CN111162676B - Flyback power supply circuit and zero voltage switching control circuit and control method thereof - Google Patents
Flyback power supply circuit and zero voltage switching control circuit and control method thereof Download PDFInfo
- Publication number
- CN111162676B CN111162676B CN201910388025.6A CN201910388025A CN111162676B CN 111162676 B CN111162676 B CN 111162676B CN 201910388025 A CN201910388025 A CN 201910388025A CN 111162676 B CN111162676 B CN 111162676B
- Authority
- CN
- China
- Prior art keywords
- zero
- control
- synchronous rectification
- signal
- voltage switching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Dc-Dc Converters (AREA)
Abstract
A flyback power supply circuit and a zero voltage switching control circuit and a control method thereof. The zero voltage switching control circuit is used for controlling a flyback power supply circuit and comprises: a primary side control circuit for generating a switching signal to control the primary side switch; the secondary side control circuit is used for generating a synchronous rectification control signal to control the synchronous rectification switch, the synchronous rectification control signal is provided with a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave controls the synchronous rectification switch to realize secondary side synchronous rectification; the secondary side control circuit determines the trigger time point of the zero voltage switching pulse according to the waveform characteristics of the ringing signal so as to control the synchronous rectification switch to conduct the zero voltage switching period and enable the primary side switch to realize zero voltage switching. The primary side control circuit or the secondary side control circuit comprises a jitter controller for generating a jitter signal and executing jitter control on the zero voltage switching pulse wave.
Description
Technical Field
The present invention relates to a flyback power supply circuit, a zero voltage switching control circuit and a control method thereof, and more particularly to a flyback power supply circuit capable of realizing zero voltage switching. The invention also relates to a zero-voltage switching control circuit used in the flyback power supply circuit and a control method thereof.
Background
Fig. 1 shows a prior art flyback power supply circuit (flyback power supply circuit 1), in which a primary side control circuit 85 controls a primary side switch S1 to switch a power transformer 10 to generate an output voltage VO, and a secondary side control circuit 95 is used to generate a synchronous rectification control signal S2C to control a synchronous rectification switch S2 to perform synchronous rectification on a secondary side.
The prior art shown in fig. 1 has the disadvantage that the synchronous rectification switch S2 cannot be accurately synchronized with the primary side switch S1 on the primary side in real time, and the primary side switch S1 has poor power conversion efficiency without zero voltage switching.
Compared with the prior art of fig. 1, the invention can accurately switch the primary side switch S1 and the synchronous rectification switch S2 synchronously by the ringing signal, and can realize zero voltage switching when the primary side switch S1 is switched, thereby effectively improving the power conversion efficiency. In addition, the invention further performs jitter control on the zero voltage switching pulse in the synchronous rectification control signal to reduce electromagnetic interference (Electromagnetic Interference, EMI).
Disclosure of Invention
In one aspect, the present invention provides a zero-voltage switching control circuit for a flyback power supply circuit for converting an input voltage to generate an output voltage, the zero-voltage switching control circuit comprising: a primary side control circuit for generating a switching signal to control a primary side switch to switch a primary side winding of a power transformer, wherein the primary side winding is coupled to the input voltage; and a secondary side control circuit for generating a synchronous rectification control signal for controlling a synchronous rectification switch to switch a secondary side winding of the power transformer to generate the output voltage, wherein the synchronous rectification control signal has a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave is used for controlling the synchronous rectification switch to conduct a synchronous rectification period to realize secondary side synchronous rectification; after the synchronous rectification pulse wave is finished, the secondary side control circuit determines the triggering time point of the zero voltage switching pulse wave according to the waveform characteristic of a ringing signal so as to control the synchronous rectification switch to conduct a preset zero voltage switching period, thereby enabling the primary side switch to realize zero voltage switching; wherein the ringing signal is related to a ringing current of the power transformer; the primary side control circuit or the secondary side control circuit comprises a jitter controller for generating a jitter signal to execute jitter control on the zero voltage switching pulse wave.
In another aspect, the present invention also provides a flyback power supply circuit for converting an input voltage to generate an output voltage, the flyback power supply circuit comprising: a power transformer coupled between the input voltage and the output voltage; a primary side switch coupled to a primary side winding of the power transformer, wherein the primary side winding is coupled to the input voltage; a synchronous rectification switch coupled to a secondary side winding of the power transformer, wherein the secondary side winding is coupled to the output voltage; and a zero voltage switching control circuit comprising: a primary side control circuit for generating a switching signal to control the primary side switch to switch the primary side winding of the power transformer; and a secondary side control circuit for generating a synchronous rectification control signal for controlling the synchronous rectification switch to switch the secondary side winding of the power transformer to generate the output voltage, wherein the synchronous rectification control signal has a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave is used for controlling the synchronous rectification switch to conduct a synchronous rectification period to realize secondary side synchronous rectification; after the synchronous rectification pulse wave is finished, the secondary side control circuit determines the triggering time point of the zero voltage switching pulse wave according to the waveform characteristic of a ringing signal so as to control the synchronous rectification switch to conduct a preset zero voltage switching period, thereby enabling the primary side switch to realize zero voltage switching; wherein the ringing signal is related to a ringing current of the power transformer; the primary side control circuit or the secondary side control circuit comprises a jitter controller for generating a jitter signal to execute jitter control on the zero voltage switching pulse wave.
In a preferred embodiment, the jitter controller generates the jitter signal in a random, pseudo-random and/or predetermined timing manner.
