KR101268847B1 - Apparatus and method for measuring battery cell voltage - Google Patents

Abstract

PURPOSE: A battery cell voltage measuring apparatus and a method thereof are provided to measure the precise cell voltage of a battery by being connected with the cell voltage of the battery and controlling the offset voltage of a differential amplifier. CONSTITUTION: A battery cell voltage apparatus includes a cell voltage dividing unit(120) which lowers the voltage of each cell into a voltage which a differential amplifier accommodates; a cell voltage selection multiplexer(140) and an offset selection multiplexer(160) to which the differential voltage of each cell which is divided in the cell voltage dividing unit is selectively inputted; a multiplexer control unit(180) which controls the selection of the differential voltage which is inputted to the cell voltage selection multiplexer and the offset selection multiplexer; a multiplexer synchronizing commanding unit(200) which synchronizes the selected differential voltage of each cell by being inputted with a synchronization command into the multiplexer control unit; the differential amplifier(220) which amplifies the differential voltage which is inputted through the cell voltage selection multiplexer and the offset selection multiplexer; and a data processor(240) which converts a battery voltage which is outputted from the differential amplifier into digital data. Multiple cell voltage dividers which comprise the cell voltage dividing unit lower the voltage of each cell into a voltage which the differential amplifier can accommodate at the same division rate by multiple resistances which are precisely matched with a capacitor. [Reference numerals] (100) Battery; (120) Cell voltage dividing unit; (140) Cell voltage selection multiplexer; (160) Offset selection multiplexer; (180) Multiplexer control unit; (200) Multiplexer synchronizing commanding unit; (220) Differential amplifier; (245) Sample and hold unit; (250) Analog digital converting unit

Description

Apparatus and method for measuring battery cell voltage of a battery

The present invention relates to an apparatus for measuring a cell voltage of a battery and a method of measuring the battery voltage, and more particularly, to adjust an offset voltage of a differential amplifier using a battery cell voltage, so that a precise cell voltage can be measured. And a measuring method thereof.

Recently, as the development of electric vehicles or hybrid vehicles has been actively developed, small and large-capacity batteries are required to be developed, and a large-capacity battery may be configured in the form of a pack in which a plurality of cells capable of repeatedly charging and discharging are connected in series.

When charging and discharging the battery pack, the state of charge (SOC) of each cell should be properly maintained and the battery pack should be protected from abnormal conditions such as overcharge or overdischarge. In addition, charging equalization is required so that each cell in the battery pack is charged while maintaining a constant voltage.

Therefore, it is necessary to periodically measure and monitor the voltage of each cell using a cell voltage measurement device.

In order to solve the necessity, an apparatus and a technology for measuring the voltage of each cell of a battery charged with a high voltage have been developed. In the conventional battery cell voltage measuring device, a differential amplifier can accept the voltage of a plurality of cells connected in series. The cell voltage is measured as low as possible, but at this time, a problem arises in that the measurement accuracy is degraded due to the high voltage division ratio of the cell voltage located at the top layer of the battery pack.

In addition, the conventional cell voltage measuring apparatus may improve the measurement accuracy by adjusting the offset voltage when setting the offset with respect to the reference voltage of the differential amplifier, but because the offset voltage of the differential amplifier is adjusted independently of the battery cell voltage offset portion It has been pointed out that a problem that greatly affects the precision of the cell voltage measuring device depends on the precision of the offset voltage set at.

Republic of Korea Patent Publication No. 2011-059318

Accordingly, the present invention was devised to solve the above-mentioned disadvantages and problems in the conventional cell voltage measuring apparatus and the measuring method, and the precision cell of the battery is controlled by adjusting the offset voltage of the differential amplifier in conjunction with the cell voltage of the battery. An object of the present invention is to provide an apparatus for measuring a cell voltage of a battery and a method of measuring the same so that voltage can be measured.

In addition, another object of the present invention is to provide a cell voltage measuring apparatus and a measuring method for filtering a change in cell voltage caused by instantaneous overcharge and overdischarge or instantaneous noise in a measurement circuit.

