CN211148785U - Insulation resistance detection circuit - Google Patents
Insulation resistance detection circuit Download PDFInfo
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- CN211148785U CN211148785U CN201920736556.5U CN201920736556U CN211148785U CN 211148785 U CN211148785 U CN 211148785U CN 201920736556 U CN201920736556 U CN 201920736556U CN 211148785 U CN211148785 U CN 211148785U
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Abstract
The application discloses an insulation resistance detection circuit, which comprises a detection power supply, a first detected resistor, a second detected resistor, a sampling resistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first switch, a second switch, a third switch and a fourth switch, wherein the first resistor, the second resistor, the third resistor, the fourth resistor, the first switch, the second switch, the third switch and the fourth switch are connected in series; the first switch, the second switch, the third switch and the fourth switch are mutually locked and controlled, the first switch, the first resistor, the second resistor and the second switch are sequentially connected in series to form a first series circuit, the third switch, the third resistor, the fourth resistor and the fourth switch are sequentially connected in series to form a second series circuit, the first series circuit is connected with the second series circuit in parallel and then connected with the sampling resistor in series to form a series-parallel hybrid circuit, two ends of the series-parallel hybrid circuit are connected with two ends of the first tested resistor and two ends of the second tested resistor in parallel, and the joint of the first tested resistor and the second tested resistor, the joint of the first resistor and the second resistor and the joint of the third resistor and the fourth resistor are mutually connected through leads. The measuring precision of the test circuit is higher.
Description
Technical Field
The application relates to an insulation resistance detection circuit.
Background
A conventional insulation resistance detection circuit is shown in fig. 1, wherein the resistance of the sampling resistor R is very small, and for the sake of illustrating the principle, it is considered that R2+ sampling R is approximately equal to R2.
By the following equation
Can find RHAnd RL，
To illustrate the disadvantages of the circuit of fig. 1, we analyze as follows: when the optical coupler of the circuit in the attached figure 1 is disconnected, the circuit is equivalent to the attached figure 2. When the circuit of fig. 1 is optically coupled, the circuit is equivalent to fig. 3 and fig. 4, in fig. 4, R3 'is the resistance value of R1 and R3 after being connected in parallel, and R4' is similar to the resistance value of R2 and R4 after being connected in parallel.
The parallel resistance calculation principle tells us that in order to calculate the accuracy of RH and R L, RH and R L must be in the same order of magnitude as R1, R2, R3 'and R4', and preferably do not exceed 5 times, so that after being connected in parallel with R6329, R2, R3 'and R4', respectively, RH and R L can have a significant effect on the resistance after being connected in parallel, and the accurate resistance can be calculated with a significant effect.
Disclosure of Invention
The purpose of the application is: in order to solve the problems, the insulation resistance detection circuit with high test precision is provided.
The technical scheme of the application is as follows:
an insulation resistance detection circuit comprises a detection power supply, a first detected resistor and a second detected resistor which are connected in series,
the circuit is characterized by further comprising a sampling resistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first switch, a second switch, a third switch and a fourth switch;
the first switch, the second switch, the third switch and the fourth switch are controlled in an interlocking mode, and when the first switch and the second switch are simultaneously conducted, the third switch and the fourth switch are simultaneously disconnected; when the first switch and the second switch are turned off at the same time, the third switch and the fourth switch are turned on at the same time;
the resistance values of the sampling resistor, the first resistor, the second resistor, the third resistor and the fourth resistor are known, and the resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are not less than 100 times of the resistance value of the sampling resistor;
first switch, first resistance, second resistance and second switch establish ties in proper order and form first series circuit, third switch, third resistance, fourth resistance and fourth switch establish ties in proper order and form second series circuit, first series circuit with after the second series circuit is parallelly connected with sampling resistor establishes ties and forms a cluster and hybrid circuit, cluster and hybrid circuit's both ends with the both ends of first resistance and the second resistance that is surveyed are parallelly connected, just the junction of first resistance and the second resistance that is surveyed, the junction of first resistance and second resistance the junction of third resistance and fourth resistance passes through wire interconnect.
On the basis of the technical scheme, the application also comprises the following preferable scheme:
the first switch, the second switch, the third switch and the fourth switch are controlled by the interlocking of the optical coupling circuit.
The resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are not less than 1000 times of the resistance value of the sampling resistor.
The resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are not less than 10K omega.
The resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are not all the same.
In the four resistors of the first resistor, the second resistor, the third resistor and the fourth resistor, the ratio of the resistance values of any two resistors is not less than 0.1 and not more than 10.
In the four resistors of the first resistor, the second resistor, the third resistor and the fourth resistor, the ratio of the resistance values of any two resistors is not less than 0.2 and not more than 5.
And the ratio of the resistance value of any one of the first resistor, the second resistor, the third resistor and the fourth resistor to the resistance value of the first tested resistor is not less than 0.2 and not more than 5.
And the ratio of the resistance value of any one of the first resistor, the second resistor, the third resistor and the fourth resistor to the resistance value of the second tested resistor is not less than 0.2 and not more than 5.
The application has the advantages that: the detection circuit can ensure that R1, R2, R3 and R4 are in the same order of magnitude, and the types of R1, R2, R3 and R4 are selected without mutual influence, mutual interference and association, so that U2 and U4 can have enough difference. The calculation accuracy is very ideal, and the influence of sampling errors is effectively overcome.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the description of the embodiments are briefly introduced below, the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a conventional insulation resistance detection circuit;
FIG. 2 is an equivalent circuit of the insulation resistance detection circuit of FIG. 1 when the circuit opto-coupler is disconnected;
FIG. 3 is one of the equivalent circuit forms of the insulation resistance detection circuit of FIG. 1 when the circuit optical coupler is closed;
FIG. 4 is a second equivalent circuit of the insulation resistance detection circuit of FIG. 1 when the circuit optocoupler is closed;
FIG. 5 is a schematic diagram of an insulation resistance detection circuit according to an embodiment of the present application;
fig. 6 is an equivalent circuit of the insulation resistance detection circuit in the embodiment of the present application when the optical coupler is disconnected;
FIG. 7 is an equivalent circuit of the insulation resistance detection circuit in the embodiment of the present application, which is closed by the optical coupler;
Detailed Description
The present application will be described in further detail below with reference to the accompanying drawings by way of specific embodiments. The present application may be embodied in many different forms and is not limited to the embodiments described in the present embodiment. The following detailed description is provided to facilitate a more thorough understanding of the present disclosure, and the words used to indicate orientation, top, bottom, left, right, etc. are used solely to describe the illustrated structure in connection with the accompanying figures.
One skilled in the relevant art will recognize, however, that one or more of the specific details can be omitted, or other methods, components, or materials can be used. In some instances, some embodiments are not described or not described in detail.
Furthermore, the technical features, aspects or characteristics described herein may be combined in any suitable manner in one or more embodiments. It will be readily appreciated by those of skill in the art that the order of the steps or operations of the methods associated with the embodiments provided herein may be varied. Thus, any sequence in the figures and examples is for illustrative purposes only and does not imply a requirement in a certain order unless explicitly stated to require a certain order.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
Fig. 5 shows a specific embodiment of the insulation resistance detection circuit of the present application, which mainly includes a detection voltage 1, a first measured resistor R L and a second measured resistor RH connected in series with each other, a sampling resistor R, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4, wherein:
the first tested resistor R L and the second tested resistor RH are connected in series, and the resistance values of the first tested resistor R L and the second tested resistor RH are unknown and are measured values of the detection circuit.
The first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 are controlled by means of interlocking of an optical coupler circuit, and when the first switch S1 and the second switch S2 are simultaneously turned on, the third switch S3 and the fourth switch S4 are simultaneously turned off; when the first switch S1 and the second switch S2 are simultaneously turned off, the third switch S3 and the fourth switch S4 are simultaneously turned on.
The resistances of the sampling resistor R, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are known, and the resistances of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are much larger than the resistance of the sampling resistor R, and generally, the resistance of each of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 is not smaller than 100 times, and more preferably 1000 times, the resistance of the sampling resistor R.
Referring to fig. 5 again, the first switch S1, the first resistor R1, the second resistor R2 and the second switch S2 are sequentially connected in series to form a first series circuit, the third switch S3, the third resistor R3, the fourth resistor R4 and the fourth switch S4 are sequentially connected in series to form a second series circuit, the first series circuit and the second series circuit are connected in parallel and then connected in series with the sampling resistor R to form a series-parallel hybrid circuit, two ends of the series-parallel hybrid circuit are connected in parallel with two ends of the first resistor R L and the second resistor RH to be measured, and a connection point of the first resistor R L and the second resistor RH to be measured, a connection point of the first resistor R1 and the second resistor R2, and a connection point of the third resistor R3 and the fourth resistor R4 are connected to each other through wires.
When the optical coupler is turned off, the first switch S1 and the second switch S2 are turned on simultaneously, the third switch S3 and the fourth switch S4 are turned off simultaneously, and the detection circuit is equivalent to fig. 6. When the optical coupler is closed, the first switch S1 and the second switch S2 are simultaneously turned off, and the third switch S3 and the fourth switch S4 are simultaneously turned on, and the detection circuit is equivalent to fig. 7.
The formula derivation method is the same as before, and is not described herein again, and can be obtained as follows:
the circuit of the embodiment has the greatest advantage that R1, R2, R3 and R4 are of the same order of magnitude, and the types of R1, R2, R3 and R4 do not influence each other, do not interfere with each other, and are not associated, so that U2 and U4 can have a sufficient difference, and after repeated simulation, for example, when R1 is 20K Ω, R2 is 100K Ω, R3 is 100K Ω, and R4 is 20K Ω, the calculation accuracy is ideal for RH and R L in the range of 5K Ω to 500K Ω, and the influence of sampling errors is effectively overcome because the difference between U2 and U4 is large enough.
During actual measurement and calculation, the resistance value of the sampling resistor R needs to be considered, the voltage at two ends of the sampling resistor R is measured, and the resistance values of the first tested resistor R L and the second tested resistor RH are accurately calculated according to the resistance value of the sampling resistor R and the voltage at two ends of the sampling resistor R.
In general, it is preferable that the resistances of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are not less than 10K Ω. And the resistances of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are not all the same, i.e. the resistances of the four resistors are not all the same (at most three are the same).
And the selection of the R4 resistance value preferably considers the input voltage limit of the singlechip, generally 0-5V, and the R4 is too large and exceeds 5V, and too small affects the sampling precision.
It is preferable to ensure that the resistances of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are in the same order of magnitude: in the four resistors, the ratio of the resistances of any two resistors is not less than 0.1 and not more than 10, and more preferably, the ratio of the resistances of any two resistors is not less than 0.2 and not more than 5.
In addition, the resistance values of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are preferably kept in the same order of magnitude as the resistance values of the first resistor R L and the second resistor RH to be measured, that is, the ratio of the resistance value of any one of the four resistors (R1, R2, R3 and R4) to the resistance value of the first resistor R L to be measured is generally not less than 0.2 and not more than 5, and the ratio of the resistance value of any one of the four resistors (R1, R2, R3 and R4) to the resistance value of the second resistor RH to be measured is not less than 0.2 and not more than 5.
The above embodiments are only for illustrating the technical concepts and features of the present application, and the purpose of the embodiments is to enable people to understand the content of the present application and implement the present application, and not to limit the protection scope of the present application. All equivalent changes and modifications made according to the spirit of the main technical scheme of the application are covered in the protection scope of the application.
Claims (9)
1. An insulation resistance detection circuit comprises a detection power supply, a first detected resistance (R L) and a second detected Resistance (RH) which are connected in series,
the circuit is characterized by further comprising a sampling resistor (R), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a first switch (S1), a second switch (S2), a third switch (S3) and a fourth switch (S4);
the first switch (S1), the second switch (S2), the third switch (S3) and the fourth switch (S4) are controlled in an interlocking manner, and when the first switch (S1) and the second switch (S2) are simultaneously turned on, the third switch (S3) and the fourth switch (S4) are simultaneously turned off; when the first switch (S1) and the second switch (S2) are simultaneously turned off, the third switch (S3) and the fourth switch (S4) are simultaneously turned on;
the resistance values of the sampling resistor (R), the first resistor (R1), the second resistor (R2), the third resistor (R3) and the fourth resistor (R4) are known, and the resistance values of the first resistor (R1), the second resistor (R2), the third resistor (R3) and the fourth resistor (R4) are all not less than 100 times of the resistance value of the sampling resistor (R);
the first switch (S1), the first resistor (R1), the second resistor (R2) and the second switch (S2) are sequentially connected in series to form a first series circuit, the third switch (S3), the third resistor (R3), the fourth resistor (R4) and the fourth switch (S4) are sequentially connected in series to form a second series circuit, the first series circuit and the second series circuit are connected in parallel and then connected in series with the sampling resistor (R) to form a series-parallel hybrid circuit, two ends of the series-parallel hybrid circuit are connected in parallel with two ends of the first resistor (R L) and the second Resistor (RH) to be measured, and the connection of the first resistor (R L) and the second resistor (R2) to be measured, the connection of the first resistor (R1) and the second resistor (R2) to be measured, and the connection of the third resistor (R3) and the fourth resistor (R4) are connected with each other through conducting wires.
2. The insulation resistance detection circuit according to claim 1, wherein the first switch (S1), the second switch (S2), the third switch (S3), and the fourth switch (S4) are interlocked controlled by an optical coupler circuit.
3. The insulation resistance detection circuit according to claim 1, wherein the resistances of the first resistor (R1), the second resistor (R2), the third resistor (R3), and the fourth resistor (R4) are not less than 1000 times the resistance of the sampling resistor (R).
4. The insulation resistance detection circuit according to claim 1, wherein the resistances of the first resistor (R1), the second resistor (R2), the third resistor (R3) and the fourth resistor (R4) are not less than 10K Ω.
5. The insulation resistance detection circuit according to claim 1, wherein the resistances of the first resistor (R1), the second resistor (R2), the third resistor (R3), and the fourth resistor (R4) are not all the same.
6. The insulation resistance detection circuit according to claim 1, wherein a ratio of resistance values of any two of the four resistors of the first resistor (R1), the second resistor (R2), the third resistor (R3) and the fourth resistor (R4) is not less than 0.1 and not more than 10.
7. The insulation resistance detection circuit according to claim 6, wherein a ratio of resistance values of any two of the four resistors of the first resistor (R1), the second resistor (R2), the third resistor (R3) and the fourth resistor (R4) is not less than 0.2 and not more than 5.
8. The insulation resistance detection circuit according to claim 1, wherein a ratio of a resistance value of any one of the first resistor (R1), the second resistor (R2), the third resistor (R3) and the fourth resistor (R4) to the first measured resistor (R L) is not less than 0.2 and not more than 5.
9. The insulation resistance detection circuit according to claim 1, wherein a ratio of a resistance value of any one of the first resistor (R1), the second resistor (R2), the third resistor (R3), and the fourth resistor (R4) to the second measured Resistor (RH) is not less than 0.2 and not more than 5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920736556.5U CN211148785U (en) | 2019-05-22 | 2019-05-22 | Insulation resistance detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920736556.5U CN211148785U (en) | 2019-05-22 | 2019-05-22 | Insulation resistance detection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN211148785U true CN211148785U (en) | 2020-07-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920736556.5U Expired - Fee Related CN211148785U (en) | 2019-05-22 | 2019-05-22 | Insulation resistance detection circuit |
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| CN (1) | CN211148785U (en) |
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- 2019-05-22 CN CN201920736556.5U patent/CN211148785U/en not_active Expired - Fee Related
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