Battery system, relay back electromotive force protection circuit and protection circuit monitoring method

Abstract

The invention relates to a battery system, a relay back electromotive force protection circuit and a protection circuit monitoring method. The battery system includes: a battery pack; a relay connected to one of the two terminals of the battery pack and including a relay coil; and a battery management system (BMS) connected to the relay coil to control an operation of the relay, in which the BMS includes: a protection circuit that operates the relay by applying a voltage to the relay coil, and that includes a capacitor connected in parallel with the relay coil; and a main control unit (MCU) that transmits a control signal for controlling an operation of the relay to the protection circuit, and that diagnoses the operation of the protection circuit based on a voltage signal received from the protection circuit.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2022-0183572 filed in the Korean Intellectual Property Office on December 23, 2022, the entire contents of which are incorporated herein by reference.

[0003] The present disclosure relates to a battery system, a relay back electromotive force (EMF) protection circuit, and a protection circuit monitoring method. Background Art

[0004] A mechanical relay may include a coil and a contactor. When the power applied to the coil is disconnected to stop the operation of the relay, a back electromotive force (EMF) is generated in the coil. Back EMF is a phenomenon that occurs due to the current characteristics of the relay coil.

[0005] When back EMF is excessively generated, the relay driver driving the relay may malfunction. Summary of the invention

[0006] Technical issues

[0007] The present disclosure attempts to provide a battery system, a relay electromotive force (EMF) protection circuit, and a protection circuit monitoring method, which can prevent back EMF by including a protection circuit that prevents back EMF from being generated in a relay and diagnosing whether the protection circuit operates normally.

[0008] Technical Solution

[0009] According to one aspect of the present disclosure, a battery system includes: a battery pack; a relay connected to one of two terminals of the battery pack and including a relay coil; and a battery management system (BMS) connected to the relay coil to control the operation of the relay, wherein the BMS includes: a protection circuit that applies a voltage to the relay coil to operate the relay and includes a capacitor connected in parallel with the relay coil; and a main control unit (MCU) that sends a control signal for controlling the operation of the relay to the protection circuit and diagnoses the operation of the protection circuit based on a voltage signal received from the protection circuit.

[0010] The protection circuit may include: a first switch that applies a driving voltage to a high voltage side of the relay coil; a second switch that connects ground to a low voltage side of the relay coil; and a Schottky diode that is connected in parallel with the relay coil and has a positive terminal connected to the high voltage side of the relay coil and a negative terminal connected to the low voltage side of the relay coil.

[0011] The BMS may further include: a first ADC, which generates a first voltage measurement signal by performing analog-to-digital conversion on a signal corresponding to the high-voltage side voltage of the relay coil; and a second ADC, which generates a second voltage measurement signal by performing analog-to-digital conversion on a signal corresponding to the low-voltage side voltage of the relay coil.

[0012] The MCU may determine whether the protection circuit is in a normal state based on the first voltage measurement signal and the second voltage measurement signal.

[0013] The MCU can monitor the first voltage measurement signal and the second voltage measurement signal to derive a first voltage value representing the voltage across the relay coil when the first switch and the second switch are in the on state, derive a second voltage value representing the voltage across the relay coil when the first switch or the second switch is in the off state, measure the back electromotive force EMF of the relay coil based on the first voltage value and the second voltage value, and determine whether the protection circuit is in the normal state based on the back EMF.

[0014] According to another aspect of the present disclosure, a relay back-EMF protection circuit includes: a first switch that applies a driving voltage to a high-voltage side of a relay coil included in a relay; a second switch that connects ground to a low-voltage side of the relay coil; a capacitor that is connected in parallel with the relay coil; and a Schottky diode having a positive terminal and a negative terminal, the positive terminal being connected to the high-voltage side of the relay coil, and the negative terminal being connected to the low-voltage side of the relay coil.

[0015] The protection circuit may further include: a first resistor and a second resistor, the first resistor and the second resistor being connected in series to the high voltage side of the relay coil; a diode having a negative terminal to which a voltage is applied and a positive terminal connected to one terminal of a third resistor, the other terminal of the third resistor being connected to the low voltage side of the relay coil; and a fourth resistor and a fifth resistor, the fourth resistor and the fifth resistor being connected in series to the low voltage side of the relay coil, and outputting a signal representing a voltage corresponding to the high voltage side voltage of the relay coil from a node between the first resistor and the second resistor, and outputting a signal representing a voltage corresponding to the low voltage side voltage of the relay coil from a node between the fourth resistor and the fifth resistor.

[0016] According to another aspect of the present disclosure, a protection circuit monitoring method for preventing back EMF of a relay comprises the following steps: a main control unit (MCU) turns on a high-voltage side switch connected to the high-voltage side of a relay coil included in the relay and a low-voltage side switch connected to the low-voltage side of the relay coil; the MCU receives two first signals from the protection circuit; the MCU derives a first voltage value based on the two first signals, the first voltage value representing the voltage across the relay coil when the high-voltage side switch and the low-voltage side switch are in the on state; the MCU turns off the high-voltage side switch or the low-voltage side switch; the MCU receives two second signals from the protection circuit; the MCU derives a second voltage value based on the two first signals, the second voltage value representing the voltage across the relay coil when the high-voltage side switch and the low-voltage side switch are in the off state; and the MCU diagnoses the operation of the protection circuit based on the first voltage value and the second voltage value.

[0017] The protection circuit may include: a capacitor connected in parallel with the relay coil; and a Schottky diode connected in parallel with the relay coil and having a positive terminal connected to a high voltage side of the relay coil and a negative terminal connected to the low voltage side of the relay coil.

[0018] The step of diagnosing the operation of the protection circuit by the MCU based on the first voltage value and the second voltage value may include the following steps: measuring the back EMF of the relay coil based on the first voltage value and the second voltage value, and determining whether the protection circuit is in a normal state based on the back EMF.

[0019] Beneficial Effects

[0020] According to the present disclosure, it is possible to reduce back electromotive force (EMF) generated in a relay coil and discharge the back EMF quickly.

[0021] According to the present disclosure, back EMF can be reduced to protect a driver driving a relay coil from being damaged by excessive back EMF.

[0022] According to the present disclosure, it is possible to determine whether the protection circuit operates normally by monitoring the voltage across the relay coil from the protection circuit to prevent back EMF. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a block diagram schematically illustrating a battery system according to an embodiment.

[0024] Figure 2 yes Figure 1 Circuit diagram of the protection circuit.

[0025] Figure 3 yes Figure 1 Circuit diagram of the protection circuit in the case of switch disconnection.

[0026] Figure 4 is a flow chart of a protection circuit monitoring method according to an embodiment.

[0027] Figure 5 is an example diagram of a comparison circuit including a TVS diode and a Schottky diode.

[0028] Figure 6 is shown connected to Figure 5 Diagram of the high side voltage diagram of the relay coil of the comparison circuit.

[0029] Figure 7 is a diagram of a high voltage side voltage of a relay coil according to an embodiment.

[0030] Figure 8 is connected to Figure 5 The low side voltage diagram of the relay coil of the comparison circuit.

[0031] Fig. 9 is a low-voltage side voltage diagram of a relay coil according to an embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and the same or similar parts are given the same figure marks and will not be described repeatedly. The suffixes "module" and / or "unit" of the parts used in the following description are given or mixed only for the sake of ease of writing of the specification, and therefore, they themselves have no mutually distinguishable meanings or functions. In addition, when it is determined that a detailed description of known technologies related to the present disclosure may obscure the subject matter of the present disclosure, the detailed description will be omitted. In addition, it should be understood that the drawings are provided only to make the exemplary embodiments of the present disclosure easy to understand, and the spirit of the present disclosure is not limited to the drawings, but includes all modifications, equivalents and substitutions included in the spirit and scope of the present disclosure.

[0033] Terms including ordinal numbers (such as first, second, etc.) may be used to describe various components, but the components are not limited to these terms. The above terms are used only for the purpose of distinguishing one component from another.

[0034] It should be further understood that the terms "include" or "have" used in this specification specify the presence of the features, numbers, steps, operations, components, parts or a combination thereof mentioned in this specification, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or a combination thereof.

[0035] Among the components according to the embodiment, a program implemented as a set of instructions specifying a control algorithm required for controlling other components can be installed in the components that control other components under specific control conditions. The control component can process input data and stored data according to the installed program to generate output data. The control component may include a non-volatile memory for storing the program and a memory for storing data.

[0036] Figure 1 is a block diagram schematically illustrating a battery system according to an embodiment.

[0037] Reference Figure 1 , the battery system 1 may include a battery pack 100 , a relay 200 , and a battery management system (BMS) 300 .

[0038] The battery pack 100 may include a plurality of battery cells. The battery pack 100 may be implemented as two or more battery cells connected in series, a plurality of battery cells having two or more battery cells connected in parallel, or two or more battery cells connected in parallel.

[0039] The relay 200 may include a relay coil 210. One terminal of the relay 200 may be connected to one of two terminals of the battery pack 100. The other terminal of the relay 200 may be connected to the external device 2.

[0040] The battery system 1 can be connected to an external device 2. The external device 2 may include a load and a charging device (such as an inverter or a converter). When the external device 2 is a charger, both terminals P+ and P- of the battery system 1 can be connected to the charger and charged by receiving power from the charger. When the external device 2 is a load, both terminals P+ and P- of the battery system 1 are connected to the load, so that the power provided by the battery pack 100 can be discharged through the load.

[0041] exist Figure 1 , the relay 200 is shown as being included only between the positive terminal + of the battery pack 100 and the terminal P+ of the battery system 1, but the present disclosure is not limited thereto. The battery system 1 may also include a relay between the negative terminal - of the battery pack 100 and the terminal P- of the battery system 1, and the back electromotive force protection circuit to be described later may also be applied to the relay between the negative terminal - and the terminal P- of the battery system 1.

[0042] The BMS 300 may operate the relay coil 210 and determine whether a protection circuit that reduces the back electromotive force (EMF) of the relay coil 210 operates within a normal range. The BMS 300 may include a relay anti-EMP protection circuit (hereinafter referred to as a "protection circuit") 310, a main control unit (MCU), and analog-to-digital converters (ADCs) ADC1 and ADC2.

[0043] The protection circuit 310 may be a circuit for discharging the back EMF that may occur due to the characteristics of the relay coil 210. The protection circuit 310 may operate based on the high-side control signal HCS and the low-side control signal LSC received from the MCU 320. The protection circuit 310 may operate the relay 200 by applying a voltage to the relay coil 210 using the high-side control signal HCS and the low-side control signal LSC. When the voltage applied to the relay coil 210 disappears due to the switching operation, a reverse voltage may be applied to both terminals of the relay coil 210. The protection circuit 310 may reduce the reverse voltage generated at both terminals of the relay coil 210. In addition, the protection circuit 310 may provide a discharge path so that the back EMF is discharged quickly. The protection circuit 310 may generate a high-side signal HSS corresponding to the high-side voltage of the relay coil 210, and send the generated high-side signal to the first analog-to-digital converter ADC1, and generate a low-side signal LSS corresponding to the low-side voltage of the relay coil 210, and send the generated low-side signal LSS to the second analog-to-digital converter ADC2.

[0044] The first analog-to-digital converter ADC1 may generate a voltage measurement signal VS1 obtained by performing analog-to-digital conversion on the high-voltage side signal HSS, and transmit the generated voltage measurement signal VS1 to the MCU 320. The second analog-to-digital converter ADC2 may generate a voltage measurement signal VS2 obtained by performing analog-to-digital conversion on the low-voltage side signal LSS, and transmit the generated voltage measurement signal VS2 to the MCU 320.

[0045] The MCU 320 may include a terminal P1 and a terminal P2. The MCU 320 may receive a voltage measurement signal VS1 from a first analog-to-digital converter ADC1 through the terminal P1. The MCU 320 may receive a voltage measurement signal VS2 from a second analog-to-digital converter ADC2 through the terminal P2. The MCU 320 may derive a high-voltage side voltage value V_COIL_H of the relay coil 210 based on the voltage measurement signal VS1. The MCU 320 may derive a low-voltage side voltage value V_COIL_L of the relay coil 210 based on the voltage measurement signal VS2.

[0046] When an excessive back EMF is generated, it may exceed the limit of the relay driver driving the relay 200, which may cause damage to the driver. Therefore, the protection circuit 310 can act as a back EMF absorber to prevent the driver from being damaged.

[0047] The MCU 320 can control the driving of the protection circuit 310 by generating a high-voltage side control signal HCS and a low-voltage side control signal LSC and sending the high-voltage side control signal HCS and the low-voltage side control signal LSC to the protection circuit 310. The MCU 320 can monitor the voltage across the relay coil 210 according to the voltage measurement signal VS1 and the voltage measurement signal VS2, and determine whether the protection circuit 310 operates within a normal range based on the monitoring result. The voltage measurement signal VS1 can represent a value corresponding to the voltage on the high-voltage side (one terminal) of the relay coil 210, and the voltage measurement signal VS2 can represent a value corresponding to the voltage on the low-voltage side (the other terminal) of the relay coil 210.

[0048] In the following, reference will be made to Figure 2 The operation of the protection circuit 310 is reviewed.

[0049] Figure 2 yes Figure 1 Circuit diagram of the protection circuit.

[0050] Reference Figure 2 The protection circuit 310 may include a high-side switch HS, a low-side switch LS, a Schottky diode D_SCH, a capacitor C, a relay coil 210, a plurality of resistors R1-R5, and a diode D1. The Schottky diode D_SCH, the capacitor C, and the relay coil 210 may be connected in parallel.

[0051] The high-side control signal HCS may control the opening and closing of the high-side switch HS. The low-side control signal LCS may control the opening and closing of the low-side switch LS. The high-side switch HS may be a switch in a high-side driver connected to the high-voltage side of the relay coil 210. The low-side switch LS may be a switch in a low-voltage driver connected to the low-voltage side of the relay coil 210.

[0052] Figure 2 It is shown that the high-side control signal HCS and the low-side control signal LCS generated by the MCU 320 control the opening and closing of the high-side switch HS and the low-side switch LS, but the present disclosure is not limited thereto. The high-side control signal HCS and the low-side control signal LCS are respectively sent to corresponding drivers in the high-side driver HSD and the low-side driver LSD, and the HSD and the LSD can control the high-side switch HS and the low-side switch LS.

[0053] The high-side switch HS may be connected to the high-voltage side of the relay coil 210 to apply a driving voltage V1 to the relay coil 210. The voltage V1 may be applied to one terminal of the high-side switch HS. For example, the voltage V1 may be a 12V voltage provided from an auxiliary terminal AUX of the vehicle. The positive terminal of the Schottky diode D_SCH, one terminal of the capacitor C, one terminal of the relay coil 210, and one terminal of the resistor R1 may be connected to the other terminal of the high-side switch HS. One terminal of the resistor R2 may be connected to the other terminal of the resistor R1. The other terminal of the resistor R2 may be connected to ground.

[0054] The high-side signal HSS may represent a node N1 voltage between the resistor R1 and the resistor R2 . The voltage represented by the high-side signal HSS may be a voltage corresponding to a voltage at one terminal (high-side) of the relay coil 210 .

[0055] The low-voltage side switch LS can be connected to the low-voltage side of the relay coil 210 to connect the relay coil 210 to ground. One terminal of the low-voltage side switch LS can be connected to ground. The negative terminal (anodeterminal) of the Schottky diode D_SCH, the other terminal of the capacitor C, the other terminal of the relay coil 210, a terminal of the resistor R3 and a terminal of the resistor R4 can be connected to the other terminal of the low-voltage side switch LS. Voltage V2 can be applied to the negative terminal of the diode D1. The positive terminal of the diode D1 can be connected to the other terminal of the resistor R3. One terminal of the resistor R5 can be connected to the other terminal of the resistor R4. The other terminal of the resistor R5 can be connected to ground.

[0056] The low voltage side signal LSS may represent a node N2 voltage between the resistor R4 and the resistor R5 . The voltage represented by the low voltage side signal LSS may be a voltage corresponding to a voltage at the other terminal (low voltage side) of the relay coil 210 .

[0057] The MCU 320 may monitor the voltage measurement signal VS1 and the voltage measurement signal VS2 received from the first analog-to-digital converter ADC1 and the second analog-to-digital converter (ADC). The MCU 320 may control the operation of the high-side switch HS and the low-side switch LS through the high-side control signal HCS and the low-side control signal LCS during the monitoring.

[0058] The MCU 320 may monitor the voltage measurement signal VS1 and the voltage measurement signal VS2 to derive a first voltage value, which indicates the voltage across the relay coil 210 when the high-side switch HS and the low-side switch LS are in the on state. In addition, the MCU 320 may monitor the voltage measurement signal VS1 and the voltage measurement signal VS2 to derive a second voltage value, which indicates the voltage across the relay coil 210 when the high-side switch HS and the low-side switch LS are in the off state. The MCU 320 may measure the back EMF of the relay coil 210 based on the first voltage value and the second voltage value.

[0059] When the MCU 320 can generate a high-side control signal HCS of the on-level and a low-side control signal LCS of the on-level and send the high-side control signal HCS of the on-level and the low-side control signal LCS of the on-level to the protection circuit 310, the high-side switch HS and the low-side switch LS can be closed. When the high-side switch HS and the low-side switch LS are closed, the voltage V1 is applied to the relay coil 210 so that the coil current IL can flow. The relay 200 can be turned on by the magnetic field caused by the coil current IL. When the high-side switch HS and the low-side switch LS are closed, the capacitor C can store charges according to the voltage across the relay coil 210. In the on state of the high-side switch HS and the low-side switch LS, the voltage measurement signal VS1 can be divided from the voltage V1 by the resistor R1 and the resistor R2 to represent the voltage applied to one terminal of the resistor R2. When the high-side switch HS and the low-side switch LS are in the on state, the voltage measurement signal VS2 can represent grounding.

[0060] Figure 3 yes Figure 1 Circuit diagram of the protection circuit in the case of switch disconnection.

[0061] Reference Figure 3 , when the MCU 320 can generate a high-side control signal HCS and a low-side control signal LCS of a cut-off level, and send the high-side control signal HCS and the low-side control signal LCS of the cut-off level to the protection circuit 310, the high-side switch HS and the low-side switch LS can be turned on. When the high-side switch HS and the low-side switch LS perform a switching operation from an on state to an off state, a reverse voltage can be applied to both terminals of the relay coil 210. In this case, the voltage measurement signal VS1 changes from a voltage having a positive polarity to a voltage having a negative polarity according to the switching operation. When the high-side switch HS and the low-side switch LS are disconnected, the voltage measurement signal VS2 can be divided from the voltage V2 by the resistor R3, the resistor R4, and the resistor R5, and can represent a voltage applied to one terminal of the resistor R5.

[0062] Hereinafter, description will be made assuming that the voltage V1 and the voltage V2 are voltages having positive polarity.

[0063] When the high-side switch HS and the low-side switch LS are in the on state, the voltage measurement signal VS1 indicates a higher voltage than the voltage measurement signal VS2, so the high-side voltage of the relay coil 210 has a positive polarity and the low-side voltage has a negative polarity.

[0064] When the high-side switch HS and the low-side switch LS are disconnected, the voltage measurement signal VS1 indicates a lower voltage than the voltage measurement signal VS2 , so the high-side voltage of the relay coil 210 has a negative polarity and the low-side voltage has a positive polarity.

[0065] At the moment when the high-voltage side switch HS and the low-voltage side switch LS are turned on, the voltage V1 is not applied to the relay coil 210, so a reverse voltage is generated at both terminals of the relay coil 210. The capacitor C is connected in parallel with the relay coil 210 to reduce the reverse voltage (v=-L*di / dt) generated at both ends of the relay coil. The time rate of change dt may increase due to the capacitor C. The time rate of change refers to the time from the point in time when the voltage in the relay coil 210 is blocked to the time when the coil current stops flowing, and the coil current flows due to the voltage charged in the capacitor C for a longer period of time than when there is no capacitor C, so the time rate of change may increase. Then, the reverse voltage generated at both ends of the relay coil 210 may be reduced. In addition, the back EMF can be discharged quickly by connecting the Schottky diode D_SCH in parallel to the relay coil 210. The Schottky diode D_SCH forms a discharge path for quickly discharging the back EMF generated in the relay coil 210, thereby allowing the back EMF to be discharged quickly.

[0066] In an embodiment, the capacitor C and the Schottky diode D_SCH in the protection circuit 310 may be connected in parallel with the relay coil 210 to prevent excessive back EMF from being generated in the relay coil. When excessive back EMF is generated, the high-side switch HS and / or the low-side switch LS may be damaged. Therefore, a protection circuit is provided to prevent the high-side switch HS and / or the low-side switch LS from being damaged.

[0067] In the following, reference will be made to Figure 4 A protection circuit monitoring method using the battery system 1 according to the embodiment is described.

[0068] Figure 4 is a flow chart of a protection circuit monitoring method according to an embodiment.

[0069] The MCU 320 may generate a high-side control signal HCS and a low-side control signal LCS of an on-level, and transmit the high-side control signal HCS and the low-side control signal LCS of the on-level to the protection circuit 310 (S1). The high-side switch HS receiving the high-side control signal HCS of the on-level and the low-side switch LS receiving the low-side control signal LCS of the on-level may be turned on.

[0070] When the high-side switch HS and the low-side switch LS are closed, the MCU 320 may receive the voltage measurement signal VS1 and the voltage measurement signal VS2 from the first analog-to-digital converter ADC1 and the second analog-to-digital converter ADC2 ( S2 ).

[0071] The MCU 320 may derive a first voltage value (S3) based on the voltage measurement signal VS1 and the voltage measurement signal VS2. The first voltage value may represent the voltage across the relay coil 210 when the high-voltage side switch HS and the low-voltage side switch LS are in the on state. The MCU 320 may derive a high-voltage side voltage value V_COIL_H and a low-voltage side voltage value V_COIL_L based on the voltage measurement signal VS1 and the voltage measurement signal VS2, and calculate the first voltage value based on the high-voltage side voltage value V_COIL_H and the low-voltage side voltage value V_COIL_L.

[0072] The MCU 320 may generate a high-side control signal HCS and a low-side control signal LCS of a cut-off level and transmit the high-side control signal HCS and the low-side control signal LCS of the cut-off level to the protection circuit 310 ( S4 ).

[0073] When the high-side switch HS and the low-side switch LS are turned on, the MCU 320 may receive the voltage measurement signal VS1 and the voltage measurement signal VS2 from the first analog-to-digital converter ADC1 and the second analog-to-digital converter ADC2 .

[0074] The MCU 320 may derive a second voltage value based on the voltage measurement signal VS1 and the voltage measurement signal VS2 (S6). The second voltage value may represent the voltage across the relay coil 210 when the high-voltage side switch HS and the low-voltage side switch LS are in the off state. The MCU 320 may derive a high-voltage side voltage value V_COIL_H and a low-voltage side voltage value V_COIL_L based on the voltage measurement signal VS1 and the voltage measurement signal VS2, and calculate the second voltage value based on the high-voltage side voltage value V_COIL_H and the low-voltage side voltage value V_COIL_L.

[0075] The MCU 320 may determine whether the protection circuit 310 is in a normal state based on the first voltage value and the second voltage value (S7). The MCU 320 may monitor the first voltage value and the second voltage value to measure the back EMF of the relay coil 210 when the high-voltage side switch HS and the low-voltage side switch LS are switched from the on state to the off state. When the magnitude of the back EMF is less than or equal to a predetermined threshold level, the MCU 320 may determine that the protection circuit 310 is in a normal state.

[0076] In the following, reference will be made to Figure 5 The operation of the embodiment is described in the comparative example.

[0077] Figure 5 is an example diagram of a comparison circuit including a TVS diode and a Schottky diode.

[0078] Figure 5 The comparison circuit 310_1 shown is an example of a protection circuit for a relay coil, in which a Schottky diode and a TVS diode are connected in series, and no capacitor is included. In the protection circuit 310_1, the switch connected to the high voltage side of the relay coil is called the high voltage side switch C_HS, and the switch connected to the low voltage side of the relay coil is called the low voltage side switch C_LS. In the protection circuit 310_1, the high voltage side voltage of the relay coil is called the high voltage side voltage V_COMP_H, and the low voltage side voltage of the relay coil is called the low voltage side voltage V_COMP_L.

[0079] In the following, reference is made to Figure 6 and Figure 7 , it will be described that when the high-voltage side switch and the low-voltage side switch are closed and then the high-voltage side switch is opened, according to the protection circuit 310 according to the embodiment, connected to Figure 5 The comparison circuit 310_1 shows the changes of the high-side voltage V_COMP_H of the relay coil and the high-side voltage V_COIL_H of the relay coil 210 .

[0080] Figure 6 Shows the connection to Figure 5 The high side voltage diagram of the relay coil of the comparison circuit.

[0081] exist Figure 6 In the time period T from 0 to T1, the high-side switch C_HS is turned on and the low-side switch C_LS is closed. During the time period T from 0 to T1, the high-side voltage V_COMP_H of the relay coil connected to the comparison circuit 310_1 may represent 0V.

[0082] When the high-side switch C_HS is closed at the time point T1 , the voltage V_COMP_H may represent 12V. Since the high-side switch C_HS and the low-side switch C_LS are closed from the time point T1 to the time point T2 , the voltage V_COMP_H may represent 12V.

[0083] When the high-side switch C_HS is turned on at time point T2, back EMF may be generated in the relay coil, so the voltage V_COMP_H drops to -40V and then may represent 0V after time point T2.

[0084] Figure 7 is a diagram showing a high voltage side voltage diagram of a relay coil according to an embodiment.

[0085] exist Figure 7 In the embodiment, during the time period T from 0 to T3, the high-voltage side switch HS is turned on and the low-voltage side switch C_LS is turned on. During the time period T from 0 to T3, the high-voltage side voltage value V_COIL_H of the relay coil 210 according to the embodiment may represent 0V.

[0086] When the high-side switch HS is closed at time point T3 , the high-side voltage value V_COIL_H may represent 12V. Since the high-side switch HS and the low-side switch LS are closed from time point T3 to time point T4 , the high-side voltage V_COIL_H may represent 12V.

[0087] When the high-side switch HS is turned on at the time point T4, a back EMF may be generated in the relay coil, so the high-side voltage value V_COIL_H drops to -0.5V and then may represent 0V after the time point T4.

[0088] Reference Figure 6 and Figure 7 , when the high-voltage side switch is disconnected, the high-voltage side voltage V_COMP_H of the relay coil connected with the comparison circuit 310_1 drops to -40V, but the high-voltage side voltage V_COIL_H of the relay coil 210 connected with the protection circuit 310 according to the present embodiment drops only to -0.5V. This can be explained by assuming that when the low-voltage side switch LS is closed, the low-voltage side voltages V_COMP_L and V_COIL_L are 0V. In the comparison circuit 310_1, the voltage across the relay coil is -40-0=-40(V), but the voltage across the relay coil 210 according to the present embodiment is -0.5-0=-0.5(V). Therefore, in the embodiment, since the reverse voltage is smaller than the reverse voltage of the comparison circuit 310_1, a smaller back EMF due to the reverse voltage can be generated.

[0089] In the following, reference is made to Figure 8 and Fig. 9, it will be described that when the high-voltage side switch and the low-voltage side switch are closed and then the low-voltage side switch is opened, according to the protection circuit 310 according to the embodiment, the connection Figure 5 The comparison circuit 310_1 shows the changes of the low-voltage side voltage V_COMP_L of the relay coil and the low-voltage side voltage V_COIL_L of the relay coil 210 .

[0090] Figure 8 is connected to Figure 5 The low side voltage diagram of the relay coil of the comparison circuit.

[0091] exist Figure 8 In the example, during the time period T from 0 to T5, the high-side switch C_HS and the low-side switch C_LS are closed. During the time period T from 0 to T5, the low-side voltage V_COMP_L of the relay coil connected to the comparison circuit 310_1 may represent 0V.

[0092] When the low-voltage side switch C_LS is turned on at time point T5, back EMF may be generated in the relay coil, so the voltage V_COMP_L rises to 52V and then may represent 12V after time point T5.

[0093] Fig. 9 is a diagram showing a low-voltage side voltage diagram of a relay coil according to an embodiment.

[0094] exist Fig. 9 In the embodiment, during the time period T from 0 to T6, the high-side switch HS and the low-side switch LS are closed. During the time period T from 0 to T6, the low-side voltage V_COIL_L of the relay coil 210 according to the embodiment may represent 0V.

[0095] When the low-side switch C_LS is turned on at the time point T6 , a back EMF may be generated in the relay coil 210 , and thus the voltage V_COMP_L rises to 12.5 V and then may represent 12 V after the time point T6 .

[0096] Reference Figure 8 and Fig. 9, when the low-voltage side switch is disconnected, the low-voltage side voltage V_COMP_L of the relay coil connected to the comparison circuit 310_1 rises to 52V, but the low-voltage side voltage V_COIL_L of the relay coil 210 connected to the protection circuit 310 according to the present embodiment rises only to 12.5V. This can be explained by assuming that when the high-voltage side switch HS is closed, the high-voltage side voltages V_COMP_H and V_COIL_H are 12V. In the comparison circuit 310_1, the voltage across the relay coil is 12-52=-40(V), but the voltage across the relay coil 210 according to the present embodiment is 12-12.5=-0.5(V). Therefore, in the embodiment, since the reverse voltage is smaller than the reverse voltage of the comparison circuit 310_1, a smaller back EMF due to the reverse voltage can be generated.

[0097] In this way, the protection circuit 310 greatly reduces the back EMF generated in the relay coil 210, thereby being able to provide sufficient protection for the high-side switch HS and / or the low-side switch LS.

[0098] Although the embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art to which the present disclosure belongs belong to the scope of the present disclosure.

Claims

1. A battery system, comprising: Battery pack; a relay connected to one of the two terminals of the battery pack and including a relay coil; as well as a battery management system (BMS), the BMS being connected to the relay coil to control the operation of the relay, Wherein, the BMS comprises: a protection circuit that applies a voltage to the relay coil to operate the relay and includes a capacitor connected in parallel with the relay coil; and A main control unit (MCU) sends a control signal for controlling the operation of the relay to the protection circuit and diagnoses the operation of the protection circuit based on a voltage signal received from the protection circuit.

2. The battery system according to claim 1, wherein: The protection circuit comprises: a first switch, wherein the first switch applies a driving voltage to a high voltage side of the relay coil; a second switch connecting ground to the low voltage side of the relay coil; and A Schottky diode is connected in parallel with the relay coil and has a positive terminal connected to the high voltage side of the relay coil and a negative terminal connected to the low voltage side of the relay coil.

3. The battery system according to claim 2, wherein: The BMS further comprises: a first ADC, the first ADC generating a first voltage measurement signal by performing analog-to-digital conversion on a signal corresponding to the high-voltage side voltage of the relay coil; and A second ADC is provided, wherein the second ADC generates a second voltage measurement signal by performing analog-to-digital conversion on a signal corresponding to the low-voltage side voltage of the relay coil.

4. The battery system according to claim 3, wherein: The MCU determines whether the protection circuit is in a normal state based on the first voltage measurement signal and the second voltage measurement signal.

5. The battery system according to claim 4, wherein: The MCU monitors the first voltage measurement signal and the second voltage measurement signal to derive a first voltage value representing the voltage across the relay coil when the first switch and the second switch are in an on state, derive a second voltage value representing the voltage across the relay coil when the first switch or the second switch is in an off state, measures a back electromotive force (EMF) of the relay coil based on the first voltage value and the second voltage value, and determines whether the protection circuit is in the normal state based on the back EMF.

6. A relay anti-EMF protection circuit, the relay anti-EMF protection circuit comprising: a first switch that applies a driving voltage to a high voltage side of a relay coil included in the relay; a second switch connecting ground to the low voltage side of the relay coil; a capacitor connected in parallel with the relay coil; as well as A Schottky diode having a positive terminal connected to the high voltage side of the relay coil and a negative terminal connected to the low voltage side of the relay coil.

7. The protection circuit according to claim 6, further comprising: a first resistor and a second resistor, the first resistor and the second resistor being connected in series to the high voltage side of the relay coil; a diode having a negative terminal to which a voltage is applied and a positive terminal connected to one terminal of a third resistor, the other terminal of the third resistor being connected to the low voltage side of the relay coil; as well as a fourth resistor and a fifth resistor, the fourth resistor and the fifth resistor being connected in series to the low voltage side of the relay coil, and A signal representing a voltage corresponding to a high-voltage side voltage of the relay coil is output from a node between the first resistor and the second resistor, and a signal representing a voltage corresponding to a low-voltage side voltage of the relay coil is output from a node between the fourth resistor and the fifth resistor.

8. A protection circuit monitoring method for preventing back EMF of a relay, the protection circuit monitoring method comprising the following steps: A main control unit (MCU) switches on a high-voltage side switch connected to a high-voltage side of a relay coil included in the relay and a low-voltage side switch connected to a low-voltage side of the relay coil; The MCU receives two first signals from the protection circuit; The MCU derives a first voltage value based on the two first signals, wherein the first voltage value represents the voltage across the relay coil when the high-voltage side switch and the low-voltage side switch are in an on state; The MCU disconnects the high-voltage side switch or the low-voltage side switch; The MCU receives two second signals from the protection circuit; The MCU derives a second voltage value based on the two first signals, wherein the second voltage value represents the voltage across the relay coil when the high-voltage side switch and the low-voltage side switch are in an off state; as well as The operation of the protection circuit is diagnosed by the MCU based on the first voltage value and the second voltage value.

9. The method according to claim 8, wherein: The protection circuit comprises: a capacitor connected in parallel with the relay coil; and A Schottky diode is connected in parallel with the relay coil and has a positive terminal connected to the high voltage side of the relay coil and a negative terminal connected to the low voltage side of the relay coil.

10. The method according to claim 8, wherein: The step of diagnosing, by the MCU, the operation of the protection circuit based on the first voltage value and the second voltage value comprises the following steps: The back EMF of the relay coil is measured based on the first voltage value and the second voltage value, and whether the protection circuit is in a normal state is determined based on the back EMF.

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