CN117665396A

CN117665396A - Insulation resistance detection circuit, method, device and medium for power battery

Info

Publication number: CN117665396A
Application number: CN202410135900.0A
Authority: CN
Inventors: 孟祥虎; 周旋; 钱宝存; 王凯; 黄帅; 张家铭; 张东阳; 李冰
Original assignee: Xuzhou Xugong Automobile Manufacturing Co ltd
Current assignee: Xuzhou Xugong Automobile Manufacturing Co ltd
Priority date: 2024-01-31
Filing date: 2024-01-31
Publication date: 2024-03-08
Anticipated expiration: 2044-01-31
Also published as: CN117665396B

Abstract

The present disclosure provides an insulation resistance detection circuit, method, apparatus, and medium for a power battery. The circuit comprises: the measuring module comprises a first measuring resistor, a second measuring resistor and a third measuring resistor; and a resistor access module including a first access branch including a first controllable switch and a first access resistor connected in series with the first controllable switch, and a second access branch including a second controllable switch and a second access resistor connected in series with the second controllable switch, a positive electrode of the power battery being connected to a reference ground potential via the first access branch, a negative electrode of the power battery being connected to the reference ground potential via the second access branch, the first controllable switch being controlled such that the first access branch is in an on state or an off state, and the second controllable switch being controlled such that the second access branch is in an on state or an off state. The circuit can accurately calculate the resistance of the insulation resistance of the positive electrode and the negative electrode.

Description

Insulation resistance detection circuit, method, device and medium for power battery

Technical Field

The present disclosure relates to electric vehicle technology, and more particularly, to an insulation resistance detection circuit, method, apparatus, and medium for a power battery.

Background

The insulation resistor of the power battery is mainly used for avoiding a leakage loop from being formed between the high-voltage power battery and the vehicle body, protecting personal safety of passengers, and also avoiding current from directly flowing to a circuit of the vehicle, and playing a certain role in protecting the circuit of the vehicle. The insulation resistor needs to meet certain resistance requirements to realize effective protection. In actual production and use, the resistance of the insulation resistor may not meet the requirements due to factors such as design, manufacturing, short circuit, aging loss, and the like. Therefore, it is important to detect the insulation resistance of the power battery.

In the related art, two equivalent measuring resistors and positive and negative insulation resistors of a power battery are utilized to form a Huygens bridge circuit, so that the insulation resistance of the power battery is detected. The above-mentioned method cannot detect the situation that the insulation resistance of the positive electrode and the negative electrode fails in the same proportion (namely, the resistance value increases or decreases in the same proportion). Moreover, when the leakage current is large, the detection method may cause erroneous judgment of the failure of the positive and negative electrode insulation resistances.

Disclosure of Invention

In order to solve at least some of the above problems, embodiments of the present disclosure provide the following technical solutions.

According to an aspect of the present disclosure, there is provided an insulation resistance detection circuit for a power battery, the circuit including: the measuring module comprises a first measuring resistor, a second measuring resistor and a third measuring resistor, wherein the first end of the first measuring resistor and the first end of the second measuring resistor are respectively connected with the positive electrode and the negative electrode of the power battery, the second end of the first measuring resistor and the second end of the second measuring resistor are connected with the first end of the third measuring resistor, and the second end of the third measuring resistor is connected to the reference ground potential; and a resistor access module including a first access branch including a first controllable switch and a first access resistor connected in series with the first controllable switch, and a second access branch including a second controllable switch and a second access resistor connected in series with the second controllable switch, a positive electrode of the power battery being connected to the reference ground potential via the first access branch, a negative electrode of the power battery being connected to the reference ground potential via the second access branch, the first controllable switch being controlled such that the first access branch is in an on state or an off state, the second controllable switch being controlled such that the second access branch is in an on state or an off state.

In some embodiments, the circuit further comprises: the controller comprises a first signal control end, a second signal control end and a grounding end, wherein the first signal control end and the second signal control end are respectively connected to the first controllable switch and the second controllable switch so as to respectively control the first access branch and the second access branch to be in an on state or an off state, and the grounding end of the controller is connected to the reference ground potential.

In some embodiments, the first controllable switch includes a first triode, an emitter of the first triode is connected with the first access resistor, a base of the first triode is connected with the first signal control end, the second controllable switch includes a second triode, a collector of the second triode is connected with the second access resistor, and a base of the second triode is connected with the second signal control end.

In some embodiments, the first controllable switch includes a first MOS transistor, a drain of the first MOS transistor is connected to the first access resistor, a gate of the first MOS transistor is connected to the first signal control terminal, the second controllable switch includes a second MOS transistor, a source of the second MOS transistor is connected to the second access resistor, and a gate of the second MOS transistor is connected to the second signal control terminal.

In some embodiments, the circuit further comprises: a first voltage acquisition module configured to acquire a first voltage between a positive electrode of the power battery and the reference ground potential and a second voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an on state and the second access branch is in an off state; and a second voltage acquisition module configured to acquire a third voltage between a positive electrode of the power battery and the reference ground potential and a fourth voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an off state and the second access branch is in an on state.

In some embodiments, the circuit further comprises: an insulation resistance calculation module configured to calculate a resistance value of a positive insulation resistance between a positive electrode of the power battery and the reference ground potential and a negative insulation resistance between a negative electrode of the power battery and the reference ground potential from the first voltage, the second voltage, the third voltage, the fourth voltage, and resistance values of the first measurement resistance, the second measurement resistance, the third measurement resistance, the first access resistance, and the second access resistance.

In some embodiments, the circuit further comprises: and the leakage current acquisition module is configured to acquire leakage current flowing through the third measuring resistor under the condition that the first access branch and the second access branch are in a disconnected state.

In some embodiments, the circuit further comprises: and the early warning module is configured to send out early warning according to the magnitude of the leakage current.

In some embodiments, the first and second measured resistances are equal in resistance.

In some embodiments, the first access resistor and the second access resistor have equal resistance values.

According to still another aspect of the embodiments of the present disclosure, there is provided an insulation resistance detection circuit for a power battery, including: the measuring module comprises a first measuring resistor, a second measuring resistor and a third measuring resistor, wherein the first end of the first measuring resistor and the first end of the second measuring resistor are respectively connected with the positive electrode and the negative electrode of the power battery, the second end of the first measuring resistor and the second end of the second measuring resistor are connected with the first end of the third measuring resistor, and the second end of the third measuring resistor is connected to the reference ground potential; and the resistor access module comprises a selection switch and an access resistor connected in series with the selection switch, wherein a first output end of the selection switch is connected with a positive electrode of the power battery, a second output end of the selection switch is connected with a negative electrode of the power battery, a third output end of the selection switch is an off terminal, a first end of the access resistor is connected to an input end of the two-way selection switch, a second end of the access resistor is connected to the reference ground potential, and the selection switch is controlled to switch among switching on the first output end, switching on the second output end or switching on the third output end.

