CN117969954A - System and method for detecting high-voltage insulation resistance of automobile - Google Patents

System and method for detecting high-voltage insulation resistance of automobile Download PDF

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Publication number
CN117969954A
CN117969954A CN202410007170.6A CN202410007170A CN117969954A CN 117969954 A CN117969954 A CN 117969954A CN 202410007170 A CN202410007170 A CN 202410007170A CN 117969954 A CN117969954 A CN 117969954A
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resistor
voltage
insulation resistance
switch
detection system
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李明
罗晓
胡红利
倪斌
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Jifu Automotive Technology Suzhou Co ltd
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Jifu Automotive Technology Suzhou Co ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

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  • Measurement Of Resistance Or Impedance (AREA)

Abstract

The invention discloses a system and a method for detecting high-voltage insulation resistance of an automobile, wherein the system comprises switches K1, K2, K3, K4 and K5, resistors R1, R2, R3, R4, R5 and R6 and a calculation control unit; the positive electrode of the high-voltage battery is grounded through a resistor R1, a switch K3 and a switch K2 which are sequentially connected in series; the negative electrode of the high-voltage battery is connected to a loop between the switches K3 and K2 after passing through the resistor R2 and the switch K4 which are connected in series in sequence; the positive electrode of the high-voltage battery is connected with the negative electrode of the high-voltage battery after passing through a switch K1, a resistor R4, a resistor R5 and a resistor R6 which are connected in series in sequence; the lead-out terminal between the switches K2 and K3 is connected between the resistor R4 and the resistor R5 through the switch K5 and the resistor R3. The self-checking and insulation detection method of the system matched design are combined, so that insulation resistance detection can be accurately and reliably performed, and an output insulation detection result is accurate and reliable.

Description

System and method for detecting high-voltage insulation resistance of automobile
Technical Field
The invention relates to the field of automobile electrical detection, in particular to an automobile high-voltage insulation resistance detection system and method.
Background
The automobile working environment is complex, and the automobile is often operated under severe working conditions such as vibration, high temperature, high humidity and the like. The power battery pack works for a long time in the environment, the insulation assembly is affected by corrosion and the like, insulation performance is poor, short circuit and the like are caused, potential safety hazards such as short circuit of the power battery pack to the automobile shell are caused, and personal safety and public safety of personnel on the automobile are threatened. Therefore, the insulation resistance detection scheme with high precision and high reliability is of great significance for guaranteeing personal safety and automobile property safety.
In the prior art, some detection methods are often adopted to detect the insulation resistance, but the insulation detection technology in the prior art is the detection calculation which is carried out by the default insulation detection circuit with perfect functions and the insulation detection circuit resistance value precision meeting the requirements. However, as the insulation detection circuit uses more measuring resistance, when the equipment runs for a long time in a severe environment, the possibility of short circuit, short circuit and resistance deviation is greatly improved, and the insulation resistance detected by insulation detection circuit is inaccurate, and even the insulation resistance detection function fails. Therefore, in the prior art, the scheme of not considering the state of the detection circuit in the detection circuit and the corresponding detection method cannot accurately and reliably detect the insulation resistance.