In a preferred embodiment, the secondary side control circuit determines a trigger time point of the zero voltage switching pulse according to the waveform characteristic, so as to control the synchronous rectification switch to conduct the preset zero voltage switching period before the primary side switch is conducted, so that in a stable state, the trigger time point of the zero voltage switching pulse is earlier than the trigger time point of the switching signal by a preset time difference, and the primary side switch realizes zero voltage switching; wherein the predetermined time difference is related to a ringing period of the ringing signal.
In a preferred embodiment, the flyback power supply operates in a discontinuous conduction mode (DCM-Discontinuous Conduction Mode).
In a preferred embodiment, the waveform is characterized by a peak, a trough, a rising edge or a falling edge of the ringing signal.
In a preferred embodiment, the jitter controller performs jitter control on the trigger timing of the zero-voltage switching pulse.
In a preferred embodiment, the jitter controller performs jitter control on a feature threshold of the waveform feature.
In a preferred embodiment, the ringing signal includes a primary side voltage across the primary side switch and/or a secondary side voltage across the primary side switch, the secondary side voltage across the synchronous rectifier switch.
In a preferred embodiment, the primary side voltage across is taken through another winding of the power transformer than the primary side winding.
In a preferred embodiment, the primary side control circuit includes the jitter controller, and the jitter signal is transferred to the secondary side control circuit via a pulse transformer to perform jitter control on the zero-voltage switching pulse.
In another aspect, the present invention also provides a flyback power supply circuit control method for controlling a flyback power supply circuit to convert an input voltage to generate an output voltage, the flyback power supply circuit control method comprising: generating a switching signal to control a primary side switch to switch a primary side winding of a power transformer, wherein the primary side winding is coupled to the input voltage; generating a synchronous rectification control signal to control a synchronous rectification switch to switch a secondary side winding of the power transformer to generate the output voltage, wherein the synchronous rectification control signal is provided with a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave is used for controlling the synchronous rectification switch to conduct a synchronous rectification period to realize secondary side synchronous rectification; executing jitter control on the zero-voltage switching pulse wave; wherein the step of generating the synchronous rectification control signal comprises: determining a trigger time point of the zero voltage switching pulse according to a waveform characteristic of the ringing signal so as to control the synchronous rectification switch to conduct a preset zero voltage switching period, thereby enabling the primary side switch to realize zero voltage switching; wherein the ringing signal is associated with a ringing current of the power transformer.
The objects, technical contents, features and effects achieved by the present invention will be more readily understood from the following detailed description of specific embodiments.
Drawings
FIG. 1 is a schematic diagram of a prior art flyback power supply.
Fig. 2A-2B are schematic diagrams illustrating an embodiment of a flyback power supply circuit according to the present invention.
Fig. 3A shows waveforms corresponding to an embodiment of the zero-voltage switching control circuit of the present invention.
Fig. 3B and 3C show synchronous rectification control signals for which the dither control is not performed and the zero-voltage switching pulse is performed, respectively.
Fig. 3D is a schematic diagram of the electromagnetic interference signal spectrum of the zero-voltage switching pulse without performing and performing the dithering control.
Fig. 4 shows a schematic diagram of an embodiment of a flyback power supply circuit according to the present invention.
Detailed Description
The drawings in the present invention are schematic and are mainly intended to represent coupling relationships between circuits and relationships between signal waveforms, which are not drawn to scale.
Referring to fig. 2A, an embodiment of a zero voltage switching control circuit (zero voltage switching control circuit 500) of the present invention is shown, wherein the zero voltage switching control circuit 500 is used in the flyback power supply circuit 2 to control the flyback power supply circuit 2 to convert an input voltage VIN to generate an output voltage VO. The flyback power supply circuit 2 includes a power transformer 10, a primary side switch S1, a synchronous rectification switch S2, and a zero voltage switching control circuit 500. The zero voltage switching control circuit 500 includes a primary side control circuit 80 and a secondary side control circuit 90. The primary side control circuit 80 is configured to generate a switching signal S1C, wherein the switching signal S1C is configured to control the primary side switch S1 to switch the primary winding W1 of the power transformer 10, and the primary winding W1 is coupled to the input voltage VIN. The secondary side control circuit 90 is configured to generate a synchronous rectification control signal S2C to control on and off of the synchronous rectification switch S2, so as to switch the secondary winding W2 of the power transformer 10, thereby generating the output voltage VO.
Referring to fig. 3A, fig. 3A shows a waveform diagram of an embodiment of a zero voltage switching control circuit according to the present invention. According to the present invention, the synchronous rectification control signal S2C has a synchronous rectification pulse PSR and a zero voltage switching pulse PZV. For example, when the primary switch S1 is turned on and then turned off again in the switching period T1 (as shown in the time point T1 of the falling edge of the switching signal S1C in the switching period T1 in fig. 3A), the synchronous rectification pulse PSR is used to control the synchronous rectification switch S2 to turn on for a synchronous rectification period t_sr to achieve synchronous rectification on the secondary side. Wherein the synchronous rectification period t_sr is substantially synchronized with the on time of the induced current of the secondary side winding W2. In other words, the synchronous rectification period t_sr starts when the secondary winding W2 transfers energy from the primary winding W1 to generate the induced current (time T1), and ends when the induced current of the secondary winding W2 drops to 0 (time T2), so that the power conversion efficiency can be improved.
The zero-voltage switching pulse PZV is used for realizing the zero-voltage switching of the primary switch S1. When the power transformer 10 Is demagnetized (demagnetized) and the synchronous rectification switch S2 Is turned on again in the switching period T1 (as shown in time T3 of fig. 3A) according to the zero voltage switching pulse PZV, the power transformer 10 induces the circulating current Is in the secondary winding W2 (as shown in fig. 3A), that Is, when the secondary current ISR Is negative (as shown in time T3 to time T4), the circulating current Is transfers energy from the output capacitor CO to the secondary winding W2, and when the synchronous rectification switch S2 Is turned off again at the end of the zero voltage switching pulse PZV (as shown in time T4), the power transformer 10 induces the circulating current Ip in the primary winding W1, which discharges the parasitic capacitor CP of the primary switch S1 to substantially 0V and charges back to the input capacitor CI, and when the primary switch S1 Is turned on in the following switching period T2 (as shown in time T5 of fig. 3A), the power transformer 10 can realize the zero voltage switching of the primary switch S1 to the Zero Voltage (ZVS).