In some embodiments, the circuit further comprises: and a controller configured to provide a control signal to the selection switch to control the selection switch to switch between switching on the first output terminal, switching on the second output terminal, or switching on the third output terminal, a ground terminal of the controller being connected to the reference ground potential.

According to still another aspect of the embodiments of the present disclosure, there is provided an insulation resistance detection method for a power battery, which is applied to the insulation resistance detection circuit described in any one of the above embodiments, the method including: controlling the first controllable switch and the second controllable switch such that the first access leg is in an on state and the second access leg is in an off state at the same time; collecting a first voltage between a positive electrode of the power battery and the reference ground potential and a second voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an on state and the second access branch is in an off state; controlling the first controllable switch and the second controllable switch such that the first access leg is in an off state and the second access leg is in an on state at the same time; collecting a third voltage between a positive electrode of the power battery and the reference ground potential and a fourth voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an off state and the second access branch is in an on state; and calculating the resistance values of a positive electrode insulation resistance between a positive electrode of the power battery and the reference ground potential and a negative electrode insulation resistance between a negative electrode of the power battery and the reference ground potential according to the first voltage, the second voltage, the third voltage, the fourth voltage and the resistance values of the first measuring resistor, the second measuring resistor, the third measuring resistor, the first access resistor and the second access resistor.

In some embodiments, the method further comprises: and under the condition that the first access branch and the second access branch are in the disconnected state, collecting leakage current flowing through the third measuring resistor. In some embodiments, the method further comprises: and sending out an early warning in response to determining that the leakage current is a non-zero value.

In some embodiments, the method further comprises: an early warning is issued in response to determining at least one of the following conditions: the resistance value of the positive electrode insulation resistor is lower than a first threshold value; or the resistance value of the negative electrode insulation resistance is lower than a second threshold value.

According to still another aspect of the embodiments of the present disclosure, there is provided an insulation resistance detection method for a power battery, which is applied to the insulation resistance detection circuit described in any one of the above embodiments, the method including: controlling the selection switch to switch on the first output end; collecting a first voltage between a positive electrode of the power battery and the reference ground potential and a second voltage between a negative electrode of the power battery and the reference ground potential while the selection switch is connected with the first output end; controlling the selection switch to switch on the second output end; collecting a third voltage between a positive electrode of the power battery and the reference ground potential and a fourth voltage between a negative electrode of the power battery and the reference ground potential while the selection switch is connected with the second output end; and calculating the resistance values of a positive electrode insulation resistance between the positive electrode of the power battery and the reference ground potential and a negative electrode insulation resistance between the negative electrode of the power battery and the reference ground potential according to the first voltage, the second voltage, the third voltage, the fourth voltage and the resistance values of the first measuring resistor, the second measuring resistor, the third measuring resistor and the access resistor.

In some embodiments, the method further comprises: controlling the selection switch to switch on the third input end; and collecting leakage current flowing through the third measuring resistor while the selection switch is connected with the third input end.

According to still another aspect of the embodiments of the present disclosure, there is provided an insulation resistance detection apparatus for a power battery, including a module for performing the method of any one of the embodiments described above.

According to still another aspect of the embodiments of the present disclosure, there is provided an insulation resistance detection apparatus for a power battery, including: a memory; and a processor coupled to the memory, the processor configured to perform the method of any of the embodiments described above based on instructions stored in the memory.

According to a further aspect of the disclosed embodiments, a computer readable storage medium is provided, comprising computer program instructions, wherein the computer program instructions, when executed by a processor, implement the method according to any of the embodiments described above.

According to a further aspect of the disclosed embodiments, a computer program product is provided, comprising a computer program, wherein the computer program, when executed by a processor, implements the method according to any of the above embodiments.

In the embodiment of the disclosure, in a measurement module formed by a plurality of measurement resistors and positive and negative insulation resistors, the balance of a bridge is destroyed by respectively connecting the parallel connection access resistors to the two ends of the positive insulation resistor and the negative insulation resistor, so that the resistance values of the positive insulation resistor and the negative insulation resistor are calculated according to the resistance values of the measurement resistors and the voltages of the positive electrode and the negative electrode of the power battery to the ground. The method can accurately calculate the resistance values of the positive and negative electrode insulation resistors, so that whether the resistance values of the positive and negative electrode insulation resistors meet the safety requirement is judged according to the resistance values, and the situation that the positive and negative electrode insulation resistors fail in the same proportion and are grounded in the related art can not be detected, or the positive and negative electrode insulation resistors fail in the wrong judgment when the leakage current is large is avoided.

The technical scheme of the present disclosure is described in further detail below through the accompanying drawings and examples.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.

Fig. 1 is a schematic diagram of an insulation resistance detection circuit for a power cell according to some embodiments of the present disclosure.

Fig. 2 is a flow diagram of an insulation resistance detection method for a power cell according to some embodiments of the present disclosure.

Fig. 3 and 4 are equivalent circuit schematic diagrams of insulation resistance detection circuits according to some embodiments of the present disclosure.

Fig. 5-8 are schematic diagrams of implementations of power cell insulation detection circuits according to some embodiments of the present disclosure.

Fig. 9 is a schematic diagram of an insulation resistance detection circuit for a power cell according to further embodiments of the present disclosure.

Fig. 10 is a flow chart of an insulation resistance detection method for a power cell according to further embodiments of the present disclosure.

Fig. 11 is a schematic composition diagram of an insulation resistance detection device for a power cell according to some embodiments of the present disclosure.

Fig. 12 is a schematic structural view of an insulation resistance detection device for a power cell according to some embodiments of the present disclosure.

Detailed Description

The following description of the technical solutions in the embodiments of the present disclosure will be made clearly and completely with reference to the accompanying drawings in the embodiments of the present disclosure, and it is apparent that the described embodiments are only some embodiments of the present disclosure, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments in this disclosure without inventive faculty, are intended to fall within the scope of this disclosure.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless it is specifically stated otherwise.

Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

The insulation resistance detection circuit of the power battery is used for detecting the resistance value of the positive insulation resistance and the negative insulation resistance of the power battery. The expected protection effect can be realized only when the resistance value of the positive and negative electrode insulation resistors exceeds a certain resistance threshold value.

