JP6705062B2 - Vehicle driving force control device and driving force control method - Google Patents

Description

The present invention relates to a driving force control device and a driving force control method for a vehicle.

In general, a vehicle such as an electric vehicle has a relatively low low-rotation torque of a motor as a drive source, and therefore, on a road surface with low friction such as a frozen road or a road mixed with dry sand (hereinafter referred to as a low μ road). The wheels tend to slip when the vehicle starts or runs.

Patent Document 1 proposes a technique for suppressing slip in such an electric vehicle.

Japanese Patent No. 3972535

According to the technique described in Patent Document 1, the slip is suppressed by performing control so that the slip ratio (s) of the wheels matches the target slip ratio (s ^* ).

Here, the slip ratio (s) of the wheel is calculated by the mathematical expression "s=(Vm-Vv)/Vm". However, s: slip ratio, Vm: drive wheel speed, Vv: vehicle body speed.

Here, in order to shorten the response time from when the vehicle slips until the slip suppression control functions, it is not necessary to detect the slip and perform the slip suppression control, but always perform the calculation of the slip suppression control. You will need it.

However, if the above-mentioned calculation of "s ^* =(Vm-Vv)/Vm" is always executed in the feedback control for slip suppression, there is a term (1/Vm) for dividing the vehicle body speed in this calculation. Therefore, for example, when Vm is lower than 0, 1/Vm included in the feedback gain has a large value. As described above, when the feedback response delay occurs in the state where 1/Vm is large, there is a problem that the control stability is deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a driving force control device for a vehicle that ensures the stability of slip suppression control even at low speeds.

In order to achieve the above object, a vehicle driving force control device and a driving force control method according to the present invention, when controlling a driving force of a vehicle equipped with a motor as a driving source, target motor torque based on an accelerator operation by a driver. Compensation in feedback control in which the difference between Vm and K·Vv converges to 0, where the drive wheel speed is Vm, the vehicle body speed is Vv, and the value set based on the target slip ratio of the wheels is K. As the amount, a correction amount for the target motor torque command value is constantly calculated, and the target motor torque command value is corrected based on the correction amount.

FIG. 1 is a block diagram showing a configuration example of a vehicle driving force control device according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of a correction amount calculation unit of the vehicle driving force control device according to the first embodiment. FIG. 3A is a graph showing a torque command value, a correction torque, and a final torque command value among simulation results of control by the vehicle driving force control apparatus according to the first embodiment. FIG. 3B is a graph showing the driving wheel speed and the driven wheel speed, out of the simulation results of the control by the vehicle driving force control apparatus according to the first embodiment. FIG. 3C is a graph showing the actual slip ratio in the simulation result of the control by the vehicle driving force control apparatus according to the first embodiment. FIG. 4 is a block diagram showing a configuration example of a vehicle driving force control device according to the second embodiment. FIG. 5 is a block diagram showing a configuration example of a correction amount calculation unit of the vehicle driving force control device according to the second embodiment. FIG. 6 is a flowchart showing PI reset processing and limit processing executed by the vehicle driving force control apparatus according to the second embodiment. FIG. 7A is a graph showing the torque command value, the correction torque, and the final torque command value in the simulation result when the PI reset process is not performed. FIG. 7B is a graph showing the driving wheel speed and the driven wheel speed in the simulation result when the PI reset process is not performed. FIG. 7C is a graph showing the actual slip ratio in the simulation result when the PI reset process is not performed. FIG. 7D is a graph showing the integrated value of the correction amount in the simulation result when the PI reset process is not performed. FIG. 8A is a graph showing a torque command value, a correction torque, and a final torque command value in the simulation result when the PI reset process is performed. FIG. 8B is a graph showing driving wheel speeds and driven wheel speeds in the simulation result when the PI reset process is performed. FIG. 8C is a graph showing the actual slip ratio in the simulation result when the PI reset process is performed. FIG. 8D is a graph showing the integrated value of the correction amount in the simulation result when the PI reset process is performed. FIG. 9A is a graph showing a torque command value, a correction torque, and a final torque command value in the simulation result when the limit process is performed. FIG. 9B is a graph showing the driving wheel speed and the driven wheel speed among the simulation results when the limit process is performed. FIG. 9C is a graph showing the actual slip ratio in the simulation result when the limit process is performed. FIG. 10 is a block diagram showing a configuration example of a vehicle driving force control device 1C according to the third embodiment. FIG. 11 is a diagram showing a grip force characteristic of a wheel with respect to a slip ratio on a high μ road and a low μ road.

Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the drawings. Here, in the accompanying drawings, the same members are designated by the same reference numerals, and duplicate description is omitted. Since the description here is the best mode for carrying out the invention, the invention is not limited to the mode.

[First Embodiment]
(Example of Configuration of Vehicle Driving Force Control Device According to First Embodiment)
A configuration example of the vehicle driving force control apparatus 1A according to the first embodiment will be described with reference to FIGS. 1, 2, and 3A to 3C.

Here, FIG. 1 is a block diagram showing a configuration example of the vehicle driving force control device 1A according to the first embodiment, and FIG. 2 shows a configuration example of the correction amount calculation unit 103 of the vehicle driving force control device 1A. Block diagrams and FIGS. 3A to 3C are graphs showing simulation results of slip suppression control by the vehicle driving force control device 1A.

As shown in FIG. 1, a vehicle driving force control apparatus 1A according to the present embodiment relates to a target motor torque based on a driver's accelerator operation for a drive unit 300 such as an electric vehicle including constituent members such as a motor and tires. Of the target motor torque, a correction amount calculation unit 103 configured by a PI control device or the like for calculating a correction amount of the target motor torque command value, and a calculation result of the correction amount calculation unit 103. A correction torque calculation unit 106 that corrects the target motor torque command value based on

The amplifier 104 is a vehicle speed Vv amplifier.

An adder/subtractor 105 that calculates a speed difference between the drive wheel speed Vm of the drive unit 300 and the amplification value of the vehicle body speed Vv is connected to the input side of the correction amount calculation unit 103.

Then, when the driving wheel speed is Vm, the vehicle body speed is Vv, and the value related to the target slip ratio of the wheel is K, the correction amount calculation unit 103 performs feedback control in which the difference between Vm and K·Vv converges to zero. As the correction amount, the correction amount for the command value of the target motor torque calculated by the target motor torque calculation unit is calculated.

Each unit of the vehicle driving force control device 1A can be configured by a central processing unit (CPU), a memory, an arithmetic circuit, and the like.

As shown in FIG. 2, the correction amount calculation unit 103 includes amplifiers 201 and 202 connected via a node n1, and an integrator 203 connected in series with the amplifier 202 and integrating an output value (gain 3). , And an adder 204 for adding the output value (gain 2) of the amplifier 201 and the integrated value of the integrator 203.

Further, the correction amount calculation unit 103 uses the difference between Vm and K·Vv (“K·Vv−Vm”) as an input value to calculate the correction amount for the command value of the target motor torque calculated by the target motor torque calculation unit 101. The correction torque calculation unit 106 calculates the correction torque by adding the command value of the target motor torque and the correction amount calculated by the correction amount calculation unit 103.

Here, the relationship between the wheel slip ratio (s), the driving wheel speed Vm, and the vehicle body speed Vv is expressed by the following mathematical expression (1).

s=(Vm-Vv)/Vm (1)
(However, s: wheel slip ratio, Vm: driving wheel speed, Vv: vehicle body speed)

If the command value of the target motor torque is corrected so that the difference between the wheel slip ratio (s) and the predetermined target slip ratio (s ^* ) converges to 0, the slip is suppressed. In this way, when the state where the difference between the two is 0 is expressed by the mathematical formula, the following mathematical formula (2) is obtained.

s ^* =(Vm-Vv)/Vm (2)
(However, s ^* : target slip ratio of the wheel)

Here, when the equation (2) is modified, the following equation (3) is obtained.

