JP4145448B2 - Power storage device remaining capacity detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a remaining capacity detection device for a power storage device that detects the remaining capacity of the power storage device.
[0002]
[Prior art]
Conventionally, a hybrid vehicle provided with a motor in addition to an engine is known as a driving source for vehicle travel.
One type of hybrid vehicle is a parallel hybrid vehicle that uses a motor as an auxiliary drive source for assisting engine output. This parallel hybrid vehicle, for example, assists the engine output by a motor during acceleration and charges the battery etc. by deceleration regeneration during deceleration to ensure the remaining capacity of the battery. However, the driver's request can be satisfied.
[0003]
As a method for detecting the remaining capacity of the battery, there is a method for calculating the remaining capacity by integrating the battery current. This is a method of detecting the battery current at a predetermined timing and integrating this value to detect the remaining capacity.
However, if the accuracy of the current sensor that detects the battery current is poor, an error occurs in the detected current value. As described above, in this method, the remaining capacity of the battery is obtained by integrating the current value. Therefore, the error is integrated together with the current value, and as a result, the calculated remaining capacity value is Large errors will be included. As described above, the calculation of the remaining capacity based on the current integration has a drawback that the detection accuracy of the remaining capacity is poor because an error occurs in the calculated value of the remaining capacity.
[0004]
In addition to the battery remaining capacity detection method based on the current integration described above, there is a method for detecting the remaining battery capacity from the open circuit voltage of the battery.
This is because the battery current and the battery terminal voltage are sampled at predetermined intervals, and the battery terminal voltage when the battery current = 0, that is, the open-circuit voltage is estimated based on these sampling data, and the remaining capacity specific to the battery -The remaining capacity corresponding to the above open voltage is detected from the open voltage characteristics.
This remaining capacity detection method has an advantage that the remaining capacity detection accuracy is higher than the remaining capacity detection based on the current integration described above.
[0005]
[Problems to be solved by the invention]
However, in the above-described method for detecting the remaining battery capacity from the open circuit voltage of the battery, the open circuit voltage can be accurately estimated during a period in which the amount of change in the battery current is large, and can be effectively used for detecting the remaining capacity. However, there is a drawback that it is difficult to estimate the open-circuit voltage during a period in which the battery current is constant.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a remaining capacity detection device for a power storage device that can improve the accuracy of remaining capacity detection and can detect the remaining capacity in real time. .
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a current detection for detecting a current (battery current Ibatt in the embodiment) of a power storage device (battery 1 in the embodiment) mounted as a vehicle drive source at a predetermined timing. Means (in the embodiment, current sensor 1-2) and the time when the current detection means detects a current value of 0 when the vehicle travels, and is set within a time period until the terminal voltage of the power storage device is stabilized. Voltage detection means (in the embodiment, voltage sensor 1-1) for detecting the terminal voltage (in the embodiment, battery voltage Vbatt) of the power storage device after a predetermined time (in the embodiment, after 1 second of load release); A state determination unit that determines from the current value detected by the current detection means whether the state of the power storage device immediately before a current value of 0 is detected is charging or discharging. (In the embodiment, is performed by the battery control unit 5 corresponds to the step S7) and (in the embodiment, the temperature sensor 1-3) temperature detecting means for detecting a temperature of said power storage device and is detected by said current detecting means Based on the terminal voltage of the power storage device detected by the voltage detection means, the state of the power storage device detected by the state determination means, and the temperature of the power storage device when the measured current value becomes zero. A first remaining capacity detection means (in the embodiment, battery control device 5) that obtains an estimated open circuit voltage from a temporal transition of the terminal voltage obtained in this manner, and obtains a remaining capacity of the power storage device from the estimated open circuit voltage , and the current a second remaining capacity calculating means for calculating the remaining capacity by accumulating the current value detected by the detection means, the remaining capacity was prompted by the second remaining capacity calculating means Characterized by comprising a correction means for correcting, based on the remaining capacity obtained by the first remaining capacity detecting means.
[0008]
As described above, by detecting whether or not the battery load is zero at a predetermined timing, when the battery load is released, that is, when the battery load becomes zero, it is possible to detect the remaining capacity based on the open voltage of the battery. Thus, the remaining capacity of the power storage device can be detected more accurately.