In the related art, two equivalent measuring resistors are respectively connected in parallel with an anode insulating resistor and a cathode insulating resistor of a power battery to form a huyghen bridge circuit, and the safety of the anode insulating resistor and the cathode insulating resistor is detected according to the change of leakage current flowing through a bridge (namely, in the bridge circuit, the path formed between one end, far away from the power battery, of the anode insulating resistor and one end, far away from the power battery, of the measuring resistor). In the case where the resistances of the positive and negative insulation resistances are equal, the bridge circuit should be in a balanced state, and the leakage current flowing through the bridge is zero. If the leakage current is a non-zero value, the resistance values of the positive and negative electrode insulation resistors are proved to be unequal, and potential safety hazards possibly exist.

However, the above-described method has the following two disadvantages: 1) When the positive and negative electrode insulation resistances are equal to each other and fail in grounding, i.e. are increased or decreased in equal proportion, the balance of the bridge circuit is not destroyed, and the leakage current is still zero, but at this time, potential safety hazards may exist because the positive and negative electrode insulation resistances are too large or too small. 2) When the insulation resistance values of the positive electrode and the negative electrode are not equal, but are all in a safe range, the leakage current is also a non-zero value. The larger the resistance difference between the positive and negative electrode insulation resistances is, the larger the leakage current is. In this case, however, the resistance values of the positive and negative electrode insulation resistances already satisfy the insulation requirements, and the positive and negative electrode insulation resistances are effective, but there is a possibility that the positive and negative electrode insulation resistances are erroneously judged to be invalid due to the presence of the leakage current.

To solve the above-described problems, the present disclosure proposes a circuit for insulation resistance detection of a power battery and a method of detecting insulation resistance of a power battery applied to the circuit.

For ease of understanding, the insulation resistance detection circuit of the power cell will be described first, and then the related insulation resistance detection method will be described in connection with the circuit.

Fig. 1 is a schematic diagram of an insulation resistance detection circuit for a power cell according to some embodiments of the present disclosure. The power cell includes a power source 10, a positive insulation resistance 01, and a negative insulation resistance 02. The positive insulation resistor 01 is terminated between the positive pole of the power supply 10 and a reference ground potential. The negative insulation resistance 02 is terminated between the negative electrode of the power supply 10 and a reference ground potential.

Unlike the related art in which the detection is performed by the resistance balance of the positive electrode insulation resistance and the negative electrode insulation resistance, the insulation resistance detection circuit 100 according to the embodiment of the present disclosure is at least used to detect the magnitudes of the resistances of the positive electrode insulation resistance 01 and the negative electrode insulation resistance 02.

As shown in fig. 1, an insulation resistance detection circuit 100 for a power battery includes a measurement module 11 and a resistance access module 12.

The measurement module 11 comprises a first measurement resistor 101, a second measurement resistor 102 and a third measurement resistor 103. The first terminal of the first measuring resistor 101 and the first terminal of the second measuring resistor 102 are connected to the positive and negative poles of the power supply 10, respectively. The second end of the first measuring resistor 101 and the second end of the second measuring resistor 102 are both connected to the first end of the third measuring resistor 103. The second end of the third measuring resistor 103 is connected to a reference ground potential.

The resistive access module 12 includes a first access leg 120 and a second access leg 130. The first access branch 120 comprises a first controllable switch 121 and a first access resistor 122 connected in series with the first controllable switch 121. The second access branch 130 comprises a second controllable switch 131 and a second access resistor 132 connected in series with the second controllable switch 131. The positive pole of the power supply 10 is connected to a reference ground potential via a first access branch 120. Thereby, the first access branch 120 is formed in parallel with the positive insulation resistance 01. The negative pole of the power supply 10 is connected to a reference ground potential via a second access branch 130. Thereby, the second access branch 130 is formed in parallel with the negative insulation resistance 02.

The first controllable switch 121 is controlled such that the first access branch 120 is in an on-state or an off-state. When the first access branch 120 is in the on state, the first access resistor 122 is connected in parallel with the positive insulation resistor 01. When the first access branch 120 is in the off state, the first access resistor 122 is not connected to the insulation resistance detection circuit 100. The second controllable switch 131 is controlled such that the second access branch 130 is in an on-state or an off-state. When the second access branch 130 is in the on state, the second access resistor 132 is connected in parallel with the negative insulation resistor 02. When the second access branch 130 is in the off state, the second access resistor 132 is not connected to the insulation resistance detection circuit 100.

In some embodiments, insulation resistance detection circuit 100 further includes a controller 140. The controller 140 includes a first signal control terminal 141, a second signal control terminal 142, and a ground terminal 143. The first signal control terminal 141 and the second signal control terminal 142 are respectively connected to the first controllable switch 121 and the second controllable switch 131 to respectively control the first access branch 120 and the second access branch 130 to be in an on state or an off state. The ground terminal 143 of the controller 140 is connected to a reference ground potential.

In some implementations, the controller 140 may be a Micro-controller Unit (MCU).

Fig. 2 is a flow diagram of an insulation resistance detection method 200 for a power cell according to some embodiments of the present disclosure. The insulation resistance detection method 200 may be applied to the insulation resistance detection circuit 100 shown in fig. 1, and the insulation resistance detection circuits 500 to 800 shown in fig. 5 to 8 hereinafter. The insulation resistance detection method 200 includes steps 201 to 209, which are described below in connection with fig. 1.

In step 201, the first controllable switch 121 and the second controllable switch 131 are controlled such that the first access branch 120 is in an on state and the second access branch 130 is simultaneously in an off state.

In step 203, a first voltage between the positive pole of the power supply 10 and the reference ground potential and a second voltage between the negative pole of the power supply 10 and the reference ground potential are collected while the first access branch 120 is in the on state and the second access branch 130 is in the off state.

In step 205, the first controllable switch 121 and the second controllable switch 131 are controlled such that the first access leg 120 is in an off state and the second access leg 130 is in an on state at the same time.

In some embodiments, steps 201 and 205 are performed by controller 140. For example, the controller 140 may transmit a control signal to the first controllable switch 121 through the first signal control terminal 141 to control on or off of the first controllable switch, thereby controlling the on or off state of the first access branch 120. The controller 140 may transmit a control signal to the second controllable switch 131 through the second signal control terminal 142 to control on or off of the second controllable switch, thereby controlling the on or off state of the second access branch 130.

