JP3272874B2 - Battery capacity / remaining time display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for estimating a remaining capacity and a remaining discharge time of a storage battery in a DC power supply system comprising a rectifier and a storage battery for supplying power to a load, and displaying the values. .

[0002]

2. Description of the Related Art FIG. 7 shows a DC power supply system which comprises a rectifier and a stationary storage battery and supplies power to a load. A charge / discharge current I of a storage battery 2 is detected by a shunt 4 and is an output of the rectifier 1. the current I _0, is obtained by finding the difference between the current I _L in the load 3 that is detected by the shunt 5. The remaining capacity of the storage battery 2 can be known by measuring and calculating the two shunt currents by the capacity / remaining time display device 6 for each unit time. FIG. 8 shows a circuit example of a conventional capacity / remaining time display device 6 (hereinafter abbreviated as a display device). 8, the input / output means 7 is a circuit for inputting a power failure signal or a failure signal from the rectifier 1 and a circuit for outputting a uniform charging signal or an alarm signal to the display device 6. The measuring means 8 reads the detection signals from the shunts 4 and 5 with an A / D converter, and calculates and calculates the difference by the calculating means 9 to obtain the remaining capacity. Further, when detecting the power failure signal by input means 7, by dividing the remaining capacity by the load current I _L to be detected from the shunt 5, it is possible to obtain the discharge remaining time at that point. The remaining capacity and the remaining discharge time are displayed by display means 10 such as an LCD or LED.

[0003]

However, the amount of discharge per unit time measured by the measuring means 8 shown in FIG. 2 and obtained by the calculating means 9 depends only on the magnitude of the battery discharge current. That is, in an actual DC power supply system,
Depending on the magnitude of the voltage drop between the storage battery 2 and the load 3 shown in FIG.
It may not be possible to discharge. Further, it is known that the discharge characteristics of a storage battery vary significantly depending on the discharge rate, and the discharge characteristics also have a large temperature dependence. Therefore, the method using only the magnitude of the discharge current has a problem that the error is large and the backup operation in an emergency is greatly affected.
The present invention is intended to solve these problems and improve the accuracy of estimating the remaining capacity and remaining discharge time of a storage battery.

[0004]

The present invention relates to a display device of a DC power supply system for supplying power from a rectifier and a storage battery to a load, and an input / output means for inputting and outputting signals to and from the rectifier. And a first measuring means for measuring an output current and a load current of the rectifier, and a calculating means for calculating a storage battery current from a difference between the output current and the load current calculated by the first measured output.・ In the remaining time display device,
A second measuring means for measuring a case temperature of the storage battery; a type, a rated capacity, and a minimum allowable power of the rectifier and the storage battery;
First storage means for storing the table data gathered specification setting items and the setting value of the pressure, the storage of the said first memory means
Condition setting means that can be selected from the above specification setting items and set according to actual operating conditions, and prepared for each storage battery type
The minimum allowable voltage of the storage battery and the case temperature are set as parameters.
Using a capacity conversion time (K) and a discharge time (T) characteristics defined in a predetermined standard of the storage battery, a discharge current (C-Rat) when the storage battery whose rated capacity is known is discharged.
e) a second storage means for obtaining a discharge coefficient for table data and storing the same as table data, and a discharge corresponding to the discharge current of the storage battery and the case temperature measured by the first measurement means and the second measurement means for each fixed unit time. A coefficient is obtained by the second storage means, and the discharge coefficient is multiplied by the discharge current and a unit time to calculate a discharge amount converted to a predetermined time rate discharge,
The remaining capacity is obtained by sequentially subtracting the discharge amount from the storage battery capacity with a full charge as an initial value, calculating a percentage with respect to a full charge, and dividing the remaining capacity by the discharge coefficient and the discharge current at that time. Calculating means for estimating the remaining discharge time under the condition; and the specification set by the condition setting means.
Display means for updating and displaying the calculation results obtained by the calculation means in correspondence with the various setting items for each unit time of measurement.

