JP5728877B2 - Battery failure judgment device - Google Patents

Description

  The present invention relates to a battery failure determination device that detects a failure of an assembled battery having a current interruption mechanism.

  There is known a power supply device having a function of cutting off a current by operating a current cut-off mechanism provided in a battery cell when the battery is abnormal. In Patent Document 1, the presence or absence of a battery cell in which a current interruption mechanism is activated is determined from the voltage of the battery cell group, and when the activation is determined, a switching element connected to a part of the current path is driven to charge the assembled battery. Disclosed is a power supply device for stopping discharge.

JP 2008-182779 A JP 2008-253064 A Japanese Patent Laid-Open No. 08-075811

  However, in the configuration of Patent Document 1, since it takes time to detect a change in the voltage of the battery cell group, it is impossible to quickly detect the operation of the current interrupt mechanism. Therefore, an object of the present invention is to quickly detect the operation of the current interrupt mechanism.

In order to solve the above-described problems, a battery failure determination apparatus according to the present invention includes (1) an assembled battery for a vehicle that includes a plurality of single cells and includes a current interrupting mechanism that interrupts current in an abnormal state of the battery; A filter capacitor that is connected to a connection line that connects the assembled battery and a converter that adjusts the voltage of the power of the assembled battery supplied to the motor, and that suppresses voltage fluctuations associated with a switching operation of the converter; and the filter capacitor A first voltage sensor that obtains information on the voltage value of the filter capacitor, and a degree of change in the voltage value of the filter capacitor within a predetermined period is calculated, and the current interrupting mechanism is activated when the degree of change is higher than a threshold value And a controller for discriminating that it has been performed.

(2) In the configuration of (1), the controller further includes a current sensor that acquires information related to the current value of the assembled battery, and the controller causes the current value detected by the current sensor to flow through the assembled battery. If it is a value indicating that the current interruption mechanism is not present and the degree of variation is higher than the threshold value, it may be determined that the current interrupting mechanism has been activated.

  According to the configuration of (2), when the voltage value of the filter capacitor fluctuates rapidly due to a factor other than battery abnormality (for example, when the vehicle slips), the controller erroneously determines that the current interrupting mechanism has been activated. Can be prevented.

(3) In the configuration of (1) or (2), the assembled battery includes a plurality of battery blocks including a plurality of the single cells, and includes a second voltage sensor that detects a voltage value of each of the battery blocks. be able to.

  According to the configuration of (3), even when the second voltage sensor cannot be used due to battery abnormality, it is possible to determine whether or not the current interrupting mechanism is activated. In addition, the second voltage sensor may be protected by early determination of whether or not the current interruption mechanism is activated. Since the second voltage sensor is protected, the failure can be easily analyzed.

( 4 ) In any one of the configurations (1) to ( 3 ), the unit cell may be a lithium ion battery.

(5) In the above configuration (4), to the connection line is provided with a relay that switches the conducting state of the current, the controller, when the current blocking mechanism is activated, even if turning off the relay Good.

According to the structure of (5), it can suppress that a high voltage continues being applied to an assembled battery (actuated current interruption mechanism) .

  According to the present invention, it is possible to quickly detect the operation of the current interrupt mechanism.

It is a block diagram of a failure determination apparatus. It is a schematic diagram which shows the voltage behavior of the filter capacitor | condenser before pressure | voltage rise when the electric current interruption mechanism act | operates at the time of charge. It is a schematic diagram which shows the voltage behavior of the filter capacitor | condenser before pressure | voltage rise when the electric current interruption mechanism act | operates at the time of discharge. It is the graph which showed typically the method of calculating the variation | change_quantity of (DELTA) VL. It is the graph which showed the time change of (DELTA) VL. 3 is a flowchart illustrating a failure determination method according to the first embodiment. 6 is a flowchart illustrating a failure determination method according to a second embodiment.

Example 1
FIG. 1 is a block diagram of a battery failure determination apparatus. The failure determination apparatus 1 according to the present embodiment drives a motor with battery power, rotates a wheel with a driving force of the motor, and rotates a wheel with a driving force obtained by the internal combustion engine. It can be mounted on a hybrid vehicle that also uses the two drive paths as a power source.

  The assembled battery 11 includes a plurality of battery blocks 13. These battery blocks 13 are electrically connected in series. Each battery block 13 includes a plurality of single cells 12. These single cells 12 are electrically connected in series. The single battery 12 may be a secondary battery such as a lithium ion battery or a nickel metal hydride battery.

The controller 30 controls the entire failure determination apparatus 1. Each battery block 13 is connected to a voltage sensor 14a. Each voltage sensor 14 a detects the voltage value of each battery block 13 and outputs the detection result to the controller 30. The current sensor 14 b detects the value of the current flowing through the assembled battery 11 and outputs the detection result to the controller 30.

  Each single cell 12 includes an output circuit unit (not shown) that outputs a signal to the controller 30 when the voltage value exceeds the working voltage, and a current interrupt mechanism. The operating voltage of the unit cell 12 is a design value set from the viewpoint of preventing deterioration of the battery, and varies depending on the type of battery. The current interrupt mechanism may be a current fuse that melts by self-heating and interrupts the current when an excessive current flows. The current cut-off mechanism may be a temperature fuse that cuts off the current by melting the fusible body by transferring the ambient temperature. The current interrupting mechanism may be a mechanism that interrupts the current path in the unit cell 12 using deformation due to pressure as described in JP-A-10-302744.

  The controller 30 executes various programs stored in the memory 21. The memory 21 may be, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), or a VRAM (Video RAM).

  The assembled battery 11 is connected to a booster circuit 31 as a converter via system main relays SMR-G, SMR-B, and SMR-P. A system main relay SMR-G is connected to the plus terminal of the assembled battery 11, and a system main relay SMR-B is connected to the minus terminal of the assembled battery 11. The system main relay SMR-P and the precharge resistor 17 are connected in parallel to the system main relay SMR-B.

  These system main relays SMR-G, SMR-B, and SMR-P are relays that close contacts when the coil is energized. When SMR is on, it means an energized state, and when SMR is off, it means a non-energized state.

  The controller 30 turns off all the system main relays SMR-G, SMR-B, and SMR-P when the current is interrupted, that is, when the ignition switch is in the OFF position. That is, the exciting current for the coils of the system main relays SMR-G, SMR-B, and SMR-P is turned off. Note that the position of the ignition switch is switched from the OFF position to the ACC position in this order.

  When the hybrid system is activated (when the main power supply is connected), that is, for example, when the driver depresses the brake pedal and pushes the push-type start switch, the controller 30 first turns on the system main relay SMR-G. Next, the controller 30 turns on the system main relay SMR-P to execute precharging.

  A precharge resistor 17 is connected to the system main relay SMR-P. For this reason, even if the system main relay SMR-P is turned on, the input voltage to the inverter 32 rises gently, and the occurrence of an inrush current can be prevented.

  When the voltage value of the inverter 32 reaches, for example, about 80% to 100% of the voltage value of the assembled battery 11, or the voltage value of the inverter 32 becomes substantially equal to the voltage value of the battery module 13. Sometimes, precharging is completed, the system main relay SMR-P is turned off, and the system main relay SMR-B is turned on.

  When the position of the ignition switch is switched from the ON position to the OFF position, the controller 30 first turns off the system main relay SMR-B, and then turns off the system main relay SMR-G. Thereby, the electrical connection between the assembled battery 11 and the inverter 32 is cut off, and the power supply is cut off.

  The booster circuit 31 boosts the output voltage of the assembled battery 11 and supplies it to the inverter 32. The inverter 32 converts the DC power from the booster circuit 31 into AC power and supplies the AC power to a motor generator (three-phase AC motor) 34. As a result, the motor / generator 34 is driven, and the kinetic energy generated by the motor / generator 34 is transmitted to the wheels so that the vehicle can travel. Here, the booster circuit 31 and the inverter 32 constitute a power control unit 33.

  On the other hand, at the time of braking of the vehicle, the motor / generator 34 converts the kinetic energy of the vehicle into electric energy and supplies it to the inverter 32. The inverter 32 converts AC power from the motor / generator 34 into DC power. The booster circuit 31 steps down the DC power from the inverter 32 and supplies it to the pre-boost filter capacitor 18.

The pre-boost filter capacitor 18 smoothes fluctuations in the voltage applied to the DC power according to the switching operation of the booster circuit 31. The capacitor voltage sensor 19 measures the voltage value across the filter capacitor 18 before boosting. The controller 30 stores the voltage value measured by the capacitor voltage sensor 19 in the memory 21, which will be described in detail later.

  Next, a change in the voltage of the pre-boost filter capacitor 18 when the current interrupt mechanism is activated inside the assembled battery 11 will be described. FIG. 2 is a schematic diagram schematically showing the voltage behavior of the pre-boost filter capacitor 18 when the current interruption mechanism of the cell 12 is activated when the battery pack 11 is charged, and the horizontal axis shows the elapsed time, The vertical axis represents the pre-boosting voltage VL. Referring to the figure, when the current interruption mechanism is activated during charging of the assembled battery 11, the current used for charging up to that point no longer flows into the assembled battery 11, and the pre-boosting voltage VL of the pre-boosting filter capacitor 18 increases. .

  The pre-boosting filter capacitor 18 is designed so that the pre-boosting voltage VL does not become higher than the upper limit voltage value. When the pre-boosting voltage VL of the pre-boosting filter capacitor 18 reaches the upper limit voltage value, it gradually or suddenly decreases.

  FIG. 3 is a schematic diagram schematically showing the voltage behavior of the pre-boost filter capacitor 18 when the current interruption mechanism of the cell 12 is activated during discharge of the assembled battery 11, and the horizontal axis shows the elapsed time, The vertical axis represents the pre-boosting voltage VL. Referring to the figure, when the current interrupt mechanism is activated during discharge of the assembled battery 11, the power control unit 33 cannot acquire power from the assembled battery 11, and is therefore charged in the pre-boost filter capacitor 18. Operate to get the charge. As a result, the pre-boosting voltage VL of the pre-boosting filter capacitor 18 drops.

As described above, when the current interruption mechanism is activated in any of the single cells 12 included in the assembled battery 11, the pre-boosting voltage VL of the pre-boosting filter capacitor 18 varies greatly. Therefore, based on the degree of change in the pre-boosting voltage VL, it is possible to quickly determine whether the current interrupting mechanism is activated .

  Specifically, when the amount of change in ΔVL indicating the degree of change in the pre-boosting voltage VL of the pre-boost filter capacitor 18 exceeds a threshold value (change amount threshold value), the current cutoff mechanism of the unit cell 12 is activated. Can be determined. The change threshold value may be a design value set according to the type of battery, analysis result, and the like.

  FIG. 4 is a graph schematically showing a method of calculating the variation amount of ΔVL, where the horizontal axis represents time and the vertical axis represents the pre-boosting voltage VL. FIG. 5 is a graph showing temporal changes in ΔVL, with the horizontal axis representing time and the vertical axis representing ΔVL.

ΔVL, as shown in FIG. 4, a more calculated to boost before voltage V L that is a predetermined number of times sampled at a predetermined period. The predetermined period may be 8 msec. The predetermined number of times may be five. That is, ΔVL may be calculated every 40 msec.

  Here, the period for sampling the pre-boosting voltage VL is determined in terms of design from the viewpoint of preventing erroneous detection, and varies according to the mounting condition on the vehicle, the type of battery, and the like. For example, when the frictional resistance of the vehicle tire fluctuates rapidly (including the slip state and the grip state), the pre-boosting voltage VL of the pre-boosting filter capacitor 18 is abruptly the same as when the current interrupt mechanism is activated. fluctuate. However, the difference in the behavior of the voltage change of the pre-boosting voltage VL can be clarified by setting the sampling period of the pre-boosting voltage VL to an appropriate value.

  Next, a failure determination method when the inside of the assembled battery 11 is disconnected will be described with reference to the flowchart of FIG. In step S101, the controller 30 samples the output of the capacitor voltage sensor 19, that is, the pre-boosting voltage VL. In step S102, the controller 30 determines whether or not the number of samplings has reached a predetermined number. If the number of samplings reaches the predetermined number, the process proceeds to step S103.

In step S103, the controller 30 calculates ΔVL based on the pre-boosting voltage VL sampled a predetermined number of times. In step S <b> 104, the controller 30 calculates the variation amount of ΔVL by comparing with the most recently calculated ΔVL stored in the memory 21.

In step S105, the controller 30 determines whether or not the amount of change in ΔVL exceeds a threshold value. When the variation amount of ΔVL exceeds the threshold value, the process proceeds to step S106.
In step S106, the controller 30 determines that the current interrupt mechanism has been activated.

When the controller 30 determines that the current interrupting mechanism is activated, the controller 30 switches off the system main relays SMR-G and SMR-B. Thereby, it can prevent that a high voltage is continuously applied to the assembled battery 11 (actuated current interruption mechanism) . As a result, the assembled battery 11 can be protected from high voltage.

When the current interruption mechanism is activated, the voltage value at the location where the current interruption mechanism is activated increases. For this reason, the method of discriminating the presence or absence of the operation | movement of a current interruption mechanism from the voltage value of the assembled battery 11 can be considered. However, in an abnormal battery state in which the current interrupt mechanism is activated, the voltage sensor 14a may not function normally due to heat received from the unit cell 12 or the like. According to the failure determination device of the present embodiment, even when the voltage sensor 14a does not function correctly, based on the degree of change in voltage before VL of boost before the filter capacitor 18 detected by the capacitor voltage sensor 19, It can be determined whether or not the current interrupt mechanism has been activated. Therefore, a highly reliable failure determination device can be provided.

A method of determining whether or not the current interrupting mechanism is activated based on a signal output from each output circuit unit that outputs a signal when the voltage value provided in each cell 12 exceeds a predetermined value is also conceivable. However, in an abnormal state of the battery in which the current interruption mechanism is activated, the output circuit unit may not function normally due to heat received from the assembled battery 11 or the like. According to the configuration of the present embodiment, even when the output circuit does not function normally, on the basis of the degree of change in voltage before VL of boost before the filter capacitor 18 detected by the capacitor voltage sensor 19, current interruption It can be determined whether the mechanism has been activated. Therefore, a highly reliable failure determination device can be provided.

On the other hand, it may be possible to protect the current without interrupting the function of each voltage sensor 14a by quickly determining that the current interrupting mechanism has been activated. In this case, by examining the voltage value detected by the voltage sensor 14a at the time of recovery, the failed battery block 13 is specified, and the failure analysis becomes easy.
(Example 2)
In the first embodiment, the presence or absence of the operation of the current interrupting mechanism is determined based only on the degree of change in the pre-boosting voltage VL of the pre-boost filter capacitor 18. However, in this embodiment, the current value of the current sensor 14b is further used as a determination criterion. include.

  When the cell 12 is operating normally, a current flows through the assembled battery 11. On the other hand, when the current cutoff mechanism of the unit cell 12 is operating, no current flows through the assembled battery 11. Therefore, by using the detection result of the current sensor 14b that detects the value of the current flowing through the assembled battery 11, more accurate interruption detection can be performed. That is, in the first embodiment, the sampling period of the pre-boosting voltage VL is set to an appropriate value to distinguish between a so-called slip state and the case where the current interrupting mechanism is activated. There is no need to make such a distinction. In the circuit of the assembled battery 11, a current flows when the pre-boosting voltage VL changes suddenly due to slipping or the like, and no current flows when the current interrupting mechanism is activated.

  Therefore, when the current value detected by the current sensor 14b is a value indicating disconnection (hereinafter referred to as a disconnection threshold), and the degree of change in the pre-boosting voltage VL of the pre-boosting filter capacitor 18 is greater than the threshold. It can be determined that the current interruption mechanism of the unit cell 12 has been activated.

  Here, the disconnection threshold may be 0A or other than 0A. When the inside of the assembled battery 11 is disconnected, as a matter of course, no current flows inside the assembled battery 11. However, there is a case where the current value detected by the current sensor 14b does not become 0A (for example, ± 4A) even though the inside of the assembled battery 11 is disconnected due to the offset error of the current sensor 14b. Even if there is an offset error in this way, the offset error may be gradually reduced by providing a so-called learning function (for example, ± 0.5 A). In this way, the disconnection threshold varies based on the design conditions of the failure determination device.

  A failure determination method when the inside of the assembled battery 11 is disconnected will be described with reference to the flowchart of FIG. In step S201, the controller 30 determines whether or not the current value detected by the current sensor 14b is a disconnection threshold value. In this flowchart, it is assumed that the disconnection threshold is 0A.

  In step S202, the controller 30 samples the output of the capacitor voltage sensor 19, that is, the pre-boosting voltage VL. In step S203, the controller 30 determines whether or not the number of samplings has reached a predetermined number. If the number of samplings reaches the predetermined number, the process proceeds to step S204.

In step S204, the controller 30 calculates ΔVL based on the sampled pre-boosting voltage VL. In step S <b> 205, the controller 30 calculates the variation amount of ΔVL by comparing with the most recently calculated ΔVL stored in the memory 21.

In step S206, the controller 30 determines whether or not the amount of change in ΔVL exceeds a threshold value. When the variation amount of ΔVL exceeds the threshold value, the process proceeds to step S207.
In step S207, the current value detected by the current sensor 14b is sampled again. If there is no change from 0A, the process proceeds to step S208.

  In step S208, the controller 30 determines that the current interrupt mechanism has been activated.

When the controller 30 determines that the current interrupting mechanism is activated, the controller 30 switches off the system main relays SMR-G and SMR-B. Thereby, it can prevent that a high voltage is continuously applied to the assembled battery 11 (actuated current interruption mechanism) .

DESCRIPTION OF SYMBOLS 1 Failure determination apparatus 11 Battery assembly 12 Cell 13 Battery block 14a Voltage sensor 14b Current sensor 17 Precharge resistor 18 Filter capacitor before boost 19 Capacitor voltage sensor 31 Booster circuit 32 Inverter 34 Motor generator 34

Claims (5)

An assembled battery for a vehicle that includes a plurality of single cells and includes a current interrupting mechanism that interrupts current in an abnormal state of the battery;
A filter capacitor that is connected to a connection line that connects the assembled battery and a converter that adjusts the voltage of power of the assembled battery supplied to the motor, and suppresses voltage fluctuations associated with the switching operation of the converter;
A first voltage sensor for obtaining information relating to a voltage value of the filter capacitor;
A battery that calculates a degree of change of the voltage value of the filter capacitor within a predetermined period, and determines that the current interrupting mechanism is activated when the degree of change is higher than a threshold value. Failure determination device. Furthermore, a current sensor for obtaining information on the current value of the assembled battery is provided,
The controller, when the current value detected by the current sensor is a value indicating that no current flows through the assembled battery, and the degree of change is higher than the threshold value, the current interruption mechanism The battery failure determination device according to claim 1, wherein the battery failure determination device is determined to be activated.   3. The battery according to claim 1, wherein the battery pack includes a plurality of battery blocks including a plurality of the single cells, and includes a second voltage sensor that detects a voltage value of each of the battery blocks. Failure determination device.   4. The battery failure determination device according to claim 1, wherein the single battery is a lithium ion battery. 5. The connection line is provided with a relay for switching a current application state,
The battery failure determination device according to claim 4, wherein the controller turns off the relay when the current interrupt mechanism is activated.

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