An insulation detection device and method in a multi-energy storage system series scenario

Abstract

The present application relates to the field of circuit performance detection, and more particularly to an insulation detection device and method in a multi-energy storage system series connection scenario, comprising: a signal processing module configured for a system composed of multiple energy storage subsystems divided into a head-end system, an intermediate system and a tail-end system, and multiple insulation detection modules connected one-to-one with the energy storage subsystems, each insulation detection module comprising a detection mode switching module, a voltage dividing module and a data sampling module, and the voltage dividing modules of all energy storage subsystems form an electrical connection loop with a switching unit; the on-off timing of all switching units is controlled according to a preset logic, the voltage sampling values of the voltage dividing modules of the head-end system under different detection modes are obtained through the data sampling module, and the signal processing module calculates the insulation impedance value of the total positive terminal and the total negative terminal to the casing accordingly. The present application can adapt to multiple energy storage subsystem series connection scenarios and accurately realize insulation impedance detection of the total positive terminal and the total negative terminal of the entire series connection system to the casing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit performance detection, in particular to an insulation detection device and method in a multi-energy storage system series connection scenario. BACKGROUND

[0002] In the field of energy storage, high-voltage energy storage systems with battery management systems (BMS) are the core equipment for realizing power storage, scheduling and efficient utilization, and their operation safety is directly related to the stable operation of the entire energy storage power station. Among them, the BMS needs to monitor the insulation impedance of the positive electrode (B+) of the battery to the case and the negative electrode (B-) of the battery to the case in real time. This link is the key to preventing safety accidents such as leakage, short circuit and even fire caused by insulation performance degradation, and is also a basic requirement for ensuring long-term reliable operation of the system.

[0003] In the scenario where a single energy storage system works independently, the existing insulation detection device can calculate the insulation impedance through preset voltage division resistor network, signal acquisition and operational amplification, etc. At this time, the circuit signal reference is stable, the detection error can be controlled within the engineering allowable range, and the safety monitoring requirements of the single system can be basically met.

[0004] However, with the improvement of capacity and voltage level requirements of energy storage application scenarios, multiple energy storage systems in series have become a common configuration (such as increasing the total output voltage of the system by series connection to adapt to high-voltage loads, or expanding the overall energy storage capacity to meet large-scale power supply requirements). However, in this series connection scenario, the existing insulation detection device has an insurmountable technical defect: not only does the detection error of the insulation impedance increase sharply, but the detection function also frequently fails or misreports, making it impossible for operation and maintenance personnel to accurately determine the actual insulation state of the series connection system, seriously weakening the system's safety protection capability, and even possibly causing unnecessary downtime or hidden safety hazards due to misjudgment.

[0005] Through analysis, the main causes of this problem include two points: first, multiple series connection energy storage systems need to connect the case grounding points to each other to ensure the uniformity of grounding, which destroys the signal reference of the insulation detection device under single system, making the voltage division signal and impedance feedback signal collected by the detection circuit lose stable reference, directly interfering with the calculation logic of the insulation impedance; second, after multiple systems are connected in series, the overall output voltage is significantly increased, and the excessively high voltage signal will exceed the rated working range of the core components such as voltage division resistors and isolation amplifiers in the original detection circuit, resulting in a decrease in the signal processing accuracy of the components, and even causing abnormal working state of the circuit, further aggravating the detection error or causing the detection function to fail.

[0006] In summary, the existing insulation detection device can only adapt to single system independent operation scene and cannot be compatible with the application requirement of multiple system series connection. There is no effective solution for the technical pain points of "ground potential interference" and "high voltage signal influence" in series connection scene. It is difficult to meet the safety monitoring requirement of large-scale energy storage system. Therefore, there is an urgent need for an insulation detection scheme which can adapt to single system and multiple system series connection scene and ensure detection accuracy in different ground potential environments. SUMMARY

[0007] Therefore, the technical problem to be solved by the present application is to overcome the problems that the existing energy storage system single system insulation detection error is controllable, but when multiple systems are connected in series, the detection error is large or even invalid and false due to the connection of the grounding point and the increase of the series voltage. In addition, the circuit is not applicable when the ground potential is different, and the insulation impedance of multiple systems cannot be measured.

[0008] To solve the above technical problems, the present application provides an insulation detection device in a multiple energy storage system series connection scene and a detection method thereof, wherein the insulation detection device comprises a signal processing module and a plurality of insulation detection modules, each insulation detection module corresponding to any one of the subsystems in the series energy storage system, comprising: a detection mode switching module, a voltage dividing module, a data sampling module, a positive terminal, a negative terminal and a ground terminal.

[0009] The positive terminal is connected to the positive terminal B+ of the battery pack in the corresponding subsystem, and the negative terminal is connected to the negative terminal B- of the battery pack in the corresponding subsystem. The ground terminal is connected to the battery case ground terminal EGND in the corresponding subsystem, and the ground terminals in all insulation detection modules are connected.

[0010] The detection mode switching module comprises a plurality of switch units, the plurality of switch units are connected with the voltage dividing module to form an electrical connection loop, the output end of the voltage dividing module is connected with the input end of the data sampling module, and the output end of the data sampling module is connected with the signal processing module.

[0011] The on-off state of the plurality of switch units of each insulation detection module is controlled, the voltage value on the voltage dividing module is collected through the corresponding data sampling module, and the position of the corresponding connected subsystem in the entire series energy storage system is determined according to the comparison result of the voltage value. The positive terminal of the insulation detection module corresponding to the first subsystem is connected to the total positive terminal of the series energy storage system, and the negative terminal of the insulation detection module corresponding to the last subsystem is connected to the total negative terminal of the series energy storage system.