[0005]

FIG. 1 shows an embodiment in which a display device 60 according to the present invention is used in the DC power supply system shown in FIG. 7, in which a temperature sensor 11 detects the case temperature of a storage battery. FIG. 2 shows a circuit configuration of the device 60 according to the present invention. The block diagram of the conventional display device 6 shown in FIG.
4. Addition of the second storage means 15 and the communication interface circuit 16 to improve the accuracy of estimating the remaining capacity and remaining discharge time at the time of discharge, and to enable the display device 60 to be mounted on a rectifier having a different rating for general use. It is intended for. Note that the measuring means 8 shown in FIG. 8 is described as a first measuring means 8 in FIG. 2 to distinguish it from the second measuring means 12. Hereinafter, each function of FIG. 2 will be described.

The second measuring means 12 amplifies the detection signal of the temperature sensor 11 if it is a voltage signal, and converts it to a voltage signal if it is an impedance signal. Monitor the temperature of the charge / discharge state. The condition setting means 13 sets the rated value of the shunts 4 and 5 operated in the system shown in FIG. 1, the type of the storage battery, the rated capacity, and the allowable minimum voltage, and also reduces the remaining capacity of the storage battery, thereby reducing the alarm output operation. This is a circuit section for setting an alarm level to be performed. Since these set values are set according to the situation at the site, they are highly versatile and can be applied to an extremely wide range.

For example, the rated current value of the shunt 4 shown in FIG. 1 is determined by adding the discharge current of the storage battery 2 and the current to the load 3 together with the rated capacity of the rectifier 1, and the rated value of the shunt 5 is the load current. Is determined by the size of Therefore, the rated capacity of the storage battery is determined by the time during which the maximum load current detected by the shunt 5 is maintained during a power failure. It is extremely effective to provide the condition setting means 13 which can be set by a key switch, a display, and the like in accordance with the setting conditions of the system which is diversified in this way, and to easily perform initial setting at the time of operation. Then, as shown in FIG. 2, in accordance with the set value, the value read by the first measuring means 8 is converted by the calculating means 9 to become an actually measured value. The first storage means 14 is a setting data table such as a value of a selectable range or a rating display for each setting item of the condition setting means 13 and is normally stored in the ROM. After being selected and set by the condition setting means 13, the nonvolatile RA
It is written and held in M etc.

The second storage means 15 is prepared for each storage battery type, and is a data table showing a relationship between a discharge current (C-Rate) with respect to a rated capacity and a discharge coefficient α by using the allowable minimum voltage and the case temperature of the storage battery as parameters. is there. This data table corresponds to the discharge current (C-Rat) shown in FIG.
e) and a table obtained by subdividing the discharge coefficient characteristics.
The minimum allowable voltage and the case temperature of the storage battery are usually stored in the ROM as parameters. The discharge coefficient α in FIG. 3 is a known rated capacity (usually 10 at 25 ° C.) set by the discharge current measured by the shunt 5 and the first measuring means 8.
It is a discharge coefficient indicating the severity of the discharge condition with respect to the discharge rate (time rate discharge capacity). This characteristic is consistent with the tendency indicated by the discharge characteristic curve of the storage battery.

Next, a description will be given of a method of calculating the characteristics shown in FIG. 3, which is an important basis for estimating the remaining capacity according to the present invention. The characteristics shown in FIG.
01 is an example of a standard characteristic diagram of the capacity conversion time K and the discharge time T of the “method of calculating the capacity of the stationary storage battery”, which is usually called a KT curve, which is prepared for each type of storage battery and storage battery temperature. The required rated capacity (10 HR) can be easily obtained by multiplying the K value corresponding to the discharge time to be performed by the discharge current, and is commonly used. FIG. 3 is a drawing using the KT standard characteristics shown in FIG. 4 as follows.

