Range adaptive inductance measurement circuit, method and multimeter

Abstract

The application relates to a range-adaptive inductance measurement circuit, method and multimeter, the circuit comprising: a signal generation circuit connected at two ends of an inductance to be measured and a range switching circuit, and a processor connected with the signal generation circuit and the range switching circuit; wherein the signal generation circuit is used for outputting an alternating current signal or a direct current signal; the range switching circuit is used for range switching; and the processor is used for obtaining an inductance value of the inductance to be measured according to an alternating current input resistance corresponding to the inductance to be measured when the signal generation circuit outputs the alternating current signal and a direct current input resistance corresponding to the inductance to be measured when the signal generation circuit outputs the direct current signal, and controlling the range switching circuit to perform range switching according to the inductance value. The circuit can realize range-adaptive inductance measurement, solves the problem of low inductance detection efficiency caused by manual range adjustment in the prior art, and has the advantages of simple structure, improved production test efficiency and reduced industrial cost.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a range-adaptive inductance measurement circuit, method, and multimeter. Background Technology

[0002] In the field of electronic circuits, inductance measurement is a frequent problem. However, commercially available multimeters do not have inductance measurement capabilities. Therefore, when measuring inductance, it is usually necessary to use other measured values ​​for additional calculations. To solve this problem, engineers designed multimeters with inductance measurement functions. While existing multimeters with inductance measurement functions can measure inductance, their electronic circuitry is complex, and they have many external components, making the production and testing process cumbersome, complicated, and costly. Furthermore, when measuring inductance, it is necessary to manually adjust the multimeter by rotating a dial to switch between different ranges. Summary of the Invention

[0003] Therefore, it is necessary to provide a range-adaptive inductance measurement circuit, method, and multimeter that has a simple structure and circuitry and can achieve adaptive selection of inductance range and perform inductance measurement, in order to address the above-mentioned technical problems.

[0004] In a first aspect, this application provides a range-adaptive inductance measurement circuit, the circuit including a signal generation circuit and a range switching circuit connected to both ends of the inductor under test, and a processor connected to the signal generation circuit and the range switching circuit; wherein...

[0005] The signal generating circuit is used to output AC or DC signals;

[0006] The range switching circuit is used for range switching;

[0007] The processor is configured to obtain the inductance value of the inductor under test based on the AC input resistance of the inductor under test when the signal generating circuit outputs the AC signal and the DC input resistance of the inductor under test when the signal generating circuit outputs the DC signal, and to control the range switching circuit to perform range switching based on the inductance value.

[0008] In one embodiment, the range switching circuit includes an amplifier circuit and a range switching sub-circuit. The range switching sub-circuit is connected between the inverting input terminal and the output terminal of the amplifier circuit, serving as a negative feedback resistor connected to the amplifier circuit.

[0009] When the signal generation circuit outputs the AC signal, the processor obtains the AC input resistance based on the first proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and the first voltage across the inductor under test; when the signal generation circuit outputs the DC signal, the processor obtains the DC input resistance based on the second proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and the second voltage across the inductor under test.

[0010] In one embodiment, the range switching subcircuit includes a first resistor, at least two second resistors, and at least two first switching switches respectively connected to the second resistors;

[0011] The processor controls the switching of the first switching switch according to the inductance value to perform range switching.

[0012] In one embodiment, the amplification circuit includes an amplifier, a second switch connected between the inverting input of the amplifier and the input of the range switching sub-circuit, a third switch connected between the inverting input and the output of the amplifier, a fourth switch connected between the non-inverting input of the amplifier and a constant voltage source, and a fifth switch connected between the non-inverting input of the amplifier and the common ground terminal of the analog signal.

[0013] When the signal generating circuit outputs the AC signal, the processor controls the second and fifth switching switches to close, and the third and fourth switching switches to open.

[0014] When the signal generating circuit outputs the DC signal, the processor controls the third and fourth switching switches to close, and the second and fifth switching switches to open.

[0015] In one embodiment, the signal generating circuit includes an AC generating circuit and a DC generating circuit. The AC generating circuit includes an AC signal generating device and an AC switch connected in sequence. The DC generating circuit includes an analog signal ground terminal and a DC switch.

[0016] The processor controls the AC switch to close and the DC switch to open, connecting the AC signal generated by the AC signal generator to the inductor under test, or...

[0017] The processor controls the DC switch to close and the AC switch to open, connecting the DC signal generated by the common ground terminal of the analog signal to the inductor under test.

[0018] In one embodiment, the signal generating circuit further includes a fuse connected between the inductor under test and the AC switch of the signal generating circuit;

[0019] When the signal generation circuit outputs the AC signal, the processor obtains the AC input resistance based on the first ratio between the voltage value and the resistance value of the negative feedback resistor in the range switching circuit and the third voltage across the inductor under test and the fuse.

[0020] When the signal generation circuit outputs the DC signal, the processor obtains the DC input resistance based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the fourth voltage across the inductor under test and the fuse.

[0021] Secondly, this application also provides a range-adaptive inductance measurement method for the range-adaptive inductance measurement circuit of the first aspect described above, the method comprising:

[0022] Acquire the AC input resistance of the inductor under test when the signal generating circuit outputs the AC signal and the DC input resistance of the inductor under test when the signal generating circuit outputs the DC signal;

[0023] Based on the AC input resistance and the DC input resistance, the inductance value of the inductor under test is obtained;

[0024] Based on the inductance value, the range switching circuit is controlled to perform range switching.

[0025] In one embodiment, the range switching circuit includes an amplifier circuit and a range switching sub-circuit. The range switching sub-circuit is connected between the inverting input terminal and the output terminal of the amplifier circuit, serving as a negative feedback resistor connected to the amplifier circuit. The step of acquiring the AC input resistance corresponding to the inductor under test when the signal generation circuit outputs the AC signal and the DC input resistance corresponding to the inductor under test when the signal generation circuit outputs the DC signal includes:

[0026] When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the first voltage across the inductor under test.

[0027] When the signal generation circuit outputs the DC signal, the DC input resistance is obtained based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the second voltage across the inductor under test.

[0028] In one embodiment, the signal generating circuit further includes a fuse connected between the inductor under test and the AC switch of the signal generating circuit. The step of acquiring the AC input resistance of the inductor under test when the signal generating circuit outputs the AC signal and the DC input resistance of the inductor under test when the signal generating circuit outputs the DC signal includes:

[0029] When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor in the range switching circuit and the third voltage across the inductor under test and the fuse.

[0030] When the signal generation circuit outputs the DC signal, the DC input resistance is obtained based on the second proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and the fourth voltage across the inductor under test and the fuse.

[0031] Thirdly, a multimeter is provided, which includes an adaptive inductance measurement circuit as mentioned in the first aspect above.

[0032] The beneficial effects of the above-described range-adaptive inductance measurement circuit, method, and multimeter are as follows: An AC or DC signal is output by the signal generation circuit; the processor obtains the inductance value of the inductor under test based on the AC input resistance corresponding to the inductor under test when the signal generation circuit outputs the AC signal and the DC input resistance corresponding to the inductor under test when the signal generation circuit outputs the DC signal; and controls the range switching circuit to perform range switching based on the inductance value. This achieves range-adaptive inductance measurement, solves the problem of low efficiency in manual range adjustment inductance detection in existing technologies, and features a simple circuit structure, improving production testing efficiency and reducing industrial costs. Attached Figure Description

[0033] Figure 1 This is a circuit module connection diagram of a range-adaptive inductance measurement circuit in one embodiment.

[0034] Figure 2 This is a circuit module connection diagram of the range switching circuit in one embodiment;

[0035] Figure 3 This is a circuit module connection diagram in a signal generation circuit of one embodiment;

[0036] Figure 4 This is a circuit diagram of a range-adaptive inductance measurement circuit in an example embodiment. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0039] This embodiment provides a range-adaptive inductance measurement circuit, such as... Figure 1 As shown, the system includes a signal generation circuit 101, an inductor under test 102, a range switching circuit 103, and a processor 104 connected to the signal generation circuit 101, the inductor under test 102, and the range switching circuit 103. The inductor under test 102 is connected between the signal generation circuit 101 and the range switching circuit 103. The signal generation circuit 101 is used to output an AC signal or a DC signal; the range switching circuit 103 is used for range switching; the processor 104 is used to obtain the inductance value of the inductor under test 102 based on the AC input resistance of the inductor under test 102 when the signal generation circuit 101 outputs the AC signal and the DC input resistance of the inductor under test 102 when the signal generation circuit 101 outputs the DC signal, and to control the range switching circuit 103 to perform range switching based on the inductance value.

[0040] In the aforementioned range-adaptive inductance measurement circuit, an AC or DC signal is output through a signal generation circuit. The processor obtains the inductance value of the inductor under test based on the AC input resistance of the inductor under test when the signal generation circuit outputs the AC signal and the DC input resistance of the inductor under test when the signal generation circuit outputs the DC signal. The processor then controls the range switching circuit to switch the range based on the inductance value, thus realizing range-adaptive inductance measurement. This solves the problem of manually adjusting the inductance range in the prior art. Furthermore, the circuit structure is simple, improving the efficiency of production testing and reducing industrial costs.

[0041] In one embodiment, such as Figure 2 As shown, the range switching circuit 103 includes an amplifier circuit 21 and a range switching sub-circuit 22. The range switching sub-circuit 22 is connected between the inverting input terminal and the output terminal of the amplifier circuit 21, and serves as the negative feedback resistor connected to the amplifier circuit 21.

[0042] Specifically, when the signal generating circuit 101 outputs the AC signal, the processor 104 obtains the AC input resistance based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the first voltage across the inductor 102 under test; when the signal generating circuit 101 outputs the DC signal, the processor 104 obtains the DC input resistance based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the second voltage across the inductor 102 under test.

[0043] In one embodiment, the amplifier circuit 21 includes an amplifier, a second switch connected between the inverting input terminal of the amplifier and the input terminal of the range switching sub-circuit, a third switch connected between the inverting input terminal and the output terminal of the amplifier, a fourth switch connected between the non-inverting input terminal of the amplifier and a constant voltage source, and a fifth switch connected between the non-inverting input terminal of the amplifier and the common ground terminal of the analog signal.

[0044] The amplifier includes an inverting input buffer amplifier.

[0045] Specifically, when the signal generating circuit 101 outputs the AC signal, the processor 104 controls the second and fifth switching switches to close and the third and fourth switching switches to open; when the signal generating circuit 101 outputs the DC signal, the processor 104 controls the third and fourth switching switches to close and the second and fifth switching switches to open.

[0046] In the above embodiments, by controlling the opening and closing of the switches on the amplifier circuit through the processor, a complete AC signal circuit and a DC signal circuit are realized between the input and output terminals of the amplifier.

[0047] In one embodiment, the range switching sub-circuit 22 includes a first resistor, at least two second resistors, and at least two first switching switches respectively connected to the second resistors. The processor 104 controls the switching of the first switching switches according to the inductance value to perform range switching.

[0048] The switchable inductance ranges include 6–600 mH, 6–60 H, and 60–600 H.

[0049] In this embodiment, the negative feedback resistor is divided, and the processor controls the opening and closing of different switches to control the resistance value of the negative feedback resistor connected to the circuit, thereby realizing the automatic switching of the measurement range.

[0050] In one embodiment, such as Figure 3 As shown, the signal generation circuit 101 includes an AC generation circuit 31 and a DC generation circuit 32. The AC generation circuit 31 includes an AC signal generating device and an AC switch connected in sequence. The DC generation circuit 32 includes an analog signal ground terminal and a DC switch.

[0051] The AC signal output by the AC signal generator includes a sine wave signal.

[0052] Specifically, the processor 104 controls the AC switch to close and the DC switch to open, so as to connect the AC signal generated by the AC signal generator to the inductor under test 102; or the processor 104 controls the DC switch to close and the AC switch to open, so as to connect the DC signal generated by the analog signal ground terminal to the inductor under test 102.

[0053] In this embodiment, the inductance value of the resistor under test is measured by using the AC and DC signals generated in the processor control loop, thereby improving the inductance measurement efficiency.

[0054] In one embodiment, the signal generating circuit further includes a fuse connected between the inductor under test 102 and the AC switch of the signal generating circuit 101.

[0055] The fuse is used to prevent high voltage input to the inductance measurement circuit from damaging the circuit components.

[0056] Specifically, when the signal generation circuit 101 outputs the AC signal, the processor 104 obtains the AC input resistance based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor in the range switching circuit 103 and the third voltage between the inductor under test 102 and the fuse.

[0057] When the signal generation circuit 101 outputs the DC signal, the processor 104 obtains the DC input resistance based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the fourth voltage across the inductor 102 under test and the fuse.

[0058] In one example embodiment, such as Figure 4 As shown, a range-adaptive inductance measurement circuit is provided, including a signal generation circuit 101, an inductance under test Lx, a range switching circuit 103, and a processor 104 connected to the signal generation circuit 101 and the range switching circuit 103, wherein:

[0059] The signal generation circuit 101 includes an AC switch S1 connected to the sine wave generator 11, a DC switch S2 connected to the common ground terminal COM of the analog signal, and a fuse F1 with one end connected to the AC switch S1 and the other end connected to the inductor Lx to be tested.

[0060] The range switching circuit 103 includes an inverting amplifier OP, a negative feedback resistor Rf (including a fourth resistor R4, a third resistor R3, a second resistor R2, and a first resistor R1 connected in sequence) connected between the inverting input terminal and the output terminal of the inverting amplifier OP, a first switching switch S41 for the negative feedback resistor Rf, a second switching switch S42 connected between the inverting input terminal of the inverting amplifier OP and the input terminal of the range switching sub-circuit, a third switching switch S43 connected between the inverting input terminal and the output terminal of the inverting amplifier, a fourth switching switch S44 connected between the non-inverting input terminal of the inverting amplifier OP and the constant voltage source VDR8, and a fifth switching switch S45 connected between the non-inverting input terminal of the inverting amplifier OP and the analog signal ground terminal COM.

[0061] The first switching switch S41 of the negative feedback resistor Rf includes a first switch S11, a second switch S12, and a third switch S13. The first switch S11 is connected in sequence to the second resistor R2 and the first resistor R1; the second switch S12 is connected in sequence to the third resistor R3, the second resistor R2, and the first resistor R1; the third switch S13 is connected in sequence to the fourth resistor R4, the third resistor R3, the second resistor R2, and the first resistor R1.

[0062] The AC input resistance R corresponding to the resistor under test is measured based on processor 104. ZAt that time, the switch in the first switching switch S41 is opened and closed. Based on the first proportional relationship α = Rf × V' between the voltage and resistance values ​​of the negative feedback resistor Rf, where V' represents the voltage across the negative feedback resistor Rf connected to the circuit, and the voltage across the resistor to be measured and the fuse is V″, the AC input resistance R is obtained. Z The calculation formula is Automatic range switching includes the following three situations:

[0063] Case 1: With AC switch S1, first switch S11, second changeover switch S42, and fifth changeover switch S45 closed, and the remaining switches open, the negative feedback resistors connected to the circuit include the second resistor R2 and the first resistor R1. The measurable range of the inductance to be measured is 6–600 mH.

[0064] The AC input resistance is obtained by collecting the voltage V1 across the second resistor R2 and the first resistor R1, and the voltage V2 across the inductor Lx and the fuse F1.

[0065] Case 2: Close AC switch S1, second switch S12, second changeover switch S42, and fifth changeover switch S45, and open the remaining switches. In this case, the negative feedback resistors connected to the circuit include the third resistor R3, the second resistor R2, and the first resistor R1. The measurable range of the inductance to be measured is 6–60H.

[0066] The AC input resistance is obtained by collecting the voltage V11 across the third resistor R3, the second resistor R2, and the first resistor R1, and the voltage V22 across the inductor Lx and the fuse F1.

[0067] Case 3: Close AC switch S1, third switch S13, second changeover switch S42, and fifth changeover switch S45, and open the remaining switches. In this case, the negative feedback resistors connected to the circuit include the fourth resistor R4, the third resistor R3, the second resistor R2, and the first resistor R1. The measurable range of the inductance to be measured is 60–600 ohms.

[0068] The AC input resistance is obtained by collecting the voltage V111 across the fourth resistor R4, the third resistor R3, the second resistor R2, and the first resistor R1, and the voltage V222 across the inductor Lx and the fuse F1.

[0069]

[0070] The DC input resistance R corresponding to the resistor under test is measured based on processor 104. LWhen the AC switch S1, the first switch S11, the second switching switch S42, and the fifth switching switch S45 are closed, the remaining switches are opened. At this time, the negative feedback resistor Rf connected to the circuit includes the second resistor R2 and the first resistor R1.

[0071] The second proportional relationship between the voltage and resistance of the negative feedback resistor Rf is β=(R1+R2)×V′, where V′ represents the voltage across the negative feedback resistor Rf connected in the circuit, the voltage across the resistor under test and the fuse is V″, and the DC input resistance is... The DC input resistance is obtained by collecting the voltage V1 across the second resistor R2 and the first resistor R1, and the voltage V2 across the inductor Lx and the fuse F1.

[0072] Processor 104 is based on the obtained AC input resistance R Z and DC input resistance R L The inductive reactance of the inductor Lx under test is obtained. Thus, the inductance value of the inductor Lx to be measured is obtained:

[0073]

[0074] Where f is the frequency of the sine wave signal.

[0075] Finally, based on the obtained inductance value of the inductor Lx to be measured, the processor 104 determines whether the AC input resistance R is being measured. Z If the range corresponding to the closed switch in the first switching switch S41 includes the measured inductance value, then the inductance value is output; otherwise, the opening and closing of the switch in the first switching switch S41 is readjusted, and another range is selected to calculate the inductance value.

[0076] Based on the same inventive concept, this application also provides a range-adaptive inductance measurement method for implementing the range-adaptive inductance measurement circuit described above. The solution provided by this method is similar to the implementation described in the circuit above. Therefore, the specific limitations of one or more range-adaptive inductance measurement method embodiments provided below can be found in the limitations of the range-adaptive inductance measurement circuit described above, and will not be repeated here.

[0077] In one embodiment, a range-adaptive inductance measurement method is provided for use in the range-adaptive inductance measurement circuits of the above embodiments, the method comprising the following steps:

[0078] Step 1: Obtain the AC input resistance of the inductor under test when the signal generation circuit outputs the AC signal and the DC input resistance of the inductor under test when the signal generation circuit outputs the DC signal.

[0079] Step 2: Based on the AC input resistance and the DC input resistance, obtain the inductance value of the inductor under test.

[0080] Step 3: Based on the inductance value, control the range switching circuit to perform range switching.

[0081] In one embodiment, the range switching circuit includes an amplifier circuit and a range switching sub-circuit. The range switching sub-circuit is connected between the inverting input terminal and the output terminal of the amplifier circuit, serving as a negative feedback resistor connected to the amplifier circuit. The step of obtaining the AC input resistance corresponding to the inductor under test when the signal generation circuit outputs the AC signal and the DC input resistance corresponding to the inductor under test when the signal generation circuit outputs the DC signal further includes the following steps:

[0082] Step 21: When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the first voltage across the inductor under test.

[0083] Step 22: When the signal generation circuit outputs the DC signal, the DC input resistance is obtained based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the second voltage across the inductor under test.

[0084] In one embodiment, the signal generating circuit further includes a fuse connected between the inductor under test and the AC switch of the signal generating circuit. The step of acquiring the AC input resistance of the inductor under test when the signal generating circuit outputs the AC signal and the DC input resistance of the inductor under test when the signal generating circuit outputs the DC signal further includes the following steps:

[0085] Step 31: When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first ratio between the voltage value and the resistance value of the negative feedback resistor in the range switching circuit and the third voltage across the inductor to be measured and the fuse.

[0086] Step 32: When the signal generation circuit outputs the DC signal, the DC input resistance is obtained based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the fourth voltage across the inductor under test and the fuse.

[0087] In one embodiment, a multimeter is provided that includes the range-adaptive inductance measurement circuit described in the above embodiments.

[0088] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A range-adaptive inductance measurement circuit, characterized in that, The circuit includes a signal generation circuit and a range switching circuit connected to both ends of the inductor under test, and also includes a processor connected to the signal generation circuit and the range switching circuit; wherein... The signal generating circuit is used to output AC or DC signals; The range switching circuit is used for range switching. The range switching circuit includes an amplifier circuit and a range switching sub-circuit. The range switching sub-circuit is connected between the inverting input terminal and the output terminal of the amplifier circuit, and serves as the negative feedback resistor connected to the amplifier circuit. The processor is configured to: when the signal generating circuit outputs the AC signal, obtain the AC input resistance based on a first proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and a first voltage across the inductor under test; when the signal generating circuit outputs the DC signal, obtain the DC input resistance based on a second proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and a second voltage across the inductor under test; obtain the inductance value of the inductor under test based on the AC input resistance and the DC input resistance, and control the range switching circuit to perform range switching based on the inductance value.

2. The range-adaptive inductance measurement circuit according to claim 1, characterized in that, The range switching sub-circuit includes a first resistor, at least two second resistors, and at least two first switching switches respectively connected to the second resistors; The processor controls the switching of the first switching switch according to the inductance value to perform range switching.

3. The range-adaptive inductance measurement circuit according to claim 1, characterized in that, The amplifier circuit includes an amplifier, a second switching switch connected between the inverting input terminal of the amplifier and the input terminal of the range switching sub-circuit, a third switching switch connected between the inverting input terminal and the output terminal of the amplifier, a fourth switching switch connected between the non-inverting input terminal of the amplifier and the constant voltage source, and a fifth switching switch connected between the non-inverting input terminal of the amplifier and the common ground terminal of the analog signal. When the signal generating circuit outputs the AC signal, the processor controls the second and fifth switching switches to close, and the third and fourth switching switches to open. When the signal generating circuit outputs the DC signal, the processor controls the third and fourth switching switches to close, and the second and fifth switching switches to open.

4. The range-adaptive inductance measurement circuit according to claim 1, characterized in that, The signal generation circuit includes an AC generation circuit and a DC generation circuit. The AC generation circuit includes an AC signal generating device and an AC switch connected in sequence. The DC generation circuit includes an analog signal ground terminal and a DC switch. The processor controls the AC switch to close and the DC switch to open, connecting the AC signal generated by the AC signal generator to the inductor under test, or... The processor controls the DC switch to close and the AC switch to open, connecting the DC signal generated by the common ground terminal of the analog signal to the inductor under test.

5. The range-adaptive inductance measurement circuit according to claim 1, characterized in that, The signal generating circuit also includes a fuse, which is connected between the inductor under test and the AC switch of the signal generating circuit; When the signal generation circuit outputs the AC signal, the processor obtains the AC input resistance based on the first ratio between the voltage value and the resistance value of the negative feedback resistor in the range switching circuit and the third voltage across the inductor under test and the fuse. When the signal generation circuit outputs the DC signal, the processor obtains the DC input resistance based on the second proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and the fourth voltage across the inductor under test and the fuse.

6. A range-adaptive inductance measurement method, used in the range-adaptive inductance measurement circuit as described in any one of claims 1 to 5, characterized in that, The range switching circuit includes an amplifier circuit and a range switching sub-circuit. The range switching sub-circuit is connected between the inverting input terminal and the output terminal of the amplifier circuit, serving as the negative feedback resistor connected to the amplifier circuit. The method includes: When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the first voltage across the inductor under test. When the signal generation circuit outputs the DC signal, the DC input resistance is obtained based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the second voltage across the inductor under test. Based on the AC input resistance and the DC input resistance, the inductance value of the inductor under test is obtained; Based on the inductance value, the range switching circuit is controlled to perform range switching.

7. The method according to claim 6, characterized in that, The signal generation circuit also includes a fuse connected between the inductor under test and the AC switch of the signal generation circuit. When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the first voltage across the inductor under test. And when the signal generation circuit outputs the DC signal, based on the second proportional relationship between the voltage value and the resistance value of the negative feedback resistor and the second voltage across the inductor under test, the DC input resistance is obtained as follows: When the signal generation circuit outputs the AC signal, the AC input resistance is obtained based on the first proportional relationship between the voltage value and the resistance value of the negative feedback resistor in the range switching circuit and the third voltage across the inductor under test and the fuse. When the signal generation circuit outputs the DC signal, the DC input resistance is obtained based on the second proportional relationship between the voltage and resistance values ​​of the negative feedback resistor and the fourth voltage across the inductor under test and the fuse.

8. A multimeter, characterized in that, The multimeter includes a range-adaptive inductance measurement circuit as described in any one of claims 1 to 5.

Images