The aforementioned "zero-voltage switching" means that, before the transistor (corresponding to the primary side switch S1) is turned on, the residual voltage of the parasitic capacitance of the transistor is discharged to 0V through the energy-free discharging path (corresponding to the primary side winding W1, for example) and the charge is charged back into the energy-free element (corresponding to the input capacitance CI, for example), so that when the transistor is turned on, the drain-source voltage of the transistor is reduced to 0V, and the parasitic Capacitance (CP) is not discharged with the on-resistance of the transistor, thereby improving the power conversion efficiency.
In addition, it should be noted that: since the parasitic effects of the circuit components themselves or the mutual matching between the components are not necessarily ideal, although the parasitic capacitance CP is intended to be discharged to 0V, it may not be possible to accurately discharge to 0V, but only to approximately 0V, that is, according to the present invention, it is acceptable that the voltage after the parasitic capacitance CP is discharged and 0V have a certain degree of error due to the circuit non-ideality, which means that the foregoing discharging is to be "approximately" 0V, and other references are also made herein to "approximately".
Specifically, in a preferred embodiment, the zero-voltage switching control circuit of the present invention is configured to control the flyback power supply circuit to operate in a discontinuous conduction mode (DCM-Discontinuous Conduction Mode), and synchronize the switching signal S1C and the zero-voltage switching pulse PZV by a ringing signal associated with a ringing current of the power transformer 10, so that the primary-side switch S1 realizes zero-voltage switching, and details thereof will be described later.
The ringing current refers to a resonance with a ringing period between each winding of the power transformer 10 and a capacitor or parasitic capacitance coupled to each other when the flyback power supply circuit is operated in the discontinuous conduction mode, i.e. the secondary side current ISR is reduced to 0 after the synchronous rectification pulse PSR is ended (time t 2), and the ringing current is generated on each winding, and during the occurrence of the ringing current, a signal related to the ringing current can be obtained at, for example, the primary side voltage across VDS1 and/or the secondary side voltage across VDS2, which is referred to herein as a ringing signal. In other words, in one embodiment, the ring signal includes a primary side voltage across VDS1 and/or a secondary side voltage across VDS2. The primary side voltage across VDS1 refers to a voltage across the current inflow end and the current outflow end of the primary side switch S1, and the secondary side voltage across VDS2 refers to a voltage across the current inflow end and the current outflow end of the synchronous rectification switch S2. Note that, in the case where the power transformer 10 and other components are both in a fixed condition, the ringing period of the ringing signal is substantially constant, so that the ringing signal is used for synchronous control of the switching signal S1C and the zero-voltage switching pulse PZV.
With continued reference to fig. 3A, in one embodiment, after the synchronous rectification pulse PSR is finished, the primary side control circuit 80 determines a trigger time point of the next switching signal S1C according to the first waveform characteristic of the ringing signal, so as to control the primary side switch S1 to be turned on again; the secondary side control circuit 90 determines the trigger time of the next zero voltage switching pulse PZV according to the second waveform characteristic of the ringing signal and a jitter signal to control the synchronous rectification switch S2 to conduct the preset zero voltage switching period t_zvs after the synchronous rectification period t_sr, thereby enabling the primary side switch S1 to realize zero voltage switching. The primary side control circuit 80 or the secondary side control circuit 90 includes a jitter controller 70 (e.g., the jitter controller 70 shown in fig. 2A is located in the secondary side control circuit 90) for generating a jitter signal for performing jitter control on the zero voltage switching pulse PZV.
The first waveform feature or the second waveform feature may be, for example, but not limited to, a peak, a trough, a rising edge, or a falling edge of the ringing signal, or a waveform feature related to a slope of the ringing signal.
With continued reference to fig. 3A, in a specific embodiment, the switching signal S1C switches the primary side switch S1 according to a switching period (e.g., corresponding to the switching periods T1, T2 and T3 in fig. 3A), wherein the triggering timing of the switching signal S1C is synchronized with one trough or one falling edge of the primary side voltage VDS1 in a current switching period of the switching period, and in a preferred embodiment, the triggering timing of the switching signal S1C is synchronized with one trough of the primary side voltage VDS1, so that the power conversion efficiency can be further improved.
For example, as shown in fig. 3A, the trigger timing of the switching signal S1C is synchronized with the second trough v2 of the primary side voltage VDS1 in the switching period T1 (and starts the switching period T2), or the third trough v3 of the switching period T2 (and starts the switching period T3), or the third trough v3 of the switching period T3 (and starts the next switching period), in practical applications, the trigger timing of the switching signal S1C may be delayed or advanced according to the input voltage VIN or the load, or may be delayed or advanced according to the setting change of the output voltage, and the mechanism of the present invention synchronizes the trigger timing of the switching signal S1C with the first waveform characteristic of the ringing signal, such as one trough or one falling edge of the primary side voltage VDS 1.
With continued reference to fig. 3A, in one embodiment, during a current switching period of the switching period, the trigger time of the zero-voltage switching pulse PZV is determined based on the occurrence time of a predetermined number of second waveform features of the ring signal and based on the jitter signal (to perform jitter control on the zero-voltage switching pulse PZV). The "preset number" is related to the number of the first waveform features or the number of the second waveform features in the previous switching period of the current switching period, so that the triggering time of the zero-voltage switching pulse PZV is earlier than the triggering time of the switching signal S1C by a preset time difference in the steady state, thereby enabling the primary-side switch S1 to realize zero-voltage switching.
