JPH09182307A - Power distribution controller for battery pack - Google Patents

Abstract

(57) Abstract: Provided is a battery pack power distribution control device capable of increasing the usable discharge capacity of a battery pack as a whole and suppressing deterioration of a specific battery. An assembled battery in which a plurality of cells 10 or 11 each including one secondary battery or a plurality of cells are connected in series or series-parallel, and a bypass circuit in which each of the cells or modules is connected in parallel. (6 and 8 or 7
And 9), which controls the amount of charge to the cell or module by controlling the current flowing through the bypass circuit, the difference in the discharge capacity between the cells or modules during the regenerative charging state during discharging. A power distribution control device for an assembled battery configured to change the amount of bypass flowing to each of the bypass circuits according to the above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power distribution control device for an assembled battery that uses a plurality of secondary batteries connected in series or in series and parallel, and in particular, each battery when performing regenerative charging such as in an electric vehicle. To a device for distributing electric power to the.

[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 manufacturing variations between batteries, and because the temperature distribution when used in an assembled battery is not uniform, etc.
Since the self-discharge amount and the charge acceptance rate (charging / discharging efficiency) are different, the degree of decrease in the discharge capacity is different for each battery. Therefore, the discharge capacity from DOD (depth of discharge: 100% at full discharge, 0% at full charge) = 0% varies among the batteries, which reduces the discharge capacity of the assembled battery. 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 = 100%. The voltage drops before it becomes
As a battery pack, the discharge ends. In addition, at the end of battery discharge, deterioration due to increased internal resistance and increased internal heat generation, deterioration due to instability of battery materials, deterioration due to local flow of large current, etc. As the battery deteriorates, the battery in the over-discharged state has a greater degree of deterioration in life.

On the other hand, during charging, DOD = 10 during discharging.
Batteries that did not reach 0% first reached DOD = 0% and the voltage rose, and charging ended. However, batteries that were over-discharged during discharging did not reach DOD = 0% and charging ended. Therefore, the difference in DOD 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 a secondary battery, if it is overcharged beyond the end-of-charge voltage or overdischarged beyond the end-of-discharge voltage, the life will be shortened. When the final voltage was reached, it was usual to finish charging and discharging as an 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 vary, and the discharge capacity of the entire assembled battery is lowered, and that a particular battery is particularly deteriorated.

As a first conventional example for dealing with the above problem, there is one disclosed in Japanese Patent Laid-Open No. 61-206179. 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. Further, as a second conventional example, there is one described in Japanese Patent Laid-Open No. 5-64377. In this conventional example, among the batteries constituting the assembled battery,
It describes that even one battery stops charging when it reaches full charge, and that a battery that reaches full charge is provided with a circuit for bypassing the charging current.

[0005]

As described above, in the conventional charge protection device, the charging current of the fully charged battery (DOD = 0%) is bypassed, and the battery less than the fully charged battery is continuously charged. Therefore, it is possible to reduce the variation during charging. However, even if all the batteries are fully charged, as described above, there is a difference in the discharge capacities of the batteries when they are fully charged. The battery having a large discharge capacity remains discharged, and the battery pack ends discharging. Therefore, there remains a problem that the actually usable discharge capacity of the battery pack as a whole is lowered, or a battery having a small discharge capacity is over-discharged and deteriorated.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is possible to increase the discharge capacity that can be used as the whole assembled battery and to suppress the deterioration of a specific battery. It is an object of the present invention to provide an assembled battery power distribution controller.

[0007]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, according to the first aspect of the invention, the amount of bypass flowing through each bypass circuit is changed according to the difference in discharge capacity between cells or modules during the regenerative charging state during discharging.

Further, in the invention according to claim 2,
The bypass amount at the time of the next discharge is set according to the difference between the discharge capacity of the cell or module having the smallest discharge capacity measured at the current discharge and the discharge capacity of the cell or module.

Further, in the invention described in claim 3,
The discharge current integrated value IC, the regenerative current integrated value IR, and the bypass amount Bk are detected, the discharge electricity amount Ak 'is calculated from them, and the voltage Vkbef before the discharge and the voltage Vkaft after the discharge are used to obtain a voltage stored in advance. Based on the relationship with the discharge depth, the discharge depth DOD (Vkbef) before discharge and the discharge depth DOD (V
kaft), the discharge capacity Ak of the module at the time of the current discharge is calculated from them, and the bypass amount set value at the time of the next discharge is calculated using the calculated value.

Further, in the invention described in claim 4,
Difference between voltage Vk at the end of discharge and minimum voltage Vmin ΔVk = Vk
Additional bypass amount according to −Vmin ΔBk = K · ΔVk
By determining (K: constant) and adding it to the bypass amount set before the current discharge, the bypass amount at the next discharge is configured.

Further, in the invention according to claim 5,
When the voltage exceeds the predetermined upper limit value, the bypass circuit is forced to turn on regardless of the set bypass amount.
It is set to N so as to suppress an increase in voltage.

According to the invention of claim 6,
The temperature of the battery is measured, the correction coefficient at that temperature is read out based on the relationship between the capacity ratio and the temperature stored in advance, and the new bypass amount is obtained by multiplying the set bypass amount setting value by the above correction factor. It is configured to be the set value.

As described above, in the present invention, the bypass amount is determined according to the discharge capacity of each cell or module that constitutes the assembled battery, so that the regeneration is performed according to the difference in discharge capacity of each module. The amount of charge can be distributed. That is, the bypass amount in the next discharge cycle is set for each discharge, and when regenerative charging is performed during the next discharge, the regenerative power is bypassed until the regenerated electric amount becomes equal to the set bypass amount above. Then, the bypass is stopped from the batteries that are equal to each other and regenerative charging is performed.Therefore, the smaller the discharge capacity of the battery, the larger the regenerative charge amount, and the same discharge capacity including the regenerative amount for each battery. I can.

[0014]

According to the present invention, since the discharge capacities including the regenerative component can be made uniform for each of the batteries constituting the assembled battery, it is possible to eliminate the generation of energy that cannot be discharged due to the dispersion of the discharge capacities. In addition, it is possible to improve the distance traveled in one charge and to suppress deterioration of the battery due to over-discharge. Also, by bypassing the regenerative current of a battery with a large capacity, it is possible to suppress an increase in voltage and give more energy to a battery with a small capacity. The effect that can be obtained is obtained.

Further, according to the fifth aspect, it is possible to prevent the deterioration of the battery due to the overvoltage. Further, according to the sixth aspect, even when the capacity of the battery greatly changes depending on the temperature, accurate control can be performed and the above effects can be reliably obtained.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a circuit diagram showing an embodiment of the present invention, which is applied to an electric vehicle having a regenerative charging function. In FIG. 1, 10 and 11 are batteries constituting an assembled battery. As this battery, a cell composed of a single battery or a module composed of a plurality of cells can be used. As an example of the module, there is one in which six lead acid battery cells are connected in series and housed in one package. Note that, in FIG. 1, a case where only two batteries are used as an assembled battery is illustrated for convenience of illustration.
Practically many batteries are used. For example, in the case of an electric vehicle, several tens to several hundreds of cells or modules are connected and used.

Further, 1 is a current sensor for detecting the discharge current and charging current of the entire battery pack, 2 is a current sensor for detecting the discharge current and charging current of the battery 10, and 3 is a discharge current and charging current for the battery 11. It is a current sensor. Current sensor 1
The detection current I ₁ of the current detection current I ₂ of the sensor 2, the bypass circuit Ib ₂ the current flowing (and the switching element 8 resistor 6) of the battery 10, detects current I ₃ of the current sensor 3, the battery 11 Bypass circuit (switching element 9 and resistor 7)
If the current flowing through Ib ₃ is Ib ₃ , there is the following relationship. I ₁ = I ₂ + Ib ₂ = I ₃ + Ib _{3 Further} , 4 and 5 are voltage sensors for detecting the voltage of each battery. However, since the ground potential (terminal potential on the low potential side) of each battery is different in the assembled battery, these voltage sensors are isolated voltage sensors, such as an isolation amplifier (this output voltage is used as a battery controller). It is necessary to read the data in 12 and perform A / D conversion).

Further, 6 and 7 are resistors for consuming bypass power, and 8 and 9 are switching elements for controlling bypass current, for example, transistors. Further, reference numeral 12 is a battery controller composed of a microcomputer or the like, which inputs the detection result of each of the above-mentioned sensors and calculates a current integrated value, a bypass current integrated value, etc. A control signal is output to the switching elements 8 and 9 via the coupler 17 and the drive circuit 18. In addition, photo coupler 1
Since 5 and 17 have different potentials between the bypass circuits as in the above, they are used to transmit the control signal while being insulated from the battery. The battery controller 12 is provided with a map that stores the characteristics of the voltage and the depth of discharge shown in FIG. 7 described later and the characteristics for temperature correction shown in FIG. 14 described later.

