Control method for electric vehicle and control device for electric vehicle

Abstract

To appropriately perform slip control for suppressing slip even in a state where all of wheels are driven.SOLUTION: In a control method for an electric vehicle including a front motor 21, a rear motor 31, and a motor controller 14, in step S203, a final torque command value calculation unit 604 performs slip rotation control of the other motor for using a driving wheel speed of one of a front wheel 22 and a rear wheel 32 and driving the other of the front wheel and the rear wheel. In step S203, torque limitation units 803, 1403 correct a target torque command value of one of the driving wheels based on limitation torque Tlim and calculate a torque limitation value. In step S1901, S1902, the final torque command value calculation unit 604 determines, based on a torque distribution ratio of the front motor 21 and the rear motor 31, the other motor for performing slip rotation control.SELECTED DRAWING: Figure 19

Description

[Technical field]

[0001] The present invention relates to a control method for an electric vehicle and a control device for an electric vehicle. [Background technology]

[0002] Conventionally, there are technologies related to slip control that suppress a slip state of an electric vehicle. For example, a slip control technology has been proposed that detects a slip state of a driving wheel using the motor rotation speed of an electric motor that drives the wheels and the driven wheel speed, and calculates a slip control command torque when slip of the driving wheel is detected, thereby limiting the output of the electric motor and suppressing slip (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-158337 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional technology, slip control is performed by detecting the slip state of the driving wheels using the rotation speed of non-slip driven wheels (i.e. wheels not driven by the electric motor). However, in the case of an electric vehicle in which all wheels are driven, there is a possibility that all wheels may slip. In this way, when all wheels are slipping, it becomes difficult to properly detect the slip state, and there is a risk that it becomes difficult to properly execute slip control to suppress slipping.

[0005] An object of the present invention is to appropriately execute slip control that suppresses slip even when all of the wheels are driven. [Means for solving the problem]

[0006] One aspect of the present invention is a control method for an electric vehicle including a first drive motor that drives a first wheel, a second drive motor that drives a second wheel, and a control device that controls the operation of the first drive motor and the second drive motor. The control device executes slip rotation speed control of the other motor that drives the other drive wheel using the drive wheel speed of one of the first wheel and the second wheel, estimates a disturbance torque value indicating a torque related to a disturbance acting on the electric vehicle based on a torque command value (first torque command value) of the other motor, a torque command value (second torque command value) of one motor that drives one drive wheel, and a rotation state of the one motor, calculates a torque limit value based on the disturbance torque value and the first torque command value, corrects a target torque command value of the one motor based on the torque limit value to set a second torque command value, and determines the other motor that executes the slip rotation speed control based on a torque distribution ratio of the first drive motor and the second drive motor that is set based on a driving force required by the electric vehicle. Effect of the Invention

[0007] According to the present invention, slip control for suppressing slip can be appropriately executed even in a state where all of the wheels are driven. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of a system configuration of an electric vehicle. [Diagram 2] FIG. 2 is a flowchart showing an example of a control process performed by the motor controller. [Diagram 3] FIG. 3 is a diagram showing an example of an accelerator opening-torque table. [Figure 4] FIG. 4 is a block diagram showing an example of a functional configuration of the torque distribution calculation unit. [Diagram 5] FIG. 5 is an explanatory diagram showing parameters used in the equation of motion of an electric vehicle. [Figure 6] FIG. 6 is a block diagram showing an example of a system configuration for slip suppression calculation processing. [Figure 7]FIG. 7 is a block diagram showing an example of a system configuration for the front slip suppression calculation process. [Figure 8] FIG. 8 is a block diagram showing an example of a functional configuration of the front torque limit calculation unit. [Figure 9] FIG. 9 is a block diagram showing an example of a functional configuration of the disturbance estimation calculation unit. [Figure 10] FIG. 10 is a block diagram showing an example of a functional configuration of the limit torque calculation unit. [Figure 11] FIG. 11 is a flowchart showing an example of a process for calculating the front torque limit value. [Figure 12] FIG. 12 is a flowchart showing an example of a process for calculating an estimated vehicle speed value. [Figure 13] FIG. 13 is a block diagram showing an example of a system configuration for rear slip suppression calculation processing. [Figure 14] FIG. 14 is a block diagram showing an example of a functional configuration of the rear torque limit calculation unit. [Figure 15] FIG. 15 is a block diagram showing an example of a functional configuration of the disturbance estimation calculation unit. [Figure 16] FIG. 16 is a block diagram showing an example of a functional configuration of the limit torque calculation unit. [Figure 17] FIG. 17 is a flowchart showing an example of a calculation process of the rear torque limit value. [Figure 18] FIG. 18 is a flowchart showing an example of a calculation process of an estimated vehicle speed value. [Figure 19] FIG. 19 is a flowchart showing an example of a calculation process of the final torque command value. [Figure 20] FIG. 20 is a time chart when an electric vehicle is accelerating. [Figure 21] FIG. 21 is a time chart when an electric vehicle is decelerating. [Figure 22] FIG. 22 is a time chart when an electric vehicle is accelerating. [Figure 23] FIG. 23 is a time chart when the electric vehicle is decelerating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] 1 is a schematic diagram showing an example of the system configuration of an electric vehicle 10. In this embodiment, an electric vehicle 10 equipped with independent motors (electric motors) at the front and rear will be described as an example. In other words, the electric vehicle 10 is a four-wheel drive vehicle in which the front wheels 22 and the rear wheels 32 are each driven by a different motor. The electric vehicle 10 includes a front drive system 11, a rear drive system 12, a battery 13, and a motor controller 14.

[0011] The front drive system 11 is a system that drives front wheels 22 by a front motor 21. In addition to the front motor 21 and the front wheels 22, the front drive system 11 includes a front inverter 23, a rotation sensor 24, a current sensor 25, and the like.

[0012] The front motor 21 is, for example, a three-phase AC synchronous motor that generates driving force using AC power input from the front inverter 23 and transmits the driving force to the front wheels 22 via the front reduction gear 26 and the drive shaft 27. That is, the output torque of the front motor 21 generates torque (driving force) on the front wheels 22. In addition, when the drive shaft of the front motor 21 is rotated by the front wheels 22 while the electric vehicle 10 is traveling, the front motor 21 generates regenerative driving force (so-called regenerative torque). This allows the front motor 21 to recover the kinetic energy of the electric vehicle 10 as electrical energy.

[0013] The front wheels 22 are drive wheels disposed at the front of the electric vehicle 10. The front wheels 22 are connected to the front motor 21 via a front reduction gear 26 and a drive shaft 27.

[0014] The front inverter 23 includes, for example, two pairs of switching elements for each phase of the front motor 21. The front inverter 23 turns these switching elements on / off in response to a PWM (Pulse Width Modulation) signal input from the motor controller 14. As a result, the front inverter 23 converts DC power supplied from the battery 13 into AC power, and passes a desired current through the front motor 21 to drive the front motor 21. The switching elements constituting the front inverter 23 are, for example, power semiconductor elements such as insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistors (MOS-FETs). During regenerative control, the front inverter 23 converts AC power generated by the front motor 21 into DC power and inputs it to the battery 13.

[0015] The rotation sensor 24 detects the rotor phase αf of the front motor 21. The rotor phase αf is a so-called electrical angle [rad]. The rotation sensor 24 is, for example, a resolver or an encoder. The detected rotor phase αf is input to the motor controller 14. In this embodiment, the reference characters relating to the front are indicated with the subscript "f" and the reference characters relating to the rear are indicated with the subscript "r". For example, the rotor phase αf means the rotor phase of the front motor 21, and the rotor phase αr means the rotor phase of the rear motor 31.

[0016] The current sensor 25 detects the current value (i uf ,i vf ,i wf ) are detected. These current values ​​i uf ,i vf ,i wf is input to the motor controller 14.

[0017] The front drive system 11 also includes other sensors (for example, a wheel rotation sensor (not shown) and a steering sensor (not shown)). The wheel rotation sensor is a sensor that detects the rotation speed of the left and right front wheels 22. The steering sensor is a rotation sensor (for example, a resolver or an encoder) that detects the rotation angle of the steering wheel.

[0018] The rear drive system 12 is a system that drives rear wheels 32 by a rear motor 31, and is configured symmetrically to the front drive system 11. Therefore, in addition to the rear motor 31 and rear wheels 32, the rear drive system 12 also includes a rear inverter 33, a rotation sensor 34, a current sensor 35, a rear reduction gear 36, a drive shaft 37, etc. Each of these components that make up the rear drive system 12 functions in the same way as each of the components of the front drive system 11. In other words, the rear wheels 32 are drive wheels located at the rear of the electric vehicle 10. The rotor phase of the rear drive system 12 detected by the rotation sensor 34 is "αr". The current flowing through each phase of the rear motor 31 detected by the current sensor 35 is "i ur ,i vr ,i wr "

[0019] The battery 13 is provided in common to the front drive system 11 and the rear drive system 12, and discharges power by supplying it to drive the front motor 21 and the rear motor 31. During regenerative control, the battery 13 is charged by regenerative power generated by the front motor 21 and the rear motor 31.

[0020] The motor controller 14 is a control device for the electric vehicle 10. The motor controller 14 acquires various vehicle variable signals as digital signals, and generates PWM signals for controlling the front motor 21 and the rear motor 31 based on these vehicle variables. The motor controller 14 then inputs the generated PWM signals to the front inverter 23 and the rear inverter 33, respectively, to drive the front motor 21 and the rear motor 31 in accordance with the vehicle variables. In other words, the motor controller 14 generates drive signals for the front inverter 23 and the rear inverter 33 through drive circuits in accordance with the PWM signals.

[0021] The vehicle variables are parameters that represent the control state of the electric vehicle 10. The motor controller 14 uses, as the vehicle variables, the rotor phase αf and the current value i uf ,i vf ,i wf , the rotor phase αr and the current value i of the rear motor 31 ur ,i vr ,i wr In addition, the motor controller 14 acquires, as vehicle variables, for example, an accelerator opening θ, a vehicle body speed (vehicle speed) V, and a DC voltage value Vdc (not shown) of the battery 13. The accelerator opening θ is a parameter that indicates the amount of operation of the accelerator (not shown) by the driver. The vehicle variables, such as the accelerator opening θ, the vehicle speed V, and the DC voltage value Vdc of the battery 13, can be detected appropriately as necessary by a sensor (not shown) or the like. The motor controller 14 may acquire the vehicle variables directly from a sensor or the like, or may acquire some or all of the vehicle variables from another controller (computer) (not shown).

[0022] [Motor controller operation example] Fig. 2 is a flowchart showing an example of control processing executed by the motor controller 14. As shown in Fig. 2, the motor controller 14 executes input processing (step S201), basic target torque calculation processing (step S202), slip suppression calculation processing (step S203), current command value calculation processing (step S204), current control calculation processing (step S205), etc. That is, the motor controller 14 is programmed to function as an input processing unit that executes the input processing (step S201), a basic target torque calculation unit that executes the basic target torque calculation processing (step S202), a slip suppression calculation unit that executes the slip suppression calculation processing (step S203), a current command value calculation unit that executes the current command value calculation processing (step S204), a current control calculation unit that executes the current control calculation processing (step S205), etc.

[0023] In step S201, the motor controller 14 executes an input process to input signals necessary for each process described below. Alternatively, the motor controller 14 may obtain each of these signals from another controller through a predetermined communication. For example, the motor controller 14 obtains vehicle variables and the like necessary for controlling the front motor 21 and the rear motor 31.

[0024] Specifically, the motor controller 14 controls the three-phase current value i uf ,i vf ,i wf , and the three-phase current value i of the rear motor 31 ur ,i vr ,i wr is obtained from the current sensors 25 and 35. The three-phase current value i uf ,i vf ,i wf Since the sum of these is 0, the motor controller 14 can obtain, for example, the currents for two of these phases and calculate the current for the remaining phase. This is because the three-phase current value i ur ,i vr ,i wr The same applies to.

[0025] Furthermore, the motor controller 14 acquires the rotor phase αf of the front motor 21 and the rotor phase αr (electrical angle) [rad] of the rear motor 31 from the rotation sensors 24, 34. Furthermore, the motor controller 14 acquires a DC voltage value Vdc [V] of the battery 13. This DC voltage value Vdc [V] may be acquired from a voltage sensor provided on a DC power supply line, or may be acquired from a power supply voltage value transmitted from the battery controller.

[0026] In addition, the motor controller 14 controls, for example, the rotational angular velocity ω mf [rad / s], and the rotational angular velocity ω of the rear motor 31 mr [rad / s]. The rotational angular velocity ω of the front motor 21 is calculated. mf is the mechanical angular velocity, which is calculated by differentiating the rotor phase αf (electrical angle) and dividing it by the number of pole pairs of the front motor 21. Similarly, the rotational angular velocity ω mr is the mechanical angular velocity, which is calculated by differentiating the rotor phase αr (electrical angle) and dividing it by the number of pole pairs of the rear motor 31.

