JP6969580B2 - Hybrid vehicle power distribution control program and hybrid vehicle - Google Patents

Description

The present invention relates to a power distribution control program for a hybrid vehicle and a hybrid vehicle. More specifically, in a hybrid vehicle equipped with a main power source for driving a vehicle and a battery, the main power source and the battery are used so as to optimize fuel efficiency. The present invention relates to a hybrid vehicle power distribution control program for power distribution between vehicles, and a hybrid vehicle using the same.

A hybrid vehicle is a vehicle that has two or more power sources. Since the hybrid vehicle can use different power sources depending on the situation, it has a feature of higher fuel efficiency than a normal vehicle having one power source. However, in a hybrid vehicle, in order to further improve fuel efficiency, it is necessary to appropriately distribute the power of the power source according to the situation. Therefore, various proposals have been made conventionally regarding the power distribution of such a hybrid vehicle.

For example, Patent Document 1 describes a control device for a hybrid vehicle including an internal combustion engine, a motor, and a battery.
(A) The operating point at which the sum of the fuel consumption of the internal combustion engine (first fuel consumption) and the value obtained by converting the change in the battery charge rate into the fuel consumption (second fuel consumption) is minimized. Set it as the target operating point of the internal combustion engine,
(B) The coefficient (conversion coefficient) for converting the change in the charge rate of the battery into the fuel consumption is the fuel consumption of the internal combustion engine within a predetermined time and the motor used to charge the battery within the predetermined time. What is updated based on the ratio to the amount of power generated by the engine is disclosed.
The document describes that such a device can further improve fuel efficiency.

Patent Document 2 describes a control device for a hybrid vehicle including an internal combustion engine, a motor, and a battery.
(A) The operating point at which the sum of the fuel consumption of the internal combustion engine (first fuel consumption) and the value obtained by converting the change in the battery charge rate into the fuel consumption (second fuel consumption) is minimized. Set it as the target operating point of the internal combustion engine,
(B) As a coefficient (conversion coefficient) for converting the change amount of the battery charge rate into the fuel consumption amount, a value corresponding to the driving mode selected by the driver is selected.
The document describes that such a device can obtain driving force characteristics that match the characteristics of each traveling mode while improving fuel efficiency.

Further, Patent Document 3 describes a control device for a hybrid vehicle including an internal combustion engine, a motor, and a battery.
(A) The operating point at which the sum of the fuel consumption of the internal combustion engine (first fuel consumption) and the value obtained by converting the change in the battery charge rate into the fuel consumption (second fuel consumption) is minimized. Set it as the target operating point of the internal combustion engine,
(B) As a coefficient (conversion coefficient) for converting the change amount of the battery charge rate into the fuel consumption amount, a value corresponding to the identified driver is selected.
The document describes that such a device can improve fuel efficiency and reduce the difference in fuel efficiency between drivers.

Patent Documents 1 to 3 describe a method of power distribution control in a hybrid vehicle including an internal combustion engine, a battery for driving a vehicle, and a motor. However, in Patent Documents 1 to 3, deterioration of the battery is not taken into consideration. The performance of a battery gradually deteriorates as it is repeatedly charged and discharged. Therefore, if the power distribution control is performed without considering the deterioration of the battery, the actual power distribution will eventually deviate from the optimum value, and the fuel consumption will decrease.
Further, in a hybrid vehicle equipped with a fuel cell, a battery for driving a vehicle, and a motor, a power distribution control method for optimizing fuel efficiency, or power distribution in consideration of deterioration of the fuel cell and / or battery. There has been no conventional example in which a control method has been proposed.

Japanese Unexamined Patent Publication No. 2017-154619 Japanese Unexamined Patent Publication No. 2017-154620 Japanese Unexamined Patent Publication No. 2017-154621

The problem to be solved by the present invention is to optimize fuel efficiency in a hybrid vehicle provided with a main power source for driving a vehicle and a battery, even if the main power source and / or the battery deteriorates. It is to provide a power distribution control program for a hybrid vehicle that is capable.
Another problem to be solved by the present invention is to provide a hybrid vehicle provided with such a power distribution control program.

