CN111525801A - Flyback converter and control method for realizing zero-voltage switch - Google Patents

Flyback converter and control method for realizing zero-voltage switch Download PDF

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CN111525801A
CN111525801A CN202010294752.9A CN202010294752A CN111525801A CN 111525801 A CN111525801 A CN 111525801A CN 202010294752 A CN202010294752 A CN 202010294752A CN 111525801 A CN111525801 A CN 111525801A
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current
forced
sampling
branch
voltage
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CN111525801B (en
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徐申
史小雨
孙乾坤
曹宇
李旭涛
孙伟锋
时龙兴
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Southeast University
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Southeast University
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    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a flyback converter and a control method for realizing zero-voltage switching, and belongs to the technical field of power generation, power transformation or power distribution. The flyback converter comprises a main circuit and a control circuit. The main circuit comprises a transformer, a primary winding of the transformer is connected with a first switching tube in series, a secondary winding of the transformer is connected with a second switching tube in series, a forced resonance winding is connected with a third switching tube and a forced resonance capacitor in series, and a sampling winding is connected with a resistor in series for voltage sampling; the control circuit is connected with the control end of the first switch tube on one hand and is used for controlling the on and off of the first switch tube; and on the other hand, the switch is connected with the control end of the third switching tube and is used for controlling the on and off of the third switching tube. This application can realize that the zero voltage of first switch tube switches on through switching on and turn-off of control third switch tube, compares in traditional flyback circuit, reduces switching loss by a wide margin, raises the efficiency.

Description

Flyback converter and control method for realizing zero-voltage switch
Technical Field
The invention relates to the technology of a switching power supply, in particular to a flyback converter and a control method for realizing zero-voltage switching, and belongs to the technical field of power generation, power transformation or power distribution.
Background
The flyback switching power supply is used as a digital-analog hybrid control system, and can be divided into two categories of analog control and digital control according to different implementation modes of a feedback control loop. Compared with an analog control flyback switching power supply, the digital control flyback switching power supply has the following two advantages: (1) strong reusability, high flexibility and convenient real-time monitoring; (2) the interference of electromagnetic noise introduced by dv/dt and di/dt values of the converter on the analog electric signals of the chip is continuously enhanced along with the increase of the switching frequency, and the digital chip has the capabilities of reducing stray signal interference (improving the anti-interference capability) and avoiding distortion of the analog signals. Therefore, the digital chip is widely applied to a high-end power supply with complex control, and the digital control mode is the mainstream control method of the high-frequency and high-efficiency switching power supply at present.
With the development of modern integration technology, the switching power supply device is designed and developed in a direction of being smaller and lighter. Meanwhile, theoretical analysis and practical experience show that the volume and the mass of components such as capacitors, inductors, transformers and the like used in the switching power supply are inversely proportional to the square root of the working frequency of the power supply. Therefore, the design of devices with smaller size and lighter weight inevitably requires increasing the operating frequency of the switching power supply.
However, the switching loss of the main power tube of the flyback switching power supply is larger and larger along with the increase of the operating frequency, which seriously affects the development of the switching power supply towards high frequency and high efficiency. Therefore, it is very important to reduce the switching loss of the main power tube of the flyback converter by a certain method.
The core part of the traditional flyback switching power supply is a flyback converter which adopts an optical coupler to realize the feedback and the electrical isolation of output voltage, but the current transmission ratio of the optical coupler is greatly influenced by temperature, and the sampling precision of the output voltage is influenced. In order to overcome the defect that the output voltage is fed back by the optical coupler, a primary side feedback control mode is adopted to directly sample from a primary side winding or an auxiliary winding to obtain an accurate output voltage signal, the optical coupler is removed, and meanwhile, the integration level is improved, and the cost and the power consumption are reduced.
The existing primary side feedback type flyback converter reduces the switching loss in a mode of conducting at the spontaneous resonance valley bottom, and has the defect of limited efficiency improvement effect in high-voltage input.
Disclosure of Invention
The invention aims to overcome the defects of the background technology and provides a flyback converter and a control method for realizing zero-voltage switching.
The invention adopts the following technical scheme for realizing the aim of the invention:
a novel flyback converter comprises a main circuit and a control circuit.