[0027] In this embodiment, the rotational angular velocity ω of the front motor 21 is used as a parameter representing the rotational speed of the electric motor included in the electric vehicle 100. mf and the rotational angular velocity ω of the rear motor 31 mr However, for example, the rotation speed N mf [rpm] and the rotation speed N of the rear motor 31 mr The rotation speed N of the front motor 21 may be used as a parameter representing the rotation speed of the electric motor. mf is obtained by dividing the rotor angular velocity ω of the front motor 21 by the number of pole pairs of the front motor 21, and calculating the rotational angular velocity ω mf After calculating the rotational angular velocity ω mf The rotation speed N of the rear motor 31 can be calculated by multiplying the rotation speed N by a unit conversion coefficient (60 / 2π) from [rad / s] to [rpm]. mr can be calculated in the same way.

[0028] In addition, the wheel rotation speed ω wfr , ω wfl , ω wrr , ω wrl [km / h] is obtained by multiplying each wheel rotation speed by the tire dynamic radius r to obtain the wheel rotation speed v [m / s], and applying a unit conversion coefficient (3600 / 1000) from [m / s] to [km / h] to the value obtained by these calculations. The left and right wheel rotation speeds of the front wheels 22 and the rear wheels 32 can be obtained based on the number of rotations detected by the wheel rotation sensors.

[0029] The accelerator opening degree θ [%] may be obtained from an accelerator opening degree sensor, or may be obtained from a vehicle controller or another controller via communication. The steering rotation angle θ_str [rad] is obtained from a rotation sensor that detects the steering rotation angle.

[0030] In step S202, the motor controller 14 (basic target torque calculation unit) calculates a target value (target torque command value T m * Specifically, the motor controller 14 executes a basic target torque calculation process to calculate a basic target torque based on the accelerator opening θ and the rotational angular velocity ω mf and / or the rotational angular velocity ω of the rear motor 31 mr Based on this, the target torque command value T m * An example of this setting will be described in detail with reference to FIG. 3. The motor controller 14 also sets the front target torque command value T mf * and the rear target torque command value T mr * An example of this setting will be described in detail with reference to FIG.

[0031] [Accelerator opening torque table example] 3 is a diagram showing an example of an accelerator opening-torque table, in which accelerator openings θ0 to θ8 respectively indicate 0 / 8 (fully closed), 1 / 8, 2 / 8, 3 / 8, 4 / 8, 5 / 8, 6 / 8, 7 / 8, and 8 / 8 (fully open).

[0032] As shown in FIG. 3, the electric vehicle 10 has a controller 11 that controls the accelerator opening θ and the rotational angular velocity ω of the front motor 21. mf and / or the rotational angular velocity ω of the rear motor 31 mr and the target torque command value T m * An accelerator opening-torque table in which the accelerator opening θ and the rotational angular velocity ω of the front motor 21 are associated with each other based on experiments, simulations, or the like is stored in advance. The motor controller 14 references the accelerator opening-torque table shown in FIG. mf and / or the rotational angular velocity ω of the rear motor 31 mr and the corresponding target torque command value T m * It is possible to obtain

[0033] [Example of front and rear motor torque distribution] 4 is a block diagram showing an example of a functional configuration of a torque distribution calculation unit 40 provided in the motor controller 14. The torque distribution calculation unit 40 includes a front wheel distribution gain multiplication unit 41 and a rear wheel distribution gain multiplication unit .

[0034] The torque distribution calculation unit 40 calculates the target torque command value T m * to the front wheels 22 and the rear wheels 32. mf * and the rear target torque command value T mr * The front target torque command value T mf * is the target torque command value T m * The rear target torque command value T mr *is the target torque command value T m * The torque to be output by the rear motor 31 is a target value. f is a value for setting the front and rear motor torque distribution, and is set to a value between 1 and 0. Note that the front and rear driving force distribution gain K f is set based on the driving force required by the electric vehicle 10. For example, the front / rear driving force distribution gain K f It is possible to set the above. As a setting method, a known setting method can be used.

[0035] Specifically, the torque distribution calculation unit 40 calculates the target torque command value T m * Front and rear drive force distribution gain K f By multiplying this, the front target torque command value T mf * In addition, the torque distribution calculation unit 40 sets the target torque command value T m * Front and rear driving force distribution gain (1-K f ) to obtain the rear target torque command value T mr * Set.

[0036] In step S203, the motor controller 14 executes a slip suppression calculation process to suppress slip of the electric vehicle 10. Specifically, the motor controller 14 executes a slip rotation speed control for one of the front wheels 22 and the rear wheels 32, and executes a torque limit control for the other wheel to limit the torque and reduce the amount of slip. In the slip suppression calculation process, the motor controller 14 also executes a front final torque command value T mf_f * and rear final torque command value T mr_f * The slip suppression calculation process will be described in detail with reference to Figs.

[0037] In step S204, the motor controller 14 calculates the target values ​​of the currents input to the front motor 21 and the rear motor 31 (dq-axis current target values ​​id * , iq * In the current command value calculation process, a current target value in a so-called dq-axis coordinate system is calculated. That is, in the current command value calculation process, the front final torque command value T mf_f * , rear final torque command value T mr_f * and the rotational angular velocity ω of the front motor 21. mf and the rotational angular velocity ω of the rear motor 31. mr and the DC voltage value Vdc of the battery 13, the dq axis current target value id * , iq * is obtained by referring to the table.

[0038] Specifically, the front inverter 23 outputs a front final torque command value T mf_f * and the rotational angular velocity ω of the front motor 21. mf and the DC voltage value Vdc of the battery 13, the dq-axis current target value idf * ,iqf * Similarly, the rear inverter 33 calculates the rear final torque command value T mr_f * and the rotational angular velocity ω of the rear motor 31. mr Based on the DC voltage value Vdc of the battery 13, the dq-axis current target value idr of the rear motor 31 is calculated. * ,iqr * Calculate the following.

[0039] In addition, the electric vehicle 10 has a front final torque command value T mf_f * and the rotational angular velocity ω of the front motor 21. mf , the DC voltage value Vdc of the battery 13, and the dq-axis current target value idf of the front motor 21. * ,iqf *The electric vehicle 10 stores a table in which the rear final torque command value T mr_f * and the rotational angular velocity ω of the rear motor 31. mr the DC voltage value Vdc of the battery 13, and the dq-axis current target value idr of the rear motor 31. * ,iqr * The motor controller 14 stores in advance a table in which the dq-axis current target value idf of the front motor 21 is associated with the dq-axis current target value idf of the front motor 21 by means of an experiment, a simulation, or the like. * ,iqf * , and the dq-axis current target value idr of the rear motor 31 * ,iqr * Calculate the following.

[0040] In step S205, the motor controller 14 executes a current control calculation process to calculate the PWM signals for driving the front motor 21 and the rear motor 31. The motor controller 14 calculates the PWM signal for driving the front motor 21 as follows.

[0041] First, the motor controller 14 calculates the three-phase current value i uf ,i vf ,i wf and the rotor phase αf of the front motor 21. Next, the motor controller 14 calculates the dq-axis current target values ​​idf and iqf of the front motor 21 based on the rotor phase αf of the front motor 21. * ,iqf * The motor controller 14 calculates the dq-axis voltage command values ​​vdf, vqf based on the deviation between the dq-axis current values ​​idf, iqf and the dq-axis current values ​​idf, iqf. At this time, the motor controller 14 may add a so-called non-interference control.

[0042] Next, the motor controller 14 calculates three-phase voltage command values ​​vuf, vvf, and vwf based on the dq-axis voltage command values ​​vdf, vqf and the rotor phase αf of the front motor 21. Then, the motor controller 14 calculates PWM signals (on duty) tu[%], tv[%], and tw[%] based on the three-phase voltage command values ​​vuf, vvf, and vwf and the DC voltage value Vdc of the battery 13.

[0043] By controlling the opening and closing of the switching elements of the front inverter 23 with the PWM signal obtained in this manner, it is possible to drive the front motor 21 with the desired torque indicated by the torque command value. Although the calculation of the PWM signal that drives the front motor 21 has been described here, the calculation of the PWM signal that drives the rear motor 31 is similar.

[0044] [On the equation of motion of electric vehicles] The slip suppression calculation process (S203) is executed based on a vehicle model of the electric vehicle 100. Specifically, the slip suppression calculation process (S203) uses a transfer characteristic Gp(s) based on the vehicle model of the electric vehicle 100 described below. The transfer characteristic Gp(s) is a transfer characteristic Gp(s) obtained by dividing the motor torque T m from motor rotation angular velocity ω m This is the transfer characteristic up to

[0045] First, the vehicle model of the electric vehicle 100, its equation of motion, and each transfer characteristic used in the slip suppression calculation process (S203) will be described.

[0046] Fig. 5 is an explanatory diagram showing parameters used in the equations of motion of electric vehicle 100. When the driving force transmission system of electric vehicle 100 is modeled as shown in Fig. 5, the equations of motion of electric vehicle 100 are expressed by the following formulas (1) to (5).

[0047]

number

[0048] The parameters in Fig. 5 and the above equations of motion are as follows. In Fig. 5, the "f" at the end of the auxiliary symbol (subscript) of each parameter indicates front and "r" indicates rear. Also, the "*" symbol at the top right of the parameters in (1) to (5) above indicates time differentiation.

[0049] J m : Motor inertia J w : Drive wheel inertia (per axle) M: Mass of the vehicle K d : Torsional rigidity of the drive system K t : Coefficient of friction between the tire and the road surface N: Overall gear ratio r: tire rolling radius ω m : Motor rotation speed T m :Motor torque T d : Torque of the drive wheels F: Force applied to the vehicle V:Vehicle speed ω w : Angular velocity of the drive wheels

[0050] Equations (1) to (5) are transformed into a Laplace transform to obtain the motor torque T m From the motor rotation angular velocity ω m The transfer characteristic Gp(s) up to is expressed by the following equation (6).

[0051]

number

[0052] Here, the coefficients b0 to b3 and the coefficients a1 to a4 shown in equation (6) are expressed by the following equations (7) to (14), respectively.

[0053]

number

[0054] When examining the poles and zeros of the transfer function (transfer characteristic) Gp(s) shown in equation (6), it can be approximated by the transfer function of the following equation (15), where one pole and one zero show extremely close values. This corresponds to α and β in equation (15) showing extremely close values.

[0055]

number

[0056] Therefore, by performing pole-zero cancellation (approximating α=β) in equation (15), it is possible to express the transfer characteristic Gp(s) in a second-order / third-order form as shown in the following equation (16).

[0057]

number

[0058] Here, equation (16) can be rewritten as equation (17) below.

[0059]

number

[0060] Here, ζz, ωz, ζp, and ωp shown in equation (17) are expressed by the following equations (18) to (21), respectively.

[0061]

number

[0062] Next, the slip suppression calculation process (S203 (see FIG. 2)) will be described with reference to FIG.

[0063] [Example of slip suppression calculation processing] 6 is a block diagram showing an example of a system configuration for implementing the slip suppression calculation process (S203 (see FIG. 2)). Specifically, the motor controller 14 includes a front slip suppression calculation unit 601, a rear slip suppression calculation unit 602, a ground load estimation calculation unit 603, and a final torque command value calculation unit 604.

[0064] The front slip suppression calculation unit 601 calculates the front final torque command value T mf_f * and rear final torque command value T mr_f * and the left rear wheel rotation speed ω wrl and the right rear wheel rotation speed ω wrr and the angular velocity ω of the front motor 21 mf and the front target torque command value T mf * and the rear target torque command value T mr * Based on the front slip rotation speed control torque T mf_slip * and the front torque limit value T mf_limit * The front slip rotation speed control torque T mf_slip * is a value used when slip rotation speed control is executed for the front wheels 22. Also, the front torque limit value T mf_limit * are values ​​used when the slip rotation speed control is not performed for the front wheels 22 (i.e., when the torque limit control is performed for the front wheels 22). mf_slip * and the front torque limit value T mf_limit * The calculation process will be described in detail with reference to FIG.

[0065] [Example of front slip suppression calculation processing] 7 is a block diagram showing an example of the functional configuration of the front slip suppression calculation unit 601. Specifically, the front slip suppression calculation unit 601 includes a front torque limit calculation unit 701, a vehicle speed estimation unit 702, and a front slip rotation speed control calculation unit 703.

[0066] The front torque limit calculation unit 701 calculates the angular velocity ω mf and the front target torque command value T mf * and the front final torque command value T mf_f * and rear final torque command value T mr_f * Based on the front torque limit T mf_limit * This front torque limit value T mf_limit * The calculation process will be described in detail with reference to FIG.

