CN114825954A - Dynamic threshold adjusting system and method for isolated power supply drive - Google Patents

Dynamic threshold adjusting system and method for isolated power supply drive Download PDF

Info

Publication number
CN114825954A
CN114825954A CN202210349490.0A CN202210349490A CN114825954A CN 114825954 A CN114825954 A CN 114825954A CN 202210349490 A CN202210349490 A CN 202210349490A CN 114825954 A CN114825954 A CN 114825954A
Authority
CN
China
Prior art keywords
time length
voltage
threshold voltage
ratio
working period
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210349490.0A
Other languages
Chinese (zh)
Inventor
关晶晶
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Southchip Semiconductor Technology Co Ltd
Original Assignee
Shanghai Southchip Semiconductor Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Southchip Semiconductor Technology Co Ltd filed Critical Shanghai Southchip Semiconductor Technology Co Ltd
Priority to CN202210349490.0A priority Critical patent/CN114825954A/en
Publication of CN114825954A publication Critical patent/CN114825954A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/081—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters wherein the phase of the control voltage is adjustable with reference to the AC source
    • H02M1/082—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters wherein the phase of the control voltage is adjustable with reference to the AC source with digital control
    • 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
    • H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33515—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 with automatic control of the output voltage or current, e.g. flyback converters with digital control

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Power Conversion In General (AREA)

Abstract

The invention discloses a dynamic threshold value adjusting system and method for isolating power supply drive, which relates to the technical field of switch power supplies, and the system comprises: a voltage regulating module; the voltage regulating module is used for: and adjusting the threshold voltage in the current working period according to the detected time length for completely opening the grid driving voltage of the power tube in the current working period and the time length for adjusting the grid driving voltage, and outputting a driving signal in the next working period to a driving circuit according to the source-drain voltage difference and the adjusted threshold voltage so as to adjust the grid driving voltage of the power tube in the next working period. The invention can realize the accurate turn-off when the inductive current passes through zero in different synchronous rectifier tube application scenes, and simultaneously reduces the conduction loss of the power tube and improves the efficiency.