An insulation resistance detection device, a vehicle, and an insulation resistance value determination method as described in patent application No. 202210899602.X, are disclosed that include: the device comprises N high-voltage platforms, N positive electrode insulation resistors, N negative electrode insulation resistors, a processing module, a first resistor, a second resistor, a voltage signal source and a voltage measuring module, wherein the first end of the first resistor is connected with a first connecting point of a first high-voltage sub-platform and a second high-voltage sub-platform, and the second end of the first resistor is connected with the first end of the second resistor; the second end of the second resistor is connected with the positive electrode of the voltage signal source; the negative electrode of the voltage signal source is connected with the ground terminal; the first end of the voltage measurement module is connected with a second connection point of the first resistor and the second resistor, and the second end of the voltage measurement module is connected with the negative electrode of the voltage signal source; the processing module is connected with the voltage measuring module and is used for determining the parallel connection value of the insulation resistances of the N high-voltage platforms according to the voltage value output by the voltage measuring module. Although the patent discloses a detection scheme of insulation resistance, the scheme still does not consider whether the detection circuit is normal, so that the defect of inaccurate detection result caused by the problem of the detection circuit cannot be solved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a system and a method for detecting the high-voltage insulation resistance of an automobile, which are used for the technical problem of inaccurate insulation resistance detection in the prior art.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: the automobile high-voltage insulation resistance detection system comprises switches K1, K2, K3, K4 and K5, resistors R1, R2, R3, R4, R5 and R6 and a calculation control unit;
The positive electrode of the high-voltage battery is grounded through a resistor R1, a switch K3 and a switch K2 which are sequentially connected in series; the negative electrode of the high-voltage battery is connected to a loop between the switches K3 and K2 after passing through the resistor R2 and the switch K4 which are connected in series in sequence;
The positive electrode of the high-voltage battery is connected with the negative electrode of the high-voltage battery after passing through a switch K1, a resistor R4, a resistor R5 and a resistor R6 which are connected in series in sequence;
The lead-out terminal between the switches K2 and K3 is connected between the resistor R4 and the resistor R5 through the switch K5 and the resistor R3.
The detection system also comprises a calculation control unit, wherein the output end of the calculation control unit is respectively connected to the switches K1, K2, K3, K4 and K5 and is used for respectively controlling the on-off states of the switches K1, K2, K3, K4 and K5 during detection; the calculation control unit is used for collecting voltages at two ends of the resistor R6 during detection, judging the fault state of the detection system based on the collected voltages, and calculating to obtain insulation resistance data based on the voltages at two ends of the resistor R6 when the detection system is in a normal state.
An insulation resistance detection method based on the high-voltage insulation resistance detection system comprises the following steps:
step 1, performing self-checking on a detection system, judging whether the detection system is in an abnormal state or a normal state, and if the detection system is in the normal state, entering a step 2;
step 2: the on-off control of the switches K1, K2, K3, K4 and K5 is carried out according to preset logic, the voltages at the two ends of the resistor R6 are collected, and the insulation resistance value is obtained based on the voltage calculation at the two ends of the resistor R6.
In step 1, performing self-checking on the detection system, and determining that the detection system is in an abnormal state and is in a normal state includes:
the switches K1, K2, K3, K4 and K5 are controlled according to preset open-close state logic, voltages at two ends of the resistor R6 are collected during each control, and whether the detection system is abnormal is judged based on the voltages at the two ends of the resistor R6.
The preset open/close state logic includes:
(1) The control switches K1, K2, K3, K4 and K5 are kept off;
(2) Closing the switch K1, and controlling the switches K2, K3, K4 and K5 to be kept open;
(3) Closing the switch K2, and controlling the switches K1, K3, K4 and K5 to be kept open;
(4) Closing the switch K3 and K5; the control switches K1, K2 and K4 are kept off;
(5) Closing the switches K1, K4 and K5; the control switches K2, K3 remain open.
In the open-close state logic (1), collecting voltages at two ends of a resistor R6, judging whether the collected voltages are 0, and if not, judging that a loop of the detection system is abnormal;
In the open-close state logic (2), collecting voltages at two ends of a resistor R6, judging whether the difference between the collected voltage and a theoretical voltage U62 exceeds a threshold value, and if yes, judging that a loop of the detection system is abnormal;
In the open-close state logic (3), collecting voltages at two ends of a resistor R6, judging whether the collected voltages are 0, and if not, judging that a loop of the detection system is abnormal;
in the open-close state logic (4), collecting voltages at two ends of a resistor R6, judging whether the difference between the collected voltage and a theoretical voltage U64 exceeds a threshold value, and if yes, judging that a loop of the detection system is abnormal;
in the open-close state logic (5), collecting voltages at two ends of a resistor R6, judging whether the difference between the collected voltage and a theoretical voltage U65 exceeds a threshold value, and if yes, judging that a loop of the detection system is abnormal;
and if the detection system loop is not judged to be abnormal under all the open-close state logics, judging that the detection system is normal.
