Apparatus for measuring insulation resistance and battery system including the same

Abstract

An apparatus for measuring insulation resistance between a battery including a plurality of battery cells and ground includes a first voltage dividing unit that distributes a voltage between a positive electrode of the battery and ground, a second voltage dividing unit that distributes a voltage between a negative electrode of the battery and ground, a first switch SW1 that connects a positive electrode of the battery to the first voltage dividing unit, a second switch SW2 that connects a negative electrode of the battery to the second voltage dividing unit, and reduces a current switching period of the first and second switches compared to a previous switching period when a first voltage that is an output of the first voltage dividing unit becomes saturated during an on-period of the first switch SW1 or a second voltage that is an output of the second voltage dividing unit becomes saturated during an on-period of the second switch SW2.

Description

[Technical field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0161633 dated November 22, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an apparatus for measuring insulation resistance and a battery system including the same. [Background technology]

[0003] In devices such as electric vehicles and hybrid vehicles that use high-output, high-voltage (e.g., several hundred volts) batteries, it is necessary to maintain good insulation of the battery from the ground (e.g., the vehicle body). If the battery insulation is not maintained, a large leakage current will flow from the battery, which may cause malfunctions of surrounding electronic devices.

[0004] Therefore, it is important to calculate whether the insulation resistance between the battery and ground falls below a certain value and to prevent this. Conventionally, the insulation resistance value is calculated by alternately turning on and off a switch connected to the positive and negative poles of the battery and detecting the voltage in each state. However, this method has problems in that it takes a long time to calculate the insulation resistance and it is not possible to accurately diagnose the point at which the insulation resistance breaks down.

[0005] Conventionally, the insulation resistance is measured for a calculated time. The cycle of turning the switch on and off varies depending on the Y capacitance value of the vehicle. However, the Y capacitance value of each vehicle differs, making it difficult to measure accurately, so the maximum Y capacitance value was used. However, this has the problem that it takes a long time to calculate the insulation resistance and can delay the diagnosis of the point of breakdown of the insulation resistance. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention seeks to measure insulation resistance.

[0007] The present invention seeks to diagnose the point in time when insulation resistance breaks down. [Means for solving the problem]

[0008] According to one aspect of the invention, an apparatus for measuring insulation resistance between a battery including a plurality of battery cells and ground includes a first voltage division unit that distributes a voltage between a positive electrode of the battery and ground, a second voltage division unit that distributes a voltage between a negative electrode of the battery and ground, a first switch SW1 that connects the positive electrode of the battery to the first voltage division unit, a second switch SW2 that connects the negative electrode of the battery to the second voltage division unit, and when a first voltage that is an output of the first voltage division unit becomes saturated during an on-period of the first switch SW1 or a second voltage that is an output of the second voltage division unit becomes saturated during an on-period of the second switch SW2, a current switching period of the first and second switches is reduced from a previous switching period.

[0009] The insulation resistance measurement device can adjust the on-period of the switch based on the point in time when the first voltage or the second voltage becomes saturated.

[0010] The insulation resistance measuring device can reset the current switching period to a predetermined initial switching period when a period in which the first voltage or the second voltage decreases occurs during an on-period of the first switch or the second switch.

[0011] The insulation resistance measuring device further includes a first insulation resistance between a positive electrode of the battery and ground, and a second insulation resistance between a negative electrode of the battery and ground, and the control unit can calculate the first insulation resistance value and the second insulation resistance value based on the first voltage and the second voltage.

[0012] The initial switching period can be set based on the capacitance of a Y capacitor connected in parallel between the battery and the external device.

[0013] According to one aspect of the invention, a battery system includes a battery including a plurality of battery cells, and an insulation resistance measuring device for measuring insulation resistance between the battery and ground, the insulation resistance measuring device including a first voltage dividing unit for distributing a voltage between a positive electrode of the battery and ground, a second voltage dividing unit for distributing a voltage between a negative electrode of the battery and ground, a first switch SW1 for connecting the positive electrode of the battery to the first voltage dividing unit, a second switch SW2 for connecting the negative electrode of the battery to the second voltage dividing unit, and a current switching period of the first and second switches is reduced from a previous switching period when a first voltage output from the first voltage dividing unit becomes saturated during an on-period of the first switch SW1 or a second voltage output from the second voltage dividing unit becomes saturated during an on-period of the second switch SW2.

[0014] The on-time of the switch can be adjusted based on when the first voltage or the second voltage saturates.