The main circuit comprises: the transformer, the first switch tube, the second switch tube, the third switch tube and the forced resonance capacitor. The transformer comprises a primary winding, a secondary winding, a forced resonance winding and a sampling winding. The primary winding is connected with the first switching tube in series to form a primary branch, and the primary branch is connected with an input power supply; the secondary winding is connected with a second switching tube in series to form a secondary branch, the second switching tube is a synchronous rectifier tube, and the conduction and the disconnection of the second switching tube are controlled by a synchronous rectifier control chip. The secondary side branch is connected with a load after passing through an output filter capacitor; a loop formed by connecting the forced resonance winding, the third switching tube and the forced resonance capacitor in series is a forced resonance branch, and the forced resonance branch is used for realizing zero-voltage switching; a loop formed by the sampling winding in series connection with the first sampling resistor and the second sampling resistor is a sampling branch circuit, voltages at two ends of the second sampling resistor are sampling voltages, and a capacitor connected with the second sampling resistor in parallel is used for filtering the sampling voltages.
The control circuit is used for carrying out constant voltage digital multi-mode control on the sampled primary side peak current and the sampled voltage, and specifically comprises the following steps: the device comprises a sampling circuit, a PI control module, a mode control module, a constant-voltage multi-mode control module and two driving modules. The sampling circuit collects an error signal of a current period, the control module obtains a control signal of the current period according to the error signal of the current period, the mode control module reads control mode information of the current period according to the error signal of the current period and the control signal of a previous period, the constant-voltage multi-mode control module generates primary side input direct-current voltage and control parameters corresponding to different control modes according to the control signal of the current period, the control mode information and voltages at two ends of the primary side current sampling resistor, the first driving module outputs a driving signal of the first switching tube according to the received control parameters corresponding to the different control modes, and the second driving module outputs a driving signal of the third switching tube according to the primary side input direct-current voltage to realize zero-voltage switching.
The control circuit controls the timely conduction and the disconnection of the third switching tube to realize zero voltage conduction, so that the switching loss is remarkably reduced, and the specific process is as follows:
after the first switch tube is switched off, energy is refracted to the secondary side branch and the forced resonance branch, the energy refracted to the secondary side enables the secondary side branch to be conducted, the primary side current is refracted to the secondary side according to ampere-turn ratio conservation, and the secondary side current is linearly reduced because the voltage at the two ends of the secondary side winding is clamped at a fixed value by the output voltage; the energy refracted to the forced resonance branch enables the freewheeling diode connected in parallel reversely on the third switching tube to be conducted, the energy is rapidly released, and the forced resonance capacitor is charged to the maximum value in the process. After the secondary side current drops to zero, the second switching tube is switched off, the output voltage loses the clamping effect on the voltage at the two ends of the secondary side winding, and the circuit enters a spontaneous resonance period, namely resonance occurs between the primary side inductor and the parasitic capacitor on the first switching tube. The third switch tube is conducted in the spontaneous resonance period, the forced resonance capacitor charges the forced resonance winding, the capacitance value of the forced resonance capacitor is large and can be approximately equal to the voltage at two ends of the capacitor, therefore, the voltage at two ends of the forced resonance winding is clamped to the maximum value by the forced resonance capacitor, the negative direction of the current of the forced resonance branch is linearly increased (the charging direction of the forced resonance capacitor is set to be positive), the third switch tube is turned off when the negative direction of the current of the forced resonance branch is increased to the maximum value, the current of the forced resonance branch is refracted to the primary side to continuously release the residual energy on the parasitic capacitor of the first switch tube, when the energy release is finished, namely the leakage source voltage of the first switch tube is equal to zero, the first switch tube is conducted to enter the next period, and at.
By adopting the technical scheme, the invention has the following beneficial effects: the forced resonance branch is added in the primary side topology of the flyback converter, the forced resonance branch enters a charging state after a primary side loop is turned off and is turned on to enter a discharging state after the self-resonance period of the converter is finished, the forced resonance current generated in the discharging state is refracted to the primary side to enable the exciting current to be reversely and linearly reduced, the purpose that the parasitic capacitance of the main switching tube quickly discharges to the exciting inductance is further achieved, the switching loss is greatly reduced while the ZVS of the flyback converter is achieved, the defects that the loss of the primary side flyback topology with the valley bottom conducted is reduced when high voltage is input and the improvement efficiency is limited are overcome, compared with the primary side active clamping flyback topology with the added MOS tube active device, the zero-voltage switching of the main switching tube is achieved with the lower device cost.
