CN111541361B - Synchronous rectification isolation driving circuit and synchronous rectification isolation power supply system - Google Patents
Synchronous rectification isolation driving circuit and synchronous rectification isolation power supply system Download PDFInfo
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- CN111541361B CN111541361B CN202010504773.9A CN202010504773A CN111541361B CN 111541361 B CN111541361 B CN 111541361B CN 202010504773 A CN202010504773 A CN 202010504773A CN 111541361 B CN111541361 B CN 111541361B
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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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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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
- 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
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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
- 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
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- 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
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- Power Engineering (AREA)
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- Dc-Dc Converters (AREA)
Abstract
The invention discloses a synchronous rectification isolation driving circuit and a synchronous rectification isolation power supply system. The first controller of the invention controls the on/off of the primary side switching tube and simultaneously generates a first off signal for controlling the synchronous rectifying tube to be reliably turned off; converting the first turn-off signal into a second turn-off signal through an isolator; and the second turn-off signal is used for controlling the turn-off of the synchronous rectifying tube, so that the high reliability is realized.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to a synchronous rectification isolation driving circuit with high reliability and a synchronous rectification isolation power supply system, which are suitable for application occasions of isolation power supplies needing synchronous rectification.
Background
With the development of technology, portable devices such as mobile phones, notebook computers, digital video cameras, tablet computers, etc. are increasing in number, and thus, power adapters are widely used. The power adapter is widely used, and meanwhile, a very outstanding problem is brought about, namely that the power consumption of the power adapter with the large number is very remarkable every year. At present, the use requirements of various countries on products such as adapters are more and more strict, and related energy efficiency standards are brought out, in particular to the energy efficiency and energy conservation requirements. For example, switching power supplies, chargers, power adapters require DOE certification, i.e., minimum energy consumption level requirements, before entering the united states market, which is specified in 2013 in a bulletin issued in the united states department of energy (DOE), which standard is DOE VI.
In order to meet the DOE VI standard, various power supply design companies are looking for ways to increase power efficiency, with synchronous rectification being an effective solution. The core problem of synchronous rectification technology is the design of synchronous rectification drive circuits. If the synchronous rectifying tube is turned on in advance or turned off in advance, short circuit is caused, and if the synchronous rectifying tube is turned on in advance or turned off in advance, the body diode (a diode in the MOS tube) is enabled to be too long in conduction time, and rectifying loss is increased. Therefore, synchronous rectification technology puts demands on the driving circuit to be on-time on/off. The most common synchronous rectification control method is sampling based on drain-source voltage.
Referring to fig. 1-2, fig. 1 is a schematic diagram of a conventional synchronous rectification and isolation power system, and fig. 2 is a schematic diagram of an operation logic of the synchronous rectification controller in fig. 1. As shown in fig. 1, the main components of the existing synchronous rectification isolated power supply system include: a rectifier bridge stack (which includes rectifier diodes D1, D2, D3, D4), an input capacitor Cin, a main transformer T1, a first controller 11, a second controller 12, a signal coupler 13, a synchronous rectification controller 14, an output filter capacitor Cout, and a dummy load R0.
Specifically, an alternating current power supply AC is connected to a primary winding T11 of the main transformer T1 after being rectified and filtered by the rectifier bridge stack and the input capacitor Cin; the secondary winding T12 of the main transformer T1 generates a bus voltage Vbus by outputting a filter capacitor Cout and a dummy load R0. The first controller 11 is electrically connected with the primary winding T11 of the main transformer T1, the second controller 12 is electrically connected with the first controller 11 through the signal coupler 13, and the synchronous rectification controller 14 is electrically connected with the secondary winding T12 of the main transformer T1.
The second controller 12 is configured to sample the output voltage and the sampled output current, obtain an output voltage signal Vfb, and sample the output current through the second sampling resistor Rcs2 to obtain an output current sampling signal Vcs, so as to generate a loop control signal Comp; the loop control signal Comp is transmitted to the first controller 11 via the signal coupler 13; the first controller 11 generates driving signals vgs_q1 with different frequencies or different pulse widths according to different loop control signals Comp to control on/off of the primary side switching tube Q1, and finally ensures output of constant voltage or constant current.
