Battery pack voltage measurement circuit

Abstract

The present invention discloses a battery pack voltage measuring circuit including: a relay unit that controls measurement of a battery pack voltage; first and second branch units that are provided between a battery pack voltage input terminal and the relay unit and that branch the battery pack voltage to different paths depending on the battery pack voltage and apply the branched voltage to the relay unit; and a voltage distribution unit that distributes the battery pack voltage applied via the first or second branch unit and the relay unit and outputs the distributed voltage to an output terminal.

Description

[Technical Field]

[0001] The present invention relates to a circuit for measuring a battery pack voltage, and more particularly to a circuit for measuring a battery pack voltage that measures the voltage of a battery pack and outputs the resultant value. [Background technology]

[0002] Rechargeable secondary batteries, or batteries, are widely used as energy sources for mobile devices such as smartphones. Batteries are also used as energy sources for environmentally friendly vehicles, such as electric vehicles and hybrid electric vehicles, which are being considered as solutions to address air pollution caused by fossil fuel-based gasoline and diesel vehicles. Batteries are used in a wide variety of applications, and they are expected to be adopted in even more fields and products in the future.

[0003] Such batteries are generally used in the form of a battery pack rather than as a single battery cell. A battery pack includes at least one battery module, and a battery module may consist of multiple battery cells. In addition, battery packs with higher capacity and voltage specifications are being developed to meet consumer demands so that they can be used for longer periods of time and provide more powerful driving.

[0004] The high-voltage specification of a battery pack provides a stronger driving force to a power-consuming device, such as an electric vehicle, that uses the battery pack. However, because the internal characteristics and internal resistance of the battery cells constituting the battery pack vary, voltage variations may occur between the battery cells due to continuous charging and discharging of the high-voltage battery. If the voltage variations between the battery cells accumulate, the battery cells may be overcharged or overdischarged, potentially causing fatal damage to the high-voltage battery. Furthermore, if the lifespan or performance degradation of the battery cells constituting the battery pack is shortened, the performance of the battery pack may be degraded. Therefore, in order to monitor and manage the performance of the battery pack, it is necessary to accurately measure the battery pack voltage, which determines the performance of the battery pack. To this end, the battery pack is equipped with a battery pack voltage measurement circuit.

[0005] The battery pack voltage measurement circuit includes a relay switch and an analog-to-digital converting (ADC) output circuit, where the relay switch turns on / off based on the overcurrent, and the ADC output circuit measures the battery pack voltage according to the current flowing through the relay switch.

[0006] Recently, the voltage of battery packs used in electric vehicles has been increasing from 400V to 800V. Therefore, the circuit for measuring battery pack voltage must also be designed to accommodate the increased battery pack voltage. To achieve this, the relay switch incorporated in the circuit for measuring battery pack voltage must meet the 800V allowable voltage. However, a relay switch that operates stably at the 800V allowable voltage requires advanced process technology and high-quality materials, resulting in a very expensive relay switch, i.e., a high-specification relay switch. If a low-specification relay switch with an allowable voltage of 400V is used to measure the voltage of an 800V battery pack, there is a risk of delay in the relay switch's turn-off time, which could cause various problems.

[0007] To use a low-specification relay switch, a battery pack voltage measurement circuit can be constructed by connecting a low-specification relay switch and a relay resistor in parallel. That is, a first resistor, a relay circuit, a second resistor, and an ADC output circuit are connected in series between the power supply terminal and the ground terminal of the battery pack, and a relay element and a relay resistor are connected in parallel to the relay circuit to construct the battery pack voltage measurement circuit. This battery pack voltage measurement circuit has the advantage that a 400V rated relay switch can be used in an 800V battery pack by adding a relay resistor in parallel with the relay switch. However, there is a problem in that leakage current occurs through the relay resistor even when the relay switch is turned off. Furthermore, because the first and second resistors are set to a resistance ratio of 800V, there is a problem in that measurement accuracy decreases when measuring a 400V battery pack voltage, which generally has a higher resistance ratio.

[0008] The following documents are examples of related prior art: [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Republic of Korea Patent No. 10-2041869 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a battery pack voltage measurement circuit that can measure high voltages using a low specification relay switch.