Drawings
Fig. 1 is a block diagram of a system structure of the novel flyback converter of the present application.
FIG. 2 is a steady state waveform diagram of the circuit key parameters of the present application.
Fig. 3 is a circuit diagram of the forced resonance branch circuit of the present application.
FIG. 4 is a frequency law graph of the constant voltage digital multi-mode control of the present application.
Fig. 5 is a voltage waveform diagram of a drain-source voltage of the first switch tube when the zero voltage conduction is realized.
The reference numbers in the figures illustrate: q1, Q2 and Q3 are first, second and third switch tubes, CFFRFor forced resonance capacitance, Np is primary winding, Ns is secondary winding, NFFRFor forced resonant winding, NZCDFor sampling the winding, CLTo output filter capacitors, RLFor the load, R1 and R2 are first and second sampling resistors, and Cz is a sampling branch capacitor.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the accompanying drawings. The topology and waveform diagrams presented in the figures are preferred embodiments of the present invention, but the embodiments that can be implemented in the present application are not limited to the embodiments listed in the present application. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Fig. 1 shows a block diagram of a system structure of the novel flyback converter disclosed in the present application, which includes a main circuit and a control circuit. The main circuit comprises a transformer, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a forced resonance capacitor CFFR. The transformer comprises a primary winding Np, a secondary winding Ns and a forced resonance winding NFFRAnd a sampling winding NZCD. The primary winding Np is connected with a first switching tube Q1 in series to form a primary branch, and the primary branch is connected with an input power supply; the secondary winding Ns is connected with the second switching tube Q2 in series to form a secondary branch circuit, and the secondary branch circuit passes through the output filter capacitor CLRear connection load RL(ii) a Forced resonance winding NFFRA third switching tube Q3 and a forced resonance capacitor CFFRA loop formed by the series connection is a forced resonance branch circuit which is used for realizing zero voltage switching; sampling winding NZCDThe loop formed by the first sampling resistor R1 and the second sampling resistor R2 in series is a sampling branch, and a sampling branch capacitor Cz connected with the second sampling resistor R2 in parallel is used for filtering the sampling voltage.
The control circuit samples primary side peak current and receives knee voltage Vsense sampled by the sampling branch circuit, the primary side peak current obtains Vcs through sampling electrons, and on-off control of the first switching tube Q1 and the third switching tube Q3 is achieved through constant-voltage digital multi-mode control.
The control circuit includes: the device comprises a sampling circuit, a PI control module, a constant-voltage multi-mode control module and two driving modules. The sampling circuit adopts a double-inflection point approximation sampling method, namely openThe characteristic that the slope change of the voltage of the oversampling winding is large before and after the knee voltage is used, two paths of voltages with fixed difference values are used for detecting the slope change, the knee voltage Vsense is automatically tracked, and the knee voltage and the output voltage V of the flyback converter are used0In a direct proportion relation with the total weight of the material,
Figure BDA0002451763980000041
therefore, accurate feedback of the output voltage can be realized, and the sampling circuit samples the knee voltage Vsense to obtain the error signal e (n) of the nth period. The PI control module obtains a control signal Vp _ c (n) of the nth period according to the error signal e (n) of the nth period. The mode judging module obtains a mode judging signal state (n) of the nth period according to the error signal e (n) of the nth period and the control signal Vp _ c (n-1) of the nth-1 period, wherein the state (n) 1 indicates that the control mode of the nth period is PWM, and the state (n) 2 indicates that the control mode of the nth period is PFM. The constant-voltage multimode control module obtains a primary sampling resistor R input to the driving module 0 according to the control signal Vp _ c (n) of the nth period and the mode judging signal state (n) of the nth periodCSThe two-terminal voltage peak value Vpeak or the switching period ts of the first switching tube, when the state (n) is equal to 1, the Vpeak is modified according to Vp _ c (n), and when the state (n) is equal to 2, the ts is modified according to Vp _ c (n); on the other hand, according to the voltage V across the primary sampling resistorCSObtaining an input DC voltage V to the drive module 1DC. The driving module 0 outputs a driving signal GD0 following Vpeak/ts to control the first switch tube Q1 to turn on and off. The output of the driving module 1 follows the input direct voltage VDCThe driving signal GD1 controls the on and off of the third switching tube Q3.
The circuit principle and the steady-state waveform of the novel flyback converter are analyzed in detail below, each switching period is divided into 5 time intervals, and the steady-state waveform is shown in fig. 2.
I) switching mode 1[ t3, t4]
At time t3, the main power transistor Q1 is turned on, i.e. GD0 is 1, and Q1 drain-source voltage VdsThe voltage across the primary winding is clamped to the rectified DC voltage V of the AC input to be 0DCSo primary side current iPLinearly rising due to the current in the other winding loop being0, so the excitation current iMagAlso rises linearly and at time i of t4MagUp to a maximum value.
II) switching mode 2[ t4, t5]
At time t4, the main power tube Q1 is turned off, that is, GD0 is 0, and the parasitic capacitance C on Q1OSSIs rapidly charged to the maximum value and clamped, the primary side loop is switched off, and the primary side current iPAnd the voltage polarity at the end with the same name is changed to be positive, and because the inductive current can not be suddenly changed, the primary current is refracted to the secondary branch and the forced resonance branch. At the time of t4, the primary current is refracted to the secondary branch, the synchronous rectifier Q2 is conducted, and the voltage at two ends of the secondary winding is clamped at V0(neglecting the Q2 conduction voltage drop), so the secondary current drops linearly, the excitation current drops linearly and the clamp voltage V0Refraction to the primary side results in VdsIs clamped to (V)DC+V0·NPNS)。
At the time t4, the primary current is refracted to the forced resonance branch, and the inductance current cannot change suddenly, and the Q3 is not conducted, so that the forced resonance current iffr(i.e., current i in fig. 3) is quickly released through a freewheeling diode connected in anti-parallel with Q3, as shown in fig. 3, during which the resonant capacitor C is forcedFFRIs charged to a maximum value, CFFRThe upper plate voltage of (2) is positive.
III) switching mode 3[ t5, t1] time period
At time t5, the secondary current drops to 0, the synchronous rectifier Q2 is turned off, and the output voltage V is0The voltage at the two ends of the secondary winding is not clamped, and a filter capacitor C is outputLCharging the load to keep the output voltage constant, the converter entering a spontaneous resonance period, exciting the inductor LPAnd Q1 parasitic capacitance COSSResonance occurs, so that the drain-source voltage V of Q1dsIs a direct voltage V on the primary side loopDCThe superimposed amplitude is (V)0·NPNS) Of a resonance period T of
Figure BDA0002451763980000061
IV) [ t1, t2] time period
At the time t1, the Q3 tube is conducted to force the resonant capacitor CFFRDischarging to the forced resonance winding, wherein the current direction is negative (the current positive direction is the direction i in the figure 3); and because of the forced resonance capacitance CFFRThe capacitance value is large and can be approximated as that two ends of the forced resonance winding are VCFFRClamping, so that the excitation current increases linearly in the reverse direction, and voltage folding of both ends of the clamped forced resonant winding to the primary side results in VdsIs also clamped to a maximum value.
V) [ t2, t3] time period
At the time of t2, when the exciting current reaches the negative peak value, Q3 is turned off, the converter enters a dead zone, the voltage at the end of the resonant winding with the same name is forced to change from negative in the reverse direction, the direction of the forced resonant current is negative, and the current is refracted to the primary side and is also negative (i.e., -iP) Due to a negative current (-i)P) The parasitic capacitance C of the Q1 can be largerOSSThe energy on the magnetic field is quickly released to the excitation inductor LPTherefore V isdsAnd rapidly decreases. t3 time VdsWhen the voltage drops to 0, the main power transistor Q1 is turned on to enter the next cycle. And to realize COSSThe residual energy is completely released at the dead zone end moment, and the turn-on and turn-off moments of the Q3 need to be accurately controlled.
From the above, it can be known that the flyback converter is a constant voltage multi-mode digital control, and the frequency law thereof is shown in fig. 4. Wherein, PWM and DPWM refer to pulse width modulation; PFM refers to pulse frequency modulation. Thus, in any load situation, the operating frequency fs of the converter is known, i.e. the period ts is also known. Therefore, if the Q3 tube conduction time t can be determinedGD1onAnd dead time t after Q3 is turned offdeadThen, through the formula (ts-t)GD1on-tdead) The conduction time of the Q3 tube (i.e., the value of t 1) can be obtained. Wherein the above-mentioned "t 1-t2 time period" and "t 2-t3 time period" are tGD1onAnd tdead。
As shown in fig. 3, the voltage across the resonant winding is forced to be clamped in the time period t1-t2, the exciting current is increased linearly in the negative direction, and the voltage across the inductor can be calculated according to the formula
Figure BDA0002451763980000062
The current peak value of the forced resonant circuit at the time t2 is obtained, and the current at the time is refracted to the primary side, so that the negative peak value of the current at the primary side at the time can be obtained according to the conservation of ampere-turn ratio
Figure BDA0002451763980000071
V is known from the description of dead time determination after Q3 turns offdsThe formula of oscillation in the dead zone is then used
Figure BDA0002451763980000072
The primary side current value i at the time t2 is obtainedp2. Through ip1＝ip2The equation can be given by formula (1):
Figure BDA0002451763980000073
in the dead time, COSSRelease energy to LPExcitation inductance LPAnd Q1 parasitic capacitance COSSResonance occurs so that VdsThe resonance voltage is the DC voltage V on the primary loopDCSuperimposed amplitude of VDCOf a resonance period T of
Figure BDA0002451763980000074
According to the coordinates a (t2, V) shown in fig. 5DC+ V0 Np/Ns) and B (t3,0) can be calculated to obtain tdeadThe value of (C) is shown in the formula (2).
Figure BDA0002451763980000075
From the formula (2), tGD1onAnd tdeadIs equal to the input voltage VDCIs related to the size of the sample VDCThe need to add an analog-to-digital converter ADC input to the control module results in a circuit that is not fully digitally controlled.
In the constant-voltage digital multi-mode algorithm adopted in the control circuit, the content of the primary side peak voltage Vcs is sampled by using a digital-to-analog converter DAC and a comparator to replace the ADC. Therefore, with Vcs known, V can be directly sampled in the control algorithm according to the formula when Q1 is onDCWithout adding extra devices, the formula when the Q1 is conducted is shown in formula (3), so that the circuit can realize complete digital control.
Figure BDA0002451763980000076
Thus, V is obtainedDCThen, t can be obtained by the formulas (1) and (2)GD1onAnd tdeadTo achieve precise control of the turn on and turn off of Q3, and thus achieve zero voltage turn on.
The foregoing is a more detailed description of the invention, taken in conjunction with the specific preferred embodiments thereof, and it is not intended that the invention be limited to these specific embodiments, as many variations of the embodiments of the invention are possible without departing from the spirit or scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (7)

1. A flyback converter, comprising:
the main circuit comprises a flyback transformer, a sampling branch circuit and a forced resonance branch circuit, wherein the sampling branch circuit and the forced resonance branch circuit are positioned on the primary side of the flyback transformer, the positive current direction of the forced resonance branch circuit is opposite to the primary side current, and the forced resonance branch circuit generates a forced resonance current opposite to the positive current direction after the spontaneous resonance period of the flyback transformer is finished until the exciting current reaches a negative peak value;
the control circuit is used for sampling the primary current peak value of the flyback transformer, receiving the knee voltage collected by the sampling branch circuit, extracting the error of the current period and control mode information from the knee voltage, generating a current period control signal according to the current period error, and generating a main switching tube driving signal following the control parameters in different control modes and a forced resonance branch circuit control signal following the primary current peak value.
2. The flyback converter of claim 1, wherein the forced resonant branch comprises a forced resonant inductor, a switching tube and a forced resonant capacitor, one end of the forced resonant inductor is connected to a positive plate of the forced resonant capacitor, a negative plate of the forced resonant capacitor is commonly grounded with a source of the switching tube, a drain of the switching tube is connected to the other end of the forced resonant inductor, a backward diode is connected between the source and the drain of the switching tube, a gate of the switching tube is connected to a control signal of the forced resonant branch, and one end of the forced resonant inductor connected to the positive plate of the forced resonant capacitor is a dotted end with a current outflow end of a primary winding of the flyback transformer.
3. The flyback converter of claim 1 wherein the sampling branch is configured to sample the knee voltage using a two-knee approach sampling method, the sampling branch comprising: the sampling circuit comprises a sampling winding, a first sampling resistor, a second sampling resistor and a sampling branch capacitor, wherein the sampling winding, the first sampling resistor and the second sampling resistor are sequentially connected in series to form a loop, and the sampling branch capacitor is connected to two ends of the second sampling resistor in parallel.
4. The flyback converter of claim 1, wherein the main switching tube driving signals that follow the control parameters in different control modes include, but are not limited to, main switching driving signals that follow peak sampling values of primary current of the flyback transformer in the PWM mode, and main switching driving signals that follow the operating frequency of the flyback converter in the PFM mode.
5. A flyback converter as claimed in claim 1, wherein the control circuit comprises:
the sampling circuit receives the knee voltage collected by the sampling branch circuit, extracts the error of the current period from the knee voltage,
a PI control module for generating a current period control signal according to the current period error,
a mode judging module for judging the control mode information of the current period according to the current period error and the control signal of the previous period,
the constant voltage multi-mode control module receives the peak value sampling value of the primary side current of the flyback transformer, generates control parameters under different control modes according to the control signal and the control mode information of the current period, extracts the primary side input direct current voltage from the peak value sampling value of the primary side current of the flyback transformer,
the first driving module receives the control parameters under different control modes, generates a main switching tube driving signal following the control parameters under different control modes, and;
and the second driving module receives the primary side input direct-current voltage and generates a forced resonance branch control signal following the primary side current peak value.
6. The flyback converter of claim 5, wherein the forced resonant branch control signal generated by the second driver module according to the received primary input DC voltage and following the peak of the primary current comprises an on-time of the forced resonant branch switch and a dead time after the forced resonant branch switch is turned off, and the on-time of the forced resonant branch switch is expressed according to the expression
Figure FDA0002451763970000021
Determining the dead time after the forced resonance branch switch is turned off according to the expression
Figure FDA0002451763970000022
Determining where tGD1on、tdeadFor the conduction time and dead time after switching-off of the forced resonant branch switch, LpIs the inductance value, C, of the primary inductor of the flyback transformerOSSIs the capacitance value of the parasitic capacitor of the main switch tube, NP、NSIs the number of turns of primary and secondary windings of the flyback transformer, VDCFor primary side input of DC voltage, V0Is the output voltage of the flyback transformer.
7. A control method for realizing zero-voltage switching of the flyback converter as claimed in any of the claims 1 to 6, it is characterized in that a main switch tube on a primary side branch of a flyback transformer is initialized to be in a conducting state, the main switch tube is turned off when an exciting current rises to a peak value, a synchronous rectifier tube on a secondary side branch of the flyback transformer is conducted, a secondary side current starts to fall, the primary side current is refracted to a forced resonance branch at the moment when the main switch tube is turned off, the forced resonance branch enters a charging state, the synchronous rectifier tube is turned off when the secondary side current of the flyback transformer falls to 0, a flyback converter enters a self-resonance period, the forced resonance branch circuit switch is initialized to be conducted at the moment when the self-resonance period is finished, the forced resonance branch circuit enters a discharge state to generate a forced resonance current, and after the forced resonance current is refracted to the primary side, the primary side current increases reversely, and the forced resonance branch switch is turned off when the primary side current increases reversely to a peak value.
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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112019060A (en) * 2020-08-28 2020-12-01 东莞市大忠电子有限公司 Vehicle-mounted AC/DC quick-charging power adapter circuit
CN112117744A (en) * 2020-09-18 2020-12-22 广东得语健康科技有限公司 Residual voltage relief device
CN112468006A (en) * 2020-10-30 2021-03-09 苏州力生美半导体有限公司 Flyback switching power supply resonance EMI optimization circuit and method
CN113193758A (en) * 2021-05-06 2021-07-30 东南大学 Forced resonance flyback converter and zero-voltage switch self-adaptive control method
CN113659837A (en) * 2021-07-05 2021-11-16 华为技术有限公司 Converter, converter control method and power adapter
TWI748777B (en) * 2020-12-02 2021-12-01 遠東科技大學 Dc power converter with step-up and step-down voltage conversion functions
CN113992018A (en) * 2021-09-30 2022-01-28 昂宝电子（上海）有限公司 Quasi-resonance switching power supply and control chip and control method thereof
CN114400899A (en) * 2020-11-16 2022-04-26 上海百功半导体有限公司 Novel zero-voltage switching control circuit and method and voltage converter
CN115208204A (en) * 2022-07-21 2022-10-18 深圳宝砾微电子有限公司 Flyback converter and control method thereof
WO2023020051A1 (en) * 2021-08-17 2023-02-23 华为数字能源技术有限公司 Resonant converter, control method for resonant converter, and power adapter
WO2024125262A1 (en) * 2022-12-15 2024-06-20 华为技术有限公司 Switching power supply circuit, switching power supply, electronic device and power supply system

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101925237A (en) * 2010-08-20 2010-12-22 杭州电子科技大学 Primary constant-current control device of isolated type flyback converter
CN104660054A (en) * 2015-02-11 2015-05-27 东南大学 Pulse hopping mode PSM control method suitable for primary side feed-back fly-back converter
CN105375783A (en) * 2015-11-13 2016-03-02 广州金升阳科技有限公司 Feedback control method, feedback control method based control method for asymmetric half bridge type flyback converter, and realization circuits for two methods
US9899931B1 (en) * 2016-10-25 2018-02-20 Alpha And Omega Semiconductor Incorporated Zero voltage switching flyback converter for primary switch turn-off transitions
CN110611431A (en) * 2019-09-30 2019-12-24 东南大学 Primary side regulation control system and control method of active clamp flyback converter
CN110677046A (en) * 2019-09-23 2020-01-10 东南大学 Peak current mode digital control system and method for flyback power supply in DCM (discontinuous conduction mode)

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101925237A (en) * 2010-08-20 2010-12-22 杭州电子科技大学 Primary constant-current control device of isolated type flyback converter
CN104660054A (en) * 2015-02-11 2015-05-27 东南大学 Pulse hopping mode PSM control method suitable for primary side feed-back fly-back converter
CN105375783A (en) * 2015-11-13 2016-03-02 广州金升阳科技有限公司 Feedback control method, feedback control method based control method for asymmetric half bridge type flyback converter, and realization circuits for two methods
US9899931B1 (en) * 2016-10-25 2018-02-20 Alpha And Omega Semiconductor Incorporated Zero voltage switching flyback converter for primary switch turn-off transitions
CN110677046A (en) * 2019-09-23 2020-01-10 东南大学 Peak current mode digital control system and method for flyback power supply in DCM (discontinuous conduction mode)
CN110611431A (en) * 2019-09-30 2019-12-24 东南大学 Primary side regulation control system and control method of active clamp flyback converter

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112019060A (en) * 2020-08-28 2020-12-01 东莞市大忠电子有限公司 Vehicle-mounted AC/DC quick-charging power adapter circuit
CN112117744A (en) * 2020-09-18 2020-12-22 广东得语健康科技有限公司 Residual voltage relief device
CN112468006A (en) * 2020-10-30 2021-03-09 苏州力生美半导体有限公司 Flyback switching power supply resonance EMI optimization circuit and method
CN114400899A (en) * 2020-11-16 2022-04-26 上海百功半导体有限公司 Novel zero-voltage switching control circuit and method and voltage converter
TWI748777B (en) * 2020-12-02 2021-12-01 遠東科技大學 Dc power converter with step-up and step-down voltage conversion functions
CN113193758A (en) * 2021-05-06 2021-07-30 东南大学 Forced resonance flyback converter and zero-voltage switch self-adaptive control method
CN113193758B (en) * 2021-05-06 2022-04-12 东南大学 Forced resonance flyback converter and zero-voltage switch self-adaptive control method
CN113659837A (en) * 2021-07-05 2021-11-16 华为技术有限公司 Converter, converter control method and power adapter
CN113659837B (en) * 2021-07-05 2023-08-04 华为数字能源技术有限公司 Converter, converter control method and power adapter
WO2023020051A1 (en) * 2021-08-17 2023-02-23 华为数字能源技术有限公司 Resonant converter, control method for resonant converter, and power adapter
CN113992018A (en) * 2021-09-30 2022-01-28 昂宝电子（上海）有限公司 Quasi-resonance switching power supply and control chip and control method thereof
CN113992018B (en) * 2021-09-30 2023-12-26 昂宝电子（上海）有限公司 Quasi-resonant switching power supply, control chip and control method thereof
CN115208204A (en) * 2022-07-21 2022-10-18 深圳宝砾微电子有限公司 Flyback converter and control method thereof
CN115208204B (en) * 2022-07-21 2023-09-22 深圳宝砾微电子有限公司 Flyback converter and control method thereof
WO2024125262A1 (en) * 2022-12-15 2024-06-20 华为技术有限公司 Switching power supply circuit, switching power supply, electronic device and power supply system

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