Description

Dynamic threshold adjusting system and method for isolated power supply drive
Technical Field
The invention relates to the technical field of switching power supplies, in particular to a dynamic threshold value adjusting system and method for isolating power supply drive.
Background
For the switching power supply topology structure, taking secondary side control as an example, in order to reduce loss, it is often necessary to turn off the synchronous power tube when the secondary side inductive current is reduced to zero. However, the synchronous power tube is not an ideal action when being turned off, the slower the turn-off action is, the larger the loss is, and under the condition that the secondary side synchronous power tube is not completely turned off, the primary side synchronous power tube is already turned on, so that a chip is damaged.
Taking the flyback switching power supply shown in fig. 1 as an example, which takes a low-side synchronous rectification circuit as an example, the system is composed of a transformer 101, a primary inductor 102, a secondary inductor 103, a primary synchronous power tube M1, a secondary synchronous power tube M2, a primary control unit 104, a secondary control unit 105, and the like. When the primary side synchronous power tube M1 is conducted, the secondary side synchronous power tube M2 is turned off, and energy is input from the input end Vin and is stored in the transformer. The primary side synchronous power tube M1 is turned off, the secondary side synchronous power tube M2 starts to be conducted, and the energy stored in the transformer is input to a load through the synchronous rectifier tube, so that the conversion and the transmission of the energy are completed. The primary side synchronous power tube M1 and the secondary side synchronous power tube M2 are conducted simultaneously, and the chip is burnt, so that the condition is avoided. The power tube has switching loss in the switching action process, and the loss is influenced by the speed of the switching action and the grid voltage current of the power tube during switching. The faster the switching action, the smaller the gate voltage and the current, and the smaller the switching loss of the power tube.
Fig. 2 shows a waveform diagram corresponding to the operation of the secondary control unit 105 in fig. 1. Referring to fig. 2, the secondary control unit 105 determines the turn-on and turn-off of the secondary synchronization power transistor M2 by detecting the drain-source voltage Vds of the secondary synchronization power transistor M2. When Vds is higher than a threshold voltage Vth1, a secondary side synchronous power tube M2 is conducted, and secondary side freewheeling is achieved; when Vds is lower than Vth2, the secondary side synchronous power tube M2 is turned off. In the process of conducting the secondary side synchronous power tube M2, the drain-source voltage Vds of the secondary side synchronous power tube M2 gradually decreases with the decrease of the secondary side inductor current Isec, and when the Vds decreases to the threshold voltage Vreg, the secondary side control circuit starts to adjust the gate drive voltage Vg of the synchronous rectifier tube. As the secondary inductor current Isec decreases, the gate driving voltage Vg of the secondary synchronous power transistor M2 gradually decreases, and the drain-source voltage Vds of the secondary synchronous power transistor M2 is maintained at Vreg. When the secondary side inductor current Isec is close to zero, Vds cannot be maintained at Vreg, and the gate driving voltage Vg of the secondary side synchronous power tube M2 is rapidly reduced to 0 when the secondary side inductor current Isec touches the turn-off threshold Vth2 of the secondary side synchronous power tube M2, so that the secondary side synchronous power tube M2 is turned off. EN _ on in fig. 2 represents a driving signal (digital control quantity) output by the on/off detection module in the secondary control unit 105, and at the moment when the secondary synchronous power tube M2 is turned on or off, EN _ on is used as an input of the driving circuit in the secondary control unit 105 to enable the driving circuit to generate the gate driving voltage Vg, EN _ reg in fig. 2 is a driving signal (digital control quantity) generated after comparing Vds with the threshold voltage Vreg in the process that the secondary synchronous power tube M2 is turned on, and EN _ reg is used as an input of the driving circuit in the secondary control unit 105 in the process that the secondary synchronous power tube M2 is turned on to adjust the gate driving voltage Vg generated by the driving circuit.
As can be seen from the above description, the conventional control method sets a fixed driving regulation threshold voltage Vreg, and when the on-resistance Rdson of the secondary side synchronous power transistor M2 changes, Vreg remains fixed. This results in that in small Rdson applications, as shown in the graph of fig. 2, even if the inductor current Isec decreases to a low value, the drain-source voltage Vds of the secondary side synchronous power transistor M2 still cannot touch the driving adjustment threshold voltage Vreg, the gate voltage is high when the power transistor is turned off, and the turn-off operation speed is slow. In the large Rdson application, as shown in the graph of fig. 2, after the drain-source voltage Vds of the secondary side synchronous power transistor M2 touches the driving adjustment threshold voltage Vreg, the driving voltage of the power transistor is excessively adjusted, so that there may be a problem of insufficient driving capability. Therefore, the operating point of the conventional control architecture for starting to adjust the driving voltage of the synchronous rectifier is relatively fixed, and the operating point of the synchronous rectifier for starting to adjust the driving voltage cannot be dynamically changed according to different application scenes, so that the use scenes of the circuit are limited, and the advantages of the method for adjusting the driving voltage are also limited.
Disclosure of Invention
Based on this, embodiments of the present invention provide a dynamic threshold adjustment system and method for isolated power supply driving, so as to implement accurate turn-off when the inductor current flows through zero in different synchronous rectifier tube application scenarios, reduce the conduction loss of the power tube, and improve the efficiency.
In order to achieve the purpose, the invention provides the following scheme:
a dynamic threshold adjustment system for an isolated power supply drive, comprising: a voltage regulating module; the voltage regulating module is used for being connected with a source-drain pressure difference detection module, a conduction-disconnection detection module and a driving circuit in a primary side control unit or a secondary side control unit of the isolation power supply; the source-drain pressure difference detection module is used for detecting the source-drain pressure difference of the power tube at the primary side control side or the secondary side control side of the isolation power supply;
the voltage regulating module is used for:
detecting the time length of the complete opening of the grid driving voltage of the power tube and the time length of the adjustment of the grid driving voltage in the current working period;
adjusting the threshold voltage under the current working period according to the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage to obtain the adjusted threshold voltage;
when the power tube is conducted in the current working period, acquiring the source-drain pressure difference and the adjusted threshold voltage, comparing the source-drain pressure difference with the adjusted threshold voltage, and outputting a driving signal of the next working period to the driving circuit; the driving circuit is used for adjusting the grid driving voltage of the power tube in the next working period according to the driving signal in the next working period.
Optionally, the voltage regulating module specifically includes:
the time length detection submodule is used for obtaining the time length of the complete opening of the grid driving voltage of the power tube and the time length of the adjustment of the grid driving voltage in the current working period according to the grid driving voltage of the power tube in the current working period, and determining the sum of the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage as the grid driving voltage conducting time length of the power tube in the current working period;
the correction submodule is used for adjusting the threshold voltage under the current working cycle according to the first ratio, the second ratio or the third ratio to obtain the adjusted threshold voltage; the first ratio is the ratio of the time length of the adjustment of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the ratio of the time length of the complete opening of the grid driving voltage to the conduction time length of the grid driving voltage; the third ratio is the ratio of the time length of the complete opening of the grid driving voltage to the time length of the adjustment of the grid driving voltage;
and the comparison submodule is used for acquiring the source-drain voltage difference and the adjusted threshold voltage when the power tube is conducted in the current working period, and outputting a driving signal of the next working period to the driving circuit when the source-drain voltage difference reaches the adjusted threshold voltage so as to adjust the grid driving voltage of the power tube in the next working period.
Optionally, the modification submodule specifically includes:
the first correction unit is used for reducing the threshold voltage under the current working cycle to obtain the adjusted threshold voltage when the first ratio is smaller than a first set value and lasts for a first set time length; when the first ratio is larger than a second set value and lasts for a second set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage; when the first ratio is greater than or equal to a first set value and less than or equal to a second set value, maintaining the threshold voltage under the current working period; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
Optionally, the modification submodule specifically includes:
the second correction unit is used for increasing the threshold voltage under the current working cycle to obtain the adjusted threshold voltage when the second ratio is smaller than the first set value and lasts for a first set time; when the second ratio is greater than a second set value and lasts for a second set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage; when the second ratio is greater than or equal to the first set value and less than or equal to the second set value, maintaining the threshold voltage under the current working cycle; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
Optionally, the modification submodule specifically includes:
the third correction unit is used for increasing the threshold voltage under the current working cycle to obtain the adjusted threshold voltage when the third ratio is smaller than the first set value and lasts for the first set time; when the third ratio is greater than a second set value and lasts for a second set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage; when the third ratio is greater than or equal to the first set value and less than or equal to the second set value, maintaining the threshold voltage under the current working cycle; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
Optionally, the first correcting unit specifically includes:
the circuit comprises a first branch circuit, a second branch circuit, a third branch circuit, a fourth branch circuit, a first inverter, a second inverter, a third inverter, a first comparator, a second comparator, a latch timer, an addition-subtraction counter and a digital-to-analog converter;
the first branch circuit comprises a first current source, a first transmission gate, a second transmission gate and a second current source which are sequentially connected from a power supply voltage end to a grounding end; two ends of the first transmission gate are connected with the first inverter in parallel; two ends of the second transmission gate are connected with the second inverter in parallel; the connection point of the first transmission gate and the second transmission gate is a first common end; a third branch is connected between the first common end and the grounding end; the third branch comprises a first capacitor and a first switch which are connected in parallel;
the second branch circuit comprises a third current source, a third transmission gate, a fourth transmission gate and a fourth current source which are sequentially connected from a power supply voltage end to a grounding end; a connection point of the third transmission gate and the fourth transmission gate is a second common end; a fourth branch is connected between the second common end and the grounding end; the fourth branch comprises a second capacitor and a second switch which are connected in parallel;
the input end of the first comparator is connected with the first public end; the output end of the first comparator is connected with the latch timer through the third inverter;
the input end of the second comparator is connected with the second common end; the output end of the second comparator is connected with the latch timer;
the latch timer is connected with the digital-to-analog converter through the addition and subtraction counter;
the first transmission gate is used for being connected with the output end of the duration detection submodule; the second transmission gate is used for being connected with the output end of the comparison submodule; the digital-to-analog converter is used for being connected with the input end of the output end of the comparison submodule so as to provide the adjusted threshold voltage for the comparison submodule.
Optionally, the value range of the first set value is (0, 1); the value range of the second set value is (0, 1).
The invention also provides a dynamic threshold value adjusting method for isolating power supply drive, which is used for the dynamic threshold value adjusting system, and the method comprises the following steps:
detecting the time length for completely switching on the grid driving voltage of a power tube in an isolation power supply and the time length for adjusting the grid driving voltage in the current working period;
adjusting the threshold voltage under the current working period according to the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage to obtain the adjusted threshold voltage;
when the power tube is conducted in the current working period, acquiring a source-drain pressure difference and the adjusted threshold voltage, comparing the source-drain pressure difference with the adjusted threshold voltage, and outputting a driving signal of the next working period to a driving circuit; the drive circuit is used for adjusting the grid drive voltage of the power tube in the next working period according to the drive signal in the next working period; and the source-drain pressure difference is detected by the source-drain pressure difference detection module and is the source-drain pressure difference of the power tube at the primary side control side or the secondary side control side of the isolation power supply.
Optionally, the adjusting the threshold voltage in the current working cycle according to the time length of the complete turn-on of the gate driving voltage and the time length of the adjustment of the gate driving voltage to obtain the adjusted threshold voltage specifically includes:
determining the sum of the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage as the grid driving voltage opening time length of the power tube under the current working period;
adjusting the threshold voltage under the current working cycle according to the first ratio, the second ratio or the third ratio to obtain the adjusted threshold voltage; the first ratio is the ratio of the time length of the adjustment of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the ratio of the time length of the complete opening of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the time length for which the gate driving voltage is completely turned on and the time length for which the gate driving voltage is adjusted.
Optionally, the adjusting the threshold voltage in the current working cycle according to the first ratio, the second ratio, or the third ratio to obtain the adjusted threshold voltage specifically includes:
when the first ratio is smaller than a first set value and lasts for a first set time, reducing the threshold voltage under the current working period to obtain an adjusted threshold voltage;
when the first ratio is larger than a second set value and lasts for a second set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage;
when the first ratio is greater than or equal to a first set value and less than or equal to a second set value, maintaining the threshold voltage under the current working period; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
Compared with the prior art, the invention has the beneficial effects that:
the embodiment of the invention provides a dynamic threshold value adjusting system and method for isolating power supply drive, wherein the system comprises: a voltage regulating module; the voltage regulating module regulates the threshold voltage of the power tube in the current working period according to the detected time length for the complete opening of the grid driving voltage of the power tube in the current working period and the time length for the regulation of the grid driving voltage, and regulates the grid driving voltage of the power tube in the next working period according to the source-drain voltage difference and the regulated threshold voltage. In different application scenes, the time length for completely switching on the grid driving voltage is different from the time length for adjusting the grid driving voltage, so that the working point (threshold voltage) of the synchronous rectifier tube for starting to adjust the driving voltage can be dynamically changed in different application scenes, the grid driving voltage of the synchronous rectifier tube is ensured to be reduced when the primary side or secondary side inductive current is reduced to a relatively small value, and the aims of quickly switching off the synchronous rectifier tube and reducing the switching loss when the synchronous rectifier tube is switched off can be fulfilled when the inductive current is reduced to a zero value. Therefore, the invention can realize the accurate turn-off when the inductive current passes through zero in different synchronous rectifier tube application scenes, and simultaneously reduces the conduction loss of the power tube and improves the efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a flyback switching power supply;
fig. 2 is a waveform diagram corresponding to the operation of a secondary side control unit in the flyback switching power supply;
FIG. 3 is a block diagram of a dynamic threshold adjustment system for isolated power drivers according to an embodiment of the present invention;
FIG. 4 is a more detailed control block diagram of a dynamic threshold adjustment system for isolated power drivers according to an embodiment of the present invention;
fig. 5 is a schematic circuit diagram of a first modification unit in the voltage regulation module according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a first operating waveform of a dynamic threshold adjustment method for secondary side driving of an isolated power supply according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a second operating waveform of the dynamic threshold adjustment method for secondary side driving of the isolated power supply according to the embodiment of the present invention;
