CN115065222B - Full-bridge synchronous rectification starting backflow prevention circuit and electronic equipment - Google Patents

Full-bridge synchronous rectification starting backflow prevention circuit and electronic equipment Download PDF

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CN115065222B
CN115065222B CN202210989820.2A CN202210989820A CN115065222B CN 115065222 B CN115065222 B CN 115065222B CN 202210989820 A CN202210989820 A CN 202210989820A CN 115065222 B CN115065222 B CN 115065222B
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voltage
circuit
input end
backflow
rectifier
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CN115065222A (en
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张亮
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Shenzhen Injoinic Technology Co Ltd
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Shenzhen Injoinic Technology Co Ltd
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Priority to CN202211487058.4A priority patent/CN115811213A/en
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Priority to PCT/CN2022/133267 priority patent/WO2024036800A1/en
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    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/0034—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using reverse polarity correcting or protecting circuits
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
    • H02M7/2195—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration the switches being synchronously commutated at the same frequency of the AC input voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J2207/20—Charging or discharging characterised by the power electronics converter
    • 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

Abstract

The application provides an use synchronous rectification of full-bridge and start anti-backflow circuit and electronic equipment, the circuit includes: four rectifier module pieces, four rectifier module pieces connect voltage output end and two voltage input end respectively, and wherein, first voltage input end is connected to two rectifier module pieces, and second voltage input end is connected to two other rectifier module pieces, and every rectifier module piece includes: the rectification circuit comprises a backflow preventing sub-circuit and a rectification tube, wherein input ports of the backflow preventing sub-circuits of the two rectification sub-modules are connected with a first voltage input end, a control port of the backflow preventing sub-circuit is connected with a grid electrode of the rectification tube, and a drain electrode of the rectification tube is connected with a voltage output end. The application provides a technical scheme has the advantage that charging efficiency is high.

Description

Full-bridge synchronous rectification starting backflow prevention circuit and electronic equipment
Technical Field
The invention relates to the field of electronic equipment, in particular to a full-bridge synchronous rectification starting backflow-preventing circuit and electronic equipment.
Background
In the field of switching power supplies, full-bridge rectifiers are widely applied, such as half-bridge push-pull converters, full-bridge push-pull converters, wireless charging receivers and the like. The traditional full-bridge rectification mode is formed by four diodes, and the sine signal is rectified by utilizing the unidirectional conductivity of the diodes. The rectifying mode is simple in structure, does not need an extra control circuit, and is very suitable for small power application, however, along with the improvement of power, the current passing through the diodes is larger and larger, and the full-bridge rectifying mode of the four diodes cannot meet the requirement of power improvement.
The full-bridge synchronous rectification mode is that four switching tubes replace diodes, and the on-resistance of the switching tubes can be very low, so that even when heavy current is passed through, the voltage drop at two ends can be very small, the efficiency can be greatly improved, but the full-bridge synchronous rectification mode can cause synchronous rectification to enter an abnormal working state (for example, the switching tubes are conducted by mistake, namely, the current flows backwards), so that the circuit cannot be normally started, and the charging efficiency of the switching power supply is influenced.
Disclosure of Invention
The embodiment of the invention provides a full-bridge synchronous rectification starting backflow prevention circuit and electronic equipment, which can prevent current from flowing backwards and further improve the charging efficiency of a switching power supply.
In a first aspect, an embodiment of the present invention provides a full-bridge synchronous rectification startup anti-backflow circuit, where the circuit includes: four rectifier module pieces, four rectifier module pieces connect voltage output end and two voltage input end respectively, and wherein, first voltage input end is connected to two rectifier module pieces, and second voltage input end is connected to two other rectifier module pieces, and every rectifier module piece includes: a backflow preventing sub-circuit and a rectifying tube, wherein,
the input ports of the backflow preventing sub-circuits of the two rectifier sub-modules are connected with the first voltage input end, the control ports of the backflow preventing sub-circuits are connected with the grid electrodes of the rectifier tubes, and the drain electrodes of the rectifier tubes are connected with the voltage output end Vo; the source electrode of the rectifier tube is connected with the second voltage input end;
the input ports of the backflow preventing sub-circuits of the other two rectifier sub-modules are connected with the second voltage input end, the control ports of the backflow preventing sub-circuits are connected with the grid electrodes of the rectifier tubes, and the drain electrodes of the rectifier tubes are connected with the voltage output end Vo; the source of the rectifier tube is connected with the first voltage input end.
In a second aspect, an electronic device is provided, and the electronic device includes the full-bridge synchronous rectification startup anti-backflow circuit provided in the first aspect.
The embodiment of the invention has the following beneficial effects:
it can be seen that the full-bridge synchronous rectification starting anti-backflow circuit can avoid current backflow, improve the charging efficiency of the switch circuit, and reduce the charging power consumption.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of a full bridge rectifier circuit;
FIG. 2 is a schematic diagram of a full bridge synchronous rectifier circuit;
FIG. 3 is a schematic diagram of current reverse-flow after the SR1 and SR2 are conducted by mistake in full-bridge synchronous rectification;
FIG. 4 is a waveform diagram of current reverse-flow after the SR1 and SR2 are conducted by mistake in the full-bridge synchronous rectification;
FIG. 5 is a schematic diagram of a full-bridge synchronous rectification startup anti-backflow circuit provided by the present application;
fig. 6 is a schematic waveform diagram of a full-bridge synchronous rectification startup anti-backflow circuit provided in the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first," "second," "third," and "fourth," etc. in the description and claims of the invention and in the accompanying drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, result, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
Referring to fig. 1, fig. 1 is a schematic diagram of a full bridge rectifier in a wireless charging receiver, where L is a receiving inductor, C1 is a series compensation capacitor, D1 to D4 form a full bridge rectifier, co is an output capacitor, and RL is a load. When the input signal is the positive half side of the sine wave, the AC1 is positive, the AC2 is negative, the D1 and the D4 are conducted, the D2 and the D3 are cut off, and the current is transmitted to the output Vout through the D1 and the D4; when the input signal is the negative half of the sine wave, the AC1 is negative, the AC2 is positive, the D2 and the D3 are conducted, the D1 and the D4 are cut off, and the current is transmitted to the output Vout through the D2 and the D3, so that the full-range rectification function of the input signal is realized.
FIG. 2 is a schematic diagram of a full-bridge synchronous rectification, in which SR 1-SR 4 are synchronous rectifiers used to replace the diodes D1-D4 in FIG. 1, and NMOS power transistors are mostly used for the synchronous rectifiers due to the small on-resistance and the consideration of area; driver is the driving circuit for driving the synchronous rectifier and turning on and off; r g1 ~R g4 The pull-down resistor is used for discharging floating electricity when the grid of the synchronous rectifier tube floats in the air; DRV 1-DRV 4 are logic signals and provide logic control function for the driving circuit; because SR1 and SR4 are NMOS tubes, therefore the drive voltage needs to boost with respect to AC1 and AC2, D5, C2 form the boost circuit with respect to AC1, when AC1 voltage is low, VCC charges BST1 through D5, the capacitance at both ends of the capacitor is VCC-VD5, VD5 is the starting voltage of the diode, when AC1 is high, the capacitance of BST1 rises correspondingly, because the voltage at both ends of the capacitor does not change suddenly, the voltage of BST1-AC1 still keeps VCC; d6, C3 constitute a booster circuit with respect to AC2, the principle of which is the same as that of the booster circuit of AC1. The LDO circuit is used for generating a power supply voltage VCC of the driving circuit, and Cm is an output capacitor of the LDO.
When the circuit is started, the voltages of Vo and VCC are 0, the SR1 to SR4 driving circuits cannot be started, so that the body diodes can work in a follow current mode, the rising speeds of Vo and VCC are very slow due to the fact that Co is generally large, the driving circuits of SR1 to SR4 cannot work for a long time, and in the process, the gate voltage pull-down capacities of SR1 and SR2 are determined by resistors Rg1 and Rg 2. We take SR1 and its driving circuit as an example to analyze the synchronizationProblems may arise during commutation start-up. As shown in FIG. 3, C g The equivalent parasitic capacitance of the gate of SR1 is, during the start-up process, because the VCC voltage is very low, the voltage difference between BST1 and AC1 is very small, and the Driver circuit cannot work normally. When the AC1 voltage rises rapidly, the body diode of SR1 is turned on, and since the gate of SR1 is initially 0, even though AC1 passes through R g1 The gate of SR1 is charged, SR1 cannot be turned on, so SR1 is always in the OFF state. When the AC1 voltage decreases rapidly, the gate voltage of SR1 will follow the decrease, and assuming that the change of AC1 is Δ V, the gate-source voltage of SR1 is:
V GS_SR1 =ΔV（1-exp -t/τ ）
wherein, tau = R g1 *C g It can be seen that when SR1 is of constant size, R g1 Determines the discharge capability of SR1 gate voltage when R g1 The smaller, V GS_SR1 The closer to 0,SR1, the more unlikely the false turn-on is, however, after the start-up is completed, the normal operation of SR1 is turned on from R g1 Go current, therefore R g1 Smaller also means larger power consumption, and R cannot be generally adjusted to meet the power consumption requirement g1 Taking small; when R is g1 The larger the value of V GS_SR1 The larger this may cause SR1 to be turned on by mistake, causing synchronous rectification to enter an abnormal operating state. We specifically analyze the operating state of synchronous rectification after false turn-on.
As shown in FIG. 3, assume R g1 And R g2 When the inductive current flows as I1, the AC2 changes from low to high, the SR2 body diode is conducted, the AC1 changes from high to low, and the SR1 triggers false turn-on, so that the current enters the SR1 from the SR2 and returns to the C1 again, and the process does not provide energy for Vo; similarly, when the inductor current such as I2 flows, AC1 changes from low to high, the SR1 body diode is conducted, AC2 changes from high to low, and SR2 triggers false turn-on, so that the current enters SR2 from SR1 and then returns to L, and no energy is provided for Vo in the process. It can be seen that no current flows into Vo during the whole transmission process, so Vo and VCC are always 0, and the circuit cannot be started normally. The corresponding waveforms are shown in FIG. 4, and Vd represents the voltage drop of the SR 1-SR 4 body diodes. When an inductor current such as I1 flows, an AC2 voltage is derived from-Vd rises rapidly to Vd, SR2 gate-source voltage Vgs (SR 2) falls from Vd to 0, at which time SR2 turns off freewheeling by the body diode, while AC1 voltage falls rapidly from Vd to-Vd, SR1 gate-source voltage Vgs (SR 1) rises from 0 to Vd, at which time SR1 is misturned on, from which current returns into C1, due to R g1 Large, vgs (SR 1) falls very slowly, so SR1 is always in the on state during this process; when an inductor current such as I2 flows, the AC1 voltage rapidly rises from-Vd to Vd, the SR1 gate-source voltage Vgs (SR 1) falls from Vd to 0, at which time SR1 is turned off and freewheeling by a body diode is achieved, while the AC2 voltage rapidly falls from Vd to-Vd, the SR2 gate-source voltage Vgs (SR 2) rises from 0 to Vd, at which time SR2 is erroneously turned on and current returns from it to L due to the fact that R g2 Larger, vgs (SR 2) falls very slowly, so SR2 is always on in this process. No current supplies power for the output Vo in the whole process, so that the voltage of Vo and VCC is still 0 even after working for a plurality of cycles, and the full-bridge synchronous rectification current cannot normally finish starting.
The application provides an use synchronous rectification of full-bridge and start anti-backflow circuit, the circuit includes: four rectifier module pieces, four rectifier module pieces connect voltage output end and two voltage input end respectively, and wherein, first voltage input end is connected to two rectifier module pieces, and second voltage input end is connected to two other rectifier module pieces, and every rectifier module piece includes: a backflow preventing sub-circuit and a rectifying tube, wherein,
the input ports of the backflow preventing sub-circuits of the two rectifier sub-modules are connected with the first voltage input end, the control ports of the backflow preventing sub-circuits are connected with the grid electrodes of the rectifier tubes, and the drain electrodes of the rectifier tubes are connected with the voltage output end Vo; the source electrode of the rectifier tube is connected with the second voltage input end;
the input ports of the backflow preventing sub-circuits of the other two rectifier sub-modules are connected with the second voltage input end, the control ports of the backflow preventing sub-circuits are connected with the grid electrodes of the rectifier tubes, and the drain electrodes of the rectifier tubes are connected with the voltage output end Vo; the source electrode of the rectifier tube is connected with the first voltage input end.
As an example of this, it is possible to provide,
the backflow prevention sub-circuit comprises: the circuit comprises a resistor, a capacitor, a comparator, a driving unit and a triode; wherein the content of the first and second substances,
the anode of the first diode is connected with a voltage source VCC, the cathode of the first diode is connected with one comparison end of the driving unit, the other comparison end of the driving unit is connected with a second voltage input end, the output end of the driving unit is a control port of the backflow preventing sub-circuit, and the input end of the driving unit is connected with a driving logic signal;
the positive input end of the comparator is connected with the cathode of the first diode, the reverse input end of the comparator is connected with reference voltage, the output end of the comparator is connected with the grid electrode of the first triode, the source electrode of the first triode is connected with the other voltage input end, the drain electrode of the first triode is connected with the grid electrode of the second triode, the source electrode of the second triode is connected with the other voltage input end, and the drain electrode of the second triode is connected with the output end of the driving unit;
one voltage input end is connected with one end of a first resistor, the other end of the first resistor is connected with the anode of a second diode, the cathode of the second diode is connected with the output end of the driving unit, the grid of the second diode and one end of a second capacitor, and the other end of the second capacitor is connected with the other voltage input end;
one end of the first capacitor is connected with the cathode of the first capacitor, the other end of the first capacitor is connected with the other voltage input end, one end of the second resistor drives the output end of the unit, and the other end of the second resistor is connected with the other voltage input end;
the output end of the comparator is connected with one input end of the AND gate circuit, the other input end of the AND gate circuit is connected with the output end of the comparator of the corresponding rectifier submodule, and the output end of the AND gate controls whether the first triodes of the two rectifier submodules work or not.
Wherein, if the first voltage input terminal can be AC1, the second voltage input terminal can be AC2; if the first voltage input terminal may be AC2, the second voltage input terminal may be AC1.
As an example of this, it is possible to provide,
the backflow prevention sub-circuit further comprises: and the anode of the third diode is connected with the other voltage input end, and the cathode of the third diode is connected with the grid of the second triode.
Fig. 5 is a schematic diagram of a full-bridge synchronous rectification startup anti-backflow circuit provided in the present application. In FIG. 5, SR1 and SR2 are synchronous rectifiers, R g1 And R g2 The values of the pull-down resistors of the grid electrodes are larger; the diode D5 and the capacitor C2 form a charge pump circuit based on AC1, and the diode D6 and the capacitor C3 form a charge pump circuit based on AC2, and are respectively used for generating driving voltages BST1 and BST2 with a voltage difference of about VCC with respect to AC1 and AC2; DRV1 and DRV2 are respectively driving logic signals of SR1 and SR2, and control the on and off of SR1 and SR2 after passing through a Driver of a driving unit; vth1 and Vth2 are reference voltages, CMP1 is used for judging whether the voltage difference between BST1 and AC1 exceeds the reference voltage Vth1 or not, CMP2 is used for judging whether the voltage difference between BST2 and AC2 exceeds the reference voltage Vth2 or not, the output BST1OK and BST2OK of the reference voltages generate a starting completion signal BSTOK after passing through AN AND gate AN1, when BSTOK =0, the circuit is not started, SR 1-SR 4 need to be turned off, a body diode of the circuit works, when BSTOK =1, the circuit is started, SR 1-SR 4 need to be normally turned on and off, and the synchronous rectification working state is entered; r1, D7, MN1, C4, D9 and MN2 form a dynamic grid pull-down circuit of the SR1, wherein MN2 is a pull-down tube switching tube and is used as a grid pull-down tube of the synchronous rectifier SR1 by utilizing the switching characteristic of the pull-down tube switching tube; r1 is used for limiting current and has a larger value; the Schottky diode D7 is used for unidirectional current flow, only allows AC2 to charge C4, blocks current from flowing from C4 to AC2, and blocks current from flowing from C4 to AC2, wherein C4 is a voltage stabilizing capacitor, and when AC2 is lower than AC1 and is not charged, the grid voltage of MN2 can be stabilized; d9 is a voltage stabilizing diode, and the grid voltage of the MN2 can be clamped below a safe value so as to prevent the MN2 from being damaged by overhigh voltage; MN1 is a switching tube, and is turned off when BST1OK =0, and is turned on when BST1OK = 1. Correspondingly, R2, D8, MN3, C5, D10 and MN4 form a dynamic grid pull-down circuit of the SR2, wherein MN3 is a pull-down tube switching tube and is used as a grid pull-down tube of the synchronous rectifier SR2 by utilizing the switching characteristic of the pull-down tube switching tube; r2 is used for limiting current and has a larger value; the Schottky diode D8 is used for unidirectional current flow, only allows the AC1 to charge the C5, blocks the current from flowing from the C5 to the AC1, and stabilizes the grid voltage of the MN4 when the AC1 is lower than the AC2 and is not charged; d10 is a voltage regulator diode, and can clamp the gate voltage of MN4 below a safe value to prevent the voltage from being too highDamage to MN4; MN3 is a switching tube, and is turned off when BST2OK =0, and is turned on when BST2OK = 1.
The working principle of the circuit is as follows: initially, VCC is 0, BST1 is not charged with voltage, and therefore is also 0, the driving circuit is not operational, BST1OK =0, AC1 and AC2 are both 0. Let Vd be the conduction voltage of SR 1-SR 4 body diodes, vs be the forward voltage drop of Schottky diode, assume that half-cycle current flow is started to turn on SR2 body diodes, then AC2 is changed from 0 to Vd, AC1 is changed from 0 to-Vd, the voltage difference between AC2 and AC1 is 2Vd, then the charging voltage of capacitor C4 is 2Vd-Vs, because Schottky diode forward voltage drop Vs is very low, the charging voltage of C4 is about 2Vd relative to AC1, and C4 has a small value, therefore MN2 gate-source voltage can rise to 2Vd quickly, and this voltage is enough to turn on MN2 to pull down the gate of SR1 to AC1. Because SR1 can not be turned on by mistake, the current can not flow back, the current flows into the output Vo from the body diode of SR2, and VCC can rise along with the current. In the next half period, the current flows to turn on the body diode of the SR1, so that AC1 is changed from-Vd to Vd, AC2 is changed from Vd to-Vd, the voltage difference between the AC1 and the AC2 is 2Vd, the charging voltage of the capacitor C5 is about 2Vd, and the value of C5 is small, so that the gate-source voltage of MN4 can quickly rise to 2Vd, and the voltage is enough to turn on the MN4 and pull down the gate of the SR2 to the AC2. Because SR2 can not be turned on by mistake, the current can not flow back, the current flows into the output Vo from the body diode of SR1, and VCC can also continuously rise.
After Vo and VCC rise, BST1 and BST2 can be charged through D5 and D6 respectively, the voltages of BST1 and BST2 gradually rise, and the voltage difference between AC2 and AC1 is gradually increased, so that the gate-source voltages Vgs (MN 2) and Vgs (MN 4) of MN2 and MN4 are gradually increased until voltage-stabilizing tubes D9 and D10 are triggered and clamped to a certain value. After VCC rises continuously for a plurality of periods, the voltage difference between BST1 and AC1 exceeds the threshold voltage Vth1, BST1OK changes from low to high, MN1 is conducted to pull the grid voltage of MN2 to AC1 potential, namely MN2 is turned off; the voltage difference between the BST2 and the AC2 exceeds a threshold voltage Vth2, the BST2OK changes from low to high, the MN3 is conducted to pull down the grid voltage of the MN4 to the AC2 potential, namely the MN4 is turned off; BSTOK also becomes high after BST1OK and BST2OK pass through the AND gate AN1, and then the synchronous rectification working state is entered, at the moment, the driving circuit can work normally, and the power consumption of the synchronous rectification working state can not be increased due to the turning-off of MN1 and MN 2.
Fig. 6 is a waveform diagram of the current provided by the present application. In the figure, both AC1 and AC2 are 0 at the beginning, the voltage of AC1 is changed from 0 to-Vd by starting the current flowing in a half period, the voltage of AC2 is changed from 0 to Vd, therefore, a gate-source voltage Vgs (MN 2) of MN2 quickly rises to 2Vd-Vs, the grid of SR1 is pulled down to AC1, and because Vgs (MN 2) has a very small rising time, vgs (SR 1) has a small burr voltage as shown by a waveform, but the time is very short, the reverse flow current is very small, most of the current flows into an output Vo, and the VCC voltage slowly rises; the current flows in the next half cycle to change the AC2 voltage from Vd to Vd, the AC1 voltage from Vd to Vd, the Schottky diode D7 blocks the current from flowing from the gate of the MN2 to the AC2, so the gate voltage of the MN2 can be kept unchanged, namely the SR1 is kept off, the gate-source voltage Vgs (MN 4) of the MN4 rapidly rises to 2Vd-Vs, the gate of the SR2 is pulled down to the AC2, and the Vgs (MN 4) has a small rising time, so that the Vgs (SR 2) has a small glitch voltage as shown in a waveform, but the time is short, the reverse-flow current is small, most of the current is equalized to the output Vo, and the VCC voltage can continuously rise. After Vo and VCC rise, the high potential of AC1 and AC2 also rises along with the rise of Vo and can be represented as Vd + Vo, therefore Vgs (MN 2) and Vgs (MN 4) also rise along with Vo and can be represented as 2Vd + Vo-Vs, the values continuously and completely switch on MN2 and MN4, SR1 and SR2 are kept off, and when 2Vd + Vo exceeds the voltage stabilization value of voltage stabilizing tubes D9 and D10, the voltage stabilizing value is kept unchanged. After continuous operation for a plurality of cycles, VCC rises to enable BSTOK =1, the circuit enters a synchronous operation state, and it can be seen from the waveforms of AC1 and AC2 that the high potential of AC1 and AC2 after synchronous rectification is about Vo, no voltage drop of a body diode exists any more, the voltage except the dead time of the low potential is about 0, the body diode is not conducted any more, and the efficiency is greatly improved relative to BSTOK = 0. After synchronous rectification, the driving of SR1 and SR2 can work normally, MN2 and MN4 are both turned off to reduce power consumption, and as can be seen from the waveforms, vgs (MN 2) and Vgs (MN 4) are in an off state, vgs (SR 1) and Vgs (SR 2) are in a switching state, and the on and off of SR1 and SR2 are controlled.
The application also provides an electronic device, which comprises a full-bridge synchronous rectification starting backflow prevention circuit shown in fig. 5.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus may be implemented in other manners. For example, the above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one type of division of logical functions, and there may be other divisions when actually implementing, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed coupling or direct coupling or communication connection between each other may be through some interfaces, indirect coupling or communication connection between devices or units, and may be in an electrical or other form.
The above embodiments of the present invention are described in detail, and the principle and the implementation of the present invention are explained by applying specific embodiments, and the above description of the embodiments is only used to help understanding the method of the present invention and the core idea thereof; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (3)

1. The utility model provides an use full-bridge synchronous rectification start-up and prevent flowing backward circuit which characterized in that, it includes to use full-bridge synchronous rectification start-up to prevent flowing backward circuit: the backflow preventing sub-circuit comprises four rectifier tubes and four rectifier tubes, wherein the four rectifier tubes are respectively: the rectifier comprises an SR1 rectifier tube, an SR2 rectifier tube, an SR3 rectifier tube and an SR4 rectifier tube, wherein one voltage input end of a backflow preventing sub-circuit of the SR1 rectifier tube is connected with a first voltage, and the other voltage input end of the backflow preventing sub-circuit of the SR1 rectifier tube is connected with a second voltage; one voltage input end of the anti-backflow sub-circuit of the rectifier tube of SR2 is connected with a second voltage, the other voltage input end is connected with a first voltage, wherein,
the control port of the anti-backflow sub-circuit of the SR1 is connected with the grid electrode of the SR1 rectifying tube, and the drain electrode of the SR1 rectifying tube is connected with the voltage output end Vo; the source electrode of the SR1 rectifying tube is connected with a second voltage;
the control port of the backflow preventing sub-circuit of the SR2 is connected with the grid electrode of the SR2 rectifying tube, and the drain electrode of the SR2 rectifying tube is connected with the voltage output end Vo; the source electrode of the SR2 rectifying tube is connected with a first voltage;
the first voltage is AC1, and the second voltage is AC2;
or the first voltage is AC2 and the second voltage is AC1;
the anti-backflow subcircuit of the SR1 rectifier tube and the anti-backflow subcircuit of the SR2 rectifier tube both comprise: the circuit comprises a resistor, a capacitor, a comparator, a driving unit and a triode; wherein the content of the first and second substances,
the anode of the first diode is connected with a voltage source VCC, the cathode of the first diode is connected with one comparison end of the driving unit, the other comparison end of the driving unit is connected with the other voltage input end, the output end of the driving unit is a control port of the anti-backflow sub-circuit, and the input end of the driving unit is connected with a driving logic signal;
the positive input end of the comparator is connected with the cathode of the first diode, the reverse input end of the comparator is connected with reference voltage, the output end of the comparator is connected with the grid electrode of the first triode, the source electrode of the first triode is connected with the other voltage input end, the drain electrode of the first triode is connected with the grid electrode of the second triode, the source electrode of the second triode is connected with the other voltage input end, and the drain electrode of the second triode is connected with the output end of the driving unit;
one voltage input end is connected with one end of a first resistor, the other end of the first resistor is connected with the anode of a second diode, the cathode of the second diode is connected with the grid of a second triode and one end of a second capacitor, and the other end of the second capacitor is connected with the other voltage input end;
one end of the first capacitor is connected with the cathode of the first diode, the other end of the first capacitor is connected with the other voltage input end, one end of the second resistor is connected with the output end of the driving unit, and the other end of the second resistor is connected with the other voltage input end; the output end of the comparator is connected with the input end of the AND gate circuit;
one input end of the AND gate circuit is connected with the output end of a comparator in the backflow preventing sub-circuit of the SR1 rectifying tube, the other input end of the AND gate circuit is connected with the output end of the comparator in the backflow preventing sub-circuit of the SR2 rectifying tube, and output signals of the output end of the AND gate are used for judging that the backflow preventing sub-circuit of the SR1 rectifying tube and the backflow preventing sub-circuit of the SR2 rectifying tube are started.
2. The full-bridge synchronous rectification startup backflow-preventing circuit applied to the claim 1,
the anti-backflow subcircuit of the SR1 rectifier tube and the anti-backflow subcircuit of the SR2 rectifier tube both comprise: and the anode of the third diode is connected with the other voltage input end, and the cathode of the third diode is connected with the grid electrode of the second triode.
3. An electronic device, characterized in that the electronic device comprises the application full-bridge synchronous rectification startup backflow-preventing circuit as claimed in any one of claims 1-2.
CN202210989820.2A 2022-08-18 2022-08-18 Full-bridge synchronous rectification starting backflow prevention circuit and electronic equipment Active CN115065222B (en)

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CN202210989820.2A CN115065222B (en) 2022-08-18 2022-08-18 Full-bridge synchronous rectification starting backflow prevention circuit and electronic equipment
CN202211487058.4A CN115811213A (en) 2022-08-18 2022-08-18 Full-bridge synchronous rectification starting anti-backflow circuit and related electronic equipment
PCT/CN2022/133267 WO2024036800A1 (en) 2022-08-18 2022-11-21 Anti-backflow circuit started by using full-bridge synchronous rectification, and electronic device

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