CN111193424B - Circuit for aging direct-current passive EMI filter - Google Patents

Circuit for aging direct-current passive EMI filter Download PDF

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CN111193424B
CN111193424B CN202010021235.4A CN202010021235A CN111193424B CN 111193424 B CN111193424 B CN 111193424B CN 202010021235 A CN202010021235 A CN 202010021235A CN 111193424 B CN111193424 B CN 111193424B
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electrically connected
negative
circuit
capacitor
resistor
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CN111193424A (en
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李超
崔庆林
冉姝玲
庄伟�
马小敏
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CETC 24 Research Institute
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CETC 24 Research Institute
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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
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/23—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only arranged for operation in parallel
    • 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
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Direct Current Feeding And Distribution (AREA)

Abstract

The invention discloses a circuit for aging a direct current passive EMI filter, which comprises an isolation power supply circuit, a first negative feedback constant current source circuit, a second negative feedback constant current source circuit and a constant voltage source circuit, wherein the isolation power supply circuit outputs three paths of mutually isolated voltages which are respectively used for supplying power to the first negative feedback constant current source circuit, the second negative feedback constant current source circuit and the constant voltage source circuit. In the invention, the first negative feedback constant current source circuit and the second negative feedback constant current source circuit are used for replacing a high-power load resistor or an electronic load, and the constant voltage source circuit is used for providing aging voltage, so that the invalid power loss is low, the system heating is low, and the working energy efficiency ratio is high; in addition, the output of the first negative feedback constant current source circuit, the output of the second negative feedback constant current source circuit and the output of the constant voltage source circuit can be adjusted, so that direct current passive EMI filters with different specifications can be used, the application range is wide, the control is simple, and the use is convenient and reliable.

Description

Circuit for aging direct-current passive EMI filter
Technical Field
The invention relates to the field of aging of EMI filters, in particular to a circuit for aging of a direct-current passive EMI filter.
Background
EMI filters, also known as electromagnetic interference filters, electrical power filters, are used to attenuate common mode interference and differential mode interference on an input power source, and are generally classified into ac and dc types according to the application category. The general direct current EMI filter is formed by passive devices such as LC and the like, and has the characteristics of high rated voltage and large rated current.
As shown in fig. 1, when a dc passive EMI filter is aged, a rated dc voltage is applied to an input end of a product, and a high-power resistor or a high-power dc electronic load is connected in parallel to an output end of the product, so as to meet the requirement of screening a passive device inside the product. Because the direct current loss of the filter is small, when the traditional method is adopted for aging, almost all input power is lost on the heating of a power resistor of an output end or an electronic load, and especially for products with high rated voltage, almost more than 95 percent of input power is dissipated on the load, so that the energy waste is extremely high.
Disclosure of Invention
The invention aims to provide a circuit for aging a direct current passive EMI filter, which can greatly reduce the invalid power.
The technical scheme of the invention is as follows:
a circuit for aging a direct current passive EMI filter comprises an isolation power supply circuit, a first negative feedback constant current source circuit, a second negative feedback constant current source circuit and a constant voltage source circuit, wherein the isolation power supply circuit outputs three paths of mutually isolated voltages which are respectively used for supplying power to the first negative feedback constant current source circuit, the second negative feedback constant current source circuit and the constant voltage source circuit; the constant current output end of the first negative feedback constant current source circuit is electrically connected with the positive constant voltage output end of the constant voltage source circuit, and the constant current return end is used for connecting the positive output end of the direct current passive EMI filter; the constant current return end of the second negative feedback constant current source circuit is electrically connected with the constant voltage output negative end of the constant voltage source circuit, and the constant current output end is used for being connected with the output negative end of the direct current passive EMI filter; and the positive constant-voltage output end of the constant-voltage source circuit is used for being connected with the positive input end of the direct-current passive EMI filter, and the negative constant-voltage output end of the constant-voltage source circuit is used for being connected with the negative input end of the direct-current passive EMI filter.
Furthermore, the isolation power supply circuit comprises an isolation transformer T1, a first rectification circuit, a second rectification circuit and a third rectification circuit, wherein the input end of the isolation transformer T1 is connected with an external alternating current power supply, the output end of the isolation transformer T1 is provided with three windings, and the three windings are respectively and electrically connected with the first rectification circuit, the second rectification circuit and the third rectification circuit;
the output positive end of the first rectifying circuit is electrically connected with the input positive end of the first negative feedback constant current source circuit, and the output negative end of the first rectifying circuit is electrically connected with the input negative end of the first negative feedback constant current source circuit; the output positive end of the second rectifying circuit is electrically connected with the input positive end of the constant voltage source circuit, and the output negative end of the second rectifying circuit is electrically connected with the input negative end of the constant voltage source circuit; and the output positive end of the third rectifying circuit is electrically connected with the input positive end of the second negative feedback constant current source circuit, and the output negative end of the third rectifying circuit is electrically connected with the input negative end of the second negative feedback constant current source circuit.
