JP2004006138A - Battery pack system and fail-safe methodology of battery pack system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure safety by making a fail-safe function work properly on the failure of a battery pack. <P>SOLUTION: This system comprises an inverter 2 for setting the output of a motor 1 that is a power source of a vehicle, a group of battery pack unit, and a control part 6. In the group of battery pack unit, the battery pack 4 and a battery pack unit 3 having a relay 5 capable of cutting off the current passage between the battery pack 4 and the inverter 2 are connected in parallel in multiple sets. The control part 6 sets to cut-off state the relay 5 comprised by the failed battery pack unit 3 at the failure of the battery pack unit 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery pack system and a fail-safe method for a battery pack system.
[0002]
[Prior art]
2. Description of the Related Art In recent years, hybrid vehicles, electric vehicles, and the like have attracted attention due to environmental issues and the like, and various secondary batteries have been developed for that purpose. Lithium ion secondary batteries are high in energy density, excellent in airtightness, and maintenance-free, and thus are excellent as batteries for hybrid vehicles and electric vehicles, but large-sized batteries have not been put to practical use. Therefore, a plurality of small battery cells are connected in series or in parallel to form a battery pack, and a desired voltage and capacity are secured using this battery pack unit.
[0003]
[Problems to be solved by the invention]
By the way, in a vehicle equipped with this kind of battery pack unit, if a battery failure occurs during traveling, the vehicle may stop. Stopping a car suddenly while driving can be dangerous.
[0004]
The present invention has been made in view of such circumstances, and an object of the present invention is to ensure safety by appropriately operating a fail-safe when a battery pack unit fails.
[0005]
[Means for Solving the Problems]
In order to solve such a problem, a first invention is capable of electrically interrupting an inverter for setting an output of a motor serving as a power source of a vehicle, a battery pack, and a current path between the battery pack and the inverter. An assembled battery unit including a plurality of assembled battery units having a relay connected in parallel, and a control unit that sets a relay of the failed assembled battery unit to a cutoff state when the assembled battery unit fails. Provide system.
[0006]
Here, in the first invention, the control unit may output an instruction to limit the maximum output of the motor to the inverter according to the number of failed battery pack units.
[0007]
In a second aspect of the present invention, in the fail-safe method of the battery pack system, a first step of detecting a failed battery pack unit as a detection target for a battery pack unit group in which a plurality of battery pack units are connected in parallel; And a second step of electrically isolating the failed battery pack unit from the battery pack system.
[0008]
Further, in the present invention, it is preferable that the method further includes a third step of limiting the maximum output of the motor serving as the power source of the vehicle according to the number of failed battery units.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a configuration diagram of the battery pack system according to the present embodiment. In an assembled battery system, an output of a motor 1 serving as a power source of a vehicle is set by an inverter 2. A plurality of battery pack units 3 serving as a power source for supplying power to the motor 1 are connected to the inverter 2 in parallel. The motor 1 is a three-phase AC motor, and a three-phase AC current is supplied from the inverter 2. For this purpose, the inverter 2 converts the DC current supplied from the battery pack unit 3 group into a three-phase AC current. The assembled battery unit 3 includes a plurality of assembled batteries 4 and a relay 5. The assembled battery 4 is configured by connecting a plurality of battery cells stacked one on another in series. The relay 5 electrically cuts off the current path between the battery pack 4 and the inverter 2 when the battery pack unit 3 fails, and separates the failed battery pack 4 from the battery pack system. The cutoff state of the relay 5 is controlled by an output signal from a control unit 6 mainly composed of a microcomputer.
[0010]
Information indicating whether or not each battery unit 3 has failed is input to the control unit 6 using a wired communication unit, for example, a controller area network (CAN). Based on the failure information, the total number of failed battery pack units 3 is specified. Further, sensor signals from the sensors 7 and 8 are input to the inverter 2. The rotation speed sensor 7 is provided in the motor 1, and the rotation speed of the motor 1 is calculated based on the sensor signal. The current sensors 8 are provided for each of the three phases of the motor 1, and a three-phase AC current supplied to the motor 1 is detected based on the sensor signals. The inverter 2 controls the motor 1 so that the actual rotation speed detected by the rotation speed sensor 7 matches the target rotation speed, or the actual current value detected by the current sensor 8 matches the target current value. Set the output.
[0011]
The control unit 6 outputs a signal instructing a cutoff state to the relay 5 corresponding to the battery pack unit 3 in order to electrically disconnect the failed battery pack unit 3. Further, the control unit 6 outputs a control signal for instructing the inverter 2 to limit the maximum output of the motor 1 to the inverter 2 according to the number of failed battery pack units 3.
[0012]
Specifically, the control unit 6 calculates a rate for limiting the maximum output of the motor 1 in accordance with the control programming stored in the ROM according to the number of failed battery pack units 3. FIG. 2 is a flowchart of a control routine according to the present embodiment. The control unit 6 repeatedly executes this control routine at a predetermined interval (for example, 100 ms). First, in step 1, a failed battery pack unit 3 is detected. Specifically, based on the failure information from each of the battery pack units 3a to 3c, the failure state instruction flags Fa to Fc corresponding to the failed battery pack unit are appropriately set to "1".
[0013]
Next, in step 2, it is determined whether or not the number of the failure state instruction flags Fa to Fc being "1" is greater than zero. The failure state instruction flags Fa to Fc are initially set to “0”. Therefore, when all of the flags Fa to Fc are “0”, the process proceeds from step 2 to step 3, and the “normal mode” as initially set is maintained. When the “normal mode” is determined, the motor 1 can be driven at the maximum output without being limited by the output from the control unit 6.
[0014]
On the other hand, when it is determined that the number of the failure state instruction flags Fa to Fc being “1” is greater than 0, the process proceeds from step 2 to step 4 and the “fail-safe mode” is set. When it is determined that the mode is the “fail safe mode”, the control unit 6 executes the fail safe. As a fail-safe, the maximum output of the motor 1 is limited according to the number of failed battery pack units 3. In the present embodiment, when the number of the failure state instruction flags Fa to Fc is “1” is one, the maximum output of the motor 1 is limited to 70%. When the number of the failure state instruction flags Fa to Fc is “1” is two, the maximum output of the motor 1 is limited to 35%. Further, when the number of the failure state instruction flags Fa to Fc is "1" is three, that is, when all the battery pack units 3a to 3c have failed, the battery pack system stops.
[0015]
When the battery pack units 3a to 3c are used in parallel as in this embodiment, for example, when the battery pack unit 3b fails, the relay 5b is turned off, and the battery pack unit 3b is disconnected from the battery pack system. As a result, the safety of the entire battery pack system is ensured, and the vehicle can run with the maximum output being limited to 70% by the battery pack units 3a and 3c. In this state, if a failure of the battery pack unit 3a is added, the relay 5a is also turned off, and the battery pack unit 3a is disconnected from the battery pack system. The maximum output is limited to 35% so that the vehicle can run only with the remaining one battery pack unit 3c, and then the vehicle can run. In this way, the maximum output of the motor 1 is limited according to the number of failed battery pack units 3, and the minimum traveling performance is secured by the remaining battery pack units 3. As a result, the traveling vehicle can be prevented from suddenly stopping, and the minimum traveling performance required to move to a safe place can be ensured.
[0016]
In the present embodiment, an example in which three battery pack units 3 are connected in parallel has been described, but more battery pack units 3 may be connected in parallel to secure a larger capacity.
[0017]
【The invention's effect】
As described above, according to the present invention, when the battery pack unit fails, the safety can be ensured by appropriately operating the fail-safe.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an assembled battery system. FIG. 2 is a flowchart of a control routine according to the present embodiment.
REFERENCE SIGNS LIST 1 motor 2 inverters 3a to 3c battery pack units 4a to 4c battery packs 5a to 5c relay 6 control unit 7 rotation sensor 8 current sensor

Claims (4)

In the assembled battery system,
An inverter for setting an output of a motor serving as a power source of the vehicle;
An assembled battery unit group in which a plurality of assembled battery units having a relay capable of electrically interrupting a current path between the assembled battery and the inverter are connected in parallel with each other,
A controller configured to set the relay of the failed battery unit to a cut-off state when the battery unit fails. The battery pack system according to claim 1, wherein the control unit outputs an instruction to limit the maximum output of the motor to the inverter according to the number of the failed battery pack units. In the fail-safe method of the assembled battery system,
A first step of detecting a failed battery unit with a battery unit group in which a plurality of battery units are connected in parallel detected;
A second step of electrically separating the failed battery pack unit from the battery pack system. 4. The fail safe of the battery pack system according to claim 3, further comprising a third step of limiting a maximum output of a motor serving as a power source of the vehicle according to the number of the failed battery pack units. Method.

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