Control method of electric vehicle and control device of electric vehicle

Abstract

One embodiment of the present application is a control method for an electrically driven vehicle. The electrically driven vehicle includes a plurality of drive wheels and a plurality of electric motors that generate driving force for the plurality of drive wheels, respectively. In the control method, a vehicle body speed is estimated for each drive wheel on the basis of a rotational speed of the electric motor. An external disturbance torque acting on the drive wheel, i.e., a drive wheel external disturbance torque, is estimated for each drive wheel on the basis of the vehicle body speed estimated for each drive wheel. A real external disturbance torque acting on the electrically driven vehicle as a whole, i.e., a vehicle external disturbance torque, is estimated on the basis of the drive wheel external disturbance torque estimated for each drive wheel. Torques that the plurality of electric motors should output, respectively, are controlled on the basis of the vehicle external disturbance torque.

Description

TECHNICAL FIELD

[0001] The present application relates to a control method of an electric vehicle and a control device of an electric vehicle. BACKGROUND

[0002] A motor control device is disclosed in JP 2019-022339 A, which stops an electric vehicle using a driving force generated by an electric motor (hereinafter referred to as a motor) for driving. Specifically, an external disturbance torque acting on the motor is estimated, and at the time of stopping, an output torque of the motor is controlled so as to coincide with the estimated external disturbance torque. SUMMARY

[0003] With respect to an electric vehicle, a plurality of electric motors for driving are sometimes used at the same time. In this way, with respect to an electric vehicle using a plurality of motors, it is sometimes difficult to accurately estimate an external disturbance torque. For example, in a case where a difference in wheel load of a plurality of drive wheels connected to each electric motor occurs depending on a road surface slope or the like, an error that cannot be ignored is sometimes superimposed on the estimated external disturbance torque. Therefore, with respect to an electric vehicle using a plurality of motors at the same time, it is not possible to accurately estimate an external disturbance torque, and as a result, it is sometimes not possible to reliably control the electric vehicle.

[0004] An object of the present application is to provide a control method of an electric vehicle and a control device of an electric vehicle, which are capable of accurately estimating an external disturbance torque and reliably controlling an electric vehicle in a case where a plurality of motors for driving are provided.

[0005] One aspect of the present application is a control method of an electric vehicle, which has a plurality of drive wheels and a plurality of electric motors that cause the plurality of drive wheels to generate driving forces, respectively. In the control method, a vehicle body speed is estimated for each drive wheel based on a rotational speed of the electric motor. In addition, an external disturbance torque acting on the drive wheel, i.e., a drive wheel external disturbance torque, is estimated for each drive wheel based on the vehicle body speed estimated for each drive wheel. Furthermore, a real external disturbance torque acting on the electric vehicle as a whole, i.e., a vehicle external disturbance torque, is estimated based on the drive wheel external disturbance torque estimated for each drive wheel, and a torque that each of the plurality of electric motors should output is controlled based on the vehicle external disturbance torque. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 is a block diagram showing the structure of an electric vehicle.

[0007] Figure 2 is a flowchart showing the control performed by a motor controller.

[0008] Figure 3 is a graph showing an example of an accelerator opening degree-torque table.

[0009] Figure 4 is an explanatory diagram showing parameters used in a motion equation of an electric vehicle.

[0010] Figure 5 is a block diagram showing a structure of performing stop control.

[0011] Figure 6 is a block diagram showing a structure of a vehicle body speed estimation section.

[0012] Figure 7 is a block diagram showing a structure of an external disturbance torque estimation section.

[0013] Figure 8 is a block diagram showing a structure of a distribution ratio operation section.

[0014] Figure 9 is a block diagram showing a structure of performing damping control.

[0015] Figure 10 is a block diagram showing a vehicle model of an electric vehicle.

[0016] Figure 11 is a block diagram of a feedforward compensator.