[0012] By controlling the on-off time sequence of the plurality of switch units of all insulation detection modules according to preset time sequence control logic, the voltage sampling value of the voltage dividing module of the first subsystem corresponding insulation detection module is obtained in different on-off time sequence corresponding detection modes by the data sampling module of the first subsystem corresponding insulation detection module, and the insulation impedance value of the total positive terminal and the total negative terminal of the whole series energy storage system to the casing is calculated by the signal processing module according to the voltage sampling value.

[0013] In an embodiment of the present application, the detection mode switching module comprises a first switch unit, a second switch unit and a third switch unit, each switch unit comprising a relay, the voltage input end of the first relay in the first switch unit being connected to the positive terminal, the voltage output end of the second relay in the second switch unit being connected to the negative terminal, and the third relay in the third switch unit being connected to the ground terminal.

[0014] In an embodiment of the present application, the voltage dividing module comprises a first resistor, a second resistor, a third resistor and a fourth resistor, one end of the first resistor being connected to the voltage output end of the first relay, the other end being connected to the input end of the data sampling module and the second resistor; the other end of the second resistor being connected to the common connection point of the third resistor, the voltage input end of the third relay and the ground terminal of the data sampling module, the other end of the third resistor being connected to the voltage input end of the second relay; one end of the fourth resistor being connected to the ground terminal of the data sampling module, the other end being connected to the voltage output end of the second relay.

[0015] In an embodiment of the present application, the data sampling module is driven by a time sequence control signal, and according to the detection task requirement, the enable end is applied with a corresponding periodic level signal to control the sampling period.

[0016] In an embodiment of the present application, each switch unit comprises a driving unit, the input end of the first driving unit in the first switch unit receiving a first control signal, the control output end of the first driving unit being connected to the control terminal of the first relay; the input end of the second driving unit in the second switch unit receiving a second control signal, the control output end of the second driving unit being connected to the control terminal of the second relay; the third driving unit in the third switch unit receiving a third control signal, the control output end of the third driving unit being connected to the control terminal of the third relay.

[0017] In one embodiment of the present invention, the first driving unit includes a first NMOS transistor, a fifth resistor, and a sixth resistor. One end of the fifth resistor receives the first control signal, and the other end is connected to the gate of the first NMOS transistor and one end of the sixth resistor. The other end of the sixth resistor is connected to the source of the first NMOS transistor and grounded. The drain of the first NMOS transistor is connected to the control terminal of the first relay.

[0018] In one embodiment of the present invention, the second driving unit includes a second NMOS transistor, a seventh resistor, and an eighth resistor. One end of the seventh resistor receives the second control signal, and the other end is connected to the gate of the second NMOS transistor and one end of the eighth resistor. The other end of the eighth resistor is connected to the source of the second NMOS transistor and grounded. The drain of the second NMOS transistor is connected to the control terminal of the second relay.

[0019] In one embodiment of the present invention, the third driving unit includes a third NMOS transistor, a ninth resistor, and a tenth resistor. One end of the ninth resistor receives the third control signal, and the other end is connected to the gate of the third NMOS transistor and one end of the tenth resistor. The other end of the tenth resistor is connected to the source of the third NMOS transistor and grounded. The drain of the third NMOS transistor is connected to the control terminal of the third relay.

[0020] Furthermore, the present invention also provides a detection method applied to the insulation detection device, comprising the following steps:

[0021] Send the first set of timing control signals to each energy storage subsystem to control the switching units of all energy storage subsystems to close according to a predetermined logic, so that the voltage divider modules of all energy storage subsystems are connected in parallel between the total positive terminal of the series energy storage system and the common chassis ground terminal through the closed switches, and collect the voltage of the voltage divider module in the first subsystem and record it as the first detection voltage;

[0022] Send the second set of timing control signals to each energy storage subsystem to control the switching units of all energy storage subsystems to close according to a predetermined logic, so that the voltage divider modules of all energy storage subsystems are connected in parallel to the total negative terminal of the series energy storage system and the common chassis ground terminal through the closed switches, and collect the voltage of the voltage divider module in the first subsystem and record it as the second detection voltage;

[0023] Based on the first detection voltage and the second detection voltage, the insulation resistance values ​​of the total positive terminal and the total negative terminal of the series energy storage system to the chassis ground are calculated.

[0024] The insulation impedance value obtained by the solution is compared with the preset insulation safety threshold to obtain the insulation performance test results of the multi-energy storage system connected in series.

[0025] In an embodiment of the present application, the detection method further comprises a subsystem position determination step in the series energy storage system, as follows:

[0026] The adjacent subsystems in the series energy storage system establish a communication connection, all subsystems are started at the same time, and the two are confirmed to be in a detection state through interaction, and the synchronous switch control timing logic is established;

[0027] The detection mode switching module driving all subsystems is turned on to build a complete voltage sampling loop, including: closing the positive terminal side solid state relay to connect the positive terminal of each subsystem to the series main loop; closing the negative terminal side solid state relay to connect the negative terminal of each subsystem to the series main loop; closing the ground terminal side solid state relay to connect the voltage dividing module of each subsystem to the common ground terminal;

[0028] Each subsystem collects the output voltage of the voltage dividing module through its own data sampling module, and the voltage value reflects the potential state of the subsystem in the series loop; the subsystem outputting a preset non-zero value is determined as the series first end system, the specific ground side relay of the first end system is driven to be disconnected, the partial loop of the first end and the common ground is cut off, and the output voltage of the data sampling module of the remaining subsystem is collected again; the subsystem outputting a zero value is determined as the series end system, and the subsystem outputting a non-first end preset non-zero value and a non-end zero value is determined as a series intermediate system.