In order to solve the above problems, the power distribution control program for a hybrid vehicle according to the present invention comprises a computer for executing the following procedure.
(A) The main power source for generating the main power for driving the vehicle, the motor for driving the vehicle, and a part of the power generated by the main power source or the regenerative energy recovered by the motor temporarily. In a hybrid vehicle equipped with a battery that is stored as electric power and for supplying the stored electric power to the motor, the accelerator opening and the vehicle speed at time t are detected, and this is used as the required power _Preq (t) of the vehicle. Procedure A to convert and store in memory.
_{(B) Substituting the Preq} (t) into the _{composite function f (P PS} ) represented by the following equation (2) (including the function obtained by mathematically transforming the f (P _{PS)). Then, the procedure B of calculating the net output P PS} ^* of the main power source when the synthetic function f (P _PS ) becomes the minimum and storing it in the memory.
f (P _PS ) = fuel (P _PS ) + γ (P _req (t) -P _PS ) ² + λ · k (P _req (t) -P _PS ) ... (2)
However,
fuel ( _PPS ) is the fuel consumption function of the main power source.
P _PS is the net output of the main power source,
γ (> 0) is the first control parameter and correlates with the degree of deterioration of the battery or the battery and the main power source.
λ is the second control parameter and correlates with the charge rate (SOC) of the battery.
k (<0) is a negative constant peculiar to the battery.
(C) A procedure C for calculating the net output P _BAT ^* _{of the battery when the synthetic function f (P PS} ) is minimized based on the following equation (1a) and storing it in the memory.
P _BAT ^* = P _req (t) -P _PS ^* ... (1a)
(D) Procedure D for operating the main power source so that the output of the main power source becomes the _{P PS} ^*, and operating the battery so that the output of the battery becomes the _{P BAT} ^*.

The hybrid vehicle according to the present invention is
The main power source for generating the main power for driving the vehicle,
A motor for driving the vehicle and
A battery for temporarily storing a part of the power generated by the main power source or the regenerative energy recovered by the motor as electric power and supplying the stored electric power to the motor.
The main power source, the motor, and a control device for controlling the operation of the battery are provided.
The control device stores a power distribution control program for a hybrid vehicle according to the present invention.

The required power P _req (t) of the vehicle is expressed by the sum of _{the net output P PS} (t) of the main power source and the net output P _{BAT (t) of the battery.} In addition, the first term (fuel consumption function of the main power source), the second term (function proportional to the square of the net output of the battery), and the third term (proportional to the net output of the battery) on the right side of the equation (2). Functions) are all functions of _PPS (t).

Of these, the first term is a function that expresses the relationship between the net output of the main power source and the fuel consumption. Therefore, minimizing the first term corresponds to reducing fuel consumption.
The second term is the product of the square of the net output of the battery and γ. γ has a positive correlation with the deterioration of the battery and a negative correlation with the deterioration of the main power source. Therefore, to minimize the second term (the more advanced deterioration of the battery) gamma is larger the, closer to the net output P _PS of the main power source (t) required power P _req (t), battery It corresponds to reducing the output sharing ratio.
Further, the third term is proportional to the product of the net output of the battery and λ. λ correlates with the amount of SOC deviation from _{SOC c.} Therefore, minimizing the third term corresponds to charging or discharging the battery so _{that the SOC approaches SOC c.}

_{Therefore, by minimizing the composite function weighted by γ and λ, the required power P req} (t) is set to the net output P of the main power source according to the operating condition or deterioration condition of the main power source and / or the battery. It can be distributed to _PS ^* and the net output P _BAT ^{* of the battery.} As a result, fuel consumption can be optimally reduced. At the same time, deterioration of the battery or the battery and the main power source can be suppressed.

It is a schematic diagram of a synthetic function f ( _PPS). It is a schematic diagram of the fuel consumption function fuel ( _PPS). It is a schematic diagram of the second term of a synthetic function. It is a schematic diagram of the third term of a synthetic function. It is a schematic diagram of the function h (ΔSOC). It is a block diagram of the power control of a hybrid vehicle equipped with a fuel cell and a battery. It is a flow diagram of the power distribution control program of the hybrid vehicle which concerns on this invention.

Hereinafter, an embodiment of the present invention will be described in detail.
[1. Hybrid vehicle]
The hybrid vehicle according to the present invention is
The main power source for generating the main power for driving the vehicle,
A motor for driving the vehicle and
A battery for temporarily storing a part of the power generated by the main power source or the regenerative energy recovered by the motor as electric power and supplying the stored electric power to the motor.
It includes the main power source, the motor, and a control device for controlling the operation of the battery.