[0011] The present invention provides a battery pack voltage measurement circuit that can prevent leakage current even when a low-spec relay switch is used. [Means for solving the problem]

[0012] A battery pack voltage measurement circuit according to one embodiment of the present invention includes a relay unit that starts measuring the battery pack voltage, first and second branch units that are provided between a battery pack voltage input terminal and the relay unit and branch the battery pack voltage into different paths depending on the battery pack voltage and apply the branched voltage to the relay unit, and a voltage distribution unit that distributes the battery pack voltage applied via the first or second branch unit and the relay unit and outputs the distributed voltage to an output terminal.

[0013] The first branch section includes a first resistor and a first switch connected in series between the battery pack voltage input terminal and the relay section.

[0014] The second branch section is connected in series between the battery pack voltage input terminal and the relay section, and includes a second resistor and a second switch connected in parallel with the first resistor and the first switch, respectively.

[0015] The relay unit includes a relay switch and a third resistor connected in parallel between the connection point of the first and second branches and the voltage dividing unit.

[0016] The device further includes a control unit that controls the first switch, the second switch, and the relay switch.

[0017] The control unit selectively opens and closes the first and second switches depending on the magnitude of the battery pack voltage.

[0018] A first resistance ratio, which is the ratio between the sum of the resistances of the voltage distribution units and the first resistance, and a second resistance ratio, which is the ratio between the sum of the resistances of the voltage distribution units and the second resistance, are set to be different from each other.

[0019] A battery pack voltage measurement circuit according to another aspect of the present invention includes a first branch section provided between a battery pack voltage input terminal and a first node, branching a first battery pack voltage; a second branch section provided between the battery pack voltage input terminal and the first node, connected in parallel with the first branch section, branching a second battery pack voltage; a relay section provided between the first node and a second node, which starts measuring the battery pack voltage in response to a switching operation; and a voltage distribution section provided between the second node and a ground terminal, which distributes the battery pack voltage applied via the first or second branch section and the relay section, and outputs the divided voltage to an output terminal.

[0020] The first branch includes a first resistor and a first switch connected in series between the battery pack voltage input terminal and the first node.

[0021] The second branch is connected in series between the battery pack voltage input terminal and the first node, and includes a second resistor and a second switch connected in parallel with the first resistor and the first switch, respectively.

[0022] The relay unit includes a relay switch and a third resistor connected in parallel between the first node and the second node.

[0023] The device further includes a control unit that controls the first switch, the second switch, and the relay switch.

[0024] The control unit selectively opens and closes the first and second switches depending on the magnitude of the battery pack voltage.

[0025] The first resistor and the second resistor have different resistance values. [Effects of the Invention]

[0026] The battery pack voltage measurement circuit according to the embodiment of the present invention can use a relay switch with low specifications, allowing for mass production at lower manufacturing costs. That is, by connecting a relay resistor in parallel with the relay switch, even when the relay switch is turned off by the relay resistor, only a low level of battery pack voltage, which is a portion of the battery pack voltage, is applied, which is an advantage of allowing a 400V rated relay to be used for a voltage of 800V, for example.

[0027] Furthermore, according to an embodiment of the present invention, the battery pack voltage is branched via the first and second branching units, making it possible to measure two different battery pack voltages. That is, the 400V battery pack voltage is branched via the first branching unit, and the 800V battery pack voltage is branched via the second branching unit, making it possible to measure a 400V or 800V battery pack voltage using a single battery pack voltage measurement circuit. Therefore, a single battery pack voltage measurement circuit can be used in a system employing a 400V battery pack and a system employing an 800V battery pack. This eliminates the need to develop measurement circuits for different battery pack voltages, thereby reducing product development costs.

