Insulation detection circuit of energy storage system

Abstract

The invention provides an insulation detection circuit of an energy storage system. A first sampling unit is used for forming a battery cluster voltage division sampling loop of a battery cluster in the energy storage system; the second sampling unit is used for forming an insulation voltage partial voltage sampling loop of a battery cluster to a casing equivalent insulation resistor in the energy storage system; the insulation resistance detection unit is used for obtaining a battery cluster partial voltage and an insulation voltage partial voltage by using the battery cluster partial voltage sampling loop and the insulation voltage partial voltage sampling loop; according to the battery cluster partial voltage, the insulation voltage partial voltage, the resistance of the first sampling unit and the resistance of the second sampling unit, constructing an electrical balance equation set about the equivalent insulation resistance of the battery cluster to the casing, and solving the electrical balance equation set to obtain the insulation resistance of the energy storage system. Sampling of battery cluster voltage division and insulation voltage division can be achieved only through one digital-to-analog converter or the digital-to-analog converter in the microcontroller, and only one change-over switch tube adopting a PhotoMOS tube is needed, so that the detection cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit performance detection, and in particular to an insulation detection circuit of an energy storage system. Background Art

[0002] With the development of clean energy around the world, the corresponding storage demand is increasing. The basic task of the energy storage system is to overcome the temporal or local differences between energy supply and demand to meet different energy needs.

[0003] Energy storage systems can be used to store kinetic energy, electrical energy, thermal energy, chemical energy and other energies. Currently, the most widely used systems are those for storing electrical energy. Among them, lithium battery energy storage systems are widely used in power storage, electric vehicles and other fields due to their advantages such as high efficiency and environmental protection. However, lithium battery energy storage systems are high-voltage systems (the voltage of on-board energy storage systems is as high as 800V, and the voltage of large storage systems is as high as 1500V), and high-voltage insulation testing is required to avoid short-circuit failures, which can cause immeasurable losses.

[0004] The inventors have found that most of the insulation detection schemes for existing energy storage systems use a balanced bridge structure for detection. The positive and negative bridge arms are respectively connected to detection resistors through PhotoMOS tubes (photocouplers), and data is collected through ADCs (digital-to-analog converters). Finally, the insulation value is calculated and solved by software. Multiple high-voltage switching tubes and ADCs are required, which is costly. Summary of the invention

[0005] In this regard, the present application provides an insulation detection circuit for an energy storage system to solve the problem that the insulation detection circuit of the existing energy storage system requires multiple high-voltage switching tubes and multiple digital-to-analog converters, resulting in high detection costs.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] The present application discloses an insulation detection circuit of an energy storage system, comprising: a first sampling unit, a second sampling unit and an insulation impedance detection unit;

[0008] The first sampling unit is used to form a battery cluster voltage division sampling circuit of the battery cluster in the energy storage system;

[0009] The second sampling unit is used to form an insulation voltage division sampling loop of the battery cluster to the casing equivalent insulation resistance in the energy storage system, and the second sampling unit includes: a sampling upper bridge arm circuit, a sampling lower bridge arm circuit and a sampling access switch, and the connection point between the sampling upper bridge arm circuit and the sampling lower bridge arm circuit is connected to the casing grounding point of the energy storage system through the sampling access switch; one of the sampling upper bridge arm circuit and the sampling lower bridge arm circuit includes a switching switch, and the insulation voltage division sampling loop formed by the sampling upper bridge arm circuit and the sampling lower bridge arm circuit is different when the switching switch is in different states;

[0010] The insulation impedance detection unit is used to obtain the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling circuit and the insulation voltage voltage division sampling circuit; construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

[0011] Optionally, in the insulation detection circuit of the energy storage system, the electrical balance equation group includes: a first battery cluster voltage balance equation, a first insulation voltage balance equation, a second battery cluster voltage balance equation, and a second insulation voltage balance equation;

[0012] The first battery cluster voltage balance equation is constructed according to the first battery cluster voltage division and the resistance of the first sampling unit, and the first insulation voltage balance equation is constructed according to the first insulation voltage division, the resistance of the second sampling unit and the equivalent insulation resistance of the battery cluster to the housing; the first battery cluster voltage division and the first insulation voltage division are obtained by sampling when the sampling access switch is in a closed state, the switching switch is in an open state, and the insulation voltage division sampling loop is in a steady-state equilibrium state;

[0013] The second battery cluster voltage balance equation is constructed according to the second battery cluster voltage division and the resistance of the first sampling unit, and the second insulation voltage balance equation is constructed according to the second insulation voltage division, the resistance of the second sampling unit and the equivalent insulation resistance of the battery cluster to the casing; the second battery cluster voltage division and the second insulation voltage division are obtained by sampling when the sampling access switch is in a closed state, the switching switch is in a conducting state, and the insulation voltage division sampling loop is in a steady-state equilibrium state.

[0014] Optionally, in the insulation detection circuit of the energy storage system, the insulation voltage division sampling loop is in a steady-state equilibrium state including:

[0015] After the switch in the insulation voltage division sampling loop performs a switching action, the insulation detection circuit of the energy storage system meets the voltage balance state.