[0015] When a period in which the first voltage or the second voltage decreases occurs during an on-period of the first switch or the second switch, the current switching period can be reset to a predetermined initial switching period.

[0016] The battery further includes a first insulation resistor between the positive electrode of the battery and ground, and a second insulation resistor between the negative electrode of the battery and ground, and the control unit can calculate the first insulation resistance value and the second insulation resistance value based on the first voltage and the second voltage.

[0017] The initial switching period can be set based on the capacitance of a Y capacitor connected in parallel between the battery and the external device. Effect of the Invention

[0018] The present invention can reduce the insulation resistance measurement time.

[0019] The present invention can accurately diagnose the time point of insulation resistance breakdown. [Brief description of the drawings]

[0020] [Figure 1] 1 is a circuit diagram illustrating an insulation resistance measuring circuit applied to a battery system according to an embodiment. [Diagram 2] 4 is a circuit diagram illustrating a first circuit formed in the battery system by a first switching mode. FIG. [Diagram 3] FIG. 4 is a circuit diagram illustrating a second circuit formed in the battery system by a second switching mode. [Figure 4] FIG. 11 is a waveform diagram showing a switch control signal and a voltage resulting from the switch control signal when measuring insulation resistance in the related art. [Diagram 5] FIG. 4 is a waveform diagram showing a switch control signal and a voltage measurement result thereof when a circuit for measuring insulation resistance according to an embodiment of the present invention is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the attached drawings, and identical or similar components will be given the same or similar reference numerals, and redundant description thereof will be omitted. The suffixes "module" and / or "part" for components used in the following description are given or mixed for the sake of ease of description, and do not have any distinct meaning or role. In addition, when it is determined that a detailed description of related known technology may obscure the gist of the embodiments disclosed herein in describing the embodiments disclosed herein, the detailed description will be omitted. In addition, the attached drawings are merely for the purpose of making the embodiments disclosed herein easily understandable, and the technical ideas disclosed herein are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or alternatives included in the ideas and technical scope of the present invention.

[0022] Terms including ordinal numbers such as "first", "second", etc. may be used to describe various components, but the components are not limited to the terms. The terms are used only to distinguish one component from another.

[0023] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0024] In this application, the terms "comprise" or "have" and the like are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof set forth in the specification, but should be understood as not precluding the presence or additional possibility of one or more other features, number, step, operation, component, part, or combination thereof.

[0025] FIG. 1 is a circuit diagram showing an insulation resistance measuring circuit applied to a battery system according to an embodiment.

[0026] The battery system 10 may include a battery 20, a first insulation resistor 11 electrically connected between a positive terminal NP of the battery 20 and ground, a second insulation resistor 12 electrically connected between a negative terminal NN and ground, and an insulation resistance measurement circuit 100.

[0027] Each of these two insulation resistors 11, 12 is a resistor that indicates the insulation state between the ground and the battery 20. If the insulation state between the battery 20 and the ground is well maintained, the first and second insulation resistors 11, 12 should have a sufficiently large value. However, if the insulation state between the battery 20 and the ground deteriorates, at least one of the first and second insulation resistors 11, 12 may become lower than a predetermined critical resistance value.

[0028] The battery system 10 may also include a positive-side parasitic capacitor CP(+) electrically connected to a positive terminal NP of the battery 20 and a negative-side parasitic capacitor CP(-) electrically connected to a negative terminal NN of the battery 20. The parasitic capacitors CP(+) and CP(-) are capacitors for indicating capacitance components formed between the ground and the battery 20. As shown in FIG 1, the parasitic capacitor CP(+) is connected in parallel to the insulation resistor 11, and the parasitic capacitor CP(-) is connected in parallel to the insulation resistor 12.

[0029] The insulation resistance measuring circuit 100 is a circuit for measuring the resistance values ​​of a first insulation resistor 11 and a second insulation resistor 12 connected to a battery 20.

[0030] The insulation resistance measuring circuit 100 may include a first voltage dividing unit 110 and a second voltage dividing unit 120. The first voltage dividing unit 110 includes a first protection resistor 111 and a first reference resistor 112. The first protection resistor 111 and the first reference resistor 112 may be connected through a first common node NC1. In addition, the second voltage dividing unit 120 includes a second protection resistor 121 and a second reference resistor 122. The second protection resistor 121 and the second reference resistor 122 may be connected through a second common node NC2.