fig. 8 is a flowchart of a dynamic threshold adjustment method for an isolated power driver according to an embodiment of the present invention.
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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
In order to solve the problem that the working point of the conventional control architecture for starting to adjust the driving voltage of the synchronous rectifier tube is relatively fixed and cannot be dynamically changed according to different application scenes, several solutions are provided at present:
in fig. 2, Ta represents the time length during which the gate driving voltage is completely turned on in a period, Treg represents the time length during which the gate driving voltage is adjusted in a period, and the time during which the power transistor is turned on in a period is T, and T is Ta + Treg.
The first scheme is as follows: in the period, when the drain-source voltage difference Vds of the secondary side synchronous power tube M2 still does not contact the driving adjustment threshold voltage Vreg within the Ta time limit, Vreg is reduced. The adjusting method can only reduce Vreg (namely, the adjusting method is only suitable for small Rdson application), and the real-time adjusting mode has the condition of misjudgment caused by circuit interference.
Scheme II: within a certain time after the power tube is conducted or a period of time before the power tube is closed, if the drain-source voltage difference Vds of the secondary side synchronous power tube M2 does not touch the driving adjustment threshold voltage Vreg, Vreg is reduced. Likewise, this adjustment method can only reduce Vreg (i.e. only for small Rdson applications).
The third scheme is as follows: the duration Treg of the adjustment of the grid driving voltage of the power tube in each period is fixed by setting the dynamically adjusted Vreg. Setting the Treg to a certain value, and as long as the switching-on time T of the power tube is slightly changed, the Vreg must be changed to meet the requirement that the Treg is always constant. To avoid the circuit being in a repetitive adjustment state, a Vreg adjustment circuit with high precision needs to be designed, which increases the area and complexity of the circuit.
Scheme one and scheme two in the application of little Rdson, can adjust drive regulation threshold voltage Vreg in real time. However, in the large Rdson application, in order to prevent the gate driving voltage from being too low, it can only be realized by fixing the duration Treg of the gate driving voltage adjustment. In the third scheme, a fixed grid drive voltage adjusting time length Treg is set, the circuit is easily excessively adjusted, and the circuit design is complex, so that the current solution can properly change the working point of the synchronous rectifier tube for adjusting the drive voltage, but the accurate turn-off of the inductive current when the inductive current passes through zero can not be realized in different application scenes of the synchronous rectifier tube, the conduction loss of the power tube needs to be reduced, and the efficiency needs to be improved.
In order to solve the above problem, the present embodiment provides a dynamic threshold adjustment system for isolated power supply driving, referring to fig. 3, the system includes: a voltage regulating module; the voltage regulating module is used for being connected with a source-drain pressure difference detection module, a conduction-disconnection detection module and a driving circuit in a primary side control unit or a secondary side control unit of the isolation power supply; the source-drain differential pressure detection module is used for detecting a source-drain differential pressure Vsd of a power tube at the primary side control side or the secondary side control side of the isolation power supply; the on-off detection module is respectively connected with the source-drain pressure difference detection module and the drive circuit, and is used for controlling the on-off of the power tube through the source-drain pressure difference Vsd and outputting a drive signal (digital control quantity) to the drive circuit at the on-off moment; the voltage regulating module is used for controlling the dynamic regulation of the threshold voltage and outputting a driving signal (digital control quantity) in the conduction process of the power tube; the driving circuit is used for generating a gate driving voltage Vg for driving the power tube according to the driving signal.
Specifically, the voltage regulating module is used for:
detecting the time length of the complete opening of the grid driving voltage of the power tube and the time length of the adjustment of the grid driving voltage in the current working period;
adjusting the threshold voltage under the current working period according to the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage to obtain the adjusted threshold voltage;
when the power tube is conducted in the current working period, acquiring the source-drain pressure difference and the adjusted threshold voltage, comparing the source-drain pressure difference with the adjusted threshold voltage, and outputting a driving signal of the next working period to the driving circuit; the driving circuit is used for adjusting the grid driving voltage of the power tube in the next working period according to the driving signal in the next working period.
The voltage regulation module is further explained by taking a low-side synchronous rectification circuit (secondary side control) as an example, but in the application, the core idea of the high-side synchronous rectification circuit (primary side control) is also applicable, namely, the voltage drop (source-drain voltage difference) on the power tube is detected, then the conduction and the disconnection of the power tube are judged, the facility regulates the threshold value, and the threshold voltage is dynamically regulated.
In one example, the voltage regulation module specifically includes:
and the time length detection submodule is used for obtaining the time length of the complete opening of the grid driving voltage of the power tube and the time length of the adjustment of the grid driving voltage in the current working period according to the grid driving voltage of the power tube in the current working period, and determining the sum of the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage as the grid driving voltage conduction time length of the power tube in the current working period.
The correction submodule is used for adjusting the threshold voltage under the current working cycle according to the first ratio, the second ratio or the third ratio to obtain the adjusted threshold voltage; the first ratio is the ratio of the time length Treg of the grid driving voltage adjustment to the grid driving voltage conduction time length T; the second ratio is the ratio of the time length Ta of the complete opening of the grid driving voltage to the conduction time length T of the grid driving voltage; the third ratio is a ratio of a time length Ta of the gate driving voltage being completely turned on to a time length Treg of the gate driving voltage being adjusted.
And the comparison submodule is used for acquiring the source-drain voltage difference and the adjusted threshold voltage when the power tube is conducted in the current working period, and outputting a driving signal of the next working period to the driving circuit when the source-drain voltage difference reaches the adjusted threshold voltage so as to adjust the grid driving voltage of the power tube in the next working period.
In one example, the modification submodule specifically includes:
the first correction unit is used for reducing the threshold voltage Vreg under the current working cycle to obtain the regulated threshold voltage when the first ratio Treg/T is smaller than a first set value m and lasts for a first set time length; when the first ratio Treg/T is larger than a second set value n and lasts for a second set time, increasing the threshold voltage Vreg under the current working period to obtain an adjusted threshold voltage; when the first ratio Treg/T is larger than or equal to a first set value m and smaller than or equal to a second set value n, keeping a threshold voltage Vreg under the current working cycle; the first set time length and the second set time length are set time periods td and set number of work cycles or 0. Wherein, the value range of the first set value m is (0, 1); the value range of the second set value n is (0, 1), that is, (0< m < n < 1). The specific implementation modes include the following three types:
and automatically correcting the driving regulation threshold voltage Vreg according to the size of the first ratio Treg/T. When Treg/T < m (0< m <1) continues for a first set time period td1, decreasing the value of Vreg; when Treg/T > n (0< n <1) continues for the second set period td2, the value of Vreg is increased. If m is less than or equal to Treg/T is less than or equal to n, then Vreg is not adjusted.
And automatically correcting and driving the adjusting threshold voltage Vreg according to the size of Treg/T. When Treg/T < m (0< m <1) and a set number of work cycles are continued, the value of Vreg is reduced; when Treg/T > n (0< n <1) continues for a set number of duty cycles, the value of Vreg is increased. And if m is less than or equal to Treg/T is less than or equal to n, regulating Vreg.
And automatically correcting and driving the adjusting threshold voltage Vreg according to the size of Treg/T. When Treg/T < m (0< m <1), immediately decrease the value of Vreg; when Treg/T > n (0< n <1), the value of Vreg is immediately increased. If m is less than or equal to Treg/T is less than or equal to n, then Vreg is not adjusted.
