Insulation resistance measuring device

Abstract

The present invention discloses an insulation resistance measuring device for measuring a positive insulation resistance provided between the positive electrode of a battery pack and ground, and a negative insulation resistance provided between the ground and the negative electrode of the battery pack, comprising first and second resistors connected in series between the positive electrode of the battery pack and ground, third and fourth resistors connected in series between the ground and the negative electrode of the battery pack, an output terminal connected between the third and fourth resistors, and a switch connected between the contact point between the first and second resistors and the negative electrode of the battery pack.

Description

[Technical field]

[0001] The present invention relates to an insulation resistance measuring device for a battery pack, and more particularly to an insulation resistance measuring device capable of reducing the number of components. [Background technology]

[0002] In recent years, as the demand for portable electronic products such as laptops and mobile phones has grown rapidly and the development of electric vehicles, energy storage batteries, robots, satellites, etc. has accelerated, active research is being conducted on high-performance batteries that can be repeatedly charged and discharged.

[0003] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Of these, lithium secondary batteries are in the spotlight due to their advantages of being freely chargeable and dischargeable since they have almost no memory effect compared to nickel-based secondary batteries, as well as their extremely low self-discharge rate and high energy density.

[0004] Meanwhile, a secondary battery may be used as a single secondary battery, but in order to provide a high-voltage and / or large-capacity power storage device, a plurality of secondary batteries are often connected in series and / or parallel. That is, in environments requiring high capacity such as electric vehicles, energy storage systems, and uninterruptible power supplies, a plurality of battery cells of the secondary battery may be joined together to be used as a battery module, or a plurality of battery modules may be joined together to be used as a battery pack.

[0005] In power storage devices using such high-voltage, large-capacity secondary batteries, such as electric vehicles equipped with battery packs, it is very important to maintain an insulating state. Here, insulation refers to separating a high-voltage area from a low-voltage area in an electric or electronic device such as an electric vehicle. If the insulating state of the battery pack is not maintained, leakage current may occur, causing various inconveniences. That is, leakage current may shorten the life of the battery pack, cause malfunction of the electric or electronic device in which the battery pack is used, and cause safety accidents such as electric shock.

[0006] In order to prevent problems caused by such leakage current, insulation resistance must be maintained at a certain level. Here, the insulation resistance exists between a high voltage area and a low voltage area. For example, when a high voltage battery pack is applied to an electric vehicle, the insulation resistance exists between the positive and negative electrodes of the battery pack and the chassis of the vehicle, i.e., ground An insulation resistor is provided in the battery pack, and the resistance value of the insulation resistor must be measured to ensure that it does not drop below a certain level. In order to measure the insulation resistance, an insulation resistance measuring device is provided in the battery pack. The insulation resistance measuring device measures the insulation resistance at any time or periodically, allowing a Battery Management System (BMS) to check the insulation condition.

[0007] The insulation resistance is measured between the positive and negative poles of the high voltage battery pack. ground A positive insulation resistor is provided between the negative electrode and ground A negative insulation resistance is provided between the positive electrode and the negative electrode. ground and a first and a second resistor for voltage distribution connected in parallel with a positive insulation resistor between the negative electrode and groundA third and fourth resistor for voltage distribution are provided between the positive electrode and the fourth resistor, and are connected in parallel with the negative insulation resistor. At this time, a first output signal is output from between the first and second resistors, and a second output signal is output from between the third and fourth resistors. In addition, a first switch is provided between the positive electrode and the first resistor, and a second switch is provided between the negative electrode and the fourth resistor. ground A 5V voltage source is connected between this and the third resistor.

[0008] However, the conventional insulation resistance measuring device described above requires two switches and a 5V voltage source. In addition, since the two switches are turned on / off, the switching operations of the switches are increased. This leads to a drawback that the circuit is complicated and the driving method is complicated. In addition, since the first and second output signals are input to the first and second input terminals of the analog-digital converter via two voltage distribution resistors, two or more input terminals of the analog-digital converter are required.

