Capacitive load insulation resistance test circuit

Abstract

The utility model discloses a capacitive load insulation resistance test circuit, which relates to the technical field of low-pass filter circuits and comprises a voltage division protection circuit, a sampling and grading circuit and a filter circuit. The input end of the voltage division protection circuit is connected with insulation voltage, the output end of the voltage division protection circuit is connected with the input end of the sampling and grading circuit, and the output end of the sampling and grading circuit is connected with the input end of the filter circuit. According to the utility model, voltage required to be applied to a load is set, current applied to the load is collected, Ohm's law calculation is carried out according to the collected current, and different grading circuits are switched, so that corresponding resistance gears are output, and then a voltage follower is used for adjusting circuits before and after self impedance matching so as to enter a single-chip microcomputer; for the capacitive load, a filtering function is added during insulation resistance test, so that the resistance fluctuation range is small, the stability of test data is improved, and the influence of the capacitive load on the test is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of low-pass filter circuits, in particular to a capacitive load insulation resistance test circuit. Background Art

[0002] With the advent of the power market, new energy vehicles are gradually being recognized by the public. The market has increasingly higher requirements for battery performance indicators. Capacitive cell testing has poor stability and high costs, and needs to meet the requirements of multiple types of field applications. Currently, the higher the automation program, the higher the time requirement. Therefore, continuous unstable cell measurement data on the assembly line will lead to abnormal situations and affect work progress.

[0003] At present, the insulation resistance test on the market is calculated through the traditional bridge insulation detection circuit. The insulation voltage is a unipolar voltage, and the direction of the withstand voltage test is also unidirectional, and the test current is a process that gradually decreases as the capacitor is filled. Capacitive load generally refers to a load with capacitance parameters, that is, a load that meets the current leading voltage characteristic. When the capacitive load is charged and discharged, the voltage cannot change suddenly. Therefore, when testing the insulation characteristics of the capacitive load, its resistance value will fluctuate.

[0004] The purpose of insulation testing is to calculate the insulation resistance. When the insulation resistance is lower than a certain threshold, it is very likely to cause a short circuit or leakage in the battery, threatening personnel safety. The existing technology does not provide stable data when testing capacitive loads, and multiple retests are required, which is time-consuming.

[0005] Currently, no effective solution has been proposed for the problems in the related technologies. Utility Model Content

[0006] In view of the problems in the related art, the utility model proposes a capacitive load insulation resistance test circuit to overcome the above technical problems existing in the existing related art.

[0007] To this end, the specific technical solutions adopted by the utility model are as follows:

[0008] A capacitive load insulation resistance test circuit comprises: a voltage-dividing protection circuit, a sampling-grading circuit and a filtering circuit; the input end of the voltage-dividing protection circuit is connected to the insulation voltage, the output end of the voltage-dividing protection circuit is connected to the input end of the sampling-grading circuit, and the output end of the sampling-grading circuit is connected to the input end of the filtering circuit.

[0009] Furthermore, the voltage-dividing protection circuit includes: a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a capacitor C3, a diode Z1 and a voltage-stabilizing tube TVS1;

[0010] Among them, one end of resistor R1 is connected to an insulating voltage, the other end of resistor R1 is connected to one end of resistor R2, and the other end of resistor R2 is respectively connected to one end of capacitor C1, one end of capacitor C2, one end of capacitor C3, the cathode of diode Z1 and one end of voltage regulator diode TVS1. And the other end of resistor R2 serves as the output end of the voltage division protection circuit. The other ends of capacitor C1, capacitor C2, capacitor C3, the anode of diode Z1 and the other end of voltage regulator diode TVS1 are kept connected and grounded.

[0011] Furthermore, resistor R1 and resistor R2 are current-limiting resistors.