[0029] The above technical solutions of the present application have the following beneficial effects compared with the prior art:

[0030] The present application can adapt to the application scenario of multiple system series connection, effectively solving the problem of large insulation detection error or even invalidation and false alarm caused by the connection of grounding points and the increase of series voltage in the prior art; by setting multiple relays, cooperating with data sampling modules and voltage dividing modules and other components, and through the CAN communication between systems to realize cooperative control, the solid state relay is controlled in a specific sequence to build different detection loops to calculate insulation impedance, even in systems with different ground potentials, similar control logic and detection precision can be achieved as in single system, and the core technical problem of inaccurate measurement of insulation impedance in multiple system series connection is successfully solved. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments of the present application and in conjunction with the accompanying drawings.

[0032] Figure 1 is the basic principle block diagram of the insulation detection device of the single energy storage system provided in the embodiment of the present application;

[0033] Figure 2This is a schematic diagram of an insulation detection device for a single energy storage system provided in an embodiment of the present invention;

[0034] Figure 3 yes Figure 2 The circuit structure diagram of the insulation detection device shown is shown.

[0035] Figure 4 This is a schematic diagram of an insulation detection device structure provided in an embodiment of the present invention for a scenario in which multiple energy storage systems are connected in series.

[0036] Figure 5 Is with Figure 4 The diagram shows a flow chart of the insulation testing method adapted to the insulation testing device.

[0037] Figure 6 This is a schematic diagram of the circuit structure of the insulation detection device in the series operation scenario of the dual energy storage system provided in the embodiments of the present invention.

[0038] Explanation of reference numerals in the accompanying drawings: 1. Energy storage system; 11. First-end system; 12. Intermediate system; 13. End system; 10. Insulation detection module; 101. Detection mode switching module; 1011. First switching unit; 1012. Second switching unit; 1013. Third switching unit; 102. Voltage divider module; 103. Data sampling module; 20. Signal processing module. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0040] Figure 1 A schematic diagram of an insulation detection circuit for a single energy storage system is shown. In this circuit, the high-voltage positive terminal B+ and the negative terminal B- of energy storage system 1 constitute the total battery voltage. The chassis grounding terminal EGND is the system's safety grounding terminal. Under normal operating conditions, the high-voltage circuit (B+, B-) and the chassis must be electrically isolated through an insulating medium (such as the battery pack casing insulation material, the high-voltage cable insulation sheath, etc.) to prevent the high voltage from forming a leakage path to the chassis.

[0041] insulation resistance Essentially, it is the total equivalent impedance of the insulation layer and potential leakage path between the positive terminal B+ and the chassis ground terminal EGND, and the insulation impedance. Essentially, it is the total equivalent impedance of the insulation layer and potential leakage current path between the negative terminal B- and the chassis grounding terminal EGND. These two are the core parameters characterizing the insulation performance of the energy storage system.

[0042] according toFigure 1 circuit structure, when the cabinet ground terminal EGND is normally connected with the cabinet, the whole voltage dividing circuit is analyzed, and the total impedance thereof includes the upper half branch impedance and the lower half branch impedance , wherein , ;

[0043] According to Kirchhoff's voltage law, the circuit output voltage in this state is , This equation cannot be directly solved because it contains two unknown quantities, insulation impedance

[0044] To eliminate the coupling of unknown quantities, an auxiliary detection state is introduced: temporarily disconnect the cabinet ground terminal EGND from the cabinet, at this time , Because it is disconnected from the grounding circuit, the voltage dividing effect is lost, and the total impedance of the circuit is simplified to , and the circuit output voltage in this state is

[0045] Given the voltage dividing resistor , , , , the battery voltage , and the output voltage measured by a high-voltage multimeter or other equipment, the above two formulas are combined to form an equation group for solving, and the specific values of insulation impedance and are obtained; by comparing the insulation impedance , with the insulation impedance safety threshold corresponding to the energy storage system, the compliance of the insulation performance of the system can be determined.

[0046] Based on the insulation detection circuit principle of the single energy storage system described above, the embodiment provides an insulation detection device suitable for a single energy storage system (as shown in Figure 2 ), which improves the insulation detection precision through hardware architecture optimization. The circuit includes an insulation detection module 10 and a signal processing module 20, wherein the insulation detection module 10 includes a detection mode switching module 101, a voltage dividing module 102, and a data sampling module 103. The modules are connected through precise electrical connections to realize insulation detection functions. The specific structure and connection relationship are as follows:

[0047] The detection mode switching module 101 includes a plurality of switch units, and the core function thereof is to realize the on-off control and mode switching of the detection loop. The module is connected with the positive terminal B+, the negative terminal B- and the chassis ground terminal EGND of the energy storage system 1 through the plurality of switch units, so as to provide switchable path selection for the subsequent construction of the voltage division circuit, and ensure that the different detection scenarios of the positive terminal B+, the negative terminal B- and the chassis ground terminal EGND can be covered through the on-off timing adjustment of the switches.

[0048] The voltage division module 102 is connected with the plurality of switch units to form a closed electrical connection loop, and the output end of the voltage division module 102 is connected with the input end of the data sampling module 103. Under different on-off combinations of the plurality of switch units, the insulation impedance of the positive terminal B+, the negative terminal B- and the chassis ground terminal EGND of the energy storage system is converted into a measurable analog voltage signal, that is, through the impedance matching of the voltage division resistor network, the voltage signal amplitude is within the effective detection range of the data sampling module, so as to realize the linear conversion of the insulation impedance-voltage signal. The output end of the data sampling module 103 is connected with the signal processing module 20, and the sampled analog voltage signal is transmitted to the signal processing module 20.

[0049] By controlling the on-off timing of the plurality of switch units according to the preset control logic, the voltage signal of the voltage division module 102 under different detection modes corresponding to different on-off timings is obtained by the data sampling module 103, and the signal processing module 20 calculates the insulation impedance value of the positive terminal B+, the negative terminal B- and the chassis of the energy storage system 1 according to the voltage signal.