[0028] According to the embodiment of the present invention, since the battery pack voltage measurement circuit can be controlled by the first and second switches of the first and second branches, leakage current through the relay resistor can be prevented even when the relay switch is turned off. That is, assuming that the first and second switches are not provided, leakage current may occur through the relay resistor when the relay switch is turned off. However, when the relay switch is turned off, the first and second switches are also maintained in the off state, so leakage current through the relay resistor can be prevented. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a circuit diagram of a measurement circuit for a battery pack voltage according to an embodiment of the present invention. [Figure 2] 3 is a circuit diagram showing a current flow for explaining a method of driving a battery pack voltage measuring circuit according to an embodiment of the present invention; FIG. [Figure 3] 3 is a circuit diagram showing a current flow for explaining a method of driving a battery pack voltage measuring circuit according to an embodiment of the present invention; FIG. [Figure 4] 3 is a circuit diagram showing a current flow for explaining a method of driving a battery pack voltage measuring circuit according to an embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The following embodiments are provided solely for the purpose of complete disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0031] FIG. 1 is a circuit diagram of a battery pack voltage measurement circuit according to an embodiment of the present invention.

[0032] 1, a battery pack voltage measurement circuit according to an embodiment of the present invention may include a first branch unit 100 connected between a battery pack voltage input terminal, i.e., a power supply terminal Vpack, and a ground terminal GND, a second branch unit 200, a relay unit 300, and a voltage dividing unit 400. More specifically, the battery pack voltage measurement circuit according to an embodiment of the present invention includes first and second branch units 100, 200 connected in parallel between the power supply terminal Vpack and a first node Q11, a relay unit 300 connected between the first node Q11 and a second node Q12, and a voltage dividing unit 400 connected between the second node Q12 and the ground terminal GND. Here, the first and second branch units 100, 200 set the path of a current input from the power supply terminal Vpack to a first and second path. The relay unit 300 includes a parallel-connected relay switch S13 and a relay resistor, i.e., a third resistor R13, and starts and stops measuring the battery pack voltage according to the on / off operation of the relay switch S13. The voltage divider 400 divides and outputs the voltage of the current input via the first path or the second path to measure the voltage output to the output terminal DEC. The battery pack voltage measuring circuit according to an embodiment of the present invention will be described in more detail below by component.

[0033] 1. First branch The first branch 100 is connected between the power supply terminal Vpack and a first node Q11 and is connected in parallel with the second branch 200. The first branch 100 may include a first resistor R11 and a first switch S11 connected in series between the power supply terminal Vpack and the first node Q11. That is, the first branch 100 is configured by connecting the first resistor R11 and the first switch S11 in series between the power supply terminal Vpack and the first node Q11. The first branch 100 is configured to allow a current to flow through a first path via the first branch 100 in accordance with the battery pack voltage. That is, when a first current corresponding to the first voltage is applied from the power supply terminal Vpack, the first branch 100 is driven so that a current flows through the first path via the first branch 100. Here, the first voltage of the battery pack may be 400 V. That is, when the battery pack voltage is 400V, the current flows through the first branch 100 .

[0034] The first switch S11 may be a field effect transistor (FET) driven in response to a first control signal CTRL1 from a control unit (not shown). When the battery pack voltage is a first voltage, i.e., 400V, the first control signal CTRL1 is generated, thereby driving the first switch S11 and allowing current to flow through the first branch 100. For example, when the battery pack voltage is 400V, the first control signal CTRL1 is output at a logic high level to drive the first switch S11. Needless to say, when the battery pack voltage is a second voltage higher than the first voltage, the first control signal CTRL1 is not generated, turning off the first switch S11. For example, when the battery pack voltage is 800V, the first control signal CTRL1 is output at a logic low level to turn off the first switch S11. In addition, the first branch 100 drops the battery pack voltage and applies it to the relay unit 300. That is, the first branch unit 100 drops the battery pack voltage of 400V by the first resistor R11 and applies it to the relay unit 300. Therefore, even if the battery pack voltage of 400V is applied to the power supply terminal Vpack, the voltage dropped by the first resistor R11 is applied to the relay unit 300.

[0035] Meanwhile, the battery pack voltage measurement circuit of the present invention applies a 400V voltage to the voltage divider 400 via the first branch 100, divides the voltage at, for example, 100:1, and outputs the divided voltage. Therefore, the first resistor R11 can have a resistance value that is a predetermined ratio to the fourth and fifth resistors R14 and R15 of the voltage divider 400. For example, if the fourth resistor R14 is 1 MΩ and the fifth resistor R15 is 20 kΩ, the first resistor R11 can have a resistance value of 1 MΩ. In this way, since the first resistor R11 has a resistance value that is a predetermined ratio to the fourth and fifth resistors R14 and R15, the 400V voltage via the first branch 100 can be divided at 100:1 and output to the output terminal DEC.

