JP2000030753A - Control device of battery for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a vehicle to run some distance even after a battery mounted on a hybrid vehicle deteriorated by a replacing level. SOLUTION: A deteriorated state of a battery for a hybrid vehicle is detected, a target SOC of the battery is set, and charge/discharge of the battery is controlled so that the SOC of the battery becomes the target SOC. Some distance of running is possible even after the deterioration state of the battery for the hybrid vehicle reached a level requiring replacement, and a driver can afford the time until replacement and have an easy mind.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a battery used in a hybrid vehicle.

[0002]

2. Description of the Related Art Generally, a battery has a characteristic that the internal resistance increases and the input / output decreases with the progress of deterioration. Therefore, when the predetermined input / output can no longer be obtained, it is determined that the life of the battery has expired, and replacement of the battery is prompted.

[0003] By the way, since a large-capacity battery is mounted on a hybrid vehicle, replacing the battery requires relatively large cost and work. Therefore, even if the mounted battery is deteriorated to the replacement level, it is desirable to allow the vehicle to travel for a certain distance and to allow time before the replacement.

An object of the present invention is to enable a hybrid vehicle to travel a certain distance when the battery mounted on the hybrid vehicle has deteriorated to a replacement level.

[0005]

According to a first aspect of the present invention, there is provided a deterioration detecting means for detecting a deterioration state of a battery for a hybrid vehicle, and a target SO of the battery based on the deterioration state detection value.
The above object is achieved by providing an SOC setting means for setting C, an SOC detection means for detecting the SOC of the battery, and a control means for controlling charging and discharging of the battery so that the SOC detection value becomes the target SOC. . (2) A control device for a battery for a hybrid vehicle according to a second aspect of the present invention includes a temperature detecting unit for detecting a temperature of the battery.
The setting means sets the target SOC based on the deterioration state detection value and the temperature detection value. (3) In the battery control device for a hybrid vehicle according to the third aspect, the deterioration detecting means determines the deterioration state by detecting the internal resistance of the battery. (4) In the control device for a battery for a hybrid vehicle according to a fourth aspect, the control means limits the input power according to the target SOC. (5) In the control device for a hybrid vehicle battery according to claim 5, the battery is a lithium ion battery.

[0006]

(1) According to the first aspect of the present invention, the deterioration state of the battery for a hybrid vehicle is detected and the target S of the battery is detected.
Since the OC is set and the charging and discharging of the battery is controlled so that the SOC of the battery becomes the target SOC, the vehicle must travel a certain distance even if the deterioration state of the battery for the hybrid vehicle reaches a level requiring replacement. The passengers can be given a sense of security because they can have enough time before the replacement. (2) According to the second aspect of the present invention, the target SOC is set based on the battery deterioration state detection value and the temperature detection value, and the charging and discharging of the battery is controlled so that the battery SOC becomes the target SOC. I made it. The output can be increased by raising the target SOC in accordance with the state of deterioration of the battery, but the input must be limited. However, since the output increases as the battery temperature rises, the target SOC need not be increased if the battery temperature is high when the target SOC is increased due to the progress of deterioration.
OC can be set. (3) According to the third aspect of the present invention, the deterioration state is determined by detecting the internal resistance of the battery, so that the deterioration state of the battery can be easily and accurately determined even during operation of the vehicle. it can. (4) According to the fourth aspect of the invention, the input power is limited according to the target SOC. Therefore, when the target SOC is increased due to the deterioration of the battery, the SOC of the battery is accurately adjusted to the target value. Can be controlled. (5) According to the fifth aspect of the present invention, when the present invention is applied to a lithium ion battery having a relatively large slope of input / output characteristics with respect to SOC, the above-described effects become more remarkable.

[0007]

FIG. 1 is a diagram showing the configuration of an embodiment. In the figure, a thick solid line indicates a transmission path of mechanical force, and a thick broken line indicates a power line. A thin solid line indicates a control line, and a double line indicates a hydraulic system. The power train of this vehicle includes a motor 1, an engine 2, a clutch 3, a motor 4, a continuously variable transmission 5, a reduction gear 6, a differential gear 7, and driving wheels 8. The output shaft of the motor 1, the output shaft of the engine 2, and the input shaft of the clutch 3 are connected to each other, and the output shaft of the clutch 3, the output shaft of the motor 4, and the input shaft of the continuously variable transmission 5 are connected to each other. ing.

When the clutch 3 is engaged, the engine 2 and the motor 4 serve as propulsion sources for the vehicle. When the clutch 3 is released, only the motor 4 serves as a propulsion source for the vehicle. The driving force of the engine 2 and / or the motor 4 is transmitted to the drive wheels 8 via the continuously variable transmission 5, the reduction gear 6, and the differential 7. Pressure oil is supplied from the hydraulic device 9 to the continuously variable transmission 5 to clamp and lubricate the belt. An oil pump (not shown) of the hydraulic device 9 is driven by a motor 10.

