JPH11174134A - Device for detecting recharged amount of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for accurately detecting a recharged amount of a battery. SOLUTION: A battery ECU 68 estimates SOC (recharged amount) by integrating charge/discharge current of a battery 50 and corrects an estimation value from the charge/discharge current of SOC to 20 or 80%, respectively, when SOC being calculated from the terminal voltage and the discharge/charge current of the battery reaches an IV judgment region that is 20% or less or 80% or higher. The correction is not resumed until the estimation value of SOC escapes from the IV judgment region once the correction is executed, thus accurately correcting the estimation value of SOC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charge detection device for detecting the charge of a secondary battery.

[0002]

2. Description of the Related Art Electric vehicles (including hybrid vehicles) in which all or part of the vehicle driving force is obtained by an electric motor.
Is equipped with a secondary battery (hereinafter simply referred to as a battery), and drives the electric motor by the electric power stored in the battery. A function unique to such an electric vehicle is regenerative braking. In the regenerative braking, the kinetic energy of the vehicle is converted into electric energy by performing the braking by causing the electric motor to function as a generator at the time of vehicle braking. The obtained electric energy is stored in the battery and is reused when accelerating. Therefore, according to the regenerative braking, in a conventional vehicle that runs only by the internal combustion engine, it is possible to reuse the energy that has been radiated into the atmosphere as heat energy, and it is possible to greatly improve the energy efficiency. it can.

Here, in order to effectively store the electric power generated during the regenerative braking in the battery, the battery needs to have a sufficient margin. Further, in a hybrid vehicle of a type in which a generator can be driven by a heat engine mounted on a vehicle to generate power and charge the battery, the power stored in the battery, that is, the amount of stored power can be freely controlled. . Therefore, in the above-described hybrid vehicle, the charged amount of the battery is set to the fully charged state (100) so that regenerative power can be received from the battery and power can be immediately supplied to the motor when requested. %) And approximately in the middle of the state where no electricity is stored (0%), for example, 50 to 60
% Is desirably controlled. Therefore, it is necessary to accurately detect the charged amount of the battery.

The relationship between the amount of charge (SOC) and the terminal voltage of such a battery, for example, a nickel-metal hydride battery, has characteristics as shown in FIG. In FIG. 6, in the region where the SOC is more than 20% to less than 80%, the terminal voltage hardly changes, and this change cannot be detected from the outside. On the other hand, when the SOC is lower than around 20% and higher than around 80%, the SO
If C changes, this change appears as a change in terminal voltage. This change can be detected from outside the battery. Therefore, when the SOC is about 20% or less and about 80% or more, the SOC can be calculated based on the terminal voltage and the current flowing through the battery. A method of calculating the SOC based on the terminal voltage and the current is hereinafter referred to as IV determination,
This area is referred to as an IV determination area. On the other hand, SOC is about 20
Since the change in the terminal voltage cannot be detected from the outside in the range between about 80% and about 80%, it is necessary to estimate the SOC by integrating the current flowing through the battery.

In a hybrid vehicle, charge and discharge of a battery are repeated, and the SOC of the battery changes every moment. Normally, this SOC is obtained by sequentially integrating the current amount with respect to the initial value, and is estimated as the SOC at that time. In this integration, the calculation is performed with the current during charging as positive and the current during discharging as negative. The estimated value is deviated from the actual SOC due to a change in the charging efficiency depending on environmental conditions such as temperature and a self-discharge such as when left for a long time.

In order to correct this deviation, the SOC is calculated based on the terminal voltage and the current flowing through the battery. When it is estimated that the calculated SOC has entered the IV determination region, the estimated value of the SOC is corrected. This correction makes the estimated value of SOC 20% when the SOC decreases and reaches 20%, and sets the estimated value of SOC to 80% when the SOC increases and reaches 80%.

[0007] The SOC detection method as described above is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-59003.

[0008]

However, the conventional S
In the OC detection method, the correction of the estimated value of the SOC is performed at predetermined time intervals while the SOC is in the IV determination region. As described above, this correction is performed when the actual SOC is 20% or less or 80% depending on the charging and discharging of the battery.
Even if it is above, the value is fixed to 20% or 80%. Therefore, there is a problem that the actual SOC is deviated from the estimated value by the correction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a battery charge detection device having high detection accuracy of the charge of the battery.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a battery storage amount detection device according to the present invention uses a battery characteristic that can be detected from the outside to detect the storage amount of a secondary battery. A battery storage amount detection device comprising: an amount detection unit; and a region defining unit that defines a current-voltage region in which the detection by the storage amount detection unit is performed, wherein the detection by the storage amount detection unit is performed. Confirmation means for confirming that a sufficient amount of charge or discharge to escape the current-voltage area defined by the area definition means has been performed; And a prohibition unit for prohibiting the detection operation by

[0011] In the above-described battery storage amount detection device,
The battery characteristics used by the charged amount detection means are current-voltage characteristics.

Further, in the above-described battery storage amount detection device,
The battery characteristic used by the charged amount detection means is dT / dt
Characteristic (T is battery temperature, t is time).

[0013] In the above-described battery charge detection device,
It is characterized in that the confirmation means confirms a predetermined amount of charge or discharge by current integration.

[0014]

Embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a power plant of a vehicle equipped with the charging control device of the present invention. A planetary gear mechanism 16 is connected to an output shaft 12 of the engine 10 through a torsion damper 14.
Planetary carrier 2 supporting planetary gear 18
0 is connected. Sun gear 22 of planetary gear mechanism 16
And ring gear 24 are connected to rotors 30 and 32 of first motor generator 26 and second motor generator 28, respectively.
It is connected to the. First and second motor generators 26 and 28 function as a three-phase AC generator or a three-phase AC motor. A power take-out gear 34 is further connected to the ring gear 24. Power take-out gear 34
Is connected to a differential gear 40 via a chain 36 and a gear train 38. The output side of the differential gear 40 is connected to a drive shaft 42 to which a drive wheel (not shown) is coupled at the end. With the above structure, the output of the engine 10 or the first and second motor generators 26 and 28 is transmitted to the drive wheels,
Drive the vehicle.

The output and rotation of the engine 10 are performed by an engine ECU 46 based on the operation amount of an accelerator pedal 44, environmental conditions such as cooling water temperature and intake pipe negative pressure, and the operating conditions of the first and second motor generators 26 and 28. The number is controlled. Further, the first and second motor generators 26 and 28 are controlled by a control device 48. The control device 48 includes two motor generators 26,
And a battery (secondary battery) 50 for supplying power to and receiving power from the power source. In the present embodiment, the battery 50 is a nickel hydride battery. The exchange of power between the battery 50 and the first and second motor generators 26 and 28 is performed by the first and second inverters 5 and 5, respectively.
2 and 54. Two inverters 52, 5
4 is performed by the control CPU 56. This control is performed by controlling the information on the operating state of the engine 10 from the engine ECU 46,
The operation amount of the accelerator pedal 44, the operation amount of the brake pedal 58, the shift range determined by the shift lever 60, the state of charge of the battery, the rotation angle θs of the sun gear of the planetary gear mechanism 16, the rotation angle θc of the planetary carrier, and the ring gear This is performed based on the rotation angle θr and the like. The rotation angles of the three elements of the planetary gear mechanism 16 are detected by a planetary carrier resolver 62, a sun gear resolver 64, and a ring gear resolver 66, respectively. The electric power stored in the battery, that is, the amount of stored power is calculated by the battery ECU 68. The control CPU 56 controls the above-described conditions and the u-phase and v-phase currents Iu1, Iv1, Iu2, Iv2 of the first and second motor generators 26, 28 and the current supplied or supplied from the battery or the other inverter. First and second inverters 5 based on L1, L2, etc.
2,54 transistors Tr1 to Tr6, Tr11 to T
r16 is controlled.