[0036] 2. Second branch The second branch 200 is connected between the power supply terminal Vpack and the first node Q11 and is connected in parallel with the first branch 100. The second branch 200 may include a second resistor R12 and a second switch S12 connected in series between the power supply terminal Vpack and the first node Q11. That is, the second branch 200 is configured by connecting the second resistor R12 and the second switch S12 in series between the power supply terminal Vpack and the first node Q11. The second branch 200 is configured to allow a current to flow through a second path via the second branch 200 in accordance with the battery pack voltage. That is, when a second current corresponding to the second voltage is applied from the power supply terminal Vpack, the second branch 200 is driven so that a current flows through the second path via the second branch 200. Here, the second voltage of the battery pack may be 800 V. That is, when the battery pack voltage is 800V, the current flows through the second branch 200 .

[0037] The second switch S12 may be a field-effect transistor (FET) driven in response to a second control signal CTRL2 from a control unit (not shown). When the battery pack voltage is a second voltage, i.e., 800V, the control unit generates the second control signal CTRL2, thereby driving the second switch S12 and allowing current to flow through the second branch unit 200. For example, when the battery pack voltage is 800V, the second control signal CTRL2 is output at a logic high level to drive the second switch S12. Needless to say, when the battery pack voltage is a first voltage lower than the second voltage, the second control signal CTRL2 is not generated, turning off the second switch S12. For example, when the battery pack voltage is 400V, the second control signal CTRL2 is output at a logic low level to turn off the second switch S12. In addition, the second branch unit 200 drops the battery pack voltage and applies it to the relay unit 300. That is, the second branch unit 200 drops the battery pack voltage of 800V using the second resistor R12 and applies it to the relay unit 300. Therefore, even if the battery pack voltage of 800V is applied to the power supply terminal Vpack, the voltage dropped by the second resistor R12 is applied to the relay unit 300.

[0038] Meanwhile, the battery pack voltage measurement circuit of the present invention applies 800V voltage to the voltage divider 400 via the second branch 200, divides it at a ratio of, for example, 200:1, and outputs the resulting voltage. Therefore, the second resistor R12 can have a resistance value that is a predetermined ratio to the fourth and fifth resistors R14 and R15 of the voltage divider 400. For example, if the fourth resistor R14 is 1 MΩ and the fifth resistor R15 is 20 kΩ, the second resistor R12 can have a resistance value of 3 MΩ. In this way, the first resistor R11 has a resistance value that is a predetermined ratio to the fourth and fifth resistors R14 and R15, so that the 800V voltage via the second branch 200 can be divided at a ratio of 200:1 and output to the output terminal DEC.

[0039] 3. Relay section The relay unit 300 is connected between the first node Q11 and the second node Q12. That is, the relay unit 300 is provided between the parallel-connected first and second branches 100 and 200 and the voltage dividing unit 400. The relay unit 300 may include a third switch, i.e., a relay switch S13, and a third resistor, i.e., a relay resistor R13. The relay switch S13 and the relay resistor R13 are connected in parallel between the first node Q11 and the second node Q13. The relay switch S13 is driven by a control signal (not shown) for measuring the battery pack voltage to provide the voltage via the first branch 100 or the second branch 200 to the voltage dividing unit 400. That is, when a control signal (not shown) for measuring the battery pack voltage is generated and applied to the relay switch S13, the relay switch S13 is turned on to provide the voltage via the first branch 100 or the second branch 200 to the voltage dividing unit 400.

[0040] Although not shown in detail in the drawings, the relay switch S13 may be composed of a solenoid and a switch. The relay switch S13 can be controlled to be turned on or off based on the magnetic force generated in the solenoid. In addition, a relay resistor R13 is connected in parallel with the relay switch S13, so that when the relay switch S13 is turned off, the voltage applied across the relay switch S13 is the same as the voltage applied across the relay resistor R13.

