JPH11136875A - Battery management device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a decline of performances and operation lives of batteries even if a plurality of battery modules are connected in parallel to each other. SOLUTION: A battery module 5a is composed of a plurality of cells which are connected in series to each other. A battery assembly 5 composed of a plurality of battery modules 5a which are connected in parallel to each other, temperature detecting means 22 which detect the battery temperatures of the respective battery modules 5a, and a charger 4 which charges the battery assembly 5, are provided. Further a charger control means 23 which controls the charger 4 in accordance with the battery temperatures detected by the temperature detecting means 22. The charger control means 23 starts charging when the temperatures of all the battery modules 5a are within a predetermined charge starting temperature range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery management device for controlling charging and discharging of a battery assembly having a plurality of battery modules connected in parallel.

[0002]

2. Description of the Related Art Conventionally, a battery used for an electric vehicle such as an electric bicycle or an electric wheelchair is formed by connecting a plurality of cell-type batteries in series, and is stored in a battery case and attached to the body of the electric vehicle. I have it. The battery case is detachable from the vehicle body of the electric vehicle so that the battery case can be charged at a location different from the vehicle body or can be replaced with a spare battery when going out.

Further, it is required that a battery used in this type of electric vehicle has a large battery capacity so that the vehicle can travel as long as possible with a single charge.

[0004]

However, in order to increase the energy amount of the battery while adopting a configuration in which the battery cells are connected in series, the number of batteries connected in series may be increased. The voltage between terminals of the case becomes too high, and in the portable battery case used for the electric vehicle as described above, there is a risk of electric shock when a finger touches the terminal, a short circuit of the terminal, and the like.

[0005] Even in a configuration in which battery cells are connected in series, the capacity can be increased without increasing the voltage by selecting a cell having a large capacity. However, in some cases, a cell that meets the required performance of the vehicle cannot be found from among the standardized cells. In that case, a new cell must be manufactured, resulting in an increase in cost.

[0006] The inventors have considered that a battery module is formed by connecting mass-produced battery cells in series, and a plurality of battery modules are connected in parallel. By adopting this configuration, it is possible to increase the battery capacity while solving problems such as electric shock, short circuit, and cost increase.

However, if a configuration in which a plurality of battery modules are connected in parallel as described above is employed, there arises a problem that performance and life are affected when charging or discharging. This is because the capacities of the battery cells differ from one another, and the capacities of the battery modules formed by connecting a plurality of the battery cells in series also differ from one another. That is, when a plurality of battery modules having different capacities are connected and used in parallel, a temperature difference occurs between the battery modules during charging and discharging.

[0008] On the other hand, a battery has a temperature at which charging can be performed (hereinafter referred to as a guaranteed charging temperature). If the battery is charged at a temperature outside the range of the guaranteed charging temperature, the performance is reduced and the life is shortened. is there. Further, when discharging a battery that has become extremely low in temperature, there is a characteristic that the battery voltage drops significantly and the battery capacity cannot be sufficiently taken out. Since a temperature difference occurs between the respective battery modules at the time of charging and discharging, there has been a problem in that charging or discharging can be performed while satisfying the above-described conditions.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and employs a configuration in which a plurality of battery modules are connected in parallel, and performs charging and discharging so that performance is not deteriorated and life is not shortened. It is an object of the present invention to provide a battery management device that can be implemented.

[0010]

A battery management device according to the present invention comprises a battery assembly formed by connecting a plurality of battery modules formed by connecting a plurality of cells in series, and a battery for each battery module. Temperature detection means for detecting a temperature, a charger for charging the battery assembly, and charger control means for controlling the charger in accordance with the battery temperature, wherein the temperature of all the battery modules is set to a predetermined value. The charger control means is configured to start charging when the temperature is within a temperature range.

According to the present invention, charging can be started in a state where the temperatures of all the battery modules are within the guaranteed charging temperature range.

[0012] A battery management device according to another aspect of the present invention includes:
In the battery management device according to the above-described invention, the charger control means is configured to terminate charging when at least one of the plurality of battery modules satisfies a condition for determining termination of charging. According to the present invention, all the battery modules can be charged so as not to be overcharged.

