JP2004325263A - Self-discharge amount detection device of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-discharge amount detection device of a battery for detecting the self-discharge amount of the battery during parking by minimizing power consumption of the battery. <P>SOLUTION: The voltage of a battery pack 2 in the no-load state is estimated from the voltage of the battery pack 2 in the loaded state just before the ignition-off time, and the voltage of the battery pack 2 in the no-load state just after the ignition-on time is subtracted from the estimated voltage of the battery pack 2, and the self-discharge amount of the battery pack 2 during the parking time from the ignition-off time until the ignition-on time is calculated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for detecting a state of a battery provided in a vehicle, and particularly to a self-discharge amount.
[0002]
[Prior art]
An electric vehicle control device is known which intermittently detects the amount of self-discharge in a parked vehicle and subtracts the amount of self-discharge during parking from the remaining capacity immediately before parking to accurately detect the remaining capacity of the battery. (For example, see Patent Document 1).
[0003]
Prior art documents related to the invention of this application include the following.
[Patent Document 1]
JP-A-11-150878
[Problems to be solved by the invention]
However, in the above-described conventional apparatus, the amount of self-discharge is detected intermittently during parking, so that the battery power is consumed for self-discharge detection in addition to self-discharge of the battery during parking. There is a problem that
[0005]
SUMMARY OF THE INVENTION The present invention provides a battery self-discharge amount detection device that detects the self-discharge amount of a parked battery while minimizing the power consumption of the battery.
[0006]
[Means for Solving the Problems]
The present invention estimates the voltage of the battery pack in the no-load state from the voltage of the battery pack in the load state immediately before the ignition is turned off, and estimates the voltage of the battery pack in the no-load state immediately after the ignition is turned on from the estimated battery voltage. In other words, the self-discharge amount of the battery pack during the parking time from the ignition off to the ignition on is calculated.
[0007]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the self-discharge amount of the battery in parking can be calculated | required accurately, minimizing the power consumption of a battery.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment in which the present invention is applied to an electric vehicle will be described. FIG. 1 shows a configuration of an embodiment. The electric vehicle is equipped with a high-voltage battery 2 serving as a power supply for driving the traveling motor 1. In this embodiment, the self-discharge amount of the high-voltage battery 2 and the abnormality of the self-discharge are detected. The electric vehicle includes, in addition to the high-voltage battery 2, an auxiliary power supply 5 for supplying a low-voltage control power supply to a battery controller 3 and a vehicle controller 4, which will be described later, and a timer power supply 3c for supplying a dedicated power supply to the timer 3b. ing.
[0009]
The high-voltage battery 2 is an assembled battery formed by connecting a plurality of battery modules M in which a plurality of battery cells C are connected in series. This embodiment shows an example in which three sets of battery modules M1 to M3 in which a plurality of battery cells C are connected in series are connected in series. The high-voltage battery 2 is a lithium-ion battery.
[0010]
The high-voltage DC power of the high-voltage battery 2 is supplied to an auxiliary system 7 and an inverter 8 via a relay 6. The accessory system 7 is an in-vehicle device such as an air conditioner and an electric power steering. The inverter 8 converts high-voltage DC power of the high-voltage battery 2 into AC power and supplies the AC power to the traveling motor 1.
[0011]
The battery controller 3 includes a CPU 3a, a timer 3b, a timer power supply 3c, a memory 3d, a cell voltage detection circuit 3e, and performs charge / discharge control of the high-voltage battery 2 and management of self-discharge. The timer 3b measures the parking time of the vehicle, more specifically, the time during which the ignition switch 9 is turned off. The timer power supply 3c is a dedicated power supply for the timer 3b, and always supplies power to the timer 3b regardless of whether the ignition switch 9 of the vehicle is on or off.
[0012]
The memory 3d stores, in addition to various maps and tables, data such as a voltage (hereinafter, referred to as a cell voltage) Vc across each battery cell C constituting the high-voltage battery 2. The cell voltage detection circuit 3e detects the cell voltage Vc of each battery cell C.
