Insulation diagnostic circuit and battery system including the same

Abstract

An insulation diagnosis circuit for diagnosing an insulation state of a battery pack may include a first resistor and a second resistor connected in series between a positive electrode of the battery pack and a first node, a first switch connected between a second node where the first resistor and the second resistor are connected to each other and a negative electrode of the battery pack, a third resistor connected between the first node and a third node, and a fourth resistor connected in series between the third node and the negative electrode of the battery pack.

Description

[Technical Field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0117682, filed September 5, 2023, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present disclosure relates to an isolation diagnostic circuit and a battery system including the same. [Background technology]

[0003] Battery insulation resistance is an important safety requirement for batteries. To ensure battery safety, vehicles and light electric vehicles equipped with batteries can instruct the Battery Management System (BMS) installed in the battery to measure and diagnose the insulation resistance. When measuring insulation resistance, the BMS uses expensive components such as photomos relays. There is a need to reduce the cost of incorporating a component for measuring battery insulation resistance into the BMS. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an insulation diagnosis circuit that can reduce the cost required to realize a circuit for measuring the insulation resistance of a battery, and a battery system including the same. [Means for solving the problem]

[0005] According to one aspect of the invention, an insulation diagnosis circuit for diagnosing an insulation state of a battery pack includes a first resistor and a second resistor connected in series between a positive electrode of the battery pack and a first node, a first switch connected between a second node where the first resistor and the second resistor are connected to each other and a negative electrode of the battery pack, a third resistor connected between the first node and a third node, and a fourth resistor connected in series between the third node and the negative electrode of the battery pack.

[0006] The first node may be coupled to ground.

[0007] The insulation diagnostic circuit may further include a second switch connected between the first node and ground and a third switch connected between the third node and one end of the fourth resistor.

[0008] When the second switch and the third switch are in an on state and the first switch is in an off state, the first resistor and the second resistor are connected in series between the positive electrode of the battery pack and the ground, and the third resistor and the fourth resistor are connected in series between the negative electrode of the battery pack and the ground, thereby forming a first insulation resistor between the ground and the positive electrode of the battery pack and a second insulation resistor between the ground and the negative electrode of the battery pack.

[0009] When the first switch to the third switch are in an on state, the second resistor is connected between the ground and the negative electrode of the battery pack, and the third resistor and the fourth resistor are connected between the ground and the negative electrode of the battery pack, so that a first insulation resistor between the ground and the positive electrode of the battery pack and a second insulation resistor between the ground and the negative electrode of the battery pack can be formed.

[0010] The second switch may be implemented as a photoMOS relay, and the first switch and the third switch may be implemented as FETs.

[0011] According to another aspect of the present invention, a battery system may include a battery pack including a plurality of battery cells, an insulation diagnostic circuit for diagnosing an insulation state of the battery pack, and a cell monitoring IC for diagnosing an insulation state of the battery pack using an insulation sensing voltage provided by the insulation diagnostic circuit. The insulation diagnostic circuit may include a first resistor and a second resistor connected in series between a positive electrode of the battery pack and a first node, a first switch connected between a second node where the first resistor and the second resistor are connected and the negative electrode of the battery pack, a third resistor connected between the first node and a third node, and a fourth resistor connected in series between the third node and the negative electrode of the battery pack.

[0012] The first node may be coupled to ground.

[0013] The insulation diagnostic circuit may further include a second switch connected between the first node and ground and a third switch connected between the third node and one end of the fourth resistor.

[0014] The cell monitoring IC can calculate a positive electrode insulation resistance between the positive electrode of the battery pack and the ground and a negative electrode insulation resistance between the negative electrode of the battery pack and the ground using a first insulation sensing voltage, which is the voltage of the third node when the first switch is in an off state, and a second insulation sensing voltage, which is the voltage of the third node when the first switch is in an on state.

[0015] The first insulation sensing voltage may be a voltage obtained by resistance-dividing the ground voltage by the third resistor and the fourth resistor, and the ground voltage may be a voltage obtained by resistance-dividing the battery pack voltage by the first insulation resistor and the second insulation resistor. The first insulation resistor may be a parallel sum of the third resistor, the fourth resistor, and the negative insulation resistor connected in series, and the second insulation resistor may be a parallel sum of the first resistor, the second resistor, and the positive insulation resistor connected in series.

[0016] The second insulation sensing voltage may be a voltage obtained by dividing the ground voltage by the third resistor and the fourth resistor, and the ground voltage may be a voltage obtained by dividing the battery pack voltage by the first insulation resistor and the second insulation resistor. The first insulation resistor may be a parallel sum of the third resistor, the fourth resistor, the second resistor, and the negative insulation resistor, which are connected in series, and the second insulation resistor may be the positive insulation resistor.

[0017] The cell monitoring IC can diagnose the insulation state of the battery pack by using a first insulation sensing voltage, which is the voltage of the third node when the first switch is in an off state, and a second insulation sensing voltage, which is the voltage of the third node when the first switch is in an on state.

[0018] When the first insulation detection voltage is equal to or lower than a predetermined first reference voltage and equal to or higher than a predetermined second reference voltage, and the second insulation detection voltage is equal to or higher than a predetermined third reference voltage, the cell monitoring IC can determine that the insulation between the positive electrode of the battery pack and the ground and the insulation between the negative electrode of the battery pack and the ground are both in an abnormal state.

[0019] When the first insulation detection voltage is equal to or less than a predetermined first reference voltage and equal to or greater than a predetermined second reference voltage, and the second insulation detection voltage is less than a predetermined third reference voltage, the cell monitoring IC can determine that the insulation between the positive electrode of the battery pack and the ground and the insulation between the negative electrode of the battery pack and the ground are all normal.

[0020] When the first insulation sensing voltage is equal to or less than a predetermined first reference voltage and less than a predetermined second reference voltage, the cell monitoring IC can determine that the insulation between the positive electrode of the battery pack and the ground is normal and that the insulation between the negative electrode of the battery pack and the ground is abnormal.

[0021] When the first insulation detection voltage exceeds a predetermined first reference voltage, the cell monitoring IC can determine that the insulation between the negative electrode of the battery pack and the ground is normal and that the insulation between the positive electrode of the battery pack and the ground is abnormal.

