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

Abstract

The present invention relates to a battery system, a relay reverse electromotive force protection circuit, and a protection circuit monitoring method. The battery system includes a battery pack, a relay including a relay coil connected to one end of both ends of the battery pack, and a battery management system (BMS, Battery Management System) connected to the relay coil to control the operation of the relay. The BMS includes a main control unit (MCU, Main Control Unit) that applies a voltage to the relay coil to operate the relay, a protection circuit including a capacitor connected in parallel with the relay coil, and transmits 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.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0183572, filed on December 23, 2022, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] This disclosure relates to a battery system, a relay back - electromotive - force protection circuit, and a protection - circuit monitoring method.

Background Art

[0003] A mechanical relay may be composed of a coil and a contactor. When the power supply applied to the coil to drive the relay is turned off to stop driving the relay, a back - electromotive force is generated in the coil. The back - electromotive force is a phenomenon generated due to the current characteristics of the relay coil.

[0004] If such a back - electromotive force is generated excessively, a failure may occur in the relay driver that drives the relay.

Summary of the Invention

Problems to be Solved by the Invention

[0005] To provide a battery system, a relay back - electromotive - force protection circuit, and a protection - circuit monitoring method that prevent back - electromotive force by including a protection circuit for preventing back - electromotive force generated in a relay in a battery system and can diagnose whether the protection circuit operates normally.

Means for Solving the Problems

[0006] A battery system according to one feature of the invention includes a battery pack, a relay connected to one end of both ends 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. The BMS includes applying a voltage to the relay coil to operate the relay, a protection circuit including a capacitor connected in parallel with the relay coil, and a main control unit (MCU) that transmits 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.

[0007] The protection circuit may further include a first switch for applying a driving voltage to the high side of the relay coil, a second switch for connecting ground to the low side of the relay coil, and a Schottky diode connected in parallel with the relay coil, having a cathode end connected to the high side of the relay coil and an anode end connected to the low side of the relay coil.

[0008] The BMS may further include a first ADC that performs analog-to-digital conversion on a signal corresponding to the high-side voltage of the relay coil to generate a first voltage measurement signal, and a second ADC that performs analog-to-digital conversion on a signal corresponding to the low-side voltage of the relay coil to generate a second voltage measurement signal.

[0009] The MCU can determine whether the protection circuit is in a normal state based on the first voltage measurement signal and the second voltage measurement signal.

[0010] The MCU monitors the first voltage measurement signal and the second voltage measurement signal to derive a first voltage value indicating the voltage across the relay coil in the on state of the first switch and the second switch, and derives a second voltage value indicating the voltage across the relay coil in the off state of the first switch or the second switch. Based on the first voltage value and the second voltage value, the back electromotive force of the relay coil is measured, and based on the back electromotive force, it can be determined whether the protection circuit is in a normal state.

[0011] The protection circuit according to another feature of the invention is a back electromotive force protection circuit of a relay, including a first switch for applying a driving voltage to the high side of the relay coil included in the relay, a second switch for connecting the ground to the low side of the relay coil, a capacitor connected in parallel with the relay coil, and a Schottky diode whose cathode terminal is connected to the high side of the relay coil and whose anode terminal is connected to the low side of the relay coil.

[0012] The protection circuit further includes a first resistor and a second resistor connected in series to the high side of the relay coil, a diode having a voltage applied to its anode terminal and one end of a third resistor connected to its cathode terminal - the other end of the third resistor is connected to the low side of the relay coil -, and a fourth resistor and a fifth resistor connected in series to the low side of the relay coil. A signal indicating a voltage corresponding to the high side voltage of the relay coil can be output from the node between the first resistor and the second resistor, and a signal indicating a voltage corresponding to the low side voltage of the relay coil can be output from the node between the fourth resistor and the fifth resistor.

[0013] A method for monitoring a protection circuit according to another feature of the invention is a method for monitoring a protection circuit for preventing the back electromotive force of a relay. The main control unit (MCU, Main Control Unit) turns on a high-side switch connected to the high side of the relay coil included in the relay and a low-side switch connected to the low side of the relay coil. The MCU receives two first signals from the protection circuit. The MCU derives a first voltage value indicating the voltage across the relay coil in the on state of the high-side switch and the low-side switch based on the two first signals. The MCU turns off the high-side switch or the low-side switch. The MCU receives two second signals from the protection circuit. The MCU derives a second voltage value indicating the voltage across the relay coil in the off state of the high-side switch and the low-side switch based on the two second signals. And the MCU diagnoses the operation of the protection circuit based on the first voltage value and the second voltage value.