[0013]
The battery controller 3 also includes a temperature sensor 10 for detecting the temperature of the high-voltage battery 2, a voltage sensor 11 for detecting a voltage Vb across the high-voltage battery 2 (hereinafter referred to as a battery voltage), and a charge / discharge current Ib for the high-voltage battery 2. Current sensor 12 is connected. The temperature sensor 10 is provided with three temperature detecting elements for each of the battery modules M1, M2, and M3, and includes a place where the temperature of each module is expected to be high, a place where the temperature is expected to be intermediate, and a temperature. Are expected to be low.
[0014]
The charge / discharge current Ib of the high-voltage battery 2 detected by the current sensor 12 is such that the discharge current from the high-voltage battery 2 to the auxiliary system 7 and the inverter 8 is positive, and the charge / discharge current from the auxiliary system 7 and the inverter 8 to the high-voltage battery 2 Is negative.
[0015]
The vehicle sensor 4 includes a CPU 4a, a memory 4b, and the like. The vehicle sensor 4 controls the inverter 8 to drive the traveling motor 1 and controls the driving of the accessory system 7. The vehicle controller 4 is connected to an ignition switch 9, an accelerator sensor 13 for detecting an amount of depression of an accelerator pedal, a brake sensor 14 for detecting a depression pressure of a brake pedal, a vehicle speed sensor 15 for detecting a vehicle speed, a warning light 16, and the like. .
[0016]
The vehicle controller 4 obtains information on the high-voltage battery 2 from the battery controller 3 via the communication line 17 and detects the accelerator pedal depression amount, the brake pedal depression pressure, and the vehicle speed using the sensors 13 to 15 described above. The driving force of the vehicle is calculated on the basis of the above, and the driving control of the traveling motor 1 is performed.
[0017]
Low-voltage control power is supplied to the battery controller 3 and the vehicle controller 4 from the auxiliary power supply 5 via the relay 18. The relay 18 is turned on as soon as the ignition switch 9 is turned on, and starts supplying control power from the auxiliary power supply 5 to the battery controller 3 and the vehicle controller 4. After the ignition switch 9 is turned off, the relay 18 is turned off when the battery controller 3 completes a process after the ignition is turned off, which will be described later, and stops supplying control power to the battery controller 3 and the vehicle controller 4.
[0018]
In this embodiment, the cell voltage Vc_on of the high-voltage battery 2 immediately after the ignition is turned on is detected, and the cell voltage Vc_off of the high-voltage battery 2 is detected immediately before the ignition is turned off. , The cell voltage Vc_on immediately after the ignition is turned on is subtracted, and the self-discharge amount Vd of the high-voltage battery 2 during the parking period from the ignition off to the ignition is obtained. Then, the self-discharge amount Vd is compared with the abnormality determination reference value, and it is determined that the battery cell C whose self-discharge amount Vd is equal to or more than the abnormality determination reference value is abnormal.
[0019]
The cell voltage Vc of each battery cell C is detected by the cell voltage detection circuit 3e. The detected value is subjected to temperature correction and deterioration correction, and the cell voltage Vc in the load state immediately before the ignition is turned off is set in the no-load state. To the cell voltage Vc.
[0020]
FIG. 2 is a flowchart showing a self-discharge management program for the high-voltage battery 2 according to one embodiment. The operation of the embodiment will be described with reference to this flowchart. When the CPU 3a of the battery controller 3 receives the on information of the ignition switch 9 via the vehicle controller 4, the CPU 3a starts executing the self-discharge management program.
[0021]
In step 1, before the relay 6 is turned on, the cell voltage (open cell voltage) Vc of each battery cell C in an unloaded state is detected by the cell voltage detection circuit 3e. In the following step 2, the temperature sensor 10 detects the average temperature of each of the battery modules M1, M2, and M3 (hereinafter referred to as module average temperature), and based on the module average temperature of each of the battery modules M1, M2, and M3, 2. An average temperature of the whole (hereinafter referred to as battery temperature Tb) is obtained.
[0022]
In step 3, the time from the off to the on of the ignition switch 9 measured by the timer 3b, that is, the parking time tp is detected. In step 4, a temperature correction coefficient kT of the cell voltage Vc corresponding to the battery temperature Tb is searched from the map shown in FIG.
