KR102390880B1 - System and method for sensing fuel cell of vehicle - Google Patents

Abstract

A fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention includes a variable ADC that converts an input voltage input to a channel connected to a fuel cell stack into bit data, and the number of cells in the fuel cell stack connected to the channel. control logic for controlling the resolution change of the variable ADC according to the present invention.

Description

SYSTEM AND METHOD FOR SENSING FUEL CELL OF VEHICLE

The present invention relates to a vehicle fuel cell sensing system and method, and for example, to a vehicle fuel cell sensing system and method for calculating an average voltage of a fuel advance cell.

Vehicles using internal combustion engines that use gasoline or heavy oil as their main fuel have a serious impact on air pollution and other pollution. Therefore, in recent years, in order to reduce pollution, much effort has been put into the development of electric vehicles or hybrid vehicles.

Among electric vehicles, a fuel cell electric vehicle (FCEV) is driven using a fuel cell stack in which a plurality of fuel cell cells are connected in series.

In the case of a fuel cell stack, unit cells constituting the fuel cell stack have an output voltage of up to 1V, and the total output voltage can be adjusted according to the number of fuel cell unit cells.

Since the voltage output from the unit cell of the fuel cell stack is very small at the level of 1V, a high-resolution ADC (Analog Digital Converter) is required to accurately detect the voltage of the unit cell.

In addition, it is spatially and physically impossible to measure the voltage of each unit cell of the fuel cell stack because the number of unit cells is large. In this case, the average voltage of multiple cells becomes the representative voltage.

1 shows an example of a fuel cell sensing system according to the prior art.

Referring to FIG. 1 , a fuel cell sensing system 10 according to the related art includes a fuel cell stack 11 , a sensing semiconductor 12 , and an operation semiconductor 13 .

The fuel cell stack 11 is connected to a channel of the sensing semiconductor 12 for each unit cell or multiple cells.

The sensing semiconductor 12 receives the voltage of the unit cell and the voltage of multiple cells of the fuel cell stack 11 through the channel. The sensing semiconductor 120 includes an ADC 12a that measures a voltage of a unit cell and a voltage of multiple cells of the fuel cell stack 110 . The ADC 12a converts the measured voltage value into bit data form and transmits it to the operation semiconductor 13 .

The operation semiconductor 13 includes an average calculation unit 13a that calculates an average voltage of a unit cell by using the transmitted bit data. The average calculating unit 13a may calculate the average voltage by dividing the received bit data based on the number of cells connected per channel.

In the fuel cell sensing system according to the prior art, when multiple cells are measured by binding two or more unit cells, when the average of the multiple cells is obtained, the accuracy is lowered unless a decimal point operation is performed, and an excessive additional circuit (MCU) for decimal point operation class) is required.

In addition, although the number of cells per channel is variable for each fuel cell stack, the number of effective bits varies according to the number of cells per channel, resulting in a difference in accuracy.

Republic of Korea Patent Publication No. 2001-0005545

Accordingly, the present invention has been devised in consideration of the above circumstances, and an object of the present invention is to provide a fuel cell sensing system and method for a vehicle in which fuel cell voltage sensing accuracy is improved.

A fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention for achieving the above object includes: a variable ADC that converts an input voltage input to a channel connected to a fuel cell stack into bit data; and the fuel connected to the channel and a control logic for controlling the change in resolution of the variable ADC according to the number of cells in the battery stack.

When the number of cells of the fuel cell stack connected to the channel is one, the control logic may change the resolution of the variable ADC to N bits (N is an integer greater than or equal to 4).

The variable ADC may convert the input voltage into N-bit data.

The control logic may change the resolution of the variable ADC to N+A bits when the number of cells in the fuel cell stack connected to the channel is at least two (2 ^A , where A is an integer of 1 or more).

The variable ADC may convert the input voltage into N+A bit data.

The control logic may obtain N-bit valid data by removing the lower A bits from the N+A bit data.

The control logic may obtain an average cell voltage of the fuel cell stack through the N-bit valid data.

The variable ADC includes a comparator that receives an input voltage from a channel connected to the fuel cell stack, a SAR logic that sequentially stores the comparator output from the most significant bit of a bit register as cycle progresses, and an output digital signal of the SAR logic. It may include a DAC that converts the analog voltage and transmits it to the comparator.

The variable ADC may be an SD-ADC whose resolution is changed by changing OSR according to the number of cells of the fuel cell stack connected to the channel.

The variable ADC may vary with a resolution capable of measuring all channels according to the maximum number of cells of the fuel cell stack connectable to the channel.

The control logic may set a register value arranged for each channel according to the number of cells of the fuel cell stack connected to the channel, and change the resolution of the variable ADC by using the set register value.

According to a preferred embodiment of the present invention for achieving the above object, there is provided a method for sensing a fuel cell for a vehicle, comprising: a bit data conversion step of converting an input voltage input to a channel connected to a fuel cell stack into bit data; a cell number counting step of calculating the number of cells of the fuel cell stack connected to the channel; and a cell average voltage obtaining step of obtaining an average cell voltage of the fuel cell stack by reducing the number of bits of the bit data based on the calculated number of cells.

The input voltage may be converted into any one of N (N is an integer of 4 or more) bit data or N+A (A is an integer of 1 or more) bit data according to the calculated number of cells.

According to the fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention, there is an effect that the fuel cell voltage sensing accuracy is improved by varying the ADC resolution according to the number of unit cells connected to the channel.

1 is a configuration diagram of a fuel cell sensing system according to the prior art.
2 is a configuration diagram of a fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention.
3 is a view for explaining an additional configuration of a fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention.
4 is a diagram for explaining 6-bit data conversion of a fuel cell voltage.
5 is a diagram for explaining 4-bit data conversion of a fuel cell voltage.
FIG. 6 is a view for explaining a first cell average voltage calculation process of the fuel cell sensing system of FIG. 2 .
FIG. 7 is a view for explaining a second cell average voltage calculation process of the fuel cell sensing system of FIG. 2 .
8 is a flowchart of a method for sensing a fuel cell for a vehicle according to a preferred embodiment of the present invention.
9 is a view showing another example of a variable ADC of a fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, it should be noted that in adding reference numerals to the components of each drawing, the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, preferred embodiments of the present invention will be described below, but the technical spirit of the present invention is not limited thereto and may be variously implemented by those skilled in the art without being limited thereto.

2 is a configuration diagram of a fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention.

Referring to FIG. 2 , a fuel cell sensing system 100 for a vehicle according to a preferred embodiment of the present invention includes a fuel cell stack 110 and a voltage sensing unit 120 .

The fuel cell stack 110 may include a plurality of cells connected in series with each other. In the fuel cell stack 110 , a different number of cells may be voltage-sensed for each channel. In one embodiment, the fuel cell stack 110 includes a lowest unit cell (uc1) composed of one cell, a lower multi-cell (mc1) composed of two cells, an upper multi-cell (mc2) composed of four cells, and an uppermost unit cell uc2.

The voltage sensing unit 120 may receive a voltage of the fuel cell stack 110 through a plurality of channels C1, C2, C3, C4, and CN.

The voltage sensing unit 120 may receive the voltage of the lowest unit cell uc1, the voltage of the lower multi-cell mc1, the voltage of the upper multi-cell mc2, and the voltage of the highest unit cell uc2 for each channel. .

The voltage sensing unit 120 may include a variable ADC 121 that converts an input voltage into bit data.

The variable ADC 121 may be a 4-bit ADC that converts an input voltage into 4-bit data. In addition, the variable ADC 121 may be changed to a 6-bit ADC to enhance detection accuracy with respect to an input voltage. The variable ADC 121 may be changed to have a larger resolution of 14 bits or more, if necessary.

Meanwhile, the variable ADC 121 may be configured as an example other than the above-described configuration. In the variable ADC 121 according to another embodiment, the resolution does not vary according to the number of cells per channel, and when the maximum number of cells that can be sensed per channel is A, a resolution capable of measuring all channels based on the resolution required for the maximum number of cells A can operate as The resolution that can measure all channels can be calculated as N+log ₂ (A) bits. After voltage sensing for all channels is performed by the variable ADC 121 , the control logic 123 may obtain N bits of resolution required per cell from the MSB to obtain a channel average voltage.

