CN114337299B - Control system of secondary rectifying tube - Google Patents
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- CN114337299B CN114337299B CN202111584193.6A CN202111584193A CN114337299B CN 114337299 B CN114337299 B CN 114337299B CN 202111584193 A CN202111584193 A CN 202111584193A CN 114337299 B CN114337299 B CN 114337299B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The application discloses a control system of a secondary rectifying tube. The control system acquires the turn-off signal of the first switching tube according to the detection of the secondary side voltage of the transformer in the converter, and the turn-off signal of the secondary side rectifying tube is acquired by judging that the magnetic reset of the transformer is completed, and slope compensation is added to provide a certain advanced turn-off quantity for the secondary side rectifying tube so as to ensure the stability of the system. The control system is simple to realize, does not need isolation transmission of signals, and can effectively improve the power density of the converter.
Description
Technical Field
The application belongs to the technical field of converters, and particularly relates to a control system of a secondary rectifying tube in a double-clamp zero-voltage switching converter.
Background
The dual-clamp zero-voltage switching converter is an isolated DC/DC circuit topology and comprises first to fourth switching tubes Q 1 ～Q 4 And secondary rectifying tube Q 5 And a power transformer T with primary side connected toFirst switch tube Q 1 And a second switching tube Q 2 The other end is connected with a third switch tube Q 3 And a fourth switching tube Q 4 Between the two, one end of the secondary side of the transformer is connected with the output voltage v o And one end is connected with the secondary rectifying tube Q 5 。
For the case of small output current, the secondary rectifying tube Q 5 The diode is adopted for rectification, so that the control complexity of the converter can be effectively reduced; however, when the output current is larger, the conduction loss of the diode is larger, resulting in lower efficiency of the converter; in order to reduce the conduction loss of the diode, a switching tube with smaller conduction resistance can be used for replacing the diode, so that the efficiency of the converter can be improved.
Secondary rectifying tube Q 5 Control signal S of (2) 5 Can be generated by a primary side control circuit of the converter and transmitted to a secondary side through isolation; or may be independently generated by the secondary side by detecting the secondary side voltage or current. Secondary rectifying tube Q 5 Control signal S of (2) 5 And a third switching tube Q 3 Control signal S of (2) 3 Identical, and thus can be controlled by a third switching tube Q 3 Control signal S of (2) 3 And the data are transmitted to the secondary side through isolation. However, in order to realize signal isolation transmission, an isolation transformer is required to be adopted for transmission, and as the insulation voltage of the primary side and the secondary side increases, the volume of the isolation transformer increases sharply, which reduces the power density of the converter significantly. In addition, a secondary rectifying tube Q 5 The control signal of (2) can be generated by a secondary synchronous rectification controller, in particular by sampling a secondary rectifying tube Q 5 Drain-source voltage v of (2) ds Feeding it into synchronous rectification controller to produce secondary rectifying tube Q 5 Control signal S 5 . But in practical application, due to the secondary rectifying tube Q 5 The parasitic inductance of the package of the transistor is caused to cause the secondary rectifying tube Q during the conduction period, and the drain-source voltage contains the inductive voltage component introduced by the parasitic inductance of the package 5 The secondary side current is turned off in advance when the secondary side current does not drop to zero, and the secondary side current is rectified from the secondary side rectifying tube Q 5 The body diode of the converter flows through the capacitor, so that the conduction loss of the converter is increased and the efficiency is reduced.
Disclosure of Invention
The present application has been made in view of the above problems occurring in the prior art, and an object of the present application is to provide a control system for a secondary rectifying tube, which uses the characteristic of the power transformer that the voltage and the second are balanced in the cycle to generate a secondary rectifying tube Q on the secondary side of the transformer 5 Control signal S of (2) 5 Without isolation transfer of active clamp Q 3 Control signal S of (2) 3 The power density of the converter can be effectively improved.