[0013] A battery management device according to another aspect of the present invention includes:
A battery assembly formed by connecting a plurality of battery modules formed by connecting a plurality of cells in series, a battery assembly formed by connecting a plurality of cells in parallel, temperature detection means for detecting a battery temperature for each battery, and discharge control for controlling a discharge current of the battery assembly Means, and the discharge control means,
When the minimum value or the average value of the battery temperatures of all the battery modules is lower than a predetermined temperature, the upper limit value of the discharge current is set relatively small.

According to the present invention, when the minimum value or the average value of the battery temperature is lower than a predetermined temperature, the battery temperature can be increased while reducing the load on the battery. The capacity can be fully utilized.

According to another aspect of the present invention, there is provided a battery management device comprising:
A battery assembly formed by connecting a plurality of battery modules formed by connecting a plurality of cells in series, a battery assembly formed by connecting a plurality of cells in parallel, temperature detection means for detecting a battery temperature for each battery, and discharge control for controlling a discharge current of the battery assembly Means, and the discharge control means,
When the minimum or average value of the battery temperatures of all the battery modules is lower than a predetermined temperature, the discharge end voltage is set relatively low.

According to the present invention, when the minimum value or the average value of the battery temperature is lower than the predetermined temperature, the battery voltage decreases as compared with the case where the minimum value or the average value of the battery temperature is higher than the predetermined temperature. Can also supply power to the load side, so that the capacity of the battery can be fully utilized even in a low temperature environment.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment Hereinafter, an embodiment of a battery management device according to the present invention will be described in detail with reference to FIGS. 1 is a block diagram showing a configuration of a battery management device according to the present invention, FIG. 2 is a block diagram showing a configuration inside a battery case, and FIGS. 3 and 4 are diagrams for explaining an operation of the battery management device during charging. 3 shows an operation before the start of charging, and FIG. 4 shows an operation at the end of charging. FIG. 5 is a flowchart for explaining the operation of the battery management device at the time of discharging, and FIG. 6 is a graph serving as a map for setting a discharging current.

In these figures, reference numeral 1 denotes a battery management device according to this embodiment. The management device 1 manages charging and discharging of a battery of an electric vehicle such as an electric bicycle or an electric wheelchair, and includes a CPU 3 housed in a battery case 2, a charger 4, and the like. The battery case 2 houses a battery assembly 5 and is formed so as to be detachable from a battery mounting portion of an electric vehicle (not shown) and a battery connecting portion (not shown) of the charger 4.

The battery assembly 5 is constructed by connecting a plurality of battery modules 5a formed by connecting a plurality of cells of a nickel-metal hydride battery in series, and has a capacity even if the terminal voltage is the same as that of the conventional battery module. I'm trying to get more. Terminals 6 and 7 are connected to the positive and negative electrodes of the battery assembly 5. These terminals 6 and 7 are connected to the charger 4 at the time of charging, and are connected to the motor control unit 8 of the electric vehicle at the time of discharging.
The terminals 6 and 7 have a structure in which the contacts come into contact with each other when the battery case 2 is mounted on the charger 4 or the electric vehicle, and the terminals 6 and 7 are electrically connected. A display device 9 connected to the motor control unit 8 is for displaying the remaining capacity of the battery assembly 5 during traveling, and is disposed on the body of the electric vehicle at a position that is easy for a driver to see.

The battery case 2 has a thermistor 10 for detecting the temperature of the battery module 5a, a current detecting means 11 for detecting a current flowing through the battery assembly 5 during charging and discharging, and a A voltage detecting means 12 for detecting a voltage between terminals and a display device 13 with a switch for displaying the remaining capacity of the battery assembly 5 are provided. The thermistor 10 is connected to each battery module 5
a so that the battery temperature can be detected for each battery module 5a.

As shown in FIG. 2, the CPU 3 is connected to the charger 4 or the motor control unit 8 of the electric vehicle via a communication interface 14 and signal terminals 15 and 16. The terminals 15, 16 are also the terminals 6,
As in 7, a contact type is used.