[0009] As the conventional techniques, the following documents can be mentioned. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Republic of Korea Patent No. 10-1771226 [Non-patent literature]

[0011] [Non-Patent Document 1] Internet blog (https: / / m.blog.naver.com / thewoodypark / 222037678937) Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention provides an insulation resistance measuring device that can reduce the number of switches and eliminate the need for a voltage source, thereby simplifying the configuration and driving method.

[0013] The present invention provides an insulation resistance measuring device that can reduce the number of output terminals and reduce the number of input terminals of an analog-to-digital converter. [Means for solving the problem]

[0014] An insulation resistance measuring device according to one aspect of the present invention is ground a positive insulation resistor provided between the ground and a negative insulation resistance provided between the positive electrode of the battery pack and ground a first resistor and a second resistor connected in series between the first resistor and the second resistor; ground and the negative terminal of the battery pack, an output terminal connected between the third and fourth resistors, and a switch connected between a contact point between the first and second resistors and the negative terminal of the battery pack.

[0015] The first and second resistors are connected in parallel with the positive isolation resistor, and the third and fourth resistors are connected in parallel with the negative isolation resistor.

[0016] When the switch is in an off state, a divided voltage of a first voltage between the positive insulation resistance and the negative insulation resistance is output from the output terminal, and when the switch is in an on state, a divided voltage of a second voltage between the positive insulation resistance and the negative insulation resistance is output from the output terminal, and the insulation resistance is calculated using the first and second voltages.

[0017] The first voltage is calculated by the following formula (1).

[0018]

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[0019] In the formula, V x1 is the first voltage, V pack1 is the battery pack voltage when the switch is in the off state, and R iso+ and R iso- are the resistance values ​​of the positive insulation resistor and the negative insulation resistor, respectively, and R 11 +R 12 =R p , R 13 +R 14 =R n It is.

[0020] The second voltage is calculated by the following formula (2).

[0021]

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[0022] In the formula, V x2 is the second voltage, V pack2 is the battery pack voltage when the switch is turned on, and R iso+ and R iso- are the resistance values ​​of the positive insulation resistor and the negative insulation resistor, respectively, and R 11 =R p ×(1-p), R 12 =R p ×p, R 11 +R 12 =R p , R 13 =R n ×(1-n), R 14 =R n ×n, R 13 +R 14 =R n It is.

[0023] The resistance value of the positive insulation resistor is calculated from the above formulas (1) and (2) according to the following formula (3).

[0024]

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[0025] The resistance value of the negative insulation resistor is calculated from the above formula (2) by the following formula (4).

[0026]

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[0027] The insulation resistance measuring device further includes a control unit that controls the switch, a voltage measuring unit that measures the output voltage of the output terminal and calculates the first and second voltages, a judgment unit that judges whether the voltage measured by the voltage measuring unit is within a set range, and a calculation unit that calculates resistance values ​​of a positive insulation resistance and a negative insulation resistance based on a judgment result by the judgment unit. Effect of the Invention

[0028] The insulation resistance measuring device of the present invention has a reduced number of switches compared to the conventional device and does not require a voltage source. Therefore, the configuration and driving method of the insulation resistance measuring device can be simplified. Also, one output signal is output from the insulation resistance measuring device and input to the analog-digital converter. Therefore, the analog-digital converter requires one input terminal to input the output signal of the insulation resistance measuring device. That is, the number of output terminals can be reduced compared to the conventional device, and therefore the number of input terminals of the analog-digital converter that inputs the output of the insulation resistance measuring device can be reduced. In short, the present invention can simplify the configuration and driving method of the insulation resistance measuring device compared to the conventional device, and can simplify the configuration of the peripheral device that inputs a signal from the insulation resistance measuring device compared to the conventional device. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a circuit diagram of a conventional insulation resistance measuring device. [Diagram 2] 1 is a circuit diagram of an insulation resistance measuring device according to an embodiment of the present invention. [Diagram 3] FIG. 4 is a block diagram of an insulation resistance measuring device according to another embodiment of the present invention. [Figure 4] FIG. 2 is an equivalent circuit diagram corresponding to a switch operation of the insulation resistance measuring device according to the embodiment of the present invention. [Diagram 5] FIG. 2 is an equivalent circuit diagram corresponding to a switch operation of the insulation resistance measuring device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. These embodiments are provided merely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0031] FIG. 1 is a circuit diagram of a conventional insulation resistance measuring device. The conventional insulation resistance measuring device is ground A positive insulation resistor Riso+ is provided between the negative pole HV- and ground and a negative insulation resistance Riso- provided between the

