1. A method for measuring insulation resistance is characterized by comprising the following steps:

s1; respectively acquiring a first maximum voltage value of a positive terminal of a battery or a whole vehicle high-voltage system relative to a ground reference end and a first minimum voltage value of a negative terminal of the battery or the whole vehicle high-voltage system relative to the ground reference end;

s2: a first constant value resistor is connected to the larger side of the first maximum voltage value and the first minimum voltage value, and a second maximum voltage value of the positive terminal relative to the ground reference end and a second minimum voltage value of the negative terminal relative to the ground reference end after the first constant value resistor is connected are collected;

s3: calculating a first insulation resistance using the first constant value resistance, the first maximum voltage value, the second maximum voltage value, the first minimum voltage value, and the second minimum voltage value;

s4: disconnecting the first fixed resistor, and respectively acquiring a third minimum voltage value of a positive terminal of the battery or the finished automobile high-voltage system relative to a ground reference end and a third maximum voltage value of a negative terminal of the battery or the finished automobile high-voltage system relative to the ground reference end;

s5: respectively collecting a second constant value resistor connected to the larger side of the third minimum voltage value and the third maximum voltage value, and collecting a fourth minimum voltage value of the positive terminal relative to the ground reference end and a fourth maximum voltage value of the negative terminal relative to the ground reference end after the second constant value resistor is connected;

s6: calculating a second insulation resistance using the second fixed resistance, the third maximum voltage value, the fourth maximum voltage value, the third minimum voltage value, and the fourth minimum voltage value;

s7: and calculating a target insulation resistance by using the first insulation resistance and the second insulation resistance to serve as the current insulation resistance of the battery or the whole vehicle high-voltage system.

2. The insulation resistance measuring method according to claim 1, wherein in the step S2, the first constant value resistor is connected between the positive electrode terminal and the ground reference terminal, the first insulation resistance is calculated by the following equation,

the R is₁As the first insulation resistance, the MaxU₁For the first maximum voltage value, the MinU₂For the first minimum voltage value, the MinU₂' is the second minimum voltage value, the MaxU₁' is the second maximum voltage value, the R₀₁Is the first constant value resistor.

3. The insulation resistance measuring method according to claim 1, wherein in the step S5, the second constant resistance is connected between the negative terminal and the ground reference terminal, and the second insulation resistance is calculated by the following equation:

the R is₂As the second insulation resistance, the MaxU₂For the third maximum voltage value, the MinU₁For the third minimum voltage value, the MinU₁' is the fourth minimum voltage value, the MaxU₂' is the fourth maximum voltage value,the R is₀₂The second constant value resistance is obtained.

4. The insulation resistance measuring method according to any one of claims 1 to 3, wherein a minimum value of the first insulation resistance and the second insulation resistance is taken as the target insulation resistance.

5. A method of measuring insulation resistance according to any one of claims 1 to 3, wherein the first constant resistance and the second constant resistance are equal to each other within an error allowance range.

6. An insulation resistance measuring circuit, used in the insulation resistance measuring method according to any one of claims 1 to 5, comprising:

the red meter pen of the first universal meter is connected with the positive terminal of the battery or the high-voltage system of the whole vehicle, and the black meter pen of the first universal meter is connected with the ground reference end of the battery or the high-voltage system of the whole vehicle;

the red meter pen of the second multimeter is connected with the ground reference end, and the black meter pen of the second multimeter is connected with the battery or the negative terminal of the high-voltage system of the whole vehicle;

the first constant resistor is connected between the positive terminal and the ground reference end or between the negative terminal and the ground reference end;

a second fixed resistor coupled between the positive terminal and the ground reference terminal or between the negative terminal and the ground reference terminal.

7. The insulation resistance measuring circuit according to claim 6, wherein the first multimeter measuring the voltage between the positive terminal of the battery or the entire vehicle high voltage system and the ground reference comprises:

measuring a first maximum voltage value and a second maximum voltage value between the positive terminal and the ground reference terminal by using a proper measuring range of the first multimeter;

measuring a third minimum voltage value and a fourth minimum voltage value between the negative terminal and the ground reference using an appropriate range of the first multimeter.