[0017] Figure 12 is a time chart showing the transition of a torque command value, a vehicle body speed, a front-rear acceleration, and an external disturbance torque of a comparative example and control of the present embodiment.

[0018] Figure 13 is a block diagram showing a structure of an electric vehicle to which the 1st modification pertains.

[0019] Figure 14 is a block diagram showing a structure of an electric vehicle to which the 2nd modification pertains.

[0020] Figure 15 is a block diagram showing a structure of an electric vehicle to which the 3rd modification pertains. DETAILED DESCRIPTION

[0021] Hereinafter, an embodiment of the present application will be described with reference to the drawings.

[0022] [EMBODIMENT]

[0023] Figure 1 is a block diagram showing a structure of an electric vehicle 100. The electric vehicle 100 is an electric vehicle having a plurality of drive wheels and a plurality of electric motors that cause the plurality of drive wheels to generate driving forces, respectively. In the present embodiment, the electric vehicle 100 is a so-called four-wheel drive vehicle having front wheels 22 and rear wheels 32 as drive wheels, and front motors 21 and rear motors 31 that cause the drive wheels to generate driving forces, respectively.

[0024] As shown in FIG. 1, an electric vehicle 100 has a front drive system 11, a rear drive system 12, a battery 13, and a motor controller 14. Figure 1

[0025] The front drive system 11 is a system that drives front wheels 22 with a front motor 21. The front drive system 11 has, in addition to the front motor 21 and the front wheels 22, a front inverter 23, a rotation sensor 24, a current sensor 25, and the like.

[0026] The front motor 21 is, for example, a three-phase alternating-current synchronous motor, and is driven by alternating-current electric power input from the front inverter 23. An output torque of the front motor 21 causes the front wheels 22 to generate a torque (driving force). In addition, the front motor 21 generates so-called regenerative torque when a drive shaft thereof is rotated by the front wheels 22. Thus, the front motor 21 can recover kinetic energy of the electric vehicle 100 as electric energy.

[0027] The front wheels 22 are a pair of drive wheels disposed at the front of the electric vehicle 100. The front wheels 22 are connected to the front motor 21 via a front speed reducer 26 and a drive shaft 27. In the present embodiment, the front wheels 22 are constituted by a right front wheel and a left front wheel. However, the right front wheel and the left front wheel are linked by the drive shaft 27, and are driven as one body, and thus, in the present embodiment, the right front wheel and the left front wheel are not distinguished from each other but are collectively referred to as the front wheels 22. In addition, the front wheels 22 are first drive wheels in contrast to the rear wheels 32 that are other drive wheels.

[0028] The front inverter 23 has two pairs of switching elements for each phase of the front motor 21. The front inverter 23 opens and closes the switching elements in accordance with a PWM (Pulse Width Modulation) signal input from the motor controller 14. Thus, the front inverter 23 converts direct-current electric power supplied from the battery 13 into alternating-current electric power and inputs the alternating-current electric power to the front motor 21, and drives the front motor 21. The switching elements that constitute the front inverter 23 are, for example, power semiconductor elements such as an IGBT (Insulated Gate Bipolar Transistor), a MOS-FET (Metal Oxide Semiconductor Field Effect Transistor), or the like. At the time of regenerative control, the front inverter 23 converts alternating-current electric power generated in the front motor 21 into direct-current electric power and inputs the direct-current electric power to the battery 13.

[0029] The rotation sensor 24 detects a rotor phase α f of the front motor 21. The rotor phase α f is so-called electric angle [rad]. The rotation sensor 24 is, for example, a resolver, an encoder. The detected rotor phase α f is input to the motor controller 14.

[0030] The current sensor 25 detects a current (hereinafter referred to as three-phase current) i​uf vf wf The three-phase currents i uf vf wf are input to the motor controller 14.

