Insulation detection method and circuit

Abstract

This application discloses an insulation detection method and circuit. The insulation detection method includes the following steps: controlling a relay to close or open according to a drive signal, such that the combination of at least two relays opening and closing includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value; acquiring the voltage of a target resistor in each output state, wherein, when the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage; determining the equivalent insulation resistance based on the voltage of the target resistor; and determining the insulation detection result based on the equivalent insulation resistance. This insulation detection method can improve the measurement accuracy of insulation resistance.

Description

Technical Field

[0001] This application relates to the field of insulation testing technology, and in particular to an insulation testing method and circuit. Background Technology

[0002] Both energy storage battery clusters and the DC side of energy storage converters contain Y-capacitors. Currently, when using the half-bridge method to measure insulation resistance, it is necessary to switch the resistances of the positive and negative bridge arms, resulting in the charging and discharging of the Y-capacitors. Since the Y-capacitors in electric vehicle battery systems are smaller than those in large-scale electrochemical energy storage, using the same insulation testing methods as for electric vehicles would lead to premature detection and inaccurate insulation resistance measurements. Summary of the Invention

[0003] In view of this, embodiments of this application provide an insulation detection method and circuit to solve the problem of premature insulation detection in energy storage systems, which leads to inaccurate measurement of insulation resistance.

[0004] In a first aspect, embodiments of this application provide an insulation detection method, including:

[0005] The relays are controlled to close or open according to the drive signal, such that the combination of opening and closing of at least two of the relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value.

[0006] In each of the output states, the voltage of the target resistor is acquired, wherein when the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage.

[0007] The equivalent insulation resistance is determined based on the voltage across the target resistor;

[0008] The insulation test results are determined based on the equivalent insulation resistance.

[0009] In this application, the insulation detection method controls the closing or opening of a relay by a drive signal, so that the voltage of the target resistor is collected in three different output states by the combination of relay opening and closing. Furthermore, during the switching process, the voltage change on the Y capacitor is reduced by the different compensation voltages corresponding to the three different output states, thereby reducing the voltage stabilization time, reducing the insulation detection time, and improving the measurement accuracy of insulation resistance.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the relay is an optocoupler relay, and the number of the optocoupler relays is four. The relays are controlled to close or open according to a drive signal, such that combinations of at least two of the relays being open or closed include three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value.

[0011] When the third and fourth optocoupler relays are closed according to the drive signal, and the first and second optocoupler relays are opened, the output state is the third compensation voltage that outputs the zero value;

[0012] When the first optocoupler relay and the third optocoupler relay are closed according to the driving signal, and the second optocoupler relay and the fourth optocoupler relay are opened, the output state is to output the first compensation voltage in the positive direction;

[0013] When the second optocoupler relay and the fourth optocoupler relay are closed according to the driving signal, and the first optocoupler relay and the third optocoupler relay are opened, the output state is to output the second compensation voltage in the negative direction.

[0014] This application provides a combined embodiment of optocoupler relays that can achieve multiple output states. In the insulation detection circuit, multiple optocoupler relays can be set to achieve different output states, and the first compensation voltage or the second compensation voltage in the output state can be used to compensate the Y capacitor of the energy storage battery cluster, thereby improving the accuracy of insulation resistance detection.

[0015] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the first optocoupler relay and the third optocoupler relay are connected in a dual-bridge-arm manner, and the second optocoupler relay and the fourth optocoupler relay are connected in the same dual-bridge-arm manner. Specifically, the first port of the first optocoupler relay is connected to the first bridge arm, the second port of the first optocoupler relay is connected to the first port of the second optocoupler relay, the second port of the second optocoupler relay is connected to the second bridge arm, the third bridge arm is divided into a first upper bridge arm and a first lower bridge arm, and the fourth bridge arm is divided into a second upper bridge arm and a second lower bridge arm. The first upper bridge arm and the second lower bridge arm have the same resistance value, the first lower bridge arm and the second upper bridge arm have the same resistance value, the first port of the third optocoupler relay is connected to the first upper bridge arm, the second port of the third optocoupler relay is connected to the first lower bridge arm, the first port of the fourth optocoupler relay is connected to the second upper bridge arm, and the second port of the fourth optocoupler relay is connected to the second lower bridge arm.

[0016] This application provides an insulation detection circuit consisting of multiple optocoupler relays and a bridge arm structure for calculating the equivalent insulation resistance. The first lower bridge arm and the second upper bridge arm serve as resistors for the voltage to be detected. Voltage acquisition is achieved based on these first lower bridge arms and second upper bridge arms under different output states, and the equivalent insulation resistance is calculated from the voltage acquisition results.

