JP3709859B2 - Battery temperature detector for thin batteries - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting the temperature of an assembled battery composed of a thin battery such as a laminated battery.
[0002]
[Prior art]
An example of an assembled battery configured using a plurality of single cells is disclosed in Japanese Patent Application Laid-Open No. 2001-266825. In the assembled battery according to the above publication, cylindrical unit cells (battery cells) are arranged in the battery case at predetermined intervals. The temperature of the assembled battery is detected by a temperature sensor disposed on the surface of the unit cell.
[0003]
[Problems to be solved by the invention]
A thin laminate battery having a laminate structure is known. When this laminated battery is used in place of a cylindrical battery and an assembled battery is constituted by a plurality of laminated batteries, it is difficult to dispose a temperature sensor on the surface of the single battery as in the prior art. That is, since the laminated battery is disposed with a predetermined size and a predetermined pressure, disposing the temperature sensor on the surface of the laminated battery obstructs the fixed dimension and the constant pressure. Furthermore, if the temperature sensor is disposed on the surface of the laminated battery, the surface layer of the battery may be damaged.
[0004]
An object of the present invention is to provide a temperature detection device for a battery pack composed of a thin battery in which the temperature of the unit cell is obtained from the temperature detected outside the surface of the unit cell.
[0005]
[Means for Solving the Problems]
The present invention relates to a temperature detection device for detecting the temperature of an assembled battery composed of a plurality of thin cells, and is provided with a heat conduction member that supports the cells so as to sandwich the cells and conducts heat from the cells. A temperature detecting means is disposed on the member, and the temperature of the unit cell is obtained by calculation using the temperature detected by the temperature detecting means.
[0006]
【The invention's effect】
According to the present invention, in the voltage detection device for a battery pack composed of thin single cells, the temperature of the single cells can be obtained from the temperature detected outside the surface of the single cells.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall configuration diagram of a vehicle equipped with an assembled battery temperature detection device according to an embodiment of the present invention. In the following embodiments, an example in which an assembled battery is applied as a power source for an electric vehicle will be described. In FIG. 1, the vehicle control system includes a vehicle system and a battery control unit. A thick solid line in the figure represents a high-power line (high-power wiring), and a normal solid line represents a low-power line (weak-power wiring). A broken line indicates a signal line transmitted / received between the blocks.
[0008]
The vehicle system includes a current sensor 201, a voltage sensor 202, a temperature sensor 203, a cooling FAN 204, a cooling air temperature sensor 205, a driving motor 301, an auxiliary machine system 302, and main relays 303A and 303B. . The assembled battery is composed of single cells (cells) C1 to Cn. The battery control unit includes a battery temperature detection unit 101 and a CPU 102.
[0009]
The drive motor 301 generates driving power for the vehicle by power supplied from the assembled battery, while generating regenerative power for the assembled battery. The auxiliary machine system 302 drives an air conditioner (A / C) (not shown) mounted on the vehicle by the electric power supplied from the assembled battery. The main relays 303 </ b> A and 303 </ b> B are controlled to be opened and closed by a command from the CPU 102, and turn on / off the power supply to the drive motor 301 and the auxiliary machine system 302.
[0010]
The current sensor 201 detects a current flowing through the high power line and sends a detection signal to the CPU 102. The voltage sensor 202 detects the voltage (total voltage) of the assembled battery and sends a detection signal to the CPU 102. A predetermined number of temperature sensors 203 are provided for the assembled battery, and each temperature detection signal is sent to the battery temperature detection unit 101. The cooling FAN 204 is driven and controlled by a command from the CPU 102 to cool the assembled battery. The cooling air temperature sensor 205 detects the air temperature by the cooling FAN 204 and sends a detection signal to the CPU 102.
[0011]
The temperature detection unit 101 collects temperature detection signals from the temperature sensor 203 to obtain the temperature of the assembled battery, and sends temperature information of the assembled battery to the CPU 102. CPU 102 uses the temperature information of the assembled battery and the air temperature information from cooling air temperature sensor 205 to calculate the duty ratio of cooling FAN 204 so that the temperature of the assembled battery falls within a predetermined temperature range, and sends a cooling command to cooling FAN 204. Send it out. The duty ratio is a control amount for the cooling FAN 204, and the air volume by the FAN 204 is adjusted according to the duty ratio. CPU102 notifies vehicle system CPU304 of temperature abnormality, when the temperature of an assembled battery is abnormal.
[0012]
The vehicle system CPU 304 controls the vehicle system by limiting the output of power output to the drive motor 301 and the auxiliary system 302 and limiting the regeneration of power regenerated from the drive motor 301. The vehicle warning lamp 305 is turned on by a command from the vehicle system CPU 304 and notifies the driver of the occurrence of an abnormality in the vehicle system. The auxiliary battery 401 supplies power to the CPU 102 and the vehicle system CPU 304. The switch SW turns on / off the power supply from the auxiliary battery 401 in conjunction with turning on / off of the ignition (IGN) switch 402 by the driver.
[0013]
FIG. 2 is a diagram illustrating the structure of the assembled battery. In FIG. 2, thin cells C1 and C2 made of a laminated battery or the like are placed at predetermined positions on the positioning plate 21. Similarly, the cells C3 and C4 are placed at predetermined positions on the positioning plate 22. The positioning plates 21 and 22 are supported at predetermined intervals by the heat sinks 41 and 42. The distance between the positioning plates 21 and 22 is set according to the size of the unit cell. Thereby, each single cell is arrange | positioned by a predetermined dimension and a predetermined pressure. The unit cell is formed by laminating a negative electrode material coated with a negative electrode active material from the front and back surfaces of the negative electrode foil and a positive electrode material coated with a positive electrode active material from the front and back surfaces of the positive electrode foil through a separator, respectively. It is laminated with a thin film to form a thin plate.
[0014]
In the example of FIG. 2, the structure of two stages from the single cells C <b> 1 to C <b> 4 has been described, but the number of stages constituting the assembled battery and the number of single cells placed on the same stage are the specifications of the assembled battery, respectively. It is set appropriately according to Further, in the actual assembled battery, a bus bar for connecting the single cells of each stage in parallel, a bus bar for interstage connection for connecting the stages in series, and the like are provided, but are omitted in FIG. The bus bar is an example of a high-power wiring member. The positioning plates 21 and 22 also serve as heat sinks that contact the surface layers of the unit cells C1 to C4 to absorb heat generated by the unit cells and transmit the heat to the heat sinks 41 and 42.
[0015]
The heat sinks 41 and 42 are provided with temperature sensors 2031 to 2034, respectively. Each temperature sensor detects the temperature of the point at which each sensor is provided on the heat sinks 41 and 42. The temperature sensors 2031 to 2034 are constituted by, for example, thermistors. Each temperature sensor is connected to a battery temperature detection unit 101 (FIG. 1), and the battery temperature detection unit 101 obtains the temperature at the point where the temperature sensor is provided from the resistance value of each temperature sensor (thermistor). The relationship between the temperature of the thermistor and the resistance value is stored in the battery temperature detection unit 101 in advance. The cooling air from the cooling FAN 204 (FIG. 1) described above is configured to be blown toward the heat sinks 41 and 42. When the cooling air hits the heat sinks 41 and 42, the assembled battery is cooled. The cooling air temperature sensor 205 (FIG. 1) is configured to detect the air temperature before reaching the heat sinks 41 and 42.
[0016]
The present invention is characterized by temperature detection of the assembled battery.
[0017]
FIG. 3 is a flowchart for explaining the flow of the assembled battery temperature detection process performed by the CPU 102. The process according to FIG. 3 is repeatedly performed when power is supplied from the auxiliary battery 401 to the CPU 102. The auxiliary battery 401 supplies power to the CPU 102 when the system is started (IGN is on) or when the assembled battery is charged. When the vehicle has finished traveling (IGN off) and the assembled battery is not charged, the processing in FIG. 3 is completed.
[0018]
In step S1 of FIG. 3, the CPU 102 sends a heat sink temperature detection command to the battery temperature detection unit 101, and proceeds to step S2. Thereby, the battery temperature detection part 101 calculates | requires the temperature of each point of a heat sink from the resistance value of each temperature sensor, and sends it out to CPU102.
[0019]
In step S2, the CPU 102 estimates a cell temperature (battery temperature). The cell temperature BT is calculated by the following equation (1).
[Expression 1]
BT = HT + ΔBT (1)
Here, HT is the heat sink temperature included in the temperature information sent from the battery temperature detection unit 101, and ΔBT is the temperature difference between the heat sink temperature and the cell temperature.
[0020]
FIG. 4 is an enlarged view of the vicinity of the unit cell C2 of FIG. Since the temperature sensor 2032 is disposed at a position away from the unit cell C2, a difference occurs between the surface temperature of the unit cell C2 and the temperature detected by the temperature sensor 2032. Since the heat generated in the unit cell C2 is transferred to the heat sink 41 via the positioning plate 21 (also serving as a heat sink) in contact with the unit cell C2, the heat sink temperature HT is usually lower than the surface temperature of the unit cell C2. . Here, the heat sink temperature HT is a temperature at a point where the temperature sensor 2032 is provided.
[0021]
FIG. 5 is a diagram showing the relationship between the position in the left-right direction and the temperature in the heat sink (positioning plate 21 and heat sink 41). The horizontal axis represents the position on the heat sink, and the vertical axis represents the temperature on the heat sink when the FAN duty of the cooling FAN 204 is X%. In FIG. 5, the temperature is substantially constant in the left-right direction of the positioning plate 21 and decreases as the heat sink 41 is approached. The temperature at the point A corresponding to the position of the temperature sensor 2032 corresponds to the heat sink temperature HT described above. The cell temperature BT is a temperature corresponding to the point B at the center of the unit cell C2. The cooling air temperature detected at the position C on the right side of the heat sink 41 corresponds to the outside air temperature. That is, the cooling air temperature sensor 205 is disposed so as to correspond to the position C.
[0022]
FIG. 6 is a diagram showing the relationship between the position of the heat sink (positioning plate 21 and heat sink 41) and the temperature when the FAN duty is 1.2 ×%. Compared to FIG. 5, the rate of temperature decrease increases at a position closer to the heat sink 41. That is, the higher the FAN duty is, the higher the cooling effect is, so that the difference ΔBT between the cell temperature BT and the heat sink temperature HT increases.
[0023]
FIG. 7 shows a table in which temperature data as shown in FIG. 5 and FIG. 6 is collected for each of a plurality of conditions and ΔBT in each condition is mapped. In the example of FIG. 7, when the outside air temperature is 0 degrees, 10 degrees, 20 degrees, 30 degrees and 40 degrees, the temperature difference when the FAN duty is 0, 0.25, 0.5, 0.75 and 1 respectively. ΔBT is shown. The map data in FIG. 7 is measured in advance as experimental data and stored in the memory in the CPU 102.
[0024]
The CPU 102 reads ΔBT from the map of FIG. 7 according to the outside air temperature by the cooling air temperature sensor 205 and the calculated FAN duty, and estimates the cell temperature using this ΔBT and the temperature information by the battery temperature detecting unit 101. The map data in FIG. 7 may be provided with a plurality of sets of data for each cell (unit cell) whose temperature is estimated, or only one set of data may be provided when each cell can be used in common. If CPU102 estimates the temperature of each single cell by the above Formula (1), it will progress to step S3.
[0025]
In step S3, the CPU 102 sets an abnormal temperature value and proceeds to step S4. The abnormal temperature value is, for example, a value that is 1σ larger than the average value of the estimated temperatures of the individual cells. Here, σ is a standard deviation. When the CPU 102 sets an abnormal temperature value (abnormal determination value), the process proceeds to step S4. In step S4, the CPU 102 determines whether or not the cell temperature is abnormal. If the cell temperature is normal, the CPU 102 makes a negative determination in step S4 and proceeds to step S5. If the cell temperature is abnormal, the CPU 102 makes a positive determination in step S4 and proceeds to step S6.
[0026]
FIG. 8 is a diagram illustrating an example of a normal cell temperature distribution. In FIG. 8, the horizontal axis represents the position on the heat sink 41, and the vertical axis represents the estimated cell temperature. For example, in the case where an assembled battery is configured by six unit cells, two unit cells are placed side by side on one positioning plate as shown in FIG. When stacked, an assembled battery of six unit cells is obtained. Although two stages are shown in FIG. 2, it is assumed that a positioning plate 23 (not shown) on which the cells C5 (not shown) and C6 (not shown) are placed is further stacked on the lower stage of the positioning plate 22. The temperature sensor is omitted on the heat sink 42 side, and is disposed only on the heat sink 41 side. In this case, the heat sink temperature HT is obtained at three points by three temperature sensors, ie, the upper temperature sensor 2032, the middle temperature sensor 2034, and the lower temperature sensor 2036 (not shown).
[0027]
A point plotted on the “upper” side of the module position on the horizontal axis in FIG. 8 is a heat sink temperature HT corresponding to the temperature sensor 2032. The point plotted on the “bottom” side of the module position is the heat sink temperature HT corresponding to the temperature sensor 2036 (not shown). The point plotted in the center of both is the heat sink temperature HT corresponding to the temperature sensor 2034. The cell temperatures of the single cells C1 and C2 are calculated using the heat sink temperature HT corresponding to the temperature sensor 2032. The cell temperatures of the cells C3 and C4 are calculated using the heat sink temperature HT corresponding to the temperature sensor 2034. The cell temperatures of the cells C5 (not shown) and C6 (not shown) are calculated using the heat sink temperature HT corresponding to the temperature sensor 2036 (not shown). In this case, the map data of FIG. 7 is prepared for each of the cells C1 to C6.
[0028]
If all of the estimated cell temperature values (estimated battery temperature) corresponding to the cells C1 to C6 are lower than the estimated abnormality determination value, the CPU 102 determines that the cell temperature distribution is normal and makes a negative determination in step S4 described above. . On the other hand, when at least one of the estimated cell temperature values (estimated battery temperature) corresponding to the cells C1 to C6 exceeds the estimated abnormality determination value, the CPU 102 regards the cell temperature distribution as abnormal, and performs step S4 described above. Make an affirmative decision.
[0029]
FIG. 9 is a diagram illustrating an example of an abnormal cell temperature distribution. In FIG. 9, the estimated cell temperature of the unit cell C6 (not shown) exceeds the range of + 1σ with respect to the average value of the estimated battery temperature.
[0030]
In step S5 of FIG. 3, the CPU 102 sends information indicating normal cell temperature to the vehicle system CPU 304, and ends the process of FIG. The vehicle system CPU 304 performs a predetermined calculation to perform charge / discharge control for the assembled battery.
[0031]
In step S6, the CPU 102 sends information indicating an abnormal cell temperature to the vehicle system CPU 304, shuts off the main relays 303A and 303B, and terminates the process in FIG. When the vehicle system CPU 304 receives information indicating a cell temperature abnormality, the vehicle system CPU 304 stops charge / discharge control for the assembled battery and lights the warning lamp 305.
[0032]
The embodiment described above will be summarized.
(1) The unit cells C1 and C2 formed of a thin laminated battery are placed on the positioning plate 21 and overlapped with the same positioning plate 22 to constitute an assembled battery. Each unit cell is sandwiched between upper and lower positioning plates and conducts (dissipates) the generated heat to the positioning plates. The positioning plates 21 and 22 are supported by the heat sinks 41 and 42, and conduct (heat radiate) the heat of the positioning plates 21 and 22 to the heat sinks 41 and 42. The heat sinks 41 and 42 absorb the heat from the positioning plates 21 and 22, while dissipating the absorbed heat to the outside. Since the positioning plates 21 and 22 also serve as heat sinks that absorb heat from the unit cells, the unit cells can be supported at a predetermined size and pressure, and the heat generated by the unit cells can be effectively absorbed. .
(2) Since the cooling air is blown toward the heat sinks 41 and 42 by the cooling FAN 204, the heat dissipation efficiency of the heat generated in the assembled battery can be further increased.
[0033]
(3) Since the temperature sensors 2032, 2034... Are provided on the heat sink 41, it is possible to detect a temperature change due to the single cell without providing a sensor on the surface of the single cell. Since no sensor is provided on the surface of the unit cell, each unit cell can be easily supported at a constant size and pressure, and the surface layer of the unit cell is not damaged.
(4) When the outside air temperature is 0 degrees, 10 degrees, 20 degrees, 30 degrees and 40 degrees, the temperature difference ΔBT when the FAN duties are 0, 0.25, 0.5, 0.75 and 1 is set in advance. It is measured as experimental data, mapped, and stored in the memory in the CPU 102. ΔBT is the difference between the actual cell temperature (cell temperature) and the temperature detected by the temperature sensors 2032, 2034. The CPU 102 reads ΔBT from the memory in accordance with the outside air temperature by the cooling air temperature sensor 205 and the calculated FAN duty, and uses the ΔBT and the detected temperature by the temperature sensors 2032, 2034. ). Thereby, the cell temperature can be estimated without directly detecting the surface temperature of the cell. Furthermore, the cell temperature can be accurately estimated in consideration of changes in the outside air temperature and temperature variations during cooling.
[0034]
(5) Since a plurality of temperature sensors are provided to estimate the battery temperature for each unit cell, the temperature distribution can be grasped for all the unit cells constituting the assembled battery. If the temperature of only some of the cells that make up the assembled battery is estimated, it cannot be detected even if a temperature abnormality occurs in anything other than that cell. Even if an abnormality occurs, this can be detected.
(6) The temperature sensor may be disposed only on the heat sink 41 side, omitting the one on the heat sink 42 side. In this case, the cost can be reduced as compared with the case where temperature sensors are provided in both the heat sinks 41 and 42.
[0035]
The temperature sensor may be disposed only on the heat sink 42 side without the heat sensor 41 side.
[0036]
Although an example in which a temperature sensor is provided corresponding to each stage of the positioning plate on which the unit cell is placed has been shown, for example, it may be provided at intervals of every other stage.
[0037]
Further, a temperature sensor may be disposed on the heat sink 41 side corresponding to the odd-numbered steps of the positioning plate, and a temperature sensor may be disposed on the heat sink 42 side corresponding to the even-numbered steps of the positioning plate.
[0038]
As a condition for determining the abnormal cell temperature distribution, the case where the estimated cell temperature of at least one single cell exceeds the range of + 1σ with respect to the average value of the estimated cell temperatures of all single cells has been described. Also good.
[0039]
The abnormality process in step S6 described above is performed by both the process of causing the vehicle system CPU 304 to turn on the warning lamp 305 and the process of causing the main relays 303A and 303B to shut off the high-power line.
[0040]
Although the temperature difference ΔBT is measured in advance as experimental data and discrete data is mapped and stored in the memory in the CPU 102, it may be stored as a function of the FAN duty and the outside air temperature.
[0041]
The correspondence between each component in the claims and each component in the embodiment of the invention will be described. For example, each of the laminated batteries C1 to C4 corresponds to the thin cell. The heat conducting member is constituted by positioning plates 21 and 22 and heat sinks 41 and 42, for example. The first temperature detection means is constituted by, for example, a temperature sensor 203 (2031 to 2034) and a battery temperature detection unit 101. The arithmetic circuit, the storage circuit, the operating state detection means, and the abnormality determination circuit are configured by the CPU 102, for example. The second temperature detection means is constituted by a cooling air temperature sensor 205, for example. The information indicating the relationship between the temperature detected by the first temperature detecting means and the temperature of the single cell corresponds to, for example, data (FIG. 7) that maps ΔBT. The blower is configured by a cooling FAN 204, for example. The operating state of the blower corresponds to, for example, FAN duty. In addition, unless the characteristic function of this invention is impaired, each component is not limited to the said structure.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a vehicle equipped with an assembled battery temperature detection device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating the structure of an assembled battery.
FIG. 3 is a flowchart for explaining a flow of an assembled battery temperature detection process performed by a CPU.
FIG. 4 is an enlarged view of a part of FIG.
FIG. 5 is a diagram showing a relationship between a position on a heat sink and temperature.
FIG. 6 is a diagram showing a relationship between a position on a heat sink and temperature.
FIG. 7 is a diagram in which ΔBT is mapped.
FIG. 8 is a diagram showing an example of a normal cell temperature distribution.
FIG. 9 is a diagram showing an example of an abnormal cell temperature distribution.
[Explanation of symbols]
21, 22 ... Positioning plate, 41, 42 ... Heat sink,
101 ... Battery temperature detection unit, 102 ... CPU,
203 (2031-2034) ... temperature sensor,
204 ... Cooling FAN, 205 ... Cooling air temperature sensor,
304 ... Vehicle system CPU, C1-C4 ... Single battery

Claims (5)

In the temperature detection device for detecting the temperature of the assembled battery composed of a plurality of thin cells,
A heat conducting member that supports the unit cells so as to sandwich the unit cells and conducts heat from the unit cells;
First temperature detecting means disposed on the heat conducting member to detect temperature;
An assembled battery temperature detection device using a thin battery, comprising: an arithmetic circuit that calculates the temperature of the unit cell using the temperature detected by the first temperature detection means. In the temperature detection apparatus of the assembled battery by the thin battery of Claim 1,
Second temperature detecting means for detecting the air temperature at a position spaced apart from the heat conducting member by a predetermined distance;
A storage circuit that stores in advance information indicating the relationship between the temperature detected by the first temperature detection unit and the temperature of the unit cell in correspondence with the temperature detected by the second temperature detection unit;
The arithmetic circuit reads information corresponding to the temperature detected by the second temperature detection means from the storage circuit, and calculates the temperature of the unit cell based on the read information and the temperature detected by the first detection means. An assembled battery temperature detection device using a thin battery. In the temperature detection apparatus of the assembled battery by the thin battery of Claim 2,
A blower for sending cooling air to the heat conducting member;
An operating state detecting means for detecting an operating state of the blower,
The storage circuit detects information indicating a relationship between a temperature detected by the first temperature detecting unit and a temperature of the unit cell by the temperature detected by the second temperature detecting unit and the operating state detecting unit. Stored in advance corresponding to each of the operating states of the blower,
The arithmetic circuit reads information corresponding to the temperature detected by the second temperature detection means and the operating state of the blower from the storage circuit, and the read information and the temperature detected by the first temperature detection means The temperature detection device for an assembled battery using a thin battery, wherein the temperature of the unit cell is calculated based on the above. In the temperature detection apparatus of the assembled battery by the thin battery in any one of Claims 1-3,
The heat conducting member conducts heat from the plurality of single cells, respectively.
The first temperature detecting means has a plurality of temperature sensors arranged at different positions on the heat conducting member,
The storage circuit stores information indicating a relationship between temperatures detected by the plurality of temperature sensors and temperatures of the plurality of single cells,
The temperature detection device for a battery pack using a thin battery, wherein the arithmetic circuit calculates temperatures of the plurality of single cells, respectively. In the temperature detection apparatus of the assembled battery by the thin battery of Claim 4,
An assembled battery temperature detection device using a thin battery, further comprising: an abnormality determination circuit that determines the presence or absence of temperature abnormality of the assembled battery by obtaining temperature distributions of the plurality of single cells from the calculation result of the arithmetic circuit.

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