[0067] [Example of front torque limit calculation section configuration] 8 is a block diagram showing an example of the functional configuration of the front torque limit calculation section 701. Specifically, the front torque limit calculation section 701 includes a disturbance estimation calculation section 801, a limit torque calculation section 802, and a torque limit section 803.

[0068] The disturbance estimation calculation unit 801 calculates the rear final torque command value T mr_f * and the front final torque command value T mf_f * and the angular velocity ω of the front motor 21 mf Based on this, the estimated disturbance torque acting on the vehicle body (disturbance torque estimate) T^ dist This disturbance torque estimate T^ is calculated. dist The calculation process will be described in detail with reference to FIG.

[0069] Here, the disturbance estimation calculation unit 801 is often generated based on a vehicle model that runs on a high μ road (for example, an asphalt road surface). Therefore, when the electric vehicle 10 runs on a high μ road, the disturbance is 0 or close to 0. In contrast, when a torque command value equivalent to a high μ road is applied on a low μ road, it is considered that the actual wheel speed of the electric vehicle 10 will increase compared to a high μ road. That is, the actual wheel speed of the electric vehicle 10 changes quickly. Therefore, when the electric vehicle 10 slips on a low μ road, it is possible to estimate the amount of the slip as a disturbance due to the low μ road. Note that the disturbance estimation calculation unit 1401 (see FIG. 14) is also capable of estimating disturbances in a similar manner.

[0070] [Example of configuration of disturbance estimation calculation section] 9 is a block diagram showing an example of a functional configuration of the disturbance estimation calculation unit 801. Specifically, the disturbance estimation calculation unit 801 includes a first motor torque estimate value calculation unit 901, a multiplication unit 902, a final total torque command value calculation unit 903, a second motor torque estimate value calculation unit 904, and a disturbance torque estimate value calculation unit 905.

[0071] The first motor torque estimate calculation unit 901 calculates the front motor torque T mf and the rotational angular velocity ω of the front motor 21. mf Transfer characteristics of model G pf H(s) / G using a low-pass filter H(s) whose order is equal to or greater than the difference between the denominator order and the numerator order of (s) pf At (s), the rotational angular velocity ω of the front motor 21 mf That is, the first motor torque estimate value is calculated based on the rotational angular velocity ω mf is a motor torque estimate based on

[0072] Here, G pf (s) indicates the transmission characteristics from motor torque to rotational speed. Therefore, 1 / G pf (s) to obtain the rotational angular velocity ω mf from front motor torque T mfIn addition, when the electric vehicle 10 actually slips while traveling on a low μ road, the amount of this slip can be estimated as the disturbance torque.

[0073] The multiplication unit 902 multiplies the rear final torque command value T mr_f * The unit conversion coefficient is used to calculate the value. Here, the unit conversion coefficient is the front overall gear ratio N f , Rear overall gear ratio N r , front tire rolling radius r f , rear tire rolling radius r r Here is an example using

[0074] The final total torque command value calculation unit 903 multiplies the value calculated by the multiplication unit 902 (rear final torque command value T mr_f * multiplied by the unit conversion coefficient) and the front final torque command value T mf_f * The final total torque command value is calculated by adding the above.

[0075] The second motor torque estimate calculation unit 904 filters the final total torque command value calculated by the final total torque command value calculation unit 903 using a low-pass filter H(s) to calculate a second motor torque estimate. That is, the second motor torque estimate is calculated based on the front final torque command value T mf_f * and rear final torque command value T mr_f * is a motor torque estimate based on

[0076] The disturbance torque estimated value calculation unit 905 calculates the disturbance torque estimated value T^ by subtracting the first motor torque estimated value calculated by the first motor torque estimated value calculation unit 901 from the second motor torque estimated value calculated by the second motor torque estimated value calculation unit 904. dist Calculate.

[0077] Here, when slip rotation speed control is executed for the rear wheels 32, the torque of the front wheels 22 is limited and the amount of slip is also reduced. In this case, the angular velocity (rotational angular velocity ω mf ) based on the external disturbance acting on the body of the electric vehicle 10, it is possible to accurately estimate the external disturbance acting on the vehicle body even on a low μ road.

[0078] The disturbances considered in this embodiment include air resistance, modeling errors due to variations in vehicle mass (number of passengers, load), tire rolling resistance, gradient resistance, and phase shift between the first motor torque estimate and the second motor torque estimate. The disturbance factors vary depending on the driving conditions. In the example shown in FIG. 9, the front final torque command value T mf_f * and rear final torque command value T mr_f * and the angular velocity ω of the front motor 21 mf and front motor torque T mf and the rotational angular velocity ω of the front motor 21 mf Transfer characteristics of model G pf Based on (s), the disturbance torque estimate T^ dist In addition, in the example shown in FIG. 15, the front final torque command value T mf_f * and rear final torque command value T mr_f * and the angular velocity ω of the rear motor 31 mr and rear motor torque T mr and the rotational angular velocity ω of the rear motor 31 mr Transfer characteristics of model G pr Based on (s), the disturbance torque estimate T^ dist It is possible to estimate these disturbance factors all at once by calculating

[0079] Returning to FIG. 8, the limit torque calculation unit 802 calculates the rear final torque command value T mr_f * and the estimated disturbance torque T^ dist Based on the limit torque Tlim The calculation process of this limit torque will be described in detail with reference to FIG.

[0080] [Example of limit torque calculation section configuration] 10 is a block diagram showing an example of a functional configuration of the limit torque calculation unit 802. Specifically, the limit torque calculation unit 802 includes an adder 1001.

[0081] The adder 1001 calculates the rear final torque command value T mr_f * and the estimated disturbance torque T^ dist Adding these together, the limit torque T lim The disturbance torque estimate T^ is calculated. dist When the electric vehicle 10 is slipping, the limit torque T lim is the rear final torque command value T mr_f * is lower than

[0082] Returning to FIG. 8, the torque limiting unit 803 determines the front target torque command value T mf * and limit torque T lim Based on the front torque limit T mf_limit * The calculation process of the front torque limit value will be described in detail with reference to FIG.

[0083] [Example of torque limiting section operation] FIG. 11 is a flowchart showing an example of a calculation process of the front torque limit value by the torque limiting unit 803.

[0084] In step S1101, the torque limiting unit 803 calculates the front target torque command value T mf * The sign of the front target torque command value T mf * It is determined whether the front target torque command value T mf *The sign of is positive, or the front target torque command value T mf * If it is 0, proceed to step S1102, and if its sign is negative, proceed to step S1103.

[0085] In steps S1102 and S1103, the torque limiting unit 803 calculates the front target torque command value T mf * and limit torque T lim In other words, the front target torque command value T mf * ≧Limit torque T lim In step S1102, it is determined whether the front target torque command value T mf * is the limit torque T lim If the front target torque command value T mf * is the limit torque T lim If it is less than that, proceed to step S1105.

[0086] In step S1104, the torque limiting unit 803 determines the front torque limit value T mf_limit * Limit torque T lim Set to.

[0087] In step S1105, the torque limiting unit 803 determines the front torque limit value T mf_limit * The front target torque command value T mf * In this manner, in this embodiment, the front target torque command value T mf * If is greater than or equal to 0, the front torque limit T mf_limit * The upper limit of the torque T lim In addition, the rear final torque command value T mr_f * and the estimated disturbance torque T^ dist Based on this, the front final torque command value T mf_f* By limiting the upper limit, it is possible to suppress spinning of the rear wheels 32 due to an excessive power running torque.

[0088] In step S1103, the front target torque command value T mf * is the limit torque T lim If the front target torque command value T mf * is the limit torque T lim If it is less than that, proceed to step S1107.

[0089] In step S1106, the torque limiting unit 803 calculates the front torque limiting value T mf_limit * The front target torque command value T mf * Set to.

[0090] In step S1107, the torque limiting unit 803 determines the front torque limit value T mf_limit * Limit torque T lim In this manner, in this embodiment, the front target torque command value T mf * If is negative, the front torque limit T mf_limit * The lower limit of the torque T lim In addition, the rear final torque command value T mr_f * and the estimated disturbance torque T^ dist Based on this, the front final torque command value T mf_f * By restricting the lower limit, it is possible to suppress spinning of the front wheels 22 due to excessive regenerative torque.

[0091] Returning to FIG. 7, the vehicle speed estimation unit 702 estimates the rear target torque command value T mr * and the right rear wheel rotation speed ω wrr and the left rear wheel rotation speed ω wrlThe process of calculating the estimated vehicle speed V^ will be described in detail with reference to FIG.

[0092] [Example of vehicle speed estimation unit operation] FIG. 12 is a flowchart showing an example of a calculation process of the vehicle speed estimation unit 702 for the vehicle speed estimated value.

[0093] In step S1201, the vehicle speed estimator 702 calculates the rear target torque command value T mr * That is, the sign of the rear target torque command value T mr * It is determined whether the rear target torque command value T mr * The sign of is positive, or the rear target torque command value T mr * If it is 0, the process proceeds to step S1202, and if its sign is negative, the process proceeds to step S1203.

[0094] In steps S1202 and S1203, the vehicle speed estimator 702 estimates the right rear wheel rotation speed ω wrr and the left rear wheel rotation speed ω wrl That is, the right rear wheel rotation speed ω wrr ≧ Left rear wheel rotation speed ω wrl In step S1202, it is determined whether the right rear wheel rotation speed ω wrr is the left rear wheel rotation speed ω wrl If so, the process proceeds to step S1204. wrr is the left rear wheel rotation speed ω wrl If it is less than that, proceed to step S1205.

[0095] In step S1204, the vehicle speed estimator 702 calculates the vehicle speed estimate V^ in relation to the left rear wheel rotation speed ω wrl Let us assume that.

[0096] In step S1205, the vehicle speed estimator 702 calculates the vehicle speed estimate V^ in relation to the right rear wheel rotation speed ω wrr Let us assume that.

[0097] In step S1203, the right rear wheel rotation speed ω wrr is the left rear wheel rotation speed ω wrl If so, the process proceeds to step S1206. wrr is the left rear wheel rotation speed ω wrl If it is less than that, proceed to step S1207.

[0098] In step S1206, the vehicle speed estimator 702 calculates the vehicle speed estimate V^ in relation to the right rear wheel rotation speed ω wrr Let us assume that.

[0099] In step S1207, the vehicle speed estimator 702 calculates the vehicle speed estimate V^ in relation to the left rear wheel rotation speed ω wrl Let us assume that.

[0100] Returning to FIG. 7, the front slip rotation speed control calculation unit 703 calculates the vehicle speed estimation value V^ calculated by the vehicle speed estimation unit 702 and the rotation angular speed ω of the front motor 21. mf For example, the front slip rotation speed control calculation unit 703 detects the slip state based on the vehicle speed estimate V^ and the rotation angular speed ω of the front motor 21. mf When the difference value becomes equal to or exceeds a predetermined value, it is possible to determine that the front motor 21 is in a slip state. mf The front slip rotation speed control torque T mf_slip * In this way, when slip is detected, the front slip rotation speed control calculation section 703 executes motor rotation speed control for making the motor rotation speed follow the target motor rotation speed.

[0101] When slip is not detected, the front slip rotation speed control calculation unit 703 calculates the front target torque command value T mf * Front slip rotation speed control torque Tmf_slip * Set to.

[0102] The target rotational angular velocity can be set to an angular velocity value equivalent to a rotation speed that causes the front wheels 22 to slip at a predetermined slip ratio with respect to the estimated vehicle speed V^. For example, the target rotational angular velocity can be set to be the estimated vehicle speed V^+α (e.g., about 3 to 5 km / h).

[0103] Generally, a vehicle moves forward by obtaining a driving force from the road surface when the tires are in contact with the road surface. In this case, it is known that a larger driving force is obtained from the road surface when the driving wheels are allowed to slip to a certain degree relative to the vehicle speed. Therefore, for the driving wheels on which the slip rotational speed control is executed, it is preferable to set the target rotational angular velocity to the vehicle speed estimate value V^+α assuming a certain degree of slipping, instead of a value according to the vehicle speed estimate value V^. In this way, the slip rotational speed control is executed to control the actual rotational speed of the driving wheels to a rotational speed command value that provides the maximum driving force obtained from the road surface.

