156 results about "Resonant power converters" patented technology

An AC-to-DC power converter configured to provide power factor correction and a single isolated low-voltage output. The power converter includes a single-stage resonant power converter including an isolation transformer, a resonant tank, a rectifier, and a bulk storage capacitor coupled to an output of the isolation transformer. In typical applications, at least one non-isolated power converter is coupled to the output of the single-stage isolated power factor correction converter.

A burst mode resonant power converter with high conversion efficiency has a rectifier, a power factor correction circuit, a resonant circuit, a controller, and a burst mode triggering unit. The maximum frequency switching end of the controller is connected to a maximum frequency variable circuit. When the load is medium or heavy, the maximum frequency variable circuit increases the maximum switch frequency of the controller. When the load is in the no-load or the light conditions, it reduces the maximum switch frequency thereof. Therefore, the controller reduces the number of times that the resonant circuit switches the bridge switch circuit. The conduction cycle of the 50% pulse signal output to the bridge switch circuit becomes longer. Larger energy can be transmitted at a time to the secondary coil of the transformer. This increases the overall efficiency.

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.

A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

The present invention relates to resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches (S1, S2). The self-oscillating feedback loop sets a switching frequency of the power converter (100) and comprises a first intrinsic switch capacitance (CGD) coupled between a switch output and a control input of the switching network and a first inductor (LG). The first inductor (LG) is coupled in-between a first bias voltage source and the control input of the switching network and has a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage (VBias) applied to the first inductor (LG). The output voltage (V0UT) of the power converter (100) is controlled in a flexible and rapid manner by controlling the adjustable bias voltage (VBias).

A resonant power converter is provided with auxiliary circuit branches and control circuitry for switchably coupling the auxiliary branches to resonant circuit components during holdup times. Auxiliary branches are coupled in parallel with any one or more of a resonant inductor, a resonant capacitor, and a magnetizing inductive winding via respective switches. When a holdup time condition is detected in accordance with, for example, a drop in the mains line voltage, the switches are controlled to adjust the corresponding inductance or capacitance for the duration of the holdup time condition or otherwise for a predetermined duration. The power converter in normal operation is configured for high efficiency and in a holdup time operation is configured to produce sufficient holdup time.

A DC power converter consisting of a series-resonant branch used to transform a DC voltage source into a DC current source exhibiting, a uni-polar, zero-current-switching characteristic. Frequency of the series-resonant branch, acting in concert with reflected load parameters, provides a forced oscillation frequency, Fo, component to an AC voltage source generated across the input winding of a power transformer by the resonant capacitor. Complex load parameters allow AC input current, displaced by 90° from the AC voltage source, to flow in the transformer primary winding throughout a composite, carrier-frequency cycle. Another component of the carrier-frequency consists of a resonant, natural oscillation frequency, Fn, resulting from resonance by the AC voltage source capacitance with the open-circuit inductance of the primary winding on the input power transformer. The composite carrier-frequency, Fo+Fn, transported through the input power transformer is directed to a rectifier / filter assembly and applied as a DC voltage to an output load. Thus, the uni-polar DC series-resonant branch is converted into an AC power transfer function, fully isolated from the input power switch, by the AC voltage source capacitor. The power transfer function characterizing a bi-polar power inverter requires a single power switch referenced to the input power return bus.

The present invention provides a controller for a power converter. The controller comprises a PWM circuit, a detection circuit, a signal generator, an oscillation circuit, a valley-lock circuit, a timing circuit and a burst circuit. The PWM circuit generates a switching signal coupled to switch a transformer of the power converter. A feedback signal is coupled to control and disable the switching signal. The detection circuit is coupled to the transformer via a resistor for generating a valley signal in response to a waveform obtained from the transformer. The signal generator is coupled to receive the feedback signal and the valley signal for generating an enabling signal. The oscillation circuit generates a maximum frequency signal. The maximum frequency signal associates with the enabling signal to generate a turning-on signal. The turning-on signal is coupled to enable the switching signal. A maximum frequency of the turning-on signal is limited.

