JP6160650B2 - Electric double-layer capacitor control device - Google Patents

Description

  The present invention relates to a control device for an electric double layer capacitor.

  In some vehicles, regenerative energy during deceleration is recovered by charging an electric double-layer capacitor. The electric power stored in the capacitor is used as appropriate for power supply to the electric load when the vehicle is stopped, for example.

  The maximum amount of electricity stored in the capacitor is reduced by aging (aging deterioration). Further, when the capacitor is charged so as to exceed its maximum charged amount, the capacitor rapidly deteriorates. For this reason, when charging the capacitor, it is necessary to take into account the decrease in the maximum amount of electricity stored due to secular change so as not to exceed the current maximum amount of electricity stored. Patent Document 1 discloses changing the target voltage at the time of charging in accordance with the degree of deterioration due to aging of the capacitor.

JP 2014-46737 A

  The degree of deterioration of the capacitor due to aging described above is relatively small. On the other hand, there is an initial deterioration as a deterioration of a capacitor. In other words, from the initial start of capacitor use until the elapse of a predetermined period of time when the initial deterioration converges, even if it is in the same use state, it is more than the deterioration due to the generally known secular change. The degree of deterioration is considerably large.

  There are individual differences in initial deterioration of a capacitor. When the maximum storage amount is shown as 100%, for example, one capacitor causes 3% initial deterioration, and another capacitor causes 7% initial deterioration. It makes a difference. For this reason, conventionally, the largest stored amount after initial deterioration, which is the largest among individual differences, is used as an initial value (for example, the maximum stored amount after 7% deterioration is used as an initial value), and subsequent aging deterioration is detected (estimated). It was like that. For this reason, the actual situation is that some capacitors do not perform charging (power storage) sufficiently utilizing the actual maximum power storage amount.

  In addition, it is thought that the said initial stage deterioration has influenced the water | moisture content in the electrolyte solution of a capacitor. That is, it is considered that in addition to the organic matter in the electrolytic solution, a reactant caused by moisture is deposited on the electrode surface, and the maximum amount of electricity stored is reduced accordingly. Then, after a lapse of a predetermined period when the reaction due to moisture ends, it is considered that a reaction product caused by the organic matter in the electrolyte volume on the electrode surface and causes a conventionally known aging deterioration. .

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for an electric two-layer capacitor capable of accurately estimating the degree of deterioration of the capacitor including the initial deterioration. There is to do.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
A control device for an electric double-layer capacitor that estimates the degree of deterioration in which the maximum storage capacity of the electric double-layer capacitor decreases,
In the period from the initial use start time set in advance as the initial deterioration period until the initial deterioration converges until the predetermined period elapses, the capacitor deterioration degree is estimated based on the first model expression indicating the initial deterioration characteristics . 1 degradation degree estimating means,
A second deterioration degree estimating means for estimating a deterioration degree of the capacitor based on a second model expression indicating the aging deterioration characteristics after the predetermined period has elapsed;
It is supposed to be equipped with.

  According to the above solution, initial deterioration and subsequent deterioration due to secular change can be accurately estimated by model equations. As a result, the current maximum power storage amount is accurately estimated, which is preferable for sufficiently charging the capacitor within a range not exceeding the maximum power storage amount.

  Each of the first model formula and the second model formula is set with the temperature, voltage, and usage time of the capacitor as parameters (corresponding to claim 2). In this case, specific parameters are provided as the parameters used in the model formula, and the parameters used in particular can be made simple and easily available from the conventional sensor. Although it is conceivable to estimate the degree of deterioration by the work amount of the capacitor, in this case, since the measured current is integrated, the integration error becomes large and the degree of deterioration is accurately estimated. It is inferior.

The first model formula and the second model formula are set as the same formula using a predetermined constant, but only the value of the predetermined constant is different,
When the predetermined constant in the first model expression and the predetermined constant in the second model expression use the first model expression, the estimated value of the degree of deterioration uses the second model expression. It is set to be larger than the estimated value of the degree of deterioration in the case,
(Corresponding to claim 3). In this case, the two model formulas are the same except that only their constants are different, which is preferable in terms of simplification of calculation for estimation.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 4,
A control device for an electric double-layer capacitor that estimates the degree of deterioration in which the maximum storage capacity of the electric double-layer capacitor decreases,
First deterioration degree estimation means for estimating the deterioration degree of the capacitor based on the first model equation in a period from the initial point of use to the elapse of a predetermined period set in advance;
A second deterioration degree estimating means for estimating the deterioration degree of the capacitor based on the second model formula after the predetermined period has elapsed;
With
Each of the first model formula and the second model formula is set with the capacitor temperature, voltage, and usage time as parameters,
The first model formula and the second model formula are set as the same formula using a predetermined constant, but only the value of the predetermined constant is different,
When the predetermined constant in the first model expression and the predetermined constant in the second model expression use the first model expression, the estimated value of the degree of deterioration uses the second model expression. Is set to be greater than the estimated degradation level
The degree of deterioration is calculated by a formula of k × t ^1/2 (k = deterioration coefficient, t = capacitor usage time),
In the first model equation, the deterioration coefficient k is set as the following equation (2):

  In the second model equation, the deterioration coefficient k is set as the following equation (3).

It is like that . This provides a concrete one for each model formula.

  The capacitor is mounted on a vehicle and is charged by regenerative energy when the vehicle is decelerated (corresponding to claim 5). In this case, it is preferable to recover the regenerative energy more sufficiently as power storage in the capacitor.

  According to the present invention, the degree of deterioration of a capacitor can be accurately estimated including initial deterioration.

The figure which shows the circuit example in the case of utilizing a capacitor for collection | recovery of the regenerative energy at the time of deceleration of a motor vehicle. The characteristic view which shows the mode of initial stage deterioration and subsequent aging deterioration. The flowchart which shows the example of control of this invention.

  FIG. 1 shows a deceleration regeneration system 1 using a capacitor. The deceleration regeneration system 1 includes a regenerative alternator 10, a battery 20, and a capacitor that stores electric power generated by the regenerative alternator 10 capable of decelerating regenerative power generation performed when the vehicle is decelerated and normal power generation driven by an engine (not shown). 30, a DC / DC converter 40 for controlling power feeding to various electric devices 60 mounted on the vehicle, a control unit 50 for controlling the deceleration regeneration system 1 (hereinafter referred to as “ECU 50”), and bypassing the DC / DC converter 40 A bypass relay 70 is provided in the bypass circuit section 75 that performs the above operation.

  The regenerative alternator 10 and the DC / DC converter 40 are connected by a first circuit unit 15, and a capacitor 30 is connected to the first circuit unit 15. The DC / DC converter 40 and the electrical device 60 are connected by a second circuit unit 65, and the battery 20 is connected to the second circuit unit 65.

  Furthermore, a bypass relay 70 that short-circuits or opens the first circuit unit 15 and the second circuit unit 65 is connected so as to bypass the DC / DC converter 40.

  The regenerative alternator 10 is a variable voltage type alternator that is belt driven by the engine and efficiently regenerates kinetic energy during deceleration, etc., and can be increased to a maximum voltage of 25 V for efficient power transmission and storage. It is. The battery 20 is a general lead battery.

  The capacitor 30 is a large-capacity low-resistance electric double layer capacitor (EDLC) that can instantly store a large amount of regenerated electric energy and efficiently extract and use it, and can generate a voltage of up to 25V. The capacitor 30 is capable of rapid power storage (several seconds when traveling at 50 to 60 km / h) and has an unlimited depth of discharge when compared with a lithium ion battery or a general lead battery used in an electric vehicle or the like. It has advantages such as having a semi-permanent lifetime.

  The DC / DC converter 40 is a converter that steps down and outputs a maximum DC 25 V to DC 14 V, and can flow up to a predetermined capacity (for example, an allowable output current value (allowable limit value) is 50 A). In general, DC / DC converters increase in size and become more expensive as capacity increases.

  The ECU 50 manages and controls the operation of the entire deceleration regeneration system 1.

  Examples of the electric device 60 include a lamp, a defroster, a blower, a seat heater, a fan, an ignition, an engine control unit, a DSC (dynamic stability control), an EPAS (electric power steering), and a power window.