In step 207, a third voltage between the positive pole of the power supply 10 and the reference ground potential and a fourth voltage between the negative pole of the power supply 10 and the reference ground potential are collected while the first access branch 120 is in the off state and the second access branch 130 is in the on state.

In some embodiments, to facilitate voltage acquisition, the insulation resistance detection circuit (e.g., insulation resistance detection circuit 100 shown in fig. 1, and insulation resistance detection circuits 500-800 shown in fig. 5-8, hereafter) further includes a first voltage acquisition module and a second voltage acquisition module.

The first voltage acquisition module is configured to acquire a first voltage between a positive pole of the power battery and a reference ground potential and a second voltage between a negative pole of the power battery and the reference ground potential while the first access leg 120 is in an on state and the second access leg 130 is in an off state.

The second voltage acquisition module is configured to acquire a third voltage between a positive pole of the power battery and a reference ground potential and a fourth voltage between a negative pole of the power battery and the reference ground potential while the first access leg 120 is in an off state and the second access leg 130 is in an on state.

In step 209, the resistance values of the positive insulation resistance 01 between the positive electrode of the power supply 10 and the reference ground potential and the negative insulation resistance 02 between the negative electrode of the power supply 10 and the reference ground potential are calculated from the first voltage, the second voltage, the third voltage, the fourth voltage, and the resistance values of the first measurement resistor 101, the second measurement resistor 102, the third measurement resistor 103, the first access resistor 122, and the second access resistor 132.

In some embodiments, the resistances of the first measurement resistor 101 and the second measurement resistor 102 are equal.

In some embodiments, the first access resistor 122 and the second access resistor 132 have equal resistance values.

In some embodiments, the resistance values of the positive insulation resistance 01 and the negative insulation resistance 02 are calculated using ohm's law. A specific calculation process is described below in connection with fig. 3 and 4.

When the first access branch 120 is turned on and the second access branch 130 is turned off, the insulation resistance detection circuit 100 of fig. 1 can be simplified to an equivalent circuit 300 as shown in fig. 3, which corresponds to connecting the first access resistor 122 in parallel with the positive insulation resistor 01.

In fig. 3, the first access resistor 122 is connected in parallel with the positive insulation resistor 01 to form an equivalent resistor 301Wherein->Resistance value of positive electrode insulation resistance 01, < ->Representing the resistance of the first access resistor 122.

Current flowing through equivalent resistor 301Wherein->Representing the voltage between the positive pole of the power supply 10 and the reference ground potential.

Current flowing through the second measuring resistor 102Wherein->Represents the voltage between the negative pole of the power supply 10 and the reference ground potential, < > >Representing the resistance of the second measuring resistor 102.

From the fact that the current flowing into the point A shown in FIG. 3 is equal to the current flowing out of the point A, the current flowing through the first measuring resistor 101And the current flowing through the third measuring resistor 103 +.>Sum of (a) and (b) of the current flowing through the second measuring resistor 102>Equal, i.e.. From the fact that the current flowing into the point B shown in FIG. 3 is equal to the current flowing out of the point B, the current flowing through the third measuring resistor 103 is +.>Equal to the current through the equivalent resistor 301>And current flowing through the negative insulation resistor 02>The difference, i.e。

Expressed by the voltage and resistance values across the first measuring resistor 101 and the second measuring resistor 102 according to ohm's lawAnd->And further according to electricityThe circuit relation uses the voltage across the first measuring resistor 101 and the second measuring resistor 102 as the first voltage +.>Second voltage->And the resistance value of the third measuring resistor 103 +.>And the current through the third measuring resistor 103 +.>The expression, equation (1) is obtained.

(1) Wherein->The resistance of the first measuring resistor 101 is shown.

In the equation (1) for the case of the liquid,will->And->And (3) carrying out equation (1) and finishing to obtain equation (2).

（2）。

When the first access branch 120 is turned off and the second access branch 130 is turned on, the insulation resistance detection circuit 100 of fig. 1 can be simplified to an equivalent circuit 400 as shown in fig. 4, which corresponds to connecting the second access resistor 132 in parallel with the negative insulation resistor 02.

In fig. 4, the second access resistor 132 and the negative insulation resistor 02 are connected in parallel to each other to form an equivalent resistor 401Wherein->Represents the resistance of the negative insulation resistance 02, +.>Representing the resistance of the second access resistor 132.

Similar to the process of obtaining equation (2), equation (3) is obtained according to the equivalent circuit 400.

（3）。

Simultaneous equations (1) and (2) give a system of equations and solve the system of equations to calculateAnd->。

To simplify the representation, let，/>，/>. Then->，。

It should be appreciated that for simplicity of calculation, assume thatBut when->In this case, the +.>And。

in some embodiments, to facilitate calculation of insulation resistance, the insulation resistance detection circuit (e.g., insulation resistance detection circuit 100 shown in fig. 1, and insulation resistance detection circuits 500 through 800 shown in fig. 5 through 8, hereinafter) further includes an insulation resistance calculation module. The insulation resistance calculation module is configured to calculate a resistance value of an anode insulation resistance between an anode of the power battery and a reference ground potential and a cathode insulation resistance between a cathode of the power battery and the reference ground potential according to the first voltage, the second voltage, the third voltage, the fourth voltage, and resistance values of the first measurement resistance, the second measurement resistance, the third measurement resistance, the first access resistance, and the second access resistance.

In the above embodiment, the bridge formed by the plurality of measuring resistors and the positive and negative insulation resistors is configured to break the balance of the bridge by connecting the parallel connection resistors to the two ends of the positive insulation resistor and the negative insulation resistor, so that the resistance values of the positive insulation resistor and the negative insulation resistor are calculated according to the resistance values of the measuring resistors and the voltages of the positive electrode and the negative electrode of the power battery to the ground. The method can accurately calculate the resistance values of the positive and negative electrode insulation resistors, so that whether the resistance values of the positive and negative electrode insulation resistors meet the safety requirements is judged according to the resistance values, and the situation that the positive and negative electrode insulation resistors fail in the same proportion and are not detected in the related art and/or the positive and negative electrode insulation resistors fail in the wrong judgment when the leakage current is large is avoided.

In some embodiments, the insulation resistance detection method 200 further comprises: an early warning is issued in response to determining at least one of the following conditions: the resistance value of the positive electrode insulation resistor is lower than a first threshold value; or the negative electrode insulation resistance is lower than the second threshold value. When the positive insulation resistance or the negative insulation resistance is lower than the corresponding threshold value, sending out early warning to prompt related detection personnel that potential safety hazards exist in the positive insulation resistance or the negative insulation resistance.