When the storage battery capacity is determined and a constant discharge current is applied, the discharge time T of 10 on the horizontal axis shown in FIG.
H is expressed as a discharge current 0.1 C corresponding to a 10-hour rate discharge (10 HR), and a value obtained by dividing the capacity conversion time K (about 10 H) on the vertical axis in FIG. FIG. 3 shows a graph obtained as a coefficient α and similarly obtained for other discharge times. The standard SBA
In 6001, when the discharge current changes to CI, CII, and CIII as shown in the discharge pattern of FIG. 5, the storage battery capacity C required for the entire discharge is given by equation (1).

[0011]

[Number 1] C = CI + CII + CIII = K 1 I 1 + K 2 (I 2 -I 1) + K 3 (I 3 -I 2) (1)

That is, for the change pattern of the discharge currents I ₁ , I ₂ , I ₃ , the storage battery capacity is directly related to the magnitude of the discharge current only in the first term I ₁ , and the second term and the second term The third term relates to the difference between (I ₂ −I ₁ ) and (I ₃ −I ₂ ). Therefore, although the required capacity cannot be determined unless the change in the discharge pattern is known, it is generally determined on the assumption that the magnitude of the discharge current at that time is constant in consideration of the worst conditions in the use of the storage battery. Also, using the equation (1), the discharge amount of Determination of when to discharge the known volume, the discharge time T ₁ of the initial values shown in the discharge pattern of Figure 5 is unknown, the discharge current by adding the time for each cycle time of measuring change the discharge time T _1, further re-calculated from that time to meet changing discharge current select capacitance conversion time K value (1) the first term of The thing that will be repeated
This method is computationally complex and impractical. Therefore, the discharge current shown in FIG. 3 is converted into a C-Rate to obtain a corresponding discharge coefficient α, and the discharge current I is multiplied by a unit time Δt as a cycle time of measurement to convert it into a 10-hour rate (10 HR). The discharge amount per hour (α × I × Δt) is obtained. The rated initial capacity C ₁₀ obtained by converting this discharge amount to 10 HR
By sequentially subtracting and repeating this from (t ₀ ),
The storage battery remaining capacity C ₁₀ (t _n ) converted to ₁₀ HR at an arbitrary discharge time t _n can be obtained by the equation (2).

[0013]

(Equation 2)

Here, α _i is an arbitrary discharge coefficient from time t ₀ to t _n , and is determined by the measured values of the discharge current I _i , the temperature of the storage battery, and the set allowable minimum voltage. Value. Further, the data table stored in the second storage means 15, suitably subdivided to Figure 3 as described above, there is a summary for each battery type and temperature, any discharge coefficient alpha _i is the data・ There are few opportunities to be obtained directly from the table, and it is usually located in the middle of the table. In such a case, the discharge current I
_{As i,} a value converted into a C-Rate, a data value before and after relating to a permissible minimum voltage and a temperature are selected, and a linear approximation calculation connecting these points is performed by the calculating means 9 to obtain an optimum discharge coefficient α _i. Is required. Therefore, the remaining capacity C ₁₀ (t
_n ) can be said to be sufficiently high in accuracy.

The remaining capacity (%) of C ₁₀ (t _n ) with respect to full charge is expressed by equation (3).

Equation 3] remaining capacity _{(%) = C 10 (t} n) / C 10 (t 0) (3) then discharging the remaining time at an arbitrary time t _n t _d, first (4) by the discharge current I _In order to return to the remaining capacity C _x (t _n ) under the condition of _n , the capacity obtained by the equation (2) is divided by α _n .

Equation 4] _{C x (t n) = C} 10 (t n) / α n (4) now to divide the discharge current I _n, the discharge current I _n the time t
_The remaining discharge time t _d when it is assumed that the discharge has continued after _n can be obtained by equation (5).

T _d = C _x (t _n ) / I _n (5) On the other hand, _assuming that the power failure has recovered at the time t _n, the remaining capacity C ₁₀ (at the time t _{n + 1} after the unit time Δt has elapsed) t
The change of ( _{n + 1} ) is added by multiplying the charging current In _{+ 1} by the unit time Δt as shown in the equation (6).