[0022] The cell monitoring IC generates a second switching control signal and a third switching control signal that are at an on level to turn on the second switch and the third switch for a first period, and a first switching control signal that is at an on level to turn on the first switch for a second period, the first period and the second period overlap, and the first period may be longer than the second period.

[0023] The cell monitoring IC may generate a second switching control signal and a third switching control signal that are on levels to turn on the second switch and the third switch during a first period and a second period, and may generate a first switching control signal that is on level to turn on the first switch during the second period. [Effects of the Invention]

[0024] To provide an insulation diagnosis circuit capable of reducing the cost required to realize a circuit for measuring the insulation resistance of a battery, and a battery system including the same. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram illustrating a battery system according to an embodiment. [Figure 2] 1 is a circuit diagram showing a partial configuration of a battery system according to an embodiment. [Figure 3] FIG. 2 is a circuit diagram showing multiple switches in an insulation diagnostic circuit according to one embodiment. [Figure 4] FIG. 3 is a waveform diagram illustrating signals controlling the switching of a plurality of switches according to one embodiment. [Figure 5] FIG. 10 is a circuit diagram showing an equivalent circuit of the insulation diagnosis circuit during a period TP1. [Figure 6] FIG. 10 is a circuit diagram showing an equivalent circuit of the insulation diagnosis circuit during a period TP2. [Figure 7] 1 is a flowchart illustrating a method for determining an insulation state according to an embodiment. [Figure 8] FIG. 10 is a waveform diagram showing signals for controlling the switching of a plurality of switches according to another embodiment. [Figure 9] FIG. 10 is a waveform diagram showing signals for controlling the switching of a plurality of switches according to another embodiment. [Figure 10] 10 is a diagram showing an insulation diagnosis circuit according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] In describing the embodiments disclosed herein, if a detailed description of related publicly known technologies is deemed to detract from the gist of the embodiments disclosed herein, the detailed description will be omitted. In addition, the attached drawings are provided to facilitate understanding of the embodiments disclosed herein, and the technical ideas disclosed herein should not be limited by the attached drawings, and should be understood to include all modifications, equivalents, or alternatives within the spirit and technical scope of the present invention.

[0027] Terms including ordinal numbers such as first, second, etc. may be used to describe various components, but the components are not limited by the terms. These terms are used only to distinguish one component from another.

[0028] When a component is described as being "coupled" or "connected" to another component, it should be understood that the component is or may be directly connected to the other component, but that there may be other components in between. On the other hand, when a component is described as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0029] In this application, terms such as "comprise" or "have" are to be understood as specifying the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but without precluding the possible presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0030] FIG. 1 is a diagram showing a battery system according to an embodiment.

[0031] The battery system 1 may include a battery pack 10, a battery management system (BMS) 20, a first relay 30, a second relay 35, a current sensor 40, and an insulation diagnostic circuit 100. The battery pack 10 includes a plurality of battery cells (CE1 to CEn) connected in series. When the first relay 30 is closed, the positive electrode (P+) of the battery pack 10 may be electrically connected to the external connection terminal (OT+) of the battery system 1. When the second relay 35 is closed, the negative electrode (P-) of the battery pack 10 may be electrically connected to the external connection terminal (OT-) of the battery system 1.

[0032] The current sensor 40 senses the current flowing through the battery pack 10 (hereinafter, battery current), and the current sensor 40 may transmit a signal (IS) to the BMS 20 indicating the sensed current.

[0033] The BMS 20 may include a cell monitoring IC 21, a main control unit (MCU) 22, and an insulation diagnosis circuit 100. The cell monitoring IC 21 is connected to a plurality of battery cells (CE1 to CEn) and can measure a plurality of cell voltages of the plurality of battery cells (CE1 to CEn) and a voltage across the battery pack 10 (hereinafter referred to as battery voltage). The cell monitoring IC 21 can generate a signal indicating the measured cell voltages and battery voltage and provide the signal to the MCU 22.

[0034] The cell monitoring IC 21 can control the insulation diagnosis circuit 100 to collect the measured voltages required to calculate the insulation resistance of the battery pack 10. The cell monitoring IC 21 can control the operation of the insulation diagnosis circuit 100 to collect the measured voltages. The cell monitoring IC 21 can determine the insulation state of the battery pack 10 based on the measured voltages. The cell monitoring IC 21 can calculate the insulation resistance of the battery pack 10 based on the measured voltages and determine the insulation state of the battery pack 10.

[0035] The MCU 22 can collect information on a plurality of battery cell voltages, battery voltages, battery currents, and the temperature of the battery pack 10, and can control the charge / discharge current of the battery pack 10 and control the cell balancing operation for the plurality of battery cells (CE1 to CEn) based on the collected cell voltages, battery currents, etc. The MCU 22 can control the opening and closing of the first relay 30 and the second relay 35 to control the charge / discharge of the battery pack 10. The MCU 22 can generate relay control signals for controlling the opening and closing of the first relay 30 and the second relay 35 and provide them to the first relay 30 and the second relay 35. The MCU 22 receives an insulation status of the battery pack 10 from the cell monitoring IC 21, and can stop the operation of the battery pack 10 or send a signal to an external device via wired or wireless communication if there is an insulation abnormality between the positive electrode (P+) and / or the negative electrode (P-) of the battery pack 10 and the ground.

[0036] FIG. 2 is a circuit diagram showing a partial configuration of a battery system according to an embodiment.

[0037] FIG. 2 specifically illustrates the battery pack 10, the first relay 30, the second relay 35, and the insulation diagnosis circuit 100. For ease of explanation, some components illustrated in FIG. 1 may be omitted in FIG. 2. In FIG. 2, an external device 5 is connected between the external connection terminals (OT+) and (OT-) of the battery system 1. This is an application example for explaining the battery system 1 and does not limit the invention. The external device 5 illustrated in FIG. 2 may be a vehicle. The external device 5 may include two Y capacitors (YC3, YC4) connected in series between the external connection terminals (OT+) and (OT-), a power converter 51, and an electrical load 52. The power converter 51 may be an inverter, and the electrical load 52 may be a motor. An X capacitor (XC) may be connected between the external connection terminals (OT+) and (OT-).

