JP4513791B2 - Power storage device - Google Patents

Description

  The present invention particularly relates to a power storage device using a capacitor.

  In recent years, so-called electric vehicles and hybrid vehicles, in which all or part of driving is performed by a motor, are becoming widespread in consideration of the environment.

  In these automobiles, the electric power of the motor is supplied from the battery. However, since the battery is rapidly changed in characteristics and deteriorated due to charging and discharging with a large current, the current supplied to the motor is limited particularly during rapid acceleration. For this reason, sufficient acceleration may not be obtained.

  Therefore, an automobile using a capacitor capable of rapid discharge in combination with a battery has been devised. Thereby, since the electric power of the capacitor in addition to the battery is supplied to the motor at the time of rapid acceleration, it is possible to accelerate more rapidly than the case of only the battery.

  In order to obtain a voltage that can drive the motor with a capacitor, if the required voltage is about 750 V, 300 capacitors must be connected in series when a capacitor with a rated voltage of 2.5 V is used. . Moreover, in order to obtain a required capacity | capacitance, a parallel connection may be combined.

  However, there are variations in capacitors, and the voltage applied to the capacitors varies. If charging is performed without taking this into account, there is a possibility that deterioration of the capacitors will progress or even damage may occur.

  Therefore, a method has been devised for managing the states of a large number of capacitors and detecting an abnormality. An example of such an abnormality detection method is shown in the block circuit diagram of FIG.

  When a plurality of capacitors 2 having a rated voltage of 2.5 V are charged from the DC power supply 1, how much current flows through each capacitor 2 and how much voltage is applied to the current detector 3 and the voltage. Each measurement is performed by the detection means 4 and the controller 5 controls the charging and determines whether the capacitor 2 is normal or abnormal.

As prior art document information related to this application, for example, Patent Document 1 is known.
JP 2003-274666 A

  According to the above-described abnormality detection method, it is possible to detect a capacitor 2 having an abnormality. Therefore, when used for assisting a motor drive battery of a hybrid vehicle, for example, among the 300 capacitors 2 as described above. If one of the capacitors reaches an operation limit and is determined to be abnormal, a measure such as removing the capacitor 2 from the circuit is taken.

  In addition, the system of the hybrid vehicle can be safely stopped by determining in advance how many abnormalities of the capacitor 2 are allowed.

  In this way, for example, it is conceivable that the capacitors 2 having abnormalities can be replaced at a time when the operation is stopped, and the maintenance becomes relatively easy.

  However, in this case, if only the abnormal capacitor 2 is replaced with a new one, the system will be used in combination with other capacitors 2 whose operating limits are approaching even if there is no abnormality at present. Each time an abnormal capacitor appears and a predetermined number of abnormalities occur, the capacitor 2 must be replaced.

  As described above, in a power storage device in which a plurality of capacitors 2 exist, the service life thereof is restricted by the capacitor 2 having a high degree of deterioration.

  Therefore, the replacement frequency increases with use for a long period of time, or the service life of the power storage device is shortened.

  On the other hand, if the number of abnormal capacitors 2 reaches a predetermined number, if the entire system is replaced, the replacement frequency will not increase, but the capacitors 2 having a margin to the operating limit will also be replaced. So it is uneconomical.

  Therefore, although it is possible to detect the abnormal capacitor 2 with the conventional configuration, it is replaced with a new one each time a predetermined number of abnormal capacitors are generated. The problem was that the service life of the product was shortened and it was generally uneconomical.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a power storage device that can extend the service life and reduce the frequency of capacitor replacement as much as possible.

In order to solve the above conventional problems, the power storage device of the present invention, a plurality of the deterioration degree detecting means for determining the deterioration degree of the Capacity data, pre-connected balanced voltage adjusting means in parallel to Kiki Yapashita, the deterioration degree detecting means and said balanced voltage adjusting means consists that the connected control unit, from the average value of the control unit the deterioration degree of the crisis Yapashita before detected by the deterioration degree detecting means, before determined handed Yapashita the deterioration degree of the variation width of a balance voltage decreases, respectively, connected the while applying a voltage across the entire capacitor, wherein so that the voltage across the previous crisis Yapashita is the balanced voltage The balance voltage adjusting means is controlled.

Since the balanced voltage as the variation width is reduced in the deterioration degree of the accordance with the present configuration key Yapashita is adjusted is delayed the deterioration degree to progress in degradation capacitor. In addition, all capacitors reach the operating limit almost at the same time. As a result, the object can be achieved.

  According to the power storage device of the present invention, the deterioration progress is delayed with respect to the capacitor that has deteriorated, and all the capacitors reach the operation limit almost at the same time, so that the service life as the power storage device can be extended, The number of capacitor replacements can be reduced as much as possible.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that the embodiment describes the case where the power storage device is applied to a hybrid vehicle.

(Embodiment 1)
1 is a partially omitted block circuit diagram of a power storage device according to Embodiment 1 of the present invention. FIG. 2 is a time-dependent characteristic diagram of the voltage across the capacitor during charging of the power storage device according to Embodiment 1 of the present invention. FIG. 3 is an operational limit characteristic diagram of the capacitor using the capacitance value and the internal resistance value of the power storage device according to the first embodiment of the present invention as parameters. FIG. 4 is a time-dependent characteristic diagram of the voltage across the capacitor after adjusting the balance voltage of the power storage device according to Embodiment 1 of the present invention.

  First, the structure of the power storage device will be described with reference to FIG. In the wiring of FIG. 1, the thick line indicates the high voltage system and the thin line indicates the signal system.