8. The insulation resistance measuring circuit of claim 6, wherein said second multimeter measuring a voltage between a negative terminal of said battery or said entire vehicle high voltage system and said ground reference comprises:

measuring a third maximum voltage value and a fourth maximum voltage value between the negative terminal and the ground reference terminal with a suitable range of the second multimeter;

and measuring a first minimum voltage value and a second minimum voltage value between the positive terminal and the ground reference terminal by using a proper measuring range of the second multimeter.

9. A power cell, comprising: the power storage battery pack further comprises: an insulation resistance measuring circuit according to any one of claims 6 to 8;

a red meter pen of a first universal meter in the insulation resistance measuring circuit is connected with a positive terminal of the power storage battery pack, and a black meter pen of the first universal meter is connected with a ground reference end of the power storage battery pack;

and a red meter pen of a second multimeter in the insulation resistance measuring circuit is connected with the ground reference end, and a black meter pen of the second multimeter is connected with the negative terminal of the power storage battery.

10. A vehicle finishing high voltage system comprising the power cell of claim 9.

11. An electric vehicle, comprising: the power cell of claim 9.

Background

In recent years, electric vehicles such as pure electric vehicles and hybrid vehicles powered by a power storage battery pack have become popular because of the problems of environmental deterioration caused by an increase in fuel cost and an excessive emission of the vehicle. Meanwhile, the safety index of the electric automobile depends on the insulation degree of the power storage battery pack. The insulation degree of the power storage battery pack can be determined by measuring the resistance value of the insulation resistance of the battery, therefore, how to measure the resistance value of the insulation resistance of the battery by adopting a high-precision measurement method to judge the insulation degree of the power storage battery pack and ensure the reliability and safety of the electric automobile is a technical problem to be solved by technical personnel in the field, in various tests and safety standard verification at present, the traditional method is to manually detect the insulation resistance by a national standard method, at the moment, the constant value resistance continuously connected into an insulation monitoring system in the whole automobile can seriously influence the detection of the insulation resistance to cause low detection precision of the insulation resistance, so the insulation monitoring system in the automobile needs to be shielded or closed when the insulation monitoring system in the automobile is shielded by using the national standard method, if the shielding performance is poor, the detection precision of the insulation resistance is also caused to be low, if the internal insulation monitoring system of the vehicle is closed, the detection steps of the insulation resistance are complicated, and the detection efficiency is low.

Disclosure of Invention

The invention aims to solve the problem that the reliability and safety of an electric automobile are influenced because the insulation degree of a storage battery power pack cannot be accurately judged due to low detection precision and detection efficiency of insulation resistance in the prior art. Therefore, the invention provides the battery insulation resistance measuring method, the circuit, the power battery and the electric automobile, which can accurately measure the resistance value of the battery insulation resistance, do not need to close or shield an insulation monitoring system in the automobile, have higher detection precision and detection efficiency, and can accurately judge the insulation degree of the power battery pack, thereby ensuring the reliability and safety of the electric automobile.

In order to solve the above problem, an embodiment of the present invention discloses a method for measuring insulation resistance, including:

s1; respectively acquiring a first maximum voltage value of a positive terminal of a battery or a whole vehicle high-voltage system relative to a ground reference end and a first minimum voltage value of a negative terminal of the battery or the whole vehicle high-voltage system relative to the ground reference end;

s2: a first constant value resistor is connected to the larger side of the first maximum voltage value and the first minimum voltage value, and a second maximum voltage value of the positive terminal relative to the ground reference end and a second minimum voltage value of the negative terminal relative to the ground reference end after the first constant value resistor is connected are collected;

s3: calculating a first insulation resistance using the first constant value resistance, the first maximum voltage value, the second maximum voltage value, the first minimum voltage value, and the second minimum voltage value;

s4: disconnecting the first fixed resistor, and respectively acquiring a third minimum voltage value of a positive terminal of the battery or the finished automobile high-voltage system relative to a ground reference end and a third maximum voltage value of a negative terminal of the battery or the finished automobile high-voltage system relative to the ground reference end;