In the embodiment, the turn-on duration T of the grid driving voltage of the power tube and the adjustment duration Treg of the grid driving voltage in the Vreg corresponding period are detected. The threshold voltage Vreg of the drive adjustment is automatically corrected through the processing of a circuit algorithm, and Treg/T is restricted within a preset range. The voltage regulating threshold of the voltage regulating module is automatically set according to different power tubes, and the method can be used for different application scenes. Compared with the traditional control mode, the control mode is flexible in application.
In an example, the modification submodule specifically includes:
the second correction unit is used for increasing the threshold voltage Vreg under the current working cycle to obtain the adjusted threshold voltage when the second ratio Ta/T is smaller than a first set value m and lasts for a first set time length; when the second ratio Ta/T is larger than a second set value n and lasts for a second set time length, reducing the threshold voltage Vreg under the current working period to obtain an adjusted threshold voltage; when the second ratio Ta/T is larger than or equal to a first set value m and smaller than or equal to a second set value n, keeping a threshold voltage Vreg under the current working cycle; the first set time length and the second set time length are set time periods td and set number of work cycles or 0. Wherein, the value range of the first set value m is (0, 1); the value range of the second set value n is (0, 1). The specific implementation modes include the following three types:
and automatically correcting the driving adjustment threshold voltage Vreg according to the size of Ta/T. When Ta/T < m (0< m <1) continues for a first set time period td1, increasing the value of Vreg; when Ta/T > n (0< n <1) continues for the second set period td2, the value of Vreg is decreased. If m is less than or equal to Ta/T is less than or equal to n, then Vreg is not adjusted.
And automatically correcting the driving adjustment threshold voltage Vreg according to the size of Ta/T. Increasing the value of Vreg when Ta/T < m (0< m <1) and a set number of duty cycles are continued; if Ta/T > n (0< n <1) continues for a set number of duty cycles, the value of Vreg is decreased. If m is less than or equal to Ta/T is less than or equal to n, then Vreg is not adjusted.
And automatically correcting the driving adjustment threshold voltage Vreg according to the size of Ta/T. When Ta/T < m (0< m <1), the value of Vreg is increased immediately; when Ta/T > n (0< n <1), the value of Vreg is immediately decreased. And if m is less than or equal to Ta/T is less than or equal to n, regulating Vreg.
In the example, the turn-on duration T of the gate driving voltage of the power tube and the duration Ta of the complete turn-on of the gate driving voltage in the Vreg corresponding period are detected. Through the processing of a circuit algorithm, the driving adjustment threshold voltage Vreg is automatically corrected, and Ta/T is restricted within a preset range. The voltage regulating threshold of the voltage regulating module is automatically set according to different power tubes, and the method can be used for different application scenes. Compared with the traditional control mode, the control mode is flexible in application.
In one example, the modification submodule specifically includes:
the third correcting unit is used for increasing the threshold voltage Vreg under the current working cycle to obtain the regulated threshold voltage when the third ratio Ta/Treg is smaller than a first set value m and lasts for a first set time length; when the third ratio Ta/Treg is larger than a second set value n and lasts for a second set time, reducing the threshold voltage Vreg under the current working period to obtain an adjusted threshold voltage; when the third ratio Ta/Treg is greater than or equal to a first set value m and less than or equal to a second set value n, keeping a threshold voltage Vreg under the current working cycle; the first set time length and the second set time length are set time periods td and set number of work cycles or 0. Wherein, the value range of the first set value m is (0, 1); the value range of the second set value n is (0, 1).
And automatically correcting the driving adjustment threshold voltage Vreg according to the size of Ta/Treg. Increasing the value of Vreg when Ta/Treg < m (0< m <1) continues for a first set time period td 1; when Ta/T > n (0< n <1) continues for the second set period td2, the value of Vreg is decreased. And if m is less than or equal to Ta/Treg is less than or equal to n, regulating Vreg.
And automatically correcting the driving adjustment threshold voltage Vreg according to the size of Ta/Treg. When Ta/Treg < m (0< m <1) and a set number of work cycles are continued, increasing the value of Vreg; when Ta/Treg > n (0< n <1) continues for a set number of duty cycles, the value of Vreg is reduced. And if m is less than or equal to Ta/Treg is less than or equal to n, regulating Vreg.
And automatically correcting the driving adjustment threshold voltage Vreg according to the size of Ta/Treg. When Ta/Treg < m (0< m <1), increasing the value of Vreg immediately; when Ta/Treg > n (0< n <1), the value of Vreg is immediately reduced. And if m is less than or equal to Ta/Treg is less than or equal to n, regulating Vreg.
In the example, the length of time Treg is adjusted by detecting the length of time Ta when the grid driving voltage of the power tube is completely turned on in the Vreg corresponding period and the length of time Treg when the grid driving voltage is adjusted. Through the processing of a circuit algorithm, the driving adjustment threshold voltage Vreg is automatically corrected, and Ta/Treg is restricted within a preset range. The voltage regulating threshold of the voltage regulating module is automatically set according to different power tubes, and the method can be used in different application scenes. Compared with the traditional control mode, the control mode is flexible in application.
The dynamic threshold adjustment system for isolated power supply driving is further described in detail below, and a specific implementation circuit of the voltage regulation module is provided.
When the dynamic threshold adjustment system drives a low-side synchronous rectification circuit (secondary-side control), the control structure is as shown in fig. 4.
Referring to fig. 4, the control structure includes a source-drain differential pressure detection module (Vds detection module), a turn-on/turn-off detection module, a voltage regulation module in the dynamic threshold adjustment system, and a driving circuit of the power tube. The Vds detection module circuit is responsible for detecting the drain terminal voltage Vds (drain-source voltage, namely drain terminal voltage, due to the fact that the source terminal is grounded), of the secondary side power tube, the source terminal of the secondary side power tube is grounded, and the drain terminal voltage, namely the drain terminal voltage Vds of the power tube, is represented. The Vds detection module is used for sampling and detecting the drain-source voltage of the power tube, the on-off detection module is used for controlling the on-off of the power tube, the voltage regulation module is used for controlling the adjustment of the dynamic threshold value, and the driving circuit generates a signal Vg for driving the power tube.
When the conduction detection module detects that the drain-source voltage Vds of the power tube is higher than the conduction negative voltage Vth1, the driving current controls the power tube M2 to be conducted. Then, the drain-source voltage Vds of the power tube is gradually reduced, and when the Vds is reduced to the driving adjustment threshold voltage Vreg, the driving circuit controls the power tube to enter a voltage regulation state. As the inductor current decreases, Vds decreases and Vg also gradually decreases, while the drain-source voltage Vds of the synchronous rectifier M2 is maintained at Vreg. When the inductor current decreases to the point that the turn-off detection module circuit detects that Vds is lower than the negative voltage threshold Vth2, the power tube is turned off.
The working principle of the voltage regulating module circuit is that the driving regulation threshold voltage Vreg is automatically corrected according to the size of Treg/T by detecting the power tube grid driving voltage conduction time T and the grid driving voltage regulation time Treg in the corresponding period of Vreg. When Treg/T < m (0< m <1) for a period td1, then decreasing the value of Vreg; when Treg/T > n (0< n <1) continues for a time td2, the value of Vreg is increased. And if m < Treg/T < n, not adjusting Vreg. The patent protects the control mode of automatically correcting and driving the adjustment threshold voltage Vreg through the processing of a circuit algorithm.
A specific implementation circuit for the first modification unit in the voltage regulation module is shown in fig. 5. Fig. 5 realizes the dynamic adjustment of the threshold voltage Vreg by detecting the Treg/T value.
The first correcting unit in the voltage regulating module specifically includes:
a first branch, a second branch, a third branch, a fourth branch, a first inverter 405, a second inverter 412, a third inverter 417, a first comparator 413, a second comparator 414, a latch timer, an up-down counter 418, and a digital-to-analog converter (DAC). The first comparator 413 and the second comparator 414 have a small amount of input offset voltage offset. The latch timer implements LOGIC latch timing.
The first branch comprises a first current source 401 (with current magnitude of mI2), a first transmission gate 403, a second transmission gate 408 and a second current source 410 (with current magnitude of I2) which are connected in sequence from a power supply voltage end to a ground end; the two ends of the first transmission gate 403 are connected in parallel with the first inverter 405; two ends of the second transmission gate 408 are connected in parallel with the second inverter 412; the connection point of the first transmission gate 403 and the second transmission gate 408 is a first common end; a third branch is connected between the first common end and the grounding end; the third branch comprises a first capacitor 406 and a first switch 415 in parallel.