In some embodiments, the first threshold and the second threshold are equal.

In some embodiments, the first controllable switch and the second controllable switch may be implemented by various transistors, including a triode (bipolar junction transistor, BJT, bipolar Junction Transistor), a junction field effect transistor (JFET, junction Field Effect Transistor), a Metal-Oxide-semiconductor field effect transistor (MOS-FET), and the like. In other embodiments, the first controllable switch and the second controllable switch may be implemented by other mechanical/electronic switches.

Fig. 5-8 are schematic diagrams of some implementations of power cell insulation detection circuits according to some embodiments of the present disclosure.

In some embodiments, as shown in fig. 5 or fig. 6, the first controllable switch includes a first triode, an emitter e of the first triode is connected to the first access resistor 122, a base b of the first triode is connected to the first signal control terminal 141 of the controller 140, the second controllable switch includes a second triode, a collector c of the second triode is connected to the second access resistor 132, and a base b of the second triode is connected to the second signal control terminal 142 of the controller 140.

For example, as shown in fig. 5, the first transistor 511 and the second transistor 512 in the insulation resistance detection circuit 500 are NPN transistors, and when the potential of the base b is smaller than the potential of the collector c and the potential of the emitter e, the NPN transistors are in an off state, and the emitter e and the collector c are not conductive; when the potential of the base b is greater than the potential of the collector c and the potential of the emitter e, the NPN transistor is in a saturated state, and the emitter e and the collector c are turned on. Accordingly, the first transistor 511 is turned on by applying a high voltage (outputting a high level signal) through the first signal control terminal 141, and the second transistor 512 is turned off by applying a low voltage (outputting a low level signal) through the second signal control terminal 142; the first transistor 511 is turned off by applying a low voltage (outputting a low level signal) through the first signal control terminal 141, and the second transistor 512 is turned on by applying a high voltage (outputting a high level signal) through the second signal control terminal 142.

As another example, as shown in fig. 6, the first transistor 611 and the second transistor 612 in the insulation resistance detection circuit 600 are PNP transistors, and when the potential of the base b is greater than the potential of the collector c and the potential of the emitter e, the PNP transistors are in an off state, and the emitter e and the collector c are not conductive; when the potential of the base b is smaller than the potential of the collector c and the potential of the emitter e, the PNP transistor is in a saturated state, and the emitter e and the collector c are turned on. Accordingly, the first transistor 611 is turned on by applying a low voltage (outputting a low level signal) through the first signal control terminal 141, and the second transistor 612 is turned off by applying a high voltage (outputting a high level signal) through the second signal control terminal 142; the first transistor 611 is turned off by applying a high voltage (outputting a high level signal) through the first signal control terminal 141, and the second transistor 612 is turned on by applying a low voltage (outputting a low level signal) through the second signal control terminal 142.

In some embodiments, to protect the first transistor, the second transistor, and the controller 140, when connected to the controller 140, the protection resistor 104 is connected in series between the base of the first transistor and the first signal control terminal 141 of the controller and/or the protection resistor 105 is connected in series between the base of the second transistor and the second signal control terminal 142 of the controller 140. The resistance of the protection resistor can be determined according to the specifications of the selected triode.

The above manner controls the base potential of the transistor by the controller so that the transistor is in a saturated state or an off state, respectively, thereby controlling the on and off of the first and second access branches 120 and 130. When the triode is in a saturated state, the emitter and the collector of the triode are conducted, and the access branch is connected; when the triode is in a cut-off state, the emitter and the collector of the triode are not conducted, and the access branch is disconnected.

In some embodiments, the first and second controllable switches comprise field effect transistors (including JFETs and MOS transistors). The following description refers to a MOS transistor as a non-limiting example. As shown in fig. 7 or fig. 8, the first controllable switch 121 includes a first MOS transistor, a drain D of the first MOS transistor is connected to the first access resistor 122, a gate G of the first MOS transistor is connected to the first signal control end 141 of the controller 140, the second controllable switch 131 includes a second MOS transistor, a source S of the second MOS transistor is connected to the second access resistor 132, and a gate G of the second MOS transistor is connected to the second signal control end 142 of the controller 140.

For example, as shown in fig. 7, the first MOS transistor 711 and the second MOS transistor 712 in the insulation resistance detection circuit 700 are P-type MOS transistors, when the voltage between the gate G and the source S is less than or equal to the threshold voltage of the MOS transistors, the P-type MOS transistors are in a conductive state, the source S and the drain D are conductive, otherwise the P-type MOS transistors are in a non-conductive state, and the source S and the drain D are non-conductive. Therefore, when a low voltage (a low level signal is output) is applied through the first signal control terminal 141, the first MOS transistor 711 is turned on, and when a high voltage (a high level signal is output) is applied through the second signal control terminal 142, the second MOS transistor 712 is turned off; the first MOS transistor 711 is turned off when a high voltage (a high level signal is output) is applied through the first signal control terminal 141, and the second MOS transistor 712 is turned on when a low voltage (a low level signal is output) is applied through the second signal control terminal 142.

For another example, as shown in fig. 8, the first MOS transistor 811 and the second MOS transistor 812 in the insulation resistance detection circuit 800 are both N-type MOS transistors, when the voltage between the gate G and the source S is greater than the threshold voltage of the MOS transistor, the N-type MOS transistor is in a conductive state, the source S and the drain D are conductive, otherwise the N-type MOS transistor is in a non-conductive state, and the source S and the drain D are non-conductive. Therefore, when a high voltage (a high level signal is output) is applied through the first signal control terminal 141, the first MOS transistor 811 is turned on, and when a low voltage (a low level signal is output) is applied through the second signal control terminal 142, the second MOS transistor 812 is turned off; the first MOS transistor 811 is turned off by applying a low voltage (outputting a low level signal) through the first signal control terminal 141, and the second MOS transistor 812 is turned on by applying a high voltage (outputting a high level signal) through the second signal control terminal 142.

In some embodiments, to protect the first MOS transistor, the second MOS transistor, and the controller 140, when connected to the controller 104, the protection resistor 104 is connected in series between the gate G of the first MOS transistor and the first signal control terminal 141 of the controller 140 and/or the protection resistor 105 is connected in series between the gate G of the second MOS transistor and the second signal control terminal 142 of the controller 140. The resistance of the protection resistor can be determined according to the specification of the selected MOS tube.