[0038] The first relay 30 includes a main relay 31, a pre-charge relay 32, and a pre-charge resistor 33. The main relay 31 is connected between the positive terminal (P+) and the external connection terminal (OT+), and the pre-charge relay 32 and pre-charge resistor 33 are connected in series between the positive terminal (P+) and the external connection terminal (OT+). The series-connected pre-charge relay 32 and pre-charge resistor 33, and the main relay 31, are connected in parallel between the positive terminal (P+) and the external connection terminal (OT+). The main relay 31 is closed by an on-level relay control signal (RC1) and can be opened by an off-level relay control signal (RC1). The pre-charge relay 32 is closed by an on-level relay control signal (RC3) and can be opened by an off-level relay control signal (RC3). The second relay 35 is connected between the negative terminal (P-) and the external connection terminal (OT-) and can be closed by an on-level relay control signal (RC2) and can be opened by an off-level relay control signal (RC2). After the second relay 35 and the pre-charge relay 32 are closed, the main relay 31 is closed, and after the main relay 31 is closed, the pre-charge relay 32 can be opened.

[0039] The Y capacitor (YC1) is connected between the positive electrode (P+) and ground, and the Y capacitor (YC2) is connected between the negative electrode (P-) and ground. The insulation resistance (RL1) indicates the insulation between the positive electrode (P+) of the battery pack 10 and ground, and the insulation resistance (RL2) indicates the insulation between the negative electrode (P-) of the battery pack 10 and ground. The insulation resistance (RL3) indicates the insulation between the wiring between the positive electrode (P+) of the battery pack 10 and the external connection terminal (OT+) and ground, and the insulation resistance (RL4) indicates the insulation between the wiring between the negative electrode (P-) of the battery pack 10 and the external connection terminal (OT-) and ground.

[0040] When an insulation diagnosis is performed, if the first relay 30 is closed, the parallel sum of the insulation resistance (RL1) and the insulation resistance (RL3) may indicate the insulation between the positive electrode of the battery pack 10 and the ground. When an insulation diagnosis is performed, if the second relay 35 is closed, the parallel sum of the insulation resistance (RL2) and the insulation resistance (RL4) may indicate the insulation between the negative electrode of the battery pack 10 and the ground. In contrast, when an insulation diagnosis is performed, if the first relay 30 is open, the insulation resistance (RL1) may indicate the insulation between the positive electrode of the battery pack 10 and the ground. When an insulation diagnosis is performed, if the second relay 35 is open, the insulation resistance (RL2) may indicate the insulation between the negative electrode of the battery pack 10 and the ground.

[0041] Hereinafter, the resistance indicating the insulation between the positive electrode of the battery pack 10 and the ground will be referred to as the positive electrode insulation resistance, and the resistance indicating the insulation between the negative electrode of the battery pack 10 and the ground will be referred to as the negative electrode insulation resistance.

[0042] When the positive electrode insulation resistance is lower than a predetermined threshold, it can be determined that the insulation between the positive electrode (P+) and ground has broken down. When the negative electrode insulation resistance is lower than a predetermined threshold, it can be determined that the insulation between the negative electrode (P-) and ground has broken down. The battery pack 10 must be electrically isolated from the external device 5. If the battery pack 10 is not isolated from the ground, the external device 5 and the battery pack 10 are connected via the ground, which may result in a breakdown of the insulation between the battery pack 10 and the external device 5. According to one embodiment, the BMS 20 calculates the positive electrode insulation resistance and the negative electrode insulation resistance via the insulation diagnosis circuit 100, compares the calculated values ​​with thresholds, and determines the insulation state between the battery pack 10 and ground based on the comparison result. Alternatively, the BMS 20 can determine the insulation state of the positive and negative electrodes of the battery pack 10 using the voltage sensed via the insulation diagnosis circuit 100. The "insulation state" can include a normal insulation state in which the insulation resistance between the two components is equal to or higher than a predetermined threshold, and an abnormal insulation state in which the insulation resistance is lower than the threshold.

[0043] The insulation diagnostic circuit 100 is connected to the positive terminal (P+), negative terminal (P-), and ground of the battery pack 10. The insulation diagnostic circuit 100 includes three switches (SW2, SW1, SW3) and four resistors (R1-R4).

[0044] The switch (SW2), resistor (R1), and resistor (R2) are connected between the positive terminal (P+) of the battery pack 10 and ground, and the switch (SW3), resistor (R3), and resistor (R4) are connected between the negative terminal of the battery pack 10 and the contact 102.

[0045] One end of resistor R1 is connected to the positive terminal (P+) of the battery pack 10, and the other end of resistor R1 and one end of resistor R2 are connected at contact 103. The other end of resistor R2 and one end of switch SW2 are connected at contact 102, and the other end of switch SW2 is connected to ground. One end of resistor R3 is connected at contact 102, and the other end of resistor R3 and one end of switch SW3 are connected at contact 101. The other end of switch SW3 is connected to one end of resistor R4, and the other end of resistor R4 is connected to the negative terminal (P-) of the battery pack 10. Switch SW1 is connected between contact 103 and the negative terminal (P-). The voltage at contact 101 (insulation sense voltage, ISV) can be provided to the cell monitoring IC 21. The cell monitoring IC 21 includes an analog-to-digital converter (ADC). The battery pack 10 may include an ADC (Analog to Digital Converter) 211 and insulation diagnostic logic 212. The ADC 211 may convert the insulation sense voltage (ISV) into a digital value and provide it to the insulation diagnostic logic 212. The insulation diagnostic logic 212 may use the digital value to calculate the positive electrode insulation resistance between the positive electrode (P+) of the battery pack 10 and ground, and the negative electrode insulation resistance between the negative electrode (P-) of the battery pack 10 and ground. The insulation diagnostic logic 212 may compare the positive electrode insulation resistance and the negative electrode insulation resistance with threshold values, and may determine 1) a normal insulation state, 2) a negative electrode insulation state, 3) a positive electrode insulation state, or 4) an abnormal insulation state depending on the comparison result.

