JP2010220377A - Electric storage device - Google Patents

Abstract

An object of the present invention is to provide a power storage device capable of achieving both detection of a short circuit abnormality between pins of a part having a narrow interval between adjacent connection pins and cancellation of an abnormal state due to a short circuit in a circuit of the power storage device.
A plurality of power storage elements 11 connected in series, a voltage detection circuit 17 electrically connected to a positive electrode of each power storage element 11 via a series circuit of a fuse 13 and a switch 15, a switch 15 and a voltage A control circuit 19 electrically connected to the detection circuit 17, and the switch 15 has a configuration in which the parasitic diodes of the two field effect transistors are connected in series so as to be opposite to each other. In No. 19, the two field effect transistors are simultaneously turned on and off when the switch 15 is turned on and off.
[Selection] Figure 1

Description

  The present invention relates to a power storage device that stores power in a power storage element and discharges it when necessary.

  In recent years, defossil fuel vehicles such as hybrid vehicles and electric vehicles have been developed from the viewpoint of environmental protection. Such a vehicle is equipped with a power storage device that stores power by connecting a plurality of power storage elements (such as single cells) in series in order to be driven by a motor. This power storage device includes a control circuit for balancing the voltages by monitoring the voltages of a plurality of power storage elements and adjusting the capacities of the individual power storage elements when variations occur. This control circuit is provided with a voltage detection circuit for detecting the voltage of each storage element.

  As the voltage detection circuit, a flying capacitor type is common. This is because a switch is provided at both ends of the plurality of power storage elements to select any one power storage element, and the flying capacitor is charged by the power storage element, whereby the voltage at both ends of the power storage element is changed between both ends of the flying capacitor. It is detected from the voltage. By adopting such a configuration, there is an advantage that the circuit configuration for detecting the voltage at both ends can be reduced and the circuit configuration is simplified.

  On the other hand, the disadvantage of the flying capacitor type is that a current limiting resistor is provided between the storage element and the flying capacitor so that a large current does not flow when a short circuit failure occurs in the switch. The measurement takes time. In particular, when a large-capacity capacitor capable of rapid charging / discharging is used as the power storage element, the voltage fluctuation is large, so that the voltage detection accuracy may be lowered.

  Further, the plurality of power storage elements are mounted in a state of being insulated from the chassis earth of the vehicle. Therefore, depending on the state of the load (the motor), the output of the power storage device may fluctuate greatly with respect to the chassis ground, and common mode noise may occur. Thereby, there is a possibility that the voltage detection accuracy of the power storage element is lowered.

  Therefore, in order to detect the voltage of the power storage element at high speed and with high accuracy, a circuit configuration is slightly complicated, but a voltage detection device provided with a voltage detection circuit including a differential amplifier in each of the power storage elements, for example, This is proposed in Patent Document 1. Such a voltage detection device is shown in the block circuit diagram of FIG.

  In FIG. 4, a differential amplifier 105 is connected to both ends of a plurality of cells connected in series (hereinafter referred to as a cell 101) via a cell switch 103. A capacitance adjusting circuit 107 is connected between the two input terminals of the differential amplifier 105. The capacity adjustment circuit 107 is composed of a series circuit of a capacity adjustment circuit switch 109 and a resistor 111. Further, a reference voltage source 115 is connected to the capacitance adjusting circuit 107 via a reference voltage source switch 113.

  The output of the differential amplifier 105 is connected to the vehicle controller 121 via the cell controller 117 and the battery controller 119. In addition to the signal from the battery controller 119, the vehicle controller 121 takes in signals from the accelerator, the brake, the vehicle speed sensor, and the like. In addition, the vehicle controller 121 outputs a signal to an indicator that informs the motor controller 123 when a voltage detection circuit including the cell switch 103 and the differential amplifier 105 connected to each cell 101 fails. A signal for driving the vehicle is output. The motor controller 123 controls the motor 127 via the inverter 125. Note that the power of the cells 101 connected in series is supplied to the motor 127 via the inverter 125.

  Next, the operation of such a voltage detection device will be described. When detecting the voltage across each cell 101, the cell controller 117 turns on the cell switch 103. As a result, the voltage across the cell 101 is output from the differential amplifier 105. When this is read by the cell controller 117, the voltage across the cells 101 can be detected. At this time, there is no current limiting resistor between the cell 101 and the differential amplifying unit 105, and the flying capacitor is unnecessary, so that the voltage across the terminal can be detected at high speed and with high accuracy.

  If there is a variation in the both-end voltage detected in this way, the cell controller 117 turns on the capacitance adjusting circuit switch 109 connected to the cell 101 having the higher both-end voltage while the cell switch 103 is turned on. As a result, the power of the cell 101 is consumed by the resistor 111, and the voltage across the both ends decreases. In this manner, the cell controller 117 reduces the voltage variation of each cell 101 by adjusting the capacity of each cell 101.

Fault diagnosis of the voltage detection circuit is performed as follows. First, all the cell switches 103 are turned off, and the capacitance adjusting circuit switch 109 and the reference voltage source switch 113 are turned on. As a result, the voltage of the reference voltage source 115 is input to each differential amplifier 105 after being divided by the resistors 111. Here, the output voltage of each differential amplifier 105 is determined by the voltage of the reference voltage source 115 and the resistance value of each resistor 111 and is known. Therefore, the failure is diagnosed based on whether or not the known output voltage is output from each differential amplifier 105. Thereby, the high reliability of a voltage detection apparatus is acquired.
Japanese Patent No. 3702861

  According to the above power storage device, the failure of the cell switch 103 or the differential amplifier 105 can be detected, but an operational amplifier with a narrow connection pin interval between other components is used. When used in 105, there is a high possibility that a short circuit abnormality between pins occurs, and there is a problem that it is necessary to detect the abnormality. Furthermore, when the abnormality occurs, the electrochemical capacitor not only detects it but also has an overdischarged state of the electric storage element, in particular, a period leading to overdischarge is shorter than that of the battery, and deterioration is likely to proceed due to overdischarge. There is also a problem that the overdischarge state in the above needs to be canceled as soon as possible.

  The present invention solves the above-described conventional problem, and in the circuit of the power storage device, the power storage device that can both detect an abnormality such as a short circuit between pins of adjacent parts having a narrow connection pin interval and quickly cancel the abnormal state due to the short circuit. The purpose is to provide.

  In order to solve the conventional problems, a power storage device of the present invention is electrically connected to a plurality of power storage elements connected in series and a positive electrode of each power storage element via a series circuit of a fuse and a switch. A voltage detection circuit; and a switch and a control circuit electrically connected to the voltage detection circuit, wherein the switch is connected in series so that parasitic diodes of two field effect transistors are opposite to each other. The control circuit is configured to simultaneously turn on and off the two field effect transistors when turning on and off the switch.

  The power storage device of the present invention includes a plurality of power storage elements connected in series, a voltage detection circuit electrically connected to a positive electrode of each power storage element through a series circuit of a fuse and a switch, and the switch. A control circuit electrically connected to the voltage detection circuit, and the switch has a configuration in which parasitic diodes of two field effect transistors are connected in series so as to be opposite to each other, and the control The circuit simultaneously turns on and off the two field effect transistors when turning on and off the switch, and turns off all of the switches when the output of the voltage detection circuit exceeds a predetermined range by cutting the fuse. It is what you do.

  According to the power storage device of the present invention, when an overcurrent flows due to a short circuit between pins of a component having a narrow connection pin interval, a fuse provided between the power storage element and the voltage detection circuit is cut, thereby causing a short circuit between the pins. The detection and the circuit of the main cause part of the overcurrent can be quickly disconnected to cancel the abnormal state. As a result, it is possible to reduce the possibility that an abnormal state such as an overcurrent will continue.

  Further, when the output of the voltage detection circuit exceeds the predetermined range due to the blow of the fuse, the entire storage element and the voltage detection circuit are turned off by turning off all the switches provided between the storage element and the voltage detection circuit. Disconnect. As a result, even if an abnormality occurs in other circuit parts due to the blown fuse, the voltage detection circuit is quickly disconnected, so that the possibility that the storage element continues to discharge and becomes overdischarged can be reduced. The effect that it can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a block circuit diagram of a power storage device according to an embodiment of the present invention. FIG. 2 is a block circuit diagram when the pin-to-pin short-circuit abnormality of the power storage device according to the embodiment of the present invention. FIG. 3 is a flowchart showing the voltage reading operation of the power storage device according to the embodiment of the present invention. In the circuit diagrams of FIGS. 1 and 2, a thick line indicates a high power system wiring, and a thin line indicates a low power system wiring for control or the like.

  In FIG. 1, the power storage device 10 has the following configuration. First, a plurality of power storage elements 11 are connected in series. In the present embodiment, a large-capacity electric double layer capacitor is used as the electricity storage element 11. In addition, the electrical storage element 11 is good also as a series-parallel connection according to required electric power specification. In this case, a plurality of power storage elements in the parallel connection portion may be collectively treated as being equivalent to one power storage element 11. Accordingly, a configuration in which a plurality of power storage elements 11 are connected in series may be used, or a configuration in which a plurality of power storage elements 11 are connected in parallel may be used as one unit, and a plurality of power storage elements 11 may be connected in series. In the present embodiment, the former configuration will be described below.

  A voltage detection circuit 17 is electrically connected to the positive electrode of each power storage element 11 via a series circuit of a fuse 13 and a switch 15. Here, the fuse 13 is cut when an overcurrent flows. Usually, the current value required by the voltage detection circuit 17 is extremely small. Therefore, a chip-type fuse having a small cut current value is used. ing. The switch 15 is configured to be turned on and off by a control circuit described later. Here, two field effect transistors (hereinafter referred to as FETs) are used so that their parasitic diodes are in opposite directions. The configuration is connected in series. At this time, the control circuit controls the two FETs to be turned on / off simultaneously. Thereby, when the two FETs are turned off, the conduction path by the parasitic diode is cut off, so that the storage element 11 and the voltage detection circuit 17 can be more reliably separated.

  In the series circuit, as shown in FIG. 1, the fuse 13 is directly connected to the storage element 11. Thereby, for example, even if an overcurrent flows due to a ground fault of the switch 15, the fuse 13 directly connected to the power storage element 11 is blown, so the possibility that the overcurrent from the power storage element 11 continues to flow can be reduced. High reliability can be obtained. Further, since the negative electrode of the lowermost storage element 11 in FIG. 1 is directly connected to the ground, a series circuit of the fuse 13 and the switch 15 is not provided. Therefore, the series circuit is configured to be connected to the positive electrode of each storage element 11.

  The voltage detection circuit 17 is electrically connected to both ends of each storage element 11, and has a configuration for outputting voltages V1, V2,..., Vn (n is the number of storage elements 11 connected in series). . Here, an operational amplifier is used as the voltage detection circuit 17. The operational amplifier is generally integrated into an IC and has a total of five terminals: two input terminals, one output terminal, and positive and negative power supply terminals. Therefore, the connection pin interval between these five terminals is narrow.

  Each of the switch 15 and the voltage detection circuit 17 is electrically connected to the control circuit 19. The control circuit 19 is composed of a microcomputer and peripheral circuits. The control circuit 19 reads the voltages V1, V2,..., Vn of each storage element 11 detected by each voltage detection circuit 17, and outputs switch on / off signals SW1 to SWn. Thus, on / off control of each switch 15 is performed. Further, the control circuit 19 has a configuration for transmitting / receiving a data signal data to / from an external control circuit (not shown). Thereby, for example, operations such as integrated control of the plurality of power storage devices 10 by the external control circuit can be performed.

  The positive electrode side of the plurality of power storage elements 11 connected in series is connected to the positive electrode terminal 21, and the negative electrode side is connected to the negative electrode terminal 23. Charging / discharging of each storage element 11 is performed via the positive electrode terminal 21 and the negative electrode terminal 23. The negative electrode terminal 23 is a common (ground) terminal inside the power storage device 10.

  A regulator 25 is electrically connected between the positive terminal 21 and the negative terminal 23. The regulator 25 generates a power supply voltage (for example, 5 V) for driving each voltage detection circuit 17, the control circuit 19, and the like from the total voltage of the storage element 11.

  Next, the operation of the power storage device 10 will be described first.

  When the external control circuit receives the use start signal of the power storage device 10 as the data signal data, the control circuit 19 outputs switch on / off signals SW1 to SWn so as to turn on all the switches 15. Thereby, each power storage element 11 is electrically connected to the voltage detection circuit 17, so that the control circuit 19 can read the voltages V <b> 1, V <b> 2,. As a result, the control circuit 19 monitors the both-end voltages V1, V2,..., Vn of the respective storage elements 11, and outputs them as data signals data to the external control circuit. Accordingly, the external control circuit can perform charge / discharge control of the storage element 11.

  On the other hand, when the external control circuit receives the use end signal of the power storage device 10 as the data signal data after the use is finished, the control circuit 19 outputs switch on / off signals SW1 to SWn so as to turn off all the switches 15. As a result, all switches 15 are turned off when not in use and each storage element 11 is electrically disconnected from the voltage detection circuit 17, so that the storage element 11 is overdischarged via the voltage detection circuit 17 when not in use. The possibility of being lost can be reduced. Furthermore, even when a pin short-circuit abnormality occurs in the voltage detection circuit 17 when not in use, the possibility of overcurrent flowing from the power storage element 11 can be reduced because the switch 15 is off.

  Normally, the operation is as described above. Next, an operation at the time of abnormality while the power storage device 10 is in use will be described.

  First, as described above, the control circuit 19 turns on each switch 15 at the normal time when the pin-to-pin short-circuit abnormality of a component (here, the operational amplifier of the voltage detection circuit 17) with a narrow connection pin interval does not occur. Thereby, both-ends voltage V1, V2, ..., Vn of each electrical storage element 11 is detected.

  In this state, as indicated by a thick dotted line in the uppermost voltage detection circuit 17 of FIG. 2, impurities made of a conductor adhere between the input terminal and the ground terminal of the voltage detection circuit 17, and the two are made conductive. Suppose that it is in a state. This corresponds to the fact that a component (op amp) having a narrow connection pin interval, such as the voltage detection circuit 17, has caused an inter-pin short circuit abnormality. As a result, this is equivalent in circuit to the fact that both ends of the second to the bottom of the power storage elements 11 connected in series are connected to the ground, so that the second power storage as shown by the thick arrows in FIG. A large current flows from the positive electrode of the element 11 toward the ground of the voltage detection circuit 17. As a result, the second fuse 13 from the top in FIG. 2 is cut. With such a configuration, when a large current (overcurrent) flows from the storage element 11 toward the voltage detection circuit 17, the fuse 13 arranged in the path including the main cause portion of the overcurrent is immediately cut off. Problems such as application of overvoltage to the entire circuit and temperature rise due to continued overcurrent can be eliminated. Furthermore, the rapid overcurrent disconnection suppresses the overdischarge even when the power storage element 11 is an electrochemical capacitor, so that the deterioration of the power storage element 11 can be reduced. In addition, since the output of the voltage detection circuit 17 greatly fluctuates when the fuse 13 is cut, it is possible to detect in which circuit portion the overcurrent has flowed.

  As a result of the above operation, the fuse 13 in the portion where the overcurrent flows directly cuts off the main cause portion, so that the short circuit abnormality between the pins is detected and the circuit of the main cause portion of the overcurrent is quickly disconnected. The possibility that an abnormal state such as an overcurrent will continue is reduced.

  Here, during the period until the fuse 13 is cut, an abnormal voltage may be applied to the other voltage detection circuit 17 through, for example, the ground, causing a malfunction such as a short circuit inside the voltage detection circuit 17. If this is left as it is, there is a possibility that an overcurrent also flows through the defective voltage detection circuit 17 or the output of the voltage detection circuit 17 becomes an abnormal value. When an overcurrent flows, as described above, the fuse 13 connected to the defective voltage detection circuit 17 is also cut. Accordingly, other circuit portions such as the voltage detection circuit 17 having a hardware abnormality can be separated. However, there may be a case where a current that does not cause the fuse 13 to continue to flow continues to flow.

  Therefore, in the present embodiment, even if an abnormality occurs in another circuit portion due to the fuse 13 being cut, the operation of quickly disconnecting all the voltage detection circuits 17 is performed in software. This operation will be described with reference to the flowchart of FIG. The flowchart of FIG. 3 is a subroutine, and is executed as appropriate (for example, every 0.1 second) by the microcomputer of the control circuit 19.

  When the subroutine of FIG. 3 is executed, the control circuit 19 assigns 1 to the variable i (step number S11). Here, the variable i indicates the order of the both-end voltage Vi. Since 1 is substituted for the variable i in S11, the both-end voltage Vi indicates the both-end voltage V1 of the first power storage element 11. In FIG. 3, for example, when i = 1, it is defined that the value on the right side (here, 1) is substituted for the variable on the left side (here, variable i), except for the determination operation.

  Next, the control circuit 19 reads the voltage Vi across the i-th storage element 11 from the voltage detection circuit 17 according to the value of the variable i (S13). Next, the control circuit 19 determines whether or not the read both-end voltage Vi exceeds a predetermined range (S15). Here, the predetermined range is a range of voltage values that can be taken by the voltage Vi across the power storage element 11. In the present embodiment, since the electric double layer capacitor is used for the power storage element 11, the predetermined range of the both-end voltage Vi is set to 0V to the rated voltage 2.5V. If the both-end voltage Vi is a negative voltage (overdischarge state) of less than 0V or an overvoltage of 2.5V or more, the both-end voltage Vi exceeds the predetermined range (Yes in S15), so that the control circuit 19 determines that some abnormality such as a short circuit between pins of the voltage detection circuit 17 or an internal circuit abnormality of the voltage detection circuit 17 accompanying the abnormality is occurring, and immediately turns off all the switches 15 (S17). Thereby, since all the voltage detection circuits 17 are disconnected from the electrical storage element 11 quickly, the possibility that the electrical storage element 11 will continue to be discharged due to an internal circuit abnormality of the voltage detection circuit 17 and the like will be reduced.

  Next, the control circuit 19 outputs an abnormal signal to the external control circuit (not shown) by the data signal data (S19) to inform the power storage device 10 that an abnormality has occurred. In response to this, the external control circuit obtains further high reliability by prohibiting charging / discharging of the power storage device 11 of the power storage device 10 or stopping the use of the power storage device 10 itself. Thereafter, the subroutine of FIG. 3 is terminated.

  Here, it returns to S15, and if both-ends voltage Vi does not exceed the predetermined range (No of S15), it will be judged that the i-th electrical storage element 11 and the voltage detection circuit 17 are normal. In this case, in order to continue to determine the abnormality of the next power storage element 11 or voltage detection circuit 17, the value of the variable i is incremented by 1 and updated (S21). Next, the control circuit 19 determines whether or not the variable i has reached n + 1 (S23). Here, n is the number of power storage elements 11 in series. If the variable i is not n + 1 (No in S23), the process returns to S13, and the operation after the reading of the next both-end voltage Vi is continued. On the other hand, if the variable i is equal to n + 1 (Yes in S23), all the voltages Vi are within the predetermined range, so the subroutine of FIG.

  Due to such an operation, if even one of the voltages Vi across the storage element 11 is abnormal, all the voltage detection circuits 17 are quickly disconnected by turning off all the switches 15, resulting in a short circuit between the pins. Even if the abnormality of the voltage detection circuit 17 occurs, it is possible to reduce the influence of overdischarge or the like of the storage element 11.

  Here, as shown in FIG. 2, the case where the input terminal of the voltage detection circuit 17 and the ground terminal are in a conductive state has been described, but the fuse 13 is also cut in the following cases.

  First, when the input terminal of the voltage detection circuit 17 and the power supply terminal are in a conductive state, since the power supply terminal is electrically connected to the regulator 25, the positive electrode of the power storage element 11 is connected via the power supply terminal. Conduction with the regulator 25 will occur. In this case, the voltage of the power supply terminal, that is, the output terminal of the regulator 25 may be extremely lower than the voltage of the positive electrode of the storage element 11. At this time, a large current flows simultaneously with the occurrence of a short circuit due to the high voltage difference. However, since a large current always flows through the fuse 13 even in this state, the fuse 13 is cut and high reliability is obtained.

  Next, when the two input terminals of the voltage detection circuit 17 become conductive, the positive electrode and the negative electrode of the power storage element 11 to which the voltage detection circuit 17 is electrically connected are short-circuited. In this case as well, a large current flows from the positive electrode to the negative electrode of the storage element 11 simultaneously with the occurrence of the short circuit. However, since at least one fuse 13 is interposed in this current path, the fuse 13 is cut. Therefore, high reliability can be obtained.

