JP3687270B2 - Generator control method for hybrid electric vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a generator control method for a hybrid electric vehicle including a traveling motor and a power generator.
[0002]
[Prior art]
Conventionally, as this type of technology, for example, a generator control method for a hybrid electric vehicle disclosed in Japanese Patent Laid-Open No. 6-225405 is known. In the present invention, the operation stop timing of the generator is controlled in accordance with the state of charge of the battery that changes with temperature, so that overcharge and overdischarge of the battery are prevented and the battery is protected.
[0003]
[Problems to be solved by the invention]
In the conventional hybrid electric vehicle generator control method described above, although the battery can be effectively protected, there is a problem that when the battery is at a low temperature, the output of the battery and the acceptance of charging are reduced.
[0004]
In order to solve this point, it is conceivable to heat the battery by utilizing the exhaust heat of the generator engine when the battery is at a low temperature. However, there is a disadvantage that the effect is not obtained because the engine is not warmed immediately after the start of traveling.
[0005]
The present invention has been made in view of the above problems, and provides a generator control method for a hybrid electric vehicle capable of quickly raising the temperature of a battery power source to an appropriate temperature and preventing battery performance degradation. For the purpose.
[0006]
In order to achieve the above object, a generator control method for a hybrid electric vehicle according to claim 1 is a driving electric motor serving as a driving source for driving an automobile, a battery power source, and electric power generated in the driving motor and the battery power source. In a hybrid electric vehicle including a power generation device to be supplied, when the temperature of the battery power source is equal to or lower than a predetermined temperature, the power generation device is configured to increase the temperature of the battery power source at an earlier timing of stopping the power generation device. It is characterized by controlling . In addition, although not particularly limited in the invention, the generator control method for a hybrid electric vehicle according to claim 2 is a discharge depth that controls stop of the power generator when the temperature of the battery power source is equal to or lower than a predetermined temperature. The power generator is controlled so as to raise the temperature of the battery power supply at an earlier timing by stopping the power generator.
[0007]
In the generator control method of the hybrid electric vehicle according to the first and second aspects, when the temperature of the battery power source is equal to or lower than the appropriate temperature, control is performed so as to advance the timing of stopping the power generation device. As a result, the temperature of the battery power source can be quickly raised to an appropriate temperature, and the performance degradation of the battery can be prevented. In addition, according to this, even when the battery power source heating device does not function in a state where the engine is cold, the temperature of the battery power source can be effectively increased, and the battery performance can be prevented from being lowered.
[0008]
The generator control method for a hybrid electric vehicle according to claim 1 or 2 , wherein the stop of the power generator is controlled in accordance with the temperature of the battery power source, in other words, with some relationship with the temperature of the battery power source. Is not particularly limited, and can be determined according to the usage environment of the electric vehicle to be mounted. The generator control method of the hybrid electric vehicle according to claim 3 , wherein the greater the difference between the appropriate battery power temperature and the actual battery power temperature, the deeper the depth of discharge for controlling the stop of the power generator, The stop of the power generator is controlled by the depth of discharge.
[0009]
The generator control method for a hybrid electric vehicle according to claim 3 suppresses a rapid change in the stop timing of the power generator by changing the timing of stopping the power generator according to the temperature of the battery power source. This eliminates the discomfort and anxiety given to the driver.
[0010]
In claims 1-3 generator control method for a hybrid electric vehicle according the type of the generator is not particularly limited, but can be employed power generator using an ordinary engine, hybrid electric claim 4, wherein In the motor vehicle generator control method, the power generator comprises a fuel cell.
In the generator control method for a hybrid electric vehicle according to the fourth aspect , since the power generator is quiet, even if the stop timing is freely changed, the driver does not feel uncomfortable.
[0011]
In the first to fourth aspects the generator control method for a hybrid electric vehicle, wherein the temperature of the battery power source, it is more preferable to employ the maximum temperature of the battery power supply.
The battery power source is more preferably a lithium ion battery.
[0012]
【The invention's effect】
According to the generator control method of the hybrid electric vehicle according to claim 1 and 2 , when the temperature of the battery power source is equal to or lower than an appropriate temperature, control is performed so as to advance the timing of stopping the power generation device. Can be quickly raised to an appropriate temperature, and the battery performance can be prevented from deteriorating. In addition, even when the battery power supply heating device does not function when the engine is cold, the temperature of the battery power supply can be effectively increased, and the battery performance can be prevented from deteriorating.
[0013]
According to the generator control method for a hybrid electric vehicle according to the third aspect, since the timing of stopping the power generation device is changed according to the temperature of the battery power supply, a sudden change in the stop timing of the power generation device can be suppressed. This eliminates the discomfort and anxiety given to the driver.
[0014]
According to the generator control method for a hybrid electric vehicle according to the fourth aspect , since the power generator is quiet, the stop timing can be freely changed without giving the driver a sense of incongruity. Therefore, it is possible to control the stop timing of the power generator in accordance with the optimal timing for raising the temperature of the battery power supply.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a generator control method for a hybrid electric vehicle according to the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0016]
(Embodiment 1)
[0017]
FIG. 1 is a block diagram showing the configuration of a series hybrid vehicle to which the present invention is applied.
[0018]
In the figure, a motor 10 is a traveling electric motor serving as a driving source for traveling an automobile. Specifically, the motor 10 is a three-phase AC motor, which is driven to rotate by being supplied with electric power from an inverter 11, and its output shaft is a differential gear 13. To the driving wheel 14 via
[0019]
The power generator 21 is a three-phase AC generator, and its input shaft is directly or indirectly connected to the engine 23 and is driven to rotate by the engine 23. The power generation output according to the start / stop of the engine Is obtained. The power generation output is supplied to the inverter 11 and the battery 31 via the converter 22.
[0020]
The battery 31 is a chargeable / dischargeable battery power source that serves as a power source for the motor 10, and is specifically an assembled battery in which a plurality of lithium ion batteries are combined. At the time of charging, the electric power of the power generator 21 passes through the converter 22. At the time of discharging, the discharged power is converted into three-phase AC power via the inverter 11 and supplied to the motor 10. More specifically, in a state where the engine 23 rotates and a power generation output is obtained from the power generation device 21, the generated power is rectified by the converter 22 and supplied to the battery 31 and also to the motor 10.
[0021]
The battery 31 is housed in a battery case 36, and the battery case 36 is provided with a cooling fan 37, which guides outside air to the battery 31 for cooling and guides air heated by a heating device (not shown) to the battery 31. The temperature of the battery 31 can be adjusted accordingly. Power for the cooling fan 37 is supplied from the auxiliary battery 61, and electric energy of the auxiliary battery 61 is stored from the battery 31 via the DC / DC converter 62.
[0022]
The motor controller 12 is a controller that controls the inverter 11 and the motor 10. The generator controller 24 is a controller that controls the converter 22, the power generation device 21, and the engine 23. The battery controller 32 is a controller that takes in the voltage and temperature 34 of the single cell in the battery 31, the total voltage of the battery, the current value 33 and the cooling air temperature 35, and controls the operation signal of the cooling fan. The vehicle controller 41 receives the battery capacity calculated by the battery controller 32 from the battery voltage, battery temperature, and current value, the output power of the battery, the regenerative reception power, and the like, and sends a command to the generator controller 24 to generate power. It is a controller that starts and stops the device 21.
[0023]
Next, the operation of the hybrid electric vehicle of the present embodiment having the above configuration will be described.
[0024]
Since a secondary battery that can be charged and discharged is accompanied by a chemical reaction, the sum of the Joule heat generation and the heat of the chemical reaction becomes an internal heat generation during charge and discharge. FIG. 2 is a graph in which charge / discharge power is plotted on the horizontal axis and the calorific value Q is plotted on the vertical axis. In the figure, line (1) shows the calorific value of the battery where the reaction heat during charging becomes an endothermic reaction, and line (2) shows the calorific value of the battery where the reaction heat during charging becomes an exothermic reaction. It is. In this embodiment, since a lithium ion battery is used as the battery 31, the reaction heat during charging is an endothermic reaction.
[0025]
The discharge power in the hybrid vehicle is 0 to 70 kW depending on driving conditions, and the charge power is 0 to 20 kW depending on the capacity of the power generator. As a frequently used condition, the discharge power is about 20 kW, and the charge power of the power generator is about 10 kW because of the engine sound that rotates the generator. Specifically, in the case of a lithium ion battery, it is preferable to install a battery having a capacity of 10 kWhr in consideration of the weight of the battery and the travel distance of only the battery.
[0026]
FIG. 3 plots the calorific value at this time. The calorific value at 20 kW discharge is 1.6 kW, and the calorific value at 10 kW charge is 0.15 kW. FIG. 4 shows the temperature rise of the battery when this hybrid electric vehicle travels. In region {circle around (1)}, the vehicle continues running only with the battery, and the battery temperature rises due to the internal heat generation of the battery. This traveling mode is referred to herein as battery output mode traveling. In area (2), the vehicle is driven by the output of the battery and the generator. Under the driving conditions below the output of the generator, the battery is charged, so the cooling capacity exceeds the heat generated by the battery, so the temperature drops. Go. This travel mode is referred to herein as battery + generator output mode travel. Region {circle around (3)} is a region where the vehicle runs with the output of only the battery as in the case of region {circle around (1)}. Region {circle around (4)} is a region that travels with the output of the battery and the generator as in region {circle around (2)}. Thereafter, region (1) and region (2) are repeated.
[0027]
FIG. 5 is a graph showing changes in performance characteristics due to changes in battery temperature. As shown in the drawing, both the output characteristics and the charge characteristics deteriorate at low temperatures. Therefore, the temperature condition for using the battery is preferably between TB1 * and TB2 *. As shown in FIG. 6, when the temperature is high (TF1 or higher), the cooling fan is controlled according to the temperature of the battery and cooled by outside air so that the temperature of the battery does not become TB2 * or higher.
[0028]
On the other hand, when the temperature is low (below TB1 *), it is necessary to heat the battery in order to ensure the battery performance. However, since the engine is not warmed immediately after the start of running, the heating effect cannot be obtained. Therefore, in the present invention, after one battery output mode traveling is completed, control is performed so as to shorten the battery + generator output mode traveling time. That is, the battery temperature is raised by bringing the stop timing of the generator to an earlier time, and the temperature is increased to TB1 * or more. FIG. 7 shows the rise in battery temperature according to the present invention. It can be seen that the temperature rise is improved after running in the battery output mode.
[0029]
In the means for heating the outside air by the heat of the engine and guiding it to the battery, the engine must be warmed up before the end of one battery output mode traveling. In addition, heating with air requires a long heating time due to poor heat transfer efficiency. On the other hand, in the present invention, the temperature rise of the battery is more effectively performed only by controlling the stop timing of the generator.
[0030]
8 to 10 show control flowcharts. FIG. 8 is a flowchart of the travel mode of the hybrid vehicle.
[0031]
In the figure, the vehicle key is turned on in step S11, and the flowchart is started. In step S12, if the previous use condition is stored, it is loaded from the storage device. In step S13, the traveling mode of the vehicle is determined. If the traveling mode is the battery output mode, the process proceeds to the battery output mode in step S141. The battery output mode is a mode in which the vehicle travels only with the battery output. On the other hand, if the traveling mode is the battery + generator output mode, the process proceeds to the battery + generator output mode in step S142. The battery + generator output mode is a travel mode that focuses on battery charging, and is a mode that travels mainly using the output power of the generator.
[0032]
FIG. 9 is a flowchart when the hybrid vehicle travels in the battery output mode. In step S21, the flow starts. When the key is turned off by the driver in step S22, the driving state is stored in step S221 and the operation is terminated. If the key is ON, it is determined in step S23 whether or not the battery discharge depth DOD has reached the preset DOD1, and if DOD1 is reached, the routine exits from this routine in step S24 and proceeds to step S141 in FIG. Return to battery + generator output mode. If the depth of discharge has not reached DOD1 in step S23, the battery output mode traveling is continued.
[0033]
FIG. 10 is a flowchart when the hybrid vehicle travels in the battery + generator output mode. In step S32, it is determined whether the measured battery temperature TB is higher or lower than TB1 *. If it is low, the discharge depth DOD of the battery that shifts to the battery output mode is set to DODC. The depth of discharge DODC shortens the discharge, battery + generator output mode. On the other hand, if the battery temperature is high, the discharge depth DOD of the battery that shifts to the battery output mode is set to DOD0. The depth of discharge DOD0 is the depth of discharge at which the battery can accept the most charge. When the key is turned off, the running state at that time is stored in step S331, and the process is terminated. In step S34, when the battery charge amount becomes smaller than the battery discharge depth DOD2, the battery + generator output mode is terminated. If the battery charge amount is not smaller than the battery discharge depth DOD2, the process returns to step S32.
[0034]
FIG. 11 is a diagram showing the state of the battery during the hybrid vehicle battery + generator output mode travel. The figure shows the charge / discharge state of the battery when stopping, accelerating, constant speed, decelerating, and stopping. When stopped, the battery is charged with an output that takes into account engine noise and generator efficiency. When accelerating or traveling up a steep hill, (maximum generator output + battery output) is required, so the battery is discharged at (vehicle output-maximum generator output). Since only the output of the generator is sufficient during constant speed traveling or gentle climbing, the generator's marginal output is used to charge the battery. Since the regenerative power from the motor is returned to the battery at the time of traveling at a reduced speed, the battery is charged with the regenerative power and the output of the generator. The broken line in the figure indicates the amount of charge of the battery, and the amount of charge increases with time. That is, the discharge depth DOD is shallow. Thus, the battery + generator output mode is a travel mode in which control is performed to charge the battery when there is a margin in the output of the generator.
[0035]
(Embodiment 2)
[0036]
Next, another example of the present invention will be described. In this embodiment, as shown in FIG. 12, the discharge depth of the battery that shifts from the battery + generator output mode to the battery output mode is set to the appropriate temperature TB1 * of the battery and the actual battery. It is characterized in that it is changed according to the difference in temperature TB.
[0037]
As shown in FIG. 5, the characteristics of the battery do not change suddenly at the optimum temperature TB1 * but change smoothly. Therefore, if the depth of discharge for shifting from the battery + generator output mode to the battery output mode is increased when the battery temperature is low, the battery output from the battery + generator output mode increases as the battery temperature approaches the appropriate temperature TB1 *. Even if the depth of discharge for shifting to the mode is reduced, the performance of the battery does not suddenly deteriorate. Therefore, the battery + generator output mode time is controlled to increase smoothly so as to eliminate the uncomfortable feeling that the unnaturalness of the generator operation stop gives to the driver. Further, since the battery can be heated by exhaust heat of the engine as time passes after the generator is operated, it is preferable to control in this way.
[0038]
(Embodiment 3)
[0039]
Next, another example of the present invention will be described with reference to FIG. 13. The power generation device of this embodiment is different from the engine of the above embodiment in that a fuel cell is used. The DC power generated by the fuel cell 51 is converted in voltage by the DC / DC converter 52 and supplied to the battery 31 or supplied to the motor 10 via the inverter 11. The fuel cell 51 and the DC / DC converter 52 are controlled by a fuel cell controller 53. If the fuel cell is used, the power generation device is quiet, so the start / stop timing can be freely changed without giving the driver a sense of incongruity. Therefore, the start / stop timing of the power generator can be controlled in accordance with the optimal timing for raising the temperature of the battery power supply.
[0040]
The embodiment described above is described in order to facilitate understanding of the present invention, and is not described in order to limit the present invention. Therefore, each element disclosed in the above embodiment includes all design changes and equivalents belonging to the technical scope of the present invention.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a series hybrid vehicle to which a generator control method for a hybrid electric vehicle of the present invention is applied.
FIG. 2 is a graph showing internal heat generation characteristics of a battery, in which charge / discharge power is plotted on the horizontal axis and heat generation amount Q is plotted on the vertical axis.
FIG. 3 is a graph showing internal heat generation characteristics of a battery, in which charge / discharge power is plotted on the horizontal axis and heat generation amount Q is plotted on the vertical axis.
FIG. 4 is a graph showing a rise in battery temperature when a hybrid electric vehicle runs.
FIG. 5 is a graph showing changes in performance characteristics due to changes in battery temperature.
FIG. 6 is a graph showing control characteristics of a cooling fan.
FIG. 7 is a graph showing an increase in battery temperature when the generator control method for a hybrid electric vehicle according to the embodiment is applied.
FIG. 8 is a flowchart of a travel mode of the hybrid vehicle according to the embodiment.
FIG. 9 is a flowchart when the hybrid vehicle according to the embodiment travels in a battery output mode.
FIG. 10 is a flowchart when the hybrid vehicle according to the embodiment travels in a battery + generator output mode.
FIG. 11 is a diagram illustrating a state of the battery when the hybrid vehicle according to the embodiment is traveling in the battery + generator output mode.
12 is a graph showing the depth of discharge for stopping the generator in Embodiment 2. FIG.
FIG. 13 is a block diagram illustrating a configuration of a series hybrid vehicle according to a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Motor 11 Inverter 12 Motor controller 13 Differential gear 14 Driving wheel 21 Power generation device 22 Converter 23 Engine 24 Generator controller 31 Battery 32 Battery controller 36 Battery case 37 Cooling fan 41 Vehicle controller 51 Fuel cell 61 Auxiliary battery 62 DC / DC converter

Claims (6)

In a hybrid electric vehicle including a driving electric motor serving as a driving source for driving an automobile, a battery power source, and a power generation device that supplies generated electric power to the driving motor and the battery power source, the temperature of the battery power source is equal to or lower than a predetermined temperature. If this is the case, the generator control method for a hybrid electric vehicle is characterized in that the generator is controlled so as to raise the temperature of the battery power supply at an earlier timing of stopping the generator. When the temperature of the battery power source is equal to or lower than a predetermined temperature, by increasing the depth of discharge for controlling the stop of the power generation device, the battery power source is heated so as to advance the timing of stopping the power generation device. The generator control method for a hybrid electric vehicle according to claim 1, wherein the generator is controlled. In a hybrid electric vehicle including a driving motor that is a driving source for driving a vehicle, a battery power source, and a power generation device that supplies generated power to the driving motor and the battery power source, an appropriate temperature of the battery power source and an actual battery the greater the difference between the temperature of the power supply, the set depth of discharge for controlling the stopping of the power generation device deeply, the generator control method for a hybrid electric vehicle and controlling the stopping of the power generation device in the discharge depth . The said electric power generating apparatus consists of fuel cells, The generator control method of the hybrid electric vehicle in any one of Claims 1-3 characterized by the above-mentioned. Wherein the temperature of the battery power source, the generator control method for a hybrid electric vehicle according to any one of claims 1 to 4, characterized in that employing the maximum temperature of the battery power supply. The battery power source, the generator control method for a hybrid electric vehicle according to any one of claims 1 to 5, characterized in that a lithium ion battery.

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