Insulation resistor and bus voltage detection circuit and control method

Abstract

The invention provides an insulation resistor and bus voltage detection circuit and a control method. The insulation resistor and bus voltage detection circuit comprises a voltage division module, a detection module, an isolation module, a switch module and a driving module, compared with the prior art, the detection circuit provided by the invention sends the first control signal and the second control signal through the single-chip microcomputer controller to control the drive module to be switched on or switched off, and the drive module drives the switch module to be switched on or switched off to be connected with the shell ground. The detection module inputs the voltage collected in the voltage dividing module to the single chip microcomputer controller through the isolation module for calculation, and the insulation resistance value of the two ends of the voltage dividing module or the bus voltage value of the battery pack is obtained; only one path of control signal is used for controlling the switch module to work, the control logic is relatively simple, detection of an insulation resistance value and detection of a bus voltage value are realized under the condition of the same resources, and the utilization rate of the system is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to an insulation resistance and bus voltage detection circuit and a control method. Background Art

[0002] The battery management system (BMS) of electric vehicles is an important link between the on-board power battery and the electric vehicle. In the high-voltage BMS system, the accuracy of insulation resistance acquisition is actually closely related to the safety of production and use. When an insulation failure occurs in the system, the high voltage will cause the outer shell to carry high voltage electricity, which will pose a great safety risk. In order to ensure the safety of the battery management system and ensure the insulation detection function of the battery management system, it is necessary to detect the insulation resistance of the battery management system. In the high-voltage BMS system (i.e., the bus voltage is greater than 400V), when the insulation resistance is less than 75K ohms, the detection error is required to be less than 15K ohms; when the insulation resistance is greater than 75K ohms, the detection error is required to be less than 20%.

[0003] The insulation resistance of the existing battery management system is mainly realized by a single-arm bridge. In the single-arm bridge method, a resistor and a capacitor are used to divide the voltage between the positive and negative electrodes of the power battery. The capacitance of the capacitor is generally large (μF level), and the resistance value on the bridge arm is also large (MΩ level). A relatively long charge and discharge period is required to ensure the voltage stability of the sampling reference point. It is easily affected by the change of external impedance during the process, which ultimately leads to inaccurate sampling results. Some researchers have also proposed the use of balanced bridge method and unbalanced bridge method for detection. The defect of the balanced bridge method is that the resistance value cannot be detected when the resistance values ​​of the positive and negative ends tend to be consistent, and both of these two methods commonly used on the market require an increase in the number of switches, resulting in increased device costs.

[0004] At the same time, the safety and reliability of the vehicle's power battery also affects the safety and reliability of the entire vehicle. One of the important parameters of the battery pack is voltage. The collection of voltage value is related to the calculation of the system's state of charge (SOC) / battery health (SOH), that is, the calculation of SOC / SOH, and accurate monitoring of real-time usage status.

[0005] At present, the bus voltage collection method of the battery pack is to lead the bus from the positive electrode of the battery pack, then collect the bus voltage to obtain the sampled voltage, and then calculate the theoretical voltage value of the battery through the sampled voltage. Among them, the single-point method and the two-point method are mainly used for calculation. However, the defects of these two methods are that the device cost is high, and the insulation resistance and the bus voltage of the battery pack cannot be detected at the same time. Summary of the invention

[0006] The present invention provides an insulation resistance and bus voltage detection circuit and a control method, the purpose of which is to realize the detection of insulation resistance value and bus voltage value under the same device resource condition, thereby effectively improving the utilization rate of the system.

[0007] In order to achieve the above object, the present invention provides an insulation resistance and bus voltage detection circuit, comprising:

[0008] Voltage divider module, detection module, isolation module, switch module, drive module, single chip controller;

[0009] The first end of the voltage divider module is connected to the positive terminal of the battery pack, and the second end of the voltage divider module is connected to the negative terminal of the battery pack;

[0010] The first end of the detection module is connected to the third end of the voltage dividing module, the second end of the detection module is connected to the first end of the switch module, the third end of the detection module is connected to the first end of the isolation module, and the second end of the isolation module is connected to the first end of the single-chip controller;

[0011] The fourth end of the voltage divider module is connected to the second end of the switch module, the third end of the switch module is connected to the second end of the drive module, and the first end of the drive module is connected to the second end of the single-chip controller;