The theoretical voltages are respectively:
Wherein R1, R2, R3, R4, R5 and R6 are respectively resistance values; vbat is the terminal voltage of the battery.
The step 2 comprises the following steps:
Step 21: closing the switch K1, and keeping the switches K2, K3, K4 and K5 open; at the moment, the voltage U6 at two ends of the sampling resistor R6 is read and the terminal voltage value Vbat of the battery is obtained through calculation;
Step 22: opening K1, K3 and K4, closing K2 and K5, and reading the voltage U6' at two ends of the sampling resistor R6 at the moment;
Step 23: closing K1, K2 and K5, and opening K3 and K4, wherein the voltages U6' at two ends of the sampling resistor R6 are collected and read at the moment;
Step 24: based on the collected voltages U6, U6', U6 ", a positive insulation resistance value Riso + and a negative insulation resistance value Riso - are calculated according to an insulation resistance formula.
The insulation resistance calculation formula includes:
The result in step 21:
The formula obtained in step 22:
The formula obtained in step 23
And (3) and (4) and (5) simultaneously solving the binary one-time equation to obtain the expressions of the positive insulation resistance value Riso + and the negative insulation resistance value Riso -.
Vbat is the voltage at both ends of the battery directly acquired by the newly added acquisition circuit or the accurate voltage at both ends of the battery acquired by the vehicle BMS.
The invention has the advantages that: the circuit with the novel design has the advantages of simple and reliable circuit structure and low cost; meanwhile, based on a newly designed circuit, two sets of logics are designed for self-checking and detection, and insulation detection is performed after the self-checking is normal, so that the detection result is more accurate and reliable, the problem of inaccurate insulation resistance detection caused by the existence of the circuit problem is avoided, and the detection accuracy is improved.
Drawings
The contents of the drawings and the marks in the drawings of the present specification are briefly described as follows:
FIG. 1 is a topology of an insulation resistance detection circuit provided in the present application;
FIG. 2 is a corresponding equivalent circuit diagram of the self-test state of the insulation resistance provided in the present application;
FIG. 3 is a schematic diagram of an equivalent circuit corresponding to a second state of the insulation resistance self-test provided in the present application;
fig. 4 is a state three corresponding equivalent circuit diagram of insulation resistance self-checking provided in the present application;
Fig. 5 is a state five corresponding equivalent circuit diagram of insulation resistance self-checking provided in the present application.
Detailed Description
The following detailed description of the invention refers to the accompanying drawings, which illustrate preferred embodiments of the invention in further detail.
The main purpose of the technical scheme of the embodiment is to design a detection circuit and design a self-checking method and an insulation detection method based on the detection circuit aiming at the problem that the error of insulation fault is caused because the deviation exists between the measured value and the actual value of insulation detection in the prior art, and the insulation detection can be realized more accurately by determining the normal condition through the self-checking method. The circuit designed by the application comprises: an insulation detection circuit is used for detecting insulation resistance of a battery positive electrode to a casing ground and a battery negative electrode to the casing ground respectively. The circuit comprises an insulation resistance unit, a standard resistance unit, a voltage dividing resistance unit and a sampling resistor. The insulation resistance unit comprises a first insulation resistance between the battery anode and the shell ground, and a second insulation resistance between the battery cathode and the shell ground; the standard resistor unit comprises a first standard resistor, a second standard resistor and a third standard resistor, wherein the positive electrode of the battery is connected with the ground of the shell through a second switch and a third switch, and the negative electrode of the battery is connected with the ground of the shell through the second switch and a fourth switch; the voltage dividing resistor unit consists of a first switch, a fifth switch, a plurality of voltage dividing resistors and the like; the sampling resistor is electrically connected with the voltage dividing resistor unit.