[1.1. Main power source]
The main power source is for generating the main power for driving the vehicle. Examples of the main power source include a fuel cell and an internal combustion engine.
When the main power source is a fuel cell, most of the electric power generated by the fuel cell is sent to the motor for driving the vehicle. Further, when the electric power generated by the fuel cell is excessive compared to the required electric power, a part of the electric power is stored in the battery.
On the other hand, when the main power source is an internal combustion engine, most of the driving force generated by the internal combustion engine is directly transmitted to the axle. Further, when the driving force generated by the internal combustion engine is excessive with respect to the required power, a part of the driving force is transmitted to the rotating shaft of the vehicle driving motor and converted into electric power. The converted power is stored in the battery.

[1.2. motor]
The motor is mainly for driving the vehicle. In the present invention, the structure of the motor is not particularly limited.
The motor is rotated by the electric power supplied from the fuel cell or the battery, and the rotational force is transmitted to the axle. However, when the internal combustion engine is generating an excessive driving force, or when the vehicle is decelerating, the driving force of the internal combustion engine or the rotational force of the axle is transmitted to the rotating shaft of the motor. That is, the motor is also used as a generator.

[1.3. battery]
The battery temporarily stores a part of the power generated by the main power source or the regenerative energy recovered by the motor as electric power, and supplies the stored electric power to the motor. In the present invention, the structure of the battery is not particularly limited.

[1.4. Control device]
The control device is for controlling the operation of the main power source, the motor, and the battery. The control device stores the power distribution control program of the hybrid vehicle according to the present invention, in addition to the general means for controlling them. The details of the power distribution control program will be described later.

[2. Power distribution control method]
[2.1. Composite function]
In a hybrid vehicle, the required power P _req (t) of the vehicle at time t is equal to the sum of _{the net output P PS} (t) of the main power source at time t and the net output P _{BAT (t) of the battery at time t.} It must always be powered by the main power source and battery. These relational expressions are shown in the following equation (1). ..
P _req (t) = P _PS (t) + P _BAT (t)… (1)

In the present invention, under such conditions,
(A) The fuel consumption function of the main power source (a function expressing the relationship between the output of the main power source and the fuel consumption), which has the effect of suppressing the fuel consumption of the main power source by minimizing it.
(B) A quadratic function of battery output that has the effect of suppressing battery output by minimizing it,
(C) The main power source by minimizing the composite function given by the sum of the linear functions of the battery output, which has the effect of keeping the battery fill rate SOC at the SOC center (SOC _{c) by minimizing it.} Determine the output.

Specifically, the composite function f ( _PPS ) is expressed by the following equation (2).
f (P _PS ) = fuel (P _PS ) + γ (P _req (t) -P _PS ) ² + λ · k (P _req (t) -P _PS ) ... (2)
However,
fuel ( _PPS ) is the fuel consumption function of the main power source.
P _PS is the net output of the main power source,
γ (> 0) is the first control parameter and correlates with the degree of deterioration of the battery or the battery and the main power source.
λ is the second control parameter and correlates with the charge rate (SOC) of the battery.
k (<0) is a negative constant peculiar to the battery.

FIG. 1 shows a schematic diagram of the composite function f ( _PPS). In FIG. 1, P _PS ^* represents the net output of the main power source when the composite function represented by the equation (2) is minimized. _{The net output P BAT} ^* of the battery at that time is expressed by the following equation (1a).
P _BAT ^* = P _req (t) -P _PS ^* ... (1a)

In the example shown in FIG. 1, the net output P _PS ^* of the main power source is larger than the required power P _req (t). Therefore, the surplus output (P _PS ^* −P _req (t)) of the main power source is charged to the battery as the battery _{charging power P BAT} ^*.
On the other hand, although not shown, when the net output P _PS ^* of the main power source is smaller than the required power P _req (t), the insufficient output (P _req (t) -P _PS ^* ) is the battery discharge power P _BAT ^*. Is discharged from the battery.
As a result, it is possible to adjust the usage amount _{of the net output P BAT} ^* of the battery according to various situations while optimally suppressing the fuel consumption.