Vm=Vv/(1-s ^* )
=K·Vv (3)

However, K is represented by the following mathematical expression (4).

K=1/(1-s ^* ) (4)

Therefore, K related to the wheel slip ratio (s) can be obtained by K=1/(1-s ^* ) when the target slip ratio is s ^* .

That is, for example, by substituting a predetermined target slip ratio s ^* =0.1 into the equation (4),
K=(1/0.9)=about 1.1
Therefore, the value of K can be obtained.

The correction amount calculation unit 103 calculates the correction amount for the command value of the target motor torque calculated by the target motor torque calculation unit 101 using the difference between Vm and K·Vv as an input value, and the correction torque calculation unit 106 sets the target torque. The correction torque is calculated by adding the command value of the motor torque and the calculated correction amount. The correction amount calculation unit 103 constantly calculates such a correction amount.

In the present embodiment, the correction amount calculation unit 103 always calculates the correction amount. However, during the calculation of the correction, there is no fraction with the speed as the denominator, so that the vehicle body speed Vv becomes a very small value ( Even in the case of extremely low speed), divergence of the feedback amount is suppressed, and stable slip suppression control can be performed.

In addition, since the slip suppression control is constantly calculated in this manner, the motor torque is corrected quickly and the tire grip is recovered from the state where the vehicle actually slips.
Further, high-speed slip suppression control can be performed by a relatively simple calculation.

Then, according to the driving force control device 1A of the vehicle, the simulation result of the slip suppression control as shown in the graphs of FIGS. 3A to 3C could be obtained.

FIG. 3A is a graph showing a torque command value (C1), a correction torque (C2), and a final torque command value (C3) among the simulation results of the control by the vehicle driving force control apparatus according to the first embodiment.

FIG. 3B is a graph showing the driving wheel speed (D1) and the driven wheel speed (D2) of the simulation results of the control by the vehicle driving force control apparatus according to the first embodiment.

FIG. 3C is a graph showing the actual slip ratio (E1) of the simulation results of the control by the vehicle driving force control apparatus according to the first embodiment.

In the examples shown in FIGS. 3A to 3C, the high μ road is switched to the low μ road 3 seconds after the simulation is started (where μ means the friction coefficient). The high-μ road is, for example, the coefficient of friction of a dry asphalt road surface, and the low-μ road is a road surface having a lower friction coefficient than the high-μ road (for example, a state where there is snow on the road surface or a frozen state).

As can be seen from FIG. 3B and FIG. 3C, when the high μ road is switched to the low μ road within 3 seconds after the start of the simulation, the friction coefficient μ (hereinafter simply referred to as “μ”) is reduced, and the slip is instantaneously generated on the drive wheels. It has occurred. That is, the drive wheel speed (D1) is sharply increased as compared with the driven wheel speed (D2). Moreover, the actual slip ratio (E1) is also rapidly increasing.

However, as shown in FIG. 3A, the slip suppression control according to the present invention outputs the speed difference feedback correction torque (C2) and the final torque command value (C3) so as to reduce the torque immediately after the slip occurs. Therefore, the slip can be suppressed in a short time without causing a relatively long time lag as in the conventional case. That is, as shown in FIGS. 3B and 3C, the drive wheel speed (D1) is reduced to approach the driven wheel speed (D2), and the actual slip ratio (E1) is also reduced in a short time.

As described above, according to the vehicle driving force control apparatus 1A, it is possible to follow the target value without diverging the feedback amount.

[Second Embodiment]
A configuration example of the vehicle driving force control device 1B according to the second embodiment will be described with reference to FIGS. 4 and 5.

Here, FIG. 4 is a block diagram showing a configuration example of the vehicle driving force control device 1B according to the second embodiment, and FIG. 5 shows a configuration example of the correction amount calculation unit 301 of the vehicle driving force control device 1B. It is a block diagram.

In addition, about the structure similar to 1 A of driving force control apparatuses of the vehicle which concerns on 1st Embodiment, the same code|symbol is attached|subjected and the overlapping description is abbreviate|omitted.

As shown in FIG. 4, the vehicle driving force control apparatus 1B according to the present embodiment is configured to set a target motor torque based on a driver's accelerator operation for a drive unit 300 such as an electric vehicle including constituent members such as a motor and tires. Of the target motor torque, a correction amount calculation unit 301 including a PI controller for calculating a correction amount of the target motor torque command value, and a calculation result of the correction amount calculation unit 301. A correction torque calculation unit 106 that corrects the target motor torque command value based on

Further, the driving force control device 1B has a limit unit 302 that converts the correction amount to 0 when the correction amount of the correction amount calculation unit 301 is larger than 0. The limit unit 302 receives the correction amount from the correction amount calculation unit 301, and outputs the correction amount (0) subjected to the limit processing as necessary to the correction torque calculation unit 106. The limit process will be described later.

An adder/subtractor 105 that calculates the drive wheel speed Vm of the drive unit 300 and the amplified value of the vehicle body speed Vv is connected to the input side of the correction amount calculation unit 301.

Here, the adder/subtractor 105 outputs “K·Vv−Vm” (however, K>1, Vm>Vv).

When the relationship of “K·Vv<Vm” is established, the output of the adder/subtractor 105 becomes negative (that is, “K·Vv−Vm<0”). The input to the correction amount calculation unit 301 at this time is negative.

When the relationship of “Vv<K·Vv<Vm” is established in this manner, the friction on the road surface is small, which corresponds to the state where the drive wheels are slipping, and corresponds to the case where the vehicle travels on a low μ road. ..

On the other hand, when the relationship of “K·Vv>Vm” is established, the output of the adder/subtractor 105 becomes positive (that is, “K·Vv−Vm>0”). The input to the correction amount calculation unit 301 at this time is positive.

When the relationship of “K·Vv>Vm>Vv” is established in this way, the friction of the road surface is large and the vehicle and the driven wheels rotate at the same speed, which corresponds to the case where the vehicle travels on a high μ road. It is equivalent to traveling.

Then, when the driving wheel speed is Vm, the vehicle body speed is Vv, and the value relating to the target slip ratio of the wheel is K, the correction amount calculation unit 301 performs feedback control in which the difference between Vm and K·Vv converges to zero. As the correction amount, the correction amount for the command value of the target motor torque calculated by the target motor torque calculation unit is calculated. When the vehicle is traveling on a high μ road, “K·Vv−Vm>0”, and the output of the adder/subtractor 105 becomes positive. As a result, the target motor torque is controlled to increase, and the driver's intention is increased. Not acceleration may occur.

Therefore, in this embodiment, a limit unit 302 is provided to set the correction amount calculated by the correction amount calculation unit 301 to 0 when “K·Vv−Vm>” 0. As a result, the acceleration not intended by the driver when the vehicle is traveling on a high μ road is suppressed.

Each unit of the vehicle driving force control device 1B can be configured by a central processing unit (CPU), a memory, an arithmetic circuit, and the like.

Further, as shown in FIG. 5, the correction amount calculation unit 301 includes amplifiers 401 and 402 connected via a node n1, and an integrator 405 connected in series to the amplifier 402 and integrating an output value (gain 1). , And an adder 406 that adds the output value (gain) of the amplifier 401 and the integrated value of the integrator 405.

Further, a calculator 404 to which the difference and the command value of the target motor torque are inputted is connected via the node n2, and an output value from the calculator 404 is inputted to the integrator 405.

Further, the computing unit 404 computes whether or not the difference is 0 or more, and outputs “flag 1” if the input is positive and outputs “flag 0” if the input is negative.

Then, the integrator 405 resets the integrated value to 0 when "flag 1" is input, and continues the integration as it is when "flag 0" is input.

