JP2010183679A - Battery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To block a current by exactly detecting an overcurrent of a battery. <P>SOLUTION: This battery system comprises the chargeable battery 1, contactors 2 connected to the battery 1, a current sensor 21 which detects a current of the battery 1, a voltage detection circuit 22 which detects a voltage of the battery 1, and a current blocking circuit 4 which switches the contactors 2 by using the magnitude of the current detected by the current sensor 21, the determination of a charging current and a discharging current, and the voltage of the battery 1 detected by the voltage detection circuit 22. The current blocking circuit 4 turns off the contactors 2 depending on an overcurrent discharging state where the detected current of the current sensor 21 is larger than a set current, a voltage drop of the battery 1 detected by the voltage detection circuit 22 is larger than a set value, and the current sensor 21 detects the discharging current, and an overcurrent charging state where the detected current of the current sensor 21 is larger than the set current, a voltage rise of the battery 1 detected by the voltage detection circuit 22 is larger than a set value, and the current sensor 21 detects the charging current. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery system that is optimal for a power supply device for a vehicle that supplies electric power to a motor that drives the vehicle, and more particularly to a battery system that detects an overcurrent of a battery and interrupts the current.

A battery system that detects an overcurrent of a battery and interrupts the current has been developed. (See Patent Document 1)
As shown in FIG. 1, the battery system of Patent Document 1 divides a battery 91 into two battery blocks 95 and connects the battery blocks 95 in series via a fuse 98. Is connected to a contactor 92. In this battery system, when an overcurrent flows through the battery 91, the fuse 98 is blown to cut off the current of the battery 91. Furthermore, an overcurrent is detected and the contactor 92 is switched off to interrupt the current. The current cutoff circuit 94 of the battery system includes a current sensor 99 that detects the current of the battery 91, and manages charging / discharging of the battery 91 with the detected current. The current sensor 99 detects a current of 200 A or less in a current range in which the battery 91 is normally charged and discharged, for example, in a vehicle battery system. When a current larger than this current flows through the battery 91, that is, when an abnormal overcurrent flows through the battery 91, the contactor 92 is switched off to interrupt the current of the battery 91. The battery system of FIG. 1 switches the contactor 92 off due to an overcurrent, and further blows the fuse 98 to achieve high safety.

JP 2008-193776 A

  However, if the battery system shown in FIG. 1 detects an overcurrent with a current sensor that cannot accurately detect the current and switches the contactor off, it actually cuts off the current of the battery where no overcurrent flows. . In this state, if the battery system supplies power to the motor that runs the vehicle, the vehicle cannot run with the motor. In a vehicle driven by a motor, this state may be a very dangerous state. Therefore, it is important to minimize the state in which the battery current is cut off due to a malfunction.

  The present invention has been developed for the purpose of eliminating the above-described adverse effects, and an important object of the present invention is to provide a battery system capable of reliably detecting an overcurrent of a battery and interrupting the current. .

Means for Solving the Problems and Effects of the Invention

  The battery system of the present invention includes a rechargeable battery 1, a contactor 2 connected in series to the output side of the battery 1, and a current sensor that discriminates a charging current and a discharging current in addition to the magnitude of the current of the battery 1. 21, a voltage detection circuit 22 that detects the voltage of the battery 1, a magnitude of the current of the battery 1 that is detected by the current sensor 21, a determination of a charging current and a discharging current, and a battery 1 that is detected by the voltage detection circuit 22 And a current interrupting circuit 4 for switching the contactor 2 with the voltage of. In the current interrupt circuit 4, the current detected by the current sensor 21 is greater than the set current, the voltage drop of the battery 1 detected by the voltage detection circuit 22 is greater than the set value, and the current sensor 21 detects the discharge current. Overcurrent discharge state, the detected current of the current sensor 21 is larger than the set current, the voltage rise of the battery 1 detected by the voltage detection circuit 22 is larger than the set value, and the current sensor 21 generates the charging current. The contactor 2 is switched off depending on the overcurrent charge state to be detected.