Further, the first rectifying circuit comprises a diode D1 and a capacitor C1, the negative end of the diode D1 is electrically connected with the positive end of the capacitor C1, the positive end of the diode D1 and the negative end of the capacitor C1 are electrically connected with the isolation transformer T1 as two input ends of the first rectifying circuit respectively, and the positive end of the capacitor C1 is electrically connected with the input positive end of the first negative feedback constant current source circuit as the output positive end of the first rectifying circuit; the negative end of the capacitor C1 is the output negative end of the first rectifying circuit and is electrically connected with the input negative end of the first negative feedback constant current source circuit;
the second rectifying circuit comprises a diode D3 and a capacitor C7, the negative end of the diode D3 is electrically connected with the positive end of the capacitor C7, the positive end of the diode D3 and the negative end of the capacitor C7 are used as two input ends of the second rectifying circuit and are respectively electrically connected with an isolation transformer T1, and the positive end of the capacitor C3 is used as the output positive end of the second rectifying circuit and is electrically connected with the input positive end of the constant-voltage power supply circuit; the negative end of the capacitor C3 is the output negative end of the second rectifying circuit and is electrically connected with the input negative end of the constant-voltage power supply circuit;
the third rectifying circuit comprises a diode D5 and a capacitor C10, the negative end of the diode D5 is electrically connected with the positive end of the capacitor C10, the positive end of the diode D5 and the negative end of the capacitor C10 are used as two input ends of the third rectifying circuit and are respectively electrically connected with an isolation transformer T1, and the positive end of the capacitor C10 is used as the output positive end of the third rectifying circuit and is electrically connected with the input positive end of the second negative feedback constant current source circuit; and the negative end of the capacitor C10 is the output negative end of the third rectifying circuit and is electrically connected with the input negative end of the second negative feedback constant current source circuit.
Further, the first negative feedback constant current source circuit and the second negative feedback constant current source circuit have the same structure.
Further, the first negative feedback constant current source circuit comprises a resistor R1, a resistor R2, a resistor R3, a potentiometer RVT1, a capacitor C2, a capacitor C3, a zener diode D2, a field effect transistor N1 and an operational amplifier U1; the first end of the resistor R1 is electrically connected to an isolation power supply circuit, the first end of the resistor R1 is also electrically connected to the positive end of the constant voltage output of the constant voltage source circuit, the second end of the resistor R1 is electrically connected to the negative end of the zener diode D2, the positive end of the zener diode D2 is electrically connected to the isolation power supply circuit, the capacitor C2 is connected in parallel to the zener diode D2, the negative end of the zener diode D2 is electrically connected to the first end of the potentiometer RVT1, the second end of the potentiometer RVT1 is electrically connected to the positive end of the zener diode D2, the variable resistance end is electrically connected to the non-inverting input end of the operational amplifier U1, the non-inverting input end of the operational amplifier U1 is electrically connected to the positive end of the zener diode D2 through the capacitor C3, the negative input end is electrically connected to the source of the FET N1, the power supply end is electrically connected to the negative end of the zener diode D2, the output end of the direct current passive EMI filter is electrically connected with the grid electrode of a field effect transistor N1 through a resistor R2, the source electrode of the field effect transistor N1 is electrically connected with the positive end of a voltage stabilizing diode D2 through a resistor R3, and the drain electrode of the field effect transistor N1 is used for being connected with the output positive end of the direct current passive EMI filter;
the second negative feedback constant current source circuit comprises a resistor R10, a resistor R11, a resistor R12, a potentiometer RVT3, a capacitor C11, a capacitor C12, a voltage stabilizing diode D6, a field effect tube N3 and an operational amplifier U3; the first end of the resistor R10 is electrically connected to an isolation power supply circuit, the first end of the resistor R10 is further used for connecting the output negative terminal of the DC passive EMI filter, the second end of the resistor R10 is electrically connected to the negative terminal of the zener diode D6, the positive terminal of the zener diode D6 is electrically connected to the isolation power supply circuit, the capacitor C11 is connected in parallel to the zener diode D6, the negative terminal of the zener diode D6 is further electrically connected to the first end of the potentiometer RVT3, the second end of the potentiometer RVT3 is electrically connected to the positive terminal of the zener diode D6, the varistor terminal is electrically connected to the non-inverting input terminal of the operational amplifier U3, the non-inverting input terminal of the operational amplifier U3 is electrically connected to the positive terminal of the zener diode D6 through the capacitor C12, the negative input terminal is electrically connected to the source of the FET N3, the power supply terminal is electrically connected to the negative terminal of the zener diode D6, and the ground terminal is electrically, the output end of the constant voltage source circuit is electrically connected with the grid electrode of a field effect transistor N3 through a resistor R11, the source electrode of the field effect transistor N3 is electrically connected with the positive end of a voltage stabilizing diode D6 through a resistor R12, and the drain electrode of the constant voltage source circuit is electrically connected with the negative end of the constant voltage output of the constant voltage source circuit.