  According to the deceleration regeneration system 1, even when idling is stopped or the accelerator is ON, the electricity stored in the regenerative alternator 10 is not generated while sufficient electricity remains in the battery 20 or the capacitor 30, without generating electricity. By using it, fuel generation is improved because power generation by an engine using fuel is suppressed.

  In addition, since acceleration / deceleration is frequently performed during city driving, the electric power stored in the capacitor 30 is stored again by deceleration before the electric power stored in the capacitor 30 is completely depleted, and the electric power necessary for the traveling vehicle is almost allotted to the decelerating regenerative energy.

  Next, the deterioration degree of the capacitor 30 will be described. In order to detect (estimate) the degree of deterioration, the ECU 50 receives signals from a temperature sensor S1 that detects the temperature of the capacitor 30 and a voltage sensor S2 that detects the voltage of the capacitor 30. Note that the usage time of the capacitor 30 is used for detecting the degree of deterioration, and this is constantly grasped (monitored) by the ECU 50 as the engine driving time (time when the ignition switch is turned on). It is.

  FIG. 2 shows a state in which the maximum charged amount changes due to the deterioration of the capacitor 30. The degree of deterioration is indicated by the degree (%) of reduction in the amount of stored electricity when the maximum amount of stored electricity at the time of shipment of the capacitor 30 is shown as 100%.

  As indicated by characteristic lines α1 to α3, the deterioration of the capacitor 30 is assumed to have a large degree of deterioration until a predetermined time (for example, 300 hours in a predetermined period) when the initial deterioration converges. After the initial deterioration, it is assumed that the deterioration degree is small. The characteristic line α1 is a deterioration characteristic when, for example, city driving is frequently used. The characteristic line α2 is a deterioration characteristic when there is much traffic traveling. A characteristic line α3 is a deterioration characteristic when used in an extremely hot region. In this way, even with the same capacitor, the deterioration characteristics are changed according to the use situation.

  Here, the capacitor 30 has a deterioration characteristic such as the characteristic line α1 or a deterioration characteristic such as the characteristic line α3 even though the capacitor 30 is in the same usage state due to individual differences. Conventionally, the characteristic of initial deterioration has not been taken into account, and for this reason, assuming that the largest degree of deterioration is shown among individual differences, subsequent aging deterioration is detected (estimated). That is, for example, the subsequent aging deterioration is estimated by using the maximum storage amount CB after the initial deterioration of the characteristic line α3 as an initial value.

However, for example, in a capacitor that has been deteriorated such as characteristic line α2 having a smaller initial deterioration than characteristic line α3, the maximum charged amount after the initial deterioration is larger than CB, and the amount of deviation further increases It is a possible margin. Similarly, in the case of a capacitor that has been deteriorated as indicated by the characteristic line α1 , the maximum charged amount after the initial deterioration is much larger than the above CB, and it is a margin that can be charged further by the deviation.

  In the present invention, initial deterioration and subsequent aging deterioration are estimated more accurately. As a result, the current maximum amount of electricity stored in the capacitor 30 can be fully utilized (allowing to use up the margin allowance shown in FIG. 2).

Next, model equations for estimating initial deterioration and aging deterioration will be described. First, the maximum charged amount of the capacitor 30 is expressed by the following equation (1) when the shipping time is shown as 100%, of which k × t ^1/2 represents the degree of deterioration.

  The deterioration coefficient k in the above equation (1) is expressed by the following equation (2) for the initial deterioration and is expressed by the following equation (3) for the aging deterioration.

  Expressions (2) and (3) are expressed by the product of Butler-Volmer law (voltage dependence) and Arrhenius law (temperature dependence). Expressions (2) and (3) are the same except that constants C, D, E, and F are different from C ′, D ′, E ′, and F ′. Of course, the relationship between the constants C, D, E, and F and C ′, D ′, E ′, and F ′ is the same as that of the calculated value in equation (2) under the same use conditions. It is set to be larger than the calculated value in 3).

  As described above, by calculating the initial deterioration by the equation (2) which is a model equation, the maximum charged amount of the capacitor 30 at the time t1 when the predetermined time has elapsed in FIG. 2 can be accurately calculated. Then, the subsequent aging deterioration is calculated with high accuracy based on the equation (3) which is a model equation. Thereby, the maximum power storage amount estimated at the present time can be made more accurate. That is, it is possible to obtain the maximum power storage amount estimated at the present time as a sum of the allowance shown in FIG. This makes it possible to recover regenerative energy that fully utilizes the maximum amount of electricity stored in the capacitor.

  Next, a control example for estimating the degree of deterioration of the capacitor 30 by the ECU 50 will be described with reference to FIG. In the following description, Q indicates a step.

  First, in Q1, the capacitor temperature T, the voltage V, and the usage time (integrated value) t so far are read. Thereafter, in Q2, it is determined whether or not the read usage time t is equal to or longer than a predetermined time t1 at which the initial deterioration ends.

  If NO in the determination of Q2, the initial deterioration is being performed. At this time, in Q3, the degradation coefficient k is calculated based on the equation (2). Thereafter, in Q4, the deterioration coefficient k calculated in Q3 and the usage time t read in Q1 are applied to Equation (1) to calculate the current maximum charged amount.

  On the other hand, if YES in Q2, the constants C, D, E, and F are changed to constants C ′, D ′, E ′, and F ′ for aging in Q5 to calculate the degree of deterioration due to aging. Replaced. Thereafter, the process shifts to Q3. The calculation by the expression (2) in Q3 is a calculation using constants C ′, D ′, E ′, and F ′ for aging deterioration. Note that the initial value (being the maximum charged amount) when calculating the degree of deterioration due to aging is the final calculated value (maximum charged amount at time t1) for the initial deterioration.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. The present invention can also be expressed as a method invention (an invention for estimating the degree of deterioration). Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention is suitable when a capacitor is used for recovering regenerative energy.

1: Deceleration regeneration system 10: Alternator 30: Capacitor 50: ECU
60: Electric device (electric load)
S1: Temperature sensor S2: Voltage sensor

Claims (5)

A control device for an electric double-layer capacitor that estimates the degree of deterioration in which the maximum storage capacity of the electric double-layer capacitor decreases,
In the period from the initial use start time set in advance as the initial deterioration period until the initial deterioration converges until the predetermined period elapses, the capacitor deterioration degree is estimated based on the first model expression indicating the initial deterioration characteristics . 1 degradation degree estimating means,
A second deterioration degree estimating means for estimating a deterioration degree of the capacitor based on a second model expression indicating the aging deterioration characteristics after the predetermined period has elapsed;
A control device for an electric double-layer capacitor, comprising: In claim 1,
The control device for an electric double-layer capacitor, wherein the first model formula and the second model formula are set with the temperature, voltage and usage time of the capacitor as parameters, respectively. In claim 2,
The first model formula and the second model formula are set as the same formula using a predetermined constant, but only the value of the predetermined constant is different,
When the predetermined constant in the first model expression and the predetermined constant in the second model expression use the first model expression, the estimated value of the degree of deterioration uses the second model expression. It is set to be larger than the estimated value of the degree of deterioration in the case,
A control device for an electric double-layered capacitor. A control device for an electric double-layer capacitor that estimates the degree of deterioration in which the maximum storage capacity of the electric double-layer capacitor decreases,
First deterioration degree estimation means for estimating the deterioration degree of the capacitor based on the first model equation in a period from the initial point of use to the elapse of a predetermined period set in advance;
A second deterioration degree estimating means for estimating the deterioration degree of the capacitor based on the second model formula after the predetermined period has elapsed;
With
Each of the first model formula and the second model formula is set with the capacitor temperature, voltage, and usage time as parameters,
The first model formula and the second model formula are set as the same formula using a predetermined constant, but only the value of the predetermined constant is different,
When the predetermined constant in the first model expression and the predetermined constant in the second model expression use the first model expression, the estimated value of the degree of deterioration uses the second model expression. Is set to be greater than the estimated degradation level
The degree of deterioration is calculated by a formula of k × t ^1/2 (k = deterioration coefficient, t = capacitor usage time),
In the first model equation, the deterioration coefficient k is set as the following equation (2):

In the second model equation, the deterioration coefficient k is set as the following equation (3).

A control device for an electric double-layered capacitor. In any one of Claims 1 thru | or 4,
A control device for an electric two-layer capacitor, wherein the capacitor is mounted on a vehicle and is charged by regenerative energy when the vehicle is decelerated.

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