[0104] Returning to FIG. 6, the rear slip suppression calculation unit 602 calculates the front final torque command value T mf_f * and rear final torque command value T mr_f * and the left front wheel rotation speed ω wfl and the right front wheel rotation speed ω wfr and the angular velocity ω of the rear motor 31 mr and the front target torque command value T mf * and the rear target torque command value T mr * Based on the rear slip rotation speed control torque T mr_slip * and rear torque limit value T mr_limit * The rear slip rotation speed control torque T mr_slip * is a value used when slip rotation speed control is executed for the rear wheels 32. Also, the rear torque limit value T mr_limit *are values ​​used when slip rotation speed control is not performed for the rear wheels 32 (i.e., when torque limit control is performed for the rear wheels 32). mr_slip * and rear torque limit value T mr_limit * The calculation process will be described in detail with reference to FIG.

[0105] [Example of rear slip suppression calculation processing] 13 is a block diagram showing an example of a functional configuration of the rear slip suppression calculation unit 602. Specifically, the rear slip suppression calculation unit 602 includes a rear torque limit calculation unit 1301, a vehicle speed estimation unit 1302, and a rear slip rotation speed control calculation unit 1303.

[0106] The rear torque limit calculation unit 1301 calculates the angular velocity ω mf and the rear target torque command value T mr * and the front final torque command value T mf_f * and rear final torque command value T mr_f * Based on this, the rear torque limit value T mr_limit * Calculate the rear torque limit value T mr_limit * The calculation process will be described in detail with reference to FIG.

[0107] [Example of rear torque limit calculation section configuration] 14 is a block diagram showing an example of a functional configuration of the rear torque limit calculation section 1301. Specifically, the rear torque limit calculation section 1301 includes a disturbance estimation calculation section 1401, a limit torque calculation section 1402, and a torque limit section 1403.

[0108] The disturbance estimation calculation unit 1401 calculates the rear final torque command value T mr_f * and the front final torque command value T mf_f * and the angular velocity ω of the rear motor 31 mfBased on this, the estimated disturbance torque acting on the vehicle body (disturbance torque estimate) T^ dist This disturbance torque estimate T^ is calculated. dist The calculation process will be described in detail with reference to FIG.

[0109] [Example of configuration of disturbance estimation calculation section] 15 is a block diagram showing an example of a functional configuration of the disturbance estimation calculation unit 1401. Specifically, the disturbance estimation calculation unit 1401 includes a first motor torque estimated value calculation unit 1501, a multiplication unit 1502, a final total torque command value calculation unit 1503, a second motor torque estimated value calculation unit 1504, and a disturbance torque estimated value calculation unit 1505.

[0110] The first motor torque estimate calculation unit 1501 calculates the rear motor torque T mr and the rotational angular velocity ω of the rear motor 31. mr Transfer characteristics of model G pr H(s) / G using a low-pass filter H(s) whose order is equal to or greater than the difference between the denominator order and the numerator order of (s) pr At (s), the rotational angular velocity ω of the rear motor 31 mr That is, the first motor torque estimate value is calculated based on the rotational angular velocity ω mr is a motor torque estimate based on

[0111] Here, G pr (s) indicates the transmission characteristics from motor torque to rotational speed. Therefore, 1 / G pr (s) to obtain the rotational angular velocity ω mr to rear motor torque T mr In addition, when the electric vehicle 10 actually slips while traveling on a low μ road, the amount of this slip can be estimated as the disturbance torque.

[0112] The multiplication unit 1502 multiplies the front final torque command value T mf_f *The unit conversion coefficient is used to calculate the value. Here, the unit conversion coefficient is the front overall gear ratio N f , Rear overall gear ratio N r , front tire rolling radius r f , rear tire rolling radius r r Here is an example using

[0113] The final total torque command value calculation unit 1503 multiplies the value calculated by the multiplication unit 1502 (front final torque command value T mf_f * multiplied by the unit conversion coefficient) and the rear final torque command value T mr_f * The final total torque command value is calculated by adding the above.

[0114] The second motor torque estimate calculation unit 1504 filters the final total torque command value calculated by the final total torque command value calculation unit 1503 using a low-pass filter H(s) to calculate a second motor torque estimate. That is, the second motor torque estimate is calculated based on the front final torque command value T mf_f * and rear final torque command value T mr_f * is a motor torque estimate based on

[0115] The disturbance torque estimated value calculation unit 1505 calculates the disturbance torque estimated value T^ by subtracting the first motor torque estimated value calculated by the first motor torque estimated value calculation unit 1501 from the second motor torque estimated value calculated by the second motor torque estimated value calculation unit 1504. dist Calculate.

[0116] Here, when slip rotation speed control is executed for the front wheels 22, the torque of the rear wheels 32 is limited and the amount of slip is also reduced. In this case, the angular velocity (rotational angular velocity ω mr ) based on the external disturbance acting on the body of the electric vehicle 10, it is possible to accurately estimate the external disturbance acting on the vehicle body even on a low μ road.

[0117] Returning to FIG. 14, the limit torque calculation unit 1402 calculates the front final torque command value T mf_f * and the estimated disturbance torque T^ dist Based on the limit torque T lim The calculation process of this limit torque will be described in detail with reference to FIG.

[0118] [Example of limit torque calculation section configuration] 16 is a block diagram showing an example of a functional configuration of the limit torque calculation unit 1402. Specifically, the limit torque calculation unit 1402 includes an adder 1601.

[0119] The adder 1601 calculates the front final torque command value T mf_f * and the estimated disturbance torque T^ dist Adding these together, the limit torque T lim The disturbance torque estimate T^ is calculated. dist When the electric vehicle 10 is slipping, the limit torque T lim is the front final torque command value T mf_f * is lower than

[0120] Returning to FIG. 14, the torque limiting unit 1403 determines the rear target torque command value T mr * and limit torque T lim Based on this, the rear torque limit value T mr_limit * The calculation process of the rear torque limit value will be described in detail with reference to FIG.

[0121] [Example of torque limiting section operation] FIG. 17 is a flowchart showing an example of a calculation process of the front torque limit value by the torque limiting unit 1403.

[0122] In step S1701, the torque limiting unit 1403 calculates the rear target torque command value Tmr * That is, the sign of the rear target torque command value T mr * It is determined whether the rear target torque command value T mr * The sign of is positive, or the rear target torque command value T mr * If it is 0, the process proceeds to step S1702, and if its sign is negative, the process proceeds to step S1703.

[0123] In steps S1702 and S1703, the torque limiting unit 1403 calculates the rear target torque command value T mr * and limit torque T lim In other words, the magnitude relationship between the rear target torque command value T mr * ≧Limit torque T lim In step S1702, it is determined whether the rear target torque command value T mr * is the limit torque T lim If the target rear torque command value T mr * is the limit torque T lim If it is less than that, proceed to step S1705.

[0124] In step S1704, the torque limiting unit 1403 calculates the rear torque limiting value T mr_limit * Limit torque T lim Set to.

[0125] In step S1705, the torque limiting unit 1403 calculates the rear torque limit value T mr_limit * The rear target torque command value T mr * In this manner, in this embodiment, the rear target torque command value T mr * If is equal to or greater than 0, the rear torque limit value T mr_limit * The upper limit of the torque T limIn addition, the front final torque command value T mf_f * and the estimated disturbance torque T^ dist Based on this, the rear final torque command value T mr_f * By limiting the upper limit, it is possible to suppress spinning of the rear wheels 32 due to an excessive power running torque.

[0126] In step S1703, the rear target torque command value T mr * is the limit torque T lim If the target rear torque command value T mr * is the limit torque T lim If it is less than that, proceed to step S1707.

[0127] In step S1706, the torque limiting unit 1403 calculates the rear torque limiting value T mr_limit * The rear target torque command value T mr * Set to.

[0128] In step S1707, the torque limiting unit 1403 calculates the rear torque limiting value T mr_limit * Limit torque T lim In this manner, in this embodiment, the rear target torque command value T mr * If is negative, the rear torque limit value T mr_limit * The lower limit of the torque T lim In addition, the front final torque command value T mf_f * and the estimated disturbance torque T^ dist Based on this, the rear final torque command value T mr_f * By restricting the lower limit, it is possible to suppress spinning of the rear wheels 32 due to excessive regenerative torque.

[0129] In the case of an electric vehicle, the motor can also be used for regenerative deceleration. However, if the electric vehicle is on a low μ road during regeneration, the drive wheels may be locked. Therefore, in this embodiment, in order to prevent the drive wheels from being locked during regeneration, the lower limit of the final torque command value for the drive wheels that are not subjected to slip rotation speed control is set to a limit torque T lim This limits the regenerative torque to reduce it.

[0130] In this embodiment, the limit torque T lim In other words, it is possible to appropriately limit the upper and lower limits of the motor torque command value of the drive wheels for which the slip rotation speed control is not executed, depending on the running state of the electric vehicle 10.

[0131] 9 and 15, the rotation state of the motor without the slip rotation speed control (rotational angular velocity ω mf Or ω mr ) and the control torque (front final torque command value T mf_f * and rear final torque command value T mr_f * ) it is possible to estimate the disturbance. Here, the final torque of the motor not executing the slip rotation speed control is limited by the sum of the final torque of the motor executing the slip rotation speed control and the disturbance torque, as shown in Figs. 10 and 16. In other words, when a slip state is estimated, the final torque of the drive wheel executing the slip rotation speed control is subtracted by the slip amount from the final torque of the drive wheel, and this torque is set as the final torque of the other drive wheels, so that the final torque of the other drive wheels can be set to a torque that does not slip. Therefore, slip of the drive wheels not executing the slip rotation speed control is suppressed.

[0132] Returning to FIG. 13, the vehicle speed estimator 1302 estimates the front target torque command value T mf * and the right front wheel rotation speed ω wfr and the left front wheel rotation speed ω wflThe process of calculating the estimated vehicle speed V^ will be described in detail with reference to FIG.

[0133] [Example of vehicle speed estimation unit operation] FIG. 18 is a flowchart showing an example of a calculation process of the vehicle speed estimation unit 1302 for the vehicle speed estimated value.

[0134] In step S1801, the vehicle speed estimator 1302 calculates the front target torque command value T mf * The sign of the front target torque command value T mf * It is determined whether the front target torque command value T mf * The sign of is positive, or the front target torque command value T mf * If it is 0, the process proceeds to step S1802, and if its sign is negative, the process proceeds to step S1803.

[0135] In steps S1802 and S1803, the vehicle speed estimator 1302 estimates the right front wheel rotation speed ω wfr and the left front wheel rotation speed ω wfl That is, the right front wheel rotation speed ω wfr ≧ Left front wheel rotation speed ω wfl In step S1802, it is determined whether the right front wheel rotation speed ω wfr is the left front wheel rotation speed ω wfl If so, the process proceeds to step S1804. wfr is the left front wheel rotation speed ω wfl If it is less than that, proceed to step S1805.

[0136] In step S1804, the vehicle speed estimator 1302 calculates the vehicle speed estimate V^ in relation to the left front wheel rotation speed ω wfl Let us assume that.

[0137] In step S1805, the vehicle speed estimator 1302 calculates the vehicle speed estimate V^ in relation to the right front wheel rotation speed ω wfr Let us assume that.

[0138] In step S1803, the right front wheel rotation speed ω wfr is the left front wheel rotation speed ω wfl If so, the process proceeds to step S1806. wfr is the left front wheel rotation speed ω wfl If it is less than that, proceed to step S1807.

[0139] In step S1806, the vehicle speed estimator 1302 calculates the vehicle speed estimate V^ in relation to the right front wheel rotation speed ω wfr Let us assume that.

[0140] In step S1807, the vehicle speed estimator 1302 calculates the vehicle speed estimate V^ in relation to the left front wheel rotation speed ω wfl Let us assume that.

[0141] As described above, the final torque of the drive wheel that does not execute the slip rotation speed control is determined by subtracting the disturbance amount (the slip amount of the drive wheel on a low μ road) estimated for the drive wheel that does not execute the slip rotation speed control from the final torque of the drive wheel that executes the slip rotation speed control. That is, the slip amount of the drive wheel that does not execute the slip rotation speed control is suppressed to be lower than the slip amount of the drive wheel that executes the slip rotation speed control. Also, the drive wheel speed of the drive wheel that does not execute the slip rotation speed control is closer to the vehicle body speed than the drive wheel speed of the drive wheel that executes the slip rotation speed control. Therefore, in this embodiment, the drive wheel speed of the drive wheel that does not execute the slip rotation speed control is estimated and used as the vehicle body speed. In this way, the drive wheel speed of the drive wheel that does not execute the slip rotation speed control is suppressed to be low, so it can be treated as an estimated value of the vehicle body used in the slip rotation speed control.

[0142] Furthermore, during acceleration, the rotation speed of the slipping wheel is assumed to be faster, so the rotation speed of the slower wheel is estimated as the estimated vehicle speed V^. On the other hand, during regeneration, the rotation speed of the slipping wheel is assumed to be slower, so the rotation speed of the faster wheel is estimated as the estimated vehicle speed V^. This makes it possible to obtain an appropriate estimated vehicle speed V^ during both acceleration and regeneration, and makes it unnecessary to additionally implement a sensor (e.g., a GPS accelerometer) for obtaining vehicle speed.