[0017] In addition to the aspects and any possible implementations described above, an implementation is further provided in which acquiring the voltage of the target resistor in each of the said output states includes:

[0018] When the output state is the first compensation voltage in the positive direction, the first lower bridge arm is used as the target resistor and the voltage is collected;

[0019] When the output state is the second compensation voltage in the negative direction, the second upper bridge arm is used as the target resistor and the voltage is acquired;

[0020] When the output state is zero, the third compensation voltage uses the first lower bridge arm and the second upper bridge arm connected in series as the target resistor and the voltage is acquired.

[0021] In this application, a target resistor can be selected and its voltage can be acquired under different output states. The equivalent insulation resistance can then be obtained based on the acquired voltage of the target resistor.

[0022] In addition to the aspects described above and any possible implementations, an implementation is further provided in which, after determining the equivalent insulation resistance based on the voltage of the target resistor, the method further includes:

[0023] The location of the cell with insulation fault is determined based on the equivalent insulation resistance.

[0024] In this application, when an insulation fault occurs between an intermediate cell and ground, the location of the cell with the insulation fault can be determined by the equivalent insulation resistance, thereby determining the insulation test result.

[0025] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the optocoupler relay employs a transistor structure and drives the optocoupler according to the drive signal.

[0026] In this application, the optocoupler relay adopts a transistor structure that can quickly respond to the drive signal, so as to quickly drive the optocoupler according to the drive signal and realize the rapid switching of the relay opening and closing combination.

[0027] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the drive signal is issued via a microcontroller connected to the base of the transistor.

[0028] In this application, a microcontroller is incorporated into the circuit. This microcontroller can receive instructions from a host computer, such as instructions to issue drive signals. There are various combinations of relay opening and closing; the microcontroller can receive instructions representing different drive signals, enabling more accurate and faster switching of each relay's opening and closing.

[0029] In addition to the aspects described above and any possible implementations, a further implementation is provided in which an isolation amplifier is used to acquire the voltage of the target resistor, and the voltage of the target resistor is input to the microcontroller after analog-to-digital conversion.

[0030] In this application, the microcontroller can not only send drive signals, but also receive the voltage signal of the target resistor after analog-to-digital conversion, thereby accurately determining the voltage magnitude of the current target resistor and effectively improving the accuracy of insulation detection.

[0031] Secondly, embodiments of this application provide an insulation detection circuit, including:

[0032] Energy storage battery clusters, and Y capacitors corresponding to the energy storage battery clusters;

[0033] Equivalent insulation resistance is used to detect the insulation condition of a circuit.

[0034] Insulation detection module, used for:

[0035] The relays are controlled to close or open according to the drive signal, such that the combination of opening and closing of at least two of the relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value.

[0036] In each of the output states, the voltage of the target resistor is acquired, wherein when the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage.

[0037] The equivalent insulation resistance is determined based on the voltage across the target resistor;

[0038] The insulation test result is determined based on the equivalent insulation resistance.

[0039] The DC side of the energy storage converter, and the Y capacitor corresponding to the DC side of the energy storage converter.

[0040] Furthermore, the relay is an optocoupler relay, and the number of the optocoupler relays is four.

[0041] Furthermore, the insulation detection module is also used for:

[0042] When the third and fourth optocoupler relays are closed according to the drive signal, and the first and second optocoupler relays are opened, the output state is the third compensation voltage that outputs the zero value;

[0043] When the first optocoupler relay and the third optocoupler relay are closed according to the driving signal, and the second optocoupler relay and the fourth optocoupler relay are opened, the output state is to output the first compensation voltage in the positive direction;

[0044] When the second optocoupler relay and the fourth optocoupler relay are closed according to the driving signal, and the first optocoupler relay and the third optocoupler relay are opened, the output state is to output the second compensation voltage in the negative direction.

[0045] Furthermore, the first optocoupler relay and the third optocoupler relay are connected in a dual-bridge-arm configuration, as are the second optocoupler relay and the fourth optocoupler relay. Specifically, the first port of the first optocoupler relay is connected to the first bridge arm, the second port of the first optocoupler relay is connected to the first port of the second optocoupler relay, the second port of the second optocoupler relay is connected to the second bridge arm, the third bridge arm is divided into a first upper bridge arm and a first lower bridge arm, and the fourth bridge arm is divided into a second upper bridge arm and a second lower bridge arm. The first upper bridge arm and the second lower bridge arm have the same resistance value, and the first lower bridge arm and the second upper bridge arm have the same resistance value. The first port of the third optocoupler relay is connected to the first upper bridge arm, the second port of the third optocoupler relay is connected to the first lower bridge arm, the first port of the fourth optocoupler relay is connected to the second upper bridge arm, and the second port of the fourth optocoupler relay is connected to the second lower bridge arm.