  The battery system described above has a feature that can reliably detect an overcurrent of the battery and interrupt the current. This is because it is possible to prevent the current sensor from erroneously detecting an overcurrent and switching off the contactor to cut off the battery current. The current cutoff circuit determines not only the current value detected by the current sensor but also the voltage drop and voltage rise of the battery detected by the voltage detection circuit, and the charge current and discharge current detected by the current sensor to turn off the contactor. To cut off the current. Even if the current sensor has a failure in which the current value cannot be accurately detected, the current sensor rarely has a failure in which the charge current and the discharge current cannot be distinguished. This is because the direction of the flowing current of the charging current and that of the discharging current are opposite, and the directions are greatly different in a state where an overcurrent flows. In addition to the current value detected by the current sensor, the current interrupt circuit distinguishes the discharge current and the charging current, and further determines the overcurrent from the voltage drop and voltage rise of the battery, and switches the contactor off. When the load is shorted and overcurrent flows, the current sensor detects the overcurrent, determines that the current is a discharge current, and the voltage detection circuit confirms that the battery voltage drop has increased. To detect. By switching the contactor off in this state and cutting off the current, battery overcurrent can be prevented in the event of a load short-circuit. However, even if an overcurrent is detected by the current sensor, the current interrupt circuit does not switch the contactor off when the voltage drop of the battery is small or the overcurrent is not the discharge current. This is because this state does not occur due to a load short-circuit or the like.

  In the above battery system, the current sensor detected current is larger than the set current, the battery voltage drop detected by the voltage detection circuit is larger than the set value, and the current sensor detects the discharge current overcurrent. The contactor is switched off as a discharge state, and further, the detected current of the current sensor is larger than the set current, the voltage rise of the battery detected by the voltage detection circuit is larger than the set value, and the current sensor detects the charging current. Switch the contactor to off-current charging state. Therefore, it is possible to reliably prevent the battery from being discharged or charged forcibly by switching off the contactor by mistake due to the failure of the current sensor.

  The battery system of the present invention includes a fuse 8 connected in series with the battery 1, and also includes a timer unit 24 for specifying a delay time until the current interrupt circuit 4 switches the contactor 2 from on to off, 8, the fusing current in the delay time of the timer unit 24 is set to be smaller than the maximum cutoff current of the contactor 2 and larger than the maximum allowable charge / discharge current of the battery 1, so that the maximum cutoff of the contactor 2 is set in the battery 1. In a state where an overcurrent larger than the current flows, the fuse 8 is blown within the delay time of the timer unit 24, and the current interrupt circuit 4 can switch the contactor 2 from on to off at the timing when the delay time elapses.

  The battery system described above has a feature that the battery overcurrent can be reliably interrupted by the contactor without welding the contactor contact, and the battery overcurrent can be reliably interrupted by a fuse. This is because the above battery system detects a battery overcurrent and sets a delay time until the contactor is switched from on to off, and the fuse blown current at this delay time is less than the contactor's maximum cutoff current, This is because the allowable charge / discharge current is set to be larger than the maximum value. This battery system shuts off the fuser by blowing the fuse within the delay time and shuts off the contactor when the delay time elapses when overcurrent greater than the contactor's maximum cutoff current flows through the battery. To do. Therefore, the battery overcurrent can be reliably and safely interrupted by both the contactor and the fuse without welding the contactor contact. Conversely, if the overcurrent continues for more than the delay time, the current is lower than the fusing characteristics of the fuse, but it is lower than the maximum breaking current of the contactor, so it is possible to cut off the current without welding the contactor It is.

  In the battery system of the present invention, the battery 1 includes a plurality of battery cells 5, and the battery cell 5 includes an internal current interrupting unit that interrupts the internal connection circuit due to overcurrent or overcharge. It can be set as the characteristic which fuses with the electric current smaller than the fusing characteristic of an electric current interruption part.

  The battery system described above is characterized in that the battery overcurrent can be reliably interrupted with a fuse or a contactor without operating the internal current interrupter built in the battery cell. This is because the battery system described above interrupts the battery current with a fuse or a contactor before the internal current interrupting section of the battery interrupts the current.

  Furthermore, in the battery system of the present invention, the internal current interruption part of the battery cell 5 can be a CID (Current Interrupt Device).