In the following, the process of resetting the integral value of the integrator 405 to 0 is referred to as “PI reset process”. The PI reset process will be described later.

The limit unit 302 limits the correction amount at the upper limit “0”. As a result, the correction torque becomes 0 even on the high μ road, so that it is possible to avoid continuously outputting the positive correction torque as in the reference example described later.

The process of limiting the upper limit of the correction amount by the limit unit 302 to “0” is called “limit process”. The limit process will be described later.

(PI reset processing and limit processing)
Next, with reference to FIG. 6, the PI reset process and the limit process executed by the vehicle driving force control apparatus 1B according to the present embodiment will be described.

Here, FIG. 6 is a flowchart showing a limit process and a PI reset process executed by the vehicle driving force control apparatus according to the second embodiment.

As shown in the flowchart of FIG. 6, when this process is started, first, in step S10, the computing unit 404 determines whether or not the input to the correction amount calculation unit 301 is “0” or more. That is, it is determined whether or not the output “K·Vv−Vm” of the adder/subtractor 105 is “0” or more. That is, in the slip state, “K·Vv-Vm” becomes less than “0” and the torque command value is corrected to be lowered, whereas “K·Vv-Vm” becomes “0” or more. Is in a state where the grip is high and the difference between Vv and Vm is small, and as a result, the correction value becomes positive and the torque command value is increased. If such “K·Vv−Vm” becomes “0” or more and the torque increase is corrected, acceleration unintended by the driver occurs, which is not preferable. Therefore, in the present embodiment, the following control is added to the first embodiment.

Then, when the determination result in step S10 is "NO", the process proceeds to step S11, the output value of the integrator 405 is output as it is, and the process proceeds to step S13.

On the other hand, if the determination result in step S10 is "YES", the process proceeds to step S12, and the integral value of the integrator 405 is reset to zero. That is, when the determination result in step S10 is "YES", "PI reset processing" is performed in step S12.

In step S13, it is determined by the processing of the limit unit 302 whether the output value of the integrator 405 is 0 or more. If the determination result is "NO", the process proceeds to step S14.

In step S14, a correction torque for speed difference feedback is calculated using the output value of the correction amount calculation unit 301, and then the process returns to the main control flow (not shown).

On the other hand, if “YES” is determined in step S13, the process proceeds to step S15 and the output value (PI output value) of the integrator 405 is reset to 0 (that is, the correction torque for speed difference feedback is After setting to 0), the process returns to the main control flow (not shown). That is, if the determination result in step S13 is "YES", "limit processing" is performed in step S15.

(Effect of PI reset processing)
Next, with reference to FIGS. 7A to 7D and FIGS. 8A to 8D, effects of the PI reset process executed by the vehicle driving force control device 1B according to the present embodiment will be described.

8A to 8D correspond to the second embodiment, and FIGS. 7A to 7D correspond to the first embodiment.

7A to 7D are graphs showing simulation results when the PI reset process is not performed. 8A to 8D are graphs showing simulation results when the PI reset process is performed.

More specifically, FIG. 7A is a graph showing a torque command value (C21), a correction torque (C22), and a final torque command value (C23). FIG. 7B is a graph showing the driving wheel speed (D21) and the driven wheel speed (D22). FIG. 7C is a graph showing the actual slip ratio (E21). FIG. 7D is a graph showing the integrated value (F21) of the correction amount. The integrated value (F21) shown in FIG. 7D is the integrated value in the integrator 203 shown in FIG.

In the example shown in FIGS. 7A to 7D, the high μ road is switched to the low μ road 40 seconds after the start of the simulation.

FIG. 8A is a graph showing a torque command value (C31), a correction torque (C32), and a final torque command value (C33). FIG. 8B is a graph showing the driving wheel speed (D31) and the driven wheel speed (D32). FIG. 8C is a graph showing the actual slip ratio (E31). FIG. 8D is a graph showing the integrated value (F31) of the correction amount. The integrated value (F31) shown in FIG. 8D is the integrated value in the integrator 405 shown in FIG.