[0012] The single-chip microcomputer controller sends a first control signal to control the driving module to be turned on, and the driving module drives the switch module to be closed and connected to the housing ground. The detection module inputs the voltage collected in the voltage divider module to the single-chip microcomputer controller through the isolation module for calculation to obtain the insulation resistance value at both ends of the voltage divider module;

[0013] The single-chip microcomputer controller sends a second control signal to control the driving module to shut down, and the driving module drives the switch module to disconnect, so that the switch module is disconnected from the casing. The detection module inputs the voltage collected in the voltage divider module to the single-chip microcomputer controller through the isolation module for calculation to obtain the bus voltage value of the battery pack.

[0014] Specifically, the voltage divider module includes:

[0015] A first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;

[0016] The first end of the first resistor is connected to the positive terminal of the battery pack, and the second end of the first resistor is connected to the first end of the second resistor and the first end of the switch module respectively;

[0017] The second end of the second resistor is respectively connected to the first end of the third resistor, the first end of the switch module, and the first end of the detection module;

[0018] The second end of the third resistor is respectively connected to the first end of the fourth resistor and the first end of the detection module;

[0019] The second end of the fourth resistor is connected to the first end of the fifth resistor, the first end of the detection module, and the first end of the switch module respectively.

[0020] The second end of the fifth resistor is connected to the first end of the sixth resistor and the first end of the switch module respectively;

[0021] The second end of the sixth resistor is connected to the negative terminal of the battery pack.

[0022] More specifically, the switch module includes:

[0023] A first solid-state relay, a second solid-state relay, a third solid-state relay, a first diode, and a second diode;

[0024] The first pin of the first solid-state relay is connected to the power supply end, the second pin of the first solid-state relay is respectively connected to the second end of the driving module and the cathode of the first diode, the fourth pin of the first solid-state relay is respectively connected to the second end of the second resistor and the first end of the detection module, and the sixth pin of the first solid-state relay is connected to the second end of the first resistor;

[0025] The first pin of the second solid-state relay is connected to the power supply end, the second pin of the first solid-state relay is respectively connected to the second end of the driving module and the cathode of the second diode, the fourth pin of the second solid-state relay is connected to the second end of the fifth resistor, and the sixth pin of the second solid-state relay is respectively connected to the second end of the fourth resistor and the first end of the detection module;

[0026] The first pin of the third solid-state relay is connected to the power supply terminal, the second pin of the third solid-state relay is respectively connected to the anode of the first diode and the anode of the second diode, the fourth pin of the third solid-state relay is connected to the isolation ground, and the sixth pin of the third solid-state relay is connected to the shell ground.

[0027] Specifically, the driver module includes:

[0028] A first NMOS transistor, a second NMOS transistor, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor;

[0029] The drain of the first NMOS tube is respectively connected to the second pin of the first solid-state relay and the cathode of the first diode, the gate of the first NMOS tube is respectively connected to the first end of the seventh resistor and the first end of the eighth resistor, the second end of the seventh resistor is connected to the second end of the single-chip controller, and the source of the first NMOS tube is connected to the second end of the eighth resistor and grounded;

[0030] The drain of the second NMOS tube is connected to the second pin of the second solid-state relay and the cathode of the second diode respectively, the gate of the second NMOS tube is connected to the first end of the ninth resistor and the first end of the tenth resistor respectively, the second end of the ninth resistor is connected to the second end of the single-chip controller, and the source of the second NMOS tube is connected to the second end of the tenth resistor and grounded.

[0031] More specifically, the detection unit includes:

[0032] A fuel gauge chip, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourteenth resistor;

[0033] The fifth pin of the fuel gauge chip is connected to the second end of the second resistor and the fourth pin of the first solid-state relay through the eleventh resistor;

[0034] The sixth pin of the fuel gauge chip is connected in parallel to the isolation ground through the twelfth resistor and the second end of the third resistor;

[0035] The seventh pin of the fuel gauge chip is connected to the first end of the fourth resistor through the thirteenth resistor;

[0036] The eighth pin of the fuel gauge chip is connected to the second end of the fourth resistor and the sixth pin of the second solid-state relay through the fourteenth resistor;

[0037] The twelfth pin of the fuel gauge chip, the thirteenth pin of the fuel gauge chip, and the fourteenth pin of the fuel gauge chip are all connected to the first end of the isolation module;

[0038] The fifteenth pin of the fuel gauge chip is connected to the first end of the isolation module and is connected to the isolation power supply.