[0014] 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, with the cathode terminal connected to the high side of the relay coil and the anode terminal connected to the low side of the relay coil.

[0015] The step in which the MCU diagnoses the operation of the protection circuit based on the first voltage value and the second voltage value may further include measuring the back electromotive force 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 electromotive force.

Advantages of the Invention

[0016] According to the embodiments of the present invention, the back electromotive force generated in the relay coil can be reduced, and the back electromotive force can be discharged quickly.

[0017] According to an embodiment of the present invention, it is possible to protect a driver that drives a relay coil by reducing a back electromotive force from being destroyed by an excessive back electromotive force.

[0018] According to an embodiment of the present invention, it is possible to monitor the voltage across both ends of a relay coil from a protection circuit for preventing a back electromotive force and determine whether the protection circuit operates normally.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the attached drawings. The same or similar reference numerals are assigned to the same or similar components, and redundant descriptions thereof are omitted. The suffixes "module" and / or "section" for the components used in the following description are given or mixed only for the ease of preparing the specification, and do not have meanings or roles that are distinct from each other by themselves. Further, when explaining the embodiments disclosed in this specification, if it is determined that a specific description of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof is omitted. Also, the attached drawings are only for facilitating the understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the attached drawings, and it should be understood that all modifications, equivalents, or alternatives included in the idea and technical scope of the present invention are included.

[0021] Terms including ordinal numbers such as first, second, etc. can be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

[0022] In this application, terms such as "including" or "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude in advance the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0023] Among the configurations according to an embodiment, in a configuration that controls other configurations under specific control conditions, a program embodied by a set of instruction words that embody the control algorithm necessary to control the other configurations may be installed. The control configuration can process input data and stored data by the installed program to generate output data. The control configuration can include a non-volatile memory for storing the program and a memory for storing data.

[0024] Figure 1 is a block diagram schematically showing a battery system according to an embodiment.

[0025] Referring to Figure 1, the battery system 1 can include a battery pack 100, a relay 200, and a battery management system (BMS) 300.

[0026] The battery pack 100 can include a plurality of battery cells. The battery pack 100 can be embodied as two or more battery cells connected in series, a plurality of battery cells each having two or more battery cells connected in parallel and connected in series, or two or more battery cells connected in parallel.

[0027] The relay 200 can include a relay coil 210. One end of the relay 200 can be connected to one of both ends of the battery pack 100. The other end of the relay 200 can be connected to the external device 2.

[0028] The battery system 1 can be connected to the external device 2. The external device 2 can include loads such as an inverter and a converter, and a charging device. When the external device 2 is a charger, both ends P+ and P- of the battery system 1 can be connected to the charger to receive power supply from the charger and be charged. When the external device 2 is a load, both ends P+ and P- of the battery system 1 can be connected to the load so that the power supplied by the battery pack 100 can be discharged through the load.

[0029] Although Figure 1 shows that the relay 200 is only included between the positive terminal + of the battery pack 100 and the terminal P+ of the battery system 1, the invention is not limited thereto. The battery system 1 can also include a relay between the negative terminal - of the battery pack 100 and the terminal P- of the battery system 1, and the relay back electromotive force protection circuit described later can be similarly applied to the relay between the negative terminal - and the terminal P- of the battery system 1.

[0030] The BMS 300 can determine whether a protection circuit that operates the relay coil 210 and reduces the back electromotive force of the relay coil 210 operates within a normal range. The BMS 300 can include a relay back electromotive force protection circuit (hereinafter, referred to as "protection circuit") 310, a main control unit (MCU, Main Control Unit), and analog-to-digital converters (ADCs) ADC1 and ADC2.

