145 results about "Zero voltage switching" patented technology

A method comprises: in an onboard charger of an electric vehicle, providing i) a direct current (DC) to DC stage including a dual-active bridge, and ii) a DC link capacitor having a DC bus voltage; and dynamically regulating the DC bus voltage to improve zero voltage switching (ZVS) in the onboard charger.

The invention discloses a TCM-mode-based Si-SiC hybrid power multi-phase staggered H-bridge converter structure and a control method thereof, according to the scheme, a three-phase staggered parallel topology of a two-phase low-frequency Si-IGBT bridge arm and a one-phase high-frequency SiC-MOSFET bridge arm is adopted, and a TCM control strategy is combined, so that zero voltage switching (ZVS) of a Si device is successfully realized, the switching loss is remarkably reduced, and the switching efficiency is improved. The system efficiency is greatly improved; and meanwhile, through pilot frequency interleaving and ripple compensation technologies, total output current ripples are greatly reduced, and optimal balance between system performance and manufacturing cost is realized while the power capacity of the converter is remarkably expanded and the dynamic response speed and the output electric energy quality are improved.

A method comprises: providing, in an onboard charger of an electric vehicle, a direct current (DC) to DC stage including a dual-active bridge having switches arranged in multiple legs, each of the multiple legs controlled by a corresponding one of pulse width modulation (PWM) signals; and dynamically modulating the PWM signals to improve zero voltage switching (ZVS) in the onboard charger.

A two-transistor flyback topology in which a portion of leakage inductance energy in the transformer is extracted and used to obtain zero voltage switching on both switching elements in any operating conditions, and in which a third low power switch eliminates parasitic oscillations and allows an operation at a determined frequency. In this topology, there are no switching losses and there are no spikes or glitches in any switching node, eliminating the need for snubbers. This topology is an “ideal two transistor flyback topology.”

System and method for controlling synchronous rectification. For example, a system for controlling synchronous rectification includes: a first control-signal generator configured to generate a first control signal; a second control-signal generator configured to receive the first control signal for a first switching cycle and generate a second control signal for a second switching cycle based at least in part on the first control signal for the first switching cycle, the first switching cycle preceding the second switching cycle; and a driver configured to receive the first control signal and generate a drive voltage based at least in part on the first control signal; wherein the second control-signal generator is further configured to: process information associated with the first control signal; determine a first time duration when the first control signal remains at a first logic level during the first switching cycle.

An insulated power supply apparatus includes, a transformer; a switching element connected in series with a primary side winding of the transformer; an active clamp circuit connected between terminals of the primary side winding of the transformer; and a power supply control semiconductor device. The switching element includes a field effect transistor and a current-voltage conversion element is connected between a source terminal of the switching element and a grounding point. The power supply control semiconductor device includes the following, a first external terminal in which voltage according to a drain side of the switching element is input, a second external terminal in which voltage converted by the current-voltage conversion element is input, an on / off control circuit that performs turn-on and turn-off of the switching element, and a ZVS determining circuit that determines whether zero voltage switching control is performed.

The invention discloses an extended double-side asymmetric phase shift modulation method for a dual-active bridge converter, and belongs to the technical field of isolated high-frequency power conversion in a power electronic technology. According to the symmetric phase shift modulation method, under the condition that the voltage conversion ratio is not matched, the zero voltage switching range of a switching tube is small, the light load efficiency is low, and variable abrupt change can occur during mode switching to cause the uncontrollable oscillation problem of inductive current. The invention provides an extended double-side asymmetric phase shift modulation method for a dual-active bridge converter in a wide voltage range. A multi-objective optimization scheme is established based on the provided modulation method, and an approximation method is provided to solve a full power range analytical solution. A smooth switching method between modes is realized, and uncontrollable oscillation of inductive current can be effectively avoided. And the conversion efficiency in a full-power range is improved.

A flyback converter comprising: a transformer having a primary side winding and a secondary side winding; a primary side switch located at the primary side of the transformer; two secondary side switches located at the secondary side of the transformer; in which the two secondary side switches are connected in parallel and have different characteristics; and a control unit configured to generate a rectification signal and a Zero Voltage Switching (ZVS) pulse and to drive the two secondary side switches; in which a secondary side switch is driven by the rectification signal and the other secondary side switch is driven by the ZVS pulse. At the end of a switching cycle, before turning on the primary side switch: the control unit is configured to generate the ZVS pulse in the secondary side winding such that the parasitic capacitor of the primary side switch is discharged, and to consequently turn on the primary side switch in ZVS conditions or near ZVS conditions.