The synchronous rectification controller 14 works according to the following principle: sampling the drain-source voltage vds_q2 of the synchronous rectifier tube Q2, and when the drain-source voltage vds_q2 is smaller than the on threshold voltage vth_on (vds_q2 < vth_on) in the process of the drain-source voltage vds_q2 falling, the driving voltage vgs_q2 is high level, and the synchronous rectifier tube Q2 is turned on; in the process of rising the drain-source voltage vds_q2, when the drain-source voltage vds_q2 is greater than the turn-off threshold voltage vth_off (vds_q2 > vth_off), the driving voltage vgs_q2 is at a low level, the synchronous rectifier Q2 is turned off, and the working logic is as shown in fig. 2. Based on this working principle, when the flyback converter works in a Continuous Conduction Mode (CCM), the synchronous rectifier Q2 is still in a conducting state when the primary side switching tube Q1 is switched from an off state to a conducting state, so that the primary side winding and the secondary side winding of the main transformer T1 have a through phenomenon, and the primary side switching tube Q1 is easily damaged.
In the prior art, chinese patent application publication CN101527525a discloses a synchronous rectification external driving scheme by directly controlling a synchronous rectification tube after a primary side gate driving signal is transferred to a secondary side. However, the synchronous rectifying tube Q2 cannot be reliably turned on and off on time without comparing the gate signals.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art and provide a synchronous rectification isolation driving circuit and a synchronous rectification isolation power supply system, which can realize reliable on-off control of a synchronous rectification tube and can ensure that the synchronous rectification tube is always in a state of low on-resistance when being on, and have low loss and high efficiency.
In order to achieve the above object, the present invention provides a synchronous rectification isolation driving circuit, comprising: the second controller is used for sampling the output voltage and the output current and further generating a loop control signal; the signal coupler is used for acquiring the loop control signal and transmitting the loop control signal to the first controller; the first controller is used for generating a first driving signal to control the on/off of a primary side switching tube according to the loop control signal, and generating a first off signal and outputting the first off signal; the isolator is used for receiving the first turn-off signal, converting the first turn-off signal into a second turn-off signal and outputting the second turn-off signal; and a synchronous rectification controller for receiving the second turn-off signal and sampling a second drain-source voltage at both ends of a drain-source of a synchronous rectifying tube, so as to generate a second driving signal to control on/off of the synchronous rectifying tube.
In order to achieve the above purpose, the invention also provides a synchronous rectification isolation power supply system, which comprises a drive control circuit, wherein the drive control circuit adopts the synchronous rectification isolation drive circuit.
The invention has the advantages that: the first controller of the invention controls the on/off of the primary side switching tube and simultaneously generates a first off signal for controlling the synchronous rectifying tube to be reliably turned off; converting the first turn-off signal into a second turn-off signal through an isolator; and then the reliable turn-off of the synchronous rectifying tube is controlled by the second turn-off signal; the explosion phenomenon caused by the direct connection of the synchronous rectifying tube and the primary side switching tube in the synchronous rectifying power supply system can be solved, and the high reliability is realized; and the MOS tube with low on-resistance is used as the synchronous rectifying tube, so that the synchronous rectifying tube is always in a state with low on-resistance when being conducted, the loss is low, and the efficiency of the whole power supply system can be improved. The synchronous rectification isolation power supply system can be applied to an intermittent mode, a critical continuous mode and a continuous mode, and has wide application range; the reliable turn-off of the synchronous rectifying tube can be controlled, the phenomenon that the primary side switching tube and the synchronous rectifying tube are simultaneously conducted to cause the power system to blow out the machine is prevented, and the reliability is high; the flyback circuit CCM can normally work in a flyback circuit CCM mode, and the synchronous rectifying tube is always in a low on-resistance state when being conducted, so that the loss is low, and the efficiency of the whole power supply system can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a prior art synchronous rectification isolated power supply system;
FIG. 2 is a schematic diagram of the operating logic of the synchronous rectification controller of FIG. 1;
FIG. 3 is a schematic diagram of a synchronous rectification isolation driving circuit according to the present invention;
FIG. 4 is a circuit diagram of an embodiment of a synchronous rectification isolation driving circuit according to the present invention;
FIG. 5 is a schematic diagram of a second embodiment of the second controller of the present invention;
FIG. 6 is a schematic diagram of a shut down signal generator according to the present invention;
FIG. 7 is a schematic diagram of an embodiment of a synchronous rectification controller according to the present invention;
FIG. 8 is a schematic diagram of a synchronous rectification isolated power supply system according to the present invention;
FIG. 9A is a main waveform diagram of a first embodiment of the system of FIG. 8 operating in a continuous mode;
fig. 9B is a main waveform diagram of a second embodiment of the system of fig. 8 operating in a continuous mode.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention. The terms first, second, third and the like in the description and in the claims and in the drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the objects so described may be interchanged where appropriate. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically connected, electrically connected or can be communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Compared with the prior art, the first controller controls the on/off of the primary side switching tube and simultaneously generates a first turn-off signal for controlling the synchronous rectifying tube to be reliably turned off; converting the first turn-off signal into a second turn-off signal through an isolator; and then the reliable turn-off of the synchronous rectifying tube is controlled by the second turn-off signal. The invention can solve the phenomenon of explosion caused by direct connection of the synchronous rectifying tube and the primary side switching tube in the synchronous rectifying power supply system, and has high reliability. And the MOS tube with low on resistance is used as the synchronous rectifying tube, so that the synchronous rectifying tube is always in a state with low on resistance when being conducted, the loss is low, and the efficiency of the whole power supply system can be improved.