In addition, the open circuit voltage of the power storage device has a characteristic that changes greatly immediately after the load is released, but the remaining capacity is detected from the open circuit voltage even in the region where the open circuit voltage of the power storage device shows a dynamic behavior. Therefore, not only the remaining capacity of the power storage device can be accurately detected, but also the remaining capacity can be detected in real time.
[0010]
Further, the remaining capacity calculated by current integration, which is assumed to have a large error, is a first remaining capacity detecting means for obtaining the remaining capacity from the open circuit voltage of the power storage device, that is, the remaining capacity detection accuracy of the power storage device is exceptional as compared with current integration. By correcting based on the remaining capacity obtained by the excellent detection means, it is possible to detect the remaining capacity of the power storage device more accurately. That is, the effect that the remaining capacity detection accuracy of the power storage device is improved can be obtained.
[0011]
According to a second aspect of the present invention , the first remaining capacity detecting means is based on an open-circuit voltage-remaining capacity characteristic map set for each temperature based on the temperature of the power storage device detected by the temperature detecting means. The remaining capacity of the power storage device is obtained, and the open-circuit voltage-remaining capacity characteristic map is determined based on the behavior of the terminal voltage of the power storage device with respect to temperature, which becomes gentler as the temperature decreases. .
Thereby, the remaining capacity of the power storage device can be detected more accurately.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment adapted for a parallel hybrid vehicle. In this figure, reference numeral 1 denotes a high voltage battery, which is constituted by connecting a plurality of modules in series with a module in which a plurality of cells are connected in series as one unit.
[0013]
The battery 1 is provided with a voltage sensor 1-1 that detects a terminal voltage of the battery 1, a current sensor 1-2 that detects current, and a temperature sensor 1-3 that detects temperature. The battery terminal voltage Vbatt, current Ibatt, and temperature Tbatt are detected and output to the battery control device 5 in response to a signal from the battery control device 5 described later.
Subsequently, reference numeral 2 denotes a power drive unit, which is configured by connecting three switching elements connected in series to each other in parallel.
[0014]
Reference numeral 3 denotes an engine that operates with fuel combustion energy, and reference numeral 4 denotes a motor that is used in combination with the engine 3 and operates with electric energy. The driving forces of both the engine 3 and the motor 4 are transmitted to driving wheels (not shown) via a transmission (not shown) made up of an automatic transmission or a manual transmission. Further, when the hybrid vehicle is decelerated, the driving force is transmitted from the driving wheels to the motor 4, and the motor 4 functions as a generator to generate a so-called regenerative braking force and charge the battery 1. In addition, it is good also as a structure provided with the generator for charge of the battery 1 separately from the motor 4 for a drive.
[0015]
The drive and regeneration of the motor 4 are performed by the power drive unit 2 in response to a control command from the motor control device 6. Specifically, when the switching element inside the power drive unit 2 is turned on and off by the motor control device 6, the electric power from the battery 1 is supplied to the motor 2 via the three-phase line, or the motor 2 Regenerative power is supplied to the battery 1.
[0016]
The battery control device 5 uses the battery terminal voltage Vbatt detected by the voltage sensor 1-1 at a predetermined timing, the battery current Ibatt detected by the current sensor 1-2, and the battery temperature Tbatt detected by the temperature sensor 1-3. The battery remaining capacity SOC is detected from these values.
[0017]
Reference numeral 7 denotes an engine control device that monitors the engine speed NE, vehicle speed, and the like at predetermined intervals to determine modes such as motor regeneration, assist, and deceleration. Further, the engine control device 7 determines the assist / regeneration amount from the result of the mode determination described above and the remaining capacity SOC transmitted from the battery control device 5, and controls the engine 3 such as adjustment of the fuel amount and ignition timing. I do.
The battery control device 5, the motor control device 6, and the engine control device 7 are constituted by a CPU (Central Processing Unit) and a memory, and the functions are realized by executing a program for realizing the functions of the control device. .