In an embodiment, when the maximum number of cells A that can be sensed per channel is 4, the variable ADC 121 may operate with 6-bit resolution. The variable ADC 121 may measure voltages of all channels with 6-bit resolution.

The control logic 123 may change the resolution of the variable ADC 121 in consideration of an input voltage for each channel or the number of cells of the fuel cell module 110 connected per channel. The control logic 123 may calculate the average voltage of the unit cells of the fuel cell stack 110 by using the bit data converted by the variable ADC 121 .

In an embodiment, the control logic 123 may set a register value arranged for each channel according to the number of cells per channel. The control logic 123 may control the variable ADC 121 using the set register value. The control logic 123 may determine the number of SAR cycles when the variable ADC 121 uses the SAR logic 121b. Also, the control logic 123 may adjust the OSR when the variable ADC 121 is a Sigma Delta (SD)-ADC (refer to FIG. 9 ).

Table 1 below shows examples of register values.

register
(Memory)
map AD[0] AD[1] number of cells per channel Ch1 0 0 unused Ch2 0 One One Ch3 One 0 2 Ch4 One One 4 pieces Ch5 One One 4 pieces …

3 is a view for explaining an additional configuration of a fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention.

Referring to FIG. 3 , in an embodiment, the variable ADC 121 includes a comparator 121a, a SAR logic 121b (Successive Approximation Register Logic), a register 121c, and a DAC 121d (Digital Analog Converter). may include

The comparator 121a compares the input voltage Vin input through the channel with the output voltage Dout of the DAC 121c. The comparator 121a outputs which voltage value is greater among the input voltage Vin and the output voltage Dout as a voltage level. The comparator 121a outputs a high-level voltage level when the input voltage Vin is greater than the output voltage Dout. The comparator 121a outputs a low-level voltage level when the input voltage Vin is less than the output voltage Dout.

The SAR logic 121b sequentially determines a comparison result as a data bit value starting with a Most Significant Bit (MSB) for each cycle.

In an embodiment, when the SAR logic 121b acquires bit data for a voltage of a unit cell in which one cell is connected to one channel, four cycles may be performed under the control of the control logic 123 . . In this case, the SAR logic 121b may acquire 4-bit data.

In an embodiment, when the SAR logic 121b acquires bit data for voltages of multiple cells in which two cells are connected to one channel, 5 cycles may be performed under the control of the control logic 123 . there is. In this case, the SAR logic 121b may acquire 5-bit data.

In an embodiment, when the SAR logic 121b acquires bit data for voltages of multiple cells in which four cells are connected to one channel, six cycles may be performed under the control of the control logic 123 . . In this case, the SAR logic 121B may acquire 6-bit data. Through this, the output resolution of the SAR logic 121b may be varied.

The register 121c may receive and store the number of cells of the fuel cell stack 110 connected for each channel from a separate controller (not shown). The number of cells for each channel stored in the register 121c may be used to control the number of cycles of the SAR logic 121b.

The DAC 121d may convert the bit data output from the SAR logic 121b into an analog voltage and output the converted bit data. The DAC 121d may transmit the output voltage Dout to the input terminal of the comparator 121a.

4 is a diagram for explaining 6-bit data conversion of a fuel cell voltage.

Referring to FIG. 4 , when one cycle is performed in the SAR logic 121b, when the input voltage Vin exceeds the output voltage Dout of the DAC 121d according to the comparison result of the comparator 121a, the SAR logic (121b) may store a 1-bit value in the most significant bit (MSB) register. In addition, when the SAR logic 121B performs two cycles, when the input voltage Vin is less than the output voltage Dout of the DAC 121d according to the comparison result of the comparator 121a, the SAR logic 121b is 0 bit The value can be stored in the bit register after the most significant bit (MSB). Thereafter, when the SAR logic 121B proceeds 3 to 6 cycles, an appropriate bit value may be stored up to the least significant bit (LSB) register based on the above description.

5 is a diagram for explaining 4-bit data conversion of a fuel cell voltage.

Referring to FIG. 5 , when one cycle is performed in the SAR logic 121b, when the input voltage Vin exceeds the output voltage Dout of the DAC 121d according to the comparison result of the comparator 121a, the SAR logic (121b) may store a 1-bit value in the most significant bit (MSB) register. In addition, when the SAR logic 121B performs two cycles, when the input voltage Vin is less than the output voltage Dout of the DAC 121d according to the comparison result of the comparator 121a, the SAR logic 121b is 0 bit The value can be stored in the bit register after the most significant bit (MSB). Thereafter, when the SAR logic 121B proceeds 3 to 4 cycles, an appropriate bit value may be stored up to a bit register excluding the two lower bits based on the above description.

FIG. 6 is a view for explaining a first cell average voltage calculation process of the fuel cell sensing system of FIG. 2 .

Referring to FIG. 6 , a process of calculating an average value of bit data obtained by the variable ADC 121 for voltages per unit cell or multiple cells of the fuel cell stack 110 can be confirmed.

In an embodiment, when the voltage Vsen of the unit cell (1Cell/Ch) connected to the channel is detected to be 0.9375V, the detected voltage may be converted into '0011' 4-bit data in the SAR logic 121b. . In this case, since the number of unit cells per channel is one, the control logic 123 may determine the 4-bit data of '0011' as the average voltage of the unit cells of the fuel cell stack 110 without additional calculation. Since the voltage per bit is approximately 0.3175V and the decimal value of '0011' is 3 in the control logic 123, the voltage per bit is multiplied by 3 to obtain an average voltage of 0.9375V of the unit cell.

In one embodiment, when the voltage Vsen of the multi-cell (2Cell/Ch) composed of two unit cells connected to the channel is detected as 1.5635V, the detected voltage is '0101' 4-bit data in the SAR logic 121b can be converted to In this case, since the number of multiple cells (2Cell/Ch) connected to the channel is two, the control logic 123 may perform a 1-bit right shift on the 4-bit data of '0101' in consideration of the number of cells per channel. . Through this, the control logic 123 may acquire 3-bit valid data of '010' except for the most significant bit, which is an invalid bit. Through this, the control logic 123 may obtain 0.625V as the average voltage Vsen of the multiple cells (2Cell/ch).

In one embodiment, when the voltage Vsen of the multi-cell (4Cell/Ch) composed of four unit cells connected to the channel is detected as 4.0625V, the detected voltage is '1101' 4-bit data in the SAR logic 121b can be converted to In this case, since the number of multi-cells (4Cell/Ch) connected to the channel is four, the control logic 123 may perform a 2-bit right shift on the 4-bit data of '1101' in consideration of the number of cells per channel. . Through this, the control logic 123 may acquire 2-bit valid data of '11' except for the upper two bits that are invalid bits. Through this, the control logic 123 may obtain 0.9375V as the average voltage Vsen of the multi-cell (4Cell/ch).

FIG. 7 is a view for explaining a second cell average voltage calculation process of the fuel cell sensing system of FIG. 2 .

Referring to FIG. 7 , a process of calculating an average value of bit data obtained by the variable ADC 121 for voltages per unit cell or multiple cells of the fuel cell stack 110 can be confirmed.

In one embodiment, when the voltage (Vsen) of the unit cell (1Cell/Ch) connected to the channel is detected as 0.9375V, the detected voltage is '0011' N in the SAR logic 121b (N is an integer greater than or equal to 4) It can be converted to bit data. Hereinafter, it will be described that N is 4. In this case, since the number of unit cells per channel is one, the control logic 123 may determine the 4-bit data of '0011' as the average voltage of the unit cells of the fuel cell stack 110 without additional calculation. Since the voltage per bit is approximately 0.3175V and the decimal value of '0011' is 3 in the control logic 123, the voltage per bit is multiplied by 3 to obtain an average voltage of 0.9375V of the unit cell.

