KR20160077875A - Method and Apparatus for filtering measurement data of secondary battery pack - Google Patents

Abstract

An apparatus for selecting measurement data comprises: a voltage measurement unit measuring a voltage of a battery pack according to a voltage measurement sampling period; a current measurement unit measuring a voltage of the battery pack according to a current measurement sampling period; and a controller selecting a voltage as effective voltage data, when battery pack power conversion occurs, wherein the voltage is measured by the voltage measurement unit after the power conversion period is over and a current value, measured during a reliability period, among a plurality of current values which are measured by the current measurement unit during the power conversion period. According to the present invention, a battery pack state may be precisely monitored, even if the sampling period is not synchronized.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for selecting measurement data of a battery pack,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and method for selecting data measured by a secondary battery, and more particularly, Apparatus and method.

Recently, due to the depletion of fossil energy and environmental pollution, there is an increasing interest in electric vehicles and hybrid vehicles that use electric energy without using fossil energy.

Such electric vehicles and hybrid vehicle batteries are mainly comprised of secondary batteries capable of repeating the discharge process of converting chemical energy into electrical energy and the charging process of converting electrical energy into chemical energy. Types of secondary batteries include nickel cadmium batteries, nickel metal hydride batteries, lithium ion batteries, and lithium ion polymer batteries.

In order to drive an electric vehicle or a hybrid vehicle, a large-capacity battery pack in which a plurality of battery cells are connected in series is used because an electric motor requiring a high output is required to be driven.

In order to accurately grasp the state of the secondary battery, the concept of state of health (SOH) is used. Batteries vary in their characteristics over time, SOH is a measure of this aging effect. Quantitative prediction of SOH allows us to grasp the aging degree of the battery in advance. A typical parameter used for predicting the SOH is the internal resistance of the battery.

The internal resistance of the battery can be estimated by calculating the ratio between the voltage of each battery cell and the charging or discharging current of the battery. However, in a battery, there is a difference between a sampling period for measuring current and a sampling period for measuring voltage, and it is difficult to accurately measure the internal resistance. Accordingly, a technique of matching the voltage sampling period of the battery with the current sampling period has been disclosed.

However, there is a problem that it is difficult to consistently match the voltage sampling period and the current sampling period with a change of one sampling period. Accordingly, the conventional techniques continuously check the difference between the current sampling period and the voltage sampling period, and change the sampling period from time to time according to the difference. However, in the method of artificially changing either the voltage sampling period or the current sampling period, it is necessary to observe a continuous sampling period and control the relevant circuit to change the sampling period. There is a problem that an overload of the control device for controlling the current measuring circuit is generated.

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve such conventional problems and it is an object of the present invention to select and use valid data from a measured current value and a voltage value without changing the voltage sampling period and the current sampling period to grasp the state of the secondary battery And an object of the present invention is to provide an apparatus and method for selecting measurement data.

Other objects and advantages of the present invention will become apparent from the following description, and it will be understood by those skilled in the art that the present invention is not limited thereto. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

According to an aspect of the present invention, there is provided a measurement data selection apparatus including: a voltage measurement unit for measuring a voltage of a battery pack according to a voltage measurement sampling period; A current measuring unit for measuring a current of the battery pack according to a current measurement sampling cycle; And a control unit that selects a voltage measured through the voltage measuring unit after the power change time as effective voltage data when a power source change of the battery pack occurs, And a controller for selecting the current value measured during the interval as the effective current data.

Wherein the control unit sets the unreliable interval and the confidence interval in the power change period and removes a current value measured during the unreliable interval from a plurality of current values measured through the current measurement unit during the power change period, The measured current value can be selected.

Preferably, the controller sets the interval from the first time to the first time and the interval from the second time to the last time in the power change period as the unreliable interval, and sets the unreliable interval as the unreliable interval have.

The controller monitors the current value measured through the current measuring unit and determines that the power change occurs when the difference between the current measured value and the measured current value immediately before the current measured value exceeds a threshold value have.

The control unit may select, as the effective voltage data, a voltage measured for the first time by the voltage measuring unit after the power change time point.

Meanwhile, the controller may monitor the state of the battery pack using the current value selected by the effective current data and the voltage value selected as the effective voltage data.