[0031] The protection circuit 310 can be a circuit that discharges the back electromotive force that may be generated due to the characteristics of the relay coil 210. The protection circuit 310 can 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 can apply a voltage to the relay coil 210 by means of the high-side control signal HCS and the low-side control signal LSC to operate the relay 200. When the voltage applied to the relay coil 210 disappears due to a switching operation, a reverse voltage may be applied across the relay coil 210. The protection circuit 310 can reduce the reverse voltage generated across the relay coil 210. Also, the protection circuit 310 can provide a discharge path so that the back electromotive force is quickly discharged. The protection circuit 310 can generate a high-side signal HSS corresponding to the voltage on the high-side of the relay coil 210 and transmit it to the first analog-to-digital converter ADC1, and generate a low-side signal LSS corresponding to the voltage on the low-side of the relay coil 210 and transmit it to the second analog-to-digital converter ADC2.

[0032] The first analog-to-digital converter ADC1 can generate a voltage measurement signal VS1 obtained by analog-to-digital converting the high-side signal HSS and transmit it to the MCU 320. The second analog-to-digital converter ADC2 can generate a voltage measurement signal VS2 obtained by analog-to-digital converting the low-side signal LSS and transmit it to the MCU 320.

[0033] The MCU 320 can include terminal P1 and terminal P2. The MCU 320 can receive a voltage measurement signal VS1 from a first analog-to-digital converter ADC1 through terminal P1. The MCU 320 can receive a voltage measurement signal VS2 from a second analog-to-digital converter ADC2 through terminal P2. The MCU 320 can derive the high-side voltage value V_COIL_H of the relay coil 210 based on the voltage measurement signal VS1. The MCU 320 can derive the low-side voltage value V_COIL_L of the relay coil 210 based on the voltage measurement signal VS2.

[0034] When the back electromotive force is excessively generated, it may lead to the destruction of the driver beyond the limit of the relay driver that drives the relay 200. Therefore, the protection circuit 310 can operate as an absorber of the back electromotive force to prevent driver destruction.

[0035] The MCU 320 can generate a high-side control signal HCS and a low-side control signal LSC and transmit them to the protection circuit 310 to control the driving of the protection circuit 310. The MCU 320 can monitor the voltage across the relay coil 210 based on the voltage measurement signal VS1 and the voltage measurement signal VS2, and can determine whether the protection circuit 310 operates within the normal range based on the monitoring result. The voltage measurement signal VS1 can indicate a value corresponding to the high-side (one end) voltage of the relay coil 210, and the voltage measurement signal VS2 can indicate a value corresponding to the low-side (the other end) voltage of the relay coil 210.

[0036] Hereinafter, with reference to FIG. 2, the operation of the protection circuit 310 will be examined.

[0037] FIG. 2 is a circuit diagram of the protection circuit of FIG. 1.

[0038] Referring to FIG. 2, the protection circuit 310 can 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 to R5, and a diode D1. The Schottky diode D_SCH, the capacitor C, and the relay coil 210 can be connected in parallel.

[0039] The high-side control signal HCS can control the opening and closing of the high-side switch HS. The low-side control signal LCS can control the opening and closing of the low-side switch LS. The high-side switch HS can be a switch inside a high-side driver connected to the high side of the relay coil 210. The low-side switch LS can be a switch inside a low-side driver connected to the low side of the relay coil 210.

[0040] In FIG. 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 invention is not limited thereto. The high-side control signal HCS and the low-side control signal LCS can be transmitted to the corresponding drivers among a high-side driver (HSD, High Side Driver) and a low-side driver (LSD, Low Side Driver) respectively, and the HSD and LSD can also control the high-side switch HS and the low-side switch LS.

[0041] The high-side switch HS is connected to the high side of the relay coil 210 and can apply a driving voltage V1 to the relay coil 210. A voltage V1 can be applied to one end of the high-side switch HS. For example, the voltage V1 can be a 12V voltage supplied from an auxiliary terminal (AUX) of the vehicle. The cathode end of the Schottky diode D_SCH, one end of the capacitor C, one end of the relay coil 210, and one end of the resistor R1 can be connected to the other end of the high-side switch HS. One end of the resistor R2 can be connected to the other end of the resistor R1. The other end of the resistor R2 can be connected to the ground.

[0042] The high-side signal HSS can indicate the node N1 voltage between resistor R1 and resistor R2. The voltage indicated by the high-side signal HSS can be a voltage corresponding to the voltage at one end (high-side) of the relay coil 210.