[0046] 1) Normal insulation state means that both the positive and negative electrodes of the battery pack are insulated from the ground. 2) Negative electrode insulation state means that the negative electrode of the battery pack is insulated from the ground and the positive electrode of the battery pack is in an abnormal insulation state from the ground. 3) Positive electrode insulation state means that the positive electrode of the battery pack is insulated from the ground and the negative electrode of the battery pack is in an abnormal insulation state from the ground. 4) Insulation abnormal state means that both the positive and negative electrodes of the battery pack are in an abnormal insulation state from the ground. In the normal insulation state, the resistance values ​​of the positive electrode insulation resistance and the negative electrode insulation resistance are all above the threshold. In the negative electrode insulation state, the negative electrode insulation resistance is above the threshold and the positive electrode insulation resistance is below the threshold. In the positive electrode insulation state, the positive electrode insulation resistance is above the threshold and the negative electrode insulation resistance is below the threshold. In the insulation abnormal state, the resistance values ​​of the positive electrode insulation resistance and the negative electrode insulation resistance are all below the threshold.

[0047] The cell monitoring IC 21 can generate multiple switching control signals (SS2 to SS3) that control the switching operations of the multiple switches (SW2 to SW3). The cell monitoring IC 21 can supply the multiple switching control signals (SS2 to SS3) to the insulation diagnosis circuit 100 for insulation diagnosis. The multiple switches (SW2 to SW3) can be turned on or off by the multiple switching control signals (SS2 to SS3). For example, the on level of the multiple switching control signals (SS2 to SS3) may be high level, and the off level may be low level.

[0048] When the switching control signal (SS2) is at a high level, the switch (SW2) is turned on, when the switching control signal (SS2) is at a low level, the switch (SW2) is turned off, when the switching control signal (SS1) is at a high level, the switch (SW1) is turned on, when the switching control signal (SS1) is at a low level, the switch (SW1) is turned off, when the switching control signal (SS3) is at a high level, the switch (SW3) is turned on, and when the switching control signal (SS3) is at a low level, the switch (SW3) is turned off.

[0049] FIG. 3 is a circuit diagram illustrating multiple switches in an insulation diagnostic circuit according to one embodiment.

[0050] 3, switch SW2 may be implemented as a photoMOS relay, and switches SW1 and SW3 may be implemented as FETs. Switch SW2 operates in the high voltage range, and the switching control signal SS2 is generated in the low voltage range, so it is implemented as a photoMOS relay. Switches SW1 and SW3 are connected to the negative pole (P-) of battery pack 10 and can be switched by the switching control signals SS1 and SS3 at low voltage levels.

[0051] The switch (SW2) may include two MOSFETs 111 and 112 connected in series, a diode 113, and a switching element 114. The switching element 114 is turned on by a switching control signal (SS2) of a high level (on level) and turned off by a switching signal (SS2) of a low level (off level). The power supply voltage (VD) is supplied to the anode of the diode 113, and the cathode of the diode 113 is connected to one end of the switching element 114, with the other end of the switching element 114 being connected to ground. The ground connected to the other end of the switching element 114 may be a low-voltage ground different from the ground for the battery pack 10. The drain of the MOSFET 111 may be connected to the contact 102, the source of the MOSFET 111 may be connected to the source of the MOSFET 112, and the drain of the MOSFET 112 may be connected to ground. When the switching element 114 is turned on, a current flows through the diode 113, and the MOSFETs 111 and 112 may be turned on by the light emitted by the diode 113. When the switching element 114 is in the off state, no current flows through the diode 113, and the MOSFETs 111 and 112 are in the off state.

[0052] The switch SW1 is implemented as an n-channel FET, and the drain of the switch SW1 is connected to the contact 103, the source of the switch SW1 is connected to the negative electrode (P-) of the battery pack 10, and a switching control signal SS1 can be supplied to the gate of the switch SW1. The switch SW1 can be turned on by the switching control signal SS1 at a high level, which is an on level, and can be turned off by the switching control signal SS1 at a low level, which is an off level.

[0053] The switch SW3 is implemented as an n-channel FET, and the drain of the switch SW3 is connected to the contact 101, the source of the switch SW3 is connected to one end of the resistor R4, and the gate of the switch SW3 is supplied with a switching control signal SS3. The switch SW3 can be turned on by the switching control signal SS3 at a high level, which is an on level, and can be turned off by the switching control signal SS3 at a low level, which is an off level.

[0054] Hereinafter, a method for measuring an insulation sense voltage (ISV) according to the switching operations of the switches SW2-SW3 will be described with reference to FIG.

[0055] FIG. 4 is a waveform diagram illustrating signals that control the switching of a plurality of switches according to one embodiment.

[0056] The period TU1 in FIG. 4 may be a unit period for insulation diagnosis. The period TU1 shown in FIG. 4 may be repeated to repeat the insulation diagnosis. When the period TU1 is repeated, there may be a predetermined time interval between two adjacent periods TU1. The MCU 22 calculates the insulation resistance in each of the repeated insulation diagnoses and can determine the insulation state of the battery pack 10 based on the calculated insulation resistance value.

[0057] 4, the period TU1 includes a period TP1 and a period TP2. In the period TP1, the switching control signals (SS2) and (SS3) are at a high level, i.e., an on level, and the switching control signal (SS1) is at a low level, i.e., an off level.

[0058] FIG. 5 is a circuit diagram showing an equivalent circuit of the insulation diagnosis circuit during the period TP1.

[0059] As shown in FIG. 5, the battery pack 10 is shown as a voltage source (VP). Two resistors (R1, R2) may be connected in series between the positive terminal of the voltage source (VP) and ground, and two resistors (R3, R4) may be connected in series between ground and the negative terminal of the voltage source (VP). A positive isolation resistor (RLP) may be connected between the positive terminal of the voltage source (VP) and ground, and a negative isolation resistor (RLN) may be connected in series between ground and the negative terminal of the voltage source (VP). The positive isolation resistor (RLP) may be the parallel sum (RL1∥RL3) of the isolation resistors (RL1) and (RL3). The negative isolation resistor (RLN) may be the parallel sum (RL2∥RL4) of the isolation resistors (RL2) and (RL4). Alternatively, the positive isolation resistor (RLP) may be the isolation resistor (RL1), and the negative isolation resistor (RLN) may be the isolation resistor (RL2).