[0050] Further, as shown in Figure 3 The detection mode switching module 101 specifically includes a first switch unit 1011, a second switch unit 1012 and a third switch unit 1013, and each switch unit includes a relay and a driving unit. The driving unit converts a weak control signal into a strong electric driving signal to realize the precise control of the relay.

[0051] The first relay in the first switch unit 1011 is connected with the positive terminal B+ of the energy storage system 1, the second relay in the second switch unit 1012 is connected with the negative terminal B- of the energy storage system 1, and the third relay in the third switch unit 1013 is connected with the chassis ground terminal EGND of the energy storage system 1. Figure 3The voltage input terminal (pin 5) of the solid-state relay U1 is connected to the positive terminal B+. The input terminal of the first drive unit in the first switching unit 1011 receives the on / off signal CTR B+ of the solid-state relay U1. The control output terminal of the first drive unit is connected to the control terminal (pin 2) of the solid-state relay U1. By turning the solid-state relay U1 on or off, the path between the positive terminal B+ and the voltage divider module 102 is switched. That is, when the solid-state relay U1 is on, the positive terminal B+ is connected to the voltage divider circuit, providing positive power to the circuit; when the solid-state relay U1 is off, the positive terminal B+ is disconnected from the voltage divider circuit, avoiding signal interference in the non-detection state.

[0052] The second relay in the second switching unit 1012 ( Figure 3 The voltage output terminal (pin 4) of the solid-state relay U2 is connected to the negative terminal B-. The input terminal of the second drive unit in the second switching unit 1012 receives the on / off signal CTR B- of the solid-state relay U2. The control output terminal of the second drive unit is connected to the control terminal (pin 2) of the solid-state relay U2. The on / off state of the negative terminal B- and the voltage divider module 102 is controlled by the on / off state of the solid-state relay U2. When the solid-state relay U2 is on, the negative terminal B- is connected to the voltage divider circuit, forming a current path from the positive terminal B+ through the voltage divider module 102 to the negative terminal B-. When the solid-state relay U2 is off, the negative terminal B- is disconnected from the circuit, which can be used to detect the insulation status of the positive terminal B+ to the chassis ground terminal EGND, improving the flexibility of the detection mode.

[0053] The third relay in the third switching unit 1013 ( Figure 3 The solid-state relay U3 is connected to the chassis ground terminal EGND. The third drive unit in the third switch unit 1013 receives the on / off signal CTR E of the solid-state relay U3, and the control output terminal of the third drive unit is connected to the control terminal (pin 2) of the solid-state relay U3. When the solid-state relay U3 is on, the voltage divider circuit is electrically connected to the chassis ground terminal EGND, and the insulation resistance of the positive terminal B+ and the negative terminal B- to the chassis ground terminal EGND can be directly measured; when the solid-state relay U3 is off, it can be used to calibrate the zero drift error of the voltage divider module 102, further improving the detection accuracy.

[0054] The first driving unit comprises a first NMOS tube Q1, a fifth resistor R5 and a sixth resistor R6, one end of the fifth resistor R5 receives a on-off signal CTR B+ of the solid state relay U1, the other end is connected with the gate of the first NMOS tube Q1 and one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected with the source of the first NMOS tube Q1 and grounded GND; the drain of the first NMOS tube Q1 is connected with the control end (the second pin) of the solid state relay U1.

[0055] The second driving unit comprises a second NMOS tube Q2, a seventh resistor R7 and an eighth resistor R8, one end of the seventh resistor R7 receives a on-off signal CTR B- of the solid state relay U2, the other end is connected with the gate of the second NMOS tube Q2 and one end of the eighth resistor R8, the other end of the eighth resistor R8 is connected with the source of the second NMOS tube Q2 and grounded; the drain of the second NMOS tube Q2 is connected with the control end (the second pin) of the solid state relay U2.

[0056] The third driving unit comprises a third NMOS tube Q3, a ninth resistor R9 and a tenth resistor R10, one end of the ninth resistor R9 receives a on-off signal CTR E of the solid state relay U3, the other end is connected with the gate of the third NMOS tube Q3 and one end of the tenth resistor R10, the other end of the tenth resistor R10 is connected with the source of the third NMOS tube Q3 and grounded; the drain of the third NMOS tube Q3 is connected with the control end (the second pin) of the solid state relay U3.

[0057] When the control signal (CTR B+, CTR B-, CTR E) is invalid level (such as low level or suspended), the gate of the first NMOS tube Q1, the second NMOS tube Q2 and the third NMOS tube Q3 may produce suspended voltage due to external noise, parasitic capacitance coupling and other factors, which may cause the MOS tube to be misdirected on. In order to avoid this situation, the resistors R6-R10 reliably pull down the MOS tube gate voltage to the source level (i.e. ground level), so as to ensure that the gate-source voltage is always 0V when the control signal is invalid, and the MOS tube is in a completely cut-off state, which avoids the solid state relay (U1, U2, U3) from being abnormally turned on due to mis-triggering from the hardware level, and ensures the reliability of the circuit logic.

[0058] The data sampling module 103 is an isolation amplifier. The voltage dividing module 102 includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. One end of the first resistor R1 is connected to a voltage output end of the solid state relay U1, and the other end is connected to the second resistor R2 and an input end (VIN) of the data sampling module 103. The other end of the second resistor R2 is connected to a common connection point of the third resistor R3, a voltage input end (5th pin) of the solid state relay U3, and a ground end (GND1) of the data sampling module 103. The other end of the third resistor R3 is connected to a voltage input end (5th pin) of the solid state relay U2. One end of the fourth resistor R4 is connected to the ground end (GND1) of the data sampling module 103, and the other end is connected to a voltage output end (4th pin) of the solid state relay U2.

[0059] In addition, the power supply end VDD1 of the data sampling module 103 is connected to a 5V isolation power supply (SIG_5V), and at the same time, the ground level (SIG_5V_GND) is connected through the capacitor C1. The power supply end VDD2 is connected to a 3.3V power supply voltage to provide a working voltage, and at the same time, the VDD2 end is connected to the ground GND through the capacitor C2.