According to an aspect of the present invention, there is provided a cell voltage measuring apparatus of a battery, in which an offset voltage of a differential amplifier is adjusted by being connected to a battery and interlocked with each cell voltage of the battery, wherein A cell voltage divider which lowers the voltage to an acceptable voltage of the differential amplifier; A cell voltage selection multiplexer and an offset selection multiplexer for selectively inputting differential voltages of the cells divided by the cell voltage divider; A multiplexer controller configured to control selection of the differential voltages input to the cell voltage selection multiplexer and the offset selection multiplexer; A multiplexer synchronization command unit configured to synchronize a selected differential voltage of each of the cells by inputting a synchronization command to the multiplexer controller; A differential amplifier for amplifying a differential voltage input through the cell voltage selection multiplexer and an offset selection multiplexer; And a data processing unit for converting the battery voltage output from the differential amplifier into digital data.

In this case, the data processing unit, a sample and hold unit; And an A / D converter configured to convert the amplified differential voltage, which is analog data, into digital data.

The output terminal of the cell voltage selection multiplexer is connected to the (+) side non-inverting terminal of the differential amplifier, and the output terminal of the offset selection multiplexer is connected to the (−) side inverting terminal of the differential amplifier. The differential voltage generated between the cell voltage selected by the multiplexer and the offset voltage selected by the offset selection multiplexer may be amplified by the differential amplifier.

On the other hand, another object of the present invention, the step of setting the number of cell voltage filtering of the initial battery; Selecting a cell voltage and an offset cell voltage of the battery through a cell voltage selection multiplexer and an offset selection multiplexer under control of a multiplexer synchronization command unit in a multiplexer control unit; Amplifying a differential voltage of a cell selected by the cell voltage selection multiplexer and the offset selection multiplexer by a differential amplifier; Outputting amplified PVcell voltage by the differential amplifier; Converting analog data into digital data through a sample and hold part and an A / D converter of a data processor of the battery voltage differentially amplified by the differential amplifier; Outputting a PVcell voltage converted into digital data by the data processor and filtering a cell voltage of the battery converted into digital data; And outputting a filtered FVcell voltage converted into digital data by the data processing unit.

In the selecting of the cell voltage and the offset cell voltage of the battery, any one channel of the cell voltage selection multiplexer and the offset selection multiplexer is selected according to an output signal of the multiplexer controller, and the channel selection is performed by a function operation input terminal. The cell voltage multiplexer channel corresponding to EN and the control signal of the address input terminal ADD may be selected.

In the filtering of the cell voltage, the filtered FVcell voltage is calculated using the SVcell voltage as digital data, and the filtered FVcell voltage is calculated using a first order filtering algorithm and a filtering parameter. Can be calculated.

The cell pressure measuring apparatus and the measuring method according to the present invention have the advantage of improving the measurement accuracy by widening the measurement range of the battery cell voltage by adjusting the offset voltage of the differential amplifier using the cell voltage of the battery.

In addition, the present invention has the advantage that the precise cell voltage measurement can be performed by filtering the cell voltage change due to the instantaneous overcharge and overdischarge of the battery due to the cell voltage change or the instantaneous noise generated in the measurement circuit.

1 is a block diagram showing the configuration of a cell voltage measuring apparatus of a battery according to the present invention.
2 is a circuit diagram of an exemplary embodiment in which a cell voltage measuring device according to the present invention is connected to a battery in which a plurality of cells are connected in series.
3 is a flowchart illustrating a method of measuring a cell voltage according to the present invention in sequence.

Matters relating to the operational effects including the technical configuration for the above object of the cell voltage measuring apparatus and the measuring method of the battery according to the present invention will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention. .

First, Figure 1 is a block diagram showing the configuration of a cell voltage measuring apparatus of a battery according to the present invention.

As shown, a cell voltage measuring apparatus of a battery according to the present invention includes a battery 100, a cell voltage divider 120, a cell voltage select multiplexer 140, an offset select multiplexer 160, a multiplexer controller 180, The multiplexer synchronization command unit 200, the differential amplifier 220 for amplifying the differential voltage of the cell constituting the battery, and the data processor 240 for converting the battery voltage output from the differential amplifier 220 to digital data may be configured. have.