The rotation speed N of the sun gear of the planetary gear mechanism 16
s, the number of revolutions Nc of the planetary carrier and the number of revolutions Nr of the ring gear are given by the gear ratio ρ of the sun gear and the ring gear.

Ns = Nr− (Nr−Nc) (1 + ρ) / ρ (1) That is, three rotation speeds Ns,
When two of Nc and Nr are determined, another rotation speed is determined. Since the rotation speed Nr of the ring gear is determined by the speed of the vehicle, if one of the rotation speed Nc of the planetary carrier, ie, the engine rotation speed, and the rotation speed Ns of the sun gear, ie, the first motor generator rotation speed is determined. ,
The other is determined. Then, the field currents of the first and second motor generators 26 and 28 are controlled in accordance with the rotation speeds at that time, and it is determined whether these motor generators function as generators or motors. When the two motor generators 26 and 28 are consuming power as a whole, power is taken out of the battery 50, and when generating power as a whole, the battery 50 is charged. For example, when the battery ECU 68 detects that the charged amount of the battery 50 is low, one or both of the two motor generators 26 and 28 generate electric power by a part of the torque generated by the engine 10, and the battery 50 Charge the battery. Also, when the amount of stored power in the battery 50 increases, the output of the engine is slightly suppressed,
Making the second motor generator 28 act as an electric motor,
The generated torque is controlled so as to be used for running the vehicle. Further, at the time of braking, one or both of the two motor generators 26 and 28 are operated as a generator, and the generated power is charged in the battery 50.

Since it is difficult to predict when the braking of the automobile will be performed, it is desirable that the battery 50 be in a state that can sufficiently receive the electric power generated by the regenerative braking. On the other hand, if the acceleration desired by the driver cannot be obtained by the output of the engine 10 alone, the battery 5 is used to operate the second motor generator 28 as an electric motor.
0 means that a certain amount of stored power must be secured. Therefore, the amount of power stored in the battery 50 is normally controlled to be about half the battery capacity, that is, the maximum power that can be stored in the battery.

In particular, in the case of a hybrid vehicle in which a battery can be charged by generating electric power by the output of an engine, by properly managing the amount of stored power in the battery, it is possible to sufficiently recover regenerative electric power during braking and achieve energy efficiency. And at the time of acceleration, the acceleration desired by the driver can be achieved. In other words, in the case of the hybrid vehicle as described above, in order to increase energy efficiency and obtain a desired acceleration or the like, it is necessary to accurately detect the state of charge (SOC) of the battery and appropriately control it.

FIG. 2 shows a schematic configuration of the present embodiment. In FIG. 2, the components common to FIG.
The same reference numerals are given. The battery 50 is an assembled battery in which a plurality of cells are connected in series as shown in the drawing.
It is connected to the motor generators 26 and 28 via 54. The two motor generators 26 and 28 are connected to the engine 10 via a transmission mechanism including a planetary gear mechanism. Further, a voltage sensor 70 as voltage detecting means for detecting a terminal voltage of the battery 50 and a current sensor 72 as current detecting means for detecting a current flowing through the battery 50 are provided. Further, temperature sensors 74 are provided at a plurality of locations of the battery 50 as temperature detecting means for detecting the battery temperature. The reason why the temperature sensors 74 are provided at a plurality of locations is as follows.
This is because the temperature of the battery 50 varies depending on the location. Outputs of the voltage sensor 70, the current sensor 72, and the temperature sensor 74 are sent to the battery ECU 68. In the battery ECU 68,
The SOC of the battery is calculated based on the obtained voltage and current,
Further, information on the temperature is sent to the control CPU 56.
Control CPU 56 determines the operating state of motor generators 26 and 28 based on the data sent from battery ECU 68 and various data from engine ECU 46 and controls inverters 52 and 54 accordingly.
As described above, in the hybrid vehicle of the present embodiment, the electric power stored in battery 50 is consumed by motor generators 26 and 28. Also, the motor generator 2
The regenerative power by the motors 6 and 28 and the power from the motor generators 26 and 28 as generators driven by the engine are supplied to the battery 50. Therefore, motor generators 26 and 28 and engine 10 function as charging / discharging means for supplying power to battery 50 or consuming the power of the battery. The control CPU 56 and the engine CPU 46 for controlling the motor generators 26 and 28 via the inverters 52 and 54 function as charge / discharge control means for controlling the charge / discharge means.

In the present embodiment, the SOC of the battery 50
Is based on the output of the current sensor 72, and is estimated by integrating the current flowing through the battery by the battery ECU 68. This is because the estimated value of the SOC becomes
Since the actual value is deviated due to a change in charging efficiency or self-discharge, calibration is also performed in the present embodiment.

When the battery is discharged, as shown in FIG. 6, when the SOC decreases to about 20%, a change in the terminal voltage can be detected by the voltage sensor 70. Therefore, based on the outputs of the voltage sensor 70 and the current sensor 72, the battery E
When the SOC calculated by the CU 68 is below the IV determination region, that is, when the SOC reaches 20% or less, the estimated value of the SOC is rewritten to 20%. When charging, SO
When C increases to around 80%, the voltage sensor 70
Thus, a change in terminal voltage can be detected. Therefore, when the calculated value of the SOC becomes 80% or more, the estimated value is rewritten to 80%. In this way, the estimated value of the SOC is calibrated. Therefore, in this calibration control, the battery ECU 68 functions as a charged amount detection unit. The battery ECU 68 also defines an IV determination region in which such calibration control is performed, and constitutes a region defining unit.

A feature of the present invention is that the battery ECU
If the calculated value of SOC by 68 reaches the above-described IV determination region and the estimated SOC value is calibrated once, the calibration is not performed again unless the estimated SOC value leaves the IV determination region.

FIGS. 3 and 4 show the flow of the calibration operation of the battery charge detection device according to the present invention. FIG.
FIG. 4 shows an operation when the calculated value of OC reaches the lower limit side (20% or less) of the IV determination region.
Each operation when the upper limit (80% or more) of the determination area is reached is shown.

In FIG. 3, when the IV lower limit determination process is started, the SOC value calculated by battery ECU 68 becomes IV
It is determined whether the lower limit (20%) of the determination area has been reached (S
10). Here, until it is determined that the lower limit has been reached, the battery ECU 68 executes an SOC estimation calculation by current integration (S12).

On the other hand, if it is determined in S10 that the lower limit has been reached, a calibration operation for correcting the estimated value of SOC to 20% is executed (S14).

Once the estimated value of the SOC is corrected once, the battery ECU 68 again executes the SOC estimation calculation by current integration (S16).

Next, the battery 50 is charged by a predetermined amount after the lower limit is determined in S10, and it is confirmed whether the estimated SOC value in S16 has left the IV determination region, that is, has exceeded 20% (S18). This confirmation is also battery EC
This is executed in U68. Therefore, the battery ECU 68 also serves as a confirmation unit. Here, the SOC estimation calculation is continued until the vehicle leaves the IV determination region (S16).

On the other hand, when the estimated SOC value exceeds 20% and leaves the IV determination region, the IV lower limit determination process is repeated from the beginning.

In FIG. 4, basically the same operation as that in the flow of FIG. 3 is performed. In FIG. 4, first, when the IV upper limit determination process is started, it is determined whether the calculated value of the SOC has reached the upper limit (80%) of the IV determination region (S2).
0). Here, until it is determined that the upper limit has been reached, the SOC estimation calculation based on the current integration is executed in the battery ECU 68 (S22).

On the other hand, if it is determined in S20 that the upper limit has been reached, a calibration operation for correcting the estimated value of SOC to 80% is executed (S24).

After the estimated value of the SOC is corrected once, the battery ECU 68 again executes the calculation of estimating the SOC by current integration (S26).

Next, after the lower limit is determined in S20, the battery 50 is discharged by a predetermined amount, and the battery ECU 68 determines whether or not the estimated value of SOC in S26 has fallen out of the IV determination region, ie, has fallen below 80% ( S2
8). Here, the SOC estimation calculation is continued until the vehicle leaves the IV determination region (S26).

On the other hand, when the estimated SOC falls below 80% and leaves the IV determination region, the IV upper limit determination process is repeated from the beginning.

FIG. 5 shows a change over time of the SOC when the IV upper limit determination process shown in FIG. 4 is executed. In FIG. 5, when the battery 50 is charged and the SOC increases and reaches the upper limit of the IV determination region, the estimated value of the SOC is corrected to 80%. Thereafter, the IV upper limit determination process is prohibited until the battery 50 is discharged by a predetermined amount. This prohibition is also performed by the battery ECU 68.

Therefore, during this time, S
Only the OC estimation operation is performed. When it is confirmed that the battery ECU 68 has discharged a predetermined amount, the IV upper limit determination process is permitted again.

Since the battery 50 is provided with the temperature sensor 74, the SOC can be estimated from a change in the battery temperature. That is, the SOC of the battery 50 is 10
At 0%, the value of dT / dt sharply increases. Therefore, if the value of dT / dt is calculated by the battery ECU 68 from the temperature detection result of the temperature sensor 74 input to the battery ECU 68, it is possible to detect that the SOC has reached 100%. Can be corrected.

As described above, according to the present invention, the S
OC can be accurately detected. In the present embodiment, a battery mounted on a hybrid vehicle has been described as an example, but the present invention is applicable to a battery for any purpose. Further, the present invention is not limited to the nickel-metal hydride battery of the present embodiment, and can be applied to a lithium ion battery, a nickel cadmium battery, a lead battery, and the like.

[0038]

As described above, according to the present invention,
After once correcting the estimated value of the SOC at the upper limit or the lower limit of the IV determination region, the correction is not performed again until a sufficient amount of charging or discharging to leave the IV determination region is performed.
It is possible to prevent an error in the estimated SOC value from occurring.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a drive system of a hybrid vehicle.

FIG. 2 is a diagram showing a schematic configuration of an embodiment of a battery charge detection device according to the present invention.

FIG. 3 is a flowchart of an operation of an IV lower limit determination process of the embodiment shown in FIG. 2;

FIG. 4 is a flowchart showing an operation of an IV upper limit determination process of the embodiment shown in FIG. 2;

FIG. 5 is a diagram showing an SOC in IV upper limit determination processing shown in FIG. 4;
It is a figure which shows a temporal change.

FIG. 6 is a diagram showing characteristics of a terminal voltage with respect to a charge amount of a nickel-metal hydride battery.

[Explanation of symbols]

10 engine, 26 first motor generator, 28
2nd motor generator, 46 engine ECU, 5
0 battery, 52 first inverter, 54 second inverter, 56 control CPU, 68 battery ECU, 70 voltage sensor, 72 current sensor, 74 temperature sensor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02J 7/00 H02J 7/00 PM

Claims (4)

[Claims] 1. A storage amount detecting means for detecting a storage amount of a secondary battery using a battery characteristic detectable from the outside, and an area defining a current-voltage region in which the detection by the storage amount detecting means is executed. And a battery storage amount detection device comprising: a battery storage amount detection device, wherein when the storage amount detection unit performs detection, the battery storage amount detection device is sufficient to escape a current-voltage region defined by the region specification unit. And a prohibition unit for prohibiting the detection operation by the storage amount detection unit until it is confirmed by the confirmation unit. Quantity detection device. 2. The battery charge detection device according to claim 1, wherein a battery characteristic used by said charge detection means is a current-voltage characteristic. 3. The battery storage amount detection device according to claim 1, wherein the battery characteristics used by the storage amount detection means are dT / dt characteristics (T is the battery temperature and t is time). Battery charge detection device. 4. The battery storage amount detection device according to claim 1, wherein the confirmation means confirms a predetermined amount of charge or discharge by current integration.