[0041] On the other hand, in the conventional technology without relay resistor R13, when relay switch S13 is turned off, most of the battery pack voltage is applied across relay switch S13. Therefore, when the battery pack voltage is high, for example, 800V, a high-rated relay may be required. However, in the present invention, by connecting relay resistor R13 in parallel with relay switch S13, even when relay switch S13 is turned off by relay resistor R13, only a low level of the battery pack voltage, which is a portion of the battery pack voltage, is applied. This has the effect of making it possible to use a 400V-rated relay for a voltage of 800V, for example. In other words, because the voltage dropped by first branch 100 or second branch 200 is applied to one side of relay switch S13, relay switch S13 can be designed as a low-spec relay element. The other side of the relay switch S13 is applied with the voltage dropped by the first branch 100 or the second branch 200 and the relay resistor R13, so that stable on / off operation can be ensured even if the relay switch S13 is used as a low-spec relay switch.

[0042] Furthermore, in the present invention, since the battery pack voltage measurement circuit can be controlled by the first and second switches S11 and S12 of the first and second branches 100 and 200, leakage current through the relay resistor R13 can be prevented even when the relay switch S13 is turned off. That is, assuming that the first and second switches S11 and S12 are not provided, leakage current may occur through the relay resistor R13 when the relay switch S13 is turned off. However, when the relay switch S13 is turned off, the first and second switches S11 and S12 are also maintained in the off state, so leakage current through the relay resistor R13 can be prevented.

[0043] On the other hand, the resistance value of the relay resistor R13 can be determined so as to satisfy the following formula 1.

[0044]

number

[0045] Equation 1 is a formula excluding the ADC output circuit, i.e., the fifth resistor R15. Here, R12, R13, and R14 are the resistance values ​​of the second resistor R12, the relay resistor R13, and the fourth resistor R14, respectively, and V lim is the allowable voltage value of the relay switch S13, and V o means the voltage value of the battery pack. Since the second resistor R12 of the second branch 200 is larger than the first resistor R11 of the first branch 100, the resistance value of the relay resistor R13 in Equation 1 is affected by the resistance value of the second resistor R12.

[0046] As is clear from Equation 1, the allowable voltage value V of the relay element S13 lim is the voltage value of the battery pack V o At this time, the battery pack voltage V o The voltage V of the battery pack is dropped by the resistance of the second resistor R12, the relay resistor R13, and the fourth resistor R14. o However, even if the voltage rises from 400V to 800V, if the resistance values ​​of the second resistor R12, the relay resistor R13, and the fourth resistor R14 are appropriately designed, the allowable voltage value V of the relay switch S13 can be lim Here, the voltage value of the battery pack V o Even if the voltage becomes 800V, the allowable voltage value V of the relay switch S13 lim is satisfied, the voltage V of the battery pack having a high voltage can be o This means that the voltage can be stably measured. Furthermore, when the relay switch S13 is turned off, a voltage dropped by the first resistor R11 or the second resistor R12 is applied to one end of the relay switch S13, and the same voltage as that applied to both ends of the relay resistor R13 is applied to both ends of the relay switch S13. Therefore, even if the relay switch S13 is used with low specifications, the relay switch S13 can be stably turned off.

[0047] As described above, using such a configuration and operation, the battery pack voltage measurement circuit according to the embodiment of the present invention provides an environment in which the relay switch S13 can be used with low specifications.

[0048] On the other hand, the resistance value of the relay resistor R13 is determined so as to satisfy the following formula 2.

[0049]

number

[0050] Equation 2 is a formula including the ADC output circuit, that is, the fifth resistor R13. Here, R12, R13, R14, and R15 are the resistance values ​​of the second resistor R12, the relay resistor R13, the fourth resistor R14, and the fifth resistor R15, respectively, and V lim is the allowable voltage value of the relay switch S13, and V o means the voltage value of the battery pack.

