JPH0888944A - Charging equipment of combined battery - Google Patents

Abstract

PURPOSE: To increase a discharge capacity as a combined battery and also to suppress the deterioration of a specify by a method wherein the amount of charge to be replenished is computed for each cell or each module on the basis of voltage and current values detected and replenishment charging is conducted selectively for each cell or each module. CONSTITUTION: AC power given from an AC power source 15 is supplied from a transformer 14a to a diode 11a through a current control element 9a, rectified by the diode and then given to a battery 1a. An arithmetic device 6a computes the amount of replenishment charge on the basis of voltage and current values determined by a voltage sensor 4a and a current sensor 5a and controls a current control circuit 8a in accordance with the value of the amount. The current control circuit 8a controls the current control element 9a to open and close in accordance with the result of computation so as to charge the battery 1a with a necessary amount of replenishment charge. In the case when all batteries 1a to 1n are charged under the same condition, current control elements 9a to 9n are controlled to be kept in an opened state until the battery reaching a charging end voltage is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charger for a battery pack in which a plurality of secondary batteries are connected in series or in series and parallel, and more particularly to a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The present invention relates to a charging device suitable for an assembled battery.

[0002]

2. Description of the Related Art In an electric vehicle or the like, an assembled battery in which a plurality of secondary batteries are connected in series or in series parallel is used.
In the case of such an assembled battery, the degree of decrease in discharge capacity (the amount of electricity that can be discharged) differs depending on each battery. For example, due to variations in manufacturing among batteries and uneven temperature distribution when used in assembled batteries, there are differences in the self-discharge amount and charge acceptance rate (charge / discharge efficiency). The degree of decrease differs for each battery. Therefore, DOD (depth of discharge: 100% at full discharge, 0 at full charge)
%) The discharge capacity from 0% varies from battery to battery,
As a result, the discharge capacity of the assembled battery is reduced. That is, at the time of discharging, a battery whose discharge capacity has become small is quickly discharged and becomes an over-discharged state, and this over-discharged battery becomes a load of other batteries, and all the batteries become DOD.
The voltage drops before it reaches 100%, and the battery pack ends discharging. Also, at the end of discharge of the battery, the internal resistance increases and the internal heat generation increases, which deteriorates due to the instability of the battery materials and the deterioration caused by the local flow of a large current. Since the deterioration of the battery progresses, the life of the battery in the over-discharged state becomes large.

On the other hand, during charging and discharging, DOD100
Batteries that did not reach% reached DOD0% first and the voltage rises, and charging ends. However, batteries that are over-discharged during discharging do not reach DOD0% and charging ends. The difference widens, and the difference in discharge capacity of each battery also widens. Therefore, when charging and discharging are repeated, the battery having a small discharge capacity is always insufficiently charged, and the variation becomes large, and the discharge capacity of the entire assembled battery decreases. Generally, in the case of secondary batteries, if they are overcharged beyond the end-of-charge voltage or over-discharged beyond the end-of-discharge voltage, the life will be shortened, but especially non-aqueous electrolyte secondary batteries such as lithium ion batteries Since this tendency is strong in the case of batteries, when even one of the assembled batteries reaches the charge end voltage or the discharge end voltage, it is necessary to terminate the charging and discharging as the assembled battery. As described above, in an assembled battery in which a plurality of secondary batteries are connected in series, there are problems that the discharge capacity and the DOD are varied, the discharge capacity of the entire assembled battery is reduced, and a particular battery is particularly deteriorated. there were.