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 present invention refers to a DC / AC power inverter control unit of a resonant-type power converter circuit (400), in particular a DC / DC converter, for supplying an output power for use in, for example, a high-voltage generator circuitry of an X-ray radio-graphic imaging system, 3D rotational angiography device or X-ray computed tomography device of the fan-or cone-beam type. More particularly, the present invention is directed to a resonant-type power converter circuit out which comprises an interphase transformer (406) connected in series to at least one series resonant tank circuit (403a and 403a′ or 403b and 403b′) at the output of two DC / AC power inverter stages (402a+b) supplying a multi-primary winding high-voltage transformer (404), wherein said interphase transformer (406) serves for removing the difference (DI) in the resonant output currents (1 and 2) of the DC / AC power inverter stages (402a+b). Furthermore, the present invention is dedicated to a control method which assures that the interphase transformer (406) is not saturated. This control method ensures zero current operation and provides for that input power losses can be minimized.

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.

Pulse width modulation is provided for controlling a resonant power converter, particularly for dimming of light emitting diode arrays without loss of efficiency. Dynamic oscillation due to the beginning of a pulse width modulated pulse burst is limited by shortening of the first and / or last pulse of a pulse bust such that the first pulse of a subsequent pulse burst close to or to connect with a full load steady-state voltage / current trajectory of the power converter. Pulse shortening made be made substantially exact to virtually eliminate dynamic oscillation but substantial reduction in dynamic oscillation is provided if inexact or even performed randomly.

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.

A synchronous rectifying circuit is provided for resonant power converter. An integrated synchronous rectifier comprises a rectifying terminal, a ground terminal a first input terminal and a second input terminal. The rectifying terminal is coupled to the secondary side of a power transformer. The ground terminal is coupled to the output of the power converter. A power transistor is connected between the rectifying terminal and the ground terminal. The first input terminal and the second input terminal are coupled to receive a pulse signal for turning on / off the power transistor. A pulse-signal generation circuit includes an input circuit coupled to receive the switching signal for switching the power transformer of the power converter.

The present invention provides a switching control circuit having a valley voltage detector to achieve the soft switching and improve the efficiency of a power converter. The switching control circuit includes a control circuit coupled to the feedback signal to generate a switching signal. Through an output circuit, the switching signal drives a switching device for switching a transformer and regulating the output of the power converter. The valley voltage detector is coupled to an auxiliary winding of the transformer for generating a control signal in response to the voltage of the transformer. The control signal is used for enabling the switching signal. The switching signal further turns on the switching device in response to a valley voltage across the switching device.

A synchronous voltage modulation circuit for resonance power converter has a resonance current extracting unit and at least one duty cycle modulation circuit. The resonance current extracting unit extracts the resonance current of the transformer for each duty cycle modulation circuit. The duty cycle modulation circuit controls the conduction period of the electronic switch on the secondary side of the transformer according to the power usage of the load connected to the power output and the resonance frequency of the resonance current on the transformer detected by the resonance current extracting unit. The conduction period increases or decreases symmetrically with respect to the central axis. The power converter output of the resonance power converter converter forms a closed loop control, thereby providing stable power to its load.

An apparatus, method, and system for measuring current within a converter. The converter including a resonant tank circuit with a capacitor, the resonant tank circuit is coupled to a DC input bridge and a first terminal of the capacitor is coupled to a ground of the DC input bridge. In addition, a voltage monitor coupled across the capacitor for measuring a voltage across the capacitor. The converter also includes a resonant current calculation module for computing a tank current value based on the voltage.

A power converter including a transformer, a resonant circuit including the transformer and a resonant capacitor having a characteristic resonant frequency and period, and output circuitry connected to the transformer for delivering a rectified output voltage to a load. Primary switches drive the resonant circuit, a switch controller operates the primary switches in a series of converter operating cycles which include power transfer intervals of adjustable duration during which a resonant current at the characteristic resonant frequency flows through a winding of the transformer. The operating cycles may also include energy recycling intervals of variable duration for charging and discharging capacitances within the converter. A gate driver includes a transformer, a plurality of switches, a current monitor, and a controller that operates the switches in a series of driver operating cycles having adjustable ON periods and adjustable transition periods during which capacitances are resonantly charged and discharged.

Control methods for resonant converters offer improved performance in resonant converters that operate with a wide input-voltage range or a wide output-voltage range (or both) by substantially reducing the switching-frequency range. Reduction in the switching frequency range is achieved by controlling the output voltage with a combination of variable-frequency control and time-delay control. Variable-frequency control may be used to control the primary switches of an isolated resonant converter, while delay-time control may be used to control secondary-side rectifier switches provided in place of diode rectifiers. The secondary-side control may be implemented by sensing the secondary current or the primary current (or both) and by delaying the turning-off of the corresponding secondary switch with respect to the zero crossings in the secondary current or the primary current.