[0051] Similarly to Equation 1, Equation 2 also defines the allowable voltage value V of the relay switch S13. lim is the voltage value of the battery pack V o The battery pack voltage V o In Equation 2, a voltage drop occurs due to the resistance values ​​of the second resistor R12, the relay resistor R13, the fourth resistor R14, and the fifth resistor R15. In particular, Equation 2 expresses the voltage value V of the battery pack. o can be further controlled to be lower by the resistance value of the fifth resistor R15, which means that the voltage value V o Even if the voltage V of the relay switch S13 increases, lim This means that it can be included in

[0052] As described above, the battery pack voltage measurement circuit according to the embodiment of the present invention can use a low-spec relay switch S13, which allows for mass production at lower manufacturing costs. Furthermore, the present invention allows the battery pack voltage measurement circuit to be controlled by the first and second switches S11 and S12 of the first and second branches 100 and 200, so that leakage current through the relay resistor R13 can be prevented even when the relay switch S13 is turned off. That is, when the relay switch S13 is turned off, the first and second switches S11 and S12 are also maintained in the off state, preventing leakage current through the relay resistor R13.

[0053] 4. Voltage distribution section The voltage dividing unit 400 is connected between the second node Q12 and the ground terminal GND. The voltage dividing unit 400 divides and outputs the voltage of the current input via the first path or the second path to measure the voltage output at the output terminal DEC. That is, the voltage dividing unit 400 divides the battery pack voltage Vpack applied via the first branch unit 100 and the relay unit 300 and outputs it to the output terminal DEC, and divides the battery pack voltage Vpack applied via the second branch unit 200 and the relay unit 300 and outputs it to the output terminal DEC. In this case, the battery pack voltage applied via the first branch unit 100 is 400 V, and the battery pack voltage applied via the second branch unit 200 is 800 V. That is, the voltage dividing unit 400 divides the battery pack voltage of 400 V or 800 V and outputs it to the output terminal DEC.

[0054] The voltage divider 400 may include fourth and fifth resistors R14 and R15 connected in series between the second node Q12 and the ground terminal GND. An output terminal DEC is provided between the fourth and fifth resistors R14 and R15. That is, the fourth resistor R14 is connected between the second node Q12 and the output terminal DEC, and the fifth resistor R15 is connected between the output terminal DEC and the ground terminal GND, forming the voltage divider 400. The voltage divider 400 divides the battery pack voltage through the fourth and fifth resistors R14 and R15 and outputs the divided voltage to the output terminal DEC. A capacitor C11 connected in parallel with the fifth resistor R15 is provided at the output terminal DEC. The fourth and fifth resistors R14 and R15 may have predetermined resistance values. That is, the fourth and fifth resistors R14 and R15 may have resistance values ​​that are in a predetermined ratio to the resistance values ​​of the first and second resistors R11 and R12. For example, the fourth resistor R14 may have a resistance of 1 MΩ, and the fifth resistor R15 may have a resistance of 20 kΩ. In this case, the first resistor R11 may have a resistance of 1 MΩ, and the second resistor R12 may have a resistance of 3 MΩ. In this way, the fourth and fifth resistors have resistance values ​​in a predetermined ratio to the resistance values ​​of the first and second resistors R11 and R12, respectively, so that the 400 V voltage through the first branch 100 can be divided at a ratio of 100:1, and the 800 V voltage through the second branch 200 can be divided and output to the output terminal DEC.

[0055] As described above, the battery pack voltage measurement circuit according to the embodiment of the present invention can use a low-specification relay switch S13, thereby enabling mass production of the battery pack voltage measurement circuit at even lower manufacturing costs. That is, by connecting the relay resistor R13 in parallel with the relay switch S13, even when the relay switch S13 is turned off by the relay resistor R13, only a low level of the battery pack voltage, which is a portion of the battery pack voltage, is applied. For example, a 400V rated relay can be used for 800V. Furthermore, because the battery pack voltage measurement circuit can be controlled by the first and second switches S11 and S12 of the first and second branches 100 and 200, leakage current through the relay resistor R13 can be prevented even when the relay switch S13 is turned off. That is, assuming that the first and second switches S11 and S12 are not provided, when the relay switch S13 is turned off, leakage current may occur through the relay resistor R13. However, when the relay switch S13 is turned off, the first and second switches S11 and S12 are also maintained in the off state, so leakage current through the relay resistor R13 can be prevented. In addition, in the present invention, the battery pack voltage is branched through the first and second branch units 100 and 200, so it is possible to measure two different battery pack voltages. That is, a 400V battery pack voltage is branched through the first branch unit 100, and an 800V battery pack voltage is branched through the second branch unit 200, so it is possible to measure a 400V or 800V battery pack voltage using a single battery pack voltage measurement circuit. Therefore, one battery pack voltage measurement circuit can be used in a system employing a 400V battery pack and a system employing an 800V battery pack, which eliminates the need to develop measurement circuits for different battery pack voltages, thereby reducing product development costs.

[0056] 2 to 4 are circuit diagrams showing current flows to explain a method of driving a circuit for measuring a battery pack voltage according to an embodiment of the present invention. That is, Fig. 2 is a circuit diagram showing current flows when the battery pack voltage is 400 V, Fig. 3 is a circuit diagram showing current flows when the battery pack voltage is 800 V, and Fig. 4 is a circuit diagram to explain a driving method when the switch is turned off.

[0057] Referring to FIG. 2 , to measure the battery pack voltage, a relay switch S13 can be turned on by a predetermined control signal. At this time, a control unit (not shown) can output a first control signal CTRL1 or a second control signal CTRL2 according to the battery pack voltage. For example, if the battery pack voltage is 400 V, the first control signal CTRL1 can be output at a high level and the second control signal CTRL2 can be output at a low level. When the first switch S11 is turned on by the high-level first control signal CTRL1, a current corresponding to the battery pack voltage flows through the first path, i.e., the first branch unit 100. That is, when the first control signal is applied at a high level, the battery pack voltage of 400 V is applied to the relay unit 300 via the first path and then to the voltage dividing unit 400. At this time, a voltage drop occurs as the voltage passes through the first branch unit 100 and the relay unit 300, and the voltage dividing unit 400 divides the dropped battery pack voltage and outputs it to the output terminal DEC. Meanwhile, the first resistor R11, the fourth resistor R14, and the fifth resistor R15 have predetermined resistance values, such that the battery pack voltage is dropped, for example, at a ratio of 100:1 and output to the output terminal DEC. To drop the 400V battery pack voltage at approximately 100:1, the first, fourth, and fifth resistors R11, R14, and R15 may have resistance values ​​of 1 MΩ, 1 MΩ, and 20 kΩ, respectively. As a result, the 400V battery pack voltage is dropped and distributed via the first branch unit 100, the relay unit 300, and the voltage dividing unit 400 before being output to the output terminal DEC. The output value of the output terminal DEC can be input to an analog-to-digital converter in a control unit (not shown), i.e., a microcontroller unit (MCU).

[0058] Referring to FIG. 3 , to measure the battery pack voltage, a relay switch S13 can be turned on by a predetermined control signal. At this time, a control unit (not shown) can output a first control signal CTRL1 or a second control signal CTRL2 according to the battery pack voltage. For example, if the battery pack voltage is 800 V, the second control signal CTRL2 can be output at a high level and the first control signal CTRL1 can be output at a low level. When the second switch S12 is turned on by the high-level second control signal CTRL2, a current corresponding to the battery pack voltage flows through the second path, i.e., the second branch unit 200. That is, when the second control signal is applied at a high level, the battery pack voltage of 800 V is applied to the relay unit 300 via the second path and then to the voltage dividing unit 400. At this time, a voltage drop occurs as the voltage passes through the second branch unit 200 and the relay unit 300, and the voltage dividing unit 400 divides the dropped battery pack voltage and outputs it to the output terminal DEC. Meanwhile, the second resistor R12, the fourth resistor R14, and the fifth resistor R15 have predetermined resistance values, so that the battery pack voltage is dropped, for example, by 200:1 and output to the output terminal DEC. To output an 800V battery pack voltage dropped by approximately 200:1, the second, fourth, and fifth resistors R12, R14, and R15 may have resistance values ​​of 3 MΩ, 1 MΩ, and 20 kΩ, respectively. As a result, the 800V battery pack voltage is dropped and distributed via the second branch unit 200, the relay unit 300, and the voltage dividing unit 400 and output to the output terminal DEC. The output value of the output terminal DEC can be input to an analog-to-digital converter of a control unit (not shown), i.e., a microcontroller unit (MCU).

[0059] Referring to FIG. 4, when the battery pack voltage is not being measured, the relay switch S13 can be turned off by a predetermined control signal. At this time, a control unit (not shown) can output the first and second control signals CTRL1 and CTRL2 in a low state by turning off the relay switch S13. Therefore, the first and second switches S11 and S12 can be turned off. In this way, by turning off both the relay switch S13 and the first and second switches S11 and S12, leakage current through the relay resistor R13 can be prevented. That is, assuming the first and second switches S11 and S12 are not provided, leakage current may occur through the relay resistor R13 when the relay switch S13 is turned off. However, when the relay switch S13 is turned off, the first and second switches S11 and S12 are also maintained in an off state, preventing leakage current from occurring through the relay resistor R13.

[0060] Although the technical concept of the present invention has been specifically described based on the above-mentioned embodiment, it should be noted that the above-mentioned embodiment is for the purpose of explanation and not for the purpose of limitation. It should be understood that a person skilled in the art of the present invention can implement various embodiments within the scope of the technical concept of the present invention.

[0061] The names of the symbols used in the specification and drawings of the present invention are as follows: [Explanation of symbols]

[0062] 100 First branch 200 Second Branch 300 Relay Section 400 Voltage distribution unit

Claims

1. a relay unit for controlling measurement of the battery pack voltage; first and second branching units provided between a battery pack voltage input terminal and the relay unit, branching the battery pack voltage to different paths according to the battery pack voltage and applying the branched voltage to the relay unit; a voltage distribution unit that distributes the battery pack voltage applied via the first or second branch unit and the relay unit and outputs the divided voltage to an output terminal; A battery pack voltage measurement circuit comprising:

2. 2. The battery pack voltage measuring circuit according to claim 1, wherein the first branch section comprises a first resistor and a first switch connected in series between the battery pack voltage input terminal and the relay section.

3. 3. The battery pack voltage measurement circuit according to claim 2, wherein the second branch section includes a second resistor and a second switch connected in series between the battery pack voltage input terminal and the relay section, and connected in parallel with the first resistor and the first switch, respectively.

4. 4. The battery pack voltage measurement circuit according to claim 3, wherein the relay unit comprises a relay switch and a third resistor connected in parallel between the connection point of the first and second branches and the voltage dividing unit.

5. The battery pack voltage measuring circuit according to claim 4 , further comprising a control unit that controls the first switch, the second switch, and the relay switch.

6. 6. The battery pack voltage measuring circuit according to claim 5, wherein the control unit selectively opens and closes the first and second switches depending on the magnitude of the battery pack voltage.

7. 7. The battery pack voltage measurement circuit according to claim 4, wherein a first resistance ratio, which is a ratio between the sum of the resistances of the voltage division units and the first resistance, and a second resistance ratio, which is a ratio between the sum of the resistances of the voltage division units and the second resistance, are set to be different from each other.

8. a first branching section provided between the battery pack voltage input terminal and the first node to branch a first battery pack voltage; a second branch section provided between the battery pack voltage input terminal and the first node, connected in parallel with the first branch section, and branching a second battery pack voltage; a relay unit provided between the first node and the second node, the relay unit controlling measurement of the battery pack voltage in response to a switching operation; a voltage distribution unit provided between the second node and a ground terminal, which distributes the battery pack voltage applied via the first or second branch unit and the relay unit and outputs the distributed voltage to an output terminal; A battery pack voltage measurement circuit comprising:

9. 9. The battery pack voltage measurement circuit of claim 8, wherein the first branch comprises a first resistor and a first switch connected in series between the battery pack voltage input terminal and the first node.

10. 10. The battery pack voltage measurement circuit of claim 9, wherein the second branch comprises a second resistor and a second switch connected in series between the battery pack voltage input terminal and the first node and connected in parallel with the first resistor and the first switch, respectively.

11. 11. The circuit for measuring a battery pack voltage according to claim 10, wherein the relay unit comprises a relay switch and a third resistor connected in parallel between the first node and the second node.

12. The battery pack voltage measuring circuit according to claim 11 , further comprising a control unit that controls the first switch, the second switch, and the relay switch.

13. The battery pack voltage measuring circuit according to claim 12 , wherein the control unit selectively opens and closes the first and second switches depending on the magnitude of the battery pack voltage.

14. 14. The battery pack voltage measurement circuit according to claim 11, wherein the first resistor and the second resistor have different resistance values.

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