JP3880924B2 - Power supply control device and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for controlling a power source which prevents the life of a storage battery from being shortened at traveling, etc. in a traffic congestion city area by reducing an exhaust gas by improving the fuel cost of a vehicle by recovering a regenerated energy to the storage battery. <P>SOLUTION: The apparatus for controlling the power source includes an engine, a generator driven by the engine, the storage battery charged by the generator, and a storage battery charging/discharging controller for controlling the charging/discharging of the storage battery so that the charged state of the storage battery may fall within a predetermined range. The apparatus is placed in the vehicle. The storage battery charging/discharging controller detects the frequency of the occurrence of the state that the engine or the vehicle is stopped and sets the upper limit value of the predetermined range if the frequency is a predetermined threshold value or more to the value lower than the upper limit value if the frequency is less than the predetermined value. <P>COPYRIGHT: (C)2004,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply control device and a control method therefor.
[0002]
[Prior art]
In recent years, due to the increasing interest in air pollution, the engine is automatically stopped (stops idling) in a short time or immediately when the vehicle is parked to stop unnecessary exhaust emissions. A vehicle having an idle stop function (hereinafter referred to as an “idle stop vehicle”) has been developed. The idle stop vehicle has a much higher frequency of restarting the engine from the stopped state (frequency of supplying power from the storage battery to the cell motor for starting the engine) than a vehicle having no idle stop function. Also, during idle stop, power is supplied from the storage battery to the vehicle control system, lights, audio, and the like. As such a storage battery for an idle stop vehicle, an inexpensive liquid lead storage battery that has been conventionally used has been studied.
[0003]
In a liquid lead-acid battery, SOC (state of charge; meaning discharge capacity) is greatly reduced due to discharge due to idle stop, and if the state of insufficient charge continues, stratification of the electrolyte occurs and sulfation occurs. Because it occurs, the life is shortened rapidly. For this reason, when an idle stop function is mounted on a conventional vehicle using an inexpensive liquid lead-acid battery, power supply control for preventing battery deterioration is important. In a conventional vehicle that does not perform idle stop, the charging voltage is set high so as to keep the SOC close to 100% at all times, and control is performed so as not to cause insufficient charging.
[0004]
Japanese Patent No. 3211699 discloses a power output apparatus of Conventional Example 1. The power output apparatus of Conventional Example 1 sets the target value of the SOC of the battery in accordance with the traveling condition of the vehicle and the predicted traveling condition, and controls the engine and the generator. The driving condition is quantified using at least one of the vehicle speed, acceleration, altitude, and map information stored in the navigation system.
[0005]
Japanese Patent Laid-Open No. 11-008909 discloses a power generation control device for a hybrid electric vehicle according to Conventional Example 2. The power generation control device for the hybrid electric vehicle of Conventional Example 2 predicts the integrated regenerative energy obtained until the completion of the downhill when the vehicle climbs the hill. Then, the target SOC value of the battery is lowered by the amount of charge predicted when the battery is charged with the regenerative energy. Therefore, the regenerative energy at the time of downhill can be accepted in the form of battery charging without waste.
[0006]
Japanese Patent Laid-Open No. 2001-268708 discloses a control device for a hybrid vehicle of Conventional Example 3. The control device for the hybrid vehicle of Conventional Example 3 changes the target value of the charge level according to the degree of deterioration of the battery. Furthermore, the target value of the charge level is set lower during steady operation than during deceleration operation.
[0007]
[Patent Document 1]
Japanese Patent No. 3211699 [Patent Document 2]
JP-A-11-008909 [Patent Document 3]
Japanese Patent Laid-Open No. 2001-268708
[Problems to be solved by the invention]
The idle stop vehicle discharges the storage battery at the time of engine start and start after the stop and after the stop, so the SOC of the storage battery is reduced. When the SOC of the storage battery decreases, the storage battery is charged if the idle stop vehicle continues to run for a while, and the SOC increases again. However, an idle stop vehicle that travels in a congested urban area may repeatedly stop after traveling a short distance. In this case, the storage battery is repeatedly discharged while being hardly charged. In such a case, the SOC of the storage battery may be less than the minimum necessary for starting the idle stop vehicle, and the idle stop vehicle may not move. For this reason, a control has been proposed in which a lower limit value of the SOC is set and the idling stop is canceled when the lower limit value is reached. However, since the number of idling stops is reduced, the effect of improving the fuel consumption is reduced. Further, since the SOC is used in a low state, sulfation due to stratification occurs particularly in a liquid lead-acid battery, and there is a possibility that the life may be shortened. On the other hand, when traveling on a highway or with a small number of traffic lights, the frequency of idling stops is low, so the storage battery is less discharged and the charging time is longer. Therefore, when charging is performed at a constant charging voltage as in conventional charging control and the SOC is controlled to be close to 100%, overcharging occurs, and an effect of improving fuel efficiency cannot be expected. In addition, since the SOC is controlled to be close to 100%, regenerative charging cannot be accepted.
[0009]
The power output devices and the like of Conventional Examples 1 to 3 control charging / discharging of the storage battery according to the driving condition of the automobile and the state of the battery. However, the power supply devices of Conventional Examples 1 to 3 do not solve the above problem that the storage battery may have a short life in traveling in a congested urban area.
[0010]
The present invention solves the above-mentioned conventional problems, recovers regenerative energy in a storage battery even when traveling on a highway or with a small number of traffic lights, reducing idling stop frequency, improving vehicle fuel efficiency, reducing exhaust gas, and Provided are a power supply control device and a control method thereof for preventing a storage battery from having a short life during traveling in a congested urban area.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following configuration. The invention according to claim 1 is an engine, a generator driven by the engine, a storage battery charged by the generator, and charging of the storage battery so that a state of charge of the storage battery is within a predetermined range. A storage battery charge / discharge control unit that controls discharge, and is mounted in a vehicle, wherein the storage battery charge / discharge control unit detects a frequency at which the engine or the vehicle is stopped, and the frequency is The power supply control device according to claim 1, wherein an upper limit value of the predetermined range when the frequency is equal to or higher than a predetermined threshold value is set higher than the upper limit value when the frequency is lower than the predetermined threshold value.
[0012]
According to a second aspect of the present invention, the generator can operate as an electric motor that assists the engine, and the storage battery charge / discharge control unit is configured to operate the storage battery at least when the engine changes from a stopped state to an operating state. And discharging and driving the generator as an electric motor, and controlling the charge and discharge of the storage battery so that the storage battery is charged by the generator after the engine continues operating. 1. The power supply control device according to 1.
[0013]
According to a third aspect of the present invention, the storage battery charge / discharge control unit sets the upper limit value when the frequency is equal to or higher than the predetermined threshold value to a maximum rating of the storage battery, and the frequency is less than the predetermined threshold value. The storage battery sets the upper limit value to a value at which the storage battery can charge regenerative energy from the generator when the value is less than another threshold value that is lower than the predetermined threshold value. A power supply control device according to claim 1 or claim 2.
[0014]
The invention according to claim 4 is the power supply control device according to claim 1 or 2, wherein the storage battery is a lead storage battery.
[0015]
The invention according to claim 5 is a control method for a power supply control device mounted on a vehicle, comprising an engine, a generator driven by the engine, and a storage battery charged by the generator, A control step for controlling charging / discharging of the storage battery so that a charging state of the storage battery is within a predetermined range; and a detection step for detecting a frequency at which the engine or the vehicle is stopped. The upper limit value of the predetermined range of the control step when the frequency is equal to or higher than a predetermined threshold is set higher than the upper limit value when the frequency is less than the predetermined threshold. This is a method for controlling the apparatus.
[0016]
According to a sixth aspect of the present invention, the generator can operate as an electric motor that assists the engine, and at least when the engine changes from a stopped state to an operating state, the storage battery is discharged to cause the generator to operate. 6. The power supply control device according to claim 5, wherein the storage battery is charged and discharged so that the storage battery is charged by the generator after being driven as an electric motor and the engine continues operating. It is a control method.
[0017]
The invention according to claim 7 sets the upper limit value when the frequency is equal to or higher than the predetermined threshold value to a maximum rating of the storage battery, and the frequency is lower than the predetermined threshold value or the predetermined threshold value. The said upper limit in case it is less than the other threshold value which is a lower value sets the said storage battery to the value which can charge the regenerative energy from the said generator, The Claim 5 or Claim 6 characterized by the above-mentioned. It is a control method of a power supply control device.
[0018]
The inventor of the present invention discharges the battery when the battery mounted on the idle stop vehicle is discharged at the time of engine start or start, and thus repeatedly stops running after a short distance especially in a congested urban area. It has been found that the quantity is proportional to the number of engine or car stops. If the frequency at which the engine or the vehicle is stopped is high, the charge amount of the storage battery may not catch up with the discharge amount. In such a case, it can prevent that the lifetime of a storage battery becomes short by controlling so that SOC of a storage battery is made high. On the other hand, when a vehicle travels on a highway, the frequency of occurrence of a state where the engine or the vehicle is stopped is low. In such a case, the regenerative energy can be reliably recovered in the storage battery by controlling the storage battery to have a low SOC.
In an idle stop vehicle using a lead storage battery, the life of the lead storage battery is shortened if the discharge is repeated while the storage battery is hardly charged.
“Frequency of occurrence of a state where the engine or the vehicle is stopped” may be counted as a frequency of changing from the operating state to the stopped state, or may be counted as a frequency of changing from the stopped state to the operating state.
[0019]
The present invention recovers regenerative energy in a storage battery to improve vehicle fuel efficiency, reduce exhaust gas, and prevent overdischarge of the storage battery during traveling in a congested urban area, and shorten the life of the storage battery such as a lead storage battery. It has the effect | action that the power supply control apparatus which prevents becoming, and its control method are realizable.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, examples specifically showing the best mode for carrying out the present invention will be described with reference to the drawings.
[0021]
"Example"
A power supply control device and a control method thereof according to an embodiment of the present invention will be described with reference to FIGS. The power supply control device of the embodiment is mounted on an idle stop vehicle.
FIG. 2 is a block diagram illustrating a configuration of the power supply control device according to the embodiment. In FIG. 2, 200 is an idle stop car, 201 is a generator, 202 is a load, 203 is a 12V, 50Ah liquid lead acid battery, 204 is a current sensor, 205 is a current measuring unit, 206 is a voltage measuring unit, and 210 is an engine. , 211 is a storage battery charge / discharge control unit. The storage battery charge / discharge control unit 211 includes an SOC calculation unit 207, an idle stop frequency calculation unit 208, and a generator control unit 209.
[0022]
The idling stop vehicle 200 has an idling stop function that automatically stops the engine without idling to park or stop, or automatically stops the engine after idling for a short time. The generator 201 is driven by the engine 210 of the idle stop vehicle 200 to generate power. The generated electric power is supplied to the load 202 and the liquid lead storage battery 203. Specifically, the load 202 is an audio device, an electrical component such as an air conditioner, a lamp, or a cell motor for starting the engine. The liquid lead-acid battery 203 is almost always charged at a constant voltage with the electric power from the generator 201 during traveling. While the engine 210 is stopped due to idle stop or the like, the liquid lead storage battery 203 is discharged to supply power to the load 202 (audio device, air conditioner, lamp, etc.). When the engine 210 starts, the liquid lead storage battery 203 is discharged to drive the generator 201 as an electric motor and supply power to the load 202 (cell motor for starting the engine). When the idle stop vehicle 200 is decelerated and braked, a regenerative current (regenerative energy) is generated in the generator 201. The liquid lead storage battery 203 is charged by this regenerative current.
[0023]
The current sensor 204 detects the current flowing through the liquid lead storage battery 203. The output of the current sensor 204 is input to the current measurement unit 205 and further input to the SOC calculation unit 207 as a current value. The voltage measuring unit 206 measures the voltage of the liquid lead storage battery 203 and outputs the measured voltage value to the generator control unit 209.
The storage battery charge / discharge control unit 211 controls the charge / discharge of the liquid lead storage battery 203 so that the SOC of the liquid lead storage battery 203 falls within a predetermined range. The SOC calculation unit 207 calculates the SOC by adding the integrated value of the charge / discharge electricity amount to the battery capacity when the liquid lead storage battery 203 is fully charged, and outputs the calculated SOC to the generator control unit 209.
[0024]
The generator control unit 209 controls the output voltage of the generator 201 by controlling the excitation current of the generator 201.
The idle stop frequency calculation unit 208 calculates the number of occurrences of idle stop per 10 minutes (occurrence frequency), and outputs it to the generator control unit 209.
[0025]
FIG. 1 is a flowchart illustrating a control method of the power supply control device according to the embodiment. In step 101, the idle stop frequency calculation unit 208 calculates the frequency of idle stops per 10 minutes. The generator control unit 209 determines whether or not the frequency of idle stop per 10 minutes is two times or more (step 102). In the case of two or more times, the process proceeds to step 103, and the target value of SOC (the upper limit value of the control range of the discharge capacity of the storage battery) is set to 100% (full charge). The generator control unit 209 sets the output voltage of the generator 201 to 15 V, and performs charging so that the SOC approaches 100% (step 105). Return to step 101.
[0026]
In step 102, when the frequency of idle stops per 10 minutes is less than twice, the routine proceeds to step 104, where the target SOC value is set to 95%. The generator control unit 209 sets the output voltage of the generator 201 to 13 V and performs control to bring the SOC close to 95% (step 105). Return to step 101.
[0027]
FIG. 3 is a diagram showing the relationship between the frequency of idle stop per 10 minutes and the amount of overcharge per hour of travel in an idle stop vehicle having the conventional example and the power supply control device of the present invention. A liquid lead-acid battery with a voltage of 12V and a battery capacity of 50Ah is mounted on an idle stop vehicle 200 and an idle stop vehicle having a conventional power supply control device, respectively, and the frequency of idle stop per 10 minutes is variously changed to run for 1 hour An experiment was conducted to check the amount of overcharge per unit. The average discharge amount per idle stop was 0.5% of the battery capacity. A solid line 301 is an experimental result of the idle stop vehicle having the power supply control device of the present invention that performs charge / discharge control of the storage battery by the method shown in the flowchart of FIG. A broken line 302 is an experimental result of an idle stop vehicle having a power supply control device of a conventional example that performs constant voltage charging (charging voltage is 14V) that always brings the SOC close to 100%.
[0028]
If the liquid lead-acid battery 203 continues to be used without being fully charged, sulfation occurs. In other words, lead sulfate, which is a discharge product, accumulates and cannot be charged, resulting in performance degradation. When sulfation occurs, the life of the liquid lead-acid battery 203 is rapidly shortened. When the frequency of idling stops is high as in driving in an urban area, the amount of discharge of the liquid lead storage battery 203 during idling stops increases and the charging time is shortened, so the SOC tends to decrease. According to the present embodiment, since the generator 201 is controlled and the charging voltage is set high in such a case, the liquid lead storage battery 203 can be charged in a short time and the SOC can be kept high. Thereby, stratification of the electrolyte solution of the liquid type lead-acid battery 203 can be suppressed, and a long life can be achieved.
[0029]
When the frequency of idle stops is low, such as during high-speed driving, the liquid lead-acid battery 203 is less likely to be insufficiently charged, so the SOC setting value is lowered (95% in the embodiment). Since the lead storage battery 203 is not always fully charged, regenerative energy due to braking or deceleration can be efficiently stored in the liquid lead storage battery 203. In the embodiment, the fact that regenerative energy is used for charging the liquid lead storage battery 203 without waste is shown in FIG. 3 (the amount of generated overcharge indicates the amount of regenerative energy consumed wastefully). I understand. As shown by a broken line 302 in FIG. 3, when charging is performed so that the SOC always approaches 100%, a loss of regenerative energy occurs. According to the present invention, it is possible to prevent the deterioration of the battery and the decrease in the electrolyte due to overcharging, and the fuel efficiency is improved.
[0030]
The threshold for the idle stop frequency per 10 minutes used in step 102 may be changed depending on the running conditions and the type of storage battery used. In the embodiment, the SOC target value is set in two stages according to the frequency of idle stop. However, it may be set in three or more stages, and a continuously changing value (for example, the occurrence frequency of idle stop is used as a parameter, and the SOC is set. Or a function for deriving a target value of.
In the embodiment, the SOC target value is increased when the frequency at which the engine stops is high, and the SOC target value is decreased when the frequency is low. Alternatively, the SOC target value may be increased when the frequency at which the vehicle is stopped is high, and the SOC target value may be decreased when the frequency is low.
[0031]
【The invention's effect】
According to the present invention, regenerative energy is recovered in a storage battery to improve vehicle fuel efficiency, reduce exhaust gas, and prevent overdischarge of the storage battery in traveling in congested urban areas, etc., and the life of the storage battery such as a lead storage battery The advantageous effect that the power supply control apparatus and its control method which prevent that becomes short can be implement | achieved is acquired.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a control method of a power supply control apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a power supply control apparatus according to an embodiment of the present invention. Figure showing the relationship between the frequency of idle stops per 10 minutes and the amount of overcharge per hour of travel in an idle stop vehicle with each device
200 Idle Stop Car 201 Generator 202 Load 203 Liquid Lead Acid Battery 204 Current Sensor 205 Current Measurement Unit 206 Voltage Measurement Unit 207 SOC Calculation Unit 208 Idle Stop Frequency Calculation Unit 209 Generator Control Unit 210 Engine 211 Storage Battery Charge / Discharge Control Unit

Claims (7)

An engine, a generator driven by the engine, a storage battery charged by the generator, and a storage battery charge / discharge control unit that controls charging / discharging of the storage battery so that a charging state of the storage battery is within a predetermined range And mounted on the car,
The storage battery charge / discharge control unit detects the frequency of occurrence of a state in which the engine or the vehicle is stopped, and sets the upper limit value of the predetermined range when the frequency is equal to or higher than a predetermined threshold value. The power supply control device is set to be higher than the upper limit value when the value is less than the threshold value. The generator can operate as an electric motor to assist the engine,
The storage battery charge / discharge control unit discharges the storage battery at least when the engine changes from a stopped state to an operating state, drives the generator as an electric motor, and after the engine continues to operate, the storage battery The power supply control device according to claim 1, wherein charge / discharge of the storage battery is controlled so as to be charged by a generator.   The storage battery charge / discharge control unit sets the upper limit value when the frequency is equal to or higher than the predetermined threshold value to the maximum rating of the storage battery, and when the frequency is less than the predetermined threshold value or from the predetermined threshold value 3. The power supply according to claim 1, wherein the upper limit value when the value is less than another threshold which is a low value is set to a value at which the storage battery can charge regenerative energy from the generator. Control device.   The power storage control device according to claim 1, wherein the storage battery is a lead storage battery. A control method for a power supply control device mounted on a car, comprising an engine, a generator driven by the engine, and a storage battery charged by the generator,
A control step of controlling charging / discharging of the storage battery so that the state of charge of the storage battery is within a predetermined range;
A detection step of detecting a frequency of occurrence of a state in which the engine or the vehicle is stopped;
Have
The upper limit value of the predetermined range of the control step when the frequency is equal to or higher than a predetermined threshold is set higher than the upper limit value when the frequency is less than the predetermined threshold. Control method of the device. The generator can operate as an electric motor to assist the engine,
At least when the engine changes from a stopped state to an operating state, the storage battery is discharged to drive the generator as an electric motor so that the storage battery is charged by the generator after the engine continues to operate. The control method of the power supply control device according to claim 5, wherein charging / discharging of the storage battery is controlled.   When the frequency is equal to or higher than the predetermined threshold, the upper limit value is set to the maximum rating of the storage battery, and when the frequency is lower than the predetermined threshold or lower than another threshold that is lower than the predetermined threshold The control method of the power supply control device according to claim 5 or 6, wherein the upper limit value is set to a value at which the storage battery can charge regenerative energy from the generator.

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