Insulation detection circuit and device

Abstract

The invention provides an insulation detection circuit and device, and the circuit is characterized in that the input end of a first path of an optocoupler relay is electrically connected with a first switch module and is also used for being electrically connected with the positive electrode of a battery pack, and the output end is electrically connected with the input end of the first path of the optocoupler relay; the output end of the first path of the relay is electrically connected with the first voltage dividing module; the input end of the second path of the optocoupler relay is electrically connected with the second switch module and is also electrically connected with the cathode of the battery pack, and the output end is electrically connected with the input end of the second path of the relay; the output end of the second path of the relay is electrically connected with the second voltage dividing module; the two switch modules are used for receiving control signals sent by the control unit; the two voltage division modules are respectively used for outputting the voltage of the positive electrode of the battery pack to the ground and the voltage of the negative electrode to the ground to the control unit; and the control unit is used for outputting an insulation detection result according to the anode-to-ground voltage and the cathode-to-ground voltage of the battery pack. The cost of insulation detection can be reduced.

Description

Technical Field

[0001] This invention relates to the field of insulation testing, and more particularly to an insulation testing circuit and device. Background Technology

[0002] Currently, insulation testing of battery packs involves separating the voltage of the positive terminal to ground and the voltage of the negative terminal to ground into two separate circuits for testing. Each circuit uses one relay, so insulation testing of the total voltage of the battery pack requires two relays, resulting in high insulation testing costs. Summary of the Invention

[0003] In view of this, embodiments of the present invention provide an insulation detection circuit and apparatus that can reduce the cost of insulation detection.

[0004] In a first aspect, embodiments of the present invention provide an insulation detection circuit, the circuit comprising: a first switching module, a second switching module, an optocoupler relay, a relay, a first voltage divider module, and a second voltage divider module; The first input terminal of the optocoupler relay is electrically connected to the first switch module and is also electrically connected to the positive terminal of the battery pack. The output terminal is electrically connected to the first input terminal of the relay. The output terminal of the first channel of the relay is electrically connected to the first voltage divider module. The second input terminal of the optocoupler relay is electrically connected to the second switching module and is also electrically connected to the negative terminal of the battery pack. The output terminal is electrically connected to the second input terminal of the relay. The second output terminal of the relay is electrically connected to the second voltage divider module. The first switch module and the second switch module are used to receive control signals sent by the control unit; The first voltage divider module is used to output the voltage of the positive terminal of the battery pack to ground to the control unit; The second voltage divider module is used to output the voltage of the negative terminal of the battery pack to ground to the control unit; The control unit is used to output insulation detection results based on the voltage of the positive terminal of the battery pack to ground and the voltage of the negative terminal of the battery pack to ground.

[0005] Optionally, it may also include: a first resistor and a second resistor; The first input terminal of the first channel of the optocoupler relay is electrically connected to the first switch module, and the second input terminal is electrically connected to the positive terminal of the total voltage of the battery pack through the first resistor; The first input terminal of the second channel of the optocoupler relay is electrically connected to the second switch module, and the second input terminal is electrically connected to the negative terminal of the total voltage of the battery pack through the second resistor.

[0006] Optionally, the first switching module includes: a first switching transistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor; the first input terminal of the first channel of the optocoupler relay includes the anode and cathode of the first light-emitting diode; The gate of the first switching transistor is electrically connected to one end of the third resistor, one end of the fourth resistor, and one end of the fifth resistor; the other end of the third resistor is electrically connected to the control unit; the other end of the fourth resistor is electrically connected to the first power supply voltage; the other end of the fifth resistor and the source of the first switching transistor are grounded. The drain of the first switching transistor is electrically connected to one end of the sixth resistor and the cathode of the first light-emitting diode; the other end of the sixth resistor is electrically connected to the second power supply voltage and one end of the seventh resistor; the other end of the seventh resistor is electrically connected to the anode of the first light-emitting diode.

[0007] Optionally, the second switch module is the same as the first switch module.

[0008] Optionally, the relay has a withstand voltage of at least 2000V.

