JP2001346339A - Power supply incorporating storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve maintainability by controlling the dispersion of charging states caused by the difference in self-discharging characteristics of each battery in a power supply that comprises a group of storage batteries connected in series for inputting and outputting a large current and that utilizes a storage battery that charges and discharge the group of the storage batteries. SOLUTION: A DC power supply 16 and a voltmeter 18 are connected to each of batteries 11a, 11b, etc. connected in series to constitute a circuit between the batteries and the DC power supply. A closed circuit voltage when a current is supplied and an open circuit one when the current supply is stopped are measured. Then, a computing and controlling device 20 obtains the difference between a voltage permissible range specified in advance and the actually measured voltage of closed and open circuits of each battery, thereby charging each battery additionally with a certain capacity if necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device using a storage battery including a battery group (storage battery module) in which a plurality of storage batteries are connected in series.

[0002]

2. Description of the Related Art Conventionally, a power supply of this type, which is used as a power supply for an electric vehicle or a hybrid electric vehicle, for example, is required to rapidly supply large power to the outside and receive large power from the outside. You. In such a use environment, a high voltage is generally required in order to suppress energy loss in the wiring portion. For this purpose, a battery group in which a plurality of storage batteries are connected in series has been used for discharging and charging.

[0003] However, the capacity of the battery is not uniform, but varies. Due to this, when the battery is used in the above-described series connection state, a battery having a small capacity (hereinafter, referred to as a “specific battery”) is discharged. In the end of discharge,
In addition, when charging, it is difficult to determine the end of charging from the voltage measurement of the battery group, so that the battery may be excessively charged.These abnormalities become abnormal as the number of batteries connected in series increases. Detection becomes difficult.

[0004] For example, in the case of an alkaline storage battery, when the specific battery is inverted, the internal pressure of the battery is unavoidably increased, especially in large current discharge, and the safety valve is opened to release gas to the outside of the system, thereby impairing the life of the battery. Become. In addition, even when the specific battery is excessively charged, the re-combination of the gas generated inside by the high current charging cannot be performed in time, and similarly, the gas is released to the outside of the system, thereby shortening the life of the battery. there were. In other types of batteries such as non-aqueous batteries, overcharging or overdischarging causes
In some cases, the activity of the battery itself is lost, which has been a further problem.

In order to avoid overdischarging or overcharging of a specific battery in the battery group, the state of charge of the battery group is evaluated, and the battery is used in a region where overdischarge or overcharging does not occur due to a variation in battery capacity. A method has also been implemented. That is, in the above-described method, for example, the initial charge state of the battery group is fixed at about 50% of the battery capacity, and the charge state and the discharge amount for the battery group are measured and integrated to estimate the charge state.

[0006]

However, in the above-mentioned method, although the state of charge can be grasped almost accurately during a certain period of use, an error from the actual state of charge occurs when the period of use is long. In addition to the above, unavoidable differences in the self-discharge characteristics of the batteries and variations in the battery temperature related to the self-discharge cause differences in the charge states of the individual batteries constituting the battery group. That is, in the above method, in addition to the deviation of the state of charge of the battery group from the state of charge estimated by the rough estimation, the state of charge of each battery varies. For this reason, long-term use without maintenance is difficult, and it is necessary to adjust the charge state of each battery as needed. However, it is generally difficult to grasp the state of charge of each of the batteries constituting the battery group, except for the battery whose open circuit voltage significantly changes depending on the state of charge, and for example, has excellent voltage flatness like an alkaline storage battery. In the case of the battery, it is particularly difficult to grasp the state of charge only from the open circuit voltage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a simple and inexpensive power supply device that can use a series-connected battery group for a long time without maintenance.