In the example shown in FIGS. 8A to 8D, the same simulation conditions as those in the examples shown in FIGS. 7A to 7D are set, and the high μ road is switched to the low μ road 40 seconds after the start of the simulation.

As can be seen from FIGS. 7B and 7C, when the high μ road is switched to the low μ road 40 seconds after the start of the simulation, slippage occurs in the driving wheels due to the reduction of the friction coefficient μ (that is, the driven wheel speed). Compared with (D22), the drive wheel speed (D21) is rapidly increasing, and the actual slip ratio (E21) is also rapidly increasing).

However, in the case where the PI reset process is not performed as in this example, the slip suppression control cannot be performed until the integral value (F21) of the correction amount shown in FIG. 7D becomes “0”. As shown, the slipped state continues for a predetermined time (for example, several seconds).

That is, when the PI reset process is not performed, positive values are continuously integrated as shown in FIG. 7D. As a result, the correction amount remains positive for a while after the slip occurs, and the slip suppression process is not performed until the integral value (F21) becomes 0 (see FIG. 7A and the like).

On the other hand, as shown in FIG. 8A, according to the slip suppression control involving the PI reset process according to the present invention, the correction torque (C32) and the final torque command value of the speed difference feedback are set so as to reduce the torque in a short time immediately after the slip occurs. (C33) is output. This is because, as shown in FIG. 8D, since the integral value is reset to "0", the correction amount becomes a negative value when the slip occurs, and the slip suppression control can be performed in an extremely short time. Is.

That is, when the PI reset process is performed, the integrated value (F31) is once reset to 0 as shown in FIG. 8D, so that the integrated value (F31) becomes a negative value immediately after the occurrence of slip, Slip can be suppressed (see FIG. 8A etc.).

As a result, as shown in FIGS. 7A to 7D, the slip can be suppressed in a short time without causing a relatively long time lag until the slip suppression works (that is, as shown in FIG. 8B, the drive wheel speed ( D31) is reduced to approach the driven wheel speed (D32)).

(Effect of limit processing)
Next, with reference to FIGS. 9A to 9C, the effect of the limit process executed by the vehicle driving force control device 1B according to the present embodiment will be described.

9A to 9C are graphs showing simulation results when limit processing is performed.

FIG. 9A is a graph showing the torque command value (C41), the correction torque (C42), and the final torque command value (C43). FIG. 9B is a graph showing the driving wheel speed (D41) and the driven wheel speed (D42). FIG. 9C is a graph showing the actual slip ratio (E41).

In the example shown in FIGS. 9A to 9C, the same simulation conditions as those in the examples shown in FIGS. 3A to 3C are set, and the high μ road is switched to the low μ road 3 seconds after the start of the simulation.

When the limit process is not performed as shown in FIGS. 3A to 3C, a positive correction amount is output even if the slip suppression correction is not required on the high μ road, and the driver does not intend to accelerate the vehicle. Can be.

On the other hand, when the limit process is performed, the slip suppression correction may not be performed on the high μ road, as shown in FIG. 9A and the like.

On the other hand, when the running road surface state changes from the high μ road to the low μ road, “K·Vv−Vm” becomes less than “0”, and the slip control described in the first embodiment is restarted. It

As described above, according to the vehicle driving force control apparatus of the present embodiment, the feedback gain (control performance) can be prevented from being influenced by the vehicle speed, and the stability of control can be maintained even at an extremely low vehicle speed. You can

Further, since the slip suppression control can be constantly turned on, the slip suppression can be made to function even at the time of starting (extremely low speed), and the slip at the time of starting can be quickly dealt with.

Further, even on a road surface other than the low μ road, the slip suppression control can be made to function, so that the slip suppression effect can be improved.

When the limit process is performed as described above, the slip suppression control can be more effectively performed, and further, the acceleration that is more in line with the driver's intention can be realized.

