238 results about "Llc converter" patented technology

The switching frequency of an LLC converter is controlled by a control unit to which a feedback circuit provides a first current dependent upon the output voltage of the converter. An oscillator circuit produces a sawtooth waveform at a frequency dependent upon the first current, up to a limit equal to a second current set by a resistor. Two complementary switch control signals are produced for controlling two switches of the converter for conduction in alternate cycles of the sawtooth waveform. A timer produces dead times between the two complementary switch control signals in dependence upon the second current. Another resistor provides a current constituting a minimum value of the first current, and a charging current of a capacitor in series with a resistor modifies the first current for soft starting of the converter.

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.

A DC converter comprises a half bridge supply circuit and one or more flyback or forward converter output circuits, and optionally also an LLC converter whose control can determine a common variable switching frequency. The half bridge supply circuit produces a 50% duty output alternating between two input voltages, such as zero and a voltage Vin. In each flyback or forward converter output circuit, a switch connects a transformer primary to the half bridge supply circuit output in a PWM controlled manner to regulate a respective flyback or forward converter DC output which is produced by the converter output circuit, with a duty ratio less than 50% whereby switching losses are reduced. Soft switching is further facilitated by the half bridge supply circuit having two transistors controlled in a complementary manner.

A resonant power converter system includes an output load and a rectifier stage that provides a DC output voltage to the output load from an AC intermediate voltage. The resonant power converter system also includes a resonant inverter stage that provides the AC intermediate voltage from a DC input voltage, wherein an inverter gain is controlled by switching between full-bridge and half-bridge topologies based on an external variable of the resonant power converter system. The resonant power converter system further includes a controller that controls the resonant power converter system. Additionally, a method of operating a power converter includes rectifying an AC intermediate voltage to provide a DC output voltage and providing the AC intermediate voltage by inverting a DC input voltage, wherein an inversion gain of the AC intermediate voltage is controlled by switching between full-bridge and half-bridge inversion topologies based on an external variable.

The invention discloses a transformer primary side series connection LLC and output parallel connection BUCK two-stage converter which comprises two high-frequency isolation transformers, wherein primary sides of the two high-frequency isolation transformers are connected in series and then connected into an LLC resonant network; the other end of the LLC resonant network is connected into a bridge circuit; secondary sides of the two high-frequency isolation transformers are sequentially connected with rectifying circuits and BUCK circuits; and output ends of the two BUCK circuits are staggered and connected in parallel. The converter can achieve zero voltage switch-on of switching tubes on the primary sides of the high-frequency transformers, and zero current switch-off of rectifying tubes on the secondary sides of the high-frequency transformers, so that the efficiency and the power density of the LLC converter are improved; and equal primary side voltage of two primary side series connection high-frequency transformers of a preceding-stage converter can be achieved based on control of the same duty ratio of the two BUCK circuits which are staggered and connected in parallel, so that the two high-frequency transformers share equallyinput power, magnetism equilibrium distribution of the high-frequency transformers is achieved, the reliability of the converter is improved, and the cost is lowered.

A power converter includes an input stage connected to receive an input signal and to provide an intermediate DC voltage, and an output stage having an LLC converter connected to receive the intermediate DC voltage and to provide a DC output voltage. Additionally, the power converter includes a control unit connected to the input and output stages to regulate the DC output voltage and set a target operating parameter of the LLC converter based on controlling the intermediate DC voltage. A method of operating a power converter is also provided.

An active snubber circuit for a power converter, a method of operating the same and an inductor inductor capacitor converter incorporating the circuit or the method. In one embodiment, the circuit includes: (1) a series-coupled first capacitor and diode associated with a secondary-side switch in the power converter and coupled to an output thereof and (2) an active snubber circuit switch coupled in parallel with the diode and configured to receive a control signal that closes the active snubber circuit switch during at least a portion of a time during which the secondary-side switch is open.