In one embodiment, when the voltage Vsen of the multi-cell (2Cell/Ch) composed of two unit cells connected to the channel is detected as 1.5635V, the detected voltage is '01010' 4+A in the SAR logic 121b (A is an integer greater than or equal to 1) may be converted into bit data. At this time, since the number of multi-cells (2Cell/Ch) connected to the channel (2 ^A , A is 1) is 2, the control logic 123 sets 5 (4+1) of '01010' in consideration of the number of cells per channel. ) for bit data, the least significant bit can be removed. Through this, the control logic 123 may acquire 4-bit valid data of '0101' except for the most significant bit, which is an invalid bit. Through this, the control logic 123 may obtain 0.78125V as the average voltage Vsen of multiple cells (2Cell/ch). This shows that the detection accuracy of the voltage 0.78125V obtained in the second cell average voltage calculation process is higher than the voltage 0.625V obtained in the first cell average voltage calculation process of FIG. 6 .

In one embodiment, when the voltage Vsen of the multi-cell (4Cell/Ch) composed of four unit cells connected to the channel is detected as 4.0625V, the detected voltage is '110100' 4+A in the SAR logic 121b It can be converted to bit data. At this time, in the control logic 123, since the number of multi-cells (4Cell/Ch) connected to the channel is 4 (2 ^A , A is 2), 6 (4+2) of '1101000' in consideration of the number of cells per channel ), the lower two bits can be removed for bit data. Through this, the control logic 123 may obtain 4-bit valid data of '1101' except for the upper two bits that are invalid bits. Through this, the control logic 123 may obtain 1.015625V as the average voltage Vsen of multiple cells (4Cell/ch). This shows that the detection accuracy of the voltage 1.015625V acquired in the second cell average voltage calculation process is higher than the voltage 0.9375V acquired in the first cell average voltage calculation process of FIG. 6 .

In this way, when the SAR logic 121b performs 6 cycles, the input voltage can be converted into bit data form by using only the upper 4 bit data from all 6 bit data. In this case, there is an effect of the division operation without a separate right shift operation.

8 is a flowchart of a method for sensing a fuel cell for a vehicle according to a preferred embodiment of the present invention.

Referring to FIG. 8 , the method for sensing a fuel cell for a vehicle according to a preferred embodiment of the present invention may include a bit data calculation step ( S810 ), a cell number calculation step ( S820 ), and a cell average voltage obtaining step ( S830 ). there is.

In the bit data calculation step S810 , the variable ADC 121 converts an input voltage input to a channel connected to the fuel cell stack 110 into bit data.

In the cell number calculation step S820 , the control logic 123 calculates the number of cells in the fuel cell stack connected to the channel.

In the cell average voltage obtaining step S830 , the control logic 123 reduces the number of bits of bit data based on the calculated number of cells to obtain the cell average voltage of the fuel cell stack 110 . The control logic 123 may change the resolution of the ADC 121 based on the previously calculated number of cells. The ADC 121 may convert the input voltage into 4-bit data to 6-bit data according to the changed resolution. The control logic 123 may determine the number of bit reductions according to the calculated number of cells, and may reduce the number of bits of bit data output from the ADC 121 through the determined number of bit reductions.

9 is a view showing another example of a variable ADC of a fuel cell sensing system for a vehicle according to a preferred embodiment of the present invention.

Referring to FIG. 9 , the variable ADC 121 may be an SD-ADC. The variable ADC 121 may include a filter unit 121a and a modulation unit 121b.

In FIG. 9A , the filter unit 121a may filter the frequency ( ^A HZ) of the input voltage and convert it into 2K·log2(OSR) bit data. Here, K may be an integer between 1 and 3. An oversampling rate (OSR) may be an exponent of 2. OSR may be adjusted according to the number of cells per channel (N). The adjusted OSR may vary the operating speed of the modulator 121b. The modulator 121b may change the resolution of the variable ADC 121 through a variable operating speed.

In FIG. 9B , when the number of cells per channel is one, the variable ADC 121 may operate at a low resolution. The input voltage may be converted into 15-bit data by the filter unit 121a. In this case, the OSR may be adjusted to 32. A frequency of 1 kHz of the input voltage may be frequency-modulated to 32 kHz by the modulator 121b. The control logic 123 may obtain upper 4-bit data from 15-bit data to obtain a cell average voltage.

In FIG. 9C , the variable ADC 121 may operate at a high resolution when the number of cells per channel is four. The input voltage may be converted into 18-bit data by the filter unit 121a. In this case, the OSR may be adjusted to 64. The frequency of the input voltage of 1 kHz may be frequency-modulated by the modulator 121b to 64 kHz. The control logic 123 may obtain upper 4-bit data from 18-bit data to obtain a cell average voltage.

When the variable ADC 121 has a low resolution, power consumption is reduced and a sensing time is reduced.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various modifications, changes and substitutions within the scope without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are for explaining, not limiting, the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments and the accompanying drawings .

Steps and/or operations according to the present invention may occur concurrently in different embodiments, either in a different order, or in parallel, or for different epochs, etc., as would be understood by one of ordinary skill in the art. can

Depending on the embodiment, some or all of the steps and/or operations run instructions, a program, an interactive data structure, a client and/or a server stored in one or more non-transitory computer-readable media. At least some may be implemented or performed using one or more processors. The one or more non-transitory computer-readable media may be illustratively software, firmware, hardware, and/or any combination thereof. Further, the functionality of a “module” discussed herein may be implemented in software, firmware, hardware, and/or any combination thereof.

100: vehicle fuel cell sensing system
110: fuel cell stack
120: voltage sensing unit
121: variable ADC
121a: comparator
121b: SAR logic
121c: register
121d: DAC
123: control logic

Claims (13)

A variable ADC that converts an input voltage input to a channel connected to the fuel cell stack into bit data: and
a control logic for controlling a resolution change of the variable ADC according to the number of cells of the fuel cell stack connected to the channel; and
The control logic, when the number of cells of the fuel cell stack connected to the channel is one, changes the resolution of the variable ADC to N bits (N is an integer greater than or equal to 4) bits;
When the number of cells of the fuel cell stack connected to the channel is at least two or more (2 ^A , A is an integer of 1 or more), the resolution of the variable ADC is changed to N+A bits. sensing system. delete The method of claim 1,
The variable ADC converts the input voltage into N-bit data when the number of cells in the fuel cell stack connected to the channel is one. delete The method of claim 1,
The variable ADC converts the input voltage into N+A bit data when the number of cells in the fuel cell stack connected to the channel is at least two or more (2 ^A , A is an integer of 1 or more) A fuel cell sensing system for vehicles. 6. The method of claim 5,
wherein the control logic is configured to obtain N-bit valid data by removing the lower A bits from the N+A-bit data. 7. The method of claim 6,
and the control logic acquires the cell average voltage of the fuel cell stack through the N-bit valid data. The method of claim 1,
The variable ADC,
a comparator receiving an input voltage from a channel connected to the fuel cell stack;
SAR logic that sequentially stores the comparator output as the cycle progresses, starting with the most significant bit of a bit register, and
DAC that converts the output digital signal of the SAR logic into an analog voltage and transmits it to the comparator
A vehicle fuel cell sensing system comprising a. The method of claim 1,
The variable ADC,
The fuel cell sensing system for a vehicle according to claim 1, wherein the OSR is variable according to the number of cells of the fuel cell stack connected to the channel and the resolution is changed. The method of claim 1,
The variable ADC,
A fuel cell sensing system for a vehicle, characterized in that the resolution of all channels is varied according to the maximum number of cells of the fuel cell stack connectable to the channel. The method of claim 1,
wherein the control logic sets a register value arranged for each channel according to the number of cells of the fuel cell stack connected to the channel, and changes the resolution of the variable ADC by using the set register value. sensing system. a bit data conversion step of converting an input voltage input to a channel connected to the fuel cell stack into bit data;
a cell number counting step of calculating the number of cells of the fuel cell stack connected to the channel; and
a cell average voltage obtaining step of reducing the number of bits of the bit data based on the calculated number of cells, and obtaining an average cell voltage of the fuel cell stack through the reduced bit data;
A vehicle fuel cell sensing method comprising a. 13. The method of claim 12,
The input voltage is converted into any one of N (N is an integer greater than or equal to 4) bit data to N+A (A is an integer greater than or equal to 1) bit data according to the calculated number of cells.

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