s5: respectively collecting a second constant value resistor connected to the larger side of the third minimum voltage value and the third maximum voltage value, and collecting a fourth minimum voltage value of the positive terminal relative to the ground reference end and a fourth maximum voltage value of the negative terminal relative to the ground reference end after the second constant value resistor is connected;

s6: calculating a second insulation resistance using the second fixed resistance, the third maximum voltage value, the fourth maximum voltage value, the third minimum voltage value, and the fourth minimum voltage value;

s7: and calculating a target insulation resistance by using the first insulation resistance and the second insulation resistance to serve as the current insulation resistance of the battery or the whole vehicle high-voltage system.

By adopting the technical scheme, the first maximum voltage, the second maximum voltage, the third minimum voltage and the fourth minimum voltage of the positive terminal and the ground reference end of the battery or the whole vehicle high-voltage system, which are accessed to the first fixed-value resistor and are not accessed to the first fixed-value resistor, and the third maximum voltage value, the fourth maximum voltage value, the first minimum voltage value and the second minimum voltage value of the negative terminal and the ground reference end of the battery or the whole vehicle high-voltage system, which are accessed to the second fixed-value resistor and are not accessed to the second fixed-value resistor can be respectively collected. The first insulation resistance and the second insulation resistance are calculated by using the measured voltage values, and a target insulation resistance value is calculated therefrom as an insulation resistance for evaluating the insulation performance of the battery. On one hand, the technical scheme of the invention can judge the insulation performance of the battery through the calculated insulation resistance, and on the other hand, as the two insulation resistances are calculated and the target insulation resistance is selected by combining the two insulation resistances, the higher the precision of the calculated insulation resistance is, the higher the precision of judging the insulation performance of the battery is, and the reliability and the safety of the electric automobile are ensured.

Further, as an alternative embodiment of the present invention, in the step S2, the first constant value resistor is connected between the positive terminal and the ground reference terminal, the first insulation resistor is calculated by the following formula,

the R is₁As the first insulation resistance, the MaxU₁For the first maximum voltage value, the MinU₂For the first minimum voltage value, the MinU₂' is the second minimum voltage value, the MaxU₁' is the second maximum voltage value, the R₀₁Is the first constant value resistor.

Further, as an alternative embodiment of the present invention, in step S5, the second constant resistance is connected between the negative terminal and the ground reference terminal, and the second insulation resistance is calculated by the following formula:

the R is₂As the second insulation resistance, the MaxU₂Is the third voltage maximum, the MinU₁For the third minimum voltage value, the MinU₁' is the fourth minimum voltage value, the MaxU₂' is the fourth voltage maximum, the R₀₂The second constant value resistance is obtained.

Further, as an alternative embodiment of the present invention, a minimum value of the first insulation resistance and the second insulation resistance is taken as the target insulation resistance.

Further, as an alternative embodiment of the present invention, the first fixed resistor and the second fixed resistor are equal to each other within an error tolerance range.

Further, an embodiment of the present invention discloses a measurement circuit of insulation resistance, which is used in any one of the above measurement methods of insulation resistance, and the measurement circuit includes:

the red meter pen of the first universal meter is connected with the positive terminal of the battery or the high-voltage system of the whole vehicle, and the black meter pen of the first universal meter is connected with the ground reference end of the battery or the high-voltage system of the whole vehicle;

the red meter pen of the second multimeter is connected with the ground reference end, and the black meter pen of the second multimeter is connected with the battery or the negative terminal of the high-voltage system of the whole vehicle;

the first constant resistor is connected between the positive terminal and the ground reference end or between the negative terminal and the ground reference end;

a second fixed resistor coupled between the positive terminal and the ground reference terminal or between the negative terminal and the ground reference terminal.

Further, as an optional embodiment of the present invention, the measuring, by the first universal meter, the voltage between the positive terminal of the battery or the entire vehicle high voltage system and the ground reference terminal includes:

measuring a first maximum voltage value and a second maximum voltage value between the positive terminal and the ground reference terminal by using a proper measuring range of the first multimeter;

measuring a third minimum voltage value and a fourth minimum voltage value between the negative terminal and the ground reference using an appropriate range of the first multimeter.