[0060] The enable end (SHTD) of the data sampling module 103 is connected to the ground end GND1, and is connected to the low-level SIG_5V_GND. When the SHTD end is connected to the low-level SIG_5V_GND, the data sampling module 103 is in a working state. According to the detection task requirement, a corresponding periodic working level is applied to the SHTD end of the data sampling module 103.

[0061] Optionally, the signal processing module 20 is a control end or an independent control chip of the energy storage system 1, including but not limited to a PLC controller or an embedded microcomputer processor. The positive differential signal output end (OUT1P) and the negative differential signal output end (OUT1N) of the data sampling module 103 are connected to the differential signal input end of the signal processing module 20, so as to realize differential transmission of the voltage sampling signal output by the voltage dividing module 102 to the signal processing module 20. This connection mode can effectively suppress common-mode interference and ensure the accuracy and stability of the sampling signal in the transmission process, thereby providing reliable data input for subsequent insulation impedance calculation.

[0062] Based on the above-mentioned insulation monitoring device of a single energy storage system, the embodiment further provides an insulation detection method applied to the device, and the implementation steps are as follows:

[0063] The on-off signals CTR B+, CTR B- and CTR E are received by the resistors R5, R7 and R9 respectively, so that the solid-state relay U1 and the solid-state relay U3 are in the on state, and the solid-state relay U2 is in the off state; in this state, after the circuit state is stable, the voltage signal across the second resistor R2 is collected by the data sampling module 103, and the voltage is recorded as :

[0064] ,

[0065] wherein, represents the insulation impedance of the casing relative to the positive terminal B+, represents the insulation impedance of the casing relative to the negative terminal B-, is the battery voltage;

[0066] The solid-state relay U1 and the solid-state relay U3 are kept in the on state, and the solid-state relay U2 is switched to the on state. After the circuit is stable, the voltage signal across the second resistor R2 is collected again by the data sampling module 103, and the voltage is recorded as :

[0067] wherein, represents the parallel resistance value of the third resistor R3 and the fourth resistor R4;

[0068] The above two formulas are combined to form a system of equations, which is solved in combination with the known voltage dividing resistors (R1-R4). The insulation impedance and can be obtained; the insulation impedance , is compared with the insulation impedance safety threshold corresponding to the energy storage system, and the compliance of the system insulation performance can be determined.

[0069] After further optimization design of the above-mentioned insulation detection device suitable for single energy storage system, the embodiment also provides an insulation detection device applied to a working scene of multiple energy storage systems in series, as shown in Figure 4 , which comprises a plurality of insulation detection modules 10 and a signal processing module 20. Each insulation detection module 10 is connected to any one of the subsystems in the series energy storage system, and comprises a detection mode switching module 101, a voltage dividing module 102, a data sampling module 103, a positive terminal, a negative terminal and a ground terminal. Preferably, the data sampling module 103 is an isolation amplifier.

[0070] The positive terminal is connected to the positive terminal B+ of the corresponding battery pack in the subsystem, the negative terminal is connected to the negative terminal B- of the corresponding battery pack in the subsystem, the ground terminal is connected to the ground terminal EGND of the battery pack shell in the corresponding subsystem, and the ground terminals in all insulation detection modules 10 are connected;

[0071] The detection mode switching module 101 includes a plurality of switch units, which are connected with the voltage division module 102 to form an electrical connection loop, the output end of the voltage division module 102 is connected with the input end of the data sampling module 103, and the output end of the data sampling module 103 is connected with the signal processing module 20;

[0072] The on-off state of the plurality of switch units of each insulation detection module 10 is controlled, the voltage value on the voltage division module 102 is collected through the corresponding data sampling module 103, and the position of the corresponding connected subsystem in the entire series energy storage system is determined according to the comparison result of the voltage value. The positive terminal of the first subsystem is connected to the total positive terminal of the series energy storage system, and the negative terminal of the last subsystem is connected to the total negative terminal of the series energy storage system. In this way, the series energy storage system is configured as a first-end system 11, an intermediate system 12 and an end system 13. The positive terminal B+ of the first-end system 11 is the total positive terminal of the series energy storage system, the negative terminal B- of the end system 13 is the total negative terminal of the series energy storage system, and the intermediate system is all energy storage subsystems between the first-end system 11 and the end system 13.

[0073] The on-off time sequence of the plurality of switch units of all insulation detection modules 10 is controlled according to the preset time sequence control logic, the voltage sampling value of the voltage division module 102 of the first-end system 11 in the corresponding detection mode under different on-off time sequences is obtained through the data sampling module of the insulation detection module of the first-end system 11, and the signal processing module 20 calculates the insulation impedance value of the total positive terminal and the total negative terminal of the entire series energy storage system to the shell according to the voltage sampling value.

[0074] Further, the insulation detection module 10 includes a voltage division module 102, a data sampling module 103 and a signal processing module 20. Figure 3The circuit principle shown is the same, the detection mode switching module 101 includes a first switching unit 1011, a second switching unit 1012 and a third switching unit 1013, each switching unit includes a relay, the voltage input end of the first relay in the first switching unit 1011 is connected to the positive end B+ of the energy storage subsystem, the voltage output end of the second relay in the second switching unit 1012 is connected to the negative end B- of the energy storage subsystem, and the third relay in the third switching unit 1013 is connected to the cabinet grounding point EGND of the energy storage subsystem, a voltage division circuit can be constructed to connect the reference potential of the cabinet ground, and the potential reference stability of the detection signal is ensured. In order to avoid signal interference caused by mechanical relay contact jitter, improve the reliability and response speed of the high-voltage circuit on-off, the first relay, the second relay and the third relay are preferably solid-state relays.