Referring to fig. 3, a schematic diagram of an architecture of the synchronous rectification isolation driving circuit of the present invention is shown. The synchronous rectification and isolation driving circuit 30 comprises a first controller 31, a second controller 32, a signal coupler 33, a synchronous rectification controller 34 and an isolator 35.
The second controller 32 is configured to sample the output voltage and the output current, and generate a loop control signal Comp. Specifically, the second controller 32 may perform operational amplification processing on the output voltage signal Vfb obtained by sampling the output voltage and a reference voltage signal Vref to generate the loop control signal Comp; or the output current sampling signal Vcs obtained by sampling the output current (for example, the output current sampling signal Vcs may be obtained by sampling the output current through a second sampling resistor Rcs 2) and a reference voltage signal Vref are subjected to operational amplification processing, so as to generate the loop control signal Comp. The reference voltage signal Vref is an externally input reference voltage signal in this embodiment, and in other embodiments, the reference voltage signal Vref may be generated internally by the second controller 32.
The signal coupler 33 is configured to obtain the loop control signal Comp, and transmit the loop control signal Comp to the first controller 31. Specifically, the signal coupler 33 may be an optical coupler, a transmitting end of the optical coupler is electrically connected to the second controller 32, and a receiving end of the optical coupler is electrically connected to the first controller 31; the transmission of the loop control signal Comp is performed by optical coupling.
The first controller 31 is configured to generate a first driving signal vgs_q1 to control on/off of a primary switch Q1 according to the loop control signal Comp, and generate and output a first off signal driver_off1. The first controller 31 generates driving signals with different frequencies or different pulse widths according to different loop control signals Comp values so as to control the on/off of the primary side switching tube Q1, and finally ensure the output of constant voltage or constant current; and the first off signal driver_off1 is used for subsequently controlling the reliable turn-off of the synchronous rectifier Q2. That is, the first controller 31 controls the on/off of the primary switching transistor Q1, and also generates a first off signal driver_off1 for controlling the synchronous rectifying transistor Q2 to be reliably turned off.
The isolator 35 is configured to receive the first shutdown signal driver_off1, convert the first shutdown signal driver_off1 into a second shutdown signal driver_off2, and output the second shutdown signal. Since the first controller 31 is different from the ground potential of the synchronous rectification controller 34, an isolation effect is achieved by the isolator 35. The level of the second off signal driver_off2 is not equal to the level of the first off signal driver_off1. Preferably, a first difference V1 is between the first shutdown signal driver_off1 and the input side reference signal of the isolator 35, a second difference V2 is between the second shutdown signal driver_off2 and the output side reference signal of the isolator 35, and the first difference V1 and the second difference V2 are in a linear relationship. That is, v1=k·v2, where the value of the ratio k is generally around 1, such as 1.11, 0.9, and the like. The separator 35 may be made of a coil or a capacitor; an isolator made of coils, the ratio k of the first difference V1 and the second difference V2 of which is related to the number of turns of the two coils; the ratio k is related to the ratio of the supply voltages of the primary and secondary sides, made of capacitors.
The synchronous rectification controller 34 is configured to receive the second shutdown signal driver_off2 and sample a second drain-source voltage vds_q2 across a drain-source of a synchronous rectification tube Q2, so as to generate a second driving signal vgs_q2 to control on/off of the synchronous rectification tube Q2. Specifically, the synchronous rectification controller 34 is further configured to: comparing the second drain-source voltage vds_q2 at both ends of the drain-source of the synchronous rectifying tube Q2 with a second threshold voltage (on threshold voltage vth_on and off threshold voltage vth_off) in the synchronous rectifying controller, and outputting a comparison result vgs_q2_1; obtaining an inverse signal vgs_q2_2 according to the comparison result vgs_q2_1, and performing operation (such as logical OR operation) with the second turn-off signal driver_off2 to output an operation result; and generating the second driving signal vgs_q2 according to the comparison result vgs_q2_1 and the operation result to control the on/off of the synchronous rectifying tube Q2. That is, the present invention processes and compares the first shutdown signal driver_off1 generated by the first controller 31 and the second drain-source voltage vds_q2 sampled at two ends of the drain-source of the synchronous rectifying tube Q2 to generate the driving signal vgs_q2 for driving the synchronous rectifying tube Q2, so as to realize the control of reliable on/off of the synchronous rectifying tube Q2; compared with the prior art that the synchronous rectifying tube is directly controlled after the primary side grid driving signal is transmitted to the secondary side, the invention has higher reliability.