As shown in FIG. 2, the CPU 3 comprises: a remaining capacity calculating means 21 for calculating the remaining capacity of the battery assembly 5; a temperature detecting means 22 for detecting the temperature of the battery module 5a; Charger control means 23 for setting output, charge stop means 24 for stopping charging, discharge control means 25 for refreshing battery assembly 5, and determination of connection of charger 4 Connection determination means 26 for performing
And charging time calculating means 27 for obtaining the longest charging time
And so on. The CPU 3 is connected to the battery assembly 5 via a power supply circuit 28 so that power is supplied from the battery assembly 5.

The remaining capacity calculating means 21 is configured to calculate the integrated value of the current detected by the current detecting means 11, that is, the remaining capacity of the battery assembly 5 from addition / subtraction of the current flowing during charging / discharging. . The obtained remaining capacity is stored in a memory (not shown). The temperature detecting means 22 is configured to detect the temperature of the battery module 5a based on the output of the thermistor 10.

The charger control means 23 sets a charging current based on the remaining capacity of the battery assembly 5 obtained by the remaining capacity calculating means 21 and the battery temperature obtained by the temperature detecting means 22. As a charge instruction signal to the charger 4 via the communication interface 14.
Is transmitted via the Internet. The charging current is set by a map (not shown).

The map is formed by allocating the charging current to the remaining capacity of the battery assembly 5 and the battery temperature at the start of charging, and the average value of the temperatures of all the battery modules a at the start of charging is, for example, a predetermined temperature. When the temperature is higher, the charging current decreases as the temperature increases and as the remaining capacity increases.

The charger control means 23 transmits the charging instruction signal to the charger 4 only when all the battery temperatures of the plurality of battery modules 5a are within a predetermined charging start temperature range. I am taking it.

The charge stopping means 24 is a specific phenomenon that occurs at the end of charging when the battery temperature reaches a predetermined charging stop temperature, when the battery voltage reaches a predetermined charging stop voltage, or when charging at a constant current. Is detected, a charging stop signal is transmitted to the charger 4 via the communication interface 14. Specific phenomena occurring at the end of charging include, for example, a phenomenon in which the battery voltage decreases at the end of charging and a phenomenon in which the rate of increase in the battery temperature increases significantly. The voltage drop is detected by the voltage drop amount calculating means 29 connected to the voltage detecting means 12, and the temperature rise rate is obtained by the temperature rise rate calculating means 30. In this embodiment, charging is stopped when at least one of the battery modules 5a satisfies the above conditions (charging stop temperature, temperature rise rate).

The connection determining means 26 sends a signal for connection determination to the charger 4 and determines whether or not the battery case 2 is connected to the charger 4. When a signal indicating the connection confirmation is returned from the charger 4, it is determined that the battery is connected to the charger 4. Further, the connection determination means 26 executes the connection confirmation, thereby making the CPU 3
It is also possible to determine whether there is an abnormality in the signal transmission means between the battery and the charger 4.

The charging time calculating means 27 calculates a maximum charging time (hereinafter referred to as a total Value), and the total timer value is sent to the charger 4 together with the charge instruction signal as a charge control signal.
In this embodiment, the charging time is calculated by the charging time calculating means 27 and the charger 4 respectively. That is,
The charging time calculating means 27 outputs a charging stop signal to the charger 4 when the elapsed time after the start of charging exceeds the total timer value.
When the elapsed time from the start of charging exceeds the total timer value, the charger 4 stops itself even if a charge stop signal is not sent from the battery case 2. More specifically, the total timer value is sent to the charger 4 together with the charge instruction signal as a charge control signal, so that the charger 4 also measures the elapsed time from the start of charging, and when the total timer value is exceeded. Even if the charge stop signal is not sent from the battery case 2, the charger 4 stops itself. The elapsed time is measured by a timer 31 and a timer 40 of the charger 4 described later. The total timer value is obtained by the following equation (1). {(Battery capacity−remaining capacity) / charging current} × constant (1) Here, the value recorded in the EEPROM 32 is used as the battery capacity.

The discharge control means 25 includes the battery case 2
When the battery case 2 is mounted on the charger 4 and the switch of the display device 13 with a switch is turned on, a refresh start signal is sent to the charger 4 while the battery case 2 is mounted on the charger 4. It is configured to send. The discharge current is set according to the map shown in FIG.