  Next, when the input terminal and the output terminal of the voltage detection circuit 17 are brought into conduction, the positive electrode of the power storage element 11 is conducted with the control circuit 19. In this case, the allowable voltage input to the control circuit 19 may be extremely lower than the voltage of the positive electrode of the storage element 11. At this time, a large current flows simultaneously with the occurrence of a short circuit due to the high voltage difference. However, since a large current always flows through the fuse 13 even in this state, the fuse 13 is cut and high reliability is obtained.

  In this way, it can be seen that the high reliability can be obtained because the fuse 13 is cut when any of the four short-circuit states including the short-circuit state of FIG. 2 occurs. Moreover, since it is not known which short circuit state occurs among the above-mentioned four ways, the fuse 13 needs to be electrically connected to the positive electrodes of all the power storage elements 11.

  With the above configuration and operation, when a pin short-circuit abnormality occurs, the fuse 13 at the location where the abnormality has occurred is immediately cut off, and other circuit parts such as the voltage detection circuit 17 are abnormal due to the fuse 13 being cut. Even so, the fuse 13 connected to the circuit portion having the abnormality is also disconnected, so that it is quickly disconnected from the power storage element 11. Therefore, it is possible to realize a power storage device that can both detect a short circuit abnormality between pins and cancel an abnormal state due to a short circuit. Further, if the output of the voltage detection circuit 17 exceeds the predetermined range due to the fuse 13 being cut, all the switches 15 are turned off, so that the storage element 11 can continue to be discharged via the voltage detection circuit 17 and become overdischarged. A power storage device capable of reducing the performance can be realized.

  In the present embodiment, only the circuit configuration relating to the voltage detection of each power storage element 11 has been described, but in addition to this, a circuit for balancing the voltage at both ends of each power storage element 11 may be provided. In this case, by executing the flowchart of FIG. 3, if there is no abnormality such as a short circuit between pins, all the voltages Vi are obtained. Therefore, based on these values, the control circuit 19 determines which power storage by the conventional method. What is necessary is just to obtain voltage balance by calculating how long the element 11 is discharged.

  In the present embodiment, an electric double layer capacitor is used as the electricity storage element 11, but this may be another electricity storage element such as an electrochemical capacitor or a secondary battery.

  The power storage device according to the present invention can both detect a short circuit abnormality between pins and cancel an abnormal state due to a short circuit, and thus is particularly useful as a power storage system for vehicles that require high reliability, a power storage device for an emergency auxiliary power source, or the like. is there.

1 is a block circuit diagram of a power storage device in an embodiment of the present invention. The block circuit diagram at the time of the short circuit between pins of the electrical storage apparatus in embodiment of this invention The flowchart which shows the both-ends voltage reading operation | movement of the electrical storage apparatus in embodiment of this invention Block diagram of a conventional voltage detector

DESCRIPTION OF SYMBOLS 10 Power storage device 11 Power storage element 13 Fuse 15 Switch 17 Voltage detection circuit 19 Control circuit

Claims (5)

A plurality of power storage elements connected in series;
A voltage detection circuit electrically connected to a positive electrode of each power storage element via a series circuit of a fuse and a switch;
A control circuit electrically connected to the switch and the voltage detection circuit;
The switch has a configuration in which parasitic diodes of two field effect transistors are connected in series so as to be opposite to each other,
The power storage device, wherein the control circuit simultaneously turns on and off the two field effect transistors when the switch is turned on and off. A plurality of power storage elements connected in series;
A voltage detection circuit electrically connected to a positive electrode of each power storage element via a series circuit of a fuse and a switch;
A control circuit electrically connected to the switch and the voltage detection circuit;
The switch has a configuration in which parasitic diodes of two field effect transistors are connected in series so as to be opposite to each other,
The control circuit simultaneously turns on and off the two field effect transistors when turning on and off the switch, and when the output of the voltage detection circuit exceeds a predetermined range by cutting the fuse, all the switches are turned on. A power storage device that is turned off. The power storage device according to claim 2, wherein the control circuit outputs an abnormal signal to the outside when all the switches are turned off. The power storage device according to claim 1, wherein the fuse is directly connected to the power storage element in the series circuit. The power storage device according to claim 1, wherein the control circuit turns off all the switches when not in use.

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