[0075] Specifically, the voltage division module 102 of the embodiment includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4, one end of the first resistor R1 is connected to the voltage output end of the first relay, for receiving the positive high-voltage signal output by the first relay, realizing preliminary voltage division and current limiting of the signal, and avoiding direct impact of the overvoltage on the subsequent module; the other end of the first resistor R1 is connected to the second resistor R2, forming a voltage division branch, and at the same time, connecting the input end of the data sampling module 103; the other end of the second resistor R2 is connected to the common connection point of the third resistor R3, the voltage input end of the third relay and the ground end (GND1) of the data sampling module 103, the other end of the third resistor R3 is connected to the voltage input end of the second relay; one end of the fourth resistor R4 is connected to the ground end of the data sampling module 103, and the other end is connected to the voltage output end of the second relay.

[0076] Further, each switching unit includes a driving unit, the input end of the first driving unit in the first switching unit 1011 receives a first control signal CTR B+, and the control output end of the first driving unit is connected to the control end of the first relay; the input end of the second driving unit in the second switching unit 1012 receives a second control signal CTR B-, and the control output end of the second driving unit is connected to the control end of the second relay; the third driving unit in the third switching unit 1013 receives a third control signal CTR E, and the control output end of the third driving unit is connected to the control end of the third relay.

[0077] In the embodiment, the first driving unit comprises a first NMOS tube Q1, a fifth resistor R5 and a sixth resistor R6, one end of the fifth resistor R5 receives the first control signal CTR B+, the other end of the fifth resistor R5 is connected with the gate of the first NMOS tube Q1 and one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected with the source of the first NMOS tube Q1 and grounded, and the drain of the first NMOS tube Q1 is connected with the control end of the first relay.

[0078] Further, in the embodiment, the second driving unit comprises a second NMOS tube Q2, a seventh resistor R7 and an eighth resistor R8, one end of the seventh resistor R7 receives the second control signal CTR B-, the other end of the seventh resistor R7 is connected with the gate of the second NMOS tube Q2 and one end of the eighth resistor R8, the other end of the eighth resistor R8 is connected with the source of the second NMOS tube Q2 and grounded, and the drain of the second NMOS tube Q2 is connected with the control end of the second relay.

[0079] Further, in the embodiment, the third driving unit comprises a third NMOS tube Q3, a ninth resistor R9 and a tenth resistor R10, one end of the ninth resistor R9 receives the third control signal CTR E, the other end of the ninth resistor R9 is connected with the gate of the third NMOS tube Q3 and one end of the tenth resistor R10, the other end of the tenth resistor R10 is connected with the source of the third NMOS tube Q3 and grounded, and the drain of the third NMOS tube Q3 is connected with the control end of the third relay.

[0080] In terms of technical implementation, the data sampling module 103 is an isolation amplifier, which is enabled by a timing control signal, and according to the specific requirements of the insulation detection task (such as single-system steady-state detection, multi-system series dynamic detection), a periodic level signal matching the requirements is applied to the enable end to realize accurate control of the sampling period of the module, and ensure the timing of voltage sampling and the logic of switch unit on-off.

[0081] In addition, for the signal processing module 20, the configuration selection can be divided into two categories: one is the built-in main control unit integrated with the series energy storage system, and the other is the external independent control chip deployed independently; the selection range of the module at least includes an industrial programmable logic controller (PLC) and an embedded microcomputer processor, and such carriers need to have signal operation, logic control and instruction output capabilities to meet the core functional requirements of insulation impedance calculation, switch unit control signal generation and detection result judgment.

[0082] In addition, as shown in Figure 5 The application further provides a detection method applied to the insulation detection device, which comprises the following steps:

[0083] The first group of timing control signals is sent to each energy storage subsystem through the CAN bus to control the switching units of all energy storage subsystems to close according to a predetermined logic, so that the voltage dividing modules 102 of all energy storage subsystems are connected in parallel between the total positive terminal of the series energy storage system and the common chassis ground terminal through the closed switches, and the voltage of the voltage dividing module 102 in the front-end system 11 is collected, which is recorded as the first detection voltage;

[0084] The second group of timing control signals is sent to each energy storage subsystem through the CAN bus to control the switching units of all energy storage subsystems to close according to a predetermined logic, so that the voltage dividing modules 102 of all energy storage subsystems are connected in parallel between the total negative terminal of the series energy storage system and the common chassis ground terminal through the closed switches, and the voltage of the voltage dividing module 102 in the front-end system 11 is collected, which is recorded as the second detection voltage;

[0085] Based on the first detection voltage and the second detection voltage, the insulation resistance values of the total positive terminal of the series energy storage system to the common chassis ground terminal and the total negative terminal to the common chassis ground terminal are calculated.

[0086] The calculated insulation impedance values are compared with the preset insulation safety threshold to obtain the insulation performance detection result of the series energy storage system.

[0087] Further, before performing insulation monitoring, a position determination step of the subsystems in the series energy storage system also needs to be performed, as follows:

[0088] The adjacent subsystems in the series energy storage system are connected through the CAN bus to complete device identity (ID) registration and state self-checking, all subsystems are started at the same time, and the two are confirmed to be in a detection state through interaction, and the switching control timing logic is synchronized.

[0089] The signal processing module 20 issues a position determination timing instruction to drive the detection mode switching module 101 of all subsystems to be fully turned on, thereby building a complete voltage sampling loop, including: closing the positive terminal B+ side solid-state relay to connect the positive terminal B+ of each subsystem to the series main circuit; closing the negative terminal B- side solid-state relay to connect the negative terminal B- of each subsystem to the series main circuit; and closing the ground terminal EGND side solid-state relay to connect the voltage dividing module 102 of each subsystem to the common ground terminal.

[0090] Each subsystem collects the output voltage of the voltage dividing module 102 through its own data sampling module 103, and the voltage value reflects the potential state of the subsystem in the series circuit.