[0039] Further, a power module consisting of a third diode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first inductor, and a power management chip;

[0040] The anode of the third diode is respectively connected to the first pin of the first solid-state relay, the first pin of the second solid-state relay, the first pin of the third solid-state relay, the first end of the first capacitor, the first end of the second capacitor, and the first end of the first inductor;

[0041] The second end of the first inductor is respectively connected to the first end of the third capacitor and the second pin of the power management chip;

[0042] The cathode of the third diode is respectively connected to the second end of the first capacitor, the second end of the second capacitor, the second end of the third capacitor, the first end of the fourth capacitor, and the first pin of the power management chip;

[0043] The second end of the fourth capacitor is respectively connected to the fifth pin of the power management chip, the sixth pin of the power management chip, the second end of the fifth capacitor, and the fourth pin of the third solid-state relay and connected to the isolation ground;

[0044] The first end of the fifth capacitor is connected to the seventh pin of the power management chip and the fifteenth pin of the power meter chip respectively.

[0045] The present invention also provides a control method for an insulation resistance and bus voltage detection circuit, wherein the insulation resistance and bus voltage detection circuit is the above-mentioned insulation resistance and bus voltage detection circuit, comprising:

[0046] Step 1, the single chip microcomputer controller sends a first control signal to control the driving module to be turned on, and the driving module drives the switch module to be closed and connected to the housing ground;

[0047] Step 2, the detection module samples the voltage by connecting with the voltage divider module to obtain a voltage sampling value;

[0048] Step 3, inputting the voltage sampling value into the single chip microcomputer controller through the isolation module;

[0049] Step 4, the single chip microcomputer controller calculates according to the voltage sampling value to obtain the insulation resistance value at both ends of the voltage divider module;

[0050] Step 5, the single-chip microcomputer controller sends a second control signal to control the driving module to turn off, the driving module drives the switch module to turn off, and the switch module is controlled to be disconnected from the housing;

[0051] Step 6: The single chip microcomputer controller calculates according to the voltage sampling value to obtain the bus voltage value of the battery pack.

[0052] The above scheme of the present invention has the following beneficial effects:

[0053] The present invention comprises a voltage divider module, a detection module, an isolation module, a switch module and a drive module; the first end of the voltage divider module is connected to the positive terminal of the battery pack, and the second end of the voltage divider module is connected to the negative terminal of the battery pack; the first end of the detection module is respectively connected to the third end of the voltage divider module, the second end of the detection module is connected to the first end of the switch module, the third end of the detection module is connected to the first end of the isolation module, and the second end of the isolation module is connected to the first end of the single-chip controller; the fourth end of the voltage divider module is connected to the second end of the switch module, the third end of the switch module is connected to the second end of the drive module, and the first end of the drive module is connected to the first end of the single-chip controller. The two ends are connected; compared with the prior art, the detection circuit provided by the present invention sends the first control signal and the second control signal through the single-chip microcomputer controller to control the driving module to be turned on or off, and the driving module drives the switch module to close or disconnect the connection shell ground, and the detection module inputs the voltage collected in the voltage divider module into the single-chip microcomputer controller through the isolation module for calculation, and obtains the insulation resistance value at both ends of the voltage divider module or the bus voltage value of the battery pack; only one control signal is used to control the operation of the switch module, the control logic is relatively simple and under the same resource conditions, the detection of the insulation resistance value and the detection of the bus voltage value are realized, which effectively improves the utilization rate of the system.

[0054] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a principle block diagram of an embodiment of the present invention;

[0056] Figure 2 is a circuit schematic diagram of an embodiment of the present invention;

[0057] Figure 3 4 is a circuit diagram of a power module in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0060] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0062] In view of the existing problems, the present invention provides an insulation resistance and bus voltage detection circuit and a control method.