[0046] Furthermore, the insulation detection module is also used for:

[0047] When the output state is the first compensation voltage in the positive direction, the first lower bridge arm is used as the target resistor and the voltage is collected;

[0048] When the output state is the second compensation voltage in the negative direction, the second upper bridge arm is used as the target resistor and the voltage is acquired;

[0049] When the output state is zero, the third compensation voltage uses the first lower bridge arm and the second upper bridge arm connected in series as the target resistor and the voltage is acquired.

[0050] Furthermore, the insulation detection module is also used for:

[0051] The cell with insulation failure is determined based on the equivalent insulation resistance.

[0052] Furthermore, the optocoupler relay adopts a transistor structure and drives the optocoupler according to the drive signal.

[0053] Furthermore, the drive signal is issued through a microcontroller, which is connected to the base of the transistor.

[0054] Furthermore, an isolation amplifier is used to acquire the voltage of the target resistor, and the voltage of the target resistor is input to the microcontroller after analog-to-digital conversion.

[0055] Furthermore, the insulation detection circuit also includes a high-voltage positive relay and a high-voltage negative relay.

[0056] In this embodiment, the closing or opening of relays is controlled by a drive signal, so that the combination of opening and closing of at least two relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value. The voltage of the target resistor is collected in each output state, so as to determine the equivalent insulation resistance by switching between various output states, thereby achieving the purpose of insulation detection. This provides a new insulation detection method. Furthermore, during the switching process, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage, thereby reducing the voltage stabilization time, reducing the insulation detection time, and improving the measurement accuracy of insulation resistance. Attached Figure Description

[0057] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 This is a circuit structure diagram of an insulation detection circuit according to an embodiment of this application;

[0059] Figure 2 This is a schematic diagram of a driving circuit structure in an embodiment of this application;

[0060] Figure 3 This is a circuit diagram of a relay switching combination according to an embodiment of this application;

[0061] Figure 4 This is a circuit diagram of another relay switching combination in the embodiments of this application;

[0062] Figure 5 This is a circuit diagram of another relay switching combination in the embodiments of this application. Detailed Implementation

[0063] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0064] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0065] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0066] It should be understood that the term "and / or" used in this document is merely a description of the same field in the related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0067] It should be understood that although terms such as first, second, third, etc., may be used to describe preset ranges in the embodiments of this application, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from one another. For example, without departing from the scope of the embodiments of this application, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0068] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0069] In this application, considering that insulation testing of energy storage systems using methods such as the half-bridge method used in electric vehicles can lead to premature detection and inaccurate insulation resistance measurements, a new insulation testing method is proposed to address these issues. This insulation testing method is primarily applied in the energy storage field, specifically targeting large-scale electrochemical energy storage applications. The insulation testing method includes:

[0070] S10: Control the relays to close or open according to the drive signal, so that the combination of opening and closing of at least two relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage with zero value.

[0071] In one embodiment, the relay is controlled to close or open according to the received drive signal. Thus, in the case of multiple relays, different combinations of relay opening and closing can be generated based on different drive signals. The result of these relay opening and closing combinations should include a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value. Through these relay opening and closing combinations, the circuit parameters under different path conditions can be provided, and the overall circuit can be analyzed based on the circuit parameters under multiple conditions, providing a technical basis for detecting insulation resistance.

[0072] S20: Acquire the voltage of the target resistor in each output state. When the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage.

[0073] In one embodiment, the voltage of the target resistor under different output states is recorded, and the equivalent insulation resistance is determined based on the circuit parameters corresponding to the three output states. Furthermore, the voltage on the Y capacitor can be compensated in a targeted manner according to the compensation voltage in different directions, so that the voltage change amplitude on the Y capacitor is reduced and the voltage stabilization state is reached more quickly.

[0074] S30: Determine the equivalent insulation resistance based on the voltage across the target resistor.

[0075] In one embodiment, insulation detection is achieved by detecting the equivalent insulation resistance. This equivalent insulation resistance has a certain conversion relationship with other resistances in the insulation detection circuit, and the magnitude of the equivalent insulation resistance can be calculated based on changes in circuit parameters.

[0076] S40: Determine the insulation test results based on the equivalent insulation resistance.

[0077] In one embodiment, if the equivalent insulation resistance is within a preset range, the insulation test result is normal; if the equivalent insulation resistance is not within the preset range, such as in the case of a short circuit, the insulation test result is abnormal.

[0078] In steps S10-S40, the relays are controlled to close or open by a drive signal, resulting in at least two relays being in a combination of three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage at zero value. The voltage of the target resistor is collected in each output state, and the equivalent insulation resistance is determined by switching between various output states, thus achieving the purpose of insulation detection. This provides a new insulation detection method. Furthermore, during the switching process, the voltage change on the Y capacitor is reduced by the first or second compensation voltage, thereby reducing the voltage stabilization time, reducing the insulation detection time, and improving the measurement accuracy of insulation resistance.

[0079] Furthermore, the relays are optocoupler relays, and the number of optocoupler relays is 4.