In a more specific embodiment, in the current switching period, the triggering time of the zero voltage switching pulse PZV is determined based on the occurrence time of the first preset number of peaks or rising edges of the primary side voltage across VDS1 and then based on the dithering signal (to perform dithering control on the zero voltage switching pulse PZV), wherein the preset number is the total number of troughs or falling edges of the primary side voltage across VDS1 in the previous switching period minus 1.
In detail, please refer to fig. 3A, in which, in the embodiment, if the "current switching period" is T2, the "previous switching period" is T1, as shown in fig. 3A, the total number of primary-side cross voltage VDS1 valleys in the previous switching period T1 is 2 (i.e. the valleys v1 and v2 in T1), and in this embodiment, the trigger time of the zero-voltage switching pulse PZV in the current switching period T2 is: the 1 st peak of the primary side voltage across VDS1 (the total number 2 of the troughs or the falling edges of the primary side voltage across VDS1 in the previous switching period T1 is reduced by 1 and is equal to 1, so that the 1 st peak is adopted in the switching period T2) is taken as a reference, and the time point of occurrence of the peak p1 in the switching period T2 is determined according to the jitter signal. In the case where the "current switching period" is the switching period T3 and the "previous switching period" is the switching period T2, as shown in fig. 3A, the total number of the primary-side cross voltage VDS1 valleys in the previous switching period T2 is 3 (i.e. the valleys v1, v2 and v3 in T2), and in this embodiment, in the current switching period T3, the trigger time of the zero-voltage switching pulse PZV is as follows: the timing of occurrence of the 2 nd peak (3-1=2) of the primary-side cross voltage VDS1 (i.e., the timing of occurrence of the peak p2 in the switching period T3) is determined based on the dither signal.
In the above embodiment, the triggering time of the switching signal S1C is synchronous with one trough (the first waveform feature) of the primary side voltage across VDS1, and the triggering time of the zero voltage switching pulse PZV is based on the occurrence time of the first preset number of peaks (the second waveform feature) of the primary side voltage across VDS1, and since the preset number is preferably less than 1 with respect to the total number of troughs (the first waveform feature) in the previous switching period, when the flyback power supply circuit is operated in the steady state (step state), the reference triggering time of the zero voltage switching pulse PZV is expected to be earlier than the triggering time of the switching signal S1C by a preset time difference, thereby enabling the primary side switch S1 to realize zero voltage switching. It is noted that, according to the present invention, the aforementioned predetermined time difference is related to the ringing period of the ringing signal. Specifically, in the present embodiment, as shown in fig. 3A, in the steady state, the preset time difference is, for example, but not limited to, about 1/4 of the ringing period (for example, the time difference between the ending time of the zero voltage switching pulse PZV and the occurrence time of v3 in the switching period T3) plus the zero voltage switching period t_zvs.
According to the spirit of the present invention, when the control is performed similarly to the above-mentioned control by the relation of different first waveform characteristics, second waveform characteristics, preset number, etc., various preset time differences can be obtained, which can be related to 1/8, 1/2, 3/4 or integer number of ringing periods, and the combination of the above, those skilled in the art should know according to the teaching of the present invention, and the details thereof are not repeated herein.
In a broader aspect, the secondary control circuit 90 determines a reference of the triggering time of the zero-voltage switching pulse PZV according to the second waveform characteristic to control the synchronous rectification switch S2 to conduct for a preset zero-voltage switching period t_zvs before the primary switch S1 is conducted, so that the triggering time of the zero-voltage switching pulse PZV is earlier than the triggering time of the switching signal S1C by a preset time difference in a steady state, thereby enabling the primary switch S1 to realize zero-voltage switching.
As described above, since the triggering timing of the switching signal S1C may be advanced or delayed according to the condition of the power supply or the load, in an embodiment, in the present switching period, when the triggering timing of the zero voltage switching pulse PZV is later than the triggering timing of the switching signal S1C, the zero voltage switching pulse PZV is not triggered, in other words, in this case, the zero voltage switching pulse PZV may be skipped and not triggered in the present switching period, but according to the control mechanism described above, the above relationship may be restored after several switching periods to trigger the zero voltage switching pulse PZV.
It should be noted that, in an embodiment, in order to not overlap the zero-voltage switching pulse PZV with the switching signal S1C, the above-mentioned condition can be expanded such that the zero-voltage switching pulse PZV is not triggered when the time difference between the triggering time of the zero-voltage switching pulse PZV and the triggering time of the switching signal S1C is smaller than a time threshold.
On the other hand, as shown in fig. 3A, in the switching period T2, the triggering time of the switching signal S1C is, for example, due to the condition of the power supply or the load or delayed (compared to the switching period T1), so that the time difference between the zero voltage switching pulse PZV and the reference triggering time of the switching signal S1C is 1.5 ringing periods plus the zero voltage switching period t_zvs in the switching period T2, although this may make the zero voltage switching of the primary side switch S1 in the switching period T2 slightly less effective, the operation according to the present invention may still be resumed in a steady state (for example, the switching period T3) after several periods, in other words, the reference triggering time of the zero voltage switching pulse PZV is earlier than the aforementioned preset time difference (for example, the relationship in the switching period T3) of the triggering time of the switching signal S1C, thereby enabling the primary side switch S1 to realize the zero voltage switching.