Further, as an optional embodiment of the present invention, the measuring, by the second multimeter, the voltage between the negative terminal of the battery or the entire vehicle high voltage system and the ground reference terminal includes:

measuring a third maximum voltage value and a fourth maximum voltage value between the negative terminal and the ground reference terminal with a suitable range of the second multimeter;

and measuring a first minimum voltage value and a second minimum voltage value between the positive terminal and the ground reference terminal by using a proper measuring range of the second multimeter.

Further, the embodiment of the invention discloses a power battery, which comprises: the power storage battery pack further comprises: a measurement circuit of insulation resistance as described in any of the above;

a red meter pen of a first universal meter in the insulation resistance measuring circuit is connected with a positive terminal of the power storage battery pack, and a black meter pen of the first universal meter is connected with a ground reference end of the power storage battery pack;

and a red meter pen of a second multimeter in the insulation resistance measuring circuit is connected with the ground reference end, and a black meter pen of the second multimeter is connected with the negative terminal of the power storage battery.

Further, an embodiment of the present invention discloses an electric vehicle, including: a power cell as described above.

Further, the embodiment of the invention discloses a whole vehicle high-voltage system which comprises the power battery.

The embodiment of the invention discloses a battery insulation resistance measuring method, a circuit, a power battery and an electric automobile, which have the following beneficial effects:

the method can be used for respectively collecting the first maximum voltage, the second maximum voltage, the third minimum voltage and the fourth minimum voltage of a positive terminal and a ground reference end of a battery or a whole vehicle high-voltage system when the positive terminal and the ground reference end are connected with a first fixed-value resistor and are not connected with the first fixed-value resistor, and the third maximum voltage value, the fourth maximum voltage value, the first minimum voltage value and the second minimum voltage value of a negative terminal and a ground reference end of the battery when the negative terminal and the ground reference end are connected with a second fixed-value resistor and are not connected with the second fixed-value resistor. The first insulation resistance and the second insulation resistance are calculated by using the measured voltage values, and a target insulation resistance value is calculated therefrom as an insulation resistance for evaluating the insulation performance of the battery. On one hand, under the condition that an insulation monitoring system in the vehicle is not required to be turned off or shielded, the insulation performance of the battery or the whole vehicle high-voltage system can be judged through the calculated insulation resistance, and on the other hand, as the two insulation resistances are calculated, the target insulation resistance is selected by combining the two insulation resistances and the insulation monitoring system in the vehicle is not required to be turned off or shielded, the calculated insulation resistance has higher precision, the detection efficiency of the insulation resistance is higher, the precision for judging the insulation performance of the battery is higher, and the reliability and the safety of the electric vehicle are ensured.

Additional features and corresponding advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1(a) is a schematic structural diagram of a measurement circuit of an insulation resistance not accessed with a first constant value resistance according to an embodiment of the present invention;

fig. 1(b) is a schematic structural diagram of a measurement circuit of an insulation resistance connected to a first constant value resistor according to an embodiment of the present invention;

fig. 1(c) is a schematic structural diagram of a measurement circuit of an insulation resistance not accessed to a second constant value resistor according to an embodiment of the present invention;

fig. 1(d) is a schematic structural diagram of a measurement circuit of an insulation resistance connected to a second constant value resistor according to an embodiment of the present invention;

fig. 1(e) is a schematic structural diagram of a measurement circuit of insulation resistance according to an embodiment of the present invention;

fig. 2 is a schematic flow chart of a method for measuring insulation resistance according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure. While the invention will be described in conjunction with the preferred embodiments, it is not intended that features of the invention be limited to these embodiments. On the contrary, the invention is described in connection with the embodiments for the purpose of covering alternatives or modifications that may be extended based on the claims of the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be practiced without these particulars. Moreover, some of the specific details have been left out of the description in order to avoid obscuring or obscuring the focus of the present invention. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