The invention discloses a SiC power device-based EV (Electric vehicle)-mounted charger. The charger comprises a main circuit and a control circuit; the main circuit comprises a rectifying and filtering module and an LLC resonant type DC/DC circuit; and the rectifying and filtering module is of a totem pole bridgeless power factor correction circuit structure and is directly connected with a three-phase alternating-current input power source; the LLC resonant type DC-DC circuit consists of a first half-bridge LLC converter and a second half-bridge LLC converter which are of the same topology, wherein the first half-bridge LLC converter and the second half-bridge LLC converter are connected in parallel and thereafter are connected in series between the rectifying and filtering module and anoutput side; the first half-bridge LLC converter and the second half-bridge LLC converter each include comprise a half-bridge inversion module, a high-frequency voltage transformation module, and a passive rectifying and filtering module; the rectifying and filtering module and the LLC resonant type DC-DC circuit are connected with the control circuit; and the control circuit adopts an average current control mode and a PFM control mode so as to realize digital control circuit output. The SiC power device-based EV (Electric vehicle)-mounted charger of the invention has the advantages of high power output precision, high power density, high reliability and small occupied space.

A power converter includes an input stage connected to receive a three phase AC input voltage and to provide multiple DC voltage levels. The power converter also includes an output stage of a plurality of interleaved LLC converters having series-connected inputs coupled to the multiple DC voltage levels and parallel-connected outputs to provide a DC output voltage. Additionally, the power converter includes a balancing circuit interconnected to the input and output stages to provide substantially balanced output currents from the plurality of interleaved LLC converters for the DC output voltage. Methods of manufacturing and operating a power converter are also provided.

Circuits and devices are described that provide power to appliances and other devices via a power correction circuit and an LLC converter, which may for example include resonant series converters and flyback converters. The circuits and devices economize on board space, part size and power start up time by separately powering up the controller circuit portion prior to powering up the LLC converter.

Photovoltaic (PV) power converters including an LLC converter stage are described. A PV power converter includes a LLC converter stage and a controller. The LLC converter stage includes an input for receiving a direct current (DC) power input from a PV module, a first transformer having a primary winding and a secondary winding and defining a DC side and an alternating current (AC) side of the PV power converter, a plurality of switches on the DC side of the first transformer, and an output coupled to the secondary winding of the first transformer to provide a DC power output. The plurality of switches is coupled between the primary winding of the first transformer and the input. The controller is located on the AC side of the PV power converter. The controller is operatively connected to the plurality of switches and configured to control operation of the plurality of switches.

Disclosed are LLC (logical link control) converter synchronous rectification method and device. The method includes: acquiring an output voltage signal and an output current signal of a converter; calculating switching frequency of a primary side field-effect transistor according to the output voltage signal and the output current signal; judging operating statuses of the converter according to resonant frequency of the converter, and calculating different primary- and auxiliary-side frequencies and duty ratios according to the different operating statuses; controlling on and off of the primary- and auxiliary-side field-effect transistors to allow output synchronous rectification drive signals to open in the discontinuous operating status of the converter and shut down in the continuous operating status of the converter. By the use of the LLC converter synchronous rectification method and device, excessive loss due to non-zero open or shutdown current is reduced when synchronous rectifier tubes operate, and system efficiency is improved.

The invention discloses a control method and a control circuit of an isolated bidirectional charger, belonging to the technical field of power electronic converters. The bi-directional charger controlcircuit adopted by the method comprises a bi-directional AC/DC converter, an isolated DC/DC converter and a control unit. The power grid is connected to the battery pack through bi-directional AC/DCconverter, isolated DC/DC converter, isolated DC/DC converter using LLC converter, control unit including sampling circuit, DSP and optocoupler isolated driving circuit. The control method realizes the high efficiency of bi-directional operation and forward and backward operation of the vehicle-mounted charger, and has the advantages of high power density, high reliability, few devices and high efficiency.

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.

The invention relates to a combined controller of an LLC series resonant converter. It includes a bridge circuit, the bridge circuit drives a resonant network, a transformer, a frequency modulation controller, a duty cycle controller, an output rectifier circuit, an output voltage detection circuit and an output current detection circuit, the resonant network is connected in series with the primary side of the transformer, and the resonant The network is connected in series between the midpoint of the bridge circuit and the transformer, the filter capacitor is connected in parallel at the output end, the output voltage sampling circuit samples the output voltage value and sends it to the frequency modulation controller and the duty ratio controller, and the output current detection circuit samples the output current value at the same time sent to the duty cycle controller. The driving waveform is comprehensively adjusted by the frequency modulation controller and the duty cycle controller and sent to the bridge circuit for voltage regulation. The invention realizes the low-frequency narrow starting pulse, reduces the impact current of the power switch when starting; realizes the low-frequency narrow starting pulse work under no-load, deep current limiting and short-circuit working conditions, reduces the impact current of the power switch, and reduces the driving loss.

The invention relates to an integrated magnetic component (802) for a power converter including N>=2 LLC converters configured for interleaved operation. The integrated magnetic component (802) includes a first yoke and a second yoke and for each LLC converter a winding carrying leg which comprises a primary winding (820c) and a secondary winding (821c), wherein the primary winding (820c) and the secondary winding (821c) are wound on the respective winding carrying leg. The integrated magnetic component (802) further includes one or more return legs. Herein the winding carrying legs and the one or more return legs are arranged side by side, each leg being magnetically connected to both yokes and the winding carrying legs include a transformer air gap (819) whereas the at least one return leg is air gap free and at least one return leg is arranged between two winding carrying legs.

The invention further relates to a power converter including a switching converter stage (811a, 811b, 811c), a rectifier stage (813a, 813b, 813c) and a resonant stage, the resonant stage including N>=2 parallel LLC converters.

The invention discloses a PWM control method for a three-level LLC resonant converter. The LLC resonant converter at least comprises a first bridge arm which is connected with a plurality of switch tubes in series and coupled at the primary side of a transformer; the switch tubes comprise two outer tubes close to both ends of the first bridge arm and two inner tubes between the outer tubes; in thePWM mode, the duty ratio of the inner tube is maintained to be no less than the minimum duty ratio when the width modulation of duty ratio is carried out on the inner tube and the outer tube according to the gain demand; the minimum duty ratio is determined according to the requirement that the duration of delaying the turn-off of the inner tube can avoid the reverse resonance of resonance current after the outer tube is turned off. By maintaining the duty ratio of the inner tube to be no less than the minimum duty ratio, the resonance process of current of the primary side of the converter is changed, thereby avoiding generating the problem of the backward recovery of a body diode.

Disclosed is a hybrid dc-dc converter. The hybrid dc-dc converter includes: a pair of transformers configured to magnetically couple a primary side to a secondary side, a full-bridge converter including four switches constituting a full-bridge inverter circuit and a first transformer, and an LLC resonant converter including a resonant inductor, a resonant capacitor, and a second transformer, which constitute an LLC resonant circuit, wherein an output of the full-bridge converter and an output of the LLC resonant converter are connected to each other in series at the secondary side.

A method for operating a power controller is provided. The method includes activating a rectifying FET upon a detection of an activation body diode conduction current occurring in the rectifying FET. The method generates an activation signal for a corresponding primary FET. The method further includes deactivating the corresponding rectifying FET upon a reception of a deactivation signal. The method further includes then deactivating the corresponding primary FET after delaying the deactivation signal, wherein the delay lessens a conduction time of a deactivation body current of the corresponding rectifying FET. The method further includes generating a deactivation signal and deactivating the corresponding rectifying FET upon a reception of the deactivation signal and deactivating the primary FET after delaying the deactivation signal. The delaying lessens a conduction time of a deactivation body current of the corresponding rectifying FET.

The switching frequency of an LLC converter is controlled by a control unit to which a feedback circuit provides a first current dependent upon the output voltage of the converter. An oscillator circuit produces a sawtooth waveform at a frequency dependent upon the first current, up to a limit equal to a second current set by a resistor. Two complementary switch control signals are produced for controlling two switches of the converter for conduction in alternate cycles of the sawtooth waveform. A timer produces dead times between the two complementary switch control signals in dependence upon the second current. Another resistor provides a current constituting a minimum value of the first current, and a charging current of a capacitor in series with a resistor modifies the first current for soft starting of the converter.