The second branch comprises a third current source 402 (with the current magnitude of nI1), a third transmission gate 404, a fourth transmission gate 409 and a fourth current source 411 (with the current magnitude of I1) which are connected in sequence from a power supply voltage end to a ground end; the connection point of the third transmission gate 404 and the fourth transmission gate 409 is a second common terminal; a fourth branch is connected between the second common end and the grounding end; the fourth branch comprises a second capacitor 407 and a second switch 416 connected in parallel.
An input terminal of the first comparator 413 is connected to the first common terminal; the output terminal of the first comparator 413 is connected to the latch timer through the third inverter 417.
An input terminal of the second comparator 414 is connected to the second common terminal; the output of the second comparator 414 is connected to the latch timer.
The latch timer is connected to the dac via the up-down counter 418.
The first transmission gate is used for being connected with the output end of the duration detection submodule; the second transmission gate is used for being connected with the output end of the comparison submodule; the digital-to-analog converter is used for being connected with the input end of the output end of the comparison submodule so as to provide the adjusted threshold voltage for the comparison submodule. The comparison submodule can be a comparator or an operational amplifier.
The implementation principle of the circuit is as follows: EN _ on controls the conduction of the first transmission gate 403 and the fourth transmission gate 409 to charge and discharge the first capacitor 406 (with capacitance value of C2) and the second capacitor 407 (with capacitance value of C1), respectively, and EN _ reg controls the conduction of the second transmission gate 408 and the third transmission gate 404 to charge and discharge the first capacitor 406 (with capacitance value of C2) and the second capacitor 407 (with capacitance value of C1), respectively.
When Treg/T < m, the voltage of Vc2 is put to 0, the output of the first comparator 413 goes low, vreggigh goes from 0 to 1, and the state is latched by the latch timer, taking C1 as C2. If this state lasts for a certain time td1, then Vreg adjustment is implemented by the up-down counter 418 and the digital-to-analog converter, i.e. the value of Vreg is decreased, Treg will increase in the next cycle. When Treg/T > n, the voltage of Vc1 will be charged higher than 0, the output of the second comparator 414 will go high, VregLow will jump from 0 to 1 in one cycle, and the state is latched by the latch timer. If this state lasts for a certain time td2, Vreg adjustment is achieved by the up-down counter 418 and the digital-to-analog converter, i.e. Vreg is increased, Treg will decrease in the next cycle.
Fig. 6 shows the working waveforms of the dynamic threshold adjustment method implemented by the dynamic threshold adjustment system for the secondary side driving of the isolated power supply. Referring to fig. 6, in the first period, the adjustment voltage threshold is Vreg ', and the gate driving voltage of the power transistor is completely turned on for a time Ta ', and the gate driving voltage is adjusted for a time Treg '. In the second working period, Vreg' is fixed, and the gate driving voltage of the corresponding power tube is completely turned on for a time Ta, and the gate driving voltage is adjusted for a time Treg. Due to the fact that the secondary side power tube Rdson or other reasons cause that Vds touches Vreg ' after a long time Ta, the adjusting time is short, Treg ' < Treg meets the enabling condition Treg/T < m of the voltage adjusting module, after the state lasts for a certain time, VregLow is 1, the voltage adjusting circuit adjusts Vreg ' to Vreg0, the adjusting time length of the grid driving voltage of the power tube after adjustment is increased to Treg0, namely Treg0> Treg, and the Vreg continuous adjustment knows that Treg0/T > m > Treg/T is met.
Similarly, as shown in fig. 7, when Vds touches Vreg 'immediately after a short time Ta, the adjustment time is too long, and at this time, the regulator module enable condition Treg/T > n is satisfied, and after this state continues for a certain time, vreggh becomes 1, the regulator circuit down-regulates Vreg' to Vreg1, and the adjustment time length of the gate driving voltage of the power tube after adjustment is reduced to Treg1, at this time, Treg1< Treg, Vreg continues to be adjusted until Treg1/T < n < Treg/T is satisfied.
The dynamic threshold adjusting method of the drive can automatically correct the value of the threshold voltage Vreg, so that Treg/T is maintained in the range that m is less than or equal to Treg/T is less than or equal to n. In different synchronous rectifier tube applications and different application scenes, whether a high-side or low-side synchronous rectifier circuit is adopted, the power tube is provided with suitable driving capability, meanwhile, the accurate turn-off of the zero-current flowing of the inductance is realized, the conduction loss of the power tube can be reduced, and the efficiency is improved.
The invention also provides a dynamic threshold value adjusting method for the isolated power supply drive, which is used for the dynamic threshold value adjusting system in the embodiment. Referring to fig. 8, the method includes:
step 801: and detecting the time length of the complete opening of the grid driving voltage of the power tube in the isolation power supply and the time length of the adjustment of the grid driving voltage in the current working period.
Step 802: and adjusting the threshold voltage under the current working period according to the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage to obtain the adjusted threshold voltage.
Step 803: when the power tube is conducted in the current working period, acquiring a source-drain pressure difference and the adjusted threshold voltage, comparing the source-drain pressure difference with the adjusted threshold voltage, and outputting a driving signal of the next working period to a driving circuit; the drive circuit is used for adjusting the grid drive voltage of the power tube in the next working period according to the drive signal in the next working period; and the source-drain pressure difference is detected by the source-drain pressure difference detection module and is the source-drain pressure difference of the power tube at the primary side control side or the secondary side control side of the isolation power supply.
In one example, step 802 specifically includes:
1) and determining the sum of the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage as the grid driving voltage opening time length of the power tube in the current working period.
2) Adjusting the threshold voltage under the current working cycle according to the first ratio, the second ratio or the third ratio to obtain the adjusted threshold voltage; the first ratio is the ratio of the time length of the adjustment of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the ratio of the time length of the complete opening of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the time length for which the gate driving voltage is completely turned on and the time length for which the gate driving voltage is adjusted.
The first implementation manner of the step 2) is as follows:
and when the first ratio is smaller than a first set value and lasts for a first set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage.
And when the first ratio is greater than a second set value and lasts for a second set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage.
When the first ratio is greater than or equal to a first set value and less than or equal to a second set value, maintaining the threshold voltage under the current working period; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
The second implementation manner of the step 2) is as follows:
and when the second ratio is smaller than the first set value and lasts for the first set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage.
And when the second ratio is greater than a second set value and lasts for a second set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage.
When the second ratio is greater than or equal to the first set value and less than or equal to the second set value, maintaining the threshold voltage under the current working cycle; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
The third implementation manner of the step 2) is as follows:
and when the third ratio is smaller than the first set value and lasts for the first set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage.
And when the third ratio is greater than a second set value and lasts for a second set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage.
When the third ratio is greater than or equal to the first set value and less than or equal to the second set value, maintaining the threshold voltage under the current working cycle; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
The dynamic threshold adjusting method for the isolated power supply driving of the embodiment can realize accurate turn-off when the inductance current passes through zero in different synchronous rectifier tube applications; and the accurate turn-off of the power tube can be realized when the inductive current passes zero, and the conduction loss of the power tube can be reduced.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The method disclosed by the embodiment corresponds to the system disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the system part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (10)