Disclosed is a flyback converter and a control method thereof. The flyback converter includes a first switching transistor, a second switching transistor, a transformer, a first capacitor, a power supply device. A resonant loop circuit is formed by connecting the first capacitor to a primary side winding of the transformer and the second switching transistor. In a first operating mode, a controllable switching transistor of the power supply device is turned on before the second switching transistor is turned off, and after the second switching transistor is turned off, the charging capacitor is charged and stores energy. In a second operating mode, before the first switching is turned on, the controllable switching transistor is turned on, and the charging capacitor is charged and stores energy. The conversion efficiency of the power supply is enhanced while enabling the first switching transistor to operate under zero voltage switching, thereby reducing switching losses.

Disclosed is a system for zero voltage switching in a power converter with a first half-bridge and a second half-bridge. The first half-bridge has a first set of transistors and output inductor. The second half-bridge has a second set of transistors and auxiliary inductor. A current sensing means measures, at switching cycle scale, average and maximum current values of output inductor and average, minimum and maximum current values of auxiliary inductor. A voltage sensing means measures input and output voltages of first and second half-bridge. A controller is configured to compute dead times of pulse width modulation control signal of second half-bridge, generate pulse width modulation control signal of second half-bridge and to adapt dead times of first half-bridge.

The invention relates to automatic reverse current regulation in an active clamped flyback converter. According to one embodiment, a method is presented that includes sensing a reverse current through a main switch of an active clamped flyback (ACF) converter. The ACF converter includes a flyback transformer and an auxiliary switch. The method further includes determining whether a sensed voltage corresponding to the reverse current exceeds a threshold; reducing a duration of the reverse current by an incremental time interval, the duration of the reverse current including a first incremental time interval, the duration of the reverse current corresponding to a duration in which the auxiliary switch is activated; increasing the duration by a second incremental time interval greater than the first incremental time interval, the increasing in response to the reverse current not exceeding the threshold; and activating the auxiliary switch for the duration to achieve zero voltage switching (ZVS).

Systems and methods for operating a wireless power transfer device are described. A circuit can generate a first signal that indicates a voltage at a node between a first high-side (HS) transistor and a first low-side (LS) transistor in a switching converter falling below ground. The circuit can delay a gate-source voltage of a second LS transistor in the switching converter to generate a second signal. The circuit can merge the first signal and the second signal to generate a third signal. A controller can use the third signal to trigger a rising edge of a command signal to turn on the first LS transistor at a specific time. The first LS transistor being turned on at the specific time reduces a diode conduction time of a body diode of the first LS transistor.

A buck topology operates in discontinuous mode in which energy contained in the parasitic oscillations is harvested as needed, with additional energy provided by a voltage injection source, the power switchers of the buck topology turn on at zero voltage in any operating conditions.

The invention discloses a bidirectional DC-AC converter control method considering a soft switching condition and current optimization. According to the invention, the switching loss of the converter is reduced by optimizing the phase shift angle and the switching condition of the converter, and the energy transmission efficiency is optimized by minimizing the effective value of the current, so that the performance of the whole sodium battery energy storage system is improved. Specifically, based on the relation between the excitation inductance Lm and the current effective value Iprms, the phase shift angle of the converter is accurately controlled, the current transmission efficiency is optimized, and it is ensured that the zero-voltage switching condition of a primary side bridge arm and a secondary side bridge arm can be achieved in the working process, so that the loss of the converter is remarkably reduced, and the energy conversion efficiency is improved.

An example apparatus can include one or more of a transformer, a primary circuit electrically coupled to the transformer, and a first auxiliary circuit and a second auxiliary circuit, wherein the primary circuit includes a first bridge leg having a first pair of switches and a second bridge leg having a second pair of switches, the first auxiliary circuit is electrically coupled to the first bridge leg of the primary circuit, the second auxiliary circuit is electrically coupled to the second bridge leg of the primary circuit, wherein each auxiliary circuit is configured to store energy when one switch of a respective pair of switches is on and the other switch of the respective pair of switches is off, and provide the stored energy to recharge all attached capacitances in the respective bridge leg when both switches of the respective pair of switches are off.