  In the battery system of the present invention, the current sensor 21 includes a current detection resistor 25 connected in series with the battery 1, and a differential amplifier 26 that amplifies a voltage induced across the current detection resistor 25. The current of the battery 1 can be detected by the output voltage of the differential amplifier 26.

  In the battery system of the present invention, the output voltage of the battery 1 can be 10 V or more and 500 V or less.

  In the battery system of the present invention, the battery 1 can supply electric power to the motor 11 that drives the vehicle via the contactor 2.

It is a schematic block diagram of the power supply device which the present applicant applied previously. It is a schematic block diagram of the battery system concerning one Example of this invention. It is a figure which shows the characteristic which the battery system shown in FIG. 2 interrupts | blocks an electric current.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a battery system for embodying the technical idea of the present invention, and the present invention does not specify the battery system as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The battery system shown in FIG. 2 is mounted on a vehicle such as a hybrid car, a fuel cell vehicle, and an electric vehicle, and drives a motor 11 connected as a load 10 to drive the vehicle. A motor 11 serving as a load 10 of the battery 1 is connected to the battery 1 via an inverter 12. The inverter 12 converts the direct current of the battery 1 into a three-phase alternating current, and controls the power supplied to the motor 11.

  The battery system of this figure includes a battery 1, a fuse 8 connected in series with the battery 1, a contactor 2 connected to the output side of the battery 1 to switch on / off the power supply to the load 10, Before the contactor 2 is turned on, a precharge circuit 3 for precharging the capacitor 13 of the load 10 and a current cutoff circuit 4 for controlling the precharge circuit 3 and the contactor 2 on and off are provided.

  The battery 1 drives a motor 11 that causes the vehicle to travel via an inverter 12. In order to supply a large amount of power to the motor 11, the battery 1 has a high output voltage by connecting a number of rechargeable battery cells 5 in series. The battery cell 5 is a lithium ion battery or a nickel metal hydride battery. A battery system in which a battery cell is a lithium ion battery has a plurality of lithium ion batteries connected in series. In a battery system in which battery cells are nickel metal hydride batteries, a plurality of nickel metal hydride batteries are connected in series to form a battery module, and a plurality of battery modules are connected in series to increase the output voltage. The battery system does not specify a battery as a lithium ion battery or a nickel metal hydride battery. As the battery, any rechargeable battery such as a nickel cadmium battery can be used.

  The battery 1 has an output voltage as high as 200 to 400 V, for example, so that large power can be supplied to the motor 11. However, the battery system can also connect a DC / DC converter (not shown) to the output side of the battery to boost the voltage of the battery and supply power to the load. This battery system can reduce the output voltage of a battery by reducing the number of batteries connected in series. Therefore, the battery 1 can set the output voltage to 150 to 400 V, for example.

  The current interruption circuit 4 is input from a voltage detection circuit 22 that detects the voltage of the battery cell 5 that constitutes the battery 1 and a current sensor 21 that detects the current of the battery 1 in order to control charging and discharging of the battery 1. The contactor 2 is controlled by the signal.

  The voltage detection circuit 22 detects the voltage of the plurality of battery cells 5 or detects the voltage of the battery module in which the plurality of battery cells are connected in series. A battery system using a lithium ion battery as a battery detects the voltage of each lithium ion battery using a voltage detection circuit, and a battery system using a battery as a nickel metal hydride battery includes a plurality of nickel metal hydride batteries using a voltage detection circuit. The voltage of the battery modules connected in series is detected.

  The current sensor 21 detects the current flowing through the battery 1 in order to detect the remaining capacity of the battery cell 5. The battery system includes a current sensor 21 for calculating the remaining capacity of the battery 1 and controlling the current for charging and discharging the battery 1. The current interrupt circuit 4 calculates the remaining capacity by integrating the current of the battery 1 detected by the current sensor 21. The battery system transmits a signal to the vehicle side to control the charge / discharge current so that the remaining capacity of the battery 1 is about 50%. This is to reduce the deterioration of the battery 1 as much as possible in various running conditions. Since the remaining capacity of the battery 1 increases with the integrated value of the charging current and decreases with the integrated value of the discharging current, it can be calculated with the integrated value of the charging current and the discharging current.

