JP2010288358A - Power storage device - Google Patents

Abstract

An object of the present invention is to provide a power storage device that can reduce voltage balance deviation due to discharge from a power storage element and can detect disconnection.
A plurality of power storage elements 21 connected in series, a capacitor 23 electrically connected to every other end of each power storage element 21, and a voltage detection line 25 electrically connected to both ends of the power storage element 21. A voltage detection circuit 27 connected to detect the voltage of the storage element 21 (Vi: i = 1 to n, where n is the number of series storage elements 21), and a control circuit 41 electrically connected to the voltage detection circuit 27 The control circuit 41 obtains the change width (ΔVi) of the voltage (Vi) of each storage element 21 during the predetermined period (Δt) when the storage element 21 is charged / discharged, and the change width (ΔVi) is a predetermined value ( It is determined that the voltage detection line 25 between the storage element 21 and the voltage detection circuit 27 that is equal to or less than (ΔVs) is disconnected.
[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, a vehicle such as a hybrid vehicle having improved efficiency has been developed by collecting regenerative energy generated during braking as regenerative power. Such a vehicle requires a power storage device for storing the regenerative power and discharging it at times other than braking.

  In this power storage device, for example, in order to drive an auxiliary machine of a vehicle, a plurality of power storage elements are connected in series or in series-parallel to increase the voltage. In the case of such a configuration, the voltage of each power storage element varies in the process of repeatedly charging and discharging. As a result, there are overcharged and overdischarged power storage elements, which may shorten the life of the power storage device. Therefore, in the power storage device, it is important to detect and monitor the voltage of each power storage element.

  As such a voltage detection circuit for a storage element, for example, the configuration of Patent Document 1 has been proposed. In the configuration of Patent Document 1, an assembled battery is used as the power storage element. A circuit diagram of this assembled battery voltage detection circuit is shown in FIG.

  The assembled battery 101 has a configuration in which a plurality of battery modules 103 as the storage elements are connected in series. An analog-digital converter 107 is electrically connected to both ends of these battery modules 103 via voltage detection lines 105. The output of the analog-digital converter 107 is connected to an arithmetic circuit (not shown), from which the voltage of each battery module 103 can be detected.

  Each voltage detection line 105 is electrically connected to a voltage dividing resistor 109 except for the one connected to the voltage detection point V3. Further, a voltage branch line 111 is connected between the voltage dividing resistor 109 and the analog-digital converter 107. This voltage branch line 111 is connected to the ground via a voltage dividing resistor 113. Since the voltage detection point V3 is directly connected to the ground by the voltage detection line 105, the voltage branch line 111 and the voltage dividing resistors 109 and 113 are not connected. Further, as shown in FIG. 5, since the analog-digital converter 107 is also connected to the ground, the voltage detection point V3 and the analog-digital converter 107 are electrically connected via the ground.

  Here, as shown in FIG. 5, since the voltage dividing resistor 109 is 110 kΩ and the voltage dividing resistor 113 is 10 kΩ, the voltage dividing ratio between them is about 0.083. Therefore, for example, the voltage at the voltage detection point V1 is multiplied by 0.083 and input to the analog-digital converter 107.

  By connecting the voltage dividing resistors 109 and 113 as shown in FIG. 5, the arithmetic circuit can detect the disconnection of the voltage detection line 105. For example, if a disconnection occurs in the voltage detection line 105 at the mark x in FIG. 5, the voltage detection line 105 is electrically connected to the ground via the voltage dividing resistors 109 and 113. A voltage detection value by the converter 107 (hereinafter referred to as voltage data V (CH1)) is approximately 0V. Therefore, the voltage across the battery module 103 to which the disconnected voltage detection line 105 is connected is the difference between the voltage data V (CH1) at the voltage detection point V1 and the voltage data V (CH2) at the voltage detection point V2, that is, V ( Since it is obtained from CH1) −V (CH2), if the former is approximately 0V, the voltage across the both ends becomes negative. Usually, since the voltage across the battery module 103 does not become negative, the arithmetic circuit can determine that the voltage detection line 105 is disconnected.

Japanese Patent No. 3696124

  According to the voltage detection circuit of the assembled battery, the disconnection of the voltage detection line 105 can be determined, so that high reliability is surely obtained. However, both ends of the battery module 103 are always connected via the voltage dividing resistors 109 and 113. Since it is connected to the ground, it is in a state of being always discharged, though slightly. At this time, as in the configuration of FIG. 5, even if the battery module 103 has a large storage capacity, even if the discharge amount is not a problem, the storage element has excellent rapid charge / discharge characteristics, such as an electric double layer capacitor. In the case where a regenerative electric power can be efficiently recovered while using a battery having a small storage capacity, there has been a problem that the voltage balance of the storage element is lost due to constant discharge.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a power storage device that can reduce a voltage balance shift due to discharge from a power storage element and can detect disconnection.

  In order to solve the conventional problems, a power storage device of the present invention includes a plurality of power storage elements connected in series, a capacitor electrically connected to every other end of the power storage element, and the power storage element. And a voltage detection line that is electrically connected to both ends of the battery by a voltage detection line and detects a voltage of the power storage element (Vi: i = 1 to n, where n is a series number of the power storage elements). A control circuit connected to the storage device, wherein the control circuit obtains a change width (ΔVi) of the voltage (Vi) of each storage element during a predetermined period (Δt) during charging and discharging of the storage element, It is determined that the voltage detection line between the power storage element having a change width (ΔVi) equal to or less than a predetermined value (ΔVs) and the voltage detection circuit is disconnected.

  The power storage device of the present invention includes a plurality of power storage elements connected in series, a first capacitor electrically connected to every other end of the power storage element, and the first capacitor being disconnected. A second capacitor having a capacitance value larger than that of the first capacitor is electrically connected to both ends of the storage element, and is electrically connected to both ends of the storage element through voltage detection lines, and the voltage (Vi : I = 1 to n, where n is the series number of the storage elements), and a control circuit electrically connected to the voltage detection circuit, the control circuit including the storage element When charging / discharging, a change width (ΔVi) of the voltage (Vi) of each storage element in a predetermined period (Δt) is obtained, and the storage element in which the change width (ΔVi) is equal to or less than a predetermined value (ΔVs); The voltage detection line to and from the voltage detection circuit It is obtained so as to determine that the disconnected.

  According to the power storage device of the present invention, a voltage detection circuit and a circuit configuration using only a capacitor electrically connected to both ends of every other storage element, or a voltage detection circuit and every other storage element. The disconnection is determined by the circuit configuration using only the first capacitor electrically connected to both ends and the second capacitor electrically connected to both ends of the storage element to which the first capacitor is not connected. There is almost no deviation in voltage balance due to the charge taken out from the storage element. Therefore, it is possible to detect disconnection while balancing the voltage of the storage element.

1 is a block circuit diagram of a power storage device according to Embodiment 1 of the present invention. It is a partial circuit diagram at the time of disconnection of the electrical storage apparatus in Embodiment 1 of this invention, (a) is a block circuit diagram, (b) is an equivalent circuit diagram It is a partial circuit diagram at the time of disconnection of the other part of the electrical storage apparatus in Embodiment 1 of this invention, (a) is a block circuit diagram, (b) is an equivalent circuit diagram It is a partial circuit diagram at the time of disconnection of the electrical storage apparatus in Embodiment 2 of this invention, (a) is a block circuit diagram, (b) is an equivalent circuit diagram Circuit diagram of conventional voltage detection circuit

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Here, a case where the power storage device is applied to an idling stop vehicle with a regeneration function will be described.

(Embodiment 1)
1 is a block circuit diagram of a power storage device according to Embodiment 1 of the present invention. 2A and 2B are partial circuit diagrams when the power storage device according to the first embodiment of the present invention is disconnected. FIG. 2A is a block circuit diagram, and FIG. 2B is an equivalent circuit diagram. 3A and 3B are partial circuit diagrams of the other part of the power storage device according to Embodiment 1 of the present invention when disconnected, where FIG. 3A is a block circuit diagram and FIG. 3B is an equivalent circuit diagram. In FIG. 1 to FIG. 3, a thick line indicates a power system wiring, and a thin line indicates a signal system wiring.

  In FIG. 1, a generator 11 mounted on a vehicle and a main power supply 13 are electrically connected to a power storage device 17 via a charge / discharge circuit 15. Therefore, the charging / discharging circuit 15 controls charging / discharging of the regenerative power with respect to the power storage device 17. The charge / discharge circuit 15 is also electrically connected to a load 19 that is an auxiliary machine of the vehicle. The main power supply 13 is a lead battery.

  Next, the configuration of the power storage device 17 will be described. An electric double layer capacitor is used for the storage element 21 for storing the regenerative power. The storage element 21 uses a plurality of elements having the same electrical characteristics such as a capacitance value and a rated voltage within a standard range, and is connected in series by power system wiring. Here, 15 power storage elements 21 are connected in series by a metal plate-like bus bar (not shown). At both ends of the series connection body of the storage elements 21, the positive electrode side is connected to the charge / discharge circuit 15, and the negative electrode side is connected to the ground. The number of power storage elements 21 may be increased or decreased as appropriate according to the required power specifications. Moreover, it is good also as a series-parallel connection according to a required capacitance value. In this case, the storage elements 21 connected in parallel may be handled as one storage element 21 in the following description.

  A capacitor 23 is electrically connected to every other end of the electricity storage element 21. Specifically, in the configuration of FIG. 1, the top storage element 21 directly connected to the charge / discharge circuit 15 is numbered first, and the bottom storage element 21 directly connected to ground is numbered 15. When applied, the capacitors 23 are connected to both ends of the even-numbered (second, fourth,...) Power storage element 21. The capacitance value of the capacitor 23 is smaller than the capacitance value of the power storage element 21, for example, a value smaller by 6 digits or more. As a result, the capacitor 23 is charged instantaneously, the response of disconnection detection described later is improved, and the constant discharge from the power storage element 21 is almost eliminated, so that the amount of charge taken out from the power storage element 21 is minimized. it can.

  Both ends of the storage element 21 are electrically connected to a voltage detection circuit 27 by voltage detection lines 25, respectively. Specifically, it has the following configuration.

  As described above, the power storage elements 21 are connected to each other in series by the bus bar, and a protrusion (not shown) for detecting the voltage of the power storage element 21 is provided on a part of the bus bar. The protrusion is inserted into a terminal hole 30 provided in a circuit board 29 on which a capacitor 23, a voltage detection circuit 27, a control circuit described later, and the like are mounted, and is electrically and mechanically connected by soldering. The terminal hole 30 is provided with a copper foil pattern (not shown), and the other end is wired on the circuit board 29 so as to reach the input terminal 31 of the voltage detection circuit 27. The input terminal 31 and the other end of the copper foil pattern are also electrically and mechanically connected by soldering. Therefore, the voltage detection line 25 is made of the protrusion, the copper foil pattern, and solder for connecting the two.

  With such a configuration, the capacitor 23 can be soldered to the copper foil pattern. As a result, both are electrically and mechanically connected on the circuit board 29. Therefore, it is possible to form the copper foil pattern so that the capacitor 23 is provided at the nearest position where it can be connected to the input terminal 31 of the voltage detection circuit 27. By disposing the capacitor 23 in this way, the distance from the capacitor 23 to the input terminal 31 can be shortened as much as possible. Therefore, disconnection in the copper foil pattern (part of the voltage detection line 25) between the two is possible. Can be greatly reduced.

  Next, the voltage detection circuit 27 will be described. The voltage detection circuit 27 has a configuration in which a voltage difference between adjacent input terminals 31 in FIG. That is, for example, the uppermost input terminal 31 and the lower input terminal 31 in FIG. 1 are connected to an operational amplifier (not shown) within the voltage detection circuit 27, and the operational amplifier obtains the voltage difference. . Accordingly, the voltage difference corresponds to the voltage Vi (i = 1 to n, where n is the series number of the storage elements 21 and n = 15 in the first embodiment) at both ends of the storage element 21. Thus, the voltage Vi of each power storage element 21 can be detected. The voltage detection circuit 27 has a function of sequentially outputting the voltage Vi in response to a control signal cont from a control circuit described later.

  As described above, since the voltage Vi is detected by the operational amplifier built in the voltage detection circuit 27, it is equivalent to the configuration in which the input resistor 33 of the operational amplifier is connected between the adjacent input terminals 31. Become. Therefore, in FIG. 1, the following description will be made assuming that the input resistors 33 are connected between the adjacent input terminals 31. Note that the voltage detection circuit 27 is configured so that the resistance values of the input resistors 33 are substantially equal in order to equalize the charge carry-out from the power storage elements 21. As a result, the input currents from the respective storage elements 21 to the voltage detection circuit 27 are substantially equal, and the voltage balance deviation can be reduced. Here, “substantially equal” is defined to mean equal within an error range of the resistance value of the input resistor 33.

  A balance circuit 35 is electrically connected to both ends of each power storage element 21. The balance circuit 35 is a circuit for adjusting the voltage Vi of the power storage element 21 and is configured by a series circuit of a switch 37 and a resistor 39 as shown in FIG. Therefore, when the switch 37 of the balance circuit 35 is turned on, the resistor 39 is connected to both ends of the power storage element 21 to which the balance circuit 35 is connected, so that the voltage Vi of the power storage element 21 is lowered. Can be adjusted. In this way, it is possible to reduce the variation in the voltage Vi of each power storage element 21 and achieve equalization. In the first embodiment, the balance circuit 35 is provided separately from the circuit board 29, but this may be integrated by mounting a switch 37 and a resistor 39 on the circuit board 29.

  A control circuit 41 is electrically connected to the voltage detection circuit 27 and the balance circuit 35 through signal wiring. The control circuit 41 includes a microcomputer and peripheral circuits, and all of these components are solder-mounted with the copper foil pattern on the circuit board 29. The control circuit 41 reads the voltage Vi from the voltage detection circuit 27 and outputs a control signal cont such as a voltage detection request to the voltage detection circuit 27. Further, the balance circuit 35 is controlled by outputting an on / off signal SWi (i = 1 to n) to the switch 37 of each balance circuit 35. The control circuit 41 is also connected to a vehicle-side control circuit (not shown) by signal wiring, and exchanges various data signals data indicating the control and state of the power storage device 17.

  Next, the operation of the power storage device 17 will be described.

  First, the operation of the power storage device 17 during normal vehicle use will be described. When the vehicle is braked from the running state, the generator 11 generates regenerative power. The vehicle side control circuit controls the charge / discharge circuit 15 in order to charge the regenerative power to the power storage device 17. As a result, the regenerative power is charged in each power storage element 21 of the power storage device 17. At this time, the control circuit 41 transmits a control signal cont to the voltage detection circuit 27 so as to detect the voltage Vi of each storage element 21. In response to this, the voltage detection circuit 27 outputs the voltage Vi to the control circuit. From the voltage Vi thus obtained, the control circuit 41 obtains the total voltage Vc of the storage element 21 and outputs it as the data signal data to the vehicle side control circuit. The vehicle-side control circuit compares the total voltage Vc with a preset full charge voltage (for example, if the upper limit voltage of each storage element 21 is 2 V, the full charge voltage is 2 V × 15 = 30 V from n = 15). When the total voltage Vc reaches the full charge voltage, the charging / discharging circuit 15 is controlled to stop charging. As a result, the regenerative power is charged in the power storage device 17 until the total voltage Vc of the power storage element 21 reaches the full charge voltage. If the generation of the regenerative power is completed before the total voltage Vc reaches the full charge voltage, the charging of the power storage device 17 is also terminated at that time.