The application discloses a resonant converter optimization method and system based on an fmincon function, which first determines transformer ratio and maximum and minimum values of converter output voltage DC gain; then converts an LLC resonant converter into an equivalent circuit, and deduces the converter output voltage DC gain as a first constraint condition; and establishes a converter loss model according to the equivalent circuit; analyzes the condition for realizing ZVS (Zero Voltage Switching) of a switching tube as a second constraint condition; finally, an optimization design function fmincon is called to perform optimization design on the resonant converter parameters. The loop power consumption of the converter is taken as an evaluation index for the resonant converter parameter design, the output voltage DC gain and the condition for realizing ZVS of the switching tube are taken as constraint conditions, the LLC resonant converter parameters are comprehensively evaluated, the LLC resonant converter parameters are obtained, which make all indexes of the converter reach the best balance, and the overall performance of the converter is effectively improved.

The application discloses a multi-path weak coupling wide voltage output DC-DC converter based on zero voltage switching, which comprises a direct current input power supply V in and N output branches, wherein N is a positive integer and N is greater than or equal to 2; the multi-path weak coupling wide voltage output DC-DC converter can realize good cross regulation among output ports by using a small number of elements, can realize both step-up output and step-down output, can meet different voltage demands, has a wide output voltage range, is easy to realize zero voltage switching, and thus can ensure high system efficiency; the multi-path output voltages can be respectively adjusted by independent control variables, and the cross coupling effect among the multiple output ports is effectively reduced.

According to one embodiment, a power amplifier includes a plurality of switches and an output tank network. One or more of the switches are configured to generate one or more first intermediate waveforms having one or more first fundamental frequency components, and one or more of the switches are configured to generate one or more second intermediate waveforms by chopping the one or more first intermediate waveforms with controllable timing. The second intermediate waveforms have one or more second fundamental frequency components that are controllably reduced from those of the one or more first intermediate waveforms. The output tank network is configured to filter the one or more second intermediate waveforms to provide an output waveform to a load, the output waveform having one or more third fundamental frequency components. In some cases, all switches achieve zero voltage switching under different power and load conditions with resistive and reactive loads.

To provide a method for using a secondary switch for enabling zero-voltage switching of the secondary switch in a flyback converter.SOLUTION: A method relates to zero-voltage switching (ZVS) of a secondary switch (e.g., a synchronous rectifier) in a flyback converter. The method causes a secondary control device to enable dynamic calculation of a secondary switch hold time required to achieve the ZVS of a primary switch during a switching cycle and thereby to determine the required secondary switch hold time without requiring communication from a primary side to a secondary side by measuring the charge time and discharge time during the switching cycle.SELECTED DRAWING: Figure 3A

The present invention belongs to the field of wireless charging, and particularly relates to a method for designing topological parameters of zero-voltage switching or zero-phase-angle input in a wireless charging system. Based on the minimum unit of the constant-current and constant-voltage mode conversion, that is, the conversion from the constant-current mode to the constant-voltage mode or from the constant-voltage mode to the constant-current mode, the addition principle of additional compensation devices is proposed; the additional compensation devices are connected in series in the constant-current branch or the additional compensation devices are connected in parallel in the constant-voltage branch; the compensated topological structure is topologically split, and the impedance conversion is carried out with the resonant T-network as the basic unit, and the additional compensation parameters can be directly calculated, and the additional compensation parameters are the topological parameters of zero-voltage switching or zero-phase-angle input. Based on the addition principle of the compensation devices proposed by this invention, all the compensation positions of the topological structure can be obtained; the calculation method of the additional compensation parameters proposed by this invention is simpler. Compared with the traditional method of obtaining the parameter values according to the simulation results, this method greatly shortens the parameter design cycle and is more conducive to the parameter design of the system.

The present description concerns a power converter (400) comprising: a switch (114) comprising first (114d) and second (114s) conduction terminals intended to receive a first AC voltage (Vds), a first circuit (402) for detecting a minimum value reached by the first voltage at each halfwave, and for averaging minimum values over a plurality of halfwaves, and a second circuit (404) for controlling the switch configured, according to the average of said values, to turn on the switch when the first voltage is substantially null.

The utility model discloses a resonant LLC switching power supply converter and a zero-voltage switch control circuit thereof, and the converter comprises a first switch module, a second switch module, a third switch module, a fourth switch module, a first capacitor module, a second capacitor module, a third capacitor module, an inductor module, and an isolation module. The zero-voltage switch control circuit comprises a reference voltage module, a current detection module, a first control module and a second control module, and the reference voltage module, the current detection module, the first control module and the second control module work cooperatively. The switching loss of the first switching module and the second switching module of the resonant LLC switching power supply converter is dynamically controlled and greatly reduced.