Further, the potentiometer RVT1 and the potentiometer RVT3 are two groups of potentiometers on the same duplex potentiometer, so that the potentiometer RVT1 and the potentiometer RVT3 can be synchronously adjusted.
Further, the constant voltage source circuit comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a potentiometer RVT2, a capacitor C5, a capacitor C6, a capacitor C8, a capacitor C9, a zener diode D4, a zener diode D7, a triode Q1, a field effect transistor N2 and an operational amplifier U1; the first end of the resistor R4 is electrically connected with the isolation power supply circuit, the second end of the resistor R4 is electrically connected with the negative end of the voltage stabilizing diode D4, the positive terminal of the voltage stabilizing diode D4 is electrically connected with an isolation power supply circuit, the capacitor C8 is connected with the voltage stabilizing diode D4 in parallel, the negative end of the voltage-stabilizing diode D4 is electrically connected with the first end of a potentiometer RVT2, the second end of the potentiometer RVT2 is electrically connected with the positive end of a voltage-stabilizing diode D4, the variable resistance end is electrically connected with the non-inverting input end of an operational amplifier U2, the non-inverting input end of the operational amplifier U2 is electrically connected with the positive end of a voltage stabilizing diode D4 through a capacitor C9, the negative input end of the operational amplifier U2 is electrically connected with the positive end of a voltage stabilizing diode D4 through a resistor R9, the power supply end of the operational amplifier U is electrically connected with the negative end of a voltage stabilizing diode D4, the grounding end of the operational amplifier U2 is electrically connected with the positive end of a voltage stabilizing diode D4, and the output end of the operational amplifier U2 is electrically connected with;
the emitter of the triode Q1 is electrically connected with the positive terminal of the zener diode D4 through a resistor R8, the collector is electrically connected with the gate of the field effect transistor N2, the gate of the field effect transistor N2 is electrically connected with the source thereof through a zener diode D7, the resistor R5 is connected in parallel with the zener diode D7, the source of the field effect transistor N2 is electrically connected with the first terminal of the resistor R4, the drain is electrically connected with the negative phase input terminal of the operational amplifier U2 through a resistor R6, the drain of the field effect transistor N2 is also electrically connected with the positive terminal of the capacitor C6, the positive terminal of the capacitor C6 is used for connecting the input positive terminal of the dc passive EMI filter, the negative terminal of the capacitor C6 is electrically connected with the positive terminal of the zener diode D4, the negative terminal of the capacitor C6 is also used for connecting the input negative terminal of the dc passive EMI filter, and the capacitor C5 is connected in parallel.
Further, the constant voltage power supply circuit further comprises a capacitor C4, and the capacitor C4 is connected in parallel with the resistor R6 and is used for improving the load change response speed of the constant voltage power supply circuit.
Has the advantages that: in the invention, the first negative feedback constant current source circuit and the second negative feedback constant current source circuit are used for replacing a high-power load resistor or an electronic load, and the constant voltage source circuit is used for providing aging voltage, so that the invalid power loss is low, the system heating is low, and the working energy efficiency ratio is high; in addition, the output of the first negative feedback constant current source circuit, the output of the second negative feedback constant current source circuit and the output of the constant voltage source circuit can be adjusted, so that direct current passive EMI filters with different specifications can be used, the application range is wide, the control is simple, and the use is convenient and reliable.
Drawings
FIG. 1 is a circuit diagram of a conventional DC passive EMI filter burn-in circuit;
FIG. 2 is a block diagram of the present invention;
fig. 3 is a circuit diagram of the present invention.
Detailed Description
The invention will be further explained with reference to the drawings.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the term "connected" is to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, or a communication between two elements, or may be a direct connection or an indirect connection through an intermediate medium, and a specific meaning of the term may be understood by those skilled in the art according to specific situations.
As shown in fig. 2, the circuit for aging a direct current passive EMI filter of the present invention includes an isolation power supply circuit 1, a first negative feedback constant current source circuit 2, a second negative feedback constant current source circuit 3, and a constant voltage source circuit 4, where the isolation power supply circuit 1 outputs three mutually isolated voltages, which are respectively used to supply power to the first negative feedback constant current source circuit 2, the second negative feedback constant current source circuit 3, and the constant voltage source circuit 4; the constant current output end of the first negative feedback constant current source circuit 2 is electrically connected with the positive constant voltage output end of the constant voltage source circuit 4, and the constant current return end is used for connecting the positive output end of the direct current passive EMI filter 5; the constant current return end of the second negative feedback constant current source circuit 3 is electrically connected with the constant voltage output negative end of the constant voltage source circuit 4, and the constant current output end is used for being connected with the output negative end of the direct current passive EMI filter 5; and the positive constant-voltage output end of the constant-voltage source circuit 4 is used for being connected with the positive input end of the direct-current passive EMI filter 5, and the negative constant-voltage output end of the constant-voltage source circuit 4 is used for being connected with the negative input end of the direct-current passive EMI filter 5.
As shown in fig. 3, the isolation power supply circuit 1 includes an isolation transformer T1, a first rectification circuit 11, a second rectification circuit 12 and a third rectification circuit 13, an input end of the isolation transformer T1 is connected to an external ac power supply, an output end of the isolation transformer T1 is provided with three windings, and the three windings are respectively electrically connected to the first rectification circuit 11, the second rectification circuit 12 and the third rectification circuit 13; of course, the isolation transformer T1 may be replaced by three one-to-one transformers, and the input ends of the three one-to-one transformers are connected in parallel.
The first rectifying circuit 11 comprises a diode D1 and a capacitor C1, the positive terminal of the diode D1 is electrically connected with the first output terminal of the isolation transformer T1, the negative terminal is electrically connected with the positive terminal of the capacitor C1, and the positive terminal of the capacitor C1 is electrically connected with the input positive terminal of the first negative feedback constant current source circuit 2; the negative end of the capacitor C1 is electrically connected with the second output end of the isolation transformer T1, and the negative end of the capacitor C1 is also electrically connected with the input negative end of the first negative feedback constant current source circuit 2;
the second rectifying circuit 12 comprises a diode D3 and a capacitor C7, the positive end of the diode D3 is electrically connected with the third output end of the isolation transformer T1, the negative end of the diode D3 is electrically connected with the positive end of the capacitor C7, and the positive end of the capacitor C7 is electrically connected with the input positive end of the constant-voltage power supply circuit 4; the negative end of the capacitor C7 is electrically connected with the fourth output end of the isolation transformer T1, and the negative end of the capacitor C7 is also electrically connected with the input negative end of the constant-voltage power supply circuit 4;
the third rectifying circuit 13 comprises a diode D5 and a capacitor C10, the positive terminal of the diode D5 is electrically connected with the fifth output terminal of the isolation transformer T1, the negative terminal is electrically connected with the positive terminal of the capacitor C10, and the positive terminal of the capacitor C10 is electrically connected with the input positive terminal of the second negative feedback constant current source circuit 3; the negative terminal of the capacitor C10 is electrically connected to the sixth output terminal of the isolation transformer T1, and the negative terminal of the capacitor C10 is also electrically connected to the input negative terminal of the second negative feedback constant current source circuit 3.
The first negative feedback constant current source circuit 2 and the second negative feedback constant current source circuit 3 have the same structure; the first negative feedback constant current source circuit 2 comprises a resistor R1, a resistor R2, a resistor R3, a potentiometer RVT1, a capacitor C2, a capacitor C3, a voltage stabilizing diode D2, a field effect transistor N1 and an operational amplifier U1; the first end of the resistor R1 is electrically connected to the isolated power supply circuit 1, the first end of the resistor R1 is also electrically connected to the positive end of the constant voltage output of the constant voltage source circuit 4, the second end of the resistor R1 is electrically connected to the negative end of the zener diode D2, the positive end of the zener diode D2 is electrically connected to the isolated power supply circuit 1, the capacitor C2 is connected in parallel to the zener diode D2, the negative end of the zener diode D2 is electrically connected to the first end of the potentiometer RVT1, the second end of the potentiometer RVT1 is electrically connected to the positive end of the zener diode D2, the varistor end is electrically connected to the non-inverting input end of the operational amplifier U1, the non-inverting input end of the operational amplifier U1 is electrically connected to the positive end of the zener diode D2 through the capacitor C3, the negative input end is electrically connected to the source of the FET N1, the power supply end is electrically connected to the negative end of the zener diode D2, and, the output end is electrically connected with the grid electrode of a field effect transistor N1 through a resistor R2, the source electrode of the field effect transistor N1 is electrically connected with the positive end of a voltage stabilizing diode D2 through a resistor R3, and the drain electrode is used for connecting the output positive end of the direct current passive EMI filter 5.
The second negative feedback constant current source circuit 3 comprises a resistor R10, a resistor R11, a resistor R12, a potentiometer RVT3, a capacitor C11, a capacitor C12, a voltage stabilizing diode D6, a field effect tube N3 and an operational amplifier U3, wherein the potentiometer RVT1 and the potentiometer RVT3 are two groups of potentiometers on the same duplex potentiometer; the first end of the resistor R10 is electrically connected to the isolated power supply circuit 1, the first end of the resistor R10 is further used for connecting the output negative terminal of the dc passive EMI filter 5, the second end of the resistor R10 is electrically connected to the negative terminal of the zener diode D6, the positive terminal of the zener diode D6 is electrically connected to the isolated power supply circuit 1, the capacitor C11 is connected in parallel to the zener diode D6, the negative terminal of the zener diode D6 is further electrically connected to the first end of the potentiometer RVT3, the second end of the potentiometer t3 is electrically connected to the positive terminal of the zener diode D6, the varistor terminal is electrically connected to the non-inverting input terminal of the operational amplifier U3, the non-inverting input terminal of the operational amplifier U3 is electrically connected to the positive terminal of the zener diode D48 through the capacitor C12, the negative phase input terminal is electrically connected to the source of the fet N3, the power supply terminal is electrically connected to the negative terminal of the zener diode D6, and the ground terminal is electrically connected, the output end is electrically connected with the grid electrode of a field effect transistor N3 through a resistor R11, the source electrode of the field effect transistor N3 is electrically connected with the positive end of a voltage stabilizing diode D6 through a resistor R12, and the drain electrode is electrically connected with the negative end of the constant voltage output of the constant voltage source circuit 4.
The constant-voltage power supply circuit 4 comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a potentiometer RVT2, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C8, a capacitor C9, a zener diode D4, a zener diode D7, a triode Q1, a field effect transistor N2 and an operational amplifier U1; the first end of the resistor R4 is electrically connected with the isolated power supply circuit 1, the second end of the resistor R4 is electrically connected with the negative end of the voltage stabilizing diode D4, the positive terminal of the voltage stabilizing diode D4 is electrically connected with the isolation power supply circuit 1, the capacitor C8 is connected with the voltage stabilizing diode D4 in parallel, the negative end of the voltage-stabilizing diode D4 is electrically connected with the first end of a potentiometer RVT2, the second end of the potentiometer RVT2 is electrically connected with the positive end of a voltage-stabilizing diode D4, the variable resistance end is electrically connected with the non-inverting input end of an operational amplifier U2, the non-inverting input end of the operational amplifier U2 is electrically connected with the positive end of the zener diode D4 through a capacitor C9, the negative input end is electrically connected with the positive end of the zener diode D4 through a resistor R9, the power supply end is electrically connected with the negative end of the zener diode D4, the ground end is electrically connected with the positive end of the zener diode D4, and the output end is electrically connected with the base of the triode Q1 through a resistor R7.
The emitter of the triode Q1 is electrically connected with the positive end of a voltage stabilizing diode D4 through a resistor R8, the collector of the triode Q1 is electrically connected with the grid of a field effect transistor N2, the grid of the field effect transistor N2 is electrically connected with the source of the field effect transistor N48325 through a voltage stabilizing diode D7, the resistor R5 is connected with the voltage stabilizing diode D7 in parallel, the source of the field effect transistor N2 is electrically connected with the first end of a resistor R4, the drain of the field effect transistor N2 is electrically connected with the negative phase input end of an operational amplifier U2 through a resistor R6, and the capacitor C63; the drain of the field effect transistor N2 is also electrically connected to the positive terminal of a capacitor C6, the positive terminal of the capacitor C6 is used to connect the positive input terminal of the dc passive EMI filter 5, the negative terminal of the capacitor C6 is electrically connected to the positive terminal of a zener diode D4, the negative terminal of the capacitor C6 is also used to connect the negative input terminal of the dc passive EMI filter 5, and the capacitor C5 is connected in parallel with the capacitor C6.
The working principle of the embodiment is as follows:
as shown in fig. 2 and 3, after the external ac power is supplied to the input terminal of the transformer T1, three isolated ac voltages are respectively output to the three windings at the output terminal of the transformer T1; the first path of voltage is sent to the first negative feedback constant current source circuit 2, half-wave rectification is carried out on the first path of voltage through a diode D1 and a capacitor C1, the obtained direct current voltage is stabilized through a voltage stabilizing circuit consisting of a resistor R1 and a voltage stabilizing diode D2, and then the direct current voltage is further filtered through C2 to serve as the power supply voltage of the operational amplifier U1. Meanwhile, the voltage filtered by the C2 is divided by the potentiometer RVT1 and filtered by the C3, and then is sent to the non-inverting input terminal of the U1, and the set value of the output current of the first negative feedback constant current source circuit 2 can be adjusted by adjusting the potentiometer RVT 1. The output end of the U1 controls the size of the conducting channel resistance of the field effect transistor N1 through the resistor R2, and further adjusts the current flowing between the drain D of the N1 and the source S, so that constant current output is realized; specifically, when the current flowing between the drain D and the source S of N1 is greater than the current setting value, the voltage generated across the resistor R3 increases and acts on the inverting input terminal of U1 in a feedback manner, so as to reduce the output voltage of U1, further increase the channel resistance of N1, and reduce the current flowing between the drain D and the source S of N1 to the current setting value; when the current flowing between the drain D and the source S of the N1 is smaller than the current set value, the voltage generated at the two ends of the resistor R3 is reduced and acts on the inverting input end of the U1 in a feedback mode, so that the output voltage of the U1 is increased, the channel resistance of the N1 is reduced, and the current flowing between the drain D and the source S of the N1 is increased to the current set value.
The third path of voltage output by the transformer T1 is sent to the second negative feedback constant current source circuit 3, and since the circuit structures of the second negative feedback constant current source circuit 3 and the first negative feedback constant current source circuit 2 are completely the same, the working principle thereof is also the same as that of the first negative feedback constant current source circuit 2.
The second path of voltage output by the transformer T1 is sent to the constant voltage source circuit 4, half-wave rectification is performed through the diode D3 and the capacitor C7, the obtained direct current voltage is stabilized through a voltage stabilizing circuit composed of the resistor R4 and the voltage stabilizing diode D4, and then further filtered through the C8 to be used as the power supply voltage of the operational amplifier U2. Meanwhile, the voltage filtered by the C8 is divided by a potentiometer RVT2 and filtered by a C9 and then is input to a non-inverting input end of the U2, a set value of the output voltage of the constant voltage source circuit 4 can be adjusted by adjusting the potentiometer RVT2, and the output end of the U2 controls the current I between the collector and the emitter of the triode Q1 through a resistor R7CEThereby changing the voltage drop across the resistor R5, i.e. changing the voltage V between the gate and the source of the FET N2GSFurther, the magnitude of the output voltage of the constant voltage source circuit 4 is controlled; specifically, when the voltage output by the constant voltage source circuit 4 is greater than the voltage set value, the voltage output to the inverting input terminal of U2 by the resistor divider circuit composed of R6 and R9 increases, the output voltage of U2 decreases, and I of Q1 decreasesCEWhen the voltage across the R5 decreases, the on-resistance of N2 increases, and the voltage output from the constant voltage source circuit 4 decreases to a voltage set value; when the voltage output by the constant voltage source circuit 4 is smaller than the voltage set value, the voltage output to the inverting input end of U2 by the resistor voltage dividing circuit consisting of R6 and R9 is reduced, so that the output voltage of U2 is reduced, and I of Q1 is increasedCEAs the voltage across R5 increases, the on-resistance of N2 decreases, and the voltage output from the constant voltage power supply circuit 4 increases to the voltage set value.
The capacitor C4 is connected with the resistor R6 in parallel and is used for improving the load change response speed of the constant voltage source circuit 4; the emitter series resistor R8 of the transistor Q2 is used to raise the quiescent operating point of the base of the transistor Q2 to reduce the requirement that the operational amplifier U2 outputs to the lower power rail. The non-inverting input end of the U2 is an output voltage size setting end of the constant voltage source, the port is divided by a potentiometer RVT2, filtered by C12 and input to the non-inverting end, and the voltage size of the constant voltage source can be adjusted by adjusting the potentiometer RVT 2.
When the direct current passive EMI filter 5 is aged, the constant-current output end of the first negative feedback constant current source circuit 2 is electrically connected with the output positive end of the constant voltage source circuit 4 and then electrically connected with the input positive end IN + of the direct current passive EMI filter 5, and the constant-current return end of the first negative feedback constant current source circuit 2 is electrically connected with the output positive end OUT + of the direct current passive EMI filter 5; the constant current return end of the second negative feedback constant current source circuit 3 is electrically connected with the output negative end of the constant voltage source circuit 4 and then electrically connected with the input negative end IN-of the direct current passive EMI filter 5, and the constant current output end of the second negative feedback constant current source circuit 3 is electrically connected with the output negative end OUT-of the direct current passive EMI filter 5. The current output by the constant current output end of the first negative feedback constant current source circuit 2 is used for aging the inductance between the input positive end IN + and the output positive end OUT + of the direct current passive EMI filter 5, the current output by the constant current output end of the second negative feedback constant current source circuit 3 is used for aging the inductance between the output negative end OUT-and the input negative end IN-of the direct current passive EMI filter 5, and the voltage output by the constant voltage source circuit 4 is used for aging the capacitance of the direct current passive EMI filter 5, so that the no-load aging of the direct current passive EMI filter 5 is realized; the aging efficiency is high, the loss of the invalid power is small, and the system heating is small.
The set values of the output currents of the first negative feedback constant current source circuit 2 and the second negative feedback constant current source circuit 3 can be adjusted by adjusting the potentiometers RVT1 and RVT3, because the potentiometers RVT1 and RVT3 are double potentiometers, synchronous adjustment of the RVT1 and the RVT3 can be ensured during adjustment, and the set value of the output voltage of the constant voltage source circuit 4 can be adjusted by adjusting the potentiometer RVT2, so that the direct current passive EMI filters 5 with different specifications can be aged, and the passive EMI filter has the advantages of wide application range, simplicity in control and convenience and reliability in use.
The undescribed parts of the present invention are consistent with the prior art, and are not described herein.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures made by using the contents of the present specification and the drawings can be directly or indirectly applied to other related technical fields, and are within the scope of the present invention.

Claims (8)

1. A circuit for aging a dc passive EMI filter, characterized in that: the power supply circuit comprises an isolation power supply circuit (1), a first negative feedback constant current source circuit (2), a second negative feedback constant current source circuit (3) and a constant voltage source circuit (4), wherein the isolation power supply circuit (1) outputs three paths of mutually isolated voltages which are respectively used for supplying power to the first negative feedback constant current source circuit (2), the second negative feedback constant current source circuit (3) and the constant voltage source circuit (4); the constant-current output end of the first negative feedback constant-current source circuit (2) is electrically connected with the positive constant-voltage output end of the constant-voltage source circuit (4), and the constant-current return end is used for connecting the positive output end of the direct-current passive EMI filter (5); the constant current return end of the second negative feedback constant current source circuit (3) is electrically connected with the constant voltage output negative end of the constant voltage source circuit (4), and the constant current output end is used for being connected with the output negative end of the direct current passive EMI filter (5); and the positive constant-voltage output end of the constant-voltage source circuit (4) is used for being connected with the positive input end of the direct-current passive EMI filter (5), and the negative constant-voltage output end is used for being connected with the negative input end of the direct-current passive EMI filter (5).