According to another aspect of the present invention, there is provided a method of selecting measurement data, the method comprising: monitoring a battery pack; A voltage data selection step of selecting a voltage measured after the power change time point as effective voltage data when a power source change of the battery pack occurs as a result of the monitoring; And a current data selection step of selecting a current value measured during a confidence interval from the plurality of current values measured during the power change period and selecting the selected current value as effective current data.

The present invention filters and selects a voltage value and a current value measured in a voltage sampling period and a current sampling period on the basis of a power supply change period without changing a voltage sampling period and a current sampling period, The load of the battery management system caused by an artificial change in the sampling period can be reduced.

Also, according to the present invention, a current value in which a delay occurs in a current value measured during a current sampling period is removed based on a power supply variation period, and only reliable current values are selected, so that the state of the battery pack There is an effect that can be accurately monitored.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and form a part of the specification, illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention. And shall not be construed as limited to such matters.
1 is a schematic block diagram of a measurement data sorting apparatus for a battery pack according to an embodiment of the present invention.
2 is a flowchart showing a method of selecting measurement data of a battery pack according to an embodiment of the present invention.
3 is a diagram for explaining a method of selecting a valid voltage and an effective current based on a power supply change period according to an embodiment of the present invention.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, in which: There will be. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a measurement data sorting apparatus for a battery pack according to an embodiment of the present invention.

1, the apparatus for measuring data of a secondary battery pack according to the present invention includes a battery pack 10, a current measuring unit 20, a voltage measuring unit 30, a controller 40, and a storage unit 50, .

The battery pack 10 is an electric energy storing means and includes a plurality of rechargeable battery cells connected in series. The battery pack 10 may be a rechargeable lithium ion battery, a lithium metal battery, a lithium polymer battery, a nickel cadmium battery, a nickel metal hydride battery, a nickel zinc battery, and a lead acid battery.

The current measuring unit 20 is electrically connected to both terminals of the battery pack 10. The current measuring unit 20 periodically measures a discharge current output from the battery pack 10 or a charge current flowing into the battery pack 10 according to a current sampling period and outputs the measured current value to the control unit 40 Output.

The voltage measuring unit 30 is electrically connected to each battery cell included in the battery pack 10. The voltage measuring unit 30 periodically measures the voltage of the battery pack 10 according to the voltage sampling period and outputs the measured voltage value to the control unit 40. [

The storage unit 50 stores the selected current and voltage as valid data. In addition, the storage unit 50 may store environment data including setting information of a confidence interval, an unreliable interval, a power change period, and the like. The storage unit 50 may be a semiconductor device such as a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory, a hard disk, or the like, but the present invention is not limited thereto.

The control unit 40 selects effective data having reliability from among the current values measured through the current measuring unit 20 and the voltage values measured through the voltage measuring unit 30 based on the power supply change period and outputs the valid data to the storage unit 50 And monitors the state of the battery pack 10 such as the voltage change, the current change, the internal resistance change, and the capacity based on the current value and the voltage value stored as the valid data, and controls charging and discharging. The control unit 40 determines the first measured voltage value through the voltage measuring unit 30 after the power source change has occurred, after checking the period of the power source change when the power source change is detected in the battery pack 10 And stores them as the voltage data in the storage unit 50. [ Also, the control unit 40 sets the unreliable period and the confidence period in the power change period. The unreliable section is a time area in which a delay time occurring when a current value is transmitted, a delay time occurring in an internal circuit, and the like occurs.

The control unit 40 removes the current value corresponding to the unreliable period from the plurality of current values measured through the current measurement unit 20 during the power change period and then outputs the remaining current values as the effective current data to the storage unit 50 ). At this time, the control unit 40 sets the interval from the first time to the first time and the second time point to the last time in the power change period as the unreliable interval, and sets the unreliable interval as the unreliable interval. Based on the setting data stored in the storage unit 50, the control unit 40 can set the confidence interval and the unreliable interval in the power change period.

On the other hand, the controller 40 compares the current value measured immediately before with the current value measured at the present time through the current measuring unit 20, and when the difference of the current values exceeds the threshold current, 10). Also, the controller 40 can confirm the power change period by checking the time interval between the immediately previous power change point and the current power change point. Alternatively, the control unit 40 can check the power change period through CAN (Controller Area Network) communication with an external device (for example, a control device of an automobile) that is supplied with power from the battery pack 10, The power supply change period can be checked based on the environmental data stored in the power supply change period.

Preferably, the sampling period having a longer time out of the voltage sampling period and the current sampling period is not shorter than the power source change period, and has a time equal to or greater than the time of the power source change period.