It should be noted that in this specification, like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

An insulation resistance measuring method, circuit, power battery, vehicle high-voltage system and electric vehicle disclosed in the embodiments of the present invention are described below with reference to fig. 1(a), fig. 1(b), fig. 1(c), fig. 1(d) and fig. 2, where fig. 1(a) is a schematic structural diagram of a measuring circuit of an insulation resistance not accessed to a first constant resistance disclosed in the embodiments of the present invention, fig. 1(b) is a schematic structural diagram of a measuring circuit of an insulation resistance accessed to a first constant resistance disclosed in the embodiments of the present invention, fig. 1(c) is a schematic structural diagram of a measuring circuit of an insulation resistance not accessed to a second constant resistance disclosed in the embodiments of the present invention, fig. 1(d) is a schematic structural diagram of a measuring circuit of an insulation resistance accessed to a second constant resistance disclosed in the embodiments of the present invention, and fig. 1(e) is a schematic structural diagram of a measuring circuit of an insulation resistance disclosed in the embodiments of the present invention, fig. 2 is a schematic flow chart of a method for measuring insulation resistance according to an embodiment of the present invention.

It should be noted that, for a finished vehicle high-voltage system, the finished vehicle high-voltage system includes a battery, and the battery provides high voltage for the finished vehicle, so when the insulation performance test is performed on the battery or the finished vehicle high-voltage system, the detection methods are consistent, that is, a voltage output end of the finished vehicle high-voltage system is an anode terminal, an anode of the battery is a cathode terminal, a cathode of the finished vehicle high-voltage system is a cathode terminal, and a cathode of the battery is a cathode terminal.

The embodiment of the invention realizes the following scheme for detecting the insulation resistance of the vehicle by a national standard method when a measurement circuit utilizing the insulation resistance works normally:

as shown in fig. 1(e), two identical multimeters (a first multimeter and a second multimeter) simultaneously measure the U1 value on both sides of the resistor R1 and the U2 value on both sides of the resistor R2, where U1 is the voltage of the positive terminal to the low voltage ground (ground reference terminal) and U2 is the voltage of the negative terminal to the low voltage ground (ground reference terminal);

adjusting the meter pen contacts of the first universal meter and the second universal meter to enable the readings of the meter pen contacts to be positive values, namely, a red meter pen of the first universal meter for measuring U1 is connected with a positive terminal, a black meter pen is connected with a low-voltage ground (a ground reference terminal), and a red meter pen of the second universal meter for measuring U2 is connected with a low-voltage ground (a ground reference terminal) and a black meter pen is connected with a negative terminal;

due to the interference of an insulation monitoring system in the vehicle, the U1 value and the U2 value fluctuate regularly, but the sum of the values at any moment is basically consistent with the voltage Ub at two ends of the battery, and the Ub is the voltage between the high-voltage positive and negative buses of the battery.

The multimeter is adjusted to the appropriate fixed range and the measurement process is then performed as in fig. 1(a) to 1 (d).

As shown in fig. 1(a), the circuit for measuring the insulation resistance to which the first constant value resistance is not connected includes: in the first universal meter 10, the red pen of the first universal meter 10 is connected to the positive terminal of the battery 20, and the black pen of the first universal meter 10 is connected to the ground reference terminal of the battery 20.

And a red meter pen of the second multimeter 30 is connected with the ground reference end, and a black meter pen of the second multimeter 30 is connected with the negative terminal of the battery.

Specifically, MaxU₁Showing a first maximum voltage value, MinU, of the positive terminal of the battery relative to the ground reference terminal₂A first minimum voltage value of the negative terminal of the battery relative to the ground reference is indicated.

As shown in fig. 1(b), the circuit for measuring the insulation resistance connected to the first constant value resistance includes: in the first universal meter 10, the red pen of the first universal meter 10 is connected to the positive terminal of the battery 20, and the black pen of the first universal meter 10 is connected to the ground reference terminal of the battery 20.

And a red meter pen of the second multimeter 30 is connected with the ground reference end, and a black meter pen of the second multimeter 30 is connected with the negative terminal of the battery.

