Insulation diagnosis circuit and battery system including same

Abstract

An insulation diagnosis circuit for diagnosing an insulation state of a battery pack may comprise: 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 negative electrode of the battery pack and a second node at which the first resistor and the second resistor are connected to each other; 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

Insulation diagnostic circuit and battery system including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0117682, filed September 5, 2023, the entire contents of which are incorporated herein by reference.

[0003] The present disclosure relates to an insulation diagnostic circuit and a battery system including the same.

[0004] Battery insulation resistance is a critical safety requirement. Battery-equipped vehicles and light electric vehicles can command the battery management system (BMS) to measure and diagnose insulation resistance to ensure battery safety. BMSs use expensive components, such as photomos relays, to measure insulation resistance. Therefore, there is a need to reduce the cost of equipping the BMS with components for measuring battery insulation resistance.

[0005] An object of the present invention is to provide an insulation diagnostic circuit capable of reducing the cost required for implementing a circuit for measuring the insulation resistance of a battery, and a battery system including the same.

[0006] An insulation diagnosis circuit for diagnosing an insulation state of a battery pack according to one feature of the invention 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 to which the first resistor and the second resistor are connected 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.

[0007] The above first node can be connected to ground.

[0008] The above 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.

[0009] 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, so that a first insulation resistance between the ground and the positive electrode of the battery pack and a second insulation resistance between the ground and the negative electrode of the battery pack can be formed.

[0010] 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, and 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.

[0011] The second switch may be implemented as a photomos relay, and the first switch and the third switch may be implemented as FETs.

[0012] According to another aspect of the invention, a battery system may include a battery pack including a plurality of battery cells, an insulation diagnosis 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 detection voltage provided from the insulation diagnosis circuit. The insulation diagnosis 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 to which the first resistor and the second resistor are connected 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.

[0013] The above first node can be connected to ground.

[0014] The above 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.

[0015] The cell monitoring IC can calculate the positive insulation resistance between the positive electrode of the battery pack and the ground and the negative insulation resistance between the negative electrode of the battery pack and the ground using the first insulation detection voltage, which is the voltage of the third node when the first switch is in the off state, and the second insulation detection voltage, which is the voltage of the third node when the first switch is in the on state.

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

[0017] The second insulation detection voltage may be a voltage obtained by resistance-dividing the voltage of the ground by the third resistor and the fourth resistor, and the voltage of the ground may be a voltage obtained by resistance-dividing the voltage of the battery pack by the first insulation resistor and the second insulation resistor. The first insulation resistance may be a parallel sum resistance of the third resistor and the fourth resistor, the second resistor, and the negative insulation resistance connected in series, and the second insulation resistance may be the positive insulation resistance.

[0018] The cell monitoring IC can diagnose the insulation status of the battery pack using a first insulation detection voltage, which is the voltage of the third node when the first switch is in an off state, and a second insulation detection voltage, which is the voltage of the third node when the first switch is in an on state.

[0019] 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 abnormal when the first insulation detection voltage is lower than or equal to a predetermined first reference voltage and higher than or equal to a predetermined second reference voltage, and the second insulation detection voltage is higher than or equal to a predetermined third reference voltage.

[0020] 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 when the first insulation detection voltage is lower than or equal to a predetermined first reference voltage and higher than or equal to a predetermined second reference voltage, and the second insulation detection voltage is lower than a predetermined third reference voltage.

[0021] The above cell monitoring IC can determine that the insulation between the positive electrode of the battery pack and the ground is normal and the insulation between the negative electrode of the battery pack and the ground is abnormal when the first insulation detection voltage is lower than a predetermined first reference voltage and lower than a predetermined second reference voltage.

[0022] The above cell monitoring IC can determine that the insulation between the negative electrode of the battery pack and the ground is normal and the insulation between the positive electrode of the battery pack and the ground is abnormal when the first insulation detection voltage exceeds a predetermined first reference voltage.

[0023] The cell monitoring IC generates a second switching control signal and a third switching control signal that are on levels for turning on the second switch and the third switch for a first period, and a first switching control signal that is on levels for turning on the first switch for a second period, wherein the first period and the second period overlap, and the first period may be longer than the second period.

[0024] The cell monitoring IC can generate a second switching control signal and a third switching control signal that are on levels for turning on the second switch and the third switch during the first period and the second period, and can generate a second switching control signal that is on levels for turning on the first switch during the second period.

[0025] Provided are an insulation diagnostic circuit that can reduce the cost required to implement a circuit for measuring the insulation resistance of a battery, and a battery system including the same.

[0026] FIG. 1 is a diagram illustrating a battery system according to one embodiment.

[0027] FIG. 2 is a circuit diagram showing a part of a battery system according to one embodiment.

[0028] FIG. 3 is a circuit diagram showing a plurality of switches in an insulation diagnostic circuit according to one embodiment.

[0029] FIG. 4 is a waveform diagram showing signals that control switching of a plurality of switches according to one embodiment.

[0030] Fig. 5 is a circuit diagram showing an equivalent circuit of an insulation diagnostic circuit in period TP1.

[0031] Fig. 6 is a circuit diagram showing an equivalent circuit of an insulation diagnostic circuit in period TP2.

[0032] Fig. 7 is a flowchart illustrating a method for determining an insulation status according to one embodiment.

[0033] FIG. 8 is a waveform diagram showing signals controlling switching of multiple switches according to another embodiment.

[0034] FIG. 9 is a waveform diagram showing signals controlling switching of multiple switches according to another embodiment.