Reference numerals 21 and 22 are temperature sensors for detecting the temperature of each battery (used in the fourth embodiment). Reference numeral 13 denotes an inverter, which converts the DC power of the battery pack into AC power to drive the motor 14, and converts the regenerative power of the motor 14 into DC power during braking to recharge the battery pack. is there. In addition to this, for example, a control circuit for controlling the electric power applied to the motor 14 according to the operation amount of the accelerator pedal and performing the regenerative charging during braking is necessary, but in FIG.
And is abbreviated.

Next, FIGS. 2 and 3 are concrete circuit diagrams of the bypass circuit. FIG. 2 uses a photocoupler 15 and a drive circuit 16, and FIG. 3 shows a D / A converter 19 and an isolator. The one using the amplification amplifier 20 is shown. FIG.
In the example, a PWM signal is used as a control signal from the battery controller 12, the photocoupler 15 transmits the PWM signal while insulating it from the battery itself, and then the switching element 8 via the drive circuit 16 including the resistor R and the capacitor C. Is controlled (details will be described later). In the example shown in FIG. 3, digital data is used as a control signal from the battery controller 12, the D / A converter 19 converts the digital data into an analog signal, and the isolation amplifier 20 insulates the battery from the battery itself for transmission. After that, the switching element 8 is controlled (details will be described later).

(First Embodiment) The operation of the first embodiment will be described below. In this embodiment, the bypass amount of the bypass circuit is set according to the capacity of each battery (cell or module) forming the assembled battery. Specifically, the capacity value of the battery having the smallest capacity and the battery concerned are set. The difference from the capacity value of is controlled to be the bypass amount of the bypass circuit connected to the battery.

FIGS. 5 and 6 are flowcharts showing the processing sequence in the first embodiment, and FIGS.
Are connected at the points marked with (A) and (B). First, in step S0 of FIG. 5, the initial capacity C of each module (the batteries 10 and 11 of FIG. 1 are shown. The same applies hereinafter).
k (1 ≦ k ≦ n: n is the number of modules) is set.
In the description below, the capacity means the discharge capacity. This initial capacity setting is required only at the first use.
That is, in the present embodiment, since the bypass amount of each module is set to be equal to the capacity difference of each module, it is necessary to obtain the capacity of each module for each discharge, but the second and subsequent discharges are performed. Sometimes the process of obtaining the capacity of each module after the end of the previous discharge (step S
Since 21) is performed and the value is used, the initial capacity may be set only for the first time. Therefore, the process starts from step S1 from the second time. It should be noted that the initial setting value in step S0 is accurate if the capacity test of each module is performed in advance and the value is used. However, the initial setting value is accurate from the second time, so the initial setting value is simply the rated value. All you have to do is enter. However, in this case, the capacities of all the modules are set to the same value, so that the effect of the present invention does not occur only during the first discharge.

Next, when the ignition switch of the electric vehicle is turned on, the control flow is started in step S1. Then, in step S2, the module number k
Set to = 1. Succeedingly, in a step S3, a bypass amount is set for the module. For this bypass amount, the smallest capacity of all modules is C
If min, the difference Bk (Bk = Ck-Cmin) between the capacity Ck of the module and the Cmin is set as the bypass amount set value of the module. Therefore, the bypass amount is 0 for the module having the minimum capacity.

Next, in step S4, the terminal voltage Vkbef of the module before discharge is measured. This value is used when calculating the capacity of each module in step S21 after the end of discharge. Next, in step S5, the module number k
Is equal to the number of modules n, and when they are not equal (when processing of all modules is not completed), k = k + 1 is set in step S6, and then steps S3 to
The process of S5 is repeated. When the processing of all the modules is completed, the process goes to step S7. Note that the above step S1
The processes of to S6 are started when the ignition switch is turned on, and are completed before the vehicle starts traveling.

In step S7, it is determined whether or not it is during regenerative charging while the vehicle is traveling. That is, the value of the current sensor 1 in FIG. 1 is monitored, and when the current flows from the assembled battery to the motor, it means that the motor is being driven (S7: No).
When the current flows from the motor to the assembled battery, the regenerative charging is being performed (S7: Yes), and the process proceeds to step S8. In step S8, the regenerative current integrated value IR is obtained, and in step S9, the module number k
To 1.

Next, in step S10, it is determined whether or not the bypass amount Bk of the module set in step S3 is larger than 0 (whether or not the bypass amount of the module remains), and No. In this case, the bypass circuit OFF signal is transmitted in step S11. If the bypass circuit is turned off, the bypassed power is 0
Then, the battery is fully regeneratively charged. When the bypass amount Bk is larger than 0, a signal for turning on the bypass circuit of the module is transmitted in step S12. This signal is a PWM signal (details will be described later).