[0063] like Figure 1 As shown, an embodiment of the present invention provides an insulation resistance and bus voltage detection circuit, including:

[0064] Voltage dividing module, detection module, isolation module, switch module, drive module;

[0065] The first end of the voltage divider module is connected to the positive terminal of the battery pack, and the second end of the voltage divider module is connected to the negative terminal of the battery pack;

[0066] The first end of the detection module is respectively connected to the third end of the voltage dividing module, the second end of the detection module is connected to the first end of the switch module, the third end of the detection module is connected to the first end of the isolation module, and the second end of the isolation module is connected to the first end of the single-chip controller;

[0067] The fourth end of the voltage divider module is connected to the second end of the switch module, the third end of the switch module is connected to the second end of the drive module, the first end of the drive module is connected to the second end of the single chip controller, and the fourth end of the switch module is connected to the housing ground.

[0068] Most preferably, Figure 2 As shown, the voltage divider module includes:

[0069] A first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6;

[0070] The first end of the first resistor R1 is connected to the positive terminal of the battery pack, and the second end of the first resistor R1 is connected to the first end of the second resistor R2 and the first end of the switch module respectively;

[0071] The second end of the second resistor R2 is respectively connected to the first end of the third resistor R3, the first end of the switch module, and the first end of the detection module;

[0072] The second end of the third resistor R3 is connected to the first end of the fourth resistor R4 and the first end of the detection module respectively;

[0073] The second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5, the first end of the detection module, and the first end of the switch module respectively.

[0074] The second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6 and the first end of the switch module respectively;

[0075] The second end of the sixth resistor R6 is connected to the negative terminal of the battery pack;

[0076] Most preferably, Figure 2 As shown, the switch module includes:

[0077] A first solid-state relay S1, a second solid-state relay S2, a third solid-state relay S3, a first diode D1, and a second diode D2, wherein the first solid-state relay S1 and the second solid-state relay S2 form an OR gate for outputting a logic control result to control the on and off of the third solid-state relay S3. When any one of the first solid-state relay S1 or the second solid-state relay S2 is closed, the third solid-state relay S3 is closed, and the insulation collection ground is connected to the shell ground to detect the insulation resistance value;

[0078] The first pin of the first solid-state relay S1 is connected to the power supply end, the second pin of the first solid-state relay S1 is respectively connected to the second end of the driving module and the cathode of the first diode D1, the fourth pin of the first solid-state relay S1 is respectively connected to the second end of the second resistor R2 and the first end of the detection module, and the sixth pin of the first solid-state relay S1 is connected to the second end of the first resistor R1;

[0079] The first pin of the second solid-state relay S2 is connected to the power supply end, the second pin of the first solid-state relay S1 is respectively connected to the second end of the driving module and the cathode of the second diode D2, the fourth pin of the second solid-state relay S2 is connected to the second end of the fifth resistor R5, and the sixth pin of the second solid-state relay S2 is respectively connected to the second end of the fourth resistor R4 and the first end of the detection module;

[0080] A first pin of the third solid-state relay S3 is connected to a power supply terminal, a second pin of the third solid-state relay S3 is respectively connected to an anode of the first diode D1 and an anode of the second diode D2, a fourth pin of the third solid-state relay S3 is connected to an isolation ground, and a sixth pin of the third solid-state relay S3 is connected to a casing ground.

[0081] Most preferably, Figure 2 As shown, the drive module includes:

[0082] A first NMOS transistor Q1, a second NMOS transistor Q2, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10;

[0083] The drain of the first NMOS transistor Q1 is connected to the second pin of the first solid-state relay S1 and the cathode of the first diode D1 respectively, the gate of the first NMOS transistor Q1 is connected to the first end of the seventh resistor R7 and the first end of the eighth resistor R8 respectively, the second end of the seventh resistor R7 is connected to the second end of the single-chip controller, and the source of the first NMOS transistor Q1 is connected to the second end of the eighth resistor R8 and grounded;

[0084] The drain of the second NMOS tube Q2 is respectively connected to the second pin of the second solid-state relay S2 and the cathode of the second diode D2, the gate of the second NMOS tube Q2 is respectively connected to the first end of the ninth resistor R9 and the first end of the tenth resistor R10, the second end of the ninth resistor R9 is connected to the second end of the single-chip controller, and the source of the second NMOS tube Q2 is connected to the second end of the tenth resistor R10 and grounded.