  Thereafter, when the vehicle stops, the engine stops and the idling stop state is set. In the meantime, the power consumed by the load 19 is supplied from the main power supply 13, but the charge / discharge circuit 15 may be controlled so as to supply the regenerative power stored in the power storage device 17.

  Next, when the driver depresses the accelerator and performs an operation of causing the vehicle to re-run, the vehicle-side control circuit supplies the regenerative power stored in the power storage device 17 to the starter connected to the engine. To control. Here, the starter is not explicitly shown in FIG. 1, but it may be a part of the load 19 or may be configured to operate the generator 11 as a starter.

  By repeating the above operation, the regenerative electric power stored in the power storage device 17 can be used for restarting the engine, so that a highly efficient and fuel-saving vehicle can be realized.

  Next, the voltage detection operation of the power storage device 17 and the voltage equalization operation of each power storage element 21 will be described.

  First, the control circuit 41 transmits a control signal cont to the voltage detection circuit 27 so as to detect the voltage Vi when the storage element 21 is not charged or discharged. In response to this, the voltage detection circuit 27 sequentially detects the voltage Vi of each storage element 21 and outputs it to the control circuit 41. When the reception of the voltage Vi of each storage element 21 is completed, the control circuit 41 obtains the minimum value Vmin of the voltage Vi, and an on / off signal to turn on the switch 37 until the voltages Vi of all the storage elements 21 become the minimum value Vmin. SWi is output. Note that the switch 37 connected to the power storage element 21 having the minimum value Vmin is kept off because the voltage Vi is already equal to the minimum value Vmin.

  By such an operation, the switch 39 is on at both ends of the power storage element 21 having the voltage Vi higher than the minimum value Vmin, so that the resistor 39 is connected. As a result, a current flows from the storage element 21 to the resistor 39, and the voltage Vi decreases.

  The control circuit 41 continues to detect the voltage Vi of each power storage element 21 by the voltage detection circuit 27 even after the switch 37 is turned on. When the voltage Vi reaches the minimum value Vmin, the switch 37 connected to the power storage element 21 is detected. Turn off. By repeating such an operation, the voltage Vi of all the storage elements 21 can be equalized to the minimum value Vmin.

  Here, the voltage Vi is continuously detected, and equalization is performed by performing control to turn on the switch 37 until the target voltage (minimum value Vmin) is reached, but this is performed as follows. You may equalize. First, the correlation of the ON period of the switch 37 with respect to the voltage difference between the voltage Vi and the minimum value Vmin is obtained in advance. Here, the correlation is such that the ON period is longer as the voltage difference is larger. Next, when equalization is performed, the ON period is determined from the voltage difference and the correlation, and control is performed so that the switch 37 is kept on during that period. Thereby, equalization is possible even if the control circuit 41 does not continue to detect the voltage Vi.

  Next, the disconnection detection operation of the voltage detection line 25 in the power storage device 17 will be described. The disconnection detection operation is appropriately executed by the control circuit 41 when the storage element 21 is charged / discharged.

  First, the control circuit 41 transmits a control signal cont to the voltage detection circuit 27 so as to detect the voltage Vi when the storage element 21 is charged / discharged. In response to this, the voltage detection circuit 27 sequentially outputs the voltages Vi across the respective storage elements 21 to the control circuit 41 to the control circuit 41, so that the control circuit 41 reads the voltages Vi.

  After that, the control circuit 41 reads each voltage Vi from the voltage detection circuit 27 again by the above operation after the predetermined period Δt has elapsed. Here, the predetermined period Δt is determined as follows. If the predetermined period Δt is set too long, when the charging / discharging of the storage element 21 stops within the predetermined period Δt or the charging and discharging are reversed, the change width ΔVi of the voltage Vi before and after the elapse of the predetermined period Δt (the predetermined period Δt The absolute value of the difference between the voltage Vi before elapse of time and the voltage Vi after elapse) becomes smaller. Even if the predetermined period Δt is set too short, the change width ΔVi generally decreases. As a result, as will be described later, since it is determined that the voltage detection line 25 connected to the storage element 21 having the change width ΔVi equal to or less than the predetermined value ΔVs is disconnected, the predetermined period Δt is too short or too long. There is a possibility that the change width ΔVi is calculated to be small, and an accurate disconnection determination cannot be made. Therefore, the predetermined period Δt is determined in advance from the charge / discharge characteristics of the power storage device 17 as a period during which charging / discharging continues and a sufficient change width ΔVi is obtained. In the first embodiment, the predetermined period Δt is 0.1 seconds.

  The control circuit 41 calculates the change width ΔVi of the voltage Vi before and after the elapse of the predetermined period Δt, and then compares each change width ΔVi with the predetermined value ΔVs. Here, the predetermined value ΔVs is determined in advance as a value smaller than the minimum value of the normal change width ΔVi assumed based on the charge / discharge characteristics of the power storage device 17. Therefore, if the change width ΔVi is smaller than the predetermined value ΔVs, it can be determined that the voltage change associated with charging / discharging of the storage element 21 is not transmitted to the voltage detection circuit 27 and the voltage detection line 25 is disconnected. Here, in the first embodiment, the maximum value of the detection error of the voltage detection circuit 27 is used as the predetermined value ΔVs. This is because the maximum value of the detection error is smaller than the minimum value of the change width ΔVi. The maximum value of the detection error is experimentally obtained in advance and stored in a memory built in the control circuit 41. The predetermined value ΔVs is not limited to the maximum value of the detection error of the voltage detection circuit 27, but may be determined as a value obtained by adding a margin to the maximum value of the detection error, or an assumed change width ΔVi. What is necessary is just to determine suitably in the range which can judge a disconnection, such as determining as a value which considered the detection error and the margin to the minimum value of this.

  From these facts, when the change width ΔVi is larger than the predetermined value ΔVs, that is, here, larger than the maximum value of the detection error of the voltage detection circuit 27, the change width ΔVi in the voltage Vi of the storage element 21 due to charging / discharging is obtained correctly. Will be. Therefore, the control circuit 41 determines that the voltage detection line 25 of the storage element 21 is not broken.

  On the other hand, the case where it is disconnected will be described in detail with reference to FIG. FIG. 2A is a partially enlarged view of the storage element 21, the capacitor 23, the voltage detection line 25, the voltage detection circuit 27, and the balance circuit 35. In FIG. 2A, the eleventh and twelfth elements of the 15 storage elements 21 counted from the storage element 21 connected to the charge / discharge circuit 15 are shown as an example. Therefore, since the capacitor 23 is connected to both ends of the even-numbered power storage element 21 as described above, it is connected to both ends of the twelfth power storage element 21 in FIG.

  In such a storage element 21, the voltage across the voltage detection line 25 before the disconnection occurs is the voltage V11b for the eleventh storage element 21 and the voltage V12b for the twelfth storage element 21. Suppose.

  If the storage element 21 is charged in this state, the voltages V11b and V12b increase with time. At this time, since the capacitance value of the capacitor 23 is extremely smaller than the capacitance value of the electricity storage element 21 as described above, the voltage across the capacitor 23 becomes equal to the voltage V12b.

  Assume that the voltage detection line 25 is disconnected at the mark x in FIG. Note that, as described above, the voltage detection line 25 is composed of the protrusion on the bus bar, the copper foil pattern on the circuit board 29, and the solder that connects the two. The soldered portion with the copper foil pattern formed in the terminal hole 30 is probabilistically high. That is, since the power storage device 17 is mounted on the vehicle, the vibration concentrates on the soldered portion of the protrusion, causing solder peeling, or peeling of the copper foil pattern portion soldered to the protrusion occurs. Cheap. On the other hand, since the input terminal 31 and the capacitor 23 of the voltage detection circuit 27 are solder-mounted on the copper foil pattern formed on the circuit board 29, the probability of occurrence of disconnection due to the concentration of vibrations at that portion is small.

  FIG. 2B shows an equivalent circuit diagram when a disconnection occurs at the mark “X” in FIG. Both ends of the capacitor 23 are connected only to both ends of the input resistor 33 of the voltage detection circuit 27. Here, since the time constant determined by the resistance value of the input resistor 33 and the capacitance value of the capacitor 23 is configured to be sufficiently large with respect to the predetermined period Δt, the time constant of the capacitor 23 during the predetermined period Δt. Fluctuations in voltage at both ends are small. Therefore, the voltage across the capacitor 23 immediately after the disconnection maintains the voltage V12b of the storage element 21 immediately before the disconnection, and is smaller than the voltage V12a of the twelfth storage element 21 that has risen due to the subsequent charging after the disconnection. Become. Note that the voltage of the eleventh power storage element 21 after the disconnection is V11a.

  In this state, when the control circuit 41 performs the disconnection detection operation, as shown in FIG. 2B, the voltage detection circuit 27 outputs the voltage V11a + V12a as the voltage of the eleventh power storage element 21, and the twelfth power storage element. The voltage 21 is output because the capacitor 23 maintains the voltage V12b immediately before the disconnection as described above.

  Thereafter, when the predetermined period Δt elapses and the voltage detection circuit 27 detects the voltage Vi again, the voltage of the eleventh storage element 21 is charged with the eleventh and 12th after being charged during the predetermined period Δt. The total voltage V11a + V12a of the 12th power storage element 21 is output. As the voltage of the 12th power storage element 21, the voltage across the capacitor 23 hardly changes in a short period of about the predetermined period Δt, so the voltage V12b is output again.

  Thereafter, the control circuit 41 calculates the change width ΔVi, and the change width ΔV11 of the eleventh power storage element 21 is the change width of the total voltage V11a + V12a of the eleventh and twelfth power storage elements 21 before and after the lapse of the predetermined period Δt. Become. Since the change width ΔV11 is the sum of the change widths of the two power storage elements 21, it is larger than the change width ΔVi of the other power storage elements 21 without disconnection. In particular, when 15 power storage elements 21 having the same characteristics are used as in the first embodiment, the change width ΔV11 is approximately twice as large as the change width ΔVi of other power storage elements 21 without disconnection. .

  On the other hand, the voltage across the capacitor 23 is input to the voltage detection circuit 27 as the voltage of the twelfth storage element 21, and the voltage V12b remains almost unchanged before and after the lapse of the predetermined period Δt. 0V.

  From these things, the control circuit 41 judges a disconnection as follows. First, since the change width ΔV12 is equal to or less than the predetermined value ΔVs, it is determined that the voltage detection line 25 between the twelfth storage element 21 and the voltage detection circuit 27 is disconnected.

  Since this result is transmitted from the control circuit 41 to the vehicle-side control circuit as a data signal data, the vehicle-side control circuit can inform the driver of a disconnection failure of the power storage device 17 and can ensure high reliability. It becomes. Further, by determining the disconnection of the voltage detection line 25 in this way, it is possible to reduce the discharge from the power storage element 21 for determining the disconnection compared to the conventional case.

  However, at this stage, it is impossible to distinguish which of the two voltage detection lines 25 connected to both ends of the twelfth storage element 21 is broken.

  Therefore, the control circuit 41 is referred to as two power storage elements 21 (hereinafter referred to as adjacent power storage elements) connected to both sides of a twelfth power storage element 21 (hereinafter referred to as a disconnected power storage element) whose change width ΔV12 is equal to or less than a predetermined value ΔVs. Here, the respective change widths ΔV11 and ΔV13 in the eleventh and thirteenth power storage elements 21) are compared. Here, although the thirteenth power storage element 21 is not shown in FIG. 2, a normal change width ΔV <b> 13 is obtained because no disconnection occurs. On the other hand, as described above, the change width ΔV11 is approximately twice as large as the change width ΔV13 of the other power storage elements 21 without disconnection. For these reasons, the change width ΔV11 in the eleventh power storage element 21 is larger than the predetermined value ΔVs, but is larger than the normal change width ΔV13. Therefore, a voltage detection circuit from a connection point between the adjacent storage element (11th storage element 21) having a large value among the change widths ΔV11 and ΔV13 of the adjacent storage element and the disconnected storage element (12th storage element 21). It is determined that the voltage detection lines 25 connected up to 27 are disconnected. Thereby, it is possible to distinguish which voltage detection line 25 is disconnected. The control circuit 41 transmits this information to the vehicle-side control circuit with the data signal data, so that not only the driver is informed of the disconnection failure but also the location where the disconnection has occurred, so the time and cost required for repair can be reduced. Can be reduced.

  The disconnected voltage detection line 25 in FIG. 2 is on the high voltage side of the capacitor 23 (the positive side of the twelfth storage element 21), but on the low voltage side of the capacitor 23 (the negative side of the twelfth storage element 21). A case where the voltage detection line 25 is disconnected will be described with reference to FIG. The disconnection of the voltage detection line 25 is assumed to have occurred in the path from the connection point of the twelfth storage element 21 and the thirteenth storage element 21 to the voltage detection circuit 27, as indicated by a cross in FIG. . In this case, as shown in FIG. 3B, an equivalent circuit is a circuit in which another input resistor 33 is connected in series to a parallel circuit of a capacitor 23 and an input resistor 33, and the twelfth and thirteenth storage elements 21. Are connected to both ends of the series circuit. Therefore, when the disconnection as shown in FIG. 3A occurs, the voltage across the capacitor 23 maintains the voltage V12b of the twelfth storage element 21 immediately before the disconnection, as in FIG. On the other hand, the voltage across the input resistor 33 connected to both ends of the thirteenth storage element 21 is the total voltage V12a + V13a of the twelfth and thirteenth storage elements 21 after the disconnection. As a result, for the twelfth power storage element 21, the voltage V12b remains almost unchanged before and after the elapse of the predetermined period Δt, so that the change width ΔV12 is almost 0V. On the other hand, for the thirteenth power storage element 21, the change width ΔV13 before and after the elapse of the predetermined period Δt is approximately twice as large as the change width ΔVi of the other power storage elements 21 without disconnection. Therefore, since the change width ΔV12 is equal to or less than the predetermined value ΔVs, it can be determined that the voltage detection line 25 between the twelfth storage element 21 and the voltage detection circuit 27 is disconnected, and further, the disconnection storage element (here, Among the change widths ΔV11 and ΔV13 in the adjacent storage elements (herein, the eleventh and thirteenth storage elements 21) of the twelfth storage element 21), ΔV13 is large, so the thirteenth storage element 21 and the twelfth storage element It can be specified that the voltage detection line 25 from the connection point 21 to the voltage detection circuit 27 is broken.

  Therefore, even when the voltage detection line 25 on the low voltage side of the capacitor 23 is disconnected as shown in FIG. 3, the disconnection can be determined in the same manner as in FIG.

  When the voltage detection line 25 on the positive electrode side in the first power storage element 21 is disconnected, one end of the input resistor 33 is in an electrically floating state. Therefore, since the change width ΔV1 is almost 0, a disconnection can be determined. Similarly, when the voltage detection line 25 on the negative electrode side of the ground-side (15th) power storage element 21 is disconnected, one end of the input resistor 33 is in an electrically floating state, and the change width ΔV15 becomes almost zero. Therefore, disconnection of the voltage detection line 25 connected to the ground can also be determined.

  Next, when the control circuit 41 determines that any one of the voltage detection lines 25 is disconnected as described above, the control circuit 41 immediately turns off each switch 37 and stops the operation of the balance circuit 35. As a result, it is possible to reduce the possibility that the voltage Vi varies on the contrary by performing the equalization of the storage elements 21 with the erroneous voltage Vi due to the disconnection.

  With the above-described configuration and operation, the resistance values of the capacitors 23 electrically connected to both ends of every other storage element 21 as the disconnection determination circuit and the input resistors 33 connected to each storage element 21 are substantially equal. By using the voltage detection circuit 27, the power storage device 17 capable of detecting disconnection while reducing the deviation of the voltage balance due to the discharge from the power storage element 21 can be realized.

  In the first embodiment, the capacitor 23 is provided on the circuit board 29 at the closest position connectable to the input terminal 31. This is due to the following reason.

  If the voltage detection line 25 is disconnected between the capacitor 23 and the input terminal 31, the sum of the voltages at both ends of the two storage elements 21 connected to the disconnected voltage detection line 25 is The voltage is applied to both ends of the series circuit of the two input resistors 33 connected to the storage element 21. Since the resistance values of the input resistors 33 are substantially equal, the voltage at the connection point of the two input resistors 33 (the portion where the disconnected voltage detection line 25 was connected) is about half of the sum of the voltages at both ends. As described above, the voltage is equivalent to the case where the voltage detection line 25 is not disconnected because the characteristics of the respective storage elements 21 are aligned as described above. As a result, although the voltage detection line 25 is actually disconnected, the voltage Vi is detected in the correct range, so that the disconnection determination cannot be performed. That is, according to the first embodiment, it is not possible to detect a disconnection between the capacitor 23 and the input terminal 31. Therefore, in order to reduce the possibility of the disconnection, the capacitor 23 is mounted and arranged as close as possible to the input terminal 31.

(Embodiment 2)
4A and 4B are partial circuit diagrams when the power storage device according to the second embodiment of the present invention is disconnected. FIG. 4A is a block circuit diagram, and FIG. 4B is an equivalent circuit diagram. In FIG. 4, the thick line indicates the power system wiring, and the thin line indicates the signal system wiring.

  In the configuration of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. That is, the characteristic configuration of the second embodiment is that, as shown in FIG. 4A, the first capacitor 51 is electrically connected to both ends of every other storage element 21, and the first capacitor 51 is also connected. Is that the second capacitor 53 is electrically connected to both ends of the unconnected storage element 21. Here, the capacitance value of the second capacitor 53 is larger than the capacitance value of the first capacitor 51. Specifically, the second capacitor 53 has a capacitance value that is one digit larger than the capacitance value of the first capacitor 51. The first capacitor 51 is the same as the capacitor 23 described in the first embodiment. Accordingly, the voltage across the first capacitor 51 follows very rapidly according to the change in the voltage Vi of the power storage element 21 connected to both ends of the first capacitor 51, but the voltage across the second capacitor 53 is equal to the second voltage. This slowly follows the change in voltage Vi of the storage element 21 connected to both ends of the capacitor 53.

  Further, as in the first embodiment, the capacitance values of the first capacitor 51 and the second capacitor 53 are both extremely smaller than the capacitance value per one storage element 21. That is, as described in the first embodiment, the capacitance value of the capacitor 23 is smaller by 6 digits or more than the capacitance value of the electricity storage element 21, and therefore the capacitance value of the first capacitor 51 that is the same as the capacitor 23 is also equal to the electricity storage element. It is 6 digits or more smaller than the capacity value of 21. On the other hand, since the second capacitor 53 has a capacitance value that is one digit larger than the capacitance value of the first capacitor 51, the second capacitor 53 has a capacitance value that is five digits or less smaller than the capacitance value of the storage element 21. Will have.

  Next, the characteristic operation of the power storage device 17 will be described.

  Now, let us assume that the portion indicated by the cross in FIG. At this time, since the first capacitor 51 has a small capacitance value, the voltage between both ends thereof becomes the both-ends voltage V12b of the storage element 21 immediately before the disconnection as described in the first embodiment. On the other hand, the capacitance value of the second capacitor 53 is an order of magnitude larger than the capacitance value of the first capacitor 51, so that the follow-up to the voltage change of the storage element 21 is slow. Therefore, when the disconnection occurs, the second capacitor 53 is not fully charged, and the voltage between both ends is V11a + V12a as shown in FIG. 4B. This is the same behavior as in the first embodiment. Therefore, even in a circuit configuration in which the second capacitor 53 is added to the first embodiment, disconnection can be detected in the same manner as in the first embodiment.

  4 describes the disconnection when the first capacitor 51 is disposed below the second capacitor 53, but the disconnection occurs when the positions of the first capacitor 51 and the second capacitor 53 are reversed. Can also be detected in the same manner as in FIG. 3 of the first embodiment.

  In order to detect the disconnection in this way, in the second embodiment, the capacitance value of the second capacitor 53 is set to be one digit larger than the capacitance value of the first capacitor 51. The required capacitance value of the two capacitors 53 varies depending on the predetermined period Δt (also in the second embodiment, 0.1 second as in the first embodiment). That is, when the capacitance value of the second capacitor 53 decreases, the voltage behavior of the first capacitor 51 at the time of disconnection approaches, so the accuracy of disconnection detection decreases. On the other hand, if the capacitance value of the second capacitor 53 is increased too much, the change in the voltage across the second capacitor 53 during the predetermined period Δt becomes small, and the accuracy of disconnection detection also decreases. Furthermore, there is a possibility that the charge from the power storage element 21 is increased and the voltage balance is lost. Therefore, the optimum capacitance values of the first capacitor 51 and the second capacitor 53 may be determined according to the predetermined period Δt.

  Operations other than the above are the same as those in the first embodiment.