As a first conventional example for dealing with the above problem, there is, for example, one described in Japanese Patent Application Laid-Open No. 51-85437. This device increases the charging voltage or the charging current when the variations in the voltages of the batteries forming the assembled battery increase, and performs uniform charging. A second conventional example is Japanese Patent Laid-Open No. 61-206179.
Is described in Japanese Patent Application Publication No. In this device, a bypass circuit is connected in parallel to each of the batteries that make up the assembled battery, a fully charged battery conducts the bypass circuit to reduce the charging current, and a battery that has not finished charging continues to be charged. By doing so, the variation is reduced. Also, the third
As a conventional example of the above, there is one described in JP-A-5-64377. In this conventional example, among the respective batteries constituting the assembled battery, one that stops charging when it reaches full charge, and one that has a circuit that bypasses the charging current when the battery reaches full charge are described. ing. 12
Is the battery voltage V when operating the bypass circuit of the battery which has reached full charge (end-of-charge voltage) as described above.
b, current Ib flowing through the battery, current I flowing through the bypass circuit
It is a characteristic view which shows the change of bp. As shown in FIG. 12, from the start of charging to time t ₁ , the bypass circuit is turned off,
The current of the charging circuit is directly used as the battery current Ib. Then, the battery voltage Vb gradually rises due to the charging, and the bypass circuit is activated at the time t ₁ when the charging end voltage is reached. After that, the current Ibp flowing through the bypass circuit is gradually increased and the battery current Ib is gradually decreased so that the battery voltage Vb does not exceed the end-of-charge voltage. At time t ₂ , the charging current is 0
It has become. As mentioned above, full charge (end-of-charge voltage)
The variation can be eliminated by operating the bypass circuit to reduce the charging current for the batteries that have reached the above condition, and continuing normal charging for the other batteries that have not reached the full charge.

[0005]

However, in the case of the lead-acid secondary battery, the method described in the first conventional example can charge each battery to a full charge. In the case of the water-based electrolyte secondary battery, when an overvoltage is applied as in the first conventional example, there is a problem that the life of the battery is seriously adversely affected as described above. Further, in both the second conventional example and the third conventional example, since the charging current of the fully charged battery is bypassed, there are the following problems. That is, when charging, the battery is not always charged until it is fully charged, and in many cases charging is terminated halfway,
In the above-mentioned conventional example, the variation eliminating function does not work until the battery is fully charged, so it is difficult to always eliminate the variation of each battery. In addition, like the first to third conventional examples,
Even if each battery is fully charged during charging, the actual discharge capacity of each battery will be different due to the difference in discharge capacity and the difference in internal resistance due to manufacturing variations, temperature differences, etc. as described above. There is a difference in reaching. For example, as shown in FIG. 13, even when each battery is discharged from full charge, the time point at which the discharge end voltage reaches the discharge end voltage differs due to the difference between the discharge capacity and the internal resistance of each battery.
Battery reaches the end of discharge fastest. Therefore, as described above, there is a problem that the deterioration of the battery having the characteristic A progresses and the discharge capacity of the entire assembled battery decreases.

The present invention has been made in order to solve the problems of the prior art as described above, and it is possible to increase the discharge capacity of a battery pack and suppress deterioration of a specific battery. An object is to provide a battery charging device.

[0007]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in the invention according to claim 1, an assembled battery in which a plurality of cells each composed of one secondary battery or a module each composed of a plurality of cells are connected in series or series-parallel, and the voltage of the cells or modules is detected. Voltage detecting means, current detecting means for detecting a current flowing through the cell or module, and calculating means for calculating a charge amount to be replenished for each cell or each module based on the detected voltage value and current value. And a control means for selectively performing supplemental charging for each cell or each module according to the calculation result of the calculation means. The above configuration corresponds to, for example, the embodiment described later with reference to FIG.

According to a second aspect of the present invention, in the arithmetic unit, the discharge capacity decrease ΔQr due to an increase in internal resistance,
Sum of discharge capacity decrease ΔQc due to deterioration and discharge capacity decrease ΔQd due to insufficient initial charge ΔQ = ΔQr + ΔQc
+ ΔQd is calculated, and ΔQ is used as the charge amount to be replenished. Further, as described in claim 3, the arithmetic unit adds ΔQ + ΔQe to the above ΔQ by adding a charge amount ΔQe corresponding to a predetermined value or an internal resistance value to a battery having a particularly large internal resistance. Is the charge amount to be replenished. Alternatively, as set forth in claim 4, the arithmetic means respectively calculates the voltage of each cell or module at each of a plurality of predetermined current values and each of the plurality of current values obtained from the voltage of the entire assembled battery. The amount of insufficient electricity at the specified current value is calculated on the basis of the average voltage of one cell or one module in 1 above and is used as the supplementary charge amount. The above configuration is
For example, this corresponds to the embodiment shown in FIG. 6 described later. Alternatively, claim 5
As described in (1), the calculating means calculates the voltage of each cell or each module at a predetermined current value, and the average voltage of one cell or one module obtained from the voltage of the entire assembled battery at the specified current value. The shortage of electricity is calculated and used as the supplementary charge.

