CN110596449B - Knee-point voltage sampling system and method based on primary-side feedback flyback converter - Google Patents

Knee-point voltage sampling system and method based on primary-side feedback flyback converter Download PDF

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CN110596449B
CN110596449B CN201910838273.6A CN201910838273A CN110596449B CN 110596449 B CN110596449 B CN 110596449B CN 201910838273 A CN201910838273 A CN 201910838273A CN 110596449 B CN110596449 B CN 110596449B
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signal
sampling
converter
voltage information
holding
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CN110596449A (en
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唐顺柏
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Hichip Technology Ltd
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    • 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
    • G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
    • 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

Abstract

The invention discloses a knee point voltage sampling system based on a primary side feedback flyback converter, which comprises a delay line module, a first delay module and a second delay module, wherein the delay line module is used for delaying feedback voltage information on an auxiliary winding of the converter for a preset time integrally so as to generate a voltage delay signal; the signal generation module is used for integrating the reference voltage information of the converter and the feedback voltage information on the auxiliary winding to obtain a sampling holding signal related to the degaussing time of the converter; and the sampling and holding module is used for sampling and holding the voltage delay signal through the sampling and holding signal so as to obtain continuous knee voltage information. The system is reasonable in design, simple and efficient, continuous knee point voltage information is obtained by sampling through integral time delay of feedback voltage information, sampling efficiency is high, and sampling errors are small. Meanwhile, the invention also discloses a knee point voltage sampling method based on the primary side feedback flyback converter, and the method is simple in calculation and high in calculation speed, so that the sampling efficiency is improved.

Description

Knee-point voltage sampling system and method based on primary-side feedback flyback converter
Technical Field
The invention relates to the technical field of isolated power converters, in particular to a knee point voltage sampling system and method based on a primary side feedback flyback converter.
Background
As portable electronic devices are being updated and improved, isolated power converters have been rapidly developed. The flyback converter has the advantages of high efficiency, simple structure, low cost and the like, and occupies a dominant position in the field of power adapters and chargers.
As shown in fig. 1, a commonly used circuit of an isolated power converter includes a primary winding N1, a secondary winding N2, and an auxiliary winding N3. The primary coil N1 and the auxiliary coil N3 are grounded and isolated from the secondary coil N2, and primary side feedback does not directly sample from the output end but calculates the output voltage and current from the primary coil N1; wherein the output currentThe voltage is converted into a voltage signal through a resistor Rcs and detected, and the output voltage is detected by dividing the voltage through resistors R1 and R2 by using an auxiliary winding (auxiliary coil N3) and then feeding back the voltage VfbAnd (6) detecting.
After the inverter has demagnetized, the LC circuit formed in the auxiliary winding N3 begins to oscillate, and the output voltage will drop sinusoidally. Thus, the feedback voltage VfbAs shown in fig. 2 below, the voltage at the auxiliary winding N3 will then appear knee-like. Therefore, the demagnetization voltage is referred to as knee voltage, and the dotted circle (point a) in fig. 2 is the knee voltage time, and the most common ways of knee voltage detection are the delay method, the slope method, and the resonance method.
As shown in fig. 3, the delay method is performed by applying the feedback voltage V from the time Toff of the converter (the time when the primary winding N1 is turned off)fbAnd delaying the curve for a certain time T1, further sampling the voltage of the VA point, and taking the voltage of the VA point as the knee point voltage. But due to the feedback voltage signal VfbThe signal will vary to some extent during the converter Tdm time (degaussing time) and the sampling is therefore very inaccurate.
As shown in FIG. 4, the slope method is implemented by detecting the feedback voltage VfbThe slope of the signal curve, as shown at VB in FIG. 4, is the voltage at the knee point, but this approach requires a feedback voltage VfbSlope conversion of a signal curve in the degaussing time (Tdm) and the dead time (Tdead) is obvious, otherwise, knee voltage signals cannot be detected, and the method is complicated.
As shown in FIG. 5, the resonance method is to use a feedback voltage VfbThe signal curve is compared with a zero crossing point to obtain the period T of the oscillation signal, and the period T/4 can be subtracted from the VC moment due to the fixed resonance period to obtain the knee point voltage.