[2.2. Fuel consumption function]
[2.2.1. Overview]
The first term on the right side of equation (2) is a fuel consumption function Fuel (P _PS), a function representing the relationship between the net output P _PS and the fuel consumption of the main power source.
FIG. 2 shows a schematic diagram of the fuel consumption function fuel ( _PPS ). As shown in FIG. 2, there is a positive correlation between _{P PS and fuel consumption, and the larger the P PS} , the higher the fuel consumption. That is, minimizing the first term corresponds to reducing fuel consumption.

[2.2.2. Approximation by quadratic function]
The shape of fuel ( _PPS ) differs depending on the type and specifications of the main power source, and generally cannot be expressed by a simple function. Therefore, _{when finding the minimum value of f (PPS} ), when pursuing calculation accuracy, it is preferable to find the optimum solution by iterative calculation such as the gradient method.
On the other hand, fuel (P _PS ) may be approximated by a quadratic function of _{P PS.} In this case, since _{the calculation of the minimum value of f (PPS} ) can be obtained by a simple calculation, the calculation time can be shortened.

The following equation (9) shows the fuel consumption function approximated by the quadratic function.
fuel (P _PS ) = a ・ P _PS ² ＋ b ・ P _PS ＋ c… (9)
However,
fuel ( _PPS ) is the fuel consumption function of the main power source.
P _PS is the net output of the main power source,
a (> 0), b, and c are coefficients obtained by fitting the relationship between the true fuel consumption characteristic of the main power source and the P _{PS, respectively.}
As a fitting method, for example, there is a least squares method.

Since the coefficient a is a positive value, when this is substituted into the equation (2), f ( _PPS ) becomes a quadratic convex function. Therefore, the minimum value is uniquely obtained as the solution of the following equation (10).
df (P _PS ) / dP _PS = 0 ... (10)
Therefore, the optimum solution P _PS ^* is given by the following equation (11).
P _PS ^* = (λ ・ k + 2γ ・ P _req (t) −b) / 2 (a + γ)… (11)
When the equation (11) is used, the calculation accuracy is slightly lowered, but there is an advantage that the calculation load is small because the repetitive calculation of the optimization can be avoided.

[2.3. Section 2 (quadratic function of battery output)]
[2.3.1. Overview]
The second term of the equation (2) consists of a function obtained by multiplying the square of the battery output by the first control parameter γ. γ is a function of the deterioration index of the main power source and the deterioration index of the battery, and always takes a positive value. Further, γ is a coefficient that becomes larger as the deterioration of the battery is larger and / or as the deterioration of the main power source is smaller.

FIG. 3 shows a schematic diagram of the second term of the composite function. As shown in FIG. 3, the _{larger the difference between P req} (t) and P _PS , the larger the second term. That is, minimizing the first term _{corresponds to bringing P PS} closer to P _req (t).
Further, as γ becomes larger, the slope of the parabola becomes larger, so that _{a slight increase in the difference between P req} (t) and P _PS appears as a large increase in the second term. In other words, the larger the γ, the smaller the output sharing ratio of the battery.

That is, the greater the deterioration of the battery and / or the smaller the deterioration of the main power source, the larger the γ. Further, as a result, the output sharing ratio of the main power source becomes large, so that deterioration of the battery can be suppressed.
Conversely, the smaller the deterioration of the battery and / or the greater the deterioration of the main power source, the smaller the γ. Further, as a result, the output sharing ratio of the battery becomes large, so that deterioration of the main power source can be suppressed.

[2.3.2. 1st control parameter γ]
In order to determine the second term, it is necessary to know the value of the first control parameter γ. Specifically, γ can be calculated from the following equations (3) and (4).

γ = γ ₀ + Δγ… (3)
Δγ = α / Det _PS + β ・ Det _BAT … (4)
However,
γ ₀ is the nominal value (constant),
Det _PS is a deterioration index of the main power source.
Det _BAT is a deterioration index of the battery.
α is _{a conversion coefficient (constant) of the reciprocal of Det PS} , and is zero (when the main power source is an internal combustion engine) or a positive value (when the main power source is a fuel cell).
β is a conversion coefficient (constant) of _{Det BAT.}

Det _PS is an index showing that the deterioration of the main power source is progressing as the value becomes larger. The size of Det _PS depends on the operation history of the main power source. When the main power source is a fuel cell (FC), the _{operation history that affects Det FC} includes, for example, the history of FC current / voltage, the time change rate of voltage, the frequency of each time change rate of voltage, and the voltage. There is a frequency for each.
When the main power source is an internal combustion engine, the influence of deterioration can be ignored. _{In this case, Det PS} is excluded from γ by setting α = 0 in the equation (4).