According to the invention of claim 6,
When the load of the battery pack is the drive device of the traveling vehicle, the supplementary charging is performed by regenerative charging performed when the traveling vehicle is decelerated or braked. The above configuration corresponds to, for example, the embodiment shown in FIG. 8 described later. Further, in the invention according to claim 7, all of the assembled battery and a resonant circuit provided for each cell or each module having a different resonant frequency from the others, and a rectifying circuit for rectifying the output thereof Of the variable frequency power source connected to the resonant circuit and the rectifier circuit as a whole, and the frequency of the variable frequency power source is made to match the resonant frequency of the resonant circuit of the cell or module requiring supplementary charging, which is obtained by the computing means. And a frequency setting means for controlling so that only the cells or modules of the resonance circuit resonating at the power supply frequency are selectively replenished and charged. The above configuration corresponds to, for example, the embodiments shown in FIGS. 9 and 11 described later. Further, claim 8
As described above, the secondary battery is a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery). However,
The present invention can be applied to an assembled battery of other secondary batteries such as a lead-acid secondary battery.

[0010]

In the invention described in claim 1, when charging the assembled battery 1 in which a plurality of cells each consisting of one secondary battery or a module consisting of a plurality of cells are connected in series or series-parallel, the above-mentioned cells are charged. Alternatively, the amount of charge to be replenished is calculated for each cell or module based on the voltage value and current value of the module, and replenishment charging is performed for each cell or module. Therefore, the discharge capacity of each cell or module can always be made uniform,
It is possible to increase the discharge capacity of the whole assembled battery and suppress deterioration of a specific battery. The charge amount to be replenished is, for example, as described in claim 2, a discharge capacity decrease ΔQr due to an increase in internal resistance.
And the discharge capacity decrease ΔQc due to deterioration and the discharge capacity decrease ΔQd due to insufficient initial charge are taken as ΔQ. Further, the invention of claim 3 is such that, for a battery having a particularly large internal resistance, the charge amount ΔQe in the margin is added to the above ΔQ.

Further, the invention of claim 4 pays attention to the fact that the relationship between the average voltage of the battery and the discharge amount varies depending on the discharge current, and a plurality of current values (for example, "large", "medium", "small"). Of 3
The replenishment charge amount is calculated on the basis of the difference between the average voltage when the value is taken) and the actual voltage of each cell at that time. Further, the invention of claim 5 is to calculate by one of the plurality of current values. Further, the invention of claim 6 is configured such that the above-mentioned supplementary charging is performed by regenerative charging, and since the supplemental charging can be performed between load driving, the discharge capacity of each battery is always kept uniform. You can According to the invention of claim 7, a resonance circuit is used as a means for selecting a cell or a module for performing supplementary charging, and each battery is selectively selected without using a current control element such as a switching element. Can be charged. In addition, in claim 1, only the supplementary charging is specified, but in addition to the supplementary charging, a normal basic charging (for example, all cells or modules are charged under the same conditions) may be performed. . In the basic charging, the control means is opened to supply the charging current, for example, for a predetermined time or until the battery which reaches the end-of-charge voltage is detected.

[0012]

EXAMPLES The present invention will be described in detail below based on examples. FIG. 1 is a diagram of a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an assembled battery, in which batteries 1a to 1n (cells formed of a single battery or a module formed of a plurality of cells) are connected in series. It should be noted that they may be connected in series and parallel. 2 is a control device,
The electric power supply is controlled when the load 3 is driven by the electric power of the assembled battery 1. For example, the control device 2 is a circuit including a DC / AC converter and a control computer in an electric vehicle, and the load 3 is an electric vehicle driving motor. The control device 2 and the load 3 are the output (discharge) circuit of the assembled battery, and the parts 4 and below described below are the parts of the charging circuit of this embodiment. Reference numeral 4 is a voltage sensor that detects the voltage of each battery, and 5 is a current sensor that detects the current flowing through the battery. The voltage sensor 4 and the current sensor 5
Is shown separated from the batteries, but is connected to each battery. For example, as for the voltage, the terminal of the battery may be simply connected to the arithmetic unit 6 and the voltage value may be detected by the arithmetic unit 6, or the current sensor 5 may be provided with one sensor common to each unit cell. . Further, 6 is an arithmetic unit (details will be described later), 7 is a memory, and 8 is a current control circuit, which controls the current control element 9 based on the arithmetic result of the arithmetic unit 6. The current control element 9 is an opening / closing element composed of a transistor or the like, a variable resistance or a variable capacitance diode, etc., and controls the ON time in the case of the switching element, changes the resistance value in the case of a variable resistance, and changes the capacitance in the case of a variable capacitance diode. Is controlled to control the amount of electricity stored, thereby controlling the value of the flowing current. Further, 10 is a Zener diode for preventing overvoltage, 11 is a rectifying diode, 12 and 13 are resistors, and 14 is a transformer. The above 4 to 14 constitute a charge control circuit, and as shown by suffixes a to n in the figure, the batteries 1a to 1 are attached.
It is provided for each n. However, the arithmetic unit 6
The memory 7 may be provided as a whole. Further, since the currents flowing through the batteries 1a to 1n are the same, the current sensor 5
Also, one may be provided for the entire assembled battery 1. Reference numeral 15 is an AC power supply that supplies power to all charging control circuits.