[0031] The resistance values ​​of the first protection resistor 111 , the first reference resistor 112 , the second protection resistor 121 , and the second reference resistor 122 can be stored in advance in the memory 180 .

[0032] Furthermore, according to an embodiment, the insulation resistance measuring circuit 100 may further include a reference voltage source 140 coupled between the second reference resistor 122 and ground.

[0033] The reference voltage source 140 may supply a predetermined voltage relative to the ground to the second voltage dividing unit 120. The reference voltage source 140 may supply a voltage VDC with respect to the ground to the second voltage dividing unit 120. A second protective resistor 121 and a second reference resistor 122 are connected in series between the reference voltage source 140 and a negative terminal NN of the battery 20, and a voltage applied between a second common node NC2 to which the second protective resistor 121 and the second reference resistor 122 are connected and the ground is input to the voltage measuring unit 150. A voltage value of the voltage VDC supplied from the reference voltage source 140 may be stored in advance in the memory 180.

[0034] The insulation resistance measuring circuit 100 may further include a switching unit 130.

[0035] The switching unit 130 may include a first switch SW1 and a second switch SW2. The first switch SW1 may be connected between the positive terminal NP and the first voltage dividing unit 110. The second switch SW2 may be connected between the positive terminal NN and the second voltage dividing unit 120.

[0036] The switching unit 130 may further include a safety switch SW3. The safety switch SW3 may be installed between two battery cells 21, 22 adjacent to each other and connected in series in the battery 20. When the safety switch SW3 is turned off, the use of the battery 20 is interrupted. The switch driving unit 160 may control the safety switch SW3 independently of the first switch SW1 and the second switch SW2.

[0037] The first switch SW1 and the second switch SW2 can be controlled independently of each other in response to a signal output from the switch driver 160. That is, the first switch SW1 and the second switch SW2 can be turned on or off. Therefore, the switch modes can include a first switching mode in which the first switch SW1 and the second switch SW2 are 'turned on-turned off', a second switching mode in which they are 'turned off-turned on', a third switching mode in which they are 'turned on-turned on', and a fourth switching mode in which they are 'turned off-turned off'. Each switching mode can be executed only while the battery 20 is in an unloaded state. The unloaded state can be said to be a state in which charging and discharging of the battery 20 are suspended.

[0038] For example, the switch driver 160 may turn on the first switch SW1 and turn off the second switch SW2 in the first switching mode to form a first circuit CC1 (see FIG. 2). The first circuit CC1 is a circuit in which the first voltage divider 110 is connected to the positive terminal NP and the second voltage divider 120 is isolated from the negative terminal NN. This will be described later with reference to FIG. 2.

[0039] In the second switching mode, the switch driver 160 may turn off the first switch SW1 and turn on the second switch SW2 to form a second circuit CC2 (see FIG. 3). The second circuit CC2 refers to a circuit in which the first voltage divider 110 is isolated from the positive terminal NP and the second voltage divider 120 is connected to the negative terminal NN. This will be described later with reference to FIG. 3.

[0040] In the third switching mode, the switch driver 160 can turn on both the first switch SW1 and the second switch SW2.

[0041] In addition, the switch driver 160 can turn off both the first switch SW1 and the second switch SW2 in the fourth switching mode.

[0042] The voltage measurement unit 150 can measure the voltages of the first common node NC1 and the second common node NC2. Specifically, the voltage applied to the first voltage distribution unit 110 is divided according to the ratio between the resistance value of the first protective resistor 111 and the resistance value of the first reference resistor 112, and can be measured by the voltage measurement unit 150. Similarly, the voltage applied to the second voltage distribution unit 120 is divided according to the ratio between the resistance value of the second protective resistor 112 and the resistance value of the second reference resistor 122, and can be measured by the voltage measurement unit 150. That is, the voltage measurement unit 150 can measure a voltage applied between the first common node NC1 and the ground (hereinafter, referred to as a first voltage V1) and a voltage applied between the second common node NC2 and the ground (hereinafter, referred to as a second voltage V2). The first voltage V1 may be equal to the voltage across the first reference resistor 112, and the second voltage V2 may be equal to the sum of the voltage across the second reference resistor 122 and VDC.

[0043] The voltage measurement unit 150 may include a first input port IN1 connected to a first common node NC1 and a second input port IN2 connected to a second common node NC2. The voltage measurement unit 150 may include a voltage sensor and an analog-digital converter (ADC). The voltage sensor outputs an analog signal corresponding to a voltage input through the first input port IN1 and an analog signal corresponding to a voltage input through the second input port IN2 to the ADC. The ADC may convert the analog signal of the first input port IN1 into a digital signal and convert the analog signal of the second input port IN2 into a digital signal.

