JP4291629B2 - Battery device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery device having a circuit that reduces power consumption by disconnecting an overvoltage protection circuit when the battery is not charged.
[0002]
[Prior art]
In the conventional overvoltage protection circuit for battery cells, the cell charging voltage of a lithium ion battery is one of the parameters of life, and if any of the cells in a multistage series is biased to a high charging voltage, the cell capacity will be degraded. An overvoltage protection circuit is connected to each cell for the purpose of avoiding this problem. A common charging current flows in each cell connected in series, and charging is managed with the same current-time product. Therefore, charging current is shunted to the overvoltage protection circuit for cells whose charging voltage rises quickly due to variations among cells. As a result, the upper limit of the charging voltage is limited (see, for example, Non-Patent Document 1).
[0003]
However, since the overvoltage protection circuit consumes its own power when it is not charged, trickle charging for supplementary charging needs to be added to the operating conditions during orbital operation in outer space, and complicated operating conditions are required. In addition, during storage and transportation on the ground, the battery is discharged due to power consumption by the overvoltage protection circuit, and the battery voltage decreases when left for a long time. At this time, depending on the type of the battery (for example, a lithium ion battery), the battery voltage falls below the minimum value of the specified voltage and is damaged. Therefore, it is required to manage and maintain the battery voltage within the specified voltage range.
[0004]
[Non-Patent Document 1]
Toshio Okamura and two others, “Development of Lithium-ion Battery System for Spacecraft-Report of Examination Results of Space Battery System Using Lithium-ion Battery-”, February 17, 2000, IEICE Technical Research Report Vol. 99 No. 624,625
[0005]
[Problems to be solved by the invention]
The present invention solves the above-described problems and relates to a battery device that includes a switch that cuts off between a battery cell and an overvoltage protection circuit except when charging a battery, thereby reducing power consumed during non-charging.
[0006]
[Means for Solving the Problems]
A battery device according to the present invention includes a plurality of battery cells connected in series, stores a battery, a power source that charges the battery, a signal generation circuit that detects a voltage of the power source and outputs an operation signal. A plurality of overvoltages connected in parallel for each of the battery cells, and detecting the overvoltage of each of the battery cells, bypassing charging of the battery cell that has detected the overvoltage by driving a shunt element, and protecting each of the battery cells A protection circuit, a plurality of switches connected in parallel for each of the battery cells, and including a shunt element and a plurality of switches for cutting off or conducting a connection path between the battery cells, and from the signal generation circuit Based on the operation signal, a plurality of switches for individually driving the respective switches for each of the battery cells. Comprising a driving circuit, wherein the respective switch, based on a signal generated from the respective switch driving circuit based on the operation signal from the signal generating circuit, when the voltage of the power source is higher than the reference voltage The connection path between the overvoltage protection circuit including the shunt element and the battery cell is in a conductive state, and the connection path between the overvoltage protection circuit including the shunt element and the battery cell is cut off when the voltage of the power supply is lower than a reference voltage. It is what.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Specific examples of the present invention will be described in detail below. FIG. 1 is a block diagram showing a lithium ion battery device for a spacecraft power system according to the present invention. Of course, it may be used other than the spacecraft power system. This battery device uses the output current of a solar cell as means for determining the switch operating state, and is a spacecraft provided with a switch and a switch driving circuit for each battery cell that cuts off / conducts between the battery cell and the overvoltage protection circuit. It is a part of the lithium ion battery device for electric power systems. The space system power system includes a solar cell 1 that generates power during sunshine, a constant voltage control circuit 2 that outputs a current by controlling the power generated by the solar cell 1 to a constant voltage, and an output current from the constant voltage control circuit 2 Other devices for operating and operating satellites and spacecraft that consume power supplied from the output current detection circuit 3 for monitoring and detection, the solar cell 1, etc. (hereinafter collectively referred to as the load device 5), loads in the shade In preparation for supplying power to the device 5, a battery 7 that stores power during sunshine, a backflow prevention diode 4 that prevents current from flowing back from the battery 7 to the constant voltage control circuit 2 during shade, and a battery 7 that is charged during sunshine are charged. A battery charge / discharge controller 6 that discharges the power stored in the battery 7 to the load device 5 in the shade, battery cells 8a to 8c constituting the battery 7, and an overvoltage protection circuit 1 connected in parallel. Switch driving for individually driving the switches 11a to 11c and the switches 11a to 11c using switching devices such as relays as devices for shutting off / conducting the overvoltage protection circuits 10a to 10c and the battery cells 8a to 8c The circuit 9a-9c is comprised.
The output current detection circuit 3 generates a current detection resistor 15 that detects an output current from the solar cell 1 and an operation / stop signal that is transmitted to the switch drive circuits 9a to 9c using the voltage generated in the resistor 15. The signal generation circuit 16 is configured. The overvoltage protection circuits 10a to 10c include switches 11a to 11c for cutting off / conducting connection between the battery cells 8a to 8c and the overvoltage protection circuits 10a to 10c, battery cells 8a to 8c, shunt elements 12a to 12c for bypassing each charging current, The circuit is composed of drive circuits 13a to 13c that control the operation of the shunt elements 12a to 12c and cell voltage detection circuits 14a to 14c that monitor and detect the voltages of the battery cells 8a to 8c.
[0008]
The operation of the lithium ion battery device for a spacecraft power system according to the present invention will be described. During sunlight when the solar cell 1 is irradiated with solar light, the solar cell 1 starts power generation as a constant current source, converts the generated power of the solar cell 1 and outputs a constant voltage to the constant voltage control circuit 2. When the output current rises, power is supplied to the battery charge / discharge controller 6 and the load device 5 that charge-control the battery 7 at a constant current / constant voltage. Further, when the output current of the constant voltage control circuit 2 rises from the shade time to the sunshine time, the output current detection circuit 3 converts the voltage into a voltage by the current detection resistor 15 provided in the output current detection circuit 3. The detected voltage value is output to the signal generation circuit 16. The signal generation circuit 16 constantly monitors the voltage value from the resistor 15 and constantly compares it with a reference voltage set by a Zener diode or the like. When the voltage from the resistor 15 reaches the reference voltage value, the signal generation circuit 16 Thus, an operation signal (for example, a high level signal) is generated and transmitted to the switch drive circuits 9a to 9c. The switch drive circuits 9a to 9c that have received the operation signal transmit the drive voltage / current necessary for turning on the switches 11a to 11c to the switches 11a to 11c as drive signals, so that the switches 11a to 11c become conductive. The overvoltage protection circuits 10a to 10c are in a state where the voltage of the battery cell 8 can be constantly monitored because the switches 11a to 11c are in a conductive state, and are in a standby state enabling overvoltage protection during charging. If the switches 11a to 11c can be turned on by a signal from the signal generation circuit 16, the switch drive circuits 9a to 9c are unnecessary.
[0009]
The operation of the overvoltage protection circuits 10a to 10c will be described on behalf of the overvoltage protection circuit 10a. In the standby state of the overvoltage protection circuit 10a, when the battery cell 8a is further charged and the voltage of the battery cell 8a rises and reaches the overvoltage level determined and defined by the specifications and operating conditions of the battery cell 8a, the battery cell 8a voltage is monitored. The cell voltage detection circuit 14a (for example, a circuit configured by a semiconductor element such as an operational amplifier or a transistor) is connected to a driving circuit 13a (for example, a circuit configured by a semiconductor element such as a transistor) and a driving circuit operation signal (for example, an analog signal). The drive circuit 13a that has received the drive circuit operation signal transmits a drive signal (for example, an analog signal) to the shunt element 12a (for example, a semiconductor element such as a transistor), and gradually turns on the shunt element 12a to turn on the battery cell. The charging current of 8a is gradually bypassed.
