CN211426739U - Test circuit - Google Patents
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- CN211426739U CN211426739U CN201922025077.5U CN201922025077U CN211426739U CN 211426739 U CN211426739 U CN 211426739U CN 201922025077 U CN201922025077 U CN 201922025077U CN 211426739 U CN211426739 U CN 211426739U
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Abstract
The utility model discloses a test circuit. The test circuit includes: an alternating current power supply, an impedance stabilizing circuit and a frequency spectrometer; the first end of the impedance stabilizing circuit is connected with an alternating current power supply, and the second end of the impedance stabilizing circuit is connected with a switching power supply and is used for isolating the alternating current power supply from the switching power supply; the first end of the frequency spectrograph is connected with the third end of the impedance stabilizing circuit, the second end of the frequency spectrograph is grounded, and the frequency spectrograph is used for displaying the interference information frequency spectrum of the switching power supply. The embodiment of the utility model provides an in, be connected with the spectrometer through switching power supply's test circuit, realized the spectrometer to switching power supply's interference information frequency spectrum's analysis, reduced switching power supply's test cost, can be applied to the test of finished product total coverage.
Description
Technical Field
The utility model relates to a switching power supply electromagnetic interference radiation test circuit especially relates to a test circuit.
Background
Almost all electronic devices require a regulated dc power supply to supply power. The switching power supply is a power supply mode which is widely adopted at present, and has the advantages of small volume, light weight, high energy conversion efficiency and the like. However, the switching power supply operates in a higher frequency state, and the external radiation interference is stronger, so that the switching power supply needs to test radiation in an electromagnetic interference darkroom, and the radiation value in the electromagnetic interference darkroom needs to meet the requirements of regulations.
Because the testing cost of the switching power supply in the electromagnetic interference dark room is very high and the switching power supply needs to consume a long time, the switching power supply cannot be applied to the full-coverage testing of finished products.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a test circuit to realize the analysis of frequency spectrograph to switching power supply's interference information frequency spectrum, reduce switching power supply's test cost.
The embodiment of the utility model provides a test circuit, include:
an alternating current power supply, an impedance stabilizing circuit and a frequency spectrometer;
the first end of the impedance stabilizing circuit is connected with an alternating current power supply, and the second end of the impedance stabilizing circuit is connected with a switching power supply and is used for isolating the alternating current power supply from the switching power supply;
the first end of the frequency spectrograph is connected with the third end of the impedance stabilizing circuit, the second end of the frequency spectrograph is grounded, and the frequency spectrograph is used for displaying the interference information frequency spectrum of the switching power supply.
Optionally, the third end of the impedance stabilizing circuit includes a live wire output end and a zero line output end;
the impedance stabilizing circuit comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first inductor, a second inductor, a first resistor and a second resistor, wherein the first end of the first capacitor is electrically connected with a live wire end of an alternating current power supply and the first end of the first inductor respectively, and the second end of the first capacitor and the first end of the second capacitor are grounded; the second end of the first inductor is electrically connected with the first end of the third capacitor and the switching power supply respectively; the second end of the third capacitor is respectively and electrically connected with the first end of the first resistor and the live wire output end; the second end of the second capacitor is electrically connected with the zero line end of the alternating current power supply and the first end of the second inductor respectively, and the second end of the second inductor is electrically connected with the first end of the fourth capacitor; the second end of the fourth capacitor is electrically connected with the first end of the second resistor and the zero line output end respectively; the second end of the second resistor is electrically connected with the second end of the first resistor.
Optionally, the test circuit further comprises a toggle switch; the first end of the toggle switch is electrically connected with the first end of the frequency spectrograph; the second end of the toggle switch is electrically connected with the output end of the live wire or the output end of the zero wire;
when the second end of the toggle switch is toggled to be electrically connected with the output end of the live wire, the frequency spectrograph acquires a first common-mode current; when the second end of the toggle switch is toggled to be electrically connected with the output end of the zero line, the frequency spectrograph acquires a second common mode current; the frequency spectrograph is also used for displaying the interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current.
Optionally, the test circuit further includes a load and a rectifying circuit, and two ends of the load are connected to two ends of the switching power supply and used for simulating the load carrying capacity of the switching power supply;
one end of the rectifying circuit is connected with the second end of the impedance stabilizing circuit, and the other end of the rectifying circuit is connected with the switching power supply and used for converting alternating current into direct current.
Optionally, the test circuit further includes a ground metal plate, one end of the ground metal plate is connected to the second end of the impedance stabilizing circuit, and the other end of the ground metal plate is connected to the second end of the spectrometer.
Optionally, the frequency spectrograph is further configured to determine that the switching power supply is qualified when the maximum amplitude of the interference information frequency spectrum of the switching power supply is smaller than the reference frequency spectrum amplitude, and otherwise, determine that the switching power supply is unqualified.
Optionally, the frequency spectrograph is further configured to determine that the switching power supply is qualified when the maximum amplitude of the interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current is smaller than the reference frequency spectrum amplitude, and otherwise, determine that the switching power supply is unqualified.
The embodiment of the utility model provides a still provide a test method, be applied to above-mentioned arbitrary embodiment test circuit, include:
the impedance stabilizing circuit isolates the alternating current power supply from the switching power supply;
the frequency spectrograph acquires and displays the interference information frequency spectrum of the switching power supply.
Optionally, the testing method further includes: and when the maximum amplitude of the interference information frequency spectrum of the switching power supply is smaller than the reference frequency spectrum amplitude, the frequency spectrograph judges that the switching power supply is qualified, otherwise, the frequency spectrograph judges that the switching power supply is unqualified.
Optionally, the third end of the impedance stabilizing circuit includes a live wire output end and a zero line output end;
the impedance stabilizing circuit comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first inductor, a second inductor, a first resistor and a second resistor, wherein the first end of the first capacitor is electrically connected with a live wire end of an alternating current power supply and the first end of the first inductor respectively, and the second end of the first capacitor and the first end of the second capacitor are grounded; the second end of the first inductor is electrically connected with the first end of the third capacitor and the switching power supply respectively; the second end of the third capacitor is respectively and electrically connected with the first end of the first resistor and the live wire output end; the second end of the second capacitor is electrically connected with the zero line end of the alternating current power supply and the first end of the second inductor respectively, and the second end of the second inductor is electrically connected with the first end of the fourth capacitor; the second end of the fourth capacitor is electrically connected with the first end of the second resistor and the zero line output end respectively; the second end of the second resistor is electrically connected with the second end of the first resistor; the test circuit also comprises a toggle switch; the first end of the toggle switch is electrically connected with the first end of the frequency spectrograph; the second end of the toggle switch is electrically connected with the output end of the live wire or the output end of the zero wire; when the second end of the toggle switch is electrically connected with the output end of the live wire, the frequency spectrograph acquires a first common-mode current; when the second end of the toggle switch is electrically connected with the output end of the zero line, the frequency spectrograph acquires a second common-mode current;
the test method further comprises the following steps:
the frequency spectrograph displays an interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current; and when the maximum amplitude of the interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current is smaller than the reference frequency spectrum amplitude, judging that the switching power supply is qualified, otherwise, judging that the switching power supply is unqualified.
The embodiment of the utility model provides an in, be connected with the spectrometer through switching power supply's test circuit, realized the spectrometer to switching power supply's interference information frequency spectrum's analysis, reduced switching power supply's test cost, can be applied to the test of finished product total coverage.
Drawings
Fig. 1 is a schematic structural diagram of a test circuit according to a first embodiment of the present invention;
fig. 2 is a schematic structural diagram of a test circuit according to a second embodiment of the present invention;
fig. 3 is a schematic structural diagram of a test circuit in a third embodiment of the present invention;
fig. 4 is a schematic flow chart of a testing sender in the fourth embodiment of the present invention;
fig. 5 is a schematic flow chart of a testing method according to a fifth embodiment of the present invention;
fig. 6 is a schematic flow chart of a test circuit according to a sixth embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1 is a schematic structural diagram of a test circuit according to an embodiment of the present invention, as shown in fig. 1, the test circuit includes: an alternating current power supply 10, an impedance stabilizing circuit 20 and a spectrometer 30; the first end 21 of the impedance stabilizing circuit 20 is connected with the alternating current power supply 10, and the second end 22 of the impedance stabilizing circuit 20 is connected with the switching power supply 40 and used for isolating the alternating current power supply 10 from the switching power supply 40; the first terminal 31 of the spectrometer 30 is connected to the third terminal 23 of the impedance stabilizing circuit 20, the second terminal 32 of the spectrometer 30 is grounded, and the spectrometer 30 is used for displaying the interference information spectrum of the switching power supply 40.
In the technical solution of the above embodiment, on one hand, the first end 21 of the impedance stabilizing circuit 20 is connected to the ac power supply 10, the second end 22 of the impedance stabilizing circuit 20 is connected to the switching power supply 40, the ac power supply 10 provides the gate ac voltage and frequency to the switching power supply 40 through the impedance stabilizing circuit 20, the third end 23 of the impedance stabilizing circuit 20 is connected to the spectrometer 30, and the spectrum of the interference information of the switching power supply 40 is displayed on the spectrometer 30; on the other hand, the impedance stabilizing circuit 20 between the ac power supply 10 and the switching power supply isolates the ac power supply 10 from the switching power supply 40, ensuring that the spectrum analyzer 30 displays the interference information spectrum of the switching power supply 40.
According to the technical scheme, the testing circuit of the switching power supply is connected with the frequency spectrograph, so that the interference information frequency spectrum of the switching power supply is analyzed by the frequency spectrograph, the testing cost of the switching power supply is reduced, and the testing circuit can be applied to finished product full coverage testing.
Example two
Fig. 2 is a schematic structural diagram of the test circuit according to the second embodiment of the present invention, as shown in fig. 2, the third terminal 23 of the impedance stabilizing circuit 20 includes a live line output terminal OUTL and a zero line output terminal OUTN; the impedance stabilizing circuit 20 comprises a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1, a second inductor L2, a first resistor R1 and a second resistor R2, wherein a first end of the first capacitor C1 is electrically connected with a live wire end Line of the alternating current power supply 10 and a first end of the first inductor L1 respectively, and a second end of the first capacitor C1 and a first end of the second capacitor C2 are both grounded; the second end of the first inductor L1 is electrically connected to the first end of the third capacitor C3 and the switching power supply 40, respectively; a second end of the third capacitor C3 is electrically connected to the first end of the first resistor R1 and the live line output end OUTL, respectively; a second end of the second capacitor C2 is electrically connected to Neutral of the ac power supply 10 and a first end of the second inductor L2, respectively, and a second end of the second inductor L2 is electrically connected to a first end of the fourth capacitor C4; a second end of the fourth capacitor C4 is electrically connected with the first end of the second resistor R2 and the zero line output end OUTN, respectively; a second terminal of the second resistor R2 is electrically connected to a second terminal of the first resistor R1.
It should be noted that, a first end of a first capacitor C1 of the impedance stabilizing circuit 20 is connected to a live Line end Line of the ac power supply 10, a high-pass filter of the live Line is formed by a first inductor L1, a third capacitor C3 and a first resistor R1, the other end of the first inductor L1 is connected to the switching power supply 40, and a second end of the third capacitor C3 is electrically connected to a live Line output end OUTL, so that the spectrum coupling of the interference information at the live Line end of the switching power supply 40 to the spectrometer 30 is realized; the second end of the second capacitor C2 of the impedance stabilizing circuit 20 is connected to the NEUTRAL line end NEUTRAL of the ac power supply 10, a high-pass filter of the NEUTRAL line is formed by the elements of the second inductor L2, the fourth capacitor C4 and the second resistor R2, the other end of the second inductor L2 is connected to the switching power supply 40, and the second end of the fourth capacitor C4 is electrically connected to the NEUTRAL line output end OUTN, so that the spectrum coupling of the interference information at the NEUTRAL line end of the switching power supply 40 to the spectrometer 30 is realized.
On the other hand, the first end of the first inductor L1 of the impedance stabilizing circuit 20 is further connected to the first capacitor C1, and is grounded after passing through the first capacitor C1, so as to protect the live line in the impedance stabilizing circuit 20; the first end of the second inductor L2 of the impedance stabilizing circuit 20 is further connected to a second capacitor C2, and is grounded after passing through the second capacitor C2, so as to protect the neutral line in the impedance stabilizing circuit 20.
Optionally, the test circuit further comprises a toggle switch 50; the first end 51 of the toggle switch 50 is electrically connected with the first end 31 of the spectrometer 30; the second end 52 of the toggle switch 50 is electrically connected to the live line output terminal OUTL or the zero line output terminal OUTN;
when the second terminal 52 of the toggle switch 50 is electrically connected to the live line output terminal OUTL, the frequency spectrograph 30 obtains a first common mode current; when the second end 52 of the toggle switch 50 is electrically connected with the zero line output terminal OUTN, the frequency spectrograph 50 obtains a second common mode current; the spectrometer 30 is further configured to display an interference information spectrum corresponding to the larger of the first common-mode current and the second common-mode current.
It should be noted that, when the second terminal 52 of the toggle switch 50 is electrically connected to the live line output terminal OUTL, the ac power supply 10 supplies power to the switching power supply 40 through the first inductor L1, and goes to the live line output terminal OUTL through the first inductor L1 and the third capacitor C3, the live line output terminal OUTL is connected to the second terminal 52 of the toggle switch 50, and goes to the first terminal 31 of the spectrometer 30 through the first terminal 51 of the toggle switch 50, so that the spectrometer 30 obtains the first common mode current; when the second end 52 of the toggle switch 50 is electrically connected to the zero line output terminal OUTN, the ac power supply 10 supplies power to the switching power supply 40 through the second inductor L2, and reaches the zero line output terminal OUTN through the second inductor L2 and the fourth capacitor C4, the zero line output terminal OUTN is connected to the second end 52 of the toggle switch 50, and the spectrometer 30 obtains a second common mode current through the first end 51 of the toggle switch 50 to the first end 31 of the spectrometer 30.
On the other hand, the frequency spectrograph 30 displays the interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current according to the obtained first common-mode current of the live line output terminal OUTL and the second common-mode current of the zero line output terminal OUTN.
Optionally, the spectrometer 30 is further configured to determine that the switching power supply 40 is qualified when the maximum amplitude of the interference information spectrum of the switching power supply 40 is smaller than the reference spectrum amplitude, and otherwise, determine that the switching power supply 40 is unqualified.
It should be noted that, when the maximum amplitude of the interference information spectrum of the switching power supply 40 is smaller than the reference spectrum amplitude, the spectrometer 30 in the switching circuit determines that the switching power supply 40 is qualified, otherwise, determines that the switching power supply 40 is not qualified. When the switching power supply 40 is operated, the MOSFET and the transformer will generate a ringing of about 12MHz, which is a triple frequency of 36MHz, and the radiation margin will be smaller when the amplitude of the ringing is larger and larger when the amplitude of the ringing is smaller. Through the setting of the frequency spectrograph 30, when the maximum amplitude of the frequency point of 11.5M to 19MHz exceeds the reference spectrum amplitude, the frequency spectrograph 30 judges that the finished product of the switching power supply 40 is unqualified, and when the amplitude of the frequency point of 11.5M to 19MHz is lower than the reference spectrum amplitude, the frequency spectrograph 30 judges that the finished product of the switching power supply 40 is qualified.
Optionally, the frequency spectrograph 30 is further configured to determine that the switching power supply 40 is qualified when the maximum amplitude of the interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current is smaller than the reference frequency spectrum amplitude, and otherwise, determine that the switching power supply 40 is unqualified.
When the second end 52 of the toggle switch 50 is electrically connected to the live line output terminal OUTL, the spectrometer 30 obtains a first common mode current, and when the second end 52 of the toggle switch 50 is electrically connected to the zero line output terminal OUTN, the spectrometer 50 obtains a second common mode current, and by setting the spectrometer 30, the spectrometer 30 obtains an interference information spectrum corresponding to the larger of the first common mode current and the second common mode current, when the maximum amplitude of the frequency point of 11.5M to 19MHz exceeds the reference spectrum amplitude, the spectrometer 30 determines that the switch power supply 40 is unqualified, and when the amplitude of the frequency point of 11.5M to 19MHz is lower than the reference spectrum amplitude, the spectrometer 30 determines that the switch power supply 40 is qualified.
According to the technical scheme, when the third output end of the impedance stabilizing circuit is connected with the frequency spectrograph through the live wire output end, the frequency spectrograph acquires a first common-mode current, when the third output end of the impedance stabilizing circuit is connected with the frequency spectrograph through the zero wire output end, the frequency spectrograph acquires a second common-mode current, the frequency spectrograph acquires an interference information frequency spectrum corresponding to the larger one of the first common-mode current and the second common-mode current, and the switch power supply is judged to be qualified or unqualified according to the relation between the maximum amplitude of the interference information frequency spectrum corresponding to the larger one of the first common-mode current and the second common-mode current and the reference frequency spectrum amplitude.
EXAMPLE III
Fig. 3 is a schematic structural diagram of a test circuit provided by the third embodiment of the present invention, as shown in fig. 3, the test circuit further includes a load 70 and a rectifying circuit 60, and both ends of the load 70 are connected to both ends of the switching power supply 40, so as to simulate the loading capacity of the switching power supply 40.
It should be noted that the test circuit further includes a load 70, where the load is connected to two ends of the switching power supply 40 and is used for simulating the load capacity of the switching power supply 40, and the load 70 may be a resistor, and by connecting with the resistor, it is simulated whether the switching power supply 40 operates normally under the load condition.
The rectifying circuit 60 has one end connected to the second end 22 of the impedance stabilizing circuit 20 and the other end connected to the switching power supply 40, and is configured to convert the ac power into the dc power.
The rectifying circuit 60 has one end connected to the second end 22 of the impedance stabilizing circuit 20 and one end connected to the switching power supply 40, so as to realize the power supply 40 from the ac power supply 10 to the switching power supply, wherein the rectifying circuit 60 is configured to convert the ac power of the ac power supply 10 into dc power to supply the switching power supply 40.
The rectifier circuit 60 may be a rectifier diode or a rectifier circuit including other components, and may be configured to convert the ac power of the ac power supply 10 into the dc power required by the switching power supply 40.
Optionally, the test circuit further includes a grounding metal plate 80, one end of the grounding metal plate 80 is connected to the second terminal 22 of the impedance stabilizing circuit 20, and the other end is connected to the second terminal 32 of the spectrometer 30.
It should be noted that the test circuit includes a grounding metal plate 80, one end of the grounding metal plate 80 is connected to the second end 22 of the impedance stabilizing circuit 20, and the other end is connected to the second end 32 of the spectrometer 30. The other end of the first inductor L1 of the impedance stabilizing circuit 20 is connected to one end of the switching power supply 40 after passing through the rectifying circuit 60, the other end of the switching power supply 40 is grounded through the grounding metal plate 80, the first end of the first capacitor C1 of the impedance stabilizing circuit 20 is connected to the live Line end Line of the ac power supply 10, a high-pass filter of the live Line is formed by the first inductor L1, the third capacitor C3 and the first resistor R1, and the second end of the third capacitor C3 is electrically connected to the live Line output end OUTL, so that the interference information spectrum at the live Line end of the switching power supply 40 is coupled to the spectrometer 30; the other end of the second inductor L2 of the impedance stabilizing circuit 20 is connected to one end of the switching power supply 40 after passing through the rectifying circuit 60, the other end of the switching power supply 40 is grounded through the grounding metal plate 80, the second end of the second capacitor C2 of the impedance stabilizing circuit 20 is connected to the NEUTRAL line NEUTRAL of the ac power supply 10, a high-pass filter of the NEUTRAL line is formed by the second inductor L2, the fourth capacitor C4 and the second resistor R2, the other end of the second inductor L2 is connected to the switching power supply 40, the second end of the fourth capacitor C4 is electrically connected to the NEUTRAL output terminal OUTN, and the spectrum coupling of the interference information at the NEUTRAL end of the switching power supply 40 to the spectrometer 30 is achieved.
According to the technical scheme, the grounding metal plate is connected with the switching power supply, the grounding capacitance of the switching power supply is collected, the interference information frequency spectrum of the switching power supply is displayed in the frequency spectrograph through connection with the frequency spectrograph, the rectifying circuit converts the electricity of the alternating current power supply into direct current to supply power to the switching power supply, and the load is used for testing the loading capacity of the switching power supply.
Example four
The embodiment of the utility model provides a fourth provides a test method, including any one test circuit in the above-mentioned embodiment, fig. 4 is the utility model provides a fourth test method's that provides flow schematic diagram, as shown in fig. 4, test method includes:
s100, isolating an alternating current power supply from a switching power supply by an impedance stabilizing circuit;
the first end of the impedance stabilizing circuit is connected with the alternating current power supply, the second end of the impedance stabilizing circuit is connected with the switching power supply, the tested switching power supply is isolated from the alternating current power supply through the impedance stabilizing circuit, and the interference information frequency spectrum of the tested switching power supply displayed on the frequency spectrograph is ensured.
S200, the frequency spectrograph acquires and displays the interference information frequency spectrum of the switching power supply.
The frequency spectrograph can judge the radiation intensity of the switching power supply by acquiring and displaying the interference information frequency spectrum of the switching power supply to be detected and the interference information frequency spectrum of the switching power supply to be detected.
According to the technical scheme, the impedance stabilizing circuit ensures that the frequency spectrum of the interference information of the detected switching power supply is displayed by the frequency spectrograph, and the frequency spectrum of the interference information of the switching power supply is acquired and displayed by the frequency spectrograph, so that the frequency spectrum of the interference information of the switching power supply is analyzed by the frequency spectrograph.
EXAMPLE five
Fig. 5 is a schematic flow chart of a testing method provided by the fifth embodiment of the present invention, as shown in fig. 5, the testing method further includes:
s300, when the maximum amplitude of the interference information frequency spectrum of the switching power supply is smaller than the reference frequency spectrum amplitude, the switching power supply is judged to be qualified, and otherwise, the switching power supply is judged to be unqualified.
And when the maximum amplitude of the interference information frequency spectrum of the switching power supply is smaller than the reference frequency spectrum amplitude, the frequency spectrograph in the switching circuit judges that the switching power supply is qualified, otherwise, the frequency spectrograph judges that the switching power supply is unqualified. When the switching power supply 40 is operated, the MOSFET and the transformer will generate a ringing of about 12MHz, which is a triple frequency of 36MHz, and the radiation margin will be smaller when the amplitude of the ringing is larger and larger when the amplitude of the ringing is smaller. Through the setting of the frequency spectrograph, when the maximum amplitude of the 11.5M-19 MHz frequency point exceeds the reference frequency spectrum amplitude, the frequency spectrograph judges that the switch power supply finished product is unqualified, and when the amplitude of the 11.5M-19 MHz frequency point is lower than the reference frequency spectrum amplitude, the frequency spectrograph judges that the switch power supply finished product is qualified.
According to the technical scheme, the switch power supply finished product is qualified or unqualified by setting the frequency spectrograph.
EXAMPLE six
Fig. 6 is a schematic flow chart of a testing method provided by the sixth embodiment of the present invention, as shown in fig. 6, the testing method further includes:
s400, displaying an interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current by a frequency spectrograph; and when the maximum amplitude of the interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current is smaller than the reference frequency spectrum amplitude, judging that the switching power supply is qualified, otherwise, judging that the switching power supply is unqualified.
It should be noted that the third end of the impedance stabilizing circuit comprises a live wire output end and a zero wire output end;
the impedance stabilizing circuit comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first inductor, a second inductor, a first resistor and a second resistor, wherein the first end of the first capacitor is electrically connected with a live wire end of an alternating current power supply and the first end of the first inductor respectively, and the second end of the first capacitor and the first end of the second capacitor are grounded; the second end of the first inductor is electrically connected with the first end of the third capacitor and the switching power supply respectively; the second end of the third capacitor is respectively and electrically connected with the first end of the first resistor and the live wire output end; the second end of the second capacitor is electrically connected with the zero line end of the alternating current power supply and the first end of the second inductor respectively, and the second end of the second inductor is electrically connected with the first end of the fourth capacitor; the second end of the fourth capacitor is electrically connected with the first end of the second resistor and the zero line output end respectively; the second end of the second resistor is electrically connected with the second end of the first resistor; the test circuit also comprises a toggle switch; the first end of the toggle switch is electrically connected with the first end of the frequency spectrograph; the second end of the toggle switch is electrically connected with the output end of the live wire or the output end of the zero wire; when the second end of the toggle switch is electrically connected with the output end of the live wire, the frequency spectrograph acquires a first common-mode current; and when the second end of the toggle switch is electrically connected with the output end of the zero line, the frequency spectrograph acquires a second common mode current.
When the second terminal 52 of the toggle switch 50 is electrically connected to the live line output terminal OUTL, the ac power supply 10 supplies power to the switching power supply 40 through the first inductor L1, and reaches the live line output terminal OUTL through the first inductor L1 and the third capacitor C3, the live line output terminal OUTL is connected to the second terminal 52 of the toggle switch 50, and the spectrometer 30 obtains a first common mode current through the first terminal 51 of the toggle switch 50 to the first terminal 31 of the spectrometer 30; when the second end 52 of the toggle switch 50 is electrically connected to the zero line output terminal OUTN, the ac power supply 10 supplies power to the switching power supply 40 through the second inductor L2, and reaches the zero line output terminal OUTN through the second inductor L2 and the fourth capacitor C4, the zero line output terminal OUTN is connected to the second end 52 of the toggle switch 50, and the spectrometer 30 obtains a second common mode current through the first end 51 of the toggle switch 50 to the first end 31 of the spectrometer 30. By setting the frequency spectrograph 30, the frequency spectrograph 30 obtains the interference information frequency spectrum corresponding to the larger of the first common mode current and the second common mode current, when the maximum amplitude of the frequency point of 11.5M to 19MHz exceeds the reference frequency spectrum amplitude, the frequency spectrograph 30 judges that the finished product of the switching power supply 40 is unqualified, and when the amplitude of the frequency point of 11.5M to 19MHz is lower than the reference frequency spectrum amplitude, the frequency spectrograph 30 judges that the finished product of the switching power supply 40 is qualified.
According to the technical scheme, the frequency spectrum of the interference information corresponding to the larger one of the live wire end and the zero wire end of the switching power supply is acquired through setting the frequency spectrograph, and qualified or unqualified judgment of the finished switching power supply is achieved.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (7)
1. A test circuit, comprising:
an alternating current power supply, an impedance stabilizing circuit and a frequency spectrometer;
the first end of the impedance stabilizing circuit is connected with the alternating current power supply, and the second end of the impedance stabilizing circuit is connected with the switching power supply and is used for isolating the alternating current power supply from the switching power supply;
the first end of the frequency spectrograph is connected with the third end of the impedance stabilizing circuit, the second end of the frequency spectrograph is grounded, and the frequency spectrograph is used for displaying the interference information frequency spectrum of the switching power supply.
2. The test circuit of claim 1, wherein the third terminal of the impedance stabilization circuit comprises a live output and a neutral output;
the impedance stabilizing circuit comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first inductor, a second inductor, a first resistor and a second resistor, wherein the first end of the first capacitor is electrically connected with a live wire end of the alternating current power supply and the first end of the first inductor respectively, and the second end of the first capacitor and the first end of the second capacitor are grounded; the second end of the first inductor is electrically connected with the first end of the third capacitor and the switching power supply respectively; the second end of the third capacitor is electrically connected with the first end of the first resistor and the live wire output end respectively; a second end of the second capacitor is electrically connected with a zero line end of the alternating current power supply and a first end of the second inductor respectively, and a second end of the second inductor is electrically connected with a first end of the fourth capacitor; a second end of the fourth capacitor is electrically connected with a first end of the second resistor and the zero line output end respectively; the second end of the second resistor is electrically connected with the second end of the first resistor.
3. The test circuit of claim 2, further comprising a toggle switch; the first end of the toggle switch is electrically connected with the first end of the frequency spectrograph; the second end of the toggle switch is electrically connected with the live wire output end or the zero line output end;
when the second end of the toggle switch is electrically connected with the live wire output end, the frequency spectrograph acquires a first common-mode current; when the second end of the toggle switch is electrically connected with the output end of the zero line, the frequency spectrograph acquires a second common-mode current; the frequency spectrograph is also used for displaying an interference information frequency spectrum corresponding to the larger of the first common-mode current and the second common-mode current.
4. The test circuit according to claim 1, further comprising a load and a rectifying circuit, wherein two ends of the load are connected to two ends of the switching power supply for simulating the load capacity of the switching power supply;
and one end of the rectifying circuit is connected with the second end of the impedance stabilizing circuit, and the other end of the rectifying circuit is connected with the switching power supply and is used for converting alternating current into direct current.
5. The test circuit of claim 1, further comprising a grounded metal plate having one end connected to the second end of the impedance stabilization circuit and another end connected to the second end of the spectrometer.
6. The test circuit of claim 1, wherein the spectrometer is further configured to determine that the switching power supply is acceptable when a maximum magnitude of an interference information spectrum of the switching power supply is less than a reference spectrum magnitude, and otherwise determine that the switching power supply is unacceptable.
7. The test circuit of claim 3, wherein the spectrometer is further configured to determine that the switching power supply is qualified when the maximum amplitude of the interference information spectrum corresponding to the larger of the first common mode current and the second common mode current is smaller than a reference spectrum amplitude, and otherwise determine that the switching power supply is unqualified.
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| CN201922025077.5U CN211426739U (en) | 2019-11-21 | 2019-11-21 | Test circuit |
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