Battery unit

Abstract

To provide a battery unit capable of reducing noise included in a temperature measurement result while suppressing a circuit scale.SOLUTION: A battery unit of the present invention includes: a battery stack in which a plurality of battery cells are stacked in a lamination direction; an end plate provided on both ends of the battery stack in the lamination direction; a positive temperature characteristic thermistor provided in contact with the first battery cell located on the end plate side in the battery stack and having positive resistance characteristics in which a resistance value increases as temperature increases; and a negative temperature characteristic thermistor provided in contact with the second battery cell located on a center side of the first battery cell in the battery stack and having negative resistance characteristics in which the resistance value decreases as temperature increases.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to, for example, a battery unit configured such that a plurality of battery cells are stacked in a stacking direction. [Background technology]

[0002] In an assembled battery in which multiple battery cells are combined and used as one battery, multiple battery cells arranged in one direction (for example, the stacking direction) are restrained by applying pressure from both ends in the stacking direction to form a battery stack. In such a battery stack, it is necessary to measure the temperature of the battery cells to keep the battery performance within a certain range. Therefore, an example of a battery temperature measurement technology for an assembled battery is disclosed in Patent Document 1.

[0003] The battery control device described in Patent Document 1 is equipped with a plurality of temperature sensors that detect the temperature of an assembled battery formed by connecting a plurality of battery modules in series, a drive circuit unit having one end connected to the temperature sensor and applying a drive voltage to the temperature sensor, a filter circuit unit connected to the other end of the drive circuit unit and removing noise, and a microcomputer that is connected to the temperature sensor via the drive circuit unit and the filter circuit unit and controls the assembled battery based on the temperature signal input from the temperature sensor, and further includes a multiplexer whose input side is switchably connected to the plurality of temperature sensors and whose output side is connected to the microcomputer via at least one of the drive circuit unit and the filter circuit unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-224071 A Summary of the Invention [Problem to be solved by the invention]

[0005] When measuring the temperature of a battery cell, noise contained in the measurement results can be an issue, and Patent Document 1 addresses this issue by providing a filter circuit section. However, adding a component such as a filter circuit section increases the number of components and increases the volume of the device, which can be problematic.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to reduce noise contained in temperature measurement results while suppressing the circuit scale. [Means for solving the problem]

[0007] One embodiment of a battery unit according to the present invention comprises a battery stack in which a number of battery cells are stacked in a stacking direction, end plates provided at both ends of the battery stack in the stacking direction, a positive temperature characteristic thermistor provided in contact with a first battery cell located on the end plate side in the battery stack and having positive resistance characteristics in which the resistance value increases with increasing temperature, and a negative temperature characteristic thermistor provided in contact with a second battery cell located more centrally than the first battery cell in the battery stack and having negative resistance characteristics in which the resistance value decreases with increasing temperature. Effect of the Invention

[0008] According to the battery unit of the present invention, it is possible to reduce noise contained in the temperature measurement result while suppressing the circuit scale. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a battery unit according to a first embodiment. [Diagram 2] 4 is a graph illustrating a temperature distribution of the battery unit according to the first embodiment. [Diagram 3] 4 is a block diagram of a temperature detection circuit corresponding to a low temperature range temperature sensor of the battery unit according to the first embodiment. FIG. [Figure 4] 4 is a block diagram of a temperature detection circuit corresponding to a high temperature range temperature sensor of the battery unit according to the first embodiment. FIG. [Diagram 5] FIG. 11 is a schematic diagram of a battery unit according to a second embodiment. [Figure 6] FIG. 11 is a schematic diagram of a battery unit according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In addition, in each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0011] First embodiment Fig. 1 shows a schematic diagram of a battery unit 1 according to the first embodiment. As shown in Fig. 1, the battery unit 1 according to the first embodiment has a battery stack in which multiple battery cells are stacked in one direction (for example, the stacking direction). Furthermore, in the battery unit 1, end plates are provided on both ends of the battery stack in the stacking direction, and the stacked battery cells are constrained in a state in which a compressive force in the stacking direction is applied to the stacked battery cells via the end plates.

[0012] In addition, in the battery unit 1 shown in Fig. 1, a battery module is formed in which multiple battery cells are arranged in a direction perpendicular to the stacking direction, and multiple battery modules are stacked in the stacking direction to form a battery stack. In Fig. 1, one battery module includes six battery cells. In the following explanation, the rows of battery cells that are arranged at the same position in the stacking direction among the battery cells included in each battery module are referred to as the first cell row to the sixth cell row.

[0013] Here, the temperature distribution of the battery unit 1 shown in Fig. 1 will be described. Fig. 2 shows a graph illustrating the temperature distribution of the battery unit according to the first embodiment. As shown in Fig. 2, in the battery unit 1, the closer to the end plate, the lower the battery temperature. LowIt can be seen that the battery temperature is higher in the center of the stacking direction of the battery stack. This tendency is the same for all cell rows. When multiple battery cells are stacked, the closer to the center of the stacking direction, the less heat is dissipated from adjacent battery cells or adjacent areas, so heat tends to build up and become hotter.

[0014] Therefore, as shown in FIG. 1, in the battery unit 1 of the first embodiment, a cell having a low temperature range temperature sensor that prioritizes measurement accuracy in the low temperature range is installed in a first cell where the battery generates less heat, and a cell having a high temperature range temperature sensor that prioritizes measurement accuracy in the high temperature range is installed in a second cell where the battery generates less heat.

[0015] The first battery cell is a battery cell located on the end plate side in the battery stack. The second battery cell is a battery cell arranged closer to the center than the first battery cell in the battery stack. In the example shown in FIG. 1, the battery cell in contact with the end plate is set as the first cell which is the low temperature range temperature sensor installation cell, and the battery cell near the center in the stacking direction is set as the second cell which is the high temperature range temperature sensor installation cell. Note that the first cell The first battery cell does not necessarily have to be in contact with the end plate, but may be located closer to the end plate than the second cell. Also, the second battery cell may be located farther from the end plate than the first battery cell, and closer to the center than the first battery cell.

[0016] The battery unit 1 according to the first embodiment uses, as the low temperature range temperature sensor, a positive temperature coefficient thermistor (hereinafter referred to as a PTC (Positive Temperature Coefficient) thermistor) having a positive resistance characteristic in which the resistance value increases with an increase in temperature. The battery unit 1 according to the first embodiment uses, as the high temperature range temperature sensor, a negative temperature coefficient thermistor (hereinafter referred to as an NTC (Negative Temperature Coefficient) thermistor) having a negative resistance characteristic in which the resistance value decreases with an increase in temperature. The battery unit 1 according to the first embodiment has a temperature detection circuit corresponding to the PTC thermistor and a temperature detection circuit corresponding to the NTC thermistor.

[0017] Fig. 3 shows a block diagram of a temperature detection circuit 10 corresponding to the low temperature range temperature sensor of the battery unit 1 according to the first embodiment. As shown in Fig. 3, the temperature detection circuit 10 corresponding to the low temperature range temperature sensor has a PTC thermistor Rtp whose resistance value changes with temperature. The PTC thermistor Rtp has a positive temperature characteristic in which the resistance value increases as the temperature rises. In other words, the resistance value of the PTC thermistor Rtp becomes low on the low temperature side.

[0018] One end of the PTC thermistor Rtp is connected to a ground wire, and the other end is given a power supply voltage via a first resistor R11. In the temperature detection circuit 10, a first detection voltage VL output from a connection point between the PTC thermistor Rtp and the first resistor R11 is converted into a digital value by the voltage detection circuit 11. In the temperature detection circuit 10, a temperature corresponding to the magnitude of the first detection voltage VL as a digital value output by the voltage detection circuit 11 is calculated by the voltage-temperature conversion circuit 12. The temperature information calculated by the voltage-temperature conversion circuit 12 is transmitted to a higher-level system and used to control the battery pack.

[0019] Next, Fig. 4 shows a block diagram of the temperature detection circuit 20 corresponding to the high temperature range temperature sensor of the battery unit 1 according to the first embodiment. As shown in Fig. 4, the temperature detection circuit 20 corresponding to the low temperature range temperature sensor has an NTC thermistor Rtn whose resistance value changes with temperature. The NTC thermistor Rtn has negative temperature characteristics in which the resistance value decreases as the temperature increases. In other words, the resistance value of the NTC thermistor Rtn decreases on the high temperature side.

