JP2015061504A - Power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress heat generation of a current limiting resistor, while reducing voltage applied between terminals of a current limiter, when the current limiter of a power storage element is operated.SOLUTION: A power storage system has a power storage device and first to third relays. The power storage device has a plurality of power storage elements which are connected in series, and each of the power storage elements has a current limiter for blocking a current path in the power storage element. The first relay is arranged in a positive pole line of the power storage device and the second relay is arranged in a negative pole line of the power storage device. A plurality of smoothing capacitors are connected in series between the positive pole line and the negative pole line. An intermediate line is connected to a connection point of two power storage elements and a connection point of the plurality of the smoothing capacitors, and the third relay is arranged in the intermediate line. A current limiting resistor and a fourth relay are connected in series with each other and connected in parallel to the first and second relays respectively or to the third relay.

Description

  The present invention relates to a power storage system including a power storage device in which a plurality of power storage elements are connected in series, and each power storage element includes a current breaker.

  In Patent Document 1, by providing an intermediate line in addition to the positive electrode line and the negative electrode line, the voltage applied between the terminals of the current breaker is reduced when the current breaker included in the storage element is activated. I have to.

International Publication No. 2013/061358 Pamphlet JP 2012-202723 A

  In Patent Document 1, since the current continues to flow through the current limiting resistor provided in the intermediate line, the heat generation of the current limiting resistor must be monitored.

  The power storage system according to the present invention includes a power storage device and first to third relays. The power storage device includes a plurality of power storage elements connected in series, and each power storage element includes a current breaker that interrupts a current path inside the power storage element. The first relay is disposed on a positive line connecting the positive terminal of the power storage device to the load, and the second relay is disposed on a negative line connecting the negative terminal of the power storage device to the load.

  A plurality of smoothing capacitors are connected in series between the positive electrode line and the negative electrode line. An intermediate line is connected to the connection point of the two power storage elements included in the power storage device and the connection point of the plurality of smoothing capacitors, and the third relay is disposed on the intermediate line. The current limiting resistor and the fourth relay are connected in series to each other, and are connected in parallel to each of the first relay and the second relay, or to the third relay.

  According to the present invention, similarly to Patent Document 1, by using the intermediate line, the voltage applied between the terminals of the current breaker in the operating state can be reduced. In addition, by using the fourth relay, it is possible to prevent the current from continuing to flow through the current limiting resistor and to suppress the heat generation of the current limiting resistor.

It is a figure which shows the structure of the battery system which is Example 1. FIG. It is a figure which shows the structure of a cell. 6 is a flowchart illustrating processing according to turning on an ignition switch in the first embodiment. It is a figure which shows the structure of the battery system which is Example 2. FIG. In Example 2, it is a flowchart explaining the process according to ON of an ignition switch.

  Examples of the present invention will be described below.

  A battery system (corresponding to the power storage system of the present invention) that is Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram showing a configuration of a battery system.

  The battery system of this embodiment is mounted on a vehicle. The vehicle includes a hybrid vehicle and an electric vehicle. The hybrid vehicle includes an engine or a fuel cell in addition to the assembled battery as a power source for running the vehicle. An electric vehicle includes only an assembled battery as a power source for running the vehicle.

  The assembled battery (corresponding to the power storage device of the present invention) 10 has a plurality of single cells (corresponding to the power storage element of the present invention) 11 connected in series. As the cell 11, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor (capacitor) can be used instead of the secondary battery. The number of unit cells 11 can be appropriately set in consideration of the required output of the assembled battery 10 and the like. In the present embodiment, the plurality of single cells 11 are connected in series, but the plurality of single cells 11 connected in parallel may be included in the assembled battery 10.

  System main relay (corresponding to the first relay of the present invention) SMR-B is arranged on positive line PL connected to the positive terminal of battery pack 10. System main relay SMR-B receives control signal B from controller 50 and switches between on and off. The current limiting resistor R1 and the system main relay (corresponding to the fourth relay of the present invention) SMR-P1 are connected in series to each other and are connected in parallel to the system main relay SMR-B. System main relay SMR-P1 receives control signal P1 from controller 50 and switches between on and off. The current limiting resistor R1 is used to suppress inrush current from flowing through the load when the assembled battery 10 is connected to the load.