[Third Embodiment]
A configuration example of the vehicle driving force control device 1C according to the third embodiment will be described with reference to FIGS. 10 and 11.

Here, FIG. 10 is a block diagram showing a configuration example of a driving force control device 1C for a vehicle according to the third embodiment, and FIG. 11 shows grip force characteristics of wheels with respect to slip ratios on a high μ road and a low μ road. It is a figure.

The same components as those of the vehicle driving force control apparatus 1A according to the first embodiment and the vehicle driving control apparatus 1B according to the second embodiment will be denoted by the same reference numerals and redundant description will be omitted.

As shown in FIG. 11, the high μ road and the low μ road have different μ peaks (the maximum value of μ in the figure, and the corresponding slip ratio grips most on the road surface). In this embodiment, the target slip ratio setting unit 107 that changes the target slip ratio (s ^* ) according to the road surface is provided. When the slip ratio is larger than the slip ratio of the μ peak value, the tire is in a slip state, and when the slip ratio is equal to or smaller than the slip ratio of the μ peak value, the tire grips.

When the following mathematical expression (5) is satisfied, it is estimated that the current target slip ratio is larger than the slip ratio that is the μ peak on the road surface and is in the slip region in the μ-slip ratio curve.

Α in the mathematical expression (5) is a predetermined threshold value for which the estimation is valid, and is set as an initial value (for example, 0.1) of the target slip ratio or the current target slip ratio.

The target slip ratio setting unit 107 searches for and sets an optimum target slip ratio on the road surface (a slip ratio having a μ peak, which will be referred to as an optimum slip ratio hereinafter). The method for searching for the optimum slip ratio is known in "Estimation and control of road surface conditions that make the most of the features of electric vehicles" (by Yoichi Hori and Kimihisa Furukawa). In this way, the target slip ratio setting unit 107 sets the target slip ratio to the optimum slip ratio, and updates K based on the above equation (4).

(Vm-Vv)/Vm>α (5)

Here, although the denominator of the speed exists in the mathematical expression (5), the target slip ratio setting unit 107 has the control system 100 of the driving force control device 1C for the vehicle (the configuration surrounded by the two-dot chain line in FIG. 10). , And the denominator of the speed itself does not become the gain in the feedback loop of the driving force control device 1C, and therefore the problem referred to in the first embodiment does not occur.

Although the content of the present invention has been described above with reference to the embodiments, the present invention is not limited to these descriptions, and it is obvious to those skilled in the art that various modifications and improvements can be made. The discussion and drawings that form part of this disclosure should not be understood as limiting the invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

For example, the configuration of the third embodiment (target slip ratio setting unit 107) may be applied to the configuration of the second embodiment.

In this case, first, the slip control of the above-described first embodiment is performed based on the target slip ratio. At that time, the above condition (5) is satisfied (in other words, the slip ratio of the μ peak value on the traveling low μ road is smaller than the target slip ratio, and slip control is performed at the target slip ratio. However, if the slip state cannot be obtained), the target slip ratio setting unit 107 searches for and sets the optimum slip ratio, as described in the third embodiment.

Then, when the road condition changes from a state where the vehicle is traveling with the optimum slip ratio set on the low μ road to a high μ road and “K·Vv−Vm” becomes “0” or more, the target slip ratio is set to the initial value. While returning to (for example, 0.1), limit processing is performed as described in the second embodiment. Further, when the limit processing is performed, the high μ road is changed to the low μ road, and when the condition of “K·Vv−Vm<0” is reached, the limit processing is released, and the slip suppression control based on the target slip ratio (target motor The correction of the torque command value) is restarted.

Note that the target slip ratio setting unit 107 may estimate the current μ, and when the estimated μ becomes larger than a predetermined value, the target slip ratio may be returned to the initial value (for example, 0.1). Incidentally, in the present embodiment, the target slip ratio setting unit 107 calculates μ based on the following mathematical expression (6), but is not particularly limited.