[0009] Optionally, the first voltage divider module includes: an eighth resistor, a ninth resistor, a tenth resistor, a first capacitor, a second capacitor, a third capacitor, and a first Zener diode; One end of the eighth resistor, one end of the ninth resistor, one end of the tenth resistor, one end of the first capacitor, and the cathode of the first Zener diode are all electrically connected to the first output terminal of the relay. The other end of the eighth resistor is electrically connected to the third power supply voltage and one end of the second capacitor; The other end of the tenth resistor is electrically connected to one end of the third capacitor and the control unit. The other end of the first capacitor, the other end of the second capacitor, the other end of the third capacitor, the other end of the ninth resistor, and the anode of the first Zener diode are all grounded.

[0010] Optionally, the second voltage divider module is the same as the first voltage divider module.

[0011] Optionally, the control unit is specifically used for: The insulation resistance value is output based on the voltage between the positive terminal and ground of the battery pack and the voltage between the negative terminal and ground of the battery pack.

[0012] Optionally, the control unit is further configured to: The bus voltage, ambient temperature, and ambient humidity of the battery pack are acquired in real time. The baseline allowable leakage power is determined based on the baseline power values ​​set by international and national safety standards and the vehicle safety factor. The dynamic coefficient is determined based on the ambient temperature, the ambient humidity, and the aging degradation factor. The minimum insulation resistance threshold is dynamically generated based on the bus voltage, the dynamic coefficient, and the baseline allowable leakage power. An insulation fault alarm or an update of historical health status is triggered based on the relationship between the insulation resistance value and the minimum insulation resistance threshold.

[0013] Optionally, the control unit is specifically used for: Determine whether the insulation resistance value is less than the minimum insulation resistance threshold; If so, trigger an insulation fault alarm; If not, update the historical health status based on the insulation resistance value.

[0014] On the other hand, embodiments of the present invention provide an insulation detection device, the device comprising: the above-described insulation detection circuit.

[0015] The insulation detection circuit and device provided in this invention include: an input terminal of an optocoupler relay electrically connected to a first switching module and also electrically connected to the positive terminal of the battery pack; an output terminal electrically connected to the input terminal of the first channel of the relay; an output terminal of the first channel of the relay electrically connected to a first voltage divider module; an input terminal of the second channel of the optocoupler relay electrically connected to a second switching module and also electrically connected to the negative terminal of the battery pack; an output terminal electrically connected to the input terminal of the second channel of the relay; an output terminal of the second channel of the relay electrically connected to a second voltage divider module; two switching modules for receiving control signals sent by a control unit; two voltage divider modules for outputting the voltage between the positive and negative terminals of the battery pack to ground and the voltage between the positive and negative terminals of the battery pack to ground, respectively, to the control unit; and the control unit for outputting insulation detection results based on the voltage between the positive and negative terminals of the battery pack to ground. This reduces the cost of insulation detection. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an insulation detection circuit in the prior art; Figure 2 A schematic diagram of an insulation detection circuit provided in an embodiment of the present invention; Figure 3 for Figure 2 A detailed schematic diagram of the insulation detection circuit shown. Figure 4 This is a schematic diagram illustrating the execution steps of the control unit in an embodiment of the present invention; Figure 5 for Figure 4A diagram illustrating how insulation fault alarms or historical health status updates are triggered based on the relationship between insulation resistance values ​​and minimum insulation resistance thresholds; Figure 6 This is a schematic diagram of an insulation detection device provided in an embodiment of the present invention. Detailed Implementation

[0017] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0019] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0020] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0021] The insulation detection circuit measures the insulation withstand voltage (voltage value) of the positive and negative terminals of the battery pack to ground in the Battery Management System (BMS). It then converts this voltage value into a resistance value through the control unit, and determines whether the positive and negative terminals of the battery pack are insulated from ground based on the resistance value.

[0022] Figure 1 The diagram shows an insulation detection circuit in the prior art, such as... Figure 1 As shown, existing technology detects the voltage values ​​of the positive and negative terminals of the battery pack to ground separately, using one relay for each of the two circuits. Therefore, a total of two relays are required, namely relay 1 and relay 2, and these two relays have low withstand voltage values. The need for two relays leads to higher testing costs.

[0023] join Figure 1Insulation testing performs an insulation self-test upon power-on, specifically including: measuring voltage once when all switches are disconnected at power-on; measuring voltage once when relay 1 and the first channel of the optocoupler relay are closed; measuring voltage once when relay 2 and the second channel of the optocoupler relay are closed; and measuring voltage once when relays 1 and 2 are disconnected and the second and second channels of the optocoupler relay are closed. By comparing the measured voltage values ​​with the design values, the self-test circuit is checked for insulation faults. Under various operating conditions, such as charging, discharging, resting, different temperatures, different battery voltages, and different SOC (State of Charge), the insulation resistance value is measured by controlling the switches of relays 1, 2, and the first and second channels of the optocoupler relay. At the same time, it is compared with the voltage ratio threshold to determine whether an insulation problem has occurred.

