Insulation detection circuit device and method

Abstract

The invention discloses an insulation detection circuit device and method. The insulation detection circuit device comprises a first solid-state relay U1 control circuit, a detection circuit and a high-voltage reed switch relay control circuit. The first solid-state relay control circuit comprises a first solid-state relay U1, and when the MCU module outputs a high level, the first solid-state relay U1 is switched on; the detection circuit comprises a first operational amplifier circuit, a second operational amplifier circuit and an isolation amplifier circuit, and the detection circuit is used for monitoring voltages at two ends of the resistor Rnss to be detected in real time; the high-voltage reed switch relay control circuit comprises a high-voltage reed switch relay, and the output end of the high-voltage reed switch relay can switch voltage; a traditional insulation detection circuit often needs two AD pins to detect the voltage of an upper bridge arm and a lower bridge arm which are switched back and forth, and the circuit does not need to be additionally connected with a known resistor in parallel, occupies few AD pins of an MCU module, and facilitates passing of a high-voltage insulation and withstand voltage test.

Description

Technical Field

[0001] The invention belongs to the technical field of insulation detection, and in particular relates to an insulation detection circuit device and method. Background Art

[0002] In BMS (Battery Management System), the insulation detection function requires special consideration and design because it involves personal safety issues. Because the voltage in the energy storage system can be as high as hundreds of volts or even more than one thousand volts, if it is touched by people, it will endanger people's life safety, which is absolutely to be avoided. Therefore, the insulation of the energy storage system is very important and needs to be protected by special measures.

[0003] Chinese invention patent CN113295927B discloses an insulation detection system and an insulation detection method, wherein the insulation detection system uses a first voltage measuring unit and a second voltage measuring unit to obtain a first sampling voltage, a second sampling voltage, a third sampling voltage and a fourth sampling voltage, and combines the magnitude relationship between the first sampling voltage and the third sampling voltage. According to Millman's theorem, the insulation resistance of the high-voltage system can be calculated using a combination of the first sampling voltage and the third sampling voltage or a combination of the second sampling voltage and the fourth sampling voltage, thereby realizing insulation detection of a high-voltage system including one or more high-voltage devices, and the calculation process uses a combination of the first sampling voltage and the third sampling voltage or a combination of the second sampling voltage and the fourth sampling voltage. This scheme avoids the adverse effect of the excessive resistance of the first resistor on the insulation detection accuracy and improves the insulation detection accuracy. However, in BMS, the applicability and insulation detection accuracy of this scheme are difficult to judge.

[0004] Therefore, the present invention provides an insulation detection circuit device and method for solving the problems raised by the above background technology. Summary of the invention

[0005] In response to the problems raised by the above background technology, the purpose of the present invention is to provide an insulation detection circuit device and method, which, compared with the traditional insulation detection circuit, occupies fewer AD pins of the MCU, has a simple circuit structure, can flexibly change the resistance value, and improves the insulation detection efficiency.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0007] An insulation detection circuit device and method, including an MCU module, and also including a first solid-state relay U1 control circuit, a detection circuit and a high-voltage reed switch relay control circuit;

[0008] The first solid-state relay control circuit includes a first solid-state relay U1, and when the MCU module outputs a high level, the first solid-state relay U1 is turned on;

[0009] The detection circuit includes a first operational amplifier circuit, a second operational amplifier circuit and an isolation amplifier circuit, and the detection circuit is used to monitor the voltage across the resistor Rnss to be tested in real time;

[0010] The high-voltage reed switch relay control circuit comprises a high-voltage reed switch relay, and the relay output end of the high-voltage reed switch relay can switch voltage.

[0011] It is further defined that the first solid-state relay control circuit also includes a resistor R5 and a first IO interface of the MCU module, the first solid-state relay U1 includes pin 4 and pin 6, one end of the resistor R5 is connected to the first IO interface, and the other end is connected to the first solid-state relay U1, and when the MCU module outputs a high level, pins 4 and 6 of the first solid-state relay U1 are turned on.