[0016] Optionally, in the insulation detection circuit of the energy storage system, the insulation impedance detection unit includes: a digital-to-analog converter, a first isolation chip and a first microcontroller;

[0017] The digital-to-analog converter is connected to the first microcontroller via the first isolation chip;

[0018] The digital-to-analog converter is used to collect the battery cluster divided voltage and the insulation voltage divided voltage by using the battery cluster divided voltage sampling circuit and the insulation voltage divided voltage sampling circuit, and convert the collected battery cluster divided voltage and the insulation voltage divided voltage from digital signals to analog signals;

[0019] The first isolation chip is used to isolate the digital-to-analog converter located on the high-voltage side of the system and the first microcontroller located on the low-voltage side of the system;

[0020] The first microcontroller is used to construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

[0021] Optionally, in the insulation detection circuit of the energy storage system, the insulation impedance detection unit includes: a second isolation chip, a third isolation chip, a first operational amplifier circuit, a second operational amplifier circuit and a second microcontroller;

[0022] The second isolation chip is connected to the second microcontroller via the first operational amplifier circuit, and the third isolation chip is connected to the second microcontroller via the second operational amplifier circuit;

[0023] The second isolation chip is used to isolate the first sampling unit located at the high voltage side of the system and the first operational amplifier circuit located at the low voltage side of the system;

[0024] The third isolation chip is used to isolate the second sampling unit located at the high voltage side of the system and the second operational amplifier circuit located at the low voltage side of the system;

[0025] The first operational amplifier circuit is used to amplify the battery cluster voltage division in the battery cluster voltage division sampling loop;

[0026] The second operational amplifier circuit is used to amplify the insulation voltage division in the insulation voltage division sampling loop;

[0027] The second microcontroller is used to sample the amplified battery cluster divided voltage and the insulation voltage, and construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the resistance of the first sampling unit, the resistance of the second sampling unit, the sampled battery cluster divided voltage and the insulation voltage, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

[0028] Optionally, in the insulation detection circuit of the energy storage system described above, the battery cluster sampling unit comprises: a first resistor and a second resistor;

[0029] One end of the first resistor serves as a first end of the first sampling unit and is connected to the positive electrode of the battery cluster of the energy storage system;

[0030] The other end of the first resistor is connected to one end of the second resistor;

[0031] The other end of the second resistor serves as the second end of the first sampling unit and is connected to the negative electrode of the battery cluster.

[0032] Optionally, in the insulation detection circuit of the energy storage system, the sampling upper bridge arm circuit includes: a third resistor, a fourth resistor and the switching switch; the sampling lower bridge arm circuit includes: a fifth resistor and a sixth resistor;

[0033] One end of the third resistor is connected to one end of the fourth resistor, and the connection point is connected to the positive electrode of the battery cluster;

[0034] The other end of the fourth resistor is connected to one end of the switch, the other end of the switch is respectively connected to one end of the third resistor and one end of the fifth resistor, and the other end of the fifth resistor is connected to the negative electrode of the battery cluster through the sixth resistor.

[0035] Optionally, in the insulation detection circuit of the energy storage system, the sampling upper bridge arm circuit includes: a seventh resistor; the sampling lower bridge arm circuit includes: an eighth resistor, a ninth resistor, a tenth resistor and the switching switch;

[0036] One end of the seventh resistor is connected to the positive electrode of the battery cluster; the other end of the seventh resistor is connected to one end of the eighth resistor and one end of the ninth resistor respectively; the other end of the eighth resistor is connected to one end of the tenth resistor; the other end of the ninth resistor is connected to one end of the switching switch; the other end of the switching switch is connected to the other end of the tenth resistor, and the connection point is connected to the negative electrode of the battery cluster.

[0037] Optionally, in the insulation detection circuit of the energy storage system, the sampling upper bridge arm circuit includes: an eleventh resistor, a twelfth resistor and the switching switch; the sampling lower bridge arm circuit includes: a thirteenth resistor and a fourteenth resistor;

[0038] One end of the eleventh resistor is connected to the positive electrode of the battery cluster; the other end of the eleventh resistor is respectively connected to one end of the twelfth resistor and one end of the switching switch; the other end of the switching switch is connected to the other end of the twelfth resistor and one end of the thirteenth resistor; the other end of the thirteenth resistor is connected to the other end of the fourteenth resistor; the other end of the fourteenth resistor is connected to the negative electrode of the battery cluster.

[0039] Optionally, in the insulation detection circuit of the energy storage system, the insulation impedance detection unit is further used to: control the actions of the sampling access switch and the switching switch;

[0040] And / or, periodically executing the steps of obtaining the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling loop and the insulation voltage voltage division sampling loop; constructing an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solving the electrical balance equation group to obtain the insulation impedance of the energy storage system;

[0041] And / or, after the battery cluster is connected to the energy storage system, the sampling access switch is controlled to be disconnected.

[0042] The present invention provides an insulation detection circuit of an energy storage system, comprising: a first sampling unit, a second sampling unit and an insulation impedance detection unit; the first sampling unit is used to form a battery cluster voltage division sampling circuit of a battery cluster in the energy storage system; the second sampling unit is used to form an insulation voltage division sampling circuit of an equivalent insulation resistance of a battery cluster to a casing in the energy storage system, the second sampling unit comprises: a sampling upper bridge arm circuit, a sampling lower bridge arm circuit and a sampling access switch, the connection point between the sampling upper bridge arm circuit and the sampling lower bridge arm circuit is connected to a casing grounding point of the energy storage system through the sampling switch; one of the sampling upper bridge arm circuit and the sampling lower bridge arm circuit comprises a switching switch, and the insulation voltage division sampling circuits formed by the sampling upper bridge arm circuit and the sampling lower bridge arm circuit are different when the switching switch is in different states; the insulation The impedance detection unit is used to obtain the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling circuit and the insulation voltage voltage division sampling circuit; according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing is constructed, and the electrical balance equation group is solved to obtain the insulation impedance of the energy storage system. With the above structure, the present application only needs one digital-to-analog converter or uses the digital-to-analog converter in the microcontroller itself to realize the sampling of the battery cluster voltage division and the insulation voltage division, and only needs one switching switch tube using a PhotoMOS tube, so the detection cost is low; in addition, the present application uses the real-time collected battery cluster voltage division to calculate the insulation impedance, which can also avoid the calculation error caused by voltage fluctuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0044] Figures 1 to 6 Circuit diagrams of insulation detection circuits of six energy storage systems provided in this application;

[0045] Figure 7 and Figure 8 The following are circuit diagrams of two existing insulation detection circuits. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0048] An embodiment of the present application provides an insulation detection circuit for an energy storage system to solve the problem that the insulation detection circuit of an existing energy storage system requires multiple high-voltage switching tubes and multiple digital-to-analog converters, resulting in high detection costs.