The mode controls the grid potential of the MOS tube through the controller, so that the MOS tube is in an on state or an off state respectively, and the on and off of the first access branch and the second access branch are controlled. When the MOS tube is in a conducting state, the source electrode S and the drain electrode D of the MOS tube are conducted, and the access branch is connected; when the MOS tube is in the cut-off state, the source electrode S and the drain electrode D of the MOS tube are not conducted, and the access branch is disconnected.

It is easily conceivable that the first controllable switch 121 and the second controllable switch 131 may be different types of transistors or MOS transistors, for example, the first controllable switch 121 includes an NPN transistor and the second controllable switch 131 includes a P-type MOS transistor. The positions of the access resistor and the controllable switch in the access circuit can be adjusted according to the requirements, and the present disclosure is not particularly limited.

In some embodiments, the insulation resistance detection circuit 100 further includes a leakage current acquisition module. The leakage current acquisition module is configured to acquire the leakage current flowing through the third measurement resistor 103 in case that both the first access leg 120 and the second access leg 130 are in an off state.

In some embodiments, the insulation resistance detection method 200 further includes, in correspondence with the above-described embodiments: in case both the first access leg 120 and the second access leg 130 are in an open state, the leakage current through the third measuring resistor 103 is collected. Through the monitoring to leakage current size, can help judging rapidly whether positive, negative pole insulation resistance probably has the potential safety hazard. When the leakage current is non-zero, the resistance values of the positive and negative electrode insulation resistors are unequal, and when the leakage current is overlarge, the resistance values of the positive and negative electrode insulation resistors have larger difference, and potential safety hazards possibly exist.

In some embodiments, the insulation resistance detection circuit 100 further includes an early warning module. The early warning module is configured to send out early warning according to the magnitude of the leakage current. Accordingly, the insulation resistance detection method 200 further includes issuing an early warning in response to determining that the leakage current is a non-zero value. In other embodiments, the warning is issued when the leakage current is greater than a preset current value. The early warning prompts that potential safety hazards possibly exist in the positive electrode insulation resistance and the negative electrode insulation resistance.

In some embodiments, when the early warning module is further configured to issue an early warning in response to determining at least one of the following conditions: the resistance value of the positive electrode insulation resistor is lower than a first threshold value; or the negative electrode insulation resistance is lower than the second threshold value. The early warning module monitors the leakage current obtained from the leakage current acquisition module at any time, and sends out early warning according to the calculated resistance values of the positive and negative insulation resistances, and the early warning module can quickly respond and send out early warning no matter what kind of problems occur in the positive and negative insulation resistances.

The present disclosure also provides another insulation resistance detection circuit 900 that may be juxtaposed with the insulation resistance detection circuit 100 shown in fig. 1, both of which may solve the problems of the related art, but have some differences in circuit structure.

The insulation resistance detection circuit 900 is described below with reference to fig. 9, and the insulation resistance detection method 1000 applied to the insulation resistance detection circuit 900 is described with reference to fig. 10.

Fig. 9 is a schematic diagram of an insulation resistance detection circuit for a power cell according to further embodiments of the present disclosure. Fig. 10 is a flow chart of an insulation resistance detection method for a power cell according to further embodiments of the present disclosure.

In some embodiments, as shown in fig. 9, the insulation resistance detection circuit 900 includes a measurement module 91 and a resistance access module 92. The insulation resistance detection circuit 900 may also be used to detect the insulation resistance of the power cell.

The measurement module 91 has the same circuit configuration as the measurement module 11 of fig. 1. The measurement module 91 comprises a first measurement resistor 901, a second measurement resistor 902 and a third measurement resistor 903. The first end of the first measuring resistor 901 and the first end of the second measuring resistor 902 are connected to the positive and negative pole of the power supply 10, respectively, the second end of the first measuring resistor 901 and the second end of the second measuring resistor 902 are connected to the first end of the third measuring resistor 903, and the second end of the third measuring resistor is connected to the reference ground potential.

The resistive access module 92 differs from the circuit configuration of the resistive access module 12 of fig. 1. The resistor accessing module 92 includes a selection switch 921 and an accessing resistor 922 connected in series with the selection switch 921. The first output terminal a of the selection switch 921 is connected to the positive electrode of the power source 10 of the power battery, the second output terminal b of the selection switch 921 is connected to the negative electrode of the power source 10, and the third output terminal c of the selection switch 921 is an off terminal. A first terminal of the access resistor 922 is connected to an input terminal of the selection switch 921, and a second terminal of the access resistor 922 is connected to a reference ground potential. The selection switch 921 is controlled to switch between turning on the first output terminal, turning on the second output terminal, or turning on the third output terminal.

In some embodiments, the insulation resistance detection circuit 900 further comprises a controller 940 configured to provide a control signal to the selection switch 921 to control the selection switch 921 to switch between switching on the first output a, switching on the second output b, or switching on the third output c, the ground 943 of the controller 940 being connected to a reference ground potential.

In some embodiments, the insulation resistance detection method 1000 as shown in fig. 10 is applied to the insulation resistance detection circuit 900 as shown in fig. 9. The insulation resistance detection method 1000 includes steps 1001 to 1009.

In step 1001, the control selection switch 921 is switched to turn on the first output terminal a.

In step 1003, a first voltage between the positive electrode of the power supply 10 of the power battery and the reference ground potential and a second voltage between the negative electrode of the power supply 10 of the power battery and the reference ground potential are collected while the selection switch 921 is turned on the first output terminal a.

In step 1005, the control selection switch 921 is switched to turn on the second output terminal b.

In step 1007, a third voltage between the positive electrode of the power supply 10 and the reference ground potential and a fourth voltage between the negative electrode of the power supply 10 and the reference ground potential are collected while the selection switch 921 is turned on the second output terminal b.

In step 1009, the resistance values of the positive insulation resistance 01 between the positive electrode of the power supply 10 and the reference ground potential and the negative insulation resistance 02 between the negative electrode of the power supply 10 and the reference ground potential are calculated from the first voltage, the second voltage, the third voltage, the fourth voltage, and the resistance values of the first measurement resistor 901, the second measurement resistor 902, the third measurement resistor 903, and the access resistor 922.

In some embodiments, the insulation resistance detection method 1000 further comprises: control the selector switch to switch 921 to turn on the third output terminal c; the leakage current flowing through the third measuring resistor 903 is collected while the selection switch 921 turns on the third output terminal c.

The solution shown in fig. 9 and 10 differs from the solution shown in fig. 1 and 2 only in that the first access leg 120 and the second access leg 130 shown in fig. 1 are replaced by the same access leg in fig. 9 and 10. But the relevant effect and the process of calculating the insulation resistance of the positive and negative electrodes are the same. The embodiments of the schemes shown in fig. 9 and 10 refer to the embodiments related to the schemes shown in fig. 1 and 2, and are not described herein.