  In FIG. 1, a battery 11 is used as a main power source for driving a motor of a hybrid vehicle. The battery 11 includes a booster circuit (not shown).

  Charging / discharging of the battery 11 is controlled by a charge / discharge control circuit 12.

  The charge / discharge control circuit 12 is also responsible for the control of a control unit 30 (details will be described later) for charging and discharging 300 series-connected capacitors 13 used as an auxiliary for the battery 11 and monitoring and controlling the capacitors 13. It is responsible for overall system control such as optimum output adjustment of the output of the battery 11 and the capacitor 13.

  A connector 12a for exchanging data with a control circuit (not shown) of the hybrid vehicle is also connected.

  As the capacitor 13, an electric double layer capacitor excellent in rapid charge / discharge was used.

  The charge / discharge of the capacitor 13 is controlled by the charge / discharge control circuit 12 so that the charge switch 14 is turned on during charging and the discharge switch 15 is turned on during discharging. When charging / discharging is not performed, both the charging switch 14 and the discharging switch 15 are turned off.

  The charge switch 14 is connected in series with current detection means 16 for detecting the charging current.

  Next, the peripheral circuit 17 connected to each capacitor 13 (the range of the peripheral circuit 17 with respect to the uppermost capacitor 13 in FIG. 1 is shown by the widest dotted line. The other capacitors 13 are squares because it is difficult to see the figure. (Dotted lines are omitted. The same applies to the other drawings).

  The peripheral circuit 17 is used as a part of the deterioration progress detection means, and the deterioration progress detection means is configured by combining the peripheral circuit 17 and a control unit 30 described later.

  A sampling capacitor 20 having a smaller capacity than the capacitor 13 is connected to both ends of the capacitor 13 in parallel via two switches 21. Further, the balance voltage adjusting means 23 is further connected in parallel to both ends of the capacitor 13.

  The switch 21 is a three-terminal type. As shown in FIG. 1, one end of the changeover switch is connected to the capacitor 13, and the other is connected to a control unit 30 (described later) including a voltage measurement circuit that measures the voltage across the capacitor 13. Either one is selected by an external signal.

  The balance voltage adjusting means 23 is in the range indicated by the second widest square dotted line in FIG. 1 and can adjust the voltage across the capacitor 13.

  Specifically, it has the following configuration.

  First, a switch 25 connected in series with the balance resistor 24 is connected in parallel with the capacitor 13.

  Furthermore, a voltage dividing resistor A26 and a voltage dividing resistor B27 for dividing the voltage across the capacitor 13 are connected in series to the capacitor 13, and the divided voltage Vs is input to one of the comparators 28. The output (reference voltage) Vf of the balance voltage setting means 31 (shown by the smallest square dotted line in FIG. 1) is connected to the other input side of the comparator 28.

  The balance voltage setting unit 31 is configured to generate an adjustable reference voltage Vf by connecting in series a digital potentiometer 33 and a resistor 34 whose resistance values can be adjusted by signals from the reference power supply 32 and the control unit 30. Note that since the digital potentiometer 33 includes the nonvolatile memory 35, the adjusted resistance value can be stored even when the power of the power storage device is turned off.

  Accordingly, the reference voltage Vf of the balance voltage setting means 31 is determined by the resistance value of the digital potentiometer 33 instructed by the control unit 30, and the reference voltage Vf and the shared voltage Vs are input to the comparator 28. In other words, the voltage across the capacitor 13 is compared with the reference voltage Vf.

  The comparator 28 controls on / off of the switch 25 according to the comparison result of the input voltage.

  The power storage device according to the first embodiment includes 300 capacitors 13 having the peripheral circuit 17 as described above (all circuits except the capacitor 13 within the range indicated by the dotted line as the peripheral circuit 17 in FIG. 1) in series. In FIG. 1, only the first two and the last one are shown, and the others are omitted.

  Next, the control unit 30 will be described.

  The control unit 30 has a function of monitoring and controlling the capacitor 13 and incorporates the following components in the first embodiment.

  That is, as an electrical indirect connection means, a photoelectric converter group 36 having a function of an electrical insulation means such as a photocoupler or a photo IC, a microcomputer 37 for executing various calculations and control from a measurement signal, and a microcomputer 37 Transmission / reception for controlling communication between the AD converter 38 for measuring the voltage across the capacitor 13 under the control of the capacitor 13, the multiplexer 39 for switching and measuring the voltage of the capacitor 13, and the charge / discharge circuit 12 and other control unit 30 The unit 40 is configured.

  Thereby, the microcomputer 37 controls the switch 21, the multiplexer 39 and the AD converter 38 while being electrically insulated via the photoelectric converter group 36, measures the voltage across the capacitor 13, and sets the resistance value to the digital potentiometer 33. I am going to tell you.

  Since the capacitor 13 and the peripheral circuit 17 are composed of 300 sets, the processing efficiency and the total merit are examined in performing various arithmetic processes. In the first embodiment, one control is performed for four sets of the capacitor 13 and the peripheral circuit 17. The unit 30 is provided, and the switching of the switch 21, the measurement of the voltage across the capacitor 13, the instruction of the set resistance value to the digital potentiometer 33, etc. are processed in parallel for the four sets of capacitors 13 and the peripheral circuit 17.

  Accordingly, since there are 75 control units 30, each control unit 30 is configured to communicate with each other various kinds of calculation information and control results via the built-in transmission / reception unit 40.

  Further, for example, in the voltage measurement of the capacitor 13, the control unit 30 starts measuring the voltage of each capacitor 13 at the same time by transmitting a measurement start command from the charge / discharge control circuit 12 as a broadcast output. For example, information common to all the control units 30 is instructed by broadcast output from the charge / discharge control circuit 12 all at once, and information data is transmitted.

  A temperature sensor 41 for measuring temperature is provided in the vicinity of the capacitor 13 inside the power storage device. This temperature data is taken in by the charge / discharge control circuit 12, and the temperature data is also transmitted to the control unit 30 all at once. The temperature sensor 41 is a thermistor with excellent sensitivity.

  In the overall circuit of the first embodiment, the high voltage system circuit and the grounds of the 75 control units 30 are independent of each other. As a result, it is configured to prevent the spread of failures such as the contact between the high voltage and the low voltage due to a malfunction of the switch.

  In addition, the number attached | subjected to the ground shown with the inverted triangle to the peripheral circuit 17 or the control part 30 shows that the ground of the same number is connected.

  Therefore, since there are 75 control units, the numbers attached to the ground are 1... N.

  Next, the operation of such a power storage device will be described.

  When an ignition switch (not shown, hereinafter abbreviated as IG) of a hybrid vehicle (hereinafter abbreviated as a vehicle) is turned on, the power storage device body and the charge / discharge control circuit 12 are activated.

  The charge / discharge control circuit 12 outputs information that the IG is turned on by the broadcast output to the control unit 30, and the capacitor 13 is kept at a constant current up to a specified voltage (the voltage across the capacitor 13 is 750 V as in the conventional case). Charge with.

  Specifically, the charge / discharge control circuit 12 shown in FIG. FIG. 2 shows the change with time in the voltage across the capacitor after the start of charging. The horizontal axis represents time, and the vertical axis represents the voltage across the capacitor.

  The voltage across the capacitor before starting charging differs depending on the situation after the previous vehicle use. Although it is better for the capacitor 13 to discharge all 300 after use of the vehicle, the power is wasted because the power must be charged at the time of restart.

  Therefore, a method of leaving the vehicle without forcibly discharging it after use of the vehicle is conceivable. In this case, since spontaneous discharge occurs, electric power remains in the capacitor 13 when the vehicle is used again, and only the amount of spontaneous discharge needs to be charged, thereby reducing waste.

  Therefore, there are systems that completely discharge in consideration of life and efficiency, and systems that spontaneously discharge, so the origin of the vertical axis in FIG.

  Here, in order to make the explanation easy to understand, it is assumed that discharge is forcibly performed after use of the vehicle, and the voltage across all capacitors 13 is 0V. In FIG. 2, description will be made using the time-varying characteristics of an arbitrary capacitor x indicated by a solid line.

  When charging is started at time 0, a steep voltage rise corresponding to the internal resistance value R of the capacitor x occurs, and thereafter, charging proceeds with time and the voltage across the capacitor increases.

  During this charging, the degradation progress degree prediction of the capacitor x is performed using the capacitor degradation progress detection means (Japanese Patent Laid-Open No. 2005-28908) that has already been disclosed.

  An outline of the deterioration progress detection means is as follows. Each capacitor 13 obtained based on the current and voltage when charging each capacitor 13 at the time of starting the power storage device body and the temperature data from the temperature sensor 41 provided in the vicinity of the capacitor 13. The deterioration progress of each capacitor 13 is obtained from the correlation between the internal resistance value R and the deterioration progress.

  Therefore, since the internal resistance value R and the temperature T are necessary for predicting the deterioration progress, a specific method for obtaining the internal resistance value R will be described. Since the capacitance value C is also obtained at the same time, it will be described together.

  First, in order to obtain the internal resistance value R, charging is interrupted by turning off the charging switch 14 instantaneously (in the order of several tens of ms) at an arbitrary time until the charging of the capacitor x is completed.

As a result, the voltage across the capacitor causes a voltage drop. This voltage drop width Vix is proportional to the internal resistance value R of the capacitor x. That is, since the charging current I is a constant current and is obtained from the current detection means 16,
R = Vix / I (1)
Is required.

  The problem here is the method of measuring the instantaneous voltage drop for each of the 300 capacitors 13.

  On the other hand, in the first embodiment, the voltage drop is obtained as follows.

  First, based on the instruction data from the charge / discharge control circuit 12, each control unit 30 reads the voltage across the capacitor immediately before the charge is interrupted. Specifically, this is performed as follows.

  First, all the switches 21 are simultaneously switched to the capacitor 13 side. Thereby, the capacitor 13 and the sampling capacitor 20 are connected in parallel.

  Here, since the capacitance of the sampling capacitor 20 is much smaller than the capacitance of the capacitor 13, the voltage across the sampling capacitor 20 becomes equal to the voltage across the capacitor 13.

  Next, all the switches 21 are switched to the control unit 30 side (voltage measurement side).

  Thereafter, the voltage across the four sampling capacitors 20, that is, the voltage across the capacitors 13 is sequentially switched and read by switching the multiplexer 39 built in the control unit 30.

  The voltage across the selected capacitor 13 is stored as digital data in a memory (not shown) built in the microcomputer 37 via the AD converter 38 and the photoelectric converter group 36.

  Thus, although it takes a very long time to sequentially read the voltage across the capacitor 13 as many as 300, the 75 control units 30 can read four at a time and finish reading at high speed.

  Next, when the reading of the capacitor voltage before the interruption of charging is completed, the charging switch 14 is turned off and at the same time, the switch 21 is controlled again so that the sampling capacitor 20 is connected in parallel with the capacitor 13.

  As a result, as described above, the voltage across the sampling capacitor 20 becomes equal to the voltage across the capacitor 13.

  After that, wait until the voltage drop settles down to a constant value, and when it becomes a constant value, the switch 21 is controlled and switched to the control unit 30 side to read the voltage after the drop held in the sampling capacitor 20 after resuming charging, The voltages across the four sampling capacitors 20 are sequentially stored in the memory.

  Next, the charging / discharging control circuit 12 instantaneously controls the charging switch 14 to resume charging.

  Vix can be obtained by the above operation. Thereafter, since the charging current I is known, the internal resistance value Rx can be obtained from the equation (1).

  This is obtained for 300 capacitors 13.

  Next, in order to obtain the capacitance value C, the slope of the voltage across the capacitor during charging is obtained.

The inclination is obtained as a change width Vd of the voltage across the capacitor during a certain time t. Thereby, from the relational expression of charge amount Q = I · t = C · Vd to be charged,
C = I · t / Vd (2)
As required. Here, since I and t are determined, C can be obtained by obtaining Vd.

  In order to obtain Vdx for the capacitor x in FIG. 2, first, the voltage V1 across the capacitor x is obtained at an arbitrary time t1. As described above, the switch 21 is controlled to switch and the voltage at both ends at the time t1 is sampled and held, and the multiplexer 39 is sequentially switched for each of the four sampling capacitors 20 to read the voltage across the capacitor 13.

  As a result, V1 corresponding to 300 capacitors is obtained at high speed and at the same time sampling.

  Next, when the time t elapses and becomes t2, V2 of 300 capacitors 13 is obtained in the same manner.

  Thus, Vdx = V2−V1 can be obtained. This is obtained for 300 capacitors 13, and the capacitance value C is obtained from equation (2).

  Thereafter, charging is performed until the reference voltage Vf of the capacitor is reached.

  The operation at this time is such that the comparator 28 compares the divided voltage Vs corresponding to the voltage across the capacitor with the divided voltage Vs of the voltage dividing resistor A27 and the reference voltage Vf output from the balance voltage setting means 31, and exceeds the reference voltage Vf. Then, the comparator 28 turns on the switch 25 so that a current flows through the balance circuit, thereby controlling the voltage across the capacitor 13 so as not to exceed the reference voltage Vf.

  In this way, charging is completed, but the capacitor 13 varies, and particularly as the deterioration progresses and approaches the operating limit, the charging ends quickly as indicated by the dotted line in FIG.

  That is, when it deteriorates, the internal resistance value R increases and the capacitance value C decreases, so that the stored charge amount Q also decreases. The amount of charge Q corresponds to the time integral (area) during charging in the graph of FIG. 2, but the capacitor y, whose deterioration of the dotted line has progressed, has a small Q, so the slope at the time of charging increases, and the reference voltage (full charge) is quickly reached. ).

  Therefore, since the charging completion time varies depending on the capacitor 13, charging is performed until all the capacitors 13 reach the reference voltage.

  For such a capacitor y, the internal resistance value Ry and the capacitance value Cy are obtained in the same manner as the capacitor x.

  When charging is completed as described above, the charging switch 14 is turned off. At this time, the internal resistance value R and the capacitance value C of all 300 capacitors 13 are obtained.

  Next, the degree of deterioration of each capacitor 13 is predicted, and the balance voltage is controlled so as to delay the progress of deterioration for the capacitor 13 that has deteriorated from the average value of the degree of deterioration.

  Further, in order to maintain the specified voltage as the power storage device, the balance voltage is controlled so that a deterioration load is applied to the capacitor 13 having a sufficient progress of deterioration.

  A method for obtaining the balance voltage will be described.

  FIG. 3 shows operation limit lines of the capacitor 13 at each temperature when the capacitance value C is taken on the horizontal axis and the internal resistance value R is taken on the vertical axis. That is, when C and R obtained by the above-described method are plotted as coordinates (C, R), if the operating limit line at the current temperature is exceeded, it can be determined that the capacitor 13 has reached the operating limit.

  The operation limit line is obtained in advance by performing an operation limit test on the capacitor 13, and the data is stored in the microcomputer 37.

  FIG. 3 shows an image obtained by plotting the coordinates (Cn, Rn): n = 1 to 300 of the 300 capacitors 13 already obtained by dots.

  When the capacitors 13 are all new and are selected and used with little variation in C and R, the coordinate point is solidified in the lower right part of the graph of FIG. 3, but considering normal use, the capacitor 13 varies. Since this occurs, the deterioration proceeds with a certain width.

  When the operating limit is approached, the capacitance value C decreases and the internal resistance value R increases, so that the distribution is generally from the lower right to the upper left. FIG. 3 shows an image of such a state distribution.

  The deterioration progress prediction of the capacitor 13 having such a distribution will be described.

  Originally, as described above, the capacitance value C decreases and the internal resistance value R increases. Therefore, here, the distance until the extension line of the tendency reaches the operation limit line is defined as the deterioration progress degree. However, since the behavior with respect to the degree of deterioration (change in the distance to the operation limit line) is the same for both C and R, the degree of deterioration control may be performed using either parameter.

  However, for the capacitance value C, Vdx (slope) described in FIG. 2 is monitored and controlled. However, since C and R are obtained during charging, Vdx is monitored and controlled after charging is completed. I can't control it.

  Therefore, attention was focused on the control of the internal resistance value R as another parameter of the degree of deterioration.

  In the 300 plots of FIG. 3, the plots of coordinates (Cm, Rm) obtained by averaging Cn and Rn are indicated by black circles. Among the plots, the deterioration progress with respect to the average internal resistance value Rm is assumed that the current temperature is 30 ° C. (the temperature can be known from the temperature data of the temperature sensor 41). This corresponds to the shortest distance Rlm of the line.

  Therefore, the voltage across each capacitor 13 is corrected so that the shortest distance between Rn of the 300 capacitors 13 and the operation limit line, that is, the degradation progress Rln is all Rlm.

  In other words, for a capacitor x that has a long degradation progress Rlx, a load is applied in the operation limit characteristic by giving a slightly higher balance voltage (in a direction in which the degradation progress is slightly shortened), and conversely For the capacitor y having a short deterioration degree Rly, adjustment is made in the direction of extending the deterioration degree by giving a slightly lower balance voltage so as to reduce the load in the operation limit characteristics.

  As a result, the variation width of the deterioration progress of all the capacitors 13 is adjusted to be small.

  This utilizes the feature that the deterioration degree of the capacitor 13, in other words, the life is greatly influenced by the balance voltage, and the life is shortened as the balance voltage is increased.

  Such a control method will be specifically described below.

  Since the deterioration degree Rlx of the capacitor x is longer than the average deterioration degree Rlm, the difference ΔRlx can be added to obtain the average deterioration degree Rlm.

  Similarly, since the deterioration progress Rly of the capacitor y is shorter than the average deterioration progress Rlm, the average deterioration progress Rlm can be obtained by subtracting the difference ΔRly.

  Therefore, as shown in FIG. 4, a voltage equivalent to ΔRlx is applied to the former by using the above-mentioned characteristics to the voltages Vx and Vy across the current capacitor x and capacitor y under full charge. Controls the progress of deterioration by subtracting a voltage corresponding to ΔRly.

The adjustment voltage at this time is
+ ΔVlx = + ΔRlx · I (3)
−ΔVly = −ΔRly · I (4)
Thus, the progress of deterioration corresponding to these adjustment voltages or the suppression of deterioration is achieved. Here, I is a current.

  Therefore, the actual operation is summarized as follows.

  First, after all the capacitors 13 have reached the reference voltage (full charge), the correction calculation of the deterioration progress is performed to obtain ΔVln (n = 1 to 300) in each capacitor 13.

  Next, after the charge switch 14 is turned on and a specified voltage (750 V in the first embodiment) is applied to both ends of all the capacitors 13, only ΔVln determined at an arbitrary balance voltage adjustment timing shown in FIG. The digital potentiometer 33 is adjusted so that the reference voltage changes.

  Here, an adjustment signal of the microcomputer 37 is transmitted to the digital potentiometer 33 by serial communication.

  For this reason, since it is inefficient to transmit the adjustment signal from one microcomputer 37 to the 300 digital potentiometers 33 by serial communication at a time, the adjustment signal is transmitted to the four digital potentiometers 33 connected to each control unit 30. Like to do.

  Note that the charge / discharge control circuit 12 collects the balance voltage information from each control unit 30 and mutually adjusts the balance voltage from each control unit 30 so that the power storage device as a whole has a specified voltage.

  At this time, the digital potentiometer 33 is controlled via the photoelectric converter group 36 to electrically insulate the microcomputer 37 from the peripheral circuit 17.

  The adjustment in the direction of decreasing the voltage across the capacitor 13 can be performed by turning on the switch 25 and causing a current to flow through the balance resistor 24, but it is necessary to apply a voltage in the increasing direction. Therefore, the charge control is performed again on both ends of all the capacitors 13 to enable adjustment of the voltage across the capacitors 13.

  As described above, since the reference voltage, in other words, the balance voltage is adjusted so as to approach the average deterioration degree, the voltage across both capacitors 13 is different, but the voltage across all capacitors 13 is 750 V, and the necessary voltage Can be secured.

  When the adjustment of all the capacitors 13 is completed, the charging switch 14 is turned off.

  As described above, the balance voltage setting means 31 is controlled so that the balance voltage of each capacitor 13 is adjusted and the variation width of deterioration of each capacitor is reduced.

  When the voltage across the capacitor 13 is increased at the time of adjusting the balance voltage, since the deterioration proceeds rapidly if the voltage is too high, control is performed so as not to exceed the specified voltage. The specified voltage is, for example, a voltage that is 10% higher than the rated voltage of the capacitor 13. Therefore, when the microcomputer 37 controls the digital potentiometer 33 so that the voltage across the capacitor 13 becomes smaller than the specified voltage, rapid deterioration of the capacitor 13 can be avoided, and the service life of the power storage device is extended. It becomes possible.

  In the first embodiment, the balance voltage is adjusted so as to approach the average deterioration progress of each capacitor 13, but it is inevitable that all the capacitors 13 will deteriorate. Therefore, the control unit 30 detects the deterioration progress of each capacitor 13 by the deterioration progress detection means and transmits it to the charge / discharge control circuit 12. However, all the capacitors 13 are deteriorated from the deterioration progress obtained at this time. If it is found, the charge / discharge control circuit 12 outputs the information from the connector 12a to the control circuit (not shown) of the hybrid vehicle. Thereby, the control circuit of the hybrid vehicle notifies the driver that the service life of the power storage device has elapsed by performing an operation such as issuing a warning to the driver. By operating in this way, the reliability of the deterioration of all the capacitors 13 is ensured while extending the service life of the power storage device.

  Further, when the use of the vehicle is finished and the IG is turned off, in the first embodiment, the discharge switch 15 is turned on to forcibly discharge in order to extend the life of the capacitor, but when the vehicle is used again, the IG is turned off. When turned on, since the non-volatile memory 35 is built in the digital potentiometer 33, the reference voltage Vf output by the balance voltage setting means 31 is the balance voltage adjusted last time.

  Even in this case, the reference voltage is adjusted again by the method described so far. By repeating this every time the vehicle is used, the deterioration progress of all the capacitors 13 can be made almost equal in the end.

  In the first embodiment, the reference voltage adjustment is performed at the time of starting the vehicle or the power storage device body because the charging characteristics to the capacitor 13 shown in FIGS. 2 and 4 are necessary.

  However, since the deterioration of the capacitor 13 hardly progresses sharply, the reference voltage adjustment need not be performed every time the vehicle is started, and may be performed every predetermined time, for example, every time the vehicle is inspected.

  With the above configuration and operation, the deterioration progress of all the capacitors 13 is controlled to reduce the variation width of the deterioration progress, thereby extending the service life of the power storage device as compared with the conventional case. As a result, the capacitor 13 and the power storage device body A power storage device that can reduce the number of replacements as much as possible has been realized.

  In the first embodiment, 300 capacitors 13 are connected in series, but this may be connected in parallel or in series-parallel depending on the required power.

  In the first embodiment, the system for forcibly discharging each capacitor 13 after the use of the vehicle has been described. However, this may be similarly adjusted in a system for spontaneous discharge.

(Embodiment 2)
Embodiment 2 of the present invention will be described below with reference to the drawings.

  FIG. 5 is a partially omitted block circuit diagram of the power storage device according to the second embodiment of the present invention. FIG. 6 is a correlation diagram between the capacitor leakage current and the deterioration progress ratio of the power storage device according to Embodiment 2 of the present invention. FIG. 7 is a correlation diagram between the amount of change in capacitor leakage current and the amount of change in balance voltage of the power storage device according to Embodiment 2 of the present invention.

  In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, detailed description thereof is omitted, and only different portions will be described.

  That is, the feature of the second embodiment is that the degree of deterioration of each capacitor 13 is not obtained from the internal resistance value R, but from the leakage current of each capacitor 13.

  Here, the configuration and operation for determining the degree of progress of deterioration from the leakage current will be described in detail.

  First, the difference in configuration from the first embodiment is as follows from the comparison between FIG. 1 and FIG.

1) The sampling capacitor 20 is eliminated. 2) The voltage across the capacitor 13 is not taken in by the control unit 30. 3) One of the switches 21 (3-terminal type) is connected to the conventional balance voltage adjusting means 23, and the other The capacitor 13, the current detection means 16, and the constant voltage source 42 are connected in series to form a closed loop circuit. 4) The current detection means 16 connected in series with the charge switch 14 of FIG. 1 is eliminated. Next, the operation will be described. .

  When the IG is turned on when using the vehicle, the information is input from the charge / discharge control circuit 12 to the microcomputer 37 of each control unit 30.

  The charge / discharge control circuit 12 turns on the charge switch 14, and the microcomputer 37 of each control unit 30 switches the switch 21 to the balance voltage adjusting means 23 side. Thereby, a charging current flows from the battery 11.

  In addition, 300 switches 21 are provided as in the first embodiment, and all the switches 21 are configured to be switched in the same direction via the control unit 30 according to instruction data from the charge / discharge control circuit 12 all at once.

  Charging is continuously performed until all capacitors 13 are fully charged while adjusting both-end voltages by the balance voltage adjusting means 23.

  When the charging is completed, the charging / discharging control circuit 12 turns off the charging switch 14, and then transmits information for switching the switch 21 to the current detecting means 16 side by broadcast output to each control unit 30.

  Thereby, the closed circuit of the capacitor 13, the constant voltage source 42, the current detection means 16, and the switch 21 forming a part of the deterioration progress detection means is configured. In addition, the deterioration progress detection means includes software of the microcomputer 37 built in the control unit 30. The operation will be described later.

  In the closed circuit configured by switching the switch 21, ideally no current flows, but the leakage current LC of the capacitor 13 flows due to the deterioration of the capacitor 13. This is due to a decrease in the insulation resistance of the capacitor 13 along with the deterioration, and becomes data directly related to the progress of the deterioration of the capacitor 13. This LC is detected by the current detection means 16.

  In the second embodiment, the current detection means 16 is composed of a highly accurate resistor, and the LC is measured from the voltage across the resistor generated by the LC.

  Note that the current detection means 16 may be configured by an electrical insulation technique such as a magnetic field sensor.

  Here, as in the first embodiment, 75 LCs of four capacitors 13 are measured by 75 control units 30 in order to quickly measure LCs of 300 capacitors 13.

  In the measurement method, the output of the current detection means 16 is sequentially switched by the multiplexer 39 as in the first embodiment.

  When the LC loading is finished, the switch 21 is switched again to the balance voltage adjusting means 23 side.

  Next, the deterioration progress ratio L is obtained from the obtained LC. Here, the deterioration progress ratio L is a value that assumes a ratio with the current deterioration progress when the limit value of the deterioration progress of the capacitor 13 is 1. For example, the deterioration progresses for 20 years for vehicles. As the limit value of the degree, 20 years is 1, so 0.5 indicates that the deterioration progress is 10 years.

  This deterioration progress ratio L has a correlation with LC, and FIG. 6 shows the result of experimentally determining the relationship between the two. In FIG. 6, the horizontal axis represents the leakage current LC, and the vertical axis represents the deterioration progress ratio L.

  As shown in FIG. 6, the deterioration progress ratio L is in a non-linear inverse proportional relationship with LC. The larger the LC, the smaller the deterioration progress ratio L, that is, the shorter the service life. In addition, there is a region where the deterioration progress ratio L decreases rapidly as LC increases.

  Therefore, the balance voltage of each capacitor 13 is adjusted as follows.