[0023]
FIG. 4 is a map showing a temperature correction coefficient kT of the cell voltage Vc with respect to the battery temperature Tb. The temperature coefficient kT when the battery temperature Tb is room temperature 20 ° C. is set to 1. The temperature coefficient kT increases as the battery temperature Tb becomes higher than 20 ° C., and the temperature coefficient kT decreases as the battery temperature Tb becomes lower than 20 ° C.
[0024]
In step 5, the cell voltage Vc of each battery cell C detected in step 1 is corrected by multiplying by the temperature coefficient kT, and the cell voltage Vc_on of each battery cell C after temperature correction is obtained. The cell voltage Vc_on is a cell voltage in a no-load state immediately after the ignition is turned on, that is, an open cell voltage. In step 6, the self-discharge amount Vd of the high-voltage battery 2 during the parking time tp is determined.
[0025]
Specifically, the cell voltage Vc_on immediately after the ignition is determined in step 5 is subtracted for each battery cell C from the cell voltage Vc_off of each battery cell C immediately before the ignition is described below, and the parking time tp for each battery cell C is determined. The self-discharge amount Pc is obtained. Note that the cell voltage Vc_on immediately after the ignition is turned on is a cell voltage in a no-load state (open state) after temperature correction. The cell voltage Vc_off immediately before the ignition is turned off is a cell voltage obtained by converting a cell voltage in a loaded state into a cell voltage in a non-loaded state and then performing a temperature correction and a deterioration correction, which will be described in detail later.
[0026]
In step 7, an abnormality determination reference value corresponding to the SOC immediately before the ignition is turned off and the parking time tp is interpolated from the abnormality determination reference value table of the self-discharge amount Vd shown in FIG. In FIG. 5, for example, when the parking time tp is 24 h and the SOC immediately before the ignition is turned off is 90%, the abnormality determination reference value is 6 mV / cell, so the self-discharge amount Vd during parking is less than 6 mV. Is normal, and the battery cell C of 6 mV or more is determined to be abnormal.
[0027]
In step 8, it is checked whether or not there is any battery cell C whose self-discharge amount is determined to be abnormal when the self-discharge amount Vd during parking is equal to or larger than the abnormality determination reference value. The process proceeds to step 9 and if there is no abnormal cell, the process proceeds to step 11.
[0028]
If there is a battery cell C having a self-discharge amount abnormality, a self-discharge amount abnormality signal is output to the vehicle controller 4 in step 9 and the warning light 16 is turned on by the vehicle controller 4. In the following step 10, the charge / discharge limit value of the high-voltage battery 2 is determined based on the number of battery cells C in which the self-discharge amount abnormality has occurred, and is output to the vehicle controller 4. The vehicle controller 4 limits the charge / discharge capacity of the high-voltage battery 2 based on the charge / discharge limit value.
[0029]
In step 11, the deterioration coefficient kR of the high-voltage battery 2 is calculated, and the previous value stored in the memory 3d is updated. Specifically, the voltage sensor 11 detects the battery voltage Vb of the high-voltage battery 2 at a plurality of time points, and the current sensor 12 detects the charge / discharge current Ib of the high-voltage battery 2 at a plurality of time points. Vb and the charging / discharging current Ib are plotted on a two-dimensional plane and linearly regressed, and the resistance of the high-voltage battery 2 is calculated from the slope of the regression line. By dividing this resistance value by the resistance value at the time of new product stored in the memory 3d in advance, the deterioration coefficient kR of the high-voltage battery 2 is obtained.
[0030]
In the following step 12, the SOC of the high-voltage battery 2 is detected, and the previous value stored in the memory 3d is updated. Specifically, the characteristics of the SOC of the high-voltage battery 2 with respect to the battery voltage Vb are detected in advance, and a characteristic map as shown in FIG. 6 is stored in the memory 3d. Then, the SOC corresponding to the battery voltage Vb detected by the voltage sensor 11 is calculated from the characteristic map shown in FIG.
