Insulation resistance detection circuit of new energy automobile

Abstract

The utility model discloses a new energy automobile insulation resistance detection circuit, which relates to the technical field of new energy automobiles and comprises a positive insulation resistor Rx and a negative insulation resistor Ry, one end of the positive insulation resistor Rx is electrically connected with a battery pack BAT, one end of the negative insulation resistor Ry is electrically connected with the battery pack BAT, and the other ends of the positive insulation resistor Rx and the negative insulation resistor Ry are short-circuited and grounded. One end of the positive insulation resistor Rx is electrically connected with a switch S1, the switch S1 is electrically connected with a first on-off resistance circuit, a resistor R3 and a resistor R5, and the resistor R5 is electrically connected with a resistor R7 and a first acquisition module; one end of the negative insulation resistor Ry is electrically connected with a switch S2, and the switch S2 is electrically connected with a second on-off resistance circuit, a resistor R4 and a second acquisition module at the same time; and the first on-off resistance circuit, the resistor R3, the resistor R7, the first acquisition module, the second on-off resistance circuit, the resistor R4 and the second acquisition module are grounded. The resistance value of the insulation resistor calculated by the device is accurate.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy vehicles, in particular to an insulation resistance detection circuit for new energy vehicles. Background Art

[0002] In automotive systems, the vehicle can be simply divided into a high-voltage component, a low-voltage component, and a body ground (physical ground). High-voltage components primarily include the battery, charging and discharging circuits, and high-voltage monitoring. Low-voltage components primarily include the low-voltage power supply, CPU circuits, and communication control circuits. The body ground is generally the vehicle's exterior. The module's metal housing and the upper and lower housings of the battery pack are also connected to the body ground. Passengers also come into direct contact with the vehicle body. For personal safety, a certain level of insulation is required between the high-voltage component and the body ground to prevent high-voltage circuits from creating leakage paths to the body ground, potentially endangering personal safety.

[0003] Currently, the main methods for testing the insulation resistance of new energy electric vehicles include AC injection, current sensing, balanced bridge, and unbalanced bridge. Each of these methods has its own drawbacks: the AC injection method cannot determine which pole is faulty and is relatively expensive; the current sensing method is costly and cannot calculate insulation resistance when both poles have insulation faults or when the insulation resistance decreases proportionally; the balanced bridge method cannot identify faults when the insulation resistance between both electrodes and ground decreases; and the unbalanced bridge method, during actual testing, can cause inaccurate insulation resistance calculations if the voltage on both sides of the insulation resistance changes.

[0004] It can be seen that the technical problems existing in the above-mentioned detection methods are mainly the following:

[0005] 1. Unable to determine which pole has a fault;

[0006] Second, the cost is high;

[0007] 3. The insulation resistance value is calculated inaccurately. Utility Model Content

[0008] In view of the above defects, the purpose of this utility model is to provide a new energy vehicle insulation resistance detection circuit, which can accurately calculate the insulation resistance value and determine which pole has a fault, and has low cost.

[0009] In order to achieve the above purpose, the technical solution of the utility model is:

[0010] A new energy vehicle insulation resistance detection circuit includes a positive electrode insulation resistor Rx electrically connected to a battery pack BAT at one end and a negative electrode insulation resistor Ry electrically connected to the battery pack BAT at one end, the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry having their other ends short-circuited and grounded; one end of the positive electrode insulation resistor Rx is electrically connected to a switch S1, which is simultaneously electrically connected to a first switchable resistance circuit, a resistor R3, and a resistor R5, and the resistor R5 is simultaneously electrically connected to a resistor R7 and a first acquisition module; one end of the negative electrode insulation resistor Ry is electrically connected to a switch S2, which is simultaneously electrically connected to a second switchable resistance circuit, a resistor R4, and a second acquisition module; the first switchable resistance circuit, the resistor R3, the resistor R7, the first acquisition module, the second switchable resistance circuit, the resistor R4, and the second acquisition module are all grounded; and the first acquisition module and the second acquisition module are both electrically connected to a processing module.

[0011] The first switchable resistance circuit includes a resistor R1 electrically connected to the switch S1 , the resistor R1 is electrically connected to a switch S3 , and the switch S3 is grounded.

[0012] The second switchable resistance circuit includes a resistor R2 electrically connected to the switch S2, the resistor R2 is electrically connected to a switch S4, and the switch S4 is grounded.

[0013] The resistance values ​​of the resistor R2 and the resistor R3 are equal.

[0014] The positive electrode insulation resistance Rx is the equivalent resistance between the positive electrode of the power battery and the ground terminal, and the negative electrode insulation resistance Ry is the equivalent resistance between the negative electrode of the power battery and the ground terminal.

[0015] Wherein, the first acquisition module and the second acquisition module are both voltage acquisition modules.

[0016] Wherein, the processing module includes a single chip microcomputer and its peripheral circuits.

[0017] Wherein, the peripheral circuit of the single chip microcomputer includes an alarm circuit.

[0018] After adopting the above technical solution, the beneficial effects of the utility model are:

[0019] Since the insulation resistance detection circuit of the new energy vehicle of the present invention includes a positive insulation resistor Rx with one end electrically connected to the battery pack BAT and a negative insulation resistor Ry with one end electrically connected to the battery pack BAT, the other ends of the positive insulation resistor Rx and the negative insulation resistor Ry are short-circuited and grounded; one end of the positive insulation resistor Rx is electrically connected to the switch S1, and the switch S1 is also electrically connected to the first switchable resistance circuit, the resistor R3 and the resistor R5, and the resistor R5 is also electrically connected to the resistor R7 and the first acquisition module; one end of the negative insulation resistor Ry is electrically connected to the switch S2, and the switch S2 is also electrically connected to the second switchable resistance circuit, the resistor R4 and the second acquisition module; the first switchable resistance circuit, the resistor R3, the resistor R7, the first acquisition module, the second switchable resistance circuit, the resistor R4 and the second acquisition module are all grounded; the first acquisition module and the second acquisition module are both electrically connected to the processing module. The utility model detects the voltage across the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry, and when performing the detection, the on / off of the switch S1, the switch S2, the first switchable resistance circuit and the second switchable resistance circuit can be adjusted according to the voltage change across the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry. Thus, the resistance values ​​of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry can be accurately calculated without being affected by the voltage change across the insulation resistor, and thus which pole has a fault can be accurately determined with low cost.

[0020] In summary, the insulation resistance detection circuit of the new energy vehicle of the present invention solves the technical problems such as the inaccuracy of the insulation resistance value calculation of the new energy vehicle in the prior art. The insulation resistance detection circuit of the new energy vehicle of the present invention can accurately calculate the insulation resistance value and can determine which pole has a fault, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the principle diagram of the insulation resistance detection circuit of the utility model new energy vehicle;

[0022] Figure 2 This is the principle diagram of the first detection condition of the insulation resistance detection circuit of the utility model for new energy vehicles;

[0023] Figure 3 This is the principle diagram of the second detection condition of the insulation resistance detection circuit of the new energy vehicle of the utility model;

[0024] Figure 4 This is the principle diagram of the third detection condition of the insulation resistance detection circuit of the new energy vehicle of the utility model. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] The directions mentioned in this specification are based on the directions shown in the drawings and only represent relative positions, not absolute positions.

[0027] like Figure 1 As shown, an insulation resistance detection circuit for a new energy vehicle includes a positive electrode insulation resistor Rx electrically connected to the battery pack BAT at one end, and a negative electrode insulation resistor Ry electrically connected to the battery pack BAT at one end. The other ends of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry are short-circuited and grounded. One end of the positive electrode insulation resistor Rx is electrically connected to a switch S1, which is also electrically connected to a first switchable resistor circuit, resistor R3, and resistor R5. Resistor R5 is also electrically connected to resistor R7 and a first acquisition module. One end of the negative electrode insulation resistor Ry is electrically connected to a switch S2, which is also electrically connected to a second switchable resistor circuit, resistor R4, and a second acquisition module. The first switchable resistor circuit, resistor R3, resistor R7, the first acquisition module, the second switchable resistor circuit, resistor R4, and the second acquisition module are all grounded. The first and second acquisition modules are both electrically connected to a processing module.

[0028] like Figure 1 As shown, the first switchable resistor circuit includes a resistor R1 electrically connected to a switch S1, which is electrically connected to a switch S3, which is grounded. The second switchable resistor circuit includes a resistor R2 electrically connected to a switch S2, which is electrically connected to a switch S4, which is grounded.

[0029] like Figure 1 As shown, in this embodiment, resistors R1, R2, R3, R4, R5, and R7 are resistors of known resistance, and preferably, the resistance of resistor R2 is equal to that of resistor R3. It should be noted that the resistance values ​​of resistors R1, R2, R3, R4, R5, and R7 are related to the actual battery pack voltage and current, and the maximum voltage that the resistors themselves can divide must also be considered. Therefore, the specific resistance values ​​of resistors R1, R2, R3, R4, R5, and R7 are not limited in this example, and those skilled in the art can select them according to actual conditions. In this embodiment, the positive electrode insulation resistance Rx is the equivalent resistance between the positive electrode of the power battery and the ground terminal, and the negative electrode insulation resistance Ry is the equivalent resistance between the negative electrode of the power battery and the ground terminal.

[0030] like Figure 1 As shown, in this embodiment, both the first and second acquisition modules are voltage acquisition modules. The processing module includes a single-chip microcontroller and its peripheral circuits, which include an alarm circuit. Because both the first and second acquisition modules are conventional voltage acquisition modules, the specific circuitry and usage of the acquisition modules will not be detailed here. The single-chip microcontroller and its peripheral circuits are also conventional circuits and therefore will not be described in detail here.

[0031] like Figure 1 As shown, the working process of the insulation resistance detection circuit of the utility model for new energy vehicles is as follows:

[0032] Under normal working conditions, the positive insulation resistance Rx and the negative insulation resistance Ry are very large, sufficient to protect human safety. When an insulation failure occurs, the positive insulation resistance Rx and the negative insulation resistance Ry will decrease, which may cause electric shock to the human body.

[0033] When insulation detection is not required, the switches S1 , S2 , S3 and S4 are controlled to be disconnected.

[0034] When the insulation detection instruction is received, the processing module controls the closing of switches S1 and S2 and the opening of switches S3 and S4. At this time, the circuit is equivalent to the following: Figure 2 In the circuit shown in FIG. 1 , the voltage across the resistor R3 at this moment is collected by the first collection module. The voltage across the resistor R4 at this moment is collected by the second collection module. , That is, the negative electrode voltage of the battery pack BAT , according to the voltage on both sides of the resistor R3 detected by the resistor series-parallel formula , we can get the positive voltage of the battery pack BAT at this moment, which is defined as formula 1:

[0035] ,

[0036] Thus, the total voltage of the battery pack BAT at this moment is obtained , and judge and size.

[0037] According to Kirchhoff's current theorem, the voltage relationship at this moment can be obtained, which is defined as Formula 2:

[0038] .

[0039] when When the switches S1, S2 and S3 are closed and the switch S4 is open, the circuit is equivalent to the following Figure 3 In the circuit shown in FIG. 1 , the voltage across the resistor R3 at this moment is collected by the first collection module. The voltage across the resistor R4 at this moment is collected by the second collection module. , That is, the negative electrode voltage of the battery pack BAT , according to the voltage on both sides of the resistor R3 detected by the resistor series-parallel formula , we can get the positive voltage of the battery pack BAT, which is defined as formula three:

[0040] ,

[0041] Thus, the total voltage of the battery pack BAT at this moment is obtained .

[0042] According to Kirchhoff's current theorem, the voltage relationship at this moment can be obtained, which is defined as Formula 4:

[0043] .

[0044] According to the simultaneous equations of Formula 1, Formula 2, Formula 3 and Formula 4,

[0045] ,

[0046] Substituting the known resistance values ​​into the equation, the resistance values ​​of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry can be obtained. The obtained resistance values ​​of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry are compared with the preset resistance values. If the resistance value of the positive electrode insulation resistor Rx is less than the preset resistance value, an insulation fault exists between the positive electrode of the battery pack BAT and the ground, and the fault is reported. If the resistance value of the negative electrode insulation resistor Ry is less than the preset resistance value, an insulation fault exists between the negative electrode of the battery pack BAT and the ground, and the fault is reported. If the resistance values ​​of both the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry are less than the preset resistance values, an insulation fault exists between both the positive electrode and the negative electrode of the battery pack BAT and the ground, and the fault is reported.

[0047] when When the switches S1, S2 and S4 are closed and the switch S3 is opened, the circuit becomes as follows: Figure 4 In the circuit shown, the voltage on both sides of the resistor R3 collected by the first collection module is The voltage on both sides of the resistor R4 collected by the second collection module is , That is, the negative electrode voltage of the battery pack BAT , according to the voltage on both sides of the resistor R3 detected by the resistor series-parallel formula , we can get the positive voltage of the battery pack BAT at this moment, which is defined as Formula 5:

[0048] ,

[0049] Thus, the total voltage of the battery pack BAT at this moment is obtained .

[0050] According to Kirchhoff's current theorem, the voltage relationship at this moment can be obtained, which is defined as Formula 6:

[0051] .

[0052] According to the simultaneous equations of Formula 1, Formula 2, Formula 5 and Formula 6,

[0053] ,

[0054] Substituting the known resistance values ​​into the equation, the resistance values ​​of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry can be obtained. The obtained resistance values ​​of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry are compared with the preset resistance values. If the resistance value of the positive electrode insulation resistor Rx is less than the preset resistance value, an insulation fault exists between the positive electrode of the battery pack BAT and the ground, and the fault is reported. If the resistance value of the negative electrode insulation resistor Ry is less than the preset resistance value, an insulation fault exists between the negative electrode of the battery pack BAT and the ground, and the fault is reported. If the resistance values ​​of both the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry are less than the preset resistance values, an insulation fault exists between both the positive electrode and the negative electrode of the battery pack BAT and the ground, and the fault is reported.

[0055] In summary, the insulation resistance detection circuit for new energy vehicles of the present invention is not affected by voltage changes on both sides of the resistor, accurately calculates the insulation resistance value, and can accurately determine which pole has a fault, and has low cost.

[0056] The present invention is not limited to the above-mentioned specific implementation methods. Various modifications made by ordinary technicians in this field based on the above-mentioned conception without creative work are all within the scope of protection of the present invention.

Claims

1. The insulation resistance detection circuit of new energy vehicles is characterized by: It includes a positive electrode insulation resistor Rx with one end electrically connected to the battery pack BAT and a negative electrode insulation resistor Ry with one end electrically connected to the battery pack BAT, the other ends of the positive electrode insulation resistor Rx and the negative electrode insulation resistor Ry are short-circuited and grounded; one end of the positive electrode insulation resistor Rx is electrically connected to a switch S1, and the switch S1 is also electrically connected to a first switchable resistance circuit, a resistor R3 and a resistor R5, and the resistor R5 is also electrically connected to a resistor R7 and a first acquisition module; one end of the negative electrode insulation resistor Ry is electrically connected to a switch S2, and the switch S2 is also electrically connected to a second switchable resistance circuit, a resistor R4 and a second acquisition module; the first switchable resistance circuit, the resistor R3, the resistor R7, the first acquisition module, the second switchable resistance circuit, the resistor R4 and the second acquisition module are all grounded; the first acquisition module and the second acquisition module are both electrically connected to a processing module.

2. The new energy vehicle insulation resistance detection circuit according to claim 1, characterized in that: The first switchable resistance circuit includes a resistor R1 electrically connected to the switch S1 , the resistor R1 electrically connected to a switch S3 , and the switch S3 is grounded.

3. The new energy vehicle insulation resistance detection circuit according to claim 2, characterized in that: The second switchable resistance circuit includes a resistor R2 electrically connected to the switch S2 , the resistor R2 electrically connected to a switch S4 , and the switch S4 is grounded.

4. The new energy vehicle insulation resistance detection circuit according to claim 3, characterized in that: The resistance values ​​of the resistor R2 and the resistor R3 are equal.

5. The new energy vehicle insulation resistance detection circuit according to claim 3, characterized in that: The positive electrode insulation resistance Rx is the equivalent resistance between the positive electrode of the power battery and the ground terminal, and the negative electrode insulation resistance Ry is the equivalent resistance between the negative electrode of the power battery and the ground terminal.

6. The new energy vehicle insulation resistance detection circuit according to claim 1, characterized in that: The first acquisition module and the second acquisition module are both voltage acquisition modules.

7. The new energy vehicle insulation resistance detection circuit according to claim 3, characterized in that: The processing module includes a single chip microcomputer and its peripheral circuits.

8. The new energy vehicle insulation resistance detection circuit according to claim 7, characterized in that: The peripheral circuit of the single chip microcomputer includes an alarm circuit.

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