[0008]

According to the present invention, there is provided a power supply apparatus having a battery group in which a plurality of storage batteries are connected in series, and using a storage battery for charging and discharging the battery group. A current measuring means comprising an ammeter for measuring the input / output current of the battery group; a DC power supply for generating a plurality of energized states or any of an energized state and a non-energized state for each battery of the battery group; A voltage measuring means comprising a voltmeter for measuring a voltage in each of the batteries when charging, discharging and pausing using a power supply, and connection switching between the DC power supply and the voltage measuring means and the individual batteries are performed. Calculating the state of charge of the battery group based on the input / output current value measured by the connection switching means including a circuit switcher and the preset initial state of charge setting of the battery group; In both cases, an arithmetic control unit including an arithmetic control unit that specifies a plurality of energized states of each of the batteries or a voltage allowable range in any of the energized state and the non-energized state based on data or a calculation formula input in advance. The arithmetic and control unit is configured such that the voltage measured by the charging or discharging on the high current side in the energized state of each battery set from the DC power supply is lower than the specified allowable voltage range on the high current side. The voltage measured on the small current side or the non-energized state of the energized state is set in advance for each battery that does not exceed the voltage allowable range on the specified small current side or the non-energized state. There is provided a power supply device using a storage battery for charging an electric quantity by sequentially switching connections from the DC power supply.

That is, each battery is connected to a DC power supply, a circuit is formed between the battery and the DC power supply, charged at a predetermined current value for a predetermined time, and a closed circuit voltage at a predetermined time after the start of charging. Measured and then measured the open circuit voltage after a certain period of time after stopping charging, the closed circuit voltage was a value reflecting the battery charging state and internal impedance, and the open circuit voltage reflected the battery charging state Value.
On the other hand, the state of charge of the battery group is calculated using the input / output current value and the initial state of charge setting value. Specify a range. Next, the arithmetic and control unit determines that a battery whose actually measured closed circuit voltage is lower than the voltage allowable range and whose open circuit voltage does not exceed the voltage allowable range is a battery in a low state of charge, and sets a preset electric power. By charging the amount, the state of charge can be increased.

Although the amount of additional charge for a battery having a low open circuit voltage can be arbitrarily set, it is not desirable to charge the battery until it greatly exceeds the state of charge of another battery. The amount of electricity for the additional charge is 15% or less of the battery capacity and 1% or more. Further, the deterioration of the battery can be detected based on the difference between the decreasing closed circuit voltage and the increasing open circuit voltage when the internal impedance increases. In addition, for a battery having an abnormal self-discharge speed, such a battery is frequently recharged, and thus can be detected based on the frequency of recharge. By detecting these defective batteries, the occurrence of abnormality is notified.

[0011] Further, the wiring connection of each battery is constituted by a simple detachable fitting structure of a first metal fitting for multipoint connection and a second metal fitting attached to the tip of a cable from a DC power supply. This facilitates battery replacement.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a power supply device using a storage battery according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram showing an example of a configuration of a power supply device using a storage battery according to the present invention. In the figure, a power supply device 10 according to the present invention includes a series-connected storage battery group 11 in which batteries 11a, 11b,... Are connected in series, an electric motor 13 serving also as a generator and driving a driving body 12, and a series-connected battery group. 11, a current controller 14 for controlling the amount of current supplied to the motor 13; an ammeter 15 for measuring the input / output current of the series-connected storage battery group 11;
A DC power supply 16 for charging the individual batteries, a circuit switch 17 for switching connection between the individual batteries and the DC power supply 16, and a voltmeter 18 for measuring a closed circuit voltage of the batteries after the start of charging. A control panel 19 for inputting the operating conditions of the electric motor 13, and a control instruction to the current controller 14 based on the operating conditions, to control the switching operation of the circuit switch 17 and to control the state of charge of the series-connected storage battery group 11. And an arithmetic and control unit 20 for designating the allowable voltage range in the calculation and in the energized state or the non-energized state of the battery.

In such a configuration, the series-connected storage battery group 11 includes at least one storage battery module in which batteries 11a, 11b,... Are connected in series, and has been charged to a predetermined charge state before use. It is in the initial charge state. The series-connected storage battery group 11 is connected to the electric motor 13 via the current controller 14. The driving body 12 is also connected to an external driving source (not shown), and has a structure for charging the series-connected battery group 11 with electric energy generated by the driving source. The present invention is not limited to this,
For example, a structure may be used in which the series-connected battery group 11 is charged as necessary with a DC-converted current from an external commercial power supply (not shown).

When the operating conditions of the electric motor 13 are inputted from the operation panel 19, the arithmetic and control unit 20 gives a control instruction to the current controller 14 to control the electric current supplied from the series-connected battery group 11 to the electric motor 13, and At the start of operation (acceleration) of the drive unit 12, the driving unit 12 is driven with a desired output,
When the driving body 12 is stopped or decelerated, the electric motor 13 is made to function as a generator, and the regenerative current is charged to the series-connected battery group 11.

When the driving body 12 is stopped or decelerated, if the DC connection battery group 11 is charged with all the braking energy as a regenerative current, the charging current of the DC connection battery group 11 may exceed the chargeable current value. In this case, for example, the driving body 12
May be combined with external mechanical braking means (not shown) for braking. In the operating state, the DC connection battery group 11 repeats charging and discharging based on a command from the operation panel 19, and the input / output current flowing at this time is measured by the ammeter 15 and the arithmetic and control unit 20
Multiplied by

In the arithmetic and control unit 20, data on the state of charge (initial state of charge) of the DC-connected battery group 11 before use is input and stored in advance. The arithmetic and control unit 20 adds the data of the initial state of charge and the integrated value of input / output current by charge / discharge after the start of use by using the following formula to calculate the state of charge (charge) of the DC-connected battery group 11. Of electricity) is calculated.

(Initial charge amount) + (input / output current integrated amount) −
(Estimated amount of self-discharge) On the other hand, the arithmetic and control unit 20 uses, for example, the power supply device of the present embodiment as a power supply device of an automobile while current is not input and output between the electric motor 13 and the DC connection battery group 11. In this case, when the key is inserted and the idling state or the like is stopped, the circuit switch 17 is switched to connect the individual batteries to the DC power supply 16 in order, and charge each battery with a predetermined current from the DC power supply 16. Do. In the present embodiment, for example, among the batteries of the DC connection battery group 11, the batteries are connected to the DC power supply 16 in order from the battery 11a, and each battery is charged with a predetermined current from the DC power supply 16.

When a predetermined time has elapsed after the start of charging of the battery 11a, a closed circuit voltage of a circuit formed between the battery 11a and the DC power supply 16 is measured by a voltmeter 18, Do not record in memory. Next, the arithmetic and control unit 20 stops the current from the DC power supply 16 and, after a lapse of a predetermined time, measures the open circuit voltage of the circuit formed between the battery 11a and the DC power supply 16 with the voltmeter 18, and similarly measures It is recorded in the memory in the arithmetic and control unit 20.

The arithmetic and control unit 20 uses the recorded closed-circuit voltage value and open-circuit voltage value to calculate the above-mentioned state of charge using the previously input and stored correlation table data or calculation formula. Compared with the closed circuit voltage value and open circuit voltage value corresponding to the value, the actually measured closed circuit voltage value is lower than the allowable value of the closed circuit voltage value corresponding to the state of charge calculation value, and is actually measured. When the set open circuit voltage value is within the preset allowable range, the DC power supply 16 is operated to charge the battery 11a with a predetermined amount of charge (additional charge).

The reference data for comparing the closed circuit voltage and the open circuit voltage changes depending on the current value, the battery capacity, the ambient temperature, and the like when measuring the closed circuit voltage. For this reason, it is possible to determine and measure an appropriate current value and energizing time for measuring the closed-circuit voltage in accordance with the battery capacity, and create the measurement. For example,
A battery with a capacity of 7 Ah can be charged at 35 A for 5 seconds, and the voltage at the end of charging can be recorded as a closed circuit voltage, and then the voltage 5 seconds after charging is stopped can be recorded as an open circuit voltage.
As reference data, a value obtained when the same processing is performed on a battery in a healthy state is measured in advance and used. Since the voltage value changes depending on the ambient temperature, the reference data is, for example, 10
It is desirable to measure and record each change in ° C. and calculate an approximate value for the intermediate temperature by an interpolation method.