[0032] As shown in Figure 1, a conventional insulation resistance measuring device is used to measure the positive and negative poles. ground A first and a second resistor R1, R2 for voltage distribution are provided between the negative pole HV- and the positive insulation resistor Riso+ in parallel. groundBetween the positive electrode HV+ and the first resistor R1, a third and fourth resistor R3, R4 for voltage distribution are provided, which are connected in parallel with the negative insulation resistor Riso-. At this time, a first output signal ADC1 is outputted from between the first and second resistors R1, R2, and a second output signal ADC2 is outputted from between the third and fourth resistors R3, R4. That is, a distributed voltage between the first and second resistors R1, R2 is inputted to a first input terminal of an analog-digital converter, and a distributed voltage between the third and fourth resistors R3, R4 is inputted to a second input terminal of the analog-digital converter. In addition, a first switch SW1 is provided between the positive electrode HV+ and the first resistor R1, and a second switch SW2 is provided between the negative electrode HV- and the fourth resistor R4. In addition, ground A 5V voltage source is connected between the third resistor R3 and the ground The third resistor R3 and ground It is connected between the two and serves to apply voltage.

[0033] In such a conventional insulation resistance measuring device, the first and second switches SW1 and SW2 are repeatedly turned on and off at a set measurement period. At this time, the first and second switches SW1 and SW2 may be turned on or off simultaneously or alternately depending on the period. When the first switch SW1 is turned on, the positive pole HV+ and ground The positive voltage (Vpositive) between the negative pole HV- and ground A negative voltage (Vnegative) between is distributed and a second output signal ADC2 is measured.

[0034] However, the conventional insulation resistance measuring device described above requires two switches and a 5V voltage source. In addition, since the two switches are turned on / off, the switching operations of the switches are increased. This leads to disadvantages such as a complicated circuit and a complicated driving method. In addition, since the first and second output signals are input to the first and second input terminals of the analog-digital converter via two voltage distribution resistors, two or more input terminals of the analog-digital converter are required.

[0035] Fig. 2 is a circuit diagram of an insulation resistance measuring device according to one embodiment of the present invention, and Fig. 3 is a block diagram of an insulation resistance measuring device according to one embodiment of the present invention, that is, Fig. 3 is a block diagram showing the insulation resistance measuring device of the present invention and its peripheral devices.

[0036] 2 and 3, the insulation resistance measuring device according to an embodiment of the present invention can measure the positive insulation resistance Riso+ and the negative insulation resistance Riso- between the positive electrode HV+ and the negative electrode HV- of the battery pack 100. ground A negative insulation resistor Riso- is provided between the negative electrode HV- of the battery pack 100 and ground The insulation resistance measuring device according to an embodiment of the present invention for measuring such insulation resistance Riso+ and Riso- is provided between the positive electrode HV+ and ground A first and second resistors R11 and R12 for voltage distribution are provided between the positive insulation resistor Riso+ and the negative pole HV- and ground and a switch SW provided between the first and second resistors R11, R12 and the negative electrode HV-. That is, the insulation resistance measuring device according to one embodiment of the present invention has a reduced number of switches compared to the conventional technology described with reference to FIG. 1, and does not require a voltage source.

[0037] The first and second resistors R11 and R12 are connected to the positive pole HV+ ground and may be connected in parallel with the positive insulation resistor Riso+. In this case, the resistance value of the first resistor R11 and the resistance value of the second resistor R12 may have a set resistance ratio. Here, the set resistance ratio may be a ratio between the resistance value of the first resistor R11 and the resistance value of the second resistor R12 that is set to reduce and measure the voltage of the battery pack 100 applied to the first resistor R11.