Preferably, the synchronous rectifier Q2 is a MOS transistor with an on-resistance lower than a preset resistance threshold when turned on. By adopting the MOS tube with low on-resistance (usually only a few mΩ) as the synchronous rectifying tube to replace the rectifying diode with relatively large on-state loss, the synchronous rectifying tube is always in a state with low on-resistance when being conducted, the loss is low, and the efficiency of the whole power supply system can be improved.
It should be noted that the first controller 31, the second controller 32, the synchronous rectification controller 34, and the isolator 35 according to the present invention may be composed of a circuit including logic devices. Specifically, logic devices include, but are not limited to: analog logic devices and digital logic devices. Wherein analog logic devices are devices for processing analog electrical signals, including, but not limited to: a combination of one or more logic devices such as comparators, schmitts, inverters, and gates, or gates; digital logic devices are devices for processing digital signals represented by pulsed signals, including, but not limited to: a combination of one or more logic devices such as flip-flops, gates, latches, selectors, and the like.
Referring to fig. 3 and fig. 4-fig. 7, fig. 4 is a circuit diagram of an embodiment of a synchronous rectification isolation driving circuit according to the present invention, fig. 5 is a schematic diagram of an embodiment of a second controller according to the present invention, fig. 6 is a schematic diagram of a shutdown signal generator according to the present invention, and fig. 7 is a schematic diagram of an embodiment of a synchronous rectification controller according to the present invention.
As shown in fig. 4, in the present embodiment, the second controller 32 is operative to sample the output voltage and the output current, and to perform operational amplification processing on the sampled signal and a reference voltage signal Vref, generate and output a loop control signal Comp. Specifically, the second controller 32 may be connected to a bus voltage Vbus terminal of the output voltage, so as to sample the output voltage to obtain an output voltage signal Vfb; and accessing GND at the output voltage side through a second sampling resistor Rcs2 to sample the output voltage generated by the output current flowing through the second sampling resistor Rcs2, so as to obtain an output current sampling signal Vcs. When the load of the output end is smaller (smaller than a preset value), the output voltage signal Vfb and the reference voltage signal Vref can be used for comparison operation and amplification processing to generate the loop control signal Comp, and finally, the output constant voltage is ensured; when the load of the output end is relatively large (larger than a preset value), the output current sampling signal Vcs and the reference voltage signal Vref can be used for comparison operation and amplification processing, the loop control signal Comp is generated, and finally the output constant current is ensured.
In a further embodiment, the second controller 32 includes an operational amplifier OPA1, the positive input terminal of which inputs the reference voltage signal Vref, the negative input terminal of which inputs the output voltage signal Vfb or the output current sampling signal Vcs, and the output terminal of which outputs the loop control signal Comp, as shown in fig. 5.
With continued reference to fig. 4, in this embodiment, the signal coupler 33 is an optocoupler, a transmitting end 331 of the optocoupler is electrically connected to the second controller 32, and a receiving end 332 of the optocoupler is electrically connected to the first controller 31; the transmission of the loop control signal Comp is performed by optical coupling. In a further embodiment, the loop control signal Comp output by the operational amplifier OPA1 in the second controller 32 is transmitted through the transmitting end 331 of the optical coupler. Further, a current limiting resistor Ropt is connected in series between the transmitting end 331 of the optocoupler and the output end of the operational amplifier OPA1, and the transmitting end 331 of the optocoupler is also connected in parallel with a bias resistor Rbia, as shown in fig. 5. In other embodiments, the transmitting end 331 of the optocoupler may be integrated with the second controller 32 within the same secondary control chip.
With continued reference to fig. 4, in this embodiment, the first controller 31 includes: the primary side switch Q1, a modulation signal generator 311, a driver 312 and a turn-off signal generator 313. That is, the primary side switching transistor Q1 and the modulation signal generator 311, the driver 312, and the off signal generator 313 may be integrated in the same primary control chip. In other embodiments, the receiving end 332 of the optocoupler may also be integrated within the primary control chip.
Specifically, the modulation signal generator 311 is configured to receive the loop control signal Comp, generate the first driving signal vgs_q1 according to the loop control signal Comp, and output the first driving signal vgs_q1. The driver 312 is configured to control on/off of the primary side switching tube Q1 according to the first driving signal vgs_q1. The off signal generator 313 is configured to generate and output the first off signal driver_off1 according to the first driving signal vgs_q1.
Alternatively, the modulation signal generator 311 may employ a PWM generator to generate driving signals with different pulse widths according to different values of the loop control signal Comp; or a PFM generator is used to generate drive signals of different pulse frequencies according to different values of the loop control signal Comp.
Alternatively, the turn-off signal generator 313 may employ a detection rising edge module DRE1 (as shown in part (a) of fig. 6) or a schmitt trigger ST1 (as shown in part (b) of fig. 6). The detecting rising edge module DRE1 generates the first shutdown signal driver_off1 according to the first driving signal vgs_q1, and the rising edge of the first shutdown signal driver_off1 is synchronous with the rising edge of the first driving signal vgs_q1 or advanced by a preset time before the rising edge of the first driving signal vgs_q1. The first driving signal vgs_q1 for driving the primary side switching tube Q1 is obtained after passing through a detection rising edge module DRE1, and when the rising edge or the about to occur of the first driving signal vgs_q1 occurs, a narrow pulse occurs in the first turning-off signal driver_off1; in practical applications, the rising edge of the first off signal driver_off1 is synchronous with or slightly advanced (advanced by a predetermined time) to the rising edge of the first driving signal vgs_q1.
With continued reference to fig. 4, in the present embodiment, the first controller 31 further includes an LDO (low dropout linear regulator) 314; the LDO314 is configured to supply power to the modulation signal generator 311, the driver 312, and the shutdown signal generator 313.
With continued reference to fig. 4, in this embodiment, the isolator 35 is a digital isolator ISO. Since the first controller 31 is different from the ground potential of the synchronous rectification controller 34, an isolation effect is achieved by the digital isolator ISO. The input port IN of the digital isolator ISO receives the first shutdown signal driver_off1, the input side reference port PGND thereof is connected to a reference ground, the output port OUT thereof outputs the second shutdown signal driver_off2, and the output side reference port SGND thereof is connected to a signal ground (IN this embodiment, it is connected to GND). The level of the second off signal driver_off2 is not equal to the level of the first off signal driver_off1.
With continued reference to fig. 4, in the present embodiment, the synchronous rectification controller 34 is configured to receive the second shutdown signal driver_off2 and sample a second drain-source voltage vds_q2 across a drain-source of a synchronous rectification tube Q2; comparing the second drain-source voltage vds_q2 at both ends of the drain-source of the synchronous rectifying tube Q2 with a second threshold voltage (including an on threshold voltage vth_on and an off threshold voltage vth_off) in the synchronous rectifying controller, and outputting a comparison result vgs_q2_1; obtaining an inverse signal vgs_q2_2 according to the comparison result vgs_q2_1, and performing operation (such as logical OR operation) with the second turn-off signal driver_off2 to output an operation result; and generating the second driving signal vgs_q2 according to the comparison result vgs_q2_1 and the operation result to control the on/off of the synchronous rectifying tube Q2.
In a further embodiment, the synchronous rectification controller 34 includes a hysteresis comparator HC1, an inverter INV1, an OR gate OR1, and an RS flip-flop RS1, as shown in fig. 7. Specifically, the hysteresis comparator HC1 is configured to compare the second drain-source voltage vds_q2 across the drain-source of the synchronous rectifier Q2 with the second threshold voltage (on threshold voltage vth_on and off threshold voltage vth_off) in the synchronous rectifier controller, and output a comparison result vgs_q2_1. The working logic is as shown in part A: in the process of the second drain-source voltage vds_q2 falling, when the second drain-source voltage vds_q2 is smaller than the on threshold voltage vth_on (vds_q2 < vth_on), the output comparison result vgs_q2_1 is at a high level; in the process that the second drain-source voltage vds_q2 rises, when the second drain-source voltage vds_q2 is greater than the off threshold voltage vth_off (vds_q2 > vth_off), the output comparison result vgs_q2_1 is at a low level. The inverter INV1 is configured to invert the comparison result vgs_q2_1 to obtain an inverted signal vgs_q2_2. The OR gate OR1 is configured to perform an OR operation on the inverted signal vgs_q2_2 and the second off signal driver_off2, and output an operation result Vor. The S end of the RS trigger RS1 is used for receiving the comparison result Vgs_Q2_1, the R end of the RS trigger is used for receiving the operation result Vor, and the Q end of the RS trigger is used for outputting the second driving signal Vgs_Q2 so as to control the on/off of the synchronous rectifying tube Q2; when both the S end and the R end of the RS trigger RS1 are 1, the Q end outputs 0, so that the reliable turn-off of the synchronous rectifying tube Q2 is controlled.
The invention processes and compares the first turn-off signal driver_off1 generated by the first controller 31 and the second drain-source voltage vds_q2 at two drain-source ends of the synchronous rectifying tube Q2 to generate the driving signal vgs_q2 for driving the synchronous rectifying tube Q2, thereby realizing the control of the reliable turn-on/turn-off of the synchronous rectifying tube Q2; compared with the prior art that the synchronous rectifying tube is directly controlled after the primary side grid driving signal is transmitted to the secondary side, the invention has higher reliability.
Preferably, the synchronous rectifier Q2 is a MOS transistor with an on-resistance lower than a preset resistance threshold when turned on. By adopting the MOS tube with low on-resistance (usually only a few mΩ) as the synchronous rectifying tube to replace the rectifying diode with relatively large on-state loss, the synchronous rectifying tube is always in a state with low on-resistance when being conducted, the loss is low, and the efficiency of the whole power supply system can be improved.
Based on the same inventive concept, the invention also provides a synchronous rectification isolation power supply system which comprises a drive control circuit, wherein the drive control circuit adopts the synchronous rectification isolation drive circuit. The synchronous rectification and isolation power supply system of the present invention is further described below with reference to the accompanying drawings.
Referring to fig. 8-9A-9B, fig. 8 is a schematic diagram of the synchronous rectification and isolation power supply system according to the present invention, fig. 9A is a main waveform diagram of a first embodiment of the system shown in fig. 8 operating in a continuous mode, and fig. 9B is a main waveform diagram of a second embodiment of the system shown in fig. 8 operating in a continuous mode.
As shown in fig. 8, the synchronous rectification and isolation power supply system of the present invention adopts Flyback isolation topology (Flyback), and the main devices include: the rectifier bridge stack (which includes rectifier diodes D1, D2, D3, D4), an input capacitor Cin, a main transformer T1, a drive control circuit 82, an output filter capacitor Cout, and a dummy load R0. The alternating current power supply AC is connected to a primary winding T11 of the main transformer T1 after being rectified and filtered by the rectifier bridge stack and the input capacitor Cin; the secondary winding T12 of the main transformer T1 generates a bus voltage Vbus through the output filter capacitor Cout and the dummy load R0. The drive control circuit 82 is electrically connected between the primary winding T11 of the main transformer T1 and the secondary winding T12 of the main transformer T1, and receives the bus voltage Vbus.
The driving control circuit 82 is configured to control the synchronous rectification and isolation power supply system, and the driving control circuit 82 adopts the synchronous rectification and isolation driving circuit 30 according to the present invention. Specifically, the first controller 31 of the driving control circuit 82 is electrically connected to the primary winding T11 of the main transformer T1; the second controller 32 of the drive control circuit 82 is electrically connected to the first controller 31 through the signal coupler 33, and receives the bus voltage Vbus; the synchronous rectification controller 34 of the drive control circuit 82 is electrically connected to the secondary winding T12 of the main transformer T1.
The primary side switching tube Q1 in the first controller 31 is an NMOS tube, a source terminal thereof receives an input voltage sampling signal obtained by sampling an input current by a first sampling resistor Rcs1, a gate terminal thereof is electrically connected to the driver 312 in the first controller 31, and a Drain terminal thereof is electrically connected to the primary side winding T11 of the main transformer T1 through a Drain port to receive a high voltage start signal. Correspondingly, the LDO314 of the first controller 31 receives the high voltage start signal through a Drain port, and supplies power to the modulation signal generator 311, the driver 312 and the shutdown signal generator 313 in the first controller 31 after performing low voltage differential linear conversion.
The second controller 32 is connected to the bus voltage Vbus end of the output voltage to sample the output voltage to obtain an output voltage signal Vfb; and accessing GND at the output voltage side through a second sampling resistor Rcs2 to sample the output voltage generated by the output current flowing through the second sampling resistor Rcs2, so as to obtain an output current sampling signal Vcs.