Next, in step S13, the bypass amount Δ
Calculate Bk (amount bypassed). In this calculation method, first, the current sensor of the module (2 in FIG.
Or, from the value Ik of 3) and the value I of the current sensor 1, IBk is calculated by the following (Formula 1). IBk = I-Ik (Equation 1) Time Δ required for one cycle of the control flow to the above value IBk
By multiplying by t, the bypass amount ΔBk in that cycle can be obtained.

Next, in step S14, a value obtained by subtracting the bypass amount ΔBk obtained in step S13 from the bypass amount setting value Bk obtained so far is set as the bypass setting value in the next cycle. Next, in step S15, the module number k
Is equal to the number of modules n, and if they are not equal (when the processing of all modules is not completed), k = k + 1 is set in step S16, and then step S1
The processing from 0 to S15 is repeated. When the ON / OFF setting of the bypass circuit and the update of the bypass amount set value are completed for all modules, the process returns to step S7. As described above, the actually bypassed amount is sequentially subtracted from the initially set bypass amount setting value, and when the bypass amount becomes 0, the bypass circuit of the module is turned off and full regenerative charging is performed.

On the other hand, if it is determined in step S7 that it is not during regeneration, the process proceeds to step S17 in FIG. After obtaining the discharge current integrated value IC of the assembled battery in step S17,
In step S18, it is determined whether or not the discharge is finished. If the discharge is not finished, the process returns to step S7 in FIG. 5, and if it is finished, the process goes to step S19. It should be noted that the judgment of the end of discharge is made based on whether or not the voltage of the assembled battery has dropped to the discharge end voltage. Specifically, for example,
(1) When the assembled battery voltage (sum of each module voltage) drops to a predetermined set value (eg, 9.9 V × n in the case of a module in which six lead storage batteries are connected in series), (2) or one Even in the module, the voltage is the set value (for example, 9.
9V). When the above-mentioned setting (1) is made, the control is particularly effective for improving one-charge traveling distance, and when the setting is made as (2), the control is particularly effective for the life of the battery.

Next, in step S19, the module number k is set to 1, and in step S20, the voltage Vkaft of the module after the end of discharge is measured. In the storage battery immediately after discharge, the concentration of the electrolytic solution near the electrodes is particularly low, and it takes time for the concentration to become uniform throughout. As a phenomenon that can be seen from the outside, this corresponds to that the voltage drop due to the internal resistance during discharge does not rise immediately after the end of discharge but gradually rises and finally stabilizes after a while. That is, since the voltage immediately after discharge fluctuates, it is desirable to measure the voltage Vkaft at the end of discharge after a predetermined time has elapsed (for example, 10 minutes) after the end of discharge. However, in the case of charging immediately after discharging, measure the voltage immediately before charging.

Next, in step S21, the capacity Ak of the module is calculated. This calculation is performed as follows. First, the amount of discharged electricity Ak ′ discharged from the module is obtained. This discharge electricity amount Ak 'is determined in step S1.
From the discharge current integrated value IC obtained in step 7, the regenerative current integrated value IR obtained in step S8, and the bypass amount Bk, the following equation (2) is used. Ak '= IC- (IR-Bk) (Equation 2) That is, the discharge electricity amount Ak' is a value obtained by subtracting the regenerative charge amount (IR-Bk) from the discharge current integrated value IC.

Next, from the voltage Vkbef before discharge obtained in step S4 and the voltage Vkaft after discharge obtained in step S20, using the graph shown in FIG. 7, the depth of discharge DO before discharge is performed.
D (Vkbef) and the depth of discharge DOD (Vkaft) after discharge are obtained. Then, the capacity Ak of the module is calculated from the above values using the following (Equation 3).

[0033]

(Equation 3)

For example, when the voltage before discharge is 13 V and the voltage after discharge is 12 V, DOD ≈ before discharge from FIG.
10%, and DOD after discharge is approximately 72%. Then, if the discharge electricity quantity Ak '= 30Ah, then from the above equation (3), Ak
≈48.4 Ah.

Next, the capacity Ak calculated as described above is updated as the capacity Ck used in step S3 in the next calculation. Next, in step S23, the module number k
Is equal to the number of modules n, and if they are not equal (when the processing of all modules is not completed), k = k + 1 is set in step S24, and then step S2
The processing from 0 to S23 is repeated. When the next update of the capacity Ck is completed for all modules, step S25
The control flow ends with.