With continued reference to fig. 3A, as described above, in an embodiment, the ring signal may also be the secondary side voltage VDS2, so that the reference trigger point of the zero voltage switching pulse PZV may also be determined by the secondary side voltage VDS2, as shown in fig. 3A, in an embodiment, the reference trigger point of the zero voltage switching pulse PZV is the occurrence point of the second side voltage VDS2 with a predetermined number of troughs (e.g., the 2 nd trough in the switching period T3 in fig. 3A) or the falling edges in the previous switching period (e.g., the switching period T2), wherein the predetermined number is the total number of troughs or the falling edges of the secondary side voltage VDS2 in the previous switching period (e.g., the switching period T2 has a total of 2 troughs in the switching period T2 in fig. 3A).
Since the voltages of the windings of the transformer have a certain relationship with each other, the primary side across voltage VDS1 may be obtained by another winding other than the primary side winding W1 of the power transformer 10, such as the secondary side winding W2 or other windings, such as the auxiliary winding WA, specifically, the primary side across voltage VDS1 equivalent may be obtained by the secondary side across voltage VDS2 or the auxiliary voltage VM (fig. 2A).
In one embodiment, each peak or each rising edge of the ring signal may be determined by detecting that the ring signal rises to a first voltage threshold, and in another embodiment, each trough or each falling edge of the ring signal may be determined by detecting that the ring signal falls to a second voltage threshold.
With continued reference to fig. 3A, in an embodiment, in the case that the ring signal corresponds to the primary side voltage VDS1, the first voltage threshold corresponding to the primary side voltage VDS1 may be, for example, a voltage threshold VT1H as shown in fig. 3A, and in an embodiment, the voltage threshold VT1H is related to the input voltage VIN, for example, the voltage threshold VT1H is equal to the input voltage VIN, or the voltage threshold VT1H is the input voltage VIN plus an offset value, so that the voltage threshold VT1H is higher than the input voltage VIN and is closer to the peak of the primary side voltage VDS 1.
With continued reference to fig. 3A, in an embodiment, in the case where the ring signal corresponds to the primary side voltage VDS1, the second voltage threshold corresponding to the primary side voltage VDS1 may be, for example, a voltage threshold VT1L as shown in fig. 3A, and in an embodiment, the voltage threshold VT1L is related to the input voltage VIN, for example, the voltage threshold VT1H is equal to the input voltage VIN, or the voltage threshold VT1H is the input voltage VIN minus an offset value, such that the voltage threshold VT1H is lower than the input voltage VIN and is closer to the trough of the primary side voltage VDS 1.
The manner of obtaining the peaks, valleys, rising edges or falling edges can be analogized to the secondary side cross-voltage VDS2.
With continued reference to fig. 3A, for example, in the case where the ring signal corresponds to the secondary side voltage across VDS2, the second voltage threshold corresponding to the secondary side voltage across VDS2 may be, for example, a voltage threshold VT2L as shown in fig. 3A, and in an embodiment, the voltage threshold VT2L is related to the output voltage VO, for example, the voltage threshold VT2L is equal to the output voltage VO, or the voltage threshold VT2L is a divided voltage of the output voltage VO, so that the voltage threshold VT2L is lower than the output voltage VO and is closer to the trough of the secondary side voltage across VDS2.
It should be noted that, when the flyback power supply circuit operates in a steady state, it is expected that the reference trigger point of the zero-voltage switching pulse PZV and the switching timing of the switching signal S1C will trigger at substantially the fixed time point of the current switching cycle, that is, the switching frequency of the flyback power supply circuit 2 will be a relatively fixed value, which results in relatively high electromagnetic interference generated due to the electromagnetic induction effect during the operation of the flyback power supply circuit. In the present invention, the interference signal generated by the zero-voltage switching pulse PZV is represented by an electromagnetic interference (EMI) signal. Fig. 3D shows a schematic diagram of the electromagnetic interference signal spectrum without performing and with performing jitter control on the zero-voltage switching pulse PZV. The electromagnetic interference signal is formed as an interference signal having a relatively high intensity at a specific frequency (generally, corresponding to the switching frequency) due to the fixed reference trigger timing of the zero-voltage switching pulse PZV, as shown by the dashed waveform in fig. 3D, wherein the horizontal axis of fig. 3D represents the frequency and the vertical axis represents the electromagnetic interference signal (e.g., but not limited to, in dB or V).
For this reason, according to the present invention, the dither controller (e.g., the dither controller 70 shown in fig. 2A) generates a dither signal for performing dither control (jitter control) on the zero-voltage switching pulse PZV to spread the electromagnetic interference signal (spread spectrum) so as to avoid the electromagnetic interference signal from being excessively concentrated at a specific frequency, thereby reducing electromagnetic interference. The electromagnetic interference signal spectrum diagram for performing the dither control on the zero-voltage switching pulse PZV is illustrated as a solid line waveform in fig. 3D. For example, electromagnetic interference signals such as, but not limited to, those generated by the primary winding, the secondary winding, and/or the auxiliary winding are generated by operation of the flyback power supply circuit.
The dithering signal may be used to perform dithering control (jitter control) on the zero-voltage switching pulse PZV, such as, but not limited to, by a dithering controller (e.g., dithering controller 70 of fig. 2A) that generates the dithering signal in a random, pseudo-random, and/or predetermined timing manner. The dither signal performs dither control, for example, on the trigger timing of the zero-voltage switching pulse. In one embodiment, as shown in fig. 3C, in contrast to fig. 3B, fig. 3B shows a synchronous rectification control signal S2C that does not perform jitter control on the zero-voltage switching pulses PZV1, PZV2, and PZV 3; fig. 3C shows a synchronous rectification control signal S2C 'for performing dither control on the zero-voltage switching pulses PZV', PZV2', and PZV'. As shown in fig. 3C, the jitter controller generates a jitter signal, for example, in a predetermined timing manner, and the jitter signal performs jitter control on the trigger points of the zero-voltage switching pulses PZV ', PZV2', PZV 'such that the trigger points of the zero-voltage switching pulses PZV1', PZV2', PZV' are respectively time T3 plus Δt, time T3 plus 2Δt and time T3 plus 3Δt, and so on in the switching periods T1, T2, T3. The above combinations of the timing and Δt are only examples and not limiting, and other predetermined timing, random timing or pseudo-random timing may be used according to the present invention. The control method of the jitter signal is not limited to discrete time jitter, and may be continuous time jitter.