[0085] Most preferably, Figure 2 As shown, the detection unit includes:

[0086] A power meter chip, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a fourteenth resistor R14;

[0087] The fifth pin of the fuel gauge chip is connected to the second end of the second resistor R2 and the fourth pin of the first solid-state relay S1 through the eleventh resistor R11;

[0088] The sixth pin of the fuel gauge chip is connected to the isolation ground in parallel with the second end of the third resistor R3 through the twelfth resistor R12;

[0089] The seventh pin of the fuel gauge chip is connected to the first end of the fourth resistor R4 through the thirteenth resistor R13;

[0090] The eighth pin of the fuel gauge chip is connected to the second end of the fourth resistor R4 and the sixth pin of the second solid-state relay S2 through the fourteenth resistor R14;

[0091] The twelfth pin of the fuel gauge chip, the thirteenth pin of the fuel gauge chip, and the fourteenth pin of the fuel gauge chip are all connected to the first end of the isolation module;

[0092] The fifteenth pin of the fuel gauge chip is connected to the first end of the isolation module and connected to the isolation power supply;

[0093] In the embodiment of the present invention, the fuel meter chip adopts a 24-bit three-channel fuel meter chip, and the fifth pin and the sixth pin of the fuel meter chip are respectively connected to the two ends of the third resistor R3 as the first group of sampling points for differential sampling, and the first sampling value obtained is Ur3, and the seventh pin and the eighth pin of the fuel meter chip are respectively connected to the two ends of the fourth resistor R4 as the second group of sampling points for differential sampling, and the second sampling value obtained is Ur4; the prior art uses a single-chip microcomputer ADC with an accuracy of 12 bits, and a dedicated ADC chip can achieve 16-bit accuracy, but the relatively high cost; the embodiment of the present invention uses a fuel meter chip with an accuracy of 24 bits, and the accuracy difference is 2 of the single-chip microcomputer ADC 12 =4096 times, twice that of the dedicated ADC 8 = 256 times, but the cost is only half of that of a dedicated ADC chip, which not only improves the detection accuracy of the insulation resistance value and the bus voltage value, but also reduces the device cost.

[0094] Most preferably, Figure 3 As shown, the insulation resistance and bus voltage detection circuit also includes:

[0095] A power module consisting of a third diode D3, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first inductor L1, and a power management chip;

[0096] The anode of the third diode D3 is respectively connected to the first pin of the first solid-state relay S1, the first pin of the second solid-state relay S2, the first pin of the third solid-state relay S3, the first end of the first capacitor C1, the first end of the second capacitor C2, and the first end of the first inductor L1;

[0097] The second end of the first inductor L1 is connected to the first end of the third capacitor C3 and the second pin of the power management chip respectively;

[0098] The cathode of the third diode D3 is respectively connected to the second end of the first capacitor C1, the second end of the second capacitor C2, the second end of the third capacitor C3, the first end of the fourth capacitor C4, and the first pin of the power management chip;

[0099] The second end of the fourth capacitor C4 is respectively connected to the fifth pin of the power management chip, the sixth pin of the power management chip, the second end of the fifth capacitor C5, and the fourth pin of the third solid-state relay S3 and connected to the isolation ground;

[0100] The first end of the fifth capacitor C5 is connected to the seventh pin of the power management chip and the fifteenth pin of the power meter chip respectively.

[0101] The specific principles of the embodiments of the present invention are as follows:

[0102] The detection module samples the voltage in the voltage divider module and inputs the sampled voltage into the single-chip microcomputer controller through the isolation module. The single-chip microcomputer controller sends S1_CONTROL and S2_CONTROL control signals to control the first NMOS tube Q1 and the second NMOS tube Q2 to be turned on or off. The first NMOS tube Q1 and the second NMOS tube Q2 drive the first solid-state relay S1 and the second solid-state relay S2 to form an OR gate output logic control result to control the third solid-state relay S3 to be turned on and off. When any of the first solid-state relay S1 or the second solid-state relay S2 is closed, the third solid-state relay S3 is closed, and the insulation collection ground is connected to the shell ground CH1 to detect the insulation resistance values ​​Ra and Rb at both ends of the voltage divider module; when the first solid-state relay S1, the second solid-state relay S2, and the third solid-state relay S3 are all disconnected, the bus voltage value U of the battery pack is detected.