[0018]
Next, the remaining battery capacity detection in the first embodiment of the present invention having the above-described configuration will be described in detail with reference to FIG. Note that each process described below is performed by executing a program stored in the memory of the battery control device 5.
[0019]
First, when the ignition is turned on in FIG. 2, in step S1, the battery control device 5 receives the battery terminal voltage Vbatt and the battery temperature Tbatt from the voltage sensor 1-1 and the temperature sensor 1-3, and these values are obtained. Originally, the remaining battery charge SOC is detected in step S2.
By the way, in step S1, since the vehicle is not traveling, the battery 1 is in a state where no current flows. Thus, the battery terminal voltage Vbatt in a state where the battery current Ibatt does not flow for a predetermined period or longer can be regarded as the open circuit voltage OCV.
[0020]
FIG. 3 shows the open circuit voltage OCV-remaining capacity SOC characteristics of the battery 1. As shown in this figure, the open circuit voltage OCV and the remaining capacity SOC of the battery 1 have a correlation, and the correlation differs depending on the battery temperature Tbatt. Therefore, the remaining battery capacity SOC can be detected from the open circuit voltage OCV of the battery and the open circuit voltage OCV-remaining capacity SOC characteristic corresponding to the battery temperature Tbatt at that time.
The open circuit voltage OCV-remaining capacity SOC characteristic is provided for each temperature and stored in a nonvolatile memory in the battery control device 5.
[0021]
Next, the process executed by the battery control device 5 in step S2 will be described in detail. First, the battery control device 5 reads the open circuit voltage OCV-remaining capacity SOC characteristic corresponding to the battery temperature Tbatt detected in step S1 from the above-mentioned memory, and refers to the open circuit voltage OCV-remaining capacity SOC characteristic. The remaining capacity SOC corresponding to the battery terminal voltage Vbatt detected in S1 is detected. Thereby, an accurate battery remaining capacity SOC can be obtained.
[0022]
Next, when the vehicle starts to travel, the value of the battery current Ibatt changes from zero. In step S3, the battery control device 5 receives the battery current Ibatt detected by the current sensor 1-2, and calculates the remaining battery charge SOC by integrating the battery current Ibatt.
Subsequently, in step S4, the battery control device 5 receives the battery temperature Tbatt from the temperature sensor 1-3.
Next, in step S <b> 5, the battery control device 5 determines whether or not the current load of the battery 1 is zero. That is, the battery current Ibatt is received from the current sensor 1-2, and if this value is 0, it is determined that the load = 0.
[0023]
If the load is 0 in step S5, the process proceeds to step S6, and the battery terminal voltage Vbatt at that time is received from the voltage sensor 1-1 after a predetermined time, for example, 1 second after the load release.
Next, in step S7, it is determined whether the state before the release of the load, that is, whether the state of the battery 1 before the time point when the battery current Ibatt detected by the current sensor 1-2 is 0 was a discharge or a charge. This can be determined from the direction of the current Ibatt flowing through the battery 1.
[0024]
If the state before the release of the load is discharge in step S7, the process proceeds to step S8, and the remaining battery charge SOC is detected from the battery terminal voltage Vbatt one second after the release of the load detected in step S6. Hereinafter, this process will be described in detail.
[0025]
First, FIG. 5 shows the transition of the battery terminal voltage Vbatt after the load release at a certain remaining capacity. As shown in the figure, it takes a little time (specifically, about 1 to 3 minutes, about 60 to 180 seconds) until the battery terminal voltage Vbatt is stabilized after the load is released.
[0026]
When the state of the battery 1 before the load release is charging, as shown by L1 in FIG. 5, the battery terminal voltage Vbatt gradually decreases with time, while the state of the battery 1 before the load release is discharged. If there is, the battery terminal voltage Vbatt gradually rises with time as indicated by L2 in FIG. 5, and L1 and L2 converge to a certain voltage value and stabilize. This stable battery terminal voltage Vbatt is the open circuit voltage OCV.
[0027]
As described above, the transition of the battery terminal voltage Vbatt after the load is released changes depending on the battery state before the load release, that is, whether the battery 1 is in the charged state or the discharged state before the load release. To do.