[0043] The low-side switch LS is connected to the low side of the relay coil 210 and can connect the relay coil 210 to ground. One end of the low-side switch LS can be connected to ground. The other end of the low-side switch LS can be connected to the anode end of the Schottky diode D_SCH, the other end of the capacitor C, the other end of the relay coil 210, one end of the resistor R3, and one end of the resistor R4. A voltage V2 can be applied to the anode end of the diode D1. The cathode end of the diode D1 can be connected to the other end of the resistor R3. One end of the resistor R5 can be connected to the other end of the resistor R4. The other end of the resistor R5 can be connected to ground.

[0044] The low-side signal LSS can indicate the node N2 voltage between resistor R4 and resistor R5. The voltage indicated by the low-side signal LSS can be a voltage corresponding to the voltage at the other end (low-side) of the relay coil 210.

[0045] The MCU 320 can monitor the voltage measurement signals VS1 and VS2 received from the first analog-to-digital converter ADC1 and the second analog-to-digital converter ADC2. The MCU 320 can control the operations 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 monitoring.

[0046] The MCU320 can monitor the voltage measurement signal VS1 and the voltage measurement signal VS2 to derive a first voltage value indicating the voltage across both ends of the relay coil 210 in the on state of the high-side switch HS and the low-side switch LS. Further, the MCU320 can monitor the voltage measurement signal VS1 and the voltage measurement signal VS2 to derive a second voltage value indicating the voltage across both ends of the relay coil 210 in the off state of the high-side switch HS and / or the low-side switch LS. The MCU320 can measure the back electromotive force of the relay coil 210 based on the first voltage value and the second voltage value.

[0047] When the MCU320 generates an on-level high-side control signal HCS and an on-level low-side control signal LCS and transmits them 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 can be applied to the relay coil 210 and the coil current IL can flow. The relay 200 can be turned on by the magnetic field generated by the coil current IL. While the high-side switch HS and the low-side switch LS are closed, the capacitor C can store the charge due to the voltage across both ends of 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 indicate the voltage applied to one end of the resistor R2 after being divided by the resistors R1 and R2 from the voltage V1. In the on state of the high-side switch HS and the low-side switch LS, the voltage measurement signal VS2 can indicate the ground.

[0048] FIG. 3 is a circuit diagram of the protection circuit of FIG. 1 with the switch turned off.

[0049] Referring to FIG. 3, when the MCU 320 generates a high-side control signal HCS and a low-side control signal LCS at an off level and transmits them 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 switch from the on state to the off state, a reverse voltage can be applied across both ends of the relay coil 210. In this case, the voltage measurement signal VS1 is changed from a voltage with a positive polarity to a voltage indicating a negative polarity by the switching operation. When the high-side switch HS and the low-side switch LS are turned off, the voltage measurement signal VS2 can indicate the voltage applied to one end of the resistor R5 after being distributed by the resistors R3, R4, and R5 from the voltage V2.

[0050] Hereinafter, it will be described on the assumption that the voltage V1 and the voltage V2 are voltages with a positive polarity.

[0051] In the on state of the high-side switch HS and the low-side switch LS, since the voltage measurement signal VS1 indicates a higher voltage than the voltage measurement signal VS2, the high-side voltage of the relay coil 210 has a positive polarity and the low-side voltage has a negative polarity.

[0052] When the high-side switch HS and the low-side switch LS are turned off, since the voltage measurement signal VS1 indicates a lower voltage than the voltage measurement signal VS2, the high-side voltage of the relay coil 210 has a negative polarity and the low-side voltage has a positive polarity.

[0053] When the high-side switch HS and the low-side switch LS are opened, since voltage V1 is not applied to the relay coil 210, a reverse voltage is generated across the relay coil 210. A capacitor C is connected in parallel to the relay coil 210 to reduce the reverse voltage (v = -L * di / dt) generated across both ends of the relay coil. The capacitor C can increase the rate of change of time (dt). The rate of change of time means the time from when the voltage is cut off from the relay coil 210 until the coil current stops flowing. The period during which the coil current flows due to the voltage charged in the capacitor C becomes longer compared to when there is no capacitor C, and the rate of change of time can be increased. Then, the reverse voltage generated across both ends of the relay coil 210 can be reduced. Also, a Schottky diode D_SCH is connected in parallel to the relay coil 210 to quickly discharge the back electromotive force. The Schottky diode D_SCH forms a discharge path for discharging the back electromotive force generated in the relay coil 210 so that the back electromotive force can be quickly discharged.

