CN112198358B - Flyback converter input voltage secondary side detection circuit - Google Patents
Flyback converter input voltage secondary side detection circuit Download PDFInfo
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- CN112198358B CN112198358B CN202010931460.1A CN202010931460A CN112198358B CN 112198358 B CN112198358 B CN 112198358B CN 202010931460 A CN202010931460 A CN 202010931460A CN 112198358 B CN112198358 B CN 112198358B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage 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
- 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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
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- Dc-Dc Converters (AREA)
Abstract
The invention provides a flyback converter input voltage secondary side detection circuit, which comprises a primary side circuit and a secondary side circuit; the primary side circuit comprises a switching tube and a primary side winding; the secondary side circuit includes a secondary side first circuit, which includes: the homonymous end of the secondary side first winding is respectively connected with the anode of the first diode and the cathode of the third diode, and the synonym end of the secondary side first winding is respectively connected with the cathode of the second diode and the anode of the fourth diode; two ends of a filter circuit consisting of a first resistor, a second resistor and a first capacitor are respectively connected with the cathode of the first diode and the anode of the second diode. According to the invention, the input voltage of the secondary side of the flyback converter is detected by the input voltage detection circuit with simple structure and low cost by utilizing the voltage of the primary side winding of the transformer equal to the input voltage when the switching tube is switched on and the voltage proportional relation between the primary side first winding of the transformer and the primary side winding of the transformer.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to a flyback converter input voltage secondary side detection circuit.
Background
A flyback converter as a switching power supply (digital power supply) is an essential key component in modern electronic systems, and thus design of the switching power supply with low cost, high density, digitization, high efficiency, high reliability, and the like has been an important research subject.
A control chip of the flyback converter is generally disposed on a secondary side (also disposed on a primary side) of the flyback converter, and in order to implement an under-voltage and over-voltage protection function of an input voltage of a digital power supply, the following two methods are generally adopted at present:
firstly, the input voltage is transmitted to a secondary side through an input voltage detection circuit consisting of an isolation operational amplifier, but the method has the problems of large volume and high cost of the isolation operational amplifier;
secondly, input under-voltage and over-voltage detection is achieved on the primary side through the operational amplifier, and the control signal is transmitted to the secondary side through the optical coupler.
Disclosure of Invention
The invention provides a flyback converter input voltage secondary side detection circuit and a detection method, solves the problems in the prior art, and provides the flyback converter secondary side input voltage detection circuit which is simple in structure and low in cost.
One embodiment of the invention provides a flyback converter input voltage secondary side detection circuit, which comprises a primary side circuit and a secondary side circuit; wherein the content of the first and second substances,
the primary side circuit comprises a switching tube and a primary side winding; the secondary side circuit comprises a secondary side first circuit; wherein the content of the first and second substances,
the secondary-side first circuit, comprising:
the homonymous end of the secondary side first winding is respectively connected with the anode of the first diode and the cathode of the third diode, and the synonym end of the secondary side first winding is respectively connected with the cathode of the second diode and the anode of the fourth diode;
two ends of a filter circuit consisting of a first resistor, a second resistor and a first capacitor are respectively connected with the cathode of the first diode and the anode of the second diode; one end of the first resistor is connected to the cathode of the first diode, and the other end of the first resistor is connected to one end of the first capacitor; the other end of the first capacitor is connected to the anode of the second diode; the second resistor is connected with the first capacitor in parallel, and the voltage at two ends of the second resistor is the detection value of the input voltage of the primary circuit;
two ends of the second capacitor are respectively connected with the anode of the third diode and the cathode of the fourth diode;
the switching period of the switching tube is less than the product of the first capacitor and the second resistor, and the first resistor is less than the second resistor.
Further, the switch tube is a field effect tube enhanced N-MOS.
Further, the secondary side circuit further comprises a secondary side second circuit;
the secondary side second circuit includes:
the secondary side second winding is connected with a fifth diode and a third capacitor in series; and the homonymous end and the synonym end of the secondary side second winding are respectively connected with the anode of the fifth diode and one end of the third capacitor.
Furthermore, the connection end of the first capacitor and the second diode is grounded, and the connection end of the second capacitor and the third diode is grounded.
Compared with the prior art, the embodiment of the invention has the beneficial effects that:
one embodiment of the invention provides a flyback converter input voltage secondary side detection circuit, which comprises a primary side circuit and a secondary side circuit; the primary side circuit comprises a switching tube and a primary side winding; the secondary side circuit comprises a secondary side first circuit; wherein the secondary side first circuit comprises: the homonymous end of the secondary side first winding is respectively connected with the anode of the first diode and the cathode of the third diode, and the synonym end of the secondary side first winding is respectively connected with the cathode of the second diode and the anode of the fourth diode; two ends of a filter circuit consisting of a first resistor, a second resistor and a first capacitor are respectively connected with the cathode of the first diode and the anode of the second diode; one end of the first resistor is connected to the cathode of the first diode, and the other end of the first resistor is connected to one end of the first capacitor; the other end of the first capacitor is connected to the anode of the second diode; the second resistor is connected with the first capacitor in parallel, and the voltage at two ends of the second resistor is the detection value of the input voltage of the primary circuit; and two ends of the second capacitor are respectively connected with the anode of the three diodes and the cathode of the fourth diode. According to the invention, the input voltage of the secondary side of the flyback converter is detected by the input voltage detection circuit with simple structure and low cost by utilizing the voltage of the primary side winding of the transformer equal to the input voltage when the switching tube is switched on and the voltage proportional relation between the primary side first winding of the transformer and the primary side winding of the transformer.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a circuit for detecting a secondary side of an input voltage of a flyback converter according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be understood that the step numbers used herein are for convenience of description only and are not intended as limitations on the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to and includes any and all possible combinations of one or more of the associated listed items.
A first aspect.
Referring to fig. 1, an embodiment of the invention provides a secondary side detection circuit of an input voltage of a flyback converter, which includes a primary side circuit and a secondary side circuit. The primary side circuit comprises a switching tube Q1 and a primary side winding Np(ii) a The secondary side circuit includes a secondary side first circuit.
Further, the secondary-side first circuit includes:
secondary side first winding Ns2The secondary side first winding Ns2Respectively connected to the anode of the first diode D1 and the cathode of the third diode D3, and the secondary side first winding Ns2The synonym terminals of the first diode D are respectively connected with the cathode of the second diode D2 and the anode of the fourth diode D4;
two ends of a filter circuit consisting of a first resistor R1, a second resistor R2 and a first capacitor C1 are respectively connected with the cathode of the first diode D1 and the anode of the second diode D2; one end of the first resistor R1 is connected to the cathode of the first diode D1, and the other end of the first resistor R1 is connected to one end of the first capacitor C1; the other end of the first capacitor C1 is connected to the anode of the second diode D2; the second resistor R2 is connected in parallel with the first capacitor C1, and the voltage at two ends of the second resistor R2 is the detection value of the input voltage of the primary side circuit;
two ends of the second capacitor C2 are connected to the anode of the third diode D3 and the cathode of the fourth diode D4, respectively.
In a specific embodiment, the filter circuit composed of the first resistor R1, the second resistor R2 and the first capacitor C1 is used for filtering high-frequency noise; the first resistor R1 is used for suppressing surge current.
In one embodiment, assume that the primary winding N of the transformerpAnd the first winding Ns2The turn ratio of (2) is K1. When the switching tube Q1 is switched on, the primary winding N of the transformerpVoltage on is equal to input voltage VinThen the first winding Ns2Is equal to Vinand/K1. The first diode D1 and the second diode D2 are turned on, and the third diode D3 and the fourth diode D4 are turned off to charge the capacitor C1; when the switch tube Q1 is turned off, the first diode D1 and the second diode DThe diode D2 is turned off, the third diode D3 and the fourth diode D4 are turned on, and the capacitor C1 discharges through R2; since C1 × R2 is greater than the switching period, the discharge rate of C1 is less than the charge rate, and since R1 is less than R2, the voltage on the C1 capacitor will rush to V after a plurality of switching periodsinand/K1, thereby realizing input voltage detection.
When the input voltage VinWhen the switching tube Q1 is switched on and off suddenly, the first winding Ns2Voltage on is less than the detection voltage Vin_sAt this time, the first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are all in an off state, the first capacitor C1 discharges through the second resistor R2, and the voltage of the first capacitor C1 decreases throughout the whole switching period until the detection voltage V is detectedin_sAgain equal to the first winding N when the switching tube Q1 is switched ons2The voltage of (c).
The invention provides a flyback converter input voltage secondary side detection circuit which realizes secondary side detection of input voltage by utilizing the voltage of a primary winding of a transformer equal to the input voltage when a switching tube is switched on and the voltage proportional relation between an auxiliary winding of a voltage device and the primary winding of the transformer. The invention provides the flyback converter secondary input voltage detection circuit with simple structure and low cost, and contributes to the performance improvement of high and new technology electronic products.
In a specific embodiment, the secondary side circuit further comprises a secondary side second circuit; the secondary side second circuit includes: secondary winding Ns1And a fifth diode D5 and a third capacitor C3 connected in series; the secondary side second winding Ns1The homonymous terminal and the synonym terminal of the third capacitor are respectively connected with the anode of the fifth diode and one end of the third capacitor.
The connection end of the first capacitor C1 and the second diode D2 is grounded, and the connection end of the second capacitor C2 and the third diode D3 is grounded.
In a specific embodiment, a switching period of the switching tube is less than a product of the first capacitor and the second resistor, and the first resistor is less than the second resistor. Preferably, the switching period of the switching tube is less than the product of the first capacitor and the second resistor, and the first resistor is less than the second resistor. Preferably, the switch tube is a field effect transistor enhanced N-MOS.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (4)
1. A flyback converter input voltage secondary side detection circuit is characterized by comprising a primary side circuit and a secondary side circuit; wherein the content of the first and second substances,
the primary side circuit comprises a switching tube and a primary side winding; the secondary side circuit comprises a secondary side first circuit; wherein the content of the first and second substances,
the secondary-side first circuit, comprising:
the homonymous end of the secondary side first winding is respectively connected with the anode of the first diode and the cathode of the third diode, and the synonym end of the secondary side first winding is respectively connected with the cathode of the second diode and the anode of the fourth diode;
two ends of a filter circuit consisting of a first resistor, a second resistor and a first capacitor are respectively connected with the cathode of the first diode and the anode of the second diode; one end of the first resistor is connected to the cathode of the first diode, and the other end of the first resistor is connected to one end of the first capacitor; the other end of the first capacitor is connected to the anode of the second diode; the second resistor is connected with the first capacitor in parallel, and the voltage at two ends of the second resistor is the detection value of the input voltage of the primary circuit;
two ends of the second capacitor are respectively connected with the anode of the third diode and the cathode of the fourth diode;
the switching period of the switching tube is less than the product of the first capacitor and the second resistor, and the first resistor is less than the second resistor.
2. The flyback converter input voltage secondary detection circuit of claim 1 wherein the switching transistor is a fet-enhanced N-MOS.
3. The flyback converter input voltage secondary detection circuit of claim 1 wherein the secondary circuit further comprises a secondary second circuit;
the secondary side second circuit includes:
the secondary side second winding is connected with a fifth diode and a third capacitor in series; and the homonymous end and the synonym end of the secondary side second winding are respectively connected with the anode of the fifth diode and one end of the third capacitor.
4. The flyback converter input voltage secondary detection circuit of claim 1 wherein a connection of the first capacitor to the second diode is coupled to ground and a connection of the second capacitor to the third diode is coupled to ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010931460.1A CN112198358B (en) | 2020-09-07 | 2020-09-07 | Flyback converter input voltage secondary side detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010931460.1A CN112198358B (en) | 2020-09-07 | 2020-09-07 | Flyback converter input voltage secondary side detection circuit |
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| Publication Number | Publication Date |
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| CN112198358A CN112198358A (en) | 2021-01-08 |
| CN112198358B true CN112198358B (en) | 2021-10-01 |
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| CN202010931460.1A Active CN112198358B (en) | 2020-09-07 | 2020-09-07 | Flyback converter input voltage secondary side detection circuit |
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Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005317278A (en) * | 2004-04-27 | 2005-11-10 | Canon Inc | Stroboscopic device |
| CN101771353B (en) * | 2010-02-24 | 2011-12-14 | 英飞特电子（杭州）有限公司 | Auxiliary source circuit for switch power supply |
| CN204131397U (en) * | 2014-09-05 | 2015-01-28 | 武汉永力睿源科技有限公司 | A kind of input voltage detection circuit of isolating inverse-excitation type high frequency switch power |
| CN104578790A (en) * | 2014-12-29 | 2015-04-29 | 东南大学 | Digital signal sampling circuit applied to primary-side feedback flyback converter and control method of digital signal sampling circuit |
| CN107769569A (en) * | 2017-10-13 | 2018-03-06 | 深圳市盛弘电气股份有限公司 | A kind of half bridge flyback resonance circuit |
| CN108233723A (en) * | 2018-03-26 | 2018-06-29 | 珠海格力电器股份有限公司 | Circuit of reversed excitation and flyback converter |
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Address after: 201600 Building 1, 469 sanbang Road, Songjiang District, Shanghai Applicant after: Shanghai Juntao Technology Co.,Ltd. Address before: 201600 Building 1, 469 sanbang Road, Songjiang District, Shanghai Applicant before: SHANGHAI JUNTAO POWER EQUIPMENT Co.,Ltd. |
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