That is, the discharge control means 25 limits the discharge current to the discharge limit B when the lowest temperature among all the battery modules 5a (hereinafter, this temperature is referred to as the lowest battery module temperature) is lower than -10 ° C. When the minimum battery module temperature is in the range of -10 ° C to -5 ° C, the discharge current is set to the discharge limit A. When the minimum battery module temperature is higher than -5 ° C, the discharge current is set to the maximum allowable discharge value. It is configured to be set. Note that an average value of the temperatures of all the battery modules 5a can be used instead of the minimum battery module temperature. When the discharge current is set to the discharge limit A or the discharge limit B, the discharge control unit 25 uses the discharge limit A or the discharge limit B as a discharge control signal and sets the motor control unit 8.
To send to. The motor control unit 8 controls the output based on the discharge control signal.

The refresh is performed by discharging the battery assembly 5 with the charger 4.
The discharge control means 25 sends a refresh stop signal to the charger 4 when the voltage between the terminals of the battery assembly 5 reaches a predetermined refresh end value at the time of refresh.

As shown in FIG. 1, the charger 4 converts AC power supplied from an outlet plug 33 into DC by an AC / DC converter 34, and supplies the DC to the charging terminal 6 as a charging current. I have. Also, this charger 4
The receiving means 35, the comparing / calculating means 36, and the output controlling means 37 for passing the charging current set by the CPU 3
And a discharger 38 for refreshing the battery assembly 5.
And a discharge control means 39 for controlling the power supply 8.

The receiving means 35 receives the signal C via the signal terminal 15.
It is provided for receiving a signal from the PU 3 or transmitting a signal to the CPU 3, and is configured to receive a charge instruction signal and a charge stop signal and transmit these signals to the comparison / calculation signal 36. The elapsed time (charging time) after the start of charging is measured by the timer 40, and a charging stop signal is sent to the comparing / calculating means 36 when the charging time exceeds the total timer value sent from the CPU 3. I have.
The self-stopping means according to the present invention is constituted by the receiving means 35 in this embodiment. Further, the receiving means 35 has a reply means 41 for sending a signal indicating connection confirmation to the CPU 3 when receiving the signal for connection determination sent by the CPU 3.

Further, the receiving means 35 includes a CPU
3 receives the refresh start signal or the refresh stop signal transmitted by the discharge control means 39.
To be sent to. Battery assembly 5
Is started by the discharge control means 39 sending a discharge start signal to the discharger 38, and is ended by sending the discharge stop signal. At the time of refreshing, the receiving means 35 sends a charge stop signal to the comparing / calculating means 36. In FIG. 1, an LED 42 connected to the receiving means 35 is an LE for lighting the LED 43 at the time of charging or refreshing.
D driver.

The comparing / calculating means 36 includes the receiving means 35
A target charging current is determined from the charging instruction signal transmitted by the DC / DC converter, and based on the outputs of the current detecting means 44 and the voltage detecting means 45 provided on the downstream side of the AC / DC converter 34, the charging current matches the target charging current. The output control means 37 is configured to perform feedback control. The output control means 37 controls the output of the AC / DC converter 34 according to the control signal sent from the comparison / calculation means 36.

Next, the operation of the battery management device 1 configured as described above will be described with reference to the flowcharts shown in FIGS. First, the operation during charging will be described with reference to FIGS. CPU 3 in battery case 2
Determines whether the charger 4 is connected as shown in step 101 of FIG. In this determination, the connection determination means 26 sends a connection determination signal to the charger 4 and the charger 4
This is performed by detecting whether or not returns a connection confirmation signal.

When the battery case 2 is mounted on the charger 4, a signal for connection confirmation is returned from the charger 4, so that the connection is determined in step 101, and the process proceeds to step 102. In step 102, the CPU 3 determines whether or not the battery voltage has dropped significantly. In this embodiment, when the battery voltage is 16 V or lower, the process proceeds to step 103, and when the battery voltage is higher than 16 V, the process proceeds to step 104. In step 103, time measurement is started using the timer 31 as a pre-charge timer, and pre-charge is performed. This preliminary charging is performed until the battery voltage becomes 16 V or more in step 105. If the pre-charge time exceeds the predetermined pre-charge timer value, the process proceeds from step 106 to step 107, where
43 is lit so that an abnormal state can be determined.

In step 104, of the plurality of battery modules 5a, the first battery module 5a
The charger control means 23 of the CPU 3 determines whether or not the temperature is within a range of a predetermined charging start temperature. The temperature range is set to 0 ° C. to 40 ° C. in this embodiment. If the temperature of the first battery module 5a is not within this temperature range, the process proceeds to step 108,
After waiting for a predetermined time for charging, the process returns to step 104. When the temperature of the first battery module 5a is within the above-mentioned temperature range, as shown in steps 109 to 110, the same determination as in step 104 is performed on all the second and subsequent battery modules 5a.

Then, all the battery modules 5a
When the temperature is within the above temperature range, the CPU 3
Sets the total timer value and the charging current in step 111, checks whether the communication function is normal in step 112, and sends the charging current and the total timer value to the charger 4 in step 113. When the charger 4 receives these signals, the charger 4 starts charging as shown in step 114 of FIG.

After the start of charging, as shown in step 115, the CPU 3 determines whether or not the battery voltage has reached the charging stop voltage. In this embodiment, the charging stop voltage is set to 40V. If the battery voltage has not reached the charge stop voltage, the process proceeds to step 116, and if the battery voltage has reached the charge stop voltage, step 1 is performed.
Proceeding to 17, the CPU 3 sends a charging stop signal to the charger 4.

In step 116, the CPU 3 determines whether or not the temperature of the first battery module 5a has reached the charging stop temperature. In this embodiment, the charging stop temperature is set to 50 ° C. If the result of this determination is NO, it is determined whether or not the battery temperature has reached the charging stop temperature for all the second and subsequent battery modules 5a as shown in steps 118 and 119. Step 1
If YES is determined in any one of 16, 118 and 119, that is, if the battery temperature has reached the charging stop temperature even in one of the plurality of battery modules 5a, the process proceeds to step 117 to stop charging. I do.

If the temperatures of all the battery modules 5a have not reached the charging stop temperature, the CPU 3 determines in step 120 whether or not a phenomenon in which the temperature rise rate at the end of charging increases in the first battery module 5a. . If the above phenomenon is detected, the process proceeds to step 117 to stop charging. If the above phenomenon is not detected, the detection of the phenomenon is performed on all the second and subsequent battery modules 5a as shown in steps 121 and 122. Is determined. When the above-mentioned phenomenon occurs in at least one of the plurality of battery modules 5a, the CPU 3 stops charging, and when the above-mentioned phenomenon does not occur in all the battery modules 5a, the CPU 3 proceeds to step 123 to decrease the voltage. Is detected.

If a voltage drop has occurred, the process proceeds to step 117 to stop charging. If a voltage drop has not occurred, the process proceeds to step 124 to determine whether or not the charging time has reached the total timer value. judge. Step 1
If NO is determined in step 24, that is, if the charging time has not reached the total timer value, step 11
Returning to step 5, if YES is determined in step 124, the process proceeds to step 117 to stop charging.

At the time of discharging, a discharging signal is input to the CPU 3 as shown in step 201 of FIG. This discharge signal is sent by the motor control unit 8. Upon receiving the discharge signal, the CPU 3 detects the temperatures of all the battery modules 5a in step 202, and
To detect the minimum battery module temperature (Tmin). Then, in step 204, it is determined whether or not the minimum battery module temperature is lower than -5C. NO here
When the determination is YES, the process returns to step 202, and when the determination is YES, the process proceeds to step 205, where the CPU 3 determines whether or not the minimum battery module temperature is lower than −10 ° C.

If NO is determined in step 205,
That is, if the minimum battery module temperature is higher than −10 ° C. and lower than −5 ° C., the CPU 3 proceeds to step 20.
In step 6, the discharge current is set to the discharge limit A. In step 207, a discharge control signal is sent to the motor control unit 8. Then, at step 208, the minimum battery module temperature is -5 ° C.
It is determined whether it is higher. If the minimum battery module temperature is higher than −5 ° C., the CPU 3 sends a restriction release signal to the motor control unit 8 as shown in step 209, and returns to step 202. If NO is determined in step 208, that is, if the minimum battery module temperature is lower than −5 ° C., the process proceeds to step 205.

If it is determined in step 205 that the minimum battery module temperature is lower than -10.degree.
U3 sets the discharge current to discharge limit B in step 210, and sends a discharge control signal to the motor control unit 8 in step 211. Then, the process returns to step 205. As described above, when the minimum battery module temperature is lower than −5 ° C., the upper limit value of the discharge current is set to the discharge limit A or the discharge limit B so as to be relatively small, so that the load of the battery assembly 5 can be reduced in a low temperature environment. And lightly discharge the battery to increase the battery temperature (the temperature of each battery module 5a).

Therefore, this battery management device 1
Starts charging when the temperature of all battery modules 5a is within a predetermined charging start temperature range, so that charging is performed in a state where the temperature of all battery modules 5a is within the guaranteed charging temperature range. You can start. Therefore, all the battery modules 5a can be charged without lowering the battery performance or shortening the life.

Further, since the battery management device 1 adopts a configuration in which charging is terminated when at least one of the plurality of battery modules 5a satisfies the condition for judging termination of charging, all the battery modules 5a
a can be charged so as not to be overcharged.

Further, the battery management device 1 includes:
When the minimum value of the temperature of all the battery modules 5a (minimum battery module temperature) is lower than a predetermined temperature, the upper limit value of the discharge current is set relatively small. When the temperature is lower than the predetermined temperature, the battery temperature can be increased while reducing the load on the battery assembly 5, so that the capacity of the battery assembly 5 can be sufficiently utilized even in a low-temperature environment. That is, in addition to being able to increase the capacity by connecting a plurality of battery assemblies 5 in parallel, the cruising distance of the electric vehicle equipped with the battery management device 1 can be increased.

Second Embodiment A battery management apparatus according to another invention for changing the discharge end voltage will be described in detail with reference to FIGS. In addition,
The battery management device according to the present invention has the same configuration as that of the first embodiment except that the configuration of the discharge control means is different. Therefore, in this embodiment, when describing the hardware, FIGS.
Are used.

FIG. 7 is a flowchart for explaining the operation of the battery management device according to another invention at the time of discharging, and FIG. 8 is a graph serving as a map for setting the discharge end voltage. The discharge control means 25 of the battery management device 1 according to this embodiment has a configuration in which the discharge end voltage is set relatively low when the minimum battery module temperature (Tmin) is lower than a predetermined temperature during discharging. The discharge end voltage is a minimum voltage at which the discharge of the battery assembly 5 is stopped. In this embodiment, the discharge end voltage changes in three stages based on the map shown in FIG.

The discharge control means 25 selects the discharge end voltage B (minimum value) when the minimum battery temperature is lower than -10.degree. C., and the minimum battery temperature is higher than -10.degree.
When the battery temperature is lower, the discharge end voltage A (intermediate value) is selected, and when the minimum battery temperature is higher than −5 ° C., the normal discharge end voltage (maximum value) is selected. The discharge control means 25 is configured to transmit the set discharge end voltage to the motor control unit 8 as a discharge control signal.

The operation of the battery management apparatus 1 having the discharge control means 25 having the above-described structure at the time of discharging will be described with reference to the flowchart of FIG. After a discharge signal is input to the CPU 3 during discharging as shown in step 301 of FIG. 7, the CPU 3 detects the temperatures of all the battery modules 5a in step 302, and detects the minimum battery module temperature (Tmin) in step 303. I do. Then, in step 304, it is determined whether or not the minimum battery module temperature is lower than -5C. If the determination is NO here, the process returns to step 302, and if the determination is YES, the process proceeds to step 305, and the CPU 3 determines whether the minimum battery module temperature is lower than -10C.

If NO is determined in step 305,
That is, if the minimum battery module temperature is higher than −10 ° C. and lower than −5 ° C., the CPU 3 proceeds to step 30.
In step 6, the discharge end voltage is set to the discharge end voltage A. In step 307, a discharge control signal is sent to the motor control unit 8. Then, in step 308, it is determined whether or not the minimum battery module temperature is higher than -5C. If the minimum battery module temperature is higher than -5C, step 30
As shown by 9, the CPU 3 sends a restriction release signal to the motor control unit 8 and returns to step 302. If NO is determined in step 308, that is, if the minimum battery module temperature is lower than −5 ° C., the process proceeds to step 305.