The technical solution for realizing the purpose of the application is as follows: a control system for secondary rectifying tube of dual-clamp zero-voltage switching converter is composed of the first to fourth switching tubes and secondary rectifying tube, and a power transformer T with primary end connected between the first and second switching tubes and another end connected between the third and fourth switching tubes, and secondary end connected to output voltage v o One end of the system is connected with the secondary rectifying tube, and the system comprises S 1 Reproduction circuit, integral sampling circuit, volt-second balance detection circuit and S 5 A generating circuit; wherein the output voltage v of the converter o And drain voltage v of secondary rectifying tube d For this purpose, the inputs of the control system are all connected to S 1 Reproduction circuit, at the same time v d Also connected to the integral sampling circuit; integrated sampling signal v generated by an integrated sampling circuit sen And S is 1 Control signal S generated by reproduction circuit 11 The voltage-second balance detection circuit is connected to generate S 5 Shut-off signal S 5_off Further, S 5 Shut-off signal S 5_off And S is 1 Control signal S generated by reproduction circuit 11 Access S 5 Generating circuit, last S 5 The generating circuit generates a control signal S of the secondary rectifying tube 5 。
Further, the S 1 The reproduction circuit is used for reproducing the control signal S of the primary side first switching tube on the secondary side 1 The reproduced signal is denoted as S 11 。
Further, the saidS 1 The reproduction circuit comprises two signal input terminals, which are respectively output voltages v o And drain voltage v of secondary rectifying tube d The signal output end is the control signal S of the primary side first switch tube 1 Is a reproduction signal S of (1) 11 ，v o And v d Scaled to k by a scaling circuit i ·v o And k i ·v d Then respectively connected to the negative end and the positive end of the first comparator, the negative end of the first comparator passes through the resistor R bias1 Connected to a DC voltage source V bias1 Wherein k is i For scaling the coefficients.
Further, the integral sampling circuit is connected with the secondary side of the transformer in parallel.
Further, the integral sampling circuit is connected with the secondary rectifying tube in parallel.
Further, the integral sampling circuit comprises a first resistor, a second resistor and a first capacitor, wherein the first resistor and the first capacitor are connected in series, and the second resistor and the first capacitor are connected in parallel.
Further, the volt-second balance detection circuit comprises a first monostable trigger, a sampling switch tube, a sampling holding capacitor, a pull-up resistor and a second comparator, and comprises two signal input ends which are respectively output v of an integrating circuit sen And S is 1 Reproducing the output signal S of the circuit 11 Also comprises a signal output end, namely S 5 Turning off the signal; s is S 1 Reproducing the output signal S of the circuit 11 Connected to the input of the first monostable flip-flop, which fetches S 11 And output to the grid of the sampling switch tube; output v of integral sampling circuit sen The inverting input end of the second comparator is connected to the drain electrode of the sampling switch tube; the source electrode of the sampling switch tube is connected with one end of the sampling holding capacitor, the other end of the sampling holding capacitor is connected to the reference ground, and the common end of the source electrode of the sampling switch tube and the sampling holding capacitor is connected with the non-inverting input end of the second comparator; one end of the pull-up resistor is connected to the non-inverting input end of the second comparator, and the other end is connected to the bias voltage source V bias2 。
Further, the methodThe S is 5 The generating circuit comprises a second monostable trigger and an RS trigger which are provided with two signal input ends, namely an output signal S of the volt-second balance detecting circuit 5_off And S is 1 Reproducing the output signal S of the circuit 11 ，S 11 The falling edge of the second monostable trigger is taken out through the second monostable trigger and then connected to the setting end of the RS trigger, namely the S end, and the second monostable trigger is used for opening the secondary rectifying tube; s is S 5_off The signal is connected to the reset end, namely the R end, of the RS trigger and is used for turning off the secondary rectifying tube.
Compared with the prior art, the application has the remarkable advantages that:
1) The control signal of the secondary rectifying tube can be directly generated by the secondary, so that the control signal of the primary active clamping tube Q3 is prevented from being transmitted to the secondary to be led into circuits such as an isolation transformer, the space is saved, and the power density of the converter can be effectively improved.
2) The traditional synchronous rectification controller can lead to the problem that the secondary rectifying tube is turned off in advance due to the packaging parasitic inductance of the secondary rectifying tube, so that the conduction loss of the converter is increased, and the efficiency is reduced. The application does not have the problem of the advanced turn-off of the secondary rectifying tube, obtains the turn-off signal of the first switching tube according to the detection of the secondary voltage of the transformer in the converter, is used as the turn-on signal of the secondary rectifying tube, obtains the turn-off signal of the secondary rectifying tube by judging the completion of the magnetic reset of the transformer, and adds slope compensation to provide a certain advanced turn-off quantity for the secondary rectifying tube so as to ensure the stability of the system.
The application is described in further detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a block diagram of a primary-secondary control architecture for a dual clamp zero voltage switching converter in one embodiment.
FIG. 2 is a block diagram of the internal of a synchronous rectification controller in one embodiment.
FIG. 3 is a diagram of S in a synchronous rectification controller according to one embodiment 1 The circuit diagram is reproduced.
FIG. 4 is a diagram of S in a synchronous rectification controller according to one embodiment 1 A typical waveform diagram of the circuit is reproduced.
FIG. 5 is an embodimentThe integral sampling circuit diagram in the synchronous rectification controller is provided, wherein the diagram (a) is that the integral sampling circuit is connected with the secondary side of the transformer in parallel, and the diagram (b) is that the integral sampling circuit is connected with the secondary side rectifying tube Q 5 And are connected in parallel.
Fig. 6 is a diagram of a volt-second balance detection circuit in a synchronous rectification controller as provided in one embodiment.
FIG. 7 is a diagram of S in a synchronous rectification controller according to one embodiment 5 A signal generating circuit diagram.
Fig. 8 is a block diagram of a synchronous rectification controller implementation in one embodiment.
FIG. 9 is a diagram of simulated waveforms for control proposed in one embodiment.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
It should be noted that, if directional indications (such as up, down, left, right, front, and rear … …) are included in the embodiments of the present application, the directional indications are merely used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are correspondingly changed.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present application.
Fig. 1 shows a block diagram of a master controller and a synchronous rectification controller in a dual clamp zero voltage switching converter in accordance with an embodiment of the present application. The main controller has four signal input terminals for respectively inputting voltage V of the converter in First switch tube Q 1 And a second switching tube Q 2 Is set to the ground voltage v A Third switch tube Q 3 And a fourth switching tube Q 4 Is set to the ground voltage v B Clamp capacitor voltage v c The method comprises the steps of carrying out a first treatment on the surface of the The main controller is also provided with four signal output ends which are respectively a first switch tube Q 1 Second switch tube Q 2 Third switch tube Q 3 And a fourth switching tube Q 4 Control signal S of (2) 1 、S 2 、S 3 、S 4 The method comprises the steps of carrying out a first treatment on the surface of the The synchronous rectification controller has two signal input terminals for outputting voltage v o And secondary rectifying tube Q 5 Is the drain voltage v of (2) d . The synchronous rectification controller has a signal output terminal as a secondary rectifying tube Q 5 Control signal S of (2) 5 。
FIG. 2 shows an internal block diagram of a synchronous rectification controller in an embodiment of the application, specifically including S 1 Reproduction circuit, integral sampling circuit, volt-second balance detection circuit and S 5 A circuit is generated. Wherein the output voltage v o And secondary rectifying tube Q 5 Is the drain voltage v of (2) d The input ends of the control are all connected with S 1 Reproduction circuit, additionally v d And is also connected to the integral sampling circuit. Integrated sampling signal v generated by an integrated sampling circuit sen And S is 1 Control signal S generated by reproduction circuit 11 The S generated by the volt-second balance detection circuit is connected into the volt-second balance detection circuit 5 Shut-off signal S 5_off Further, S 5 Shut-off signal S 5_off And S is 1 Control signal S generated by reproduction circuit 11 Access S 5 Generating circuit, last S 5 The generating circuit generates a secondary rectifying tube Q 5 Control signal S of (2) 5 。
S 1 The reproduction circuit is used for reproducing the control signal S of the primary side first switching tube on the secondary side 1 The reproduced signal is namedS 11 . FIG. 3 shows S according to an embodiment of the present application 1 A reproduction circuit including two signal input terminals for respectively outputting voltage v o And secondary rectifying tube Q 5 Is the drain voltage v of (2) d The signal output end is the control signal S of the primary side first switch tube 1 Is a reproduction signal S of (1) 11 。
v o And v d Scaled to k by a scaling circuit i ·v o And k i ·v d Wherein k is i To scale the coefficient, connected to the negative and positive terminals of the comparator 1, respectively, the negative termination resistor R of the comparator 1 bias1 To DC voltage source V bias1 。S 1 Typical waveforms of the replica circuit are shown in fig. 4, when the dual clamp zero voltage switching converter operates in: 1) Energy storage stage: first switch tube Q 1 And a fourth switching tube Q 4 During the on period, the secondary rectifying tube Q 5 Is the drain voltage v of (2) d Equal to the output voltage v o And input voltage V in The sum of voltages folded to the secondary side, which is larger than the output voltage, the comparator 1 outputs a high level; 2) Energy transfer phase: second switch tube Q 2 And a third switching tube Q 3 During the on period, the secondary rectifying tube Q 5 Is the drain voltage v of (2) d Approximately zero, lower than the output voltage v o The comparator 1 outputs a low level; 3) Resonance stage: secondary rectifying tube Q 5 Is the drain voltage v of (2) d Gradually rise but the amplitude is always lower than the output voltage v o The comparator 1 outputs a low level; 4) And (3) a follow current stage: secondary rectifying tube Q 5 Is the drain voltage v of (2) d Equal to the output voltage v o However, since a certain bias voltage is superimposed on the negative side of the comparator 1, the comparator 1 outputs a low level. To sum up, the output S of the comparator 1 11 In the first switching tube Q only 1 The on period is set to high level, i.e. S 11 The primary side first switch tube Q is reproduced 1 Control signal S of (2) 1 。
To obtain a secondary rectifying tube Q 5 Control signal S of (2) 5 The moments of its rising and falling edges need to be acquired.
1) Acquisition S 5 Rising edge: with the first switching tube Q 1 And a fourth switching tube Q 4 Is turned off, the secondary rectifying tube Q 5 Is the drain voltage v of (2) d Gradually decrease when v d <v o At the time S 1 Reproducing the output signal S of the circuit 11 Low, if the output voltage v of the converter o Lower, can be considered as a secondary rectifying tube Q 5 Approximately realize soft switching when S 11 The falling edge of (1) can be used as the secondary rectifying tube Q 5 Control signal S of (2) 5 Rising edge of (2); if the output voltage v of the converter o Higher, can be to S 11 After a certain time delay is added, the falling edge of the capacitor is taken out as a secondary rectifying tube Q 5 Control signal S of (2) 5 Is provided for the rising edge of (a).
2) Acquisition S 5 Falling edge: the power transformer in the dual clamp zero voltage switching converter is volt-second balanced during each switching cycle. The double-clamp zero-voltage switching converter has four working phases, and the resonant phase time is short, so that the influence on the volt-second of the power transformer is small, and the volt-second of the power transformer in the follow current phase is unchanged, so that the power transformer can be approximately considered to realize volt-second balance in the input energy storage phase and the primary and secondary side energy transfer phase. In other words, the magnetic reset completion time of the power transformer is S 5 The turn-off moment.
In order to judge whether the magnetic reset of the power transformer is finished, the volt-second information of the power transformer needs to be acquired first, and therefore, the embodiment of the application introduces an integral sampling circuit to integrate the secondary side voltage of the transformer. FIG. 5 shows a specific implementation of the integral sampling circuit of the present embodiment, which is composed of a resistor R 1 ,R 2 And capacitor C 1 Constitution in which the resistor R 1 And capacitor C 1 Series connection of resistors R 2 And capacitor C 1 In parallel, and there is:
R 1 ·C 1 ＞＞T s
the integral sampling circuit can be directly usedIn parallel with the secondary side of the transformer, as shown in FIG. 5 (a), a secondary rectifying tube Q may be provided 5 In parallel, as shown in fig. 5 (b), the method shown in fig. 5 (b) is recommended. At this time, by adjusting R 1 And R is 2 Can adjust the capacitance C according to the proportion of 1 On DC voltage V dc ，V dc The expression of (2) is:
to avoid the capacitance C 1 The voltage on the circuit is too high to influence the signal processing of the subsequent circuit.
After obtaining the volt-second information of the power transformer, it is necessary to further determine when the magnetic reset of the power transformer is completed, for this purpose, the embodiment introduces a volt-second balance detection circuit, as shown in fig. 6, which is composed of a monostable trigger, a sampling switch tube, and a sampling holding capacitor C SH Pull-up resistor R bias2 DC voltage source V bias2 And a comparator 2. It comprises two signal input terminals, respectively the output v of the integrating circuit sen And S is 1 Reproducing the output signal S of the circuit 11 . In addition, it also includes a signal output terminal, i.e. S 5 The signal is turned off. S is S 1 Reproducing the output signal S of the circuit 11 Connected to the input of the monostable flip-flop, which fetches S 11 And output to the grid of the sampling switch tube; output v of integrating circuit sen A drain electrode connected to the sampling switch tube, and an inverting input terminal of the comparator 2; source electrode of sampling switch tube and sampling holding capacitor C SH One end of (C) is connected with the sample-and-hold capacitor SH The other end of the comparator is connected to the reference ground, and the connection point between the two is connected to the non-inverting input terminal of the comparator 2; resistor R bias2 One end is connected to the non-inverting input end of the comparator 2, and the other end is connected to a bias voltage source V bias2 。
At the beginning of the switching cycle, i.e. the first switching tube Q 1 Is turned on for time v sen Sample and hold, sample and hold capacitor C SH Is of voltage value v SH . Along with the firstA switch tube Q 1 And a fourth switching tube Q 4 Is conducted, the power transformer starts to magnetize, v sen Gradually increase, v sen >v SH The method comprises the steps of carrying out a first treatment on the surface of the When the first switch tube Q 1 And a fourth switching tube Q 4 After being turned off, the second switch tube Q 2 Third switch tube Q 3 And secondary rectifying tube Q 5 Starting to conduct, demagnetizing the power transformer, v sen Gradually decreasing. When v sen Reduced to v SH When the magnetic reset of the power transformer is completed, the output of the comparator 2 is set high, generating S 5 Is turned off by the off signal S 5_off . Notably, due to the sample-and-hold capacitance C SH Has certain leakage current, the load impedance is not infinite, and the voltage v of the sample-hold capacitor SH Will exhibit natural sag characteristics which will result in a secondary rectifying tube Q 5 Delay off. And Q is 5 In order to solve the above problem, the embodiment provides adding a pull-up resistor R bias2 Connected to a DC voltage source V bias2 By flowing through R bias2 The current of the sample-hold capacitor is compensated and the sample-hold capacitor is charged slowly, so that the voltage v of the sample-hold capacitor SH Exhibits rising characteristics such that the secondary rectifying tube Q 5 And the energy of the secondary side can be effectively prevented from reversely filling the primary side by a certain amount of early turn-off, and the stability of the system is improved.
S 5 The generating circuit is composed of a monostable trigger and an RS trigger, and has two signal input ends, namely an output signal S of the volt-second balance detecting circuit 5_off And S is 1 Reproducing the output signal S of the circuit 11 。S 11 The falling edge is taken out by the monostable trigger and then connected to the setting end (S end) of the RS trigger for switching on the secondary rectifying tube Q 5 ；S 5_off The signal is connected to the reset end (R end) of the RS trigger for turning off the secondary rectifying tube Q 5 . The circuit structure is shown in fig. 7.
In order to clearly describe the connection relation between the functional modules, fig. 8 shows a specific implementation circuit of the secondary rectifying tube control signal of the dual-clamp zero-voltage switching converter according to the embodiment of the application.
To further illustrate the effectiveness of the control system, fig. 9 shows a simulation waveform, which can be obtained from the figure, and the control method of the secondary rectifying tube according to the embodiment can be implemented in the first switching tube Q 1 And a fourth switching tube Q 4 After the turn-off, the secondary rectifying tube Q is rapidly turned on 5 The method comprises the steps of carrying out a first treatment on the surface of the At the same time at the secondary side current i s When the value is approximately 0, the secondary rectifying tube Q is turned off 5 Namely, the control mode of the secondary rectifying tube provided by the embodiment can accurately generate the secondary rectifying tube Q 5 Can solve the problem of primary and secondary side transmission of signals and secondary side rectifying tube Q in the prior art 5 Early turn-off problem.
In summary, the control system of the secondary rectifying tube provided by the application has the following advantages: the control signal of the secondary rectifying tube can be directly generated by the secondary side, thereby avoiding the third switching tube Q of the primary side 3 The control signal of the converter is transmitted to the secondary side to be led into circuits such as an isolation transformer, so that the space is saved, and the power density of the converter can be effectively improved. The traditional synchronous rectification controller can lead to the problem that the secondary rectifying tube is turned off in advance due to the packaging parasitic inductance of the secondary rectifying tube, so that the conduction loss of the converter is increased, and the efficiency is reduced. The control method provided by the embodiment does not have the problem of early turn-off of the secondary rectifying tube.
The technical scheme of the application is not limited to the embodiment, and all technical schemes obtained by modifying or equivalently replacing the technical scheme of the application are covered in the scope of the application.
Claims (8)
1. A control system for a secondary rectifier of a dual clamp zero voltage switching converter comprising a first switching tube (Q 1 ) Second switch tube (Q) 2 ) Third switch tube (Q) 3 ) Fourth switch tube (Q) 4 ) And secondary rectifying tube (Q) 5 ) And a power transformer T with primary side connected to the first switch tube (Q 1 ) And a second switchTube (Q) 2 ) The other end of the primary side of the power transformer T is connected with a third switching tube (Q 3 ) And fourth switching tube (Q) 4 ) Between the two, one end of the secondary side of the power transformer T is connected with the output voltage v o The other end of the secondary side of the power transformer T is connected with a secondary side rectifying tube (Q) 5 ) Wherein the control system comprises S 1 Reproduction circuit, integral sampling circuit, volt-second balance detection circuit and S 5 A generating circuit; wherein, the output voltage v of the dual-clamp zero-voltage switching converter o And secondary rectifying tube (Q) 5 ) Is the drain voltage v of (2) d S is connected to the input signals of the control system 1 Reproduction circuit with drain voltage v d Also connected to the integral sampling circuit; integrated sampling signal v generated by an integrated sampling circuit sen And S is 1 Control signal S generated by reproduction circuit 11 The voltage-second balance detection circuit is connected to generate a turn-off signal S 5_off Further, turn off signal S 5_off And S is 1 Control signal S generated by reproduction circuit 11 Access S 5 Generating circuit, last S 5 The generating circuit generates a secondary rectifying tube (Q) 5 ) Control signal S of (2) 5 ；
The S is 1 The reproduction circuit is used for reproducing the first switching tube (Q) at the secondary side of the power transformer T 1 ) Control signal S of (2) 1 The reproduced signal is recorded as a control signal S 11 ；
The S is 1 The reproduction circuit comprises two signal input ends respectively connected with the output voltage v o And secondary rectifying tube (Q) 5 ) Is the drain voltage v of (2) d The signal output end outputs a control signal S 11 Output voltage v o And drain voltage v d Scaled to k by a scaling circuit i ·v o And k i ·v d Then respectively connected to the negative end and the positive end of the first comparator, the negative end of the first comparator passes through the resistor R bias1 Connected to a DC voltage source V bias1 Wherein k is i For scaling the coefficients.
2. The control system of a secondary rectifier of claim 1 wherein the integral sampling circuit is connected in parallel with the secondary of the power transformer T.
3. Control system of a secondary rectifying tube according to claim 1, characterized in that the integral sampling circuit is integrated with the secondary rectifying tube (Q 5 ) And are connected in parallel.
4. A control system for a secondary side rectifier according to claim 2 or 3, wherein the integral sampling circuit comprises a first resistor R 1 A second resistor R 2 First capacitor C 1 Wherein the first resistor R 1 And a first capacitor C 1 In series, a second resistor R 2 And a first capacitor C 1 And are connected in parallel.
5. The control system of a secondary rectifier of claim 4 wherein said first resistor R 1 A second resistor R 2 First capacitor C 1 The following relationship exists:
R 1 ·C 1 ＞＞T s
wherein T is s The switching period f of the double-clamp zero-voltage switching converter s Is T s Is the inverse of (c).
6. The control system of a secondary rectifier of claim 5 wherein the first resistor R is adjusted 1 A second resistor R 2 Can adjust the first capacitance C 1 On DC voltage V dc ，V dc The expression is:
7. the control system of a secondary side rectifier according to claim 1, wherein the volt-second balance detection circuit comprises a first monostable trigger, a sampling switch tube, a sampling hold capacitor (C SH ) Pull-up resistor (R) bias2 ) And a second comparator including two signal input terminals respectively connected to the integrated sampling signals v of the integrated sampling circuit sen And S is 1 Control signal S of reproduction circuit 11 Also comprises a signal output end, namely a turn-off signal S 5_off ；S 1 Control signal S of reproduction circuit 11 Connected to the input of the first monostable flip-flop, which takes out the control signal S 11 And output to the grid of the sampling switch tube; integrated sampling signal v of integrated sampling circuit sen The inverting input end of the second comparator is connected to the drain electrode of the sampling switch tube; the source of the sampling switch tube and the sample-hold capacitor (C SH ) Is connected to one end of the sample-and-hold capacitor (C SH ) Is connected to the ground, the source of the sampling switch tube and the sample-and-hold capacitor (C SH ) One end of the second comparator is connected with the non-inverting input end of the second comparator; pull-up resistor (R) bias2 ) Is connected to the non-inverting input of the second comparator, and a pull-up resistor (R bias2 ) Is connected to a bias voltage source V bias2 。
8. The control system of a secondary side rectifier of claim 7 wherein S 5 The generating circuit comprises a second monostable trigger and an RS trigger which are provided with two signal input ends and are respectively connected with the turn-off signal S of the volt-second balance detecting circuit 5_off And S is 1 Control signal S of reproduction circuit 11 Control signal S 11 The falling edge is taken out by the second monostable trigger and then connected to the setting end of the RS trigger, namely the S end, for opening the secondary rectifying tube (Q 5 ) The method comprises the steps of carrying out a first treatment on the surface of the Shut-off signal S 5_off The signal is connected to the reset end of the RS trigger, namely the R end, for turning off the secondary rectifying tube (Q 5 )。
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