Det _BAT is an index showing that the deterioration of the battery is progressing as the value becomes larger. Det _BAT depends on the operation history of the battery. The _{operation history that affects the Det BAT} includes, for example, the battery temperature, the battery current history, and the battery charge rate history.

γ ₀ , α, and β are constants that are uniquely determined once the specifications of the main power source (that is, the fuel cell) and / or the battery are determined, respectively. Therefore, once Det _PS and Det _BAT are known, γ is uniquely determined. The calculation method of Det _PS and Det _BAT is not particularly limited, and the optimum method can be selected according to the purpose.

As a _{method of calculating Det PS} and Det _BAT , for example,
(A) A method of storing the actual operation history of the main power source and / or the battery and estimating γ from the actual operation history.
(B) A method of estimating γ from a map that gives γ to the parameters based on parameters other than the operation history of the main power source and the battery (for example, aging).
(C) A method of estimating γ from the deviation between the reference operating point (IV) and the measured operating point.
and so on.

Among these, the method of estimating γ based on the actual operation history is suitable as a method of calculating γ because the estimation accuracy of the deterioration progress of the main power source and / or the battery is high. Specifically, γ is preferably calculated by the following method.
(1) A database (A) showing the relationship between the operation history of the main power source and the deterioration index Det _PS of the main power source is stored in the memory in advance, and the Det _{PS corresponding to the actual operation history of the main power source is stored.} Read from the database (A) _{and store the read Det PS} in the memory (procedure E1).
_{(2) A database (B) showing} the relationship between the battery operation history and the battery deterioration index Det BAT is stored in the memory in advance, and the Det _BAT corresponding to the actual battery operation history is read from the database (B). , The read Det _BAT is stored in the memory (procedure E2).
(3) γ is calculated by substituting Det _PS and Det _BAT into the above-mentioned equations (3) and (4), and the calculated λ is stored in the memory (procedure E3).

[2.4. Section 3 (linear function of battery output)]
[2.4.1. Overview]
The third term of the equation (2) consists of a function obtained by multiplying the battery output by the second control parameter λ and the constant k. λ is a function of the charge rate (SOC) of the battery, and may take a positive value or a negative value. Further, λ is a coefficient whose absolute value becomes larger as the amount of deviation of SOC from the center of battery charge rate (SOC _{c) increases.}

FIG. 4 shows a schematic diagram of the third term of the composite function. k is a battery-specific negative value. Therefore, when λ is a positive value, the third term becomes a straight line rising to the right as shown in FIG. When λ is positive, minimizing the third term corresponds to reducing the output sharing ratio of the main power source and increasing the output sharing ratio of the battery.

On the contrary, when λ is negative, the third term is a straight line descending to the right, although not shown. When λ is negative, minimizing the third term corresponds to increasing the output sharing ratio of the main power source and decreasing the output sharing ratio of the battery.
Furthermore, since λ _{correlates with SOC c} , minimizing the third term corresponds to charging or discharging the battery so _{that the SOC approaches SOC c.}

[2.4.2. λ calculation method]
The second control parameter λ can be calculated by various methods.

[A. First method]
The first method is a method of calculating λ based on the following equations (5) and (6).
λ = λ ₀ + g ・ ΔSOC… (5)
ΔSOC = SOC-SOC _c ... (6)
However,
λ ₀ is the nominal value (constant),
g is a conversion coefficient (constant) of ΔSOC or a function obtained by multiplying the conversion coefficient of ΔSOC by a smoothing filter (low-pass filter).
SOC _c is the center of the charge rate SOC of the battery.

λ ₀ and SOC _c are constants that are uniquely determined once the battery specifications are determined. Further, g is a positive constant that can be arbitrarily set according to the purpose, and as the value becomes larger, a slight difference in ΔSOC appears as a large difference in λ. Therefore, if the SOC that changes from moment to moment is known, λ can be known.

In the first method, it is preferable to specifically calculate λ by the following method.
(1) The charge rate (SOC) of the battery is detected and stored in the memory (procedure F1).
(2) λ is calculated by substituting SOC into the above-mentioned equations (5) and (6), and the calculated λ is stored in the memory (procedure F2).

[B. Second method]
The second method is a method of calculating λ based on the equations (7) and (8).
λ = λ ₀ + sign (ΔSOC) ・ h (ΔSOC)… (7)
h (ΔSOC) = h (SOC-SOC _c )… (8)
However,
λ ₀ is the nominal value (constant),
sign (x) is a sign function,
h (x) is in the vicinity of the center of the charging rate (SOC _c) of the battery is zero, the SOC due to the SOC is increased or decreased from the SOC _c increases exponentially, the SOC _c A line-symmetrical non-linear function with the axis of symmetry.

sing (ΔSOC) represents a positive or negative sign of ΔSOC.
FIG. 5 shows a schematic diagram of the function h (ΔSOC). As shown in FIG. 5, h (ΔSOC) is an arbitrary nonlinear function having a _{large value near the upper limit and the lower limit of the SOC and a small value near the SOC c.} h (ΔSOC) is not particularly limited, and may be an even-order function such as a quadratic function or a 4-hour number, or a polynomial function showing even function characteristics.

The first method has an advantage that the calculation load is small because λ is represented by a linear function of SOC. However, in the first method, even if the SOC _{deviates slightly from the SOC c} , λ becomes a large value. Therefore, the battery may be charged and discharged more than necessary.
In contrast, the second method keeps λ at a relatively small value when the _{SOC is near SOC c.} Therefore, in the second method, charging / discharging of the battery is not repeated more than necessary.

In the second method, it is preferable to specifically calculate λ by the following method.
(1) The charge rate (SOC) of the battery is detected and stored in the memory (procedure F1).
(2) calculating the λ by substituted into the SO C to the above-described equations (7) and (8), and stores the λ calculated in the memory (Step F3).

[3. Power distribution control method]
FIG. 6 shows a block diagram of power control of a hybrid vehicle including a fuel cell and a battery. When the main power source (PS) is a fuel cell (FC), the power distribution control is performed as follows.

First, the accelerator opening and the vehicle speed are detected _{and converted into the required power P req} (t) of the vehicle. Here, the "vehicle speed" is the actual vehicle speed at the present time. Once the specifications of the hybrid vehicle are determined, the required power P _req (t) can be uniquely calculated from the accelerator opening and the vehicle speed.
Next, γ and λ are calculated based on the FC operation history (for example, the FC current / voltage history), the battery operation history (for example, the battery current history), and the SOC.
Next, using the calculated _Preq (t), γ, and λ, the net output P _FC ^* _{of FC when the composite function f (P FC} ) is minimized, and the net output P _BAT ^* of the battery are calculated. calculate.
Further, the main power source is operated so that the output of the main power source becomes _{P PS} ^*, and the battery is operated so that _{the output of the battery becomes P BAT} ^*.

[4. Hybrid vehicle power distribution control program]
FIG. 7 shows a flow chart of a power distribution control program for a hybrid vehicle according to the present invention.
First, in step 1 (hereinafter, simply referred to as “S1”), the accelerator opening degree and the vehicle speed at time t are detected. Next, in S2, this is _{converted into the required power P req} (t) of the vehicle and stored in the memory (procedure A).

Next, in S3, the first control parameter γ is calculated. The method for calculating γ is not particularly limited, but the methods using the above-mentioned equations (3) and (4) (procedures E1 to E3) are preferable. Since the details of the procedures E1 to E3 are as described above, the description thereof will be omitted.

Next, in S4, the second control parameter λ is calculated. The method of calculating λ is not particularly limited, but
(A) Method using equations (5) and (6) (procedures F1 and F2), or
(B) Method using equations (7) and (8) (procedures F1 and F3)
Is preferable. Since the details of the procedures F1 to F3 are as described above, the description thereof will be omitted.

_{Next, in S5, P req} (t) is _{added to the composite function f (P PS} ) (including the function obtained by mathematically transforming f (P _PS )) represented by the above equation (2). _{Substitution is performed to calculate the net output P PS} ^* of the main power source when the composite function f (P _PS ) is minimized, and this is stored in the memory (procedure B). Since the details of the equation (2) are as described above, the description thereof will be omitted.