[0012] It is further defined that the first operational amplifier circuit is U5.1, the second operational amplifier circuit is U5.2, and the isolation amplifier circuit is U3.

[0013] The first operational amplifier circuit U5.1 includes a first operational amplifier, a resistor R3, a resistor R7 and a resistor R13, one end of the resistor R7 is connected to the resistor to be measured Rnss and the resistor R3, and the other end is connected to the pin 3 of the first operational amplifier, and the resistor R13 is connected to the pins 1 and 2 of the first operational amplifier;

[0014] The second operational amplifier circuit U5.2 includes a second operational amplifier, a resistor R8, a resistor R10 and a resistor 12, wherein the resistor R8 is connected to pin 5 of the second operational amplifier, the resistor R10 is connected to pin 6 of the second operational amplifier, and the resistor 12 is connected to pins 6 and 7 of the second operational amplifier;

[0015] The isolation amplifier circuit U3 includes an isolation amplifier, a capacitor C1, a capacitor C2, a capacitor C3 and a resistor R9, wherein the capacitor C1 is connected to pin 1 of the isolation amplifier, the capacitor C2 is connected to pin 2 of the isolation amplifier, and the resistor R9 is connected to pin 7 of the isolation amplifier, the capacitor C3 and the AD pin of the MCU module.

[0016] It is further defined that when the input voltage is positive, the potential of the input terminal of the second operational amplifier circuit U5.2 is the same as the input signal, and the second operational amplifier circuit U5.2 is used to transmit the positive signal to the output terminal;

[0017] When the input signal is negative, the output voltage of the first operational amplifier circuit U5.1 is 0V, and the second operational amplifier circuit U5.2 inverts the input signal to obtain the input signal voltage value. At this time, the output voltage is amplified by the isolation amplifier U3 and then transmitted to the AD pin of the MCU module for collection. The output voltage is constantly a positive voltage.

[0018] It is further defined that the high-voltage reed switch relay control circuit also includes a resistor R11, a resistor R14, a resistor R15 and a transistor Q1, pin No. 3 of the high-voltage reed switch relay is connected to resistor R11, the resistor R11 is connected to the emitter of the transistor Q1, the resistor R14 and the resistor R15 are connected to the base of the transistor Q1, the resistor R14 is connected to the third IO interface of the MCU module, the emitter of the transistor Q1 is connected to resistor R15, and pin No. 7 of the high-voltage reed switch relay is connected to the casing ground. When the third IO interface of the MCU module outputs a high level, the high-voltage reed switch relay is closed, the casing ground is connected to the detection circuit, and insulation detection starts.

[0019] It is further defined that the insulation detection circuit device and method according to claim 2 is characterized in that: it also includes a second solid-state relay control circuit, the second solid-state relay control circuit includes a second solid-state relay U2, a resistor R6 and a second IO interface of the MCU module, pin 6 of the second solid-state relay U2 is connected to the second IO interface of the MCU module, and the resistor R6 is connected to the second IO interface of the MCU module.

[0020] It is further defined that it also includes a main circuit, the main circuit includes a resistor R1, a resistor R2, a resistor to be measured Rpss, a resistor R3 and a resistor R4, the resistor R1 is connected to pin No. 6 of the second solid-state relay U2, the resistor R2 and pin No. 6 of the first solid-state relay U1;

[0021] The resistor R2 is connected to the resistor to be measured Rpss, the resistor to be measured Rpss is connected to the resistor to be measured Rnss, the resistor to be measured Rnss is connected to the resistor R3, the resistor R3 is connected to pin 4 of the second solid-state relay and the resistor R4, and the resistor R4 is connected to pin 4 of the first solid-state relay U1.