In this case, the data processor 240 may include a sample and hold unit 245 and an A / D converter 250.

The battery 100 may be configured in the form of a package or a module in which a plurality of cells are electrically connected and packaged in a housing (not shown), and the plurality of cells constituting the battery 100 may be connected in series. Can be.

In addition, the cell voltage divider 120 lowers the voltage of each cell constituting the battery 100 to a voltage that the differential amplifier 220 can accommodate, and the cell voltage select multiplexer 140 divides the divided voltages. The differential voltage of the cells can be selected.

In this case, the cell voltage selection multiplexer 140 may control the selection of the differential voltage through the multiplexer controller 180, and the multiplexer synchronization command unit 200 transmits the synchronization command by the selection of the differential voltage to the multiplexer controller 180. Can be entered.

In addition, the differential amplifier 220 is amplified by the differential voltage of each cell input from the cell voltage select multiplexer 180, and the output voltage amplified from the differential amplifier 220 is analog data, so that the output voltage of the data processor The digital data may be converted at 240.

2 is a circuit diagram of an exemplary embodiment in which a cell voltage measuring apparatus according to the present invention is connected to a battery in which a plurality of cells are connected in series.

As shown in FIG. 2, in the battery 100, a plurality of cells (cells 1 to 11) may be connected in series with each other. In this case, as illustrated in the drawing, the battery 100 may include, for example, a configuration in which 11 batteries are connected in series.

The negative electrode 118 of the cell 1 disposed on the lowermost side of the battery 100 may be connected to the reference potential 119, and the measuring points A to K, which are the measurement standards of the cells (cells 1 to 11), may be It is connected to the resistors Rs 101 to 111. In this case, the resistors 101 to 111 connected to each cell may serve as a protection resistor to prevent an overcurrent from flowing in each cell when an over input voltage is applied to each cell or when each cell is shorted with a reference potential. In addition, the resistors 101 to 111 of the cells may be individually connected to the plurality of cell voltage dividers 121 to 131 constituting the cell voltage divider 120.

In this case, the cell voltage dividers 121 to 131 are voltages capable of accommodating the voltages of the cells by the plurality of resistors R1 and R2 precisely matched with the capacitor C1 at the same voltage division ratio. Can be lowered. Here, the capacitor C1 included in each cell voltage divider 121 to 131 serves as a filter for filtering the divided voltage.

The cell voltage dividers 121 to 131 are based on a reference potential 119 to which the negative electrode 118 of the lowermost cell (cell 1) is connected, and divides the reference potential and voltages of the cells. 121 through 131 may be connected to the cell voltage select multiplexer 140 so that each cell voltage may be input to the cell voltage select multiplexer 140.

In this case, the cell voltages connected to the measuring points D 'and H' of the cells 4 and 8 among the cells (cells 1 through 11) and divided by the cell voltage dividers 124 and 128 are transferred to the offset selection multiplexer 160. Can be entered.

The output terminal of the cell voltage selection multiplexer 140 is connected to the (+) side non-inverting terminal 224 of the differential amplifier 220, and the output terminal of the offset selection multiplexer 160 is connected to the differential amplifier 220. It may be connected to the (−) side inverting terminal 222. Accordingly, the differential voltage generated between the cell voltage selected by the cell voltage selection multiplexer 160 and the offset voltage selected by the offset selection multiplexer 160 may be amplified by the differential amplifier 220.

In addition, the cell voltage selection multiplexer 160 has one functional operation input terminal EN and three address input terminals ADD, and the offset selection multiplexer 160 has one functional operation input terminal EN. It may have two address input terminals ADD. In this case, any one channel of the cell voltage selection multiplexer 140 and the offset selection multiplexer 160 may be selected by the output signal of the multiplexer controller 180. The function operation input terminal of the multiplexer controller 180 may be selected. A channel corresponding to the EN and the control signal of the address input terminal ADD may be selected.

The voltage PVcell of each cell output from the differential amplifier 220 may be calculated as in Equations 1 to 11 below. In this case, in the case of a lithium ion battery, one cell voltage is at most 4.1V.

In the conventional cell voltage measuring apparatus, the offset voltage of the automatic amplifier 220 is selected by dividing the reference voltage generated by the reference voltage generator through the offset voltages of the differential amplifier 220 calculated as described above. As the cell voltage of the battery is independently selected, the measurement accuracy of the cell voltage is affected by the precision of the offset voltage set by the offset unit.

However, in the present invention, the offset selection multiplexer 160 adjusts the offset voltage of the differential amplifier 220 through each cell voltage of the battery 100, thereby maintaining a wide measurement range for each cell voltage of the battery 100. As a result, measurement accuracy can be improved.

On the other hand, SVcell that is the voltage of cells 1, 5, and 9 before filtering by using the PVcell voltage converted into digital data by the data processor 240 is calculated as shown in Equation 12 below, and the cells 2, 3, SVcell, which is the voltage of the cell 4, the cell 6, the cell 7, the cell 8, the cell 10, and the cell 11, can be calculated as shown in Equation 13. In this case, in the case of a lithium ion battery, all SVcells converted into digital data using a PVcell voltage may be maintained at a maximum of 4.1V or less.

Where N: 01, 05, 09

Where M: 02, 03, 04, 06, 07, 08, 10, 11

        N: M-1

In addition, the cell voltage FVcell filtered using the SVcell may be calculated by Equation 14 below. In this case, the filtered cell voltage FVcell may apply a simple first order filtering algorithm. First order filter algorithm, the cell voltage and the product of the filter in the filtering parameter to the cell voltage to be filtered in the next time (FVcell _{n + 1)} is the cell voltage (FVcell _n) filtering at the current time, previous time (FVcell _{n- Add 1} ) multiplied by (1-filtering parameter). When the cell voltage of the initial battery is filtered, the filtered cell voltage FVcell may set the cell voltage filtering frequency of the initial battery to track the cell voltage SVcell before filtering.

Where 0 ≤ k ≤ 1 ( k : filtering parameter)

Looking at the cell voltage measurement method using the cell voltage measuring apparatus according to the present invention configured as described above are as follows.

3 is a flowchart illustrating a method of measuring a cell voltage according to the present invention sequentially.

As shown, the cell voltage measurement method of the battery according to the present invention, first set the number of cell voltage filtering of the initial battery (step S300).

Next, the multiplexer controller 180 selects the cell voltage and the offset cell voltage of the battery 100 by the control of the multiplexer synchronization command unit 200 (step S310). In this case, the multiplexer controller 180 selects the cell voltage and the offset cell voltage. Any one of the cell voltage selection multiplexer 140 and the offset selection multiplexer 160 is selected, and the selection of the channel is a cell voltage multiplexer corresponding to the control signals of the functional operation input terminal EN and the address input terminal ADD. The channel of can be selected.

Next, the differential voltages of the cells selected by the cell voltage selection multiplexer 140 and the offset selection multiplexer 160 are amplified by the differential amplifier 220 (step S320).

Next, the PVcell voltage amplified by the differential amplifier 220 is output (step S340).

In operation S330, analog data is converted into digital data through the sample and hold unit 245 and the A / D converter 250 of the data processor 240.

Next, the PVcell voltage converted into digital data is output from the data processor 240 (step S340).

In addition, the cell voltage of the battery 100 converted into digital data is filtered (step S350), and the filtering of the cell voltage is converted into digital data and filtered using the PVcell voltage amplified by the differential amplifier 220. The SVcell, which is the previous cell voltage, may be calculated, and the filtered FVcell voltage may be calculated using the SVcell voltage. In this case, the filtered FVcell voltage may be calculated using a first order filtering algorithm and a filtering parameter.

Next, it is determined whether the number of times the cell voltage filtering processing exceeds the predetermined initial number of times battery cell voltage filtering (step S360).

At this time, if the number of times the cell voltage filtering process does not exceed the number of times the cell voltage filtering of the initial battery, the number of cells of the battery selected by the multiplexer synchronization command unit 200 is increased.

On the other hand, if the number of times the cell voltage filtering processing exceeds the set number of cell voltage filtering of the initial battery, it is determined whether the cell voltage value of the battery which has been converted into digital data and filtered exceeds the cell voltage range of the battery (step S370).

Thereafter, if the cell voltage value of the battery which is converted into digital data and filtered exceeds the range of the battery cell voltage, the filtering parameter is changed (step S380).

At this time, the cell voltage value of the battery, which is converted into digital data and filtered, does not exceed the cell voltage range of the battery, and the number of battery cells selected by the control of the multiplexer synchronization command unit is increased (step S390).

Finally, the data processor 240 outputs the filtered FVcell voltage converted to digital data (step S400).

In the above embodiment of the present invention, the cell voltage measuring apparatus of the battery capable of charging and discharging through recharging may be configured to adjust the cell voltages of the reference potentials, cells 4, 8, and the measuring points D 'and H' with respect to the battery in which 11 cells are connected in series. The circuit configuration in which the offset voltage of the differential amplifier is adjusted has been described as an example, and the present invention is not limited to the circuit configuration of the above embodiment, but may be applied to a circuit configuration that is modified or modified differently.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

100. Battery 120. Cell voltage divider
140. Cell Voltage Selection Multiplexer 160. Offset Selection Multiplexer
180. Multiplexer control unit 200. Multiplexer synchronization command unit
220. Differential amplifier 240. Data processing section
245. Sample and hold part 250. A / D conversion part

Claims (19)

In the cell voltage measuring apparatus of the battery is connected to the battery is adjusted to the offset voltage of the differential amplifier by interlocking with each cell voltage of the battery,
A cell voltage divider for lowering a voltage of each cell constituting the battery to a voltage that the differential amplifier can accommodate;
A cell voltage selection multiplexer and an offset selection multiplexer for selectively inputting differential voltages of the cells divided by the cell voltage divider;
A multiplexer controller configured to control selection of the differential voltages input to the cell voltage selection multiplexer and the offset selection multiplexer;
A multiplexer synchronization command unit configured to synchronize a selected differential voltage of each of the cells by inputting a synchronization command to the multiplexer controller;
A differential amplifier for amplifying a differential voltage input through the cell voltage selection multiplexer and an offset selection multiplexer; And
A data processor converting the battery voltage output from the differential amplifier into digital data,
The plurality of cell voltage dividers constituting the cell voltage divider may have a voltage at which the differential amplifier can receive the voltages of the cells at the same voltage division ratio by a plurality of resistors R1 and R2 that are precisely matched to the capacitor C1. Device for measuring battery cell voltage
The method of claim 1,
The data processing unit includes a sample and hold unit; And
Cell voltage measurement device of the battery further comprises an A / D converter for converting the amplified differential voltage, which is analog data into digital data.
The method of claim 1,
The battery is configured in the form of a package or module in which a plurality of cells are electrically connected and packaged in a housing, and the plurality of cells constituting the battery are cell voltage measuring devices of a battery connected in series with each other.
The method of claim 1,
The cell voltage measuring device of the battery connected to the reference potential of the negative electrode of the cell disposed on the lowermost side of the battery
delete The method of claim 1,
Capacitor C1 included in each cell voltage divider is a cell voltage measuring device of a battery serving as a filter for filtering the divided voltage.
The method of claim 1,
The output terminal of the cell voltage selection multiplexer is connected to the (+) side non-inverting terminal of the differential amplifier, and the output terminal of the offset selection multiplexer is connected to the (−) side inverting terminal of the differential amplifier. Cell voltage measuring device of a battery in which a differential voltage generated between a cell voltage selected by a multiplexer and an offset voltage selected by the offset selection multiplexer is amplified by the differential amplifier
The method of claim 7, wherein
The cell voltage selection multiplexer includes one functional operation input terminal EN and four address input terminals ADD. The offset selection multiplexer includes one functional operation input terminal EN and two address input terminals ADD. Device for measuring battery cell voltage
The method of claim 1,
Any one channel of the cell voltage selection multiplexer and the offset selection multiplexer may be selected by the output signal of the multiplexer controller, and the control signal of the function operation input terminal EN and the address input terminal ADD of the multiplexer controller may be selected. Device for measuring cell voltage of battery in which corresponding channel is selected
The method of claim 1,
The cell voltage measuring device of the battery, which is converted into digital data using the PVcell voltage amplified by the differential amplifier and the cell voltage before filtering, is calculated as in the following equations.
Equation
SV cellN = PV cellN ≤ 4.1 V
Where N: 01, 05, 09

Equation
SV cellM = PV cellM -PV cellN ≤ 4.1V
Where M: 02, 03, 04, 06, 07, 08, 10, 11
N: M-1
The method of claim 10,
The cell voltage FVcell filtered using the SVcell is calculated as in the following equation, and the filtered cell voltage FVcell is subjected to a simple first order filtering algorithm.
Equation
FV cell _{N + 1} = k × SV cell _N + (1-k) × SV cell _N-1
Where 0 ≤ k ≤ 1 ( k : filtering parameter)
Setting the number of cell voltage filtering of the initial battery;
Selecting a cell voltage and an offset cell voltage of the battery through a cell voltage selection multiplexer and an offset selection multiplexer under control of a multiplexer synchronization command unit in a multiplexer control unit;
Amplifying a differential voltage of a cell selected by the cell voltage selection multiplexer and the offset selection multiplexer by a differential amplifier;
Outputting the amplified PVcell voltage by the differential amplifier;
Converting analog data into digital data through a sample and hold part and an A / D converter of a data processor of the battery voltage differentially amplified by the differential amplifier;
Filtering the SVcell voltage converted into the digital data; And
Outputting a filtered FVcell voltage converted into digital data by the data processor;
Cell voltage measurement method of a battery comprising a.
The method of claim 12,
Selecting a cell voltage and an offset cell voltage of the battery;
Any one channel of the cell voltage selection multiplexer and the offset selection multiplexer is selected according to the output signal of the multiplexer controller, and the selection of the channel corresponds to the control signal of the function operation input terminal EN and the address input terminal ADD. And a cell voltage multiplexer and an offset selection multiplexer channel.
The method of claim 12,
In the step of filtering the SVcell voltage
The filtering of the cell voltage is performed by converting the digital data using the PVcell voltage amplified by the differential amplifier, calculating the SVcell which is the cell voltage before filtering, and using the SVcell voltage, the filtered FVcell voltage is calculated, and the filtered FVcell. A method of measuring cell voltage of a battery in which voltage is calculated using a first order filtering algorithm and filtering parameters.
The method of claim 12,
In the step of filtering the SVcell voltage of the battery,
Determining whether the number of times of filtering the cell voltage exceeds the predetermined number of times of initial battery cell voltage filtering;
Cell voltage measurement method of a battery further comprising.
16. The method of claim 15,
And increasing the number of cells of the battery selected by the multiplexer synchronizing command unit if the number of times of filtering of the cell voltage does not exceed the number of times of filtering the cell voltage of the initial battery.
16. The method of claim 15,
The method further includes determining whether the cell voltage value of the filtered battery that is converted to digital data exceeds the cell voltage range of the battery when the number of times the cell voltage filtering process exceeds the set cell voltage filtering number of the initial battery. Method for measuring cell voltage
The method of claim 12,
In the step of filtering the SVcell voltage of the battery converted into the digital data,
Changing the filtering parameter when the cell voltage value of the filtered battery exceeds the range of the divided cell voltage of the battery;
Cell voltage measurement method of a battery further comprising.
The method of claim 12,
In the step of filtering the SVcell voltage of the battery converted into the digital data,
If the cell voltage value of the filtered battery does not exceed the divided cell voltage range of the battery, increasing the number of battery cells selected by the control of the multiplexer synchronization command unit.

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