CN114200992A - Feedback voltage sampling method and circuit, output voltage control method and circuit - Google Patents

Feedback voltage sampling method and circuit, output voltage control method and circuit Download PDF

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CN114200992A
CN114200992A CN202111461964.2A CN202111461964A CN114200992A CN 114200992 A CN114200992 A CN 114200992A CN 202111461964 A CN202111461964 A CN 202111461964A CN 114200992 A CN114200992 A CN 114200992A
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China
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signal
voltage
module
current
circuit
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CN114200992B (en
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文鹏
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Shenzhen Biyi Microelectronics Co ltd
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Shenzhen Biyi Microelectronics Co ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • 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

Abstract

The method comprises the steps of acquiring a primary current signal, a voltage feedback signal of a current period and a driving signal of a previous period of a flyback circuit, generating a control signal according to the voltage feedback signal, the primary current signal and the driving signal of the previous period, sampling and holding the voltage feedback signal according to the control signal to output a sampling and holding signal of the current period, wherein the sampling and holding signal is used for reflecting voltage information of the voltage feedback signal, and the accuracy of feedback voltage sampling under sudden change of the primary current signal is realized, so that the stable output of the flyback circuit is ensured, and the stability of power supply conversion is further ensured.

Description

Feedback voltage sampling method and circuit, output voltage control method and circuit
Technical Field
The invention relates to the field of voltage detection, in particular to a feedback voltage sampling method and circuit and an output voltage control method and circuit.
Background
With the continuous improvement of the urban development level and the continuous abundance of power consumption requirements, the requirements on power supply transformation equipment are higher and higher. Flyback converters are indispensable components in electronic devices, and are widely used in various forms of alternating current/direct current (AC/DC) and direct current/direct current (DC/DC) conversion. Compared with a secondary side feedback control flyback circuit, the primary side feedback control flyback circuit has the advantages of simple structure and good economical efficiency, and is widely applied to small and medium power chargers and adapters. Wherein the constant control of the output voltage determines the constancy of the output voltage, and the constant control of the output voltage depends on ensuring the constancy of the feedback voltage. Therefore, the constant sampling of the feedback voltage is important for ensuring the stable output of the flyback circuit.
The existing feedback voltage proportion sampling technology needs to ensure that the primary side current peak value can not suddenly change, and has the problem that the sampled feedback voltage can not accurately reflect the output voltage after the primary side current peak value is suddenly reduced, so that the stable output of a flyback circuit can not be ensured.
Disclosure of Invention
In view of the above, it is desirable to provide a feedback voltage sampling method and circuit, and an output voltage control method and circuit.
A feedback voltage sampling method, comprising:
acquiring a primary side current signal of a flyback circuit, a voltage feedback signal of a current period and a driving signal of a previous period;
generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period;
and sampling and holding the voltage feedback signal according to the control signal to output a sampling and holding signal of the current period, wherein the sampling and holding signal is used for reflecting the voltage information of the voltage feedback signal.
In one embodiment, the primary side current signal comprises a current period primary side current signal and a previous period primary side current signal; the generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period includes:
acquiring the demagnetization time of the flyback circuit in the previous period according to the voltage feedback signal and the driving signal;
acquiring a pulse time point of the control signal according to the current period primary side current signal, the previous period primary side current signal and the demagnetization time;
generating the control signal at the pulse time point.
In one embodiment, the obtaining the demagnetization time of the flyback circuit in the previous period according to the voltage feedback signal and the driving signal includes:
acquiring a first time point corresponding to a falling edge of the driving signal according to the driving signal;
acquiring a second time point when the voltage feedback signal firstly drops to zero after the drive signal arrives;
and acquiring the demagnetization time according to the first time point and the second time point.
In one embodiment, the time length value between the first time point and the pulse time point is a first time length value; the first time length value of the current period is in direct proportion to the demagnetization time of the previous period, in direct proportion to the current peak value of the primary side current signal of the current period, and in inverse proportion to the current peak value of the primary side current signal of the previous period.
In one embodiment, the method further comprises the following steps:
and generating a driving signal of the current period according to the sampling and holding signal of the current period, wherein the driving signal is also used for controlling the output voltage of the flyback circuit.
A method of controlling an output voltage, comprising:
acquiring a driving signal of a corresponding period according to the sampling and holding signal of the corresponding period obtained by the method;
and controlling the output voltage of the flyback circuit according to the driving signal of the corresponding period.
A feedback voltage sampling circuit, comprising:
the signal acquisition module is used for being connected with the flyback circuit and acquiring a primary side current signal, a voltage feedback signal of the current period and a driving signal of the previous period of the flyback circuit;
the signal generating module is connected with the signal acquiring module and used for generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period;
and the sampling and holding module is used for being respectively connected with the flyback circuit and the signal generating module, sampling and holding the voltage feedback signal according to the control signal so as to output a sampling and holding signal of the current period, and the sampling and holding signal is used for reflecting the voltage information of the voltage feedback signal.