[0080] In one embodiment, the relay can specifically be an MOC type optocoupler relay, and in order to include at least 3 output states, the number of optocoupler relays can be specifically set to 4 or more.

[0081] Furthermore, in step S10, which involves controlling the relays to close or open according to the drive signal, such that the combination of opening and closing at least two relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value, the specific steps include the following:

[0082] S11: The third compensation voltage is the output state of zero when the third and fourth optocoupler relays are closed according to the drive signal, and when the first and second optocoupler relays are opened.

[0083] S12: When the first and third optocoupler relays are closed according to the drive signal, and the second and fourth optocoupler relays are opened, the output state is the first compensation voltage in the positive direction of the output.

[0084] S13: When the second and fourth optocoupler relays are closed according to the drive signal, and the first and third optocoupler relays are opened, the output state is the second compensation voltage in the negative direction of the output.

[0085] In one embodiment, by using different opening and closing combinations of four optocoupler relays, three output states can be obtained: a third compensation voltage with zero output value, a first compensation voltage with the output state in the positive direction, and a second compensation voltage with the output state in the negative direction. Among these three output states, the first compensation voltage with the output state in the positive direction and the second compensation voltage with the output state in the negative direction are used to compensate the voltage of the Y capacitor in the energy storage battery cluster, so that the voltage change of the Y capacitor is reduced and the time for the voltage to stabilize is shortened, thereby improving the accuracy of insulation resistance detection.

[0086] In steps S11-S13, a combined embodiment of optocoupler relays that can realize multiple output states is provided. In the insulation detection circuit, multiple optocoupler relays can be set to achieve different output states. The first compensation voltage or the second compensation voltage in the output state can be used to compensate the voltage of the Y capacitor of the energy storage battery cluster, thereby improving the accuracy of insulation resistance detection.

[0087] Furthermore, the first and third optocoupler relays are connected in a double-bridge-arm configuration, as are the second and fourth optocoupler relays. Specifically, the first port of the first optocoupler relay is connected to the first bridge arm, the second port of the first optocoupler relay is connected to the first port of the second optocoupler relay, and the second port of the second optocoupler relay is connected to the second bridge arm. The third bridge arm is divided into a first upper bridge arm and a first lower bridge arm, and the fourth bridge arm is divided into a second upper bridge arm and a second lower bridge arm. The first upper bridge arm and the second lower bridge arm have the same resistance value, and the first lower bridge arm and the second upper bridge arm have the same resistance value. The first port of the third optocoupler relay is connected to the first upper bridge arm, the second port of the third optocoupler relay is connected to the first lower bridge arm, the first port of the fourth optocoupler relay is connected to the second upper bridge arm, and the second port of the fourth optocoupler relay is connected to the second lower bridge arm.

[0088] In one embodiment, an insulation detection circuit is provided, comprising multiple optocoupler relays and a bridge arm structure for calculating the equivalent insulation resistance. The first lower bridge arm and the second upper bridge arm serve as resistors for the voltage to be detected. Voltage acquisition is achieved based on these first lower bridge arms and second upper bridge arms under different output states, and the equivalent insulation resistance is calculated from the voltage acquisition results. Understandably, the opening and closing of the optocoupler relays causes the upper bridge arm of the insulation detection circuit to exhibit different conduction and cutoff results under different output states, and the equivalent insulation resistance can be obtained based on these different results under different output states.

[0089] Furthermore, the optocoupler relay adopts a transistor structure and drives the optocoupler according to the drive signal.

[0090] In one embodiment, the optocoupler relay may specifically include a light-emitting diode and an optocoupler transistor, enabling signal transmission via an electrical → optical → electrical signal carrier.

[0091] Furthermore, the drive signal is issued through the microcontroller, which is connected to the base of the transistor.

[0092] In one embodiment, the drive signal is specifically issued by the microcontroller. Before issuing the drive signal, the microcontroller may first receive a control command from the host computer and issue the drive signal according to the control command, thereby controlling the closing of the optocoupler relay.

[0093] Furthermore, in this embodiment, an isolation amplifier is used to acquire the voltage of the target resistor, and the voltage of the target resistor is input to the microcontroller after analog-to-digital conversion.

[0094] In one embodiment, the voltage of the target resistor is finally returned to the microcontroller via analog-to-digital conversion. This processing method can preserve the accuracy of the voltage signal and improve the output results of voltage acquisition.

[0095] Furthermore, in step S20, that is, the step of acquiring the voltage of the target resistor in each output state, the following steps are specifically included:

[0096] S21: When the output state is the positive direction of the first compensation voltage, the first lower bridge arm is used as the target resistor and the voltage is collected.

[0097] S22: The second compensation voltage is in the negative direction of the output state. The second upper bridge arm is used as the target resistor and the voltage is collected.