[0103] The embodiment of the present invention further provides a control method for an insulation resistance and bus voltage detection circuit, wherein the insulation resistance and bus voltage detection circuit is the above-mentioned insulation resistance and bus voltage detection circuit, comprising:

[0104] Step 1, the single chip microcomputer controller sends a first control signal to control the driving module to be turned on, and the driving module drives the switch module to be closed and connected to the housing ground;

[0105] Step 2, the detection module samples the voltage by connecting with the voltage divider module to obtain a voltage sampling value;

[0106] Step 3, inputting the voltage sampling value into the single chip microcomputer controller through the isolation module;

[0107] Step 4, the single chip microcomputer controller calculates according to the voltage sampling value to obtain the insulation resistance value at both ends of the voltage divider module;

[0108] Step 5, the single-chip microcomputer controller sends a second control signal to control the driving module to turn off, the driving module drives the switch module to turn off, and the switch module is controlled to be disconnected from the housing;

[0109] Step 6: The single chip microcomputer controller calculates according to the voltage sampling value to obtain the bus voltage value of the battery pack.

[0110] In the embodiment of the present invention, the insulation resistance value is calculated using the unbalanced bridge method, and the process is as follows:

[0111] When the first solid-state relay S1, the second solid-state relay S2, and the third solid-state relay S3 are all disconnected,

[0112] U=Ur4(R1+R2+R3+R4+R5+R6) / R4

[0113] When the first solid-state relay S1 is disconnected, Ua=Ur3(R1+R2+R3) / R3

[0114] When the first solid-state relay S1 is closed, Ua=Ur3(R1+R3) / R3

[0115] When the second solid-state relay S2 is disconnected, Ub = Ur4 (R4 + R5 + R6) / R4

[0116] When the second solid-state relay S2 is closed, Ub = Ur4 (R4 + R6) / R4

[0117] Using the node current method, we list equations containing only two unknowns, Ra and Rb, and solve them simultaneously to obtain:

[0118] When the first solid-state relay S1 and the second solid-state relay S2 are both closed, and the second solid-state relay S2 is open:

[0119] Ur31 / R3+Ur31(R1+R3) / R3 / Ra

[0120] =Ur41 / R4+Ur41(R4+R5+R6) / R4 / Rb

[0121] When the second solid-state relay S2 and the third solid-state relay S3 are both closed and the first solid-state relay S1 is open:

[0122] Ur32 / R3+Ur32(R1+R2+R3) / R3 / Ra

[0123] =Ur42 / R4+Ur42(R4+R6) / R4 / Rb

[0124] Wherein, R1=R6, R5=R2, R3=R4, R1, R2, R3 are the resistance values ​​of the first voltage-dividing resistor, the second voltage-dividing resistor, and the third voltage-dividing resistor, respectively; R4, R5, R6 are the resistance values ​​of the fourth voltage-dividing resistor, the fifth voltage-dividing resistor, and the sixth voltage-dividing resistor, respectively; Ur31 and Ur41 are the first sampling value and the second sampling value when the first solid-state relay S1 and the third solid-state relay S3 are closed and the second solid-state relay S2 is disconnected, respectively; Ur32 and Ur42 are the first sampling value and the second sampling value when the second solid-state relay S2 and the third solid-state relay S3 are both closed and the first solid-state relay S1 is disconnected;

[0125] The insulation resistance values ​​at both ends of the voltage divider module can be solved by the above equation:

[0126] Ra={Ur31*(R1+R3) 2 *Ur42-Ur41*Ur32(R1+R2+R3) 2} / {Ur41*(Ur32-Ur42)(R1+R2+R3)-Ur42(R1+R3)(Ur31-Ur41)}

[0127] Rb={Ur41*(R1+R3+R2) 2 *Ur32-Ur31*Ur42(R1+R3) 2} / {Ur32*(Ur31-Ur41)(R1+R2+R3)-Ur31(R1+R3)(Ur32-Ur42)}.

[0128] Wherein, Ra represents the insulation resistance value of the positive end of the voltage divider module, and Rb represents the insulation resistance value of the negative end of the voltage divider module.

[0129] In the embodiment of the present invention, the calculation process of the bus voltage value of the battery pack is as follows:

[0130] When the first solid-state relay S1, the second solid-state relay S2, and the third solid-state relay S3 are all disconnected, the bus voltage value is:

[0131] U=Ur4(R1+R2+R3+R4+R5+R6) / R4.