In one embodiment, the sample-and-hold module is further configured to control a switch tube inside the sample-and-hold module to conduct a path between the sample-and-hold module and the flyback circuit according to the control signal, so as to obtain a voltage feedback signal of the flyback circuit, and perform sample-and-hold to output a sample-and-hold signal.
In one embodiment, the circuit further comprises:
and the voltage loop module is connected with the sampling and holding module and used for generating a driving signal of the current period according to the sampling and holding signal of the current period, and the driving signal is also used for controlling the output voltage of the flyback circuit.
In one embodiment, the sample and hold module comprises:
a first switch tube and a first capacitor; one end of the first switch tube is connected with one end of the flyback circuit, the other end of the first switch tube, one end of the first capacitor and one end of the voltage loop module are connected in common, and the other end of the first capacitor is grounded.
In one embodiment, the circuit further comprises:
and the primary current module is used for being respectively connected with the flyback circuit and the signal acquisition module to acquire the primary current signal of the flyback circuit.
In one embodiment, the primary side current module comprises:
a second switch tube and a second capacitor; one end of the second switch tube is connected with one end of the flyback circuit, the other end of the second switch tube, one end of the second capacitor and the other end of the signal generation module are connected in common, and the other end of the second capacitor is grounded.
An output voltage control circuit comprising:
the drive control module is used for acquiring a drive signal of a corresponding period according to the sampling hold signal of the corresponding period acquired by the circuit;
and the voltage control module is used for controlling the output voltage of the flyback circuit according to the driving signal of the corresponding period.
According to the feedback voltage sampling method and circuit and the output voltage control method and circuit, the primary side current signal of the flyback circuit, the voltage feedback signal of the current period and the driving signal of the previous period are obtained, the control signal is generated according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period, the voltage feedback signal is sampled and held according to the control signal so as to output the sampling and holding signal of the current period, the sampling and holding signal is used for reflecting the voltage information of the voltage feedback signal, the accuracy of sampling the feedback voltage under the sudden change of the primary side current signal is realized, the stable output of the flyback circuit is ensured, and the stability of power supply conversion is further ensured.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow diagram of a feedback voltage sampling method in one embodiment;
FIG. 2 is a schematic diagram of a sample and hold process in one embodiment;
FIG. 3 is a graph of current voltage waveforms through a feedback voltage sampling method and circuit in one embodiment;
FIG. 4 is a detailed flow chart of step 104 in one embodiment;
FIG. 5 is a flowchart detailing step 402 in one embodiment;
FIG. 6 is a flow chart of a method of controlling output voltage in one embodiment;
FIG. 7 is a block diagram of a feedback voltage sampling circuit in one embodiment;
FIG. 8 is a block diagram of a feedback voltage sampling circuit in one embodiment;
FIG. 9 is a block diagram of a feedback voltage sampling circuit in one embodiment;
FIG. 10 is a block diagram of a feedback voltage sampling circuit in one embodiment;
FIG. 11 is a block diagram of a feedback voltage sampling circuit in one embodiment;
FIG. 12 is a block diagram of a feedback voltage sampling circuit in one embodiment;
FIG. 13 is a block diagram of an output voltage control circuit in one embodiment;
FIG. 14 is a block diagram of an output voltage control circuit in one embodiment;
FIG. 15 is a schematic diagram of the structure of a rectifier module in one embodiment;
FIG. 16 is a schematic diagram of the structure of an absorbent module in one embodiment;
FIG. 17 is a schematic diagram of the structure of a secondary rectifier filter module in one embodiment;
FIG. 18 is a schematic diagram of the structure of a power module in one embodiment;
FIG. 19 is a schematic diagram of the structure of a detection module in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first client may be referred to as a second client, and similarly, a second client may be referred to as a first client, without departing from the scope of the present application. Both the first client and the second client are clients, but they are not the same client.
Referring to fig. 1, a flowchart of a feedback voltage sampling method according to an embodiment is shown.
In the present embodiment, as shown in fig. 1, the feedback voltage sampling method includes steps 102 to 106.
Step 102, a primary current signal of the flyback circuit, a voltage feedback signal of the current period and a driving signal of the previous period are obtained.
The flyback circuit is a primary circuit of a transformer of the flyback power supply; the flyback power supply is characterized in that when a primary coil of a transformer is just excited by direct-current pulse voltage, a secondary coil of the transformer does not provide power output for a load, and only after the excitation voltage of the primary coil of the transformer is turned off, the power output is provided for the load, and the transformer switching power supply is called as a flyback switching power supply or a flyback transformer switching power supply. The transformer consists of a primary winding Np, a secondary winding Ns and an auxiliary winding Na, which are coupled with each other.
The primary side current signal of the flyback circuit is a current signal flowing through a primary side winding Np of the switching power supply of the flyback transformer, and can be a primary side current peak value signal Ipk, namely a current flowing through a switching tube of the primary side winding. The method for acquiring the primary side current peak signal may be that the primary side current peak signal Ipk is represented by a reference current signal Ipk _ ref generated by the measurement voltage control module, or that the primary side current peak signal Ipk is represented by a current sampling signal Vcs _ sample generated when the primary side current signal flows through the sampling resistor.
Wherein, the voltage feedback signal V of the current periodFBAnd is used for characterizing the DC pulse in the current period to provide the power output Vout to the load. The method for obtaining the voltage feedback signal of the current period may be to obtain the feedback signal of the output voltage of the current period through a non-optical coupling transmission mode such as an auxiliary winding Na.
The driving signal PWM is a pulse width adjusting signal output by the primary feedback controller, and is used to control the switching on and off of the switching tube of the primary winding of the flyback power supply, so as to adjust the output voltage Vout provided to the load.
And 104, generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period.
The method for generating the control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period may be that the voltage feedback signal V is generated by a circuit unit having a signal generating function in the primary side feedback controllerFBThe primary side current signal Ipk and the driving signal of the previous period are analyzed and processed, and a driving signal used for controlling the switching tube of the primary side winding in the current period is generated.
And 106, sampling and holding the voltage feedback signal according to the control signal to output a sampling and holding signal of the current period, wherein the sampling and holding signal is used for reflecting the voltage information of the voltage feedback signal.
In an ideal condition, when the sampling module is in a sampling state, the output signal of the sampling and holding module changes along with the change of the input signal; when in the hold state, the output signal of the sample-and-hold block is held at the input signal level value at the instant the hold command is received. Optionally, as shown in fig. 2, when the circuit is in the sampling state, the switch is turned on, and the holding capacitor is charged, and if the capacitance value is small, the holding capacitor can complete charging and discharging within a short time, and then the output signal of the output terminal changes along with the change of the input signal; when the circuit is in a holding state, the switch is off because the switch is off, the input end of the integrated operational amplifier is in a high-impedance state, the capacitor discharges slowly, and the output signal is basically kept at a signal level value at the moment of disconnection because one end of the capacitor is connected with a signal following circuit formed by the integrated operational amplifier. The switch in the sampling and holding module is a semiconductor switch tube.
Optionally, referring to fig. 3, a current-voltage waveform diagram of a method and a circuit for sampling voltage by feedback in one embodiment is shown. As shown in fig. 3, when the current flowing through the primary winding switching tube, i.e., the primary current peak value Ipk, suddenly changes, the time Tdem for characterizing the demagnetization time of the flyback circuit may be a time starting point which is a falling edge of the PWM driving signal, and a time ending point which is a first voltage falling zero crossing after the PWM of the driving signal is turned off; the marking method of the feedback voltage sampling position P in the current period takes the falling edge of the PWM driving signal as the time starting point and takes the pulse rising edge of the current sampling signal Vcs _ sample as the time ending point. Therefore, from the principle of capacitance charge balance, it is possible to:
P(n)≈k*Tdem(n)
therefore, when the primary current peak signal Ipk suddenly decreases, the sampling pulse signal, i.e., the control signal CV _ sample, occurs before the demagnetization of the flyback power transformer is finished, so that the voltage information of the voltage feedback signal can be accurately reflected according to the sampling hold signal of the current period output by the control signal CV _ sample.
According to the feedback voltage sampling method provided by the embodiment, the primary side current signal, the current period voltage feedback signal and the previous period driving signal of the flyback circuit are obtained, the control signal is generated according to the voltage feedback signal, the primary side current signal and the previous period driving signal, the voltage feedback signal is sampled and held according to the control signal so as to output the current period sampling and holding signal, and the control signal is generated before the demagnetization of the flyback power supply transformer is finished, so that the sampling and holding signal can accurately reflect the voltage information of the voltage feedback signal, and the accuracy of feedback voltage sampling under sudden change of the primary side current signal is realized.
Referring now to FIG. 4, a flowchart illustrating the operation of step 104 according to one embodiment is shown.
In the present embodiment, the primary side current signal includes a current period primary side current signal and a previous period primary side current signal, and as shown in fig. 4, the step 104 includes sub-steps 402 to 406.
And step 402, acquiring the demagnetization time of the flyback circuit in the previous period according to the voltage feedback signal and the driving signal.
Wherein, the demagnetization time Tdem of the flyback circuit includes a time starting point and a time ending point, wherein the time starting point may beThe time point corresponding to the falling edge of the driving signal PWM, and the time end point may be the voltage feedback signal V of the current period after the driving signal PWM is turned offFBThe point in time of the first falling zero crossing.
And step 404, acquiring a pulse time point of the control signal according to the primary side current signal in the current period, the primary side current signal in the previous period and demagnetization time.
The primary side current signal may be a reference current signal Ipk _ ref generated by a current reference generation module in the primary side feedback controller, or a Vcs _ sample obtained by sampling and holding a primary side current peak signal and a voltage signal generated by the primary side current through a sampling resistor.
The method for obtaining the pulse time point P (n +1) of the control signal in the current period may be obtained by processing a primary side current signal Ipk (n +1) in the current period, a primary side current signal Ipk (n) in a previous period, and demagnetization time Tdem of the flyback circuit according to a mapping relationship through a signal processing module in the primary side feedback controller.
At step 406, a control signal is generated at the pulse time point.
And outputting a control signal CV _ sample according to the information of the pulse time point P (n + 1).
Referring to FIG. 5, a flowchart illustrating step 402 according to an embodiment is shown.
In the present embodiment, as shown in fig. 3, the step 402 includes sub-steps 502 to 506.
Step 502, obtaining a first time point corresponding to a falling edge of the driving signal according to the driving signal.
Alternatively, the first time point is a time point corresponding to a falling edge of the driving signal, and may be a time starting point of a demagnetization time of the flyback circuit.
Step 504, a second time point at which the voltage feedback signal first drops to zero after the drive signal arrives is obtained.
Alternatively, the second time point may be a time end point of a demagnetization time of the flyback circuit.
And step 506, acquiring demagnetization time according to the first time point and the second time point.
And determining the demagnetization time length of the flyback circuit according to the time interval between the time starting point and the time ending point of the demagnetization time of the flyback circuit.
In one embodiment, the time length value between the first time point and the pulse time point is a first time length value; the first time length value of the current period is in direct proportion to the demagnetization time of the previous period, in direct proportion to the current peak value of the primary side current signal of the current period, and in inverse proportion to the current peak value of the primary side current signal of the previous period.
The first time length value of the current period may be a time interval length P (n +1) between a time start point of the demagnetization time of the flyback circuit and a pulse time mark point of the control signal, and the time interval length P (n +1) is proportional to the demagnetization time tdem (n) of the flyback circuit in the last period; the time interval length P (n +1) between the time starting point of the demagnetization time of the flyback circuit and the pulse time marking point of the control signal is in direct proportion to the current peak value Ipk (n +1) of the primary side current signal in the current period; the time interval length P (n +1) between the time starting point of the demagnetization time of the flyback circuit and the pulse time marking point of the control signal is inversely proportional to the current peak value Ipk (n) of the primary side current signal in the previous period. The specific relational expression is as follows:
P(n+1)＝k*Ipk(n+1)/Ipk(n)*Tdem(n)
in the approximation that the difference between the first and second values,
Tdem(n+1)≈Ipk(n+1)/Ipk(n)*Tdem(n)
then
P(n+1)≈k*Tdem(n+1)
The following can be obtained approximately: the sampling position of the feedback voltage in the current period is in direct proportion to the demagnetization time of the transformer in the current period. Wherein k is a proportionality coefficient.
In one embodiment, the driving signal of the current period is generated according to the sampling and holding signal of the current period, and the driving signal is also used for controlling the output voltage of the flyback circuit.
Outputting a control signal CV _ sample according to the information of the pulse time point P (n +1) of the control signal; the control signal CV _ sample is used for controlling the on and off of a switch tube in the sampling and holding module to realize the electricity supplyPressure feedback signal VFBAnd performing sample hold to generate a sample hold signal VFB _ hold and further generate a driving signal of the current period, thereby controlling the output voltage Vout of the flyback circuit.
Referring to fig. 6, a flowchart of a control method of an output voltage according to an embodiment is shown.
In this embodiment, as shown in fig. 6, the method for controlling the output voltage includes steps 602 to 604.
Step 602, obtaining a driving signal of a corresponding period according to the sample-hold signal of the corresponding period obtained by the method described above.
And step 604, controlling the output voltage of the flyback circuit according to the driving signal of the corresponding period.
Acquiring a pulse time point P (n +1) of a control signal according to a primary side current signal Ipk (n +1) of the current period, a primary side current signal Ipk (n) of the previous period and demagnetization time Tdem (n); outputting a control signal CV _ sample according to the information of the pulse time point P (n +1) of the control signal; the control signal CV _ sample is used for controlling the on and off of a switch tube in the sampling and holding module to realize the voltage feedback signal VFBAnd performing sample hold to generate a sample hold signal VFB _ hold and further generate a driving signal of the current period, thereby controlling the output voltage Vout of the flyback circuit.
It should be understood that although the steps in the flowcharts of fig. 1 and 4-6 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 1 and 4-6 may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of performing the sub-steps or stages is not necessarily sequential, but may be performed alternately or alternatingly with other steps or at least some of the sub-steps or stages of other steps. It should be noted that the different embodiments described above may be combined with each other.
Fig. 7 is a block diagram of a feedback voltage sampling circuit according to an embodiment.
In this embodiment, the feedback voltage sampling circuit includes a signal obtaining module 702, a signal generating module 704, and a sample-and-hold module 706.
The signal obtaining module 702 is configured to be connected to the flyback circuit, and obtain a primary current signal of the flyback circuit, a voltage feedback signal of a current period, and a driving signal of a previous period.
The signal generating module 704 is connected to the signal obtaining module 702, and is configured to generate a control signal according to the voltage feedback signal, the primary current signal, and the driving signal of the previous period.
And a sample-and-hold module 706, which is respectively connected to the flyback circuit and the signal generation module 704, and is configured to sample and hold the voltage feedback signal according to the control signal to output a sample-and-hold signal of the current period, where the sample-and-hold signal is used to reflect voltage information of the voltage feedback signal.
In this embodiment, each module is used to execute each step in the corresponding embodiment in fig. 1, and specific reference is made to fig. 1 and the related description in the corresponding embodiment in fig. 1, which are not repeated herein.
In the feedback voltage sampling circuit provided in this embodiment, the signal obtaining module 702 obtains a primary current signal, a voltage feedback signal of a current period, and a driving signal of a previous period of the flyback circuit, the signal generating module 704 generates a control signal according to the voltage feedback signal, the primary current signal, and the driving signal of the previous period, the sample and hold module 706 performs sample and hold on the voltage feedback signal according to the control signal to output a sample and hold signal of the current period, the sample and hold signal is used for reflecting voltage information of the voltage feedback signal, and accuracy of feedback voltage sampling under sudden change of the primary current signal is achieved, so that stable output of the flyback circuit is ensured, and stability of power conversion is further ensured.
In one embodiment, the sample-and-hold module is further configured to control a switching tube inside the sample-and-hold module to conduct a path between the sample-and-hold module and the flyback circuit according to the control signal, so as to obtain a voltage feedback signal of the flyback circuit, and perform sample-and-hold to output a sample-and-hold signal.
The control signal CV _ sample is used for controlling the on and off of a switch tube in the feedback voltage sampling and holding module, namely, a channel between the sampling and holding module and a voltage feedback module in the flyback circuit is switched on, so that a voltage feedback signal of the flyback circuit is obtained, and sampling and holding are carried out to output a sampling and holding signal VFB _ hold.
Fig. 8 is a block diagram of a feedback voltage sampling circuit according to an embodiment.
In this embodiment, the feedback voltage sampling circuit includes a signal obtaining module 802, a signal generating module 804, a sample-and-hold module 806, and further includes a voltage loop module 808.
And a voltage loop module 808, connected to the sample-and-hold module 806, configured to generate a driving signal of a current period according to the sample-and-hold signal of the current period, where the driving signal is further used to control an output voltage of the flyback circuit.
The voltage loop module 808 receives the sample-and-hold signal VFB _ hold output by the sample-and-hold module 806 in the current period to generate a driving signal in the current period, and further controls the output voltage Vout of the flyback circuit.
Fig. 9 is a block diagram of a feedback voltage sampling circuit according to an embodiment.
As shown in fig. 9, in this embodiment, the feedback voltage sampling circuit includes a signal acquisition module, a signal generation module, a sample-and-hold module, and a voltage loop module.
The signal generating module generates a control signal, namely a sampling pulse signal CV _ sample, according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period; the sampling pulse signal CV _ sample is used for controlling the on and off of a switch tube in the feedback voltage sampling and holding module, namely, a channel between the sampling and holding module and a voltage feedback module in the flyback circuit is conducted, so that a voltage feedback signal of the flyback circuit is obtained, and sampling and holding are carried out to output a sampling and holding signal VFB _ hold; and the voltage loop module receives the sampling and holding signal VFB _ hold output by the sampling and holding module in the current period to generate a driving signal in the current period, and further controls the output voltage Vout of the flyback circuit.
In one embodiment, as shown in fig. 9, the sample-and-hold module includes a first switch tube S1, a first capacitor C1; one end of the first switch tube S1 is connected to one end of the flyback circuit, the other end of the first switch tube S1, one end of the first capacitor C1, and one end of the voltage loop module are connected in common, and the other end of the first capacitor C1 is grounded.
Fig. 10 is a block diagram of a feedback voltage sampling circuit according to an embodiment.
In this embodiment, the feedback voltage sampling circuit includes a signal obtaining module 1002, a signal generating module 1004, a sample-and-hold module 1006, a voltage loop module 1008, and a primary current module 1010.
The primary current module 1010 is configured to be connected to the flyback circuit and the signal obtaining module 1002, respectively, to obtain a primary current signal of the flyback circuit.
The method for acquiring the primary side current signal of the flyback circuit by the primary side current module 1010 may be to represent the primary side current peak signal Ipk by measuring a reference current signal Ipk _ ref generated by the voltage control module, or to represent the primary side current peak signal Ipk by measuring a current sampling signal Vcs _ sample generated when the primary side current signal flows through the sampling resistor.
Fig. 11 is a block diagram of a feedback voltage sampling circuit according to an embodiment.
As shown in fig. 11, in this embodiment, the feedback voltage sampling circuit includes a signal obtaining module, a signal generating module, a sample-and-hold module, a voltage loop module, and a primary side current module; the primary side current module is respectively connected with the voltage loop module and the signal acquisition module.
The sampling circuit comprises a primary side current module, a signal acquisition module, a signal generation module and a sampling module, wherein the primary side current module measures a reference current signal Ipk _ ref generated by the voltage loop module to represent a primary side current peak signal Ipk, namely a primary side current signal of the flyback circuit, the signal acquisition module acquires the primary side current signal of the flyback circuit, a voltage feedback signal of the current period and a driving signal of the previous period, and the signal generation module generates a control signal, namely a sampling pulse signal CV _ sample, according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period; the sampling pulse signal CV _ sample is used for controlling the on and off of a switch tube in the feedback voltage sampling and holding module, namely, a channel between the sampling and holding module and a voltage feedback module in the flyback circuit is conducted, so that a voltage feedback signal of the flyback circuit is obtained, and sampling and holding are carried out to output a sampling and holding signal VFB _ hold; and the voltage loop module receives the sampling and holding signal VFB _ hold output by the sampling and holding module in the current period to generate a driving signal in the current period, and further controls the output voltage Vout of the flyback circuit.
Fig. 12 is a block diagram of a feedback voltage sampling circuit according to an embodiment.
As shown in fig. 12, in this embodiment, the feedback voltage sampling circuit includes a signal acquisition module, a signal generation module, a sample-and-hold module, a voltage loop module, and a primary current module; the primary side current module is connected with the signal acquisition module.
The signal acquisition module acquires a primary side current signal of the flyback circuit, a voltage feedback signal of a current period and a driving signal of a previous period, and the signal generation module generates a control signal, namely a sampling pulse signal CV _ sample, according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period; the sampling pulse signal CV _ sample is used for controlling the on and off of a switch tube in the feedback voltage sampling and holding module, namely, a channel between the sampling and holding module and a voltage feedback module in the flyback circuit is conducted, so that a voltage feedback signal of the flyback circuit is obtained, and sampling and holding are carried out to output a sampling and holding signal VFB _ hold; and the voltage loop module receives the sampling and holding signal VFB _ hold output by the sampling and holding module in the current period to generate a driving signal in the current period, and further controls the output voltage Vout of the flyback circuit.
In one embodiment, as shown in fig. 12, the primary side current module includes a second switching tube S2, a second capacitor C2; one end of the second switch tube S2 is connected to one end of the flyback circuit, the other end of the second switch tube S2, one end of the second capacitor C2, and the other end of the signal generation module are connected in common, and the other end of the second capacitor C2 is grounded.
Fig. 13 is a block diagram of an output voltage control circuit according to an embodiment.
In this embodiment, the output voltage control circuit includes a driving control module 1302 and a voltage control module 1304.
The driving control module 1302 is configured to obtain a driving signal of a corresponding period according to the sample-and-hold signal of a corresponding period obtained by the above circuit.
And a voltage control module 1304, configured to control an output voltage of the flyback circuit according to the driving signal of the corresponding period.
In this embodiment, each module is configured to execute each step in the embodiment corresponding to fig. 6, and specific reference is made to fig. 6 and the related description in the embodiment corresponding to fig. 6, which are not repeated herein.
In the output voltage control circuit provided in this embodiment, the drive control module 1302 obtains the drive signal of the corresponding period according to the sample hold signal of the corresponding period obtained by the circuit, and the voltage control module 1304 controls the output voltage of the flyback circuit according to the drive signal of the corresponding period, so as to achieve accuracy of feedback voltage sampling under sudden change of the primary current signal, thereby ensuring stable output of the flyback circuit and further ensuring stability of power conversion.
Referring to fig. 14, a block diagram of an embodiment of an output voltage control circuit is shown.
In this embodiment, as shown in fig. 14, the voltage control module may also be used in an output voltage control circuit, which includes a rectifying module 1410, a starting module 1420, an absorbing module 1430, a secondary rectifying and filtering module 1440, a power supply module 1450, a detecting module 1460, a voltage control module 1470, and a voltage converting module 1480.
And the rectifying module 1410 is connected to the ac power supply, and is configured to convert an ac signal output by the ac power supply into a dc signal.
And a starting module 1420, connected to the rectifying and filtering module 1410, for starting the voltage control module 1470 via an external power source.
The absorption module 1430 is connected to the voltage conversion module 1480 for suppressing voltage surges.
And a secondary rectifying and filtering module 1440 connected to the voltage converting module 1480, for converting the output signal in ac form output through the secondary winding in the voltage converting module into an output voltage in dc form.
The power supply module 1450 is respectively connected to the voltage control module 1470 and the voltage conversion module 1480, and is configured to convert the electric energy output by the voltage conversion module 1480 into the voltage control module 1470.
The detecting module 1460 is connected to the power supplying module 1450, the voltage control module 1470, and the voltage converting module 1480, respectively, and is configured to detect whether the voltage converting module 1480 is demagnetized, and detect whether the output voltage control circuit is over-voltage.
The voltage control module 1470 is connected to the start module 1420, the absorption module 1430, the power supply module 1450, and the detection module 1460, respectively, and is configured to control stability of the dc voltage output of the flyback circuit.
The voltage conversion module 1480, which may be a transformer, includes a primary winding Np, a secondary winding Ns, and an auxiliary winding Na.
Fig. 15 is a schematic diagram of a structure of a rectifier module according to an embodiment.
In the present embodiment, as shown in fig. 15, the rectifying module may be a full-bridge rectifying circuit composed of four diodes, i.e., a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, for rectifying the input voltage into a dc output, and the dc output corresponds to the input voltage, i.e., when the input voltage is increased, the dc output is increased correspondingly, and when the input voltage is decreased, the dc output is decreased correspondingly.
In one embodiment, the start-up module may be a start-up resistor Rst, and the start-up resistor Rst is connected to the power supply terminal VDD of the voltage control module. When the voltage control module is started, the starting resistor charges the power supply module.
Referring to fig. 16, a schematic diagram of the structure of an absorber module in one embodiment is shown.
In the present embodiment, as shown in fig. 16, the absorption module includes a fifth diode D5, a second capacitor C2, and a first resistor R1; the cathode of the fifth diode D5, one end of the second capacitor C2, and one end of the first resistor R1 are connected in common, the other end of the second capacitor C2, the other end of the first resistor R1, and one end of the primary winding Np are connected in common, and the anode of the fifth diode D5 is connected to the other end of the primary winding Np.
Fig. 17 is a schematic diagram of a structure of the secondary rectifying and filtering module in one embodiment.
In this embodiment, as shown in fig. 17, the secondary rectifying and filtering module includes a sixth diode D6, a third capacitor C3, and a first resistor R2; the cathode of the sixth diode D6, one end of the third capacitor C3, and one end of the second resistor R2 are connected in common, the other end of the third capacitor C3, the other end of the second resistor R2, and one end of the secondary winding Ns are connected in common and grounded, and the anode of the sixth diode D6 is connected to the other end of the secondary winding Ns.
Fig. 18 is a schematic diagram of a power supply module according to an embodiment.
In the present embodiment, as shown in fig. 12, the power supply module includes a seventh diode D7, a fourth capacitor C4; the cathode of the seventh diode D7, one end of the fourth capacitor C4, and the power supply terminal VDD of the voltage control module are connected together, and the anode of the seventh diode D7 is connected to one end of the auxiliary winding Na.
Fig. 19 is a schematic diagram of a structure of the detection module in one embodiment.
In the present embodiment, as shown in fig. 19, the detection module includes a third resistor R3, a fourth resistor R4; one end of the third resistor R3, one end of the fourth resistor R4 and the feedback end FB of the voltage control module are connected in common, the other end of the third resistor R3 is grounded, and the other end of the fourth resistor R4 is connected with one end of the auxiliary winding Na.
Referring to fig. 18, a graph of current and voltage waveforms through a feedback voltage sampling method and circuit according to an embodiment is shown. As shown in fig. 18, even when the primary current peak signal Ipk suddenly decreases, the sample-hold pulse signal CV _ sample occurs before the demagnetization of the flyback power transformer is finished, i.e., the sample-hold pulse signal can accurately reflect the voltage information of the voltage feedback signal.
The division of each module in the feedback voltage sampling circuit and the output voltage control circuit is only used for illustration, in other embodiments, the feedback voltage sampling circuit and the output voltage control circuit may be divided into different modules as needed to complete all or part of the functions of the feedback voltage sampling circuit and the output voltage control circuit.
For the specific limitations of the feedback voltage sampling circuit and the output voltage control circuit, reference may be made to the limitations of the feedback voltage sampling method and the output voltage control method, which are not described herein again. All or part of the modules in the feedback voltage sampling circuit and the output voltage control circuit can be realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
The embodiment of the present application further provides a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor is enabled to execute the steps of the method in the foregoing embodiments.
The embodiment of the application also provides a computer readable storage medium. One or more non-transitory computer-readable storage media containing computer-executable instructions that, when executed by one or more processors, cause the processors to perform the steps of the feedback voltage sampling method, the output voltage control method.
The feedback voltage sampling method and circuit, the output voltage control method and the circuit provided in the above embodiments realize the accuracy of sampling the feedback voltage under the sudden change of the primary current signal, thereby ensuring the stable output of the flyback circuit, further ensuring the stability of power conversion, further improving the safety and reliability of the power system and the equipment, and having important economic value and popularization and practice value.
Any reference to memory, storage, database, or other medium used herein may include non-volatile and/or volatile memory. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM), which acts as external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), synchronous Link (Synchlink) DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and bus dynamic RAM (RDRAM).
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (13)

1. A feedback voltage sampling method, comprising:
acquiring a primary side current signal of a flyback circuit, a voltage feedback signal of a current period and a driving signal of a previous period;
generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period;
and sampling and holding the voltage feedback signal according to the control signal to output a sampling and holding signal of the current period, wherein the sampling and holding signal is used for reflecting the voltage information of the voltage feedback signal.
2. The method of claim 1, wherein the primary current signal comprises a current period primary current signal and a previous period primary current signal; the generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period includes:
acquiring the demagnetization time of the flyback circuit in the previous period according to the voltage feedback signal and the driving signal;
acquiring a pulse time point of the control signal according to the current period primary side current signal, the previous period primary side current signal and the demagnetization time;
generating the control signal at the pulse time point.
3. The method according to claim 2, wherein said obtaining a demagnetization time of the flyback circuit in a previous cycle according to the voltage feedback signal and the driving signal comprises:
acquiring a first time point corresponding to a falling edge of the driving signal according to the driving signal;
acquiring a second time point when the voltage feedback signal firstly drops to zero after the drive signal arrives;
and acquiring the demagnetization time according to the first time point and the second time point.
4. A method according to claim 3, wherein the length of time between the first point in time and the pulse point in time is a first length of time value; the first time length value of the current period is in direct proportion to the demagnetization time of the previous period, in direct proportion to the current peak value of the primary side current signal of the current period, and in inverse proportion to the current peak value of the primary side current signal of the previous period.
5. The method of claim 1, further comprising:
and generating a driving signal of the current period according to the sampling and holding signal of the current period, wherein the driving signal is also used for controlling the output voltage of the flyback circuit.
6. A method of controlling an output voltage, comprising:
the sample-and-hold signal of the corresponding period obtained according to the method of any one of claims 1 to 5, a drive signal of the corresponding period is obtained;
and controlling the output voltage of the flyback circuit according to the driving signal of the corresponding period.
7. A feedback voltage sampling circuit, comprising:
the signal acquisition module is used for being connected with the flyback circuit and acquiring a primary side current signal, a voltage feedback signal of the current period and a driving signal of the previous period of the flyback circuit;
the signal generating module is connected with the signal acquiring module and used for generating a control signal according to the voltage feedback signal, the primary side current signal and the driving signal of the previous period;
and the sampling and holding module is used for being respectively connected with the flyback circuit and the signal generating module, sampling and holding the voltage feedback signal according to the control signal so as to output a sampling and holding signal of the current period, and the sampling and holding signal is used for reflecting the voltage information of the voltage feedback signal.
8. The circuit of claim 7, wherein the sample-and-hold module is further configured to control a switch tube inside the sample-and-hold module to conduct a path between the sample-and-hold module and the flyback circuit according to the control signal, so as to obtain a voltage feedback signal of the flyback circuit, and perform sample-and-hold to output a sample-and-hold signal.
9. The circuit of claim 7, further comprising:
and the voltage loop module is connected with the sampling and holding module and used for generating a driving signal of the current period according to the sampling and holding signal of the current period, and the driving signal is also used for controlling the output voltage of the flyback circuit.
10. The circuit of claim 9, wherein the sample and hold module comprises:
a first switch tube and a first capacitor; one end of the first switch tube is connected with one end of the flyback circuit, the other end of the first switch tube, one end of the first capacitor and one end of the voltage loop module are connected in common, and the other end of the first capacitor is grounded.
11. The circuit of claim 7, further comprising:
and the primary current module is used for being respectively connected with the flyback circuit and the signal acquisition module to acquire the primary current signal of the flyback circuit.
12. The circuit of claim 11, wherein the primary current module comprises:
a second switch tube and a second capacitor; one end of the second switch tube is connected with one end of the flyback circuit, the other end of the second switch tube, one end of the second capacitor and the other end of the signal generation module are connected in common, and the other end of the second capacitor is grounded.
13. An output voltage control circuit, comprising:
a drive control module, configured to obtain a drive signal of a corresponding period according to the sample-and-hold signal of a corresponding period obtained by the circuit according to any one of claims 7 to 12;
and the voltage control module is used for controlling the output voltage of the flyback circuit according to the driving signal of the corresponding period.
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US20100054000A1 (en) * 2008-08-30 2010-03-04 Active-Semi, Inc. Accurate voltage regulation of a primary-side regulation power supply in continuous conduction mode operation
CN111107697A (en) * 2019-12-24 2020-05-05 深圳大学 Constant-current control circuit of flyback converter
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