[0031] The rear drive system 12 is a system that drives the rear wheels 32 with the rear motor 31, and is configured to be symmetrical to the front drive system 11. Therefore, the rear drive system 12 has, in addition to the rear motor 31 and the rear wheels 32, a rear inverter 33, a rotation sensor 34, a current sensor 35, a rear reducer 36, a drive shaft 37, and the like. The above-described parts that constitute the rear drive system 12 function in the same manner as the parts of the front drive system 11. That is, the rear wheels 32 are a pair of drive wheels disposed at the rear of the electric vehicle 10. The rear wheels 32 are constituted by a right rear wheel and a left rear wheel, and in the present embodiment, the right rear wheel and the left rear wheel are collectively referred to as the rear wheels 32 without distinction. The rear wheels 32 are the second drive wheels in contrast to the front wheels 22 that are the other drive wheels. The rotor phase of the rear drive system 12 detected by the rotation sensor 34 is "α r ". The currents flowing in the respective phases of the rear motor 31 detected by the current sensor 35 are "i ur vr wr ".

[0032] The battery 13 is commonly provided for the front drive system 11 and the rear drive system 12, and supplies electric power for driving the front motor 21 and the rear motor 31. In addition, the battery 13 is charged by regenerative electric power generated in the front motor 21 and the rear motor 31 at the time of regenerative control.

[0033] The motor controller 14 is a control device of the electric vehicle 100. The motor controller 14 is constituted by one or a plurality of computers including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input / output interface (I / O interface), and the like, for example. In addition, the motor controller 14 is programmed to control the front motor 21 and the rear motor 31 and the like at a predetermined control cycle. For example, the motor controller 14 acquires various vehicle variables, and generates PWM signals for driving the front motor 21 and the rear motor 31 based on the vehicle variables, respectively. Further, the motor controller 14 inputs the generated PWM signals to the front inverter 23 and the rear inverter 33, respectively, thereby driving the front motor 21 and the rear motor 31 in accordance with the vehicle variables.

[0034] The vehicle variables are parameters indicating a control state and the like of the electric vehicle 10. The motor controller 14 acquires, as the vehicle variables, for example, the rotor phase α f of the front motor 21 and the three-phase currents i​​​​​​uf 、i vf 、i wf , the rotor phase α of the rear motor 31 r And the three-phase current i ur 、i vr 、i wr In addition, the motor controller 14 obtains the accelerator opening A po , and the DC voltage V of the battery 13 dc As vehicle variables. Accelerator opening A po A is a parameter that indicates the amount of operation of the accelerator pedal by the driver. po and the DC voltage V of the battery 13 dc The vehicle variables can be appropriately detected as needed by, for example, sensors not shown. The motor controller 14 of this embodiment directly obtains the vehicle variables from sensors, but the motor controller 14 can obtain some or all of the vehicle variables from other controllers (computers) not shown.

[0035] In the electric vehicle 100 configured as described above, the motor controller 14 estimates the external disturbance torque, which is torque generated by external disturbances. Based on the estimated external disturbance torque, the motor controller 14 controls the torques to be output by the front motor 21 and the rear motor 31, thereby controlling the operation of the electric vehicle 100. The following describes in detail, as an example, how the estimated external disturbance torque is used to distribute the driving force to the front wheels 22 and rear wheels 32, and how it is used to stop the electric vehicle 100.

[0036] Figure 2 1 is a flow chart showing the control performed by the motor controller 14. Figure 2 As shown, the motor controller 14 performs input processing S11, first torque target value calculation S12, stop control S13, vibration reduction control S14, current target value calculation S15, and current control calculation S16. Specifically, the motor controller 14 is programmed to function as an input processing unit that performs input processing S11, a first torque target value calculation unit that performs first torque target value calculation S12, a stop control unit that performs stop control S13, and a vibration reduction control unit that performs vibration reduction control S14. Furthermore, the motor controller 14 is programmed to function as a current target value calculation unit that performs current target value calculation S15, and a current control calculation unit that performs current control calculation S16.

[0037] The input process S11 is a process of acquiring vehicle variables and the like required for controlling the front motor 21 and the rear motor 31 or performing calculations.

