JP2008312396A - Power supply system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply system for a vehicle capable of performing control on abnormality reliably and safely. <P>SOLUTION: A voltage measurement means VM measures a voltage value of each single battery of a battery pack 100, which includes a plurality of single batteries connected in series and supplies electric power to a load. A current measurement means IM measures a current value flowing in the battery pack 100. A memory means MM stores a voltage-current normal range table showing a normal range of current values for voltage values on normal operation of each single battery. A first discrimination means DM1 discriminates whether or not a current value measured by the current measurement means IM for a voltage value measured by the voltage measurement means VM is within the normal range of the voltage-current normal range table stored in the memory means MM. When it is not discriminated by the first discrimination means DM1 that the current value is within the normal range of the normal range table, a breaking means BM shuts down the supply of electric power from the battery pack 100 to the load. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle power supply system used in a vehicle equipped with a high voltage power supply such as a hybrid vehicle.

  Conventionally, in this type of vehicle power supply system, when the detected voltage value is abnormal, the main relay is turned off, and the high-voltage power supply composed of a plurality of single cells and the load are controlled (for example, patent document). 1).

FIG. 6 is a schematic block diagram showing a configuration of a conventional vehicle power supply system. In FIG. 6, the traveling vehicle power supply system includes a lithium secondary battery 2, a lithium battery control unit having a microcomputer 20a, and a vehicle control unit having a microcomputer 30a. Each single battery constituting the lithium secondary battery 2 is connected to a voltage measurement circuit 25 that measures the voltage of each single battery. The vehicle control unit determines whether or not the voltage of each unit cell exceeds a voltage upper limit value that allows safe use of the unit cell every predetermined time, and even if one of the unit cells exceeds the voltage upper limit value, an abnormal voltage is exceeded. Is determined, the switch SW2 is turned off. In this way, charging / discharging of the lithium secondary battery 2 is interrupted at the abnormal voltage.
JP 2004-32871 A (FIG. 2)

  However, in the above-described vehicle power supply system, the abnormality determination is based only on the voltage. In this case, when the measurement value is fixed to a certain value due to the abnormality of the voltage measurement circuit 25, or the lithium battery having the microcomputer 20a. When the switch SW2 cannot be turned off due to an abnormality in the control unit, the lithium secondary battery 2 cannot be cut off, current flows from the lithium secondary battery 2, and the lithium secondary battery 2 is overdischarged. there is a possibility. In particular, in the case of the lithium secondary battery 2, during overdischarge and overcharge, the inside of the battery may be shorted, resulting in a dangerous state. Further, at the moment when the battery voltage largely fluctuates due to the flow of a large current, it may be erroneously determined to be abnormal, and charging / discharging of the lithium secondary battery 2 may be interrupted.

  Therefore, in view of the above-described problems, an object of the present invention is to provide a vehicle power supply system that can perform control at the time of abnormality more reliably and safely.

  In order to solve the above-mentioned problems, the vehicle power supply system according to claim 1 is an assembled battery in which a plurality of single cells are connected in series and supplies power to a load, as shown in the basic configuration diagram of FIG. 100, voltage measuring means VM for measuring the voltage value of each unit cell of the assembled battery 100, current measuring means IM for measuring the current value flowing through the assembled battery 100, and the voltage during normal operation of each unit cell A storage means MM storing a voltage-current normal range table representing a normal range of current values with respect to values, and a current value measured by the current measurement means IM with respect to a voltage value measured by the voltage measurement means VM. First determination means DM1 for determining whether or not the voltage-current normal range table stored in the storage means MM is within a normal range, and the first determination means DM1 determines that the current value is the voltage − Positive current If it is not determined to be within the normal range in the range table, characterized in that it comprises a blocking means BM for blocking the supply of electric power to the load from the battery pack 100.

  In the first aspect of the present invention, the vehicle power supply system includes a plurality of single cells connected in series, and the voltage measurement unit VM measures the voltage value of each single cell of the assembled battery 100 that supplies power to the load. The current value flowing through the battery 100 is measured by the current measuring means IM. The storage means MM stores a voltage-current normal range table representing a normal range of current values with respect to voltage values during normal operation of each unit cell. The first determination unit DM1 is within the normal range of the voltage-current normal range table in which the current value measured by the current measurement unit IM is stored in the storage unit MM with respect to the voltage value measured by the voltage measurement unit VM. It is determined whether or not. When the first determination unit DM1 does not determine that the current value is within the normal range of the voltage-current normal range table, the blocking unit BM blocks the supply of power from the assembled battery 100 to the load. Thereby, overdischarge of the assembled battery 100 can be prevented, and even when the battery voltage largely fluctuates due to a large current flowing, the control at the time of abnormality can be performed more reliably and safely without erroneously judging the abnormality. Can do.

  The vehicle power supply system according to claim 2, which has been made to solve the above-described problem, is a battery pack in which a plurality of single cells are connected in series and supplies power to a load, as shown in the basic configuration diagram of FIG. 2. 100, voltage measuring means VM for measuring the voltage value of each unit cell of the assembled battery 100, current measuring means IM for measuring the current value flowing through the assembled battery 100, and voltage measured by the voltage measuring means VM Voltage change rate calculating means VRM for calculating the rate of change of the value, current change rate calculating means IRM for calculating the rate of change of the current value measured by the current measuring means IM, and the voltage during normal operation of each unit cell Storage means MM storing a voltage change rate-current change rate normal range table representing a normal range of the current change rate with respect to the change rate, and the current change with respect to the voltage change rate calculated by the voltage change rate calculating means VRM. Second determination means DM2 for determining whether or not the current change rate calculated by the rate calculation means IRM is within the normal range of the voltage change rate-current change rate normal range table stored in the storage means MM. When the second determination means DM2 determines that the current change rate is not within the normal range of the voltage change rate-current change rate normal range table, the power from the assembled battery 100 to the load And a shut-off means BM for shutting off the supply.

  According to the second aspect of the invention, the vehicle power supply system includes a plurality of single cells connected in series, and the voltage measurement means VM measures the voltage value of each single cell of the assembled battery 100 that supplies power to the load. The current value flowing through the battery 100 is measured by the current measuring means IM. Then, the change rate of the voltage value measured by the voltage measurement unit VM is calculated by the voltage change rate calculation unit VRM, and the change rate of the current value measured by the current measurement unit IM is calculated by the current change rate calculation unit IRM. To do. The storage means MM stores a voltage change rate-current change rate normal range table representing a normal range of the current change rate with respect to the voltage change rate during normal operation of each unit cell. The current change rate calculated by the current change rate calculating means IRM with respect to the voltage change rate calculated by the voltage change rate calculating means VRM is the voltage change rate-current change rate normal range table stored in the storage means MM. Whether or not it is within the normal range is determined by the second determination means DM2. When the second determination unit DM2 does not determine that the current change rate is within the normal range of the voltage change rate-current change rate normal range table, the blocking unit BM supplies power from the assembled battery 100 to the load. Shut off. Thereby, overdischarge of the assembled battery 100 can be prevented, and even when the battery voltage largely fluctuates due to a large current flowing, the control at the time of abnormality can be performed more reliably and safely without erroneously judging the abnormality. Can do.

  According to the first aspect of the present invention, the voltage value and the current value of the assembled battery 100 are monitored, and control is performed so that the power supply from the assembled battery 100 to the load is interrupted by the interrupting means BM when an abnormality occurs. 100 can be prevented from being overdischarged, and even when the battery voltage fluctuates greatly due to the flow of a large current, the control at the time of abnormality can be performed more reliably and safely without erroneously judging it as an abnormality.

  According to the second aspect of the present invention, the voltage change rate and the current change rate of the assembled battery 100 are monitored, and control is performed so that the supply of power from the assembled battery 100 to the load is interrupted by the interrupting means BM when abnormal. The overdischarge of the assembled battery 100 can be prevented, and even when the battery voltage greatly fluctuates due to a large current flowing, the control at the time of abnormality can be performed more reliably and safely without erroneously determining the abnormality.

  Embodiments of the present invention will be described below with reference to the drawings.

  (First Embodiment) FIG. 3 is a block diagram showing the configuration of a vehicular power supply system according to the first embodiment of the present invention. The electric circuit of a hybrid vehicle includes a low voltage system circuit that operates with a 12V battery and a high voltage system circuit for driving a motor that operates with a high voltage. This vehicle power supply system is used for a high voltage system circuit of a hybrid vehicle. The

  The vehicle power supply system includes an assembled battery 100 in which a plurality of single cells are connected in series, and main relays MR1 and MR2 respectively connected between a positive electrode and a negative electrode of the assembled battery 100 and a motor generator (not shown) as a load. The current sensor IS detects the current flowing through the assembled battery 100, and the battery monitoring unit 200.