The VDD port of the synchronous rectification controller 34 is connected to GND through a capacitor Cr2, the VS port is connected to GND, the VD port is connected to the secondary winding T12 of the main transformer T1, and the EN port is connected to the output port OUT of the isolator 35 in the driving control circuit 82.
Because the driving control circuit 82 adopts the synchronous rectification and isolation driving circuit 30 of the present invention, the structure and the beneficial effects of the synchronous rectification and isolation driving circuit 30 are described in detail before, and are not repeated here.
The synchronous rectification isolation power supply system also comprises an absorption circuit which is composed of a capacitor Cr1, a diode Dr1 and a resistor R1. The capacitor Cr1 is connected with the diode Dr1 in series and then connected between two taps of the primary winding T11 of the main transformer T1 in parallel; the resistor R1 is connected in parallel with two ends of the capacitor Cr 1.
The main waveform diagrams of the synchronous rectification isolated power supply system working in the continuous mode (CCM) are shown in fig. 9A-9B, wherein ipri is primary side current of a main transformer, and isec is secondary side current of the main transformer. The waveform diagram shown in fig. 9A is an operation waveform diagram of the turn-off signal generator 313 in the first controller 31 using a detection rising edge module; the waveform diagram shown in fig. 9B is an operation waveform diagram of the shutdown signal generator 313 in the first controller 31 using a schmitt trigger. As can be seen from fig. 9A to 9B, at the moment when the primary side switching tube Q1 is turned on, the primary side current of the main transformer starts to increase from 0, and the secondary side current of the main transformer starts to decrease, and during this period, the second drain-source voltage vds_q2 across the drain-source of the synchronous rectifying tube Q2 is always at a low level, so as to prevent the primary side switching tube Q1 and the synchronous rectifying tube Q2 from being turned on simultaneously.
The synchronous rectification isolation power supply system can be applied to an intermittent mode, a critical continuous mode and a continuous mode, and has wide application range; the first controller is used for controlling the on/off of the primary side switching tube and generating a first turn-off signal for controlling the synchronous rectifying tube to be reliably turned off, processing and comparing the first turn-off signal with drain-source voltages obtained by sampling the drain-source ends of the synchronous rectifying tube to generate a driving signal for driving the synchronous rectifying tube, so that the reliable turn-off of the synchronous rectifying tube can be controlled, and the phenomenon of power system frying caused by the simultaneous conduction of the primary side switching tube and the synchronous rectifying tube is prevented, and the reliability is high; the flyback circuit CCM can normally work in a flyback circuit CCM mode, and the synchronous rectifying tube is always in a low on-resistance state when being conducted, compared with the pre-turn-off function which is adopted in the market and used for automatically reducing the driving voltage of the synchronous rectifying tube and increasing the on-resistance of the synchronous rectifying tube when the current flowing through the synchronous rectifying tube is smaller than a set value, the flyback circuit CCM has low loss and can improve the efficiency of the whole power supply system.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (11)
1. A synchronous rectification isolated drive circuit, comprising:
the second controller is used for sampling the output voltage and the output current and further generating a loop control signal;
the signal coupler is used for acquiring the loop control signal and transmitting the loop control signal to the first controller;
the first controller is used for generating a first driving signal to control the on/off of a primary side switching tube according to the loop control signal, and generating a first off signal and outputting the first off signal;
the isolator is used for receiving the first turn-off signal, converting the first turn-off signal into a second turn-off signal and outputting the second turn-off signal; and
a synchronous rectification controller, configured to receive the second turn-off signal and sample a second drain-source voltage at two ends of a drain-source of a synchronous rectification tube, so as to generate a second driving signal to control on/off of the synchronous rectification tube; the synchronous rectification controller is further configured to:
comparing the second drain-source voltage at two ends of the drain-source of the synchronous rectifying tube with the second threshold voltage in the synchronous rectifying controller, and outputting a comparison result;
acquiring an inversion signal according to the comparison result, and performing operation with the second turn-off signal to output an operation result; and generating the second driving signal according to the comparison result and the operation result so as to control the on/off of the synchronous rectifying tube.
2. The circuit of claim 1 wherein the second controller further performs an operational amplification process on the output voltage signal obtained from the sampled output voltage and a reference voltage signal to generate the loop control signal; or further carrying out operational amplification processing on an output current sampling signal obtained by sampling the output current and a reference voltage signal to generate the loop control signal.
3. The circuit of claim 1, wherein the signal coupler employs an optocoupler, a transmitting end of the optocoupler is electrically connected to the second controller, and a receiving end of the optocoupler is electrically connected to the first controller.