  First, the deterioration progress ratio L is obtained from the LC for each of the 300 capacitors 13. This is shown in FIG. Since LC varies, the degradation progress ratio L varies between the maximum degradation progress ratio Lmax and the minimum degradation progress ratio Lmin corresponding to the width of the maximum leakage current LCmax and the minimum leakage current LCmin shown on the horizontal axis. It will be.

  Next, the total deterioration progress ratio L is averaged to obtain an average deterioration progress ratio Lm. Lm is indicated by a black circle on the vertical axis of FIG.

  Here, an arbitrary capacitor x is considered. It is assumed that the deterioration rate ratio L of the capacitor x is Lx. Lx is indicated by a white circle on the vertical axis of FIG.

  From FIG. 6, it can be said that since Lx is larger than Lm, the deterioration progress is larger than the average. Therefore, in order to average the deterioration progress, a deviation ΔLx with respect to the average deterioration progress ratio Lm is obtained for each capacitor 13 so that the smaller one becomes larger and the smaller one becomes larger. The corresponding balance voltage V is controlled.

  This will be specifically described below.

  Deviation ΔLx is expressed by equation (5) from deterioration rate ratio Lx of capacitor x and average deterioration rate ratio Lm.

ΔLx = Lx−Lm (5)
Next, a deviation (change amount) ΔLCx of the leakage current corresponding to ΔLx is obtained. Therefore, the leakage current LCx corresponding to Lx is read according to the arrow in FIG. At the same time, the leakage current LCm corresponding to Lm is read according to the arrow in FIG.

  The deviation between the obtained LCx and LCm is the leakage current change amount ΔLCx.

That is,
ΔLCx = LCm−LCx (6)
It is requested from.

  If ΔLCx is determined, the balance voltage change amount ΔVx of the capacitor x can be obtained from FIG.

  That is, in FIG. 7, the horizontal axis represents the leakage current change amount ΔLC and the vertical axis represents the balance voltage change amount ΔV, and the correlation between the two is experimentally obtained and shown for each temperature. Assuming that it is ° C., in the graph (shown by a bold line), the balance voltage change amount ΔVx corresponding to ΔLCx can be determined by reading the graph as indicated by the arrows in the figure. Thereby, the temperature-corrected balance voltage change amount ΔVx is obtained.

  The balance voltage Vn is determined from the equation (7) from the balance voltage change amount ΔVn (n = 1 to 300) of all the capacitors 13 and the current balance voltage Vfn by the above procedure.

Vn = Vfn + ΔVn (7)
When all the balance voltages Vn are determined as described above, the microcomputer 37 adjusts the digital potentiometer 33 of the balance voltage setting means 31 via the photoelectric converter group 36, and controls so that the voltage across each capacitor 13 becomes the balance voltage Vn. .

  Since the subsequent operation is the same as that of the first embodiment, the details are omitted. However, the voltage across the 300 capacitors 13 can be quickly made the balance voltage Vn.

  With the above operation, the adjustment for averaging the deterioration progress of the capacitor 13 is completed. This operation is normally performed when the vehicle or the power storage device main body is inspected in the second embodiment because the capacitor 13 usually hardly deteriorates rapidly.

  At this time, since the digital potentiometer 33 stores the set value in the non-volatile memory 35 as in the first embodiment, the voltage across the capacitor 13 is adjusted by Vn (= reference voltage Vf) set at the time of inspection at the time of restart. is doing.

  With the above configuration and operation, the variation range of the deterioration degree of all the capacitors 13 is reduced, so that the service life of the power storage device can be extended as compared with the conventional case. A power storage device that can be reduced was realized.

(Embodiment 3)
FIG. 8 is a partially omitted block circuit diagram of the high-precision power storage device according to Embodiment 3 of the present invention.

  In FIG. 8, the same components as those in FIG. 5 are assigned the same reference numerals and detailed description thereof is omitted, and only different portions will be described.

  That is, the feature of the third embodiment is that the temperature sensor 41 is provided in the vicinity of each capacitor 13.

  This is effective in the case where all of the 300 capacitors 13 are not necessarily at the same temperature and unevenness occurs in the internal temperature of the power storage device.

  Accordingly, since it is necessary to read the temperatures at 300 locations at high speed, the output of the temperature sensor 41 is connected to the multiplexer 39 of the control unit 30, and the four temperature sensors 41 are sequentially read when the output of the current detection means 16 is read. The operation of reading the temperature data at the same time is performed simultaneously by the 75 control units 30.

  Thus, by accurately reading the temperature of each capacitor 13, when the balance voltage Vn is determined in FIG. 7, the temperature-corrected Vn can be determined from the graph corresponding to the more accurate temperature. Degradation progress can be adjusted with accuracy.

  Other configurations and operations are the same as those in the second embodiment.

  With the above configuration and operation, a power storage device that can further extend the deterioration progress of the capacitor 13 as compared with the configuration of the second embodiment can be realized.

  Note that the configuration in which each capacitor is provided with the temperature sensor 41 is also applicable to the power storage device of the first embodiment, and the same effect can be obtained.

(Embodiment 4)
FIG. 9 is a partially omitted block circuit diagram of the temperature controller-equipped power storage device according to the fourth embodiment of the present invention.

  In FIG. 9, the same components as those in FIG. 8 are given the same reference numerals and detailed description thereof is omitted, and only different portions will be described.

  That is, the feature of the fourth embodiment is that 300 sets of capacitors 13 and peripheral circuits 17 are provided in the temperature controller 43. As a result, the overall temperature of the capacitor 13 and the peripheral circuit 17 can be kept constant.

