JP2012132758A - Deterioration determination device for power storage device and vehicle mounting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine deterioration of a power storage device without having an excessive amount of heat generation of a resistor and without taking excessive time in capacity measurement of a power storage device.SOLUTION: A deterioration determination device for a power storage device has a resistor 7 connected to a power storage device (3) in series and a determination part (10) which determines deterioration of the power storage device (3) by calculating the capacity of the power storage device (3) based on a voltage value of the power storage device (3) after flowing a discharge current I from the power storage device (3) to the resistor 7 for a fixed time. The ratio of internal resistance value (r×n) of the power storage device (3) when it is new to the resistance value R of the resistor 7 is set to 0.02% or more and 1% or less.

Description

  The present invention obtains the capacity of the electricity storage device based on the resistor connected in series with the electricity storage device and the voltage value of the electricity storage device after flowing a discharge current from the electricity storage device through the resistor for a predetermined time. The present invention relates to a deterioration determination device including a determination unit that determines deterioration of the power storage device, and a vehicle including the same.

  In recent years, for the purpose of further improving the fuel efficiency of a vehicle, a so-called deceleration regenerative system that collects energy at the time of deceleration as regenerative power by intensively generating power with an alternator when the vehicle decelerates is becoming widespread. .

  In a vehicle equipped with the deceleration regeneration system as described above, a capacitor (condenser) such as an electric double layer capacitor or a recharge ion capacitor is used as a device (storage device) for storing the power generated intensively during deceleration. ) May be used. Unlike secondary batteries such as lead-acid batteries (which store electrical energy through chemical reactions at the electrodes), capacitors physically adsorb charges, so the charge and discharge reactions are fast, and the internal resistance is also low. There are few characteristics. For this reason, a large current supplied from the alternator at the time of deceleration can be instantaneously absorbed, and is being widely used as a power storage device for a vehicle deceleration regeneration system.

  Here, when charging and discharging are repeatedly performed on the capacitor, the deterioration of the capacitor proceeds due to decomposition of the electrolytic solution accompanying the rise in the temperature of the capacitor. Since the capacity of the capacitor gradually decreases as the capacitor deteriorates, the capacitor needs to be replaced when the capacity decreases to some extent.

  The following Patent Documents 1 to 3 are known as techniques for determining (diagnosis) the deterioration of the capacitor. In all of the methods for determining deterioration disclosed in these documents, the electric power charged in the capacitor is discharged over a predetermined time through a resistor connected to the capacitor, and the capacitance of the capacitor is determined based on the capacitor voltage after the discharge. The degree of decrease (degradation progress) is determined.

JP 2006-173385 A JP 2008-66390 A JP 2008-27946 A

  By the way, when the electric power charged in the capacitor is discharged through the resistor as described above, depending on the resistance value of the resistor, the current flowing through the resistor becomes too large and the resistor excessively generates heat, or the capacitor discharges. However, there is a problem that the time required for determining the deterioration (time required for measuring the capacitance of the capacitor) becomes long without progressing easily.

  The resistance value of the resistor also affects the measurement accuracy of the capacitor capacity. That is, when the deterioration of the capacitor progresses, not only the capacitance of the capacitor decreases, but also a phenomenon that the internal resistance of the capacitor increases. For this reason, depending on the resistance value of the resistor, the increase in the internal resistance affects the measurement result of the capacitor capacitance, and there arises a problem that the deterioration of the capacitor cannot be accurately determined.

  In addition, the above-described needs for accurately determining a decrease in capacity (presence / absence of deterioration) also exist for various power storage devices other than capacitors.

  The present invention has been made in view of the circumstances as described above, and the electricity storage device can be accurately obtained within a range in which the amount of heat generated by the resistor is not excessive and the time required for measuring the capacity of the electricity storage device does not become too long. It is an object of the present invention to provide a degradation determination device capable of determining degradation of a vehicle and a vehicle equipped with the degradation determination device.

  In order to solve the above-described problems, the present invention provides a resistor connected in series with an electricity storage device, and a voltage value of the electricity storage device after a discharge current from the electricity storage device flows through the resistor for a predetermined time. And a determination unit for determining deterioration of the electricity storage device by determining the capacity of the electricity storage device based on the resistance value of the resistor, the internal resistance value of the electricity storage device when new to the resistance value of the resistor The ratio is set to 0.02% or more and 1% or less (claim 1).

  In the present invention, “electric storage device” is a general term for batteries that can be repeatedly charged and discharged, and a capacitor that physically adsorbs electric charge and a capacitor that stores electricity using a chemical reaction. It is a concept that includes both secondary batteries.

  According to the present invention, by setting the resistance value of the resistor connected to the electricity storage device in the above range, the amount of heat generated by the resistor due to the passage of the discharge current can be obstructed for work such as maintenance. The measurement time required for obtaining the capacity of the electricity storage device can be suppressed to a length that is practically acceptable. Moreover, since the resistance value of the resistor is sufficiently larger than the internal resistance value of the electricity storage device, the increase in internal resistance accompanying the deterioration of the electricity storage device is minimized to affect the voltage value of the electricity storage device. Therefore, only a decrease in the capacity of the electricity storage device can be accurately measured. As described above, according to the present invention, it is possible to accurately determine the presence / absence of deterioration of an electricity storage device based on a decrease in capacity while considering practicality.

  Here, the degradation determination apparatus of the present invention can be applied to various types of power storage devices, but is particularly suitable for power storage devices having charge / discharge characteristics such that the voltage value under a constant current changes linearly over time. (Claim 2).

  Examples of the battery having charge / discharge characteristics as described above include an electric storage device including at least one of an electric double layer capacitor, a rechargeable ion capacitor, or a high-power lithium ion battery.

  For example, when the electricity storage device includes one or more electric double layer capacitors, the resistance value of the resistor per electric double layer capacitor is preferably set to 0.1Ω or more and 5Ω or less (claim 4). ).

  Since the internal resistance of the electric double layer capacitor when it is new is about 1 mΩ, the ratio of the internal resistance value of the electricity storage device to the resistance value of the resistor is set by setting the resistance value of the resistor in the above range. It becomes 0.02% or more and 1% or less, and the presence / absence of deterioration of the electricity storage device can be accurately determined while considering practicality.

  The storage device deterioration determination apparatus as described above is a vehicle equipped with a so-called deceleration regeneration system, that is, an alternator driven by an engine, a DC / DC converter interposed between the alternator and an electric load, and the above A power storage device connected in series with the alternator so as to store the electric power generated by the alternator. The present invention can be suitably applied to a vehicle that is recovered as regenerative electric power (claim 5).

  According to this configuration, it is possible to accurately determine the deterioration of the power storage device provided as a part of the vehicle deceleration regeneration system in consideration of practicality, and to improve the reliability of the deceleration regeneration system.

  In the vehicle, the resistor is preferably connected in parallel with the DC / DC converter via a switch.

  Alternatively, the resistor is connected in parallel through a converter circuit and a switch inside the DC / DC converter.

  According to these configurations, the voltage value of the electricity storage device can be measured without being affected by the circuit in the DC / DC converter, and deterioration of the electricity storage device can be accurately determined based on the value.

  For example, when the influence of the converter circuit on the measurement is small, the resistor may be connected in series with the converter circuit inside the DC / DC converter.

  When the electric storage device is composed of ten electric double layer capacitors connected in series, the resistance value of the resistor is preferably set to 1Ω or more and 50Ω or less (claim 9).

  By setting the resistance value of the resistor within such a range, the ratio of the internal resistance value of the electricity storage device to the resistance value of the resistor can be set to 0.02% or more and 1% or less. Can be accurately determined in consideration of practicality.

  As described above, according to the present invention, the deterioration of the electricity storage device can be accurately determined within a range in which the amount of heat generated by the resistor is not excessive and the time required for measuring the capacity of the electricity storage device does not become too long. Can be provided, and a vehicle equipped with the same.

It is a figure showing the schematic structure of the vehicles carrying the deceleration regeneration system concerning one embodiment of the present invention. It is a flowchart which shows the specific procedure when performing deterioration determination control with respect to the capacitor unit contained in the said deceleration regeneration system. It is the graph which showed how the voltage value changed with discharge time at the time of discharge of the above-mentioned capacitor unit. It is the graph which showed the relationship between the said capacitor voltage and a capacitor capacity | capacitance for every elapsed time after a discharge start. It is the prediction diagram which predicted progress of degradation of the above-mentioned capacitor unit. It is the graph which showed simultaneously the relationship between the resistance value of the resistor connected to the said capacitor unit, and the emitted-heat amount, and the relationship between the resistance value of the said resistor, and the measurement time required for deterioration determination. It is a figure for demonstrating the deformation | transformation Example of this invention. It is a figure for demonstrating the characteristic of the electrical storage device which can apply the deterioration determination apparatus of this invention suitably.

(1) Overall Configuration FIG. 1 is a diagram showing a schematic configuration of a vehicle equipped with a deceleration regeneration system according to an embodiment of the present invention. The vehicle shown in the figure includes an engine 1 provided as a driving source for traveling, an alternator 2 that generates power by obtaining driving force from the engine 1, and an alternator 2 connected in series, and the regenerative power generated by the alternator 2 is generated. A capacitor unit 3 for storing electric power (corresponding to an electric storage device according to the present invention), an electric load 4 composed of various lights, air conditioners, instruments, etc., and a DC / DC connected between the electric load 4 and the alternator 2 A PCM (power-train control) comprising a DC converter 5, a battery 6 comprising a lead storage battery for supplying power to the electric load 4, a CPU for controlling the operation of each part such as the engine 1 and the alternator 2 and various memories. module) 10.

  The capacitor unit 3 is formed by connecting a plurality (here, 10) of capacitor cells 17 each consisting of a single electric double layer capacitor in series. Hereinafter, each electric double layer capacitor 17 is referred to as a capacitor cell 17. Each capacitor cell 17 has an internal resistance 16. In FIG. 1, the resistance value of each internal resistance 16 is r. The resistance value (internal resistance value) r of the internal resistor 16 is generally about 1 mΩ when new.

  The capacitor unit 3 is connected in series with the alternator 2 and stores the electric power generated by the alternator 2 when the vehicle is decelerated. That is, the power generation in the alternator 2 is basically performed only when the vehicle is decelerated, and the electric power is intensively charged in the capacitor unit 3. Thereby, the energy at the time of deceleration is collect | recovered as regenerative electric power. The alternator 2 has a built-in rectifier 15 that converts the generated AC power into DC power. The generated power generated by the alternator 2 is converted to DC by the rectifier 15 and then sent to the capacitor unit 3. . Capacitor unit 3 can be charged to a maximum of about 25 V, and the electric power generated by alternator 2 exceeding this amount is supplied to battery 6 via DC / DC converter 5 (after being stepped down by DC / DC converter 5). Sent to.

  On the other hand, in the operating state other than the time of deceleration (during idling, steady running, or acceleration), power generation by the alternator 2 is basically not performed. That is, the electric power charged in the capacitor unit 3 when the vehicle is decelerated is sequentially sent to the battery 6 through the DC / DC converter 5 and stored there. And in the driving | running state other than the time of deceleration, the electric power stored in the said battery 6 is supplied to the electric load 4, and the electric power of the electric load 4 is supplied without operating the alternator 2. FIG. Of course, depending on the traveling scene of the vehicle, power generation by the alternator 2 may be temporarily performed in an operating state other than during deceleration.

  Here, as in the above configuration, the capacitor unit 3 composed of a plurality of electric double layer capacitors and the battery 6 composed of a lead storage battery are used together by taking advantage of the characteristics of the capacitor unit 3 and the battery 6. This is for efficiently recovering energy during deceleration. That is, since the capacitor unit 3 physically stores electric charges like a capacitor, it can receive a large current instantaneously, and temporarily generates electric power generated intensively by the alternator 2 during deceleration. Suitable for storing electricity. On the other hand, the battery 6 is a power storage device using a chemical reaction, and cannot handle a temporary large current, but has a property that the charging capacity is larger than that of the capacitor unit 3. Therefore, the electric power generated by the alternator 2 is temporarily stored in the capacitor unit 3 and then sent to the battery 6 having a large capacity. Note that the electric power stored in the capacitor unit 3 may be directly supplied to the electric load 4 of the vehicle without passing through the battery 6.

  The capacitor unit 3 is provided with a temperature sensor 18 for detecting the temperature of the capacitor unit 3 and a voltage sensor 19 for detecting the voltage of the capacitor unit 3. The detection values of the temperature sensor 18 and the voltage sensor 19 are input to the PCM 10 as electric signals.

  A resistor 7 is provided between the capacitor unit 3 and the ground (vehicle body). In FIG. 1, the resistance value of the resistor 7 is R. The resistor 7 is connected in series via the capacitor unit 3 and the switch 8. On the other hand, in relation to the DC / DC converter 5, the resistor 7 is connected in parallel via the DC / DC converter 5 and the switch 8.

  When the switch 8 determines deterioration of the capacitor unit 3 (details will be described later), the switch 8 receives a command from the PCM 10 to connect the capacitor unit 3 and the resistor 7, and to connect the capacitor unit 3 to the DC / DC. It operates so as to cut off the connection with the converter 5. On the other hand, at the other normal times, the switch 8 operates to disconnect the connection between the capacitor unit 3 and the resistor 7 and to connect the capacitor unit 3 and the DC / DC converter 5 contrary to the above. To do.

(2) Degradation determination of the capacitor unit The vehicle with the deceleration regeneration system having the above configuration has a function for determining the deterioration of the capacitor unit 3. Control for determining the deterioration of the capacitor unit 3 is performed by the PCM 10. That is, the PCM 10 corresponds to a determination unit according to the present invention that determines deterioration of the capacitor unit 3. Hereinafter, how the deterioration of the capacitor unit 3 is determined by the control of the PCM 10 will be described.

  FIG. 2 is a flowchart showing a specific procedure of the deterioration determination control executed by the PCM 10. When the process shown in this flowchart starts, the PCM 10 counts the number of days that have elapsed since the previous deterioration determination was made (in the first case, the number of days that have elapsed since the start of use of the vehicle), and the number of days is equal to or greater than the predetermined number of days. It is determined whether or not (step S1). That is, the deterioration determination of the capacitor unit 3 does not have to be performed every day and may be performed periodically. Therefore, it is first determined whether or not the number of days elapsed from the previous implementation date is equal to or greater than the predetermined number of days.

  If it is determined YES in step S1 and it is confirmed that the predetermined number of days have elapsed, the PCM 10 performs control to read the temperature Tc and the voltage Vc of the capacitor unit 3 from the temperature sensor 18 and the voltage sensor 19, respectively. Execute (Step S2).

  Next, the PCM 10 determines whether or not the capacitor unit 3 is stopped (step S3). Specifically, when neither charging from the alternator 2 to the capacitor unit 3 nor discharging from the capacitor unit 3 to the battery 6 is performed, for example, when the vehicle is parked (when the engine is stopped). Then, it is determined that the capacitor unit 3 is stopped. Even when the vehicle is traveling, the capacitor unit 3 is stopped if charging and discharging to the capacitor unit 3 can be stopped for a certain period or more, such as during cruising traveling on a highway. Is determined.

  When it is determined YES in step S3 and it is confirmed that the capacitor unit 3 is stopped, the PCM 10 detects the temperature Tc of the capacitor unit 3 detected by the temperature sensor 18 (hereinafter referred to as the capacitor temperature Tc). Is determined to be within a predetermined range (step S4). That is, it is desirable that the deterioration determination of the capacitor unit 3 is performed when the capacitor unit 3 is in a certain temperature state to some extent in order to ensure the accuracy of the determination. Therefore, the determination in step S4 is first executed so as to permit the deterioration determination only when the capacitor temperature Tc is within the predetermined range.

  When it is determined YES in step S4 and it is confirmed that the capacitor temperature Tc is within the predetermined range, the PCM 10 detects the voltage Vc of the capacitor unit 3 detected by the voltage sensor 19 (hereinafter referred to as the capacitor voltage Vc). It is determined whether or not there is a predetermined value (step S5). The predetermined value of the capacitor voltage Vc used for the determination here is a value determined in advance as a starting voltage for discharge control (step S6) of the capacitor unit 3 to be described later, for example, 12V (as an individual voltage of each capacitor cell 17). Is set to 1.2V). When the capacitor voltage Vc deviates from the predetermined value, the capacitor unit 3 may be intentionally charged / discharged until it reaches the predetermined value. For example, when the capacitor voltage Vc exceeds a predetermined value, the excess power is discharged to the battery 6, and when the capacitor voltage Vc is lower than the predetermined value, the insufficient power is charged by the battery 6. Try to cover.

  When it is determined YES in step S5 and it is confirmed that the capacitor voltage Vc is at a predetermined value, the PCM 10 starts control for causing the capacitor unit 3 to discharge (step S6). That is, by connecting the capacitor unit 3 and the resistor 7 and operating the switch 8 in a direction that cuts off the connection between the capacitor unit 3 and the DC / DC converter 5, the electric power charged in the capacitor unit 3 can be reduced. It is discharged to the ground (vehicle body) through the resistor 7.

  Then, the PCM 10 determines whether or not a predetermined time (for example, 300 sec) has elapsed after the start of the discharge from the capacitor unit 3 in step S6, based on the count value of the timer incorporated therein. (Step S7). Then, when it is determined as YES here and it is confirmed that a predetermined time has elapsed, the capacitor voltage Vc at that time (capacitor voltage Vc after the predetermined time has elapsed) is acquired from the voltage sensor 19, and the voltage value is obtained. Based on the above, control for calculating the capacitance C of the capacitor unit 3 (hereinafter also referred to as capacitor capacitance C) is executed (step S8).

  Here, how the capacitor capacitance C is calculated from the capacitor voltage Vc will be specifically described. FIG. 3 is a graph showing how the capacitor voltage Vc (V) changes according to the discharge time t (sec) when the capacitor unit 3 is discharged. A plurality of diagrams (curves) in this graph represent the difference in the decrease rate of the voltage Vc depending on the degree of deterioration of the capacitor unit 3. That is, if the electrolytic solution of the capacitor unit 3 (precisely, the electrolytic solution of each capacitor cell 17 constituting the capacitor unit 3) is decomposed and the capacitor unit 3 is deteriorated, the capacitance C is decreased. The rate of decrease in Vc increases as the deterioration progresses (that is, the capacitor capacitance C decreases). In FIG. 3, the diagram in which the decrease rate of the capacitor voltage Vc is fast (that is, the diagram positioned relatively on the lower side) means that the deterioration of the capacitor unit 3 is progressing accordingly. Specifically, the uppermost diagram X in FIG. 3 shows the change in the voltage Vc when the capacitor unit 3 is new (when it is not deteriorated), and the diagram below the diagram X is: The change of the voltage Vc when the deterioration of the capacitor unit 3 progresses is shown.

  If this phenomenon is used, the capacitor capacitance C can be calculated based on the measured value of the capacitor voltage Vc when a predetermined time has elapsed from the start of discharge. That is, the smaller the capacitor voltage Vc after a predetermined time, the lower the value of the capacitor capacitance C. Note that the measurement timing of the capacitor voltage Vc (predetermined time after the start of discharge) can be set as appropriate, but from the viewpoint of accurately obtaining the capacitor capacitance C, the timing at which the difference in the voltage Vc depending on the degree of deterioration is most likely to appear. For example, in the example of FIG. 3, the timing when the capacitor voltage Vc when new is about half (6 V) at the start of discharge (300 sec after the start of discharge) is suitable.

  FIG. 4 is a graph showing the relationship between the capacitor voltage Vc and the capacitor capacitance C for each elapsed time after the start of discharge. Specifically, the four diagrams in this graph indicate the relationship between the capacitor voltage Vc and the capacitor capacitance C when the elapsed time after the start of discharge is 80 sec, 120 sec, 300 sec, and 600 sec, in order from the right. . In any of the diagrams, the capacitor capacitance C is calculated to be lower as the capacitor voltage Vc after discharge is smaller. This is because the rate of decrease in the capacitor voltage Vc increases as the capacitor unit 3 deteriorates and its capacitance C decreases, as in the graph of FIG. 3 described above. Of the above four diagrams, the diagram Y representing the relationship between the voltage Vc after 300 seconds and the capacitance C has the lowest slope (that is, the difference in the voltage Vc due to the decrease in the capacitance C tends to appear). ) From this, it can be said that the timing at which the voltage Vc is measured (predetermined time after the start of discharge) is preferably a timing at which the capacitor voltage Vc at the time of a new product is about half that at the start of discharge.

  The PCM 10 stores the relationship between the voltage Vc and the capacitance C as shown in FIG. 4 in advance as map format data, and calculates the capacitor capacitance C based on the map data. For example, when calculating the capacitor capacity C based on the value of the capacitor voltage Vc 300 seconds after the start of discharging of the capacitor unit 3, the above-described capacitor capacity C is calculated using map data corresponding to the diagram Y in FIG. calculate.

  When the calculation of the capacitor capacity C is completed as described above, the PCM 10 determines whether or not the deterioration of the capacitor unit 3 has progressed more than predicted based on the capacitor capacity C (step S9). That is, the capacitance C of the capacitor unit 3 tends to gradually decrease as the usage time (years) of the capacitor unit 3 becomes longer as shown in the diagram Z of FIG. can do. The PCM 10 stores in advance a predicted deterioration value of the capacitor capacity C (a value of the capacitor capacity C predicted from the usage time of the capacitor unit 3) obtained based on the tendency of deterioration, and the step S8 is more than the predicted value. If the capacitance C calculated in (1) is small, it is determined that the capacitor unit 3 has deteriorated.

  When it is determined as YES in step S9 and it is confirmed that the capacitor unit 3 is deteriorated more than expected, the PCM 10 executes control for changing the control program of the capacitor unit 3 (step S10). That is, the capacitor unit 3 is controlled so as not to receive power supplied from the alternator 2 when the detected temperature Tc exceeds, for example, 60 ° C. in order to prevent an excessive temperature rise. When the deterioration of the unit 3 is confirmed, the control program of the capacitor unit 3 is rewritten, and the upper limit temperature (60 ° C.) is lowered to, for example, about 50 ° C. Thereby, since the temperature of the capacitor unit 3 decreases on average, the speed of the deterioration can be moderated. On the other hand, when the deterioration of the capacitor unit 3 is not confirmed, there is no need to change the control program as described above, so the upper limit temperature of the capacitor unit 3 is maintained at 60 ° C., for example.

  Next, in relation to the above-described deterioration determination of the capacitor unit 3, what value the resistance value R of the resistor 7 should be set will be described.

  As described in steps S6 to S9 in FIG. 2, when determining the deterioration of the capacitor unit 3, the charging power of the capacitor unit 3 is discharged to the ground (vehicle body) via the resistor 7, and the capacitor unit associated therewith is discharged. 3, the deterioration of the capacitor unit 3 is determined according to the degree of decrease in the voltage Vc. At this time, since the current I (FIG. 1) discharged from the capacitor unit 3 to the ground (vehicle body) varies depending on the resistance value R of the resistor 7, the discharge current I can be controlled by setting the resistance value R. it can.

  For example, when the resistance value R of the resistor 7 is increased, the discharge current I can be reduced. Then, since the rate of voltage drop of the capacitor unit 3 is slowed down, the time (measurement time) required for determining the deterioration of the capacitor unit 3 is lengthened. On the other hand, the amount of heat generated by the resistor 7 can be kept low. .

  Conversely, when the resistance value R is decreased, the discharge current I can be increased. Then, since the rate of voltage drop of the capacitor unit 3 is increased, the time required for determining the deterioration of the capacitor unit 3 (measurement time) can be shortened, while the amount of heat generated by the resistor 7 is increased.

  FIG. 6 is a graph showing simultaneously the relationship between the resistance value R (Ω) of the resistor 7 and its calorific value Q (W), and the relationship between the resistance value R and the measurement time Tm (min) required for deterioration determination. It is. The graph of FIG. 6 was calculated under the condition that the discharge was continued for the new capacitor unit 3 until the capacitor voltage Vc was reduced from 12V to 6V, which is half of that. According to the figure, the relationship as described above, that is, as the resistance value R is larger, the measurement time Tm (time until the capacitor voltage Vc is reduced to 6V) is longer, and as the resistance value R is smaller, the calorific value Q ( It can be seen that the relationship that W) becomes large appears.

  In consideration of the graph of FIG. 6, in this embodiment, the resistance value R of the resistor 7 is set in a range of 1Ω to 50Ω. When the resistance value R is 1Ω, the heating value Q of the resistor 7 is about 150 W, and the heating value of 150 W corresponds to a temperature increase of about 45 ° C. in calculation. If the ambient temperature is 25 ° C., the temperature of the resistor 7 reaches about 70 ° C. If the resistor 7 generates heat further than this, for example, it is assumed that the maintenance work is hindered. For this reason, in this embodiment, the lower limit value of the resistance value R is set to 1Ω. ing. Note that the measurement time Tm when R = 1Ω is a sufficiently short time of about 0.16 min, so there is no problem with the measurement time.

  On the other hand, when the resistance value R is 50Ω, the measurement time Tm required for the deterioration determination is 8.3 min. If the measurement time Tm is further increased to, for example, 10 minutes or more, the influence on the measurement accuracy due to changes in the environmental atmosphere, the problem of safety due to energization for a long time while the engine is stopped, and the measurement during running Due to concerns about feasibility and the like, the measurement time Tm is preferably less than 10 min. In consideration of such points, in this embodiment, the upper limit value of the resistance value R is set to 50Ω. The calorific value Q when R = 50Ω is a sufficiently small value of about 2.9 W, so there is no problem with the calorific value.

  In the graph of FIG. 6, the resistance value of the resistor 7 per capacitor cell (the value obtained by dividing the resistance value R by the number of capacitor cells 17) is shown in parentheses along the horizontal axis. That is, in the present embodiment, the capacitor unit 3 is composed of ten capacitor cells (electric double layer capacitors) 17, and therefore the value of the resistance value R (1Ω to 50Ω) is as a value per cell. 1/10, that is, 0.1Ω to 5Ω. When the number of capacitor cells 17 constituting the capacitor unit 3 is different from the example of the present embodiment, a value obtained by multiplying the resistance value per cell by the number of capacitor cells 17 is set as the resistance value R. That's fine. For example, when the number of capacitor cells 17 is five, the resistance value R is set to 0.5Ω or more and 25Ω or less.

  Here, the capacitor unit 3 includes the internal resistance 16 of each capacitor cell 17 as described above. Since the resistance value r (internal resistance value r) of the internal resistor 16 tends to increase when the capacitor unit 3 (capacitor cell 17) deteriorates, the value of the voltage Vc of the capacitor unit 3 is deteriorated by the deterioration of the capacitor unit 3. As a result, the measurement is made lower due to the influence of the voltage drop due to the increase in the internal resistance value r.

  However, when the resistance value R of the resistor 7 is set to 1Ω or more and 50Ω or less (0.1Ω or more and 5Ω or less per capacitor cell) as in this embodiment, the influence of the increase in the internal resistance value r is caused. Becomes sufficiently small, and a decrease in the capacitance C of the capacitor unit 3 can be accurately examined.

  That is, the internal resistance value r of each capacitor cell 17 constituting the capacitor unit 3 is, for example, about 1 mΩ when new, and the resistance value R of the resistor 7 described above (0.1Ω to 5Ω per capacitor cell) The resistance value R is 0.02% or more and 1% or less of the resistance value R. For this reason, for example, when the discharge of the capacitor unit 3 is started from 12 V (1.2 V per capacitor cell), the voltage drop due to the internal resistance value r (1 mΩ) remains at 0.012 to 0.00024Ω. Is only 1% or less in comparison with the voltage (1.2 V) at the start of discharge of each capacitor cell 17. Therefore, even if the internal resistance value r slightly increases from 1 mΩ due to the deterioration of the capacitor unit 3 (capacitor cell 17), the influence of the influence on the measured value of the capacitor voltage Vc is small. Under such circumstances, in this embodiment, it is possible to accurately check the degree of decrease in the capacitor capacitance C (whether or not the capacitor unit 3 has deteriorated) based on the measured value of the capacitor voltage Vc.

(3) Operational Effects As described above, in this embodiment, a capacitor having an internal resistance value r of 1 mΩ as a device (electric storage device) for intensively storing the electric power generated by the alternator 2 when the vehicle is decelerated. A capacitor unit 3 in which ten cells 17 (electric double layer capacitors) were connected in series was used. In order to determine the deterioration of the capacitor unit 3, a resistor 7 having a resistance value R set to 1Ω or more and 50Ω or less is connected in series with the capacitor unit 3, and the discharge current I from the capacitor unit 3 is used as a resistor. 7, the deterioration of the capacitor unit 3 is determined by obtaining the capacitance C of the capacitor unit 3 based on the voltage value Vc of the capacitor unit 3 after flowing for a predetermined time. According to such a configuration, there is an advantage that the deterioration of the capacitor unit 3 can be accurately determined within a range in which the amount of heat generated by the resistor 7 does not become excessive and the time required for measuring the capacitor capacitance C does not become too long. is there.

  That is, in the above embodiment, the resistance value R of the resistor 7 is set in the above range (1Ω or more and 50Ω or less), so that the resistor accompanying the passage of the discharge current I as described with reference to FIG. 7 can be suppressed to a level that does not hinder maintenance work (150W or less), and the measurement time required to obtain the capacitor capacity C is suppressed to a length that is practically acceptable (10min or less). can do. Moreover, since the resistance value R of the resistor 7 is sufficiently larger than the internal resistance value (1 mΩ × 10) of the entire capacitor unit 3, the increase in the internal resistance accompanying the deterioration of the capacitor unit 3 is the voltage of the capacitor unit 3. The influence on the value Vc can be minimized, and only the decrease in the capacitance C of the capacitor unit 3 can be accurately measured. As described above, according to the embodiment, it is possible to accurately determine the presence or absence of deterioration of the capacitor unit 3 based on the decrease in the capacitance C while considering practicality.

  In the above embodiment, since the resistor 7 is connected in parallel to the DC / DC converter 5 via the switch 8, the voltage value Vc of the capacitor unit 3 is not affected by the circuit in the DC / DC converter 5. And the deterioration of the capacitor unit 3 can be accurately determined based on the value.

(4) Other Embodiments In the above embodiment, the capacitor unit 3 is a capacitor unit 17 in which ten capacitor cells 17 (electric double layer capacitors) having an internal resistance value r of about 1 mΩ are connected in series. Although the resistance value R of the body 7 is set to 1Ω to 50Ω, the number of the capacitor cells 17 is not limited to 10 as a matter of course. Assuming that the number of capacitor cells 17 is n, the resistance value of the resistor 7 per capacitor cell (the value obtained by dividing the resistance value R by the number n of cells; R ÷ n), regardless of the number n of the capacitor cells 17. If the resistance value R of the resistor 7 is set to n × 0.1Ω or more and n × 5Ω or less, the same effect as described above can be obtained.

  Furthermore, even when the internal resistance value r when the capacitor cell 17 is new is not 1 mΩ, the ratio of the internal resistance value r when new to the resistance value (R ÷ n) of the resistor 7 per capacitor cell (r × n ÷ R), in other words, if the ratio of the internal resistance value (r × n) of the entire capacitor unit 3 to the resistance value R is set to 0.02% or more and 1% or less, the same effect as described above can be obtained. can get.

  In the above embodiment, the resistor 7 is provided outside the DC / DC converter 5 and the resistor 7 is connected in parallel with the converter 5. However, like the resistor 7 ′ shown in FIG. Inside the DC / DC converter 5, a resistor 7 ′ may be connected in parallel to a converter circuit 5a including a diode or the like via a switch 8 ′. Even in this case, the voltage value Vc of the capacitor unit 3 can be measured without being affected by the converter circuit 5a.

  Of course, when the influence of the converter circuit 5a on the measurement is very small, or when the voltage value Vc of the capacitor unit 3 is measured in consideration of the influence of the converter circuit 5a in advance, the DC / DC converter 5 May be provided with a resistor 7 'in a state of being connected in series with the converter circuit 5a.

  In the above embodiment, the resistor 7 is connected to the ground (vehicle body), so that the power charged in the capacitor unit 3 is discharged to the ground (vehicle body) when the deterioration of the capacitor unit 3 is determined. The battery 6 may be charged with the electric power discharged from the capacitor unit 3 by connecting the resistor 7 to the battery 6. In this way, there is a concern that the internal resistance of the battery 6 affects the accuracy of the deterioration determination, but it is more advantageous in terms of fuel consumption because it is not necessary to throw electric power outside. However, since the deterioration determination is performed only periodically, even in the above-described embodiment in which the charging power of the capacitor unit 3 is discarded to the outside, the influence on the fuel consumption is almost negligible.

  In the above embodiment, the capacitor unit 3 including a plurality of electric double layer capacitors (capacitor cells 17) is provided as a part of the vehicle deceleration regeneration system, and deterioration of the capacitor unit 3 is determined. The configuration of the present invention is not limited to the capacitor unit 3 including the electric double layer capacitor as described above, but can be applied to various power storage devices (batteries that can be repeatedly charged and discharged).

  Specifically, as a deterioration determination target other than the electric double layer capacitor, a hybrid capacitor such as a rechargeable ion capacitor or a high-power rechargeable ion battery is suitable regardless of whether it is for in-vehicle use.

  The electric double layer capacitor, the rechargeable ion capacitor (hybrid capacitor), and the high-power lithium ion battery, when discharged under the condition that the current is constant as shown in the diagram W1 of FIG. Discharge), and the voltage changes linearly as the discharge time elapses. 8 is different in tendency from the previous graph of FIG. 3 (the voltage drop rate becomes slower with the passage of time), but this is a natural discharge in the case of FIG. This is because the current decreases with time.

  The configuration of the present invention is suitable for determining the deterioration of an electricity storage device having a linear charge / discharge characteristic as shown by a diagram W1 in FIG. On the other hand, the lead storage battery used as the battery 6 in the above embodiment does not decrease in voltage until the discharge time has passed to some extent as shown in the diagram W2 in FIG. Has the property of decreasing. Although it is somewhat difficult to determine the deterioration of an electricity storage device having such charge / discharge characteristics, it is possible to determine deterioration by a similar method if the charge / discharge characteristics are examined in advance.

2 Alternator 3 Capacitor unit (electric storage device)
5 DC / DC converter 5a converter circuit 8 switch 7 resistor 10 PCM (determination unit)
R (resistance) resistance value r internal resistance value

Claims (9)

A capacitor connected in series with the power storage device; and determining the capacity of the power storage device based on a voltage value of the power storage device after flowing a discharge current from the power storage device through the resistor for a predetermined time. A deterioration determination device including a determination unit for determining deterioration of
An electrical storage device deterioration determination apparatus, wherein a ratio of an internal resistance value of the electrical storage device when new to the resistance value of the resistor is set to 0.02% or more and 1% or less. The deterioration determination apparatus for an electricity storage device according to claim 1,
The power storage device deterioration determining apparatus, wherein the power storage device is a power storage device having charge / discharge characteristics such that a voltage value under a constant current changes linearly with time. The deterioration determination apparatus for an electricity storage device according to claim 2,
The power storage device deterioration determining apparatus, wherein the power storage device includes at least one of an electric double layer capacitor, a rechargeable ion capacitor, or a high-power lithium ion battery. In the storage device deterioration determination device according to claim 3,
Deterioration determination of an electricity storage device, wherein the electricity storage device includes one or more electric double layer capacitors, and a resistance value of the resistor per electric double layer capacitor is set to 0.1Ω to 5Ω. apparatus. An alternator driven by an engine, a DC / DC converter interposed between the alternator and an electric load, and an electricity storage device connected in series with the alternator so as to store electric power generated by the alternator. The vehicle is configured to recover the energy at the time of deceleration as regenerative power by storing the electric power generated by the alternator at the time of deceleration of the vehicle in the power storage device,
A vehicle comprising the deterioration determination device according to any one of claims 1 to 4 as a device for determining deterioration of the power storage device. The vehicle according to claim 5, wherein
A vehicle in which the resistor is connected in parallel to the DC / DC converter via a switch. The vehicle according to claim 5, wherein
A vehicle in which the resistor is connected in parallel through a converter circuit and a switch inside the DC / DC converter. The vehicle according to claim 5, wherein
A vehicle characterized in that the resistor is connected in series with a converter circuit inside the DC / DC converter. The vehicle according to any one of claims 5 to 8,
A vehicle characterized in that the electricity storage device comprises 10 electric double layer capacitors connected in series, and the resistance value of the resistor is set to 1Ω to 50Ω.

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