[0035] Fig. 10 is a diagram showing an insulation diagnostic circuit according to another embodiment.

[0036] In describing the embodiments disclosed in this specification, detailed descriptions of related known technologies will be omitted if it is determined that such detailed descriptions may obscure the gist of the embodiments disclosed in this specification. In addition, the attached drawings are provided solely to facilitate understanding of the embodiments disclosed in this specification, and the technical concepts disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and substitutes included within the spirit and technical scope of the present invention.

[0037] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0038] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0039] In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0040] FIG. 1 is a diagram illustrating a battery system according to one embodiment.

[0041] 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).

[0042] 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) can 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) can be electrically connected to the external connection terminal (OT-) of the battery system (1).

[0043] The current sensor (40) detects the current flowing in the battery pack (10) (hereinafter, battery current), and the current sensor (40) can transmit a signal (IS) indicating the detected current to the BMS (20).

[0044] The BMS (20) may include a cell monitoring IC (21), a main control unit (MCU) (22), and an insulation diagnostic 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 two terminals of the battery pack (10) (hereinafter, battery voltage). The cell monitoring IC (21) may generate a signal indicating the measured plurality of cell voltages and battery voltage and provide the signal to the MCU (22).

[0045] The cell monitoring IC (21) can collect measurement voltages required to calculate the insulation resistance of the battery pack (10) by controlling the insulation diagnosis circuit (100). The cell monitoring IC (21) can control the operation of the insulation diagnosis circuit (100) to collect the measurement voltages. The cell monitoring IC (21) can determine the insulation state of the battery pack (10) based on the measurement voltages. The cell monitoring IC (21) can calculate the insulation resistance of the battery pack (10) based on the measurement voltages and determine the insulation state of the battery pack (10).

[0046] The MCU (22) collects information about a plurality of battery cell voltages, battery voltages, battery currents, and temperatures of the battery pack (10), and controls the charge and discharge current of the battery pack (10) based on the collected plurality of cell voltages, battery currents, etc., and can control cell balancing operations for the plurality of battery cells (CE1 to CEn). The MCU (22) can control the opening and closing of the first relay (30) and the second relay (40) to control the charging and discharging 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 the signals to the first relay (30) and the second relay (35). The MCU (22) receives the insulation status of the battery pack (10) from the cell monitoring IC (21), and if there is an insulation abnormality between the positive electrode (P+) and / or negative electrode (P-) of the battery pack (10) and the ground, the MCU can stop the operation of the battery system (10) or transmit the status to an external device via wired or wireless communication.

[0047] FIG. 2 is a circuit diagram showing a part of a battery system according to one embodiment.

[0048] In Fig. 2, a battery pack (10), a first relay (30), a second relay (35), and an insulation diagnosis circuit (100) are specifically illustrated. For convenience of explanation, some components illustrated in Fig. 1 may be omitted in Fig. 2. In Fig. 2, an external device (5) is connected between an external connection terminal (OT+) and an external connection terminal (OT-) of a battery system (1). This is one 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 terminal (OT+) and the external connection terminal (OT-), a power conversion device (51), and an electrical load (52). The power conversion device (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 terminal (OT+) and the external connection terminal (OT-).

[0049] The first relay (30) includes a main relay (31), a precharge relay (32), and a precharge resistor (33). The main relay (31) is connected between the positive electrode (P+) and an external connection terminal (OT+), and the precharge relay (32) and the precharge resistor (33) are connected in series between the positive electrode (P+) and the external connection terminal (OT+). The series-connected precharge relay (32) and the precharge resistor (33), and the main relay (31) are connected in parallel between the positive electrode (P+) and the external connection terminal (OT+). The main relay (31) can be closed according to an on-level relay control signal (RC1), and can be opened according to an off-level relay control signal (RC1). The precharge relay (32) can be closed according to an on-level relay control signal (RC3), and can be opened according to an off-level relay control signal (RC3). The second relay (35) is connected between the cathode (P-) and the external connection terminal (OT-), and can be closed according to an on-level relay control signal (RC2) and opened according to an off-level relay control signal (RC2). After the second relay (35) and the precharge relay (32) are closed, the main relay (31) can be closed, and after the main relay (31) is closed, the precharge relay (32) can be opened.

[0050] The Y capacitor (YC1) is connected between the positive electrode (P+) and the ground, and the Y capacitor (YC2) is connected between the negative electrode (P-) and the ground. The insulation resistance (RL1) represents insulation between the positive electrode (P+) of the battery pack (10) and the ground, and the insulation resistance (RL2) represents insulation between the negative electrode (P-) of the battery pack (10) and the ground. The insulation resistance (RL3) represents insulation between the wiring between the positive electrode (P+) of the battery pack (10) and the external connection terminal (OT+) and the ground, and the insulation resistance (RL4) may represent insulation between the wiring between the negative electrode (P-) of the battery pack (10) and the external connection terminal (OT-) and the ground.

[0051] When the insulation diagnosis is performed, if the first relay (30) is in a closed state, the parallel sum resistance of the insulation resistance (RL1) and the insulation resistance (RL3) may represent insulation between the positive pole of the battery pack (10) and the ground. When the second relay (35) is in a closed state, the parallel sum resistance of the insulation resistance (RL2) and the insulation resistance (RL4) may represent insulation between the negative pole of the battery pack (10) and the ground. In contrast, when the insulation diagnosis is performed, if the first relay (30) is in an open state, the insulation resistance (RL1) may represent insulation between the positive pole of the battery pack (10) and the ground. When the second relay (35) is in an open state, the insulation resistance (RL2) may represent insulation between the negative pole of the battery pack (10) and the ground.