[0049] See also Figures 1 to 6 , the insulation detection circuit of the energy storage system mainly includes: a first sampling unit 101, a second sampling unit 102 and an insulation impedance detection unit 103;

[0050] In practical applications, it is also combined with Figures 1 to 6 The first sampling unit 101 and the second sampling unit 102 are connected in parallel between the battery cluster Vb of the energy storage system and the equivalent capacitance of the battery cluster to the casing.

[0051] Among them, the equivalent capacitance of the battery cluster to the casing may include: the equivalent capacitance C1 of the battery cluster facing the casing and the equivalent capacitance C2 of the battery cluster facing the casing; the specific values ​​of the equivalent capacitance C1 of the battery cluster facing the casing and the equivalent capacitance C2 of the battery cluster facing the casing can be confirmed based on actual products and are all within the protection scope of this application.

[0052] The first sampling unit 101 is used to form a battery cluster voltage division sampling loop of a battery cluster in the energy storage system.

[0053] In some embodiments, Figures 1 to 6 As shown, the first sampling unit 101 may include: a first resistor R5 and a second resistor R6;

[0054] One end of the first resistor R5 serves as the first end of the first sampling unit 101 and is connected to the positive electrode of the battery cluster Vb of the energy storage system; the other end of the first resistor R5 is connected to one end of the second resistor R6; the other end of the second resistor R6 serves as the second end of the first sampling unit 101 and is connected to the negative electrode of the battery cluster Vb.

[0055] In practical applications, since the first sampling unit 101 is connected in parallel to the positive electrode of the battery cluster Vb of the energy storage system and the negative electrode of the battery cluster Vb of the energy storage system, the battery cluster voltage division can be obtained by sampling the voltage division of any resistor in the first sampling unit 101; however, when only one digital-to-analog converter is provided in the insulation impedance detection circuit, in order to ensure that the digital-to-analog converter can realize the collection of the battery cluster voltage division and the insulation voltage voltage division, the resistor used for collecting the battery cluster voltage division in the first sampling unit 101 and the resistor used for collecting the insulation voltage division in the second sampling unit 102 should have a common connection point, and the common connection point serves as the sampling reference point of the digital-to-analog converter.

[0056] For example, Figure 1 , Figure 3 , Figure 5 For example, when only one digital-to-analog converter is set in the insulation impedance detection circuit, Figure 1 The resistor used in the first sampling unit 101 to collect the divided voltage of the battery cluster may be the resistor R6, and the resistor used in the second sampling unit 102 to sample the divided voltage of the insulation voltage may be the resistor R3; Figure 3 The resistor used in the first sampling unit 101 to collect the divided voltage of the battery cluster may be the resistor R6, and the resistor used in the second sampling unit 102 to sample the divided voltage of the insulation voltage may be the resistor R10; Figure 5 The resistor used in the first sampling unit 101 to obtain the divided voltage of the battery cluster may be the resistor R6, and the resistor used in the second sampling unit 102 to obtain the divided voltage of the insulation voltage may be the resistor R14.

[0057] The second sampling unit 102 is used to form an insulation voltage division sampling loop of the battery cluster to the equivalent insulation resistance of the casing in the energy storage system.

[0058] Among them, the equivalent insulation resistance of the battery cluster to the casing may include: the equivalent insulation resistance Rp of the battery cluster to the casing and the equivalent insulation resistance Rn of the battery cluster to the casing, both of which are virtual resistors, representing the degree of insulation between the positive electrode of the battery cluster and the negative electrode of the battery cluster and the casing; in the present application, the insulation impedance of the energy storage system is usually represented by the smaller resistance of the two virtual resistors, or the parallel value of the two virtual resistors.

[0059] Combination Figures 1 to 6The second sampling unit 102 may include: a sampling upper bridge arm circuit 1021, a sampling lower bridge arm circuit 1022 and a sampling access switch S2, wherein the connection point between the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit 1022 is connected to the housing grounding point GND of the energy storage system through the sampling access switch S2; one of the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit 1022 includes a switching switch S1, and when the switching switch S1 is in different states, the insulation voltage divider sampling loop formed by the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit 1022 is different.

[0060] In practical applications, since the sampling access switch S2 is arranged between the connection point between the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit 1022 and the housing grounding point GND of the energy storage system, its different states can control whether the insulation detection circuit is connected, without the need for frequent switching, and a signal relay with a voltage tolerance greater than the battery cluster voltage can be selected, thereby reducing the circuit cost.

[0061] However, since the state of the switching switch S1 determines the insulation voltage divider sampling loop, the state needs to be frequently switched according to the insulation detection control logic during the insulation impedance detection process. Therefore, the switching switch should use a high-voltage PhotoMOS tube whose voltage tolerance should be greater than the battery cluster voltage, and the state can be controlled by the microcontroller in the insulation detection unit on the low-voltage side.

[0062] In some embodiments, Figure 1 and Figure 2 As shown, the sampling upper bridge arm circuit 1021 may include: a third resistor R1, a fourth resistor R4 and a switch S1; the sampling lower bridge arm circuit 1022 includes: a fifth resistor R2 and a sixth resistor R3;

[0063] One end of the third resistor R1 is connected to one end of the fourth resistor R4, and the connection point is connected to the positive electrode of the battery cluster Vb; the other end of the fourth resistor R4 is connected to one end of the switching switch S1, and the other end of the switching switch S1 is respectively connected to one end of the third resistor R1 and one end of the fifth resistor R2, and the other end of the fifth resistor R2 is connected to the negative electrode of the battery cluster Vb through the sixth resistor R3.