[0022] An insulation detection circuit detection method:

[0023] The third IO interface of the MCU module controls the high-voltage reed switch relay to close and start insulation detection. Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack, Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack, Vbat is the voltage between B+ and B-, V1 is the upper bridge arm voltage, V2 is the lower bridge arm voltage, Vnss is the voltage across Rnss collected by the AD pin of the MCU module after the voltage collection circuit, and R1, R2, R3, R4 and the resistances to be measured Rpss and Rnss are known resistances;

[0024] Let Rp'=R1+R2+Rpss; let Rn'=r3+r4+Rnss;

[0025] V1 = Vbat - V2;

[0026] at the same time

[0027] So we can get the formula:

[0028] Further defined, if the voltage of the lower bridge arm is greater than the voltage of the upper bridge arm, u1 is closed, at this time: Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack; Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack; Vbat is the voltage between B+ and B-, V1' is the voltage of the upper bridge arm; V2' is the voltage of the lower bridge arm, and Vnss' is the voltage across the resistor Rnss to be measured collected by the AD pin of the MCU module after the voltage acquisition circuit; wherein R1, R2, R3, R4 and the resistors Rpss and Rnss to be measured are known resistors;

[0029] Let Rn" = (R3 + R4 + Rnss) / / (Rpss + R2);

[0030] V1' = Vbat - V2';

[0031] at the same time

[0032] So we can get the formula:

[0033] Further defined, if the voltage of the upper bridge arm is greater than the voltage of the lower bridge arm, the second solid-state relay U2 is closed; at this time: Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack; Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack, Vbat is the voltage between B+ and B-, V1” is the voltage of the upper bridge arm; V2” is the voltage of the lower bridge arm, Vnss” is the voltage across Rnss collected by the AD pin of the MCU module after the voltage acquisition circuit, wherein R1, R2, R3, R4 and the resistances to be measured Rpss and Rnss are known resistances;

[0034] Let Rp'=(R1+R2+Rpss) / / (Rnss+R3);

[0035] V2" = Vbat - V1';

[0036] at the same time

[0037] So we can get the formula:

[0038] By solving the equations simultaneously, we can obtain the sizes of Rp and Rn.

[0039] The insulation detection circuit device and method provided by the present invention have the following beneficial effects:

[0040] 1. Simple circuit structure:

[0041] Compared with the traditional insulation detection circuit, there is no need to connect an additional known resistor in parallel. This solution uses its own structure to flexibly control the relay to change the resistance values ​​of the upper and lower bridge arms respectively.

[0042] 2. Occupies fewer AD pins of the MCU module:

[0043] Compared with traditional insulation detection circuits, two AD pins are often required to detect the upper and lower bridge arm voltages after switching back and forth.

[0044] 3. Can pass high voltage insulation withstand test:

[0045] Since the energy storage system needs to pass a withstand voltage test that is several times larger than its own voltage platform, and the maximum switching voltage at the output end of the high-voltage reed switch relay can reach several thousand or even tens of thousands of volts, it can pass the withstand voltage test well. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0047] Figure 1 It is an overall circuit diagram of an insulation detection circuit device and method embodiment of the present invention;

[0048] Figure 2 A first solid-state relay control circuit diagram of an insulation detection circuit device and method embodiment of the present invention;

[0049] Figure 3 A detection circuit diagram of an insulation detection circuit device and method embodiment of the present invention;

[0050] Figure 4A high-voltage reed switch relay control circuit diagram of an insulation detection circuit device and method embodiment of the present invention;

[0051] Figure 5 A high-voltage dry reed switch relay closing circuit diagram of an insulation detection circuit device and method embodiment of the present invention;

[0052] Figure 6 A closed circuit diagram of a first solid-state relay U1 in an insulation detection circuit device and method embodiment of the present invention;

[0053] Figure 7 This is a closed circuit diagram of the second solid-state relay U2 in an insulation detection circuit device and method embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0055] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0056] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] like Figure 1 As shown, an insulation detection circuit device and method of the present invention includes an MCU module, a first solid-state relay control circuit, a detection circuit and a high-voltage reed switch relay control circuit;