In a second aspect, the present application provides a method for self-checking a detection circuit, the method comprising: all switches are not conducted, and a first voltage is obtained through a sampling resistor; controlling the first switch to be closed, and obtaining a second voltage through the sampling resistor; controlling the fifth switch to be closed, and obtaining a third voltage through a sampling resistor; controlling the third switch and the fifth switch to be closed to obtain a fourth voltage; controlling the first switch, the fourth switch and the fifth switch to be closed, and obtaining a fifth voltage through a sampling resistor; based on the mutual comparison between the voltages, it can be determined whether the function of the insulation detection circuit is reliable
In a third aspect, the present application provides a method of insulation resistance detection, the detection method comprising: controlling the first switch, the second switch, the third switch and the fourth switch to be closed, and reading a sixth voltage; controlling the second switch, the third switch, the fourth switch and the fifth switch to be closed, and reading a seventh voltage; controlling the first switch, the second switch, the third switch, the fourth switch and the fifth switch to be closed, and reading an eighth voltage; and determining the resistance values of the first insulation resistor and the second insulation resistor according to the sixth voltage, the seventh voltage and the eighth voltage.
The application provides an insulation detection circuit, an insulation circuit self-checking method and an insulation resistance detection method, which comprise a first insulation resistance between a battery anode and a casing ground and a second insulation resistance between a battery cathode and the casing ground; the standard resistor unit comprises a first standard resistor, a second standard resistor and a third standard resistor, wherein the positive electrode of the battery is connected with the ground of the shell through a second switch and a third switch, and the negative electrode of the battery is connected with the ground of the shell through the second switch and a fourth switch; the voltage dividing resistor unit is composed of a first switch, a fifth switch and a plurality of voltage dividing resistors; a first switch, a second switch, a third switch, a fourth switch and a fifth switch. All switches are not conducted, and a first voltage is obtained through a sampling resistor; controlling the first switch to be closed, and obtaining a second voltage through the sampling resistor; controlling the fifth switch to be closed, and obtaining a third voltage through a sampling resistor; controlling the third switch and the fifth switch to be closed to obtain a fourth voltage; controlling the first switch, the fourth switch and the fifth switch to be closed, and obtaining a fifth voltage through a sampling resistor; according to the mutual comparison between the voltages, whether the function of the insulation detection circuit is reliable or not can be judged. Reading a sixth voltage by controlling the first switch, the second switch, the third switch and the fourth switch to be closed; controlling the second switch, the third switch, the fourth switch and the fifth switch to be closed, and reading a seventh voltage; controlling the first switch, the second switch, the third switch, the fourth switch and the fifth switch to be closed, and reading an eighth voltage; and determining the resistance values of the first insulation resistor and the second insulation resistor according to the sixth voltage, the seventh voltage and the eighth voltage. Through this insulation resistance detection mode, increased the self-checking function to insulation detection circuit, guaranteed insulation detection circuit's reliability and insulation resistance data's credibility.
Wherein: the first, second, third, fourth and fifth switches are K1, K2, K3, K4 and K5 respectively; the resistors R1 and R2 are respectively a first standard resistor and a second standard resistor; the equivalent first insulation resistance and the second insulation resistance are riso+ and Riso-; the divider resistors are R3, R4 and R5, and the sampling resistor R6. As shown in fig. 1, a circuit structure diagram of a specific design is shown:
Riso +, riso-are equivalent positive and negative insulation resistances, respectively, in fig. 1. The automobile high-voltage insulation resistance detection system comprises switches K1, K2, K3, K4 and K5, resistors R1, R2, R3, R4, R5 and R6 and a calculation control unit;
The positive electrode of the high-voltage battery is grounded through a resistor R1, a switch K3 and a switch K2 which are sequentially connected in series; the negative electrode of the high-voltage battery is connected to a loop between the switches K3 and K2 after passing through the resistor R2 and the switch K4 which are connected in series in sequence;
The positive electrode of the high-voltage battery is connected with the negative electrode of the high-voltage battery after passing through a switch K1, a resistor R4, a resistor R5 and a resistor R6 which are connected in series in sequence;
The leading-out terminal between the switches K2 and K3 is connected between the resistor R4 and the resistor R5 through the switch K5 and the resistor R3;
The detection system comprises a calculation control unit, wherein the output end of the calculation control unit is respectively connected to the switches K1, K2, K3, K4 and K5 and is used for respectively controlling the on-off states of the switches K1, K2, K3, K4 and K5 during detection; the calculation control unit is used for collecting the voltages at the two ends of the resistor R6 during detection, judging the fault state of the detection system based on the collected voltages, and calculating the insulation resistance data based on the voltages at the two ends of the resistor R6 when the detection system is in a normal state.
The insulation resistance detection method based on the high-voltage insulation resistance detection system comprises the following steps:
step 1, performing self-checking on a detection system, judging whether the detection system is in an abnormal state or a normal state, and if the detection system is in the normal state, entering a step 2;
step 2: the on-off control of the switches K1, K2, K3, K4 and K5 is carried out according to preset logic, the voltages at the two ends of the resistor R6 are collected, and the insulation resistance value is obtained based on the voltage calculation at the two ends of the resistor R6.
In the step 1, self-checking is carried out on the detection system, the detection system is judged to be in an abnormal state and is in a normal state, if the detection system is judged to be in an abnormal state, an alarm for detecting the circuit abnormality of the insulation detection system is sent out, at the moment, a user is informed of the abnormality of the insulation detection circuit, the insulation resistance value cannot be accurately detected, or the alarm is carried out to remind the user that the vehicle insulation detection is abnormal; when the abnormal state of the detection system circuit is not detected, the detection step of the insulation resistance value can be carried out, so that the accurate and reliable detection of the resistance value in the subsequent detection step is ensured. The self-checking step comprises the following steps:
the switches K1, K2, K3, K4 and K5 are controlled according to preset open-close state logic, voltages at two ends of the resistor R6 are collected during each control, and whether the detection system is abnormal is judged based on the voltages at the two ends of the resistor R6.
As shown in fig. 2-5, the insulating self-test step includes:
Step 1: all switches are kept in an off state, and the voltage at two ends of the sampling resistor R6 is read, and is theoretically 0V at the moment; if the reading value is not 0, judging that the detection system circuit is abnormal, and further judging that the sampling loop is abnormal, namely, a K1 normally closed fault or a K2+K5 normally closed fault;
Step 2: the switch K1 is closed, the other switches are kept open, as shown in an equivalent circuit diagram in FIG. 2, the voltages at two ends of the sampling resistor R6 are read, and the voltage is theoretically the following Wherein R4, R5 and R6 represent resistance values, and Vbat is the terminal voltage of the power battery read by the battery management system BMS; if the reading error exceeds the threshold value, judging that the detection system circuit is abnormal, and further judging that the R4, R5 and R6 circuits are faulty or the switch K1 is faulty; the threshold here refers to an error value allowed in the error range, and if the requirement for insulation detection is high, the threshold may be set to 0 directly.
Step 3: closing a switch K2, and reading the voltage at two ends of a sampling resistor R6, wherein the voltage is 0V theoretically at the moment; if the read value is not 0, the sampling loop is judged to be abnormal, and further K2 or K3 normally closed faults can be judged.
Step 4: closing the switch K3 and K5; the switches K1, K2 and K4 are kept off, the voltage at two ends of the sampling resistor R6 is read, the equivalent circuit diagram is shown in figure 3, and the voltage is theoretically as followsIf the reading error exceeds the threshold value, judging that the circuit loop of the detection system is abnormal, and further judging that the circuits of R1 and K3 are faulty or the circuits of K5 and R3 are faulty; wherein the resistors R1, R3, R5 and R are resistance values, and Vbat is the terminal voltage of the power battery read by the battery management system BMS;
Step 5: closing the switches K1, K4 and K5; the switches K2 and K3 are kept off, the voltages at two ends of the sampling resistor R6 are read, the equivalent circuit is shown in figure 4, and the voltage is theoretically as follows
If the reading error exceeds the threshold value, the circuit loop abnormality of the detection system is judged, and further the sampling loop abnormality, namely R2 and K4 loop faults, can be judged.
And (2) after no abnormality is detected in the steps 1-5, the self-checking is normal, and insulation detection can be carried out after the self-checking is normal, otherwise, the self-checking abnormality is judged and an alarm prompt is output.
And an insulation detection step:
Step one: closing K1, reading the voltage U6 at two ends of the sampling resistor R6, wherein the voltage is shown as an equivalent circuit in FIG. 2, and calculating the Vbat value by using the voltage, wherein the voltage is shown as a formula (1)
Step two: opening K1, K3 and K4, closing K2 and K5, and reading the voltage U6' at two ends of the sampling resistor R6 to obtain a formula (2) based on kirchhoff current theorem, wherein the equivalent circuit is shown in FIG. 5
Step three: closing K1, K2 and K5, opening K3 and K4, reading the voltage U6' at two ends of the sampling resistor R6, and obtaining the following formula based on the kirchhoff current theorem and the resistor voltage reference formula:
The objective of calculating the positive insulation resistance Riso + and the negative insulation resistance Riso - is achieved by performing binary once equation solving according to the above formulas (1) (2) (3) (4) (5), because the other values except Riso +、Riso- in the formulas (1) (2) (3) (4) (5) are known resistance values or voltages at both ends of the acquired R6, the insulation resistance Riso +、Riso- can be calculated.
It is obvious that the specific implementation of the present invention is not limited by the above-mentioned modes, and that it is within the scope of protection of the present invention only to adopt various insubstantial modifications made by the method conception and technical scheme of the present invention.

Claims (10)

1. An automobile high voltage insulation resistance detecting system, which is characterized in that: the device comprises switches K1, K2, K3, K4 and K5, resistors R1, R2, R3, R4, R5 and R6 and a calculation control unit;
The positive electrode of the high-voltage battery is grounded through a resistor R1, a switch K3 and a switch K2 which are sequentially connected in series; the negative electrode of the high-voltage battery is connected to a loop between the switches K3 and K2 after passing through the resistor R2 and the switch K4 which are connected in series in sequence;
The positive electrode of the high-voltage battery is connected with the negative electrode of the high-voltage battery after passing through a switch K1, a resistor R4, a resistor R5 and a resistor R6 which are connected in series in sequence;
The lead-out terminal between the switches K2 and K3 is connected between the resistor R4 and the resistor R5 through the switch K5 and the resistor R3.
2. The automotive high voltage insulation resistance detection system of claim 1, wherein: the detection system also comprises a calculation control unit, wherein the output end of the calculation control unit is respectively connected to the switches K1, K2, K3, K4 and K5 and is used for respectively controlling the on-off states of the switches K1, K2, K3, K4 and K5 during detection; the calculation control unit is used for collecting voltages at two ends of the resistor R6 during detection, judging the fault state of the detection system based on the collected voltages, and calculating to obtain insulation resistance data based on the voltages at two ends of the resistor R6 when the detection system is in a normal state.
3. An insulation resistance detection method based on the high-voltage insulation resistance detection system according to claim 1 or 2, characterized in that: the method comprises the following steps:
step 1, performing self-checking on a detection system, judging whether the detection system is in an abnormal state or a normal state, and if the detection system is in the normal state, entering a step 2;
step 2: the on-off control of the switches K1, K2, K3, K4 and K5 is carried out according to preset logic, the voltages at the two ends of the resistor R6 are collected, and the insulation resistance value is obtained based on the voltage calculation at the two ends of the resistor R6.
4. A method of detecting insulation resistance as defined in claim 3, wherein: in step 1, performing self-checking on the detection system, and determining that the detection system is in an abnormal state and is in a normal state includes:
the switches K1, K2, K3, K4 and K5 are controlled according to preset open-close state logic, voltages at two ends of the resistor R6 are collected during each control, and whether the detection system is abnormal is judged based on the voltages at the two ends of the resistor R6.
5. The insulation resistance detection method according to claim 4, wherein:
the preset open/close state logic includes:
(1) The control switches K1, K2, K3, K4 and K5 are kept off;
(2) Closing the switch K1, and controlling the switches K2, K3, K4 and K5 to be kept open;
(3) Closing the switch K2, and controlling the switches K1, K3, K4 and K5 to be kept open;
(4) Closing the switch K3 and K5; the control switches K1, K2 and K4 are kept off;
(5) Closing the switches K1, K4 and K5; the control switches K2, K3 remain open.
6. The insulation resistance detection method according to claim 4, wherein: in the open-close state logic (1), collecting voltages at two ends of a resistor R6, judging whether the collected voltages are 0, and if not, judging that a loop of the detection system is abnormal;
In the open-close state logic (2), collecting voltages at two ends of a resistor R6, judging whether the difference between the collected voltage and a theoretical voltage U62 exceeds a threshold value, and if yes, judging that a loop of the detection system is abnormal;
In the open-close state logic (3), collecting voltages at two ends of a resistor R6, judging whether the collected voltages are 0, and if not, judging that a loop of the detection system is abnormal;
in the open-close state logic (4), collecting voltages at two ends of a resistor R6, judging whether the difference between the collected voltage and a theoretical voltage U64 exceeds a threshold value, and if yes, judging that a loop of the detection system is abnormal;
in the open-close state logic (5), collecting voltages at two ends of a resistor R6, judging whether the difference between the collected voltage and a theoretical voltage U65 exceeds a threshold value, and if yes, judging that a loop of the detection system is abnormal;
and if the detection system loop is not judged to be abnormal under all the open-close state logics, judging that the detection system is normal.
7. The insulation resistance detection method according to claim 6, wherein:
The theoretical voltages are respectively:
Wherein R1, R2, R3, R4, R5 and R6 are respectively resistance values; vbat is the terminal voltage of the battery.
8. An insulation resistance detection method according to any one of claims 3 to 7, wherein: the step2 comprises the following steps:
Step 21: closing the switch K1, and keeping the switches K2, K3, K4 and K5 open; at the moment, the voltage U6 at two ends of the sampling resistor R6 is read and the terminal voltage value Vbat of the battery is obtained through calculation;
Step 22: k1, K3 and K4 are opened, K2 and K5 are closed, and the voltage U6' at the two ends of the sampling resistor R6 is read at the moment;
Step 23: closing K1, K2 and K5, and opening K3 and K4, wherein the voltages U6' at two ends of the sampling resistor R6 are collected and read at the moment;
Step 24: based on the collected voltages U6, U6', U6 ", a positive insulation resistance value Riso + and a negative insulation resistance value Riso - are calculated according to an insulation resistance formula.
9. The insulation resistance detection method according to claim 8, wherein: the insulation resistance calculation formula includes:
The result in step 21:
The formula obtained in step 22:
The formula obtained in step 23
And (3) and (4) and (5) simultaneously solving the binary one-time equation to obtain the expressions of the positive insulation resistance value Riso + and the negative insulation resistance value Riso -.
10. The insulation resistance detection method according to claim 7, wherein:
vbat is the voltage at both ends of the battery directly acquired by the newly added acquisition circuit or the accurate voltage at both ends of the battery acquired by the vehicle BMS.
CN202410007170.6A 2024-01-03 2024-01-03 System and method for detecting high-voltage insulation resistance of automobile Pending CN117969954A (en)

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Application Number Priority Date Filing Date Title
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