阅读说明：本技术 电流测量设备、电流测量方法和包括电流测量设备的电池组 (Current measuring apparatus, current measuring method, and battery pack including current measuring apparatus ) 是由 李沅泰 崔良林 于 2019-06-11 设计创作，主要内容包括：提供了电流测量设备、电流测量方法及包括电流测量设备的电池组。所述电流测量设备包括：开关电路,其安装在电池的充/放电路径上；电流测量单元,其包括设置在充/放电路径中的分流电阻器并输出与分流电阻器两端的电压相对应的电流信号；电压测量单元,其用于测量开关电路两端的电压；温度测量单元,其用于测量开关电路的温度；以及控制单元。控制单元基于电流信号,确定表示流过分流电阻器的电流的第一电流值。控制单元基于测量到的电压和测量到的温度,确定表示流过开关电路的电流的第二电流值。控制单元基于第一电流值和第二电流值,确定分流电阻器是否处于正常状态。(Provided are a current measuring apparatus, a current measuring method, and a battery pack including the current measuring apparatus. The current measuring apparatus includes: a switching circuit mounted on a charge/discharge path of the battery; a current measuring unit including a shunt resistor provided in a charge/discharge path and outputting a current signal corresponding to a voltage across the shunt resistor; a voltage measuring unit for measuring a voltage across the switching circuit; a temperature measuring unit for measuring a temperature of the switching circuit; and a control unit. The control unit determines a first current value representing a current flowing through the shunt resistor based on the current signal. The control unit determines a second current value representing a current flowing through the switching circuit based on the measured voltage and the measured temperature. The control unit determines whether the shunt resistor is in a normal state based on the first current value and the second current value.)

1. A current measuring device for measuring a current flowing through a charge-discharge path of a battery, the current measuring device comprising:

a switching circuit mounted on the charge and discharge path;

a current measuring unit having a shunt resistor mounted on the charge and discharge path and configured to output a current signal corresponding to a voltage across the shunt resistor;

a voltage measurement unit configured to measure a voltage across the switching circuit;

a temperature measurement unit configured to measure a temperature of the switching circuit; and

a control unit operably coupled to the switching circuit, the current measurement unit, the voltage measurement unit, and the temperature measurement unit,

wherein the control unit is configured to:

determining, based on the current signal, a first current value indicative of a current flowing through the shunt resistor,

determining a second current value indicative of a current flowing through the switching circuit based on the measured voltage and the measured temperature, an

Determining whether the shunt resistor is in a normal state based on the first current value and the second current value.

2. Current measurement device according to claim 1,

wherein the control unit is configured to determine an on-resistance of the switching circuit based on the measured temperature, an

Wherein the second current value is obtained by dividing the measured voltage by the on-resistance.

3. The current measuring apparatus according to claim 2, further comprising:

a storage device configured to store a lookup table in which a correspondence between a temperature of the switching circuit and an on-resistance of the switching circuit is recorded,

wherein the control unit is configured to determine an on-resistance recorded in the lookup table in association with the measured temperature as the on-resistance of the switching circuit by using the measured temperature as an index.

4. Current measurement device according to claim 1,

wherein the control unit is configured to determine a third current value indicating a current flowing through the charge and discharge path based on the first current value and the second current value.

5. Current measurement apparatus according to claim 4,

wherein the control unit is configured to determine one of the first current value, the second current value, and an average of the first current value and the second current value as the third current value when a difference between the first current value and the second current value is within a normal range.

6. Current measurement apparatus according to claim 4,

wherein the control unit is configured to determine the second current value as the third current value when a difference between the first current value and the second current value is out of a normal range.

7. Current measurement apparatus according to claim 4,

wherein the control unit is configured to output a fault message when a difference between the first current value and the second current value exceeds a normal range.

8. Current measurement apparatus according to claim 6,

wherein the control unit is configured to determine the normal range based on the measured temperature.

9. Current measurement apparatus according to claim 8,

wherein the control unit is configured to expand the normal range as the measured temperature decreases.