[0060] 4 can indicate any point in time during the period TP1. The ADC 211 can convert the insulation sensing voltage (ISV) at the time T1 into a digital signal. The insulation sensing voltage (ISV) at the time T1 can be defined as follows:

[0061] [Formula 1] ISV=VG1*R4 / (R3+R4)

[0062] In Equation 1, "VG1" is the ground voltage at time T1, "R3" is the resistance value of resistor (R3), and "R4" is the resistance value of resistor (R4).

[0063] The ground voltage (VG1) can be defined as in Equation 2.

[0064] [Formula 2] VG1=VP*Rn1 / (Rp1+Rn1)

[0065] In Equation 2, "VP" is the voltage of the voltage source (VP), "Rn1" is the negative resistance seen from the ground at time T1, and "Rp2" is the positive resistance seen from the ground at time T1. The negative resistance (Rn1) is the parallel sum of the two series-connected resistors (R3, R4) and the negative insulation resistor (RLN) ((R3+R4∥RLN)). The positive resistance (Rp1) is the parallel sum of the two series-connected resistors (R1, R2) and the positive insulation resistor (RLP) ((R1+R2)∥RLP).

[0066] In the period TP2, the switching control signal (SS2), the switching control signal (SS1), and the switching control signal (SS3) are at a high level, ie, an on level.

[0067] FIG. 6 is a circuit diagram showing an equivalent circuit of the insulation diagnosis circuit during the period TP2.

[0068] 6, a resistor (R1) is connected between both ends of a voltage source (VP) corresponding to the battery pack 10, and the resistor (R1) is connected between the negative terminal of the voltage source (VP) and ground. Two resistors (R3, R4) may be connected in series between ground and the negative terminal of the voltage source (VP). A positive electrode insulation resistor (RLP) may be connected between the positive terminal of the voltage source (VP) and ground, and a negative electrode insulation resistor (RLN) may be connected in series between ground and the negative terminal of the voltage source (VP).

[0069] 4 can indicate any point in time during the period TP2. The ADC 211 can convert the insulation sensing voltage (ISV) at time T2 into a digital signal. The insulation sensing voltage (ISV) at time T2 can be defined as follows:

[0070] [Formula 3] ISV=VG2*R4 / (R3+R4)

[0071] In Equation 3, "VG2" is the ground voltage at time T2, "R3" is the resistance value of resistor (R3), and "R4" is the resistance value of resistor (R4).

[0072] The ground voltage (VG2) can be defined as in Equation 4.

[0073] [Formula 4] VG2=VP*Rn2 / (Rp2+R2n)

[0074] In Equation 4, "VP" is the voltage of the voltage source (VP), "Rn2" is the negative resistance seen from ground at time T2, and "Rp2" is the positive resistance seen from ground at time T2. The negative resistance (Rn2) is the parallel sum of the two series-connected resistors (R3, R4), resistor (R2), and the negative insulation resistor (RLN) ((R3+R4)∥R2∥RLN). The positive resistance (Rp2) is the value of the positive insulation resistor (RLP).

[0075] The insulation diagnosis logic 212 knows the two values ​​of the insulation sensing voltage (ISV) obtained from time points T1 and T2, the resistance values ​​of the four resistors (R1-R4), and the voltage value of the battery pack 10, and can therefore calculate the resistance values ​​of the positive electrode insulation resistor (RLP) and the negative electrode insulation resistor (RLN) using Equations 1 to 4.

[0076] The insulation diagnosis logic 212 compares the resistance values ​​of the positive electrode insulation resistance (RLP) and the negative electrode insulation resistance (RLN) with a predetermined threshold and can determine that there is an abnormality in the insulation between the pole of the battery pack 10 corresponding to an insulation resistance smaller than the threshold and ground. For example, if the resistance value of the positive electrode insulation resistance (RLP) is less than the threshold and the resistance value of the negative electrode insulation resistance (RLN) is equal to or greater than the threshold, the insulation diagnosis logic 212 can determine that the battery pack 10 is in a negative electrode insulation state. If the resistance value of the negative electrode insulation resistance (RLN) is less than the threshold and the resistance value of the positive electrode insulation resistance (RLP) is equal to or greater than the threshold, the insulation diagnosis logic 212 can determine that the battery pack 10 is in a positive electrode insulation state. If the resistance values ​​of both the positive electrode insulation resistance (RLP) and the negative electrode insulation resistance (RLN) are less than the threshold, the insulation diagnosis logic 212 can determine that the battery pack 10 is in an insulation abnormality state. If the resistance values ​​of both the positive electrode insulation resistance (RLP) and the negative electrode insulation resistance (RLN) are equal to or greater than the threshold value, the insulation diagnosis logic 212 can determine that the battery pack 10 is in a normal insulation state.

[0077] In the above embodiment, the insulation diagnosis is performed through calculation of the positive and negative insulation resistance values, but the invention is not limited to this. The insulation diagnosis logic 212 can determine the insulation state based on the insulation sense voltage (ISV) values ​​acquired at time points T1 and T2.

[0078] For example, assume that the voltage of the battery pack 10 is 800V, R1=2.8MΩ, R2=2.8MΩ, R3=5.6MΩ, and R4=30KΩ, and that RL1 to RL4 are 10MΩ when in a normal insulation state and 100KΩ when in an abnormal insulation state.

[0079] 1) When the battery pack 10 is in a normal insulation state, the insulation sensing voltage (ISV) measured at time T1 may be 2.13 V, and the insulation sensing voltage (ISV) measured at time T2 may be 0.91 V. Specifically, in the normal insulation state, the positive electrode resistance (Rp1) at time T1 is (2.8 + 2.8) || (10 || 10) [MΩ], or 2.64 MΩ, and the negative electrode resistance (Rn1) is (5.6 + 0.03) || (10 || 10) [MΩ], or 2.65 MΩ. Therefore, VG1 at time T1 is approximately 400 V, and ISV is 400 * (30 / 5630), or 2.13 V. Under normal insulation conditions, the negative resistance (Rn2) at time T2 is (5.6 + 0.03)∥2.8∥(10∥10) [MΩ]. If we ignore the "0.03" for ease of calculation, the value is 1.36MΩ, and the positive resistance (Rp2) is (10∥10) [MΩ], or 5MΩ. Therefore, at time T2, VG1 is approximately 171V, and ISV is 171*(30 / 5630), or 0.91V.