C ₁₀ (t _{n + 1} ) = C ₁₀ (t _n ) + I _{n + 1} × Δt (6)

The arithmetic processing in charging and discharging the storage battery is performed by the arithmetic means 9 shown in FIG. Since the difference due to the calculation method of charging and discharging appears as a difference in the remaining capacity, in charging at the time of recovery from power failure, the charging current is reduced to a certain value, for example, 0.01 C or less, and then the charging timer is started. Even if the remaining capacity is 100
%, It is possible to correct the calculation error by considering it as 100% of full charge, and these corrections are also performed by the arithmetic means 9. The remaining capacity and remaining discharge time obtained as described above are updated and displayed for each cycle time Δt by the display means 10 such as an LED, a liquid crystal, and an EL.

If the display means 10 uses a dot pitch display means having a sufficient resolution to show the change of the remaining capacity / discharge remaining time, the locus of the discharge state as shown in FIG. ) And estimation (indicated by a dashed line) can be illustrated by a command from the calculating means 9. The outline shown in FIG. 6 will be described below. Power failure detection time t
After ₀ , the unit time Δt as the first measurement cycle time
In the above, the calculation from the equations (2) to (5) is performed for the discharge current I ₁ , and the point B where the remaining discharge time t _d = t ₄ can be obtained. Since the discharge current I ₁ is constant up to time t _1, the point C is the intersection of the straight line and the time t ₁ connecting point A and point B locus of remaining capacity and discharge time along a straight line between AC reduction I do. At time t ₁ , the locus when the battery current increases to I ₂ is as follows.

[0018] At the discharge current I ₁ at time t ₀ in the same manner as it was determined point B, also obtaining a discharge time t ₂ becomes point D for the discharge current I ₂ is determined. Point A, moves parallel to the point C at time t ₁ is the change point of the discharge current I ₂ without changing the straight inclination at this time (t ₄ / t ₂₎ connecting the D, the elapsed time on the horizontal axis Is a new estimated value of the remaining discharge time at the time t _{1, and the} time E from the previous estimated time t ₄ to the time t
Changes to ₃ and becomes shorter. Since the discharge current I ₂ is constant at an arbitrary time t _x , the remaining capacity C ₁₀ (t _x ) is obtained at a point F on a straight line connecting the points C and E. On the other hand, at time t ₃ is a limit value of the E point when discharge remaining time is assumed to future discharge current flows I _2, since the course of this point as time does not depend on the magnitude of the discharge current, the straight line G points are determined at time t ₁ when translated CB.

That is, at time t ₁ , the remaining discharge time is (t
₄ -t rapidly decreased from ₁₎ to (t ₃ -t _1), then until the time t _x represents the trajectory decreases linearly.
Further, a change in remaining capacity estimated thereafter is indicated by a chain line connecting points F and E, and a change in remaining discharge time is indicated by a chain line connecting points H and E. If both can be obtained similarly by changing the discharge current is generated for after time t _x, it is useful as a man-machine interface having a means for displaying and plotting them.

As a practical example, a sudden change in the remaining time at the time t ₁ changes in accordance with a change in the load current, so that it is intuitive and easy to understand. In the case of a small value that does not reach the time, a method of sequentially cutting off loads of lower priority levels according to the importance of the load is performed. The remaining discharge time increases with the release of the load, and it is easy to determine whether the current state is good or whether the load needs to be released. Further, it is easy to estimate when the remaining capacity reaches the alarm level set by the condition setting means 13.

As described above, the method of obtaining the remaining capacity according to the present invention is based on the method (1) of the capacity calculation method based on the standard SBA6001.
Although not based on the formula, it is effective as an approximate method, and has extremely improved accuracy as compared with the conventional calculation method using the product of current and time. As described above, the actual storage battery capacity is determined by the holding time assuming that the worst value of the maximum discharge current is constant because the discharge pattern is not generally known. It is not appropriate to discuss the present invention, and the present invention is a relatively simple calculation and incorporates the concept based on the standard SBA6001, so that it is highly accurate and practical.