[0143] Returning to FIG. 13, the rear slip rotation speed control calculation unit 1303 calculates the vehicle speed estimation value V^ calculated by the vehicle speed estimation unit 1302 and the rotational angular velocity ω of the rear motor 31. mr For example, the rear slip rotation speed control calculation unit 1303 detects the slip state based on the vehicle speed estimation value V^ and the rotation angular velocity ω of the rear motor 31. mr When the difference value becomes equal to or greater than a predetermined value, it is possible to determine that the vehicle is in a slip state. When the rear slip rotation speed control calculation unit 1303 detects a slip, it calculates the rotation angular velocity ω mr The rear slip rotation speed control torque T mr_slip * In this way, when slip is detected, rear slip rotation speed control calculation section 1303 executes motor rotation speed control for making the motor rotation speed follow the target motor rotation speed.

[0144] In addition, when slip is not detected, the rear slip rotation speed control calculation unit 1303 calculates the rear target torque command value T mr * Rear slip speed control torque T mr_slip * Set to.

[0145] The target rotational angular velocity can be set to an angular velocity value equivalent to a rotation speed that causes the rear wheels 32 to slip at a predetermined slip ratio with respect to the estimated vehicle speed V^. For example, the target rotational angular velocity can be set to be the estimated vehicle speed V^+α (e.g., about 3 to 5 km / h).

[0146] [Example of operation of ground load estimation calculation unit] Returning to FIG. 6, the ground load estimation calculation unit 603 calculates the front ground load w based on the vehicle longitudinal acceleration a obtained from the acceleration sensor (G sensor). f And rear ground load w r Specifically, the ground load estimation calculation unit 603 estimates the front ground load w f And rear ground load w r It is estimated that:

[0147]

number

[0148] W: Weight of vehicle [N] L: Wheelbase [m] l f :Distance from center of gravity to front wheel [m] l r :Distance from center of gravity to rear wheel [m] h: Height from the ground to the center of gravity [m] g: Gravitational acceleration [m / s 2 ]

[0149] For example, when the acceleration of the electric vehicle 10 increases, the vehicle longitudinal acceleration a becomes a positive value, so that the front ground load w f becomes smaller, and the rear ground load w r For example, when the accelerator pedal is depressed in a stopped electric vehicle 10, a load is applied to the rear of the electric vehicle 10. On the other hand, when the electric vehicle 10 decelerates, the vehicle longitudinal acceleration a becomes a negative value, and the front ground load w f becomes larger, and the rear ground load w rFor example, when the brake pedal is depressed on the electric vehicle 10 while it is moving, a load is applied to the front of the electric vehicle 10.

[0150] Here, the driving force of the road surface is calculated by the calculation value (e.g., multiplication value) of the road surface μ and the ground load. Therefore, the larger the ground load, the larger the driving force obtained. Therefore, since the driving force is larger for the driving wheel with the larger ground load, slip rotation speed control is executed for the driving wheel with the larger ground load.

[0151] The final torque command value calculation unit 604 calculates the front / rear driving force distribution gain K f And the front ground load w f And rear ground load w r and front slip rotation speed control torque T mf_slip * and the front torque limit value T mf_limit * and rear slip rotation speed control torque T mr_slip * and rear torque limit value T mr_limit * Based on this, the front final torque command value T mf_f * and rear final torque command value T mr_f * The front final torque command value T mf_f * and rear final torque command value T mr_f * The calculation process will be described in detail with reference to FIG.

[0152] [Example of operation of the final torque command value calculation unit] FIG. 19 is a flowchart showing an example of a calculation process of the final torque command value by the final torque command value calculation unit 604.

[0153] In step S1901, the final torque command value calculation unit 604 calculates the front driving force distribution K f (Front and rear driving force distribution gain K f ) and rear drive force distribution 1-K f Absolute value of difference with |2Kf Determine whether or not -1| is greater than a given value X. Absolute value |2K f If |-1| is greater than the predetermined value X, the process proceeds to step S1902. f If -1| is equal to or less than the predetermined value X, the process proceeds to step S1903. Here, the predetermined value X is 0 or a positive value close to 0. In this embodiment, an example is shown in which X=0. In this manner, in the determination process of step S1901, it is determined whether or not there is a difference in the driving force distribution (torque distribution) between the front and rear (i.e., whether or not it is substantially 1:1).

[0154] In step S1902, the final torque command value calculation unit 604 calculates the front driving force distribution K f and rear drive force distribution 1-K f Compare the size of the front drive force distribution K f Rear drive force distribution 1-K f If it is greater than , the process proceeds to step S1904. f Rear drive force distribution 1-K f If it is equal to or less than this, the process proceeds to step S1906.

[0155] In step S1904, the final torque command value calculation unit 604 calculates the front final torque command value T mf_f * Front slip rotation speed control torque T mf_slip * Set to.

[0156] In step S1905, the final torque command value calculation unit 604 calculates the rear final torque command value T mr_f * The rear torque limit value T mr_limit * Set to.

[0157] In step S1906, the final torque command value calculation unit 604 calculates the front final torque command value T mf_f * The front torque limit value T mf_limit * Set to.

[0158] In step S1907, the final torque command value calculation unit 604 calculates the rear final torque command value T mr_f * Rear slip speed control torque T mr_slip * Set to.

[0159] In step S1903, the final torque command value calculation unit 604 calculates the front ground load w f And rear ground load w r Compare the size of the front ground load w f is the rear ground load w r If it is equal to or greater than this, the process proceeds to step S1908. f is the rear ground load w r If it is smaller, the process proceeds to step S1910.

[0160] In step S1908, the final torque command value calculation unit 604 calculates the front final torque command value T mf_f * Front slip rotation speed control torque T mf_slip * Set to.

[0161] In step S1909, the final torque command value calculation unit 604 calculates the rear final torque command value T mr_f * The rear torque limit value T mr_limit * Set to.

[0162] In step S1910, the final torque command value calculation unit 604 calculates the front final torque command value T mf_f * The front torque limit value T mf_limit * Set to.

[0163] In step S1911, the final torque command value calculation unit 604 calculates the rear final torque command value T mr_f * Rear slip speed control torque Tmr_slip * Set to.

[0164] Here, if the drive wheels for which the slip rotation speed control is performed are fixed to either the front wheels 22 or the rear wheels 32, there is a risk that the acceleration or deceleration according to the tire limit cannot be obtained because the load transfer of the electric vehicle 10 is not taken into consideration. Therefore, in this embodiment, the drive wheels for which the slip rotation speed control is performed are switched according to the driving scene of the electric vehicle 10. Specifically, the torque distribution ratio of the front motor 21 and the rear motor 31 is changed sequentially according to the driving scene of the electric vehicle 10, so it is possible to switch the drive wheels for which the slip rotation speed control is performed based on the torque distribution ratio.

[0165] For example, as shown by the determination processes of steps S1901 and S1902, when the torque distribution ratio of the front motor 21 is greater than that of the rear motor 31, the drive wheels on which the slip rotation speed control is performed are switched to the front wheels 22. On the other hand, when the torque distribution ratio of the rear motor 31 is greater than that of the front motor 21, the drive wheels on which the slip rotation speed control is performed are switched to the rear wheels 32.

[0166] Also, for example, as shown in the determination processing of steps S1901 and S1903, even when the torque distribution ratio of the front motor 21 and the rear motor 31 is the same or approximately the same, it is possible to switch the drive wheels for which slip rotation speed control is performed based on the driving scene of the electric vehicle 10. For example, the front ground load w f and rear ground load w r Since the front load w f and rear ground load w r Based on this, it is possible to determine the drive wheels for which slip rotation speed control is to be performed.

[0167] For example, when the electric vehicle 10 is traveling uphill, the rear ground load w r is the front ground load w fTherefore, the driving wheels for which the slip rotation speed control is performed are switched to the rear wheels 32. On the other hand, when the electric vehicle 10 is traveling downhill, the front ground load w f is the rear ground load w r Since the slip rotation speed control is performed on the front wheels 22, the driving wheels 22 are switched to the front wheels 22.

[0168] In addition, for example, when the electric vehicle 10 is traveling on a flat road, the front ground load w f and rear ground load w r For example, when the electric vehicle 10 is accelerating on a flat road, the rear ground load w r is the front ground load w f Therefore, the driving wheels for which the slip rotation speed control is performed are switched to the rear wheels 32. On the other hand, when the electric vehicle 10 is decelerating on a flat road, the front ground load w f is the rear ground load w r Since the slip rotation speed control is performed on the front wheels 22, the driving wheels 22 are switched to the front wheels 22.

[0169] In addition, for example, when the electric vehicle 10 is turning on a flat road, the front ground load w f and rear ground load w r When the electric vehicle 10 is turning on a flat road, the relationship between the front ground load w f and rear ground load w r It is possible to determine which drive wheels should undergo slip rotation speed control depending on the magnitude relationship between the torque saturation torque and the torque limit torque.

[0170] In this way, the ground contact load estimation calculation unit 603 calculates a parameter (front ground contact load w f and rear ground load w r) is acquired. This parameter indicates the magnitude relationship between the ground loads of the front wheels 22 and the rear wheels 32, and is a parameter that suggests the driving scene of the electric vehicle 10. Then, the final torque command value calculation unit 604 can determine the drive wheels for which slip rotation speed control is to be executed based on the parameter.

[0171] In this embodiment, the front ground load wf and the rear ground load wr are estimated using the vehicle longitudinal acceleration a acquired by the acceleration sensor. However, it is also possible to estimate the front ground load wf and the rear ground load wr depending on the driving conditions of the electric vehicle 10. As described above, when the electric vehicle 10 is driving uphill or downhill, the rear ground load w r and front ground load w f In addition, as described above, when the electric vehicle 10 is traveling on a flat road, the rear ground load w r and front ground load w f In this way, the ground contact loads of the front wheels 22 and the rear wheels 32 can be estimated based on at least parameters that are correlated with the longitudinal acceleration of the electric vehicle 10, gradients, etc. This makes it possible to estimate the ground contact loads without the need for additional sensors.

[0172] [First Operation Example of the Present Embodiment] First, the torque distribution calculation unit 40 (see FIG. 4) calculates K f = 0.6 (driving force distribution ratio 60:40) is shown below.

[0173] [Example of slip control during acceleration] Fig. 20 is a time chart showing the transition of each value related to the electric vehicle 10 when the slip suppression calculation process (see Fig. 2) is executed during acceleration of the electric vehicle 10. In each of the graphs shown in Fig. 20(A) to (C), the horizontal axis indicates the time axis.

[0174] Fig. 20(A) is a time chart showing the transition of the vehicle speed of the electric vehicle 10 and the drive wheel speeds of the front wheels 22 and rear wheels 32. The vertical axis in Fig. 20(A) represents speed. A dotted line L1 represents the vehicle speed of the electric vehicle 10. A dotted line L2 represents the drive wheel speed of the front wheels 22. A solid line L3 represents the drive wheel speed of the rear wheels 32.

[0175] FIG. 20B is a time chart showing the transition of the target torque command value and the final torque command value for the front wheels 22 and the rear wheels 32. The vertical axis shown in FIG. 20B indicates the torque command value. The dotted line L11 indicates the front target torque command value T mf * The dotted line L12 indicates the rear target torque command value T mr * That is, the dotted lines L11 and L12 indicate the torque required by the driver when the driver depresses the accelerator pedal. f = 0.6, the front target torque command value T mf * is the rear target torque command value T mr * The dotted line L13 is the front final torque command value T mf_f * The solid line L14 indicates the rear final torque command value T mr_f * Here, the front target torque command value T mf * The value of this is the front final torque command value T mf_f * The rear target torque command value T mr * The value of this is the rear final torque command value T mr_f * If this is the case, the motor speed may increase in both the front and rear, and the motor rotation speed may deviate from the vehicle speed and diverge. For this reason, the torque is reduced in both the front and rear to reduce the front final torque command value T mf_f * , rear final torque command value T mr_f * Set.

[0176] Fig. 20(C) is a time chart showing a transition of the longitudinal acceleration L21 of the electric vehicle 10. The vertical axis shown in Fig. 20(C) represents the longitudinal acceleration.

[0177] In FIG. 20, at time t1, the front target torque command value T mf * and the rear target torque command value T mr * This shows an example in which a powering torque is applied to the motor and acceleration is started.

[0178] FIG. 20 also shows an example in which a slip state is detected in the front wheels 22 at time t2. Here, when the electric vehicle 10 is started on a low μ road by stepping on the accelerator pedal from a stopped state, both the front and rear wheels often slip. In the example shown in FIG. 20, the driving force distribution ratio is 60:40, so slip rotation speed control that adjusts the slip ratio to an appropriate value is executed on the front wheels 22. Therefore, the driving wheel speed (dotted line L2) increases while slipping relative to the vehicle speed (dotted line L1) of the electric vehicle 10. Also, focusing on torque, when the electric vehicle 10 is started on a low μ road by stepping on the accelerator pedal from a stopped state, slip of the front wheels 22 is detected, so that torque reduction is executed as shown by the dotted line L13 and solid line L14, and the vehicle speed increases while maintaining the torque reduction.

[0179] In this way, the drive wheel speed (dotted line L2) of the front wheels 22 increases while the slip ratio is maintained at an appropriate value. On the other hand, the rear wheels 32 are controlled by the rear slip suppression calculation unit 602 and the final torque command value calculation unit 604 (see FIG. 6) so as not to slip, and therefore the drive wheel speed (solid line L3) and the vehicle speed (dotted line L1) increase in a state closer to each other than the drive wheel speed (dotted line L2) of the front wheels 22. In this way, since the drive wheel speed (solid line L3) and the vehicle speed (dotted line L1) are close to each other, it becomes possible to use the drive wheel speed (solid line L3) of the rear wheels 32 as the vehicle speed. Then, by using the drive wheel speed (solid line L3) of the rear wheels 32 as the vehicle speed for the slip rotational speed control of the front wheels 22, it becomes possible to execute appropriate slip suppression control. That is, it becomes possible to use the rear rotational speed as the vehicle speed while preventing slip as much as possible for the rear wheels 32. This makes it possible to accelerate appropriately while traveling even on a road surface on which the front wheels 22 and rear wheels 32 may slip.

[0180] In this way, by executing the slip rotation speed control to make the front motor rotation speed follow the front target motor rotation speed, the front final torque command value T mf_f * is the front target torque command value T mf * The upper limit is set to suppress slippage.

[0181] On the other hand, the rear final torque command value T mr_f * is the rear target torque command value T mr * For the front final torque command value T mf_f * and the estimated disturbance torque T dist The upper limit is limited by the sum of the rear wheels 32 and the slip is suppressed. In addition, since the slip amount of the drive wheel speed of the rear wheels 32 is suppressed to be low, it can be treated as a vehicle speed estimate used in the slip rotation speed control of the front wheels 22. Therefore, the front target motor rotation speed can be calculated based on the drive wheel speed of the rear wheels 32.

[0182] FIG. 20 also shows an example of a case where the drive wheel speeds of the front wheels 22 and the rear wheels 32 are prevented from spinning at time t3, and appropriate acceleration is possible.

[0183] [Example of slip control during deceleration] Fig. 21 is a time chart showing the transition of each value related to the electric vehicle 10 when the slip suppression calculation process (see Fig. 2) is executed during deceleration of the electric vehicle 10. In each of the graphs shown in Fig. 21(A) to (C), the horizontal axis represents the time axis.

[0184] Fig. 21(A) is a time chart showing the transition of the vehicle speed of the electric vehicle 10 and the drive wheel speeds of the front wheels 22 and rear wheels 32. The vertical axis shown in Fig. 21(A) represents speed. A dotted line L31 represents the vehicle speed of the electric vehicle 10. A dotted line L32 represents the drive wheel speed of the front wheels 22. A solid line L33 represents the drive wheel speed of the rear wheels 32.

[0185] FIG. 21B is a time chart showing the transition of the target torque command value and the final torque command value for the front wheels 22 and the rear wheels 32. The vertical axis shown in FIG. 21B indicates the torque command value. A dotted line L41 indicates the front target torque command value T mf * The dotted line L42 indicates the rear target torque command value T mr * That is, the dotted lines L41 and L42 indicate the torque required by the driver due to the operation of the accelerator pedal. f = 0.6, the front target torque command value T mf * is the rear target torque command value T mr * The dotted line L43 indicates the front final torque command value T mf_f * The solid line L44 indicates the rear final torque command value T mr_f * Shows.

[0186] Fig. 21(C) is a time chart showing a transition of the longitudinal acceleration L51 of the electric vehicle 10. The vertical axis shown in Fig. 21(C) represents the longitudinal acceleration.

[0187] In FIG. 21, at time t11, the front target torque command value T mf * and the rear target torque command value T mr * This shows an example in which regenerative torque is applied to the motor and deceleration begins.

[0188] FIG. 21 also shows an example in which a locked state is detected in the front wheels 22 at time t12. Here, when the electric vehicle 10 travels in a decelerating state on a low μ road, it is considered that both the front and rear wheels will be locked. In the example shown in FIG. 21, the driving force distribution ratio is 60:40, so slip rotation speed control that adjusts the slip ratio to an appropriate value is executed on the front wheels 22. Therefore, the driving wheel speed (dotted line L32) decreases while slipping relative to the vehicle speed (dotted line L31) of the electric vehicle 10. Also, focusing on torque, when the electric vehicle 10 travels in a decelerating state on a low μ road, slip of the front wheels 22 is detected, so torque reduction is executed as shown by dotted line L43 and solid line L44, and the vehicle speed decreases while maintaining the torque reduction.

[0189] In this way, the drive wheel speed (dotted line L32) of the front wheels 22 decreases while the slip ratio is maintained at an appropriate value. On the other hand, the rear wheels 32 are controlled by the rear slip suppression calculation unit 602 and the final torque command value calculation unit 604 (see FIG. 6) not to lock, so that the drive wheel speed (solid line L33) and the vehicle speed (dotted line L31) decrease in a state closer to each other than the drive wheel speed (dotted line L32) of the front wheels 22. Since the drive wheel speed (solid line L33) and the vehicle speed (dotted line L31) are close to each other in this way, it becomes possible to use the drive wheel speed (solid line L33) of the rear wheels 32 as the vehicle speed. Then, by using the drive wheel speed (solid line L33) of the rear wheels 32 as the vehicle speed for the slip rotational speed control of the front wheels 22, it becomes possible to execute appropriate slip control. That is, it becomes possible to use the rear rotational speed as the vehicle speed by preventing the rear wheels 32 from locking as much as possible. This makes it possible to run while appropriately decelerating even on road surfaces where the front wheels 22 and rear wheels 32 may slip.

[0190] In this way, by executing the slip rotation speed control to make the front motor rotation speed follow the front target motor rotation speed, the front final torque command value T mf_f * is the front target torque command value T mf * The lower limit is set and locking is suppressed.

[0191] On the other hand, the rear final torque command value T mr_f * is the rear target torque command value T mr * For the front final torque command value T mf_f * and the estimated disturbance torque T dist The lower limit is set by the sum of and thus the lock is suppressed. In addition, since the slip amount of the drive wheel speed of the rear wheels 32 is suppressed to be low, it can be treated as a vehicle speed estimate used in the slip rotation speed control of the front wheels 22. Therefore, the front target motor rotation speed can be calculated based on the drive wheel speed of the rear wheels 32.

[0192] FIG. 21 also shows an example of a case where the drive wheel speeds of the front wheels 22 and the rear wheels 32 can be prevented from being locked at time t13 and appropriate deceleration can be performed.

[0193] [Second Example of Operation of the Present Embodiment] Next, the torque distribution calculation unit 40 (see FIG. 4) calculates K f = 0.5 (driving force distribution ratio 50:50) is shown below.

[0194] [Example of slip control during acceleration] Fig. 22 is a time chart showing the transition of each value related to the electric vehicle 10 when the slip suppression calculation process (see Fig. 2) is executed during acceleration of the electric vehicle 10. In each of the graphs shown in Fig. 22(A) to (D), the horizontal axis represents the time axis.

[0195] Fig. 22(A) is a time chart showing the transition of the vehicle speed of the electric vehicle 10 and the drive wheel speeds of the front wheels 22 and rear wheels 32. The vertical axis shown in Fig. 22(A) represents speed. A dotted line L61 represents the vehicle speed of the electric vehicle 10. A dotted line L62 represents the drive wheel speed of the front wheels 22. A solid line L63 represents the drive wheel speed of the rear wheels 32.

[0196] FIG. 22B is a time chart showing the transition of the target torque command value and the final torque command value for the front wheels 22 and the rear wheels 32. The vertical axis shown in FIG. 22B indicates the torque command value. A dotted line L71 indicates the front target torque command value T mf * The dotted line L72 indicates the rear target torque command value T mr * That is, the dotted lines L71 and L72 indicate the torque required by the driver when the driver depresses the accelerator pedal. f = 0.5, the front target torque command value T mf * , rear target torque command value T mr * The dotted line L73 indicates the front final torque command value T mf_f *The solid line L74 indicates the rear final torque command value T mr_f * Here, the front target torque command value T mf * The value of this is the front final torque command value T mf_f * The rear target torque command value T mr * The value of this is the rear final torque command value T mr_f * If this is the case, the motor speed may increase in both the front and rear, and the motor rotation speed may deviate from the vehicle speed and diverge. For this reason, the torque is reduced in both the front and rear to reduce the front final torque command value T mf_f * , rear final torque command value T mr_f * Set.

[0197] Fig. 22(C) is a time chart showing a transition of the longitudinal acceleration L81 of the electric vehicle 10. The vertical axis shown in Fig. 22(C) represents the longitudinal acceleration.

[0198] Fig. 22(D) is a time chart showing the transition of the ground load of the front wheels 22 and the rear wheels 32. The vertical axis shown in Fig. 22(D) shows the value of the ground load. The dotted line L91 shows the front ground load wf. The dotted line L92 shows the rear ground load wr.

[0199] In FIG. 22, at time t21, the front target torque command value T mf * and the rear target torque command value T mr * This shows an example in which a powering torque is applied to the motor and acceleration is started.

[0200] FIG. 22 also shows an example in which a slip state is detected in the rear wheel 32 at time t22. When the electric vehicle 10 is stopped on a low μ road and the accelerator pedal is depressed to start moving, both the front and rear wheels often slip. In the example shown in FIG. 22, the driving force distribution ratio is 50:50, so the wheel for which slip rotation speed control is executed is determined based on the magnitude of the ground contact load of the front wheels 22 and the rear wheels 32. Specifically, as shown in FIG. 22(D), from time t21 onwards, the rear ground contact load w r (Dotted line L92) is the front ground load w f (dotted line L91). Therefore, it is decided to execute slip rotation speed control for the rear wheels 32, which adjusts the slip ratio to an appropriate value. For this reason, the drive wheel speed (solid line L63) increases while slipping relative to the vehicle speed of the electric vehicle 10 (dotted line L61). Also, focusing on torque, when the accelerator pedal is depressed to start the electric vehicle 10 from a stopped state on a low μ road, slip of the rear wheels 32 is detected, and therefore, as shown by dotted line L73 and solid line L74, torque reduction is executed and the vehicle speed increases while maintaining the torque reduction.

[0201] In this way, the drive wheel speed (solid line L63) of the rear wheels 32 increases while the slip ratio is maintained at an appropriate value. On the other hand, the front wheels 22 are controlled by the front slip suppression calculation unit 601 and the final torque command value calculation unit 604 (see FIG. 6) so as not to slip, and therefore the drive wheel speed (dotted line L62) and the vehicle speed (dotted line L61) increase in a state closer to each other than the drive wheel speed (solid line L63) of the rear wheels 32. In this way, since the drive wheel speed (dotted line L62) and the vehicle speed (dotted line L61) are close to each other, it becomes possible to use the drive wheel speed (dotted line L62) of the front wheels 22 as the vehicle speed. Then, by using the drive wheel speed (dotted line L62) of the front wheels 22 as the vehicle speed for the slip rotational speed control of the rear wheels 32, it becomes possible to execute appropriate slip suppression control. That is, it becomes possible to use the rotational speed of the front wheels 22 as the vehicle speed while preventing the front wheels 22 from slipping as much as possible. This makes it possible to accelerate appropriately while traveling even on a road surface on which the front wheels 22 and rear wheels 32 may slip.

[0202] In this way, by executing the slip rotation speed control to make the rear motor rotation speed follow the rear target motor rotation speed, the rear final torque command value T mr_f * is the rear target torque command value T mr * The upper limit is set to suppress slippage.

[0203] On the other hand, the front final torque command value T mf_f * is the front target torque command value T mf * For the rear final torque command value T mr_f * and the estimated disturbance torque T dist The upper limit is limited by the sum of the above, and slip is suppressed. In addition, since the slip amount of the drive wheel speed of the front wheels 22 is suppressed to be low, it can be treated as a vehicle speed estimate used in the slip rotation speed control of the rear wheels 32. Therefore, the rear target motor rotation speed can be calculated based on the drive wheel speed of the front wheels 22.

[0204] FIG. 22 also shows an example of a case where the drive wheel speeds of the front wheels 22 and the rear wheels 32 are prevented from spinning at time t23, and appropriate acceleration is possible.