[0058] The first solid-state relay control circuit includes a first solid-state relay U1, and when the MCU module outputs a high level, the first solid-state relay U1 is turned on;

[0059] like Figure 3 As shown, the detection circuit includes a first operational amplifier circuit, a second operational amplifier circuit and an isolation amplifier circuit, and the detection circuit is used to monitor the voltage across the resistor Rnss to be tested in real time;

[0060] The high-voltage reed switch relay control circuit comprises a high-voltage reed switch relay, and the relay output end of the high-voltage reed switch relay can switch voltage.

[0061] like Figure 2 As shown, in the actual application of this embodiment, the first solid-state relay control circuit also includes a resistor R5 and a first IO interface of the MCU module, the first solid-state relay U1 includes pin 4 and pin 6, one end of the resistor R5 is connected to the first IO interface, and the other end is connected to the first solid-state relay U1, when the MCU module outputs a high level, pins 4 and 6 of the first solid-state relay U1 are turned on.

[0062] In the practical application of this embodiment, the first operational amplifier circuit is U5.1, the second operational amplifier circuit is U5.2, and the isolation amplifier circuit is U3.

[0063] The first operational amplifier circuit U5.1 includes a first operational amplifier, a resistor R3, a resistor R7 and a resistor R13, one end of the resistor R7 is connected to the resistor to be measured Rnss and the resistor R3, and the other end is connected to the pin 3 of the first operational amplifier, and the resistor R13 is connected to the pins 1 and 2 of the first operational amplifier;

[0064] The second operational amplifier circuit U5.2 includes a second operational amplifier, a resistor R8, a resistor R10 and a resistor 12, wherein the resistor R8 is connected to pin 5 of the second operational amplifier, the resistor R10 is connected to pin 6 of the second operational amplifier, and the resistor 12 is connected to pins 6 and 7 of the second operational amplifier;

[0065] The isolation amplifier circuit U3 includes an isolation amplifier, a capacitor C1, a capacitor C2, a capacitor C3 and a resistor R9, wherein the capacitor C1 is connected to pin 1 of the isolation amplifier, the capacitor C2 is connected to pin 2 of the isolation amplifier, and the resistor R9 is connected to pin 7 of the isolation amplifier, the capacitor C3 and the AD pin of the MCU module.

[0066] In practical applications of this embodiment, when the input voltage is positive, the potential of the input terminal of the second operational amplifier circuit U5.2 is the same as the input signal, and the second operational amplifier circuit U5.2 is used to transmit the positive signal to the output terminal;

[0067] When the input signal is negative, the output voltage of the first operational amplifier circuit U5.1 is 0V, and the second operational amplifier circuit U5.2 inverts the input signal to obtain the input signal voltage value. At this time, the output voltage is amplified by the isolation amplifier U3 and then transmitted to the AD pin of the MCU module for collection. The output voltage is constantly a positive voltage.

[0068] like Figure 4 As shown, in the actual application of this embodiment, the high-voltage reed switch relay control circuit also includes a resistor R11, a resistor R14, a resistor R15 and a transistor Q1, pin No. 3 of the high-voltage reed switch relay is connected to resistor R11, the resistor R11 is connected to the emitter of the transistor Q1, the resistor R14 and the resistor R15 are connected to the base of the transistor Q1, the resistor R14 is connected to the third IO interface of the MCU module, the emitter of the transistor Q1 is connected to resistor R15, and pin No. 7 of the high-voltage reed switch relay is connected to the chassis ground. When the third IO interface of the MCU module outputs a high level, the high-voltage reed switch relay is closed, the chassis ground is connected to the detection circuit, and insulation detection starts.

[0069] Specifically, the reason for using high-voltage reed switch relays is that the energy storage system needs to undergo a withstand voltage test that is several times the size of its own voltage platform, and the maximum switching voltage at the output end of the high-voltage reed switch relay can reach several thousand or even tens of thousands of volts, which makes it easy to pass the withstand voltage test.