[0064] It should be noted that in order to avoid the connection of the sampling resistor affecting the normal insulation of the loop, the third resistor R1 and the fifth resistor R2 should be selected to be large enough, and the resistance voltage capability needs to be greater than the voltage division of the energy storage system on the resistor; in specific applications, this can be achieved by connecting multiple high-voltage resistors in series.

[0065] It should also be noted that in Figure 1 and Figure 2In the circuit shown, the sixth resistor R3 is used as a resistor in the second sampling unit 102 for sampling to obtain the insulation voltage division, that is, a sampling resistor; when the insulation detection circuit of the energy storage system uses a digital-to-analog converter to realize insulation voltage division acquisition, the system's voltage division on the sixth resistor R3 needs to meet the detection range of the digital-to-analog converter, that is, the insulation detection circuit should satisfy the following relationship: R3 / (R1+R2+R3)*Vb_max<the range of the digital-to-analog converter; wherein Vb_max represents the maximum voltage of the battery cluster.

[0066] In some embodiments, Figure 3 and Figure 4 As shown, the sampling upper bridge arm circuit 1021 may include: a seventh resistor R7; the sampling lower bridge arm circuit 1022 includes: an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and a switch S1;

[0067] One end of the seventh resistor R7 is connected to the positive electrode of the battery cluster Vb; the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8 and one end of the ninth resistor R9 respectively; the other end of the eighth resistor R8 is connected to one end of the tenth resistor R10; the other end of the ninth resistor R9 is connected to one end of the switching switch S1; the other end of the switching switch S1 is connected to the other end of the tenth resistor R10, and the connection point is connected to the negative electrode of the battery cluster Vb.

[0068] It should be noted that in order to avoid the connection of the sampling resistor affecting the normal insulation of the loop, the seventh resistor R7 and the eighth resistor R8 should be selected to be large enough, and the resistance voltage capability needs to be greater than the voltage division of the energy storage system on the resistor; in specific applications, this can be achieved by connecting multiple high-voltage resistors in series.

[0069] It should also be noted that in Figure 3 and Figure 4 In the circuit shown, the tenth resistor R10 is used as a resistor in the second sampling unit 102 for sampling and obtaining the insulation voltage division, that is, a sampling resistor; when the insulation detection circuit of the energy storage system uses a digital-to-analog converter to realize insulation voltage division acquisition, the system's voltage division on the tenth resistor needs to meet the detection range of the digital-to-analog converter, that is, the insulation detection circuit should satisfy the following relationship: R10 / (R7+R8+R10)*Vb_max<the range of the digital-to-analog converter; wherein Vb_max represents the maximum voltage of the battery cluster.

[0070] In some embodiments, Figure 5 and Figure 6 As shown, the sampling upper bridge arm circuit 1021 includes: an eleventh resistor R11, a twelfth resistor R12 and a switch S1; the sampling lower bridge arm circuit 1022 includes: a thirteenth resistor R13 and a fourteenth resistor R14;

[0071] One end of the eleventh resistor R11 is connected to the positive electrode of the battery cluster Vb; the other end of the eleventh resistor R11 is respectively connected to one end of the twelfth resistor R12 and one end of the switching switch S1; the other end of the switching switch S1 and the other end of the twelfth resistor R12 are connected to one end of the thirteenth resistor R13; the other end of the thirteenth resistor R13 is connected to the other end of the fourteenth resistor R14; the other end of the fourteenth resistor R14 is connected to the negative electrode of the battery cluster Vb.

[0072] It should be noted that in order to avoid the connection of the sampling resistor affecting the normal insulation of the circuit, the eleventh resistor R11 and the thirteenth resistor R13 should be selected to be large enough, and the resistance voltage capability needs to be greater than the voltage division of the energy storage system on the resistor; in specific applications, this can be achieved by connecting multiple high-voltage resistors in series.

[0073] It should also be noted that in Figure 5 and Figure 6 In the circuit shown, the fourteenth resistor R14 is used as a resistor in the second sampling unit 102 for sampling and obtaining the insulation voltage divided voltage, that is, a sampling resistor; when the insulation detection circuit of the energy storage system uses a digital-to-analog converter to realize insulation voltage divided voltage acquisition, the system's divided voltage on the fourteenth resistor R14 needs to meet the detection range of the digital-to-analog converter, that is, the insulation detection circuit should satisfy the following relationship: R14 / (R11+R12+R13+R14)*Vb_max<the range of the digital-to-analog converter; wherein Vb_max represents the maximum voltage of the battery cluster.

[0074] The insulation impedance detection unit 103 is used to obtain the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling circuit and the insulation voltage division sampling circuit; construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit 101 and the resistance of the second sampling unit 102, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

[0075] In practical applications, the insulation impedance detection unit can sample the voltage of the sampling resistors in the battery cluster voltage division sampling loop and the insulation voltage voltage division sampling loop, thereby obtaining the battery cluster voltage division and the insulation voltage division.

[0076] In some embodiments, the insulation impedance detection unit 103 may also be used to: control the actions of the sampling access switch S2 and the switching switch S1;

[0077] And / or, periodically executing the steps of obtaining the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling loop and the insulation voltage voltage division sampling loop; constructing an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solving the electrical balance equation group to obtain the insulation impedance of the energy storage system;

[0078] And / or, after the battery cluster Vb is connected to the energy storage system, the sampling access switch S2 is controlled to be disconnected.