  As for the temperature of the temperature regulator 43, a set temperature signal is transmitted to the temperature regulator controller 44 via the microcomputer 37 based on the command of the charge / discharge control circuit 12. As a result, the temperature controller 43 is kept constant at an arbitrary set temperature.

  In this case, the balance voltage Vn to each capacitor 13 can be obtained while keeping the temperature of each capacitor 13 constant. Therefore, the determination of Vn after temperature correction according to FIG. Although it is used, a slight temperature unevenness can be detected by the temperature sensor 41 provided in each capacitor 13, so that the deterioration progress can be adjusted with higher accuracy than in the third embodiment. .

  Since the temperature controller 43 is further provided, the deterioration progress of the capacitor 13 becomes larger (longer) as the temperature is lower as apparent from FIG. 3. Therefore, the deterioration progress of the capacitor 13 can be controlled by adjusting the temperature lower. Can be extended.

  Other configurations and operations are the same as those in the second embodiment.

  With the above configuration and operation, it is possible to realize a power storage device capable of further extending the deterioration progress of the capacitor 13 as compared with the configuration of the third embodiment.

  Note that the configuration in which the capacitor 13 and the entire peripheral circuit 17 are built in the temperature controller can also be applied to the power storage device of the first embodiment, and the same effect can be obtained.

  The power storage device according to the present invention can reduce the variation range of the deterioration progress of all capacitors by adjusting the deterioration progress of each capacitor, thereby extending the service life as a power storage device. As a result, it is possible to reduce the number of replacements of the capacitor and the power storage device itself as much as possible, so that it is particularly useful as an auxiliary power storage device for a motor drive battery of a hybrid vehicle.

FIG. 3 is a partially omitted block circuit diagram of the power storage device according to Embodiment 1 of the present invention. Time-dependent characteristic diagram of voltage across capacitor during charging of power storage device in Embodiment 1 of the present invention Capacitor operating limit characteristic diagram with the capacitance value and internal resistance value of the power storage device in Embodiment 1 of the present invention as parameters Time-dependent characteristic diagram of the voltage across the capacitor after adjusting the balance voltage of the power storage device in Embodiment 1 of the present invention Partially omitted block circuit diagram of the power storage device in Embodiment 2 of the present invention Correlation diagram between capacitor leakage current and deterioration progress ratio of power storage device in Embodiment 2 of the present invention Correlation diagram between amount of change in capacitor leakage current and amount of change in balance voltage of power storage device according to Embodiment 2 of the present invention Partially omitted block circuit diagram of the high-precision power storage device in Embodiment 3 of the present invention Partially omitted block circuit diagram of a power storage device with a temperature controller in Embodiment 4 of the present invention Block circuit diagram showing a conventional abnormality detection method

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 Capacitor 16 Current detection means 21 Switch 23 Balance voltage adjustment means 30 Control part 33 Digital potentiometer 35 Non-volatile memory 36 Photoelectric converter group 37 Microcomputer 41 Temperature sensor 42 Constant voltage source 43 Temperature controller

Claims (10)

A plurality of capacitors connected in series or in parallel or in series and parallel;
A deterioration progress detection means for determining the deterioration progress of the capacitor;
A balanced voltage adjusting means connected before Kiki Yapashita,
The deterioration progress detection means and the balance voltage adjustment means are connected, and comprises a control unit with a built-in microcomputer,
From the mean value of the control unit the deterioration degree of the crisis Yapashita before detected by the deterioration degree detecting means determines variation width of the deterioration degree of the front hear Yapashita is a balanced voltage as decreases respectively,
With a voltage applied across both capacitors connected,
Power storage device across voltage before crisis Yapashita controls the balance voltage adjusting means so that the balanced voltage. Deterioration degree detecting means electric storage device main body of the starting current at the time of charging the key Yapashita when, the voltage, and the internal resistance of the crisis Yapashita before the temperature data obtained based on from the temperature sensor provided in said capacitor near The power storage device according to claim 1, wherein the deterioration progress of the capacitor is obtained from a correlation between the value and the deterioration progress. Deterioration degree detecting means and a constant voltage source connected in parallel to the key Yapashita,
Current detection means connected in series between the capacitor and the constant voltage source;
The switch is connected between the capacitor and the current detection means, and switches to either one of the balance voltage adjustment means or the current detection means,
When detecting the degree of deterioration, the switch determines the leakage current of the capacitor by selecting the current detection means side,
The power storage device according to claim 1 for determining the deterioration degree of the front-handed Yapashita from the correlation of the leakage current and deterioration degree. The power storage device according to claim 1, wherein the control of the balance voltage adjusting means is performed every predetermined period. A temperature controller is provided to keep the temperature of the entire capacitor constant.
The power storage device according to claim 1 for obtaining a balance voltage before crisis Yapashita the temperature before crisis Yapashita while constant. The power storage device according to claim 1, wherein the balance voltage adjusting means and the microcomputer are electrically insulated by providing an electrical indirect connection means in the control unit. The power storage device according to claim 1, wherein the balance voltage adjusting means is a digital potentiometer including a nonvolatile memory whose resistance value can be adjusted by a signal from the control unit. · The Yapashita respectively provided temperature sensors in the vicinity of power storage device according to balance voltage prior handed Yapashita to claim 1, determined by temperature compensation. Balanced voltage adjusting means, a power storage device according to claim 1 for controlling so as the voltage across the key Yapashita does not exceed the specified voltage. The power storage device according to claim 1, wherein when the deterioration progress detection unit detects that all the capacitors are deteriorated, the information is output.

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