[0038] The third and fourth resistors R13 and R14 are connected to the negative pole HV- ground and may be connected in parallel with the negative insulation resistor Riso-. In this case, the resistance value of the third resistor R13 and the resistance value of the fourth resistor R14 may have a set resistance ratio. Here, the set resistance ratio may be a ratio between the resistance value of the third resistor R13 and the resistance value of the fourth resistor R14 set to reduce and measure the voltage of the battery pack 100 applied to the third resistor R13. Also, an output signal ADC may be output from between the third and fourth resistors R13 and R14. The output signal ADC between the third and fourth resistors R13 and R14, i.e., the distributed voltage of the third and fourth resistors R13 and R14, may be input to an analog-digital converter. That is, the insulation resistance measuring device according to one embodiment of the present invention outputs one output signal, which is input to the analog-digital converter. Therefore, the analog-digital converter requires one input terminal to input the output signal of the insulation resistance measuring device. In other words, the number of output terminals can be reduced compared to the conventional art, and therefore the number of input terminals of the analog-digital converter that inputs the output of the insulation resistance measuring device can be reduced.

[0039] The switch SW is provided between the first and second resistors R11, R12 and the negative electrode HV-. That is, the switch SW is provided between a node between the first and second resistors R11, R12 and the negative electrode HV-. Such a switch SW can be turned on / off to adjust the voltage of the output terminal ADC. That is, depending on whether the switch SW is turned on / off, the first voltage V x1 The distribution voltage of and the second voltage V x2 In this way, the first voltage V x1 The distribution voltage of and the second voltage V x2 The divided voltage is output, and the first voltage V x1 and a second voltage V x2 Then, the resistance values ​​of the positive insulation resistance Riso+ and the negative insulation resistance Riso- can be calculated.

[0040] On the other hand, as shown in FIG. 3, the insulation resistance measuring device according to the present invention may further include a control unit 210 that controls switch SW, a voltage measuring unit 220 that measures the voltage of the output signal from between the third and fourth resistors R13, R14, a judgment unit 230 that judges whether the voltage measured by the voltage measuring unit 220 is within a set range, and a calculation unit 240 that calculates the resistance values ​​of the positive insulation resistance Riso+ and the negative insulation resistance Riso- based on the judgment result of the judgment unit 230.

[0041] The control unit 210 can control the switch SW. That is, the control unit 210 can control the switch SW to turn the switch SW on / off. The control unit 210 can control the switch SW periodically and can make the on / off cycles equal. Needless to say, the control unit 210 can also control the switch SW intermittently and can make the on / off cycles different. On the other hand, the control unit 210 can control the switch SW based on the determination result in the determination unit 230.

[0042] The voltage measurement unit 220 measures the voltage of the output signal between the third and fourth resistors R13 and R14. That is, the first voltage V x1 The distribution voltage of and the second voltage V x2 The voltage measurement unit 220 outputs a divided voltage V x1 and a second voltage V x2 That is, the voltage measurement unit 220 calculates the first voltage V x1 The distribution voltage of and the second voltage V x2 Measure the divided voltage of and calculate the first voltage V x1 and a second voltage V x2 At this time, the voltage measurement unit 220 calculates the first voltage V x1 Calculate the second voltage V x2 The voltage measurement unit 220 may also include an analog-digital converter that converts an analog voltage signal into a digital voltage signal. That is, the voltage measurement unit 220 includes an analog-digital converter and calculates the first voltage V outputted between the third and fourth resistors R13 and R14. x1 The distribution voltage of and the second voltage V x2 After the analog voltage signal of the distributed voltage is converted into a digital voltage signal, the voltage can be measured.