10. A battery pack comprising a current measuring device according to any one of claims 1 to 9.

11. A current measuring method for measuring a current flowing through a charge-discharge path of a battery, the current measuring method comprising the steps of:

measuring a voltage across a switching circuit mounted on the charge and discharge path;

measuring a temperature of the switching circuit;

determining a first current value indicating a current flowing through a shunt resistor mounted on the charge and discharge path based on a voltage across the shunt resistor;

determining a second current value indicative of current flowing through the switching circuit based on the measured voltage and the measured temperature; and

determining whether the shunt resistor is in a normal state based on the first current value and the second current value.

12. The current measuring method according to claim 11,

wherein the second current value is obtained by dividing the measured voltage by an on-resistance associated with the measured temperature.

13. The current measuring method according to claim 11,

wherein in the step of determining whether the shunt resistor is in a normal state, it is determined that the shunt resistor is in a normal state when a difference between the first current value and the second current value is within a normal range.

Technical Field

The present disclosure relates to an apparatus and method for measuring current flowing through a charge and discharge path of a battery and a battery pack including the same.

The present application claims priority from korean patent application No.10-2018-0072156, filed in korea at 22.6.2018, and korean patent application No.10-2019-0064721, filed in korea at 31.5.2019, the disclosures of which are incorporated herein by reference.

Background

Recently, the demand for portable electronic products such as notebook computers, video cameras, and portable telephones has sharply increased, and electric vehicles, energy storage batteries, robots, satellites, and the like have been seriously developed. Therefore, high-performance secondary batteries that allow repeated charge and discharge are being actively studied.

Currently commercially available batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, lithium batteries, and the like. Among these batteries, lithium batteries are receiving attention because they have little memory effect compared to nickel-based batteries and also have an extremely low self-discharge rate and high energy density.

In order to measure the current flowing through the battery, a shunt resistor may be mounted on a charge and discharge path of the battery. The current measured using the shunt resistor is mainly used to determine an overcurrent or to estimate a state of charge (SOC) and a state of health (SOH) of the battery.

The current measurement using the shunt resistor is based on the voltage across the shunt resistor divided by the reference resistance. The reference resistance is predetermined in consideration of the material, size, shape, and the like of the shunt resistor. However, if the shunt resistor gradually deteriorates over time or is damaged due to vibration and shock, the actual resistance of the shunt resistor may greatly differ from the reference resistance.

In particular, with respect to ISO 26262 (international standard for vehicle safety), it is necessary to determine whether or not the current measured by a current sensor including a shunt resistor is reliable (or whether or not the current sensor is normal) in order to satisfy the highest level d of four levels of an automotive safety integrity level (ASI L). conventionally, the current measured by the current sensor and the current measured by another current sensor (for example, a hall effect current sensor) are compared with each other, thereby improving the reliability of the current measurement result.

Disclosure of Invention

Technical problem

The present disclosure is designed to solve the problems of the related art, and therefore, the present disclosure is directed to providing an apparatus and method for diagnosing whether a shunt resistor mounted on a charge and discharge path of a battery is in a normal state without an additional sensor, and a battery pack including the same.

These and other objects and advantages of the present disclosure will be understood from the following detailed description, and will become more fully apparent from the exemplary embodiments of the present disclosure. Also, it will be readily understood that the objects and advantages of the present disclosure may be realized in the manner set forth in the appended claims and combinations thereof.

Technical scheme

In one aspect of the present disclosure, there is provided a current measuring device for measuring a current flowing through a charge-discharge path of a battery. The current measuring apparatus includes: a switching circuit mounted on the charge and discharge path; a current measuring unit having a shunt resistor installed on the charge and discharge path and configured to output a current signal corresponding to a voltage across the shunt resistor; a voltage measurement unit configured to measure a voltage across the switching circuit; a temperature measurement unit configured to measure a temperature of the switching circuit; and a control unit operably coupled to the switching circuit, the current measurement unit, the voltage measurement unit, and the temperature measurement unit. The control unit is configured to determine a first current value indicative of a current flowing through the shunt resistor based on the current signal. The control unit is configured to determine a second current value indicative of a current flowing through the switching circuit based on the measured voltage and the measured temperature. The control unit is configured to determine whether the shunt resistor is in a normal state based on the first current value and the second current value.

The control unit may be configured to determine an on-resistance of the switching circuit based on the measured temperature. The second current value is obtained by dividing the measured voltage by the on-resistance.