The DC power supply 16 is preferably used because the operation is simple if, for example, a constant current power supply is used, and a predetermined amount of charge performed when it is determined that the state of charge is low only needs to control the charging time. However, the present invention is not limited to this. When the battery is mounted on an automobile, the DC power supply 16 may be configured by, for example, a storage battery provided separately from the battery group 11 so that the DC power supply 16 can be charged by using a part of the power generated by the electric motor 13. It may be configured by using some of the modules 11.

When the above series of operations on the battery 11a is completed, the arithmetic and control unit 20 then controls the circuit switch 17 to form a circuit between the battery 11b and the DC power supply 16, and performs the same operation as above. Do. Then, the arithmetic and control unit 20 similarly switches the batteries sequentially and performs the same operation on all the batteries constituting the DC-connected battery group 11, thereby exceeding the allowable range beyond the calculated state of charge. In addition, additional charging is performed on a battery having a low state of charge to correct variations in the state of charge of each battery, and a history of additional charging is recorded for each battery.

It should be noted that if the charge amount at the time of additional charge is too large, the state of charge of the battery immediately after the additional charge may be too high as compared with other batteries, and if it is too small, additional charge must be performed frequently. Have to be. Therefore, in the present embodiment, taking into account the fact that the initial state of charge is constant at about 50% of the battery capacity and the range in which the battery is not fully charged, the preferable charge amount is 1% to 15% of the nominal capacity of the battery. And more preferably, 2% or more and 10% or less.

Further, in the power supply device 10, when the open circuit voltage becomes higher than the allowable range in spite of the low closed circuit voltage of the battery, or when the frequency of the additional charge is determined to be different from the recorded history. In a situation such as when the battery is extremely high compared to the battery, there is a possibility that the cycle life of the battery is exhausted or a short circuit occurs inside and outside the battery.
Therefore, in the arithmetic and control unit 20 of the present embodiment, a function of detecting these abnormal batteries and informing the operation panel 19 of the abnormal batteries is added.

As described above, the open circuit voltage generally tends to decrease as the battery charge decreases. However, the open circuit voltage varies depending on the history of charging or discharging before measurement, and also changes depending on the value of the current flowing through the circuit at the time of charging and discharging. Attempting to estimate from voltage alone results in non-negligible errors. On the other hand, in the present embodiment, each battery is charged at a predetermined current value for a predetermined time, and a closed circuit voltage is measured for a predetermined time after the start of charging.
Next, the open circuit voltage is measured after a certain period of time has elapsed since the charging was stopped. As a result, the closed circuit voltage has a value reflecting the amount of charge of the battery and the internal impedance of the battery, the open circuit voltage has a value reflecting the amount of charge of the battery, and the charging under a certain condition immediately before the measurement of the open circuit voltage. Therefore, in this embodiment, the influence of the charge / discharge history of the battery can be greatly reduced, and the measurement accuracy can be improved.

In this embodiment, the case where the closed circuit voltage at the time of charging and the open circuit voltage after the charging is stopped has been described. However, the present invention is not limited to this. A combination of a later open circuit voltage or a combination of closed circuit voltages with different currents can also be used. Further, the arithmetic and control unit of the present embodiment calculates the charge amount of the battery group using the initial charge state setting value and the input / output current value, and based on the data or the calculation formula input in advance, the energization state of each battery, respectively. Specify the voltage tolerance for. A battery whose actually measured closed-circuit voltage is lower than the voltage allowable range and whose open-circuit voltage does not exceed the voltage allowable range has a clearly lower charge state than the charge state recognized by the arithmetic and control unit. Is determined, and a predetermined amount of electricity is charged from the DC power supply to the battery. In this case, it is not necessary to accurately grasp the difference between the state of charge recognized by the arithmetic and control unit and the state of charge of the actual battery, and it is possible to increase the state of charge by performing additional charging to a battery that has shifted slightly below the allowable difference. I just need.

