JP3602250B2 - Power storage device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power storage device configured by connecting in series and parallel a power storage capacitor such as an ultra-large capacity electric double layer capacitor used for a power storage device of an electric vehicle.
[0002]
[Prior art]
Conventionally, as a power storage device for an electric vehicle, a device mainly including a secondary battery (storage battery) such as a lead storage battery or a nickel cadmium battery has been developed. In parallel with the development of the power storage device using the secondary battery, research on using an extremely large-capacity capacitor (power storage device) called an electric double layer capacitor as a power storage device for an electric vehicle has been advanced.
[0003]
This electric double layer capacitor combines an activated carbon or an activated carbon fiber with an aqueous electrolyte or an organic electrolyte as disclosed in JP-A-60-15138 or US Pat. No. 3,536,963. Thereby, an extremely large capacitance is realized. Typically, ultra-large capacitors of 5F to 10F are realized under the same diameter and almost three times the thickness of a ten-yen coin, and are commercially available.
[0004]
Such a large-capacity capacitor has already exceeded that of a lead-acid battery or the like in terms of the amount of electricity stored per unit volume and unit weight, and is therefore extremely promising as a power storage device for electric vehicles. Such an electric double layer capacitor also has the advantage of being extremely economical in that, unlike conventional storage batteries, there is no substantial limitation on the number of times that it can be charged and discharged.
[0005]
Conventionally, capacitors (capacitors) have been used alone or in combination with circuit elements such as coils and resistors to realize various AC electrical characteristics such as surge absorption, smoothing, filtering, and tuning. The capacitance is at most several hundred μF, and the stored energy is extremely small even if it is a capacitor. Therefore, a capacitor having an ultra-large capacity of several tens of farads is generally used for storing DC power, except for a very special use, and is distinguished from a conventional capacitor for realizing a small-capacity AC characteristic. be able to. Therefore, in this specification, capacitors having a large capacity of several tens of F or more, such as an electric double layer capacitor for storing DC power, are collectively referred to as “capacitors for power storage”.
[0006]
In the case of an electric double layer capacitor which is one of such DC storage capacitors, a typical withstand voltage is as low as several volts. For this reason, in order to realize a power storage device for an electric vehicle having a storage amount of several hundred KWH and an output voltage of about 300 volts, a large number, typically several hundreds, of DC storage capacitors are connected in series as a module. A connected capacitor array will be formed.
[0007]
When an electric storage device for an electric vehicle is realized by using the above storage capacitor, hundreds of modules are connected in series and parallel, so that deterioration occurring in a part of the module may greatly impair the function of the entire storage device. There is. For this reason, it is necessary to determine the presence or absence of deterioration for each module element, and to separate the module that has been determined to have deteriorated from the capacitor array.
[0008]
Conventionally, as a method for determining the presence or absence of deterioration of an electric double layer capacitor, a low frequency square wave signal is applied between terminals of the electric double layer capacitor as proposed in Japanese Patent Application Laid-Open No. Hei 6-342024. There is known a method of making a determination based on an integral value of a predetermined portion of a terminal voltage at the time. Further, as another method for determining the deterioration of the electric double layer capacitor, a zener diode and a light emitting diode are connected in series between the terminals of the electric double layer capacitor as proposed in Japanese Patent Application Laid-Open No. 7-99723. A device that detects a failure from the light emission amount of a light emitting diode has been proposed.
[0009]
A method of separating a module determined to have deteriorated from a capacitor array is proposed in Japanese Patent Application Laid-Open No. 7-99142. According to this method, an electric double layer capacitor is connected in parallel to each of the diodes connected in series via a detachable connector, and the electric double layer capacitor determined to be deteriorated is extracted from the detachable connector. Is configured.
[0010]
[Problems to be solved by the invention]
Among the above-described methods for determining the deterioration of the electric double layer capacitor, the method proposed in JP-A-6-342024 may be suitable for screening at the manufacturing stage. However, since this is an indirect determination method, there is a possibility that an erroneous determination may occur, and there is a problem in the accuracy of determination at least as a determination method in a use state.
[0011]
Among the above-described methods for determining the deterioration of the electric double-layer capacitor, the method proposed in Japanese Patent Application Laid-Open No. 7-99723 is suitable for a worker performing inspection and repair to visually find a defective element. Could be. However, in order to realize automatic determination by an electronic control unit (ECU) or the like while the vehicle is traveling, a photoelectric conversion circuit that temporarily converts the light emission amount of the light emitting diode into an electric signal such as a voltage or a current is required for each element. There is a problem that the cost of the apparatus increases.
[0012]
Further, with respect to a method of separating a module determined to have deteriorated from a capacitor array composed of these series-parallel connections, the method proposed in Japanese Patent Application Laid-Open No. H07-99142 is disclosed in Japanese Patent Application Laid-Open No. H07-99142. However, there is a problem in realizing automatic determination by an electronic control unit (ECU) while the vehicle is running.
Accordingly, an object of the present invention is to provide a highly accurate determination of deterioration of each module, relatively inexpensive, and suitable for automatic determination of a deteriorated module by an electronic control unit or the like while the vehicle is running and automatic separation from the capacitor array. To provide a power storage device.
[0013]
[Means for Solving the Problems]
The power storage device of the present invention that solves the above-mentioned problems of the prior art includes a capacitor array in which a plurality of capacitor modules including a storage capacitor such as an electric double layer capacitor are connected in series and parallel, and a voltage between terminals of each capacitor module. A monitoring / control unit for detecting at least one of the temperature and separating the capacitor module in which the detected inter-terminal voltage and / or temperature is abnormal as a deteriorated module from the capacitor array.
[0014]
The determination of whether the inter-terminal voltage and temperature of each capacitor module is abnormal, upper SL terminal voltage and temperature of all of the capacitor module in the connection monitoring and control unit in the series-parallel connection unit Is calculated based on whether or not the terminal voltage or the temperature detected for any one of the capacitor modules deviates from the range of the upper and lower limits set above and below the respective average values.
[0015]
【Example】
FIG. 1 is a functional block diagram illustrating a configuration of a power storage device according to an embodiment of the present invention. The power storage device according to the present embodiment includes a capacitor array CG including an electric double layer capacitor module group connected in series and parallel, a degraded module is separated from the capacitor array CG, and the power storage device according to the type of a charging power supply. An electronic control unit ECU for changing the serial / parallel connection state of the capacitor modules in the capacitor array CG, and a display unit DP for displaying the occurrence of a deteriorated module and the identifier of the deteriorated module. I have.
[0016]
As shown in FIG. 2, the capacitor array CG configured by the serial / parallel connection of the electric double layer capacitors is divided into groups G1, G2, G3,. At the same time, the groups of electric double layer capacitor modules are connected in series / parallel through control signal lines CL1 and CL2 connected to the electronic control unit ECU by switching switches SW1 and SW2 controlled by the electronic control unit ECU. Connected so that changes can be made.
[0017]
That is, when the switches SW1 and SW2 are switched as illustrated in FIG. 2, the groups G1, G2, G3,... Of the electric double layer capacitor modules are connected to each other in series. On the other hand, the groups G1, G2, G3,... Are connected in parallel with each other by switching the switches SW1, SW2 so as to be in a state opposite to that shown in the figure. Within each group G1, G2, G3,..., A further small number of groups of electric double layer capacitor modules are connected in series and parallel as shown in FIG. At the same time as the connection is changed from series to parallel, the same connection is changed within each group.
[0018]
FIG. 3 is an equivalent circuit diagram showing the configuration of the electric double layer capacitor module 10 which is the minimum unit of the electric double layer capacitor connected in series / parallel. FIG. 4 is a perspective view showing the appearance of the electric double layer capacitor module. FIG. The electric double layer capacitor module 10 has a large capacity electric double layer capacitor cell C, positive and negative terminals T1 and T2, and a main part for connecting the electric double layer capacitor cell C between the positive and negative terminals T1 and T2. In addition to the electric circuit MP, a bypass electric circuit BP, a switch SW for selecting one of the bypass electric circuit BP and the main electric circuit MP and connecting to the positive terminal T1, and a control for supplying a control signal for selection to the switch SW A signal line CL and a control terminal CNT for receiving the control signal from an electronic control unit ECU external to the electric double layer capacitor module 10 are provided.
[0019]
The electric double layer capacitor module 10 further externally monitors the resistor R connecting the control signal line CL to the negative terminal of the electric double layer capacitor cell C and the voltage between the terminals of the electric double layer capacitor cell C. Voltage monitoring lines m1 and m2, voltage monitoring terminals M1 and M2, a thermocouple TH for detecting an operating temperature of the electric double layer capacitor cell C, and a voltage between terminals of the thermocouple TH. Voltage monitoring terminals M3 and M4 for monitoring from the electronic control unit ECU outside the double-layer capacitor module 10 are provided.
[0020]
During the operation of the electric double layer capacitor module 10, a control signal of a positive voltage is supplied from the electronic control unit ECU to the control terminal CNT, the switch SW is switched as shown in FIG. Appears between the positive terminal T1 and the negative terminal T2. During this operation period, the voltage between the terminals of the electric double layer capacitor C and the operation temperature are monitored by the monitor terminals (M1, M2) and (M3, M4) and the monitor terminals for connecting these monitor terminals to the electronic control unit ECU. Through the monitor signal line, the electronic control unit ECU (FIG. 1) monitors at a constant cycle.
[0021]
The electronic control unit ECU assigns the input port number to which each monitor signal line is drawn to the module number i (= 1, 2, 3,... N) of the corresponding electric double layer capacitor module connected to this input port. Manage as As illustrated in FIG. 5, the electronic control unit ECU associates the terminal voltage Vi and the operating temperature Ti monitored from each electric double layer capacitor module with the module number i and forms the module status on the built-in memory. Manage in the management table.
[0022]
The electronic control unit ECU calculates an average value Vav for all the capacitor modules connected in the capacitor array from the terminal voltage Vi monitored for each capacitor module, and further calculates an average value Vav greater than 1 for this average value. By multiplying a predetermined constant α and a predetermined constant β smaller than 1, an allowable upper limit value Vmax (= αVav) and an allowable lower limit value Vmin (= βVav) are calculated, respectively, and a module status management table is calculated. Write in.
[0023]
Similarly, the electronic control unit ECU calculates an average value Tav for all the capacitor modules from the operating temperature Ti monitored for each capacitor module, and further calculates a predetermined constant γ larger than 1 for this average value, By multiplying by a predetermined constant δ smaller than 1, an allowable upper limit value Tmax (= γTav) and an allowable lower limit value Tmin (= δTav) are calculated and written in the module status management table.
[0024]
The electronic control unit ECU monitors the inter-terminal voltage Vi and the operating temperature Ti for each capacitor module, and each time the calculation of the average value and the allowable upper / lower limit values is completed, the newly monitored inter-terminal voltage Vi and the operating temperature. For Ti, it is checked whether any of these are between the corresponding allowable lower limit and the allowable upper limit. When the electronic control unit ECU detects a capacitor module in which the terminal voltage or the operating temperature does not exist between the lower limit value and the lower limit value, the electronic control unit ECU regards the capacitor module as a deteriorated module, and Disconnect from array CG.
[0025]
FIG. 6 is a conceptual diagram showing the average value of the voltage between terminals of each capacitor module managed in the module status management table and how the allowable upper limit / lower limit changes with time. The voltage between the terminals of each capacitor module decreases with time as the discharge of the vehicle power storage device configured by these components progresses, but is hatched by multiplying the average value by a constant value. Since the deterioration of each module is detected based on the relative value of the range of the allowable upper and lower limits shown as above, the detection accuracy is maintained at a high value.
[0026]
The reason why deterioration can be determined not only from the voltage between terminals but also from the operating temperature of each capacitor module is as follows. That is, when the series resistance increases due to the deterioration of the electric double layer capacitor cell C in any one of the capacitor modules, the Joule heat loss increases and the operating temperature of the electric double layer capacitor cell C rises. Conversely, when the current flowing through the electric double layer capacitor cell C becomes zero due to an open circuit failure due to a disconnection or the like generated in any one of the capacitor modules, Joule heat disappears and the operating temperature of this capacitor module is reduced. Is lower than the normal operating temperature of the capacitor module. Thus, deterioration can be detected by monitoring the operating temperature of each capacitor module.
[0027]
The electronic control unit ECU disconnects the capacitor module deemed to be deteriorated from the capacitor array CG. That is, the electronic control unit ECU sets the positive voltage being output to zero on a signal line connected to the control terminal CNT (FIG. 3) of the capacitor module 10 determined to be deteriorated. Accordingly, in this capacitor module, the bypass circuit BP is connected to the positive terminal T1 through the switch SW instead of the main circuit MP, and the positive and negative terminals T1 and T2 are short-circuited by the bypass circuit BP. As a result, the capacitor module determined to be deteriorated is disconnected from the capacitor array CG in FIG.
[0028]
In the capacitor module once deemed to be degraded and separated, a positive voltage appears at the control terminal CNT due to the generation of static electricity or induced noise, and the switch SW operates, and this capacitor module is removed. In order to prevent reconnection to the capacitor array CG, a resistor R is connected between the control signal line CL and the main electric circuit MP connected to the negative terminal of the electric double layer capacitor cell C. . The positive voltage appearing on the control signal line CL for a short time due to static electricity, induced noise, or the like is discharged onto the main electric circuit MP through the resistor R and disappears. The same purpose can be achieved by connecting a general-purpose capacitor having a capacitance of about several tens of μF between the control signal line CL and the main electric circuit MP instead of the resistor.
[0029]
The electronic control unit ECU sets a deterioration flag F indicating that the capacitor module has been cut off from the capacitor array CG due to deterioration as a deterioration of the corresponding capacitor number in the module status management table. Write to. FIG. 5 illustrates a case where the capacitor module of module number 3 is in a deteriorated state. The state of this deterioration is read out to the display unit DP (FIG. 1), and an indication that deterioration has occurred in some capacitor modules and the module number of the capacitor module separated due to this deterioration are displayed on the liquid crystal display panel. Etc. are displayed.
[0030]
As shown in FIG. 7, a specific example of the switch SW shown in FIG. 3 includes high power field effect transistors FET1 and FET2 and an inverter INV. When a certain level of positive voltage appears on the control voltage line CL, the FET1 is turned on and the FET2 is turned off, and the main circuit MP is connected to the positive terminal T1 through the FET1. When a certain level of positive voltage disappears from the control signal line CL, the FET1 is turned off, the FET2 is turned on, the bypass circuit BP is connected to the positive terminal T1 through the FET2, and a bypass is connected between the terminals T1 and T2 of this element. It is bypassed through the electric circuit BP.
[0031]
When charging the power storage device, the ECU changes the series-parallel connection state of the groups G1, G2, G3,... Constituting the capacitor array CG and the capacitor modules in each group according to the magnitude of the charging voltage. change. Further, the ECU detects a terminal voltage of an output terminal (not shown) of the power storage device connected to the DC / DC converter during a discharge period when the vehicle is running, and the output terminal voltage drops to a certain level or less. When the fact is detected, the parallel connection state is shifted to the series connection state, thereby compensating for the voltage drop at the output terminal of the power storage device.
[0032]
For such a purpose, it is more desirable to change the voltage of the output terminal during the discharge period in multiple steps by adopting a configuration in which the series-parallel connection is switched in multiple steps. In addition, by performing serial / parallel switching in multiple stages according to the state of increase in the voltage of the charge input terminal during the charging period, the terminal voltage can be changed according to the progress of charging.
[0033]
As described above, the configuration in which the voltage between terminals and the operating temperature of each capacitor module are monitored, and if any one of them is abnormal, it is determined that the capacitor module is deteriorated. However, for each capacitor module, deterioration is determined by monitoring only the voltage between its terminals, deterioration is determined by monitoring only the operating temperature, or deterioration is determined only when both are abnormal and both are abnormal. It is also possible to adopt a configuration in which it is determined that an error has occurred.
[0034]
【The invention's effect】
As described above in detail, the power storage device of the present invention monitors at least one of the terminal voltage and the operating temperature of each capacitor module connected in series and parallel, and at least one of these capacitors exhibits an abnormal value.・ Since the module is provided with a monitoring and control unit that separates the module from the capacitor array by regarding the module as a deterioration module, the deterioration is directly judged and the accuracy of the judgment is improved. There is an effect that automatic determination and automatic switching of a deteriorated module by a unit or the like become possible.
[0035]
According to the present invention , the average value of the terminal voltage and the operating temperature of all the capacitor modules connected to the capacitor array CG is calculated, and the terminal voltage and the operating temperature detected for any one of the capacitor modules are calculated. The battery is determined to be abnormal if it deviates from the upper and lower limits set above and below the calculated average value.Unlike conventional storage batteries, the voltage between terminals greatly increases according to the progress of charging and discharging. For a power storage device that uses a power storage capacitor that fluctuates rapidly, or a power storage device for a vehicle that has a temperature that fluctuates greatly depending on the traveling area, season, and the like, it is possible to determine the deterioration with extremely high accuracy.
[Brief description of the drawings]
FIG. 1 is a functional block diagram illustrating a configuration of a power storage device according to an embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram showing an example of a configuration for changing a connection of a series-parallel connection unit CG of the embodiment.
FIG. 3 is a perspective view showing an appearance of an element including a minimum unit electric double layer capacitor of the embodiment.
FIG. 4 is a perspective view showing the appearance of the device.
5 is a conceptual diagram showing an example of the contents of a management table for the electronic control unit ECU of FIG. 1 to centrally manage the state of each element.
FIG. 6 is a conceptual diagram showing how the terminal voltage of each capacitor module changes over time managed by the management table.
FIG. 7 is a circuit diagram showing an example of a specific configuration of a switch SW of FIG. 3;
[Explanation of symbols]
CG Capacitor array ECU that is configured when electric double layer capacitors are connected in series / parallel. Electronic control unit DP Display unit 10 Capacitor module C Electric double layer capacitor cells T1, T2 Positive / negative terminal MP Main circuit BP Bypass circuit SW Switch CNT Control terminal

Claims (8)

A capacitor array in which a plurality of capacitor modules including storage capacitors are connected in series and parallel, and a voltage and temperature between terminals of each of the capacitor modules are detected, and the detected voltage and / or temperature between terminals is abnormal. A monitoring and control unit for separating the module from the capacitor array by regarding the module as a deteriorated module ;
This monitoring / control unit calculates an average value of the terminal voltage and the temperature of all the capacitor modules connected in series and parallel, and detects one or both of the terminal voltage and the temperature detected for any one of the capacitor modules. The power storage device is characterized in that it is determined that the abnormality occurs when the average value deviates from a range between an upper limit value and a lower limit value set above and below the average value . A capacitor array in which a plurality of capacitor modules including a storage capacitor are connected in series / parallel, and a voltage between terminals of each of the capacitor modules are detected. A capacitor module having an abnormal detected terminal voltage is regarded as a deteriorated module. A monitoring / control unit for separating the capacitor array from the capacitor array ;
This monitoring / control unit calculates the average value of the terminal voltage for all the capacitor modules connected in series and parallel, and the terminal voltage detected for any one of the capacitor modules is set above and below the average value. A power storage device characterized in that the abnormality is determined when the value deviates from the range between the upper limit value and the lower limit value . A capacitor array in which a plurality of capacitor modules including a storage capacitor are connected in series and parallel, and the temperature of each of the capacitor modules is detected, and the detected capacitor module having an abnormal temperature is regarded as a deteriorated module, and Having a monitoring / control unit separated from the capacitor array ;
This monitoring and control unit calculates an average value of the temperatures of all the capacitor modules connected in series and parallel, and the detected temperature of any one of the capacitor modules is set to an upper limit and a lower limit set above and below the average. A power storage device, wherein the abnormality is determined when the value deviates from the lower limit range . In each of claims 1 to 3,
The power storage device, wherein the power storage capacitor is an electric double layer capacitor. In any one of claims 1 to 4,
The power storage device, wherein the monitoring / control unit includes display means for displaying that a module deemed to be deteriorated has appeared. In any one of claims 1 to 5,
The power storage device, wherein the display unit of the monitoring / control unit further includes a unit that displays an identifier of the capacitor module considered to be degraded. In any one of claims 1 to 6,
A bypass circuit and a switch are provided inside each of the capacitor modules, and the separation of the module considered as degraded from the capacitor array is performed by switching a switch in the module deemed as degraded. A power storage device characterized by being formed by forming a bypass electric circuit. In any one of claims 1 to 7,
A power storage device, wherein a connection state of each capacitor module in the capacitor array in series / parallel can be changed by control of the monitoring / control unit.

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