[0010]
On the other hand, when shifting from sunshine to shade, the solar cell 1 is not irradiated with sunlight and does not generate power, so the generated power of the solar cell 1 decreases and the output current of the constant voltage control circuit 2 that outputs a constant voltage also decreases to zero. The power supply from the solar cell 1 to the load device 5 is stopped. However, the power supply to the load device 5 is supplemented by supplying the power charged in the battery 7 to the load device 5 via the battery charge / discharge controller 6. At this time, the backflow prevention diode 4 is provided to prevent the current from the battery 7 from flowing back to the constant voltage control circuit 2 side. Further, since the output current of the constant voltage control circuit 2 becomes zero, the voltage value generated in the current detection resistor 15 provided in the output current detection circuit 3 is also reduced, and the reference voltage value set by a zener diode or the like is set. In the following, a stop signal (for example, a low level signal) is generated from the signal generation circuit 16, the switches 11a to 11c are cut off via the switch drive circuits 9a to 9c, and the overvoltage protection circuits 10a to 10c are connected to the battery cell 8a. Separated from ~ 8c. From this, when the switches 11a to 11c are cut off, the power to the overvoltage protection circuits 10a to 10c that has been always borne by the battery cells 8a to 8c is reduced.
[0011]
FIG. 2 shows details of the operation of the switch drive circuit 9a on behalf of the output current detection circuit 3 and the switch drive circuits 9a to 9c. As an example of the configuration of FIG. 2, the signal generation circuit 16 includes a voltage differential amplifier circuit 17 that amplifies an input low voltage, a comparison circuit 18 that generates an operation signal by comparing the output voltage of the voltage differential amplifier circuit 17 and a reference voltage, A reference voltage generation circuit 19 such as a Zener diode for generating a reference voltage, a pull-up power source 20 for generating an operation signal, and a pull-up resistor 21 are included. The switch drive circuit 9a transmits a drive signal to the switch 11a by an operation signal. Drive signal generating element 22a and pull-up power supply 20a. When the output current of the constant voltage control circuit 2 rises from the shade time to the sunshine time, the current detection resistor 15 that converts the output current into a voltage increases the output voltage from zero and outputs it to the signal generation circuit 16. The resistor 15 has a low resistance value so that power supply to the load device 5 and the battery 7 is not hindered, and thus the output voltage is also low. Here, the output voltage is amplified by the voltage differential amplifier circuit 17 in the signal generation circuit 16, and the voltage is compared with the reference voltage generated by the reference voltage generation circuit 19 by the comparison circuit 18. When the output voltage side is large, the comparison circuit 18 outputs an operation signal (in the example, a high level signal). The switch drive circuit 9a to which the operation signal is input outputs a drive signal (in the example, a high level signal) when the internal drive signal generating element 22a is turned on, and the switch 11a is turned on, thereby overvoltage protection circuit 10a. Set to standby. On the other hand, when shifting from daylight to shade, when the output current of the constant voltage control circuit 2 drops to zero, the output voltage of the resistor 15 becomes zero, that is, the output voltage of the voltage differential amplifier circuit 17 is also zero. It becomes. The comparison circuit 18 outputs a stop signal (in this example, a low level signal) when the voltage is smaller than the reference voltage generated by the reference voltage generation circuit 19. The switch drive circuit 9a receiving the stop signal outputs a drive stop signal (in this example, a low level signal) by turning off the internal drive signal generating element 22a, and turns off the switch 11a to protect against overvoltage. The circuit 10a is separated from the battery cell 8a.
[0012]
FIG. 3 shows an embodiment in which a current sensor 24 is provided instead of the current detection resistor 15 shown in FIG. 2 and an output current detection circuit 23 for detecting the output of the current sensor 24 is used in place of the signal generation circuit 16. . Here, the specific examples of FIGS. 1 and 2 use the voltage drop generated in the current detection resistor 15 in the output current detection circuit 3 as a method of detecting the start of charging. Even if the output current is detected as a voltage value and replaced with the output current detection circuit 23 that operates the comparison circuit 18, the same operation is performed. The current sensor 24 may detect the current in a non-contact manner. As a result, the power consumed by the current detection resistor 15 is suppressed, and the loss is reduced.
[0013]
FIG. 4 shows an embodiment in which an output voltage detection circuit 25 that directly detects a voltage is used in place of the current detection resistor 15 and the signal generation circuit 16 shown in FIG. Here, the specific examples in FIGS. 1 and 2 use the voltage drop generated in the current detection resistor 15 in the output current detection circuit 3 as a method for detecting the start of charging. Even if the output voltage of the circuit 2 is directly monitored and replaced with the output voltage detection circuit 25 for operating the comparison circuit 18, the same operation is performed. Since the voltage is directly detected, the accuracy is improved as compared with the above, and the number of parts is reduced, which is advantageous.
[0014]
FIG. 5 shows an embodiment in which an overvoltage protection circuit using a semiconductor switch 26a is used instead of the switch 11a shown in FIG. The switch 11a that cuts off / conducts the battery cell 8a and the overvoltage protection circuit 10a is configured by a switching device such as a relay, but operates in the same manner even if it is replaced with the semiconductor 26a. The use of a semiconductor switch reduces the failure probability and can withstand a longer operation than the mechanical switchgear as described above.
[0015]
FIG. 6 shows changes in voltage and current output by the constant voltage control circuit 2 when shifting from shade to sunlight, and further from sunlight to shade. The constant voltage control circuit 2 rises from zero for both the output voltage 27 and the output current 28 when shifting from shade to sunshine. In the case of the output current detection circuit 3, the output current detection circuit 3 transmits an operation signal to the switch drive circuits 9a to 9c when the output current 28 exceeds the reference current value 30. In the case of the output voltage detection circuit 25, the output voltage detection circuit 25 transmits an operation signal to the switch drive circuits 9a to 9c when the output voltage 27 exceeds the reference voltage value 29. Next, when the time shifts from daylight to shade, the constant voltage control circuit 2 decreases both the output voltage 27 and the output current 28 to zero. In the case of the output current detection circuit 3, the output current detection circuit 3 transmits a stop signal to the switch drive circuits 9a to 9c when the output current 28 falls below the reference current value 30. In the case of the output voltage detection circuit 25, the output voltage detection circuit 25 transmits a stop signal to the switch drive circuits 9a to 9c when the output voltage 27 falls below the reference voltage value 29.
[0016]
Further, the present invention shows an example of a battery device using the output of the solar cell 1 in FIG. 1, but the power system battery device that operates in the same manner even if it is replaced with a generator or a power supply device instead of the solar cell 1 Configure.
[0017]
As described above, according to the present invention, since the power consumed during the standby state of the overvoltage protection circuits 10a to 10c is reduced, trickle charging for supplementing the power consumption becomes unnecessary during orbital operation in outer space, and the operating conditions are simplified. The battery 7 can be prevented from being lowered during storage and transportation, and the management of the battery device can be simplified.
[0018]
A battery for storing power, a power supply for charging the battery, a signal generation circuit for detecting the voltage of the power supply and outputting an operation signal when the voltage is higher than the reference voltage, and a battery connected in parallel to detect the overvoltage of the battery A switch for turning on / off the overvoltage protection circuit provided in the overvoltage protection circuit is consumed during orbital operation in outer space by a battery device driven by an operation signal from the signal generation circuit. Trickle charging for replenishing electric power is unnecessary, simplification of operating conditions, and battery voltage management can be simplified by preventing battery voltage drop during ground storage and transportation.
[0019]
Moreover, a simple configuration can be achieved by detecting the power supply voltage with a current detection resistor.
[0020]
By detecting the power supply voltage with the current sensor, the power consumed by the current detection resistor can be suppressed, so that the loss is reduced.