Further, the transition of the battery terminal voltage Vbatt after the load is released also varies depending on the remaining battery capacity SOC and the battery temperature Tbatt.
In other words, if the battery temperature Tbatt, the remaining capacity SOC, and the battery state before the load release are equal, the temporal transition of the battery terminal voltage Vbatt after the load release draws substantially the same curve.
[0028]
FIG. 6 shows a time transition of the battery terminal voltage Vbatt after the load release at different battery temperatures Tbatt. In this figure, M1 and M2 are behaviors of the battery terminal voltage Vbatt when the state of the battery 1 before the release of the load is charging. Among these, M1 shows a case where the battery temperature Tbatt is lower than M2. Yes.
On the other hand, N1 and N2 are behaviors of the battery terminal voltage Vbatt when the state of the battery 1 before the release of the load is discharge. Among these, N1 is the battery terminal voltage Vbatt when the battery temperature Tbatt is lower than N2. Shows the behavior.
[0029]
As shown in this figure, the lower the battery temperature Tbatt, the smoother the transition of the battery terminal voltage Vbatt after the load release, and it takes a long time for the voltage to stabilize.
[0030]
From the characteristics as described above, the value of the open circuit voltage OCV can be estimated from the elapsed time after the release of the load and the battery terminal voltage at that time (any value in the Q region in FIG. 5). Furthermore, since the open circuit voltage OCV and the remaining capacity SOC have a correlation as shown in FIG. 3 as described above, the remaining battery capacity SOC can be obtained from the estimated open circuit voltage OCV.
[0031]
FIG. 4 shows, for example, the correlation between the terminal voltage V0 of the battery 1 and the remaining capacity SOC corresponding to this value when 1 second has elapsed from the load release. In this figure, L1 is the battery terminal voltage V0-remaining capacity SOC characteristic when the battery state before the load release is charging, and L2 is the battery terminal voltage V0 when the battery state before the load release is discharging. -Remaining capacity SOC characteristics.
[0032]
Note that the battery terminal voltage V0-remaining capacity SOC characteristic after 1 second of load release as shown in FIG. 4 is also created for each temperature in the same manner as the open circuit voltage OCV-remaining capacity SOC characteristic. It is stored in a provided non-volatile memory.
[0033]
Next, the process performed by the battery control device 5 in step S8 will be specifically described.
First, in step S4, the battery terminal voltage V0-remaining capacity SOC characteristic (see FIG. 4) after 1 second of load release corresponding to the battery temperature Tbatt detected by the temperature sensor 1-3 is read from the memory. Next, in the battery terminal voltage V0-remaining capacity SOC characteristic, with reference to the discharge-side curve (L2 in FIG. 4), the load release detected by the voltage sensor 1-1 in step S6 is 1 second later. The remaining capacity SOC corresponding to the battery terminal voltage V0 is detected.
[0034]
On the other hand, if it is determined in step S7 that the battery state before release is charging, the process proceeds to step S9, and the battery terminal after 1 second of load release corresponding to the battery temperature Tbatt detected by the temperature sensor 1-3 in step S4. The voltage V0-remaining capacity SOC characteristic (see FIG. 4) is read from the memory. Next, in the battery terminal voltage V0-remaining capacity SOC characteristic, with reference to the charging-side curve (L1 in FIG. 4), one second after the load release detected by the voltage sensor 1-1 in step S6. The remaining capacity SOC corresponding to the battery terminal voltage V0 is detected.
[0035]
When the battery remaining capacity SOC is detected in this way, the battery control device 5 changes the battery remaining capacity SOC calculated by current integration in step S3 to the value of the remaining capacity SOC detected in step S8 or step S9. To do.
In the present embodiment, the battery terminal voltage Vbatt is set to the voltage sensor 1 one second after the load release, that is, one second after the time when the value of the battery current Ibatt detected by the current sensor 1-2 is 0. However, it is possible to arbitrarily set how many seconds after the load release the voltage is detected. Further, the battery terminal voltage-remaining capacity SOC characteristic stored in the memory is also a characteristic at the set time described above.
[0036]
By detecting the remaining capacity of the power storage device in this way, the remaining capacity SOC is detected from the detected open-circuit voltage OCV even in a region (Q region in FIG. 5) in which the change in the open-circuit voltage OCV is large immediately after the release of the load. It becomes possible. As a result, the remaining capacity SOC can be detected in real time at the timing when the load is released, and the remaining capacity can be detected more accurately.
In hybrid vehicles, electric vehicles, and the like, the remaining capacity of the battery is closely related to the control thereof, so that the remaining capacity detection accuracy is improved, so that the control accuracy of the vehicle is also improved.
[0037]
【The invention's effect】
As described above, according to the remaining capacity detection device for a power storage device according to the present invention, a current detection unit that detects a current of the power storage device, and a predetermined time after a time point when a current value of 0 is detected by the current detection unit. A state of determining whether the state of the power storage device immediately before the detection of the current value of 0 is charging or discharging from the voltage detection means for detecting the terminal voltage of the power storage device and the current value detected by the current detection means A determination unit; and a first remaining capacity detection unit that obtains the remaining capacity of the power storage device from the terminal voltage of the power storage device detected by the voltage detection unit and the state of the power storage device determined by the state determination unit. Yes.
[0038]
With this configuration, immediately after the load is released, the remaining capacity is detected from the open voltage of the power storage device, and the remaining night amount calculated by current integration is corrected based on this value. Thereby, the remaining capacity accuracy of the power storage device can be improved.
In addition, since the remaining capacity of the power storage device can be detected simply by detecting the terminal voltage and temperature of the power storage device after a predetermined time from the load release, it is possible to detect the accurate remaining capacity in real time.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a hybrid vehicle.
FIG. 2 is a flowchart showing processing performed by a remaining capacity detection device according to an embodiment of the present invention.
FIG. 3 is a diagram showing an open circuit voltage-remaining capacity characteristic of a power storage device according to an embodiment of the present invention.
FIG. 4 is a diagram showing an open-circuit voltage-remaining capacity characteristic of a power storage device after 1 second of load release in an embodiment of the present invention.
FIG. 5 is a diagram showing a temporal transition of an open-circuit voltage after load release in one embodiment of the present invention.
FIG. 6 is a diagram showing a temporal transition of an open-circuit voltage after load release when battery temperatures are different in an embodiment of the present invention.
[Explanation of symbols]
1 Battery (power storage device)
5 Battery control device 1-1 Voltage sensor (voltage detection means)
1-2 Current sensor (current detection means)
1-3 Temperature sensor (temperature detection means)

Claims (2)

Current detection means for detecting a current of a power storage device mounted as a vehicle drive source at a predetermined timing;
The terminal voltage of the power storage device is detected after a predetermined time set within the time from when the current detection unit detects a current value of 0 when the vehicle travels until the terminal voltage of the power storage device becomes stable. Voltage detection means;
State determination means for determining whether the state of the power storage device immediately before a current value of 0 is detected from the current value detected by the current detection means is charging or discharging;
Temperature detecting means for detecting the temperature of the power storage device;
When the current value detected by the current detection means becomes 0, the terminal voltage of the power storage device detected by the voltage detection means, the state of the power storage device detected by the state determination means , First remaining capacity detection means for obtaining an estimated open-circuit voltage from a temporal transition of the terminal voltage obtained based on the temperature of the power storage device and obtaining a remaining capacity of the power storage device from the estimated open-circuit voltage ;
A second remaining capacity calculating means for calculating the remaining capacity by accumulating the current value detected by said current detecting means,
The remaining capacity et been determined by the second remaining capacity detection means, and correcting means for changing the residual capacity determined by the first remaining capacity detecting means,
A remaining capacity detecting device for a power storage device, comprising: The first remaining capacity detection means, the open circuit voltage is set by the temperature based on the temperature of which is detected by said temperature detecting means and the power storage device - determined remaining capacity of said power storage device by the remaining charge characteristic map, the open 2. The remaining capacity of the power storage device according to claim 1, wherein the voltage-remaining capacity characteristic map is determined based on a behavior of the terminal voltage of the power storage device, which becomes gentler as temperature decreases, with respect to temperature. Detection device.

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