1. A dynamic threshold adjustment system for an isolated power supply drive, comprising: a voltage regulating module; the voltage regulating module is used for being connected with a source-drain pressure difference detection module, a conduction-disconnection detection module and a driving circuit in a primary side control unit or a secondary side control unit of the isolation power supply; the source-drain pressure difference detection module is used for detecting the source-drain pressure difference of the power tube at the primary side control side or the secondary side control side of the isolation power supply;
the voltage regulating module is used for:
detecting the time length of the grid driving voltage of the power tube in the current working period being completely switched on and the time length of the grid driving voltage adjustment;
adjusting the threshold voltage under the current working period according to the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage to obtain the adjusted threshold voltage;
when the power tube is conducted in the current working period, acquiring the source-drain pressure difference and the adjusted threshold voltage, comparing the source-drain pressure difference with the adjusted threshold voltage, and outputting a driving signal of the next working period to the driving circuit; the driving circuit is used for adjusting the grid driving voltage of the power tube in the next working period according to the driving signal in the next working period.
2. The dynamic threshold adjustment system for isolated power drivers of claim 1, wherein the voltage regulation module specifically comprises:
the time length detection submodule is used for obtaining the time length of the complete opening of the grid driving voltage of the power tube and the time length of the adjustment of the grid driving voltage in the current working period according to the grid driving voltage of the power tube in the current working period, and determining the sum of the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage as the grid driving voltage conducting time length of the power tube in the current working period;
the correction submodule is used for adjusting the threshold voltage under the current working cycle according to the first ratio, the second ratio or the third ratio to obtain the adjusted threshold voltage; the first ratio is the ratio of the time length of the adjustment of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the ratio of the time length of the complete opening of the grid driving voltage to the conduction time length of the grid driving voltage; the third ratio is the ratio of the time length of the complete opening of the grid driving voltage to the time length of the adjustment of the grid driving voltage;
and the comparison submodule is used for acquiring the source-drain voltage difference and the adjusted threshold voltage when the power tube is conducted in the current working period, and outputting a driving signal of the next working period to the driving circuit when the source-drain voltage difference reaches the adjusted threshold voltage so as to adjust the grid driving voltage of the power tube in the next working period.
3. The dynamic threshold adjustment system for an isolated power driver of claim 2, wherein the modification submodule specifically comprises:
the first correction unit is used for reducing the threshold voltage under the current working cycle to obtain the adjusted threshold voltage when the first ratio is smaller than a first set value and lasts for a first set time length; when the first ratio is larger than a second set value and lasts for a second set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage; when the first ratio is greater than or equal to a first set value and less than or equal to a second set value, maintaining the threshold voltage under the current working period; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
4. The dynamic threshold adjustment system for an isolated power driver of claim 2, wherein the modification submodule specifically comprises:
the second correction unit is used for increasing the threshold voltage under the current working cycle to obtain the adjusted threshold voltage when the second ratio is smaller than the first set value and lasts for a first set time; when the second ratio is greater than a second set value and lasts for a second set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage; when the second ratio is greater than or equal to the first set value and less than or equal to the second set value, maintaining the threshold voltage under the current working cycle; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
5. The dynamic threshold adjustment system for an isolated power driver of claim 2, wherein the modification submodule specifically comprises:
the third correction unit is used for increasing the threshold voltage under the current working cycle to obtain the adjusted threshold voltage when the third ratio is smaller than the first set value and lasts for the first set time; when the third ratio is greater than a second set value and lasts for a second set time, reducing the threshold voltage under the current working period to obtain the adjusted threshold voltage; when the third ratio is greater than or equal to the first set value and less than or equal to the second set value, maintaining the threshold voltage under the current working cycle; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
6. The dynamic threshold adjustment system for an isolated power driver according to claim 3, wherein the first modification unit specifically includes:
the circuit comprises a first branch circuit, a second branch circuit, a third branch circuit, a fourth branch circuit, a first inverter, a second inverter, a third inverter, a first comparator, a second comparator, a latch timer, an addition-subtraction counter and a digital-to-analog converter;
the first branch comprises a first current source, a first transmission gate, a second transmission gate and a second current source which are sequentially connected from a power supply voltage end to a grounding end; two ends of the first transmission gate are connected with the first inverter in parallel; two ends of the second transmission gate are connected with the second inverter in parallel; the connection point of the first transmission gate and the second transmission gate is a first common end; a third branch is connected between the first common end and the grounding end; the third branch comprises a first capacitor and a first switch which are connected in parallel;
the second branch circuit comprises a third current source, a third transmission gate, a fourth transmission gate and a fourth current source which are sequentially connected from a power supply voltage end to a grounding end; a connection point of the third transmission gate and the fourth transmission gate is a second common terminal; a fourth branch is connected between the second common end and the grounding end; the fourth branch comprises a second capacitor and a second switch which are connected in parallel;
the input end of the first comparator is connected with the first public end; the output end of the first comparator is connected with the latch timer through the third inverter;
the input end of the second comparator is connected with the second common end; the output end of the second comparator is connected with the latch timer;
the latch timer is connected with the digital-to-analog converter through the addition and subtraction counter;
the first transmission gate is used for being connected with the output end of the duration detection submodule; the second transmission gate is used for being connected with the output end of the comparison submodule; the digital-to-analog converter is used for being connected with the input end of the output end of the comparison submodule so as to provide the adjusted threshold voltage for the comparison submodule.
7. The dynamic threshold adjustment system for the isolated power supply driver according to claim 3, wherein the first set value has a value range of (0, 1); the value range of the second set value is (0, 1).
8. A dynamic threshold adjustment method for isolated power supply driving, for use in the dynamic threshold adjustment system of any one of claims 1-7, the method comprising:
detecting the time length of the complete opening of the grid driving voltage of a power tube in the isolation power supply and the time length of the adjustment of the grid driving voltage in the current working period;
adjusting the threshold voltage under the current working period according to the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage to obtain the adjusted threshold voltage;
when the power tube is conducted in the current working period, acquiring a source-drain pressure difference and the adjusted threshold voltage, comparing the source-drain pressure difference with the adjusted threshold voltage, and outputting a driving signal of the next working period to a driving circuit; the drive circuit is used for adjusting the grid drive voltage of the power tube in the next working period according to the drive signal in the next working period; and the source-drain pressure difference is detected by the source-drain pressure difference detection module and is the source-drain pressure difference of the power tube at the primary side control side or the secondary side control side of the isolation power supply.
9. The method according to claim 8, wherein the adjusting the threshold voltage in the current duty cycle according to the time length of the gate driving voltage being completely turned on and the time length of the gate driving voltage being adjusted to obtain the adjusted threshold voltage specifically comprises:
determining the sum of the time length of the complete opening of the grid driving voltage and the time length of the adjustment of the grid driving voltage as the grid driving voltage opening time length of the power tube under the current working period;
adjusting the threshold voltage under the current working period according to the first ratio, the second ratio or the third ratio to obtain the adjusted threshold voltage; the first ratio is the ratio of the time length of the adjustment of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the ratio of the time length of the complete opening of the grid driving voltage to the conduction time length of the grid driving voltage; the second ratio is the time length for which the gate driving voltage is completely turned on and the time length for which the gate driving voltage is adjusted.
10. The method according to claim 9, wherein the adjusting the threshold voltage in the current duty cycle according to the first ratio, the second ratio, or the third ratio to obtain the adjusted threshold voltage specifically comprises:
when the first ratio is smaller than a first set value and lasts for a first set time, reducing the threshold voltage under the current working period to obtain an adjusted threshold voltage;
when the first ratio is larger than a second set value and lasts for a second set time, increasing the threshold voltage under the current working period to obtain the adjusted threshold voltage;
when the first ratio is greater than or equal to a first set value and less than or equal to a second set value, maintaining the threshold voltage under the current working period; the first set time length and the second set time length are set time periods and set number of work cycles or 0.
CN202210349490.0A 2022-04-02 2022-04-02 Dynamic threshold adjusting system and method for isolated power supply drive Pending CN114825954A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210349490.0A CN114825954A (en) 2022-04-02 2022-04-02 Dynamic threshold adjusting system and method for isolated power supply drive