[0091] Since the positive terminal B+ of the first subsystem is the total positive terminal of the entire series energy storage system, the complete voltage division signal of the series loop can be collected on the voltage division module 102 of the first subsystem, and the voltage value matches the preset first terminal reference voltage range, so the subsystem with a preset non-zero output is determined as the first terminal system 11.

[0092] After determining the first terminal system 11, the specific ground side relay of the first terminal system 11 is driven to cut off the partial loop of the first terminal and the common ground, and the output voltage of the data sampling module 103 of the remaining subsystem is collected again. Since the negative terminal B- of the last subsystem is the total negative terminal of the entire series energy storage system, its potential is consistent with the common ground EGND, and there is no voltage difference in the voltage division module 102, so the subsystem with zero output of the isolation amplifier is determined as the last terminal system 13.

[0093] The remaining subsystems are between the first terminal system 11 and the last terminal system 13, and the potential is between the total positive terminal and the total negative terminal of the series energy storage system. The voltage value collected by the voltage division module 102 is between the first terminal specific value and zero, and changes linearly with the series level, so the subsystem with a non-first terminal preset non-zero value and a non-last terminal zero value is determined as the middle system 12.

[0094] Each subsystem stores its own position information, which is used for subsequent switch control logic adaptation for insulation detection, such as the first terminal system 11 leading the voltage data sampling process and the last terminal system 13 cooperating to adjust the on-off of the ground relay.

[0095] Figure 6 The circuit structure schematic diagram of the insulation detection device in the series working scene of the double energy storage system is shown. The first relay, the second relay, and the third relay of the detection mode switching module 101 in the energy storage system one are solid-state relays U1, U2, and U3, respectively. The first relay, the second relay, and the third relay of the detection mode switching module 101 in the energy storage system two are solid-state relays U10, U20, and U30, respectively. The negative terminal B- of the energy storage system one and the positive terminal B+ of the energy storage system two are connected, and the chassis ground points EGND of the two systems are connected in common.

[0096] The energy storage system one and the energy storage system two are controlled to start at the same time through the CAN bus, and the basic information such as device ID and hardware state is exchanged through CAN communication to confirm that both are in a normal state for detection, and the switch control timing logic is synchronized.

[0097] According to the preset logic, all detection mode switching modules 101 of the two subsystems are turned on: including B+ side relays (such as solid-state relay U1 in system 1 and solid-state relay U10 in system 2), B- side relays (such as solid-state relay U2 in system 1 and solid-state relay U20 in system 2), and ground side relays (such as solid-state relay U3 in system 1 and solid-state relay U30 in system 2), to construct a complete voltage sampling circuit.

[0098] The output voltage signals of the corresponding voltage divider modules 102 are collected by the isolation amplifier U4 in System 1 and the isolation amplifier U40 in System 2. If the isolation amplifier of a certain subsystem outputs a preset non-zero value, the subsystem is determined to be the first-end system in a series connection, and its positive terminal (B+) is the total positive terminal of the entire series energy storage system; if the isolation amplifier of another subsystem outputs a zero value, the subsystem is determined to be the last-end system in a series connection, and its negative terminal (B-) is the total negative terminal of the entire series energy storage system.

[0099] Solid-state relays U1 and U3 in control system 1 and solid-state relay U30 in system 2 are in the ON state. Solid-state relays U2 in system 1 and U10 and U20 in system 2 are closed. The voltage across the voltage divider resistor R2 is collected using isolation amplifier U4 and denoted as [the voltage is then described]. According to Kirchhoff's voltage law, we can obtain:

[0100] ;

[0101] Solid-state relays U1 and U3 in control system 1, and solid-state relays U30 and U20 in system 2 are in the ON state. When solid-state relays U2 in system 1 and U10 in system 2 are closed, the voltage across the voltage divider resistor R2 is collected using isolation amplifier U4 and denoted as . According to Kirchhoff's voltage law, we can obtain:

[0102] ;

[0103] By combining the two formulas above to construct a system of equations, and then solving the system using the known voltage divider resistors (R1~R4), the insulation resistance can be obtained. and The specific value; the insulation resistance , By comparing the insulation impedance with the safety threshold corresponding to the energy storage system, the compliance of the system's insulation performance can be determined.

[0104] Obviously, the above embodiments are merely example for clearly illustrating, and are not limitation to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and can not be exhausted. The obvious changes or variations derived therefrom are still within the scope of the present invention.

Claims

1. An insulation testing device for a multi-energy storage system series scenario, characterized in that, It includes a signal processing module and multiple insulation detection modules. Each insulation detection module is connected to any subsystem in the series energy storage system and includes: a detection mode switching module, a voltage divider module, a data sampling module, a positive terminal, a negative terminal, and a grounding terminal. Wherein, the positive terminal is connected to the positive terminal B+ of the battery pack in the corresponding subsystem, and the negative terminal is connected to the negative terminal B- of the battery pack in the corresponding subsystem; the grounding terminal is connected to the battery pack housing grounding terminal EGND in the corresponding subsystem, and the grounding terminals in all insulation detection modules are connected. The detection mode switching module includes multiple switching units, which are connected to the voltage divider module to form an electrical connection loop. The output terminal of the voltage divider module is connected to the input terminal of the data sampling module, and the output terminal of the data sampling module is connected to the signal processing module. The on / off state of multiple switching units of each insulation detection module is controlled. The voltage value on the voltage divider module is collected by the corresponding data sampling module. The position of the corresponding subsystem in the whole series energy storage system is determined according to the comparison result of the voltage value. The positive terminal of the insulation detection module corresponding to the first subsystem is connected to the total positive terminal of the series energy storage system, and the negative terminal of the insulation detection module corresponding to the last subsystem is connected to the total negative terminal of the series energy storage system. By controlling the on / off timing of multiple switching units of all insulation detection modules according to preset timing control logic, the data sampling module of the insulation detection module corresponding to the first subsystem obtains the voltage sampling value of its voltage divider module in the detection mode corresponding to different on / off timing. The signal processing module calculates the insulation impedance value of the total positive terminal and the total negative terminal of the entire series energy storage system to the casing based on the voltage sampling value.