Of course, the manner in which the dither signal performs the dither control (jitter control) on the zero-voltage switching pulse PZV is not limited thereto, and it is within the scope of the present invention for the dither signal to cause the dither effect at the trigger point of the zero-voltage switching pulse PZV, resulting in the spread of the electromagnetic interference signal as illustrated by the solid line waveform in fig. 3D. In one embodiment, the dither signal generated by the dither controller performs dither control on a feature threshold of the waveform feature. For example, the characteristic threshold is, but not limited to, the aforementioned voltage threshold VT1H, voltage threshold VT1L, voltage threshold VT2L, or the like; that is, the dithering signal generated by the dithering controller performs dithering control on the voltage threshold VT1H, the voltage threshold VT1L, or the voltage threshold VT2L, so that the triggering time of the zero-voltage switching pulse PZV has a dithering effect, resulting in spreading of the electromagnetic interference signal as illustrated by the solid-line waveform in fig. 3D.
Referring to fig. 4, a flyback power supply circuit (flyback power supply circuit 4) including a zero-voltage switching control circuit (zero-voltage switching control circuit 502) according to an embodiment of the present invention is shown. In the present embodiment, the pulse transformer 20 is used for coupling the synchronous rectification synchronization signal sr_sync from the primary side control circuit 100 to the secondary side control circuit 200 to generate the synchronous rectification control signal S2C; referring to fig. 3A, in detail, the synchronous rectification control signal S2C triggers the generation of the zero voltage switching pulse PZV according to the synchronous rectification synchronous signal sr_sync. That is, the jitter controller 70 is not limited to be located in the secondary side control circuit as shown in fig. 2A and 2B, but may be located in the primary side control circuit as in the primary side control circuit 100 of the present embodiment. The jitter control can be performed on the zero-voltage switching pulse PZV by coupling the synchronous rectification synchronization signal sr_sync from the primary side control circuit 100 through the pulse transformer 20 to the secondary side control circuit 200 to generate the synchronous rectification control signal S2C.
The present invention has been described in terms of the preferred embodiments, but the above description is only for the purpose of easily understanding the present invention by those skilled in the art, and is not intended to limit the scope of the claims of the present invention. The embodiments described are not limited to single applications but may be combined, for example, two or more embodiments may be combined, and portions of one embodiment may be substituted for corresponding components of another embodiment. In addition, various equivalent changes and various combinations will be apparent to those skilled in the art, and for example, the term "processing or calculating based on a signal or generating an output result" in the present invention is not limited to the processing or calculating based on the signal itself, but includes performing voltage-to-current conversion, current-to-voltage conversion, and/or scaling conversion of the signal, if necessary, and then processing or calculating based on the converted signal to generate an output result. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described herein, embody the principles of the invention and are thus equally well suited to the particular use contemplated. Accordingly, the scope of the invention should be assessed as that of the above and all other equivalent variations.
Claims (26)
1. A zero voltage switching control circuit is used in a flyback power supply circuit to convert an input voltage to generate an output voltage, and comprises:
a primary side control circuit for generating a switching signal to control a primary side switch to switch a primary side winding of a power transformer, wherein the primary side winding is coupled to the input voltage; and
a secondary side control circuit for generating a synchronous rectification control signal for controlling a synchronous rectification switch to switch a secondary side winding of the power transformer to generate the output voltage, wherein the synchronous rectification control signal has a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave is used for controlling the synchronous rectification switch to conduct a synchronous rectification period to realize secondary side synchronous rectification;
after the synchronous rectification pulse wave is finished, the secondary side control circuit determines the triggering time point of the zero voltage switching pulse wave according to the waveform characteristic of a ringing signal so as to control the synchronous rectification switch to conduct a preset zero voltage switching period before the primary side switch is conducted, so that in a stable state, the triggering time point of the zero voltage switching pulse wave is earlier than the triggering time point of the switching signal by a preset time difference, and the primary side switch realizes zero voltage switching;
wherein the ringing signal is related to a ringing current of the power transformer;
wherein the ringing current is related to resonance generated between the primary winding and/or the secondary winding of the power transformer and parasitic capacitance coupled to each other;
wherein the predetermined time difference is related to a ringing period of the ringing signal;
the primary side control circuit or the secondary side control circuit comprises a jitter controller for generating a jitter signal to execute jitter control on the zero voltage switching pulse wave.
2. The zero-voltage switching control circuit of claim 1, wherein the jitter controller generates the jitter signal in a random, pseudo-random and/or predetermined timing manner.
3. The zero-voltage switching control circuit of claim 1, wherein the flyback power supply operates in a discontinuous conduction mode.
4. The zero-voltage switching control circuit of claim 1 wherein the waveform is characterized by a peak, a trough, a rising edge, or a falling edge of the ringing signal.
5. The zero-voltage switching control circuit of claim 1, wherein the jitter controller performs jitter control on a trigger timing of the zero-voltage switching pulse.
6. The zero-voltage switching control circuit of claim 1, wherein the dithering controller performs dithering control on a characteristic threshold value of the waveform characteristic.
7. The zero-voltage switching control circuit of claim 1, wherein the ringing signal comprises a primary side voltage across the current-in and current-out of the primary side switch and/or a secondary side voltage across the current-in and current-out of the synchronous rectification switch.
8. The zero-voltage switching control circuit of claim 7 wherein the primary side voltage across is taken through another winding of the power transformer other than the primary side winding.
9. The zero-voltage switching control circuit of claim 1, wherein the primary-side control circuit includes the jitter controller, and the jitter signal is transferred to the secondary-side control circuit via a pulse transformer to perform jitter control on the zero-voltage switching pulse.
10. A flyback power supply circuit for converting an input voltage to generate an output voltage, the flyback power supply circuit comprising:
a power transformer coupled between the input voltage and the output voltage;
a primary side switch coupled to a primary side winding of the power transformer, wherein the primary side winding is coupled to the input voltage;
a synchronous rectification switch coupled to a secondary side winding of the power transformer, wherein the secondary side winding is coupled to the output voltage; and
a zero voltage switching control circuit comprising:
a primary side control circuit for generating a switching signal to control the primary side switch to switch the primary side winding of the power transformer; and
a secondary side control circuit for generating a synchronous rectification control signal for controlling the synchronous rectification switch to switch the secondary side winding of the power transformer to generate the output voltage, wherein the synchronous rectification control signal has a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave is used for controlling the synchronous rectification switch to conduct a synchronous rectification period to realize secondary side synchronous rectification;
after the synchronous rectification pulse wave is finished, the secondary side control circuit determines the triggering time point of the zero voltage switching pulse wave according to the waveform characteristic of a ringing signal so as to control the synchronous rectification switch to conduct a preset zero voltage switching period before the primary side switch is conducted, so that in a stable state, the triggering time point of the zero voltage switching pulse wave is earlier than the triggering time point of the switching signal by a preset time difference, and the primary side switch realizes zero voltage switching;
wherein the ringing signal is related to a ringing current of the power transformer;
wherein the ringing current is related to resonance generated between the primary winding and/or the secondary winding of the power transformer and parasitic capacitance coupled to each other;
wherein the predetermined time difference is related to a ringing period of the ringing signal;
the primary side control circuit or the secondary side control circuit comprises a jitter controller for generating a jitter signal to execute jitter control on the zero voltage switching pulse wave.
11. The flyback power supply of claim 10 wherein the jitter controller generates the jitter signal in a random, pseudo-random, and/or predetermined timing pattern.
12. The flyback power supply of claim 10 wherein the flyback power supply operates in a discontinuous conduction mode.
13. The flyback power supply of claim 10 wherein the waveform is characterized by a peak, a trough, a rising edge, or a falling edge of the ringing signal.
14. The flyback power supply of claim 10 wherein the jitter controller performs jitter control on the trigger point of the zero-voltage switching pulse.
15. The flyback power supply of claim 10 wherein the jitter controller performs jitter control on a characteristic threshold of the waveform characteristic.
16. The flyback power supply of claim 10 wherein the ringing signal comprises a primary side voltage across the primary side switch between the current-in and current-out terminals and/or a secondary side voltage across the synchronous rectifier switch between the current-in and current-out terminals.
17. The flyback power supply of claim 16 wherein the primary side voltage across is obtained through another winding of the power transformer other than the primary side winding.
18. The flyback power supply of claim 10 wherein the primary-side control circuit includes the dither controller and the dither signal is delivered to the secondary-side control circuit via a pulse transformer to perform dither control on the zero-voltage switching pulse.
19. A flyback power supply circuit control method is used for controlling a flyback power supply circuit to convert an input voltage to generate an output voltage, and comprises the following steps:
generating a switching signal to control a primary side switch to switch a primary side winding of a power transformer, wherein the primary side winding is coupled to the input voltage;
generating a synchronous rectification control signal to control a synchronous rectification switch to switch a secondary side winding of the power transformer to generate the output voltage, wherein the synchronous rectification control signal is provided with a synchronous rectification pulse wave and a zero voltage switching pulse wave, and the synchronous rectification pulse wave is used for controlling the synchronous rectification switch to conduct a synchronous rectification period to realize secondary side synchronous rectification; and
executing jitter control on the zero-voltage switching pulse wave;
wherein the step of generating the synchronous rectification control signal comprises: determining a triggering time point of the zero-voltage switching pulse wave according to a waveform characteristic of a ringing signal, so as to control the synchronous rectification switch to conduct a preset zero-voltage switching period before the primary side switch is conducted, so that in a stable state, the triggering time point of the zero-voltage switching pulse wave is earlier than the triggering time point of the switching signal by a preset time difference, and the primary side switch realizes zero-voltage switching;
wherein the ringing signal is related to a ringing current of the power transformer;
wherein the ringing current is related to resonance generated between the primary winding and/or the secondary winding of the power transformer and parasitic capacitance coupled to each other;
wherein the predetermined time difference is related to a ringing period of the ringing signal.
20. The flyback power supply circuit control method of claim 19 wherein performing dither control on the zero-voltage switching pulse comprises: a dithering signal is generated in a random, pseudo-random and/or predetermined timing manner to perform dithering control on the zero voltage switching pulse.
21. The flyback power supply circuit control of claim 19 wherein the flyback power supply operates in a discontinuous conduction mode.
22. The flyback power supply control method of claim 19 wherein the waveform is characterized by a peak, a valley, a rising edge or a falling edge of the ringing signal.
23. The flyback power supply circuit control method of claim 19 wherein the step of performing dither control on the zero-voltage switching pulse comprises: and executing jitter control on the triggering time point of the zero-voltage switching pulse wave.