The application provides a mixed control LLC series resonant converter dead-time control method, which respectively calculates the current of phase leading and lagging bridge arm switch time and the shortest dead-time required for realizing ZVS (zero voltage switching), and uses a parameter fitting method to simplify the calculation amount, and controls the dead-time of two bridge arm switches in real time on an embedded controller. The application considers the different dead-time required for realizing zero voltage switching of the two bridge arm switches of the primary side of the mixed control LLC series resonant converter, and controls in real time, so that the primary side switch loses zero voltage switching due to working condition change is prevented, and the reverse conduction time of the switch is reduced as much as possible, and the loss is reduced. The application has good application effect in the mixed control LLC series resonant converter with high frequency and wide gain range.

A protection circuit of a resonant converter including first and second switches, where the protection circuit comprises: a comparator configured to (i) compare a direct current (DC) link voltage of the resonant converter with a voltage across both ends of one of the first or second switches and (ii) output one or more signals based on the comparison, and a microcomputer configured to detect whether zero voltage switching is performed, based on the one or more output signals from the comparator.

A system includes four primary side switches of a primary bridge of a dual active bridge (DAB) converter; four secondary side switches of a secondary bridge of the DAB converter; and a control circuit configured to operate the DAB converter in a first mode in which all of the four secondary side switches operate under zero voltage switching (ZVS) and less than all of the four primary side switches operate under ZVS; and in response to a thermal condition, operating the DAB converter in a second mode in which less than all of the four secondary side switches operate at the ZVS and all of the four primary side switches operate at the ZVS. A method includes operating a control circuit of an operating system to implement a first mode and a second mode. In some embodiments, the control circuit switches between a first mode and a second mode based on one or more thermal conditions.

Embodiments of the invention relates to a three-phase bidirectional power converter (100) using a soft switching cell (120). The three-phase bidirectional power converter (100) comprises a switching network (110), a soft switching cell (120), an input (130), and a DC bus (140). The three-phase bidirectional power converter (100) is configured to: align the switches of the switching network (110) into a switching pattern, and to discharge a current from the soft switching cell (120) into the switching network (110) for zero voltage switching of the aligned switches of the switching network (110) according to the switching pattern. Furthermore, the invention also relates to a corresponding method.

A non-isolated DC-to-DC switching hybrid converter is implemented using a cross-coupled series-capacitor quadruple step-down buck converter topology. In some embodiments, the DC-to-DC switching hybrid converter includes a switched-capacitor converter circuit and incorporates a zero-voltage switching network to implement soft switching and a coupled inductor to realize a fixed step-down ratio. The hybrid converter is capable of supporting a high step-down ratio (such as 8:1) while providing high efficiency. In other embodiments, the DC-to-DC switching hybrid converter incorporates a transformer in place of the coupled inductor to further increase the step-down ratio.

Zero voltage switching with a secondary switch (e.g., a synchronous rectifier) is described herein. The method allows a secondary side controller to calculate a required secondary switch hold time. By measuring a forward pin voltage when the primary switch is conducting, the required secondary switch hold time may be determined without the need for primary to secondary communication.

The present invention discloses a control current and method for a zero-voltage switch, which utilizes a secondary-side feedback switching power supply auxiliary winding in combination with a PMOS tube to achieve the zero-voltage start-up function of the switching power supply. Compared with the existing technology, the circuit is relatively simple and has fewer circuit components, which is conducive to reducing the size of the charger and adapter.

The embodiment of the invention provides a flyback conversion circuit, a control method thereof and a control chip. The flyback conversion circuit comprises a primary side unit, a secondary side unit and an auxiliary unit, the primary side unit comprises a main switch tube and a primary side winding, the first end of the primary side winding is electrically connected with a power supply, the second end of the primary side winding is electrically connected with the first end of the main switch tube, and the second end of the main switch tube is electrically connected with reference ground; the secondary side unit comprises a secondary side winding; the auxiliary unit comprises an auxiliary switch tube, a first capacitor and an auxiliary winding; the first end of the auxiliary winding is electrically connected with the first end of the first capacitor, the second end of the first capacitor is electrically connected with the first end of the auxiliary switch tube, and the second end of the auxiliary switch tube is electrically connected with the second end of the auxiliary winding; the second end of the auxiliary winding is electrically connected with the reference ground; the second end of the primary winding, the first end of the auxiliary winding and the first end of the secondary winding are dotted terminals. The flyback conversion circuit can realize zero-voltage switching in different working modes, so that the working efficiency is improved.