[0012] Furthermore, the sampling grading circuit includes: analog switch chip IC10, capacitor C4, capacitor C5, capacitor C6, capacitor C7, capacitor C8, capacitor C9, resistor R3, resistor R4, resistor R5 and resistor R6;

[0013] Among them, the 13th pin of analog switch chip IC10 is connected to the output end of the voltage division protection circuit. The 16th pin of analog switch chip IC10 is connected to one end of capacitor C4. The other end of capacitor C4 is respectively connected to the 8th pin of analog switch chip IC10 and one end of capacitor C5. The other end of capacitor C5 is connected to the 7th pin of analog switch chip IC10. The 1st pin of analog switch chip IC10 is respectively connected to the 12th pin of analog switch chip IC10, one end of capacitor C9 and one end of resistor R6. The 5th pin of analog switch chip IC10 is respectively connected to the 14th pin of analog switch chip IC10, one end of capacitor C8 and one end of resistor R5. The 2nd pin of analog switch chip IC10 is respectively connected to the 15th pin of analog switch chip IC10, one end of resistor R4 and one end of capacitor C7. The 4th pin of analog switch chip IC10 is respectively connected to the 11th pin of analog switch chip IC10, one end of resistor R3 and one end of capacitor C6. The other ends of resistor R6, capacitor C9, resistor R5, capacitor C8, resistor R4, capacitor C7, resistor R3 and capacitor C6 are kept connected and grounded.

[0014] Furthermore, the sampling grading circuit includes four grades, namely grade 0, grade 1, grade 2 and grade 3. The sampling resistor corresponding to grade 0 is 0.3k, the sampling resistor corresponding to grade 1 is 3k, the sampling resistor corresponding to grade 2 is 30k, and the sampling resistor corresponding to grade 3 is 300k.

[0015] Furthermore, the filtering circuit includes operational amplifier OP1, electrolytic capacitor E1, electrolytic capacitor E2, capacitor C10, capacitor C11, capacitor C12, resistor R7, resistor R8, diode D1 and diode D2;

[0016] Among them, the third pin of the operational amplifier OP1 is connected to the third pin of the analog switch chip IC10. The second pin of the operational amplifier OP1 is connected to the sixth pin of the operational amplifier OP1 and one end of the resistor R7. The seventh pin of the operational amplifier OP1 is respectively connected to one end of the electrolytic capacitor E1 and one end of the capacitor C10. The other end of the electrolytic capacitor E1 is connected to the other end of the capacitor C10. The fourth pin of the operational amplifier OP1 is respectively connected to one end of the electrolytic capacitor E2 and one end of the capacitor C11. The other end of the electrolytic capacitor E21b is connected to the other end of the capacitor C11. The other end of the resistor R7 is respectively connected to one end of the capacitor C12 and one end of the resistor R8. The other end of the capacitor C12 is connected to the anode of the diode D1 and grounded. The other end of the resistor R8 is respectively connected to the cathode of the diode D1 and the cathode of the diode D2.

[0017] The beneficial effects of the present utility model are as follows: By setting the voltage to be applied to the load, collecting the current applied to the load, performing Ohm's law calculation based on the collected current, switching to different divided circuit, and thus outputting the corresponding resistance range, and then adjusting the impedance of the front and rear circuits through a voltage follower to enter the single-chip microcomputer; when the present utility model performs insulation resistance test on capacitive loads, a filtering function is added to make the resistance fluctuation range smaller, thereby improving the stability of test data and reducing the influence of the capacitive load itself on the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 is the circuit schematic diagram of a capacitive load insulation resistance test circuit according to an embodiment of the present utility model;

[0020] Figure 2 is the circuit schematic diagram of a voltage dividing protection circuit in a capacitive load insulation resistance test circuit according to an embodiment of the present utility model;

[0021] Figure 3 is the circuit schematic diagram of a sampling and dividing circuit in a capacitive load insulation resistance test circuit according to an embodiment of the present utility model;

[0022] Figure 4 is the circuit schematic diagram of a filtering circuit in a capacitive load insulation resistance test circuit according to an embodiment of the present utility model;

[0023] Figure 5It is a test flow chart of a capacitive load insulation resistance test circuit according to an embodiment of the present invention.

[0024] In the figure:

[0025] 1. Voltage dividing protection circuit; 2. Sampling and grading circuit; 3. Filtering circuit. Specific implementation manners

[0026] According to an embodiment of the present invention, a capacitive load insulation resistance test circuit is provided.

[0027] Now, the present invention will be further described in conjunction with the accompanying drawings and specific implementation manners. As Figures 1-4 shown, the capacitive load insulation resistance test circuit according to an embodiment of the present invention includes: a voltage dividing protection circuit 1, a sampling and grading circuit 2, and a filtering circuit 3; the input end of the voltage dividing protection circuit 1 is connected to the insulation voltage, the output end of the voltage dividing protection circuit 1 is connected to the input end of the sampling and grading circuit 2, and the output end of the sampling and grading circuit 2 is connected to the input end of the filtering circuit 3.

[0028] In one embodiment, the voltage dividing protection circuit 1 includes: a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a capacitor C3, a diode Z1, and a voltage stabilizing diode TVS1;

[0029] Wherein, one end of the resistor R1 is connected to the insulation voltage, the other end of the resistor R1 is connected to one end of the resistor R2, the other end of the resistor R2 is respectively connected to one end of the capacitor C1, one end of the capacitor C2, one end of the capacitor C3, the cathode of the diode Z1, and one end of the voltage stabilizing diode TVS1, and the other end of the resistor R2 is used as the output end of the voltage dividing protection circuit 1, and the other ends of the capacitor C1, the capacitor C2, the capacitor C3, the anode of the diode Z1, and the other end of the voltage stabilizing diode TVS1 are connected and grounded.

[0030] In one embodiment, the resistor R1 and the resistor R2 are current limiting resistors.

[0031] In one embodiment, the sampling and grading circuit 2 includes: an analog switch chip IC10, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a resistor R3, a resistor R4, a resistor R5, and a resistor R6;

[0032] Among them, the 13th pin of the analog switch chip IC10 is connected to the output end of the voltage division protection circuit 1. The 16th pin of the analog switch chip IC10 is connected to one end of the capacitor C4. The other end of the capacitor C4 is respectively connected to the 8th pin of the analog switch chip IC10 and one end of the capacitor C5. The other end of the capacitor C5 is connected to the 7th pin of the analog switch chip IC10. The 1st pin of the analog switch chip IC10 is respectively connected to the 12th pin of the analog switch chip IC10, one end of the capacitor C9 and one end of the resistor R6. The 5th pin of the analog switch chip IC10 is respectively connected to the 14th pin of the analog switch chip IC10, one end of the capacitor C8 and one end of the resistor R5. The 2nd pin of the analog switch chip IC10 is respectively connected to the 15th pin of the analog switch chip IC10, one end of the resistor R4 and one end of the capacitor C7. The 4th pin of the analog switch chip IC10 is respectively connected to the 11th pin of the analog switch chip IC10, one end of the resistor R3 and one end of the capacitor C6. The other end of the resistor R6, the other end of the capacitor C9, the other end of the resistor R5, the other end of the capacitor C8, the other end of the resistor R4, the other end of the capacitor C7, the other end of the resistor R3 and the other end of the capacitor C6 are kept connected and grounded.

[0033] In one embodiment, the sampling grading circuit 2 includes four grades, namely grade 0, grade 1, grade 2 and grade 3. The sampling resistor corresponding to grade 0 is 0.3k, the sampling resistor corresponding to grade 1 is 3k, the sampling resistor corresponding to grade 2 is 30k, and the sampling resistor corresponding to grade 3 is 300k.

[0034] In one embodiment, the filtering circuit 3 includes an operational amplifier OP1, an electrolytic capacitor E1, an electrolytic capacitor E2, a capacitor C10, a capacitor C11, a capacitor C12, a resistor R7, a resistor R8, a diode D1 and a diode D2;

[0035] Among them, the 3rd pin of the operational amplifier OP1 is connected to the 3rd pin of the analog switch chip IC10. The 2nd pin of the operational amplifier OP1 is connected to the 6th pin of the operational amplifier OP1 and one end of the resistor R7. The 7th pin of the operational amplifier OP1 is respectively connected to one end of the electrolytic capacitor E1 and one end of the capacitor C10. The other end of the electrolytic capacitor E1 is connected to the other end of the capacitor C10. The 4th pin of the operational amplifier OP1 is respectively connected to one end of the electrolytic capacitor E2 and one end of the capacitor C11. The other end of the electrolytic capacitor E21b is connected to the other end of the capacitor C11. The other end of the resistor R7 is respectively connected to one end of the capacitor C12 and one end of the resistor R8. The other end of the capacitor C12 is connected to the anode of the diode D1 and grounded. The other end of the resistor R8 is respectively connected to the cathode of the diode D1 and the cathode of the diode D2.

[0036] As Figure 5 shown is the test process of the present invention in actual application.

[0037] The first part is to calculate the collected current value, and its purpose is to obtain the corresponding resistance value through the collected current value. The specific test process is as follows:

[0038] As Figure 2 shown, after the insulation voltage passes through two current-limiting resistors, namely resistor R1 and resistor R2; the resistors mainly play a role in current limiting; then it enters the protection circuit, and capacitor C1 and capacitor C2 are connected in parallel. The capacitors play a role of buffering and stabilizing in the circuit, which can reduce the change range of the voltage and current of the subsequent circuit and prevent the subsequent circuit from being damaged due to sudden state changes. Then it passes through diode Z1 and voltage regulator diode TVS1, mainly to prevent overvoltage and overcurrent conditions in the circuit from damaging the subsequent circuit.

[0039] As Figure 3 shown, the acquisition and grading circuit; after the voltage passes through the voltage-dividing protection circuit and current limiting, it enters the input end of the analog switch chip IC10 (CD4052). CD4052 is a 2-way four-to-one analog switch circuit with a common enable input control bit. Each multiplexer has four independent inputs (Y0 to Y3), (X0 to X3) and a common output terminal (XY); which specific channel is output is determined by the address code AB.

[0040] According to the sampling resistance of 0.3k for the 0th gear, 3k for the 1st gear - 3k; 30k for the 2nd gear - 30k; 300k for the 3rd gear - 300k; according to the collected current and the set voltage, the gear can be obtained according to the current; the calculated resistance is output, and the corresponding resistance is output; when testing a capacitive load, the data will be stable within one gear; so the data tends to be stable.

[0041] Finally, there is a filtering circuit. As Figure 4 shown, after the output resistance, it enters N9 OP01. This operational amplifier is a voltage follower, mainly for impedance matching; resistor R7 and capacitor C12 form an RC filtering circuit to process the output data accordingly.

[0042] Ohm's law calculation is performed by collecting the current and the applied voltage in real time; thus, the corresponding resistance value is obtained; the collected current is the current collected in real time, and the data will be processed accordingly; thus, it is converted into a resistance value; the low-pass filtering function will compare the instantaneous current to judge the stability of the data at this time.

[0043] In summary, by means of the above technical solutions of the present utility model, after setting the voltage to be applied to the load, the current applied to the load is collected. According to the collected current, Ohm's law calculation is performed, and then the circuit is switched to different gear circuits, so as to output the corresponding resistance gear. Then, the voltage follower adjusts its own impedance to match the front and rear circuits and then enters the single-chip microcomputer. When the present utility model is used to test the insulation resistance value of capacitive loads, a filtering function is added to make the fluctuation range of the resistance value smaller, thereby improving the stability of the test data and reducing the influence of the capacitive load itself on the test.

[0044] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A capacitive load insulation resistance test circuit, characterized in that: include: A voltage division protection circuit (1), a sampling and grading circuit (2) and a filtering circuit (3); The input end of the voltage-dividing protection circuit (1) is connected to an insulating voltage, the output end of the voltage-dividing protection circuit (1) is connected to the input end of the sampling and grading circuit (2), and the output end of the sampling and grading circuit (2) is connected to the input end of the filtering circuit (3).

2. A capacitive load insulation resistance test circuit according to claim 1, characterized in that: The voltage-dividing protection circuit (1) comprises: a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a capacitor C3, a diode Z1 and a voltage-stabilizing tube TVS1; One end of the resistor R1 is connected to an insulation voltage, the other end of the resistor R1 is connected to one end of the resistor R2, the other end of the resistor R2 is respectively connected to one end of the capacitor C1, one end of the capacitor C2, one end of the capacitor C3, the cathode of the diode Z1 and one end of the voltage regulator TVS1, and the other end of the resistor R2 serves as the output end of the voltage divider protection circuit (1), the other end of the capacitor C1, the other end of the capacitor C2, the other end of the capacitor C3, the anode of the diode Z1 and the other end of the voltage regulator TVS1 remain connected and grounded.

3. A capacitive load insulation resistance test circuit according to claim 2, characterized in that: The resistor R1 and the resistor R2 are current limiting resistors.

4. A capacitive load insulation resistance test circuit according to claim 2, characterized in that: The sampling and grading circuit (2) comprises: an analog switch chip IC10, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a resistor R3, a resistor R4, a resistor R5 and a resistor R6; The 13th pin of the analog switch chip IC10 is connected to the output end of the voltage divider protection circuit (1), the 16th pin of the analog switch chip IC10 is connected to one end of the capacitor C4, the other end of the capacitor C4 is respectively connected to the 8th pin of the analog switch chip IC10 and one end of the capacitor C5, the other end of the capacitor C5 is connected to the 7th pin of the analog switch chip IC10, the 1st pin of the analog switch chip IC10 is respectively connected to the 12th pin of the analog switch chip IC10, one end of the capacitor C9 and one end of the resistor R6, the 5th ... The 14th pin, one end of the capacitor C8 and one end of the resistor R5 are connected, the 2nd pin of the analog switch chip IC10 is respectively connected to the 15th pin of the analog switch chip IC10, one end of the resistor R4 and one end of the capacitor C7, the 4th pin of the analog switch chip IC10 is respectively connected to the 11th pin of the analog switch chip IC10, one end of the resistor R3 and one end of the capacitor C6, the other end of the resistor R6, the other end of the capacitor C9, the other end of the resistor R5, the other end of the capacitor C8, the other end of the resistor R4, the other end of the capacitor C7, the other end of the resistor R3 and the other end of the capacitor C6 remain connected and grounded.

5. A capacitive load insulation resistance test circuit according to claim 4, characterized in that: The sampling step circuit (2) comprises four gears, namely, gear 0, gear 1, gear 2 and gear 3. The sampling resistor corresponding to gear 0 is 0.3k, the sampling resistor corresponding to gear 1 is 3k, the sampling resistor corresponding to gear 2 is 30k, and the sampling resistor corresponding to gear 3 is 300k.

6. A capacitive load insulation resistance test circuit according to claim 4, characterized in that: The filter circuit (3) comprises an operational amplifier OP1, an electrolytic capacitor E1, an electrolytic capacitor E2, a capacitor C10, a capacitor C11, a capacitor C12, a resistor R7, a resistor R8, a diode D1 and a diode D2; Among them, the third pin of the operational amplifier OP1 is connected to the third pin of the analog switch chip IC10, the second pin of the operational amplifier OP1 is connected to the sixth pin of the operational amplifier OP1 and one end of the resistor R7, the seventh pin of the operational amplifier OP1 is respectively connected to one end of the electrolytic capacitor E1 and one end of the capacitor C10, the other end of the electrolytic capacitor E1 is connected to the other end of the capacitor C10, the fourth pin of the operational amplifier OP1 is respectively connected to one end of the electrolytic capacitor E2 and one end of the capacitor C11, the other end of the electrolytic capacitor E21b is connected to the other end of the capacitor C11, the other end of the resistor R7 is respectively connected to one end of the capacitor C12 and one end of the resistor R8, the other end of the capacitor C12 is connected to the anode of the diode D1 and is grounded, and the other end of the resistor R8 is respectively connected to the cathode of the diode D1 and the cathode of the diode D2.

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