[0024] In high-voltage battery systems for new energy vehicles, insulation failure is a core contributing factor to major safety accidents such as electric shock, short circuits, and fires. Current mainstream insulation testing methods (such as the national standard GB / T 18384.3) generally employ a fixed resistance threshold method (e.g., insulation resistance value). (<500 Ω / V) indicates a fault. This method has the following significant drawbacks: Poor voltage adaptability: High-voltage platforms (such as 800V systems) exhibit high leakage power under the same insulation resistance. As the voltage squared increases, among which This refers to the bus voltage of the battery pack. A fixed threshold is too strict at low voltages (high false alarm rate) and too lenient at high voltages (high risk of missed alarms).

[0025] Ignoring actual safety boundaries: The essence of safety risk is determined by leakage energy, not the absolute value of resistance. Traditional methods only consider resistance and cannot dynamically reflect the true risk level.

[0026] Poor compatibility with operating conditions: Increased temperature and humidity will accelerate the aging of insulation materials, and the actual leakage current will increase under the same resistance, but the fixed threshold cannot be adjusted adaptively.

[0027] Meanwhile, the existing method uses two 1000V withstand voltage relays and two optocoupler relays for opening detection, but the opening time of the two relays is consistent, so the cost is high.

[0028] Meanwhile, some existing improvement solutions also have the following shortcomings: Voltage proportional threshold method: Although it partially responds to voltage changes, the coefficient is an empirical constant and still cannot accurately correspond to the safe power boundary. In addition, it does not consider environmental factors, which may lead to false alarms (at low voltage) or missed alarms (at high voltage).

[0029] Multi-level segmented threshold method: different thresholds are set in different voltage ranges, but the switching point is prone to judgment oscillation, and it is still a static rule without establishing an energy model.

[0030] Redundant relay application: From a practical application perspective, it is unnecessary to use two relays of the same specification with a voltage rating of 1000V, which would increase costs.

[0031] Therefore, existing technologies lack a dynamic threshold mechanism based on leakage power as a safety benchmark, making it difficult to meet the requirements for high-precision, all-condition insulation protection, while also incurring high hardware costs.

[0032] To address the aforementioned technical issues, this invention provides an insulation detection circuit that can reduce the cost of insulation detection.

[0033] Figure 2 This is a schematic diagram of an insulation detection circuit provided in an embodiment of the present invention. Figure 3 for Figure 2 A detailed schematic diagram of the insulation detection circuit is shown.

[0034] like Figure 2 As shown, the insulation detection circuit includes: a first switch module, a second switch module, an optocoupler relay, a relay, a first voltage divider module, and a second voltage divider module.

[0035] The first input terminal of the optocoupler relay is electrically connected to the first switching module and is also used for electrical connection to the positive terminal of the battery pack. The output terminal is electrically connected to the first input terminal of the relay. The first output terminal of the relay is electrically connected to the first voltage divider module.

[0036] The second input terminal of the optocoupler relay is electrically connected to the second switch module and is also used for electrical connection to the negative terminal of the battery pack. The output terminal is electrically connected to the second input terminal of the relay. The output terminal of the second channel of the relay is electrically connected to the second voltage divider module.

[0037] The first switch module and the second switch module are used to receive control signals sent by the control unit. The control signals are high and low level signals. Specifically, the first switch module is used to receive a first control signal, and the second switch module is used to receive a second control signal.

[0038] The first voltage divider module is used to output the voltage between the positive terminal of the battery pack and ground to the control unit.

[0039] The second voltage divider module is used to output the voltage of the negative terminal of the battery pack to ground to the control unit; The control unit is used to output insulation detection results based on the voltage of the positive terminal of the battery pack to ground and the voltage of the negative terminal of the battery pack to ground.

[0040] The optocoupler relay is dual-channel, with the first channel used to detect the voltage of the positive terminal of the battery pack to ground, and the second channel used to detect the voltage of the negative terminal of the battery pack to ground.