In the S5, the fuel consumption function Fuel (P _PS) of formula (2) may be used quadratic function represented by the aforementioned formula (9). In this case, P _PS ^* _{can be obtained by substituting P req} (t) into the above equation (11) (procedure B'). Since the details of the formula (9) and the formula (11) are as described above, the description thereof will be omitted.

Next, in S6, based on the above equation (1a), _{the net output P BAT} ^* of the battery when the _{synthetic function f (P PS} ) is minimized is calculated and stored in the memory (procedure C). .. Since the details of the formula (1a) are as described above, the description thereof will be omitted.

Next, in S7, the main power source is operated so that the output of the main power source becomes _{P PS} ^*, and the battery is operated so that _{the output of the battery becomes P BAT} ^{* (procedure D).}
Next, proceed to S8. In S8, it is determined whether or not to continue the power distribution control. When the power distribution control is continued (S8: YES), the process returns to S1 and each step from S1 to S8 described above is repeated. On the other hand, when the power distribution control is terminated (S8: NO), the program is terminated as it is.

[5. Action]
The required power P _req (t) of the vehicle is expressed by the sum of _{the net output P PS} (t) of the main power source and the net output P _{BAT (t) of the battery.} In addition, the first term (fuel consumption function of the main power source), the second term (function proportional to the square of the net output of the battery), and the third term (proportional to the net output of the battery) on the right side of the equation (2). Functions) are all functions of _PPS (t).

Of these, the first term is a function that expresses the relationship between the net output of the main power source and the fuel consumption. Therefore, minimizing the first term corresponds to reducing fuel consumption.
The second term is the product of the square of the net output of the battery and γ. γ has a positive correlation with the deterioration of the battery and a negative correlation with the deterioration of the main power source. Therefore, to minimize the second term (the more advanced deterioration of the battery) gamma is larger the, closer to the net output P _PS of the main power source (t) required power P _req (t), battery It corresponds to reducing the output sharing ratio.
Further, the third term is proportional to the product of the net output of the battery and λ. λ correlates with the amount of SOC deviation from _{SOC c.} Therefore, minimizing the third term corresponds to charging or discharging the battery so _{that the SOC approaches SOC c.}

_{Therefore, by minimizing the composite function weighted by γ and λ, the required power P req} (t) is set to the net output P of the main power source according to the operating condition or deterioration condition of the main power source and / or the battery. It can be distributed to _PS ^* and the net output P _BAT ^{* of the battery.} As a result, fuel consumption can be optimally reduced. At the same time, deterioration of the battery or the battery and the main power source can be suppressed.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

The power distribution control program according to the present invention can be used for power distribution of a hybrid vehicle equipped with a fuel cell and a battery, or a hybrid vehicle equipped with an internal combustion engine and a battery.

Claims (9)