4. The circuit of claim 1, wherein the first controller comprises the primary side switching tube, the first controller further comprising:
a modulation signal generator for receiving the loop control signal, generating the first driving signal according to the loop control signal and outputting the first driving signal;
the driver is used for controlling the on/off of the primary side switching tube according to the first driving signal; and
and the turn-off signal generator is used for generating and outputting the first turn-off signal according to the first driving signal.
5. The circuit of claim 4, wherein the modulation signal generator is a PWM generator or a PFM generator.
6. The circuit of claim 4, wherein the turn-off signal generator employs a detect rising edge module or a schmitt trigger; the detection rising edge module generates the first turn-off signal according to the first driving signal, and the rising edge of the first turn-off signal is synchronous with the rising edge of the first driving signal or advanced by a preset time.
7. The circuit of claim 4, wherein the first controller further comprises an LDO; the LDO is used for supplying power to the modulation signal generator, the driver and the turn-off signal generator.
8. The circuit of claim 1, wherein the first shut-off signal has a first difference between the first shut-off signal and the input side reference signal of the isolator and the second shut-off signal has a second difference between the second shut-off signal and the output side reference signal of the isolator, the first difference and the second difference being in a linear relationship.
9. The circuit of claim 1, wherein the synchronous rectification controller comprises:
a hysteresis comparator for comparing the second drain-source voltage at both ends of the drain-source of the synchronous rectifying tube with the second threshold voltage in the synchronous rectifying controller, and outputting a comparison result;
the inverter is used for inverting the comparison result to obtain an inverted signal;
an OR gate for OR-operating the inverted signal and the second turn-off signal to output an operation result; and an RS trigger, wherein the S end is used for receiving the comparison result, the R end is used for receiving the operation result, and the Q end is used for outputting the second driving signal so as to control the on/off of the synchronous rectifying tube.
10. The circuit of claim 1, wherein the synchronous rectifier tube is a MOS tube having an on-resistance lower than a predetermined resistance threshold when turned on.
11. A synchronous rectification isolated power supply system, comprising a drive control circuit employing a synchronous rectification isolated drive circuit as claimed in any one of claims 1 to 10.
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| CN113162390B (en) * | 2020-12-17 | 2022-05-10 | 上海晶丰明源半导体股份有限公司 | Control circuit of isolated power supply, isolated power supply and control method thereof |
| CN115912877A (en) * | 2023-01-18 | 2023-04-04 | 维沃移动通信有限公司 | Power supply circuit, power supply control method and electronic equipment |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203491883U (en) * | 2013-10-12 | 2014-03-19 | 成都芯源系统有限公司 | Isolated switch converter and controller thereof |
| CN203691245U (en) * | 2013-12-31 | 2014-07-02 | 西安理工大学 | Synchronous rectifier controller used for flyback converter |
| CN107508468A (en) * | 2016-08-29 | 2017-12-22 | 杰华特微电子（杭州）有限公司 | The control circuit and method and isolation type switching power supply of isolation type switching power supply |
| CN109039093A (en) * | 2018-09-29 | 2018-12-18 | 杰华特微电子（杭州）有限公司 | Isolation type switching power supply and its control method |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7787264B2 (en) * | 2007-07-25 | 2010-08-31 | System General Corp. | Apparatus to provide synchronous rectifying circuit for flyback power converters |
| CN102969912B (en) * | 2012-10-23 | 2014-08-13 | 矽力杰半导体技术(杭州)有限公司 | Control and drive circuit and method |
| CN103490605B (en) * | 2013-10-12 | 2015-12-23 | 成都芯源系统有限公司 | Isolated switch converter and controller and control method thereof |
| JP6563651B2 (en) * | 2014-12-24 | 2019-08-21 | ローム株式会社 | Insulation synchronous rectification type DC / DC converter, synchronous rectification controller, power supply device using the same, power supply adapter, and electronic device |
-
2020
- 2020-06-05 CN CN202010504773.9A patent/CN111541361B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203491883U (en) * | 2013-10-12 | 2014-03-19 | 成都芯源系统有限公司 | Isolated switch converter and controller thereof |
| CN203691245U (en) * | 2013-12-31 | 2014-07-02 | 西安理工大学 | Synchronous rectifier controller used for flyback converter |
| CN107508468A (en) * | 2016-08-29 | 2017-12-22 | 杰华特微电子（杭州）有限公司 | The control circuit and method and isolation type switching power supply of isolation type switching power supply |
| CN109039093A (en) * | 2018-09-29 | 2018-12-18 | 杰华特微电子（杭州）有限公司 | Isolation type switching power supply and its control method |
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