[0031]
In step 13, the charge / discharge current Ib by the current sensor 12, the cell voltage Vc for each battery cell C by the cell voltage detection circuit 3e, and the battery temperature Tb by the temperature sensor 10 are sequentially repeated for a predetermined time, for example, 5 seconds. Detect and update the previous data stored in the memory 3d. For example, if the charge / discharge current Ib, cell voltage Vc, and battery temperature Tb are detected and stored every second, five sets of data are sampled and updated to the latest data in five seconds.
[0032]
In step 14, it is confirmed whether or not the ignition switch 9 has been turned off. If not, the process returns to step 11. Therefore, while the ignition switch 9 is on, the latest data of the high-voltage battery 2, that is, the deterioration coefficient kR, the SOC, the charging / discharging current Ib, the cell voltage Vc, and the battery temperature Tb are calculated or calculated in steps 11 to 13 at any time. The detected value is updated, and the value stored in the memory 3d is updated.
[0033]
On the other hand, when the ignition switch 9 is turned off, the deterioration coefficient kR, the SOC, the charge / discharge current Ib, the cell voltage Vc, and the battery temperature Tb stored in the memory 3d are the latest data immediately before the ignition is turned off. When the ignition switch 9 is turned off, the routine proceeds to step 15, where the latest deterioration coefficient kR, SOC, cell voltage Vc and battery temperature Tb of each battery cell C of the high voltage battery 2 are read from the memory 3d immediately before the ignition is turned off.
[0034]
In step 16, a correction value for the latest cell voltage Vc immediately before the ignition is turned off is calculated. In general, a battery has a different cell voltage between a loaded state, that is, a charge / discharge state, and a no-load state, that is, an open-terminal state. As described above, since the cell voltage Vc_on immediately after the ignition is turned on is the open cell voltage in the no-load state, the cell voltage Vc in the load state immediately before the ignition is turned off is converted into the cell voltage in the no-load state, and the cell voltage under the same condition is converted. To calculate the self-discharge amount Vd of the battery cell C.
[0035]
First, the charge / discharge current Ib sampled during a predetermined time (here, 5 seconds) immediately before the ignition is turned off is read out from the memory 3d, and is squared to obtain the load of the high-voltage battery 2 immediately before the ignition is turned off. Next, from the cell voltage correction value table (see FIG. 7) stored in the memory 3d, the cell voltage Vc corresponding to the load of the high-voltage battery 2 (the square integrated value of the charging / discharging current Ib) and the SOC immediately before the ignition is turned off. Interpolate the correction value of. Specifically, when the square integrated value of the charge and discharge current Ib at SOC 80% is 20A ^2, the cell voltage correction value is 6.5 mV.
[0036]
In step 17, the cell voltage Vc of each battery cell C is corrected using the correction value according to the SOC and load of the high-voltage battery 2 immediately before the ignition is turned off. At this time, when the charging / discharging current Ib immediately before the ignition is turned off is positive and the high-voltage battery 2 is in a discharging state, a correction value is added to the cell voltage Vc of each battery cell C, and conversely, the charging / discharging immediately before the ignition is turned off. When the current Ib is negative and the high-voltage battery 2 is in a charged state, the correction value is subtracted from the cell voltage Vc of each battery cell C.
[0037]
The corrected cell voltage Vc is obtained by converting a cell voltage in a load state immediately before ignition is turned off to a stable open cell voltage in a no-load state.
[0038]
In step 18, a temperature correction coefficient kT of the cell voltage Vc corresponding to the latest battery temperature Tb immediately before the ignition is turned off is searched from the map shown in FIG. In a succeeding step 19, the cell voltage Vc of each battery cell C corrected according to the SOC and load of the high-voltage battery 2 is multiplied by the temperature correction coefficient kT and the latest deterioration coefficient kR immediately before the ignition is turned off. The cell voltage Vc is corrected based on the deterioration state and the temperature of No. 2.
[0039]
In step 20, the corrected cell voltage Vc of each battery cell C is stored in the memory 3d as the cell voltage Vc_off in the no-load state of each battery cell C immediately before the ignition is turned off, that is, immediately before entering the parking state. In the following step 21, the timer 3b is started to start measuring the parking time tp, and the relay 18 is turned off to stop supplying the control power from the auxiliary power supply 5 to the battery controller 3 and the vehicle controller 4.
[0040]
As described above, according to the embodiment, the cell voltage Vc_off of the battery pack in the no-load state is estimated by calculation from the cell voltage of the battery pack (high-voltage battery 2) in the load state immediately before the ignition is turned off. Since the cell voltage Vc_on of the battery pack in the no-load state immediately after the ignition is turned on is subtracted from the cell voltage Vc_off of the battery pack, the self-discharge amount Vd of the battery pack during the parking time tp from the time when the ignition is turned off to the time when the ignition is turned on is calculated. It is not necessary to detect the self-discharge amount by intermittently consuming the power of the control power source during parking as in the related art, and a small amount of time is required for the calculation process of the cell voltage Vc_off immediately after the ignition is turned off and the timer for measuring the parking time. An accurate self-discharge amount Vd during parking can be obtained only by the power consumption of the control power supply.
[0041]
In one embodiment, when the self-discharge amount Vd of the battery pack (high-voltage battery 2) is equal to or greater than a predetermined reference value, it is determined that the battery pack is abnormal, so that the battery pack abnormality can be reliably detected. Further, since the abnormality determination reference value is set based on the parking time tp and the SOC of the battery pack, an accurate abnormality determination can be performed based on an appropriate determination reference value according to the parking time and the SOC of the battery pack.
[0042]
According to one embodiment, the cell voltage Vc_off of the battery pack in the no-load state immediately before the ignition is turned off is estimated based on the charge / discharge current Ib and the SOC of the battery pack (the high-voltage battery 2) immediately before the ignition turns off. The cell voltage Vc_off of the assembled battery in the no-load state can be accurately estimated.
[0043]
In one embodiment, since the cell voltages Vc_on and Vc_off of the assembled battery (high-voltage battery 2) are corrected according to the temperature of the assembled battery, the self-discharge amount Vd is accurate even when the temperature environment of the assembled battery changes. Can be requested. Further, in one embodiment, the cell voltage Vc_off of the battery pack (high-voltage battery 2) immediately before the ignition is turned off is corrected according to the degree of deterioration of the battery pack. The quantity Vd can be determined.
[0044]
The correspondence between the components of the claims and the components of the embodiment is as follows. That is, the cell voltage detection circuit 3e and the voltage sensor 11 serve as voltage detection means, and the CPU 3a of the battery controller 3 uses the voltage estimation means, self-discharge amount calculation means, abnormality determination means, SOC detection means, temperature correction means, deterioration detection means and deterioration detection means. The correction means, the current sensor 12 constitutes a current detection means, and the temperature sensor 10 constitutes a temperature detection means. Note that each component is not limited to the above configuration as long as the characteristic functions of the present invention are not impaired.
[0045]
In the above-described embodiment, an example in which the present invention is applied to an electric vehicle is described. However, the present invention is not limited to an electric vehicle, and can be applied to an assembled battery mounted on an engine vehicle or a hybrid vehicle.
[0046]
In the above-described embodiment, an example in which a lithium-ion battery is used as the high-voltage battery 2 has been described. However, the type of battery is not limited to a lithium-ion battery, and may be, for example, a nickel-manganese battery. Further, the number of battery modules constituting the high-voltage battery and the number of battery cells constituting the battery module are not limited to the configuration of the above-described embodiment. Furthermore, the configuration of the series-parallel connection of the battery cells or battery modules of the high-voltage battery is not limited to the configuration of the above-described embodiment.
[0047]
In the above-described embodiment, an example is described in which the cell voltage Vc is detected for each battery cell C of the high-voltage battery 2 and the amount of self-discharge of the high-voltage battery 2 during parking is managed based on the cell voltage Vc of each battery cell C. Although shown, the voltage (module voltage) at both ends of each battery module M may be detected, and the self-discharge amount of the parked high-voltage battery 2 may be managed based on the module voltage of each battery module. Further, the voltage between both ends of the high-voltage battery 2, that is, the battery voltage may be detected, and the self-discharge amount of the high-voltage battery 2 during parking may be managed based on the battery voltage. Note that the module voltage and the battery voltage can be obtained from the sum of the cell voltages Vc of the battery cells C detected by the cell voltage detection circuit 3e.
[0048]
In the above-described embodiment, an example has been described in which the voltage in the loaded state of the battery pack immediately before the ignition is turned off is converted to the voltage in the no-load state based on the charge / discharge current and the SOC of the battery pack immediately before the ignition is turned off. Alternatively, the voltage in the load state of the battery pack immediately before the ignition is turned off may be converted to the voltage in the no-load state based on only the charge / discharge current of the battery pack immediately before the ignition turns off.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment.
FIG. 2 is a flowchart showing a self-discharge management program according to one embodiment.
FIG. 3 is a flowchart showing a self-discharge management program according to one embodiment, following FIG. 2;
FIG. 4 is a diagram showing a temperature correction coefficient map of a cell voltage.
FIG. 5 is a diagram showing an abnormality determination reference value table for a self-discharge amount of a battery cell.
FIG. 6 is a diagram showing a characteristic map of SOC with respect to battery voltage.
FIG. 7 is a diagram showing a cell voltage correction value table for the SOC and load of the high-voltage battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Running motor 2 High voltage battery M1-M3 Battery module C Battery cell 3 Battery controller 3a CPU
3b Timer 3c Timer power supply 3d Memory 3e Cell voltage detection circuit 4 Vehicle controller 4a CPU
4b memory 5 auxiliary power supply 6 relay 7 auxiliary system 8 inverter 9 ignition switch 10 temperature sensor 11 voltage sensor 12 current sensor 13 accelerator sensor 14 brake sensor 15 vehicle speed sensor 16 warning light 17 communication line 18 relay

Claims (8)

An apparatus for detecting a self-discharge amount of an assembled battery mounted on a vehicle,
Voltage detection means for detecting the voltage of the battery pack;
Voltage estimating means for estimating the voltage of the battery pack in a no-load state from the voltage of the battery pack in a load state immediately before ignition-off,
From the voltage of the battery pack estimated by the voltage estimating means, the voltage of the battery pack in a no-load state immediately after ignition is turned on is subtracted to calculate the self-discharge amount of the battery pack during the parking time from ignition off to on. A battery self-discharge amount detecting device, comprising: The battery self-discharge amount detection device according to claim 1,
An apparatus for detecting the amount of self-discharge of a battery, comprising: abnormality determining means for determining that the assembled battery is abnormal when the amount of self-discharge of the assembled battery is equal to or greater than a predetermined reference value. The battery self-discharge amount detection device according to claim 1 or 2,
A current detecting means for detecting a charge / discharge current of the battery pack;
The battery self-discharge amount detection device, wherein the voltage estimating means estimates a voltage of the battery pack in a no-load state based on a charge / discharge current of the battery pack immediately before ignition is turned off. The battery self-discharge amount detection device according to claim 3,
SOC detecting means for detecting the SOC of the battery pack,
The battery self-discharge amount detecting device, wherein the voltage estimating means estimates a voltage of the battery pack in a no-load state based on a charge / discharge current and an SOC of the battery pack immediately before ignition is turned off. The device for detecting the amount of self-discharge of a battery according to any one of claims 1 to 4,
Temperature detection means for detecting the temperature of the battery pack;
Temperature correction for correcting the voltage of the battery pack estimated by the voltage estimating means and the voltage of the battery pack in a no-load state immediately after the ignition is turned on detected by the voltage detecting means in accordance with the temperature of the battery pack. Means for detecting the amount of self-discharge of a battery. The device for detecting the amount of self-discharge of a battery according to any one of claims 1 to 4,
Deterioration detection means for detecting the degree of deterioration of the battery pack;
A battery self-discharge amount detection device, comprising: a deterioration correction unit that corrects the voltage of the battery pack estimated by the voltage estimation unit in accordance with the degree of deterioration of the battery pack. The battery self-discharge amount detection device according to claim 2,
The self-discharge amount detecting device for a battery, wherein the reference value is set based on a parking time from an ignition off to an ignition on. The battery self-discharge amount detection device according to claim 2,
SOC detecting means for detecting the SOC of the battery pack,
The self-discharge amount detecting device for a battery, wherein the reference value is set based on an SOC of the battery pack.

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