Meanwhile, the controller 40 may be configured as a microprocessor that can execute the measurement data selection method according to the present invention in a programmable manner. Alternatively, the control unit 40 may be configured as a semiconductor chip in which the control flow of the measurement data selection method according to the present invention is implemented by a logic circuit. However, the present invention is not limited thereto.

Furthermore, the measurement data sorting apparatus according to the present invention can be used in combination with a battery pack driving apparatus that receives power from the battery pack 10. For example, the present invention can be used in various electronic products such as a notebook computer, a mobile phone, and a personal portable multimedia player. As another example, the present invention can be used in combination with various battery-powered power devices such as fossil fuel-powered vehicles, electric vehicles, hybrid vehicles, and electric bicycles.

In addition, the measurement data selection device according to the present invention can be used in a battery management system (BMS) that controls the charging and discharging of the battery pack 10 and protects the battery pack from overcharge or overdischarge.

2 is a flowchart showing a method of selecting measurement data of a battery pack according to an embodiment of the present invention.

Referring to FIG. 2, the current measuring unit 20 starts measuring the current of the battery pack 10 at regular intervals according to the current sampling period, and transmits the measured current value to the controller 40. Also, the voltage measuring unit 30 periodically measures the voltage of the battery pack 10 according to the voltage sampling period, and transmits the measured voltage value to the controller 40.

When the current measurement is started by the current measurement unit 20, the control unit 40 analyzes the plurality of current values received from the current measurement unit 20 and calculates a load (not shown in the figure) (Step S201). If the power supply to the battery pack 10 has been changed, That is, when the current value is received from the current measuring unit 20, the control unit 40 checks the difference between the received current value and the current value received from the current measuring unit 20 immediately before, And if it exceeds the threshold, it is determined that a power change has occurred at the present time. The control unit 40 determines that a power change (e.g., charging or discharging of the battery pack) has occurred when the current measured current rises above the threshold value before the immediately-measured current.

Next, the control unit 40 continuously receives one or more voltage values measured in accordance with the voltage sampling period in the voltage measuring unit 30, and among them, the voltage value received for the first time after the power change time point is stored in the battery pack 10 As the effective voltage data for the storage unit 50 (S203).

Then, the control unit 40 checks the power change period (S205). At this time, the controller 40 can confirm the power change period by checking the time interval between the immediately previous power change point and the current power point. The control unit 40 can confirm the power change period in the environment data stored in the storage unit 50 or can receive the power of the upper level control device And the power change period can be confirmed from the host controller.

Next, the control unit 40 sets the unreliable interval and the confidence interval in the power change period (S207). At this time, the control unit 40 sets the unreliable interval and the confidence interval in the power change period based on the setting information of the unreliable interval and the confidence interval stored in the environment data of the storage unit 50. [ Preferably, the control unit 40 sets the interval from the first time to the first time point and the interval from the second time point to the last time in the power change period as the unreliable interval, and sets the unreliable interval as the unreliable interval do. For example, when the power change period is 100 ms, the control unit 40 may set the interval from 0 m to 30 ms and the interval from 71 m to 100 ms as the unreliable interval, and set the remaining intermediate intervals other than the unreliable interval as the confidence interval .

The reason why the controller 40 sets the unreliable section for a certain period of time before and after the power change period is that the unreliable section is generated in the unreliable section due to the delay time generated in the transfer of the current value, It is determined that an internal delay has occurred. That is, the control unit 40 sets the interval in which the internal delay occurs as the unreliable interval.

Referring back to FIG. 2, the control unit 40 determines whether or not the current value corresponding to the unreliable period is included in the plurality of current values measured by the current measurement unit 20 during the power change period, And stores the selected one or more current values as effective current data in the storage unit 50 (S209). That is, the control unit 40 removes the current value measured during the unreliable time (i.e., the delay time occurs) from the plurality of current values sequentially received from the current measuring unit 20 according to the sampling period, And stores the measured current value in the storage unit 50 as effective current data.

Next, the controller 40 checks and monitors the state (e.g., remaining capacity, current change, voltage change, internal resistance change, etc.) of the battery pack 10 based on the valid voltage and the effective current (S211) .

FIG. 2 illustrates a process corresponding to one cycle, and the process according to FIG. 2 may be performed at predetermined time intervals.

3 is a diagram for explaining a method of selecting a valid voltage and an effective current based on a power supply change period according to an embodiment of the present invention.

In Fig. 3, it is explained that the sampling period of the current is 10 ms, the sampling period of the voltage is 100 ms, and the power source change period is 100 ms. In addition, in FIG. 3, a section 310 from t ₁ to t ₂ and a section 320 from t ₃ to t ₄ in the power change period are explained as unreliable sections.

Referring to FIG. 3, the controller 40 can confirm that the power change period is 100 ms based on the time interval at which the first power (power ₁ ) change and the second power (power ₂ ) change occur. In FIG. 3, the control unit 40 stores the voltage value (V ₂ ) measured first after the power change time t ₁ in the storage unit 50 as effective data. I ₆ , I ₇ , I ₈ , I ₁₃ , I _14, and I ₁₅ measured during the unreliable periods 310 and 320 in the power change period are sorted into untrusted data to remove, and stored in the confidence interval 330, the current value (that is, I _9, I _10, I ₁₁ and I _12), the storing unit 50 by selecting a current data measured during effective.

As described above, according to the present invention, the measured voltage value and the current value are selected based on the power supply change period without changing the voltage sampling period and the current sampling period, and the battery pack (10), thereby reducing the load caused by the change of the sampling period.

Further, the present invention eliminates unreliable current values having a delay time from the current values measured during the current sampling period based on the power supply change period, thereby making it easier to grasp the state of the battery pack whose sampling period is not synchronized can do.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. The present invention is not limited to the drawings.

10: Battery pack 20: Current measuring unit
30: voltage measuring unit 40:
50:

Claims (12)

A voltage measuring unit for measuring a voltage of the battery pack according to a voltage measurement sampling cycle;
A current measuring unit for measuring a current of the battery pack according to a current measurement sampling cycle; And
Wherein the control unit selects the voltage measured through the voltage measuring unit after the power change time point as the effective voltage data when the power source change of the battery pack occurs, And a control unit for selecting the current value measured during a predetermined period of time as valid current data. The method according to claim 1,
The control unit,
Wherein the control unit sets the unreliable interval and the confidence interval in the power change period, removes the measured current value during the unreliable interval from among the plurality of current values measured through the current measurement unit during the power change period, And the selected current value is selected. 3. The method of claim 2,
Wherein,
Wherein the control unit sets the interval from the first time to the first time and the interval from the second time to the last in the power change period as the unreliable interval and sets the confidence interval between the unreliable interval Sorting device. 4. The method according to any one of claims 1 to 3,
The control unit,
Wherein the controller monitors the current value measured by the current measuring unit and determines that the power supply change occurs when the difference between the current measured value and the immediately measured current value exceeds a threshold value Data selection device. 4. The method according to any one of claims 1 to 3,
Wherein,
Wherein the voltage measuring unit selects the first voltage measured by the voltage measuring unit after the power change time as the effective voltage data. 4. The method according to any one of claims 1 to 3,
The control unit,
And monitors the state of the battery pack using a current value selected by the effective current data and a voltage value selected as the effective voltage data. A monitoring step of monitoring whether or not a power source change of the battery pack occurs;
A voltage data selection step of selecting a voltage measured after the power change time point as effective voltage data when a power source change of the battery pack occurs as a result of the monitoring; And
And a current data selection step of selecting a current value measured during a confidence interval from the plurality of current values measured during the power change period and selecting the selected current value as effective current data. 8. The method of claim 7,
The current data selection step comprises:
Setting a non-confidence interval and a confidence interval in the power change period; And
And removing the measured current value during the unreliable period from among the plurality of current values measured during the power changing period and selecting the measured current value during the confidence interval as the valid data. Selection method. The method of claim 8, wherein
The current data selection step comprises:
Wherein the control unit sets the interval from the first time to the first time and the interval from the second time to the last in the power change period as the unreliable interval and sets the confidence interval between the unreliable interval Selection method. 10. The method according to any one of claims 7 to 9,
Wherein the monitoring step comprises:
Wherein the plurality of measured current values are monitored to determine that a power source change occurs when the difference between the current measured current value and the immediately measured current value exceeds a threshold value. 10. The method according to any one of claims 7 to 9,
The voltage data selection step may include:
Wherein the first measured voltage is selected as the effective voltage data after the power change time point. 10. The method according to any one of claims 7 to 9,
Further comprising the step of monitoring the state of the battery pack using the current value selected by the effective current data and the voltage value selected as the effective voltage data.

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