resonant signal first reaches to a crossing voltage. Then, a second constant current charges the second capacitor when the voltage of the resonant signal equals to the crossing voltage while the voltage of the resonant signal varies from high to low. Finally, the comparator turns on the NMOSFET when a voltage of the second capacitor equals to a voltage of the first capacitor.

Abstract: A switching power supply includes a first auxiliary power supply for causing a first auxiliary winding of a transformer to induce voltage by ON/OFF control of a switching element connected to a primary winding of the transformer. The voltage induced by the first auxiliary winding charges a capacitor in the first auxiliary power supply. The switching power supply also includes a control circuit for starting and stopping the ON/OFF control of the switching element by comparing a voltage of the capacitor with a first threshold value, an activation circuit for charging the capacitor with voltage from the power supply input to the switching power supply, and a determination unit for determining a lifespan of the switching power supply based on the voltage of the capacitor after the voltage of the capacitor becomes greater than or equal to the first threshold value.

Abstract: A method for controlling operation of a resonant converter is to be implemented by a control module that generates a drive signal for controlling a power switch of the resonant converter to thereby control an output voltage and an output current provided by the resonant converter to a load. The method includes: (A) configuring the control module to determine if the load is operating in a first mode or a second mode; (B) configuring the control module to generate the drive signal according to the output voltage when the control module determines that the load is operating in the first mode; and (C) configuring the control module to generate the drive signal according to the output current when the control module determines that the load is operating in the second mode.

Abstract: A current detecting circuit detects a resonant current in a primary side of a resonant converting circuit to generate a current detecting signal. An output detecting circuit generates a feedback signal according to the output voltage. A resonant controller generates a clock signal and adjusts an operating frequency of the clock signal in response to the feedback signal for modulating the output voltage of the resonant circuit. The resonant controller includes a resonance deviation protection unit which detects the current detecting signal according to a phase of the clock signal to determine whether the resonant circuit enters a region of zero current switching or not. When the resonant circuit enters the region of zero current switching, the resonant controller executes a corresponding protection process in response to that the resonant controller operates in a starting mode or a normal operating mode.

Abstract: A maximize efficiency method for resonant converter with self-adjusting switching points is disclosed. The method is operated by a resonant converter, which comprises a transformer and a field effect transistor (FET). When the transistor is turned on, energy is stored in the transformer. When the transistor is turned off, a resonant signal is generated at a drain of the transistor. At this time, a suitable trigger time has to be found to turn on the transistor, so as to reduce switching power loss. The method measures the slope of the resonant signal at the trigger time. This is used as a reference to adjust the next cycle's trigger time. If the slope is negative at the time of trigger, a delta time is added to the trigger time in the next cycle, If the slope is positive, a delta time is subtracted from the trigger time for the next cycle.

Abstract: A series resonant converter of the present invention includes an inverter circuit having at least a pair of a first and second switching device connected between two input terminals, a transformer having a primary winding and a secondary winding connected to the inverter circuit, a first and second resonant capacitor connected to a secondary side of the transformer and connected in series to each other between two output terminals, a first and second unidirectional device connected in series to each other, and a resonant induction device that is operated along with the first and second resonant capacitor and resonates in series. The first and second unidirectional device are configured such that current does not flow from the first and second resonant capacitor to the input terminal by preventing electric charge of the first and second resonant capacitor from being discharged to a primary side of the transformer.

Abstract: The invention deals with the control of a resonant LLC converter by setting up criteria for state parameters of the resonant converter, so that the converter may be operated in a near capacitive mode. The current flowing in the resonant tank and optionally the voltage at the a predetermined point in the resonant tank are monitored, and wherein a switch (a high side switch or a low side switch) is turned off when a first criterion is fulfilled together with a second criterion or optionally a third criterion, the first criterion ensuring a minimum time has lapsed after the switch is turned on, the second criterion being that the absolute value of the current is reaching a predetermined current level, the third criterion being that the voltage at the predetermined point reaches a predetermined voltage level.

Abstract: The invention provides a power supply apparatus for supplying electric power to a capacitive load. The apparatus has a transformer, a positive half-period driver and a negative half-period driver supplying positive and negative half-periods of voltage to the first coil. The second coil forms an electric resonance circuit and supplies electric voltage to the load. Zero crossings of the voltage supplied to the first coil are determined from a third coil on the transformer, and alternation between positive and negative half-periods of voltage supplied to the first coil is done at the zero crossings of the voltage supplied to the first coil.

Abstract: In one embodiment, a quasi-resonant power supply controller is configured to select particular valley values of a switch voltage to determine a time to enable a power switch. The valleys values are selected responsively to a range of values of a feedback signal.

Abstract: A DC/DC converter has three half-bridge-type current resonant DC/DC converters that are connected in parallel, have a phase difference of 120 degrees, and are operated at a frequency higher than a resonant frequency. Each of the three half-bridge-type current resonant DC/DC converters includes a transformer having a primary winding, a secondary winding, and a tertiary winding, a series circuit connected to both ends of a DC power source and including first and second switching elements, a series circuit connected to both ends of the first or second switching element and including a resonant reactor, the primary winding of the transformer, and a resonant capacitor, and a rectifying circuit to rectify a voltage generated by the secondary winding and output the rectified voltage to a smoothing capacitor. The tertiary windings are annularly connected to a reactor.

Abstract: Object of this invention is to prevent deviating increase of switching frequency of a switching element for a half-wave rectification current resonance type switching power supply device in the process of a soft start operation. To solve the object, between output terminals of a direct current power source, a first switching element Q1 and a second switching element Q2 are connected in series. A primary winding of a transformer T1 and a current resonant capacitor Cri are connected to the second switching element Q2 in parallel. A gate control circuit is designed to gradually lengthen the on period of the first switching element Q1 and also designed to shorten the on period of the second switching element Q2 in time of the start operation. This makes it possible to perform a soft start without deviating from the frequency band required for voltage control.

Abstract: A digital dynamic delay modulator and the method thereof are applied to a flyback converter. A first input voltage signal from the flyback converter is received and compared with a threshold voltage to determine whether a counting condition is matched. When the counting condition is matched, an integer predetermined count number is counted to determine a delay time. After finishing the counting, a first output signal is generated to turn on a switching device for the flyback converter. The slope of the first input voltage signal is detected when the switching device is turned on, and the slope is used to adjust the count number with integer increment/decrement. Therefore, the delay time for switching the flyback converter can be precisely controlled in digital and dynamic manner.

Abstract: The present invention relates to an adapter power supply, which includes a switching unit for switching a DC voltage; a transformer which has a primary winding connected to the switching unit, a secondary winding electromagnetically coupled to the primary winding, and an auxiliary winding electromagnetically coupled to the primary winding; a rectifier for rectifying a voltage outputted from the transformer; and a controller for controlling the switching unit to operate according to the PWM scheme in a normal operation mode, and to operate according to a quasi-resonant scheme in a standby mode, by detecting information of a load connected to the rectifier.

Abstract: A control device for a resonant converter is described. The converter comprises a switching circuit adapted to drive a resonant circuit that includes at least one capacitor. The converter is adapted to convert an input signal into an output signal and the switching circuit includes at least a half bridge of first and second switches, the central point of said half bridge being connected to the resonant circuit. The control device comprises a controller adapted to generate at least a control signal of the switching circuit by comparing a signal representative of the energy of the resonant circuit with at least another signal.

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 quantization of the mode of operation is significantly reduced or eliminated.

Abstract: An isolated DC-to-DC voltage step-up converter is provided with four switches, an input inductor, an isolation transformer, two resonant inductors and two resonant capacitors and operates with two distinct intervals: ON-time interval and an OFF-time interval. The two half-wave sinusoidal resonant capacitor charge and discharge intervals, one during the ON-time interval and the other during the OFF-time interval are chosen as to eliminate the losses due to energy stored in the leakage inductance of the isolation transformer and to operates with zero voltage switching of the primary side switches. It provides the output voltage regulation over the wide input voltage range with the same low voltage stresses of all four switching devices. The isolation transformer has full bi-directional flux capability and has DC bias. Despite the two independently controlled resonances, the output voltage is controlled by the duty ratio D control at constant switching frequency.

Abstract: A resonant power conversion apparatus includes a transformer T1 having a primary winding n1, a secondary winding n2, a tertiary winding n3, and a reset winding nR, a series circuit of switches S1 and S2, a capacitor Cr1 and diode D1 to the switch S1, a capacitor Cr2 and diode D2 to the switch S2, a series circuit of the winding n1 and a diode Dn1, a series circuit of the winding nR and a diode DR, a reactor Lr connected between a connection point of the switches S1 and S2 and a connection point of the windings n2 and n3, a switch S10 connected between the DC power source and the winding n2, a switch S20 connected between the DC power source and the winding n3, and a controller 10 configured to perform a zero-voltage switching operation of the switches S1 and S2.