CN112994464A - Flyback switching circuit and control method thereof - Google Patents
Flyback switching circuit and control method thereof Download PDFInfo
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- CN112994464A CN112994464A CN202110170744.8A CN202110170744A CN112994464A CN 112994464 A CN112994464 A CN 112994464A CN 202110170744 A CN202110170744 A CN 202110170744A CN 112994464 A CN112994464 A CN 112994464A
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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
- 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
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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Abstract
The invention discloses a flyback switch circuit and a control method thereof, wherein a bias voltage signal larger than zero is set and used for controlling the turn-off time of a first switch tube in the flyback switch circuit so that the drain-source voltage of a main power switch tube of the flyback switch circuit is consistent with the bias voltage signal before the main power switch tube is turned on, thereby reducing the turn-on power consumption of the main power switch tube and improving the system efficiency.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a flyback switching circuit and a control method thereof.
Background
The flyback switching circuit comprises a main power switching tube, energy is provided for a load through the conduction and the closing of the main power switching tube, the switching control of the main power switching tube is the control core of the switching circuit, and how to effectively control the switching state of the main power switching tube is a very challenging task.
In the active clamping flyback switching power supply in the prior art, a clamping capacitor is connected between a drain electrode and an input end of a main power switching tube, and a clamping switching tube is connected between the drain electrode and the capacitor of the main power switching tube, the clamping switching tube is conducted at a certain time during the turn-off period of the main power switching tube, the clamping switching tube is not conducted during the turn-on period of the main switching tube, after the conduction of the clamping switching tube, a primary side winding can generate a negative magnetizing current, the drain electrode voltage of the main power switching tube can be reduced along with the negative magnetizing current, then the clamping switching tube is controlled to be turned off, the main power switching tube is conducted, the conduction loss of the main power switching tube can be reduced, but the prior art does not accurately control the turn-off time of the clamping switching tube before the main power switching tube is turned on, when the main power switching tube is turned on, the voltage of the common, if the main power switch tube is turned on, the whole power supply system has larger energy loss, and the system efficiency is influenced.
Disclosure of Invention
In view of this, the present invention provides a flyback switching circuit that reduces the turn-on loss of a main power switch tube by adjusting the turn-off time of a first switch tube, and solves the technical problems of large turn-on loss of the main power switch tube and low system efficiency of the flyback switching circuit in the prior art.
The technical solution of the present invention is to provide a flyback switching circuit, including a main power switching tube, a transformer and a secondary rectifier tube, where the transformer includes a primary winding and a secondary winding, the main power switching tube is connected to the primary winding, and the secondary rectifier tube is connected to the secondary winding, and the flyback switching circuit further includes: the primary side switch control unit and the first switch tube are used for adjusting the drain-source voltage of the main power switch tube, the switch control unit controls the switch states of the main power switch tube and the first switch tube, the switch control unit comprises a bias voltage circuit and a turn-off adjusting circuit,
the bias voltage circuit outputs a bias voltage signal larger than zero, and the turn-off regulating circuit receives the bias voltage signal and regulates the turn-off time of the first switching tube according to the bias voltage signal so as to control the voltage of the main power switching tube at the turn-on time.
Preferably, the turn-off adjusting circuit adjusts a turn-off time of the first switching tube, so that before the main power switching tube is turned on, a drain-source voltage of the main power switching tube is consistent with the bias voltage signal.
Preferably, the bias voltage circuit outputs a bias voltage signal of a predetermined value, the predetermined value being greater than zero.
Preferably, the bias voltage circuit outputs an adjustable bias voltage signal, and the voltage value of the adjustable bias voltage signal is greater than zero.
Preferably, the bias voltage circuit receives an input voltage of the flyback switching circuit, and the adjustable bias voltage signal is proportional to the input voltage.
Preferably, the flyback switch circuit includes a first capacitor and a clamp switch tube, the first capacitor and the clamp switch tube are connected in series between a high potential end of an input power source of the flyback switch circuit and a common node of the main power switch tube and the primary winding, the clamp switch tube is used as the first switch tube, or the flyback switch circuit includes an auxiliary winding, an auxiliary switch tube and an auxiliary capacitor, which are coupled with the transformer, the auxiliary winding, the auxiliary switch tube and the auxiliary capacitor are connected in series to form a loop, and the auxiliary switch tube is used as the first switch tube.
Preferably, the switch control unit includes a turn-off control circuit,
the turn-off control circuit receives a first voltage signal representing the current of the primary winding, compares the first voltage signal with a first reference voltage signal, and takes a comparison result as a reset signal for controlling the turn-off of the first switching tube.
Preferably, the turn-off regulating circuit includes a voltage detecting circuit and an adjusting circuit,
the voltage detection circuit receives the bias voltage signal, detects the node voltage of the main power switch tube, outputs a voltage detection signal according to the node voltage of the main power switch tube and the bias voltage signal,
the adjusting circuit is electrically connected with the turn-off control circuit and the voltage detection circuit, and adjusts the turn-off time of the first switch tube according to the voltage detection signal.
Preferably, the turn-off adjustment circuit includes a voltage detection circuit and a threshold adjustment circuit,
the voltage detection circuit receives the bias voltage signal, detects the node voltage of the main power switch tube, outputs a voltage detection signal according to the node voltage of the main power switch tube and the bias voltage signal,
the threshold adjusting circuit is electrically connected with the voltage detection circuit and the turn-off control circuit, and adjusts the magnitude of the first reference voltage signal according to the voltage detection signal, so that the turn-off time of the first switching tube is adjusted.
The invention also discloses a control method of the flyback switching circuit, the flyback switching circuit comprises a main power switching tube, a transformer, a secondary side rectifier tube and a first switching tube used for adjusting the drain-source voltage of the main power switching tube, wherein the control method comprises the following steps:
according to a first voltage signal representing the current of a primary winding of the transformer, comparing the first voltage signal with a first reference voltage signal, and taking a comparison result as a reset signal for controlling the first switching tube to be switched off;
and outputting a bias voltage signal larger than zero, and adjusting the turn-off time of the first switching tube according to the bias voltage signal so as to control the on-time voltage of the main power switching tube.
Preferably, the turn-off time of the first switch tube is adjusted, so that before the main power switch tube is turned on, the drain-source voltage of the main power switch tube is consistent with the bias voltage signal.
Preferably, the bias voltage signal is output at a predetermined value, the predetermined value being greater than zero.
Preferably, an input voltage of the flyback switch circuit is received, and an adjustable bias voltage signal is output, where a voltage value of the adjustable bias voltage signal is greater than zero and is in a proportional relationship with the input voltage.
Preferably, the node voltage of the main power switch tube is detected, and a voltage detection signal is output according to the bias voltage signal and the node voltage of the main power switch tube,
and receiving the comparison result and the voltage detection circuit, and adjusting the turn-off time of the first switching tube according to the voltage detection signal.
Preferably, the node voltage of the main power switch tube is detected, and a voltage detection signal is output according to the bias voltage signal and the node voltage of the main power switch tube,
and adjusting the magnitude of the first reference voltage signal according to the voltage detection signal so as to adjust the turn-off time of the first switching tube.
Compared with the prior art, the circuit structure provided by the invention has the advantages that the turn-off time of the first switching tube is adjusted by setting the bias voltage signal larger than zero, so that the drain-source voltage of the main power switching tube is a preset value larger than zero before the main power switching tube is turned on, the turn-on power consumption of the switching tube is reduced, and the system efficiency is improved.
Drawings
Fig. 1 is a circuit block diagram of a conventional flyback switching circuit;
fig. 2(a) is a circuit block diagram of a first embodiment of a switch control unit according to the present invention;
FIG. 2(b) is a circuit diagram of an embodiment of the switch control unit in FIG. 2 (a);
FIG. 3(a) is a circuit block diagram of a second embodiment of a switch control unit according to the present invention;
FIG. 3(b) is a circuit diagram of an embodiment of the switch control unit in FIG. 3 (a);
FIG. 4 is a waveform diagram illustrating operation of the circuit block diagram of FIG. 2;
fig. 5 is a circuit block diagram of another conventional flyback switching circuit.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.
In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale, which is only used for convenience and clarity to assist in describing the embodiments of the present invention.
Fig. 2 is a circuit block diagram of a conventional flyback switching circuit, fig. 2 is a circuit block diagram of an active clamp flyback switching circuit, fig. 2(a) is a circuit block diagram of a first embodiment of a switch control unit according to the present invention, and fig. 2(b) is a circuit diagram of an embodiment of the switch control unit in fig. 2 (a). Referring to fig. 2, 2(a) and 2(b), the circuit structure of the embodiment of the present invention is described, in which the flyback switching circuit in the embodiment of the present invention includes a main power switching tube MO, a transformer and a secondary rectifier, the transformer includes a primary winding and a secondary winding L2, the primary winding includes a magnetizing inductor L2MAnd a winding L1, wherein one power end (such as a drain end) of the main power switch tube is connected with the primary winding, the other power end (such as a source end) of the main power switch tube is grounded, and the secondary rectifier tube is connected with the secondary winding. The flyback switching circuit may further include a primary-side switching control unit 1 and a first switching tube, the first switching tube is used for adjusting drain-source voltage of the main power switching tube, and the switching control unit controls switching states of the main power switching tube and the first switching tube.
In one embodiment, the switch control unit may include a turn-off control circuit including a current calculating circuit 1-1, a comparing circuit 1-2, and an RD trigger, the current calculating circuit 1-1 receiving a voltage signal V of a first winding coupled to the primary windingBAnd a first voltage signal V1 representing the current of the primary winding is obtained by calculation, wherein, as shown in FIG. 2(b), a current calculation circuit calculates and obtains a first voltage signal V1 by using volt-second balance (charge and discharge integral balance on a capacitor C2), then a comparison circuit 1-2 (such as a comparator) compares the first voltage signal V1 with a first reference voltage signal Vref,the comparison result is used as a reset signal for controlling the clamp switch tube to be switched off, and the principle is as follows: when the main power switch tube MO is conducted, the clamp switch tube MAAt turn-off, magnetizing inductance LMThe voltage on is Vin-VSWWhen the main power switch tube MO is turned off, the clamp switch tube MAWhen turned on, LMAt a voltage of VABy means of LMUpper voltage (characterized by voltage V)B) Volt-second balance determination clamping switch tube MAThe turn-off instant of.
In one embodiment, the switch control unit 1 includes a bias voltage circuit 1-2 and a turn-off regulating circuit including a voltage detection circuit 1-4 and an adjustment circuit 1-5. The bias voltage circuit outputs a bias voltage signal delta V which is larger than zero; the voltage detection circuit receives the bias voltage signal DeltaV and detects the node voltage V of the main power switch tubeSWA voltage detection signal V2 is outputted, the adjusting circuit 1-5 is electrically connected with the turn-off control circuit and the voltage detection circuit, here, the adjusting circuit 1-5 is connected with the output end of the comparison circuit 1-2 and the output end of the voltage detection circuit 1-3, the adjusting circuit adjusts the clamping switch tube M according to the voltage detection signal V2AFor example, the effective time length of the comparison result is adjusted according to the voltage detection signal V2 to adjust the clamp switch tube MAThe turn-off instant of. In this embodiment, the adjusting circuits 1-5 and the RD flip-flops are configured as a logic control circuit, the output terminals of the adjusting circuits 1-5 are connected to the reset terminals of the RD flip-flops, and the set terminals of the RD flip-flops receive and control the clamp switch tube MAThe conducting signal can be generated by a suitable circuit, for example, a clamp switch M is formed according to the turn-off signal of the main power switchAThe conducting signal, not shown in FIG. 2, the logic control circuit outputs a signal VMAControl clamp switch tube MAThe switch state of (1).
In one embodiment, the bias voltage circuit outputs a bias voltage signal of a predetermined value, the predetermined value being greater than zero, e.g., the bias voltage signal Δ V is obtained by adding a voltage of a predetermined value magnitude to a zero voltage, where the bias voltage circuit can be implemented by an adder.
In another embodiment, the bias voltage circuit outputs an adjustable bias voltage signal having a voltage value greater than zero. The bias voltage circuit receives the input voltage of the flyback switch circuit, and the adjustable bias voltage signal is proportional to the input voltage, for example, Δ V is proportional to the input voltage, Δ V is K Vin, and K is a constant greater than zero and less than 1. Here, the bias voltage circuit may be implemented by a suitable circuit configuration, and the adjustable bias voltage signal Δ V is obtained by adding a zero voltage to a predetermined voltage value in a certain direct proportional relationship with the input voltage by an adder.
In one embodiment, the turn-off regulating circuit adjusts the turn-off time of the first switch tube, so that the drain-source voltage of the main power switch tube is consistent with the bias voltage signal before the main power switch tube is turned on. If the bias voltage signal Δ V is set to 100mv, the main power switch tube is turned on at the position where the drain-source voltage of the main power switch tube is adjusted to be 100mv, or the main power switch tube is turned on at the position where the drain-source voltage of the main power switch tube is adjusted to be K Vin, so that the loss of the system is controlled to be minimum, and the efficiency is controlled to be maximum.
The working process of the implementation of the invention is explained below with reference to the working waveform diagram of fig. 4: at time t1, main power switch MA is turned on and magnetizing inductor LMThe current IL on rises; by t2, main power switch MA is turned off and inductor L is magnetizedMThe upper current IL begins to decrease, and at some point after t2 is turned off, the clamp switch tube MAWhen conducting, the inductor L is magnetizedMThe current IL on starts to drop below zero; by time t3, when current IL reaches a first reference voltage signal, here characterized as reference current signal Iref, clamping switching tube MATurn-off, voltage V across drain and source of main power switch MASWBegins to drop to t4 time point, the voltage V between the two ends of the drain and the sourceSWEqual to the input voltage Vin, will then be onAnd the main power switch tube MO. Then in the current working period, the voltage detection circuit enables the voltage V between the two ends of the drain and the sourceSWComparing with the bias voltage signal Δ V (such as Vth in FIG. 4), when the voltage V is applied across the drain and sourceSWWhen deviation exists between the voltage and the bias voltage signal delta V, the clamping switch tube M is adjusted through a voltage detection signal V2ASuch as the dashed line in fig. 4, delays the turn-off time such that the voltage V across the drain and source at the turn-on time of the main power switch is in the next switching cycleSWIn accordance with the bias voltage signal Δ V.
Referring to fig. 3(a), a circuit block diagram of a second embodiment of the switch control unit according to the present invention is shown, and fig. 3(b) is a circuit diagram of an embodiment of the switch control unit shown in fig. 3 (a). In this embodiment, the topology of the flyback switching circuit is still exemplified by the switching circuit in fig. 1. In one embodiment, the switch control unit may include a turn-off control circuit including a current calculating circuit 1-1, a comparing circuit 1-2, and an RD flip-flop, the RD flip-flop is a logic control circuit, and the current calculating circuit 1-1 receives a voltage signal V of a first winding coupled to the primary windingBAnd calculating to obtain a first voltage signal V1 representing the current of the primary winding, wherein, as shown in FIG. 3(b), the current calculating circuit calculates to obtain a first voltage signal V1 by using volt-second balance (charge and discharge integral balance on a capacitor C2), and then compares the first voltage signal V1 with a first reference voltage signal Vref by a comparison circuit 1-2, and the comparison result is used as a reset signal for controlling the turning-off of the clamping switch tube.
In one embodiment, the turn-off regulating circuit comprises a voltage detecting circuit 1-4 and a threshold regulating circuit 1-6, wherein the voltage detecting circuit is the same as the voltage detecting circuit in the first embodiment, so that the voltage detecting circuit 1-4 receives the bias voltage signal and detects the node voltage of the main power switch tube by using the same label, and outputs a voltage detecting signal V2 according to the node voltage of the main power switch tube and the bias voltage signal; the threshold adjusting circuit 1-6 is electrically connected to the voltage detecting circuit 1-4 and the turn-off controlThe circuit, here, the threshold value regulating circuit 1-6 connects the output end of the voltage detection circuit 1-4 and the connection end of the first reference voltage signal Vref of the turn-off control circuit, and the threshold value regulating circuit regulates the magnitude of the first reference voltage signal according to the bias voltage signal, thereby adjusting the turn-off time of the clamp switch tube. Here, since the comparison result between the first voltage signal V1 and the first reference voltage signal Vref is a reset signal for controlling the clamp switch to turn off, adjusting the first reference voltage signal Vref may advance or delay the clamp switch to turn off. In the working process, according to the current working period, the voltage V between the two ends of the drain and the sourceSWThe result of comparison with the bias voltage signal Δ V regulates the first reference voltage signal Vref when the voltage V across the drain and source isSWWhen deviation exists between the voltage and the bias voltage signal delta V, the first reference voltage signal Vref is adjusted to be larger or smaller through the voltage bias signal, and therefore the clamping switch tube M is adjustedASuch that in the next switching period the voltage V across the drain and source isSWThe signal is consistent with the bias voltage signal delta V, and the working efficiency of the system is improved.
Fig. 5 is a circuit block diagram of another conventional flyback switching circuit. In the flyback switching circuit, the flyback switching circuit includes an auxiliary winding N coupled with the transformerZVSThe auxiliary winding, the auxiliary switching tube Sa and the auxiliary capacitor are connected in series to form a loop, a common connection end is grounded, and the auxiliary switching tube is used as the first switching tube. The flyback switching circuit of the fig. 5 embodiment is one example of another topology that may be controlled using the techniques disclosed herein.
Finally, the invention discloses a control method of a flyback switching circuit, wherein the flyback switching circuit comprises a main power switching tube, a transformer, a secondary side rectifier tube and a first switching tube for adjusting the drain-source voltage of the main power switching tube, and the control method comprises the following steps:
according to a first voltage signal representing the current of a primary winding of the transformer, comparing the first voltage signal with a first reference voltage signal, and taking a comparison result as a reset signal for controlling the first switching tube to be switched off;
and outputting a bias voltage signal larger than zero, and adjusting the turn-off time of the first switching tube according to the bias voltage signal so as to control the on-time voltage of the main power switching tube.
And adjusting the turn-off time of the first switch tube to ensure that the drain-source voltage of the main power switch tube is consistent with the bias voltage signal before the main power switch tube is turned on.
Wherein the bias voltage signal of a predetermined value is output, the predetermined value being greater than zero.
The flyback switching circuit comprises a flyback switching circuit, an adjustable bias voltage signal and a control circuit, wherein the input voltage of the flyback switching circuit is received, the adjustable bias voltage signal is output, and the voltage value of the adjustable bias voltage signal is larger than zero and is in proportional relation with the input voltage.
Wherein, the node voltage of the main power switch tube is detected, and a voltage detection signal is output according to the bias voltage signal and the node voltage of the main power switch tube,
and receiving the comparison result and the voltage detection circuit, and adjusting the turn-off time of the first switching tube according to the voltage detection signal.
Wherein, the node voltage of the main power switch tube is detected, and a voltage detection signal is output according to the bias voltage signal and the node voltage of the main power switch tube,
and adjusting the magnitude of the first reference voltage signal according to the voltage detection signal so as to adjust the turn-off time of the first switching tube.
The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.
Claims (10)
1. A flyback switching circuit comprises a main power switching tube, a transformer and a secondary rectifier tube, wherein the transformer comprises a primary winding and a secondary winding, the main power switching tube is connected with the primary winding, the secondary rectifier tube is connected with the secondary winding, and the flyback switching circuit further comprises:
the primary side switch control unit and the first switch tube are used for adjusting the drain-source voltage of the main power switch tube, the switch control unit controls the switch states of the main power switch tube and the first switch tube,
the switch control unit includes a bias voltage circuit and a turn-off adjustment circuit,
the bias voltage circuit outputs a bias voltage signal greater than zero,
the turn-off regulating circuit receives the bias voltage signal and adjusts the turn-off time of the first switching tube according to the bias voltage signal so as to control the voltage of the main power switching tube at the turn-on time.
2. The flyback switching circuit of claim 1,
and the turn-off regulating circuit regulates the turn-off time of the first switching tube, so that the drain-source voltage of the main power switching tube is consistent with the bias voltage signal before the main power switching tube is turned on.
3. The flyback switching circuit of claim 1,
the bias voltage circuit outputs a bias voltage signal of a predetermined value, the predetermined value being greater than zero.
4. The flyback switching circuit of claim 1,
the bias voltage circuit outputs an adjustable bias voltage signal, and the voltage value of the adjustable bias voltage signal is greater than zero.
5. The flyback switch circuit of claim 4, wherein the bias voltage circuit receives an input voltage of the flyback switch circuit, the adjustable bias voltage signal being proportional to the input voltage.
6. The flyback switching circuit of any of claims 1-5,
the flyback switching circuit comprises a first capacitor and a clamping switching tube, the first capacitor and the clamping switching tube are connected between a high potential end of an input power supply of the flyback switching circuit and a common node of the main power switching tube and the primary winding in series, the clamping switching tube is used as the first switching tube, or the flyback switching circuit comprises an auxiliary winding, an auxiliary switching tube and an auxiliary capacitor, the auxiliary winding, the auxiliary switching tube and the auxiliary capacitor are coupled with the transformer in series to form a loop, and the auxiliary switching tube is used as the first switching tube.
7. The flyback switching circuit of claim 6, wherein the switch control unit comprises a turn-off control circuit,
the turn-off control circuit receives a first voltage signal representing the current of the primary winding, compares the first voltage signal with a first reference voltage signal, and takes a comparison result as a reset signal for controlling the turn-off of the first switching tube.
8. The flyback switching circuit of claim 7, wherein the turn-off regulation circuit comprises a voltage detection circuit and a regulation circuit,
the voltage detection circuit receives the bias voltage signal, detects the node voltage of the main power switch tube, outputs a voltage detection signal according to the node voltage of the main power switch tube and the bias voltage signal,
the adjusting circuit is electrically connected with the turn-off control circuit and the voltage detection circuit, and adjusts the turn-off time of the first switch tube according to the voltage detection signal.
9. The flyback switching circuit of claim 7, wherein the turn-off regulation circuit comprises a voltage detection circuit and a threshold regulation circuit,
the voltage detection circuit receives the bias voltage signal, detects the node voltage of the main power switch tube, outputs a voltage detection signal according to the node voltage of the main power switch tube and the bias voltage signal,
the threshold adjusting circuit is electrically connected with the voltage detection circuit and the turn-off control circuit, and adjusts the magnitude of the first reference voltage signal according to the voltage detection signal, so that the turn-off time of the first switching tube is adjusted.
10. A control method of a flyback switching circuit comprises a main power switching tube, a transformer, a secondary rectifier tube and a first switching tube used for adjusting drain-source voltage of the main power switching tube, wherein the control method comprises the following steps:
according to a first voltage signal representing the current of a primary winding of the transformer, comparing the first voltage signal with a first reference voltage signal, and taking a comparison result as a reset signal for controlling the first switching tube to be switched off;
and outputting a bias voltage signal larger than zero, and adjusting the turn-off time of the first switching tube according to the bias voltage signal so as to control the on-time voltage of the main power switching tube.
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| CN202110170744.8A CN112994464A (en) | 2021-02-08 | 2021-02-08 | Flyback switching circuit and control method thereof |
| CN202111027281.6A CN114189156B (en) | 2021-02-08 | 2021-09-02 | Flyback switching circuit and control method thereof |
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| CN202110170744.8A CN112994464A (en) | 2021-02-08 | 2021-02-08 | Flyback switching circuit and control method thereof |
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| CN114089014A (en) * | 2022-01-21 | 2022-02-25 | 广东希荻微电子股份有限公司 | Drain-source voltage detection circuit and drain-source voltage detection method |
| US11876436B2 (en) | 2021-12-07 | 2024-01-16 | Halo Microelectronic International | Voltage detecting apparatus and method for switching power converters |
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| CN102664526B (en) * | 2012-05-15 | 2015-12-16 | 迈象电子科技（上海）有限公司 | The method of reverse excitation circuit and the loss of reduction reverse excitation circuit transformer leakage inductance |
| CN106059313B (en) * | 2016-07-19 | 2018-05-29 | 深圳南云微电子有限公司 | The circuit of reversed excitation and its control method of active clamp |
| CN107749716B (en) * | 2017-10-27 | 2023-06-23 | 杰华特微电子股份有限公司 | Flyback active clamp circuit and control method thereof |
| CN108988652A (en) * | 2018-09-10 | 2018-12-11 | 杰华特微电子（张家港）有限公司 | Flyback active clamp circuit and its control method |
| CN109245569B (en) * | 2018-09-18 | 2020-04-24 | 西安矽力杰半导体技术有限公司 | Flyback converter and control circuit thereof |
| CN113141118B (en) * | 2019-11-08 | 2023-04-28 | 矽力杰半导体技术(杭州)有限公司 | Control circuit and switching converter using same |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11876436B2 (en) | 2021-12-07 | 2024-01-16 | Halo Microelectronic International | Voltage detecting apparatus and method for switching power converters |
| CN114089014A (en) * | 2022-01-21 | 2022-02-25 | 广东希荻微电子股份有限公司 | Drain-source voltage detection circuit and drain-source voltage detection method |
| CN114089014B (en) * | 2022-01-21 | 2022-04-12 | 广东希荻微电子股份有限公司 | Drain-source voltage detection circuit and drain-source voltage detection method |
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| Publication number | Publication date |
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| CN114189156B (en) | 2024-05-24 |
| CN114189156A (en) | 2022-03-15 |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant before: JOULWATT TECHNOLOGY Inc.,Ltd. |
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Application publication date: 20210618 |