[0020] One end of the NTC thermistor Rtn is connected to a ground wiring, and the other end is given a power supply voltage via a second resistor R21. In the temperature detection circuit 20, the second detection voltage VH output from the connection point between the NTC thermistor Rtn and the second resistor R21 is converted into a digital value by the voltage detection circuit 21. In the temperature detection circuit 20, the voltage-temperature conversion circuit 22 calculates a temperature corresponding to the magnitude of the digital value of the second detection voltage VH output by the voltage detection circuit 21. The temperature information calculated by the voltage-temperature conversion circuit 22 is transmitted to a higher-level system and used for controlling the battery pack. The voltage detection circuit 21 and the voltage-temperature conversion circuit 22 may be circuits built into one semiconductor device together with the voltage detection circuit 11 and the voltage-temperature conversion circuit 12.

[0021] As explained above, in the battery unit 1 of embodiment 1, the temperature of the battery cells on the end plate side of the battery stack, where the temperature is relatively low, is detected using a PTC thermistor, and the temperature of the battery cells located in the central part of the battery stack, where the temperature is relatively high, is detected using an NTC thermistor.

[0022] That is, in the battery unit 1 according to the first embodiment, the temperature detection circuit 10, which requires particularly high accuracy in temperature detection, uses a PTC thermistor Rtp that has a low resistance value in the low temperature range of the detection target. As a result, in the temperature detection circuit 10, the resistance value of the first resistor R11 for obtaining the first detection voltage VL in the temperature range in which high accuracy in temperature detection is required can be reduced. On the other hand, in the battery unit 1 according to the first embodiment, the temperature detection circuit 20, which requires particularly high accuracy in temperature detection, uses an NTC thermistor Rtn that has a low resistance value in the high temperature range of the detection target. As a result, in the temperature detection circuit 20, the resistance value of the second resistor R21 for obtaining the second detection voltage VH in the temperature range in which high accuracy in temperature detection is required can be reduced. And, by reducing the resistance values ​​of both the first resistor R11 and the second resistor R21 in this way, in the battery unit 1, the impedance of the detection section consisting of a series circuit of a thermistor and a resistor can be kept low, and therefore noise superimposed on the detection result can be suppressed. That is, in the battery unit 1 according to the first embodiment, a low-noise measurement result can be obtained without additional circuits or processing.

[0023] Here, the first resistor R11 and the second resistor R21 will be described in more detail. For example, when only a PTC thermistor is used as the thermistor for temperature detection, it is necessary to increase the resistance value of the second resistor R21 of the temperature detection circuit 20 in order to ensure the linearity of the detection voltage on the high temperature side. On the other hand, when only an NTC thermistor is used as the thermistor for temperature detection, it is necessary to increase the resistance value of the first resistor R11 of the temperature detection circuit 10 in order to ensure the linearity of the detection voltage on the low temperature side. In this way, when only a thermistor with one type of temperature characteristic is used as the thermistor for temperature detection, it is necessary to increase the resistance value of the pull-up resistor (for example, the first resistor R11 or the second resistor R21) of either the temperature detection circuit 20, which requires detection accuracy on the high temperature side, or the temperature detection circuit 10, which requires detection accuracy on the low temperature side, and this causes a problem that the impedance of the detection unit including the thermistor increases and the noise superimposed on the measurement result increases. However, in the battery unit 1 according to the first embodiment, such noise can be suppressed by combining a PTC thermistor and an NTC thermistor according to the temperature range to be detected.

[0024] In the above embodiment, an example has been described in which PTC thermistors are arranged at two points separated from each other on both ends of the battery stack, and one NTC thermistor is arranged for the battery stack. However, the PTC thermistor can also be arranged at only one of the two ends of the battery stack.

[0025] Embodiment 2 Another embodiment of a battery stack included in a battery unit will be described in the second embodiment. A schematic diagram of a battery unit 2 according to the second embodiment is shown in FIG.

[0026] As shown in Fig. 5, the battery unit 2 according to the second embodiment does not constitute a module in which a plurality of battery cells are combined, but constitutes a battery stack by stacking a plurality of battery cells in a row. In this battery unit 2 as well, end plates are provided at both ends of the battery stack. And in the second embodiment as well, a PTC thermistor is provided so as to contact a first battery cell located on the end plate side in the battery stack, and an NTC thermistor is provided so as to contact a second battery cell arranged closer to the center than the first battery cell in the battery stack. Also in the example shown in Fig. 5, as in Fig. 1, PTC thermistors are provided at two points separated from each other on both ends of the battery stack, and one NTC thermistor is provided near the center of the battery stack.

[0027] In this way, even if the shape of the battery stack changes, by providing a PTC thermistor in the battery cells that tend to be cold and are located at both ends in the stacking direction of the battery stack, and by providing an NTC thermistor in the battery cell that tends to be hot and is located near the center of the battery stack, the battery unit 2 in embodiment 2 can achieve the effect of reducing noise superimposed on the measurement results, just like battery unit 1 in embodiment 1, without adding any circuits or components.

[0028] Third embodiment Another embodiment of a battery stack included in a battery unit will be described in the third embodiment. A schematic diagram of a battery unit 3 according to the third embodiment is shown in FIG.

[0029] As shown in Fig. 6, in the battery unit 3 according to the third embodiment, the battery stack is sandwiched between a pair of different end plates, and is configured with a battery stack having multiple battery blocks (battery blocks B1, B2 in Fig. 6) in which multiple battery cells are stacked in the stacking direction. In each of the battery blocks B1, B2, a PTC thermistor is disposed in the battery cell at the stack end (area adjacent to the end plate), and an NTC thermistor is disposed in the battery cell near the center of the stack.

[0030] In this way, even if the battery stack is divided, by providing a PTC thermistor in the battery cell which tends to be cold and is located at both ends in the stacking direction of each divided battery stack, and providing an NTC thermistor in the battery cell which tends to be hot and is located near the center of the battery stack, the battery unit 3 in embodiment 3 can achieve the effect of reducing noise superimposed on the measurement results, just like the battery unit 1 in embodiment 1, without adding any circuits or components.

[0031] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0032] 1~3 Battery Unit 10, 20 Temperature detection circuit 11, 21 Voltage detection circuit 12, 22 Voltage temperature conversion circuit Rtp PTC Thermistor Rtn NTC thermistor R11 First Resistor R21 Second Resistor

Claims

1. a battery stack in which a plurality of battery cells are stacked in a stacking direction; end plates provided at both ends of the battery stack in a stacking direction; a positive temperature coefficient thermistor provided in the battery stack so as to be in contact with a first battery cell located on the end plate side, the positive temperature coefficient thermistor having a positive resistance characteristic in which a resistance value increases as temperature increases; a negative temperature coefficient thermistor provided in contact with a second battery cell disposed in the battery stack closer to the center than the first battery cell, the negative temperature coefficient thermistor having a negative resistance characteristic in which a resistance value decreases as temperature increases; A battery unit having

2. the negative temperature characteristic thermistor has one end connected to a ground line and the other end receiving a power supply voltage via a first resistor, and outputs a first detection voltage from a connection point between the negative temperature characteristic thermistor and the first resistor; the positive temperature coefficient thermistor has one end connected to the ground wiring and the other end to which the power supply voltage is applied via a second resistor, and a second detection voltage is output from a connection point between the positive temperature coefficient thermistor and the second resistor; 2. The battery unit according to claim 1, further comprising a temperature detection circuit that calculates a temperature of the battery cell in which the negative temperature characteristic thermistor is installed and a temperature of the battery cell in which the positive temperature characteristic thermistor is installed based on the first detection voltage and the second detection voltage.

3. 3 . The battery unit according to claim 1 , wherein the positive temperature characteristic thermistors are disposed at two points spaced apart from each other on both ends of the battery stack, and one negative temperature characteristic thermistor is disposed for the battery stack.

4. the battery stack includes a plurality of battery blocks sandwiched between different pairs of the end plates, each of which has a plurality of the battery cells stacked in the stacking direction; 3. The battery unit according to claim 1, wherein each of the battery blocks includes two of the positive temperature coefficient thermistors and one of the negative temperature coefficient thermistors.

5. The battery unit according to claim 1 , wherein the battery stack has a configuration in which battery modules, each of which has a plurality of the battery cells arranged in a direction perpendicular to the stacking direction, are arranged in the stacking direction.

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