And a first constant resistor 40, wherein the first constant resistor 40 is connected between the positive terminal and the ground reference terminal or between the negative terminal and the ground reference terminal.

Specifically, MaxU₁' denotes a second maximum voltage value, MinU, of the positive terminal connected between the positive terminal and the ground reference terminal with respect to the ground reference terminal₂' denotes a second minimum voltage value of the negative terminal with respect to the ground reference.

As shown in fig. 1(c), the circuit for measuring the insulation resistance not connected to the second constant value resistor includes: in the first universal meter 10, the red pen of the first universal meter 10 is connected to the positive terminal of the battery 20, and the black pen of the first universal meter 10 is connected to the ground reference terminal of the battery 20.

And a red meter pen of the second multimeter 30 is connected with the ground reference end, and a black meter pen of the second multimeter 30 is connected with the negative terminal of the battery.

Specifically, MinU₁Showing a third minimum voltage value, MaxU, of the positive terminal of the battery with respect to the ground reference terminal when the first constant resistance is turned off and the second constant resistance is not accessed₂A third maximum voltage value of the negative terminal of the battery relative to the ground reference is indicated.

As shown in fig. 1(d), the measurement circuit of the insulation resistance connected to the second constant value resistor includes: in the first universal meter 10, the red pen of the first universal meter 10 is connected to the positive terminal of the battery 20, and the black pen of the first universal meter 10 is connected to the ground reference terminal of the battery 20.

And a red meter pen of the second multimeter 30 is connected with the ground reference end, and a black meter pen of the second multimeter 30 is connected with the negative terminal of the battery.

And the second fixed-value resistor 50 is connected between the positive terminal and the ground reference end or between the negative terminal and the ground reference end.

Specifically, MinU₁' the expression is a fourth minimum voltage value, MaxU, of the positive terminal relative to the ground reference terminal after the negative terminal and the ground reference terminal are connected into the second constant value resistor₂' denotes a fourth maximum voltage value of the negative terminal with respect to the ground reference.

Specifically, as an alternative embodiment of the present invention, the measuring the voltage between the positive terminal of the battery and the ground reference terminal by the first universal meter 10 includes:

the first and second maximum voltage values between the positive terminal and the ground reference terminal are measured using the maximum span of the first universal meter 10.

The third and fourth minimum voltage values between the negative terminal and the ground reference terminal are measured using the minimum range of the first universal meter 10.

Specifically, as an alternative embodiment of the present invention, measuring the voltage between the negative terminal of the battery and the ground reference terminal by second multimeter 30 comprises:

third and fourth maximum voltage values between the negative terminal and the ground reference are measured using the maximum range of second multimeter 30.

A first minimum voltage value and a second minimum voltage value between the positive terminal and the ground reference terminal are measured using a minimum measurement range of second multimeter 30.

As shown in fig. 2, the insulation resistance measuring method includes:

s1: respectively collecting a first maximum voltage value of a positive terminal of the battery or the whole vehicle high-voltage system relative to a ground reference end and a first minimum voltage value of a negative terminal of the battery or the whole vehicle high-voltage system relative to the ground reference end.

S2: and connecting a first constant value resistor at the larger side of the first maximum voltage value and the first minimum voltage value, and acquiring a second maximum voltage value of the positive terminal relative to the ground reference end and a second minimum voltage value of the negative terminal relative to the ground reference end after the first constant value resistor is connected.

S3: and calculating a first insulation resistance by using the first constant value resistance, the first maximum voltage value, the second maximum voltage value, the first minimum voltage value and the second minimum voltage value.

S4: and disconnecting the first fixed value resistor, and respectively acquiring a third minimum voltage value of the positive terminal of the battery or the whole vehicle high-voltage system relative to the ground reference end and a third maximum voltage value of the negative terminal of the battery or the whole vehicle high-voltage system relative to the ground reference end.

S5: and respectively acquiring a second constant value resistor connected to the larger side of the third minimum voltage value and the third maximum voltage value, and acquiring a fourth minimum voltage value of the positive terminal relative to the ground reference terminal and a fourth maximum voltage value of the negative terminal relative to the ground reference terminal after the second constant value resistor is connected.