Consistent with an example embodiment there is a method of controlling a resonant power converter; the power converter includes first and second series connected switches connected between a supply voltage line and a ground line and a resonance circuit, having a capacitor and an inductor. The resonance circuit is connected to a node connecting the first and second switches. The method comprises repeated sequential steps of closing the first switch to start a conduction interval; sampling a voltage across the capacitor to obtain a sampled voltage level; and opening the first switch to end the conduction interval when a voltage across the capacitor crosses a voltage level determined by addition of the sampled voltage level with a predetermined voltage difference; wherein controlling the predetermined voltage difference determines a power output of the resonant power converter.

Consistent with an example embodiment there is a method of controlling a resonant power converter; the power converter includes first and second series connected switches connected between a supply voltage line and a ground line and a resonance circuit, having a capacitor and an inductor. The resonance circuit is connected to a node connecting the first and second switches. The method comprises repeated sequential steps of closing the first switch to start a conduction interval; sampling a voltage across the capacitor to obtain a sampled voltage level; and opening the first switch to end the conduction interval when a voltage across the capacitor crosses a voltage level determined by addition of the sampled voltage level with a predetermined voltage difference; wherein controlling the predetermined voltage difference determines a power output of the resonant power converter.

A resonant power converter with half bridge and full bridge operations and a method for control thereof are provided. The resonant power converter includes a full bridge circuit, a control circuit and a PFC circuit. The full bridge circuit switches a power transformer in response to switching signals. The control circuit coupled to receive a feedback signal and an input signal generates switching signals. The feedback signal is correlated to the output of the power converter and the input signal is correlated to the input voltage of the full bridge circuit, where the full bridge circuit is operated as a full bridge switching when the input signal is lower than a threshold, and the full bridge circuit is operated as a half bridge switching when the input signal is higher than the threshold. The PFC circuit generates the input voltage of the full bridge circuit.

A device to drive a plurality of power switches in a power converter with an input voltage port having an input voltage comprises a drive resonant tank, a switch network, a control block configured to control the turn-on and turn-off of drive switches, and an output port. The drive resonant tank comprises a resonant inductor, and a resonant capacitor which comprises an input capacitance of a power switch. The switch network has a plurality of drive switches, which are controlled such that the drive resonant tank goes through a resonant state and a pseudo clamp state consecutively during a switching period. A gate drive voltage of a power switch fluctuates slightly during the pseudo clamp state. The output port has two terminals coupled to a gate and a source of a power switch respectively.

A method and semiconductor device for controlling skip mode operation during light load conditions in a resonant power converter includes a skip mode controller circuit that compares a feedback signal corresponding to the secondary output level with a reference voltage to determine when to invoke skip mode. When entering skip mode the skip mode controller ceases switching by turning on the lower switch for a prolonged time to leave the resonant capacitor partially charged. Upon resuming switching, the lower switch is turned on first to drive current through the inductances, and asymmetric switching is used where the upper switch is on, initially for shorter periods to allow zero voltage switching. If the load increases, the on-time of upper and lower switches converge and conventional symmetric switching resumes.

A method of operating a resonant power supply in standby mode is disclosed, in which the switching period of the power supply is longer than the resonance period. The power converter is operated in normal mode for a significant fraction of one resonance period. Efficient operation is maintained, despite the switching period being extended beyond the resonance period, by using resonance current to enable soft switching, where this is beneficial, and dumping the resonance current into the load where this is more beneficial. Control methodologies to regulate the output power are also disclosed.

A controller for a power converter is provided. The controller includes a PWM circuit, a detection circuit, a signal generation circuit and an oscillation circuit. The PWM circuit generates a switching signal coupled to switch a transformer of the power converter. A feedback signal is coupled to the PWM circuit to disable the switching signal. The detection circuit is coupled to the transformer via a resistor for generating a valley signal in response to a signal waveform of the transformer. The signal generation circuit is coupled to receive the feedback signal and the valley signal for generating an enabling signal. The oscillation circuit generates a maximum frequency signal. The maximum frequency signal associates with the enabling signal to generate a pulse signal. The feedback signal is correlated to an output load of the power converter. The maximum frequency of the pulse signal is limited.