  The system main relay (corresponding to the second relay of the present invention) SMR-G is disposed on the negative electrode line NL connected to the negative electrode terminal of the assembled battery 10. System main relay SMR-G receives control signal G from controller 50 and switches between on and off. The current limiting resistor R2 and the system main relay (corresponding to the fourth relay of the present invention) SMR-P2 are connected in series to each other and are connected in parallel to the system main relay SMR-G. System main relay SMR-P2 receives control signal P2 from controller 50 and switches between on and off. The current limiting resistor R2 is used to suppress inrush current from flowing through the load when the assembled battery 10 is connected to the load.

  The controller 50 has a built-in memory 51. The memory 51 stores a program for operating the controller 50 and various information. The memory 51 can also be arranged outside the controller 50.

  The capacitors C1 and C2 are connected in series between the positive electrode line PL and the negative electrode line NL. One end of the capacitor C1 is connected to the positive line PL, and one end of the capacitor C2 is connected to the negative line NL. Capacitors C1 and C2 are used to smooth the current between positive line PL and negative line NL.

  A system main relay (corresponding to the third relay of the present invention) SMR-C is arranged in the intermediate line ML. System main relay SMR-C receives control signal C from controller 50 and switches between on and off.

  One end of the intermediate line ML is connected to a connection point of the first battery group 10A and the second battery group 10B included in the assembled battery 10. The other end of the intermediate line ML is connected to a connection point between the capacitors C1 and C2. Capacitor C1 is connected in parallel with first battery group 10A via positive electrode line PL and intermediate line ML. The capacitor C2 is connected in parallel with the second battery group 10B via the negative electrode line NL and the intermediate line ML.

  The number of single cells 11 included in the first battery group 10A and the second battery group 10B is preferably substantially equal to each other. When the number of the single cells 11 is substantially equal, the case where the number of the single cells 11 is the same and the case where the number of the single cells 11 are slightly different are included.

  The current sensor 61 is disposed on the positive line PL, and the current sensor 62 is disposed on the negative line NL. The controller 50 receives the outputs of the current sensors 61 and 62 and acquires the current values flowing through the positive line PL and the negative line NL. Here, the current value when the assembled battery 10 is discharged can be a negative value, and the current value when the assembled battery 10 is charged can be a positive value.

  The booster circuit 20 boosts the output voltage of the assembled battery 10 and outputs the boosted power to the inverter 30. The step-up circuit 20 can step down the output voltage of the inverter 30 and output the step-down power to the assembled battery 10. The booster circuit 20 includes a reactor 21, diodes 22 and 23, and transistors (npn transistors) 24 and 25 as switching elements. Reactor 21 has one end connected to system main relay SMR-B and the other end connected to a connection point of transistors 24 and 25.

  The transistors 24 and 25 are connected in series, and a control signal from the controller 50 is input to the bases of the transistors 24 and 25. The transistors 24 and 25 are switched between on and off in response to a control signal from the controller 50. Diodes 22 and 23 are connected between the collectors and emitters of the transistors 24 and 25 so that current flows from the emitter side to the collector side, respectively. Specifically, the anodes of the diodes 22 and 23 are connected to the emitters of the transistors 24 and 25, and the cathodes of the diodes 22 and 23 are connected to the collectors of the transistors 24 and 25.

  As the transistors 24 and 25, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used. In place of the npn transistor, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) may be used.

  When the boosting operation of the booster circuit 20 is performed, the controller 50 turns on the transistor 25 and turns off the transistor 24. Thereby, a current flows from the assembled battery 10 to the reactor 21, and magnetic energy corresponding to the amount of current is accumulated in the reactor 21. Next, the controller 50 switches current from the reactor 21 to the inverter 30 via the diode 22 by switching the transistor 25 from on to off. Thereby, the energy accumulated in the reactor 21 is released, and the boosting operation is performed.

  When performing the step-down operation, the controller 50 turns on the transistor 24 and turns off the transistor 25. Thereby, the electric power from the inverter 30 is supplied to the assembled battery 10, and the assembled battery 10 is charged. In this embodiment, the booster circuit 20 is provided, but the booster circuit 20 may be omitted.

  The inverter 30 converts the DC power from the assembled battery 10 into AC power and outputs the AC power to the motor / generator 40. As the motor / generator 40, a three-phase AC motor can be used. Motor generator 40 receives AC power from inverter 30 and generates kinetic energy for running the vehicle. The kinetic energy generated by the motor generator 40 is transmitted to the wheels.

  When the vehicle is decelerated or stopped, the motor generator 40 converts kinetic energy generated during braking of the vehicle into electrical energy. The AC power generated by the motor / generator 40 is output to the assembled battery 10 after being converted into DC power by the inverter 30. The assembled battery 10 can store regenerative power.

  The assembled battery 10 can be charged using power from an external power source. The external power source is a power source disposed outside the vehicle, and for example, a commercial power source can be used as the external power source. When power from an external power source is supplied to the assembled battery 10, a charger can be added to the battery system shown in FIG. When the external power supply supplies AC power, the charger can convert AC power into DC power and supply DC power to the assembled battery 10. When the external power supply supplies DC power, DC power can be supplied to the assembled battery 10.

  FIG. 2 shows the configuration of the unit cell 11. The unit cell 11 includes a power generation element 11 a that charges and discharges, and a current breaker 11 b that blocks a current flowing through the unit cell 11. The power generation element 11a can be composed of, for example, a positive electrode element, a negative electrode element, and a separator disposed between the positive electrode element and the negative electrode element. The positive electrode element has a current collector plate and a positive electrode active material layer, and the negative electrode element has a current collector plate and a negative electrode active material layer. An electrolyte solution is infiltrated into the separator, the positive electrode active material layer, and the negative electrode active material layer. Instead of using the electrolytic solution, a solid electrolyte can also be used.

  The current breaker 11b is built in the unit cell 11, and interrupts the current flowing through the unit cell 11 when the unit cell 11 is in an overcharged state or the like. As the current breaker 11b, for example, a valve that deforms according to the internal pressure of the unit cell 11 can be used. Gas may be generated inside the cell 11 due to overcharging of the cell 11 or the like. Since the internal pressure of the unit cell 11 increases due to the generation of gas, the valve can be deformed as the internal pressure increases. By deforming the valve and mechanically disconnecting the power generation element 11a, the current path flowing through the unit cell 11 can be interrupted.

  The current breaker 11b is not limited to the configuration including the valve described above. In other words, the current breaker 11b only needs to be able to interrupt the current path inside the unit cell 11 in order to avoid an abnormal state of the unit cell 11. For example, a fuse or the like can be used as the current breaker 11b. If a fuse is used, the fuse can be blown when a current of a predetermined value or more flows through the unit cell 11 (fuse).

  The operation of the battery system of the present embodiment will be described using the flowchart shown in FIG. The process shown in FIG. 3 is executed by the controller 50. The process shown in FIG. 3 is executed when the ignition switch of the vehicle is switched from OFF to ON. When the processing shown in FIG. 3 is started, the system main relays SMR-B, SMR-C, SMR-G, SMR-P1, and SMR-P2 are turned off.

  In step S101, the controller 50 determines whether or not there is a request for activation (Ready-ON) of the battery system. When there is a request to start the battery system, the process proceeds to step S102.

  In step S102, the controller 50 switches the system main relays SMR-P1 and SMR-P2 from off to on. The capacitors C1 and C2 are precharged by the current from the assembled battery 10. When the capacitors C1 and C2 are precharged, the current flows through the current limiting resistors R1 and R2, so that the inrush current can be suppressed from flowing through the capacitors C1 and C2.

  Here, the system main relays SMR-P1 and SMR-P2 can be operated at the same timing or can be operated at different timings. If system main relays SMR-P1 and SMR-P2 are operated at the same timing, the time required for starting the battery system can be shortened as compared with the case where they are operated at different timings. When system main relays SMR-P1 and SMR-P2 are operated at the same timing, the drive circuits for system main relays SMR-P1 and SMR-P2 can be shared.

  In step S103, the controller 50 switches the system main relay SMR-C from off to on. In step S104, the controller 50 switches the system main relays SMR-B and SMR-G from off to on. Here, the system main relays SMR-B and SMR-G can be operated at the same timing or can be operated at different timings.

  If system main relays SMR-B and SMR-G are operated at the same timing, the time required for starting the battery system can be shortened as compared with the case where the system main relays SMR-B and SMR-G are operated at different timings. When the system main relays SMR-B and SMR-G are operated at the same timing, the drive circuits for the system main relays SMR-B and SMR-G can be shared.

  In step S105, the controller 50 switches the system main relays SMR-P1 and SMR-P2 from on to off. Here, the system main relays SMR-P1 and SMR-P2 can be operated at the same timing or can be operated at different timings. After performing the process of step S105, the connection between the assembled battery 10 and the booster circuit 20 is completed, and the battery system is in an activated state (Ready-On).

  The operation when the ignition switch is switched from OFF to ON is not limited to the processing shown in FIG. Specifically, the system main relay SMR-P1 may be turned on from off before switching the system main relay SMR-B from off to on. Further, the system main relay SMR-P2 may be turned on from off before switching the system main relay SMR-G from off to on.

  Furthermore, the system main relay SMR-C may be turned on from off before switching at least one of the system main relays SMR-P1 and SMR-P2 from on to off. After the capacitor C1 (or C1, C2) is precharged and the system main relay SMR-B is turned on, the system main relay SMR-P1 may be turned off. Further, after capacitor C2 (or C1, C2) is precharged and system main relay SMR-G is turned on, system main relay SMR-P2 may be turned off.

  When the connection between the assembled battery 10 and the booster circuit 20 is cut off and the battery system is brought into a stopped state (Ready-Off), the controller 50 turns the system main relays SMR-B, SMR-C, and SMR-G from on to off. Switch to.

  When the assembled battery 10 is being charged / discharged and the current breaker 11b is activated in any of the unit cells 11, a voltage is applied between the terminals of the current breaker 11b in the activated state. According to the present embodiment, by providing the intermediate line ML, it is possible to reduce the voltage applied between the terminals of the current breaker 11b as compared with the configuration in which the intermediate line ML is omitted.

  When the assembled battery 10 is being discharged, for example, when the current breaker 11b of the cells 11 included in the first battery group 10A is activated, the first battery group 10A is interposed between the terminals of the current breaker 11b. A voltage corresponding to is applied. Since the current of the second battery group 10B can flow to the capacitors C1 and C2 via the intermediate line ML, the voltage of the second battery group 10B is applied between the terminals of the current breaker 11b in the activated state. Can be suppressed.

  For example, in the first battery group 10A, when the current breaker 11b of the unit cell 11 connected to the positive line PL is activated, the voltage of the first battery group 10A is mainly between the terminals of the current breaker 11b. A corresponding reverse voltage is applied. If the intermediate line ML is omitted, a reverse voltage corresponding to the voltage of the assembled battery 10 is applied between the terminals of the current breaker 11b. Since the voltage of the first battery group 10A is lower than the voltage of the assembled battery 10, the voltage applied between the terminals of the current breaker 11b can be reduced according to the present embodiment.

  When the battery pack 10 is being charged, for example, when the current breaker 11b of the unit cells 11 included in the first battery group 10A is activated, the terminals of the current breaker 11b in the activated state are A voltage corresponding to the voltage of one battery group 10A and the capacitor C1 is applied. By using the intermediate line ML, a charging current can be passed through the second battery group 10B.

  For example, in the first battery group 10A, when the current breaker 11b of the unit cell 11 connected to the positive electrode line PL is activated, electric charge is accumulated in the capacitor C1, and the voltage of the capacitor C1 increases. A voltage corresponding to the difference between the voltage of the first battery group 10A and the voltage of the capacitor C1 is applied between the terminals of the current breaker 11b in the operating state. If the intermediate line ML is omitted, a voltage corresponding to the difference between the voltage of the assembled battery 10 and the voltages of the capacitors C1 and C2 is applied between the terminals of the current breaker 11b in the activated state. Since the voltage of the first battery group 10A is lower than the voltage of the assembled battery 10, the voltage applied between the terminals of the current breaker 11b can be reduced according to the present embodiment.

  In this embodiment, when the battery system is in the activated state, no current flows through the current limiting resistors R1 and R2. Thereby, it is possible to suppress the heat generation of the current limiting resistors R1 and R2 due to the current continuously flowing through the current limiting resistors R1 and R2.