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210349490.0A CN114825954A (en) 2022-04-02 2022-04-02 Dynamic threshold adjusting system and method for isolated power supply drive

Publications (1)

Publication Number Publication Date
CN114825954A true CN114825954A (en) 2022-07-29

Family

ID=82532842

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210349490.0A Pending CN114825954A (en) 2022-04-02 2022-04-02 Dynamic threshold adjusting system and method for isolated power supply drive

Country Status (1)

Country Link
CN (1) CN114825954A (en)

Similar Documents

Publication Publication Date Title
CN110149042B (en) Power tube grid driving circuit with sectional driving function
US10116222B2 (en) Soft switching flyback converter with primary control
CN102231605B (en) Synchronous rectification control circuit of switch power supply secondary and flyback switch power supply
US8130515B2 (en) Bi-directional DC-DC converter and method for controlling the same
WO2013037309A1 (en) Adaptive dead time control apparatus and method for switching power converters
CN102545662A (en) Switch control circuit, converter using the same, and switch control method
EP4047804B1 (en) Converter and power adapter
CN111585440B (en) Control system and method of active clamp flyback converter
CN113726165B (en) Flyback converter and control method thereof
CN101902134A (en) Supply unit
WO2020228818A1 (en) Synchronous rectification control system and method for quasi-resonant flyback converter
CN110829846A (en) Zero-voltage switch control circuit and method applied to switching power supply
CN111786563A (en) Synchronous rectification control circuit and switching power supply
CN114189156B (en) Flyback switching circuit and control method thereof
CN111585441B (en) Control system and method for primary side regulation active clamping flyback converter
CN110994982A (en) Soft switching mode BUCK converter and control method thereof
US10418910B2 (en) Isolated switch-mode power supply and control circuit and control method for isolated switch-mode power supply
CN113726166A (en) Flyback converter and control method thereof
CN111682769B (en) Self-adaptive synchronous rectification digital control method of active clamp forward converter
CN109177780B (en) Charging control method and device and electric automobile
CN114825954A (en) Dynamic threshold adjusting system and method for isolated power supply drive
JP4098494B2 (en) Switching power supply
CN112737339A (en) Self-adaptive soft drive control circuit
CN111786561A (en) Synchronous rectification control circuit, control method and switching power supply
CN108429468A (en) It adaptively adjusts the synchronous rectifying controller of driving voltage and uses its circuit

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination