CN102801340B - Control method and controller for AC-DC converter - Google Patents

Abstract

Translated fromChinese

本发明公开了一种AC-DC变换器的控制方法，其通过采集AC-DC变换器的辅助绕组电压信号，并采用高精度的原边反馈技术，自动补偿反馈量，以获得精确的反馈量，进而构造出PWM信号以驱动AC-DC变换器中的开关管，最终实现控制调节变换器输出电压的目的；故本发明方法计算得到反馈量的精度，进而保证了AC-DC变换器输出电压的精度。本发明还公开了一种AC-DC变换器的控制器，包括原边采样电路和数字补偿器；原边采样电路包括波形实时分析模块、单输入双输出数模转换器和两个比较器；能够得到相对精确的反馈量，其采用数模转换器(而非模数转换器)，相比较之下，降低了设计难度，节省了消耗的面积。

The invention discloses a control method of an AC-DC converter, which collects the auxiliary winding voltage signal of the AC-DC converter and adopts a high-precision primary side feedback technology to automatically compensate the feedback amount to obtain an accurate feedback amount , and then construct a PWM signal to drive the switching tube in the AC-DC converter, and finally realize the purpose of controlling and adjusting the output voltage of the converter; therefore, the method of the present invention calculates the accuracy of the feedback amount, thereby ensuring the output voltage of the AC-DC converter accuracy. The invention also discloses a controller of an AC-DC converter, which includes a primary-side sampling circuit and a digital compensator; the primary-side sampling circuit includes a waveform real-time analysis module, a single-input double-output digital-to-analog converter and two comparators; Relatively accurate feedback can be obtained, and a digital-to-analog converter (rather than an analog-to-digital converter) is used, which reduces design difficulty and saves consumed area by comparison.

Description

A kind of control method of AC-DC converter and controller thereof

Technical field

The invention belongs to voltage changer control technology field, be specifically related to control method and the controller thereof of a kind of AC-DC (AC-DC) converter.

Background technology

Along with the development of battery charger, LED drive circuit etc., the designing technique chip of AC-DC converter has also obtained develop rapidly.The integrated level of AC-DC converter chip is required also improving gradually, and designer is required to use as little as possible the outer device of sheet, to reduce hardware spending and converter overall volume.

Fig. 1 is traditional based on secondary feedback AC-DC converter.This chip adopts light-coupled isolation feedback system as shown in the figure, output voltage on load resistance passes through photoelectrical coupler, be delivered to transformer primary side as feedback voltage, and remove regulation output voltage by controller, this feedback system not only needs the outer photoelectrical coupler of a sheet, increase expense, and the current transfer ratio of photoelectrical coupler is subject to the impact of temperature larger, along with the variation of temperature, current transfer ratio can be nonlinear change, cause the sampling of output voltage to occur error, affect output voltage precision, this impact is the most obvious in the larger power supply of the heavier heating of load.

The AC-DC converter based on former limit feedback is as shown in Figure 2 widely adopted.In figure, feedback voltage is that the auxiliary winding up-sampling of transformer from converter obtains, and is characterized in also realizing the isolation of former limit and secondary without photoelectrical coupler in the situation that, but due to auxiliary winding voltage V_sensenon-direct voltage, therefore, at a sampling hold circuit of chip internal design, removes at a fixing sampled point V that samples_senseobtain feedback quantity V_fBbut under actual conditions, sampling hold circuit may be very inaccurate, this fixing sampled point cannot be followed the tracks of knee voltage, and the impact of diode drop can cause the not accurate of sampling.

According to the known existing sampling feedback technology of above-mentioned situation, the feedback quantity V of its output_fBbetween corresponding feedback voltage and converter output voltage, there is certain error.This error, along with loading condition and the outer device parameters of sheet of system change and change, cannot compensate this error in sheet.The error of feedback quantity directly affects the precision of output voltage.

Summary of the invention

For the existing above-mentioned technological deficiency of prior art, the invention provides a kind of control method and controller thereof of AC-DC converter, can obtain the output voltage of relatively accurate feedback quantity with control change device.