Disclosure of Invention
The knee point voltage sampling system and the method thereof are reasonable in design, simple and efficient, continuous knee point voltage information is obtained by sampling through integral time delay of feedback voltage information, the sampling efficiency is high, the sampling error is small, and in addition, the system is suitable for knee point voltage sampling of different types of feedback voltage signal curves, and the sampling application range is wide; meanwhile, the method is simple in calculation, does not involve complex algorithm, and is high in calculation speed, so that the sampling efficiency is improved.
In order to realize the purpose, the following technical scheme is adopted:
a knee point voltage sampling system based on a primary side feedback flyback converter comprises
The delay line module is used for delaying the feedback voltage information on the auxiliary winding of the converter for a preset time integrally so as to generate a voltage delay signal;
the signal generation module is used for integrating the reference voltage information of the converter and the feedback voltage information on the auxiliary winding to obtain a sampling holding signal related to the degaussing time of the converter;
and the sampling and holding module is used for sampling and holding the voltage delay signal through the sampling and holding signal so as to obtain continuous knee voltage information.
Further, the sample-and-hold signal includes
The sampling and holding module is used for receiving the sampling signal to sample the voltage delay signal to obtain knee voltage information at each moment;
and the sampling and holding module is used for receiving the holding signal to hold the knee voltage information at each moment so as to obtain continuous knee voltage information.
Further, the signal generating module comprises
The comparator is used for receiving feedback voltage information at a non-inverting input end of the comparator, receiving reference voltage information at an inverting input end of the comparator, and obtaining a first signal related to the feedback voltage information;
the trigger is connected with the output end of the comparator and used for filtering an interference signal in the first signal to obtain a degaussing periodic signal related to the degaussing time of the converter;
and the logic processing unit is respectively connected with the output end of the trigger, the comparator and the common connecting end of the trigger and is used for carrying out logic processing on the first signal and the demagnetization periodic signal so as to obtain a sampling and holding signal related to the demagnetization time of the converter.
Further, the interference signal comprises a resonance signal related to a dead time of the converter.
Further, the sample-and-hold module comprises a logic not gate U1, a logic not gate U2, an operational amplifier U3, a MOS tube M1, a MOS tube M2, a MOS tube M3 and a MOS tube M4; the input end of the logic not gate U1 and the gate of the MOS tube M1 are used for receiving a sampling signal, and the output end of the logic not gate U1 is connected with the gate of the MOS tube M2; the source and the drain of the MOS transistor M1 are respectively and correspondingly connected with the source and the drain of the MOS transistor M2, and the common connection end of the source of the MOS transistor M1 and the source of the MOS transistor M2 is used for receiving a voltage delay signal; the input end of the logic not gate U2 and the gate of the MOS tube M3 are used for receiving a holding signal, and the output end of the logic not gate U2 is connected with the gate of the MOS tube M4; the source and the drain of the MOS transistor M3 are respectively and correspondingly connected with the source and the drain of the MOS transistor M4, and the common connection end of the drain of the MOS transistor M3 and the drain of the MOS transistor M4 is used for outputting knee voltage information; the non-inverting input end of the operational amplifier U3 is connected to the common connection end of the drain of the MOS transistor M1 and the drain of the MOS transistor M2, and the inverting input end of the operational amplifier U3 is connected with the output end thereof and then electrically connected to the common connection end of the source of the MOS transistor M3 and the source of the MOS transistor M4.
Furthermore, the non-inverting input end of the operational amplifier U3 and the common connection end of the MOS tube M1 and the MOS tube M2 are grounded through a filter capacitor C1; the common connection end of the drain electrode of the MOS transistor M3 and the drain electrode of the MOS transistor M4 is also grounded through a filter capacitor C2.