If it is determined in step 305 that the minimum battery module temperature is lower than -10.degree.
U3 sets the discharge end voltage to the discharge end voltage B in step 310.
, And a discharge control signal is sent to the motor control unit 8 in step 311. Then, the process returns to step 305.

Accordingly, when the minimum battery module temperature is lower than −5 ° C., the discharge end voltage is set to the discharge end voltage A or the discharge end voltage B to be relatively small, so that the minimum battery module temperature is −5 ° C. Power can be supplied to the motor control unit 8 even when the battery voltage is lower than when the battery voltage is higher. For this reason, even in a low temperature environment, the battery capacity can be fully utilized,
Along with being able to increase the capacity by connecting a plurality of battery modules 5a in parallel, the cruising distance of the electric vehicle equipped with the battery management device 1 can be extended.

The end-of-discharge voltage can be changed steplessly according to the minimum battery module temperature as shown in FIGS. FIG. 9 is a flowchart showing the operation of the battery management device when adopting a configuration in which the discharge end voltage is changed steplessly. FIG. 10 is a graph showing a change in the discharge end voltage. FIG. 11 is a discharge end voltage in a small current range. 5 is a graph showing a map for setting a discharge termination voltage in a large current region.

When this embodiment is adopted, the discharge end voltage C in the small current region IA shown in FIG.
Is set by reading from the map shown in FIG. The map of FIG. 11 is formed so that the discharge end voltages C and D are determined according to the minimum battery module temperature. That is, when the minimum battery module temperature is lower than −10 ° C. or higher than 0 ° C., the discharge end voltages C and D in the small current region IA and the large current region IB are both constant irrespective of the battery temperature. When the battery module temperature is in the range of −10 ° C. to 0 ° C., the discharge end voltages C and D both increase steplessly as the battery temperature increases.

In such a configuration, the CPU 3 detects the temperatures of all the battery modules 5a in step 402 after the discharge signal is input in step 401 of FIG. ) Is detected. Then, in step 404, the CPU 3 reads out the discharge end voltages C and D corresponding to the lowest battery module temperature from the map shown in FIG. 11, and sends the voltage data to the motor control unit 8 as a discharge control signal.

When the discharge control signal is received, the motor control unit 8 performs the discharge until the battery voltage drops to the discharge end voltage C when the discharge current is in the small current range IA, as shown in FIG. When the current is in the large current range IB, discharging is performed until the battery voltage drops to the discharge end voltage D. The discharge end voltage when the discharge current is between the small current region IA and the large current region IB gradually decreases from the discharge end voltage C to the discharge end voltage D. Even with such a configuration, the same effects as those in the case shown in FIGS. 7 and 8 can be obtained.

When the discharge end voltage is changed as shown in FIGS. 7 to 11, an average value of the temperatures of all the battery modules 5a may be used instead of the lowest battery module temperature.

In each of the embodiments described above, the example in which the CPU 3 is provided in the battery case 2 has been described. However, the CPU 3 can be provided in the charger 4 in order to perform the control at the time of charging, and the CPU 3 can be provided at the time of discharging. The CPU 3
Can be provided in the motor control unit 8. When the latter configuration is adopted, at least the discharge control means 25 is provided in the motor control unit 8, and the temperature information (the minimum battery module temperature Tmin or the temperature of all the battery modules 5 a) is transmitted from the battery case 2 to the discharge control means 25. By doing so, the control of the discharge current and the control of the end voltage as described above are performed.

[0064]

As described above, according to the present invention, charging can be started in a state where the temperatures of all battery modules are within the guaranteed charging temperature range, so that the battery performance is reduced or the life is shortened. It is possible to charge all battery modules without becoming inconvenienced.

According to another aspect of the present invention, when at least one of the plurality of battery modules satisfies the temperature condition for judging the end of charging, the charging is completed, all the battery modules are charged so as not to be overcharged. Therefore, all the battery modules can be charged without lowering the battery performance or shortening the service life.

According to another aspect of the present invention, when the minimum or average temperature of all battery modules is lower than a predetermined temperature, the upper limit of the discharge current is relatively reduced. When the temperature is lower than a predetermined temperature, the battery temperature can be increased while reducing the load on the battery, so that the capacity of the battery can be fully utilized even in a low-temperature environment. That is, by equipping the electric vehicle with the battery management device, it is possible to increase the capacity by connecting a plurality of battery modules in parallel, and to extend the cruising distance.