[0044] The voltage measurement unit 150 measures a battery voltage VBat between the positive and negative electrodes of the battery 20. The battery voltage VBat may be measured by the voltage measurement unit 150 when the third switching mode is being executed. Alternatively, a voltage sensor (not shown) provided separately from the voltage measurement unit 150 may measure the battery voltage VBat and output a measurement signal indicating the measured terminal voltage VBat to the controller 170.

[0045] The controller 170 is operatively coupled to the voltage measurement unit 150 and the switch driver 160. The controller 170 controls the switch driver 160 based on a measurement signal output from the voltage measurement unit 150. The controller 170 can be realized in terms of hardware, including at least one of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), microprocessors, and other electrical units for performing functions.

[0046] The memory 180 may additionally store data, instructions, and software required for the overall operation of the battery system 10. The memory 120 may include at least one type of storage medium among a flash memory type, a hard disk type, a solid state disk type (SSD type), a silicon disk drive type (SDD type), a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), and a programmable read-only memory (PROM).

[0047] 2 or 3, a method for the insulation resistance measuring circuit 100 according to the present invention to calculate the resistance value of the first insulation resistor 11 and the resistance value of the second insulation resistor 12 will be described in detail. Hereinafter, the resistance value of the first insulation resistor 11 will be referred to as the 'first insulation resistance value' or 'RLeak(+)', and the resistance value of the second insulation resistor 12 will be referred to as the 'second insulation resistance value' or 'RLeak(-)'.

[0048] FIG. 2 is a circuit diagram illustrating a first circuit formed in the battery system by the first switching mode.

[0049] After a certain amount of time has passed since the first switching mode was started, the first voltage V1 reaches a stable state where it does not change any more over time due to the parasitic capacitors CP(+) and CP(-). Therefore, for the sake of convenience, the parasitic capacitors CP(+) and CP(-) will be omitted.

[0050] In the circuit CC1, the first protection resistor 111 and the first reference resistor 112 may be connected in series between the positive terminal NP of the battery 20 and the ground. Specifically, one end of each of the first protection resistor 111 and the first reference resistor 112 is connected through a first common node NC1. The other end of the first protection resistor 111 is connected to or isolated from the positive terminal NP through a first switch SW1. The other end of the first reference resistor 112 is connected to the ground.

[0051] Here, the current flowing from the positive terminal NP to the first protective resistor 111 and the first reference resistor 112 is called I1, the current flowing from the positive terminal NP to the first insulation resistor 11 is called I2, and the current flowing through the second insulation resistor 12 is called I3.

[0052] Hereinafter, the first voltage V1 is expressed as in the following equation (1).

number

[0053] If equation (1) is rearranged with respect to I1, it can be expressed as equation (2) below.

number

[0054] In addition, since the first voltage dividing unit 110 and the first insulation resistor 11 are electrically connected in parallel, the following relationship (Equation 3) is established.

number

[0055] By rearranging equation (3) using equation (2), the following equation (4) can be derived.

number

[0056] On the other hand, if Kirchhoff's current law is applied to the first circuit CC1, the following equation (5) is derived.

number

[0057] By substituting the above-mentioned formulas (2) and (4) into the above-mentioned formula (5) and rearranging it with respect to I3, the following formula (6) can be obtained.

number

[0058] Meanwhile, when the battery voltage is VBat, applying Kirchhoff's voltage law to the first circuit CC1 leads to the first equation in the following equation (7): Then, by rearranging the first equation using I2 and I3 obtained through equations (4) and (6), the last equation in the following equation (7) can be derived.

number

[0059] The equation in the last line included in Equation 7 is one of two circuit equations required to calculate the first insulation resistance value RLeak(+) and the second insulation resistance value RLeak(-).

[0060] FIG. 3 is a circuit diagram illustrating a second circuit formed in the battery system by the second switching mode.

[0061] As in the first switching mode described above, after a certain amount of time has passed since the second switching mode was started, the second voltage V2 reaches a stable state where it does not change any more over time due to the parasitic capacitors CP(+) and CP(-). Therefore, for the sake of convenience, the parasitic capacitors CP(+) and CP(-) are omitted.

[0062] In the circuit CC2, the second protection resistor 121 and the second reference resistor 122 may be connected in series between the negative terminal NN of the battery 20 and the reference voltage source 140. Specifically, one end of each of the second protection resistor 121 and the second reference resistor 122 is connected to each other through a second common node NC2. The other end of the second protection resistor 121 is connected to or isolated from the negative terminal NN through a second switch SW2. The other end of the second reference resistor 122 is connected to the reference voltage source 140.

[0063] Here, the current flowing from the reference voltage source 140 through the second reference resistor 122 and the second protective resistor 121 is called I1, the current flowing through the second insulation resistor 12 is called I2, and the current flowing from the positive terminal NP through the first insulation resistor 11 is called I3.

[0064] Then, the second voltage V2 is expressed by the following equation (8).

number

[0065] If the above-mentioned formula (8) is rearranged with respect to I1, it can be expressed as the following formula (9).

number

[0066] In addition, since the second insulation resistor 12 is electrically connected in parallel to the series connection circuit of the second voltage dividing unit 120 and the reference voltage source 140, the following relationship (Equation 10) is established.

number

[0067] By rearranging equation (10) using equation (9), the following equation (11) can be derived.

number

[0068] On the other hand, if Kirchhoff's current law is applied to the second circuit CC2, the following equation (12) is derived.

number

[0069] By substituting the above-mentioned formulas (9) and (11) into the above-mentioned formula (12) and rearranging it with respect to I3, it can be expressed as the following formula (13).

number

[0070] Meanwhile, when the battery voltage is VBat, applying Kirchhoff's voltage law to the second circuit CC2 leads to the first line of the equation included in the following equation (14). Then, by rearranging the first line of the equation using I2 and I3 obtained through equations (11) and (13), the last line of the equation included in the following equation (14) can be derived.

number

[0071] The equation in the last line included in (Equation 14) is the remaining one of the two circuit equations for calculating the first insulation resistance value RLeak(+) and the second insulation resistance value RLeak(-).

[0072] The solution of the simultaneous equations including the equation in the last line of (Equation 7) and the equation in the last line of (Equation 14) can be expressed as shown in the following (Equation 15).

number

[0073] In equation (15), R1, R2, and VDC are each a predetermined value, and VBat, the first voltage V1, and the second voltage V2 are each a value measured by the voltage measurement unit 150. The voltage measurement unit 150 outputs measurement signals indicating VBat, the first voltage V1, and the second voltage V2, respectively, to the controller 170. The first voltage V1 and the second voltage V2 can each be measured within a predetermined short period (e.g., 5 seconds) before and after the point in time when VBat is measured.

[0074] The controller 170 can calculate the first insulation resistance value RLeak(+) and the second insulation resistance value RLeak(-) using the above formula (15) based on VBat, the first voltage V1, and the second voltage V2 indicated by the measurement signal output from the voltage detection unit 130.

[0075] The controller 170 can compare at least one of the first insulation resistance value RLeak(+) and the second insulation resistance value RLeak(-) with a given critical resistance value. The controller 170 diagnoses whether the insulation state of the first and second insulation resistors 11, 12 between the battery 20 and the ground is maintained. That is, the controller 170 monitors whether the first insulation resistance value RLeak(+) or the second insulation resistance value RLeak(-) is equal to or lower than the critical resistance value.

[0076] The insulation resistance measuring circuit 100 can transmit the diagnosis results of the first and second insulation resistors 11, 12 to an external device. The external device may be, for example, an ECU of a vehicle.

[0077] The insulation resistance measuring circuit 100 can output a warning message if the insulation between the battery 20 and the ground is not well maintained. The warning message may be information corresponding to the diagnosis results of the first and second insulation resistors 11, 12. The warning message may be an LED, an LCD, an alarm, or a combination of these. The controller 170 may include a processor, an application-specific integrated circuit (ASIC), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., known in the technical field to which the present invention belongs, for calculating the insulation resistance using the above-mentioned equation (15) and executing various control logics.

[0078] FIG. 4 is a waveform diagram showing switch control signals and resulting voltages when measuring insulation resistance in the conventional method.

[0079] The controller 170 may control the switch driver 160 so that the first switch SW1 and the second switch SW2 operate with a constant switching period. A signal used by the switch driver 160 to control the first switch SW1 is referred to as a first switch signal S1, and a signal used by the switch driver 160 to control the second switch SW2 is referred to as a second switch signal S2.

[0080] As described above, the voltage at the first common node NC1 measured by the voltage measuring section 150 is referred to as the first voltage V1, and the voltage at the second common node NC2 is referred to as the second voltage V2.