Steps S1 to S25 of the above control flow correspond to the period from the start of vehicle running after charging the assembled battery (to be exact, the ignition switch is ON) to the start of next charging. Therefore, when the traveling is interrupted during discharging and restarted without charging, the values before the interruption of traveling are used as they are as the set values, and the control flow starts from step S7.

Further, it is necessary to allow only part or all of the regenerative current to flow in the bypass circuit and control so that no current directly flows from the assembled battery. For that purpose, the control of the switching element of the bypass circuit must be a method capable of arbitrarily controlling the bypass current value, that is, an analog method, rather than mere digital ON / OFF control. A control for realizing this is shown in FIG.
FIG. 4 is a diagram showing PI control (proportional / integral control). If the battery controller 12 determines that the bypass circuit is ON, the regenerative current detected by the current sensors 2 and 3 in FIG. 1 becomes zero. , PI control is performed, and the signal is sent to the switching element (base signal in the case of a transistor) of the bypass circuit. Specifically, as shown in FIG. 3, the PI output from the battery controller 12 is output.
The control signal (digital signal) is converted into an analog signal by the D / A converter 19, and the analog signal is supplied to the isolation amplifier 2
It is given as a base signal of the transistor 8 via 0.
In this case, since the control signal is an analog signal, it is necessary to use an isolation amplifier instead of a photocoupler for insulation between circuits.

As described above, the battery controller 2
When a computer is used as 0, since a normal output is a digital signal, a D / A converter and an isolation amplifier are required. A circuit in which such a configuration is further simplified is the circuit shown in FIG. In FIG.
A PWM signal (digital signal) having a duty ratio proportional to the magnitude of the PI control output is sent from the battery controller 12 to drive the drive circuit 16 via the photocoupler 15. Capacitor C of drive circuit 16
Is charged through the resistor R while the signal is ON, and OFF
Since the current escapes to the transistor 8 during the period, the terminal voltage of the capacitor C (base voltage of the transistor 8) is PW.
It changes according to the duty ratio of the M signal. Since the drive circuit 16 operates as a simple D / A conversion circuit as described above, it becomes possible to control the bypass current arbitrarily by controlling the transistor 8 in an analog manner.

In any of the circuits shown in FIG. 2 and FIG. 3, when the regenerative current is too large to bypass all the regenerative currents, the output of the PI control is saturated and the switching elements are completely turned on. , Module terminal voltage V
A current (Ia = Va / Ra, Ib = Vb / Rb) determined by a and Vb and the bypass resistors Ra and Rb flows, and the remaining current flows to the module as a regenerative current.

As described above, in the first embodiment, since the bypass amount is determined according to the discharge capacity of each module, the regenerative charge amount is adjusted according to the difference in the discharge capacity of each module. Can be distributed. That is, the discharge capacity of each battery is estimated for each discharge, the difference from the minimum value is calculated for each battery, and the value is set as the bypass amount for the next discharge. If regenerative charging is performed during the next discharge, the regenerative power is bypassed until the amount of regenerated electricity becomes equal to the bypass amount set above, and the bypass is sequentially stopped from the batteries that have become equal to perform regenerative charging. Let me do it. Therefore, the smaller the discharge capacity of the battery, the larger the regenerative charge amount, and the discharge capacity including the regenerative amount can be made uniform for each of the batteries that make up the assembled battery. Can be eliminated,
It is possible to improve the distance traveled on one charge and to prevent deterioration of the battery due to over-discharge. Also, by bypassing the regenerative current of a large capacity battery,
Since the increase in voltage of the battery can be suppressed and more energy can be given to the battery having a small capacity, the charging distance can be further improved from this aspect.

(Second Embodiment) The operation of the second embodiment will be described below. Also in this embodiment, the bypass amount of the bypass circuit is set in accordance with the capacity of each battery (cell or module) forming the assembled battery. However, the bypass amount calculation method is different from that of the first embodiment. Is different. 8 and 9 are flowcharts showing the processing sequence in the second embodiment.
Are connected at the points marked with (C) and (D).

First, in FIG. 8, in step S0 ',
The bypass amount of each module k = 1 to n is set. This is the initial setting only for the first time. For example, the value of the initial setting is accurate if the capacity test of each module is performed in advance and the difference from the minimum capacity is used as the bypass amount. Since the value becomes the value, the default value may simply be input the rated value.

Further, steps S1, S3, S7 and S9-
Some parts of S12, S15, and S16 are described in a simplified manner, but the same reference numerals in FIG. 5 have the same contents. However, the actual bypass amount calculation and update processes in steps S13 'and S14' are different from those in FIG. That is, in step S13 ′, the regenerative current of the module is detected from the values of the current sensors 2 and 3 in FIG.
The bypass amount BIk actually bypassed by the bypass circuit of the module is obtained by obtaining and integrating the difference between that value and the entire regenerative current value detected by the current sensor 1. Then, in step S14 ', a value obtained by subtracting the above BIk from the previous setting value is obtained, and that value is updated as the bypass amount setting value in the next cycle.

If it is determined in step S7 that regeneration is not in progress, the voltage Vk (value before discharge completion) of each module is measured and stored in step S26, and then the process proceeds to step S27 in FIG. In step S27, it is determined whether or not the discharge is completed. If the discharge is not completed, the process returns to step S7 in FIG.
Go to 28. The judgment of the end of discharge is made in step S of FIG.
Similar to 18.

At step S28, the minimum voltage Vmin among the voltages of the respective modules obtained at step S26.
Is selected. Then, after setting the module number k to 1 in step S29, in step S30, step S
The difference ΔVk = Vk−Vmin between the voltage Vk of each module obtained in step 26 and the above-mentioned minimum voltage Vmin is calculated. Next, in step S31, the preset constant K is multiplied by the above-mentioned ΔVk to obtain the additional bypass amount ΔBk = K · ΔVk of the module at the time of the next discharge. Then, in step S32, the bypass amount additional amount Δ is added to the bypass amount Bk for the module set in step S0 ′ or S3 of FIG. 8 before the current discharge.
A value Bk '= Bk + ΔBk obtained by adding Bk is provisionally set as the bypass setting amount of the module at the time of the next discharge.

Next, in step S33, it is determined whether or not the module number k is equal to the module number n, and if they are not equal (when the processing of all modules is not completed).
In step S34, after setting k = k + 1, the processes of steps S30 to S33 are repeated. When the update of the temporary setting of the bypass amount is completed for all the modules, the process goes to step S35. In step S35, step S32
The minimum one of the bypass amounts set in step 1 is selected as the minimum temporary bypass amount Bmin '. Next, step S3
At 6, it is determined whether or not the minimum temporary bypass amount Bmin 'is 0. If the minimum temporary bypass amount Bmin' is 0, the temporary bypass amounts Bk 'for all the modules are set as the bypass amounts Bk at step S37.

On the other hand, if No in step S36,
After the module number k is set to 1 in step S38, a value obtained by subtracting the minimum temporary bypass amount Bmin 'from the temporary bypass amount Bk' of each module is updated as the next bypass amount set value Bk in step S39. The above processing is based on the following reasons. That is, when the minimum provisional bypass amount Bmin 'is not 0, the bypass circuits of all modules are turned on at the same time, which wastefully consumes regenerative energy. To avoid such a situation, Bmi
n'is subtracted from the provisional bypass setting value of each module.

Next, in step S40, it is determined whether or not the module number k is equal to the module number n, and if they are not equal (when the processing of all modules is not completed).
In step S41, after setting k = k + 1, the processes of steps S39 to S40 are repeated. When the next update of the bypass amount Bk is completed for all modules, the control flow ends in step S42.

As described above, in the second embodiment, the difference ΔV between the voltage Vk of each module and the minimum voltage Vmin.
Additional bypass amount ΔBk = K · Δ according to k = Vk−Vmin
By obtaining Vk and adding it to the bypass amount set before the current discharge, the bypass set amount for the next discharge is obtained.

(Third Embodiment) The operation of the third embodiment will be described below. In this embodiment, when the voltage of the battery (cell or module) becomes larger than the upper limit value, the bypass circuit is forcibly turned on to suppress the increase in voltage regardless of the set bypass amount. This is an example of configuration. 10 and 11 are flow charts showing the processing sequence in the third embodiment, and FIGS. 10 and 11 are connected at points designated by reference numerals (E) and (F).

First, in FIG. 10, steps S0 to S
The steps up to 9 are the same as the steps denoted by the same reference numerals in FIG. Next, in step S43, the voltage Vk of the module is measured, and in step S44, the value is larger than the upper limit value indicating the fully charged state (for example, 14.7 V in the case of a module with six lead storage batteries connected in series). Determine whether or not. If it is larger than the upper limit, step S
At 47, the bypass circuit is turned on (fully opened) to suppress the module voltage rise. Next, in step S48, the bypass amount ΔBk is calculated, and in step S49, the bypass amount set value Bk of the next cycle is updated. This content
This is similar to steps S13 and S14 of FIG.

On the other hand, if No in step S44 (when the voltage does not exceed the upper limit value), it is determined in step S45 whether the bypass amount set value Bk is larger than 0 (the bypass amount remains for the module. Whether or not) is determined, and if the result is Yes, the process goes to step S47 to perform the same process as above. If No in step S45, that is, if the bypass amount for the module does not remain, the bypass circuit is turned off in step S46 to perform regenerative charging.

Next, in step S50, it is determined whether or not the module number k is equal to the module number n, and if they are not equal (when the processing of all modules is not completed).
In step S51, k = k + 1 is set, and then steps S43 to S50 are repeated. When the processing of all the modules is completed, the process goes to step S52.

In step S52, the module number k is set to 1 again, and in step S53, the bypass setting value B
k is updated to Bk-Bkmin (Bkmin: minimum value of bypass setting amount). Then, in step S54, the module number k
Is equal to the number of modules n, and if they are not equal, in step S55, k = k + 1 is set, and then the processes of steps S53 to S54 are repeated. When all the modules have been processed, the process returns to step S7. The reason for performing the process of step S53 is as follows. That is, when the bypass set value Bk = 0, the bypass circuit is not normally turned on during the discharge, but since the module voltage exceeds the upper limit value, the above step S
When the bypass circuit is turned on by the processing of 44 and S47, the above-mentioned processing is performed because it is necessary to add the corresponding amount of electricity to all the modules. At this time, the minimum value Bkmin of the bypass setting amount is a negative value (step S4
In the calculation of Bk = current Bk−current Bk−ΔBk of 9, since the current module Bk = 0 of the smallest capacity, the next time Bk, that is, Bkmin becomes negative), so Bk−Bkmin
Effectively adds Bkmin to Bk. Note that steps S17 to S25 in FIG. 11 are the same as those in FIG.

As described above, in the present embodiment,
When the battery voltage exceeds the upper limit, the bypass circuit is forced to turn on regardless of the set bypass amount.
Since N is set to suppress the increase in voltage, deterioration of the battery due to overvoltage can be prevented. In addition,
The present embodiment exemplifies a case where the above configuration is combined with the first embodiment, but may be combined with the second embodiment.

(Fourth Embodiment) The operation of the fourth embodiment will be described below. In this embodiment, the temperature of each battery is measured, and from a temperature correction map prepared in advance,
By reading the correction coefficient at that temperature and multiplying the set bypass amount set value by the temperature correction coefficient to obtain a new bypass amount set value, the bypass amount is temperature-corrected. 12 and 13
12 is a flow chart showing the processing sequence in the fourth embodiment, and FIGS. 12 and 13 are connected at points marked with (G) and (H).

In FIG. 12, steps S0 to S16.
Is the same as the step denoted by the same reference numeral in FIG. 5, but is different from step S56 between step S2 and step S3.
And step S57 is inserted. The capacity Ck initially set in step S0 is set such that the battery temperature is a predetermined reference temperature (for example, 30 ° C.). In step S56,
The temperature Tkbef of the module is read from the value of the temperature sensor 21 or 22 shown in FIG. And step S5
At 7, the temperature of the capacitance is corrected. In this temperature correction, a correction coefficient (value on the vertical axis of FIG. 14) is read from a map (see FIG. 14) showing the relationship between the module capacity ratio and the module temperature built in the battery controller 12 of FIG. Is multiplied by Ck to calculate the temperature-corrected capacity Ck. Then, in step S3, the bypass setting value Bk is set by using the temperature-corrected capacity Ck. Other steps in FIG. 12 are the same as those in FIG.

Next, referring to FIG. 13, steps S17-.
S25 is the same as that of FIG. 6, but steps S19 and S
Steps S58 and S59 are inserted between 20 and
The difference is that step S60 is inserted between steps S22 and S23. First, in step S58, the module temperature Tkaft after the end of discharge is measured from the output of the temperature sensor 21 or 22 in FIG. Then, in step S59, the average value of the module temperature Tkbef before discharge and the module temperature Tkaft after the end of discharge calculated in step S56 of FIG. The module temperature is Tkav. Tkav = (Tkbef + Tkaft) / 2 (Equation 4) Next, in step S60, the capacity Ck of the module updated in step S22 is corrected according to the module temperature Tkav obtained in step S59. In the correction, the module capacity ratio at the module temperature Tkav is read from the map shown in FIG. 14 built in the battery controller 12, and is multiplied by the capacity Ck (actually, the reciprocal of the value on the vertical axis in FIG. 14). Then, the capacity at the reference temperature of 30 ° C. is calculated. Then, it is stored as the capacity Ck used in the next step S3. The other steps are the same as those in FIG.