2. The insulation testing device according to claim 1, characterized in that, The detection mode switching module includes a first switch unit, a second switch unit, and a third switch unit. Each switch unit includes a relay. The voltage input terminal of the first relay in the first switch unit is connected to the positive terminal. The voltage output terminal of the second relay in the second switch unit is connected to the negative terminal. The third relay in the third switch unit is connected to the ground terminal.

3. The insulation testing device according to claim 2, characterized in that, The voltage divider module includes a first resistor, a second resistor, a third resistor, and a fourth resistor. One end of the first resistor is connected to the voltage output terminal of the first relay, and the other end is connected to the second resistor and the input terminal of the data sampling module. The other end of the second resistor is connected to the common connection point of the third resistor, the voltage input terminal of the third relay, and the ground terminal of the data sampling module. The other end of the third resistor is connected to the voltage input terminal of the second relay. One end of the fourth resistor is connected to the ground terminal of the data sampling module, and the other end is connected to the voltage output terminal of the second relay.

4. The insulation testing device according to claim 3, characterized in that, The data sampling module is driven by a timing control signal. According to the detection task requirements, its enable terminal is applied with a corresponding periodic level signal to control its sampling period.

5. The insulation testing device according to claim 2, characterized in that, Each switching unit includes a driving unit. The input terminal of the first driving unit in the first switching unit receives a first control signal, and the control output terminal of the first driving unit is connected to the control terminal of the first relay. The input terminal of the second driving unit in the second switching unit receives a second control signal, and the control output terminal of the second driving unit is connected to the control terminal of the second relay. The third driving unit in the third switching unit receives a third control signal, and the control output terminal of the third driving unit is connected to the control terminal of the third relay.

6. The insulation testing device according to claim 5, characterized in that, The first driving unit includes a first NMOS transistor, a fifth resistor, and a sixth resistor. One end of the fifth resistor receives the first control signal, and the other end is connected to the gate of the first NMOS transistor and one end of the sixth resistor. The other end of the sixth resistor is connected to the source of the first NMOS transistor and grounded. The drain of the first NMOS transistor is connected to the control terminal of the first relay.

7. The insulation testing device according to claim 5, characterized in that, The second driving unit includes a second NMOS transistor, a seventh resistor, and an eighth resistor. One end of the seventh resistor receives the second control signal, and the other end is connected to the gate of the second NMOS transistor and one end of the eighth resistor. The other end of the eighth resistor is connected to the source of the second NMOS transistor and grounded. The drain of the second NMOS transistor is connected to the control terminal of the second relay.

8. The insulation testing device according to claim 5, characterized in that, The third driving unit includes a third NMOS transistor, a ninth resistor, and a tenth resistor. One end of the ninth resistor receives the third control signal, and the other end is connected to the gate of the third NMOS transistor and one end of the tenth resistor. The other end of the tenth resistor is connected to the source of the third NMOS transistor and grounded. The drain of the third NMOS transistor is connected to the control terminal of the third relay.

9. A detection method for an insulation testing device as described in any one of claims 1 to 8, characterized in that, include: Send the first set of timing control signals to each energy storage subsystem to control the switching units of all energy storage subsystems to close according to a predetermined logic, so that the voltage divider modules of all energy storage subsystems are connected in parallel between the total positive terminal of the series energy storage system and the common chassis ground terminal through the closed switches, and collect the voltage of the voltage divider module in the first subsystem and record it as the first detection voltage; Send the second set of timing control signals to each energy storage subsystem to control the switching units of all energy storage subsystems to close according to a predetermined logic, so that the voltage divider modules of all energy storage subsystems are connected in parallel to the total negative terminal of the series energy storage system and the common chassis ground terminal through the closed switches, and collect the voltage of the voltage divider module in the first subsystem and record it as the second detection voltage; Based on the first detection voltage and the second detection voltage, the insulation resistance values ​​of the total positive terminal and the total negative terminal of the series energy storage system to the common chassis grounding terminal are calculated. The insulation impedance value obtained by the solution is compared with the preset insulation safety threshold to obtain the insulation performance test results of the series energy storage system.

10. The detection method according to claim 9, characterized in that, It also includes the subsystem location determination step in the series energy storage system, as follows: In the series energy storage system, each adjacent subsystem establishes a communication connection, all subsystems are powered on at the same time, and the two are confirmed to be in a state of waiting for detection through interaction, and the timing logic of synchronous switch control is used. The detection mode switching modules of all subsystems are turned on to construct a complete voltage sampling circuit, including: closing the solid-state relay on the positive terminal B+ side to connect the positive terminal of each subsystem to the series main circuit; closing the solid-state relay on the negative terminal B- side to connect the negative terminal of each subsystem to the series main circuit. Close the solid-state relay on the GND side of the grounding terminal to connect the voltage divider modules of each subsystem to the common ground terminal; Each subsystem acquires the output voltage of the voltage divider module through its own data sampling module. This voltage value reflects the potential state of the subsystem in the series circuit. Subsystems with preset non-zero output values ​​are identified as the first-end system in the series circuit. The designated grounding relay of the first-end system is driven to disconnect, cutting off the part of the circuit between the first end and the common ground. The output voltage of the data sampling modules of the remaining subsystems is acquired again. Subsystems with zero output values ​​are identified as the last-end system in the series circuit. The remaining subsystems with output values ​​that are neither the preset non-zero value of the first end nor the zero value of the last end are identified as intermediate systems in the series circuit.

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