[0098] S23: When the output state is zero, the first lower bridge arm and the second upper bridge arm connected in series are used as target resistors and the voltage is collected.

[0099] Steps S21-S23 provide a specific implementation method for selecting a target resistor and acquiring its voltage under different output states. The acquired voltage of the target resistor can be used to obtain the equivalent insulation resistance based on the circuit parameters under different output states.

[0100] Furthermore, after determining the equivalent insulation resistance based on the voltage of the target resistor, the process further includes the following steps:

[0101] The location of the cell with insulation fault can be determined based on the equivalent insulation resistance.

[0102] Understandably, battery testing typically only measures the resistance between the total positive and negative terminals of the high-voltage circuit and the ground busbar. However, the insulation resistance of the intermediate cell to ground is very high. If an insulation fault occurs in the intermediate cell, the resistance obtained by using a bridge insulation test that only measures the total positive and negative electrodes is inaccurate. In this embodiment, the location of the cell with the insulation fault can also be determined based on the equivalent insulation resistance. Furthermore, determining the cell with the insulation fault can specifically be the steps included in step S40 of determining the insulation test result based on the equivalent insulation resistance; the order of these steps is not limited here.

[0103] Figure 1 This is a circuit structure diagram of an insulation detection circuit according to an embodiment of this application.

[0104] like Figure 1As shown, the insulation detection circuit includes a battery cluster 1, an insulation detection module 2, a DC side of an energy storage converter 4, and a battery cabinet 3 that houses the battery cluster 1 and the insulation detection module 2. The battery cluster 1 includes an energy storage battery cluster, which is composed of multiple batteries connected in series. An equivalent insulation resistance Rm and a Y-capacitor corresponding to the energy storage battery cluster are also included between the battery cluster 1 and the insulation detection module 2. The Y-capacitor corresponding to the energy storage battery cluster includes Cp and Cn, with Cp corresponding to the high-voltage positive terminal HV+ and Cn corresponding to the high-voltage negative terminal HV-. The insulation detection module 2 includes four optocoupler relays MOC1-MOC4. Specifically, optocoupler relay MOC1 can be the first optocoupler relay mentioned in the above embodiment, optocoupler relay MOC2 can be the second optocoupler relay mentioned in the above embodiment, optocoupler relay MOC3 can be the third optocoupler relay mentioned in the above embodiment, and optocoupler relay MOC4 can be the fourth optocoupler relay mentioned in the above embodiment. These optocoupler relays are specifically driven by optocoupler transistors Q1-Q4. The insulation detection module 2 also includes a pulse power supply and a drive unit. The pulse power supply is used to output corresponding compensation voltages under different output states. The drive unit is used to receive drive signals k1-k4, which are issued by the microcontroller (MCU) in the insulation detection module 2. Specifically, the microcontroller can be 32-bit to complete data transmission. The bridge arms corresponding to optocoupler relay MOC1 are R11 and R12, and the bridge arms corresponding to optocoupler relay MOC2 are R21 and R22. The second port of optocoupler relay MOC1 is connected to the first port of optocoupler relay MOC2. The first port of optocoupler relay MOC1 is connected to bridge arms R11 and R12, and the second port of optocoupler relay MOC2 is connected to bridge arms R21 and R22. The bridge arms corresponding to optocoupler relay MOC3 are R13 and R14, and the bridge arms corresponding to optocoupler relay MOC4 are R23 and R24, where R13 = R23 and R14 = R24. The first port of optocoupler relay MOC3 is connected to R13, and the second port of optocoupler relay MOC3 is connected to R14. The first port of optocoupler relay MOC4 is connected to R24, and the second port of optocoupler relay MOC4 is connected to R23. When acquiring the voltage of R14 and R24, filtering circuits are set after each of them, including a first filtering circuit composed of C1 and R10, and a second filtering circuit composed of C3 and R17. After the voltage signal is filtered, it is input to the isolation amplifier (ISO-AMP) and converted into 16-bit data by digital-to-analog converters (ADC1, ADC2) and input to the microcontroller. The isolation amplifier is followed by a third filtering circuit composed of R15, R16, and C2, and a fourth filtering circuit composed of R18, R19, and C4. The DC side 4 of the energy storage converter includes a corresponding grounded Y capacitor, which includes C5 and C6. Additionally, the DC side 4 of the energy storage converter also includes capacitors C7 and C8.The insulation detection circuit may also include a high-voltage positive relay and a high-voltage negative relay between the insulation detection module 2 and the DC side 4 of the energy storage converter. The high-voltage positive relay includes switches KM1 and KM2, which are connected in parallel. Switch KM2 is also connected in series with a pre-charge resistor R27. The high-voltage negative relay includes switch KM3.