The motors 1, 4, and 10 are AC machines such as a three-phase synchronous motor or a three-phase induction motor. The motor 1 is mainly used for starting and generating electric power, and the motor 4 is mainly used for propulsion and braking of a vehicle. . The motor 10 is for driving the oil pump of the hydraulic device 9. In addition,
The motors 1, 4, and 10 are not limited to AC machines, and DC motors can be used. Further, when the clutch 3 is engaged, the motor 1 can be used for propulsion and braking of the vehicle, and the motor 4 can be used for starting the engine and generating power.

The clutch 3 is a powder clutch, and the transmission torque can be adjusted because the transmission torque is almost proportional to the exciting current. The continuously variable transmission 5 is a continuously variable transmission of a belt type, a toroidal type, or the like, and can continuously adjust the speed ratio.

The motors 1, 4, and 10 are driven by inverters 11, 12, and 13, respectively. When a DC motor is used for the motors 1, 4, and 10, a DC / DC converter is used instead of the inverter.
The inverters 11 to 13 are connected to a main battery 15 via a common DC link 14, convert DC charging power of the main battery 15 into AC power, supply the AC power to the motors 1, 4, 10, and 4 is converted into DC power and the main battery 1
Charge 5. Since the inverters 11 to 13 are connected to each other via the DC link 14, the power generated by the motor during the regenerative operation can be directly supplied to the motor during the power running operation without passing through the main battery 15. it can.

The main battery 15 is a lithium ion battery. Note that another type of battery such as a nickel-metal hydride battery or a lead battery can be used as the main battery 15.

The controller 16 includes a microcomputer and its peripheral parts, various actuators, etc., and controls the rotation speed and output torque of the engine 2, the transmission torque of the clutch 3, the rotation speed and output torque of the motors 1, 4, and 10. The gear ratio of the transmission 5 and the SOC of the main battery 15 are controlled.

As shown in FIG. 2, the controller 16 includes a vehicle key switch 20, an SOC detecting device 21, a temperature sensor 22, a voltage sensor 23, and a current sensor 24.
Are connected. The SOC detection device 21 detects the SOC (charge state) of the main battery 15, and the temperature sensor 22 detects the temperature of the main battery 15. Also,
The voltage sensor 23 detects a terminal voltage of the main battery 15, and the current sensor 24 detects a charge / discharge current of the main battery 15.

Here, the SOC control of the battery of this embodiment will be described. FIG. 3 shows the S of the lithium ion battery.
This shows input / output characteristics with respect to OC. In the figure, the solid line shows the characteristics when the device is new, and the broken line shows the characteristics when the device is deteriorated. Generally, as the SOC increases, the output of the battery increases and the input decreases. If this property is used, when the battery is deteriorated and the output is reduced, the output can be compensated to some extent by increasing the SOC by increasing the SOC.

On the other hand, in a hybrid vehicle, charging and discharging are controlled so that the SOC of the main battery always falls within a target value or a target range. Specifically, the target value of the SOC is set to 50% or the target range is set to 30 to 70%, and the SOC of the main battery is detected during traveling so that the detected value becomes close to the target value, or The charge and discharge of the main battery is controlled to fall within the range.

Therefore, in this embodiment, the deterioration state of the main battery 15 is detected, a warning is issued when the deterioration state reaches a level requiring replacement, and the SOC target value or target range is set in accordance with the progress of deterioration. Raise the lower limit,
Compensates for output reduction due to deterioration. As a result, even if the main battery deteriorates to the replacement level, a certain traveling distance is secured, and the battery can be replaced with sufficient time.

However, increasing the target value of SOC or the lower limit of the target range, as is apparent from FIG. 3, decreases the input margin of the battery. It needs to be restricted. In a hybrid vehicle, the input to the main battery is usually performed in the regenerative braking mode, so that the regenerative reception power is limited.

The battery also has the characteristic that the output increases as the temperature increases. Therefore, in this embodiment, the target SOC is set according to the state of deterioration of the battery and the temperature of the battery, and the target SOC is set higher as the deterioration proceeds, and the target SOC is set lower as the temperature of the battery is higher.

Next, a method for detecting the state of deterioration of the battery will be described. As described above, since the internal resistance of the battery increases as it deteriorates, the internal resistance can be detected to determine the state of deterioration. The internal resistance of the battery can be determined by dividing the difference between the open-circuit voltage and the terminal voltage during charge / discharge by the charge / discharge current. For more accurate determination, the terminal voltage and current at the time of discharge are sampled, the voltage-current characteristics are determined by linearly regressing the sampled data, and the internal resistance can be known from the slope. Further, the output capacity with respect to the SOC can be obtained by calculation, and the deterioration state can be detected by comparing with the output capacity at the time of new product.

FIG. 4 is a flowchart showing the SOC control according to one embodiment. The operation of the embodiment will be described with reference to this flowchart. The controller 16
When the key switch 20 of the vehicle is set to the ON position, the control program is repeatedly executed. In step 1, the deterioration state of the main battery 15 is detected by the method described above, and the temperature of the main battery 15 is detected by the temperature sensor 22. When a temperature sensor is not installed in the main battery 15, the detection value of the outside air temperature sensor for air conditioning may be substituted for the battery temperature. In the following step 2, a warning is issued if the state of deterioration of the main battery 15 has reached a level requiring replacement.
In step 3, a target SOC is set according to the deterioration state of the main battery 15 and the temperature Tb.

FIGS. 5 and 6 show the S of the main battery.
The output characteristics when the product is new (solid line) and the output characteristics when deteriorated (broken line) with respect to OC are shown. As shown in FIG. 5, when controlling the SOC of the main battery 15 to the target value of 50%,
When new, the output of P1 is obtained, but when it deteriorates, only the output of P3 is obtained. Therefore, at the time of deterioration, the target SOC
Is raised from 50% to 75%, the output P1 when new
If not, an output of P2 higher than P3 is obtained.

On the other hand, as shown in FIG. 6, when the SOC of the main battery 15 is controlled to the target range of 30 to 70%, at least the output of P13 is obtained when the battery is new, but the output of P15 is obtained in the worst case when it deteriorates. You can only get it. Therefore, the lower limit value of the target SOC range is set to 3
When it is raised from 0% to 50%, the minimum output P1 when new
A minimum output of P14 which is close to, if not equal to 3, is obtained.

After setting the target SOC in accordance with the state of deterioration and temperature of the main battery 15, the SOC of the main battery 15 is detected by the SOC detection device 21 in step 4, and in step 5, the SOC detection value is set to the target value. The charge / discharge of the main battery 15 is controlled in such a manner. At this time, if the target SOC is set higher than when the product is new,
Target regenerative power to main battery 15
Limit according to C.

In the configuration of the above embodiment, the voltage sensor 23, the current sensor 24, and the controller 16 serve as deterioration detecting means, the controller 16 serves as SOC setting means and control means, and the SOC detecting device 21 serves as SOC.
The temperature sensor 22 constitutes a temperature detecting means, and the temperature sensor 22 constitutes a temperature detecting means.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a diagram illustrating a configuration of an embodiment following FIG. 1;

FIG. 3 is a diagram showing input / output characteristics of a lithium ion battery with respect to SOC.

FIG. 4 is a flowchart illustrating SOC control according to one embodiment.

FIG. 5 is a diagram illustrating an improvement result of output characteristics at the time of deterioration according to an embodiment.

FIG. 6 is a diagram illustrating an improvement result of output characteristics at the time of deterioration according to an embodiment.

[Explanation of symbols]

 1, 4, 10 Motor 2 Engine 3 Clutch 5 Continuously variable transmission 6 Reduction gear 7 Differential device 11-13 Inverter 14 DC link 15 Main battery 16 Controller 20 Key switch 21 SOC detection device 22 Temperature sensor 23 Voltage sensor 24 Current sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H02J 7/00 H02J 7/00 X (72) Inventor Hideaki Horie 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor (72) Inventor Takeshi Iwai, Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Takaaki Abe 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa, Nissan Motor Co., Ltd. (72) Inventor Mikio Kawai Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa

Claims (5)

[Claims] 1. A deterioration detection means for detecting a deterioration state of a battery for a hybrid vehicle, an SOC setting means for setting a target SOC of the battery based on the deterioration state detection value, and an SOC detection for detecting an SOC of the battery And control means for controlling charging and discharging of the battery so that the SOC detection value becomes the target SOC. 2. The control device for a battery for a hybrid vehicle according to claim 1, further comprising: a temperature detecting unit for detecting a temperature of the battery, wherein the SOC setting unit is configured to detect the deterioration state detection value and the temperature detection value. A control device for a battery for a hybrid vehicle, wherein a target SOC is set based on the target SOC. 3. The hybrid vehicle battery control device according to claim 1, wherein said deterioration detecting means detects an internal resistance of said battery to determine a deterioration state. Control device for vehicle battery. 4. The hybrid vehicle battery control device according to claim 1, wherein said control means limits the input power in accordance with said target SOC. Battery control device. 5. The control device for a hybrid vehicle battery according to claim 1, wherein the battery is a lithium ion battery.