  According to the present embodiment, when one of the battery groups 10A and 10B fails, the vehicle can be driven using the output of the battery group that does not fail. For example, when the current breaker 11b of the unit cells 11 included in the first battery group 10A is activated, the vehicle can be driven using the output of the second battery group 10B.

  The configuration of the battery system that is Embodiment 2 of the present invention will be described with reference to FIG. In the present embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, differences from the first embodiment will be mainly described.

  In the present embodiment, as in the first embodiment, the system main relay SMR-B is disposed on the positive line PL, and the system main relay SMR-G is disposed on the negative line NL. A system main relay SMR-C is arranged in the intermediate line ML. In this embodiment, a current limiting resistor R and a system main relay (corresponding to the fourth relay of the present invention) SMR-P are connected in parallel to the system main relay SMR-C. System main relay SMR-P is connected in series.

  System main relay SMR-P is switched between on and off by receiving control signal P from controller 50. The current limiting resistor R is used to suppress an inrush current from flowing through the load when the assembled battery 10 is connected to the load.

  The operation of the battery system of this example will be described with reference to the flowchart shown in FIG. The process shown in FIG. 5 is executed by the controller 50. The process shown in FIG. 5 is executed when the ignition switch of the vehicle is switched from OFF to ON. When the processing shown in FIG. 5 is started, the system main relays SMR-B, SMR-C, SMR-G, and SMR-P are turned off.

  In step S201, the controller 50 determines whether or not there is a request for activation (Ready-ON) of the battery system. When there is a request to start the battery system, the process proceeds to step S202.

  In step S202, the controller 50 switches the system main relay SMR-P from off to on. In step S203, the controller 50 switches the system main relay SMR-G (or SMR-B) from off to on. Capacitor C2 is precharged when system main relay SMR-G is on, and capacitor C1 is precharged when system main relay SMR-B is on.

  In step S204, the controller 50 switches the system main relay SMR-B (or SMR-G) from off to on. When system main relay SMR-B is on, capacitor C1 is precharged, and when system main relay SMR-G is on, capacitor C2 is precharged. As described above, when the capacitors C1 and C2 are precharged, the current flows through the current limiting resistor R, so that the inrush current to the capacitors C1 and C2 can be suppressed.

  In step S205, the controller 50 switches the system main relay SMR-C from off to on. In step S206, the controller 50 switches the system main relay SMR-P from on to off. After performing the process of step S205, the connection between the assembled battery 10 and the booster circuit 20 is completed, and the battery system is in an activated state (Ready-On).

  In the present embodiment, the same effect as that of the first embodiment can be obtained. That is, it is possible to reduce the voltage applied between the terminals of the current breaker 11b, or to suppress the heat generation of the current limiting resistor R that accompanies the current flowing through the current limiting resistor R.

  The operation when the ignition switch is switched from OFF to ON is not limited to the processing shown in FIG. Specifically, the system main relay SMR-P may be turned on after one of the system main relays SMR-B and SMR-G is turned on. Moreover, the system main relay SMR-P may be turned off after the capacitors C1 and C2 are precharged and the system main relay SMR-C is turned on.

10: assembled battery, 11: single cell, 11a: power generation element, 11b: current breaker,
10A: first battery group, 10B: second battery group, 20: booster circuit,
30: Inverter, 40: Motor generator, 50: Controller,
51: Memory, 61, 62: Current sensor, PL: Positive line, NL: Negative line,
ML: intermediate line, C1, C2: capacitor,
SMR-B, SMR-G, SMR-C: System main relay,
SMR-P1, SMR-P2, SMR-P: System main relay,
R1, R2, R: current limiting resistors

Claims (1)

A power storage device comprising a plurality of power storage elements connected in series, each power storage element including a current breaker that interrupts an internal current path;
A first relay disposed on a positive line connecting a positive terminal of the power storage device to a load;
A second relay disposed on a negative electrode line connecting the negative electrode terminal of the power storage device to the load;
A plurality of smoothing capacitors connected in series between the positive electrode line and the negative electrode line;
A third relay disposed in an intermediate line connecting a connection point of the two storage elements included in the power storage device and a connection point of the plurality of smoothing capacitors;
A current limiting resistor and a fourth relay connected in parallel with each of the first relay and the second relay, or connected in parallel with the third relay, and connected in series with each other;
A power storage system comprising:

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