  The current cutoff circuit 4 controls the contactor 2 to be turned on / off by a signal from the current sensor 21 and a signal input from the voltage detection circuit 22 to cut off the overcurrent flowing through the battery 1. The current sensor 21 detects the current of the battery 1 but accurately detects the current value within a range in which the battery 1 is allowed to be charged and discharged. Therefore, the current sensor 21 cannot detect the magnitude of the overcurrent when the overcurrent flows through the battery 1. That is, the current sensor 21 can detect whether or not an overcurrent flows, but cannot detect the magnitude of the overcurrent. Accordingly, when the current sensor 21 detects an overcurrent, the current interrupt circuit 4 discriminates the signal of the voltage detection circuit 22, the discharge current and the charge current, switches the contactor 2 from on to off, and Cut off current.

  The current interruption circuit 4 determines that not only the detection current of the current sensor 21 but also all the following conditions (1) to (3) are satisfied, and determines that an overcurrent flows through the battery 1. The contactor 2 is switched off to interrupt the current. The state satisfying the conditions (1) to (3) occurs when the battery 1 is discharged [first state] and when the battery 1 is charged [second state].

[First state: Battery discharge state]
(1) The detected current of the current sensor 21 is larger than the set current,
(2) The voltage drop of the battery 1 detected by the voltage detection circuit 22 is larger than the set value,
(3) Current sensor 21 is detecting the discharge current

  The above state occurs when the battery 1 is discharged, for example, when the load 10 is short-circuited and an overcurrent flows.

[Second state: Battery charge state]
(1) The detected current of the current sensor 21 is larger than the set current,
(2) The voltage rise of the battery 1 detected by the voltage detection circuit 22 is larger than the set value,
(3) Current sensor 21 detects charging current

  The above-described state occurs due to a failure of the charging circuit or a failure of a DC / AC inverter connected as the load 10 or a DC / DC converter that boosts the battery voltage in the vehicle power supply device.

  The set current that the current interrupt circuit 4 determines as an overcurrent based on a signal from the current sensor 21 is set to an optimum value depending on the application of the battery system. For example, a battery system used in a vehicle power supply apparatus sets a set current to be determined as an overcurrent to 200A. However, even in the battery system for this application, the same set current is not used in the state in which the battery 1 is discharged and the state in which the battery 1 is charged. For example, when the set current is discharged, it is larger or smaller than the set current. You can also The set current determined to be an overcurrent is set, for example, in the range of 100A to 400A based on battery electrical characteristics, vehicle type, acceleration performance required for the vehicle, braking force for regenerative braking required for the vehicle, and the like. Further, depending on the electric characteristics of the battery, the performance required for the vehicle, and the like, it can be set to be larger than 400A or smaller than 100A.

  The set value of voltage drop or voltage rise that the current interrupt circuit 4 determines to be overcurrent is set to an optimum value in consideration of the application of the battery system, the type of battery, and the number of batteries for detecting the voltage. For example, in a battery system used in a power supply device for a vehicle, the battery is a lithium ion battery, and in a current interruption circuit that detects a voltage drop and a voltage rise from the voltage of one battery cell, the set value is 0.4V. However, in the battery system used for this application, as with the set voltage, the battery electrical characteristics, vehicle type, acceleration performance required for the vehicle, regenerative braking braking force required for the vehicle, etc. For example, it can be set in the range of 0.1 V / cell to 1.5 V / cell, and more than 1.5 V, or more than 0.1 V, depending on the electric characteristics of the battery and the performance required for the vehicle. Can be set smaller.

  The battery 1 is discharged to decrease the voltage, and is charged to increase the voltage. In order to detect the voltage drop and voltage rise of the battery 1 whose voltage fluctuates, the current interrupt circuit 4 compares the input voltage value with the voltage value detected before the set time, and determines the voltage from the difference voltage. Detect drops and voltage rises. The set time is set to 0.3 seconds, for example. This current interruption circuit 4 can detect the voltage drop and the voltage rise by detecting the voltage of the battery 1 with a sampling period of 0.3 seconds and comparing the detected voltage with the previous detected voltage.

  However, the current interrupt circuit is not a change in the battery voltage during the set time. For example, in a hybrid car, the battery open circuit voltage is detected during a time period when the battery is not charged and discharged, and then the battery is discharged or charged. It is also possible to detect a voltage drop and a voltage rise by comparing the detection voltage detected at the timing to the open circuit voltage. Furthermore, the open circuit voltage of the battery that is not charged / discharged can also be specified from the remaining capacity of the battery. This is because the open circuit voltage of the battery is specified with the remaining capacity as a parameter. Therefore, the current interrupt circuit calculates the remaining capacity of the battery by accumulating the current that charges and discharges the battery, identifies the open voltage of the battery from the calculated remaining capacity, and compares the detected voltage to the open voltage. Thus, voltage drop and voltage rise can be detected.

  The current interrupt circuit 4 is a signal input from the current sensor 21 and determines whether the current is discharging the battery 1 or charging the current. The current sensor 21 detects the current of the battery 1 by amplifying the voltage induced at both ends of the current detection resistor 25 connected in series with the battery 1 by the differential amplifier 26. In this current sensor 21, since the output voltage of the differential amplifier 26 is proportional to the current of the battery 1, the current interrupt circuit 4 can detect the current of the battery 1 with the voltage input from the current sensor 21. Further, the current sensor 21 reverses the polarity of the voltage output between the state where the battery 1 is charged and the state where it is discharged. For example, the current sensor 21 that outputs a positive voltage while detecting a discharge current outputs a negative voltage while detecting a charging current. Therefore, the current interrupt circuit 4 can determine whether the battery 1 is discharged or charged based on whether the voltage input from the current sensor 21 is positive or negative. In particular, the current sensor 21 outputs a large voltage signal to the current interrupt circuit 4 when an overcurrent flows in the battery 1, so that the current interrupt circuit 4 is reliably stabilized from the voltage input from the current sensor 21. The discharged state and the charged state can be determined.

  The current interruption circuit 4 detects that the above conditions (1) to (3) are satisfied and switches the contactor 2 from on to off, but satisfies the conditions (1) and (3) ( If the condition of 2) is not satisfied, it is determined that the current sensor 21 has failed. When the condition (2) is satisfied and the conditions (1) and (3) are not satisfied, it is determined that the voltage detection circuit 22 has failed. Further, when the conditions (1) and (2) are satisfied and the condition (3) is not satisfied, it is determined that the current sensor 21 is faulty. In a battery system used for a power supply device for a vehicle, when it is determined that the current sensor 21 is in failure or the voltage detection circuit 22 is in failure, the contactor 2 is not immediately switched from on to off, for example, Display battery system failure. In this state, the charging current and discharging current of the battery system are limited so that the vehicle can be driven, but a prompt repair is displayed.

  In the battery system shown in the figure, the overcurrent of the battery 1 is interrupted by the contactor 2, and the overcurrent is also interrupted by the fuse 8 to further improve safety. This current interrupt circuit 4 detects the overcurrent in the overcurrent discharge state or overcurrent charge state from the conditions (1) to (3) described above, and then sets a delay time for switching the contactor 2 off. A timer unit 24 for storing is provided. The current interruption circuit 4 switches the contactor 2 from on to off at the timing when the delay time stored in the timer unit 24 has elapsed after detecting the overcurrent. In FIG. 3, the delay time for switching off the contactor 2 by the current interrupting circuit 4 is set to 0.3 seconds. The current cut-off circuit 4 detects an overcurrent and switches off the contactor 2 at a timing when a delay time of 0.3 seconds elapses to cut off the current of the battery 1. That is, the current of the battery 1 is not cut off until 0.3 seconds elapses after the overcurrent is detected.

  The contactor 2 is controlled by the current interrupt circuit 4 to switch the contact on and off. Although not shown in the figure, the contactor 2 includes an exciting coil that switches the contacts on and off. The current interruption circuit 4 controls the current of the exciting coil to switch the contactor 2 on and off. The normal contactor 2 energizes the excitation coil to turn on the contact, cuts off the excitation coil current, and switches the contact off.

  The contactor 2 is specified with a maximum cut-off current that can cut off the current. The maximum breaking current can be increased by increasing the contact capacity and pressing the movable contact firmly against the fixed contact. However, a contactor with a large maximum breaking current has a large movable contact and a fixed contact, a strong spring to quickly separate the large movable contact from the fixed contact, and a movable contact to quickly move the movable contact away from the fixed contact. It is also necessary to increase the stroke for reciprocating the contact. A strong spring contactor requires a large excitation coil and a large current, that is, a large excitation coil to increase power consumption. The power consumption of the exciting coil is always consumed while the contact is kept on. A contactor with a large power consumption has a drawback that the exciting coil generates a large amount of heat and consumes a large amount of power in a state where the contact is kept on. For this reason, the maximum cut-off current of electric power is set to an optimum current value according to the use from the size, power consumption, and calorific value.

  For example, in a battery system used for a power supply device for a vehicle, it is essential to reduce the size and weight of the contactor, and therefore the maximum breaking current cannot be increased unnecessarily. However, when the output voltage of the battery system is increased in order to increase the power supplied to the load, the short-circuit current that flows when the load is short-circuited becomes extremely large. Furthermore, the energy of the short current increases in proportion to the square of the current. For this reason, if the battery system controls the contactor to be turned off while the load is short-circuited and a large short-circuit current flows, if the short-circuit current exceeds the contactor's maximum breaking current, a strong arc is generated between the contacts at the time of breaking. In this case, the movable contact may be welded to the fixed contact and cannot be switched off.

  In order to prevent contact welding of the contactor 2, to reliably cut off the overcurrent of the battery 1, and to realize the characteristic of not cutting off the current of the battery 1 in a current range smaller than the overcurrent, the fusing characteristics of the fuse 8 are It has unique characteristics. The time for the fuse 8 to blow and cut off the current becomes shorter as the current increases, as shown by the curve A in FIG. Since the fuse 8 is blown by its own heat generation, it is difficult to accurately control the current value to blow. A fuse that is easily blown will blow in the range of the allowable charge / discharge current of the battery that allows charging / discharging of the battery. On the other hand, fuses that are difficult to blow cannot reliably prevent contact welding of contactors. By setting the characteristics of the fuse 8 and the contactor 2 in a preferable state, the battery system reliably prevents the contact of the contactor 2 from being welded. Further, the overcurrent of the battery 1 is prevented between the contactor 2 and the fuse 8. Can be shut off reliably. In order to realize this, the fusing current for fusing the fuse 8 is such that the fusing current in the delay time of the timer unit 24 of the current breaking circuit 4 is smaller than the maximum breaking current of the contactor 2.

  In FIG. 3, since the maximum breaking current of the contactor 2 is 500 A and the delay time is 0.3 seconds, the fusing current after 0.3 seconds of the fuse 8 is made smaller than 500 A. This fuse 8 has a current larger than the maximum contact current of the contactor 2, that is, between 0 and 0.3 seconds counted by the timer unit 24, which is larger than the contact of the contactor 2 is welded by an arc generated at the time of interruption. And the current of the battery 1 is cut off. Therefore, the overcurrent that does not blow the fuse 8 until the delay time of 0.3 seconds is a current that is not welded by the arc generated when the contact of the contactor 2 is cut off. Therefore, the contactor 2 after 0.3 seconds of the delay time. The contacts are not welded by switching off. Further, after the delay time of 0.3 seconds elapses, the contactor 2 cuts off the current of the battery 1 regardless of whether the fuse 8 is blown or not. Fusing characteristics after 2 seconds are not required. The fusing characteristic required for the fuse 8 is a fusing characteristic from the moment when the overcurrent flows to the delay time, that is, from 0 to 0.3 seconds. In particular, only the fusing current after a delay time of 0.3 seconds after an overcurrent flows is required. However, it is not preferable that the fuse 8 be blown in a range of allowable charge / discharge current that allows charging / discharging of the battery 1. Therefore, the fuse 8 has a fusing current after 0.3 seconds that is a delay time larger than 200 A that is the maximum value of the allowable charging / discharging current of the battery 1. From this, the fuse 8 is designed to be blown by a current between the curve A of FIG. 3 and “the maximum value of the allowable charge / discharge current of the battery”. The fuse 8 having the fusing characteristics of the curve B is blown at a current smaller than 200 A which is the maximum current for charging and discharging the battery 1 after the delay time of 0.3 seconds has elapsed, and the allowable charging / discharging current of the battery 1 is reduced. It becomes impossible to charge and discharge in the range. For this reason, the battery system cannot be used at a normal current value and cannot be used.

  Further, when the battery cell 5 constituting the battery 1 is in an abnormal state such as an overcurrent discharge state or an overcurrent charge state, the internal connection circuit of the battery cell 5 is cut off, that is, the internal current is cut off by itself. A blocking part is provided. The internal current interrupting unit includes a CID that operates by an abnormal increase in battery internal pressure and interrupts current. The CID operates and cuts off the current when the battery cell 5 is overcharged and the internal pressure is abnormally increased. However, because of the structure that cuts off the current, it is excessive compared with other battery cell structural members. The current resistance is low. Therefore, when an overcurrent is generated, fusing most easily occurs in the battery cells.

  A curve C in FIG. 3 shows a cutoff characteristic in which the internal current cutoff unit operates to cut off the current. The fusing characteristics (curve A and curve B) of the fuse 8 are set so as to blow with a current smaller than the interruption characteristic of the internal current interruption part. Therefore, before the delay time of 0.3 seconds, the fuse 8 is blown to prevent current interruption by the internal current interruption unit.

  Further, as shown by curve C in FIG. 3, the interruption characteristic of the internal current interruption unit is such that the interruption current after 0.3 seconds which is the delay time of the timer unit 24 is larger than 500 A of the maximum interruption current of the contactor 2. It is set. In this battery system, in the state where the overcurrent flows through the battery 1, the contactor 2 is switched from on to off with an overcurrent smaller than the internal current cut-off unit cuts off the current. The current of the battery 1 is interrupted before the interrupting part interrupts the current. For this reason, an overcurrent can be interrupted while preventing the operation of the internal current interrupter.

  The load 10 connected to the battery 1 has a motor 11 connected to the output side of the inverter 12. The inverter 12 as the load 10 is connected with a large-capacity capacitor 13 in parallel. The capacitor 13 supplies power to the inverter 12 of the load 10 from both the battery 1 and the contactor 2 in a state where the contactor 2 is switched on. In particular, large power is instantaneously supplied from the capacitor 13 to the inverter 12 of the load 10. The instantaneous power that can be supplied to the load 10 is increased by connecting the capacitor 13 in parallel with the battery 1. Since the instantaneous maximum power that can be supplied from the capacitor 13 to the inverter 12 of the load 10 is proportional to the capacitance, the capacitor 13 has a very large capacitance of, for example, 4000 to 6000 μF. When a large-capacitance capacitor 13 in a discharged state is connected to the battery 1 having a high output voltage, a very large charge current instantaneously flows. This is because the impedance of the capacitor 13 is extremely small.

  The precharge circuit 3 precharges the capacitor 13 of the load 10 before the contactor 2 is turned on by an ON signal input from the ignition switch 14. The precharge circuit 3 precharges the capacitor 13 while limiting the charging current of the capacitor 13. The precharge circuit 3 has a precharge switch 7 and a precharge switch 7 connected in series. The precharge resistor 6 limits the precharge current of the capacitor 13 of the load 10. The precharge circuit 3 can reduce the precharge current by increasing the electrical resistance of the precharge resistor 6. For example, the precharge resistor 6 is a cement resistor of 10Ω and 30W. The precharge resistor 6 limits the peak charging current at which the battery 1 with an output voltage of 400V charges the capacitor 13 to 40A.

  The precharge circuit 3 is connected to the contact of the contactor 2 in parallel. In the illustrated battery system, contactors 2 are provided on both the plus side and the minus side, and a precharge circuit 3 is connected in parallel with the contact of the plus side contactor 2A. In this battery system, the precharge circuit 3 precharges the capacitor 13 with the negative contactor 2B on and the positive contactor 2A off. When the capacitor 13 is precharged by the precharge circuit 3, the plus-side contactor 2A is switched from OFF to ON, and the precharge switch 7 of the precharge circuit 3 is switched OFF.

  The precharge circuit 3 turns on the precharge switch 7 to precharge the capacitor 13. The precharge switch 7 is a switch having a mechanical contact such as a contactor. However, the precharge switch can also use semiconductor switching elements such as transistors and FETs. Since the precharge switch of the semiconductor switching element is not deteriorated like a contact, the lifetime can be extended. Further, since it can be switched on and off at high speed in a very short time, the capacitor can be precharged while being switched on and off.

  After the capacitor 13 is precharged by the precharge circuit 3, the positive side contactor 2A controlled in parallel with the precharge circuit 3 is switched on to supply power from the battery 1 to the load 10, that is, the battery 1, the motor 11 is driven so that the vehicle can run.

1 ... battery 2 ... contactor 2A ... plus contactor
2B: Negative contactor 3 ... Precharge circuit 4 ... Current interrupt circuit 5 ... Battery cell 6 ... Precharge resistor 7 ... Precharge switch 8 ... Fuse 10 ... Load 11 ... Motor 12 ... Inverter 13 ... Capacitor 14 ... Ignition switch 21 ... Current sensor 22 ... Voltage detection circuit 24 ... Timer unit 25 ... Current detection resistor 26 ... Differential amplifier 91 ... Battery 92 ... Contactor 94 ... Current cutoff circuit 95 ... Battery block 98 ... Fuse 99 ... Current sensor

Claims (7)

A battery (1) that can be charged, a contactor (2) connected in series on the output side of the battery (1), and a charge current and a discharge current in addition to the magnitude of the current of the battery (1) A current sensor (21), a voltage detection circuit (22) for detecting the voltage of the battery (1), a magnitude of the current of the battery (1) detected by the current sensor (21), a charge current and a discharge current And a current interrupt circuit (4) for switching the contactor (2) with the voltage of the battery (1) detected by the voltage detection circuit (22),
The current interrupt circuit (4) has a detection current of the current sensor (21) larger than a set current, and a voltage drop of the battery (1) detected by the voltage detection circuit (22) is larger than a set value. In addition, an overcurrent discharge state in which the current sensor (21) detects a discharge current, and
The detected current of the current sensor (21) is larger than a set current, and the voltage rise of the battery (1) detected by the voltage detection circuit (22) is larger than a set value, and the current sensor (21) A battery system configured to switch off the contactor (2) in an overcurrent charging state in which the charging current is detected. A fuse unit (8) connected in series with the battery (1), and the current interrupt circuit (4) includes a timer unit (24) for specifying a delay time until the contactor (2) is switched from on to off. )
The fuse (8) is set so that the fusing current in the delay time of the timer section (24) is less than the maximum breaking current of the contactor (2) and larger than the maximum allowable charging / discharging current of the battery (1). And
In the state where an overcurrent larger than the maximum breaking current of the contactor (2) flows through the battery (1), the fuse (8) is blown within the delay time of the timer unit (24), and the delay time has elapsed. The battery system according to claim 1, wherein the current interrupting circuit (4) switches the contactor (2) from on to off at the timing.   The battery (1) includes a plurality of battery cells (5), the battery cell (5) includes an internal current cut-off unit that cuts off an internal connection circuit due to overcurrent or overcharge, and the fuse (8) is blown out. The battery system according to claim 2, wherein the characteristic is a characteristic of fusing with a current smaller than a fusing characteristic of the internal current interrupting portion.   The battery system according to claim 3, wherein the internal current interrupting part of the battery cell (5) is a CID (Current Interrupt Device).   The current sensor (21) is a current detection resistor (25) connected in series with the battery (1), and a differential amplifier (26) that amplifies the voltage induced across the current detection resistor (25). The battery system according to any one of claims 1 to 4, wherein the current of the battery (1) is detected by the output voltage of the differential amplifier (26).   The battery system according to any one of claims 1 to 4, wherein an output voltage of the battery (1) is 10 V or more and 500 V or less.   The battery system according to claim 1, wherein the battery (1) supplies electric power to a motor (11) for running the vehicle via a contactor (2).

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