Next, the operation will be described. The battery 1a will be described as an example, but the same applies to other batteries. The AC power supplied from the AC power supply 15 is supplied to the transformer 1
It is supplied to the battery 1a after being rectified from the diode 4a via the current control element 9a from the diode 4a. The calculation device 6a calculates a supplementary charge amount based on the voltage value and the current value obtained by the voltage sensor 4a and the current sensor 5a (details will be described later), stores the result in the memory 7a, and calculates the current according to the value. It controls the control circuit 8a. The current control circuit 8a controls the opening and closing of the current control element 9a according to the above calculation result, and charges the battery 1a by the necessary supplementary charge amount. In the case of basic charging other than replenishment charging (for example, all the batteries 1a to 1n are charged under the same conditions), for example, during a predetermined time or until a battery that reaches the end-of-charge voltage is detected. ,
The current control elements 9a to 9n are controlled so as to be kept open. Further, the Zener diode 10a conducts when the terminal voltage of the battery 1a reaches or exceeds a predetermined value and prevents overvoltage from being applied. As described above, each battery is charged.

The calculation of the replenishment charge amount in the calculation device 6a will be described below. The replenishment charge amount is basically the sum of the decrease ΔQr in discharge capacity due to an increase in internal resistance, the decrease ΔQc in discharge capacity due to deterioration of the battery, and the decrease ΔQd in discharge capacity due to insufficient initial charge ΔQ = ΔQr + ΔQ
It is calculated as c + ΔQd. 2 to 4 are discharge characteristic curve diagrams for explaining the above-mentioned respective decrease amounts ΔQr, ΔQc, and ΔQd of the discharge capacity, where the vertical axis is the voltage and the horizontal axis is the discharge time. First, as shown in FIG. 2, when the internal resistance Δr of the battery increases, the end of discharge is reached early, and the discharge capacity decreases. In this case, the discharge capacity decrease (loss) is ΔQ
r. Further, as shown in FIG. 3, when the battery deteriorates, the end of discharge reaches that much earlier, so the discharge capacity becomes smaller. In this case, the discharge capacity decrease (loss) is ΔQ
c. Further, as shown in FIG. 4, when the full charge has not been reached in the previous charge, the initial charge amount becomes insufficient and the end of discharge reaches that much earlier, so the discharge capacity becomes smaller. In this case, the reduced amount (deficiency) of the discharge capacity is ΔQd. The arithmetic unit 6a calculates the above-mentioned respective amounts of decrease in the discharge capacity, and sums them to obtain the supplementary charge amount ΔQ.

Hereinafter, a method of calculating the above-mentioned respective discharge capacity reduction amounts will be described with reference to FIGS. FIG. 2 is a discharge characteristic curve diagram for explaining a method of calculating the discharge capacity decrease ΔQr due to the internal resistance. First, two current values I
The voltage values V ₁ and V ₂ at ₁ and I ₂ are calculated respectively, and the internal resistance value r is calculated by the following equation (1). ΔV = | V ₂ −V ₁ | ΔI = | I ₂ −I ₁ | (Equation 1) ΔV / ΔI = r Next, when the prescribed maximum current value determined in advance is Ireg, the following (Equation 2) The maximum drop voltage ΔVmax is calculated by the formula. ΔVmax = r × Ireg (Equation 2) Next, in the discharge characteristic curve shown in FIG. 2, the characteristic curve (shown by the broken line) that is moved in parallel by the maximum drop voltage ΔVmax from the specified discharge characteristic curve shown by the solid line is discharged. The amount of electricity Q ′ that reaches the cutoff voltage is obtained, and Q ₀ in the specified discharge characteristic curve
Then, the decrease ΔQr in the discharge capacity is calculated from the difference between and. That is, ΔQr = Q ₀ −Q ′.