[0021]
By directly detecting the power supply voltage as a voltage, the voltage can be detected with high accuracy, and the number of parts is reduced, which is advantageous.
[0022]
Since the switch is a relay switch, a simple configuration can be achieved.
[0023]
Since the switch is a semiconductor switch, the probability of failure is reduced and it can withstand long-term operation.
[0024]
Since the power source is a solar cell, trickle charging for replenishing consumed power during orbital operation in outer space is unnecessary, and the operating conditions can be simplified.
[0025]
【The invention's effect】
According to the present invention, it is possible to reduce the power consumed by the overvoltage protection circuit in the standby state during non-charging.
[Brief description of the drawings]
FIG. 1 includes a switch and a switch driving circuit that use an output current of a solar cell as a detection means during charging, and that cuts off / conducts between a battery cell connected in series and an overvoltage protection circuit connected in parallel to each battery cell. A battery device provided with an overvoltage protection circuit.
FIG. 2 is a part of a specific example of a battery device showing detailed operations of a detection means and a switch drive circuit during charging.
FIG. 3 is a part of a specific example of a battery device that detects an output current of a solar cell by a current sensor.
FIG. 4 is a part of a specific example of a battery device that operates a switch drive circuit by directly monitoring an output voltage of a constant voltage control circuit.
FIG. 5 is a part of a specific example of a battery device in which a switch is a semiconductor switch.
FIG. 6 is an example of a transition diagram of the voltage and current output by the constant voltage control circuit when shifting from shade to sunlight and from sunlight to shade.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solar cell 2 Constant voltage control circuit 3 Output current detection circuit 4 Backflow prevention diode 5 Load apparatus 6 Battery charge / discharge controller 7 Battery 8 Battery cell 9 Switch drive circuit 10 Overvoltage protection circuit 11 Switch 12 Shunt element 13 Drive circuit 14 Cell voltage Detection circuit 15 Current detection resistor 16 Signal generation circuit 17 Voltage differential amplification circuit 18 Comparison circuit 19 Reference voltage generation circuit 20 Pull-up power supply 21 Pull-up resistor 22 Drive signal generation element 23 Output current detection circuit 24 Current sensor 25 Output voltage Detection circuit 26 Semiconductor switch 27 Output voltage 28 Output current 29 Reference voltage value 30 Reference current value

Claims (7)

A battery composed of a plurality of battery cells connected in series and storing electric power;
A power source for charging the battery;
A signal generation circuit for detecting a voltage of the power supply and outputting an operation signal;
A plurality of overvoltage protections that are connected in parallel for each of the battery cells, and when the overvoltage of each of the battery cells is detected, charging of the battery cell that has detected the overvoltage is bypassed by driving a shunt element, thereby protecting the battery cells. Circuit,
A plurality of switches that are connected in parallel for each battery cell and that disconnect or cut off or connect the connection path between the overvoltage protection circuit including the shunt element and the battery cell;
A plurality of switch driving circuits for individually driving each switch for each of the battery cells based on an operation signal from the signal generating circuit;
With
Each of the switches includes the shunt element when the voltage of the power source is higher than a reference voltage based on a signal generated from the switch driving circuit based on an operation signal from the signal generation circuit. A battery device in which a connection path between a circuit and the battery cell is in a conductive state, and a connection path between the overvoltage protection circuit including the shunt element and the battery cell is cut off when a voltage of the power source is lower than a reference voltage.   The battery device according to claim 1, wherein the power supply voltage is detected by a current detection resistor.   The battery device according to claim 1, wherein the power supply voltage is detected by a current sensor.   The battery device according to claim 1, wherein the power supply voltage is directly detected as a voltage. The battery device according to any one of claims 1 to 4 , wherein the switch is a relay switch. The battery device according to any one of claims 1 to 4 wherein the switch is a semiconductor switch. The battery device according to any one of claims 1 to 6 , wherein the power source is a solar battery.

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