[0079] It should be noted that, in the process of implementing insulation impedance detection, it is necessary to control the sampling access switch S2 and the switching switch S1 to meet different insulation detection circuit requirements; and in order to facilitate insulation impedance detection, the sampling access switch S2 and the switching switch S1 can be controlled by the insulation impedance detection unit 103.

[0080] In practical applications, periodically executing the insulation impedance detection step can ensure the accuracy of the insulation impedance detection results; in addition, it can also promptly detect any emergencies in the energy storage system.

[0081] It should also be noted that after the battery cluster Vb is connected to the energy storage system, that is, after the battery cluster Vb is connected to the energy storage converter (PCS), the sampling access switch S2 can be controlled to be disconnected, and the insulation detection circuit is prohibited from being connected to avoid affecting the insulation detection of the energy storage converter.

[0082] In some embodiments, Figure 1 , Figure 3 , Figure 5 As shown, the insulation impedance detection unit 103 may include: a digital-to-analog converter 1031, a first isolation chip 1032 and a first microcontroller 1033;

[0083] The digital-to-analog converter 1031 is connected to the first microcontroller 1033 via the first isolation chip 1032;

[0084] The digital-to-analog converter 1031 is used to collect the battery cluster voltage and the insulation voltage by using the battery cluster voltage sampling circuit and the insulation voltage sampling circuit, and convert the collected battery cluster voltage and the insulation voltage from digital signals to analog signals;

[0085] In practical applications, such as Figure 1 , Figure 3 , Figure 5As shown, the sampling reference point of the digital-to-analog converter is connected to the common connection point of the resistor used for collecting the battery cluster voltage division in the first sampling unit 101 and the resistor used for collecting the insulation voltage division in the second sampling unit 102; a sampling input point of the digital-to-analog converter 1031 is connected to the other end of the resistor used for collecting the battery cluster voltage division in the first sampling unit 101, and the second sampling input point of the digital-to-analog converter 1031 is connected to the other end of the resistor used for collecting the insulation voltage division in the second sampling unit 102.

[0086] By connecting in the above manner, the digital-to-analog converter 1031 can collect the battery cluster voltage division and the insulation voltage division for constructing the electrical balance equation group about the battery cluster to the casing equivalent insulation resistance.

[0087] The first isolation chip 1032 is used to isolate the digital-to-analog converter 1031 located at the high-voltage side of the system and the first microcontroller 1033 located at the low-voltage side of the system;

[0088] In practical applications, since the digital-to-analog converter 1031 is a high-voltage side device of the system, and the first microcontroller 1033 is a low-voltage side device of the system, the two are devices with a relatively high potential difference. In order to ensure effective communication between the two, improve the safety of the insulation detection circuit of the energy storage system, and protect the safety of electronic control equipment and operators, it is necessary to connect a first isolation chip between the two.

[0089] It should be noted that the specific selection of the first isolation chip 1032 may be determined according to the application environment and user requirements, including but not limited to digital chips.

[0090] The first microcontroller 1033 is used to construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

[0091] Among them, the first microcontroller 1031 can be an MCU (Microcontroller Unit), or a host computer, a computer or a processor with data processing functions, etc., which can be determined according to the application environment and user needs, and are all within the protection scope of this application.

[0092] It should be noted that the first microcontroller 1031 is mainly used to control the insulation impedance circuit to implement the insulation impedance detection logic in the insulation impedance detection of the energy storage system, so as to obtain the insulation impedance of the energy storage system.

[0093] In practical applications, the electrical balance equations for the equivalent insulation resistance of the battery cluster to the housing mainly include: a first battery cluster voltage balance equation, a first insulation voltage balance equation, a second battery cluster voltage balance equation, and a second insulation voltage balance equation;

[0094] The first battery cluster voltage balance equation is constructed according to the first battery cluster voltage division and the resistance of the first sampling unit, and the first insulation voltage balance equation is constructed according to the first insulation voltage division, the resistance of the second sampling unit and the equivalent insulation resistance of the battery cluster to the casing; the first battery cluster voltage division and the first insulation voltage division are obtained by sampling when the sampling access switch S2 is in a closed state, the switching switch S1 is in an open state, and the insulation voltage division sampling loop is in a steady-state equilibrium state;

[0095] A second battery cluster voltage balance equation is constructed according to the second battery cluster voltage division and the resistance of the first sampling unit, and a second insulation voltage balance equation is constructed according to the second insulation voltage division, the resistance of the second sampling unit and the equivalent insulation resistance of the battery cluster to the casing; the second battery cluster voltage division and the second insulation voltage division are obtained by sampling when the sampling access switch S2 is in a closed state, the switching switch S1 is in a conducting state, and the insulation voltage division sampling loop is in a steady-state equilibrium state.

[0096] It can be understood that the electrical balance equation group includes two sets of voltage balance equations, and the insulation detection circuits of the energy storage systems corresponding to the two sets of voltage balance equations have the same battery cluster voltage division sampling circuit formed by the first sampling unit 101 and the different insulation voltage division sampling circuits formed by the second sampling unit 102.

[0097] It should be noted that the insulation voltage voltage division sampling circuit is in a steady-state equilibrium state when: after the switching switch S1 in the insulation voltage voltage division sampling circuit performs the switching action, the insulation detection circuit of the energy storage system meets the voltage balance state. Since the insulation voltage voltage division sampling circuit will change after the switching switch S1 is controlled to perform the switching action, the voltage of the insulation detection circuit will also change during the switching process. In order to ensure the accuracy of the insulation impedance finally detected, the sampling of the battery cluster voltage division and the insulation voltage division needs to be performed when the insulation detection circuit meets the voltage balance state.

[0098] It should also be noted that the steady-state time required for the insulation detection circuit to meet the voltage balance state after the switch S1 is actuated can be determined in combination with the RC discharge curve in the insulation detection circuit. The steady-state time required for the insulation detection circuit to meet the voltage balance state is different when the switch S1 is in different states.

[0099] In some embodiments, Figure 2 , Figure 4 , Figure 6As shown, the insulation impedance detection unit 103 may include: a second isolation chip 1034, a third isolation chip 1037, a first operational amplifier circuit 1035, a second operational amplifier circuit 1038 and a second microcontroller 1036;

[0100] The second isolation chip 1034 is connected to the second microcontroller 1036 via the first operational amplifier circuit 1035 , and the third isolation chip 1037 is connected to the second microcontroller 1036 via the second operational amplifier circuit 1038 ;

[0101] The second isolation chip 1034 is used to isolate the first sampling unit 101 located at the high voltage side of the system and the first operational amplifier circuit 1035 located at the low voltage side of the system;

[0102] The third isolation chip 1037 is used to isolate the second sampling unit 102 located at the high voltage side of the system and the second operational amplifier circuit 1038 located at the low voltage side of the system;

[0103] The first operational amplifier circuit 1035 is used to amplify the battery cluster divided voltage in the battery cluster divided voltage sampling loop;

[0104] The second operational amplifier circuit 1038 is used to amplify the insulation voltage division in the insulation voltage division sampling loop;

[0105] Since the first operational amplifier circuit 1035 and the second operational amplifier circuit 1038 are low-voltage side devices of the system, and the first sampling unit 101 and the second sampling unit 102 are high-voltage side devices of the system, the potential difference between the two is relatively high. In order to ensure that the operational amplifier circuit effectively amplifies the battery cluster voltage division and the insulation voltage division, improve the safety of the insulation detection circuit of the energy storage system, and protect the safety of electronic control equipment and operators, it is necessary to connect the first isolation chip 1034 between the first sampling unit 101 and the first operational amplifier circuit 1035, and connect the second isolation chip 1037 between the second sampling unit 102 and the second operational amplifier circuit 1038.

[0106] In a specific application, the specific selection of the second isolation chip 1034 and the third isolation chip 1037 may be determined according to the application environment and user requirements, including but not limited to isolation operational amplifiers.

[0107] The second microcontroller 1036 is used to sample the amplified battery cluster voltage division and insulation voltage, and construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the resistance of the first sampling unit 101, the resistance of the second sampling unit 102, the sampled battery cluster voltage division and insulation voltage, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

[0108] The specific selection of the second microcontroller 1036 may refer to the first microcontroller 1033 and will not be described in detail here.

[0109] It should be noted that the battery cluster voltage division and the insulation voltage division can be isolated and amplified by the second isolation chip 1034, the third isolation chip 1037, the first operational amplifier circuit 1035 and the second operational amplifier circuit 1038, and the digital-to-analog conversion module in the second microcontroller 1036 can be used for sampling to reduce the number of digital-to-analog converters used in the insulation detection circuit, thereby further reducing hardware costs.

[0110] It should also be noted that, in some embodiments, Figures 1 to 6 The resistors in the insulation detection circuit of the energy storage system shown can be an equivalent circuit structure; in specific applications, it can be achieved by connecting resistors in series to meet the withstand voltage requirements; and the bridge arm where the sampling resistor is located in the second sampling unit 102 is displayed as two equivalent resistors in order to highlight the voltage division for sampling by the digital-to-analog converter.

[0111] Based on the above principle, the insulation detection circuit of the energy storage system provided in this embodiment includes: a first sampling unit 101, a second sampling unit 102 and an insulation impedance detection unit 103; the first sampling unit 101 is used to form a battery cluster voltage division sampling circuit of a battery cluster in the energy storage system; the second sampling unit 102 is used to form an insulation voltage division sampling circuit of the battery cluster to the casing equivalent insulation resistance in the energy storage system, and the second sampling unit 102 includes: a sampling upper bridge arm circuit 1021, a sampling lower bridge arm circuit 1022 and a sampling access switch S2, the connection point between the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit 1022 is connected to the casing grounding point GND of the energy storage system through the sampling switch S2; one of the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit includes a switching switch, and the sampling upper bridge arm circuit 1021 and the sampling lower bridge arm circuit are in different states. The insulation voltage division sampling loop formed by the circuit 1022 is different; the insulation impedance detection unit 103 is used to obtain the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling loop and the insulation voltage division sampling loop; according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit 101 and the resistance of the second sampling unit 102, an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing is constructed, and the insulation impedance of the energy storage system is obtained by solving the electrical balance equation group. With the above structure, the present application only needs one digital-to-analog converter or a digital-to-analog conversion module in the microcontroller itself to realize the sampling of the battery cluster voltage division and the insulation voltage division, and only needs one switching switch tube using a PhotoMOS tube, so the detection cost is low; in addition, the present application uses the real-time collected battery cluster voltage division to calculate the insulation impedance, which can also avoid the calculation error caused by voltage fluctuation.

[0112] It is worth noting that compared with Figure 7 and Figure 8The existing insulation detection circuit shown in the figure only requires one digital-to-analog converter in the present application; and the battery cluster voltage division sampling circuit and the insulation voltage voltage division sampling circuit in the present application use fixed resistance voltage division, so the insulation impedance detection accuracy of the energy storage system is higher.

[0113] Based on the above, Figure 1 and Figure 2 Taking the insulation detection circuit of the energy storage system shown as an example, the operation logic of the insulation detection circuit may be as follows:

[0114] 1: When the battery cluster is not connected to the energy storage system, the sampling access switch is closed, the switching switch is opened, and after the first steady-state time t1 is met, the voltage is sampled through the digital-to-analog converter. The voltage division of the battery cluster is recorded as v1 (the voltage division of the sampling resistor in the first sampling unit 101), and the insulation impedance voltage division is recorded as u1 (the voltage division of the sampling resistor in the second sampling unit 102);

[0115] 2: Close the sampling access switch and the switching switch. After the second steady-state time t2 is met, the voltage is sampled through the digital-to-analog converter. The battery cluster voltage division is recorded as v2, and the insulation impedance voltage division is recorded as u2;

[0116] 3: Construct the electrical balance equations about the equivalent insulation resistance of the battery cluster to the chassis:

[0117]

[0118] Among them, the voltage balance equation of the first battery cluster is: The first insulation voltage balance equation is The voltage balance equation of the second battery cluster is: The second insulation voltage balance equation is:

[0119]

[0120] Solve the equations to calculate the equivalent insulation resistance Rp of the battery cluster to the chassis and the equivalent insulation resistance Rn of the battery cluster to the chassis:

[0121]

[0122] 4: Before the battery cluster is connected to the energy storage system, repeat steps 1 to 3 to perform periodic testing of insulation impedance.

[0123] 5: The battery cluster is connected to the energy storage system, the sampling access switch and the switching switch are disconnected, and the insulation detection circuit is prohibited from being connected to avoid affecting the insulation detection of the energy storage converter.

[0124] It should be noted that the specific values ​​of the first steady-state time t1 and the second steady-state time t2 are calculated as follows:

[0125]

[0126] It can be understood that the first steady-state time t1 and the second steady-state time t2 can be 5 times the RC discharge time in the edge detection circuit; of course, it is not limited to this, and can also be determined according to the application environment and user needs, all within the protection scope of this application.

[0127] It should be noted that if the insulation detection circuit of the energy storage system is Figure 3 and Figure 4 , the operation logic of the insulation detection circuit is the same as above, except that the electrical balance equations for the equivalent insulation resistance of the battery cluster to the chassis are different, specifically:

[0128]

[0129] Among them, the voltage balance equation of the first battery cluster is: The first insulation voltage balance equation is The voltage balance equation of the second battery cluster is: The second insulation voltage balance equation is:

[0130]

[0131] Solve the equations to calculate the equivalent insulation resistance Rp of the battery cluster to the chassis and the equivalent insulation resistance Rn of the battery cluster to the chassis:

[0132] .

[0134] It should be noted that if the insulation detection circuit of the energy storage system is Figure 5 and Figure 6 , the operation logic of the insulation detection circuit is the same as above, except that the electrical balance equations for the equivalent insulation resistance of the battery cluster to the chassis are different, specifically:

[0135]

[0136]

[0137] Among them, the voltage balance equation of the first battery cluster is: The first insulation voltage balance equation is The voltage balance equation of the second battery cluster is: The second insulation voltage balance equation is:

[0138]

[0139] Solve the equations to calculate the equivalent insulation resistance Rp of the battery cluster to the chassis and the equivalent insulation resistance Rn of the battery cluster to the chassis:

[0140]

[0141] It should be noted that the specific values ​​of the first steady-state time t1 and the second steady-state time t2 are calculated as follows:

[0142]

[0143] It should be noted that the operating logic of the insulation detection circuit provided in the present application uses the real-time sampling results of the battery cluster Vb to calculate the insulation value during the insulation impedance detection process, which can avoid the calculation error caused by voltage fluctuations; and, only one bridge arm is switched, that is, only a switching switch needs to be set in one sampling bridge arm circuit, and the control logic is simpler.

[0144] It should also be noted that the above-mentioned detection logic is only a specific example of the present application in practical application; in specific applications, it can also be modified in combination with specific application conditions and user needs, all within the scope of protection of the present application.

[0145] Based on the above embodiments, optionally, in another insulation detection circuit of an energy storage system provided in the present application, the insulation impedance detection unit 103 can also determine whether insulation failure occurs according to the insulation impedance of the energy storage system, and cut off power supply after determining that insulation failure occurs.

[0146] In practical applications, the insulation impedance detection unit 103 may also be used to generate a prompt signal after determining that the insulation fails.

[0147] This warning signal can be used to indicate insulation failure in the energy storage system so that relevant personnel can handle it in a timely manner.

[0148] The features recorded in the various embodiments in this specification can be replaced or combined with each other, and the same and similar parts between the various embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0149] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0150] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An insulation detection circuit for an energy storage system, characterized in that: include: A first sampling unit, a second sampling unit and an insulation impedance detection unit; The first sampling unit is used to form a battery cluster voltage division sampling circuit of the battery cluster in the energy storage system; The second sampling unit is used to form an insulation voltage division sampling loop of the battery cluster to the casing equivalent insulation resistance in the energy storage system, and the second sampling unit includes: a sampling upper bridge arm circuit, a sampling lower bridge arm circuit and a sampling access switch, and the connection point between the sampling upper bridge arm circuit and the sampling lower bridge arm circuit is connected to the casing grounding point of the energy storage system through the sampling access switch; one of the sampling upper bridge arm circuit and the sampling lower bridge arm circuit includes a switching switch, and the insulation voltage division sampling loop formed by the sampling upper bridge arm circuit and the sampling lower bridge arm circuit is different when the switching switch is in different states; The insulation impedance detection unit is used to obtain the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling circuit and the insulation voltage voltage division sampling circuit; construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

2. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The electrical balance equation group includes: a first battery cluster voltage balance equation, a first insulation voltage balance equation, a second battery cluster voltage balance equation, and a second insulation voltage balance equation; The first battery cluster voltage balance equation is constructed according to the first battery cluster voltage division and the resistance of the first sampling unit, and the first insulation voltage balance equation is constructed according to the first insulation voltage division, the resistance of the second sampling unit and the equivalent insulation resistance of the battery cluster to the housing; the first battery cluster voltage division and the first insulation voltage division are obtained by sampling when the sampling access switch is in a closed state, the switching switch is in an open state, and the insulation voltage division sampling loop is in a steady-state equilibrium state; The second battery cluster voltage balance equation is constructed according to the second battery cluster voltage division and the resistance of the first sampling unit, and the second insulation voltage balance equation is constructed according to the second insulation voltage division, the resistance of the second sampling unit and the equivalent insulation resistance of the battery cluster to the casing; the second battery cluster voltage division and the second insulation voltage division are obtained by sampling when the sampling access switch is in a closed state, the switching switch is in a conducting state, and the insulation voltage division sampling loop is in a steady-state equilibrium state.

3. The insulation detection circuit of the energy storage system according to claim 2, characterized in that: The insulation voltage division sampling circuit is in a steady-state equilibrium state including: After the switch in the insulation voltage division sampling loop performs a switching action, the insulation detection circuit of the energy storage system meets the voltage balance state.

4. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The insulation impedance detection unit comprises: a digital-to-analog converter, a first isolation chip and a first microcontroller; The digital-to-analog converter is connected to the first microcontroller via the first isolation chip; The digital-to-analog converter is used to collect the battery cluster divided voltage and the insulation voltage divided voltage by using the battery cluster divided voltage sampling circuit and the insulation voltage divided voltage sampling circuit, and convert the collected battery cluster divided voltage and the insulation voltage divided voltage from digital signals to analog signals; The first isolation chip is used to isolate the digital-to-analog converter located on the high-voltage side of the system and the first microcontroller located on the low-voltage side of the system; The first microcontroller is used to construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

5. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The insulation impedance detection unit includes: a second isolation chip, a third isolation chip, a first operational amplifier circuit, a second operational amplifier circuit and a second microcontroller; The second isolation chip is connected to the second microcontroller via the first operational amplifier circuit, and the third isolation chip is connected to the second microcontroller via the second operational amplifier circuit; The second isolation chip is used to isolate the first sampling unit located at the high voltage side of the system and the first operational amplifier circuit located at the low voltage side of the system; The third isolation chip is used to isolate the second sampling unit located at the high voltage side of the system and the second operational amplifier circuit located at the low voltage side of the system; The first operational amplifier circuit is used to amplify the battery cluster divided voltage in the battery cluster divided voltage sampling loop; The second operational amplifier circuit is used to amplify the insulation voltage division in the insulation voltage division sampling loop; The second microcontroller is used to sample the amplified battery cluster divided voltage and the insulation voltage, and construct an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the resistance of the first sampling unit, the resistance of the second sampling unit, the sampled battery cluster divided voltage and the insulation voltage, and solve the electrical balance equation group to obtain the insulation impedance of the energy storage system.

6. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The battery cluster sampling unit comprises: a first resistor and a second resistor; One end of the first resistor serves as a first end of the first sampling unit and is connected to the positive electrode of the battery cluster of the energy storage system; The other end of the first resistor is connected to one end of the second resistor; The other end of the second resistor serves as the second end of the first sampling unit and is connected to the negative electrode of the battery cluster.

7. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The sampling upper bridge arm circuit comprises: a third resistor, a fourth resistor and the switching switch; the sampling lower bridge arm circuit comprises: a fifth resistor and a sixth resistor; One end of the third resistor is connected to one end of the fourth resistor, and the connection point is connected to the positive electrode of the battery cluster; The other end of the fourth resistor is connected to one end of the switch, the other end of the switch is respectively connected to one end of the third resistor and one end of the fifth resistor, and the other end of the fifth resistor is connected to the negative electrode of the battery cluster through the sixth resistor.

8. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The sampling upper bridge arm circuit includes: a seventh resistor; the sampling lower bridge arm circuit includes: an eighth resistor, a ninth resistor, a tenth resistor and the switching switch; One end of the seventh resistor is connected to the positive electrode of the battery cluster; the other end of the seventh resistor is connected to one end of the eighth resistor and one end of the ninth resistor respectively; the other end of the eighth resistor is connected to one end of the tenth resistor; the other end of the ninth resistor is connected to one end of the switching switch; the other end of the switching switch is connected to the other end of the tenth resistor, and the connection point is connected to the negative electrode of the battery cluster.

9. The insulation detection circuit of the energy storage system according to claim 1, characterized in that: The sampling upper bridge arm circuit comprises: an eleventh resistor, a twelfth resistor and the switching switch; the sampling lower bridge arm circuit comprises: a thirteenth resistor and a fourteenth resistor; One end of the eleventh resistor is connected to the positive electrode of the battery cluster; the other end of the eleventh resistor is respectively connected to one end of the twelfth resistor and one end of the switching switch; the other end of the switching switch is connected to the other end of the twelfth resistor and one end of the thirteenth resistor; the other end of the thirteenth resistor is connected to the other end of the fourteenth resistor; the other end of the fourteenth resistor is connected to the negative electrode of the battery cluster.

10. The insulation detection circuit of the energy storage system according to any one of claims 1 to 9, characterized in that: The insulation impedance detection unit is also used to: control the actions of the sampling access switch and the switching switch; And / or, periodically executing the steps of obtaining the battery cluster voltage division and the insulation voltage division by using the battery cluster voltage division sampling loop and the insulation voltage voltage division sampling loop; constructing an electrical balance equation group about the equivalent insulation resistance of the battery cluster to the casing according to the battery cluster voltage division, the insulation voltage division, the resistance of the first sampling unit and the resistance of the second sampling unit, and solving the electrical balance equation group to obtain the insulation impedance of the energy storage system; And / or, after the battery cluster is connected to the energy storage system, the sampling access switch is controlled to be disconnected.

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