A hybrid vehicle power distribution control program that allows a computer to perform the following steps:
(A) The main power source for generating the main power for driving the vehicle, the motor for driving the vehicle, and a part of the power generated by the main power source or the regenerative energy recovered by the motor temporarily. In a hybrid vehicle equipped with a battery that is stored as electric power and for supplying the stored electric power to the motor, the accelerator opening and the vehicle speed at time t are detected, and this is used as the required power _Preq (t) of the vehicle. Procedure A to convert and store in memory.
_{(B) Substituting the Preq} (t) into the _{composite function f (P PS} ) represented by the following equation (2) (including the function obtained by mathematically transforming the f (P _{PS)). Then, the procedure B of calculating the net output P PS} ^* of the main power source when the synthetic function f (P _PS ) becomes the minimum and storing it in the memory.
f (P _PS ) = fuel (P _PS ) + γ (P _req (t) -P _PS ) ² + λ · k (P _req (t) -P _PS ) ... (2)
However,
fuel ( _PPS ) is the fuel consumption function of the main power source.
P _PS is the net output of the main power source,
γ (> 0) is the first control parameter and correlates with the degree of deterioration of the battery or the battery and the main power source.
λ is the second control parameter and correlates with the charge rate (SOC) of the battery.
k (<0) is a negative constant peculiar to the battery.
(C) A procedure C for calculating the net output P _BAT ^* _{of the battery when the synthetic function f (P PS} ) is minimized based on the following equation (1a) and storing it in the memory.
P _BAT ^* = P _req (t) -P _PS ^* ... (1a)
(D) Procedure D for operating the main power source so that the output of the main power source becomes the _{P PS} ^*, and operating the battery so that the output of the battery becomes the _{P BAT} ^*. The power distribution control program for a hybrid vehicle according to claim 1, further comprising the following procedure.
(E1) A database (A) showing the relationship between the operation history of the main power source and the deterioration index Det _PS of the main power source is stored in the memory in advance, and corresponds to the actual operation history of the main power source. The _{procedure E1 for reading the Det PS} from the database (A) and storing the read Det _PS in the memory.
(E2) A database (B) showing the relationship between the operation history of the battery and the deterioration index Det _{BAT of the battery is stored in the memory in advance, and the Det BAT} corresponding to the actual operation history of the battery is stored in the memory. Procedure E2 which reads from the database (B) _{and stores the read Det BAT} in the memory.
(E3) A procedure E3 in which the γ is calculated by substituting the Det _PS and the Det _BAT into the following equations (3) and (4), and the calculated λ is stored in the memory.
γ = γ ₀ + Δγ… (3)
Δγ = α / Det _PS + β ・ Det _BAT … (4)
However,
γ ₀ is the nominal value (constant),
Det _PS is a deterioration index of the main power source.
Det _BAT is a deterioration index of the battery.
α is _{a conversion coefficient (constant) of the reciprocal of Det PS} , and is zero (when the main power source is an internal combustion engine) or a positive value (when the main power source is a fuel cell).
β is a conversion coefficient (constant) of _{Det BAT.} The power distribution control program for a hybrid vehicle according to claim 1 or 2, further comprising the following procedure.
(F1) A procedure F1 for detecting the charge rate (SOC) of the battery and storing it in the memory.
(F2) A procedure F2 in which the SOC is calculated by substituting the SOC into the following equations (5) and (6), and the calculated λ is stored in the memory.
λ = λ ₀ + g ・ ΔSOC… (5)
ΔSOC = SOC-SOC _c ... (6)
However,
λ ₀ is the nominal value (constant),
g is a conversion coefficient (constant) of ΔSOC or a function obtained by multiplying the conversion coefficient of ΔSOC by a smoothing filter (low-pass filter).
SOC _c is the center of the charge rate of the battery. Instead of the steps F2, comprising the steps F3 to the λ calculated by the to enter the SO C cash to the following equation (7) and (8), and stores the λ calculated in the memory The power distribution control program for a hybrid vehicle according to claim 3.
λ = λ ₀ + sign (ΔSOC) ・ h (ΔSOC)… (7)
h (ΔSOC) = h (SOC-SOC _c )… (8)
However,
λ ₀ is the nominal value (constant),
sign (x) is a sign function,
h (x) is in the vicinity of the center of the charging rate (SOC _c) of the battery is zero, the SOC due to the SOC is increased or decreased from the SOC _c increases exponentially, the SOC _c A line-symmetrical non-linear function with the axis of symmetry. The power distribution control program for a hybrid vehicle according to any one of claims 1 to 4, wherein the fuel consumption function is represented by the following equation (9).
fuel (P _PS ) = a ・ P _PS ² ＋ b ・ P _PS ＋ c… (9)
However,
fuel ( _PPS ) is the fuel consumption function of the main power source.
P _PS is the net output of the main power source,
a (> 0), b, and c are coefficients obtained by fitting the relationship between the true fuel consumption characteristic of the main power source and the P _{PS, respectively.} The procedure B corresponds to any one of claims 1 to 5 _{comprising the procedure B'for calculating the P PS} ^* by substituting the P req (t) into the following equation (11). The described hybrid vehicle power distribution control program.
P _PS ^* = (λ ・ k + 2γ ・ P _req (t) −b) / 2 (a + γ)… (11) The power distribution control program for a hybrid vehicle according to any one of claims 1 to 6, wherein the main power source is a fuel cell. The main power source for generating the main power for driving the vehicle,
A motor for driving the vehicle and
A battery for temporarily storing a part of the power generated by the main power source or the regenerative energy recovered by the motor as electric power and supplying the stored electric power to the motor.
The main power source, the motor, and a control device for controlling the operation of the battery are provided.
A hybrid vehicle in which the power distribution control program for the hybrid vehicle according to any one of claims 1 to 6 is stored in the control device. The hybrid vehicle according to claim 8, wherein the main power source is a fuel cell.

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