[0081] When the battery system 10 is connected to an external device, the controller 170 may calculate a tau value based on a Y capacitor of a capacitor connected in parallel between the battery system 10 and the external device. Here, the external device may be a vehicle. The controller 170 may then calculate a saturation time of the first voltage V1 and the second voltage V2 based on the calculated tau value and set a switching period Ts including the saturation time. The switching period Ts refers to a period from when the first switch SW1 is turned on to when the first switch SW1 is turned on the next time, or a period from when the second switch SW2 is turned on to when the second switch SW2 is turned on the next time.

[0082] It takes a certain amount of time for the first voltage V1 and the second voltage V2 to stabilize by the Y capacitor. The first voltage V1 and the second voltage V2 used in the insulation resistance measurement must be saturation voltages in a stabilized state. Hereinafter, the saturation voltage will be referred to as Vth. Therefore, the saturation voltages of the first and second voltages V1 and V2 can be used in the insulation resistance measurement. In FIG. 4, the saturation voltages Vth1 and Vth2 are shown to be at a constant level in consideration of the fact that the insulation resistance does not change within a short time, but the invention is not limited thereto.

[0083] On the other hand, when the battery system 10 is electrically isolated from the external device, the Y capacitance value may be very small. In such a case, the controller 170 can set the minimum switching period Ts.

[0084] However, as mentioned above, the Y capacitor value may differ from vehicle to vehicle, and conventionally, the controller 170 may set the switching period Ts based on the maximum Y capacitor value that may be possessed when the battery system 10 is connected to the vehicle.

[0085] For example, FIG. 4 shows a case where the switching period Ts of the insulation resistance measurement circuit 100 is 10 seconds. The first switch signal S1 can control the first switch SW1 to repeat an on period and an off period in a 10-second period. Therefore, the first switch SW1 repeats on and off every 5 seconds. The second switch signal S2 can control the second switch SW2 to repeat an off period and an on period in a 10-second period. Therefore, the second switch SW2 also repeats on and off every 5 seconds.

[0086] The first voltage V1 may saturate after a certain time has elapsed. Here, saturation may mean that the voltage does not increase any more during the on-period of the switch and the voltage value is maintained. The first voltage V1 may saturate during the on-period of the first switch SW1.

[0087] However, as shown in FIG. 4, since the on-period of the first switch SW1 according to the switching period Ts has not yet elapsed even after the first voltage V1 is saturated, the first voltage V1 can be maintained as the saturation voltage Vth1 for the remaining on-period of the first switching signal S1 from the point at which the first voltage V1 reaches the voltage value of the saturation voltage Vth1 to the point at which the entire on-period has elapsed.

[0088] Similarly, the second voltage V2 may also saturate after a certain time has elapsed, but since the on-period of the second switch SW2 according to the switching period Ts has not yet elapsed even after the second voltage V2 saturates, the second voltage V1 may also be maintained as the saturation voltage Vth2 for the remaining on-period of the second switching signal S2.

[0089] In this way, the longer the period during which the first voltage V1 and the second voltage V2 are maintained as the saturation voltage, the more unnecessary time is required for the insulation resistance measurement.

[0090] 4, an abnormal voltage event VP may occur while the voltage measuring unit 150 is measuring the first voltage V1. The abnormal voltage event VP may include a case where the first voltage V1 or the second voltage V2 increases suddenly and then decreases suddenly. The abnormal voltage event VP may occur due to various reasons such as insulation resistance breakdown, measurement error, etc., and the voltage (e.g., V1, V2) value required for measuring the insulation resistance may not be measured accurately due to the abnormal voltage event VP.

[0091] Since the value of the first voltage V1 measured in the section including the abnormal voltage event VP is not effective for measuring the insulation resistance, the insulation resistance must be measured using the first voltage V1 measured in the next switching period, i.e., there may be a waiting time until the next switching period is completed in order to accurately measure the insulation resistance.

[0092] For example, as shown in Fig. 4, if an abnormal voltage event VP occurs in the first voltage V1 during the ON period of the first switch SW1, it may be difficult to measure a valid voltage value for the first voltage V1 in that period. Therefore, in order to obtain a valid voltage value of the first voltage V1, it is necessary to wait an additional time (at least 10 seconds) until the next ON period of the first switch SW1 ends.

[0093] As a result, it was previously impossible to know exactly when an insulation resistance abnormal voltage event occurred, and when a problem occurred, it was unclear whether it was a problem with an external device or an internal problem in the battery system.