24. The flyback power supply circuit control method of claim 19 wherein the step of performing dither control on the zero-voltage switching pulse comprises: jitter control is performed on a feature threshold of the waveform feature.
25. The flyback power supply circuit control method of claim 19 wherein the ringing signal comprises a primary side voltage across the primary side switch between the current in and the current out and/or a secondary side voltage across the synchronous rectifier switch between the current in and the current out.
26. The flyback power supply circuit control method of claim 19 further comprising: after the synchronous rectification pulse is finished, determining the trigger time point of the next switching signal according to another waveform characteristic of the ringing signal so as to control the primary side switch to be turned on again.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110625292.8A CN113489328B (en) | 2018-11-08 | 2019-05-10 | Zero-voltage switching control circuit, flyback power supply circuit and control method thereof |
| US16/586,916 US10715028B2 (en) | 2018-11-08 | 2019-09-28 | Flyback power converter and ZVS control circuit and control method thereof |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201862757734P | 2018-11-08 | 2018-11-08 | |
| US62/757,734 | 2018-11-08 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110625292.8A Division CN113489328B (en) | 2018-11-08 | 2019-05-10 | Zero-voltage switching control circuit, flyback power supply circuit and control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111162676A CN111162676A (en) | 2020-05-15 |
| CN111162676B true CN111162676B (en) | 2023-07-25 |
Family
ID=70555760
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910388025.6A Active CN111162676B (en) | 2018-11-08 | 2019-05-10 | Flyback power supply circuit and zero voltage switching control circuit and control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111162676B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111628632B (en) * | 2019-02-28 | 2022-03-01 | 立锜科技股份有限公司 | Flyback power supply circuit and zero voltage switching control circuit and control method thereof |
| TWI746259B (en) * | 2020-06-02 | 2021-11-11 | 立錡科技股份有限公司 | Flyback power converter circuit and conversion control circuit and control method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103490609A (en) * | 2012-06-11 | 2014-01-01 | 电力系统技术有限公司 | Method of suppressing electromagnetic interference emission |
| CN106130349A (en) * | 2015-05-06 | 2016-11-16 | 立锜科技股份有限公司 | Flyback type electric source supply device and controller thereof and driver |
| CN107210678A (en) * | 2015-02-06 | 2017-09-26 | 德州仪器公司 | Soft handover flyback converter |
| CN108736730A (en) * | 2017-04-18 | 2018-11-02 | 立锜科技股份有限公司 | Flyback power-switching circuit and conversion control circuit therein |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9203292B2 (en) * | 2012-06-11 | 2015-12-01 | Power Systems Technologies Ltd. | Electromagnetic interference emission suppressor |
-
2019
- 2019-05-10 CN CN201910388025.6A patent/CN111162676B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103490609A (en) * | 2012-06-11 | 2014-01-01 | 电力系统技术有限公司 | Method of suppressing electromagnetic interference emission |
| CN107210678A (en) * | 2015-02-06 | 2017-09-26 | 德州仪器公司 | Soft handover flyback converter |
| CN106130349A (en) * | 2015-05-06 | 2016-11-16 | 立锜科技股份有限公司 | Flyback type electric source supply device and controller thereof and driver |
| CN108736730A (en) * | 2017-04-18 | 2018-11-02 | 立锜科技股份有限公司 | Flyback power-switching circuit and conversion control circuit therein |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111162676A (en) | 2020-05-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113489328B (en) | Zero-voltage switching control circuit, flyback power supply circuit and control method thereof | |
| US10566893B2 (en) | ZVS control circuit for use in a flyback power converter | |
| KR102225011B1 (en) | Burst mode control in resonant converters | |
| JP5181014B2 (en) | Circuit regulator and its synchronous timing pulse generation circuit | |
| US10868473B2 (en) | Secondary side controlled control circuit for power converter with synchronous rectifier | |
| US11201554B2 (en) | Flyback power converter and ZVS control circuit and control method thereof | |
| US9252676B2 (en) | Adaptive active clamp of flyback power converter with high efficiency for heavy load and light load | |
| TWI389435B (en) | Method and apparatus of provdingsynchronous regulation for offline power converter | |
| CN111628632B (en) | Flyback power supply circuit and zero voltage switching control circuit and control method thereof | |
| TWI448063B (en) | Controllers and switching methods for power converters and controlling methods for quasi-resonant power converters | |
| CN104052289A (en) | Switched mode power converter controller with ramp time modulation | |
| JP6968638B2 (en) | Modulating the jitter frequency as the switching frequency approaches the jitter frequency | |
| CN113726165B (en) | Flyback converter and control method thereof | |
| CN109768708B (en) | Zero voltage switching control circuit for flyback power supply circuit | |
| CN102723856A (en) | Synchronous rectifier control circuit and switch power supply employing same | |
| CN111162676B (en) | Flyback power supply circuit and zero voltage switching control circuit and control method thereof | |
| CN114123784A (en) | Resonant half-bridge flyback power supply and primary side control circuit and control method thereof | |
| US8373404B2 (en) | Negative lock loop and control method for a flyback voltage converter | |
| WO2022121073A1 (en) | Isolated power conversion method for demagnetization iteration control, and power conversion circuit | |
| CN104009627A (en) | Multiphase conversion controller | |
| KR100966965B1 (en) | Dc/dc converter with multi-output | |
| CN113890365B (en) | Flyback converter and switching control circuit and control method thereof | |
| CN112713778B (en) | Switching control circuit and method for controlling flyback power supply circuit | |
| KR100916488B1 (en) | Power supply synchronized with input power switching | |
| Najm et al. | A novel low cost PV micro-inverters based on analog control and interleaving method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |