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WO2024169135A1 - 采样控制系统、方法、控制器、原边反馈交直流转换器 - Google Patents

采样控制系统、方法、控制器、原边反馈交直流转换器 Download PDF

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Publication number
WO2024169135A1
WO2024169135A1 PCT/CN2023/110892 CN2023110892W WO2024169135A1 WO 2024169135 A1 WO2024169135 A1 WO 2024169135A1 CN 2023110892 W CN2023110892 W CN 2023110892W WO 2024169135 A1 WO2024169135 A1 WO 2024169135A1
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WIPO (PCT)
Prior art keywords
capacitor
switch
sampling
time
primary
Prior art date
Application number
PCT/CN2023/110892
Other languages
English (en)
French (fr)
Inventor
杨兆年
Original Assignee
西安致芯微电子有限公司
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Publication of WO2024169135A1 publication Critical patent/WO2024169135A1/zh

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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0046—Arrangements for measuring currents or voltages or for indicating presence or sign thereof characterised by a specific application or detail not covered by any other subgroup of G01R19/00
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0006—Arrangements for supplying an adequate voltage to the control circuit of converters
    • 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
    • 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
    • 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

Definitions

  • the present invention relates to the technical field of switching power supplies, and more specifically, to a sampling control system, method, controller, and a primary-side feedback AC/DC converter.
  • PSR Primary side feedback
  • FIG1 is a block diagram of a primary feedback AC-DC converter of the prior art.
  • the primary feedback AC-DC drive power supply includes a rectifier bridge BR, an input capacitor Cin, a start-up resistor R4, a power supply rectifier diode D1, a power supply capacitor C1, an upper voltage divider resistor R1 and a lower voltage divider resistor R2, a controller, a transformer 200, a power tube N1, a current detection resistor Rcs, a rectifier diode D2, and an output capacitor Cout; wherein the transformer includes a primary winding Np, an auxiliary winding Na, and a secondary winding Ns; the upper voltage divider resistor R1 and the lower voltage divider resistor R2 constitute a sampling circuit, and the FB pin is the voltage feedback lead-in pin of the auxiliary winding Na of the transformer, and obtains a signal from the sampling circuit constituted by the upper voltage divider resistor R1 and the lower voltage divider resistor R2.
  • the FB pin maintains and controls the operating frequency through the sampling control circuit.
  • the primary side of the transformer is turned on, and the transformer stores energy. Since the polarity of the primary winding Np of the transformer is opposite to the same-name end of the auxiliary winding Na and the secondary winding Ns, the FB pin is a negative voltage when the primary side is turned on; when the power tube is turned off and the system is in the demagnetization stage, the secondary side of the transformer releases energy. Since the polarity of the same-name end of the auxiliary winding Na is the same as that of the secondary winding Ns, the FB voltage is a positive voltage.
  • the controller samples the VFB voltage at this time and compares it with the reference voltage to control the switching frequency so that the output voltage Vo is stable at the set value; during the demagnetization stage, the secondary current decreases with time, and when it drops to 0, the secondary demagnetization ends.
  • the primary power tube N1 is not turned on again, the feedback voltage signal FB enters resonance, and the demagnetization time of the secondary winding is recorded as Tons.
  • FB voltage sampling is very important.
  • the secondary-side demagnetization stage the secondary-side power flowing through the Schottky will generate a voltage drop Vz.
  • the forward voltage drop of Vz decreases as the current decreases. Therefore, sampling as close to the end of demagnetization as possible can make Vz as small as possible, so that the detected output voltage Vo is as close to the actual output voltage as possible.
  • the traditional approach is generally to first detect the demagnetization time Tons(n-1) of the previous cycle, and then take 2/3 of the demagnetization time of the previous cycle as the sampling time during the demagnetization of this cycle.
  • the early PSR flyback controller generally adopts a CS (Current Sense, primary current) peak fixed solution.
  • the CS peak values of two adjacent cycles are basically equal, and the demagnetization time of two adjacent cycles is also basically equal. It is not wrong to take 2/3 of the demagnetization time of the previous cycle as the sampling time of this cycle.
  • the CS peak value of the current PSR flyback controller is no longer fixed, but changes with the load. The lighter the load, the smaller the CS peak value, that is, the smaller the secondary-side demagnetization current.
  • the CS peak is the largest at full load
  • the demagnetization current peak of the secondary winding is the largest, recorded as Ips
  • the sampling is performed at 2/3 of the Tons time, and the Schottky current is 0.33Ips at this time; when the CS peak drops to 1/3 of the maximum value at light load, the peak of the secondary demagnetization current is only 0.33Ips.
  • the Schottky current at the time of sampling is 0.11Ips. Due to the current of 0.33Ips and 0.11Ips, there will be a large difference in the Schottky voltage drop.
  • the present invention provides a sampling control system for a primary feedback AC/DC converter, wherein the primary feedback AC/DC converter comprises a transformer, wherein the transformer has a primary winding, a secondary winding and an auxiliary winding, and the sampling control system comprises a charging module, an energy storage module, a discharging module and a control sampling module, wherein the charging module is used to charge the energy storage module, and the discharging module is used to discharge the energy storage module, and the control sampling module is used to control the charging of the charging module, control the discharging of the discharging module and adjust the generation time of the sampling pulse according to the primary current peak value of the primary winding, wherein the smaller the primary current peak value is, the shorter the time distance between the generation time and the start demagnetization time of the secondary winding is, and the control sampling module also samples the feedback voltage signal of the auxiliary winding of the transformer within the sampling time of the sampling pulse.
  • the charging module includes a first charging unit, a second charging unit and a third charging unit;
  • the energy storage module includes a first energy storage element and a second energy storage element;
  • the discharging module includes a first discharging unit and a second discharging unit;
  • the first charging unit is used to charge the first energy storage element
  • the second charging unit is used to charge the second energy storage element
  • the third charging unit is used to control the second energy storage element.
  • the first energy storage element is used for charging the first energy storage element
  • the first discharging unit is used for discharging the first energy storage element
  • the second discharging unit is used for discharging the second energy storage element.
  • the first charging unit includes a first current source and a first switch; the second charging unit includes a second current source and a second switch; the third charging unit includes a fifth switch; the first energy storage element includes a first capacitor; the second energy storage element includes a second capacitor; the first discharging unit includes a third switch; the second discharging unit includes a fourth switch;
  • the first current source is electrically connected to the positive plate of the first capacitor through the first switch, and the negative plate of the first capacitor is grounded;
  • the second current source is electrically connected to the positive plate of the second capacitor through the second switch, and the negative plate of the second capacitor is grounded;
  • the third switch is electrically connected to the positive plate of the first capacitor;
  • the fourth switch is electrically connected to the positive plate of the second capacitor;
  • the fifth switch is electrically connected between the positive plate of the first capacitor and the positive plate of the second capacitor.
  • the control sampling module includes a comparator, a pulse generator and a timing generator.
  • the positive input of the comparator is the output voltage of the second energy storage element
  • the negative input of the comparator is the output voltage of the first energy storage element
  • the output end of the comparator is electrically connected to the input end of the pulse generator
  • the timing generator collects the primary on-off signal of the transformer.
  • the primary on-off signal is high level
  • the primary on-off signal is low level.
  • the timing generator sends a discharge signal to the second discharge unit, and the second discharge unit discharges the second energy storage element.
  • the timing generator sends a second charging signal.
  • the timing generator sends a signal to the second charging unit, and the second charging unit charges the second energy storage element.
  • the timing generator sends the first charging signal to the first charging unit after a set delay time relative to sending the second charging signal, and the first charging unit charges the first energy storage element.
  • the comparator triggers the pulse generator, and the pulse generator generates a sampling pulse to the timing generator and sends the sampling pulse as a discharge signal to the first discharge unit.
  • the timing generator receives the sampling signal sent by the pulse generator and samples the feedback voltage signal of the auxiliary winding of the transformer.
  • the secondary side demagnetization is completed, and the timing generator sends a charging signal to the third charging unit, and the second energy storage element charges the first energy storage element.
  • the charging module includes a first charging unit, a second charging unit and a third charging unit, the first charging unit includes a first current source and a first switch, the second charging unit includes a second current source and a second switch, and the third charging unit includes a fifth switch;
  • the energy storage module includes a first energy storage element and a second energy storage element, the first energy storage element includes a first capacitor, and the second energy storage element includes a second capacitor;
  • the discharge module includes a first discharge unit and a second discharge unit, the first discharge unit includes a third switch, and the second discharge unit includes a fourth switch;
  • the control sampling module includes a comparator, a pulse generator and a timing generator; wherein the first current source is connected to the first discharge unit through The first switch is electrically connected to the positive plate of the first capacitor, and the negative plate of the first capacitor is grounded.
  • the second current source is electrically connected to the positive plate of the second capacitor through the second switch, and the negative plate of the second capacitor is grounded.
  • the third switch is electrically connected to the positive plate of the first capacitor, and the fourth switch is electrically connected to the positive plate of the second capacitor.
  • the fifth switch is electrically connected between the positive electrodes of the first capacitor and the second capacitor.
  • the positive input terminal of the comparator is electrically connected to the positive plate of the second capacitor, and the negative input terminal of the comparator is connected to the positive plate of the first capacitor.
  • the output terminal of the comparator is connected to the input terminal of the pulse generator, and the output terminal of the pulse generator is electrically connected to the timing generator.
  • the timing generator collects the primary on-off signal of the transformer.
  • the timing generator When the primary winding is turned on, the primary on-off signal is high level. When the primary winding is turned off, the primary on-off signal is low level. When the primary on-off signal is converted from high level to low level, the timing generator sends a discharge signal to the fourth The first capacitor is discharged when the output voltage of the second capacitor is 0V, and the fourth switch is disconnected. The timing generator sends a second charging signal to the second switch, and the second switch is turned on. The second current source charges the second capacitor. The timing generator sends a first charging signal to the first switch after a delay setting time relative to sending the second charging signal. The first switch is turned on, and the first current source charges the first capacitor.
  • the first switch When the output voltage of the second capacitor is equal to the output voltage of the first capacitor, the first switch is disconnected.
  • the comparator triggers the pulse generator, and the pulse generator generates a sampling pulse to the timing generator.
  • the timing generator samples the feedback voltage signal of the transformer.
  • the pulse generator sends the sampling pulse as a discharge signal to the third switch.
  • the third switch is turned on, the first capacitor is discharged, and the output voltage of the first capacitor is 0V.
  • the timing generator sends a charging signal to the fifth switch, and the fifth switch is turned on.
  • the second capacitor charges the first capacitor.
  • the timing generator includes a secondary side demagnetization time obtaining unit, a judgment unit, a sampling pulse generation time determining unit, a signal acquisition unit and a signal sending unit, wherein:
  • the signal acquisition unit is used to collect the primary on/off signal and the feedback voltage signal
  • the secondary side demagnetization time acquisition unit is used to obtain the secondary side demagnetization time according to the primary side current peak value collected by the signal acquisition unit;
  • the judging unit is used to judge whether the demagnetization time obtained by the secondary-side demagnetization time obtaining unit is not greater than the demagnetization threshold;
  • the sampling pulse generation time determination unit is used to determine the generation time of the sampling pulse according to the judgment result of the judgment unit.
  • the judgment result of the judgment unit is that the demagnetization time is not greater than the demagnetization threshold
  • the distance t between the generation time and the demagnetization start time is
  • c1 is the capacitance value of the first capacitor
  • c2 is the capacitance value of the second capacitor
  • Tons is the demagnetization time
  • the judgment result of the judgment unit is that the demagnetization time is greater than the demagnetization threshold
  • the distance t between the generation time and the start demagnetization time meets the following formula:
  • a is the current ratio of the first current source to the second current source
  • b is the current ratio of the first capacitor to the The capacitance ratio of the second capacitor
  • td is the set time of delay of the first charging signal relative to the second charging signal
  • the signal sending unit is used to control the first switch, the second switch, the third switch, the fourth switch and the fifth switch according to the demagnetization time obtained by the secondary side demagnetization time obtaining unit and the generation time determined by the sampling pulse generation time determination unit, so that the sampling pulse is generated at the pulse generator at the generation time.
  • the current value of the first current source is 0.9 times the current value of the second current source, so that the voltage rise slope of the second capacitor is 0.6 times the voltage rise slope of the first capacitor.
  • the sampling time t is finally achieved. The closer the current values of the two current sources are, the higher the matching degree is. The greater the difference in the current values of the two current sources is, the greater the possibility of mismatch is.
  • the capacitance value of the first capacitor is 1.5 times the capacitance value of the second capacitor.
  • the demagnetization threshold is 4us.
  • 4us is mainly for the real PSR power supply system currently in mass production in the industry.
  • the minimum demagnetization time is generally between 3-5us, so the demagnetization threshold is 4us.
  • the demagnetization threshold is less than 3us. If it is too small, interference caused by resonance will occur.
  • the set delay time of the first charging signal relative to the second charging signal is 1.6us.
  • the interference time caused by resonance is generally around 1us; therefore, the chip generally prohibits sampling within 1-2.5us to prevent resonance interference, and 1.6us is a suitable intermediate value; at the same time, 1.6us is 40% of the demagnetization threshold of the present invention, which satisfies the sampling time between 0.4*Tons—0.8*Tons.
  • a sampling control method for controlling the sampling of a feedback voltage signal of a primary feedback AC/DC converter, wherein the primary feedback AC/DC converter comprises a transformer, wherein the transformer has a primary winding, a secondary winding and an auxiliary winding, and the feedback voltage signal is a voltage-divided signal of the output voltage of the auxiliary winding, and comprises: adjusting the generation time of the sampling pulse according to the primary current peak value of the primary winding of the primary feedback AC/DC converter, wherein the smaller the primary current peak value is, the shorter the distance between the generation time and the start demagnetization time of the secondary winding is.
  • the step of adjusting the generation time of the sampling pulse according to the primary current peak value of the primary winding of the primary feedback AC/DC converter comprises:
  • the generation time of the sampling pulse remains unchanged
  • the sampling pulse generation time is the same as the secondary winding
  • the time distance from the start of demagnetization increases with the increase of the primary current peak value.
  • the demagnetization threshold is 4us
  • the sampling pulse is 4us
  • the initial value of the time distance between the generation time and the start time of demagnetization is 0.4*Tons.
  • the time distance between the generation time of the sampling pulse and the start time of demagnetization conforms to the following formula:
  • t is the time distance between the generation time and the start of demagnetization time
  • Tons is the demagnetization time
  • the primary current peak value varies from 1 times to 3 times
  • the time distance between the generation time of the sampling pulse and the start time of demagnetization varies from 0.4*Tons to 0.8*Tons.
  • a controller comprising the above-mentioned sampling control system.
  • a primary-side feedback AC-DC converter comprising a transformer and the above-mentioned controller.
  • the present invention adopts a control system and a method that adopts a sampling method that changes with the CS peak value.
  • the sampling time changes from 0.4*Tons to 0.8*Tons, so that CS can change arbitrarily within the above range.
  • the current of Schottky is fixed, so that the detected output voltage will not introduce additional errors due to the different forward voltage drops of Schottky under different currents, thereby ensuring a good load regulation rate.
  • FIG1 is a block diagram of a primary-side feedback AC/DC converter of the prior art
  • FIG2 is a schematic block diagram of an embodiment of the sampling control system of the present invention.
  • FIG3 is a circuit diagram of an embodiment of the sampling control system of the present invention.
  • FIG4 is a schematic diagram of waveforms of various signals of the sampling control system of the present invention.
  • FIG. 5 is a waveform diagram of sampling of different primary current peak values by the sampling control system of the present invention.
  • FIG6 is a schematic diagram of a primary-side feedback AC-DC converter according to the present invention.
  • 1-sampling control system 11-charging module, 111-first charging unit, 101-
  • first current source 103-first switch, 112-second charging unit, 102-second current source, 106-second switch, 113-third charging unit, 105-fifth switch, 12-energy storage module, 121-first energy storage element, 108-first capacitor, 122-second energy storage element, 109-second capacitor, 13-discharging module, 131-first discharging unit, 104 third switch, 132-second discharging unit, 107-fourth switch, 14-control sampling module, 141-comparator, 142-pulse generator, 143-timing generator, 1431-signal acquisition unit, 1432-secondary demagnetization time acquisition unit, 1433-judgment unit, 1434-sampling pulse generation time determination unit, 1435-signal Transmitting unit; 2-operational amplifier; 3-frequency control unit; 4-RS trigger; 5-driving unit; 6-cycle-by-cycle current limiting unit, 7-built-in power supply; 100-controller; 200-transformer.
  • FIG2 is a schematic block diagram of an embodiment of the sampling control system of the present invention.
  • the sampling control system 1 is used for a primary feedback AC/DC converter.
  • the primary feedback AC/DC converter includes a transformer.
  • the transformer has a primary winding, a secondary winding, and an auxiliary winding.
  • the generation time of the sampling pulse is adjusted according to the primary current peak value of the primary winding of the transformer, so that when the primary peak current changes cycle by cycle, the output voltage does not change with the change of the primary peak current.
  • the sampling control system 1 of the present invention includes a charging module 11, an energy storage module 12, a discharging module 13 and a control sampling module 14.
  • the charging module 11 is used to charge the energy storage module 12, and the discharging module 13 is used to discharge the energy storage module 12.
  • the control sampling module 14 is used to control the charging of the charging module 11, control the discharging of the discharging module 13, and adjust the generation time of the sampling pulse according to the primary current peak value of the primary winding. The smaller the primary current peak value, the shorter the time distance between the generation time and the start demagnetization time of the secondary winding.
  • the control sampling module 14 also samples the feedback voltage signal of the auxiliary winding of the transformer within the sampling time of the sampling pulse.
  • the charging module 11 includes a first charging unit 111 , a second charging unit 112 and a third charging unit 113 ;
  • the energy storage module 12 includes a first energy storage element 121 and a second energy storage element 122 ;
  • the discharging module 13 includes a first discharging unit 131 and a second discharging unit 132 ;
  • the first charging unit 111 is used to charge the first energy storage element 121
  • the second charging unit 112 is used to charge the second energy storage element 122
  • the third charging unit 113 is used to control the charging of the first energy storage element 121 by the second energy storage element 122
  • the first discharging unit 131 is used to discharge the first energy storage element 121
  • the second discharging unit 132 is used to discharge the second energy storage element 122.
  • the first charging unit 111 includes a first current source 101 and a first switch 103; the second charging unit 112 includes a second current source 102 and a second switch 106; the third charging unit 113 includes a fifth switch 105; the first energy storage element 121 includes a first capacitor 108; the second energy storage element 122 includes a second capacitor 109; the first discharging unit 131 includes a third switch 104; the second discharging unit 132 includes a fourth switch 107;
  • the first current source 101 is connected to the first capacitor 108 through the first switch 103.
  • the positive plate is electrically connected, the negative plate of the first capacitor 108 is grounded
  • the second current source 102 is electrically connected to the positive plate of the second capacitor 109 through the second switch 106
  • the negative plate of the second capacitor 109 is grounded
  • the third switch 104 is electrically connected to the positive plate of the first capacitor 108
  • the fourth switch 107 is electrically connected to the positive plate of the second capacitor 109
  • the fifth switch 105 is electrically connected between the positive plate of the first capacitor 108 and the positive plate of the second capacitor 109.
  • the control sampling module 14 includes a comparator 141, a pulse generator 142 and a timing generator 143.
  • the positive input of the comparator 141 is the output voltage of the second energy storage element 122
  • the negative input of the comparator 141 is the output voltage of the first energy storage element 121.
  • the output end of the comparator 141 is electrically connected to the input end of the pulse generator 142.
  • the timing generator 143 collects the primary on-off signal of the transformer. When the primary winding is turned on, the primary on-off signal is high level. When the primary winding is turned off, the primary on-off signal is low level.
  • the timing generator 143 sends a discharge signal to the second discharge unit 132.
  • the second discharge unit 132 discharges the second energy storage element 122.
  • the timing generator 143 sends a second charging signal to the second charging Unit 112
  • the second charging unit 112 charges the second energy storage element 122
  • the timing generator 143 sends the first charging signal to the first charging unit 111 after a delay setting time relative to sending the second charging signal
  • the first charging unit 111 charges the first energy storage element 121, when the output voltage of the second energy storage element 122 is equal to the output voltage of the first energy storage element 121
  • the first charging unit 111 finishes charging the first energy storage element 121
  • the comparator 141 triggers the pulse generator 142
  • the pulse generator 142 generates a sampling pulse to the timing generator 143 and sends the sampling pulse as a discharge signal to the first discharge unit 131, the
  • the charging module 11 includes a first charging unit 111, a second charging unit 112 and a third charging unit 113, wherein the first charging unit 111 includes a first current source 101 and a first switch 103, the second charging unit 112 includes a second current source 102 and a second switch 106, and the third charging unit 113 includes a fifth switch 105;
  • the energy storage module 12 includes a first energy storage element 121 and a second energy storage element 122, the first energy storage element 121 includes a first capacitor 108, and the second energy storage element 122 includes a second capacitor 109;
  • the discharging module 13 includes a first discharging unit 131 and a second discharging unit 132, the first discharging unit 131 includes a third switch 104, and the second discharging unit 132 includes a fourth switch 107;
  • the control sampling module 14 includes a comparator 141, a pulse generator 142 and a timing generator 143;
  • the first current source 101 is electrically connected to the positive plate of the first capacitor 108 through the first switch 103, the negative plate of the first capacitor 108 is grounded, the second current source 102 is electrically connected to the positive plate of the second capacitor 109 through the second switch 106, the negative plate of the second capacitor 109 is grounded
  • the third switch 104 is electrically connected to the positive plate of the first capacitor 108
  • the fourth switch 107 is electrically connected to the positive plate of the second capacitor 109
  • the fifth switch 105 is electrically connected between the positive electrodes of the first capacitor 108 and the second capacitor 109
  • the positive input terminal of the comparator 141 is electrically connected to the positive plate of the second capacitor 109
  • the negative input terminal of the comparator 141 is connected to the positive plate of the first capacitor 108
  • the output terminal of the comparator 141 is connected to the input terminal of the pulse generator 142
  • the output end of the pulse generator 142 is electrically connected to the timing generator 143.
  • the timing generator 143 collects the primary on-off signal of the transformer. When the primary winding is turned on, the primary on-off signal is high level. When the primary winding is turned off, the primary on-off signal is low level. When the primary on-off signal is converted from high level to low level, the timing generator 143 sends a discharge signal to the fourth switch 107. The fourth switch 107 is turned on, and the second capacitor 109 is discharged. When the output voltage of the second capacitor 109 is 0V, the fourth switch 107 is turned off. The timing generator 143 sends a second charging signal to the second switch 106, the second switch 106 is turned on, and the second current source 102 charges the second capacitor 109.
  • the timing generator 143 sends a first charging signal to the first switch 103 after a set delay time relative to the sending of the second charging signal.
  • the first switch 103 is turned on, and the first current source 101 charges the first capacitor 108.
  • the first switch 103 is turned off, and the comparator 141 triggers the pulse generator 142.
  • the pulse generator 142 generates a sampling pulse to the timing generator 143, and the timing generator 143 samples the feedback voltage signal of the transformer.
  • the pulse generator 142 sends the sampling pulse as a discharge signal to the third switch 104, the third switch 104 is turned on, the first capacitor 108 is discharged, and the output voltage of the first capacitor 108 is 0V.
  • the timing generator 143 sends a charging signal to the fifth switch 105, the fifth switch 105 is turned on, and the second capacitor 109 charges the first capacitor 108.
  • the timing generator 143 includes a secondary side demagnetization time obtaining unit 1432, a judging unit 1433, a sampling pulse generation time determining unit 1434, a signal collecting unit 1431 and a signal sending unit 1435, wherein:
  • the signal acquisition unit 1431 is used to collect the primary on/off signal and the feedback voltage signal
  • the secondary side demagnetization time obtaining unit 1432 is used to obtain the secondary side demagnetization time according to the primary side current peak value collected by the signal collecting unit 1431;
  • the judging unit 1433 is used to judge whether the demagnetization time obtained by the secondary-side demagnetization time obtaining unit 1432 is not greater than the demagnetization threshold;
  • the sampling pulse generation time determination unit 1434 is used to determine the generation time of the sampling pulse according to the judgment result of the judgment unit 1433.
  • the judgment result of the judgment unit 1433 is that the demagnetization time is not greater than the demagnetization threshold
  • the distance t between the generation time and the demagnetization start time is
  • c1 is the capacitance value of the first capacitor 108
  • c2 is the capacitance value of the second capacitor 109
  • Tons is the demagnetization time
  • the judgment result of the judgment unit 1433 is that the demagnetization time is greater than the demagnetization threshold
  • the distance t between the generation time and the start demagnetization time meets the following formula (1):
  • a is the current ratio of the first current source 101 to the second current source 102
  • b is the capacitance ratio of the first capacitor 108 to the second capacitor 109
  • td is the set time of the first charging signal delayed relative to the second charging signal
  • the signal sending unit 1435 is used to control the first switch 103, the second switch 106, the third switch 104, the fourth switch 107 and the fifth switch 105 according to the demagnetization time obtained by the secondary side demagnetization time obtaining unit 1432 and the generation time determined by the sampling pulse generation time determination unit 1434, so that the sampling pulse is generated at the pulse generator 142 at the generation time.
  • the sampling control system 1 is composed of a first current source 101, a second current source 102, a first switch 103, a third switch 104, a fifth switch 105, a second switch 106, a fourth switch 107, a first capacitor 108, a second capacitor 109, a comparator 141, a pulse generator 142 and a timing generator 143, wherein:
  • One end of the first current source 101 and the second current source 102 are connected to the internal power supply VDD, the other end of the first current source 101 is connected to the first switch 103, the other end of the first switch 103 is connected to one end of the third switch 104 and the positive plate of the first capacitor 108, the control end of the first switch 103 is connected to the signal Tons_delay, the other end of the third switch 104 is grounded, the control end of the third switch 104 is connected to the signal SH, the negative plate of the first capacitor 108 is grounded, one end of the fifth switch 105 is connected to the positive plate of the first capacitor 108, the other end of the fifth switch 105 is connected to the positive plate of the second capacitor 109, the control end of the fifth switch 105 is connected to the signal Tons_end, the negative plate of the second capacitor 109 is grounded, one end of the fourth switch 107 is connected to the positive plate of the second capacitor 109, the other end of the fourth switch 107 is grounded, the control end of the fourth switch 107 is connected to the
  • the function of the comparator 141 is to compare the voltages of V1 and V2 in real time when the enable signal Tons is at a high level, and when Tons is at a low level, the comparator output VA is forced to be at a low level.
  • the function of the pulse generator 142 is to convert the rising edge of the output VA of the comparator 141 into a narrow pulse SH with a width of about several hundred nanoseconds.
  • the function of the timing generator is to generate four output signals according to three input signals, among which Tons is the secondary side demagnetization signal, and After a short delay (about tens of nanoseconds), the falling edge begins to flip to a high level. At the end of demagnetization, after Ips (the secondary side demagnetization current peak is the largest) discharges to 0, the FB resonant falling edge is judged as the end of demagnetization.
  • Tons flips to a low level, and Tons is a high level during the entire demagnetization stage;
  • Tons_end is a narrow pulse with a pulse width of about 100ns generated by the falling edge of Tons (that is, the end of demagnetization);
  • PFM_end is a narrow pulse with a pulse width of about 100ns generated by the falling edge of PFM;
  • Tons_delay is a square wave signal that starts from the rising edge of Tons, flips to a high level after 1.6us, and flips to a low level at SH.
  • FIG4 is a waveform diagram of each signal of the sampling control system described in FIG3.
  • PFM is a primary on-off signal.
  • the primary winding is turned on, and FB is clamped at about -0.6V by the internal body diode.
  • the primary current Ipp starts to rise from 0, and the CS voltage rises accordingly.
  • the primary side is shut down, and the transformer current is reflected to the secondary side.
  • the primary current Ipp starts to rise from 0, and the CS voltage rises accordingly.
  • the primary side is shut down, and the transformer current is reflected to the secondary side.
  • the secondary current Ips Nps*Ipp, Nps is the turns ratio between the primary and secondary sides.
  • Tons is proportional to Ips, and thus Tons is also proportional to the primary peak current Ips and the CS peak voltage.
  • the fourth switch 107 is turned off, and then the secondary side demagnetization begins.
  • the second switch 106 is turned on (at this time, the fifth switch 105 and the fourth switch 107 are turned off), and the second current source 102 charges the second capacitor 109.
  • the voltage V2 of the positive plate of the second capacitor 109 rises from 0 with a slope (I/c).
  • V2 rises to a value greater than the positive plate of the first capacitor 108
  • V1 the output of the comparator 141 flips from a low level to a high level, and the pulse generator sends out a sampling narrow pulse SH, which is the sampling pulse of FB.
  • the timing generator After the demagnetization phase begins, that is, after Tons flips from a low level to a high level, the timing generator starts timing 1.6us. After 1.6us, Tons_delay flips to a high level and starts to control the switch 103 to turn on.
  • the first current source 101 charges the first capacitor 108 through the first switch 103.
  • V2 rises from 0V with a slope unit, and the end point of the rise is Vh, while V1 starts at 0.4Vh, maintains 0.4Vh before 1.6us, and starts to rise at a slope unit of 0.6 after 1.6us, pushing the sampling time back. That is, if the demagnetization time Tons is less than 4us, the sampling time is fixed at the moment of 0.4*Tons. When the demagnetization time is greater than 4us, the sampling time is calculated as follows:
  • V1 0.4Vh+(t-1.6us)*0.6 slope units (4)
  • the chip can automatically adjust the sampling time when the primary peak current Ipp changes with the load, so that under any load, the Schottky current and the Schottky voltage drop Vz are equal at the sampling time, thereby achieving a good load regulation rate.
  • the present invention introduces modulation of the sampling time by the CS peak voltage of each cycle.
  • the sampling time varies from 0.4*Tons to 0.8*Tons, so that CS can be arbitrarily varied within the above range.
  • the current of the Schottky is fixed, so that the detected output voltage will not introduce additional errors due to the different forward voltage drops of the Schottky under different currents, thereby ensuring a good load regulation rate.
  • the present invention further provides a controller 100 for controlling the PFM frequency and sampling and holding the feedback terminal FB of the transformer auxiliary winding.
  • the controller 100 includes the sampling control system 1 of the above-mentioned embodiments.
  • the controller 100 further includes an operational amplifier 2, a frequency control unit 3, an RS trigger 4, a driving unit 5 and a cycle-by-cycle current limiting unit 6.
  • the frequency control unit 3 sends an initial pulse frequency modulation signal (PFM signal) to the sampling control system.
  • the sampling control system 1 is used to collect the feedback signal of the feedback end of the primary feedback AC/DC converter.
  • the operational amplifier 2 is used to amplify the difference between the sampling signal (FB_sh) and the reference signal (FB_ref) and output a continuous analog signal.
  • the frequency control unit 3 is used to control the frequency of the pulse frequency modulation signal to change continuously according to the continuous analog signal output by the operational amplifier.
  • the RS trigger 4 is used to send a pulse frequency modulation signal to the driving unit.
  • the driving unit 5 is used to amplify the pulse frequency modulation signal output by the RS trigger, thereby controlling the conduction and shutdown of the primary side of the transformer.
  • the cycle-by-cycle current limiting unit 6 is used to compare the current value (CS) of the primary side of the transformer with the current limiting reference (CS_ref) in each cycle, and perform cycle shutdown when the current value of the primary side of the transformer reaches the current limiting reference.
  • the operational amplifier 2 determines the operating frequency of the controller. The higher the operating frequency, the greater the energy transmitted. When the output voltage is lower than the reference, the operating frequency is increased, the transmission energy is increased, and the output voltage is increased. When the output voltage is higher than the reference, the operating frequency is reduced, the transmission energy is reduced, and the output voltage is reduced.
  • the controller controls the output power of the transformer by adjusting the operating frequency.
  • the controller 100 further comprises a built-in power supply 7 for providing internal power for the holding circuit.
  • the controller of the present invention can accurately implement sampling that changes with CS when the primary peak current changes cycle by cycle.
  • FIG6 is a schematic diagram of a primary-side feedback AC-DC converter according to the present invention.
  • the primary-side feedback AC-DC converter includes a transformer 200 and the controller 100 of the above-mentioned embodiments.
  • the transformer 200 includes a primary winding Np, an auxiliary winding Na and a secondary winding Ns.
  • the polarity of the primary winding is opposite to the same-named ends of the auxiliary winding and the secondary winding.
  • the auxiliary winding is electrically connected to the sampling control system 1 as a feedback end.
  • the primary feedback AC/DC converter further includes a rectifier bridge BR, a rectifier diode D2, a smoothing capacitor Cout, a power tube N1 and a current detection resistor Rcs.
  • the rectifier bridge BR inputs AC power, and the output of the rectifier bridge BR is electrically connected to one end of the primary winding Np of the transformer 200, and the other end of the primary winding Np is electrically connected to the input end of the power tube N1.
  • the control end of the power tube N1 is electrically connected to the controller 100, and the output end of the power tube N1 is electrically connected to the current detection resistor Rcs.
  • the rectifier diode D2 and the smoothing capacitor Cout are connected in series and then connected in parallel to the two ends of the secondary winding Ns of the transformer 200.
  • the transformer 200 further comprises an upper voltage-dividing resistor R1 and a lower voltage-dividing resistor R2 connected in series, the upper voltage-dividing resistor R1 and the lower voltage-dividing resistor R2 are connected in series to an auxiliary winding Na of the transformer 200, and a feedback terminal FB is derived from between the upper voltage-dividing resistor R1 and the lower voltage-dividing resistor R2.
  • the sampling control system of each of the above embodiments is used to sample and control the primary feedback AC/DC converter, and the sampling of the feedback voltage signal of the primary feedback AC/DC converter is controlled.
  • the primary feedback AC/DC converter includes a transformer, and the transformer has a primary winding, a secondary winding, and an auxiliary winding.
  • the feedback voltage signal is a voltage-divided signal of the output voltage of the auxiliary winding, including:
  • the generation time of the sampling pulse is adjusted according to the primary current peak value of the primary winding of the primary feedback AC/DC converter.
  • the step of adjusting the generation time of the sampling pulse according to the primary current peak value of the primary winding of the primary feedback AC/DC converter includes:
  • the generation time of the sampling pulse remains unchanged
  • the demagnetization time is greater than the demagnetization threshold, the time distance between the sampling pulse generation time and the start demagnetization time of the secondary winding increases as the primary current peak value increases.
  • the demagnetization threshold is 4us
  • the initial value of the time distance between the generation time of the sampling pulse and the start time of demagnetization is 0.4*Tons
  • the time distance between the generation time of the sampling pulse and the start time of demagnetization conforms to the following formula (6):
  • t is the time distance between the generation time and the start of demagnetization time
  • Tons is the demagnetization time
  • the primary current peak value varies from 1 times to 3 times
  • the time distance between the generation time of the sampling pulse and the start time of demagnetization varies from 0.4*Tons to 0.8*Tons.

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Abstract

本发明提供采样控制系统、方法、控制器、原边反馈交直流转换器，用于原边反馈交直流转换器，采样控制系统包括充电模块、储能模块、放电模块和控制采样模块，充电模块用于对储能模块充电，放电模块用于对储能模块放电，控制采样模块用于控制充电模块充电、控制放电模块放电以及根据原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，原边电流峰值越小，生成时刻与次边绕组的开始消磁时刻的时间距离越短，控制采样模块还在采样脉冲的采样时间内对变压器的辅助绕组的反馈电压信号进行采样。本发明能在原边峰值电流逐周期变化时，获得更高的采样精度，使得输出电压不会随着原边峰值电流的变化而变化。

Description

采样控制系统、方法、控制器、原边反馈交直流转换器
本申请基于申请号为202310129117.9、申请日为2023年02月16日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本申请作为参考。
技术领域
本发明涉及开关电源技术领域，更具体地，涉及采样控制系统、方法、控制器、原边反馈交直流转换器。
背景技术
原边反馈(PSR)方式的AC—DC控制技术，与传统的副边反馈
开关电源机构结构相比，其最大的优势在于省去了隔离反馈器件，这样就节省了电路板上的空间，降低了成本并且提高了系统的可靠性，
因此广泛应用于中小功率的充电器、适配器和LED驱动。
图1为现有技术的原边反馈交直流(AC-DC)转换器的结构框图，如图1所示，所述原边反馈AC-DC驱动电源包括整流桥BR、输入电容Cin、启动电阻R4、供电整流二极管D1、供电电容C1、上分压电阻R1和下分压电阻R2、控制器、变压器200、功率管N1、电流侦测电阻Rcs、整流二极管D2、输出电容Cout；其中,所述变压器包括原边绕组Np、辅助绕组Na以及次级绕组Ns；上分压电阻R1和下分压电阻R2构成取样电路，所述FB引脚为变压器的辅助绕组Na电压反馈引入脚，并从上分压电阻R1和下分压电阻R2构成取样电路中取得信号。在控制器内部，FB引脚经采样控制电路保持并控制工作频率。当功率管导通时，变压器原边导通，变压器储能，由于变压器原边绕组Np的极性相对辅助绕组Na和次级绕组Ns同名端相反，因此在原边导通时，FB引脚为负电压；当功率管关断系统处于消磁阶段，变压器次边释放能量，由于辅助绕组Na与次级绕组Ns同名端极性相同，因此FB电压为正电压，此时变压器次级绕组电压为Vs＝Vo+Vz，其中，Vo为变压器的输出电压，Vz为整流二极管D2的压降，辅助绕组电压Va＝Vs×(NA/NS)＝VFB×R2/(R1+R2),因此Vo＝VFB×R2×NS/[(R1+R2)*NA]-Vz，其中，NA为辅助绕组的匝数，NS为次级绕组的匝数，VFB为辅助绕组Na的反馈电压，也就是输出电压是反馈电压VFB的函数，控制器通过采样此时的VFB电压，与基准电压相比较，用于控制开关频率，使得输出电压Vo稳定在设定值；消磁阶段次边电流随时间下降，当下降到0时，次边消磁结束，此时如果原边功率管N1没有再次导通，则反馈电压信号FB进入谐振，将次级绕组的消磁时间记为Tons。
为了精确侦测输出电压，FB电压采样就显得十分重要。由于次边消磁阶段，次边电力流过肖特基会产生压降Vz，Vz正向压降随着电流减小而减小，因此尽量在消磁接近结束时来采样，可以使Vz尽量小，从而所侦测到的输出电压Vo尽量接近真实的输出电压。传统的做法一般是先侦测上一个周期的消磁时间Tons(n-1)，然后本周期消磁时取上个周期消磁时间的2/3来作为采样时间，早期的PSR反激控制器一般采用CS(Current Sense,原边电流)峰值固定的方案，这样，相邻的两个周期CS峰值基本相等，相邻两个周期的消磁时间也基本相等，取上个周期消磁时间的2/3来作为本周期的采样时间并无不妥。但是为了获得更高的能效，现在的PSR反激控制器，其CS峰值不在固定，而是随负载变化而变化，负载越轻，CS峰值越小，也就是次边消磁电流越小。比如在满载时CS峰值最大，次边绕组的消磁电流峰值最大，记为Ips，那么在Tons的2/3时间采样，此时肖特基电流为0.33Ips；当轻载时CS峰值降到最大值的1/3，那么次边消磁电流的峰值只有0.33Ips，如果仍然在Tons的2/3时间采样，那么采样时肖特基电流为0.11Ips，由于0.33Ips和0.11Ips的电流，会使肖特基压降有较大差距，轻载下采样时肖特基电流小，正向压降Vz也小，侦测采样到的VFB也偏小，环路要使侦测电压等于内部参考电压，就会增大频率，使输出电压升高，因此，固定Tons比例采样会导致不同CS(即不同负载下，因为CS是随负载变化的)下，输出电压因为肖特基压降不同而导致差异，负载越轻，输出电压越高，使负载调整率变得更差。。
发明内容
针对现有技术存在问题中的一个或多个，本发明提供一种采样控制系统，用于原边反馈交直流转换器，所述原边反馈交直流转换器包括变压器，所述变压器具有原边绕组、次边绕组和辅助绕组，所述采样控制系统包括充电模块、储能模块、放电模块和控制采样模块，所述充电模块用于对所述储能模块充电，所述放电模块用于对所述储能模块放电，所述控制采样模块用于控制充电模块充电、控制放电模块放电以及根据所述原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，所述原边电流峰值越小，所述生成时刻与所述次边绕组的开始消磁时刻的时间距离越短，所述控制采样模块还在采样脉冲的采样时间内对变压器的辅助绕组的反馈电压信号进行采样。
根据本发明的一个方面，所述充电模块包括第一充电单元、第二充电单元和第三充电单元；所述储能模块包括第一储能元件和第二储能元件；所述放电模块包括第一放电单元和第二放电单元；
其中，所述第一充电单元用于对第一储能元件充电，所述第二充电单元用于对第二储能元件充电，所述第三充电单元用于控制第二储 能元件对第一储能元件的充电，所述第一放电单元用于对第一储能元件放电，所述第二放电单元用于对第二储能元件放电。
根据本发明的一个方面，所述第一充电单元包括第一电流源和第一开关；所述第二充电单元包括第二电流源和第二开关；所述第三充电单元包括第五开关；所述第一储能元件包括第一电容；所述第二储能元件包括第二电容；所述第一放电单元包括第三开关；所述第二放电单元包括第四开关；
其中，所述第一电流源通过第一开关与第一电容的正极板电连接，第一电容的负极板接地，所述第二电流源通过第二开关与第二电容的正极板电连接，第二电容的负极板接地，所述第三开关与第一电容的正极板电连接，所述第四开关与所述第二电容的正极板电连接，所述第五开关电连接在第一电容的正极板和第二电容的正极板之间。
根据本发明的一个方面，所述控制采样模块包括比较器、脉冲发生器和时序发生器，所述比较器的正向输入为第二储能元件的输出电压，所述比较器的负向输入为第一储能元件的输出电压，所述比较器的输出端与所述脉冲发生器的输入端电连接，所述时序发生器采集变压器的原边通断信号，原边绕组导通时，原边通断信号为高电平，原边绕组截止时，原边通断信号为低电平，原边通断信号由高电平转换为低电平时，时序发生器发送放电信号给第二放电单元，第二放电单元对第二储能元件放电，第二储能元件放电结束，变压器的次边绕组的次边消磁开始，时序发生器发送第二充电信号给第二充电单元，第二充电单元对第二储能元件充电，时序发生器相对于发送第二充电信号延迟设定时间发送第一充电信号给第一充电单元，第一充电单元对第一储能元件充电，当第二储能元件的输出电压等于第一储能元件的输出电压时，第一充电单元对第一储能元件充电结束，比较器触发脉冲发生器，脉冲发生器生成采样脉冲给时序发生器同时将采样脉冲作为放电信号发送给第一放电单元，时序发生器收到脉冲发生器发送的采样信号对变压器的辅助绕组的反馈电压信号进行采样，次边消磁结束，时序发生器发送充电信号给第三充电单元，第二储能元件对第一储能元件充电。
根据本发明的一个方面，所述充电模块包括第一充电单元、第二充电单元和第三充电单元，所述第一充电单元包括第一电流源和第一开关，所述第二充电单元包括第二电流源和第二开关，所述第三充电单元包括第五开关；所述储能模块包括第一储能元件和第二储能元件，所述第一储能元件包括第一电容，所述第二储能元件包括第二电容；所述放电模块包括第一放电单元和第二放电单元，所述第一放电单元包括第三开关，所述第二放电单元包括第四开关；所述控制采样模块包括比较器、脉冲发生器和时序发生器；其中，所述第一电流源通过 第一开关与第一电容的正极板电连接，第一电容的负极板接地，所述第二电流源通过第二开关与第二电容的正极板电连接，第二电容的负极板接地，所述第三开关与第一电容的正极板电连接，所述第四开关与所述第二电容的正极板电连接，所述第五开关电连接在第一电容和第二电容的正电极之间，所述比较器的正向输入端与第二电容的正极板电连接，所述比较器的负向输入端与第一电容的正极板连接，所述比较器的输出端与所述脉冲发生器的输入端连接，所述脉冲发生器的输出端与所述时序发生器电连接，所述时序发生器采集变压器的原边通断信号，原边绕组导通时，原边通断信号为高电平，原边绕组截止时，原边通断信号为低电平，原边通断信号由高电平转换为低电平时，时序发生器发送放电信号给第四开关，第四开关导通，第二电容放电，第二电容的输出电压为0V时，第四开关断开，时序发生器发送第二充电信号给第二开关，第二开关导通，第二电流源对第二电容充电，时序发生器相对于发送第二充电信号延迟设定时间发送第一充电信号给第一开关，第一开关导通，第一电流源对第一电容充电，当第二电容的输出电压等于第一电容的输出电压时，第一开关断开，比较器触发脉冲发生器，脉冲发生器生成采样脉冲给时序发生器，时序发生器对变压器的反馈电压信号进行采样，同时脉冲发生器将采样脉冲作为放电信号发送给第三开关，第三开关导通，第一电容放电，第一电容输出电压为0V，变压器的次边绕组消磁结束时，时序发生器发送充电信号给第五开关，第五开关导通，第二电容对第一电容充电。
根据本发明的一个方面，所述时序发生器包括次边消磁时间获得单元、判断单元、采样脉冲生成时刻确定单元、信号采集单元和信号发送单元，其中：
所述信号采集单元用于采集原边通断信号和反馈电压信号；
所述次边消磁时间获得单元用于根据信号采集单元采集的原边电流峰值得到次边消磁时间；
所述判断单元用于判断次边消磁时间获得单元得到的消磁时间是否不大于消磁阈值；
所述采样脉冲生成时刻确定单元用于根据所述判断单元的判断结果确定采样脉冲的生成时刻，当判断单元的判断结果为消磁时间不大于消磁阈值时，所述生成时刻与开始消磁时刻的距离t为其中，c1为第一电容的电容值，c2为第二电容的电容值，Tons为消磁时间；当判断单元的判断结果为消磁时间大于消磁阈值时，所述生成时刻与开始消磁时刻的距离t符合下式：
其中，a为第一电流源和第二电流源的电流比值，b为第一电容与 第二电容的电容比值，td为第一充电信号相对于第二充电信号延迟的设定时间；
所述信号发送单元用于根据次边消磁时间获得单元得到的消磁时间和采样脉冲生成时刻确定单元确定的生成时刻控制第一开关、第二开关、第三开关、第四开关和第五开关，以使得在所述脉冲发生器在所述生成时刻生成采样脉冲。
根据本发明的一个方面，第一电流源的电流值是第二电流源的电流值的0.9倍，使得第二电容的电压上升斜率是第一电容的电压上升斜率的0.6倍，最终要实现采样时间t，两个电流源的电流值越接近，匹配度越高，两个电流源的电流值差距越大，失配的可能性越大。
根据本发明的一个方面，所述第一电容的电容值是第二电容的电容值的1.5倍，第一电容和第二电容的电容值越接近，匹配度越高，使得第二电容的电压上升斜率是第一电容的电压上升斜率的0.6倍，最终要实现采样时间t。
根据本发明的一个方面，所述消磁阈值为4us，4us主要是针对目前行业内量产的真实PSR电源系统，最小消磁时间一般取在3-5us之间，所以所述消磁阈值为4us，消磁阈值小于3us，太小会出现因为谐振带来的干扰。
根据本发明的一个方面，所述第一充电信号相对于第二充电信号延迟的设定时间为1.6us，通常的系统设计，谐振可能带来干扰时间一般在1us左右；所以芯片一般会在1-2.5us的时间内来禁止采样，以防止谐振干扰，1.6us是个合适的中间值；同时1.6us为本发明消磁阈值的40％，满足采样时间在0.4*Tons—0.8*Tons之间。
根据本发明的另一个方面，提供一种采样控制方法，用于控制原边反馈交直流转换器的反馈电压信号的采样，所述原边反馈交直流转换器包括变压器，所述变压器具有原边绕组、次边绕组和辅助绕组，所述反馈电压信号为辅助绕组的输出电压的分压信号，包括：根据原边反馈交直流转换器的原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，所述原边电流峰值越小，所述生成时刻与所述次边绕组的开始消磁时刻距离越短。
根据本发明的另一个方面，所述根据原边反馈交直流转换器的原边绕组的原边电流峰值大小调整采样脉冲的生成时刻的步骤包括：
根据原边电流峰值获得次边绕组的消磁时间；
判断上述消磁时间是否不大于消磁阈值；
如果消磁时间不大于消磁阈值，所述采样脉冲的生成时刻不变；
如果消磁时间大于消磁阈值，所述采样脉冲生成时刻与次边绕组
的开始消磁时刻的时间距离随着原边电流峰值增大而增大。
根据本发明的另一个方面，所述消磁阈值为4us，所述采样脉冲
的生成时刻与开始消磁时刻的时间距离的初始值为0.4*Tons，所述采样脉冲的生成时刻与开始消磁时刻的时间距离符合下式：
其中，t为生成时刻与开始消磁时刻的时间距离，Tons为消磁时间。
根据本发明的另一个方面，所述原边电流峰值从1倍到3倍的范围内变化，所述采样脉冲的生成时刻与开始消磁时刻的时间距离对应的在0.4*Tons到0.8*Tons范围内变化。
根据本发明的第三方面，提供一种控制器，包括上述采样控制系统。
根据本发明的第四方面，提供一种原边反馈交直流转换器，包括变压器和上述控制器。
本发明采用控制系统及方法采用随CS峰值变化的采样方法，CS峰值越大，采样时间越靠后，CS峰值越小，采样时间越靠前，在CS峰值变从1倍到3倍的变化范围内，采样时间从0.4*Tons变化到0.8*Tons，使得CS在上述范围内任意变化，采样时肖特基的电流都是固定的，从而使得侦测输出电压不会因为肖特基在不同电流下的正向压降不同，而引入额外误差，保证良好的负载调整率。
附图说明
通过参考以下具体实施方式内容并且结合附图，本发明的其它目的及结果将更加明白且易于理解。在附图中：
图1是现有技术的原边反馈交直流转换器的结构框图；
图2是本发明所述采样控制系统的一个实施例的构成框图示意图；
图3是本发明所述采样控制系统的一个实施例的电路示意图；
图4是本发明所述采样控制系统的各信号的波形示意图；
图5是本发明所述采样控制系统的针对不同原边电流峰值采样的波形示意图；
图6是本发明所述原边反馈交直流转换器的示意图；
其中，1-采样控制系统，11-充电模块，111-第一充电单元，101-
第一电流源，103-第一开关，112-第二充电单元，102-第二电流源，106-第二开关，113-第三充电单元，105-第五开关，12-储能模块，121-第一储能元件，108-第一电容，122-第二储能元件，109-第二电容，13-放电模块，131-第一放电单元，104第三开关，132-第二放电单元，107-第四开关，14-控制采样模块，141-比较器，142-脉冲发生器，143-时序发生器，1431-信号采集单元，1432-次边消磁时间获得单元，1433-判断单元，1434-采样脉冲生成时刻确定单元，1435-信号 发送单元；2-运算放大器；3-频率控制单元；4-RS触发器；5-驱动单元；6-逐周期限流单元，7-内建电源；100-控制器；200-变压器。
具体实施方式
在下面的描述中，出于说明的目的，为了提供对一个或多个实施
例的全面理解，阐述了许多具体细节。然而，很明显，也可以在没有
这些具体细节的情况下实现这些实施例。
下面将参照附图来对根据本发明的各个实施例进行详细描述。
图2是本发明所述采样控制系统的一个实施例的构成框图示意图，如图2所示，所述采样控制系统1用于原边反馈交直流转换器，所述原边反馈交直流转换器包括变压器，所述变压器具有原边绕组、次边绕组和辅助绕组，根据变压器原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，实现在原边峰值电流逐周期变化时，使得输出电压不会随着原边峰值电流的变化而变化。本发明所述采样控制系统1包括充电模块11、储能模块12、放电模块13和控制采样模块14，所述充电模块11用于对所述储能模块12的充电，所述放电模块13用于对所述储能模块12放电，所述控制采样模块14用于控制充电模块11充电、控制放电模块13放电以及根据所述原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，所述原边电流峰值越小，所述生成时刻与所述次边绕组的开始消磁时刻的时间距离越短，所述控制采样模块14还在采样脉冲的采样时间内对变压器的辅助绕组的反馈电压信号进行采样。
在一个实施例中，如图2所示，所述充电模块11包括第一充电单元111、第二充电单元112和第三充电单元113；所述储能模块12包括第一储能元件121和第二储能元件122；所述放电模块13包括第一放电单元131和第二放电单元132；
其中，所述第一充电单元111用于对第一储能元件121充电，所述第二充电单元112用于对第二储能元件122充电，所述第三充电单元113用于控制第二储能元件122对第一储能元件121的充电，所述第一放电单元131用于对第一储能元件121放电，所述第二放电单元132用于对第二储能元件122放电。
在一个实施例中，如图2和图3所示，所述第一充电单元111包括第一电流源101和第一开关103；所述第二充电单元112包括第二电流源102和第二开关106；所述第三充电单元113包括第五开关105；所述第一储能元件121包括第一电容108；所述第二储能元件122包括第二电容109；所述第一放电单元131包括第三开关104；所述第二放电单元132包括第四开关107；
其中，所述第一电流源101通过第一开关103与第一电容108的 正极板电连接，第一电容108的负极板接地，所述第二电流源102通过第二开关106与第二电容109的正极板电连接，第二电容109的负极板接地，所述第三开关104与第一电容108的正极板电连接，所述第四开关107与所述第二电容109的正极板电连接，所述第五开关105电连接在第一电容108的正极板和第二电容109的正极板之间。
在一个实施例中，如图2所示，所述控制采样模块14包括比较器141、脉冲发生器142和时序发生器143，所述比较器141的正向输入为第二储能元件122的输出电压，所述比较器141的负向输入为第一储能元件121的输出电压，所述比较器141的输出端与所述脉冲发生器142的输入端电连接，所述时序发生器143采集变压器的原边通断信号，原边绕组导通时，原边通断信号为高电平，原边绕组截止时，原边通断信号为低电平，原边通断信号由高电平转换为低电平时，时序发生器143发送放电信号给第二放电单元132，第二放电单元132对第二储能元件122放电，第二储能元件122放电结束，变压器的次边绕组的次边消磁开始，时序发生器143发送第二充电信号给第二充电单元112，第二充电单元112对第二储能元件122充电，时序发生器143相对于发送第二充电信号延迟设定时间发送第一充电信号给第一充电单元111，第一充电单元111对第一储能元件121充电，当第二储能元件122的输出电压等于第一储能元件121的输出电压时，第一充电单元111对第一储能元件121充电结束，比较器141触发脉冲发生器142，脉冲发生器142生成采样脉冲给时序发生器143同时将采样脉冲作为放电信号发送给第一放电单元131，时序发生器143收到脉冲发生器142发送的采样信号对变压器的辅助绕组的反馈电压信号进行采样，次边消磁结束，时序发生器143发送充电信号给第三充电单元113，第二储能元件122对第一储能元件121充电。
在一个实施例中，如图2和图3所示，所述充电模块11包括第一充电单元111、第二充电单元112和第三充电单元113，所述第一充电单元111包括第一电流源101和第一开关103，所述第二充电单元112包括第二电流源102和第二开关106，所述第三充电单元113包括第五开关105；所述储能模块12包括第一储能元件121和第二储能元件122，所述第一储能元件121包括第一电容108，所述第二储能元件122包括第二电容109；所述放电模块13包括第一放电单元131和第二放电单元132，所述第一放电单元131包括第三开关104，所述第二放电单元132包括第四开关107；所述控制采样模块14包括比较器141、脉冲发生器142和时序发生器143；
其中，所述第一电流源101通过第一开关103与第一电容108的正极板电连接，第一电容108的负极板接地，所述第二电流源102通过第二开关106与第二电容109的正极板电连接，第二电容109的负 极板接地，所述第三开关104与第一电容108的正极板电连接，所述第四开关107与所述第二电容109的正极板电连接，所述第五开关105电连接在第一电容108和第二电容109的正电极之间，所述比较器141的正向输入端与第二电容109的正极板电连接，所述比较器141的负向输入端与第一电容108的正极板连接，所述比较器141的输出端与所述脉冲发生器142的输入端连接，所述脉冲发生器142的输出端与所述时序发生器143电连接，所述时序发生器143采集变压器的原边通断信号，原边绕组导通时，原边通断信号为高电平，原边绕组截止时，原边通断信号为低电平，原边通断信号由高电平转换为低电平时，时序发生器143发送放电信号给第四开关107，第四开关107导通，第二电容109放电，第二电容109的输出电压为0V时，第四开关107断开，时序发生器143发送第二充电信号给第二开关106，第二开关106导通，第二电流源102对第二电容109充电，时序发生器143相对于发送第二充电信号延迟设定时间发送第一充电信号给第一开关103，第一开关103导通，第一电流源101对第一电容108充电，当第二电容109的输出电压等于第一电容108的输出电压时，第一开关103断开，比较器141触发脉冲发生器142，脉冲发生器142生成采样脉冲给时序发生器143，时序发生器143对变压器的反馈电压信号进行采样，同时脉冲发生器142将采样脉冲作为放电信号发送给第三开关104，第三开关104导通，第一电容108放电，第一电容108输出电压为0V，变压器的次边绕组消磁结束时，时序发生器143发送充电信号给第五开关105，第五开关105导通，第二电容109对第一电容108充电。
在一个实施例中，如图2所示，所述时序发生器143包括次边消磁时间获得单元1432、判断单元1433、采样脉冲生成时刻确定单元1434、信号采集单元1431和信号发送单元1435，其中：
所述信号采集单元1431用于采集原边通断信号和反馈电压信号；
所述次边消磁时间获得单元1432用于根据信号采集单元1431采集的原边电流峰值得到次边消磁时间；
所述判断单元1433用于判断次边消磁时间获得单元1432得到的消磁时间是否不大于消磁阈值；
所述采样脉冲生成时刻确定单元1434用于根据所述判断单元1433的判断结果确定采样脉冲的生成时刻，当判断单元1433的判断结果为消磁时间不大于消磁阈值时，所述生成时刻与开始消磁时刻的距离t为其中，c1为第一电容108的电容值，c2为第二电容109的电容值，Tons为消磁时间；当判断单元1433的判断结果为消磁时间大于消磁阈值时，所述生成时刻与开始消磁时刻的距离t符合下式(1)：
其中，a为第一电流源101和第二电流源102的电流比值，b为第一电容108与第二电容109的电容比值，td为第一充电信号相对于第二充电信号延迟的设定时间；
所述信号发送单元1435用于根据次边消磁时间获得单元1432得到的消磁时间和采样脉冲生成时刻确定单元1434确定的生成时刻控制第一开关103、第二开关106、第三开关104、第四开关107和第五开关105，以使得在所述脉冲发生器142在所述生成时刻生成采样脉冲。
在一个优选实施例中，如图3所示，所述采样控制系统1由第一电流源101、第二电流源102，第一开关103、第三开关104、第五开关105、第二开关106、第四开关107，第一电容108、第二电容109、比较器141，脉冲发生器142和时序发生器143组成，其中，
第一电流源101和第二电流源102一端连接内部电源VDD，第一电流源101的另一端连接第一开关103,第一开关103的另一端连接第三开关104的一端和第一电容108的正极板，第一开关103的控制端连接信号Tons_delay，第三开关104的另一端接地，第三开关104的控制端接信号SH，第一电容108的负极板接地，第五开关105的一端连接第一电容108的正极板，第五开关105的另一端接第二电容109的正极板，第五开关105的控制端接信号Tons_end，第二电容109的负极板接地，第四开关107的一端连接第二电容109的正极板，第四开关107的另一端接地，第四开关107的控制端接信号PF_end，第二开关106的一端连接第二电容109的正极板，第二开关106的另一端接第二电流源102的另一端，第二开关106的控制端接信号Tons，比较器141的正向输入端接第二电容109的正极板信号V2，比较器141的负向输入端接第一电容108的正极板信号V1，比较器141的输出连接脉冲发生器142的输入，脉冲发生器142的输出端为脉冲采样信号SH，用于FB电压的采样，同时作为时序发生器的输出；时序发生器的两个输入端分别连接信号PFM(原边通断信号)和FB(反馈电压信号)，并产生四个输出信号Tons(次边消磁信号)、Tons_end(消磁结束信号)、PFM_end(原边断开信号)和Tons_delay(消磁延时信号)，用于控制上述几个开关的通断。
比较器141的作用是在使能信号Tons为高电平时，实时比较V1和V2的电压，在Tons为低电平时，比较器输出VA被强制为低电平。
脉冲发生器142的作用是将比较器141的输出VA的上升沿转化为一个宽度约几百纳秒的窄脉冲SH。时序发生器的作用是根据三个输入信号，产生四个输出信号，其中Tons为次边消磁信号，从PFM 下降沿经过短暂延时(约几十纳秒)开始翻转为高电平，在消磁结束，Ips(次边消磁电流峰值最大)放电到0后，FB谐振下降沿判断为消磁结束，此时Tons翻转为低电平，整个消磁阶段Tons为高电平；Tons_end是由Tons下降沿(即消磁结束时刻)产生的一个脉宽约100ns的窄脉冲；PFM_end是由PFM下降沿产生的一个脉宽约100ns的窄脉冲；Tons_delay是从Tons上升沿开始计时，1.6us之后翻转为高电平，SH时刻翻转为低电平的一个方波信号。
图4是图3所述采样控制系统的各信号的波形示意图，如图4所示，PFM是原边通断信号，PFM为高电平时原边绕组导通，FB被内部体二极管钳位在-0.6V附近，原边电流Ipp从0开始上升，CS电压随之上升，当CS电压上升到逐周期关断阈值时，原边关断，变压器电流反射到次边，原边电流Ipp从0开始上升，CS电压随之上升，当CS电压上升到逐周期关断阈值时，原边关断，变压器电流反射到次边，次边电流Ips＝Nps*Ipp，Nps为原边与次边的匝比，此时次边消磁开始，输出电压Vo＝VFB×R2×NS/[(R1+R2)*NA]‐Vz，次边消磁时间信号Tons为高电平，Tons＝(Ips*Ls)/(Vo+Vz)，在系统稳定工作时，输出电压固定等于设定值，变压器次边感量LS也是定值，因此Tons和Ips成正比，因而Tons也和原边峰值电流Ips以及CS峰值电压成正比。每个周期原边导通结束时，PFM_end窄脉冲信号控制第四开关107导通(此时第五开关105和第二开关106关断)将第二电容109正极板放电到0，即V2＝0V，窄脉冲过后开关第四开关107关断，然后次边消磁开始，Tons为高电平阶段第二开关106导通(此时第五开关105和第四开关107关断)，第二电流源102给第二电容109充电，第二电容109正极板电压V2从0开始以斜率(I/c)上升，这里将(I/c)记为一个斜率单位，即K＝1，当V2上升到大于第一电容108正极板电压V1时，比较器141的输出从低电平翻转为高电平，脉冲发生器发出采样窄脉冲SH，SH就是FB的采样脉冲，通过采样FB来侦测输出电压Vo，同时SH控制第三开关104导通，将第一电容108的正极板放电到0，即V1＝0V，然后SH窄脉冲结束，第三开关104关断，V1维持0V，而V2继续上升，直到Ips下降到0，消磁结束，Tons变为低电平，第二开关106关断，第二电容109充电结束，其电压V2max＝(I/c)*Tons＝Tons*1个斜率单位，记为V2max＝Vh。消磁阶段Tons结束后，Tons_edn窄脉冲控制第五开关105导通(此时其他开关全部处于关断状态)，第一电容108和第二电容109形成并联关系，由于并联之前V1＝0，并联之后 个斜率单位，也就是V1＝V2＝0.4Vh，Tons_end窄脉冲结束后开关105关断，此时第一开关103和第三开关104也关断，因 此V1维持0.4Vh不变，并作为下个消磁阶段的采样判断基准，由于相邻两个周期CS峰值基本不变，因此Tons也相等，因此下个周期的采样时间就是在0.4*Tons时刻。
在消磁阶段开始后，即Tons从低电平翻转为高电平后，时序发生器开始计时1.6us，1.6us之后Tons_delay翻转为高电平，并开始控制开关103导通，第一电流源101通过第一开关103给第一电容108充电，电压V1上升斜率为(0.9*I)/(1.5*c)＝0.6*(I/c)，＝0.6个斜率单位，这样在Tons开始时，V2从0V为起点以一个斜率单位上升，且上升终点为Vh，而V1以0.4Vh为起点，在1.6us之前维持0.4Vh，1.6us之后开始以0.6个斜率单位上升，将采样时间往后推。即，如果消磁时间Tons＜4us，那么采样时间固定在0.4*Tons时刻，当消磁时间＞4us之后，采样时间计算如下：
V2＝t*1个斜率单位     (2)
Vh＝Tons*1个斜率单位     (3)
V1＝0.4Vh+(t‐1.6us)*0.6个斜率单位    (4)
当V2＝V1时刻为t       (5)
由公式(2)、(3)、(4)和(5)求得
t＝Tons‐2.4us
也就是本发明将采样时刻固定在两个位置，如果消磁时间Tons＜4us，那么采样时刻固定在0.4*Tons时刻，如果消磁时间Tons＞4us，那么采样时刻固定在(Tons‐2.4us)时刻，这样的话由于消磁阶段Ips下降速度是固定的，且在Tons结束时下降到0，那么在(Tons‐2.4us)时刻，Ips是一个固定值，Ips＝(Vo+Vz)*2.4us/Ls，采样时刻离消磁结束的间隔是2.4us，消磁结束电流是＝0的，那么2.4us乘以电流下降斜率，就是采样时刻的肖特基电流值，那么也就是当Tons＞4us之后，SH采样时刻对应的肖特基电流永远固定于Ips＝(Vo+Vz)*.2.4us/Ls，那么此刻肖特基压降Vz也就用于固定于一个定值，不会随Tons变化，即，采样时刻Vz不会随CS变化，那么在任意负载和CS峰值电压下，Vz都不会因为带来额外误差，从而使得输出电压Vo保持良好的负载调整率。如果在系统设计时，调整好变压器参数，使得轻载即CS峰值最小的时候，消磁时间等于4us附近，那么在整个CS变化范围内，也就是任意负载下，任意CS峰值下，采样的时刻所对应的肖特基电流都相等，可以实现最优性能。图5显示了在这个最优设计下，CS1为最大CS峰值，当CS峰值为最小值(1/3)*CS1时，消磁时间为4us，采样在0.4*Tons，即1.6us处；当CS峰值为最小值的两倍(2/3)*CS1时，消磁时间为8us，采样在0.7*Tons，即5.6us处；当CS峰值为最小值的三倍1*CS1时，消磁时间为12us，采样在0.8*Tons，即9.6us处；从图4可以看出，三个峰值下的采样时刻对应的肖特基电 流Ips完全相等。
通过以上发明，芯片可以在原边峰值电流Ipp随负载变化时，自动调节采样时间，使得任意负载下，采样时刻肖特基的电流都相等，肖特基的压降Vz也都相等，从而实现良好的负载调整率。
本发明通过引入每个周期CS峰值电压对采样时间的调制，CS越大，采样时间越靠后，CS越小，采样时间越靠前，在CS峰值变从1倍到3倍的变化范围内，采样时间从0.4*Tons变化到0.8*Tons，使得CS在上述范围内任意变化，采样时肖特基的电流都是固定的，从而使得侦测输出电压不会因为肖特基在不同电流下的正向压降不同，而引入额外误差，保证良好的负载调整率。
如图6所示，本发明还提供控制器100，用于控制PFM频率并对变压器辅助绕线组的反馈端FB采样保持，控制器100包括上述各实施例的采样控制系统1。
如图6所示，控制器100还包括运算放大器2、频率控制单元3、RS触发器4、驱动单元5和逐周期限流单元6，所述频率控制单元3发送初始脉冲频率调制信号(PFM信号)给采样控制系统，所述采样控制系统1用于采集原边反馈交直流转换器的反馈端的反馈信号，所述运算放大器2用于放大采样信号(FB_sh)和基准信号(FB_ref)之差，输出连续模拟信号；所述频率控制单元3用于根据运算放大器输出的连续模拟信号控制脉冲频率调制信号的频率连续变化；所述RS触发器4用于向驱动单元发送脉冲频率调制信号；所述驱动单元5用于放大所述RS触发器输出的脉冲频率调制信号，从而控制变压器原边的导通和关闭；所述逐周期限流单元6用于在每个周期比较变压器原边的电流值(CS)和限流基准(CS_ref)，当变压器原边的电流值达到限流基准时，进行周期关断。
上述运算放大器2决定控制器的工作频率，工作频率越高，传输的能量越大，当输出电压比基准低时，提高工作频率，增大传输能量，提高输出电压，当输出电压比基准高时，降低工作频率，减少传输能量，降低输出电压；控制器通过调节工作频率来控制变压器的输出功率。
优选地，所述控制器100还包括内建电源7，为采用保持电路提供内部电源。
本发明所述控制器可以精确地实现在原边峰值电流逐周期变化时，随CS变化的采样，CS越大，采样时间越靠后，CS越小，采样时间越靠前，使得输出电压不会随着原边峰值电流的变化而变化。
图6是本发明所述原边反馈交直流转换器的示意图，如图6所示，所述原边反馈交直流转换器包括变压器200和上述各实施例的控制器100。
如图6所示，所述变压器200包括原边绕组Np、辅助绕组Na和次级绕组Ns，所述原边绕组的极性相对辅助绕组和次级绕组同名端相反，所述辅助绕组作为反馈端与采样控制系统1电连接。
如图6所示，所述原边反馈交直流转换器还包括整流桥BR、整流二极管D2、平滑电容Cout、功率管N1和电流侦测电阻Rcs，所述整流桥BR输入交流电，所述整流桥BR的输出与变压器200的原边绕组Np的一端电连接，原边绕组Np的另一端与功率管N1的输入端电连接，功率管N1的控制端与控制器100电连接，功率管N1的输出端与电流侦测电阻Rcs电连接，所述整流二极管D2和平滑电容Cout串联后并联在变压器200的次级绕组Ns两端。
优选地，所述变压器200还包括串联的上分压电阻R1和下分压电阻R2，上分压电阻R1和下分压电阻R2串联在变压器200的辅助绕组Na，从上分压电阻R1和下分压电阻R2之间引出反馈端FB。
在一个实施例中，利用上述各实施例的采样控制系统对原边反馈交直流转换器采样控制，控制原边反馈交直流转换器的反馈电压信号的采样，所述原边反馈交直流转换器包括变压器，所述变压器具有原边绕组、次边绕组和辅助绕组，所述反馈电压信号为辅助绕组的输出电压的分压信号，包括：
根据原边反馈交直流转换器的原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，所述原边电流峰值越小，所述生成时刻与所述次边绕组的开始消磁时刻距离越短。
在一个实施例中，所述根据原边反馈交直流转换器的原边绕组的原边电流峰值大小调整采样脉冲的生成时刻的步骤包括：
根据原边电流峰值获得次边绕组的消磁时间；
判断上述消磁时间是否不大于消磁阈值；
如果消磁时间不大于消磁阈值，所述采样脉冲的生成时刻不变；
如果消磁时间大于消磁阈值，所述采样脉冲生成时刻与次边绕组的开始消磁时刻的时间距离随着原边电流峰值增大而增大。
在一个实施例中，所述消磁阈值为4us，所述采样脉冲的生成时刻与开始消磁时刻的时间距离的初始值为0.4*Tons，所述采样脉冲的生成时刻与开始消磁时刻的时间距离符合下式(6)：
其中，t为生成时刻与开始消磁时刻的时间距离，Tons为消磁时间。
根据本发明的另一个方面，所述原边电流峰值从1倍到3倍的范围内变化，所述采样脉冲的生成时刻与开始消磁时刻的时间距离对应的在0.4*Tons到0.8*Tons范围内变化。
尽管前面公开的内容示出了本发明的示例性实施例，但是应当注意，在不背离权利要求限定的范围的前提下，可以进行多种改变和修改。此外，尽管本发明的元素可以以个体形式描述或要求，但是也可以设想具有多个元素，除非明确限制为单个元素。

Claims (15)

  1. 一种采样控制系统，用于原边反馈交直流转换器，所述原边反馈交直流转换器包括变压器，所述变压器具有原边绕组、次边绕组和辅助绕组，其特征在于，所述采样控制系统包括充电模块、储能模块、放电模块和控制采样模块，所述充电模块用于对所述储能模块充电，所述放电模块用于对所述储能模块放电，所述控制采样模块用于控制充电模块充电、控制放电模块放电以及根据所述原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，所述原边电流峰值越小，所述生成时刻与所述次边绕组的开始消磁时刻的时间距离越短，所述控制采样模块还在采样脉冲的采样时间内对变压器的辅助绕组的反馈电压信号进行采样。
  2. 根据权利要求1所述的采样控制系统，其特征在于，所述充电模块包括第一充电单元、第二充电单元和第三充电单元；所述储能模块包括第一储能元件和第二储能元件；所述放电模块包括第一放电单元和第二放电单元；
    其中，所述第一充电单元用于对第一储能元件充电，所述第二充电单元用于对第二储能元件充电，所述第三充电单元用于控制第二储能元件对第一储能元件的充电，所述第一放电单元用于对第一储能元件放电，所述第二放电单元用于对第二储能元件放电。
  3. 根据权利要求2所述的采样控制系统，其特征在于，所述第一充电单元包括第一电流源和第一开关；所述第二充电单元包括第二电流源和第二开关；所述第三充电单元包括第五开关；所述第一储能元件包括第一电容；所述第二储能元件包括第二电容；所述第一放电单元包括第三开关；所述第二放电单元包括第四开关；
    其中，所述第一电流源通过第一开关与第一电容的正极板电连接，第一电容的负极板接地，所述第二电流源通过第二开关与第二电容的正极板电连接，第二电容的负极板接地，所述第三开关与第一电容的正极板电连接，所述第四开关与所述第二电容的正极板电连接，所述第五开关电连接在第一电容的正极板和第二电容的正极板之间。
  4. 根据权利要求2所述的采样控制系统，其特征在于，所述控制采样模块包括比较器、脉冲发生器和时序发生器，所述比较器的正向输入为第二储能元件的输出电压，所述比较器的负向输入为第一储能元件的输出电压，所述比较器的输出端与所述脉冲发生器的输入端电连接，所述时序发生器采集变压器的原边通断信号，原边绕组导通时，原边通断信号为高电平，原边绕组截止时，原边通断信号为低电平，原边通断信号由高电平转换为低电平时，时序发生器发送放电信号给第二放电单元，第二放电单元对第二储能元件放电，第二储能元件放电结束，变压器的次边绕组的次边消磁开始，时序发生器发送第二充电信号给第二充电单元，第二充电单元对第二储能元件充电，时序发 生器相对于发送第二充电信号延迟设定时间发送第一充电信号给第一充电单元，第一充电单元对第一储能元件充电，当第二储能元件的输出电压等于第一储能元件的输出电压时，第一充电单元对第一储能元件充电结束，比较器触发脉冲发生器，脉冲发生器生成采样脉冲给时序发生器同时将采样脉冲作为放电信号发送给第一放电单元，时序发生器收到脉冲发生器发送的采样信号对变压器的辅助绕组的反馈电压信号进行采样，次边消磁结束，时序发生器发送充电信号给第三充电单元，第二储能元件对第一储能元件充电。
  5. 根据权利要求1所述的采样控制系统，其特征在于，所述充电模块包括第一充电单元、第二充电单元和第三充电单元，所述第一充电单元包括第一电流源和第一开关，所述第二充电单元包括第二电流源和第二开关，所述第三充电单元包括第五开关；所述储能模块包括第一储能元件和第二储能元件，所述第一储能元件包括第一电容，所述第二储能元件包括第二电容；所述放电模块包括第一放电单元和第二放电单元，所述第一放电单元包括第三开关，所述第二放电单元包括第四开关；所述控制采样模块包括比较器、脉冲发生器和时序发生器；
    其中，所述第一电流源通过第一开关与第一电容的正极板电连接，第一电容的负极板接地，所述第二电流源通过第二开关与第二电容的正极板电连接，第二电容的负极板接地，所述第三开关与第一电容的正极板电连接，所述第四开关与所述第二电容的正极板电连接，所述第五开关电连接在第一电容和第二电容的正电极之间，所述比较器的正向输入端与第二电容的正极板电连接，所述比较器的负向输入端与第一电容的正极板连接，所述比较器的输出端与所述脉冲发生器的输入端连接，所述脉冲发生器的输出端与所述时序发生器电连接，所述时序发生器采集变压器的原边通断信号，原边绕组导通时，原边通断信号为高电平，原边绕组截止时，原边通断信号为低电平，原边通断信号由高电平转换为低电平时，时序发生器发送放电信号给第四开关，第四开关导通，第二电容放电，第二电容的输出电压为0V时，第四开关断开，时序发生器发送第二充电信号给第二开关，第二开关导通，第二电流源对第二电容充电，时序发生器相对于发送第二充电信号延迟设定时间发送第一充电信号给第一开关，第一开关导通，第一电流源对第一电容充电，当第二电容的输出电压等于第一电容的输出电压时，第一开关断开，比较器触发脉冲发生器，脉冲发生器生成采样脉冲给时序发生器，时序发生器对变压器的反馈电压信号进行采样，同时脉冲发生器将采样脉冲作为放电信号发送给第三开关，第三开关导通，第一电容放电，第一电容输出电压为0V，变压器的次边绕组消磁结束时，时序发生器发送充电信号给第五开关，第五开关导通，第 二电容对第一电容充电。
  6. 根据权利要求5所述的采样控制系统，其特征在于，所述时序发生器包括次边消磁时间获得单元、判断单元、采样脉冲生成时刻确定单元、信号采集单元和信号发送单元，其中：
    所述信号采集单元用于采集原边通断信号和反馈电压信号；
    所述次边消磁时间获得单元用于根据信号采集单元采集的原边电流峰值得到次边消磁时间；
    所述判断单元用于判断次边消磁时间获得单元得到的消磁时间是否不大于消磁阈值；
    所述采样脉冲生成时刻确定单元用于根据所述判断单元的判断结果确定采样脉冲的生成时刻，当判断单元的判断结果为消磁时间不大于消磁阈值时，所述生成时刻与开始消磁时刻的距离t为其中，c1为第一电容的电容值，c2为第二电容的电容值，Tons为消磁时间；当判断单元的判断结果为消磁时间大于消磁阈值时，所述生成时刻与开始消磁时刻的距离t符合下式：
    其中，a为第一电流源和第二电流源的电流比值，b为第一电容与第二电容的电容比值，td为第一充电信号相对于第二充电信号延迟的设定时间；
    所述信号发送单元用于根据次边消磁时间获得单元得到的消磁时间和采样脉冲生成时刻确定单元确定的生成时刻控制第一开关、第二开关、第三开关、第四开关和第五开关，以使得在所述脉冲发生器在所述生成时刻生成采样脉冲。
  7. 根据权利要求6所述的采样控制系统，其特征在于，第一电流源的电流值是第二电流源的电流值的0.9倍，所述第一电容的电容值是第二电容的电容值的1.5倍。
  8. 根据权利要求6所述的采样控制系统，其特征在于，所述消磁阈值为4us。
  9. 根据权利要求6所述的采样控制系统，其特征在于，所述第一充电信号相对于第二充电信号延迟的设定时间为1.6us。
  10. 一种采样控制方法，用于控制原边反馈交直流转换器的反馈电压信号的采样，所述原边反馈交直流转换器包括变压器，所述变压器具有原边绕组、次边绕组和辅助绕组，所述反馈电压信号为辅助绕组的输出电压的分压信号，其特征在于，包括：
    根据原边反馈交直流转换器的原边绕组的原边电流峰值大小调整采样脉冲的生成时刻，所述原边电流峰值越小，所述生成时刻与所述次边绕组的开始消磁时刻距离越短。
  11. 根据权利要求10所述的采样控制方法，其特征在于，所述根据原边反馈交直流转换器的原边绕组的原边电流峰值大小调整采样脉冲的生成时刻的步骤包括：
    根据原边电流峰值获得次边绕组的消磁时间；
    判断上述消磁时间是否不大于消磁阈值；
    如果消磁时间不大于消磁阈值，所述采样脉冲的生成时刻不变；
    如果消磁时间大于消磁阈值，所述采样脉冲生成时刻与次边绕组的开始消磁时刻的时间距离随着原边电流峰值增大而增大。
  12. 根据权利要求11所述的采样控制方法，其特征在于，所述消磁阈值为4us，所述采样脉冲的生成时刻与开始消磁时刻的时间距离的初始值为0.4*Tons，所述采样脉冲的生成时刻与开始消磁时刻的时间距离符合下式：
    其中，t为生成时刻与开始消磁时刻的时间距离，Tons为消磁时间。
  13. 根据权利要求12所述的采样控制方法，其特征在于，所述原边电流峰值从1倍到3倍的范围内变化，所述采样脉冲的生成时刻与开始消磁时刻的时间距离对应的在0.4*Tons到0.8*Tons范围内变化。
  14. 一种控制器，其特征在于，包括权利要求1-9中任一所述的采样控制系统。
  15. 一种原边反馈交直流转换器，其特征在于，包括变压器和权利要求14所述的控制器。
PCT/CN2023/110892 2023-02-16 2023-08-03 采样控制系统、方法、控制器、原边反馈交直流转换器 WO2024169135A1 (zh)

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