[0070] In the actual application of this embodiment, a second solid-state relay control circuit is also included, which includes a second solid-state relay U2, a resistor R6 and a second IO interface of the MCU module, pin 6 of the second solid-state relay U2 is connected to the second IO interface of the MCU module, and the resistor R6 is connected to the second IO interface of the MCU module.

[0071] In the practical application of this embodiment, a main circuit is also included, the main circuit includes a resistor R1, a resistor R2, a resistor to be measured Rpss, a resistor R3 and a resistor R4, the resistor R1 is connected to pin 6 of the second solid-state relay U2, the resistor R2 and pin 6 of the first solid-state relay U1;

[0072] The resistor R2 is connected to the resistor to be measured Rpss, the resistor to be measured Rpss is connected to the resistor to be measured Rnss, the resistor to be measured Rnss is connected to the resistor R3, the resistor R3 is connected to pin 4 of the second solid-state relay and the resistor R4, and the resistor R4 is connected to pin 4 of the first solid-state relay U1.

[0073] An insulation detection circuit detection method:

[0074] like Figure 5 As shown, the third IO interface of the MCU module controls the high-voltage reed switch relay to close and start insulation detection, Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack, Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack, Vbat is the voltage between B+ and B-, V1 is the upper bridge arm voltage, V2 is the lower bridge arm voltage, Vnss is the voltage across Rnss collected by the AD pin of the MCU module after the voltage collection circuit, and R1, R2, R3, R4 and the resistances to be measured Rpss and Rnss are known resistances;

[0075] Let Rp'=R1+R2+Rpss; let Rn'=r3+r4+Rnss;

[0076] V1 = Vbat - V2;

[0077] at the same time

[0078] So we can get the formula:

[0079] Specifically, under ideal conditions, the insulation resistance of B+ and B- of the battery pack to the chassis ground should be infinite; as long as the resistance of one of Rn and Rp is large enough, the chassis ground and the battery do not form a conductive loop, and they are insulated from each other; only when the insulation resistance of Rn and Rp drops to a certain value at the same time, the high-voltage battery loop forms a leakage loop to the chassis ground, which will cause a short circuit.

[0080] Specifically, after detecting the upper and lower bridge arm voltages for the first time, the magnitudes of the two voltages are judged to determine whether to close the solid-state relay U1 or U2 for the second time.

[0081] like Figure 6As shown, in the actual application of this embodiment, if the voltage of the lower bridge arm is greater than the voltage of the upper bridge arm, the first solid-state relay U1 is closed, at this time: Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack; Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack; Vbat is the voltage between B+ and B-, V1' is the voltage of the upper bridge arm; V2' is the voltage of the lower bridge arm, and Vnss' is the voltage across the resistor Rnss to be measured collected by the AD pin of the MCU module after the voltage acquisition circuit; wherein R1, R2, R3, R4 and the resistors Rpss and Rnss to be measured are known resistors;

[0082] Let Rn" = (R3 + R4 + Rnss) / / (Rpss + R2);

[0083] V1' = Vbat - V2';

[0084] at the same time

[0085] So we can get the formula:

[0086] like Figure 7 As shown, in the actual application of this embodiment, if the voltage of the upper bridge arm is greater than the voltage of the lower bridge arm, the second solid-state relay U2 is closed; at this time: Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack; Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack, Vbat is the voltage between B+ and B-, V1" is the voltage of the upper bridge arm; V2" is the voltage of the lower bridge arm, Vnss" is the voltage across Rnss collected by the AD pin of the MCU module after the voltage collection circuit, wherein R1, R2, R3, R4 and the resistances to be measured Rpss and Rnss are known resistances;

[0087] Let Rp'=(R1+R2+Rpss) / / (Rnss+R3);

[0088] V2'' = Vbat - V1';

[0089] at the same time

[0090] So we can get the formula:

[0091] By solving the equations simultaneously, we can obtain the sizes of Rp and Rn.

[0092] Software Optimization:

[0093] This embodiment uses an optimized software algorithm to ensure that the detection voltage is stable. Due to the presence of capacitors in the high-voltage circuit, after the bias resistor is connected, the detection voltage takes a long time to reach a new stable value. If the insulation resistance calculation is performed when the inspection voltage is not stable, a large error will occur. This embodiment adds time filtering, voltage comparison and other methods to the software to ensure that the insulation resistance calculation is performed after the inspection voltage is stable.

[0094] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An insulation detection circuit device, comprising an MCU module, characterized in that: It also includes a first solid-state relay U1 control circuit, a detection circuit and a high-voltage reed switch relay control circuit; The first solid-state relay control circuit includes a first solid-state relay U1, and when the MCU module outputs a high level, the first solid-state relay U1 is turned on; The detection circuit includes a first operational amplifier circuit, a second operational amplifier circuit and an isolation amplifier circuit, and the detection circuit is used to monitor the voltage across the resistor Rnss to be tested in real time; The high-voltage reed switch relay control circuit comprises a high-voltage reed switch relay, and the relay output end of the high-voltage reed switch relay can switch voltage.

2. An insulation detection circuit device according to claim 1, characterized in that: The first solid-state relay control circuit also includes a resistor R5 and a first IO interface of the MCU module. The first solid-state relay U1 includes pin 4 and pin 6. One end of the resistor R5 is connected to the first IO interface, and the other end is connected to the first solid-state relay U1. When the MCU module outputs a high level, pins 4 and 6 of the first solid-state relay U1 are turned on.

3. An insulation detection circuit device according to claim 1, characterized in that: The first operational amplifier circuit is U5.1, the second operational amplifier circuit is U5.2, and the isolation amplifier circuit is U3. The first operational amplifier circuit U5.1 includes a first operational amplifier, a resistor R3, a resistor R7 and a resistor R13, one end of the resistor R7 is connected to the resistor to be measured Rnss and the resistor R3, and the other end is connected to the pin 3 of the first operational amplifier, and the resistor R13 is connected to the pins 1 and 2 of the first operational amplifier; The second operational amplifier circuit U5.2 includes a second operational amplifier, a resistor R8, a resistor R10 and a resistor 12, wherein the resistor R8 is connected to pin 5 of the second operational amplifier, the resistor R10 is connected to pin 6 of the second operational amplifier, and the resistor 12 is connected to pins 6 and 7 of the second operational amplifier; The isolation amplifier circuit U3 includes an isolation amplifier, a capacitor C1, a capacitor C2, a capacitor C3 and a resistor R9, wherein the capacitor C1 is connected to pin 1 of the isolation amplifier, the capacitor C2 is connected to pin 2 of the isolation amplifier, and the resistor R9 is connected to pin 7 of the isolation amplifier, the capacitor C3 and the AD pin of the MCU module.

4. An insulation detection circuit device according to claim 4, characterized in that: When the input voltage is positive, the potential of the input terminal of the second operational amplifier circuit U5.2 is the same as the input signal, and the second operational amplifier circuit U5.2 is used to transmit the positive signal to the output terminal; When the input signal is negative, the output voltage of the first operational amplifier circuit U5.1 is 0V, and the second operational amplifier circuit U5.2 inverts the input signal to obtain the input signal voltage value. At this time, the output voltage is amplified by the isolation amplifier U3 and then transmitted to the AD pin of the MCU module for collection. The output voltage is constantly a positive voltage.

5. An insulation detection circuit device according to claim 1, characterized in that: The high-voltage reed switch relay control circuit also includes a resistor R11, a resistor R14, a resistor R15 and a transistor Q1. Pin 3 of the high-voltage reed switch relay is connected to resistor R11, and the resistor R11 is connected to the emitter of the transistor Q1. The resistor R14 and the resistor R15 are connected to the base of the transistor Q1. The resistor R14 is connected to the third IO interface of the MCU module, and the emitter of the transistor Q1 is connected to resistor R15. Pin 7 of the high-voltage reed switch relay is connected to the casing ground. When the third IO interface of the MCU module outputs a high level, the high-voltage reed switch relay is closed, the casing ground is connected to the detection circuit, and insulation detection starts.

6. An insulation detection circuit device according to claim 1, characterized in that: An insulation detection circuit device and method according to claim 2 is characterized in that: it also includes a second solid-state relay control circuit, the second solid-state relay control circuit includes a second solid-state relay U2, a resistor R6 and a second IO interface of the MCU module, pin 6 of the second solid-state relay U2 is connected to the second IO interface of the MCU module, and the resistor R6 is connected to the second IO interface of the MCU module.

7. An insulation detection circuit device according to claim 6, characterized in that: It also includes a main circuit, which includes a resistor R1, a resistor R2, a resistor to be measured Rpss, a resistor R3 and a resistor R4, wherein the resistor R1 is connected to pin No. 6 of the second solid-state relay U2, the resistor R2 and pin No. 6 of the first solid-state relay U1; The resistor R2 is connected to the resistor to be measured Rpss, the resistor to be measured Rpss is connected to the resistor to be measured Rnss, the resistor to be measured Rnss is connected to the resistor R3, the resistor R3 is connected to pin 4 of the second solid-state relay and the resistor R4, and the resistor R4 is connected to pin 4 of the first solid-state relay U1.

8. A method for detecting an insulation detection circuit, characterized in that: The third IO interface of the MCU module controls the high-voltage reed switch relay to close and start insulation detection. Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack, Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack, Vbat is the voltage between B+ and B-, V1 is the upper bridge arm voltage, V2 is the lower bridge arm voltage, Vnss is the voltage across Rnss collected by the AD pin of the MCU module after the voltage collection circuit, and R1, R2, R3, R4 and the resistances to be measured Rpss and Rnss are known resistances; Let Rp'=R1+R2+Rpss; let Rn'=r3+r4+Rnss; <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> V1=Vbat-V2; at the same time So we can get the formula:

9. An insulation detection circuit method according to claim 8, characterized in that: If the voltage of the lower bridge arm is greater than the voltage of the upper bridge arm, the first solid-state relay U1 is closed. At this time: Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack; Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack; Vbat is the voltage between B+ and B-, V1' is the voltage of the upper bridge arm; V2' is the voltage of the lower bridge arm, and Vnss' is the voltage across the resistor Rnss to be measured collected by the AD pin of the MCU module after the voltage acquisition circuit; wherein R1, R2, R3, R4 and the resistors Rpss and Rnss to be measured are known resistors; Let Rn" = (R3 + R4 + Rnss) / / (Rpss + R2); <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> V1'=Vbat-V2'; at the same time So we can get the formula:

10. An insulation detection circuit method according to claim 9, characterized in that: If the voltage of the upper bridge arm is greater than that of the lower bridge arm, the second solid-state relay U2 is closed; at this time: Rp is the resistance to be measured between the chassis ground and the negative electrode B- of the battery pack; Rn is the resistance to be measured between the chassis ground and the positive electrode B+ of the battery pack, Vbat is the voltage between B+ and B-, V1” is the voltage of the upper bridge arm; V2” is the voltage of the lower bridge arm, Vnss” is the voltage across Rnss collected by the AD pin of the MCU module after the voltage acquisition circuit, where R1, R2, R3, R4 and the resistances to be measured Rpss and Rnss are known resistances; Let Rp'=(R1+R2+Rpss) / / (Rnss+R3); <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> V2”=Vbat-V1'; at the same time So we can get the formula: By solving the equations simultaneously, we can obtain the sizes of Rp and Rn.

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