According to another invention, when the minimum or average value of the battery temperature of all the battery modules is lower than a predetermined temperature, the discharge end voltage is relatively reduced, the minimum or average value of the battery temperature is reduced. When the temperature is lower than the predetermined temperature, power can be supplied to the load side even if the battery voltage is lower than when the minimum or average value of the battery temperature is higher than the set temperature.

Therefore, the capacity of the battery can be fully utilized even in a low-temperature environment. By installing this battery management device in an electric vehicle, a plurality of batteries can be connected in parallel to increase the capacity. Together with what can be done, the cruising distance can be extended.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a battery management device according to the present invention.

FIG. 2 is a block diagram showing a configuration inside a battery case.

FIG. 3 is a flowchart illustrating an operation of the battery management device before charging is started.

FIG. 4 is a flowchart illustrating an operation of the battery management device when charging is completed.

FIG. 5 is a flowchart for explaining an operation at the time of discharging of the battery management device.

FIG. 6 is a graph showing a map for setting a discharge current.

FIG. 7 is a flowchart for explaining an operation at the time of discharging of a battery management device according to another invention.

FIG. 8 is a graph showing a map for setting a discharge end voltage.

FIG. 9 is a flowchart showing the operation of the battery management device in the case of employing a configuration in which the discharge end voltage is changed steplessly.

FIG. 10 is a graph showing a change in a discharge end voltage.

FIG. 11 is a graph showing a map for setting a discharge termination voltage in a small current region and a discharge termination voltage in a large current region.

[Explanation of symbols]

1 ... Battery management device, 2 ... Battery case, 3
... CPU, 4 ... charger, 5 ... battery assembly,
5a: battery module, 10: thermistor, 22
... temperature detection means, 23 ... charger control means, 25 ... discharge control means.

Claims (6)

[Claims] 1. A battery assembly formed by connecting a plurality of cells in series and formed by connecting a plurality of battery modules, temperature detecting means for detecting a battery temperature for each of the battery modules, and the battery assembly. A charger for charging, and charger control means for controlling the charger in accordance with the battery temperature detected by the temperature detection means, wherein the temperature of all the battery modules is set to a predetermined value. A battery management device, wherein charging is started when the temperature is within a range of a start temperature. 2. The battery management device according to claim 1, wherein the charger control means is configured to end charging when at least one of the plurality of battery modules satisfies a condition for judging end of charging. A battery management device characterized by the above-mentioned. 3. A battery assembly formed by connecting a plurality of battery modules formed by connecting a plurality of cells in series, a temperature detecting means for detecting a battery temperature for each of the battery modules, and a battery module. A discharge control means for controlling a discharge current, wherein the discharge control means sets the upper limit value of the discharge current relatively small when the minimum values of the battery temperatures of all the battery modules are lower than a predetermined temperature. A battery management device, characterized in that: 4. A battery assembly formed by connecting a plurality of battery modules formed by connecting a plurality of cells in series, a temperature detecting means for detecting a battery temperature for each of the battery modules, Discharge control means for controlling the discharge current, wherein the discharge control means sets the upper limit value of the discharge current relatively small when the average value of the battery temperatures of all the battery modules is lower than a predetermined temperature. A battery management device, characterized in that: 5. A battery assembly formed by connecting a plurality of battery modules formed by connecting a plurality of cells in series, a temperature detecting means for detecting a battery temperature for each of the battery modules, and Discharge control means for controlling the discharge current, wherein the discharge control means is configured to set the discharge end voltage relatively low when the minimum value of the battery temperature of all battery modules is lower than a predetermined temperature. A battery management device, characterized in that: 6. A battery assembly formed by connecting a plurality of cells in series and formed by connecting a plurality of battery modules in parallel, temperature detecting means for detecting a battery temperature for each of the battery modules, and Discharge control means for controlling a discharge current, wherein the discharge control means is configured to set a discharge end voltage relatively low when an average value of battery temperatures of all battery modules is lower than a predetermined temperature. A battery management device, characterized in that: