JP2003018756A - Output-deterioration calculation device for secondary battery and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve calculation accuracy in an output-deterioration calculation for a secondary battery. SOLUTION: An output-deterioration calculation device for the secondary battery calculates internal resistance Ri0 and Rc1 corresponding to the respective voltages, by detecting an open-circuit voltage V0 and a voltage Vi, when, with which, charging the secondary battery 15 at a constant power. The output deterioration of the secondary battery 15 is calculated by calculating the ratio between the internal resistance Ri0 of the secondary battery 15 at the initial state and the internal resistance Rc1 at the deterioration calculation. With such an arrangement, the calculation accuracy of the output-deterioration calculation for the secondary battery 15 can be improved, unaffected by an error at the current detection, a calculation error at the heavy load, an error at the calculation for a straight line of regression, and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery output deterioration calculating apparatus and an output deterioration calculating method capable of charging and discharging.

[0002]

2. Description of the Related Art Conventionally, there is a method described in Japanese Patent Application Laid-Open No. 2000-261901 as an output deterioration calculation method for a secondary battery mounted on an electric vehicle including a hybrid electric vehicle. In this conventional method, when the motor is driven by using the electric power stored in the secondary battery, that is, the current and the voltage at the time of discharging the secondary battery are detected, and the voltage value and the current value are sampled at a plurality of points. A regression line showing the discharge characteristics of the battery is obtained. The deterioration coefficient of the secondary battery is calculated by calculating the internal resistance of the secondary battery at the time of battery deterioration calculation and calculating the ratio with the internal resistance in the initial state from the obtained regression line.

[0003]

However, in the conventional secondary battery deterioration calculation method, the error due to the current sensor at the time of detecting the current and the error due to the voltage sensor at the time of detecting the voltage are superposed. May be detected as a sampling point. In this case, since the internal resistance calculated from the regression line has a value different from the actual internal resistance, there is a problem that an accurate deterioration coefficient cannot be obtained.

An object of the present invention is to provide a secondary battery output deterioration calculation device and an output deterioration calculation method which can accurately perform a secondary battery deterioration calculation.

[0005]

FIG. 1 showing an embodiment.
The present invention will be described with reference to FIG. (1) The present invention detects only the voltage of the secondary battery 15 in the secondary battery output deterioration calculation method for calculating the battery output deterioration from the output ratio of the battery output at the time of deterioration of the secondary battery 15 and the initial battery output. It is characterized in that the output ratio is calculated. (2) The invention according to claim 2 is an output deterioration calculation device for a secondary battery, which calculates a battery output from an output ratio between a battery output when the secondary battery 15 is deteriorated and an initial battery output, and an open circuit voltage of the secondary battery 15. And the output deterioration is calculated based on the voltage when the secondary battery 15 is charged with constant power. (3) The invention of claim 3 is the output deterioration calculating device for a secondary battery according to claim 2, wherein the calculation of the output deterioration is performed by the secondary battery 15
Is performed based on the internal resistance of the secondary battery 15 calculated based on the open circuit voltage and the voltage when the secondary battery 15 is charged with constant power. (4) In the secondary battery output deterioration computing device according to claim 2 or 3, the secondary battery 15 is the secondary battery 15 that supplies electric power to an electric motor mounted in a hybrid electric vehicle. .

In the section of means for solving the above problems, the present invention is associated with FIG. 1 of the embodiment for the sake of easy understanding, but the present invention is limited to the embodiment. Not a thing.

[0007]

The present invention has the following effects. (1) According to the invention of claim 1, since the output deterioration calculation is performed by detecting only the voltage of the secondary battery, it is not necessary to provide a current sensor. Therefore, since there is no influence of a detection error when the current is detected by the current sensor, the accuracy of the deterioration calculation can be improved as compared with the method of detecting the current and performing the output deterioration calculation. (2) According to the second aspect of the invention, the output deterioration calculation is performed based on the open circuit voltage of the secondary battery and the voltage when the secondary battery is charged with constant power. The calculation accuracy can be improved as compared with the method of obtaining the regression line by sampling the current value. Further, it is not necessary to consider the influence of the calculation error when the load is high.

[0008]

FIG. 1 is a diagram showing the configuration of an embodiment in which an output deterioration computing device for a secondary battery according to the present invention is applied to a hybrid electric vehicle. In the figure, a thick solid line indicates a mechanical force transmission path, and a thick broken line indicates a power line. Also, 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 drive 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. Also, 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.

When the clutch 3 is engaged, the engine 2 and the motor 4
Both, or only engine 2 becomes the propulsion source of 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 gear 7. An oil pump (not shown) of the hydraulic device 9 is driven by the motor 10 and supplies pressure oil to the continuously variable transmission 5.

The motors 1, 4, 10 are AC machines such as a three-phase synchronous motor or a three-phase induction motor. The motor 1 is mainly used for engine starting and power generation, and the motor 4 is mainly used for propulsion and braking of the vehicle. The motor 10 is for driving the oil pump of the hydraulic device 9. The motors 1, 4 and 10 are not limited to AC machines, but 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 engine starting and power generation.

The clutch 3 is a powder clutch and can adjust the transmission torque. The clutch 3 may be a dry single plate clutch or a wet multi-plate clutch. The continuously variable transmission 5 is a continuously variable transmission such as a belt type or toroidal type, and can continuously adjust the gear ratio.

Inverters 11, 12, 13 drive and control motors 1, 4, 10 respectively. In addition, the motor 1,
When a DC motor is used for 4, 10, a DC / DC converter is used instead of the inverter. Inverter 1
1 to 13 are connected to a main battery 15 via a common DC link 14, and convert DC charging power of the main battery 15 into AC power and supply it to the motors 1, 4, 10. Also, the AC power generated by the motors 1 and 4 is converted into DC power to charge the main battery 15. Since the inverters 11 to 13 are connected to each other via the DC link 14, the electric power generated by the motor in the regenerative operation can be directly supplied to the motor in the power running operation without the main battery 15. it can. As the main battery 15, various batteries such as lithium-ion batteries, nickel-hydrogen batteries, lead batteries, and so-called power capacitors such as electric double layer capacitors can be used.

The current sensor 18 detects the current when the main battery 15 is charged and discharged, and the voltage sensor 19 detects the terminal voltage of the main battery 15. The current sensor 18 may not be provided, as described later. Vehicle speed sensor 2
0 detects the vehicle speed of the vehicle. The detection value of each sensor is input to the controller 16. Controller 1
Reference numeral 6 includes a microcomputer and its peripheral parts, various actuators, etc., and is used for the rotational speed and output torque of the engine 2, the transmission torque of the clutch 3, the rotational speed and output torque of the motors 1, 4, 10 and the continuously variable transmission 5. Controls the gear ratio, etc.

2 and 3 are flow charts showing the control procedure of an embodiment of the output deterioration calculating apparatus for a secondary battery according to the present invention. The control starting from step S1 is performed by the controller 16 when the vehicle is started. Hereinafter, description will be made in order from step S1. In step S1, it is determined whether or not an ignition switch (IGN-SW) not shown is turned on. If it is determined that it is turned on, the process proceeds to step S2. If it is determined that it is not turned on, the process waits in step S1 until it is turned on.

In step S2, the vehicle speed sensor 20 detects the vehicle speed. The detected vehicle speed is input to the controller 16. In the next step S3, it is determined whether or not the vehicle is stopped. This determination is made based on the vehicle speed detected in step S2. When the vehicle is not stopped, that is, while the vehicle is traveling, there is a high possibility that the battery 15 is being charged and discharged, and the open circuit voltage of the battery 15 cannot be detected. Therefore, when it is determined that the vehicle is not stopped (running), this control is ended, and when it is determined that the vehicle is stopped, the process proceeds to step S4.

In step S4, the motor 1 for generating electric power
It is determined whether or not (hereinafter, referred to as the generator motor 1) is operating. The controller 16 sends a control command signal for the generator motor 1 to the inverter 11 to control the generator motor 1. That is, based on the control command signal of the generator motor 1 transmitted by the controller 16, the generator motor 1
Determine whether or not is operating. If the generator motor 1 is operating, the battery 15 is being charged, and therefore it is not necessary to perform the battery deterioration calculation until the power generation operation of the generator motor 1 is stopped. Even if the operation of the generator motor 1 is stopped and the battery deterioration calculation is performed, in order to detect the voltage of the battery 15, it is necessary to wait until the voltage stabilizes. In consideration of these matters, when it is determined that the generator motor 1 is operating, this control is ended without performing battery deterioration calculation. If it is determined that the generator motor 1 is not operating, the process proceeds to step S5.

In step S5, the voltage sensor 19 detects the open circuit voltage V0 of the battery 15. Open voltage V
When 0 is detected, the process proceeds to step S6. In step S6, based on the open circuit voltage V0 detected in step S5,
The internal resistance Ri of the battery 15 is detected. This method
This will be described using the voltage-internal resistance characteristic curve of the secondary battery shown in FIG. In the voltage-internal resistance characteristic curve of the secondary battery shown in FIG. 4, a solid line is a graph showing a state where the battery is new, that is, an initial characteristic of the secondary battery, and a dotted line is a graph when the battery is deteriorated. There is. The internal resistance Ri corresponding to the open circuit voltage V0 detected in step S5 is detected by using the graph showing the initial characteristic represented by the solid line. Internal resistance R
When i is detected, the process proceeds to step S7.

In step S7, temperature correction is performed on the internal resistance Ri detected in step S6. That is, the temperature-corrected internal resistance Ri0 is calculated and stored by the following equation (1) using the temperature coefficient α based on the battery temperature detected by a temperature sensor (not shown). Ri0 = Ri × α / 100 (1) When the internal resistance Ri0 after temperature correction is calculated, step S8
Proceed to. In step S8, the engine is started and the process proceeds to step S9. In step S9, a drive command signal for the generator motor 1 is transmitted to the inverter 11 to drive the generator motor 1. Here, the generator motor 1 is driven so as to maintain the output value (electric power) at P0. The constant power P0 generated by the generator motor 1 is stored in the battery 15.

In step S10, the voltage sensor 19 detects the voltage value V1 of the battery 15 being charged.
The detected voltage value V1 is input to the controller 16. In the next step S11, the internal resistance R is calculated from the voltage value V1 of the battery 15 being charged detected in step S10.
Calculate and store c1.

In FIG. 5, the output value from the generator motor 1 is P0.
Current I and voltage V flowing from the battery 15 when
It is a graph which shows the relationship with. The internal resistance Rc1 during the output deterioration calculation of the secondary battery can be calculated by the following equation (2). Rc1 = V1. (V1-V0) / P0 (2) As can be seen from the above equation (2), the internal resistance Rc1 is as shown in FIG.
In, the inclination of the straight line connecting the point (I, V1) and the point (0, V0) is shown. When the voltage value when the deterioration of the battery progresses is V1 ′, the internal resistance Rc1 ′ when the output deterioration progresses can be calculated by the following equation (3). Rc1 ′ = V1 ′ · (V1′−V0) / P0 (3) Also in this case, the internal resistance Rc1 ′ has the slope of the straight line connecting the point (I ′, V1 ′) and the point (0, V0). Shows. Figure 5
As can be seen from the above, as the deterioration of the battery progresses, the internal resistance increases.

When the internal resistance Rc1 is calculated, step S
Proceed to 12. In step S12, the output deterioration coefficient γ is calculated using the internal resistance Ri0 in the initial state of the battery and the internal resistance Rc1 in the output deterioration calculation. The output deterioration coefficient γ indicating the output deterioration state of the battery can be calculated by the following equation (4). γ = Pc / Pint = Ri0 / Rc1 × 100 (4) where Pint is the dischargeable output in the initial state of the battery and Pc is the dischargeable output when the battery is deteriorated. Formula (4)
As can be seen from the above, as the output deterioration of the secondary battery progresses, the internal resistance Rc1 increases, so that the output deterioration coefficient γ decreases. When the output deterioration coefficient γ is calculated, step S13
Proceed to. In step S13, the output deterioration coefficient γ calculated in step S12 is stored in the memory 21 in the controller 16. This output deterioration coefficient γ is used until the vehicle next stops. When the output deterioration coefficient γ is stored in the memory 21, the process proceeds to step S14. In step S14, the inverter 11 outputs a command signal for stopping the operation of the generator motor 1.
Send to. When the operation of the generator motor 11 is stopped, this control is ended.

According to the output deterioration calculation device for a secondary battery of the present invention, the battery deterioration calculation control is started when the vehicle is started (step S1). The open circuit voltage V0 of the battery 15 in the state where the vehicle is stopped and the generator motor 1 is not operating is detected (steps S2 to S).
5). After calculating the internal resistance Ri of the battery 15 based on the open circuit voltage V0, the internal resistance Ri0 after temperature correction is calculated (steps S6 to S7). Then, the engine is operated to detect the voltage value Vi when the battery 15 is being charged with the constant power P0 (steps S8 to S10). Using the detected voltage value Vi, the internal resistance R
After calculating c1, the output deterioration coefficient γ is calculated using the internal resistance Ri0 and the internal resistance Rc1 (steps S11 to S12). The calculated output deterioration coefficient γ is stored in the memory 21.
Then, when the operation of the generator motor 1 is stopped, the present control ends.