[0205] [Example of slip control during deceleration] Fig. 23 is a time chart showing the transition of each value related to the electric vehicle 10 when the slip suppression calculation process (see Fig. 2) is executed during deceleration of the electric vehicle 10. In each of the graphs shown in Fig. 23(A) to (D), the horizontal axis represents the time axis.

[0206] Fig. 23(A) is a time chart showing the transition of the vehicle speed of the electric vehicle 10 and the drive wheel speeds of the front wheels 22 and rear wheels 32. The vertical axis shown in Fig. 23(A) represents speed. A dotted line L101 represents the vehicle speed of the electric vehicle 10. A dotted line L102 represents the drive wheel speed of the front wheels 22. A solid line L103 represents the drive wheel speed of the rear wheels 32.

[0207] FIG. 23B is a time chart showing the transition of the target torque command value and the final torque command value for the front wheels 22 and the rear wheels 32. The vertical axis shown in FIG. 23B indicates the torque command value. The dotted line L111 indicates the front target torque command value T mf * The dotted line L112 indicates the rear target torque command value T mr * That is, the dotted lines L111 and L112 indicate the torque required by the driver due to the operation of the accelerator pedal. f = 0.5, the front target torque command value T mf * , rear target torque command value T mr * The dotted line L113 indicates the front final torque command value T mf_f * The solid line L114 indicates the rear final torque command value T mr_f * Shows.

[0208] Fig. 23(C) is a time chart showing a transition of the longitudinal acceleration L121 of the electric vehicle 10. The vertical axis shown in Fig. 23(C) represents the longitudinal acceleration.

[0209] FIG. 23(D) is a time chart showing the transition of the ground load of the front wheels 22 and the rear wheels 32. The vertical axis shown in FIG. 23(D) shows the value of the ground load. The dotted line L131 shows the front ground load w f The solid line L132 indicates the rear ground load w r Shows.

[0210] In FIG. 23, at time t31, the front target torque command value T mf * and the rear target torque command value T mr * This shows an example in which regenerative torque is applied to the motor and deceleration begins.

[0211] FIG. 23 also shows an example in which a locked state is detected in the front wheel 22 at time t32. Here, if the electric vehicle 10 travels on a low μ road while decelerating, it is conceivable that both the front and rear wheels will enter a locked state. In the example shown in FIG. 23, the driving force distribution ratio is 50:50, so the wheel for which slip rotation speed control is executed is determined based on the magnitude of the ground contact load of the front wheels 22 and the rear wheels 32. Specifically, as shown in FIG. 23(D), from time t31 onwards, the front ground contact load w f (Dotted line L131) is the rear ground load w r (solid line L132). Therefore, slip rotation speed control is executed on the front wheels 22 to adjust the slip ratio to an appropriate value. As a result, the drive wheel speed (dotted line L102, solid line L103) decreases while slipping relative to the vehicle speed of the electric vehicle 10 (dotted line L101). Also, focusing on torque, when the electric vehicle 10 travels in a decelerating state on a low μ road, slip of the rear wheels 32 is detected, and therefore, as shown by the dotted line L113 and solid line L114, torque reduction is executed and the vehicle speed decreases while maintaining the torque reduction.

[0212] In this way, the drive wheel speed (dotted line L102) of the front wheels 22 decreases while the slip ratio is maintained at an appropriate value. On the other hand, the rear wheels 32 are controlled by the rear slip suppression calculation unit 602 and the final torque command value calculation unit 604 (see FIG. 6) not to lock, so that the drive wheel speed (solid line L103) and the vehicle speed (dotted line L101) decrease in a state closer to each other than the drive wheel speed (dotted line L102) of the front wheels 22. Since the drive wheel speed (solid line L103) and the vehicle speed (dotted line L101) are close to each other in this way, it becomes possible to use the drive wheel speed (solid line L103) of the rear wheels 32 as the vehicle speed. Then, by using the drive wheel speed (solid line L103) of the rear wheels 32 as the vehicle speed for the slip rotational speed control of the front wheels 22, it becomes possible to execute appropriate slip control. That is, it becomes possible to use the rear rotational speed as the vehicle speed by preventing the rear wheels 32 from locking as much as possible. This makes it possible to run while appropriately decelerating even on road surfaces where the front wheels 22 and rear wheels 32 may slip.

[0213] In this way, by executing the slip rotation speed control to make the front motor rotation speed follow the front target motor rotation speed, the front final torque command value T mf_f * is the front target torque command value T mf * The lower limit is set and locking is suppressed.

[0214] On the other hand, the rear final torque command value T mr_f * is the rear target torque command value T mr * For the front final torque command value T mf_f * and the estimated disturbance torque T dist The lower limit is set by the sum of and thus the lock is suppressed. In addition, since the slip amount of the drive wheel speed of the rear wheels 32 is suppressed to be low, it can be treated as a vehicle speed estimate used in the slip rotation speed control of the front wheels 22. Therefore, the front target motor rotation speed can be calculated based on the drive wheel speed of the rear wheels 32.

[0215] FIG. 23 also shows an example of a case where the drive wheel speeds of the front wheels 22 and the rear wheels 32 can be prevented from being locked at time t33 and appropriate deceleration can be performed.

[0216] In this manner, in this embodiment, the drive wheels for which slip rotation speed control is executed are switched depending on the running conditions (for example, torque distribution ratio, ground load) of the electric vehicle 10. Specifically, the front slip suppression calculation unit 601 and the rear slip suppression calculation unit 602 each calculate the front / rear slip rotation speed control torque (T mf_slip * , T mr_slip * ) and front / rear torque limit values ​​(T mf_limit * , T mr_limit * Then, a final torque command value calculation unit 604 uses the torque distribution ratio and the ground loads of the front wheels 22 and the rear wheels 32 to switch the drive wheels for which slip rotation speed control and torque suppression control are to be executed.

[0217] In this embodiment, the switching control of the drive wheels for executing the slip rotation speed control and the torque suppression control is executed sequentially even during driving. Therefore, even if the driving state of the electric vehicle 10 changes (for example, when changing from an acceleration state to a deceleration state), it is possible to execute the switching control sequentially in response to the change.

[0218] In this way, the electric vehicle 10 is an electric vehicle that uses multiple motors (front motor 21, rear motor 31) as driving sources to drive the front wheels 22 and the rear wheels 32 independently. The electric vehicle 10 also includes a driver request torque calculation means (motor controller 14: basic target torque calculation unit) that calculates a driver request torque based on vehicle information such as a driver operation, a driving force distribution ratio setting means (torque distribution calculation unit 40) that sets a distribution ratio for distributing the driver request torque output from the multiple driving sources (front motor 21, rear motor 31) to the multiple driving sources, a motor torque command value calculation means (torque distribution calculation unit 40) that calculates a motor torque command value for each of the multiple driving sources, and a torque command acting on the vehicle body based on an angular velocity that is correlated with the motor torque command value and the rotational speed of the drive shaft. The system includes a disturbance torque estimation means (disturbance estimation calculation unit 801, 1401) for estimating disturbance, a means (front slip rotation speed control calculation unit 703, rear slip rotation speed control calculation unit 1303) for calculating a motor torque command value of a driving wheel for which slip rotation speed control is performed, and a control means (front torque limit calculation unit 701, rear torque limit calculation unit 1301, final torque command value calculation unit 604) for limiting the other motor torque command value (motor torque command value of a driving wheel not performing slip rotation speed control) based on the motor torque command value of the driving wheel for which slip rotation speed control is performed and the disturbance torque estimated value. The final torque command value calculation unit 604 switches the driving wheel for which slip rotation speed control is performed according to the torque distribution ratio (driving force distribution ratio) of multiple driving sources (front motor 21, rear motor 31).

[0219] [Examples of Effects of This Embodiment] Here, in the case of a two-wheel drive electric vehicle in which either the front or the rear is driven, it is possible to estimate the vehicle speed using the rotation speed of the non-slip driven wheel. However, in the case of a four-wheel drive electric vehicle 10 in which both the front and rear are driven, both the front and rear drive wheels may slip. For this reason, in the case of a four-wheel drive electric vehicle 10, it is difficult to obtain the vehicle speed as easily as in the case of a two-wheel drive electric vehicle. Therefore, it is conceivable to additionally mount an expensive vehicle speed meter such as a sensor capable of measuring the vehicle speed (e.g., a GPS speedometer) and execute slip rotation speed control based on the vehicle speed measured by these sensors. However, mounting these sensors increases the manufacturing cost of the electric vehicle, so it is important to suppress these manufacturing costs.

[0220] In this embodiment, the final torque command value of one of the driving wheels undergoing the slip rotation speed control and the disturbance torque estimate value T^ acting on the vehicle body according to the running resistance of the road surface are calculated. dist Based on the above, the final torque command value of the other drive wheel is limited. This makes it possible to reduce the slip amount of the drive wheel not subjected to slip rotation speed control, and to suppress the slip or lock of the drive wheel. Therefore, it is possible to estimate an appropriate vehicle speed using the wheel rotation speed of the drive wheel not subjected to slip rotation speed control, and it is possible to appropriately execute slip rotation speed control to suppress slip during start acceleration or deceleration of the electric vehicle 10 on a low μ road. In other words, even in a road surface state in which both the front wheels 22 and the rear wheels 32 of a four-wheel drive electric vehicle 10 in which both the front and rear wheels are driven simultaneously slip, it is possible to appropriately suppress slip by executing the slip suppression calculation process according to this embodiment. In addition, since the slip rotation speed control is performed using the rotation angular speed of the motor not subjected to slip rotation speed control as an input, it is not necessary to additionally install an expensive vehicle speed meter such as a sensor capable of measuring the vehicle speed, and it is possible to suppress the manufacturing cost of the electric vehicle 10.

[0221] [Configuration Example and Effects of This Embodiment] The control method for an electric vehicle 10 according to this embodiment is a control method for an electric vehicle including a front motor 21 (an example of a first drive motor) that drives front wheels 22 (an example of a first wheel), a rear motor 31 (an example of a second drive motor) that drives rear wheels 32 (an example of a second wheel), and a motor controller 14 (an example of a control device) that controls the operation of the front motor 21 and the rear motor 31. In step S203, the final torque command value calculation unit 604 (motor controller 14) uses the drive wheel speed of one of the front wheels 22 and the rear wheels 32 to execute slip rotation speed control of the other motor that drives the other drive wheel. In step S203, the disturbance estimation calculation unit 801 (motor controller 14) calculates a rear final torque command value T mr_f * (an example of the first torque command value) and the front final torque command value T mf_f * (An example of the second torque command value) and the rotational angular velocity ω of the front motor 21 mf (An example of the rotation state of one of the motors) based on the above, a disturbance torque estimate T^ relating to the disturbance acting on the electric vehicle 10 is calculated. dist In step S203, the disturbance estimation calculation unit 1401 (the motor controller 14) estimates the front final torque command value T mf_f * (an example of a first torque command value) and a rear final torque command value T mr_f * (An example of the second torque command value) and the rotational angular velocity ω of the rear motor 31 mr (An example of the rotation state of one of the motors) based on the above, a disturbance torque estimate T^ relating to the disturbance acting on the electric vehicle 10 is calculated. dist In step S203, the limit torque calculation unit 802 (motor controller 14) estimates the disturbance torque estimated value T^ estimated by the disturbance estimation calculation unit 801. dist and rear final torque command value T mr_f * Based on the limit torque T lim(an example of a torque limit value). In step S203, the limit torque calculation unit 1402 (motor controller 14) calculates the disturbance torque estimation value T^ estimated by the disturbance estimation calculation unit 1401. dist and the front final torque command value T mf_f * Based on the limit torque T lim In step S203, the torque limiting unit 803 (motor controller 14) calculates the limit torque T lim Based on this, the front target torque command value T mf * (An example of the target torque command value of one motor) is corrected to obtain the front torque limit value T mf_limit * In step S203, the torque limiting unit 1403 (motor controller 14) calculates the limit torque T lim Based on this, the rear target torque command value T mr * (An example of the target torque command value of one of the motors) is corrected to obtain the rear torque limit value T mr_limit * In steps S1901 and S1902, the final torque command value calculation unit 604 (motor controller 14) determines the other motor for executing the slip rotation speed control based on the torque distribution ratio (driving force distribution ratio) between the front motor 21 and the rear motor 31, which is set based on the driving force required by the electric vehicle 10. Note that the rotational angular velocity ω mf is an example of an angular velocity correlated with the rotational speed of the drive shaft of the front wheel 22, and the rotational angular velocity ω mr is an example of an angular velocity that is correlated with the rotational speed of the drive shaft of the rear wheel 32.