[0094] FIG. 5 is a waveform diagram showing a switch control signal and a voltage measurement result thereof when a circuit for measuring insulation resistance according to an embodiment of the present invention is used.

[0095] FIG. 5 also shows the saturation voltage Vth at a constant level, taking into consideration that the insulation resistance does not change over a short period of time, but the invention is not limited to this.

[0096] The controller 170 can set the initial switching period Ts1 based on the maximum Y-capacitor value that the battery system 10 and the vehicle can have when coupled together.

[0097] For example, the controller 170 may calculate a tau value based on a Y capacitor, which is a capacitor connected in parallel between the battery system 10 and an external device, calculate a saturation time of the first voltage V1 and the second voltage V2 based on the calculated tau value, and set a switching period Ts1 including at least the saturation times of the first voltage V1 and the second voltage V2. In FIG 5, a case where the initial switching period Ts1 of the insulation resistance measurement circuit 100 is 10 seconds is illustrated as an example.

[0098] As shown in Fig. 5, the first voltage V1 may saturate after a certain time in the initial switching period Ts1. However, since the on-period of the first switch SW1 according to the switching period Ts1 has not yet elapsed even after the first voltage V1 saturates, the first voltage V1 may be maintained as the saturation voltage Vth1 during the remaining on-period of the first switching signal S1 from the time when the first voltage V1 reaches the voltage value of the saturation voltage Vth1 to the time when the on-period of the first switching signal S1 has elapsed. In this case, the controller 170 may reduce the on-period of the first switch SW1, thereby reducing the switching period Ts1. For example, the controller 170 may set the on-period of the first switch SW1 to the time (3 seconds) that it took for the first voltage V1 to saturate in the previous switching period Ts1.

[0099] Similarly, in the initial switching period Ts1, the second voltage V2 may saturate after a certain time has elapsed. However, since the on-period of the second switch SW2 according to the switching period Ts1 has not yet elapsed even after the second voltage V2 has saturated, the second voltage V1 may be maintained as the saturation voltage Vth2 during the remaining on-period of the second switching signal S2 from the time when the second voltage V2 reaches the voltage value of the saturation voltage Vth2 to the time when the on-period of the second switching signal S2 has completely elapsed. In this case, the controller 170 may reduce the on-period of the second switch SW2, thereby reducing the switching period Ts1. For example, the controller 170 may set the on-period of the second switch SW2 to the time (3 seconds) it took for the second voltage V2 to saturate in the previous switching period Ts1.

[0100] 5, the first voltage V1 is saturated and reaches the saturation voltages Vth1 and Vth2 when 3 seconds have elapsed since the first switching signal S1 was turned on, and the second voltage V2 is saturated and reaches the saturation voltages Vth1 and Vth2 when 3 seconds have elapsed since the second switching signal S2 was turned on. This allows the controller 170 to set a new switching period Tf1 to 6 seconds.

[0101] After that, the switching driver 160 can control the first switch SW1 and the second switch SW2 in the new switching period Tf1. Therefore, the period during which the first voltage V1 and the second voltage V2 are saturated can be reduced compared to the saturation period in the case of control in the initial switching period Ts1.

[0102] When the first switch SW1 and the second switch SW2 are controlled with the new switching period Tf1, the time taken to measure the insulation resistance can be reduced.

[0103] 5, an abnormal voltage event VP may occur at a predetermined time t0 while the voltage measurement unit 150 is measuring the first voltage V1. When the controller 170 determines that an abnormal voltage event VP has occurred, the controller 170 may control the first switch SW1 and the second switch SW2 to be both turned off. The controller 170 may also reset the switching period Tf2 to the initial switching period Ts2.

[0104] There may be a delay in the controller 170 confirming the abnormal voltage event VP, changing the state of the first switch SW1 and the second switch SW2 to the off state, and setting a new switching period Ts2. Therefore, the first switch SW1 and the second switch SW2 should be able to be controlled with the new switching period Ts2 from time t1. However, the time between t0 and t1 is merely a normal radio wave delay, and is not a time interval that significantly affects the measurement of the insulation resistance.

[0105] Therefore, to obtain a valid voltage value of the first voltage V1, it is necessary to wait 5 seconds + a(t0-t1) seconds until the next ON period of the first switch SW1 ends, which is a significantly reduced wait time compared to the wait time required in conventional insulation resistance measurements.