Next, FIG. 3 is a discharge characteristic curve diagram for explaining a method of calculating the discharge capacity decrease ΔQc due to the deterioration of the battery. First, the internal resistance value r is obtained in the same manner as in the case of ΔQr. Next, the open circuit voltage (terminal voltage when the battery terminal is opened) is estimated from the internal resistance value r.
This can be estimated by adding the voltage drop due to the internal resistance to the voltage at the time of discharge. Next, by comparing the actual voltage at a certain discharge amount with the voltage at the same discharge amount on the specified discharge curve, the actual discharge curve (shown by the broken line) with respect to the specified discharge curve shown by the solid line in FIG. ) Is calculated, the discharge amount Q ″ when the curve reaches the discharge end voltage is obtained, and the discharge capacity decrease ΔQc is obtained from the difference from Q ₀ in the specified discharge characteristic curve. That is, ΔQc = Q ₀ −Q ″ Is.

Next, FIG. 4 is a discharge characteristic curve diagram for explaining a method of calculating the discharge capacity decrease ΔQd due to the initial charge shortage. First, after completion of charging, the open circuit voltage of the battery is measured, and the value is set as the discharge amount 0 and compared with the specified discharge curve. If the discharge capacity is reduced, the open circuit voltage of the battery is lower than the specified voltage as shown in FIG.
The discharge amount Q * at the point where the value is extended in parallel to the x-axis direction and intersects with the specified discharge curve becomes the discharge capacity decrease ΔQd due to the insufficient initial charge. ΔQr and Δ obtained as described above
The supplementary charge amount ΔQ is obtained by adding Qc and ΔQd.

Next, another method of calculating the supplementary charge amount ΔQ will be described. FIG. 5A is a characteristic diagram showing an increase in internal resistance at the end of discharge. As shown in FIG. 5, in the final stage of discharge (portion of kQi), the battery temperature rises as the internal resistance increases, and the deterioration is promoted. Therefore, a battery with a small discharge capacity reaches the end of discharge first, and thus is more likely to deteriorate than other batteries. In order to solve the above problem, as shown in FIG. 5 (b), a battery having a small discharge capacity is replenished and charged by ΔQ to shift the internal resistance increase region at the end of discharge as shown by a broken line to deteriorate. Can be suppressed. The above-mentioned supplementary charge amount ΔQ is calculated by the following equation (3). ΔQ = Q- (1-k) Qi (Equation 3) where Qi: total discharge amount of i-th battery Q: total discharge amount required of i-th battery as assembled battery system k: internal resistance increasing region Coefficient indicating ratio The above coefficient k is expressed by the following equation (4). k = | Qi ₀ −Qi ′ | / Qi ₀ (Equation 4) where Qi ₀ : Discharge amount until the i-th battery reaches the discharge end voltage Qi ′: Discharge amount until the internal resistance starts to increase Next, still another calculation method of the supplementary charge amount ΔQ will be described.

In this embodiment, the basic replenishment charge amount ΔQ = ΔQr + ΔQc + ΔQd is further added with a margin replenishment amount ΔQe. In this case, the supplementary charge amount is ΔQ = ΔQr + ΔQc + ΔQd + ΔQe. The replenishment amount ΔQe for the allowance is set to, for example, a predetermined value set for a battery having an increased internal resistance or a value corresponding to the increased internal resistance. With this configuration, as in the case of FIG. 5, the internal resistance increase region at the end of discharge can be shifted as shown by the broken line, and deterioration can be suppressed.

Next, FIG. 6 shows a second embodiment of the present invention. In this embodiment, the sampling timing is configured based on the discharge current value having a correlation with the discharge amount. In FIG. 6, reference numeral 16 is an average voltage detection circuit for obtaining and outputting the average voltage of each battery from the total voltage of the battery pack 1. The total voltage is the voltage from the + terminal of the battery 1a to the-terminal of the battery 1n, and is calculated by a voltage sensor (not shown) or by inputting the terminal voltages of 1a and 1n to the average voltage detection circuit 16. Calculate Reference numeral 17 denotes a timing signal generation circuit that generates a timing signal when the current value flowing through the battery pack 1 reaches a predetermined value (details will be described later). In addition, the same reference numerals as those in FIG.

FIG. 7 is a characteristic diagram showing the relationship between the average voltage and the discharge amount of each battery. As shown in FIG. 7, it can be seen that when there is a large current discharge (the load is large), the average voltage drops significantly, and the fluctuation of the average voltage corresponds to the discharge current.
Therefore, if the average voltage at three predetermined current values of "large", "medium", and "small" is measured, the approximate discharge amount can be calculated from the characteristics of FIG. The embodiment of FIG. 6 is based on the above consideration, and has a predetermined “large” or “medium”.
When three types of “small” current values I _H , I _M , and _IL are detected, the timing signal generation circuit 17 sends respective timing signals S _H , S _M , and S _L to the average voltage detection circuit 16
The average voltage is detected from the total voltage with. Average voltage, the current value I _H, I _M, there are three types of V _H, V _M, V _L according to I _L. Then, the timing signal and the average voltage described above are sent to the arithmetic units 6a to 6n. Each of the arithmetic devices 6a to 6n performs the following arithmetic operation to obtain the supplementary charge amount. For example,
The i-th arithmetic unit 6i detects the voltage of the battery 1i at the time when the respective timing signals S _H , S _M , and S _L are given. This voltage also has three of the current value I _H, I _M, V according to _{I L H1, V M1, V} L1. Next, the computing device 6i calculates the supplementary charge amount of the battery 1i based on the following equation (5).

[0022] _{Q H = (V Hi -V H} ) / I H Q M = (V Mi -V M) / I M ... ( number _{5) Q L = (V Li} -V L) / I L above the current value I _H, I _M, performs the above operation every time any one of I _L is detected, it calculates either the replenishment amount of charge of the corresponding (number 5), performs replenishment charging accordingly. The above three kinds of replenishing the charge amount Q _H, Q _M, the Q _L calculated all, to a value obtained by adding them may be replenished amount of charge, or replenishment of charge by calculating only one either May be

Next, FIG. 8 is a diagram showing a third embodiment of the present invention. The present embodiment shows a configuration in which replenishment charging is actually performed, and replenishment charging is performed using regenerative power generation. In FIG. 8, reference numeral 18 denotes a regenerative power generation device, which corresponds to a drive motor and its control device in the case of an electric vehicle, for example. Reference numeral 19 denotes a regenerative power distribution circuit that distributes regenerative power sent from the regenerative power generator 18 to the main regenerative charging circuit 20 and the sub regenerative charging circuit 22. Main regenerative charging circuit 20
Is a circuit for uniformly charging the entire assembled battery 1. The power storage device 21 is a device that temporarily stores the regenerative power sent from the regenerative power distribution circuit 19, and is, for example, a storage battery or a large-capacity capacitor. The sub-regenerative charging circuit 22 is the power storage device 2
The power sent from 1 is sent to the AC power supply 15. The sub-regenerative charging circuit 22 may be configured to send DC power and be converted into AC power by the AC power supply 15, or may be converted into AC power by the sub-regenerative charging circuit 22 and directly converted into AC power. It may be configured to send to the vessels 14a to 14n. In this case, the AC power supply 15 is unnecessary. In addition, the same reference numerals as those in FIG. 1 indicate the same things. The load system (control device 2 and load 3) in FIG. 1 is omitted in the drawing.

The operation will be described below. For example, in the case of an electric vehicle, regenerative power generation occurs at the time of braking or decelerating the vehicle, and the duration is about several seconds to several tens of seconds. The regenerative power distribution circuit 19 distributes the regenerative power generated in the regenerative power generator 18 to, for example, about 80% of the main regenerative charging circuit and about 20% of the sub regenerative charging circuit. In the main regenerative charging circuit 20, each of the batteries 1a to 1n of the assembled battery 1 is commonly charged with the above 80% power. This corresponds to the basic charging described above. As described above, since the duration of regenerative power generation is about several seconds to several tens of seconds, the main regenerative charging circuit 20 charges the entire assembled battery 1 each time regenerative power generation is performed. Although not described in this embodiment, a circuit for preventing overcharge may be provided. As the overcharge prevention circuit, for example, a circuit that stops charging by the main regenerative charging circuit 20 when at least one battery in the assembled battery 1 reaches the end-of-charge voltage can be used. On the other hand, the power storage device 21 stores 20% of the electric power supplied every several seconds to several tens of seconds as described above, and stores several minutes to several minutes.
Output continuously for about 1 hour. Then, the sub regenerative charging circuit 22 and the AC power supply 15 supply the electric power of 4 to
Each battery is supplied to each charge control circuit composed of 14 elements to replenish each battery by an amount corresponding to the replenishment charge amount ΔQ calculated as described above. As described above, since the required replenishment charging is performed by using the regenerative electric power generated during the load driving (during discharge), the discharge capacity of each battery can be always kept uniform. It is possible to suppress deterioration of the battery and deterioration that occurs in a specific battery.

Next, FIG. 9 is a diagram showing a fourth embodiment of the present invention. In FIG. 9, 31 is a rectifying diode, 32
Is a capacitor, 33 is a coil, 34 is a Zener diode for preventing overvoltage, 35 is a resistor, 36 is a transformer, 37 is an AC power supply, 38 is a voltage detection circuit for detecting the voltage of each battery,
Reference numeral 39 is a control device, and 40 is a variable frequency oscillator. In addition, the same reference numerals as those in FIG. 1 indicate the same things. In the above circuit, the capacitor 32 and the coil 33 form a resonance circuit, and the charge control circuits (portions including 31 to 36) are set to have different resonance frequencies. For example, assuming that the resonance frequency of the charge control circuit connected to the battery 1a is ωa, the battery 1b is ωb, and the battery 1c is ωc, the power transmission rate of each charge control circuit is as shown in FIG. . Therefore, by changing the frequency of the electric power supplied from the AC power supply 37, it is possible to supply the electric power only to an arbitrary battery and charge it.

In the present embodiment, the voltage detection circuit 39 detects the voltage of each battery, the control device 39 determines which battery has the reduced voltage, and the variable frequency oscillator 40 generates the resonance frequency of the battery. . The AC power supply 37 is driven by the signal of this frequency to generate the AC power of the frequency. As a result, power is supplied only to the charge control circuit corresponding to the resonance frequency, and only the battery is selectively charged. With the above configuration, each battery can be selectively charged without using a means such as the current control element 9 shown in FIG. In a non-aqueous electrolyte secondary battery such as a lithium-ion battery, overcharging or overdischarging seriously affects the life of the battery as described above, and thus sufficient stability is desired for the operation of the charge control device. However, in the case of the present embodiment, current control is not performed by a single element such as the current control element 9, but the resonance frequency of the circuit is used, so stable control can be performed for a long period of time, and safety is improved. Is high. In particular, in a battery pack that has a large number of unit batteries and is not replaced for a long period of time, such as battery packs for electric vehicles and submarines, a highly stable control device like this embodiment is effective. is there.

Next, FIG. 11 shows a fifth embodiment of the present invention. In this embodiment, in the embodiment shown in FIG. 9, the coil 33 forming the resonance circuit is also used as the winding of the transformer 36. By doing so, the components can be omitted, the configuration can be simplified, and the size and cost can be reduced. Other functions and effects are similar to those of the embodiment shown in FIG.

[0028]

As described above, in the present invention, the supplementary charge amount is calculated for each cell or module, and the supplemental charge is performed accordingly, so that the discharge capacity of each cell or module is always maintained. Therefore, it is possible to obtain the effects that the discharge capacity of the entire battery pack can be increased and the deterioration of a specific battery can be suppressed, because the battery pack can be made uniform. In addition, in the case where the replenishment charging is performed by the regenerative charging, the replenishment charging can be performed between the load driving, so that the discharge capacity of each battery can be always kept uniform, and the discharge capacity can be reduced. It is possible to suppress deterioration that occurs in a specific battery. Also, in the case of using a resonance circuit to selectively charge, each battery can be selectively charged without using a current control element, so stable control can be performed for a long period of time. It is possible to obtain the effect of being highly safe.

[Brief description of drawings]

FIG. 1 is a diagram of a first embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining a method of calculating a supplementary charge amount ΔQr due to an increase in internal resistance.

FIG. 3 is a characteristic diagram for explaining a method of calculating a supplementary charge amount ΔQc due to a decrease in discharge capacity.

FIG. 4 is a characteristic diagram for explaining a method of calculating a supplementary charge amount ΔQd due to a lack of an initial charge amount.

FIG. 5 is a characteristic diagram showing a relationship between a discharge amount and an internal resistance value for explaining another method of calculating a supplementary charge amount.

FIG. 6 is a diagram of a second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing the relationship between the amount of discharge and the average voltage of cells.

FIG. 8 is a diagram showing a third embodiment of the present invention.

FIG. 9 is a diagram of a fourth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing the relationship between resonance frequency and transmittance.

FIG. 11 is a diagram showing a fifth embodiment of the present invention.

FIG. 12 is a characteristic diagram showing a charging current in a conventional example.

FIG. 13 is a characteristic diagram showing the relationship between discharge capacity and voltage.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Assembly battery 5 ... Current sensor 1a-1n ... Single battery 6 ... Arithmetic device 2 ... Control device 7 ... Memory 3 ... Load 8 ... Current control circuit 4 ... Voltage sensor 9 ... Current control element 10 ... Zener diode 15 ... AC power supply 11 ... Diode 16 ... Average voltage detection circuit 12 ... Resistor 17 ... Timing signal generation circuit 13 ... Resistor 18 ... Regenerative power generator 14 ... Transformer 19 ... Regenerative power distribution circuit 20 ... Main regenerative charging circuit 21 ... Power storage device 22 ... Sub regenerative device Charging circuit 35 ... Resistor 31 ... Diode 36 ... Transformer 32 ... Capacitor 37 ... AC power supply 33 ... Coil 38 ... Voltage detection circuit 34 ... Zener diode 39 ... Control device 40 ... Variable frequency oscillator 41 ... Resistor

Claims (8)

[Claims] 1. An assembled battery in which a plurality of cells each comprising one secondary battery or a module each comprising a plurality of cells are connected in series or series-parallel, and voltage detection means for detecting a voltage of the cells or modules, A current detecting means for detecting a current flowing through a cell or a module, a calculating means for calculating a charge amount to be replenished for each cell or each module based on the detected voltage value and current value, and an operation of the calculating means. A battery charger for an assembled battery, comprising: a control unit for selectively performing supplemental charging for each cell or each module according to a result. 2. The calculation means comprises a discharge capacity decrease ΔQr due to an increase in internal resistance and a discharge capacity decrease ΔQc due to deterioration.
2. The charging of the assembled battery according to claim 1, wherein the sum ΔQ = ΔQr + ΔQc + ΔQd of the discharge capacity decrease ΔQd due to the initial charge shortage is obtained and the ΔQ is set as the amount of charge to be replenished. apparatus. 3. The calculation means adds ΔQe to a charge amount ΔQe corresponding to a predetermined value or an internal resistance value for a battery having a particularly large internal resistance, and ΔQ.
The battery charger for an assembled battery according to claim 2, wherein + ΔQe is a charge amount to be replenished. 4. The calculation means comprises one cell or module at each of the plurality of current values obtained from the voltage of each cell or each module at each of a plurality of predetermined current values and the voltage of the entire assembled battery. 2. The battery pack charging apparatus according to claim 1, wherein the shortage electricity amount at the specified current value is calculated based on the average voltage of the above, and is used as the supplementary charge amount. 5. The deficiency in the specified current value is based on the voltage of each cell or module at a predetermined current value and the average voltage for one cell or module obtained from the voltage of the entire battery pack. Calculate the amount of electricity,
The battery charger for an assembled battery according to claim 1, wherein the charging amount is used as a supplementary charge amount. 6. When the load of the assembled battery is a driving device for a traveling vehicle, the supplementary charging is performed by regenerative charging performed during deceleration or braking of the traveling vehicle. 5. The assembled battery charging device according to any one of 5 above. 7. A resonance circuit, which is provided for each cell or each module, having a resonance frequency different from the others, and a rectifying circuit for rectifying the output thereof, and all the resonance circuits and rectifying circuits of the assembled battery. A variable frequency power source connected to the whole as a whole, and a frequency setting means for controlling the frequency of the variable frequency power source so as to match the resonance frequency of the resonance circuit of the cell or module requiring replenishment charging calculated by the arithmetic means. 7. The battery charger for an assembled battery according to claim 1, further comprising: and selectively replenishing and charging only cells or modules of the resonance circuit that resonates at the power supply frequency. 8. The battery pack charging apparatus according to claim 1, wherein the secondary battery is a non-aqueous electrolyte secondary battery.