CN114785147A - Flyback circuit system without input electrolytic capacitor - Google Patents
Flyback circuit system without input electrolytic capacitor Download PDFInfo
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- CN114785147A CN114785147A CN202210518747.0A CN202210518747A CN114785147A CN 114785147 A CN114785147 A CN 114785147A CN 202210518747 A CN202210518747 A CN 202210518747A CN 114785147 A CN114785147 A CN 114785147A
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- 238000004891 communication Methods 0.000 description 5
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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
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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
- H02M1/32—Means for protecting converters other than automatic disconnection
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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
- H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
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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
- H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
- H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
- H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
- H02M7/06—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
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Abstract
The invention discloses a flyback circuit system without an input electrolytic capacitor, which comprises a rectification circuit BD1, a power supply filter C1, a flyback circuit, an output filter C2, an output feedback circuit, a flyback control circuit IC1 and a rectification filter C5, wherein after the voltage of an alternating current power grid passes through the rectification circuit BD1, a filter circuit C1 formed by a capacitor is filtered and provided to the flyback circuit, which provides a first output Vout1 to the load after passing through an output filter C2, and the output feedback circuit is connected after the output filter C2, provides a feedback signal into the flyback control circuit IC1, the flyback control circuit IC1 outputs to the flyback circuit after rectification, filtering and rectification so as to control the duty ratio and energy transmission of the flyback circuit, the control bandwidth is high, the dynamic response speed is high, and the problems of output voltage undervoltage shutdown or output overvoltage damage devices caused by output overshoot are solved.
Description
Technical Field
The invention relates to the technical field of intelligent electric meters, in particular to a flyback circuit system without an input electrolytic capacitor.
Background
The existing smart meter is not only used in general household or industrial use, but also used in power plants or other power generation equipment, and the voltage used by the existing smart meter is not only used in single-phase 220VAC and three-phase 380VAC, but also used in a very wide range, such as 85-450VAC for a single-phase meter and 35-550VAC for a three-phase meter. Because the internal metering, communication, battery and the like of the intelligent electric meter need safety isolation, an isolation circuit is often adopted by a power supply inside the intelligent electric meter. The single-phase or three-phase network voltage is converted into a direct voltage, often by diode rectification and electrolytic capacitor filtering. The rectified voltage can reach 780V at most, and the maximum voltage of an electrolytic capacitor for general industry can only reach 450V, so in the application of the network voltage, a designer of a power supply needs to connect two electrolytic capacitors of 450V in series for use, and resistors are often connected in parallel on a single capacitor in order to keep the voltage of the two capacitors evenly divided. This has 3 disadvantages: 1. the service life of a general electrolytic capacitor is short, the whole service life of an electric meter is influenced, the service life of the electric meter is often more than ten years, so that the electrolytic capacitor with long service life is required to be selected, and the problems of large volume, high unit price and the like of the capacitor are caused; 2. after one of the electrolytic capacitors is short-circuited or failed due to open circuit, the remaining capacitor bears all voltage, and the voltage which is as high as 780V is instantly applied to the rated voltage of the capacitor of 450V, so that the electrolytic capacitor is cracked and failed, electrolyte of the electrolytic capacitor is sprayed onto a printed circuit board, the insulation performance of an ammeter is influenced, and potential safety hazards are generated; 3. the resistor connected in parallel to the electrolytic capacitor generates extra loss, so that the standby power consumption of the electric meter is increased, the energy-saving efficiency of the electric meter is seriously influenced, and excessive energy waste is caused.
In another method, a capacitor with a small volume and a high voltage-resistant film is used to replace the electrolytic capacitor, but the method also has the following problems: because the traditional PFC control method is adopted in order to meet the harmonic regulation requirement of input current in control, the method generally adopts a critical conduction mode (CRM) of inductive current zero crossing, and in duty ratio control, firstly, a control mode that the peak current adjusts the duty ratio along with the input voltage and secondly, a duty ratio control mode of fixed conduction time are adopted, and the two control modes often cause the switching frequency to be variable frequency, the control bandwidth to be very low, the dynamic response speed to be very slow, and overshoot can occur in output when the input voltage changes or the output load changes, so that the output voltage is undervoltage shut down or an output overvoltage damage device is caused, and the stability of control modules of metering, communication and the like of an ammeter is influenced.
Disclosure of Invention
The invention aims to provide a flyback circuit system without an input electrolytic capacitor, so as to meet the requirement of technical development and overcome the defects of the existing test method.
In order to achieve the purpose, the invention provides the following technical scheme:
the application discloses a flyback circuit system without an input electrolytic capacitor, which comprises a rectification circuit BD1, a power supply filter C1, a flyback circuit, an output filter C2, an output feedback circuit, a flyback control circuit IC1 and a rectification filter C5, wherein the input end of the rectification circuit BD1 is connected with the voltage of an alternating current power grid, the output end of the rectification circuit BD1 is connected with the input end of the power supply filter C1, the output end of the filter circuit C1 is connected with the input end of the flyback circuit, the output end of the flyback circuit is connected with the input end of the output filter C2, the output end of the output filter C2 is connected with the input end of the output feedback circuit, the output end of the output feedback circuit is connected with the output end of the flyback control circuit IC1, the output end of the flyback control circuit IC1 is connected with the input end of the rectification filter, and the output end of the rectification filter is connected with the input end of the flyback circuit;
after the alternating current grid voltage passes through the rectifying circuit BD1, the filter circuit C1 composed of a capacitor filters and provides the alternating current grid voltage for the flyback circuit, the flyback circuit provides a first output Vout1 to a load after passing through the output filter C2, the output feedback circuit is connected after the output filter C2 and provides a feedback signal to the flyback control circuit IC1, and the flyback control circuit IC1 outputs the alternating current grid voltage to the flyback circuit after rectification, filtering and rectification, so that the duty ratio and energy transmission of the flyback circuit are controlled.
Preferably, two "-" pins of the rectifier circuit BD1 are connected to the input end L and the input end N, respectively, and a "+" pin and a "-" pin of the BD1 are connected to two ends of the power supply filter C1, respectively.
Preferably, one end of the power supply filter C1 is connected to the "+" pin of the BD1 and also connected to the 1 end of the transformer T1 in the flyback circuit, and the other end of the C1 is connected to the "-" pin of the BD1 and also connected to the ground.
Preferably, the flyback circuit includes a transformer T1, a transistor Q1, a diode D1, a diode D2, a diode D3, a resistor R5, a resistor R6, and a capacitor C4, the Np side of the T1 has a terminal 1 and a terminal 2, wherein the 1 terminal is connected to one end of the C1, the D1, the C4 and the R5 are connected between the 1 terminal and the 2 terminal, the 1 terminal is connected with one ends of the R5 and the C4, the anode of the D1 is connected with the 2 terminal, the cathode of the D1 is connected with the R5 and the C4, the R5 and the C4 are connected in parallel, the D pole of the Q1 is connected with the 2 terminal, the S pole is connected with one end of the R6, the G pole is connected with the DRV pin of the flyback control circuit IC1, the other end of the R6 is grounded, the Ns1 of the first winding of the T1 has a 3 terminal and a 4 terminal, the 3 end point is connected with the anode of the D2, the 4 end point is grounded and is simultaneously connected with the cathode of the output filter C2 and the negative output end Vo1-, and the cathode of the D2 is connected with the anode of the C2 and the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the 6 terminal is connected with the negative pole of the C5 and is grounded.
Preferably, the anode of the output filter C2 is connected to the cathode of the D2 and the positive output terminal Vo1+, the cathode of the C2 is connected to the 4 terminal of the T1 and the negative output terminal Vo1-, and is grounded, and the output filter C2 converts the square wave voltage rectified by the D2 from the voltage of the transformer T1 into the dc voltage required by the load.
Preferably, the output feedback circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C3, an optocoupler IC2, and an optocoupler IC3_ A, IC3_ B, where the IC3_ A, IC3_ B is two parts of the same optocoupler IC3, the IC3_ a is located on the secondary side of T1, and the IC3_ B is located on the primary side of T1, and is used to transmit signals; one end of R1 is connected to Vo1+, the other end is connected with R2, the voltage of Vo1+ is divided through a voltage division network formed by R1 and R2, one end of R1 is also connected with an R pin of IC2, the other two terminals A of IC2 are connected to Vo 1-of a secondary side, a terminal C is connected to the cathode of IC3_ A, and a capacitor C3 is connected between a terminal C and a terminal R of IC 2; the anode of the IC3_ A is connected with one end of R3, and the other end of R3 is connected to Vo1 +; the C pole of the IC3_ B is connected with the FB pin of the flyback control circuit IC1, and the E pole is grounded; r1 and R2 compare the divided voltage of Vo1+ with the internal reference voltage of IC2, IC2 amplifies the error voltage between the two, adjusts the voltage of C pin of IC2, so as to adjust the current flowing through IC3_ a, and transmits the current to IC3_ B on the primary side via optical signal, so as to adjust the FB pin voltage of IC1 connected to IC3_ B, and transmit the signal to the inside of flyback control circuit IC 1.
Preferably, the DRV pin of the flyback control circuit IC1 is connected to the G-pole of Q1, the CS pin is connected to the S-pole of Q1 and R6, the GND pin is grounded, the FB pin is connected to the C-pole of IC3_ B, and the Vcc pin is connected to the negative pole of D3 and the positive pole of C5, and is connected to the "+" pin of BD1 through R4 to supply power to IC 1.
Preferably, the T1 further includes a second winding Ns2, a diode D4, and a second output filter C6, the second winding Ns2 has 7 terminals and 8 terminals, wherein the 8 terminal is connected to the negative terminal of C6 and simultaneously connected to Vo2 ", the 7 terminal is connected to the positive terminal of D4, the negative terminal of D4 is connected to the positive terminal of C6 and simultaneously connected to Vo2+, and the second winding Ns2 is rectified by D4 and filtered by C6 to provide a second output Vout2 to the load.
Preferably, the flyback circuit comprises a transformer T, a triode Q, a diode D, a resistor R, a capacitor C, and is used for converting the voltage of C into the voltage of C, the Np side of T has a 1 terminal and a 2 terminal, wherein the 1 terminal is connected to one end of C, the 1 terminal and the 2 terminal are connected to D, C, R, and 1 terminal, the 1 terminal is connected to one end of R, C, and D, the anode of D is connected to the 2 terminal, the cathode of D is connected to R, C, and R and C are connected in parallel, the D terminal of Q is connected to the 2 terminal, the S terminal is connected to one end of R, the G terminal is connected to the DRV pin of the flyback control circuit IC, the other end of R is grounded, the first winding Ns of T has a 3 terminal and a 4 terminal, wherein the 3 terminal is connected to the anode of D, the 4 terminal is grounded and is simultaneously connected to the cathode of the output filter C and the negative output terminal Vo-, the negative electrode of D2 is connected with the positive electrodes of C7 and D5, and the negative electrode of D5 is connected with the positive electrode of C2 and the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein, the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the terminal 6 is connected with the negative pole of the C5 and is grounded.
Preferably, the flyback circuit includes a transformer T1, a transistor Q1, a diode D1, a diode D2, a diode D3, a diode D5, a resistor R5, a resistor R6, a capacitor C4, and a capacitor C7, the Np side of the T1 has a terminal 1 and a terminal 2, where the terminal 1 is connected to one end of C1, the terminal 1 and the terminal 2 are connected to D1, C4, and R5, the terminal 1 is connected to one end of R5 and C4, the positive pole of D1 is connected to the terminal 2, the negative pole of D1 is connected to R5 and C4, R5 and C4 are connected in parallel, the terminal 2 is connected to the terminal D of Q1, the terminal S is connected to one end of R1, the terminal G is connected to the DRV pin of the control circuit IC1, the other end of R4974 is grounded, the first winding 1 of T4 has a terminal 3 and a terminal 4, where the terminal D1 is connected to the terminal, the positive pole of D1, the terminal 1 is connected to the negative pole of the flyback output terminal 1, the C1, the negative pole of the filter output terminal 1 and the negative pole of the C1 is connected to the negative pole of the C1, the filter output terminal 1, the C1, the negative pole of the D1, and the negative pole of the C1, the dc 1 is connected to the dc 1, the dc-f 1, the dc output terminal of the dc output terminal 1, and the dc-f 1, and the dc output terminal of the dc-f 1 are connected to the dc output terminal of the dc-f 1, and the dc output terminal of the dc-C1, and the dc output terminal of the dc-f 1, and the dc output terminal of the control circuit is connected to the control circuit IC1, and the control circuit is connected to the control circuit IC1, the control circuit is connected to the control circuit IC1, the control circuit is connected to the control circuit IC1, the control circuit IC circuit, the control circuit is connected to the control circuit, the control circuit is connected to the control circuit, the control circuit is connected to the control circuit, the control circuit is connected, the negative electrode of the D2 is connected with the positive electrode of the C2 and the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the terminal 6 is connected with the negative pole of the C5 and is grounded.
The invention has the beneficial effects that:
(1) after the voltage of an alternating current power grid passes through the rectifying circuit, a filter circuit consisting of capacitors filters and provides the filtered voltage to the flyback circuit, the flyback circuit passes through the output filter circuit and provides the filtered voltage to a load, the output feedback circuit is connected to the output rectifying circuit and provides a feedback signal to the flyback control circuit, and therefore the duty ratio and the energy transmission of the flyback circuit are controlled, the filter circuit does not have an electrolytic capacitor and consists of a thin film capacitor with smaller capacitor capacity, and the problems of short service life, large volume and high unit price of the electrolytic capacitor in the prior art are solved; the flyback control circuit is controlled by a fixed switching frequency, the duty ratio is adjusted by fixing the primary side peak current instead of adjusting in a mode of fixing the duty ratio of conventional high-power factor flyback or in a mode of enabling the peak current to follow the input voltage, the control bandwidth is high, the dynamic response speed is high, the problems of output voltage under-voltage shutdown or output overvoltage damage devices caused by output overshoot are solved, and the stability and the safety of a system are improved;
(2) the thin film capacitor does not need to be connected with a resistor in parallel, so that the extra loss of the whole system is reduced, and the aim of saving energy consumption is fulfilled;
(3) two output ports are provided, so that power can be supplied to the control chip and the communication chip respectively without accessing an additional power supply;
(4) the problems of low feedback speed and unstable voltage of the system caused by overlarge C2 are solved, and the reliability of the system is improved.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a circuit diagram of embodiment 1 of the present invention;
FIG. 3 is a circuit diagram of embodiment 2 of the present invention;
FIG. 4 is a circuit diagram of embodiment 3 of the present invention;
fig. 5 is a circuit diagram of embodiment 4 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood, however, that the detailed description herein of specific embodiments is intended to illustrate the invention and not to limit the scope of the invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
As shown in fig. 1, the present invention provides a flyback circuit system without an input electrolytic capacitor, which comprises a rectification circuit, a power supply filter, a flyback circuit, an output filter, an output feedback circuit, a flyback control circuit, and a rectification filter, wherein an input terminal of the rectification circuit is connected to an ac power grid voltage, an output terminal of the rectification circuit is connected to an input terminal of the power supply filter, an output terminal of the filter circuit is connected to an input terminal of the flyback circuit, an output terminal of the output filter is connected to an input terminal of the output feedback circuit, an output terminal of the output feedback circuit is connected to an output terminal of the flyback control circuit, an output terminal of the flyback control circuit is connected to an input terminal of the rectification filter, and an output terminal of the rectification filter is connected to an input terminal of the flyback circuit;
after the alternating current power grid voltage passes through the rectifying circuit, a filter circuit consisting of capacitors is filtered and provided for the flyback circuit, the flyback circuit provides output to a load after output filtering, the output feedback circuit is connected to the output filter and provides a feedback signal to the flyback control circuit, and the flyback control circuit outputs the feedback signal to the flyback circuit after rectification, filtering and rectification, so that the duty ratio and energy transmission of the flyback circuit are controlled.
Example 1
As shown in fig. 2, a flyback circuit system without an input electrolytic capacitor includes a rectifier circuit BD1, a power supply filter C1, a flyback circuit, an output filter C2, an output feedback circuit, a flyback control circuit IC1, and a rectification filter C5, and is characterized in that: the input end of the rectifying circuit BD1 is connected with the voltage of an alternating current power grid, the output end of the rectifying circuit BD1 is connected with the input end of a power supply filter C1, the output end of the filter circuit C1 is connected with the input end of a flyback circuit, the output end of the flyback circuit is connected with the input end of an output filter C2, the output end of the output filter C2 is connected with the input end of an output feedback circuit, the output end of the output feedback circuit is connected with the output end of a flyback control circuit IC1, the output end of the flyback control circuit IC1 is connected with the input end of a rectifying filter, and the output end of the rectifying filter is connected with the input end of the flyback circuit;
after the alternating current grid voltage passes through a rectification circuit BD1, a filter circuit C1 composed of a capacitor is filtered and provided for a flyback circuit, the flyback circuit provides a first output Vout1 to a load after passing through an output filter C2, an output feedback circuit is connected to the output filter C2 and provides a feedback signal to a flyback control circuit IC1, and the flyback control circuit IC1 is rectified and filtered and then outputs the feedback signal to the flyback circuit so as to control the duty ratio and energy transmission of the flyback circuit.
Two pins-/-of the rectifying circuit BD1 are respectively connected to the input end L and the input end N, and a pin + and a pin-of the BD1 are respectively connected to two ends of the power supply filter C1.
One end of the power supply filter C1 is connected with the + pin of the BD1 and is simultaneously connected with the 1 end point of the transformer T1 in the flyback circuit, and the other end of the C1 is connected with the-pin of the BD1 and is simultaneously grounded.
The flyback circuit comprises a transformer T1, a triode Q1, a diode D1, a resistor R1 and a capacitor C1, wherein the Np side of the T1 has a terminal 1 and a terminal 2, the terminal 1 is connected to one end of the C1, the terminal 1 is connected with one end of the R1, the terminal C1 and the terminal R1, the terminal 1 is connected with one end of the C1, the anode of the D1 is connected with the terminal 2, the cathode of the D1 is connected with the terminal R1 and the C1, the terminal R1 is connected in parallel with the C1, the D of the Q1 is connected with the terminal 2, the S is connected with one end of the R1, the G is connected with the DRV pin of the flyback control IC1, the other end of the R1 is connected with the ground, the first winding of the T1 has a terminal 3 and a terminal 4, the terminal NS1 has a terminal 3 and a terminal 3 terminal, the terminal 3 terminal is connected with the anode of the Vo of the D1, the terminal is connected with the cathode of the output of the positive terminal of the negative of the C1 and the negative pole of the DC 1 is connected with the positive output of the D1, the D1 is connected with the positive output terminal 1, and the positive output of the negative terminal 1 of the C1 is connected with the positive output of the negative terminal 1; the Na side of T1 has 5 terminals and 6 terminals, wherein, the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the terminal 6 is connected with the negative pole of the C5 and is grounded.
The anode of the output filter C2 is connected with the cathode of the D2 and the positive output end Vo1+, the cathode of the C2 is connected with the 4 endpoint of the T1 and the negative output end Vo1-, and is grounded, and the output filter C2 converts the square wave voltage rectified by the D2 of the voltage of the transformer T1 into the direct current voltage required by the load.
The output feedback circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C3, an optical coupler IC2 and an optical coupler IC3_ A, IC3_ B, wherein the IC3_ A, IC3_ B is two parts of the same optical coupler IC3, the IC3_ A is positioned on the secondary side of the T1, and the IC3_ B is positioned on the primary side of the T1, and is used for transmitting signals; one end of R1 is connected to Vo1+, the other end is connected with R2, the voltage of Vo1+ is divided through a voltage division network formed by R1 and R2, one end of R1 is also connected with an R pin of IC2, the other two terminals A of IC2 are connected to Vo 1-of a secondary side, a terminal C is connected to the cathode of IC3_ A, and a capacitor C3 is connected between a terminal C and a terminal R of IC 2; the anode of the IC3_ A is connected with one end of R3, and the other end of R3 is connected to Vo1 +; the C pole of the IC3_ B is connected with the FB pin of the flyback control circuit IC1, and the E pole is grounded; r1 and R2 compare the divided voltage of Vo1+ with the internal reference voltage of IC2, IC2 amplifies the error voltage between the two, adjusts the voltage of C pin of IC2, thereby regulating the current flowing through IC3_ a, passing through the optical signal to the primary side IC3_ B, therefore, the voltage of the FB pin of the IC1 connected with the IC3_ B is regulated, signals are transmitted to the interior of a flyback control circuit IC1, the voltage divided by Vo + is compared with the internal reference voltage of the IC2 by the R1 and the R2, the error voltage between the two is amplified by the IC2, the voltage of the C pin of the IC2 is adjusted, thereby regulating the current flowing through IC3_ a, passing through the optical signal to the primary side IC3_ B, therefore, the FB pin voltage of the IC1 connected with the IC3_ B is regulated, and signals are transmitted to the inside of the control chip IC1, the IC2 can adopt an optical coupler with the model number TL431, and the IC3 can adopt an optical coupler with the model number EL 817.
The DRV pin of the flyback control circuit IC1 is connected with the G pole of Q1, the CS pin is connected with the S pole of Q1 and R6, the GND pin is grounded, the FB pin is connected with the C pole of IC3_ B, the Vcc pin is connected with the negative pole of D3 and the positive pole of C5, the GND pin is connected with the + pin of BD1 through R4 to supply power to IC1, the CS voltage of R6 resistance is acquired by multiplying the current flowing through R6, the CS voltage is compared with the voltage of the FB pin, when the FB pin voltage is reached, the Q1 is controlled to be turned off, the internal crystal oscillator generates 60KHz frequency, and therefore the Q1 is controlled to be turned on, and the IC1 can adopt a chip with the model of AP82 8268W.
Example 2
Since the power supply of the electric meter often has not only a single output Vout1, but a plurality of outputs are required to be provided to a control chip or a communication chip, for example, 12Vdc provided by Vout1 is provided to a power communication chip, and 5V provided by Vout2 is provided to an MCU (micro controller), an LCD display, a metering chip, an infrared receiver and the like.
In order to provide additional Vout2, a winding Ns2 needs to be added to the transformer, and a stable voltage is provided to Vout2 through a rectifier diode D4 and a filter capacitor C6, as shown in fig. 2:
on the basis of the embodiment 1, the T1 further includes a second winding Ns2, a diode D4, and a second output filter C6, the second winding Ns2 has 7 terminals and 8 terminals, wherein the 8 terminal is connected to the negative electrode of C6 and simultaneously connected to Vo2 ", the 7 terminal is connected to the positive electrode of D4, the negative electrode of D4 is connected to the positive electrode of C6 and simultaneously connected to Vo2+, and the second winding Ns2 is rectified by D4 and filtered by C6 to provide a second output Vout2 to the load.
Example 3
In the above embodiment 2, in order to filter low-frequency ripples, C2 is often larger, which results in a slow feedback speed of the whole system, when the load provided by Vout1 dynamically changes, the voltage on Vout2 is very unstable, which affects the reliability of chip power supply, and to solve this problem, we insert a diode D5 and a capacitor C7 between original D2 and C2, where the capacitance of C7 is much smaller than that of C2, and R3 and R1 are changed from the original positive terminal connected to C2 to the positive terminal connected to C7, which has the advantage that, due to the smaller capacitance of C7, the rectified voltage of feedback D2 can be faster compared, that is, the rectified voltage reacts faster than Vout1, so that Vout2 can change faster with Vout1, and the dynamic regulation rate is improved, as shown in fig. 3:
on the basis of embodiment 2, a mechanism of a flyback circuit is changed, the flyback circuit includes a transformer T1, a triode Q1, a diode D1, a diode D2, a resistor R2, a capacitor C2 and a capacitor C2, the Np side of the T2 has a terminal 1 and a terminal 2, wherein the terminal 1 is connected to one end of the C2, the terminal 1 is connected to the terminal D2, the terminal C2 and the terminal R2, the terminal 1 is connected to one end of the R2 and the C2, the positive electrode of the D2 is connected to the terminal 2, the negative electrode of the D2 is connected to the terminals R2 and C2, the R2 is connected in parallel with the terminal C2, the terminal D of the Q2 is connected to the terminal 2, the terminal S is connected to one end of the R2, the G is connected to the DRV pin of the IC control circuit IC 4, the other end of the R2 is grounded, the first winding Ns 4 has a terminal 3 and a terminal 2, the positive electrode of the terminal D2 is connected to the negative terminal of the negative electrode of the flyback control circuit Vo2, and the negative electrode of the output terminal of the C2 is connected to the output terminal of the flyback control circuit Vo2, and the output terminal 3 is connected to the output terminal C2, and the negative terminal of the filter, and the negative terminal C2 is connected to the output terminal 2, and the negative terminal of the filter output terminal of the C2, and the filter output terminal 2 is connected to the C2, and the filter output terminal 2, and the negative terminal 2 is connected to the output terminal of the C2, and the filter output terminal 2, and the output terminal of the T2, and the filter is connected to the C2, and the output terminal of the T2 is connected to the T2, and the output terminal of the T2, and the dc output terminal of the dc output terminal is connected to the dc output terminal of the T2, and the dc output terminal of the dc circuit is connected to the dc output terminal of the T2, and the dc output terminal of the dc circuit is connected to the dc circuit is, the negative electrode of the D2 is connected with the positive electrodes of the C7 and the D5, and the negative electrode of the D5 is connected with the positive electrode of the C2 and the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein, the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the terminal 6 is connected with the negative pole of the C5 and is grounded.
Example 4
In order to solve the problems in embodiment 2, we provide another solution, a D5 is connected in parallel to the original D2, and a filter capacitor C7 is added to the anode of D5, wherein the capacitance of C7 is much smaller than that of C2, and R3 and R1 are changed from the original positive terminal connected to C2 to the positive terminal connected to C7, which has the advantage that the voltage rectified by D2 can be fed back quickly due to the smaller capacitance of C7, that is, the response is faster than that of Vout1, so that Vout2 can change with Vout1 more quickly, and the dynamic regulation rate is improved.
Based on embodiment 2, a mechanism of a flyback circuit is modified, the flyback circuit includes a transformer T1, a transistor Q1, a diode D1, a diode D2, a diode D3, a diode D5, a resistor R5, a resistor R6, a capacitor C4, and a capacitor C7, the Np side of the T1 has a terminal 1 and a terminal 2, wherein the terminal 1 is connected to one end of C1, a terminal D1, a terminal C4, and a terminal R5 are connected between the terminal 1 and the terminal 2, a terminal 1 is connected to one ends of R5 and C4, a terminal D1 has a terminal 2 connected to the terminal D, a cathode of D1 is connected to the terminal R5 and C4, the terminals R5 and C4 are connected in parallel, a terminal D of Q1 is connected to the terminal 2, a terminal S is connected to one end of R1, a terminal G is connected to a DRV pin of the control circuit IC1, the other end of R1 is grounded, a first terminal of the T1 has a terminal 3 and a terminal 1, a terminal 6853 of the terminal Ns1, wherein a terminal D3 is connected to the terminal D1, a terminal D3 is connected to the other end of the terminal R1, a terminal R1 is connected to the negative terminal C1, a negative terminal 1 is connected to the negative terminal of the output of the dc 1, a negative terminal of the C1 is connected to the C1, a negative terminal 1, and a negative terminal 1 is connected to the C1, and a negative terminal 1 is connected to the output terminal 1, and a negative terminal of the C1, and a negative terminal 1 is connected to the C1, and a negative terminal of the C1 is connected to the C1, and a negative terminal 1 is connected to the C1, and a negative terminal of C1 is connected to the C1, and a negative terminal 1 is connected to the C1, and a negative terminal 1 is connected to the C1, and a negative terminal 1, and, the negative electrode of the D2 is connected with the positive electrode of the C2 and the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the terminal 6 is connected with the negative pole of the C5 and is grounded.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. The flyback circuit system without the input electrolytic capacitor comprises a rectification circuit BD1, a power supply filter C1, a flyback circuit, an output filter C2, an output feedback circuit, a flyback control circuit IC1 and a rectification filter C5, and is characterized in that: the input end of the rectifying circuit BD1 is connected with the voltage of an alternating current power grid, the output end of the rectifying circuit BD1 is connected with the input end of a power supply filter C1, the output end of the filter circuit C1 is connected with the input end of a flyback circuit, the output end of the flyback circuit is connected with the input end of an output filter C2, the output end of the output filter C2 is connected with the input end of an output feedback circuit, the output end of the output feedback circuit is connected with the output end of a flyback control circuit IC1, the output end of the flyback control circuit IC1 is connected with the input end of a rectifying filter, and the output end of the rectifying filter is connected with the input end of the flyback circuit;
after the alternating current grid voltage passes through the rectifying circuit BD1, the filter circuit C1 composed of a capacitor filters and provides the alternating current grid voltage for the flyback circuit, the flyback circuit provides a first output Vout1 to a load after passing through the output filter C2, the output feedback circuit is connected after the output filter C2 and provides a feedback signal to the flyback control circuit IC1, and the flyback control circuit IC1 outputs the alternating current grid voltage to the flyback circuit after rectification, filtering and rectification, so that the duty ratio and energy transmission of the flyback circuit are controlled.
2. The flyback circuit system without an input electrolytic capacitor of claim 1, wherein: two pins of the rectification circuit BD1 are connected to an input end L and an input end N respectively, and a pin of the rectification circuit BD1 "+" and a pin of the rectification circuit BD1 are connected to two ends of a power supply filter C1 respectively.
3. The flyback circuit system without an input electrolytic capacitor of claim 2, wherein: one end of the power supply filter C1 is connected with a + pin of the BD1 and is also connected with a 1 endpoint of a transformer T1 in the flyback circuit, and the other end of the C1 is connected with a-pin of the BD1 and is also grounded.
4. A flyback circuit system without an input electrolytic capacitor as in claim 3, wherein: the flyback circuit comprises a transformer T1, a triode Q1, a diode D1, a resistor R1 and a capacitor C1, wherein the Np side of the T1 is provided with a terminal 1 and a terminal 2, the terminal 1 is connected to one end of the C1, the terminal 1 is connected with one end of the C1, the terminal D1, the terminal C1 and the terminal R1 are connected, the terminal 1 is connected with one ends of the R1 and the C1, the positive electrode of the D1 is connected with the terminal 2, the negative electrode of the D1 is connected with the terminal R1 and the terminal C1, the D electrode of the Q1 is connected in parallel with the terminal C1, the D electrode of the Q1 is connected with the terminal 2, the S electrode is connected with one end of the R1, the G electrode is connected with the DRV pin of the flyback control IC1, the other end of the R1 is grounded, the first winding of the T1 is provided with a terminal 3 and a terminal Vo 3 and a negative electrode of the D1 is connected with the output of the positive electrode of the output of the filtering circuit C1 and the negative electrode 1+ of the output terminal C1; the Na side of T1 has 5 terminals and 6 terminals, wherein the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the terminal 6 is connected with the negative pole of the C5 and is grounded.
5. The flyback circuit system without an input electrolytic capacitor of claim 4, wherein: the anode of the output filter C2 is connected with the cathode of the D2 and the positive output end Vo1+, the cathode of the C2 is connected with the 4 end point of the T1 and the negative output end Vo1-, and is grounded at the same time.
6. The flyback circuit system without an input electrolytic capacitor of claim 5, wherein: the output feedback circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C3, an optical coupler IC2 and an optical coupler IC3_ A, IC3_ B, wherein the IC3_ A, IC3_ B is two parts of the same optical coupler IC3, the IC3_ A is positioned on the secondary side of the T1, and the IC3_ B is positioned on the primary side of the T1, and is used for transmitting signals; one end of R1 is connected to Vo1+, the other end is connected with R2, the voltage of Vo1+ is divided through a voltage division network formed by R1 and R2, one end of R1 is also connected with an R pin of IC2, the other two terminals A of IC2 are connected to Vo 1-of a secondary side, a terminal C is connected to the cathode of IC3_ A, and a capacitor C3 is connected between a terminal C and a terminal R of IC 2; the anode of the IC3_ A is connected with one end of R3, and the other end of R3 is connected to Vo1 +; the C pole of the IC3_ B is connected with the FB pin of the flyback control circuit IC1, and the E pole is grounded; r1 and R2 compare the divided voltage of Vo1+ with the internal reference voltage of IC2, IC2 amplifies the error voltage between the two, adjusts the voltage of pin C of IC2, so as to adjust the current flowing through IC3_ a, and transmits the current to IC3_ B on the primary side via optical signals, so as to adjust the voltage of pin FB of IC1 connected to IC3_ B, and transmit the signal to the inside of flyback control circuit IC 1.
7. The flyback circuit system without an input electrolytic capacitor as in claim 6, wherein: the DRV pin of the flyback control circuit IC1 is connected with the G pole of Q1, the CS pin is connected with the S pole of Q1 and R6, the GND pin is grounded, the FB pin is connected with the C pole of IC3_ B, the Vcc pin is connected with the negative pole of D3 and the positive pole of C5, and the Vcc pin is connected with the + pin of BD1 through R4 to supply power to IC 1.
8. The flyback circuit system without an input electrolytic capacitor as in claim 1, wherein: the T1 further comprises a second winding Ns2, a diode D4 and a second output filter C6, wherein the second winding Ns2 is provided with a 7 endpoint and an 8 endpoint, the 8 endpoint is connected with the cathode of the C6 and is simultaneously connected with Vo2-, the 7 endpoint is connected with the anode of the D4, the cathode of the D4 is connected with the anode of the C6 and is simultaneously connected with Vo2+, and the second winding Ns2 is rectified by a D4 and filtered by the C6 to provide a second output Vout2 to a load.
9. The flyback circuit system without an input electrolytic capacitor of claim 8, wherein: the flyback circuit comprises a transformer T1, a triode Q1, a diode D1, a diode D2, a diode D3, a diode D5, a resistor R5, a resistor R6, a capacitor C4 and a capacitor C7, wherein the Np side of the T1 is provided with a terminal 1 and a terminal 2, wherein the 1 terminal is connected to one end of the C1, the D1, the C4 and the R5 are connected between the 1 terminal and the 2 terminal, the 1 terminal is connected with one ends of the R5 and the C4, the anode of the D1 is connected with the 2 terminal, the cathode of the D1 is connected with the R5 and the C4, the R5 and the C4 are connected in parallel, the D pole of the Q1 is connected with the 2 terminal, the S pole is connected with one end of the R6, the G pole is connected with the DRV pin of the flyback control circuit IC1, the other end of the R6 is grounded, the Ns1 of the first winding of the T1 has a 3 terminal and a 4 terminal, the 3 end point is connected with the anode of the D2, the 4 end point is grounded and is simultaneously connected with the cathode of the output filter C2 and the anode of the negative output end Vo1-, the cathode of the D2 is connected with the anodes of the C7 and the D5, and the cathode of the D5 is connected with the anode of the C2 and the anode of the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein, the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the 6 terminal is connected with the negative pole of the C5 and is grounded.
10. The flyback circuit system without an input electrolytic capacitor of claim 8, wherein: the flyback circuit comprises a transformer T1, a triode Q1, a diode D1, a diode D2, a diode D3, a diode D5, a resistor R5, a resistor R6, a capacitor C4 and a capacitor C7, wherein the Np side of the T1 is provided with a 1 end point and a 2 end point, the 1 end point is connected to one end of a C1, a D1, a C4 and a R5 are connected between the 1 end point and the 2 end point, the 1 end point is connected with one ends of R5 and C4, the anode of a D1 is connected with the 2 end point, the cathode of a D1 is connected with the R5 and the C4, the R5 and the C4 are connected in parallel, the D of the Q1 is connected with the 2 end point, the S is connected with one end of the R1, the G is connected with the DRV pin of the flyback control circuit IC1, the other end of the R1 is grounded, the first winding 1 of the T1 is provided with a 3 end point and a 4 end point, the D1 is connected with the positive end point of the D1, the negative pole of the C1 is connected with the C1, and the negative pole of the C1 of the filter output terminal of the C1, and the C1 are connected with the C1, and the C1 output end of the C1, and the negative pole of the filter output end point of the C1 are connected with the C1, and the filter output end of the filter circuit, and the output end of the filter circuit is connected with the output of the filter, and the output of the filter circuit of the filter is connected with the C1, and the filter, and the output of the filter, and the filter is connected with the output of the output terminal of the C1 of the output terminal of the C1, the output terminal of the DC 1, the output terminal of the DC 1, the DC 1 of the DC 1, the DC 1 of the output terminal of the DC 1, the DC 1 of the DC 1, the negative electrode of the D2 is connected with the positive electrode of the C2 and the positive output end Vo1 +; the Na side of T1 has 5 terminals and 6 terminals, wherein, the 5 terminal is connected with the anode of D3, the cathode of D3 is connected with the anode of C5 and Vcc pin of IC 1; the 6 terminal is connected with the negative pole of the C5 and is grounded.
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