The reason for this is that the state of charge of the battery to be additionally charged is reduced at a higher speed than the rate of reduction of the state of charge due to self-discharge or the like, which is the basis for calculation by the arithmetic and control unit. This is because even if the battery is charged beyond the charge state recognized by the arithmetic and control unit due to the additional charge, the charge will again fall below the value after a long use. Therefore, in this embodiment,
The amount of charge for a battery with a low open circuit voltage can be set arbitrarily, but it is not desirable for operation to charge the battery until it greatly exceeds the state of charge of other batteries. It is desirable to be within 15%, and it is desirable that the amount of electricity per operation be within 10% of the battery capacity.

In the present invention, since the deviation from the state of charge recognized by the arithmetic and control means is detected and additional charging is performed for each battery, the rate of decrease in the actual state of charge of the battery is determined by the state of charge calculation. If the value is smaller than the value which is the basis of the correction, the correction becomes difficult. By calculating the state of charge of the battery group in accordance with the variation in the self-discharge of the battery actually used, the self-discharge coincides with the minimum one, or the rate of decrease in the state of charge is made to coincide with a smaller estimated value. It is preferable that the additional charging be performed on all the batteries, and the variation of each battery be adjusted based on the difference in the frequency of the additional charging.

On the contrary, in the present invention, it is also possible to estimate the rate of charge decrease higher than that of the actual battery, and to correct the amount by which the state of charge shifts higher by discharging. However, in this case, useless discharging is performed, so that it is more desirable to make correction by additional charging. In particular, if the battery charge state is determined using the closed circuit voltage during charging and the open circuit voltage after charging is stopped, and the battery with low charge state is additionally charged, a small capacity and variable current function can be achieved. And a simple relay device that turns on and off the current for a set time, which is advantageous in terms of cost.

The amount of electricity to be charged for judging the state of charge of each battery may be negligible with respect to the capacity of the battery. On the other hand, it is more desirable to use the same amount when calculating the state of charge of the arithmetic and control unit. In addition, when the battery deteriorates due to a large number of charge / discharge cycles, the internal impedance generally rises due to the formation of a film on the electrode surface and the heterogeneous distribution of the electrolytic solution, and the closed-circuit voltage drops significantly. The circuit voltage rises because the electrodes cannot be completely discharged. The deterioration of the battery can be grasped by detecting the difference between the closed circuit voltage and the open circuit voltage. In addition, when impurities adhere to the separator that separates the positive electrode and the negative electrode in the battery, the electrical insulation of that portion is reduced, and a battery having a large apparent self-discharge may be generated. Such a battery is frequently recharged, and can be detected and specified. In the present embodiment, by adding a function of notifying the occurrence of these defective batteries, the maintainability and reliability of the power supply device can be improved.

Further, in a DC connection battery group for a large current,
Since the electrical resistance of the connection between the individual batteries becomes a problem, several series-connected modules configured with metal fittings for multipoint welding are used, and this module is further connected with a bus bar for large current. A structure for preventing a voltage drop due to a connection portion is generally used. Therefore, in the DC connection battery group 11 of the present embodiment, as shown in FIGS. 2 and 3, a first metal fitting capable of connecting individual batteries with high rigidity at multiple points, for example, a metal fitting 21 made of iron And a structure interposed. The metal fitting 21 is a circular bottom plate 2 provided between the batteries 1.
2 and the cylindrical side plate 23 are integrally formed,
The side plate 23 has a connection portion 23 connected to a power cable 24 from the DC power supply 16 by notching a part thereof.
a is provided.

A metal fitting 25 as a second metal fitting is attached to the tip of the power cable 24. The metal fitting 25 is made up of a magnet and a connection terminal 25a to which the tip of the power cable 24 is connected, and holds the connection terminal. A connection member 25b, and an insulating member 25c disposed between the connection terminal 25a and the holding member 25b.
, And the connection terminal 25a is pressed against the connection portion 23a by magnetic force, thereby enabling connection between the individual batteries 1 and the power supply cable 24. In addition, reference numeral 26 in FIG. 2 denotes a cylindrical insulator, which fixedly holds the battery 1 together with an insulating function.