  A service plug unit 300 is connected to an intermediate position of the assembled battery 100. The service plug unit 300 includes a service plug SP and a high-voltage fuse HF that are connected in series with the assembled battery 100, and an interlock switch SW.

  The service plug SP is a detachable member that can be removed during maintenance and cut off the assembled battery 100 from the high-voltage circuit so that no electric shock is received even if the maintenance operator accidentally touches the high-voltage circuit. It can be done. The interlock switch SW is a reed switch, which is turned off when the service plug SP is removed, and sends an off signal to a host system (not shown). When an off signal is transmitted from the interlock switch SW, the host system controls the main relays MR1 and MR2 to be turned off and shuts off the high-voltage power supply of the assembled battery 100, thereby ensuring the safety of the maintenance worker.

  The battery monitoring unit 200 includes, for example, a microcomputer including a ROM that stores a control program and data, a RAM that temporarily stores data, and a CPU that executes the control program. The battery monitoring unit 200 includes an input port connected to the positive and negative electrodes of each unit cell constituting the assembled battery 100, an input port connected to the current sensor IS, and an output port connected to the main relays MR1 and MR2. And monitoring the voltage of each unit cell of the assembled battery 100 and the current flowing through the assembled battery 100, and controlling the main relays MR1 and MR2 to be turned off when an abnormality occurs.

  Next, the abnormality detection process performed by the CPU in accordance with the control program stored in the ROM in the battery monitoring unit 200 of the vehicle power supply system having the above-described configuration will be described with reference to the flowchart of FIG.

  The CPU of the battery monitoring unit 200 starts its operation when a power supply (not shown) is turned on, and is always discharged (including when the ignition switch is turned off and when the accessory switch is turned off) and discharged to the motor generator side or charged from the motor generator side. The assembled battery 100 is monitored, and the voltage value of each unit cell input from the input port connected to the positive electrode and the negative electrode of each unit cell constituting the assembled battery 100 is measured and detected at each predetermined measurement timing (step) S1). Next, the current value flowing through the assembled battery 100 input from the input port connected to the current sensor IS is measured and detected (step S3).

  Next, it is determined whether or not the current value detected in step S3 is within the normal range with respect to the voltage value detected in step S1 (step S5). This determination is made by referring to a voltage-current normal range table that is set in advance and stored in an electrically rewritable ROM (storage means) of the battery monitoring unit 200 and indicating a normal range of current with respect to the voltage of the unit cell. Done.

  This voltage-current normal range table is based on the current value-voltage value characteristic (IV characteristic) for each SOC (charging state) or degree of deterioration measured in advance with respect to the single cells constituting the assembled battery 100. It is a table | surface which shows the normal range of the electric current value with respect to each voltage value estimated in consideration of the characteristic variation for every cell. The characteristics of each unit cell may vary due to variations in the materials, dimensions, ambient temperature, etc. that make up the unit cell. This characteristic variation is estimated in advance by taking into account variations in each element such as material, dimensions, etc. The normal range of the current value can be determined based on the estimation result.

  If the detected current value is within the normal range with respect to the detected voltage value, then the process returns to step S1. If the detected current value is not in the normal range with respect to the detected voltage value, or if the voltage corresponding to the detected voltage value is not in the voltage-current normal range table, it is recognized as abnormal and then Then, control signals are output from the output ports connected to the main relays MR1 and MR2, and the main relays MR1 and MR2 are controlled to be turned off (step S7).

  Causes of abnormal current and voltage values include degradation of electrodes, electrolytes, electrolytes, etc., which are components of the cell, voltage measurement system abnormalities, and current value measurement system abnormalities. Even if any abnormality occurs, the power supply system is abnormal, and it is necessary to stop the power supply system.

  As is clear from the above description, step S1 in FIG. 4 corresponds to the voltage measurement means VM in the claims, step S3 corresponds to the current measurement means IM in the claims, and step S5 corresponds to the current measurement means IM in the claims. Corresponding to one determination means DM1, step S7 corresponds to the blocking means BM in the claims. The ROM of the battery monitoring unit 200 corresponds to storage means in the claims.

  As described above, according to the present embodiment, the voltage value and current value of the assembled battery 100 are monitored, and the main relays MR1 and MR2 are controlled to be turned off when an abnormality occurs. Even if the battery voltage fluctuates greatly due to the flow of a large current, if the current value is within the normal range with respect to the voltage value, the control at the time of abnormality is not erroneously determined as abnormal. It is possible to more reliably shut off in a duplex system with the host system. Further, the CPU of the battery monitoring unit 200 starts its operation when a power supply (not shown) is turned on, constantly monitors the assembled battery 100 (including when the ignition switch is turned off and when the accessory switch is turned off), and monitors the voltage of the assembled battery 100, Since the main relays MR1 and MR2 are cut off when the current is abnormal, the high-voltage fuse HF in the service plug unit 300 can be deleted.

  (Second Embodiment) In the first embodiment described above, the voltage value and current value of the assembled battery 100 are monitored and processing is performed at the time of abnormality. The current change rate with respect to the change rate is monitored to determine the presence or absence of abnormality, and control is performed to shut off the main relays MR1 and MR2. As an obvious abnormality example, there is a case where the current value fluctuates greatly even though the voltage value is constant.

  Hereinafter, the abnormality detection process performed by the CPU according to the control program stored in the ROM in the battery monitoring unit 200 of the present embodiment will be described with reference to the flowchart of FIG.

  The CPU of the battery monitoring unit 200 starts its operation when a power supply (not shown) is turned on, and is always discharged (including when the ignition switch is turned off and when the accessory switch is turned off) and discharged to the motor generator side or charged from the motor generator side. The assembled battery 100 is monitored, and the voltage value of each unit cell input from the input port connected to the positive electrode and the negative electrode of each unit cell constituting the assembled battery 100 is measured and detected at each predetermined measurement timing (step) S11). Next, the current value flowing through the assembled battery 100 input from the input port connected to the current sensor IS is measured and detected at each predetermined measurement timing (step S13).

  Next, the voltage change rate α (= dV / dt) is calculated and obtained based on the voltage value detected at the previous measurement timing and the voltage value detected at the current measurement timing (step S15). Next, a current change rate β (= dI / dt) is calculated and obtained based on the current value detected at the previous measurement timing and the current value detected at the current measurement timing (step S17).

  Next, it is determined whether or not the current change rate obtained in step S17 with respect to the voltage change rate obtained in step S15 is within a normal range (step S19). This determination is performed in advance, and is stored in an electrically rewritable ROM (storage means) of the battery monitoring unit 200. The voltage change rate-current indicating the normal range of the current change rate with respect to the voltage change rate of the unit cell. This is done with reference to the normal rate of change table.

  If the obtained current change rate is within the normal range with respect to the obtained voltage change rate, the process returns to step S11. If the calculated current change rate is not within the normal range with respect to the calculated voltage change rate, or the voltage change rate corresponding to the calculated voltage change rate is not in the voltage change rate-current change rate normal range table. Next, a control signal is output from the output ports connected to the main relays MR1 and MR2, and the main relays MR1 and MR2 are controlled to be turned off (step S21).

  As is clear from the above description, step S11 in FIG. 5 corresponds to the voltage measuring means VM in the claims, step S13 corresponds to the current measuring means IM in the claims, and step S15 corresponds to the voltage in the claims. Corresponding to the change rate calculating means VRM, step S17 corresponds to the current change rate calculating means IRM in the claims, step S19 corresponds to the second determining means DM2 in the claims, and step S21 in the claims. This corresponds to the blocking means BM.

  As described above, according to the present embodiment, the voltage change rate and the current change rate of the assembled battery 100 are monitored, and the main relays MR1 and MR2 are controlled to be turned off when an abnormality occurs. In addition to preventing overcharge, even if the battery voltage fluctuates greatly due to a large current flow, it is possible to more reliably control when there is an abnormality without erroneously judging it as abnormal, and it is safe with a dual system with the host system. Can be blocked. Further, the CPU of the battery monitoring unit 200 starts its operation when a power supply (not shown) is turned on, constantly monitors the assembled battery 100 (including when the ignition switch is turned off and when the accessory switch is turned off), and changes in voltage of the assembled battery 100. Since the main relays MR1 and MR2 are cut off when the rate and current change rate are abnormal, the high-voltage fuse HF in the service plug unit 300 can be deleted.