S6: and calculating a second insulation resistance by using the second constant value resistance, the third maximum voltage value, the fourth maximum voltage value, the third minimum voltage value and the fourth minimum voltage value.

S7: and calculating a target insulation resistance by using the first insulation resistance and the second insulation resistance to serve as the current insulation resistance of the battery or the high-voltage system of the whole vehicle.

Specifically, as an alternative embodiment of the present invention, in S2, the first constant resistor is connected between the positive terminal and the ground reference terminal, and the first insulation resistor is calculated by using the following formula:

R₁as a first insulation resistance, MaxU₁Is the first maximum voltage value, MinU₂Is the first minimum voltage value, MinU₂' is the second minimum voltage value, MaxU₁' is the second maximum voltage value, R₀₁Is a first constant value resistor.

Specifically, as an alternative embodiment of the present invention, in step S5, a second constant resistance is connected between the negative terminal and the ground reference terminal, and the second insulation resistance is calculated by the following formula:

R₂as a second insulation resistance, MaxU₂Is the third voltage maximum, MinU₁Is the third minimum voltage value, MinU₁' is the fourth minimum voltage value, MaxU₂' is the fourth voltage maximum, R₀₂Is a second constant value resistor.

Specifically, as an alternative embodiment of the present invention, for the selection of the target insulation resistance, but not limited to, the minimum value of the first insulation resistance and the second insulation resistance may be selected as the target insulation resistance.

Specifically, as an alternative embodiment of the present invention, the first fixed resistance and the second fixed resistance are equal.

It should be noted that, the first insulation resistance and the second insulation resistance, in which the first fixed-value resistance is connected between the negative terminal and the ground reference terminal, and the second fixed-value resistance is connected between the positive terminal and the ground reference terminal, may be calculated by inference according to the above formula, and the embodiments of the present invention are not described herein again.

In addition, the embodiment of the invention discloses a power battery, which comprises: the power storage battery pack further comprises a measurement circuit of the insulation resistance as mentioned in any one of the above.

A red meter pen of a first universal meter in the insulation resistance measuring circuit is connected with a positive terminal of the power storage battery pack, and a black meter pen of the first universal meter is connected with a ground reference end of the power storage battery pack.

A red meter pen of a second multimeter in the insulation resistance measuring circuit is connected with the ground reference end, and a black meter pen of the second multimeter is connected with the negative terminal of the power storage battery.

In addition, the embodiment of the invention discloses an electric automobile which comprises the power battery.

The embodiment of the invention discloses a battery insulation resistance measuring method, a circuit, a power battery and an electric automobile, which have the following beneficial effects:

the method can be used for respectively collecting the first maximum voltage, the second maximum voltage, the third minimum voltage and the fourth minimum voltage of a positive terminal and a ground reference end of a battery or a whole vehicle high-voltage system when the positive terminal and the ground reference end are connected with a first fixed-value resistor and are not connected with the first fixed-value resistor, and the third maximum voltage value, the fourth maximum voltage value, the first minimum voltage value and the second minimum voltage value of a negative terminal and a ground reference end of the battery when the negative terminal and the ground reference end are connected with a second fixed-value resistor and are not connected with the second fixed-value resistor. The first insulation resistance and the second insulation resistance are calculated by using the measured voltage values, and a target insulation resistance value is calculated therefrom as an insulation resistance for evaluating the insulation performance of the battery. On one hand, under the condition that an insulation monitoring system in the vehicle is not required to be turned off or shielded, the insulation performance of the battery or the whole vehicle high-voltage system can be judged through the calculated insulation resistance, and on the other hand, as the two insulation resistances are calculated, the target insulation resistance is selected by combining the two insulation resistances and the insulation monitoring system in the vehicle is not required to be turned off or shielded, the calculated insulation resistance has higher precision, the detection efficiency of the insulation resistance is higher, the precision for judging the insulation performance of the battery is higher, and the reliability and the safety of the electric vehicle are ensured.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.