ただし、上記数式（６）において、ｒはタイヤ半径、Ｊは車軸イナーシャ、ωは駆動輪角速度、Ｎは垂直抗力、Ｔ：最終トルク指令値である。

However, in the above formula (6), r is the tire radius, J is the axle inertia, ω is the drive wheel angular velocity, N is the vertical drag force, and T is the final torque command value.

Each function shown in the above-described embodiments may be implemented by one or a plurality of processing circuits. The processing circuit includes a programmed processing device such as a processing device including an electrical circuit. Processing devices also include devices such as application specific integrated circuits (ASICs) and conventional circuit components arranged to perform the functions described in the embodiments.

This application claims priority based on Japanese Patent Application No. 2017-103586 filed on May 25, 2017, the entire contents of which are incorporated herein by reference.

1A, 1B Driving force control device 101 Target motor torque calculation unit 103, 301 Correction amount calculation unit 105 Adder/subtractor 106 Correction torque calculation unit 107 Target slip ratio setting unit 201, 202, 401, 402 Amplifier 203, 405 Integrator 204, 406 Adder 300 drive unit 302 limit unit 404 arithmetic unit 405 integrator

Claims (7)

A drive force control device for a vehicle equipped with a motor as a drive source,
A target motor torque calculation unit that calculates a command value of the target motor torque based on the accelerator operation of the driver,
A correction amount calculation unit that constantly calculates a correction amount for the command value of the target motor torque;
A correction torque calculation unit that corrects the command value of the target motor torque based on the calculation result by the correction amount calculation unit;
Have
The correction amount calculation unit,
The target motor torque is defined as a correction amount in feedback control that converges the difference between Vm and K·Vv to 0, where Vm is the driving wheel speed, Vv is the vehicle body speed, and K is a value set based on the target slip ratio of the wheels. A driving force control device for a vehicle, which calculates the correction amount for a command value of a target motor torque calculated by a calculation unit. The driving force control device for a vehicle according to claim 1,
The target slip ratio setting unit searches for the optimum slip ratio on the current road surface when "(Vm-Vv)/Vm" becomes larger than a predetermined value, and sets the optimum slip ratio as the target slip ratio. A driving force control device for a vehicle, further comprising a target slip ratio setting unit that sets and updates the K. The driving force control device for a vehicle according to claim 1 or 2, wherein
The driving force control device for a vehicle, wherein the K is set as K=1/(1-s ^* ) when the target slip ratio is s ^* . The driving force control device for a vehicle according to any one of claims 1 to 3,
The correction amount calculation unit,
Using the difference between Vm and K·Vv as an input value, a correction amount for the target motor torque command value calculated by the target motor torque calculation unit is calculated,
The correction torque calculation unit,
A driving force control device for a vehicle, wherein a correction torque is calculated by adding a command value of the target motor torque and a calculated correction amount. The driving force control device for a vehicle according to any one of claims 1 to 4,
A vehicle is characterized by further comprising a limit unit arranged between the correction amount calculation unit and the correction torque calculation unit, the limit unit converting the correction amount to 0 when the correction amount of the correction amount calculation unit is larger than 0. Driving force control device. The driving force control device for a vehicle according to any one of claims 1 to 5,
The correction amount calculation unit has an integrator,
The driving force control device for a vehicle, wherein the integrator includes a reset unit that resets the calculated integral value to 0 when the calculated integral value is larger than 0. A driving force control method for a vehicle equipped with a motor as a driving source, comprising:
Calculate the target motor torque command value based on the driver's accelerator operation,
The driving wheel speed is Vm, the vehicle body speed is Vv, the value relating to the target slip ratio of the wheels is K, and the correction amount in the feedback control for converging the difference between Vm and K·Vv to 0 is set to the command value of the target motor torque. The correction amount is constantly calculated,
A driving force control method for a vehicle, comprising: correcting a command value of the target motor torque based on the correction amount.

Images