[0106] The controller 170 can then control the first switch SW1 and the second switch SW2 with a new switching period Ts2 and calculate a new insulation resistance value.

[0107] If the on-period of the first switch SW1 according to the switching period Ts2 has not elapsed even after the first voltage V1 is saturated while the controller 170 is operating in a new switching period Ts2, or if the on-period of the second switch SW2 according to the switching period Ts2 has not elapsed even after the second voltage V2 is saturated, the controller 170 can reduce the on-periods of the first switch SW1 and the second switch SW2 to reduce the switching period Ts2.

[0108] However, there may be a case where the first voltage V1 and the second voltage V2 do not reach a saturated state even though the controller 170 controls the first switch SW1 and the second switch SW2 with a new switching period Ts2. In this case, the controller 170 can determine that a problem has occurred in the insulation resistance, and can terminate all operations of the first switch SW1 and the second switch SW2.

[0109] According to one embodiment of the present invention, the switching period for the insulation resistance calculation can be determined.

[0110] According to an embodiment of the present invention, it is possible to accurately determine the time when insulation resistance breakdown occurs, and to guarantee the validity of the insulation resistance value by excluding the voltage value for the switching section where the insulation resistance measurement is problematic.

[0111] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by a person having ordinary skill in the field to which the present invention belongs also fall within the scope of the present invention.

Claims

1. In an insulation resistance measurement device for measuring insulation resistance between a battery including a plurality of battery cells and ground, a first voltage distribution unit that distributes a voltage between the positive electrode of the battery and ground; a second voltage distribution unit that distributes a voltage between the negative electrode of the battery and ground; a first switch SW1 connecting the positive electrode of the battery and the first voltage dividing unit; a second switch SW2 connecting the negative electrode of the battery and the second voltage dividing unit; When a first voltage, which is an output of the first voltage dividing unit, is saturated during an on-period of the first switch SW1, or a second voltage, which is an output of the second voltage dividing unit, is saturated during an on-period of the second switch SW2, a current switching period of the first switch SW1 and the second switch SW2 is reduced from a previous switching period.

2. 2. The insulation resistance measuring device according to claim 1, further comprising: a switch ON period that is adjusted based on a point in time at which the first voltage or the second voltage is saturated.

3. When a period in which the first voltage or the second voltage decreases occurs during an on-period of the first switch SW1 or the second switch SW2, 3. The insulation resistance measuring device according to claim 1, further comprising: a step of resetting the current switching period to a predetermined initial switching period.

4. a first insulation resistor between the positive terminal of the battery and ground; and a second insulation resistor between the negative terminal of the battery and ground; 3. The insulation resistance measuring device according to claim 1, wherein a control unit calculates values ​​of the first insulation resistance and the second insulation resistance based on the first voltage and the second voltage.

5. 4. The insulation resistance measuring device according to claim 3, wherein the initial switching period is set based on a capacitance of a Y capacitor connected in parallel between the battery and an external device.

6. a battery including a plurality of battery cells; and An insulation resistance measuring device for measuring an insulation resistance between the battery and ground, the insulation resistance measuring device comprising: a first voltage distribution unit that distributes a voltage between the positive electrode of the battery and ground; a second voltage distribution unit that distributes a voltage between the negative electrode of the battery and ground; a first switch SW1 connecting the positive electrode of the battery and the first voltage dividing unit; a second switch SW2 connecting the negative electrode of the battery and the second voltage dividing unit; When a first voltage, which is an output of the first voltage dividing unit, is saturated during an on-period of the first switch SW1, or a second voltage, which is an output of the second voltage dividing unit, is saturated during an on-period of the second switch SW2, a current switching period of the first switch and the second switch is reduced from a previous switching period.

7. The battery system of claim 6 , further comprising: adjusting an on-period of a switch based on a point at which the first voltage or the second voltage saturates.

8. When a period in which the first voltage or the second voltage decreases occurs during an on-period of the first switch SW1 or the second switch SW2, 8. The battery system of claim 6 or 7, further comprising resetting the current switching period to a predetermined initial switching period.

9. a first insulation resistor between the positive terminal of the battery and ground; and a second insulation resistor between the negative terminal of the battery and ground; The battery system according to claim 6 or 7, wherein a control unit calculates values ​​of the first insulation resistance and the second insulation resistance based on the first voltage and the second voltage.

10. The battery system according to claim 8 , wherein the initial switching period is set based on a capacitance of a Y capacitor connected in parallel between the battery and an external device.

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