[0041] like Figure 3 As shown, the insulation detection circuit also includes: a first resistor R1 and a second resistor R2; The first input terminals 3 and 4 of the first channel U1 of the optocoupler relay are electrically connected to the first switch module, and the second input terminal 6 is electrically connected to the positive terminal of the total voltage of the battery pack through the first resistor R1.

[0042] Among them, the first channel U1 of the optocoupler relay includes pins 3, 4, 5 and 6.

[0043] The first input terminals 1 and 2 of the second channel U2 of the optocoupler relay are electrically connected to the second switch module, and the second input terminal 7 is electrically connected to the negative terminal of the total voltage of the battery pack through the second resistor R2.

[0044] Among them, the first channel U2 of the optocoupler relay includes pin 1, pin 2, pin 7, and pin 8.

[0045] like Figure 3 As shown, the first switching module includes: a first switching transistor Q1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the first input terminals 3 and 4 of the first channel U1 of the optocoupler relay include the anode 3 and cathode 4 of the first light-emitting diode.

[0046] The gate of the first switching transistor Q1 is electrically connected to one end of the third resistor R3, one end of the fourth resistor R3, and one end of the fifth resistor R5.

[0047] The other end of the third resistor R3 is used for electrical connection with the control unit; the other end of the fourth resistor R4 is used for electrical connection with the first power supply voltage; the other end of the fifth resistor R5, the source of the first switching transistor Q1, is grounded.

[0048] For example, the first power supply voltage is 3.3V.

[0049] The drain of the first switching transistor Q1 is electrically connected to one end of the sixth resistor R6 and the cathode 4 of the first light-emitting diode; the other end of the sixth resistor R6 is electrically connected to the second power supply voltage and one end of the seventh resistor R7; the other end of the seventh resistor R7 is electrically connected to the anode 3 of the first light-emitting diode.

[0050] For example, the second power supply voltage is 5V.

[0051] In embodiments of the present invention, such as Figure 3 As shown, the second switch module is the same as the first switch module.

[0052] like Figure 3As shown, the first voltage divider module includes: an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a first Zener diode D1.

[0053] One end of the eighth resistor R8, one end of the ninth resistor R9, one end of the tenth resistor R10, one end of the first capacitor C1, and the cathode of the first Zener diode D1 are all electrically connected to the first output terminal 5 of the relay K.

[0054] The other end of the eighth resistor R8 is electrically connected to the third power supply voltage and one end of the second capacitor C2.

[0055] For example, the third power supply voltage is 3.3V (reference).

[0056] The other end of the tenth resistor R10 is electrically connected to one end of the third capacitor C3 and the control unit.

[0057] The other ends of the first capacitor C1, the second capacitor C2, the third capacitor C3, the ninth resistor R9, and the anode of the first Zener diode D1 are all grounded.

[0058] In embodiments of the present invention, such as Figure 3 As shown, the second voltage divider module is the same as the first voltage divider module.

[0059] In the second voltage divider module and the first voltage divider module, the resistors are used for voltage division, the capacitors are used for filtering, and the Zener diodes are used for voltage regulation.

[0060] For example, the control unit is an MCU.

[0061] In this embodiment of the invention, the first switch module, the second switch module, the first voltage divider module, and the second voltage divider module are electrically connected to different pins of the same control unit, and the specific pins can be selected according to the actual situation.

[0062] For example, the first switch Q1 is a MOSFET.

[0063] In this embodiment of the invention, both the first switching transistor Q1 and the optocoupler relay are used as switches. When insulation detection is required, the MCU sends high and low level signals to turn on the MOSFET and the optocoupler relay, thus enabling insulation detection.

[0064] like Figure 3 As shown, the first path of relay K (including pins 4 and 5) is open and not in the insulation detection state. When the first path is turned on, the input terminal 4 and the output terminal 5 of the first path are closed, and it is in the insulation detection state.

[0065] like Figure 3As shown, the second path of relay K (including pins 8 and 9) is open and not in insulation detection mode. When the second path is closed, the input terminal 9 and output terminal 8 of the second path are closed, and it is in insulation detection mode. Figure 3 As shown, when both the first and second paths of relay K are closed, the first and second paths are independent of each other and do not affect each other. Therefore, insulation detection of the positive and negative terminals of the battery pack can be performed simultaneously.

[0066] like Figure 3 As shown, the diode to the left of relay K is a freewheeling diode.