  The charge / discharge characteristics of individual cells are almost determined. For example, the rate of change of voltage and current is determined by the rated capacity, full charge voltage, and end-of-discharge voltage. That is, in both the absolute value comparison of the voltage and current in the first embodiment and the change rate comparison in the second embodiment, if the current flows, the change in voltage can be estimated by calculation according to the characteristics of the battery. In order to ensure the safety of the system, the maximum value of the current that can be flowed is usually determined, so if the maximum value of the current is determined, the maximum value of the voltage change is inevitably determined, and the absolute value also changes. The rate can also be set as a threshold for determining normality / abnormality.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications and applications are possible.

  For example, in the above-described embodiment, the abnormality is detected based on the voltage-current normal range table representing the normal range of the current value with respect to the voltage value during normal operation of each unit cell. You may make it detect abnormality based on the terminal voltage-current normal range table showing the normal range of the current value with respect to the terminal voltage value during operation.

  In the above-described embodiment, the voltage-current normal range table is measured for each SOC (charged state) or for each degree of deterioration. However, instead of this, the temperature for detecting the ambient temperature of the battery pack 100 is detected. A sensor (temperature detection means) may be further provided and measured at each ambient temperature.

  In the above-described embodiment, the case where all the components for detecting an abnormality are included in the high-voltage circuit has been described. However, as another embodiment, the components are divided into a high-voltage circuit and a low-voltage system. A configuration may be adopted in which control signals are exchanged between the two by being distributed in a circuit. For example, the voltage measuring means VM, the current measuring means IM, the cutoff means BM, the temperature detecting means, etc. may be provided in the high voltage system circuit, and the storage means MM and the first determination means DM1 may be provided in the low voltage system circuit. .

It is a basic composition figure showing the basic composition of the power supply system for vehicles of the present invention. It is a basic composition figure showing the basic composition of the power supply system for vehicles of the present invention. 1 is a block diagram showing a configuration of a vehicle power supply system according to a first embodiment of the present invention. (First embodiment) It is a flowchart which shows the abnormality detection process in the power supply system for vehicles of FIG. (First embodiment) It is a flowchart which shows the abnormality detection process in the power supply system for vehicles of FIG. (Second Embodiment) It is a schematic block diagram which shows the structure of the conventional vehicle power supply system.

Explanation of symbols

VM voltage measurement means (CPU of battery monitoring unit 200)
VRM voltage change rate calculation means (CPU of battery monitoring unit 200)
IM current measuring means (current sensor IS, battery monitoring unit 200 CPU)
IRM Current change rate calculation means (CPU of battery monitoring unit 200)
DM1 first determination means (CPU of battery monitoring unit 200)
DM2 Second determination means (CPU of battery monitoring unit 200)
MM storage means (ROM of battery monitoring unit 200)
BM cutoff means (CPU of battery monitoring unit 200, main relays MR1, MR2)
100 batteries

Claims (2)

A battery pack in which a plurality of cells are connected in series to supply power to a load;
Voltage measuring means for measuring a voltage value of each unit cell of the assembled battery;
Current measuring means for measuring a current value flowing through the assembled battery;
Storage means for storing a voltage-current normal range table representing a normal range of current values relative to voltage values during normal operation of each of the cells;
It is determined whether the current value measured by the current measuring unit is within the normal range of the voltage-current normal range table stored in the storage unit with respect to the voltage value measured by the voltage measuring unit. First determining means for
A blocking means for blocking power supply from the assembled battery to the load when the first determination means does not determine that the current value is within the normal range of the voltage-current normal range table;
A vehicle power supply system comprising: A battery pack in which a plurality of cells are connected in series to supply power to a load;
Voltage measuring means for measuring a voltage value of each unit cell of the assembled battery;
Current measuring means for measuring a current value flowing through the assembled battery;
Voltage change rate calculating means for calculating a change rate of the voltage value measured by the voltage measuring means;
Current change rate calculating means for calculating a change rate of the current value measured by the current measuring means;
Storage means for storing a voltage change rate-current change rate normal range table representing a normal range of the current change rate with respect to the voltage change rate during normal operation of each unit cell;
The voltage change rate-current change rate normal range table in which the current change rate calculated by the current change rate calculating unit with respect to the voltage change rate calculated by the voltage change rate calculating unit is stored in the storage unit. Second determination means for determining whether or not the current value is within the normal range of
When the second determination means does not determine that the current change rate is within the normal range of the voltage change rate-current change rate normal range table, the power supply from the assembled battery to the load is cut off. Blocking means to
A vehicle power supply system comprising:

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