In the conventional output deterioration calculation control of the secondary battery,
There was a calculation error when the vehicle was running under high load, such as when it accelerated suddenly or climbed a steep slope. This is because the discharge current from the battery 15 becomes large during traveling under a high load, and thus an error occurs in the regression line obtained by using the sampling points of a plurality of current values and voltage values. Therefore, when the battery output deterioration calculation is performed under a high load, a calculation result different from the actual battery deterioration state is calculated. But,
In the output deterioration calculation control of the secondary battery according to the present invention,
Since the internal resistance is calculated from the current-voltage characteristic curve when the output from the generator motor 1 has a constant value (P0) to calculate the deterioration of the battery, it is not affected by the high load running of the vehicle.

Further, unlike the conventional deterioration calculation control, since the regression calculation is not performed, the calculation error due to the regression calculation does not occur. That is, when performing regression calculation,
If a plurality of points for sampling the voltage value and the current value vary, the regression line obtained by the regression calculation will be different from the straight line showing the actual current-voltage characteristic. Since the regression calculation is not performed in the output deterioration calculation control of the secondary battery according to the present invention, the calculation accuracy is higher than that of the conventional deterioration calculation control.

Further, since the internal resistance of the battery is calculated using the open circuit voltage V0, the constant output value P0 from the generator motor 1, and the voltage value V1 at that time, the current value is detected when the internal resistance of the battery is obtained. No need. Therefore, there is no need to provide a current sensor, and even if a current sensor is provided, there is no need to increase the current detection accuracy. Thereby, the cost of the current sensor can be reduced. Further, in the method of detecting the current and performing the deterioration calculation, a detection error at the time of detecting the current may occur, but in the output deterioration calculation control of the secondary battery according to the present invention, such a detection error does not occur. Therefore, the calculation accuracy can be improved.

The present invention is not limited to the above embodiment. In the above-described embodiment, an example in which the output deterioration calculation device for a secondary battery is applied to a hybrid electric vehicle has been described, but it can also be applied to an electric vehicle. That is, when the battery 15 (secondary battery) is charged by the charger installed outside the vehicle, the battery deterioration calculation can be similarly performed. The vehicle is not limited to the vehicle as long as the battery can be charged and discharged.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a hybrid electric vehicle to which a secondary battery output deterioration calculating device according to the present invention is applied.

FIG. 2 is a flowchart showing a control procedure of an embodiment of a secondary battery output deterioration computing device according to the present invention.

FIG. 3 is a flowchart showing a control procedure following FIG.

FIG. 4 is a graph showing the voltage-internal resistance characteristics in the initial state and deterioration of the secondary battery.

FIG. 5 is a graph showing current-voltage characteristics of a secondary battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Generator motor, 2 ... Engine, 3 ... Clutch, 4 ... Motor, 5 ... Continuous transmission, 6 ... Reduction gear device, 7 ... Differential device,
8 ... Drive wheel, 9 ... Hydraulic device, 10 ... Motor, 11 ... Inverter, 12 ... Inverter, 13 ... Inverter, 14 ...
DC link, 15 ... Battery, 16 ... Controller, 1
7 ... Compressor, 18 ... Current sensor, 19 ... Voltage sensor, 20 ... Vehicle speed sensor, 21 ... Memory

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02J 7/10 H02J 7/10 FF term (reference) 2G016 CA03 CB02 CB03 CD00 5G003 AA07 CA11 CA16 EA08 FA06 GC05 5H030 AA03 AA04 AS20 FF43 FF44 5H115 PA08 PA14 PG04 PI16 PO02 PU01 PU21 PV09 QN03 SE06 TI05 TI10 TR19 TU04

Claims (4)

[Claims] 1. A secondary battery output deterioration calculation method for calculating battery output deterioration from an output ratio of a battery output at the time of deterioration of a secondary battery and an initial battery output, wherein only the voltage of the secondary battery is detected, and A method for calculating output deterioration of a secondary battery, which comprises calculating an output ratio. 2. An output deterioration calculation device for a secondary battery, which calculates battery output deterioration from an output ratio between a battery output when the secondary battery is deteriorated and an initial battery output, wherein an open circuit voltage of the secondary battery and a constant power are used. The output deterioration calculation device for a secondary battery, wherein the output ratio is calculated based on a voltage when the secondary battery is charged. 3. The secondary battery output deterioration calculating device according to claim 2, wherein the output ratio is calculated by charging the secondary battery with an open circuit voltage of the secondary battery and a constant power. An output deterioration calculation device for a secondary battery, which is performed based on an internal resistance of the secondary battery calculated based on a voltage. 4. The output deterioration calculation device for a secondary battery according to claim 2, wherein the secondary battery is a secondary battery that supplies electric power to an electric motor mounted in a hybrid electric vehicle. Characteristic secondary battery output deterioration calculating device.