Fig. 11 is a schematic composition diagram of an insulation resistance detection device for a power cell according to some embodiments of the present disclosure. The insulation resistance detection apparatus 1100 may be used in conjunction with the aforementioned insulation resistance detection circuit to implement the insulation resistance detection method 200 or the insulation resistance detection method 1000 described above. The insulation resistance detection apparatus 1100 may be implemented as program modules formed of program instructions stored on a storage medium that, when executed by a processor, implement the steps of the aforementioned insulation resistance detection method 200 or insulation resistance detection method 1000. The insulation resistance detection apparatus 1100 may also be implemented as an integrated circuit (IC, integrated Circuit), an application specific integrated circuit (ASIC, application Specific Integrated Circuit), or a Large scale integrated circuit (LSI, large-Scale Integration)), a system LSI, a super LSI, or a super LSI assembly that performs part or all of the steps of the method described in the present disclosure.

As shown in fig. 11, the insulation resistance detection apparatus 1100 includes a first control module 1101, a first acquisition module 1102, a second control module 1103, a second acquisition module 1104, and a calculation module 1105.

In some embodiments, the first control module 1101 is configured to control the first controllable switch and the second controllable switch such that the first access leg is in an on state and the second access leg is in an off state at the same time.

The first acquisition module 1103 is configured to acquire a first voltage between a positive pole of the power battery and a reference ground potential and a second voltage between a negative pole of the power battery and the reference ground potential while the first access branch is in an on state and the second access branch is in an off state.

The second control module 1103 is configured to control the first controllable switch and the second controllable switch such that the first access leg is in an off state and the second access leg is in an on state at the same time.

The second acquisition module 1104 is configured to acquire a third voltage between the positive pole of the power battery and the reference ground potential and a fourth voltage between the negative pole of the power battery and the reference ground potential while the first access branch is in the off state and the second access branch is in the on state.

The calculation module 1105 is configured to calculate a resistance value of a positive electrode insulation resistance between a positive electrode of the power battery and a reference ground potential and a negative electrode insulation resistance between a negative electrode of the power battery and the reference ground potential from the first voltage, the second voltage, the third voltage, the fourth voltage, and the resistance values of the first measurement resistor, the second measurement resistor, the third measurement resistor, the first access resistor, and the second access resistor.

In other embodiments, the first control module 1101 is configured to control the selection switch to switch on the first input.

The first acquisition module 1102 is configured to acquire a first voltage between a positive pole of the power battery and a reference ground potential and a second voltage between a negative pole of the power battery and the reference ground potential while the selection switch turns on the first input.

The second control module 1103 is configured to control the selection switch to switch on the second input.

The second acquisition module 1104 is configured to acquire a third voltage between the positive electrode of the power battery and the reference ground potential and a fourth voltage between the negative electrode of the power battery and the reference ground potential while the selection switch turns on the first input.

The calculation module 1105 is configured to calculate a resistance value of a positive electrode insulation resistance between a positive electrode of the power battery and a reference ground potential and a negative electrode insulation resistance between a negative electrode of the power battery and the reference ground potential from the first voltage, the second voltage, the third voltage, the fourth voltage, and resistance values of the first measurement resistance, the second measurement resistance, the third measurement resistance, and the access resistance.

In some embodiments, the insulation resistance detection apparatus 1100 may also include other modules to perform the methods of other embodiments described above.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different manner from other embodiments, so that the same or similar parts between the embodiments are mutually referred to. For the device embodiments, since they basically correspond to the method embodiments, the description is relatively simple, and the relevant points are referred to in the description of the method embodiments.

Fig. 12 is a schematic structural view of an insulation resistance detection device for a power battery according to still other embodiments of the present disclosure. The insulation resistance detection apparatus 1200 may be used to implement the insulation resistance detection method 200 or the insulation resistance detection method 1000 described above.

As shown in fig. 12, the insulation resistance detection apparatus 1200 includes a memory 1201 and a processor 1202 coupled to the memory 1201, the processor 1202 being configured to perform the method of any of the foregoing embodiments based on instructions stored in the memory 1201.

The memory 1201 may include, for example, system memory, fixed nonvolatile storage media, and the like. The system memory may store, for example, an operating system, application programs, boot Loader (Boot Loader), and other programs.

The insulation resistance detection apparatus 1200 may further include an input-output interface 1203, a network interface 1204, a storage interface 1205, and the like. The input/output interface 1203, the network interface 1204, the storage interface 1205, and the memory 1201 and the processor 1202 may be connected by a bus 1206, for example. The input/output interface 1203 provides a connection interface for input/output devices such as a display, mouse, keyboard, touch screen, etc. The network interface 1204 provides a connection interface for various networking devices. The storage interface 1205 provides a connection interface for external storage devices such as SD cards, U-discs, and the like.

The disclosed embodiments also provide a computer readable storage medium comprising computer program instructions which, when executed by a processor, implement the method of any of the above embodiments.

The disclosed embodiments also provide a computer program product comprising a computer program which, when executed by a processor, implements the method of any of the above embodiments.

Thus, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concepts of the present disclosure, some details known in the art are not described. How to implement the solutions disclosed herein will be fully apparent to those skilled in the art from the above description.

It will be appreciated by those skilled in the art that embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that functions specified in one or more of the flowcharts and/or one or more of the blocks in the block diagrams may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that the foregoing embodiments may be modified and equivalents substituted for elements thereof without departing from the scope and spirit of the disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. An insulation resistance detection circuit for a power cell, the circuit comprising:

the measuring module comprises a first measuring resistor, a second measuring resistor and a third measuring resistor, wherein the first end of the first measuring resistor and the first end of the second measuring resistor are respectively connected with the positive electrode and the negative electrode of the power battery, the second end of the first measuring resistor and the second end of the second measuring resistor are connected with the first end of the third measuring resistor, and the second end of the third measuring resistor is connected to the reference ground potential; and

the resistor access module comprises a first access branch and a second access branch, wherein the first access branch comprises a first controllable switch and a first access resistor connected in series with the first controllable switch, the second access branch comprises a second controllable switch and a second access resistor connected in series with the second controllable switch, the positive electrode of the power battery is connected to the reference ground potential through the first access branch, the negative electrode of the power battery is connected to the reference ground potential through the second access branch, the first controllable switch is controlled to enable the first access branch to be in an on state or an off state, and the second controllable switch is controlled to enable the second access branch to be in an on state or an off state.

2. The circuit of claim 1, further comprising:

the controller comprises a first signal control end, a second signal control end and a grounding end, wherein the first signal control end and the second signal control end are respectively connected to the first controllable switch and the second controllable switch so as to respectively control the first access branch and the second access branch to be in an on state or an off state, and the grounding end of the controller is connected to the reference ground potential.

3. The circuit of claim 2, wherein the circuit further comprises a logic circuit,

the first controllable switch comprises a first triode, the emitter of the first triode is connected with the first access resistor, the base of the first triode is connected with the first signal control end,

the second controllable switch comprises a second triode, the collector electrode of the second triode is connected with the second access resistor, and the base electrode of the second triode is connected with the second signal control end.

4. The circuit of claim 2, wherein the circuit further comprises a logic circuit,

the first controllable switch comprises a first MOS tube, the drain electrode of the first MOS tube is connected with the first access resistor, the grid electrode of the first MOS tube is connected with the first signal control end,

The second controllable switch comprises a second MOS tube, a source electrode of the second MOS tube is connected with the second access resistor, and a grid electrode of the second MOS tube is connected with the second signal control end.

5. The circuit of claim 1, further comprising:

a first voltage acquisition module configured to acquire a first voltage between a positive electrode of the power battery and the reference ground potential and a second voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an on state and the second access branch is in an off state;

and a second voltage acquisition module configured to acquire a third voltage between a positive electrode of the power battery and the reference ground potential and a fourth voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an off state and the second access branch is in an on state.

6. The circuit of claim 5, further comprising:

an insulation resistance calculation module configured to calculate a resistance value of a positive insulation resistance between a positive electrode of the power battery and the reference ground potential and a negative insulation resistance between a negative electrode of the power battery and the reference ground potential from the first voltage, the second voltage, the third voltage, the fourth voltage, and resistance values of the first measurement resistance, the second measurement resistance, the third measurement resistance, the first access resistance, and the second access resistance.

7. The circuit of claim 1, further comprising:

and the leakage current acquisition module is configured to acquire leakage current flowing through the third measuring resistor under the condition that the first access branch and the second access branch are in a disconnected state.

8. The circuit of claim 6, further comprising:

and the early warning module is configured to send out early warning according to the magnitude of the leakage current.

9. The circuit of claim 1, wherein the first measurement resistor and the second measurement resistor have equal resistance values.

10. The circuit of claim 1, wherein the first access resistor and the second access resistor have equal values.

11. An insulation resistance detection circuit for a power battery, comprising:

The resistor access module comprises a selection switch and an access resistor connected in series with the selection switch, wherein a first output end of the selection switch is connected with a positive electrode of the power battery, a second output end of the selection switch is connected with a negative electrode of the power battery, a third output end of the selection switch is an off terminal, a first end of the access resistor is connected to an input end of the two-way selection switch, a second end of the access resistor is connected to the reference ground potential, and the selection switch is controlled to switch among switching on the first output end, switching on the second output end or switching on the third output end.

12. The circuit of claim 11, further comprising:

and a controller configured to provide a control signal to the selection switch to control the selection switch to switch between switching on the first output terminal, switching on the second output terminal, or switching on the third output terminal, a ground terminal of the controller being connected to the reference ground potential.

13. An insulation resistance detection method for a power battery, characterized by being applied to the insulation resistance detection circuit of claim 1, the method comprising:

Controlling the first controllable switch and the second controllable switch such that the first access leg is in an on state and the second access leg is in an off state at the same time;

collecting a first voltage between a positive electrode of the power battery and the reference ground potential and a second voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an on state and the second access branch is in an off state;

controlling the first controllable switch and the second controllable switch such that the first access leg is in an off state and the second access leg is in an on state at the same time;

collecting a third voltage between a positive electrode of the power battery and the reference ground potential and a fourth voltage between a negative electrode of the power battery and the reference ground potential while the first access branch is in an off state and the second access branch is in an on state;

and calculating the resistance values of a positive electrode insulation resistance between a positive electrode of the power battery and the reference ground potential and a negative electrode insulation resistance between a negative electrode of the power battery and the reference ground potential according to the first voltage, the second voltage, the third voltage, the fourth voltage and the resistance values of the first measuring resistor, the second measuring resistor, the third measuring resistor, the first access resistor and the second access resistor.

14. The method as recited in claim 13, further comprising:

and under the condition that the first access branch and the second access branch are in the disconnected state, collecting leakage current flowing through the third measuring resistor.

15. The method as recited in claim 14, further comprising:

and sending out an early warning in response to determining that the leakage current is a non-zero value.

16. The method as recited in claim 13, further comprising:

an early warning is issued in response to determining at least one of the following conditions:

the resistance value of the positive electrode insulation resistor is lower than a first threshold value; or (b)

The negative electrode insulation resistance has a resistance value lower than a second threshold value.

17. An insulation resistance detection method for a power battery, applied to the insulation resistance detection circuit according to claim 11, the method comprising:

controlling the selection switch to switch on the first output end;

collecting a first voltage between a positive electrode of the power battery and the reference ground potential and a second voltage between a negative electrode of the power battery and the reference ground potential while the selection switch is connected with the first output end;

Controlling the selection switch to switch on the second output end;

collecting a third voltage between a positive electrode of the power battery and the reference ground potential and a fourth voltage between a negative electrode of the power battery and the reference ground potential while the selection switch is connected with the second output end;

and calculating the resistance values of a positive electrode insulation resistance between the positive electrode of the power battery and the reference ground potential and a negative electrode insulation resistance between the negative electrode of the power battery and the reference ground potential according to the first voltage, the second voltage, the third voltage, the fourth voltage and the resistance values of the first measuring resistor, the second measuring resistor, the third measuring resistor and the access resistor.

18. The method as recited in claim 17, further comprising:

controlling the selection switch to switch on the third output end;

and collecting leakage current flowing through the third measuring resistor while the selection switch is connected with the third output end.

19. Insulation resistance detection device for a power battery, characterized by comprising means for performing the method according to any of claims 13-18.

20. An insulation resistance detection device for a power battery, comprising:

a memory; and

a processor coupled to the memory and configured to perform the method of any of claims 13-18 based on instructions stored in the memory.

21. A computer readable storage medium comprising computer program instructions which, when executed by a processor, implement the method according to any one of claims 13-18.

22. A computer program product comprising a computer program which, when executed by a processor, implements the method according to any of claims 13-18.