[0022]

As described above, the present invention provides a means for registering and maintaining the condition of the rectifier even if the rating of the rectifier is different or the storage battery type or the rating is different so that it can be applied to a standard DC power supply system. Is done. In addition, the measured values of the two currents by the shunts 4 and 5 are converted at a ratio determined with respect to the set value, and the correction relating to the type of the storage battery, the allowable minimum voltage, the discharge rate, and the temperature is performed by the calculating means 9. The accuracy for the indication of the remaining capacity and the remaining time is extremely high. If a high-performance display unit is used, the above-described trajectory and predicted value can be illustrated. Further, by providing a communication interface circuit as necessary, it is possible to transmit such information to a host computer for monitoring. Therefore, in recent years, the function of monitoring the capacity of the storage battery is often required of the rectifier. Therefore, it is extremely useful to mount the versatile display device of the present invention in the DC power supply system.

[Brief description of the drawings]

FIG. 1 is a block diagram of a DC power supply system according to the present invention.

FIG. 2 is a block diagram of an embodiment of a capacity / remaining time display device of the present invention.

FIG. 3 is a characteristic curve diagram of a discharge current (C-Rate) for estimating a remaining capacity and a discharge coefficient in the present invention.

FIG. 4 is a characteristic curve diagram of a capacity conversion time K and a discharge time T based on a predetermined standard of a storage battery.

FIG. 5 is a discharge pattern diagram based on a predetermined standard of a storage battery.

FIG. 6 is a display example diagram in which an example of a calculation result in the present invention is displayed on a display unit.

FIG. 7 is a block diagram of a conventional DC power supply system.

FIG. 8 is a block diagram of a conventional capacity / remaining time display device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rectifier 2 storage battery 3 load 4,5 shunt 6,60 display 7 input / output means 8 first measurement means 9 calculation means 10 display means 11 temperature sensor 12 second measurement means 13 condition setting means 14 first storage means 15 2 storage means 16 communication interface circuit

Claims (3)

(57) [Claims] 1. A display device of a DC power supply system for supplying power from a rectifier and a storage battery to a load, comprising: an input / output means for inputting and outputting a signal between the rectifier and an output current of the rectifier. And first measuring means for measuring the load current,
A storage battery capacity / remaining time display device including a calculation unit for calculating a storage battery current from a difference between an output current calculated by the first measurement output and a load current, wherein a second measurement unit for measuring a case temperature of the storage battery; The type, rated capacity and allowable minimum of the rectifier and storage battery
First storage means for storing voltage specification setting items and table data in which the setting values are collected; and selecting from the specification setting items stored in the first storage means , the setting items can be set according to actual operating conditions. Condition setting means and the minimum allowable voltage of the storage battery,
Using the storage temperature as a parameter, and utilizing the capacity conversion time (K) and discharge time (T) characteristics defined in the predetermined standard of the storage battery, the discharge current (C− a second storage means for storing a table data seeking discharge coefficient for Rate), corresponding to the discharge current and the case temperature of the first measuring means and the storage battery measured more every predetermined unit time to the second measuring means calculated discharge coefficients by said second storage means, to calculate a discharge amount in terms of a predetermined time-rate discharging by multiplying the discharge current and the unit time the discharge coefficient <br/>, the initial value of the full charge The remaining capacity is obtained by sequentially subtracting the discharge amount from the storage battery capacity,
Calculating means for calculating a percentage of a full charge, dividing the remaining capacity by the discharge coefficient and the discharge current at that time, and estimating a remaining discharge time under operating conditions; and setting the specifications set by the condition setting means. Item
Display means for updating and displaying the operation result obtained by the operation means for each unit time of measurement in response to the request . 2. The storage battery according to claim 1, wherein said display means is a display means capable of updating and displaying a calculation result by said calculation means for each unit time of measurement and displaying the calculation result as a locus. Capacity / remaining time display device. 3. The capacity / remaining time of a storage battery according to claim 1, further comprising a communication interface circuit for externally transferring a value measured by said first and second measurement means and a calculation result by said calculation means. Display device.