[0222] According to this configuration, the slip amount of one of the driving wheels can be reduced by limiting the motor torque command value of one of the motors based on the motor torque command of the other motor that is undergoing slip rotation speed control and an estimated value of disturbance torque acting on the vehicle body according to the running resistance of the road surface. Also, the one of the driving wheels (the driving wheel that is not subjected to slip rotation speed control) whose motor torque command value is limited is switched according to the torque distribution ratio (driving force distribution ratio). This makes it possible to suppress slippage and locking of one of the driving wheels. In other words, it is possible to excessively limit the motor torque command value of the other driving wheel that is not subjected to slip rotation speed control, thereby avoiding the occurrence of poor acceleration or deceleration. That is, it is possible to appropriately execute slip control that suppresses slip even in a state in which the front wheels 22 and the rear wheels 32 are driven.

[0223] In the control method for electric vehicle 10 according to this embodiment, in steps S1901 and S1902, if the absolute value of the difference in the torque distribution ratio is greater than a predetermined value, the final torque command value calculation unit 604 (motor controller 14) determines the motor with the relatively larger torque distribution ratio as the other motor.

[0224] According to this configuration, it is possible to execute slip rotation speed control for the motor (the other motor) with a relatively large torque distribution ratio, and to limit the motor torque command value for the motor (the one motor) with a relatively small torque distribution ratio, thereby making it possible to suppress the slip or lock of the drive wheels that are not executed with the slip rotation speed control.

[0225] In the control method for the electric vehicle 10 according to this embodiment, in steps S1901 and S1903, if the absolute value of the difference in the torque distribution ratio is equal to or less than a predetermined value, the final torque command value calculation unit 604 (motor controller 14) determines the other motor based on the driving forces transmitted to the road surface of the front wheels 22 and the rear wheels 32, which change depending on the driving scene of the electric vehicle 10.

[0226] According to this configuration, when the torque distribution ratio between the front wheels 22 and the rear wheels 32 is approximately the same (for example, 50:50), by switching the drive wheels that perform slip rotation speed control depending on the driving situation, it is possible to improve acceleration performance or deceleration performance while suppressing spinning or locking.

[0227] In the control method for electric vehicle 10 according to this embodiment, the drive forces transmitted to the road surface of each of the front wheels 22 and the rear wheels 32 correspond to the ground contact loads of each of the front wheels 22 and the rear wheels 32. The electric vehicle 10 includes a ground contact load estimation calculation unit 603. The ground contact load estimation calculation unit 603 is capable of estimating the ground contact loads of each of the front wheels 22 and the rear wheels 32.

[0228] According to this configuration, it is possible to determine the other motor for executing the slip rotation speed control in accordance with the magnitude relationship between the ground loads of the front wheels 22 and the rear wheels 32.

[0229] In the control method for the electric vehicle 10 according to this embodiment, in step S1903, if the ground load of the front wheels 22 is equal to or greater than the ground load of the rear wheels 32, the final torque command value calculation unit 604 (motor controller 14) determines the front motor 21 (an example of a first drive motor) as the other motor, and if the ground load of the front wheels 22 is smaller than the ground load of the rear wheels 32, the final torque command value calculation unit 604 (motor controller 14) determines the rear motor 31 (an example of a second drive motor) as the other motor.

[0230] With this configuration, it is possible to determine the other motor that performs slip rotation speed control depending on the magnitude relationship between the ground loads of the front wheels 22 and the rear wheels 32. Specifically, by performing slip rotation speed control on the drive wheel with the larger ground load, maximum acceleration or deceleration can be obtained, and slip control that suppresses slipping can be appropriately performed even when the front wheels 22 and the rear wheels 32 are in driving state.

[0231] The motor controller 14 (an example of a control device) is a control device for the electric vehicle 10 that controls the operation of the front motor 21 (an example of a first drive motor) that drives the front wheels 22 (an example of a first wheel) and the rear motor 31 (an example of a second drive motor) that drives the rear wheels 32 (an example of a second wheel). The motor controller 14 includes a front slip rotation speed control calculation unit 703 and a rear slip rotation speed control calculation unit 1303 (an example of a slip rotation speed control unit), a disturbance estimation calculation unit 801 and a disturbance estimation calculation unit 1401 (an example of a disturbance torque value estimation unit), a limit torque calculation unit 802 and a limit torque calculation unit 1402 (an example of a torque limit value calculation unit), a torque limit unit 803 and a torque limit unit 1403 (an example of a second torque command value setting unit), and a final torque command value calculation unit 604 (an example of a motor determination unit). The front slip rotation speed control calculation unit 703 executes slip rotation speed control of the front motor 21 (an example of the other motor) that drives the front wheels 22 (an example of the other drive wheel) using the drive wheel speed of the rear wheels 32 (an example of the one drive wheel speed). The rear slip rotation speed control calculation unit 1303 executes slip rotation speed control of the rear motor 31 (an example of the other motor) that drives the rear wheels 32 (an example of the other drive wheel) using the drive wheel speed of the front wheels 22 (an example of the one drive wheel speed). The disturbance estimation calculation unit 801 executes slip rotation speed control of the rear motor 31 (an example of the other motor) that drives the rear wheels 32 (an example of the other drive wheel) using the drive wheel speed of the front wheels 22 (an example of the one drive wheel speed). mr_f * (an example of a first torque command value), and a front final torque command value T mf_f * (an example of a second torque command value) and the rotational angular velocity ω of the front motor 21 (an example of one of the motors) mf (An example of the rotation state of one of the motors) based on the above, a disturbance torque estimate T^ relating to the disturbance acting on the electric vehicle 10 is calculated. dist The disturbance estimation calculation unit 1401 estimates a front final torque command value T mf_f * (an example of a first torque command value), and a rear final torque command value T mr_f *(an example of a second torque command value) and the rotational angular velocity ω of the rear motor 31 (an example of one of the motors) mr (An example of the rotation state of one of the motors) based on the above, a disturbance torque estimate T^ relating to the disturbance acting on the electric vehicle 10 is calculated. dist (an example of a disturbance torque value). The limit torque calculation unit 802 estimates the disturbance torque estimated value T^ estimated by the disturbance estimation calculation unit 801. dist and rear final torque command value T mr_f * Based on the limit torque T lim The limit torque calculation unit 1402 calculates the disturbance torque estimation value T^ (an example of a torque limit value). dist and the front final torque command value T mf_f * Based on the limit torque T lim (An example of a torque limit value) is calculated by the torque limit calculation unit 802. lim Based on this, the front target torque command value T mf * (An example of the target torque command value of one motor) is corrected to obtain the front torque limit value T mf_limit * The torque limiting unit 1403 sets the limit torque T lim Based on this, the rear target torque command value T mr * (An example of the target torque command value of one of the motors) is corrected to obtain the rear torque limit value T mr_limit * The final torque command value calculation unit 604 sets a second torque command value (second torque command value). The final torque command value calculation unit 604 determines the other motor for executing the slip rotation speed control based on the torque distribution ratio (driving force distribution ratio) between the front motor 21 and the rear motor 31 that is set based on the driving force required by the electric vehicle 10.

[0232] According to this configuration, the slip amount of one of the driving wheels can be reduced by limiting the motor torque command value of one of the motors based on the motor torque command of the other motor that is undergoing slip rotation speed control and an estimated value of disturbance torque acting on the vehicle body according to the running resistance of the road surface. Also, the one of the driving wheels (the driving wheel that is not subjected to slip rotation speed control) whose motor torque command value is limited is switched according to the torque distribution ratio (driving force distribution ratio). This makes it possible to suppress slippage and locking of one of the driving wheels. In other words, it is possible to excessively limit the motor torque command value of the other driving wheel that is not subjected to slip rotation speed control, thereby avoiding the occurrence of poor acceleration or deceleration. That is, it is possible to appropriately execute slip control that suppresses slip even in a state in which the front wheels 22 and the rear wheels 32 are driven.

[0233] Note that each processing procedure shown in this embodiment is an example for realizing this embodiment, and the order of some of the processing procedures may be changed within the scope that allows the realization of this embodiment, and some of the processing procedures may be omitted or other processing procedures may be added.

[0234] Each process in this embodiment is executed based on a program for causing a computer to execute various processing procedures. This embodiment can also be understood as an embodiment of a program for realizing the function of executing each process, and a recording medium for storing the program. For example, an update process for adding a new function to the control device of the electric vehicle 10 can store the program in the storage device of the control device. This makes it possible to cause the updated control device to execute each process shown in this embodiment.

[0235] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0236] 10 Electric vehicle, 11 Front drive system, 12 Rear drive system, 13 Battery, 14 Motor controller, 21 Front motor, 22 Front wheel, 23 Front inverter, 24, 34 Rotation sensor, 25, 35 Current sensor, 26 Front reduction gear, 27, 37 Drive shaft, 31 Rear motor, 32 Rear wheel, 33 Rear inverter, 36 Rear reduction gear, 40 Torque distribution calculation unit, 601 Front slip suppression calculation unit, 602 Rear slip suppression calculation unit, 603 Ground load estimation calculation unit, 604 Final torque command value calculation unit, 701 Front torque limit calculation unit, 702, 1302 Vehicle speed estimation unit, 703 Front slip rotation speed control calculation unit, 801, 1401 Disturbance estimation calculation unit, 802, 1402 Limit torque calculation unit, 803, 1403 Torque limiting section, 901, 1501 First motor torque estimated value calculation section, 902, 1502 Multiplication section, 903, 1503 Final total torque command value section, 904, 1504 Second motor torque estimated value calculation section, 905, 1505 Disturbance torque estimated value calculation section, 1001, 1601 Adder, 1301 Rear torque limiting calculation section, 1303 Rear slip rotation speed control calculation section

Claims

1. A method for controlling an electric vehicle including a first drive motor that drives a first wheel, a second drive motor that drives a second wheel, and a control device that controls operations of the first drive motor and the second drive motor, comprising: The control device includes: executing a slip rotation speed control of a motor that drives one of the first wheel and the second wheel using a drive wheel speed of the other of the first wheel and the second wheel; estimating a disturbance torque value indicating a torque related to a disturbance acting on the electric vehicle, based on a first torque command value which is a torque command value of the other motor, a second torque command value which is a torque command value of one of the motors which drives the one of the drive wheels, and a rotation state of the one of the motors; Calculating a torque limit value based on the disturbance torque value and the first torque command value; correcting a target torque command value of the one motor based on the torque limit value to set the second torque command value; determining the other motor for executing the slip rotation speed control based on a torque distribution ratio between the first drive motor and the second drive motor, which is set based on a drive force required by the electric vehicle; A method for controlling an electric vehicle.

2. A method for controlling an electric vehicle according to claim 1, comprising: When an absolute value of the difference between the torque distribution ratios is greater than a predetermined value, the control device determines the motor having the relatively larger torque distribution ratio as the other motor. A method for controlling an electric vehicle.

3. A method for controlling an electric vehicle according to claim 1 or 2, comprising: When an absolute value of the difference between the torque distribution ratios is equal to or smaller than a predetermined value, the control device determines the other motor based on a driving force transmitted to a road surface of each of the first wheel and the second wheel, the driving force changing depending on a traveling scene of the electric vehicle. A method for controlling an electric vehicle.

4. A method for controlling an electric vehicle according to claim 3, comprising: The transmitted driving force corresponds to a ground load of each of the first wheel and the second wheel. A method for controlling an electric vehicle.

5. A method for controlling an electric vehicle according to claim 4, comprising: the first wheel is a front wheel of the electric vehicle, and the second wheel is a rear wheel of the electric vehicle; the control device determines the first drive motor as the other motor when the ground load of the front wheels is equal to or greater than the ground load of the rear wheels, and determines the second drive motor as the other motor when the ground load of the front wheels is smaller than the ground load of the rear wheels. A method for controlling an electric vehicle.

6. A control device for an electric vehicle that controls operation of a first drive motor that drives a first wheel and a second drive motor that drives a second wheel, a slip rotation speed control unit that uses a drive wheel speed of one of the first wheel and the second wheel to execute slip rotation speed control of a second motor that drives the other drive wheel; a disturbance torque value estimating unit that estimates a disturbance torque value indicating a torque related to a disturbance acting on the electric vehicle, based on a first torque command value that is a torque command value of the other motor, a second torque command value that is a torque command value of one of the motors that drives one of the drive wheels, and a rotation state of the one of the motors; a torque limit value calculation unit that calculates a torque limit value based on the disturbance torque value and the first torque command value; a second torque command value setting unit that corrects a target torque command value of the one motor based on the torque limit value to set the second torque command value; a motor determination unit that determines the other motor that executes the slip rotation speed control based on a torque distribution ratio between the first drive motor and the second drive motor that is set based on a drive force required by the electric vehicle. A control device for an electric vehicle.

Images