[0105] Figure 2 This is a schematic diagram of a driving circuit structure in an embodiment of this application. Figure 1 The specific structure of the drive circuit corresponding to the optocoupler relay MOC1 is as follows: Figure 2 As shown.

[0106] The operating voltage is set to +5V. The optocoupler relay MOC1 includes a light-emitting diode (LED) and a driving circuit consisting of an optocoupler transistor Q1. Labels 1 and 2 represent the terminals of the LED. The driving circuit includes resistors R1, R2, and R3, which are converted into a driving signal k1 by the optocoupler transistor Q1. This signal k1 causes the optocoupler relay MOC1 to close or open.

[0107] Taking the optocoupler relay MOC1 as an example, Figure 2 The port numbered 4 indicates the first port of the optocoupler relay MOC1. Figure 2 The port marked 3 represents the second port of the optocoupler relay MOC1. The specific components connected to the port marked 4 and the port marked 3 can be MOSFETs. The port settings of other optocoupler relays MOC2-MOC4 can be referenced to optocoupler relay MOC1.

[0108] Figures 3-5 These are simplified diagrams of the insulation circuit under different output states, based on... Figure 3 and Figure 5 The equivalent insulation resistance Rm can be obtained.

[0109] Figure 3 This is a circuit diagram of a relay switching combination according to an embodiment of this application. Figure 3 As shown, controlling the MOC3 and MOC4 optocoupler relays to close, and disengaging the MOC1 and MOC2 optocoupler relays, the Us pulse power supply output voltage is 0. The voltage across the R14 voltage divider resistor is measured to be Vpp, and the voltage across the R24 voltage divider resistor is measured to be Vnn. U0 is the battery cluster voltage. The first functional relationship can be obtained as follows:

[0110]

[0111] Figure 4 This is a circuit diagram of another relay switching combination in an embodiment of this application. For example... Figure 4As shown, the microcontroller controls the optocoupler relays MOC1 and MOC3 to close and the optocoupler relays MOC2 and MOC4 to open. The pulse power supply output voltage is +Us. Through Us compensation, the voltage change on the upper bridge arm Y capacitor is reduced, which can accelerate the stabilization of the voltage on the Y capacitor.

[0112] Next, the voltage across the R14 voltage divider resistor is measured to be Vpp1. According to Kirchhoff's laws, the second functional relationship can be obtained:

[0113]

[0114] Figure 5 This is a circuit diagram of yet another relay switching combination in the embodiments of this application. For example... Figure 5 As shown, optocoupler relays MOC2 and MOC4 are closed, and optocoupler relays MOC1 and MOC2 are opened. The voltage across the voltage divider resistor R24 ​​is measured to be Vnn1. The third functional relationship is:

[0115]

[0116] U0 = U1 + U2 (Equation 1-4)

[0117] Combining equations 1-1 to 1-4, with resistances R13 = R23, R14 = R24, R11 = R21, and R12 = R22, we can obtain the insulation resistance Rm. The fourth functional relationship is:

[0118]

[0119] Furthermore, the steps for determining the location of a single-point insulation fault in a battery cluster can be obtained as follows:

[0120] The fault location is determined based on the U2 value. U2 is calculated based on Rm as follows:

[0121]

[0122] If the voltage of a single battery cell is E, and the insulation fault occurs in the m-th cell, then the location of the faulty cell is:

[0123] m=U2 / E (Formula 1-7)

[0124] In this embodiment, the closing or opening of relays is controlled by a drive signal, so that the combination of opening and closing of at least two relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value. The voltage of the target resistor is collected in each output state, so as to determine the equivalent insulation resistance by switching between various output states, thereby achieving the purpose of insulation detection. This provides a new insulation detection method. Furthermore, during the switching process, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage, thereby reducing the voltage stabilization time, reducing the insulation detection time, and improving the measurement accuracy of insulation resistance.

[0125] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0126] This application also provides an insulation detection circuit, including:

[0127] Energy storage battery clusters, and corresponding Y capacitors for energy storage battery clusters;

[0128] Equivalent insulation resistance is used to detect the insulation condition of a circuit.

[0129] Insulation detection module, used for:

[0130] The relays are controlled to close or open according to the drive signal, so that the combination of opening and closing of at least two relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage with zero value.

[0131] The voltage of the target resistor is collected in each output state. When the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage.

[0132] The equivalent insulation resistance is determined based on the voltage across the target resistor;

[0133] The insulation test results are determined based on the equivalent insulation resistance.

[0134] The DC side of the energy storage converter, and the corresponding Y capacitor on the DC side of the energy storage converter.

[0135] Furthermore, the relays are optocoupler relays, and the number of optocoupler relays is 4.

[0136] Furthermore, the insulation detection module is also used for:

[0137] The third compensation voltage is output as zero when the third and fourth optocoupler relays are closed according to the drive signal, and when the first and second optocoupler relays are opened.

[0138] When the first and third optocoupler relays are closed according to the drive signal, and the second and fourth optocoupler relays are opened, the output state is the first compensation voltage in the positive direction of the output.

[0139] When the second and fourth optocoupler relays are closed according to the drive signal, and the first and third optocoupler relays are opened, the output state is the second compensation voltage in the negative direction of the output.

[0140] Furthermore, the first and third optocoupler relays are connected in a double-bridge-arm configuration, as are the second and fourth optocoupler relays. Specifically, the first port of the first optocoupler relay is connected to the first bridge arm, the second port of the first optocoupler relay is connected to the first port of the second optocoupler relay, and the second port of the second optocoupler relay is connected to the second bridge arm. The third bridge arm is divided into a first upper bridge arm and a first lower bridge arm, and the fourth bridge arm is divided into a second upper bridge arm and a second lower bridge arm. The first upper bridge arm and the second lower bridge arm have the same resistance value, and the first lower bridge arm and the second upper bridge arm have the same resistance value. The first port of the third optocoupler relay is connected to the first upper bridge arm, the second port of the third optocoupler relay is connected to the first lower bridge arm, the first port of the fourth optocoupler relay is connected to the second upper bridge arm, and the second port of the fourth optocoupler relay is connected to the second lower bridge arm.

[0141] Furthermore, the insulation detection module is also used for:

[0142] When the output state is in the positive direction, the first lower bridge arm is used as the target resistor and the voltage is collected.

[0143] The second compensation voltage is output in the negative direction, and the second upper bridge arm is used as the target resistor and the voltage is collected.

[0144] When the output state is zero, the first lower bridge arm and the second upper bridge arm connected in series are used as target resistors and the voltage is collected.

[0145] Furthermore, the insulation detection module is also used for:

[0146] The cell with insulation failure is determined based on the equivalent insulation resistance.

[0147] Furthermore, the optocoupler relay adopts a transistor structure and drives the optocoupler according to the drive signal.

[0148] Furthermore, the drive signal is issued through the microcontroller, which is connected to the base of the transistor.

[0149] Furthermore, an isolation amplifier is used to acquire the voltage of the target resistor, and the voltage of the target resistor is input to the microcontroller after analog-to-digital conversion.

[0150] Furthermore, the insulation detection circuit also includes a high-voltage positive relay and a high-voltage negative relay.

[0151] In this embodiment, the closing or opening of relays is controlled by a drive signal, so that the combination of opening and closing of at least two relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage of zero value. The voltage of the target resistor is collected in each output state, so as to determine the equivalent insulation resistance by switching between various output states, thereby achieving the purpose of insulation detection. This provides a new insulation detection method. Furthermore, during the switching process, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage, thereby reducing the voltage stabilization time, reducing the insulation detection time, and improving the measurement accuracy of insulation resistance.

[0152] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0153] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An insulation testing method, characterized in that, include: The relays are controlled to close or open according to a drive signal, such that the combination of opening and closing of at least two of the relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage with a zero value. Specifically: when the third and fourth relays are closed according to the drive signal, and the first and second relays are open, the output state is the third compensation voltage with a zero value; when the first and third relays are closed according to the drive signal, and the second and fourth relays are open, the output state is the first compensation voltage in the positive direction; when the second and fourth relays are closed according to the drive signal, and the first and third relays are open, the output state is the second compensation voltage in the negative direction. In each of the output states, the voltage of the target resistor is acquired, wherein when the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage. The equivalent insulation resistance is determined based on the voltage across the target resistor; The insulation test results are determined based on the equivalent insulation resistance.

2. The method according to claim 1, characterized in that, The relay is an optocoupler relay, the first relay is a first optocoupler relay, the second relay is a second optocoupler relay, the third relay is a third optocoupler relay, and the fourth relay is a fourth optocoupler relay.

3. The method according to claim 2, characterized in that, The first and third optocoupler relays are connected in a dual-bridge-arm configuration, as are the second and fourth optocoupler relays. Specifically, the first port of the first optocoupler relay is connected to the first bridge arm, the second port of the first optocoupler relay is connected to the first port of the second optocoupler relay, the second port of the second optocoupler relay is connected to the second bridge arm, the third bridge arm is divided into a first upper bridge arm and a first lower bridge arm, and the fourth bridge arm is divided into a second upper bridge arm and a second lower bridge arm. The first upper bridge arm and the second lower bridge arm have the same resistance value, and the first lower bridge arm and the second upper bridge arm have the same resistance value. The first port of the third optocoupler relay is connected to the first upper bridge arm, the second port of the third optocoupler relay is connected to the first lower bridge arm, the first port of the fourth optocoupler relay is connected to the second upper bridge arm, and the second port of the fourth optocoupler relay is connected to the second lower bridge arm.

4. The method according to claim 3, characterized in that, The step of acquiring the voltage of the target resistor in each of the output states includes: When the output state is the first compensation voltage in the positive direction, the first lower bridge arm is used as the target resistor and the voltage is collected; When the output state is the second compensation voltage in the negative direction, the second upper bridge arm is used as the target resistor and the voltage is acquired; When the output state is zero, the third compensation voltage uses the first lower bridge arm and the second upper bridge arm connected in series as the target resistor and the voltage is acquired.

5. The method according to any one of claims 1-4, characterized in that, After determining the equivalent insulation resistance based on the voltage of the target resistor, the method further includes: The cell with insulation failure is determined based on the equivalent insulation resistance.

6. The method according to claim 2, characterized in that, The optocoupler relay adopts a transistor structure and drives the optocoupler according to the drive signal.

7. The method according to claim 6, characterized in that, The drive signal is issued through a microcontroller, which is connected to the base of the transistor.

8. The method according to claim 7, characterized in that, An isolation amplifier is used to acquire the voltage of the target resistor, and the voltage of the target resistor is then converted from analog to digital and input to the microcontroller.

9. An insulation detection circuit, characterized in that, include: Energy storage battery clusters, and Y capacitors corresponding to the energy storage battery clusters; Equivalent insulation resistance is used to detect the insulation condition of a circuit. Insulation detection module, used for: The relays are controlled to close or open according to a drive signal, such that the combination of opening and closing of at least two of the relays includes three output states: a first compensation voltage in the positive direction, a second compensation voltage in the negative direction, and a third compensation voltage with a zero value. Specifically: when the third and fourth relays are closed according to the drive signal, and the first and second relays are open, the output state is the third compensation voltage with a zero value; when the first and third relays are closed according to the drive signal, and the second and fourth relays are open, the output state is the first compensation voltage in the positive direction; when the second and fourth relays are closed according to the drive signal, and the first and third relays are open, the output state is the second compensation voltage in the negative direction. In each of the output states, the voltage of the target resistor is acquired, wherein when the output state is the first compensation voltage in the positive direction or the second compensation voltage in the negative direction, the voltage change on the Y capacitor is reduced by the first compensation voltage or the second compensation voltage. The equivalent insulation resistance is determined based on the voltage across the target resistor; The insulation test result is determined based on the equivalent insulation resistance. The DC side of the energy storage converter, and the Y capacitor corresponding to the DC side of the energy storage converter.

10. The circuit according to claim 9, characterized in that, The relay is an optocoupler relay, the first relay is a first optocoupler relay, the second relay is a second optocoupler relay, the third relay is a third optocoupler relay, and the fourth relay is a fourth optocoupler relay.

11. The circuit according to claim 10, characterized in that, The first and third optocoupler relays are connected in a dual-bridge-arm configuration, as are the second and fourth optocoupler relays. Specifically, the first port of the first optocoupler relay is connected to the first bridge arm, the second port of the first optocoupler relay is connected to the first port of the second optocoupler relay, the second port of the second optocoupler relay is connected to the second bridge arm, the third bridge arm is divided into a first upper bridge arm and a first lower bridge arm, and the fourth bridge arm is divided into a second upper bridge arm and a second lower bridge arm. The first upper bridge arm and the second lower bridge arm have the same resistance value, and the first lower bridge arm and the second upper bridge arm have the same resistance value. The first port of the third optocoupler relay is connected to the first upper bridge arm, the second port of the third optocoupler relay is connected to the first lower bridge arm, the first port of the fourth optocoupler relay is connected to the second upper bridge arm, and the second port of the fourth optocoupler relay is connected to the second lower bridge arm.

12. The circuit according to claim 11, characterized in that, The insulation detection module is also used for: When the output state is the first compensation voltage in the positive direction, the first lower bridge arm is used as the target resistor and the voltage is collected; When the output state is the second compensation voltage in the negative direction, the second upper bridge arm is used as the target resistor and the voltage is acquired; When the output state is zero, the third compensation voltage uses the first lower bridge arm and the second upper bridge arm connected in series as the target resistor and the voltage is acquired.

13. The circuit according to any one of claims 9-12, characterized in that, The insulation detection module is also used for: The cell with insulation failure is determined based on the equivalent insulation resistance.

14. The circuit according to claim 10, characterized in that, The optocoupler relay adopts a transistor structure and drives the optocoupler according to the drive signal.

15. The circuit according to claim 14, characterized in that, The drive signal is issued through a microcontroller, which is connected to the base of the transistor.

16. The circuit according to claim 15, characterized in that, An isolation amplifier is used to acquire the voltage of the target resistor, and the voltage of the target resistor is then converted from analog to digital and input to the microcontroller.

17. The circuit according to claim 9, characterized in that, The insulation detection circuit also includes a high-voltage positive relay and a high-voltage negative relay.

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