As described above, in the present embodiment,
Since the bypass setting value is corrected according to the temperature of the battery at the time of discharging, accurate control is performed even when the capacity of the battery changes significantly according to the temperature, and the first embodiment It is possible to reliably obtain the effect described in (1). In addition, although the case where the above-described configuration is combined with the first embodiment is illustrated in the present embodiment, it may be combined with the second and third embodiments.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a circuit diagram showing details of part of FIG.

FIG. 3 is another circuit diagram showing details of a part of FIG.

FIG. 4 is a block diagram showing a PI control system.

FIG. 5 is a flowchart showing a part of the first embodiment of the present invention.

FIG. 6 is a flowchart showing another part of the first embodiment of the present invention.

FIG. 7 is a characteristic diagram showing the relationship between the battery voltage and the depth of discharge DOD.

FIG. 8 is a flowchart showing a part of a second embodiment of the present invention.

FIG. 9 is a flowchart showing another part of the second embodiment of the present invention.

FIG. 10 is a flowchart showing a part of a third embodiment of the present invention.

FIG. 11 is a flowchart showing another part of the third embodiment of the present invention.

FIG. 12 is a flowchart showing a part of a fourth embodiment of the present invention.

FIG. 13 is a flowchart showing another part of the fourth embodiment of the present invention.

FIG. 14 is a characteristic diagram showing a relationship between a module capacity ratio and a module temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Current sensor for detecting discharge current and charging current of entire battery pack 2, 3 ... Current sensor for detecting battery discharge current and charging current 4, 5 ... Voltage sensor for detecting battery voltage 6, 7 ... Resistor 8 , 9 ... Switching elements 10, 11 ... Batteries constituting assembled battery 12 ... Battery controller 13 ... Inverter 14 ... Motor 15, 17 ... Photo coupler 16, 18 ... Drive circuit 19 ... D / A converter 20 ... Isolation amplifier 21, 22 ... Temperature sensor for detecting battery temperature

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02J 7/00 302 H02J 7/00 302C 7/04 7/04 A

Claims (6)

[Claims] 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 a bypass circuit connected in parallel to each cell or module. In a device for controlling the amount of charge to the cell or module by controlling the current flowing through the bypass circuit, the bypasses according to the difference in discharge capacity of each cell or module in a regenerative charging state during discharging. An assembled battery power distribution control device characterized in that it is configured to change the amount of bypass flowing into the circuit. 2. The bypass amount for the next discharge is set according to the difference between the discharge capacity of the cell or module having the smallest discharge capacity measured at the current discharge and the discharge amount of the cell or module. Claim 1
A battery pack power distribution control device according to. 3. A regenerative charge amount (IR−) obtained by detecting a discharge current integrated value IC, a regenerative current integrated value IR and a bypass amount Bk for each cell or module and subtracting the bypass amount Bk from the regenerative current integrated value IR. Bk) is calculated and subtracted from the discharge current integrated value IC to calculate the discharge electricity amount Ak ′ discharged from the module, and the voltage Vkbef before discharge and the voltage Vkaft after discharge for each cell or module are calculated.
From the above, the discharge depth DOD (Vkbef) before discharge and the discharge depth DOD (Vkaft) after discharge are obtained based on the relationship between the voltage and the discharge depth stored in advance, and in the current discharge cycle, the following formula is used. 3. The battery pack power distribution control device according to claim 1, wherein the discharge capacity Ak of the module is calculated, and the bypass amount set value for the next discharge is calculated using the calculated discharge capacity Ak. Ak = Ak '× 100 / [DOD (Vkaft) -DOD (V
kbef)) 4. A bypass amount additional amount ΔBk = K · ΔVk (K according to a difference ΔVk = Vk−Vmin between a voltage Vk of each cell or module at the end of discharge and a voltage Vmin of a cell or module having the lowest voltage. : Constant) and add it to the bypass amount set before this discharge,
The assembled battery power distribution control device according to claim 1 or 2, wherein the bypass amount is set at the time of the next discharge. 5. When the voltage of each cell or module exceeds a predetermined upper limit value, the bypass circuit is forcibly turned on to suppress the increase in voltage regardless of the set bypass amount. The assembled battery power distribution control device according to any one of claims 1 to 4, which is configured. 6. The temperature of each cell or module is measured,
A correction coefficient at that temperature is read out based on the relationship between the capacity ratio and the temperature stored in advance, and a new bypass quantity setting value is obtained by multiplying the set bypass quantity setting value by the correction coefficient. The assembled battery power distribution control device according to any one of claims 1 to 5, characterized in that.