[0080] 2) When the battery pack 10 is in a negative electrode insulation state, the insulation sensing voltage (ISV) measured at time T1 may be 4.2 V, and the insulation sensing voltage (ISV) measured at time T2 may be 4.11 V. Specifically, in the negative electrode insulation state, the positive electrode resistance (Rp1) at time T1 is (2.8 + 2.8) || (0.1 || 0.1) [MΩ], or approximately 0.05 MΩ, and the negative electrode resistance (Rn1) is (5.6 + 0.03) || (10 || 10) [MΩ], or 2.65 MΩ. Then, VG1 at time T1 is approximately 785 V, and ISV is 785 * (30 / 5630), or 4.2 V. In the negative pole insulation state, the negative pole resistance (Rn2) at time T2 is (5.6 + 0.03)∥2.8∥(10∥10) [MΩ]. If we ignore the "0.03" for ease of calculation, the value is 1.36 MΩ, and the positive pole resistance (Rp2) is (0.1∥0.1) [MΩ], or 0.05 MΩ. Therefore, at time T2, VG1 is approximately 772 V, and ISV is 171 * (30 / 5630) = 4.11 V.

[0081] 3) In the case of a positive electrode insulation state of the battery pack 10, the insulation sensing voltage (ISV) measured at time T1 may be 0.08 V, and the insulation sensing voltage (ISV) measured at time T2 may be 0.04 V. Specifically, in the positive electrode insulation state, the positive electrode resistance (Rp1) at time T1 is (2.8 + 2.8) || (10 || 10) [MΩ], or 2.64 MΩ, and the negative electrode resistance (Rn1) is (5.6 + 0.03) || (0.1 || 0.1) [MΩ], or approximately 0.05 MΩ. Then, VG1 at time T1 is approximately 14.87 V, and ISV is 14.87 * (30 / 5630), or 0.08 V. With the positive pole insulated, the negative pole resistance (Rn2) at time T2 is (5.6 + 0.03)∥2.8∥(0.1∥0.1) [MΩ]. If we ignore the "0.03" for ease of calculation, the value is 0.049 MΩ, and the positive pole resistance (Rp2) is (10∥10) [MΩ], or 5 MΩ. Then, at time T2, VG1 is approximately 7.76 V, and ISV is 7.76 * (30 / 5630), or 0.04 V.

[0082] 4) In the case of an insulation fault state of the battery pack 10, the insulation sensing voltage (ISV) measured at time T1 may be 2.13 V, and the insulation sensing voltage (ISV) measured at time T2 may be 2.13 V. Specifically, in the insulation fault state, the positive electrode resistance (Rp1) at time T1 is (2.8 + 2.8)∥(0.1∥0.1) [MΩ], which is approximately 0.05 MΩ, and the negative electrode resistance (Rn1) is (5.6 + 0.03)∥(0.1∥0.1) [MΩ], which is approximately 0.05 MΩ. Then, VG1 at time T1 is approximately 400 V, and ISV is 400 * (30 / 5630), which is 2.13 V. Under an insulation fault condition, the negative resistance (Rn2) at time T2 is (5.6 + 0.03)∥2.8∥(0.1∥0.1) [MΩ]. If we ignore the "0.03" for ease of calculation, the value is 0.049 MΩ, and the positive resistance (Rp2) is (0.1∥0.1) [MΩ], or 0.05 MΩ. Therefore, at time T2, VG1 is approximately 400 V, and ISV is 400 * (30 / 5630), or 2.13 V.

[0083] Thus, the levels of the insulation sensing voltage (ISV) sensed at time points T1 and T2 differ for normal insulation, negative insulation, positive insulation, and abnormal insulation. That is, instead of calculating the positive and negative insulation resistances, the insulation diagnosis logic 212 can compare the digital value of the insulation sensing voltage (ISV) provided by the ADC 211 with a predetermined reference value to determine the insulation status between the positive and / or negative poles and ground. If the insulation sensing voltage (ISV) is higher than the input voltage range of the ADC 211, the value of resistor R4 can be decreased. If the insulation sensing voltage (ISV) is too low for the ADC 211 to recognize, the value of resistor R4 can be increased.

[0084] FIG. 7 is a flowchart illustrating a method for determining an insulation state according to one embodiment.

[0085] The insulation state determination method shown in FIG.

[0086] The insulation diagnosis logic 212 may compare the insulation sensing voltage (ISV_T1) at time T1 with a first reference voltage (e.g., 2.5 V) (S1). If the comparison result of step S1 indicates that the insulation sensing voltage (ISV_T1) is higher than the first reference voltage (VR1), the insulation diagnosis logic 212 may determine that the insulation state of the battery pack 10 is a negative electrode insulation state (S2).

[0087] If the comparison result of step S1 indicates that the insulation sensing voltage (ISV_T1) is less than or equal to the first reference voltage (VR1), the insulation diagnosis logic 212 may compare the insulation sensing voltage (ISV_T1) at time T1 with a second reference voltage (VR2) (e.g., 0.5 V) (S3). If the comparison result of step S3 indicates that the insulation sensing voltage (ISV_T1) is lower than the second reference voltage (VR2), the insulation diagnosis logic 212 may determine that the insulation state of the battery pack 10 is a positive insulation state (S4).

[0088] When the insulation sensing voltage (ISV_T1) at time T1 is less than the first reference voltage and greater than or equal to the second reference voltage, the insulation diagnostic logic 212 may compare the insulation sensing voltage (ISV_T2) at time T2 with a third reference voltage (e.g., 1.5 V) (VR3) (S5).

[0089] If the comparison result in step S5 indicates that the insulation sensing voltage (ISV_T2) at time T2 is equal to or greater than the third reference voltage (VR3), the insulation diagnosis logic 212 can determine that the insulation state of the battery pack 10 is an abnormal insulation state (S6).

[0090] If it is determined in step S5 that the insulation sensing voltage (ISV_T2) at time T2 is lower than the third reference voltage (VR3), the insulation diagnosis logic 212 may determine that the insulation state of the battery pack 10 is the all-insulation state (S7).

[0091] Steps S1-S7 are an example for explaining a method for determining the insulation state based on the insulation sensing voltages (ISV_T1, ISV_T2) at time points T1 and T2, and the first to third reference voltages (VR1 to VR3) are an example of criteria for classifying the insulation state, and the invention is not limited thereto.

[0092] The present invention may be embodied in a different manner from the embodiment shown in Figures 4 to 7. In the following description of other embodiments, the overlapping description of the first embodiment will be omitted.

[0093] FIG. 8 is a waveform diagram showing signals for controlling the switching of a plurality of switches according to another embodiment.

[0094] The period TU2 in FIG. 8 may be a unit period for insulation diagnosis.

[0095] 8 may be repeated, and the insulation diagnosis may be repeated. When the period TU2 is repeated, a predetermined time interval may exist between two adjacent periods TU2. The insulation diagnosis logic 212 may calculate the insulation resistance in each repeated insulation diagnosis and determine the insulation state of the battery pack 10 based on the calculated insulation resistance value.

[0096] As shown in Figure 8, period TU2 includes periods TP3 and TP4. During period TP3, the switching control signals (SS2) and (SS3) are at high levels, i.e., on levels, and the switch control signal (SS1) is at low levels, i.e., off levels. Therefore, during period TP3, switches (SW2) and (SW3) are in the on state, and switch (SW1) is in the off state. During period TP3, the equivalent circuit of the insulation diagnosis circuit is the same as that shown in Figure 5 of the previous embodiment.

[0097] 8 can indicate any point in time during the period TP3. The ADC 211 can convert the insulation sensing voltage (ISV) at the time T3 into a digital signal. The explanation for the insulation sensing voltage (ISV) at the time T3 is the same as the insulation sensing voltage (ISV) at the time T1 in the previous embodiment, which is described with reference to Equations 1 and 2.

[0098] During the period TP4, the switching control signals (SS2) to (SS3) are at a high level, ie, an on level, so that the switches (SW2), (SW1), and (SW3) are in an on state during the period TP4.

[0099] 8 can indicate any point in time during the period TP4. The ADC 211 can convert the insulation sensing voltage (ISV) at the time T4 into a digital signal. The explanation for the insulation sensing voltage (ISV) at the time T4 is the same as the insulation sensing voltage (ISV) at the time T2 in the previous embodiment, which is described with reference to Equations 3 and 4.

[0100] The method of determining the insulation state by the insulation diagnosis logic 212 is the same as that described above with reference to FIG.

[0101] FIG. 9 is a waveform diagram showing signals for controlling the switching of a plurality of switches according to another embodiment.

[0102] As shown in FIG. 9, in another embodiment, when insulation diagnosis is performed, the switches (SW2) and (SW3) are controlled to be in the ON state, and only the switch (SW1) can perform a switching operation at a constant period.

[0103] At time T5, the switching control signals SS2 and SS3 are at a high level (on level), and the switching control signal SS1 is at a low level (off level). Subsequently, the switches SW2 and SW3 are in an on state, and the switch SW1 is in an off state. The ADC 211 converts the insulation sensing voltage (ISV) at time T5 into a digital signal. The explanation for the insulation sensing voltage (ISV) at time T5 is the same as the explanation for the insulation sensing voltage (ISV) at time T1, referring to Equations 1 and 2 in the previous embodiment.

[0104] At time T6, the switching control signals SS2 to SS3 are at a high level, i.e., on level. Therefore, at time T6, the switches SW2, SW1, and SW3 are in an on state. The ADC 211 converts the insulation sensing voltage (ISV) at time T6 into a digital signal. The explanation for the insulation sensing voltage (ISV) at time T6 is the same as the explanation for the insulation sensing voltage (ISV) at time T2, which is described in relation to Equations 3 and 4 of the previous embodiment.

[0105] The method of determining the insulation state by the insulation diagnosis logic 212 is the same as that described above with reference to FIG.

[0106] An isolation diagnostic circuit according to some embodiments of the present disclosure may include only one switch, in which case ADC 211 and / or isolation diagnostic logic 212 may not operate when not in an isolation diagnostic period.

[0107] FIG. 10 is a diagram showing an insulation diagnosis circuit according to another embodiment.

[0108] The insulation diagnosis circuit 110 shown in FIG. 10 may not include the switch (SW2) and the switch (SW3) as compared with the insulation diagnosis circuit 100 previously shown in FIG.

[0109] The insulation diagnostic circuit 110 is connected to the positive terminal (P+), negative terminal (P-) and ground of the battery pack 10. The insulation diagnostic circuit 110 includes a switch (SW1) and four resistors (R1-R4).

[0110] Resistors R1 and R2 are connected between the positive terminal (P+) of the battery pack 10 and ground, and resistors R3 and R4 are connected between the negative terminal (P-) of the battery pack 10 and ground. One end of resistor R1 is connected to the positive terminal (P+) of the battery pack 10, and the other end of resistor R1 and one end of resistor R2 are connected by contact 1102, and the other end of resistor R2 is connected to ground. One end of resistor R3 is connected to ground, and the other end of resistor R3 and one end of resistor R4 are connected by contact 1101. Switch SW1 is connected between contact 1102 and the negative terminal (P-). The voltage at contact 1101 (insulation sense voltage, ISV) can be provided to the cell monitoring IC 21.

[0111] In the insulation diagnosis circuit 110 shown in FIG. 10, when the switch (SW1) is in the off state, the ADC 211 can convert the insulation sensing voltage (ISV) into a digital signal. The explanation for this insulation sensing voltage (ISV) is the same as the insulation sensing voltage (ISV) at time T1 in the previous embodiment, with reference to Equations 1 and 2. In the insulation diagnosis circuit 110, when the switch (SW1) is in the on state, the ADC 211 can convert the insulation sensing voltage (ISV) into a digital signal. The explanation for this insulation sensing voltage (ISV) is the same as the insulation sensing voltage (ISV) at time T2 in the previous embodiment, with reference to Equations 3 and 4. The insulation status determination method of the insulation diagnosis logic 212 is the same as the explanation given above with reference to FIG. 7.

[0112] In this way, the embodiment can perform insulation diagnosis of the battery pack through an insulation diagnosis circuit having a simplified circuit configuration.

[0113] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these examples, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the claims below also fall within the scope of the present invention.

Claims

1. An insulation diagnostic circuit for diagnosing an insulation state of a battery pack, a first resistor and a second resistor connected in series between the positive electrode of the battery pack and a first node; a first switch connected between a second node at which the first resistor and the second resistor are connected to each other and the negative electrode of the battery pack; a third resistor coupled between the first node and a third node; and an insulation diagnostic circuit including a fourth resistor connected in series between the third node and a negative electrode of the battery pack;

2. 2. The isolation diagnostic circuit of claim 1, wherein the first node is coupled to ground.

3. a second switch coupled between the first node and ground; and 2. The insulation diagnostic circuit of claim 1, further comprising a third switch coupled between the third node and one end of the fourth resistor.

4. When the second switch and the third switch are in an on state and the first switch is in an off state, the first resistor and the second resistor are connected in series between the positive electrode of the battery pack and the ground; the third resistor and the fourth resistor are connected in series between the negative electrode of the battery pack and the ground; 4. The insulation diagnostic circuit of claim 3, wherein a first insulation resistance is formed between the ground and the positive terminal of the battery pack, and a second insulation resistance is formed between the ground and the negative terminal of the battery pack.

5. When the first switch to the third switch are in an on state, the second resistor is connected between the ground and the negative electrode of the battery pack; the third resistor and the fourth resistor are connected between the ground and the negative electrode of the battery pack; 4. The insulation diagnostic circuit of claim 3, wherein a first insulation resistance is formed between the ground and the positive terminal of the battery pack, and a second insulation resistance is formed between the ground and the negative terminal of the battery pack.

6. 6. The insulation diagnostic circuit of claim 3, wherein the second switch is implemented as a photoMOS relay, and the first switch and the third switch are implemented as FETs.

7. a battery pack including a plurality of battery cells; an insulation diagnostic circuit for diagnosing the insulation state of the battery pack; and a cell monitoring IC that diagnoses an insulation state of the battery pack by using an insulation detection voltage provided from the insulation diagnosis circuit; The insulation diagnostic circuit includes: a first resistor and a second resistor connected in series between the positive electrode of the battery pack and a first node; a first switch connected between a second node at which the first resistor and the second resistor are connected to each other and the negative electrode of the battery pack; a third resistor coupled between the first node and a third node; and a fourth resistor connected in series between the third node and a negative electrode of the battery pack.

8. The battery system of claim 7 , wherein the first node is coupled to ground.

9. The cell monitoring IC includes:

9. The battery system of claim 8, wherein a positive electrode insulation resistance between a positive electrode of the battery pack and the ground and a negative electrode insulation resistance between a negative electrode of the battery pack and the ground are calculated using a first insulation sensing voltage that is the voltage of the third node when the first switch is in an off state and a second insulation sensing voltage that is the voltage of the third node when the first switch is in an on state.

10. The first insulation sensing voltage is the ground voltage is a voltage obtained by resistance-dividing the third resistor and the fourth resistor, and the ground voltage is a voltage obtained by resistance-dividing the battery pack voltage by a first insulation resistor and a second insulation resistor; The first insulation resistance is a parallel sum resistance of the third resistor, the fourth resistor, and the negative electrode insulating resistor, which are connected in series; The second insulation resistor is The battery system according to claim 9 , wherein the positive electrode insulating resistor is a parallel sum of the first resistor, the second resistor, and the positive electrode insulating resistor, which are connected in series.

11. The second insulation sensing voltage is the ground voltage is a voltage obtained by resistance-dividing the third resistor and the fourth resistor, and the ground voltage is a voltage obtained by resistance-dividing the battery pack voltage by a first insulation resistor and a second insulation resistor; The first insulation resistance is a parallel sum resistance of the third resistor, the fourth resistor, the second resistor, and the negative electrode insulating resistor, which are connected in series; The second insulation resistor is The battery system of claim 9 , wherein the positive electrode insulation resistor.

12. The cell monitoring IC includes:

10. The battery system of claim 9, wherein the insulation state of the battery pack is diagnosed using a first insulation sensing voltage that is the voltage of the third node when the first switch is in an off state and a second insulation sensing voltage that is the voltage of the third node when the first switch is in an on state.

13. The cell monitoring IC includes: When the first insulation sensing voltage is equal to or lower than a predetermined first reference voltage and equal to or higher than a predetermined second reference voltage, and the second insulation sensing voltage is equal to or higher than a predetermined third reference voltage, The battery system according to claim 12 , wherein the insulation between the positive electrode of the battery pack and the ground and the insulation between the negative electrode of the battery pack and the ground are both determined to be in an abnormal state.

14. The cell monitoring IC includes: When the first insulation sensing voltage is equal to or lower than a predetermined first reference voltage and equal to or higher than a predetermined second reference voltage, and the second insulation sensing voltage is lower than a predetermined third reference voltage, The battery system according to claim 12 , wherein insulation between the positive electrode of the battery pack and the ground and insulation between the negative electrode of the battery pack and the ground are all determined to be in a normal state.

15. The cell monitoring IC includes: when the first insulation sensing voltage is equal to or less than a predetermined first reference voltage and less than a predetermined second reference voltage; The battery system according to claim 12 , wherein the insulation between the positive electrode of the battery pack and the ground is determined to be normal, and the insulation between the negative electrode of the battery pack and the ground is determined to be abnormal.

16. The cell monitoring IC includes: When the first insulation sensing voltage exceeds a predetermined first reference voltage, The battery system according to claim 12 , wherein the insulation between the negative electrode of the battery pack and the ground is determined to be normal, and the insulation between the positive electrode of the battery pack and the ground is determined to be abnormal.

17. The insulation diagnostic circuit includes: a second switch coupled between the first node and ground; and The battery system of claim 7 , further comprising a third switch coupled between the third node and one end of the fourth resistor.

18. The cell monitoring IC includes: generating a second switching control signal and a third switching control signal at an on level for turning on the second switch and the third switch during a first period, and a first switching control signal at an on level for turning on the first switch during a second period; 18. The battery system of claim 17, wherein the first time period and the second time period overlap, and the first time period is longer than the second time period.

19. The cell monitoring IC includes: generating a second switching control signal and a third switching control signal at an on level to turn on the second switch and the third switch during a first period and a second period; The battery system of claim 17 , further comprising: generating a first switching control signal having an on level that turns on the first switch for the second period.

Images