The current measuring apparatus may further include a storage device configured to store a lookup table in which a correspondence relationship between the temperature of the switching circuit and the on-resistance of the switching circuit is recorded. The control unit may be configured to determine an on-resistance recorded in a lookup table in association with the measured temperature as the on-resistance of the switching circuit by using the measured temperature as an index.

The control unit may be configured to determine a third current value indicating a current flowing through the charge and discharge path based on the first current value and the second current value.

The control unit may be configured to determine one of the first current value, the second current value, and an average of the first current value and the second current value as a third current value when a difference between the first current value and the second current value is within a normal range.

The control unit may be configured to determine the second current value as a third current value when a difference between the first current value and the second current value is out of a normal range.

The control unit may be configured to output a fault message when a difference between the first current value and the second current value exceeds a normal range.

The control unit may be configured to determine the normal range based on the measured temperature. The control unit may be configured to expand the normal range as the measured temperature decreases.

In another aspect of the present disclosure, there is also provided a battery pack including a current measuring device.

In another aspect of the present disclosure, there is also provided a current measuring method for measuring a current flowing through a charge and discharge path of a battery. The method comprises the following steps: measuring a voltage across a switching circuit mounted on a charge and discharge path; measuring the temperature of the switching circuit; determining a first current value indicating a current flowing through a shunt resistor mounted on a charge and discharge path based on a voltage across the shunt resistor; determining a second current value indicative of a current flowing through the switching circuit based on the measured voltage and the measured temperature; and determining whether the shunt resistor is in a normal state based on the first current value and the second current value.

The second current value may be obtained by dividing the measured voltage by the on-resistance associated with the measured temperature.

In the determining whether the shunt resistor is in the normal state, it is determined that the shunt resistor is in the normal state when a difference between the first current value and the second current value is within a normal range.

Technical effects

According to at least one embodiment of the present disclosure, it is possible to diagnose whether or not a shunt resistor installed on a charge and discharge path of a battery is in a normal state without an additional current sensor.

The effects of the present disclosure are not limited to the above effects, and other effects not mentioned herein will be clearly understood from the claims by those skilled in the art.

Drawings

Fig. 1 is a diagram schematically showing a functional configuration of a current measuring apparatus according to an embodiment of the present disclosure.

Fig. 2 is a diagram schematically showing a battery pack including the current measuring apparatus of fig. 1.

Fig. 3 exemplarily shows a first look-up table associated with the switching circuit of fig. 1 and 2.

Fig. 4 exemplarily shows a logic circuit included in the control unit of fig. 1 and 2.

Fig. 5 is a flowchart schematically illustrating a current measuring method according to another embodiment of the present disclosure.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation.

Accordingly, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of this disclosure, so it should be understood that other equivalents and modifications could be made thereto without departing from the scope of this disclosure.

Terms including ordinal numbers such as "first," "second," etc., may be used to distinguish one element from another element among the various elements, but are not intended to limit the elements by such terms.

Throughout the specification, when a portion is referred to as "comprising" or "includes" any element, it means that the portion may further include other elements but not exclude other elements, unless explicitly stated otherwise. Further, the term "control unit" described in the specification refers to a unit that processes at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

In addition, throughout the specification, when a part is referred to as being "connected" to another part, it is not limited to the case where they are "directly connected", but also includes the case where another element is interposed between them and is "indirectly connected".

Fig. 1 is a diagram schematically showing a functional configuration of a current measuring apparatus according to an embodiment of the present disclosure, and fig. 2 is a diagram schematically showing a battery pack including the current measuring apparatus of fig. 1.

Referring to fig. 1 and 2, a battery pack P includes a battery 10, a switching circuit 50, and a current measuring device 1 (hereinafter referred to as "device").

The battery 10 includes at least one battery cell. If a plurality of battery cells are included in the battery 10, the plurality of battery cells may be electrically connected in series or in parallel with each other.

The switching circuit 50 may include at least one charging switch and at least one discharging switch. Each charging switch may be electrically connected in series to each discharging switch. If the switching circuit 50 includes a plurality of charge switches, the plurality of charge switches may be electrically connected in parallel. If the switching circuit 50 includes a plurality of discharge switches, the plurality of discharge switches may be electrically connected in parallel.

Each of the charge switches may control a current flowing in a direction for charging the battery 10. For example, each charge switch may be located between the positive terminal of the battery 10 and the positive terminal of the battery pack P, and regulate the magnitude of a charge current, which is a current flowing from the positive terminal of the battery pack P to the positive terminal of the battery 10.

Each discharge switch may control a current flowing in a direction for discharging the battery 10. For example, each discharge switch may be located between the positive terminal of the battery 10 and the positive terminal of the battery pack P, and regulate the magnitude of a discharge current, which is a current flowing from the positive terminal of the battery 10 to the positive terminal of the battery pack P.

For example, each charge switch and each discharge switch may be a Field Effect Transistor (FET) including a gate terminal, a drain terminal, and a source terminal. The FET may be turned on or off depending on the magnitude of a voltage applied between the gate terminal and the source terminal.

The device 1 is arranged to measure the current flowing through the charge-discharge path of the battery 10. The device 1 comprises a voltage measuring unit 100, a temperature measuring unit 200, a current measuring unit 300 and a control unit 400. The device 1 may further comprise storage means 500.

The voltage measuring unit 100 may be electrically connected to both ends of the switching circuit 50. That is, the voltage measuring unit 100 may be electrically connected to the switching circuit 50 in parallel to measure the voltage across the switching circuit 50.

The voltage measurement unit 100 may measure a potential difference between one end and the other end of the switching circuit 50 as a voltage of the switching circuit 50. For example, in the case where one end of each charge switch is electrically connected to the electrode terminal of the battery 10, one end of each discharge switch is electrically connected to the positive electrode terminal of the battery pack P, the other end of each charge switch and the other end of each discharge switch are electrically connected to each other, and a potential difference between one end of each charge switch and one end of each discharge switch may be measured as the voltage of the switching circuit 50 by the voltage measuring unit 100.

The voltage measurement unit 100 may be operatively coupled to the control unit 400 to exchange electrical signals with the control unit 400. The voltage measuring unit 100 may measure the voltage of the switching circuit 50 per unit time in response to a voltage measurement command from the control unit 400 and output a voltage signal indicating the measured voltage of the switching circuit 50 to the control unit 400.

The temperature measuring unit 200 is located within a predetermined distance from the switching circuit 50 and is configured to measure the temperature of the switching circuit 50. The temperature measurement unit 200 may be operatively coupled to the control unit 400 to exchange electrical signals with the control unit 400. The temperature measuring unit 200 may measure the temperature of the switching circuit 50 per unit time and output a temperature signal indicating the measured temperature of the switching circuit 50 to the control unit 400. A known temperature sensor such as a thermocouple may be used as the temperature measuring unit 200.

The current measurement unit 300 includes a shunt resistor 30 and a signal processing circuit 32.

The shunt resistor 30 may be located in a charge-discharge path between the negative terminal of the battery 10 and the negative terminal of the battery pack P. The voltage across the shunt resistor 30 depends on the direction and magnitude of the current flowing through the charge-discharge path.

The signal processing circuit 32 is operatively coupled to the control unit 400 to exchange electrical signals with the control unit 400. The signal processing circuit 32 may measure the current flowing through the shunt resistor 30 per unit time based on the voltage across the shunt resistor 30 in response to a current measurement command from the control unit 400, and output a current signal indicating the direction and magnitude of the measured current to the control unit 400.

Two input terminals of the signal processing circuit 32 may be electrically connected to one end and the other end of the shunt resistor 30, respectively. The signal processing circuit 32 may amplify the voltage across the shunt resistor 30 received through both input terminals of the signal processing circuit 32 and then output a digital signal indicating the amplified voltage to the control unit 400 as a current signal. The control unit 400 may determine the first current value indicating the direction and magnitude of the current flowing through the charge and discharge path based on the current signal from the signal processing circuit 32 per unit time according to ohm's law.

The control unit 400 may be implemented in hardware using at least one of an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a programmable logic device (P L D), a Field Programmable Gate Array (FPGA), a microprocessor, and an electrical unit for performing other functions the storage device 500 may be included in the control unit 400.

The control unit 400 determines a voltage value indicating the voltage across the switching circuit 50 based on the voltage signal per unit time from the voltage measurement unit 100. The control unit 400 determines a temperature value indicating the temperature of the switching circuit 50 based on the temperature signal per unit time from the temperature measurement unit 200.

The control unit 400 may determine a second current value indicating a direction and magnitude of the current flowing through the switching circuit 50 per unit time based on the voltage value and the temperature value associated with the switching circuit 50.

Since both the first current value and the second current value represent the direction and magnitude of the current flowing through the charge-discharge path of the battery 10, the first current value and the second current value are generally the same or different within an acceptable range. Meanwhile, if the shunt resistor 30 is damaged or a short-circuit fault or the like occurs at the shunt resistor 30, the difference between the first current value and the second current value may be significantly increased.

The control unit 400 may estimate the on-resistance of the switching circuit 50 based on the temperature of the switching circuit 50 per unit time. The on-resistance of the switching circuit 50 refers to the resistance of the switching circuit 50 when the switching circuit 50 is in an on state, and may be a parameter depending on the temperature. The control unit 400 may refer to a first lookup table in which a correspondence relationship between the temperature and the on-resistance of the switching circuit 50 is recorded, and estimate the on-resistance corresponding to the temperature of the switching circuit 5 measured at a specific point in time, which is recorded in the first lookup table, as the on-resistance of the switching circuit 50 at the specific point in time. The first lookup table may be stored in the storage device 500 in advance.

According to ohm's law, the control unit 400 may determine the second current value indicative of the current flowing through the switching circuit 50 at a specific point in time by dividing the voltage across the switching circuit 50 at the specified point in time by the estimated on-resistance.

The control unit 400 may determine a third current value indicating a current flowing through the charge and discharge path based on the first current value and the second current value. For example, the control unit 400 may determine the first current value as a current value flowing through the charge and discharge path based on a difference between the first current value and the second current value. As another example, the control unit 400 may determine an average value of the first current value and the second current value as a current value flowing through the charge and discharge path based on the first current value and the second current value. As yet another example, the control unit 400 may determine the second current value as a current value flowing through the charge and discharge path based on a difference between the first current value and the second current value.

The control unit 400 may diagnose whether the shunt resistor 30 is in the normal state based on the difference between the first current value and the second current value. For example, if the difference between the first current value and the second current value is within a normal range (e.g., -10mA to 10mA), the control unit 400 may determine that the shunt resistor 30 is in a normal state.

The normal range may be predetermined. Alternatively, the normal range may be determined by the control unit 400 based on the temperature of the switching circuit 50. The switching circuit 50 may have the following characteristics: the on-resistance of the switching circuit 50 decreases as the temperature of the switching circuit 50 increases, and the on-resistance of the switching circuit 50 increases as the temperature of the switching circuit 50 decreases. Accordingly, the control unit 400 may narrow the normal range as the temperature of the switching circuit 50 increases, and the control unit 400 may expand the normal range as the temperature of the switching circuit 50 decreases. A second lookup table that records the correspondence between the temperature and the normal range of the switching circuit 50 may be stored in the storage device 500 in advance. The control unit 400 may obtain the normal range associated with the temperature of the switching circuit 50 from the second lookup table by using the temperature of the switching circuit 50 as an index.

The control unit 400 may determine that the shunt resistor 30 is in the fault state if the difference between the first current value and the second current value exceeds the normal range. The fault state of the shunt resistor 30 may represent a state in which the difference between the resistance of the shunt resistor 30 and the reference resistance exceeds a certain level due to deterioration or damage of the shunt resistor 30. Data indicating the normal range may be stored in the storage device 500 in advance. If it is determined that the shunt resistor 30 is in the fault state, the control unit 400 may transmit a fault message to the external device 2. The external device 2 may be an Electronic Control Unit (ECU) of an electric system (e.g., an electric vehicle) in which the battery pack P is mounted.

The control unit 400 may determine any one of the first current value, the second current value, and an average value of both the first current value and the second current value as the third current value if a difference between the first current value and the second current value is within a normal range. This is because the difference between the first current value and the second current value is within the normal range, indicating that the first current value is reliable.

When the difference between the first current value and the second current value is out of the normal range, the control unit 400 may determine the second current value as a third current value.

The storage device 500 may be operatively coupled to the control unit 400 to exchange electrical signals with the control unit 400. The storage device 500 is not particularly limited as long as it is a storage medium capable of recording and erasing data. For example, the storage device 500 may be a RAM, a ROM, a register, a hard disk, an optical recording medium, or a magnetic recording medium. The memory device 500 may be electrically connected to the control unit 400 via, for example, a data bus so as to be accessible to the control unit 400. The storage device 500 may store and/or update and/or erase and/or transmit programs including various control logic executed by the control unit 400 and/or data generated when the control logic is executed.