A control method for AC-DC converter, comprises the steps:

(1) the auxiliary winding voltage signal V of collection AC-DC converter_sense, and obtain the feedback quantity V in a cycle on AC-DC converter_fB[i-1];

(2) to described feedback quantity V_fBafter [i-1] digital-to-analogue conversion, obtainfeedback voltage V 1, and will after fixed voltage value of the amplitude lifting offeedback voltage V 1, obtain comparative voltage V2;

(3) by described auxiliary winding voltage signal V_sensecompare withfeedback voltage V 1 and comparative voltage V2 respectively, obtain respectively two comparison signal V_s1and V_s2;

(4) calculate two comparison signal V_s1and V_s2trailing edge time difference Δ t, and by trailing edge time difference Δ t and fiducial time poor Δ t_refcompare, determine regulated quantity Δ V according to both differences_fB, and then utilize regulated quantity Δ V by feedback compensation algorithm_fBto feedback quantity V_fB[i-1] regulates compensation, in the hope of the feedback quantity V of AC-DC converter current period_fB[i];

(5) according to described feedback quantity V_fB[i] constructs pwm signal, to control the break-make of switching tube in AC-DC converter.

Described feedback compensation algorithm is based on following formula:

As Δ t > Δ t_reftime: V_fB[i]=V_fB[i-1]-Δ V_fB

As Δ t=Δ t_reftime: V_fB[i]=V_fB[i-1]

As Δ t < Δ t_reftime: V_fB[i]=V_fB[i-1]+Δ V_fBwherein: differ from Δ t fiducial time_reffor default set-point; Δ t and Δ t_refdiffer larger, Δ V_fBalso larger.

A controller for AC-DC converter, comprises former limit sample circuit and digital compensator;

Described digital compensator is used for according to the feedback quantity V of the AC-DC converter current period of former limit sample circuit output_fB[i] constructs pwm signal, to control the break-make of switching tube in AC-DC converter;

Described former limit sample circuit comprises a waveform real-time analysis module, a single-input double-output digital to analog converter and two comparators;

The feedback quantity V in a cycle on the AC-DC converter of described single-input double-output digital to analog converter reception waveform real-time analysis module output_fB[i-1], to feedback quantity V_fBafter [i-1] digital-to-analogue conversion, obtainfeedback voltage V 1 output, will after fixed voltage value of the amplitude lifting offeedback voltage V 1, obtain comparative voltage V2 output;

Two comparators are respectively by the auxiliary winding voltage signal V offeedback voltage V 1 and comparative voltage V2 and AC-DC converter_sensecompare, obtain respectively two comparison signal V_s1and V_s2;

Described waveform real-time analysis module is used for calculating two comparison signal V_s1and V_s2trailing edge time difference Δ t, and by trailing edge time difference Δ t and fiducial time poor Δ t_refcompare, determine regulated quantity Δ V according to both differences_fB, and then utilize regulated quantity Δ V by feedback compensation algorithm_fBto feedback quantity V_fB[i-1] regulates compensation, in the hope of the feedback quantity V of AC-DC converter current period_fB[i].

Preferably, described single-input double-output digital to analog converter is built by two MUX and a string divider resistance, and this digital to analog converter adopts the linear dividing potential drop of resistance to form, simple in structure, realize easily, and the matching precision of resistance is very high, guarantees that dividing potential drop has the good linearity.

Preferably, described waveform real-time analysis module and digital compensator are all by the FPGA realization of programming, and FPGA programming has stronger flexibility, and convenient control and adjusting for clock accuracy, have good repeatability.

The present invention is by gathering the auxiliary winding voltage signal of AC-DC converter, and adopt high-precision former limit feedback technique, auto-compensation feedback quantity, to obtain accurate feedback quantity, and then construct pwm signal to drive the switching tube in AC-DC converter, finally realize the object of regulating and controlling converter output voltage; Therefore the inventive method calculates the precision of feedback quantity, and then guarantee the precision of AC-DC converter output voltage; Controller simultaneously of the present invention adopts digital to analog converter (but not analog to digital converter), under comparing, has reduced design difficulty, has saved the area consuming.

Accompanying drawing explanation

Fig. 1 is the structural representation of AC-DC converter and the controller based on secondary feedback thereof.

Fig. 2 is the structural representation of AC-DC converter and the controller based on former limit feedback thereof.

Fig. 3 is AC-DC converter of the present invention and control structure schematic diagram thereof.

Fig. 4 is signal I in AC-DC converter_s, V_sensework wave schematic diagram with PWM.

Fig. 5 is the structural representation of controller of the present invention.

Fig. 6 is the structural representation of single-input double-output digital to analog converter.

The waveform schematic diagram of each signal when Fig. 7 (a) is the corresponding knee voltage of feedback quantity.

Fig. 7 (b) is the waveform schematic diagram of the relative knee voltage of feedback quantity each signal when excessive.

Fig. 7 (c) is the waveform schematic diagram of the relative knee voltage of feedback quantity each signal when too small.

Fig. 8 is the schematic flow sheet of feedback compensation algorithm of the present invention.

Embodiment

In order more specifically to describe the present invention, below in conjunction with the drawings and the specific embodiments, control method of the present invention and controller thereof are elaborated.

Shown in Fig. 3 the structure of AC-DC converter of the present invention and controller thereof, AC-DC converter is made up of half-wave rectifier BR, transformer T, switching tube Q, diode D and capacitor C; Wherein, the positive-negative input end of half-wave rectifier BR meets alternating voltage AC, positive output end and the former limit of transformer T winding N_psame Name of Ends be connected, negative output terminal ground connection; The former limit of transformer T winding N_pnon-same polarity be connected with the drain electrode of switching tube Q, the source ground of switching tube Q, the grid of switching tube Q receives the pwm signal that controller provides, transformer T secondary winding N_snon-same polarity be connected with the anode of diode D, the negative electrode of diode D is connected with one end of capacitor C, the other end of capacitor C and transformer T secondary winding N_ssame Name of Ends be connected and ground connection, transformer T assists winding N_auxnon-same polarity be connected with resistance R₁, transformer T assists winding N_auxsame Name of Ends ground connection, resistance R₁by with resistance R₂ground connection after series connection; The two ends of capacitor C are the output port of AC-DC converter, and the output port of AC-DC converter meets load R, and the voltage at load R two ends is the output voltage V o of AC-DC converter.

Controller comprises former limit sample circuit and digital compensator; Former limit sample circuit gathers the auxiliary winding voltage signal V of AC-DC converter_sense, and according to the feedback quantity V of this signal output AC-DC converter current period_fB[i]; Digital compensator is according to the feedback quantity V of former limit sample circuit output_fB[i] constructs pwm signal, to control the break-make of switching tube Q in AC-DC converter.

Shown in Fig. 4 the basic waveform of AC-DC converter each signal of when work, wherein I_sfor output winding current; In the time that PWM is 1, switching tube Q is open-minded, former limit winding current I_prise gradually, transformer T is at former limit winding N_pupper stored energy, auxiliary winding voltage

for negative value (N_auxand N_pbe respectively the coil turn of auxiliary winding and former limit winding), output winding (is secondary winding N_s) both end voltage V_salso be negative voltage, now diode D turn-offs, the electric current I on output winding_sbe 0, load R is powered by output capacitance C.

In the time that PWM is 0, switching tube Q turn-offs, and diode D conducting, is stored in former limit winding N_pon energy be transferred to output winding, output winding current I_srise to rapidly peak I_sPrear beginning declines gradually, and descending slope is with output winding both end voltage V_srelevant.Work as I_sdo not drop to before zero,$V_{\mathrm{sense}}\left(t\right)=(V_p+V_D+I_s*R_p)\frac{N_{\mathrm{aux}}}{N_S},$Wherein: V_dthe pressure drop of diode D, R_pit is the dead resistance of wire and diode D.Work as electric current I_sthe null moment, V_d=0,

this moment point voltage is designated as knee voltage (knee voltage).Work as I_selectric current drops to after 0, due to not conducting of switching tube Q, and former limit winding N_pand can there is series resonance between the parasitic capacitance of switching tube Q, harmonic period is by former limit winding N_pthe parasitic capacitance size of inductance and switching tube Q determines, at this one-phase$V_{\mathrm{sense}}\left(t\right)=\frac{N_{\mathrm{aux}}}{N_S}{V}_o\cos \left(\frac{1}{\sqrt{L_m{C}_p}}t\right),$Wherein: L_mit is former limit winding inductance.

By

known, work as output winding current I at flex point place_sdrop to for 0 moment, V_sensewith output voltage V_orelation in direct ratio, therefore according to the V at this some place_sensethe feedback quantity calculating is the most accurate.

When Q turn-offs, output winding current I_sdrop to after 0, i.e. V_senseafter flex point, can enter resonance condition, the moment T occurring in flex point_kneefront and back, V_senseslope variation be very large, for this feature, the present invention proposes a kind of control method of AC-DC converter output voltage, comprise the steps:

(1) the auxiliary winding voltage signal V of collection AC-DC converter_sense, and obtain the feedback quantity V in a cycle on AC-DC converter_fB[i-1]; Present embodiment is passed through resistance R₁and R₂to the auxiliary winding N of transformer T_auxthe voltage at two ends carries out dividing potential drop, therefore the auxiliary winding voltage signal V collecting_sensefor auxiliary winding N_auxthe voltage of both end voltage after step-down;

(2) to feedback quantity V_fBafter [i-1] digital-to-analogue conversion, obtainfeedback voltage V 1, and will after fixed voltage value of the amplitude lifting offeedback voltage V 1, obtain comparative voltage V2; In present embodiment, this fixed voltage value is 100mV;

(3) will assist winding voltage signal V_sensecompare withfeedback voltage V 1 and comparative voltage V2 respectively, obtain respectively two comparison signal V_s1and V_s2;

(4) calculate two comparison signal V_s1and V_s2trailing edge time difference Δ t, and by trailing edge time difference Δ t and fiducial time poor Δ t_refcompare, determine regulated quantity Δ V according to both differences_fB;

In present embodiment, differ from Δ t fiducial time_reffor 4clk, clk is a clock cycle; Δ t and Δ t_refdiffer larger, Δ V_fBalso larger; In present embodiment, | Δ t-Δ t_ref| with Δ V_fBconcrete determine that relation is as shown in table 1;

Table 1

|Δt-Δtref|	ΔVFB
		0clk	0
1clk	1
		2clk	2
3clk	3
		4clk	4

Wherein, if continuous several control cycle | Δ t-Δ t_ref| all larger, can suitably strengthen its corresponding regulated quantity.

Utilize regulated quantity Δ V by following feedback compensation algorithm_fBto feedback quantity V_fB[i-1] regulates compensation, in the hope of the feedback quantity V of AC-DC converter current period_fB[i];

As Δ t > Δ t_reftime: V_fB[i]=V_fB[i-1]-Δ V_fB

As Δ t=Δ t_reftime: V_fB[i]=V_fB[i-1]

As Δ t < Δ t_reftime: V_fB[i]=V_fB[i-1]+Δ V_fB

By select to set poor Δ t of suitable fixed voltage value and fiducial time in conjunction with actual parameter_ref, make to equal Δ t as Δ t_reftime, feedback quantity has just reacted needed knee voltage, to realize the automatic tracing to knee voltage and to realize accurate former limit sampling.

(5) according to feedback quantity V_fB[i] constructs pwm signal, to control the break-make of switching tube Q in AC-DC converter.

As shown in Figure 3, the controller of present embodiment AC-DC converter comprises former limit sample circuit and digital compensator; As shown in Figure 5, former limit sample circuit comprises a waveform real-time analysis module, a single-input double-output digital to analog converter and two comparators;

The input of single-input double-output digital to analog converter is connected with the output of waveform real-time analysis module, and two outputs are connected with the inverting input of two comparators respectively; The feedback quantity V in a cycle on the AC-DC converter of its reception waveform real-time analysis module output_fB[i-1], to feedback quantity V_fBafter [i-1] digital-to-analogue conversion, obtainfeedback voltage V 1 output, will after fixed voltage value of the amplitude lifting offeedback voltage V 1, obtain comparative voltage V2 output;

As shown in Figure 6, the single-input double-output digital to analog converter in present embodiment is by two MUX Mux1 and Mux2, and a string divider resistance R₁～R₅₁₁composition, R₁～R₅₁₁it is all substitutional resistance.Reference voltage V_refinput by the voltage after divider resistance dividing potential drop as MUX.There is an initial side-play amount in MUX Mux1 and Mux2 coding, by this digital to analog converter of this side-play amount by same input variable V_fBconvert two analog voltage V with fixed voltage difference to₁and V₂.In present embodiment, the figure place of digital-to-analogue conversion is 9, reference voltage V_reffor 1.2V; V₂and V₁with V_fBpass be:${\mathrm{<figure-callout\; label="V"\; filenames="HDA00002031934200021.png,HDA00002031934200041.png"\; state="\{\{state\}\}">V</figure-callout>}}_2=\frac{V_{\mathrm{FB}}+50}{511}*V_{\mathrm{ref}},$${\mathrm{<figure-callout\; label="V"\; filenames="HDA00002031934200041.png,HDA00002031934200051.png"\; state="\{\{state\}\}">V</figure-callout>}}_1=\frac{{\mathrm{<figure-callout\; label="V\; FB"\; filenames="HDA00002031934200041.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{FB}}}{511}*V_{\mathrm{ref}},$$\mathrm{\&Delta;V}=V_2-{\mathrm{<figure-callout\; label="V"\; filenames="HDA00002031934200041.png,HDA00002031934200051.png"\; state="\{\{state\}\}">V</figure-callout>}}_1=\frac{50}{511}*V_{\mathrm{ref}}=50\mathrm{LSB},$Visible V₁voltage is the feedback voltage of simulation.

The normal phase input end of two comparator C OMP1～COMP2 all receives the auxiliary winding voltage signal V of AC-DC converter_sense; It is respectively byfeedback voltage V 1 and comparative voltage V2 and auxiliary winding voltage signal V_sensecompare, obtain respectively two comparison signal V_s1and V_s2.

Two inputs of waveform real-time analysis module are connected with the output of comparator C OMP1～COMP2 respectively; It is for calculating two comparison signal V_s1and V_s2trailing edge time difference Δ t, and by trailing edge time difference Δ t and fiducial time poor Δ t_refcompare, determine regulated quantity Δ V according to both differences_fB, and then utilize regulated quantity Δ V by feedback compensation algorithm_fBto feedback quantity V_fB[i-1] regulates compensation, in the hope of the feedback quantity V of AC-DC converter current period_fB[i].

As shown in Figure 7, after PWM is zero level, V_sensebecome high voltage from negative voltage, V_s1and V_s2be turned to high level, afterwards along with V_sensedecline gradually, due to V2 voltage ratio, V1 is high, V_s2can be at t₁moment is first turned to low level, through V after the Δ t time_s1at t₂moment is turned to low level.The moment T that knee voltage occurs_kneefront and back, V_sensevariation slope differ greatly, therefore V₁and V₂be in V_senseon the Δ t difference that produces of diverse location very large.As shown in Fig. 7 (b), if V_fBbigger than normal, represent that the feedback voltage sampling is higher than knee voltage, V₂and V₁also can phase strain large, due to T_kneev before moment_sensedescending slope less, the Δ t now detecting is bigger than normal.As shown in Fig. 7 (c), if V_fBless than normal, the Δ t now detecting is very little.As shown in Fig. 7 (a), choose suitable Δ t_refwith Δ V, make to equal Δ t as Δ t_reftime, V_fBjust to have reacted needed knee voltage.

As shown in Figure 8, first waveform real-time analysis module detects and stores the Δ t time, then by itself and Δ t_refcompare, to the feedback quantity V in next cycle_fBadjust, wherein the V that obtains of i cycle_fBvalue is designated as V_fB[i].In order to accelerate V_fBfoundation, on the basic principle basis shown in Fig. 8 to V_fBadjusted value improve, V between the cycle of front and back_fBpass be V_fB[i+1]=V_fB[i] ± Δ V_eB, Δ t and default Δ t_refdiffer larger, regulated quantity Δ V_fBalso larger, concrete corresponding relation is because of different parameter setting differences.

The input of digital compensator is connected with the output of waveform real-time analysis module; It is for according to the feedback quantity V of the AC-DC converter current period of waveform real-time analysis module output_fB[i] regulates duty ratio d, and provide zero limit to realize the stability of system loop, comparing analog compensation does not need extra resistance capacitance to compensate, reduce the expense of the outer device of sheet, construct pwm signal according to duty ratio D simultaneously, to control the break-make of switching tube Q in AC-DC converter, realize the modulation to AC-DC converter output voltage.

In present embodiment, waveform real-time analysis module and digital compensator are all by the FPGA realization of programming.

Present embodiment, by gathering the auxiliary winding voltage signal of AC-DC converter, adopts the former limit of high accuracy Sampling techniques, and automatic tracing knee voltage, to obtain accurate feedback quantity; Calculate duty ratio according to feedback quantity, and output pwm signal corresponding to duty ratio is with the break-make of switching tube in control change device, finally realizes the modulation to converter output voltage, realizes voltage stabilizing output.

Present embodiment realizes at diode forward pressure drop V by the former limit of high accuracy Sampling techniques_dthe moment of being almost equal to zero is to V_sensesample.Get under fixed condition in peripheral parameter, calculating desirable feedback voltage is 883mV, the feedback voltage V obtaining by this implementation method₁for 890mV, feedback error is 7mV, and adopts general traditional sampling control method cannot eliminate diode current flow pressure drop V_dimpact, the feedback voltage 1V nearly that obtains of sampling, feedback error is 117mv nearly.Therefore by comparing with traditional sampling control technology, present embodiment feedback error has reduced 94%.

Claims (4)

Translated fromChinese

1.一种AC-DC变换器的控制方法，包括如下步骤：1. A control method for an AC-DC converter, comprising the steps of:（1）采集AC-DC变换器的辅助绕组电压信号V_sense，并获取AC-DC变换器上一周期的反馈量V_FB[i-1]；(1) Collect the auxiliary winding voltage signal V_sense of the AC-DC converter, and obtain the feedback value V_FB [i-1] of the previous cycle of the AC-DC converter;（2）对所述的反馈量V_FB[i-1]数模转换后得到反馈电压V1，并将反馈电压V1的幅值抬升一个固定电压值后得到比较电压V2；(2) The feedback voltage V1 is obtained after the digital-to-analog conversion of the feedback quantity V_FB [i-1], and the amplitude of the feedback voltage V1 is increased by a fixed voltage value to obtain a comparison voltage V2;（3）将所述的辅助绕组电压信号V_sense分别与反馈电压V1和比较电压V2进行比较，分别得到两个比较信号V_S1和V_S2；(3) Comparing the auxiliary winding voltage signal V_sense with the feedback voltage V1 and the comparison voltage V2 respectively to obtain two comparison signals V_S1 and V_S2 ;（4）计算出两个比较信号V_S1和V_S2的下降沿时间差Δt，并将下降沿时间差Δt与基准时间差Δt_ref进行比较，根据两者的差值确定调节量ΔV_FB，进而通过反馈补偿算法利用调节量ΔV_FB对反馈量V_FB[i-1]进行调节补偿，以求得AC-DC变换器当前周期的反馈量V_FB[i]；(4) Calculate the falling edge time difference Δt of the two comparison signals V_S1 and V_S2 , and compare the falling edge time difference Δt with the reference time difference Δt_ref , and determine the adjustment amount ΔV_FB according to the difference between the two, and then through feedback compensation The algorithm uses the adjustment quantity ΔV_FB to adjust and compensate the feedback quantity V_FB [i-1] to obtain the feedback quantity V_FB [i] of the current cycle of the AC-DC converter;所述的反馈补偿算法基于如下算式：The feedback compensation algorithm is based on the following formula:当Δt＞Δt_ref时：V_FB[i]=V_FB[i-1]-ΔV_FB；When Δt>Δt_ref : V_FB [i]=V_FB [i-1]-ΔV_FB ;当Δt=Δt_ref时：V_FB[i]=V_FB[i-1]；When Δt=Δt_ref : V_FB [i]=V_FB [i-1];当Δt＜Δt_ref时：V_FB[i]=V_FB[i-1]+ΔV_FB；When Δt<Δt_ref : V_FB [i]=V_FB [i-1]+ΔV_FB ;（5）根据所述的反馈量V_FB[i]构造出PWM信号，以控制AC-DC变换器中开关管的通断。(5) Construct a PWM signal according to the feedback value V_FB [i] to control the on-off of the switching tube in the AC-DC converter.2.一种AC-DC变换器的控制器，包括原边采样电路和数字补偿器；所述的数字补偿器用于根据原边采样电路输出的AC-DC变换器当前周期的反馈量V_FB[i]构造出PWM信号，以控制AC-DC变换器中开关管的通断；其特征在于：2. A controller of an AC-DC converter, comprising a primary side sampling circuit and a digital compensator; the digital compensator is used to output the feedback value V_FB of the current cycle of the AC-DC converter according to the primary side sampling circuit [ i] construct PWM signal, to control the on-off of switching tube in AC-DC converter; It is characterized in that:所述的原边采样电路包括一波形实时分析模块、一单输入双输出数模转换器和两个比较器；The primary side sampling circuit includes a waveform real-time analysis module, a single-input double-output digital-to-analog converter and two comparators;所述的单输入双输出数模转换器接收波形实时分析模块输出的AC-DC变换器上一周期的反馈量V_FB[i-1]，对反馈量V_FB[i-1]数模转换后得到反馈电压V1并输出，将反馈电压V1的幅值抬升一个固定电压值后得到比较电压V2并输出；The single-input and double-output digital-to-analog converter receives the feedback quantity V_FB [i-1] of the AC-DC converter in the last cycle output by the waveform real-time analysis module, and digital-to-analog conversion of the feedback quantity V_FB [i-1] Finally, the feedback voltage V1 is obtained and output, and the amplitude of the feedback voltage V1 is raised by a fixed voltage value to obtain a comparison voltage V2 and output;两个比较器分别将反馈电压V1和比较电压V2与AC-DC变换器的辅助绕组电压信号V_sense进行比较，分别得到两个比较信号V_S1和V_S2；The two comparators respectively compare the feedback voltage V1 and the comparison voltage V2 with the auxiliary winding voltage signal V_sense of the AC-DC converter, and obtain two comparison signals V_S1 and V_S2 respectively;所述的波形实时分析模块用于计算出两个比较信号V_S1和V_S2的下降沿时间差Δt，并将下降沿时间差Δt与基准时间差Δt_ref进行比较，根据两者的差值确定调节量ΔV_FB，进而通过反馈补偿算法利用调节量ΔV_FB对反馈量V_FB[i-1]进行调节补偿，以求得AC-DC变换器当前周期的反馈量V_FB[i]；The waveform real-time analysis module is used to calculate the falling edge time difference Δt of the two comparison signals V_S1 and V_S2 , compare the falling edge time difference Δt with the reference time difference Δt_ref , and determine the adjustment amount ΔV according to the difference between the two_FB , and then use the adjustment quantity ΔV_FB to adjust and compensate the feedback quantity V_FB [i-1] through the feedback compensation algorithm, so as to obtain the feedback quantity V_FB [i] of the current cycle of the AC-DC converter;所述的反馈补偿算法基于如下算式：The feedback compensation algorithm is based on the following formula:当Δt＞Δt_ref时：V_FB[i]=V_FB[i-1]-ΔV_FB；When Δt>Δt_ref : V_FB [i]=V_FB [i-1]-ΔV_FB ;当Δt=Δt_ref时：V_FB[i]=V_FB[i-1]；When Δt=Δt_ref : V_FB [i]=V_FB [i-1];当Δt＜Δt_ref时：V_FB[i]=V_FB[i-1]+ΔV_FB。When Δt<Δt_ref : V_FB [i]=V_FB [i−1]+ΔV_FB .3.根据权利要求2所述的AC-DC变换器的控制器，其特征在于：所述的单输入双输出数模转换器由两个多路选择器和一串分压电阻构建。3. The controller of the AC-DC converter according to claim 2, characterized in that: the single-input double-output digital-to-analog converter is constructed by two multiplexers and a series of voltage dividing resistors.4.根据权利要求2所述的AC-DC变换器的控制器，其特征在于：所述的波形实时分析模块和数字补偿器均通过FPGA编程实现。4. The controller of the AC-DC converter according to claim 2, characterized in that: the waveform real-time analysis module and the digital compensator are all realized by FPGA programming.

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