[0067] For example, the withstand voltage of relay K is at least 2000V. If it is an 800V system, a relay with a higher withstand voltage should be selected.

[0068] In this embodiment of the invention, a relay with a higher withstand voltage is used to replace the two relays in the prior art, and the two detection circuits are combined into one detection circuit, which simultaneously detects the voltage of the positive terminal of the battery pack to ground and the voltage of the negative terminal to ground.

[0069] The insulation testing effect achieved by using one relay with a higher withstand voltage value in this embodiment of the invention is the same as that achieved by using two relays with ordinary withstand voltage values. Since one less relay is used, the cost of insulation testing can be reduced.

[0070] Furthermore, the controller is specifically used to output the insulation resistance value based on the voltage between the positive terminal and ground of the battery pack and the voltage between the negative terminal and ground of the battery pack.

[0071] Furthermore, such as Figure 4 As shown, the controller is also used to perform the following steps: Step S1: Obtain the real-time bus voltage, ambient temperature, and ambient humidity of the battery pack.

[0072] In this embodiment of the invention, the bus voltage is collected in real time. (Supports 0-1000V range).

[0073] Step S2: Determine the baseline allowable leakage power based on the baseline power value and vehicle safety factor set by international safety standards and national standards.

[0074] In this embodiment of the invention, based on insulation resistance requirements and safety principles, the basic power value is set according to international standard ISO 6469-3:2018 and national standard GB / T 18384.3-2020, and other safety standards. To further enhance safety, the base power value is adjusted according to the vehicle safety level (ASIL). Multiply by the vehicle safety factor Obtain the baseline allowable leakage power .

[0075] Step S3: Determine the dynamic coefficient based on ambient temperature, ambient humidity, and aging degradation factor.

[0076] In this embodiment of the invention, the coefficients are no longer constants, but rather functions of environmental and aging factors, dynamically changing with ambient temperature, ambient humidity, and aging degradation factors. The dynamic coefficients are calculated using the following formula:

[0077] in, is the baseline proportional coefficient (calibrated value, default 1.0); f(T) is the temperature compensation function; g(H) is the humidity compensation function; h(Aging) is the aging degradation factor (based on battery pack operating time / cycle number lookup table degradation).

[0078] For example, Where β is the material temperature coefficient and T is the actual measured temperature. This is a reference temperature.

[0079] For example, Where γ is the humidity sensitivity coefficient and H is the actual ambient humidity. This is for reference humidity.

[0080] In this embodiment of the invention, the temperature compensation function f(T) and the humidity compensation function g(H) are initially calibrated. Specifically, the critical breakdown power of the insulating material under different temperature and humidity combinations is measured in a temperature and humidity test chamber, and the temperature compensation function f(T) and the humidity compensation function g(H) are fitted.

[0081] In this embodiment of the invention, the insulation resistance values ​​under historical normal operating conditions are recorded. Distribution, automatic tightening of dynamic coefficients To reflect the aging trend.

[0082] Step S4: Dynamically generate the minimum insulation resistance threshold based on the bus voltage, dynamic coefficient, and reference allowable leakage power.

[0083] In this embodiment of the invention, a triple adaptive model of "power-voltage-environment" is constructed to dynamically calculate the insulation fault judgment threshold, i.e., the minimum insulation resistance threshold.

[0084] In this embodiment of the invention, the dynamic minimum insulation resistance threshold is derived based on the power-resistance relationship: .

[0085] Step S5: Trigger an insulation fault alarm or update historical health status based on the relationship between the insulation resistance value and the minimum insulation resistance threshold.

[0086] In embodiments of the present invention, such as Figure 5 As shown, step S5 specifically includes: Step S51: Determine whether the insulation resistance value is less than the minimum insulation resistance threshold. If yes, proceed to step S52; otherwise, proceed to step S53.

[0087] In this embodiment of the invention, the controller is specifically used to determine whether the insulation resistance value is less than the minimum insulation resistance threshold; if the insulation resistance value is determined to be less than the minimum insulation resistance threshold, an insulation fault alarm is triggered.

[0088] Step S52: Trigger insulation fault alarm, continue to execute step S1.

[0089] Step S53: Update the historical health status based on the insulation resistance value, and continue to execute step S1.

[0090] In this embodiment of the invention, the controller is specifically used to update the historical health status based on the insulation resistance value if it is determined that the insulation resistance value is greater than or equal to the minimum insulation resistance threshold.