[0043] The determination unit 230 determines the first voltage V x1 and a second voltage V x2 That is, the determination unit 230 can determine whether the first voltage V x1 and a second voltage V x2 The determination unit 230 can determine whether the first voltage V is within a set range based on the measured value of the first voltage V and transmit the determination result to the control unit 210 and the calculation unit 240. x1 The measured value of the first voltage V is compared with the set range value. x1 If the measured value of is within the set range, the first voltage V x1Similarly, the determination unit 230 can determine that the second voltage V x2 The measured value of is compared with the set range value, and a second voltage V x2 If the change in the second voltage V x2 It can be determined that the condition is normal.

[0044] On the other hand, the control unit 210 determines that the first voltage V x1 is determined to be normal, the switch SW is turned off, and the second voltage V x2 Therefore, the control unit 210 can turn on the switch SW when it is determined that the insulation resistance is normal. x1 and the second voltage V x2 By flexibly changing the setting depending on whether or not the measurement has converged, the time required to measure the insulation resistance can be reduced.

[0045] The calculation unit 240 determines the first voltage V x1 The first voltage V x1 , the second voltage V x2 The second voltage V x2 and the voltage of the battery pack 100 at the time of calculation, the resistance values ​​of the positive insulation resistance Riso+ and the negative insulation resistance Riso- can be calculated. At this time, the calculation unit 240 can calculate the resistance values ​​of the positive insulation resistance Riso+ and the negative insulation resistance Riso- using the first and second voltages according to (Equation 1) and (Equation 2) and (Equation 3) and (Equation 4) described later. Meanwhile, the voltage of the battery pack 100 can be received from a Battery Management System (BMS) that manages the battery pack.

[0046] As described above, the insulation resistance measuring device according to one embodiment of the present invention reduces the number of switches and does not require a voltage source, compared to the conventional technology described with reference to FIG. 1. Furthermore, in the present invention, one output signal is output and input to an analog-to-digital converter. Therefore, the analog-to-digital converter requires one input terminal to input the output signal of the insulation resistance measuring device. In other words, the number of output terminals can be reduced compared to the conventional technology, and therefore the number of input terminals of the analog-to-digital converter that inputs the output of the insulation resistance measuring device can be reduced.

[0047] 4 and 5 are equivalent circuit diagrams of an insulation resistance measuring device according to the on / off state of a switch, where FIG. 4 is the equivalent circuit diagram when the switch is off, and FIG. 5 is the equivalent circuit diagram when the switch is on.

[0048] As shown in Figure 4, when the switch is turned off, the first voltage V is output between the positive isolation resistor Riso+ and the negative isolation resistor Riso-. x1 can be calculated by the following formula (1).

[0049]

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[0050] In the formula, V x1 is the first voltage, V pack1 is the battery pack voltage when the switch is turned off, and R iso+ and R iso- are the resistance values ​​of the positive insulation resistor and the negative insulation resistor, respectively, and R p , R n is calculated as follows:

[0051] R 11 +R 12 =R p , R 13 +R 14 =R n

[0052] As shown in Figure 5, when the switch is turned on, a second voltage V is output between the positive insulation resistor Riso+ and the negative insulation resistor Riso-. x2 can be calculated by the following formula (2).

[0053]

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[0054] In the formula, V x2 is the second voltage, V pack2 is the battery pack voltage when the switch is turned on, and R iso+ and R iso- are the resistance values ​​of the positive insulation resistor and the negative insulation resistor, respectively, and R p , R n It is calculated as follows:

[0055] R 11 =R p ×(1-p), R 12 =R p ×p, R 11 +R 12 =R p R 13 =R n ×(1-n), R 14 =R n ×n, R 13 +R 14 =R n

[0056] From the above formulas (1) and (2), the resistance value of the positive insulation resistance Riso+ and the resistance value of the negative insulation resistance Riso- can be calculated from formulas (3) and (4), respectively. That is, formula (3) is a formula for calculating the resistance value of the positive insulation resistance Riso+ by simultaneously using formulas (1) and (2), and formula (4) is a formula for calculating the resistance value of the negative insulation resistance Riso- using formula (2).