2. The circuit for dc passive EMI filter burn-in of claim 1, wherein: the isolation power supply circuit (1) comprises an isolation transformer T1, a first rectifying circuit (11), a second rectifying circuit (12) and a third rectifying circuit (13), wherein the input end of the isolation transformer T1 is connected with an external alternating current power supply, the output end of the isolation transformer T1 is provided with six output ends of three windings, and the three windings are respectively and electrically connected with the first rectifying circuit (11), the second rectifying circuit (12) and the third rectifying circuit (13);
the output positive end of the first rectifying circuit (11) is electrically connected with the input positive end of the first negative feedback constant current source circuit (2), and the output negative end is electrically connected with the input negative end of the first negative feedback constant current source circuit (2); the output positive end of the second rectifying circuit (12) is electrically connected with the input positive end of the constant voltage source circuit (4), and the output negative end is electrically connected with the input negative end of the constant voltage source circuit (4); and the output positive end of the third rectifying circuit (13) is electrically connected with the input positive end of the second negative feedback constant current source circuit (3), and the output negative end is electrically connected with the input negative end of the second negative feedback constant current source circuit (3).
3. The circuit for dc passive EMI filter burn-in of claim 2, wherein: the first rectifying circuit (11) comprises a diode D1 and a capacitor C1, the negative end of the diode D1 is electrically connected with the positive end of a capacitor C1, the positive end of the diode D1 and the negative end of a capacitor C1 are used as two input ends of the first rectifying circuit (11) and are respectively electrically connected with an isolation transformer T1, and the positive end of the capacitor C1 is used as the output positive end of the first rectifying circuit (11) and is electrically connected with the input positive end of the first negative feedback constant current source circuit (2); the negative end of the capacitor C1 is the output negative end of the first rectifying circuit (11) and is electrically connected with the input negative end of the first negative feedback constant current source circuit (2);
the second rectifying circuit (12) comprises a diode D3 and a capacitor C7, the negative end of the diode D3 is electrically connected with the positive end of a capacitor C7, the positive end of the diode D3 and the negative end of a capacitor C7 are used as two input ends of the second rectifying circuit (12) and are respectively electrically connected with an isolation transformer T1, and the positive end of the capacitor C3 is used as the output positive end of the second rectifying circuit (12) and is electrically connected with the input positive end of the constant-voltage power supply circuit (4); the negative end of the capacitor C3 is the output negative end of the second rectifying circuit (12) and is electrically connected with the input negative end of the constant voltage source circuit (4);
the third rectifying circuit (13) comprises a diode D5 and a capacitor C10, the negative end of the diode D5 is electrically connected with the positive end of a capacitor C10, the positive end of the diode D5 and the negative end of a capacitor C10 are used as two input ends of the third rectifying circuit (13) and are respectively electrically connected with an isolation transformer T1, and the positive end of the capacitor C10 is used as the output positive end of the third rectifying circuit (13) and is electrically connected with the input positive end of the second negative feedback constant current source circuit (3); the negative end of the capacitor C10 is the output negative end of the third rectifying circuit (13) and is electrically connected with the input negative end of the second negative feedback constant current source circuit (3).
4. The circuit for dc passive EMI filter burn-in of claim 1, wherein: the first negative feedback constant current source circuit (2) and the second negative feedback constant current source circuit (3) have the same structure.
5. The circuit for dc passive EMI filter burn-in of claim 3, wherein: the first negative feedback constant current source circuit (2) comprises a resistor R1, a resistor R2, a resistor R3, a potentiometer RVT1, a capacitor C2, a capacitor C3, a voltage stabilizing diode D2, a field effect transistor N1 and an operational amplifier U1; the first end of the resistor R1 is electrically connected with the isolation power supply circuit (1), the first end of the resistor R1 is also electrically connected with the positive end of the constant voltage output of the constant voltage source circuit (4), the second end of the resistor R1 is electrically connected with the negative end of the zener diode D2, the positive end of the zener diode D2 is electrically connected with the isolation power supply circuit (1), the capacitor C2 is connected with the zener diode D2 in parallel, the negative end of the zener diode D2 is electrically connected with the first end of the potentiometer RVT1, the second end of the potentiometer RVT1 is electrically connected with the positive end of the zener diode D2, the variable resistance end is electrically connected with the non-inverting input end of the operational amplifier U6334, the non-inverting input end of the operational amplifier U1 is electrically connected with the positive end of the zener diode D2 through the capacitor C3, the negative phase input end is electrically connected with the source of the FET N1, the power supply end is electrically connected with the negative end of the zener diode D2, and the, the output end of the direct current passive EMI filter is electrically connected with the grid electrode of a field effect transistor N1 through a resistor R2, the source electrode of the field effect transistor N1 is electrically connected with the positive end of a voltage stabilizing diode D2 through a resistor R3, and the drain electrode of the field effect transistor N1 is used for being connected with the output positive end of the direct current passive EMI filter (5);
the second negative feedback constant current source circuit (3) comprises a resistor R10, a resistor R11, a resistor R12, a potentiometer RVT3, a capacitor C11, a capacitor C12, a voltage stabilizing diode D6, a field effect transistor N3 and an operational amplifier U3; the first end of the resistor R10 is electrically connected with the isolation power supply circuit (1), the first end of the resistor R10 is also used for connecting the output negative terminal of the direct current passive EMI filter (5), the second end of the resistor R10 is electrically connected with the negative terminal of the zener diode D6, the positive terminal of the zener diode D6 is electrically connected with the isolation power supply circuit (1), the capacitor C11 is connected in parallel with the zener diode D6, the negative terminal of the zener diode D6 is also electrically connected with the first end of the potentiometer RVT3, the second end of the potentiometer RVT3 is electrically connected with the positive terminal of the zener diode D6, the varistor terminal is electrically connected with the non-inverting input terminal of the operational amplifier U3, the non-inverting input terminal of the operational amplifier U3 is electrically connected with the positive terminal of the zener diode D6 through the capacitor C38, the negative phase input terminal is electrically connected with the source of the field effect transistor N3, the power supply terminal is electrically connected with the negative terminal of the zener diode D6, and the ground terminal is electrically, the output end of the constant voltage source circuit is electrically connected with the grid electrode of a field effect transistor N3 through a resistor R11, the source electrode of the field effect transistor N3 is electrically connected with the positive end of a voltage stabilizing diode D6 through a resistor R12, and the drain electrode of the constant voltage source circuit is electrically connected with the negative end of the constant voltage output of the constant voltage source circuit (4).
6. The circuit for dc passive EMI filter burn-in of claim 5, wherein: the potentiometer RVT1 and the potentiometer RVT3 are two groups of potentiometers on the same duplex potentiometer.
7. The circuit for dc passive EMI filter burn-in of claim 1, wherein: the constant-voltage source circuit (4) comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a potentiometer RVT2, a capacitor C5, a capacitor C6, a capacitor C8, a capacitor C9, a zener diode D4, a zener diode D7, a triode Q1, a field effect transistor N2 and an operational amplifier U1; the first end of the resistor R4 is electrically connected with the isolation power supply circuit (1), the second end of the resistor R4 is electrically connected with the negative end of the voltage stabilizing diode D4, the positive terminal of the voltage stabilizing diode D4 is electrically connected with the isolation power supply circuit (1), the capacitor C8 is connected with the voltage stabilizing diode D4 in parallel, the negative end of the voltage-stabilizing diode D4 is electrically connected with the first end of a potentiometer RVT2, the second end of the potentiometer RVT2 is electrically connected with the positive end of a voltage-stabilizing diode D4, the variable resistance end is electrically connected with the non-inverting input end of an operational amplifier U2, the non-inverting input end of the operational amplifier U2 is electrically connected with the positive end of a voltage stabilizing diode D4 through a capacitor C9, the negative input end of the operational amplifier U2 is electrically connected with the positive end of a voltage stabilizing diode D4 through a resistor R9, the power supply end of the operational amplifier U is electrically connected with the negative end of a voltage stabilizing diode D4, the grounding end of the operational amplifier U2 is electrically connected with the positive end of a voltage stabilizing diode D4, and the output end of the operational amplifier U2 is electrically connected with;
the emitter of the triode Q1 is electrically connected with the positive terminal of a voltage stabilizing diode D4 through a resistor R8, the collector is electrically connected with the gate of a field effect transistor N2, the gate of the field effect transistor N2 is electrically connected with the source thereof through a voltage stabilizing diode D7, the resistor R5 is connected in parallel with a voltage stabilizing diode D7, the source of the field effect transistor N2 is electrically connected with the first terminal of a resistor R4, the drain is electrically connected with the negative phase input terminal of an operational amplifier U2 through a resistor R6, the drain of the field effect transistor N2 is also electrically connected with the positive terminal of a capacitor C6, the positive terminal of the capacitor C6 is used for connecting the input positive terminal of a direct current passive EMI filter (5), the negative terminal of the capacitor C6 is electrically connected with the positive terminal of a voltage stabilizing diode 737D 6, the negative terminal of the capacitor C6 is also used for connecting the input negative terminal of the direct current passive filter (5), and the capacitor C5 is.
8. The circuit for dc passive EMI filter burn-in of claim 7, wherein: the constant voltage source circuit (4) further comprises a capacitor C4, and the capacitor C4 is connected with the resistor R6 in parallel.
CN202010021235.4A 2020-01-09 2020-01-09 Circuit for aging direct-current passive EMI filter Active CN111193424B (en)

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