[0054] In one embodiment, in the protection circuit 310, the capacitor C and the Schottky diode D_SCH can be connected in parallel to the relay coil 210 to prevent excessive back electromotive force from being generated in the relay coil. If excessive back electromotive force is generated, the high-side switch HS and / or the low-side switch LS may be damaged, and this is to prevent that.

[0055] Hereinafter, a protection circuit monitoring method using the battery system 1 according to one embodiment will be described with reference to FIG. 4.

[0056] FIG. 4 is a flowchart of a protection circuit monitoring method according to one embodiment.

[0057] The MCU 320 can generate an on-level high-side control signal HCS and a low-side control signal LCS and transmit them to the protection circuit 310 (S1). The high-side switch HS and the low-side switch LS that receive the on-level high-side control signal HCS and the low-side control signal LCS can be turned on.

[0058] When the high-side switch HS and the low-side switch LS are closed, the MCU 320 can receive a voltage measurement signal VS1 and a voltage measurement signal VS2 from the first analog-to-digital converter ADC1 and the second analog-to-digital converter ADC2 (S2).

[0059] The MCU 320 can derive a first voltage value based on the voltage measurement signal VS1 and the voltage measurement signal VS2 (S3). The first voltage value can indicate the voltage across the relay coil 210 in the on state of the high-side switch HS and the low-side switch LS. The MCU 320 can derive a high-side voltage value V_COIL_H and a low-side voltage value V_COIL_L based on the voltage measurement signal VS1 and the voltage measurement signal VS2, and can derive the first voltage value based on the high-side voltage value V_COIL_H and the low-side voltage value V_COIL_L.

[0060] The MCU 320 can generate an off-level high-side control signal HCS and / or a low-side control signal LCS and transmit them to the protection circuit 310 (S4).

[0061] When the high-side switch HS and / or the low-side switch LS are opened, the MCU 320 can receive a voltage measurement signal VS1 and a voltage measurement signal VS2 from the first analog-to-digital converter ADC1 and the second analog-to-digital converter ADC2 (S5).

[0062] The MCU320 can derive a second voltage value based on the voltage measurement signal VS1 and the voltage measurement signal VS2 (S6). The second voltage value can indicate the voltage across both ends of the relay coil 210 in the off state of the high-side switch HS and the low-side switch LS. The MCU320 can derive the high-side voltage value V_COIL_H and the low-side voltage value V_COIL_L based on the voltage measurement signal VS1 and the voltage measurement signal VS2, and can derive the second voltage value based on the high-side voltage value V_COIL_H and the low-side voltage value V_COIL_L.

[0063] The MCU320 can determine whether the protection circuit 310 is in a normal state based on the first voltage value and the second voltage value (S7). The MCU320 monitors the first voltage value and the second voltage value to measure the back electromotive force of the relay coil 210 when the high-side switch HS and the low-side switch LS are switched from the on state to the off state. When the magnitude of the back electromotive force is below a predetermined critical level, the MCU320 can determine that the protection circuit 310 is in a normal state.

[0064] Hereinafter, the operation of an embodiment will be described with reference to the comparative example of FIG. 5.

[0065] FIG. 5 is an exemplary diagram of a comparative circuit including a TVS diode and a Schottky diode.

[0066] The comparative circuit 310_1 shown in FIG. 5 is an example of a protection circuit for a relay coil. A Schottky diode and a TVS diode are connected in series and do not include a capacitor. The switch connected to the high side of the relay coil in the comparative circuit 310_1 is defined as the high-side switch C_HS, and the switch connected to the low side of the relay coil is defined as the low-side switch C_LS. In the comparative circuit 310_1, the high-side voltage of the relay coil is described as the high-side voltage V_COMP_H, and the low-side voltage of the relay coil is described as the low-side voltage V_COMP_L.

[0067] Hereinafter, with reference to FIGS. 6 and 7, when the high-side switch and the low-side switch are closed and then the high-side switch is opened, the change in the high-side voltage V_COMP_H of the relay coil connected to the comparison circuit 310_1 in FIG. 5 and the high-side voltage V_COIL_H of the relay coil 210 by the protection circuit 310 according to one embodiment will be described.

[0068] FIG. 6 is a graph of the high-side voltage of the relay coil connected to the comparison circuit of FIG. 5.

[0069] In FIG. 6, from time T = 0 to time T1, the high-side switch C_HS is open and the low-side switch C_LS is closed. The high-side voltage V_COMP_H of the relay coil connected to the comparison circuit 310_1 during the period from time T = 0 to time T1 can indicate 0V.

[0070] When the high-side switch C_HS is closed at time T1, the voltage V_COMP_H can indicate 12V. From time T1 to time T2, the high-side switch C_HS and the low-side switch C_LS are closed, and the voltage V_COMP_H can indicate 12V.

[0071] When the high-side switch C_HS is opened at time T2, a back electromotive force is generated in the relay coil, and the voltage V_COMP_H drops to -40V and can indicate 0V after time T2.

[0072] FIG. 7 is a graph of the high-side voltage of the relay coil according to one embodiment.

[0073] In FIG. 7, from time T = 0 to time T3, the high-side switch HS is open and the low-side switch LS is closed. The high-side voltage value V_COIL_H of the relay coil 210 according to one embodiment during the period from time T = 0 to time T3 can indicate 0V.

[0074] When the high-side switch HS is closed at time T3, the voltage value V_COIL_H can indicate 12V. From time T3 to time T4, the high-side switch HS and the low-side switch LS are closed, and the voltage value V_COIL_H can indicate 12V.

[0075] When the high-side switch HS is opened at time T4, a back electromotive force is generated in the relay coil 210 and the voltage value V_COIL_H drops to -0.5V, and after time T4, it can indicate 0V.

[0076] Referring to FIGS. 6 and 7, when the high-side switch is turned off, the high-side voltage V_COMP_H of the relay coil connected to the comparison circuit 310_1 drops to -40V, but the high-side voltage V_COIL_H of the relay coil 210 connected to the protection circuit 310 according to an embodiment only drops to -0.5V. When the low-side switch LS is closed, the low-side voltages V_COMP_L and V_COIL_L can be described by assuming they are 0V. The voltage across both ends of the relay coil in the comparison circuit 310_1 is (-40)-0 = -40 (V), but the voltage across both ends of the relay coil 210 according to an embodiment is (-0.5)-0 = -0.5 (V). Therefore, since the reverse voltage is less in one embodiment compared to the comparison circuit 310_1, less back electromotive force due to the reverse voltage can be generated.

[0077] Hereinafter, with reference to FIGS. 8 and 9, when the high-side switch and the low-side switch are closed and then the low-side switch is opened, the change in the low-side voltage V_COMP_L of the relay coil connected to the comparison circuit 310_1 in FIG. 5 and the low-side voltage V_COIL_L of the relay coil 210 by the protection circuit 310 according to an embodiment will be described.

[0078] FIG. 8 is a graph of the low-side voltage of the relay coil connected to the comparison circuit in FIG. 5.

[0079] In FIG. 8, from time T = 0 to time T5, the high-side switch C_HS and the low-side switch C_LS are closed. During the period from time T = 0 to time T5, the low-side voltage V_COMP_L of the relay coil connected to the comparison circuit 310_1 can be shown to be 0V.

[0080] When the low-side switch C_LS is opened at time T5, a back electromotive force is generated in the relay coil and the voltage V_COMP_L rapidly rises to 52V, and after time T5, it can be shown to be 12V.

[0081] FIG. 9 is a graph of the low-side voltage of the relay coil according to an embodiment.

[0082] In FIG. 9, from time T = 0 to time T6, the high-side switch HS and the low-side switch LS are closed. During the period from time T = 0 to time T6, the low-side voltage value V_COIL_L of the relay coil 210 according to an embodiment can be shown to be 0V.

[0083] When the low-side switch LS is opened at time T6, a back electromotive force is generated in the relay coil 210 and the voltage V_COMP_L rapidly rises to 12.5V, and after time T6, it can be shown to be 12V.

[0084] Referring to FIGS. 8 and 9, when the low-side switch is turned off, the low-side voltage V_COMP_L of the relay coil connected to the comparison circuit 310_1 rapidly rises to 52V, but the low-side voltage V_COIL_L of the relay coil 210 connected to the protection circuit 310 according to an embodiment only rapidly rises to 12.5V. When the high-side switch HS is closed, the high-side voltages V_COMP_H and V_COIL_H can be described assuming they are 12V. The voltage across the relay coil in the comparison circuit 310_1 is 12 - 52 = -40 (V), but the voltage across the relay coil 210 according to an embodiment is 12 - 12.5 = -0.5 (V). Therefore, since the reverse voltage is less in one embodiment compared to the comparison circuit 310_1, less back electromotive force due to the reverse voltage can be generated.

[0085] In this way, since the protection circuit 310 significantly reduces the back electromotive force generated in the relay coil 210, sufficient protection for the high-side switch HS and / or the low-side switch LS is possible.

[0086] Although the embodiments of the present invention have been described in detail above, the scope of the rights of the present invention is not limited thereto, and forms variously modified and improved by those having ordinary knowledge in the field to which the present invention pertains also belong to the scope of the rights of the present invention.

Claims

1. A battery pack; A relay connected to one end of both ends of the battery pack and including a relay coil; and A battery management system (BMS) connected to the relay coil and controlling the operation of the relay, The BMS includes A protection circuit including a capacitor connected in parallel with the relay coil and applying a voltage to the relay coil to operate the relay, and A main control unit (MCU) that transmits 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. A battery system.

2. The protection circuit includes A first switch that applies a driving voltage to the high side of the relay coil; A second switch that connects ground to the low side of the relay coil; and A Schottky diode connected in parallel with the relay coil, having its cathode terminal connected to the high side of the relay coil and its anode terminal connected to the low side of the relay coil; Further including The battery system according to claim 1.

3. The BMS includes A first ADC that performs analog-to-digital conversion on a signal corresponding to the high-side voltage of the relay coil to generate a first voltage measurement signal; and A second ADC that performs analog-to-digital conversion on a signal corresponding to the low-side voltage of the relay coil to generate a second voltage measurement signal, further including The battery system according to claim 2.

4. 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. The battery system according to claim 3.

5. The MCU monitors the first voltage measurement signal and the second voltage measurement signal to derive a first voltage value indicating the voltage across the relay coil in the on state of the first switch and the second switch, and derives a second voltage value indicating the voltage across the relay coil in the off state of the first switch or the second switch, measures the back electromotive force of the relay coil based on the first voltage value and the second voltage value, and determines whether the protection circuit is in a normal state based on the back electromotive force. The battery system according to claim 4.

6. A back electromotive force protection circuit for a relay, comprising a first switch for applying a driving voltage to the high side of a relay coil included in the relay; a second switch for connecting ground to the low side of the relay coil; a capacitor connected in parallel with the relay coil; and a Schottky diode having a cathode terminal connected to the high side of the relay coil and an anode terminal connected to the low side of the relay coil protection circuit.

7. a first resistor and a second resistor connected in series to the high side of the relay coil; a diode having a voltage applied to its anode terminal and one end of a third resistor connected to its cathode terminal - the other end of the third resistor is connected to the low side of the relay coil -; and a fourth resistor and a fifth resistor connected in series to the low side of the relay coil further comprising outputs a signal indicating a voltage corresponding to the high side voltage of the relay coil from a node between the first resistor and the second resistor, and outputs a signal indicating a voltage corresponding to the low side voltage of the relay coil from a node between the fourth resistor and the fifth resistor The protection circuit according to claim 6.

8. A monitoring method for a protection circuit for preventing back electromotive force of a relay, comprising: A step in which a main control unit (MCU) turns on a high-side switch connected to the high side of a relay coil included in the relay and a low-side switch connected to the low side of the relay coil; A step in which the MCU receives two first signals from the protection circuit; A step in which the MCU derives a first voltage value indicating the voltage across the relay coil in the on state of the high-side switch and the low-side switch based on the two first signals; A step in which the MCU turns off the high-side switch or the low-side switch; A step in which the MCU receives two second signals from the protection circuit; A step in which the MCU derives a second voltage value indicating the voltage across the relay coil in the off state of the high-side switch and the low-side switch based on the two second signals; and A step in which the MCU diagnoses the operation of the protection circuit based on the first voltage value and the second voltage value A protection circuit monitoring method including the above steps.

9. The protection circuit includes: A capacitor connected in parallel with the relay coil; and A Schottky diode connected in parallel with the relay coil, having a cathode terminal connected to the high side of the relay coil and an anode terminal connected to the low side of the relay coil. The protection circuit monitoring method according to Claim 8.

10. The step in which the MCU diagnoses the operation of the protection circuit based on the first voltage value and the second voltage value further includes: Measuring the back electromotive force 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 electromotive force. The protection circuit monitoring method according to claim 8.

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