Fig. 3 exemplarily shows a first look-up table associated with the switching circuit of fig. 1 and 2.

Referring to fig. 3, as described above, the control unit 400 may refer to the first lookup table stored in the storage device 500 to determine the on-resistance of the switching circuit 50.

For example, if the temperature of the switching circuit 50 received from the temperature measuring unit 200 is "a", the control unit 400 may determine "x" associated with the temperature "a" in the first lookup table as the on-resistance of the switching circuit 50 using the temperature "a" as an index. As another example, if the temperature of the switching circuit 50 is "b", the control unit 400 may determine "y" associated with the temperature "b" in the first lookup table as the on-resistance of the switching circuit 50.

The device 1 determines the second current value indicating the current flowing through the switching circuit 50 based on the temperature of the switching circuit 50 and the voltage across the switching circuit 50 by utilizing the characteristic that the on-resistance of a semiconductor switch such as an FET included in the switching circuit 50 varies depending on the temperature. Next, the apparatus 1 compares the second current value with the first current value measured using the shunt resistor 30, thereby improving the accuracy of current measurement without adding a hall effect sensor or the like.

Fig. 4 exemplarily shows a logic circuit included in the control unit of fig. 1 and 2.

Referring to fig. 4, the control unit 400 may determine the second current value using a logic circuit 450 included in the control unit 400. Here, the logic circuit 450 may be configured to receive the temperature (T) of the switching circuit 50 when receiving_SW) And the voltage (V) across the switching circuit 50_SW) When the current value is used as an input value, a second current value (I) is output_SW) As an output value.

The device 1 may be applied to a Battery Management System (BMS). That is, the BMS may include the device 1. At least some of the components in the device 1 may be implemented by supplementing the functions of the components included in the conventional BMS or adding new functions. For example, the control unit 400 and the storage means 500 of the device 1 may be implemented as components of a BMS.

Fig. 5 is a flowchart schematically illustrating a current measuring method according to another embodiment of the present disclosure. The object to perform each step included in the method of fig. 5 may be each component of the device 1.

Referring to fig. 5, in step S100, the control unit 400 collects a voltage signal from the voltage measuring unit 100, a temperature signal from the temperature measuring unit 200, and a current signal from the current measuring unit 300.

In step S110, the control unit 400 determines a voltage value indicating the voltage across the switch circuit 50 and a temperature value indicating the temperature of the switch circuit 50 based on the voltage signal and the temperature signal.

In step S120, the control unit 400 determines a first current value indicating a current flowing through the shunt resistor 30 based on the current signal. Since the shunt resistor 30 is mounted on the charge-discharge path, the first current value also represents the current flowing through the charge-discharge path.

In step S130, the control unit 400 determines a second current value indicating the current flowing through the switching circuit 50 based on the voltage value and the temperature value determined in step S110. Since the switching circuit 50 is mounted on the charge/discharge path, the second current value also indicates the current flowing through the charge/discharge path.

In step S140, it is determined whether the shunt resistor 30 is in the normal state based on the first current value and the second current value. For example, if the difference between the first current value and the second current value is within the normal range, it can be determined that the shunt resistor 30 is in the normal state. Meanwhile, if the difference between the first current value and the second current value is out of the normal range, it may be determined that the shunt resistor 30 is in the fault state. If the value of step S140 is "NO," the process may proceed to step S150. If the value of step S140 is "YES," the method may end.

In step S150, the control unit 400 may transmit a failure message to the external device 2. The failure message is a message notifying the user or the external device 2 that the shunt resistor 30 is in the failure state.

The above-described embodiments of the present disclosure are not necessarily implemented by the apparatuses and methods, but may also be implemented by a program for implementing functions corresponding to the configuration of the present disclosure or a recording medium having the program recorded thereon. From the above description of the embodiments, a person skilled in the art can easily perform such an implementation.

The present disclosure has been described in detail. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.

In addition, a person skilled in the art may make many substitutions, modifications and changes to the above-described present disclosure without departing from the technical aspects of the present disclosure, and the present disclosure is not limited to the above-described embodiments and drawings, and each embodiment may be selectively combined partially or entirely to allow various modifications.