[0091] In this embodiment of the invention, confidence intervals can also be used for buffering, for example... When the insulation resistance value It triggers early warnings rather than alarms to avoid false triggering due to transient fluctuations.

[0092] In this embodiment of the invention, the insulation resistance value If the rate of decline exceeds a set threshold during mutation detection, the diagnostic mode is triggered in advance.

[0093] This invention, through measurement data verification, demonstrates that under dynamic operating conditions, when the bus voltage jumps from 400V to 800V, the traditional fixed threshold method fails to report faults in terms of insulation resistance value. No alarm was triggered when the value was 300K. This embodiment of the invention calculates the minimum insulation resistance threshold in real time. Accurate alarm at 640K. Regarding temperature compensation, the false alarm rate of the traditional fixed threshold method is 32% at -30℃, while the false alarm rate of this embodiment is reduced to 5%.

[0094] Compared to the drawbacks of traditional fixed threshold methods, such as fixed thresholds and high false negative rates under high voltage, the embodiments of this invention improve adaptability to high voltage and minimize insulation resistance thresholds. As the bus voltage of the battery pack increases, the system's false alarm rate decreases by more than 90% at high voltage, improving the false alarm rate at low temperatures. Traditional fixed threshold methods cause false alarms due to increased material resistance at low temperatures. This embodiment of the invention uses a dynamic coefficient K to compensate for temperature effects, reducing the false alarm rate by 70% at -40℃. It also increases aging adaptability. Traditional fixed threshold methods cannot detect the aging of insulation materials. This embodiment of the invention automatically tightens the threshold using the aging attenuation factor h (Aging), improving the end-of-life fault detection rate by 50%. Furthermore, this embodiment of the invention requires no additional hardware; cost reduction can be achieved through software upgrades.

[0095] In summary, this invention replaces the two relays in the original scheme with a relay with a higher withstand voltage, and merges two detection circuits into one detection circuit, thereby reducing costs. It links the insulation fault judgment threshold to the physical relationship between the real-time bus voltage square and the baseline allowable leakage power, which differs from the traditional voltage ratio method. This invention is essentially a power model rather than a linear empirical formula. The dynamic coefficients of the multi-factor coupling are defined as functions of environmental and aging factors, pioneering a dynamic compensation mechanism for insulation thresholds that integrates temperature, humidity, and aging variables. A confidence interval buffer strategy based on safety standards triggers early warnings rather than alarms within the confidence interval, avoiding false triggering due to transient fluctuations.

[0096] This invention proposes an insulation fault determination scheme that uses the baseline allowable leakage power as a safety benchmark and dynamically compensates for multiple environmental factors. This fundamentally solves the problem of false alarms and missed alarms in traditional schemes under high voltage / cold / high humidity scenarios. Its core lies in establishing an adaptive mathematical model of "voltage-power-environment", which provides a more accurate and reliable safety protection mechanism for insulation detection of BMS (Battery Management System), especially suitable for high voltage platforms of 800V and above. At the same time, the hardware design can reduce costs by replacing it with a single relay.

[0097] In the insulation detection circuit provided by this invention, the first input terminal of the optocoupler relay is electrically connected to the first switching module and also electrically connected to the positive terminal of the battery pack; its output terminal is electrically connected to the first input terminal of the relay. The first output terminal of the relay is electrically connected to the first voltage divider module. The second input terminal of the optocoupler relay is electrically connected to the second switching module and also electrically connected to the negative terminal of the battery pack; its output terminal is electrically connected to the second input terminal of the relay. The second output terminal of the relay is electrically connected to the second voltage divider module. Two switching modules are used to receive control signals sent by the control unit. Two voltage divider modules are used to output the voltage between the positive and negative terminals of the battery pack to ground and the voltage between the positive and negative terminals of the battery pack to ground, respectively, to the control unit. The control unit outputs the insulation detection result based on the voltage between the positive and negative terminals of the battery pack to ground. This reduces the cost of insulation detection.

[0098] Figure 6 This is a schematic diagram of the structure of an insulation detection device provided in an embodiment of the present invention, as shown below. Figure 6 As shown, the device includes Figures 2-3 The insulation detection circuit shown.

[0099] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An insulation detection circuit, characterized in that, The circuit includes: a first switching module, a second switching module, an optocoupler relay, a relay, a first voltage divider module, and a second voltage divider module; The first input terminal of the optocoupler relay is electrically connected to the first switch module and is also electrically connected to the positive terminal of the battery pack. The output terminal is electrically connected to the first input terminal of the relay. The output terminal of the first channel of the relay is electrically connected to the first voltage divider module. The second input terminal of the optocoupler relay is electrically connected to the second switching module and is also electrically connected to the negative terminal of the battery pack. The output terminal is electrically connected to the second input terminal of the relay. The second output terminal of the relay is electrically connected to the second voltage divider module. The first switch module and the second switch module are used to receive control signals sent by the control unit; The first voltage divider module is used to output the voltage of the positive terminal of the battery pack to ground to the control unit; The second voltage divider module is used to output the voltage of the negative terminal of the battery pack to ground to the control unit; The control unit is used to output insulation detection results based on the voltage of the positive terminal of the battery pack to ground and the voltage of the negative terminal of the battery pack to ground.

2. The circuit according to claim 1, characterized in that, Also includes: First resistor and second resistor; The first input terminal of the first channel of the optocoupler relay is electrically connected to the first switch module, and the second input terminal is electrically connected to the positive terminal of the total voltage of the battery pack through the first resistor; The first input terminal of the second channel of the optocoupler relay is electrically connected to the second switch module, and the second input terminal is electrically connected to the negative terminal of the total voltage of the battery pack through the second resistor.

3. The circuit according to claim 1 or 2, characterized in that, The first switching module includes: a first switching transistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor; the first input terminal of the first channel of the optocoupler relay includes the anode and cathode of the first light-emitting diode; The gate of the first switching transistor is electrically connected to one end of the third resistor, one end of the fourth resistor, and one end of the fifth resistor; the other end of the third resistor is electrically connected to the control unit; the other end of the fourth resistor is electrically connected to the first power supply voltage; the other end of the fifth resistor and the source of the first switching transistor are grounded. The drain of the first switching transistor is electrically connected to one end of the sixth resistor and the cathode of the first light-emitting diode; the other end of the sixth resistor is electrically connected to the second power supply voltage and one end of the seventh resistor; the other end of the seventh resistor is electrically connected to the anode of the first light-emitting diode.

4. The circuit according to claim 3, characterized in that, The second switch module is the same as the first switch module.

5. The circuit according to claim 1, characterized in that, The relay has a withstand voltage of at least 2000V.

6. The circuit according to claim 1, characterized in that, The first voltage divider module includes: an eighth resistor, a ninth resistor, a tenth resistor, a first capacitor, a second capacitor, a third capacitor, and a first Zener diode; One end of the eighth resistor, one end of the ninth resistor, one end of the tenth resistor, one end of the first capacitor, and the cathode of the first Zener diode are all electrically connected to the first output terminal of the relay. The other end of the eighth resistor is electrically connected to the third power supply voltage and one end of the second capacitor; The other end of the tenth resistor is electrically connected to one end of the third capacitor and the control unit. The other end of the first capacitor, the other end of the second capacitor, the other end of the third capacitor, the other end of the ninth resistor, and the anode of the first Zener diode are all grounded.

7. The circuit according to claim 6, characterized in that, The second voltage divider module is the same as the first voltage divider module.

8. The circuit according to claim 1, characterized in that, The control unit is specifically used for: The insulation resistance value is output based on the voltage between the positive terminal and ground of the battery pack and the voltage between the negative terminal and ground of the battery pack.

9. The circuit according to claim 8, characterized in that, The control unit is also used for: The bus voltage, ambient temperature, and ambient humidity of the battery pack are acquired in real time. The baseline allowable leakage power is determined based on the baseline power values ​​set by international and national safety standards and the vehicle safety factor. The dynamic coefficient is determined based on the ambient temperature, the ambient humidity, and the aging degradation factor. The minimum insulation resistance threshold is dynamically generated based on the bus voltage, the dynamic coefficient, and the baseline allowable leakage power. An insulation fault alarm or an update of historical health status is triggered based on the relationship between the insulation resistance value and the minimum insulation resistance threshold.

10. The circuit according to claim 9, characterized in that, The control unit is specifically used for: Determine whether the insulation resistance value is less than the minimum insulation resistance threshold; If so, trigger an insulation fault alarm; If not, update the historical health status based on the insulation resistance value.

11. An insulation detection device, comprising the insulation detection circuit according to any one of claims 1 to 10.

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