As described above, in the present embodiment, the wiring connection to the individual batteries is performed by connecting the first metal fittings for these multipoint connections and a part of the bus bar to the cables used for voltage measurement and charging for each battery. If it is configured with a fitting structure that can be easily attached and detached with the second metal fitting attached to the tip,
When a specific battery is deteriorated, only the module including the battery can be easily replaced, so that the handling can be simplified.

In the present invention, the present invention is not limited to this. For example, a part of the first metal fitting which can be connected at multiple points may be formed in a projection shape, or the projection-shaped product may be welded to the first metal fitting. hand,
It is also possible to form a fitting structure that can be easily attached to and detached from the tip of the power cable 24. In the power supply device of the present invention, since the current supplied from the DC power supply to each battery of the DC connection battery group is small, there is no particular problem. Therefore, a simple detachable fitting structure for the inter-battery connection structure can be applied.

The present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention.

[0036]

As described above, according to the present invention, the state of charge of each battery is detected, and additional charging is performed for each battery as necessary. A power supply that can be used without maintenance can be provided with a simple and inexpensive configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a configuration of a power supply device using a storage battery according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a battery connection structure of the DC connection battery group shown in FIG.

FIG. 3 is an enlarged perspective view of the inter-battery connection structure shown in FIG. 2;

[Explanation of symbols]

 Reference Signs List 10 power supply device 11 series-connected battery group 1, 11a, 11b, ... battery 12 driver 13 motor 14 current controller 15 ammeter 16 DC power supply 17 circuit switcher 18 voltmeter 19 operation panel 20 operation control device 21 first metal fitting 24 power cable 25 second fitting

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hirotaka Hayashida 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in Toshiba R & D Center (reference) 5G003 AA07 BA03 DA07 DA12 EA09 FA03 FA06 5H022 AA04 CC09 5H030 AA01 AS08 BB01 FF42 FF43 FF44

Claims (4)

[Claims] 1. A power supply device having a battery group in which a plurality of storage batteries are connected in series and using a storage battery for charging and discharging the battery group, wherein current measuring means for measuring input / output current of the battery group And a DC power supply for generating a plurality of energized states or any of an energized state and a non-energized state for each of the batteries in the battery group, and a voltage at each of the batteries when charging, discharging and suspending using the DC power supply Voltage measuring means for measuring the DC power supply and the voltage measuring means, and connection switching means for switching the connection between each of the batteries, the input / output current value measured by the current measuring means and the battery group in advance. Based on the set initial charging state setting value,
An operation of calculating the state of charge of the battery group and specifying a plurality of energized states of each of the batteries or a voltage allowable range in any of the energized state and the non-energized state based on data or a calculation formula input in advance. Control means, wherein the arithmetic and control means is configured such that the voltage measured in the charging or discharging on the high current side in the energized state of each battery set from the DC power supply is the specified large current side voltage tolerance. For each battery that is lower than the range and the voltage measured on the small current side or the non-energized state of the energized state does not exceed the voltage allowable range on the specified small current side or the non-energized state, A power supply device using a storage battery, wherein charging of a predetermined amount of electricity is performed by sequentially switching connections from the DC power supply. 2. The power supply device using a storage battery according to claim 1, wherein the charging of the amount of electricity performed by the DC power supply is 15% or less of the nominal capacity of the battery and 1% or more. 3. The arithmetic and control unit stores the supply time of the amount of electricity from the DC power supply for each of the batteries, and when the frequency of the supply exceeds a preset value, 2. When the voltage is lower than the voltage allowable range and the voltage on the small current side or the non-energized state exceeds the voltage allowable range, it is determined to be abnormal and notified.
Or a power supply device using the storage battery according to 2. 4. The battery group is constituted by a module in which a plurality of storage batteries are connected in series with a first metal fitting for connection interposed between the batteries, and a part of the first metal fitting is the module. The storage battery according to any one of claims 1 to 3, wherein the storage battery according to any one of claims 1 to 3, wherein the storage device according to any one of claims 1 to 3, is configured to easily and detachably fit with a second fitting attached to a tip of a cable used for voltage measurement and charging for each battery. Power supply.