[0057]

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[0058]

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[0059] Although the technical concept of the present invention as described above has been specifically described based on the above embodiment, it should be noted that the above embodiment is for the purpose of explanation and not for the purpose of limitation. It should be understood that a person skilled in the art of the present invention can implement various embodiments within the scope of the technical concept of the present invention.

[0060] The reference numerals in the drawings used in the present invention are as follows: [Explanation of symbols]

[0061] 100: Battery pack R11, R12, R13, R14: 1st resistor to 4th resistor SW: Switch V x1 , V x2 : first and second voltages 210: Control unit 220: Voltage measurement unit 230: Judgment Department 240: Calculation section

Claims

1. An insulation resistance measuring device for measuring a positive insulation resistance provided between a positive electrode of a battery pack and a ground, and a negative insulation resistance provided between the ground and a negative electrode of the battery pack, comprising: a first resistor and a second resistor connected in series between a positive electrode of the battery pack and a ground; a third resistor and a fourth resistor connected in series between the ground and the negative terminal of the battery pack; an output terminal connected between the third resistor and the fourth resistor; a switch connected between a node between the first resistor and the second resistor and a negative terminal of the battery pack; An insulation resistance measuring device comprising:

2. 2. The insulation resistance measuring device according to claim 1, wherein the first resistor and the second resistor are connected in parallel with the positive insulation resistance, and the third resistor and the fourth resistor are connected in parallel with the negative insulation resistance.

3. When the switch is in an off state, a divided voltage of a first voltage between the positive insulation resistor and the negative insulation resistor is output from the output terminal; When the switch is in an on state, a divided voltage of a second voltage between the positive insulation resistor and the negative insulation resistor is output from the output terminal; 3. The insulation resistance measuring device according to claim 1, wherein the positive insulation resistance and the negative insulation resistance are calculated using the first voltage and the second voltage.

4. The first voltage is calculated by the following formula (1): [0010] …（１） When the resistance values ​​of the first resistor, the second resistor, the third resistor, and the fourth resistor are R 11 , R 12 , R 13 , and R 14 , respectively, in the formula, V ｘ１ is the first voltage, V ｐａｃｋ１ is the battery pack voltage between the positive and negative electrodes of the battery pack at the time when V x1 is calculated when the switch is in the off state, and R ｉｓｏ＋ and R ｉｓｏ－ are the resistance values ​​of the positive insulation resistor and the negative insulation resistor, respectively, and R １１ +R １２ = R Ｐ , R １３ +R １４ = R ｎ That is, 4. The insulation resistance measuring device according to claim 3.

5. The second voltage is calculated by the following formula (2): [0025] …（２） In the formula, V ｘ２ is the second voltage, V ｐａｃｋ２ is the battery pack voltage between the positive and negative electrodes of the battery pack at the time when V x2 is calculated when the switch is turned on, and R ｉｓｏ＋ and R ｉｓｏ－ are the resistance values ​​of the positive insulation resistor and the negative insulation resistor, respectively, and R １１ = R ｐ ×(1-p), R １２ = R ｐ ×p, R １１ +R １２ = R ｐ , R １３ = R ｎ ×(1-n), R １４ = R ｎ ×n, R １３ +R １４ = R ｎ That is, 5. The insulation resistance measuring device according to claim 4.

6. The resistance value of the positive insulation resistance is calculated from the above formula (1) and formula (2) according to the following formula (3): [0030] …（３） The insulation resistance measuring device according to claim 5, wherein the insulation resistance is calculated by the following formula:

7. The resistance value of the negative insulation resistance is calculated from the above formula (2) by the following formula (4): [0045] …（４） The insulation resistance measuring device according to claim 6, wherein the insulation resistance is calculated by the following formula:

8. A control unit that controls the switch; a voltage measurement unit that measures an output voltage of the output terminal and calculates the first voltage and the second voltage; a determination unit that determines whether the voltage measured by the voltage measurement unit is within a set range; a calculation unit that calculates resistance values ​​of the positive insulation resistor and the negative insulation resistor based on a result of the judgment by the judgment unit; The insulation resistance measuring device according to claim 7 , further comprising:

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