[0132] The embodiment of the present invention includes a voltage divider module, a detection module, an isolation module, a switch module, and a drive module; the first end of the voltage divider module is connected to the positive end of the battery pack, and the second end of the voltage divider module is connected to the negative end of the battery pack; the first end of the detection module is respectively connected to the third end of the voltage divider module, the second end of the detection module is connected to the first end of the switch module, the third end of the detection module is connected to the first end of the isolation module, and the second end of the isolation module is connected to the first end of the single-chip controller; the fourth end of the voltage divider module is connected to the second end of the switch module, the third end of the switch module is connected to the second end of the drive module, and the first end of the drive module is connected to the The second end is connected; compared with the prior art, the detection circuit provided by the present invention sends the first control signal and the second control signal through the single-chip microcomputer controller to control the driving module to be turned on or off, and the driving module drives the switch module to close or disconnect the connection shell ground, and the detection module inputs the voltage collected in the voltage divider module to the single-chip microcomputer controller through the isolation module for calculation, so as to obtain the insulation resistance value at both ends of the voltage divider module or the bus voltage value of the battery pack; only one control signal is used to control the operation of the switch module, the control logic is relatively simple and under the same resource conditions, the detection of the insulation resistance value and the detection of the bus voltage value are realized, thereby effectively improving the utilization rate of the system.

[0133] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An insulation resistance and bus voltage detection circuit, It is characterized in that include: Voltage divider module, detection module, isolation module, switch module, drive module, single chip controller; The first end of the voltage divider module is connected to the positive terminal of the battery pack, and the second end of the voltage divider module is connected to the negative terminal of the battery pack; The first end of the detection module is connected to the third end of the voltage dividing module, the second end of the detection module is connected to the first end of the switch module, the third end of the detection module is connected to the first end of the isolation module, and the second end of the isolation module is connected to the first end of the single-chip controller; The fourth end of the voltage divider module is connected to the second end of the switch module, the third end of the switch module is connected to the second end of the drive module, and the first end of the drive module is connected to the second end of the single-chip controller; The single-chip microcomputer controller sends a first control signal to control the driving module to be turned on, and the driving module drives the switch module to close and connect the housing ground, and the detection module inputs the voltage collected in the voltage dividing module to the single-chip microcomputer controller through the isolation module for calculation to obtain the insulation resistance value at both ends of the voltage dividing module; The single-chip microcomputer controller sends a second control signal to control the driving module to shut down, and the driving module drives the switch module to disconnect, so that the switch module is disconnected from the housing. The detection module inputs the voltage collected in the voltage divider module into the single-chip microcomputer controller through the isolation module for calculation to obtain the bus voltage value of the battery pack.

2. The insulation resistance and bus voltage detection circuit according to claim 1, It is characterized in that The voltage divider module comprises: A first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; The first end of the first resistor is connected to the positive terminal of the battery pack, and the second end of the first resistor is connected to the first end of the second resistor and the first end of the switch module respectively; The second end of the second resistor is respectively connected to the first end of the third resistor, the first end of the switch module, and the first end of the detection module; The second end of the third resistor is connected to the first end of the fourth resistor and the first end of the detection module respectively; The second end of the fourth resistor is connected to the first end of the fifth resistor, the first end of the detection module, and the first end of the switch module respectively. The second end of the fifth resistor is connected to the first end of the sixth resistor and the first end of the switch module respectively; The second end of the sixth resistor is connected to the negative terminal of the battery pack.

3. The insulation resistance and bus voltage detection circuit according to claim 2, It is characterized in that The switch module comprises: A first solid-state relay, a second solid-state relay, a third solid-state relay, a first diode, and a second diode; The first pin of the first solid-state relay is connected to the power supply terminal, the second pin of the first solid-state relay is respectively connected to the second end of the driving module and the cathode of the first diode, the fourth pin of the first solid-state relay is respectively connected to the second end of the second resistor and the first end of the detection module, and the sixth pin of the first solid-state relay is connected to the second end of the first resistor; The first pin of the second solid-state relay is connected to the power supply terminal, the second pin of the first solid-state relay is respectively connected to the second end of the driving module and the cathode of the second diode, the fourth pin of the second solid-state relay is connected to the second end of the fifth resistor, and the sixth pin of the second solid-state relay is respectively connected to the second end of the fourth resistor and the first end of the detection module; The first pin of the third solid-state relay is connected to the power supply terminal, the second pin of the third solid-state relay is respectively connected to the anode of the first diode and the anode of the second diode, the fourth pin of the third solid-state relay is connected to the isolation ground, and the sixth pin of the third solid-state relay is connected to the shell ground.

4. The insulation resistance and bus voltage detection circuit according to claim 3, It is characterized in that The driving module comprises: A first NMOS transistor, a second NMOS transistor, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor; The drain of the first NMOS tube is respectively connected to the second pin of the first solid-state relay and the cathode of the first diode, the gate of the first NMOS tube is respectively connected to the first end of the seventh resistor and the first end of the eighth resistor, the second end of the seventh resistor is connected to the second end of the single-chip controller, and the source of the first NMOS tube is connected to the second end of the eighth resistor and grounded; The drain of the second NMOS tube is respectively connected to the second pin of the second solid-state relay and the cathode of the second diode, the gate of the second NMOS tube is respectively connected to the first end of the ninth resistor and the first end of the tenth resistor, the second end of the ninth resistor is connected to the second end of the single-chip controller, and the source of the second NMOS tube is connected to the second end of the tenth resistor and is grounded.

5. The insulation resistance and bus voltage detection circuit according to claim 4, It is characterized in that The detection unit comprises: A fuel gauge chip, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourteenth resistor; The fifth pin of the fuel gauge chip is connected to the second end of the second resistor and the fourth pin of the first solid-state relay through the eleventh resistor; The sixth pin of the fuel gauge chip is connected in parallel to the isolation ground through the twelfth resistor and the second end of the third resistor; The seventh pin of the fuel gauge chip is connected to the first end of the fourth resistor through the thirteenth resistor; The eighth pin of the fuel gauge chip is connected to the second end of the fourth resistor and the sixth pin of the second solid-state relay through the fourteenth resistor; The twelfth pin of the fuel gauge chip, the thirteenth pin of the fuel gauge chip, and the fourteenth pin of the fuel gauge chip are all connected to the first end of the isolation module; The fifteenth pin of the fuel gauge chip is connected to the first end of the isolation module and is connected to an isolated power supply.

6. The insulation resistance and bus voltage detection circuit according to claim 5, It is characterized in that Also includes: Composed of a third diode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first inductor, and a power management chip; The anode of the third diode is respectively connected to the first pin of the first solid-state relay, the first pin of the second solid-state relay, the first pin of the third solid-state relay, the first end of the first capacitor, the first end of the second capacitor, and the first end of the first inductor; The second end of the first inductor is respectively connected to the first end of the third capacitor and the second pin of the power management chip; The cathode of the third diode is respectively connected to the second end of the first capacitor, the second end of the second capacitor, the second end of the third capacitor, the first end of the fourth capacitor, and the first pin of the power management chip; The second end of the fourth capacitor is respectively connected to the fifth pin of the power management chip, the sixth pin of the power management chip, the second end of the fifth capacitor, and the fourth pin of the third solid-state relay and connected to the isolation ground; The first end of the fifth capacitor is connected to the seventh pin of the power management chip and the fifteenth pin of the power meter chip respectively.

7. A control method for an insulation resistance and bus voltage detection circuit, It is characterized in that The insulation resistance and bus voltage detection circuit is the insulation resistance and bus voltage detection circuit according to any one of claims 1 to 6, comprising: Step 1, the single chip controller sends a first control signal to control the driving module to be turned on, and the driving module drives the switch module to be closed and connected to the housing ground; Step 2, the detection module samples the voltage by connecting with the voltage dividing module to obtain a voltage sampling value; Step 3, inputting the voltage sampling value into the single chip controller through the isolation module; Step 4, the single chip microcomputer controller calculates according to the voltage sampling value to obtain the insulation resistance value at both ends of the voltage divider module; Step 5, the single-chip microcomputer controller sends a second control signal to control the driving module to turn off, and the driving module drives the switch module to turn off, thereby controlling the switch module to be disconnected from the housing; Step 6: The single chip microcomputer controller calculates according to the voltage sampling value to obtain the bus voltage value of the battery pack.

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