In order to achieve the above object, the present invention further provides a knee voltage sampling method based on the primary side feedback flyback converter, including the following steps:
s1: integrally delaying feedback voltage information on an auxiliary winding of the converter for a preset time through a delay line module to obtain a voltage delay signal;
s2: integrating the reference voltage information and the feedback voltage information of the converter through a signal generation module to respectively obtain a sampling signal and a holding signal related to the degaussing time of the converter;
s3: based on the sampling signal and the hold signal obtained in S2, the sample-and-hold module samples and holds the voltage delay signal obtained in S1, and continuous knee voltage information is obtained.
Further, the integrating the reference voltage information and the feedback voltage information of the converter by the signal generating module specifically includes the following steps:
s21: inputting reference voltage information of the converter and feedback voltage information on an auxiliary winding of the converter into a comparator to obtain a first signal related to the feedback voltage information;
s22: inputting the first signal into a trigger, filtering an interference signal in the first signal, and obtaining a demagnetization periodic signal related to the demagnetization time of the converter;
s23: based on the first signal obtained at S21 and the degaussing period signal obtained at S22, the logic processing unit logically processes the first signal and the degaussing period signal to obtain a sampling signal and a holding signal related to the degaussing time of the converter.
Further, the sampling and holding of the voltage delay signal obtained in S1 by the sample-and-hold module based on the sampling signal and the hold signal obtained in S2 specifically includes the following steps:
s31: inputting the voltage delay signal, the sampling signal and the holding signal to a sampling holding module;
s32: and controlling the sampling and holding module to work through the sampling signal and the holding signal so as to output continuous knee voltage information.
By adopting the scheme, the invention has the beneficial effects that:
1) the system is reasonable in design, the circuit is simple and efficient, and the understanding is easy, so that the error of sampling knee voltage caused by calculation errors is reduced, and the sampling precision is improved;
2) the feedback voltage information is sampled by integrally delaying the feedback voltage information, so that the sampling efficiency is high, the sampling method is suitable for knee point voltage sampling of different types of feedback voltage signal curves, and the sampling application range is wide;
3) the method has simple calculation, does not involve complex algorithm, and has high calculation speed, thereby improving knee voltage sampling efficiency.
Drawings
FIG. 1 is a circuit diagram of a prior art primary side feedback flyback converter;
FIG. 2 is a schematic diagram of a prior art feedback voltage signal;
FIG. 3 is a schematic diagram of a knee voltage sampling method using a time delay method in the prior art;
FIG. 4 is a diagram illustrating a prior art knee voltage sampling using a slope method;
FIG. 5 is a diagram illustrating a knee voltage sampling method according to the prior art;
FIG. 6 is a schematic block diagram of the present invention;
FIG. 7 is a schematic block diagram of the signal generation module of the present invention;
FIG. 8 is a circuit diagram of a sample and hold module of the present invention;
FIG. 9 is a schematic diagram of a voltage delay signal generated by delaying feedback voltage information by a predetermined time in one embodiment;
FIG. 10 is a diagram illustrating a sample signal and a hold signal obtained by a signal generating module according to an embodiment;
FIG. 11 is a diagram illustrating knee voltage information obtained in an embodiment;
wherein the figures identify the description:
1-delay line module; 2-a signal generating module;
3-a sample-and-hold module; 4-sample and hold signal;
5-voltage delay signal; 21-a comparator;
22-a flip-flop; 23-a logical processing unit;
41-sampling the signal; 42-hold signal.
Detailed Description
The invention is described in detail below with reference to the figures and the specific embodiments.
Referring to fig. 6 to 11, the present invention provides a knee voltage sampling system based on a primary feedback flyback converter, which includes
The delay line module 1 is used for delaying the feedback voltage information on the auxiliary winding of the converter for a preset time integrally to generate a voltage delay signal 5;
the signal generating module 2 is used for integrating reference voltage information of the converter and feedback voltage information on the auxiliary winding to obtain a sampling hold signal 4 related to demagnetization time of the converter;
and the sampling and holding module 3 is used for sampling and holding the voltage delay signal 5 through the sampling and holding signal 4 so as to obtain continuous knee voltage information.
The sample-hold signal 4 comprises a sampling signal 41, and the sample-hold module 3 is configured to receive the sampling signal 41 to sample the voltage delay signal 5, so as to obtain knee voltage information at each time; and the sample-hold module 3 is used for receiving the hold signal 42 to hold the knee voltage information at each moment to obtain continuous knee voltage information. The signal generation module 2 comprises
The comparator 21, a non-inverting input terminal of the comparator 21 receives the feedback voltage information, an inverting input terminal of the comparator 21 receives the reference voltage information, and the comparator 21 is configured to obtain a first signal related to the feedback voltage information; the trigger 22 is connected with the output end of the comparator 21 and is used for filtering an interference signal in the first signal to obtain a degaussing periodic signal related to the degaussing time of the converter; and the logic processing unit 23 is respectively connected with the output end of the trigger 22 and the common connection end of the comparator 21 and the trigger 22, and is used for logically processing the first signal and the demagnetization periodic signal to obtain the sample hold signal 4 related to the demagnetization time of the converter.
The interference signal comprises a resonance signal related to the dead time of the converter; the sample-and-hold module 3 comprises a logical not gate U1, a logical not gate U2, an operational amplifier U3, a MOS tube M1, a MOS tube M2, a MOS tube M3 and a MOS tube M4; the input end of the logic not gate U1 and the gate of the MOS tube M1 are used for receiving the sampling signal 41, and the output end of the logic not gate U1 is connected with the gate of the MOS tube M2; the source and the drain of the MOS transistor M1 are respectively and correspondingly connected with the source and the drain of the MOS transistor M2, and the common connection end of the source of the MOS transistor M1 and the source of the MOS transistor M2 is used for receiving the voltage delay signal 5; the input end of the logic not gate U2 and the gate of the MOS tube M3 are used for receiving the holding signal 42, and the output end of the logic not gate U2 is connected with the gate of the MOS tube M4; the source and the drain of the MOS transistor M3 are respectively and correspondingly connected with the source and the drain of the MOS transistor M4, and the common connection end of the drain of the MOS transistor M3 and the drain of the MOS transistor M4 is used for outputting knee voltage information; the non-inverting input end of the operational amplifier U3 is connected with the common connection end of the drain electrode of the MOS tube M1 and the drain electrode of the MOS tube M2, and the inverting input end of the operational amplifier U3 is connected with the output end thereof and is connected with the common connection end of the source electrode of the MOS tube M3 and the source electrode of the MOS tube M4; the non-inverting input end of the operational amplifier U3 is grounded through a filter capacitor C1 with the common connection end of the MOS tube M1 and the MOS tube M2; the common connection end of the drain electrode of the MOS transistor M3 and the drain electrode of the MOS transistor M4 is also grounded through a filter capacitor C2.
The invention also provides a knee point voltage sampling method based on the primary side feedback flyback converter, which comprises the following steps:
s1: integrally delaying feedback voltage information on an auxiliary winding of the converter for a preset time through a delay line module 1 to obtain a voltage delay signal 5;
s2: integrating the reference voltage information and the feedback voltage information of the converter through a signal generation module 2 to obtain a sampling signal 41 and a holding signal 42 related to the degaussing time of the converter respectively;
s3: based on the sampling signal 41 and the hold signal 42 obtained in S2, the sample-and-hold block 3 samples and holds the voltage delay signal 5 obtained in S1, thereby obtaining continuous knee voltage information.
The step of integrating the reference voltage information and the feedback voltage information of the converter by the signal generating module 2 specifically includes the following steps:
s21: inputting the reference voltage information of the converter and the feedback voltage information on the auxiliary winding of the converter into a comparator 21 to obtain a first signal related to the feedback voltage information;
s22: inputting the first signal to the trigger 22, filtering an interference signal in the first signal, and obtaining a demagnetization periodic signal related to the demagnetization time of the converter;
s23: based on the first signal obtained at S21 and the degaussing period signal obtained at S22, the logic processing unit 23 logically processes the first signal and the degaussing period signal to obtain a sampling signal 41 and a hold signal 42 related to the degaussing time of the converter.
The sampling and holding of the voltage delay signal 5 obtained in S1 by the sample-and-hold module 3 based on the sampling signal 41 and the hold signal 42 obtained in S2 specifically includes the following steps:
s31: inputting the voltage delay signal 5, the sampling signal 41 and the holding signal 42 into the sample-and-hold module 3;
s32: the sampling and holding module 3 is controlled to work by the sampling signal 41 and the holding signal 42 to output continuous knee voltage information.
The working principle of the invention is as follows:
as shown in fig. 6, the feedback voltage information (feedback voltage Vfb) is delayed integrally by the delay line module 1 to obtain a voltage delay signal 5 (the waveform of the voltage delay signal 5 is shown in fig. 9); after the feedback voltage information and the reference voltage information are simultaneously input to the signal generating module 2, a sampling signal 41 and a holding signal 42 (the two signals are periodic signals of the degaussing time of the converter) related to the degaussing time of the converter are obtained, and the voltage delay signal 5 (the period of the degaussing time of the voltage delay signal 5 is delayed by the delay line module 1, so that the periodic signals of the corresponding degaussing time need to be obtained to sample the signal) is sampled and held by the two signals, so that the continuous knee voltage information can be obtained.
The signal generating module 2 is shown in fig. 7, and includes a comparator 21, a flip-flop 22, and a logic processing unit 23; after the feedback voltage information and the reference voltage information pass through the comparator 21, a first signal related to the feedback voltage information can be obtained (the first signal includes a degaussing periodic signal related to the degaussing time of the converter, and an interference signal doped between the degaussing periodic signals, such as a resonant signal with a large amplitude related to the dead time of the converter, etc.). Therefore, the first signal is input to the trigger 22, so as to filter the interference signal and obtain an exact degaussing period signal; the first signal and the degaussing period signal are processed by the logic processing unit 23, and then a sampling signal 41 and a holding signal 42 (as shown in fig. 10) related to the degaussing time are obtained.
As shown in fig. 8, the sample-and-hold module 3 inputs the voltage delay signal 5, the sampling signal 41, and the hold signal 42 into the sample-and-hold module 3 to obtain continuous knee voltage information (as shown in fig. 11); the sampling signal 41 and the holding signal 42 are periodic signals related to the degaussing time of the converter, the voltage delay signal 5 is the whole delay of the feedback voltage information, the knee voltage information (such as V1 and V2 shown in FIG. 11) at each moment can be obtained more accurately by sampling the voltage delay signal 5 through the sampling signal 41, and the knee voltage information at each moment can be held through the holding signal 42, so that continuous knee voltage information can be obtained; the detection mode is convenient for monitoring feedback voltage information in the switching power supply system, regulating and controlling output voltage and realizing a constant voltage mode of the switching power supply system; as shown in fig. 8, the not logic gate U1, the not logic gate U2, and the operational amplifier U3 in the sample-and-hold block 3 are used as voltage followers, and the MOS transistor M1, the MOS transistor M2, the MOS transistor M3, and the MOS transistor M4 are used as switching transistors; the voltage delay signal 5 is input into the module, and the working state of the switch tube is controlled by the sampling signal 41 and the holding signal 42, so that continuous knee voltage information can be output.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (6)

1. A knee point voltage sampling system based on a primary side feedback flyback converter is characterized by comprising
The delay line module is used for delaying the feedback voltage information on the auxiliary winding of the converter for a preset time integrally so as to generate a voltage delay signal;
the signal generation module is used for integrating the reference voltage information of the converter and the feedback voltage information on the auxiliary winding to obtain a sampling holding signal related to the degaussing time of the converter;
the sampling and holding module is used for sampling and holding the voltage delay signal through the sampling and holding signal so as to obtain continuous knee voltage information;
wherein the sample-and-hold signal comprises:
the sampling and holding module is used for receiving the sampling signal to sample the voltage delay signal to obtain knee voltage information at each moment;
the sampling and holding module is used for receiving the holding signal to hold knee voltage information at each moment to obtain continuous knee voltage information;
the signal generation module comprises
The comparator is used for receiving feedback voltage information at a non-inverting input end of the comparator, receiving reference voltage information at an inverting input end of the comparator, and obtaining a first signal related to the feedback voltage information;
the trigger is connected with the output end of the comparator and used for filtering an interference signal in the first signal to obtain a degaussing periodic signal related to the degaussing time of the converter;
and the logic processing unit is respectively connected with the output end of the trigger, the comparator and the common connecting end of the trigger and is used for carrying out logic processing on the first signal and the demagnetization periodic signal so as to obtain a sampling and holding signal related to the demagnetization time of the converter.
2. The knee voltage sampling system based on a primary feedback flyback converter according to claim 1, wherein the interference signal comprises a resonance signal related to a dead time of the converter.
3. The knee voltage sampling system based on the primary side feedback flyback converter is characterized in that the sample-hold module comprises a logical not gate U1, a logical not gate U2, an operational amplifier U3, a MOS tube M1, a MOS tube M2, a MOS tube M3 and a MOS tube M4; the input end of the logic not gate U1 and the gate of the MOS tube M1 are used for receiving a sampling signal, and the output end of the logic not gate U1 is connected with the gate of the MOS tube M2; the source and the drain of the MOS transistor M1 are respectively and correspondingly connected with the source and the drain of the MOS transistor M2, and the common connection end of the source of the MOS transistor M1 and the source of the MOS transistor M2 is used for receiving a voltage delay signal; the input end of the logic not gate U2 and the gate of the MOS tube M3 are used for receiving a holding signal, and the output end of the logic not gate U2 is connected with the gate of the MOS tube M4; the source and the drain of the MOS transistor M3 are respectively and correspondingly connected with the source and the drain of the MOS transistor M4, and the common connection end of the drain of the MOS transistor M3 and the drain of the MOS transistor M4 is used for outputting knee voltage information; the non-inverting input end of the operational amplifier U3 is connected to the common connection end of the drain of the MOS transistor M1 and the drain of the MOS transistor M2, and the inverting input end of the operational amplifier U3 is connected with the output end thereof and then electrically connected to the common connection end of the source of the MOS transistor M3 and the source of the MOS transistor M4.
4. The knee voltage sampling system based on the primary side feedback flyback converter of claim 3, wherein the non-inverting input terminal of the operational amplifier U3 is grounded through a filter capacitor C1 with the common connection terminal of the MOS transistor M1 and the MOS transistor M2; the common connection end of the drain electrode of the MOS transistor M3 and the drain electrode of the MOS transistor M4 is also grounded through a filter capacitor C2.
5. A knee point voltage sampling method based on a primary side feedback flyback converter is characterized by comprising the following steps:
s1: integrally delaying feedback voltage information on an auxiliary winding of the converter for a preset time through a delay line module to obtain a voltage delay signal;
s2: integrating the reference voltage information and the feedback voltage information of the converter through a signal generation module to respectively obtain a sampling signal and a holding signal related to the degaussing time of the converter;
s3: based on the sampling signal and the holding signal obtained in the step S2, the sampling and holding module samples and holds the voltage delay signal obtained in the step S1 to obtain continuous knee voltage information;
the signal generation module is used for integrating the reference voltage information and the feedback voltage information of the converter, and the signal generation module specifically comprises the following steps of:
s21: inputting reference voltage information of the converter and feedback voltage information on an auxiliary winding of the converter into a comparator to obtain a first signal related to the feedback voltage information;
s22: inputting the first signal into a trigger, filtering an interference signal in the first signal, and obtaining a demagnetization periodic signal related to the demagnetization time of the converter;
s23: based on the first signal obtained at S21 and the degaussing period signal obtained at S22, the logic processing unit logically processes the first signal and the degaussing period signal to obtain a sampling signal and a holding signal related to the degaussing time of the converter.
6. The knee voltage sampling method based on the primary feedback flyback converter of claim 5, wherein the sampling and holding of the voltage delay signal obtained in S1 by the sample-and-hold module based on the sampling signal and the hold signal obtained in S2 specifically comprises the following steps:
s31: inputting the voltage delay signal, the sampling signal and the holding signal to a sampling holding module;
s32: and controlling the sampling and holding module to work through the sampling signal and the holding signal so as to output continuous knee voltage information.
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