[0052] Hereinafter, the resistance indicating the insulation between the positive electrode of the battery pack (10) and the ground is 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 is referred to as the negative electrode insulation resistance.

[0053] When the positive insulation resistance is less than a predetermined threshold, the insulation between the positive electrode (P+) and the ground can be considered to be broken, and when the negative insulation resistance is less than a predetermined threshold, the insulation between the negative electrode (P-) and the ground can be considered to be broken. The battery pack (10) must be electrically insulated from the external device (5). If the battery pack (10) is not insulated from the ground, the external device (5) and the battery pack (10) may be connected through the ground, causing the insulation between the battery pack (10) and the external device (5) to be broken. The BMS (20) according to one embodiment can calculate the positive insulation resistance and the negative insulation resistance through the insulation diagnosis circuit (100), compare the calculated values ​​with the threshold, and determine the insulation status between the battery pack (10) and the ground based on the comparison result. Alternatively, the BMS (20) can determine the insulation status of the positive and negative electrodes of the battery pack (10) using the voltages detected through the insulation diagnosis circuit (100). “Insulation state” may include a normal insulation state when the insulation resistance between two components is greater than a predetermined threshold value, and an abnormal insulation state when the insulation resistance is less than the threshold value.

[0054] The insulation diagnosis circuit (100) is connected to the positive pole (P+) and negative pole (P-) of the battery pack (10) and the ground. The insulation diagnosis circuit (100) includes three switches (SW2, SW1, SW3) and four resistors (R1-R4).

[0055] A switch (SW2), a resistor (R1), and a resistor (R2) are connected between the positive pole (P+) of the battery pack (10) and the ground, and a switch (SW3), a resistor (R3), and a resistor (R4) are connected between the negative pole of the battery pack (10) and the contact (102).

[0056] One end of the resistor (R1) is connected to the positive pole (P+) of the battery pack (10), and the other end of the resistor (R1) and one end of the resistor (R2) are connected at a contact point (103). The other end of the resistor (R2) and one end of the switch (SW2) are connected at a contact point (102), and the other end of the switch (SW2) is connected to ground. One end of the resistor (R3) is connected to the contact point (102), and the other end of the resistor (R3) and one end of the switch (SW3) are connected at a contact point (101). The other end of the switch (SW3) is connected to one end of the resistor (R4), and the other end of the resistor (R4) is connected to the negative pole (P-) of the battery pack (10). The switch (SW1) is connected between the contact point (103) and the negative pole (P-). The voltage (insulation detection voltage, ISV) of the contact point (101) can be provided to the cell monitoring IC (21). The cell monitoring IC (21) may include an analog-to-digital converter (ADC) (211) and insulation diagnosis logic (212). The ADC (211) may convert an insulation detection voltage (ISV) into a digital value and provide the digital value to the insulation diagnosis logic (212). The insulation diagnosis logic (212) may use the digital value to calculate the positive insulation resistance between the positive electrode (P+) of the battery pack (10) and the ground, and the negative insulation resistance between the negative electrode (P-) of the battery pack (10) and the ground, respectively. The insulation diagnosis logic (212) may compare the values ​​of the positive insulation resistance and the negative insulation resistance with threshold values, and may determine 1) a normal insulation state, 2) a negative insulation state, 3) a positive insulation state, and 4) an insulation abnormal state based on the comparison result.

[0057] 1) Normal insulation state means that both the positive and negative poles of the battery pack are insulated from the ground. 2) Negative insulation state means that the negative pole of the battery pack is insulated from the ground, and the positive pole of the battery pack is over-insulated from the ground. 3) Positive insulation state means that the positive pole of the battery pack is insulated from the ground, and the negative pole of the battery pack is over-insulated from the ground. 4) Over-insulation state means that the positive and negative poles of the battery pack are over-insulated from the ground. In the normal insulation state, the resistance values ​​of both the positive insulation resistance and the negative insulation resistance are greater than the threshold. In the negative insulation state, the negative insulation resistance is greater than the threshold, and the positive insulation resistance is less than the threshold. In the positive insulation state, the positive insulation resistance is greater than the threshold, and the negative insulation resistance is less than the threshold. In the over-insulation state, the resistance values ​​of both the positive insulation resistance and the negative insulation resistance are less than the threshold.

[0058] The cell monitoring IC (21) can generate a plurality of switching control signals (SS2 to SS3) that control the switching operations of a plurality of switches (SW2 to SW3). The cell monitoring IC (21) can supply a plurality of switching control signals (SS2 to SS3) to an insulation diagnosis circuit (100) for insulation diagnosis. The plurality of switches (SW2 to SW3) can turn on or off the plurality of switches (SW2 to SW3) according to the plurality of switching control signals (SS2 to SS3). For example, the on level of the plurality of switching control signals (SS2 to SS3) can be a high level, and the off level can be a low level.

[0059] 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) can be turned off.

[0060] FIG. 3 is a circuit diagram showing a plurality of switches in an insulation diagnostic circuit according to one embodiment.

[0061] As illustrated in Fig. 3, the switch (SW2) is implemented as a photoMOS relay, and the switches (SW1, SW3) can be implemented as FETs. The switch (SW2) operates in a high voltage range, but the switching control signal (SS2) is generated in a low voltage range, and is therefore implemented as a photoMOS relay. The switches (SW1, SW3) are connected to the negative pole (P-) of the battery pack (10), and can perform a switching operation by a switching control signal (SS1, SS3) of a low voltage level.

[0062] The switch (SW2) may include two MOSFETs (111, 112) connected in series, a diode (113), and a switching element (114). The switching element (114) is turned on according to a high-level switching control signal (SS2) that is an on level, and is turned off according to a low-level switching signal (SS2) that is an off level. A power supply voltage (VD) is supplied to the anode of the diode (113), the cathode of the diode (113) is connected to one end of the switching element (114), and the other end of the switching element (114) may be connected to ground. The ground connected to the other end of the switching element (114) may be a low-voltage ground, unlike the ground for the battery pack (10). The drain of the MOSFET (111) is connected to the contact (102), the source of the MOSFET (111) is connected to the source of the MOSFET (112), and the drain of the MOSFET (112) can be connected to ground. In the on state of the switching element (114), current flows in the diode (113), and the MOSFETs (111, 112) can be turned on according to the light emission of the diode (113). In the off state of the switching element (114), no current flows in the diode (113), and the MOSFETs (111, 112) are in the off state.

[0063] The switch (SW1) is implemented as an n-channel FET, the drain of the switch (SW1) is connected to a 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 a high-level switching control signal (SS1) that is an on level, and the switch (SW1) can be turned off by a low-level switching control signal (SS1) that is an off level.

[0064] The switch (SW3) is implemented as an n-channel FET, the drain of the switch (SW3) is connected to a contact (101), the source of the switch (SW3) is connected to one end of a resistor (R4), and a switching control signal (SS3) can be supplied to the gate of the switch (SW3). The switch (SW3) can be turned on by a high-level switching control signal (SS3) that is an on level, and the switch (SW3) can be turned off by a low-level switching control signal (SS3) that is an off level.

[0065] Hereinafter, a method for measuring insulation detection voltage (ISV) according to the switching operation of multiple switches (SW2-SW3) is described with reference to FIG. 4.

[0066] FIG. 4 is a waveform diagram showing signals that control switching of a plurality of switches according to one embodiment.

[0067] The period TU1 of FIG. 4 may be a unit period for insulation diagnosis. The period TU1 illustrated in FIG. 4 may be repeated, and the insulation diagnosis may be repeated. When the period TU1 is repeated, a predetermined time interval may exist between two adjacent periods TU1. The MCU (22) may calculate insulation resistances in each of the repeated insulation diagnoses, and determine the insulation status of the battery pack (10) based on the calculated insulation resistance values.

[0068] As illustrated in Fig. 4, period TU1 includes period TP1 and period TP2. In period TP1, the switching control signal (SS2) and the switching control signal (SS3) are at a high level, which is an on level, and the switching control signal (SS1) is at a low level, which is an off level.

[0069] Fig. 5 is a circuit diagram showing an equivalent circuit of an insulation diagnostic circuit in period TP1.

[0070] As illustrated in FIG. 5, the battery pack (10) is depicted as a voltage source (VP). Two resistors (R1, R2) may be connected in series between the positive pole of the voltage source (VP) and the ground, and two resistors (R3, R4) may be connected in series between the ground and the negative pole of the voltage source (VP). The positive insulation resistance (RLP) may be connected between the positive pole of the voltage source (VP) and the ground, and the negative insulation resistance (RLN) may be connected in series between the ground and the negative pole of the voltage source (VP). The positive insulation resistance (RLP) may be the parallel sum resistance (RL1∥RL3) of the insulation resistance (RL1) and the insulation resistance (RL3). The negative insulation resistance (RLN) may be the parallel sum resistance (RL2∥RL4) of the insulation resistance (RL2) and the insulation resistance (RL4). Alternatively, the positive insulation resistance (RLP) may be the insulation resistance (RL1), and the negative insulation resistance (RLN) may be the insulation resistance (RL2).

[0071] Point T1 in Fig. 4 can indicate any point in time during period TP1. The ADC (211) can convert the insulation detection voltage (ISV) of point T1 into a digital signal. The insulation detection voltage (ISV) of point T1 can be defined as in Mathematical Expression 1 below.

[0072] [Mathematical Formula 1]

[0073] ISV = VG1 * R4 / (R3+R4)

[0074] In mathematical expression 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).

[0075] The voltage of the ground (VG1) can be defined as in mathematical expression 2.

[0076] [Equation 2]

[0077] VG1 = VP * Rn1 / (Rp1+Rn1)

[0078] 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 resistance value of the two series-connected resistors (R3, R4) and the positive insulation resistance (RLP) ((R3+R4)∥RLP). The positive resistance (Rp1) is the parallel sum resistance value of the two series-connected resistors (R1, R2) and the positive insulation resistance (RLP) (((R1+R2)∥RLP).

[0079] In period TP2, the switching control signal (SS2), the switching control signal (SS1), and the switching control signal (SS3) are at a high level, which is the on level.

[0080] Fig. 6 is a circuit diagram showing an equivalent circuit of an insulation diagnostic circuit in period TP2.

[0081] As illustrated in Fig. 6, a resistor (R1) is connected between both ends of a voltage source (VP) corresponding to a battery pack (10), and the resistor (R1) is connected between the negative pole of the voltage source (VP) and the ground. Two resistors (R3, R4) may be connected in series between the ground and the negative pole of the voltage source (VP). The positive insulation resistor (RLP) may be connected between the positive pole of the voltage source (VP) and the ground, and the negative insulation resistor (RLN) may be connected in series between the ground and the negative pole of the voltage source (VP).

[0082] Point T2 in Fig. 4 can indicate any point in time within the period TP2. The ADC (211) can convert the insulation detection voltage (ISV) of point T2 into a digital signal. The insulation detection voltage (ISV) of point T2 can be defined as in the following mathematical expression 3.

[0083] [Equation 3]

[0084] ISV = VG2 * R4 / (R3+R4)

[0085] In mathematical expression 3, “VG2” is the voltage of the ground at time T2, “R3” is the resistance value of the resistor (R3), and “R4” is the resistance value of the resistor (R4).

[0086] The voltage of the ground (VG2) can be defined as in mathematical expression 4.

[0087] [Equation 4]

[0088] VG2 = VP * Rn2 / (Rp2+R2n)

[0089] In Equation 4, “VP” is the voltage of the voltage source (VP), “Rn2” is the negative resistance seen from the ground at time T2, and “Rp2” is the positive resistance seen from the ground at time T2. The negative resistance (Rn2) is the parallel sum resistance value of the two series-connected resistors (R3, R4), the resistor (R2), and the negative insulation resistance (RLN) ((R3+R4)∥R2∥RLN). The positive resistance (Rp2) is the value of the positive insulation resistance (RLP).

[0090] Since the insulation diagnosis logic (212) knows the two values ​​of the insulation detection voltage (ISV) obtained at each of time points T1 and T2, the resistance values ​​of the four resistors (R1-R4), and the voltage value of the battery pack (10), it can calculate the resistance values ​​of the positive insulation resistance (RLP) and the negative insulation resistance (RLN) through mathematical expressions 1 to 4.

[0091] The insulation diagnosis logic (212) can compare the resistance values ​​of the positive insulation resistance (RLP) and the negative insulation resistance (RLN) with a predetermined threshold, and determine that there is an insulation problem between the pole of the battery pack (10) and the ground corresponding to an insulation resistance smaller than the threshold. For example, if the resistance value of the positive insulation resistance (RLP) is less than the threshold and the resistance value of the negative insulation resistance (RLN) is greater than the threshold, the insulation diagnosis logic (212) can determine that the battery pack (10) is in a negative insulation state. If the resistance value of the negative insulation resistance (RLN) is less than the threshold and the resistance value of the positive insulation resistance (RLP) is greater than the threshold, the insulation diagnosis logic (212) can determine that the battery pack (10) is in a positive insulation state. If the resistance values ​​of both the positive insulation resistance (RLP) and the negative insulation resistance (RLN) are less than the threshold, the insulation diagnosis logic (212) can determine that the battery pack (10) is in an insulation abnormal state. If the resistance values ​​of both the positive insulation resistance (RLP) and the negative insulation resistance (RLN) are greater than the threshold, the insulation diagnosis logic (212) can determine that the battery pack (10) is in a normal insulation state.

[0092] In the previous embodiment, insulation diagnosis was performed by calculating the positive insulation resistance and negative insulation resistance values, but the invention is not limited thereto. The insulation diagnosis logic (212) can determine the insulation status based on the values ​​of the insulation detection voltage (ISV) obtained at points T1 and T2.

[0093] For example, it is assumed that the voltage of the battery pack (10) is 800 V, R1=2.8 MΩ, R2=2.8 MΩ, R3=5.6 MΩ, and R4=30 KΩ, and that RL1 to RL4 are 10 MΩ when in a normal insulation state and RL1 to RL4 are 100 KΩ when in an abnormal insulation state.

[0094] 1) When the battery pack (10) is in a normal insulation state, the insulation detection voltage (ISV) measured at time T1 may be 2.13 V, and the insulation detection voltage (ISV) measured at time T2 may be 0.91 V. Specifically, in a normal insulation state, the positive resistance (Rp1) at time T1 is (2.8+2.8)∥(10∥10)[MΩ], i.e., 2.64 MΩ, and the negative resistance (Rn1) is (5.6+0.03)∥(10∥10)[MΩ], i.e., 2.65 MΩ. Then, VG1 at time T1 is approximately 400 V, and ISV is 400*(30 / 5630), i.e., 2.13 V. Under normal insulation conditions, the cathode resistance (Rn2) at point T2 is (5.6+0.03)∥2.8∥(10∥10)[MΩ], and when “0.03” is ignored for the convenience of calculation, the value is 1.36MΩ, and the anode resistance (Rp2) is (10∥10)[MΩ], i.e., 5MΩ. Then, VG1 at point T2 is approximately 171V, and ISV is 171*(30 / 5630), or 0.91V.

[0095] 2) When the battery pack (10) is in a negative insulation state, the insulation detection voltage (ISV) measured at time T1 may be 4.2 V, and the insulation detection voltage (ISV) measured at time T2 may be 4.11 V. Specifically, in the negative insulation state, the positive resistance (Rp1) at time T1 is (2.8+2.8)∥(0.1∥0.1)[MΩ], which is approximately 0.05 MΩ, and the negative resistance (Rn1) is (5.6+0.03)∥(10∥10)[MΩ], which is 2.65 MΩ. Then, VG1 at time T1 is approximately 785 V, and the ISV is 785*(30 / 5630), which is 4.2 V. In the cathode insulation state, the cathode resistance (Rn2) at time T2 is (5.6+0.03)∥2.8∥(10∥10)[MΩ], and when “0.03” is ignored for the convenience of calculation, the value is 1.36MΩ, and the anode resistance (Rp2) is (0.1∥0.1)[MΩ], that is, 0.05MΩ. Then, VG1 at time T2 is approximately 772V, and ISV is 171*(30 / 5630), which is 4.11V.

[0096] 3) In the case of the positive insulation state of the battery pack (10), the insulation detection voltage (ISV) measured at time T1 may be 0.08 V, and the insulation detection voltage (ISV) measured at time T2 may be 0.04 V. Specifically, in the positive insulation state, the positive resistance (Rp1) at time T1 is (2.8+2.8)∥(10∥10)[MΩ], that is, 2.64 MΩ, and the negative 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 14.87 V, and the ISV is 14.87*(30 / 5630), which is 0.08 V. In the positive insulation state, the cathode resistance (Rn2) at time T2 is (5.6+0.03)∥2.8∥(0.1∥0.1)[MΩ], and when “0.03” is ignored for the convenience of calculation, the value is 0.049MΩ, and the anode resistance (Rp2) is (10∥10)[MΩ], i.e., 5MΩ. Then, VG1 at time T2 is approximately 7.76V, and ISV is 7.76*(30 / 5630), which is 0.04V.

[0097] 4) In the case of an insulation abnormality of the battery pack (10), the insulation detection voltage (ISV) measured at time T1 may be 2.13 V, and the insulation detection voltage (ISV) measured at time T2 may be 2.13 V. Specifically, in the insulation abnormality, the positive resistance (Rp1) at time T1 is (2.8+2.8)∥(0.1∥0.1)[MΩ], which is approximately 0.05 MΩ, and the negative 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. In the insulation fault condition, the cathode resistance (Rn2) at point T2 is (5.6+0.03)∥2.8∥(0.1∥0.1)[MΩ], and when “0.03” is ignored for the convenience of calculation, the value is 0.049MΩ, and the anode resistance (Rp2) is (0.1∥0.1)[MΩ], that is, 0.05MΩ. Then, VG1 at point T2 is approximately 400V, and ISV is 400*(30 / 5630) or 2.13V.

[0098] In this way, the levels of the insulation detection voltage (ISV) detected at time points T1 and T2 are different in the normal insulation state, the negative insulation state, the positive insulation state, and the insulation fault state, respectively. That is, instead of calculating the positive insulation resistance and the negative insulation resistance, the insulation diagnosis logic (212) can compare the digital value of the insulation detection voltage (ISV) provided from the ADC (211) with predetermined reference values ​​to determine the insulation state between the positive and / or negative electrodes and the ground. If the insulation detection voltage (ISV) is higher than the input voltage range of the ADC (211), the value of the resistor (R4) can be lowered. If the insulation detection voltage (ISV) is too low for the ADC (211) to recognize, the value of the resistor (R4) can be increased.

[0099] Fig. 7 is a flowchart illustrating a method for determining an insulation status according to one embodiment.

[0100] The insulation status method illustrated in Fig. 7 can be performed according to the insulation diagnosis logic (211).

[0101] The insulation diagnosis logic (212) can compare the insulation detection voltage (ISV_T1) at point T1 with a first reference voltage (e.g., 2.5 V) (S1). If the comparison result of step S1 shows that the insulation detection voltage (ISV_T1) is higher than the first reference voltage (VR1), the insulation diagnosis logic (212) can determine the insulation status of the battery pack (10) as a negative insulation status (S2).

[0102] If the comparison result of step S1 shows that the insulation detection voltage (ISV_T1) is lower than or equal to the first reference voltage (VR1), the insulation diagnosis logic (212) can compare the insulation detection voltage (ISV_T1) at time point T1 with a second reference voltage (e.g., 0.5 V) (VR2) (S3). If the comparison result of step S3 shows that the insulation detection voltage (ISV_T1) is lower than the second reference voltage (VR2), the insulation diagnosis logic (212) can determine the insulation state of the battery pack (10) as a positive insulation state (S4).

[0103] The insulation diagnosis logic (212) can compare the insulation detection voltage (ISV_T2) of time point T2 with a third reference voltage (e.g., 1.5 V) (VR3) when the insulation detection voltage (ISV_T1) of time point T1 is lower than or equal to the first reference voltage and higher than or equal to the second reference voltage (S5).

[0104] As a result of the comparison in step S5, if the insulation detection voltage (ISV_T2) at point T2 is higher than the third reference voltage (VR3), the insulation diagnosis logic (212) can determine the insulation status of the battery pack (10) as an insulation abnormality (S6).

[0105] As a result of the judgment in step S5, if the insulation detection voltage (ISV_T2) at point T2 is less than the third reference voltage (VR3), the insulation diagnosis logic (212) can determine that the insulation status of the battery pack (10) is all in an insulation state (S7).

[0106] Steps S1 to S7 are examples for explaining a method for judging an insulation state according to insulation detection voltages (ISV_T1, ISV_T2) at time points T1 and T2, and the first to third reference voltages (VR1 to VR3) are examples for criteria for distinguishing an insulation state, but the invention is not limited thereto.

[0107] The present invention may be implemented in a manner different from the embodiment illustrated in FIGS. 4 to 7. In the following description of other embodiments, any description overlapping with that of the embodiment will be omitted.

[0108] FIG. 8 is a waveform diagram showing signals controlling switching of multiple switches according to another embodiment.

[0109] The period TU2 of FIG. 8 may be a unit period for insulation diagnosis. The period TU2 illustrated in FIG. 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 insulation resistances in each of the repeated insulation diagnoses, and determine the insulation status of the battery pack (10) based on the calculated insulation resistance values.

[0110] As illustrated in FIG. 8, period TU2 includes periods TP3 and TP4. In period TP3, the switching control signal (SS2) and the switching control signal (SS3) are at a high level, which is an on level, and the switch control signal (SS1) is at a low level, which is an off level. Therefore, during period TP3, the switches (SW2) and (SW3) are in an on state, and the switch (SW1) is in an off state. The equivalent circuit of the insulation diagnostic circuit in period TP3 is the same as that in FIG. 5 of the preceding embodiment.

[0111] Time point T3 of FIG. 8 can indicate any time point during the period TP3. The ADC (211) can convert the insulation detection voltage (ISV) of time point T3 into a digital signal. The description of the insulation detection voltage (ISV) of time point T3 is the same as the insulation detection voltage (ISV) of time point T1 with reference to mathematical expressions 1 and 2 of the previous embodiment.

[0112] During period TP4, the switching control signal (SS2) to the switching control signal (SS3) are at a high level, which is the on level. Therefore, during period TP4, the switches (SW2), (SW1), and (SW3) are in the on state.

[0113] Time point T4 of FIG. 8 can indicate any time point during the period TP4. The ADC (211) can convert the insulation detection voltage (ISV) of time point T4 into a digital signal. The description of the insulation detection voltage (ISV) of time point T4 is the same as the insulation detection voltage (ISV) of time point T2 with reference to mathematical expressions 3 and 4 of the previous embodiment.

[0114] The method for judging the insulation status of the insulation diagnosis logic (212) is the same as the description previously given with reference to FIG. 7.

[0115] FIG. 9 is a waveform diagram showing signals controlling switching of multiple switches according to another embodiment.

[0116] As shown in Fig. 9, in another embodiment, when insulation diagnosis is performed, the switch (SW2) and the switch (SW3) are controlled to be in an on state, and only the switch (SW1) can perform a switching operation at a constant cycle.

[0117] At time T5, the switching control signal (SS2) and the switching control signal (SS3) are at a high level, which is an on level, and the switching control signal (SS1) is at a low level, which is an off level. Then, the switches (SW2, SW3) are in an on state, and the switch (SW1) is in an off state. The ADC (211) can convert the insulation detection voltage (ISV) at time T5 into a digital signal. The description of the insulation detection voltage (ISV) at time T5 is the same as the insulation detection voltage (ISV) at time T1 with reference to mathematical expressions 1 and 2 of the previous embodiment.

[0118] At time T6, the switching control signal (SS2) to the switching control signal (SS3) are at a high level, which is an on level. Therefore, at time T6, the switch (SW2), the switch (SW1), and the switch (SW3) are in an on state. The ADC (211) can convert the insulation detection voltage (ISV) at time T6 into a digital signal. The description of the insulation detection voltage (ISV) at time T6 is the same as the insulation detection voltage (ISV) at time T2 with reference to mathematical expressions 3 and 4 of the previous embodiment.

[0119] The method for judging the insulation status of the insulation diagnosis logic (212) is the same as the description previously given with reference to FIG. 7.

[0120] In some embodiments of the present disclosure, the insulation diagnostic circuit may include only one switch. In this case, the ADC (211) and / or the insulation diagnostic logic (212) may not operate when the insulation diagnostic period is not in progress.

[0121] Fig. 10 is a diagram showing an insulation diagnostic circuit according to another embodiment.

[0122] The insulation diagnosis circuit (110) illustrated in FIG. 10 may not include a switch (SW2) and a switch (SW3) compared to the insulation diagnosis circuit (100) previously referred to in FIG. 2.

[0123] The insulation diagnosis circuit (110) is connected to the positive pole (P+) and negative pole (P-) of the battery pack (10) and the ground. The insulation diagnosis circuit (110) includes a switch (SW1) and four resistors (R1-R4).

[0124] Resistors (R1) and (R2) are connected between the positive electrode (P+) of the battery pack (10) and the ground, and resistors (R3) and (R4) are connected between the negative electrode (P-) of the battery pack (10) and the ground. One end of resistor (R1) is connected to the positive electrode (P+) of the battery pack (10), the other end of resistor (R1) and one end of resistor (R2) are connected at a contact point (113), 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 at a contact point (111). A switch (SW1) is connected between the contact point (112) and the negative electrode (P-). The voltage (insulation detection voltage, ISV) of the contact point (111) can be provided to the cell monitoring IC (21).

[0125] In the insulation diagnosis circuit (110) illustrated in FIG. 10, when the switch (SW1) is in the off state, the ADC (211) can convert the insulation detection voltage (ISV) into a digital signal. The description of this insulation detection voltage (ISV) is the same as the insulation detection voltage (ISV) at point T1 with reference to mathematical expressions 1 and 2 of the previous embodiment. In the insulation diagnosis circuit (110), when the switch (SW1) is in the on state, the ADC (211) can convert the insulation detection voltage (ISV) into a digital signal. The description of this insulation detection voltage (ISV) is the same as the insulation detection voltage (ISV) at point T2 with reference to mathematical expressions 3 and 4 of the previous embodiment. The insulation status determination method of the insulation diagnosis logic (212) is the same as the description with reference to FIG. 7.

[0126] In this way, the embodiments can perform insulation diagnosis of a battery pack through an insulation diagnosis circuit having a simplified circuit configuration.

[0127] 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 those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. In an insulation diagnosis circuit for diagnosing the insulation status of a battery pack, A first resistor and a second resistor connected in series between the positive electrode and the first node of the battery pack; A first switch connected between a second node to which 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 the third node; and including a fourth resistor connected in series between the third node and the negative electrode of the battery pack; Insulation diagnostic circuit.

2. In paragraph 1, An insulated diagnostic circuit, wherein the first node is connected to ground.

3. In paragraph 1, a second switch connected between the first node and the ground; and Further comprising a third switch connected between the third node and one end of the fourth resistor, Insulation diagnostic circuit.

4. In paragraph 3, When the second switch and the third switch are on and the first switch is off, 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, A first insulation resistance is formed between the ground and the positive electrode of the battery pack, and a second insulation resistance is formed between the ground and the negative electrode of the battery pack. Insulation diagnostic circuit.

5. In paragraph 3, When the first switch to the third switch are in the on state, The second resistor is connected between the ground and the negative pole of the battery pack, The third resistor and the fourth resistor are connected between the ground and the negative electrode of the battery pack, A first insulation resistance is formed between the ground and the positive electrode of the battery pack, and a second insulation resistance is formed between the ground and the negative electrode of the battery pack. Insulation diagnostic circuit.

6. In paragraph 3, The second switch is implemented as a photomos relay, and the first switch and the third switch are implemented as FETs. Insulation diagnostic circuit.

7. A battery pack comprising a plurality of battery cells; An insulation diagnosis circuit for diagnosing the insulation status of the above battery pack; and Includes a cell monitoring IC that diagnoses the insulation status of the battery pack using the insulation detection voltage provided from the insulation diagnosis circuit, The above insulation diagnostic circuit, A first resistor and a second resistor connected in series between the positive electrode and the first node of the battery pack; A first switch connected between a second node to which 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 the third node; and including a fourth resistor connected in series between the third node and the negative electrode of the battery pack; Battery system.

8. In paragraph 7, A battery system wherein the first node is connected to ground.

9. In paragraph 7, The above cell monitoring IC, Calculating the positive insulation resistance between the positive electrode of the battery pack and the ground and the negative insulation resistance between the negative electrode of the battery pack and the ground using the first insulation detection voltage, which is the voltage of the third node when the first switch is in the off state, and the second insulation detection voltage, which is the voltage of the third node when the first switch is in the on state. Battery system.

10. In paragraph 9, The above first insulation detection voltage is, The voltage of the ground is a voltage that is resistance-divided by the third resistor and the fourth resistor, and the voltage of the ground is a voltage that is resistance-divided by the voltage of the battery pack by the first insulation resistor and the second insulation resistor. The above first insulation resistance is, The parallel sum resistance of the third and fourth resistors connected in series and the anode insulation resistance, The above second insulation resistance is, The parallel sum resistance of the first resistor and the second resistor connected in series, and the anode insulation resistance, Battery system.

11. In paragraph 9, The above second insulation detection voltage is, The voltage of the ground is a voltage that is resistance-divided by the third resistor and the fourth resistor, and the voltage of the ground is a voltage that is resistance-divided by the voltage of the battery pack by the first insulation resistor and the second insulation resistor. The above first insulation resistance is, The parallel sum resistance of the third resistor, the fourth resistor, the second resistor, and the cathode insulation resistance connected in series, The above second insulation resistance is, The above anode insulation resistance is, Battery system.

12. In paragraph 9, The above cell monitoring IC, Diagnosing the insulation status of the battery pack using the first insulation detection voltage, which is the voltage of the third node when the first switch is in the off state, and the second insulation detection voltage, which is the voltage of the third node when the first switch is in the on state. Battery system.

13. In paragraph 12, The above cell monitoring IC, When the first insulation detection voltage is less than or equal to a predetermined first reference voltage and greater than or equal to a predetermined second reference voltage, and the second insulation detection voltage is greater than or equal to a predetermined third reference voltage, It is determined that the insulation between the positive pole of the battery pack and the ground, and the insulation between the negative pole of the battery pack and the ground are both in an abnormal state. Battery system.

14. In paragraph 12, The above cell monitoring IC, When the first insulation detection voltage is less than or equal to a predetermined first reference voltage and greater than or equal to a predetermined second reference voltage, and the second insulation detection voltage is less than or equal to a predetermined third reference voltage, It is determined that the insulation between the positive pole of the battery pack and the ground, and the insulation between the negative pole of the battery pack and the ground are both in a normal state. Battery system.

15. In paragraph 12, The above cell monitoring IC, When the first insulation detection voltage is lower than a predetermined first reference voltage and lower than a predetermined second reference voltage, It is determined that the insulation between the positive pole of the battery pack and the ground is normal, and the insulation between the negative pole of the battery pack and the ground is abnormal. Battery system.

16. In paragraph 12, The above cell monitoring IC, When the above first insulation detection voltage exceeds a predetermined first reference voltage, It is determined that the insulation between the negative pole of the battery pack and the ground is normal, and the insulation between the positive pole of the battery pack and the ground is abnormal. Battery system.

17. In paragraph 7, The above insulation diagnostic circuit, a second switch connected between the first node and the ground; and Further comprising a third switch connected between the third node and one end of the fourth resistor, Battery system.

18. In paragraph 17, The above cell monitoring IC, Generate a second switching control signal and a third switching control signal that are on levels for turning on the second switch and the third switch during a first period, and a first switching control signal that is on levels for turning on the first switch during a second period, The first period and the second period overlap, and the first period is longer than the second period. Battery system.

19. In paragraph 17, The above cell monitoring IC, During the first period and the second period, a second switching control signal and a third switching control signal are generated at an on level that turns on the second switch and the third switch, Generating a second switching control signal that is an on level that turns on the first switch during the second period; Battery system.

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