  With the above configuration and operation, the first capacitor 51 that is electrically connected to every other end of the electricity storage element 21 as a disconnection determination circuit, and the both ends of the electricity storage element 21 that is not connected to the first capacitor 51 are electrically connected. By using the voltage detection circuit 27 in which the resistance values of the connected second capacitors 53 and the input resistors 33 connected to the respective storage elements 21 are substantially equal, the voltage balance shift due to the discharge from the storage elements 21. Thus, it is possible to realize the power storage device 17 capable of detecting disconnection while reducing the power consumption.

  In the second embodiment, as in the first embodiment, the first capacitor 51 and the second capacitor 53 are provided at the nearest position where the input terminal 31 of the voltage detection circuit 27 can be connected. Thereby, the possibility of disconnection between the first capacitor 51 and the second capacitor 53 and the input terminal 31 can be reduced.

  Moreover, although Embodiment 1 and 2 demonstrated disconnection detection operation | movement during the charge of the electrical storage element 21, this may be during discharge. However, when charging and discharging are switched before and after the elapse of the predetermined period Δt, there is a possibility that correct disconnection determination cannot be performed, so the control circuit 41 stops the disconnection determination operation. For these reasons, the disconnection detection operation needs to be performed during continuous charging or continuous discharging. The switching between charging and discharging can be known from the data signal data from the vehicle side control circuit.

  In the first and second embodiments, the resistance value of the input resistor 33 is configured to be substantially equal. However, the resistance value is sufficiently large, and the charge from each power storage element 21 to the input resistor 33 is reduced. When the carry-out (discharge) can be ignored, the voltage balance hardly shifts, so that the resistance values may not be equal.

  In the first and second embodiments, since there is a low possibility that a plurality of voltage detection lines 25 are disconnected at the same time, the disconnection determination is performed on the assumption that the disconnection occurs only at one location.

  In the first and second embodiments, the electric double layer capacitor is used for the power storage element 21, but this may be a large-capacity capacitor such as an electrochemical capacitor or a secondary battery.

  Moreover, in Embodiment 1, 2, although the case where the electrical storage apparatus 17 was applied to the idling stop vehicle was demonstrated, not only this but a some electrical storage element is connected in series like a hybrid vehicle, a construction machine, etc. You may apply to an electrical storage apparatus.

  The power storage device according to the present invention is useful as a power storage device or the like having a configuration in which a plurality of power storage elements are connected in series because the disconnection can be detected by reducing discharge from the power storage elements.

Reference Signs List 17 power storage device 21 power storage element 23 capacitor 25 voltage detection line 27 voltage detection circuit 31 input terminal 35 balance circuit 41 control circuit 51 first capacitor 53 second capacitor

Claims (9)

A plurality of power storage elements connected in series;
A capacitor electrically connected to every other end of the storage element;
A voltage detection circuit that is electrically connected to both ends of the power storage element by a voltage detection line and detects a voltage of the power storage element (Vi: i = 1 to n, n is a series number of the power storage elements);
A control circuit electrically connected to the voltage detection circuit,
The control circuit obtains a change width (ΔVi) of the voltage (Vi) of each storage element in a predetermined period (Δt) during charging and discharging of the storage element,
A power storage device configured to determine that the voltage detection line between the power storage element having the change width (ΔVi) equal to or less than a predetermined value (ΔVs) and the voltage detection circuit is disconnected. The power storage device according to claim 1, wherein a capacity value of the capacitor is smaller than a capacity value per one of the power storage elements. The power storage device according to claim 1, wherein the capacitor is provided at a closest position connectable to an input terminal of the voltage detection circuit. A plurality of power storage elements connected in series;
A first capacitor electrically connected to every other end of the storage element;
A second capacitor having a capacitance value larger than that of the first capacitor, the first capacitor being electrically connected to both ends of the non-connected storage element;
A voltage detection circuit that is electrically connected to both ends of the power storage element by a voltage detection line and detects a voltage of the power storage element (Vi: i = 1 to n, n is a series number of the power storage elements);
A control circuit electrically connected to the voltage detection circuit,
The control circuit obtains a change width (ΔVi) of the voltage (Vi) of each storage element in a predetermined period (Δt) during charging and discharging of the storage element,
A power storage device configured to determine that the voltage detection line between the power storage element having the change width (ΔVi) equal to or less than a predetermined value (ΔVs) and the voltage detection circuit is disconnected. 5. The power storage device according to claim 4, wherein capacitance values of the first capacitor and the second capacitor are both smaller than a capacitance value per one of the power storage elements. 5. The power storage device according to claim 4, wherein the first capacitor and the second capacitor are provided at a closest position connectable to an input terminal of the voltage detection circuit. The control circuit sets a larger value among the change widths (ΔVi) of the two adjacent storage elements connected to both sides of the disconnected storage element whose change width (ΔVi) is equal to or less than the predetermined value (ΔVs). The power storage device according to claim 1, wherein the voltage detection line from the connection point between the adjacent power storage element and the disconnected power storage element to the voltage detection circuit is determined to be disconnected. A balance circuit that is electrically connected to both ends of the power storage element and the control circuit and equalizes the voltage (Vi);
5. The power storage device according to claim 1, wherein when the control circuit determines that the voltage detection line is disconnected, the control circuit stops the operation of the balance circuit. 6. The power storage device according to claim 1, wherein input currents from the power storage elements to the voltage detection circuit are substantially equal.

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