[0038] Specifically, the motor controller 14 obtains the three-phase current i of the front motor 21 in the input process S11.uf , i vf , i wf and the sum of the three-phase currents i ur , i vr , i wr of the front motor 21 is zero, so the motor controller 14 is able to acquire, for example, the currents of two of the phases and calculate the current of the remaining one phase by arithmetic operation. The same applies to the three-phase currents i uf , i vf , i wf of the rear motor 31. ur , i vr , i wr .

[0039] In addition, the motor controller 14 acquires, in the input process S11, the rotor phase α f of the front motor 21, r the rotor phase α dc of the rear motor 31, and the direct-current voltage V mf of the battery 13.

[0040] In addition, the motor controller 14 performs, in the input process S11, arithmetic operation on, for example, the rotational angular velocity ω mr [rad / s] of the front motor 21, and the rotational angular velocity ω mf [rad / s] of the rear motor 31. The rotational angular velocity ω f of the front motor 21 is a mechanical angular velocity, and is calculated by differentiating the rotor phase α mr and dividing by the number of pole pairs of the front motor 21. Similarly, the rotational angular velocity ω r of the rear motor 31 is a mechanical angular velocity, and is calculated by differentiating the rotor phase α mf and dividing by the number of pole pairs of the rear motor 31.

[0041] In addition, in the present embodiment, as parameters indicating the rotational speeds of the electric motors possessed by the electric vehicle 100, the rotational angular velocity ω mr of the rear motor 31 is used. However, for example, the rotational speed N mf [rpm] of the front motor 21 and the rotational speed N mr [rpm] of the rear motor 31 can be used as parameters indicating the rotational speeds of the electric motors. The rotational speed N mf of the front motor 21 and the rotational speed N mr of the rear motor 31 can be calculated by multiplying the rotational angular velocity ω mf of the front motor 21 and the rotational angular velocity ω mr of the rear motor 31 by a unit conversion coefficient (60 / 2π), respectively.

[0042] The first torque target value calculation S12 is a calculation of the target value of the torque to be outputted by the front motor 21 and the rear motor 31 as a whole (hereinafter referred to as the first torque target value T m1 * In this embodiment, the motor controller 14 is based on the accelerator opening A po and the rotational angular velocity ω of the front motor 21 mf For the first torque target value T m1 * Perform calculations.

[0043] Figure 3 is a graph showing an example of an accelerator opening-torque table. Figure 3 As shown, the motor controller 14 holds in advance the accelerator opening A based on experiments or simulations. po and the angular velocity ω mf and the first torque target value T m1 *According to the accelerator opening-torque table. Therefore, the motor controller 14 refers to the accelerator opening-torque table and calculates the accelerator opening A po and the angular velocity ω mf The corresponding first torque target value T m1 * Perform calculations.

[0044] In a normal driving state where the stop control S13 is not executed, the first torque target value T m1 * Assigned to the front torque command value T mf1 * The torque command value T mr1 * . The previous torque command value T mf1 * It is a command value indicating the target torque that the front motor 21 should output. mr1 * It is a command value indicating the target torque that the rear motor 31 should output. mf1 * And then the torque command value T mr1 * The first torque target value T m1 * The distribution ratio K f3 According to the actual external disturbance torque acting on the electric vehicle 100 as a whole, that is, the vehicle external disturbance torque T d "Adjust. Regarding the external disturbance torque T d The corresponding first torque target value T m1* The details of the allocation will be described in detail later together with the stop control S13.

[0045] Stop control S13 (refer to Figure 2 ) is a control to stop the electric vehicle 100 and maintain the stopped state by using the front motor 21, the rear motor 31, or both. Specifically, the motor controller 14 determines whether the electric vehicle 100 is about to stop. If it is determined that the electric vehicle 100 is about to stop, the motor controller 14 executes the stop control S13. In addition, the motor controller 14 controls the vehicle external disturbance torque T d The estimated vehicle external disturbance torque T d The second torque target value T is set m2 * Furthermore, when executing the stop control S13, the motor controller 14 sets the second torque target value T m2 * Assigned to the front torque command value T mf1 * The torque command value T mr1 * Thus, the motor controller 14 stops the electric vehicle 100 and maintains the stopped state by controlling the front motor 21 and / or the rear motor 31 regardless of the slope of the road. m2 * For the previous torque command value T mf1 * And then the torque command value T mr1 * The distribution ratio is based on the vehicle external disturbance torque T d The stop control S13 will be described in detail later.

[0046] The vibration reduction control S14 is a process for suppressing vibration generated in the driving force transmission system. In the vibration reduction control S14, the motor controller 14 controls the motor 14 based on the torque command value T mf1 * The final torque command value for the front motor 21 (hereinafter referred to as the front final torque command value T mff * ) is calculated. The final torque command value T mff * The torsional vibration of the drive shaft 27 is suppressed, and the requested torque is output by the front motor 21. Similarly, in the vibration reduction control S14, the motor controller 14 outputs the requested torque based on the rear torque command value T mr1 * The final torque command value for the rear motor 31 (hereinafter referred to as the rear final torque command value T mrf *) is calculated. The rear final torque command value T mrf * The rear motor 31 is suppressed from torsional vibration and the like, and outputs a requested torque. The damping control S14 is described in detail later.

[0047] The current target value operation S15 is a process of calculating a target value (hereinafter referred to as a current target value) of a current input to the front motor 21 and the rear motor 31. The motor controller 14 calculates a current target value in a so-called dq-axis coordinate system. Specifically, the motor controller 14 calculates a dq-axis current target value i mff * , a rotational angular velocity ω mf of the front motor 21, and a direct current voltage V dc of the battery 13, and calculates a dq-axis current target value i df * , i qf * of the front motor 21. Similarly, the motor controller 14 calculates a dq-axis current target value i mrf * , a rotational angular velocity ω mr of the rear motor 31, and a direct current voltage V dc of the battery 13, and calculates a dq-axis current target value i dr * , i qr * of the rear motor 31.

[0048] Further, the motor controller 14 holds a table in advance in which the front final torque command value T mff * , the rotational angular velocity ω mf of the front motor 21, and the direct current voltage V dc of the battery 13 are associated with the dq-axis current target value i df * , i qf * of the front motor 21, by experiment or simulation or the like. Similarly, the motor controller 14 holds a table in advance in which the rear final torque command value T mrf * , the rotational angular velocity ω mr of the rear motor 31, and the direct current voltage V dc of the battery 13 are associated with the dq-axis current target value i dr * , i qr * of the rear motor 31, by experiment or simulation or the like. Therefore, the motor controller 14 refers to the above table and calculates the dq-axis current target value i df* qf * and dq-axis current target values i dr * qr *

[0049] The current control operation S16 is a process of operating PWM signals for driving the front motor 21 and the rear motor 31 respectively. The motor controller 14 operates the PWM signal for driving the front motor 21 in the following manner. First, the motor controller 14 operates dq-axis currents i uf vf wf and rotor phase α f based on three-phase currents i df qf df * qf * and dq-axis currents i df qf based on the deviation of dq-axis voltage command values v df qf . At this time, the motor controller 14 sometimes adds so-called non-interference control. In addition, the motor controller 14 operates three-phase voltage command values v df qf f based on dq-axis voltage command values v uf vf wf and rotor phase α uf vf wf and DC voltage V dc of the battery 13. The PWM signal is operated in accordance with the PWM signal thus operated, and the switching elements of the front inverter 23 are turned on and off, whereby the front motor 21 is driven in a manner to output the requested torque. The operation of the PWM signal for driving the front motor 21 is explained here, but the operation of the PWM signal for driving the rear motor 31 is the same as this.

[0050] Next, the stop control S13 and the distribution of the first torque target value T m1 * , and the damping control S14 are described in detail.

[0051] < Vehicle Model of Electric Vehicle >

[0052] ​​​​​​​​​​​​​​​​The stop control S13 and the damping control S14 are executed on the basis of a vehicle model of the electric vehicle 100. Specifically, in the stop control S13, a transfer characteristic G ωfV (s) based on the vehicle model of the electric vehicle 100 is used. ωrV (s). The transfer characteristic G ωfV (s) is a transfer characteristic from the rotational angular velocity ω mf of the front motor 21 to the vehicle body speed. The transfer characteristic G ωrV (s) is a transfer characteristic from the rotational angular velocity ω mr of the rear motor 31 to the vehicle body speed.

[0053] In addition, in the damping control S14, the transfer characteristic G pff (s) based on the vehicle model of the electric vehicle 100, the transfer characteristic G rff (s) / G pff (s), the transfer characteristic G prr (s), and the transfer characteristic G rrr (s) / G prr (s) are used. The transfer characteristic G pff (s) is a transfer characteristic from the torque (hereinafter referred to as front motor torque T mf ) output by the front motor 21 to the rotational angular velocity ω mf of the front motor 21. The transfer characteristic G rff (s) / G pff (s) is a transfer characteristic of a feedforward compensator that suppresses torsional vibration of the drive shaft 27 of the front drive system 11. The transfer characteristic G prr (s) is a transfer characteristic from the torque (hereinafter referred to as rear motor torque T mr ) output by the rear motor 31 to the rotational angular velocity ω mr of the rear motor 31. The transfer characteristic G rrr (s) / G Dr r(s) is a transfer characteristic of a feedforward compensator that suppresses torsional vibration of the drive shaft 37 of the rear drive system 12.

[0054] Here, before the stop control S13 and the damping control S14 are described in detail, the vehicle model of the electric vehicle 100 and its motion equation, and each transfer characteristic used for the damping control S14 are described in particular. As for each transfer characteristic used for the stop control S13, detailed description is made in the description of the stop control S13.

[0055] Figure 4 is a diagram that shows parameters used in the motion equation of the electric vehicle 100. As Figure 4If the drive force transmission system of the electric vehicle 100 is modeled, the motion equation of the electric vehicle 100 is represented by the following equations (1) to (11).

[0056] [Math. 1]

[0057]

[0058] T df = K df · θ df (6)

[0059] T dr = K dr · θ dr (7)

[0060] F f = K tf · (r f ω mf - V) (8)

[0061] F r = K t · (r r ω mr - V) (9)

[0062] θ df = θ mf / N f - θ wf (10)

[0063] θ dr = θ mr / N r - θ wr (11)

[0064] Figure 4 The "f" indicated at the end of the auxiliary notation (suffix) of each parameter is the front, and the "r" indicates the rear. In addition, the notation "•" indicated above the parameters in the above (1) to (5) indicates time differentiation, and the notation "•" indicated between the parameters in the above (1) to (9) indicates multiplication.

[0065] J mf , J mr : motor inertia

[0066] J wf , J wr : drive shaft inertia (1 shaft)

[0067] K df , K dr : torsional rigidity of drive shaft

[0068] K tf , K tr : Coefficient related to friction between tire and road surface

[0069] N f 、N r : Total transmission ratio

[0070] r f 、r r : Tire load radius

[0071] ω mf 、ω mr : Angular velocity of the motor

[0072] θ mf ,θ mr : Motor angle

[0073] ω wf 、ω wr : driving wheel angular velocity

[0074] θ wf ,θ wr : Driving wheel angle

[0075] T mf 、T mr : Motor torque

[0076] T df 、T dr : Drive shaft torque

[0077] F f 、F r :Driving force (2 axes)

[0078] V: Vehicle speed

[0079] M: Vehicle mass

[0080] If Laplace transform is performed on equations (1) to (11), the motor torque T can be obtained. mf The rotational angular velocity ω of the front motor 21 mf The transfer characteristic G pff (s) is expressed by the following equations (12) and (13). The coefficients b0 to b6 and the coefficients a0 to a6 in equation (13) are expressed by the following equations (14) and (15), respectively. 11 ~χ 24 and parameter δ 11 ~δ 44 They are represented by the following equations (16) and (17), respectively.

[0081] [Mathematical formula 2]

[0082] ω mf = G pff (s) · T mf (12)

[0083]

[0084] [Equation 3]

[0085]

[0086] [Equation 4]

[0087]

[0088] [Equation 5]

[0089]

[0090] [Equation 6]

[0091]

[0092] If the extreme point and the zero point of the transfer characteristic G pff (s) shown in Equation (13) are studied, the transfer characteristic G pff (s) is expressed in the form of Equation (18) shown below.

[0093] [Equation 7]

[0094]

[0095] In Equation (18), α and α', β and β', ζ pr and ζ pr ', ω pr and ω pr ' represent values that are extremely close. Therefore, the extreme zero value cancellation is performed in approximation of α = α', β = β', ζ pr = ζ pr ', and ω pr = ω pr ', and thus the transfer characteristic G pff (s) is expressed in the form of 2nd / 3rd as shown in Equation (19) shown below. In this way, in the vehicle model of the electric vehicle 100, the transfer characteristic G mf (s) from the front motor torque T mf to the rotational angular velocity ω pff of the front motor 21 can be approximated in the form of 2nd / 3rd.

[0096] [Equation 8]

[0097]

[0098] Further, the transfer characteristic G pff (s) of the normal response that suppresses the torsional vibration caused by the drive shaft 27 of the front drive system 11 can be expressed by the following expression (20). rff

[0099] [Expression 9]

[0100]

[0101] Therefore, in the front drive system 11, the feedforward compensator that suppresses the torsional vibration of the drive shaft 27 can be composed of the transfer characteristic G rff (s) / G pff (s) as shown in the following expression (21).

[0102] [Expression 10]

[0103]

[0104] As described above, the transfer characteristic G mr (s) of the rotational angular velocity ω mr of the rear motor 31 from the rear motor torque T prr (s) can be obtained. That is, the transfer characteristic G prr (s) is expressed by the following expressions (22) and (23).

[0105] [Expression 11]

[0106] ω mr = G prr (s) · T mr (22)

[0107]

[0108] Further, the transfer characteristic G rrr (s) of the normal response that suppresses the torsional vibration of the drive shaft 37 in the rear drive system 12 is expressed by the following expression (24).

[0109] [Expression 12]

[0110]

[0111] Therefore, in the rear drive system 12, the feedforward compensator that suppresses the torsional vibration of the drive shaft 37 can be composed of the transfer characteristic G rrr (s) / G prr (s) as shown in the following expression (25).

[0112] [Expression 13] ​

[0113]

[0114] In addition, the transfer characteristic G mf (s) of the electric vehicle 100 from the rear motor torque Tmr to the rotational angular velocity ω prf (s) of the front motor 21 is as follows. That is, if the transfer characteristic G prf (s) is obtained by performing Laplace transformation on the equations (1) to (11), it is expressed by the following equations (26) and (27).

[0115] [Math. 14]

[0116] ω mf = G prf (s) · T mr (26)

[0117]

[0118] Further, by investigating the extreme value of the transfer characteristic G prf (s) expressed by the equation (27), it is found that the transfer characteristic G prf (s) is expressed by the following equation (28).

[0119] [Math. 15]

[0120]

[0121] Here, α and β that are the extreme values of the equation (28) are at the origin and away from the position where the extreme value is dominant, and if the influence on the transfer characteristic G prf (s) is considered to be small, the transfer characteristic G prf (s) can be approximated to the following equation (29).

[0122] [Math. 16]

[0123]

[0124] Further, if the damping control algorithm of the rear drive system 12 is considered, the transfer characteristic G prf (s) is expressed by the following equation (30).

[0125] [Math. 17]

[0126]

[0127] Therefore, according to the normal response of the rotational angular velocity ω mf of the front motor 21, the transfer characteristic G mr (s) for suppressing the torsional vibration of the drive shaft 27 due to the input of the rear motor torque T rrf(s) is represented by the following expression (31).

[0128] [Expression 18]

[0129]

[0130] Further, the control structure of the electric vehicle 100 is formed in a substantially symmetrical structure in the front drive system 11 and the rear drive system 12, and therefore the transfer characteristics G mf of the rotational angular velocity ω mr of the rear motor 31 from the front motor torque T pfr (s) are represented by the same form as the expressions (26) to (30). In addition, the transfer characteristics G mr for suppressing the torsional vibration of the drive shaft 37 due to the input of the front motor torque T mf (s) are represented in the same form as the above-described expression (31) based on the normal response of the rotational angular velocity ω rfr of the rear motor 31.

[0131] <Stop Control>

[0132] Figure 5 is a block diagram showing the structure of the stop control S13. As shown in Figure 5 , the motor controller 14 functions as a vehicle body speed estimation section 51, an external disturbance torque estimation section 52, a 2nd torque target value operation section 53, a torque comparison section 54, and a torque distribution section 55.

[0133] The vehicle body speed estimation section 51 estimates the vehicle body speed of the electric vehicle 100 from each drive wheel based on the rotational speed of the electric motor possessed by the electric vehicle 100. In the present embodiment, with respect to the front wheel 22 as the drive wheel, the vehicle body speed estimation section 51 estimates the vehicle body speed of the electric vehicle 100 based on the rotational angular velocity ω mf of the front motor 21. Hereinafter, the vehicle body speed estimated based on the rotational angular velocity ω mf of the front motor 21 will be referred to as a 1st estimated vehicle body speed V f ^. Similarly, with respect to the rear wheel 32 as the drive wheel, the vehicle body speed estimation section 51 estimates the vehicle body speed of the electric vehicle 100 based on the rotational angular velocity ω mr of the rear motor 31. Hereinafter, the vehicle body speed estimated based on the rotational angular velocity ω mr of the rear motor 31 will be referred to as a 2nd estimated vehicle body speed V r ^. The 1st estimated vehicle body speed V f ^ and the 2nd estimated vehicle body speed V r ^ are input to the external disturbance torque estimation section 52.

[0134] And, the vehicle body speed estimation section 51 estimates the first estimated vehicle body speed V f or the second estimated vehicle body speed V r And the vehicle body speed feedback torque T ω is calculated. The vehicle body speed feedback torque T ω converges to zero as the vehicle body speed of the electric vehicle 100 decreases. The vehicle body speed feedback torque T ω is input to the second torque target value calculation section 53.

[0135] The external disturbance torque estimation section 52 estimates the vehicle external disturbance torque T mff *(previous value), the final torque instruction value T mrf *(previous value), the first estimated vehicle body speed V f and the second estimated vehicle body speed V r And the vehicle external disturbance torque T d is estimated. The external disturbance torque refers to a torque that is generated due to an external disturbance such as a road slope. The vehicle external disturbance torque T d is a torque that is considered to be a true external disturbance torque that acts on the electric vehicle 100 having a plurality of electric motors and a plurality of drive wheels as a whole. For example, even in a case where the wheel load of the front wheels 22 and the wheel load of the rear wheels 32 are different due to a road slope, the vehicle external disturbance torque T d is reduced or suppressed of an error due to the difference in the wheel load, and substantially represents a true external disturbance torque corresponding to the road slope. The vehicle external disturbance torque T d is input to the second torque target value calculation section 53.

[0136] In addition, the external disturbance torque estimation section 52 calculates the distribution ratio K d based on the estimated vehicle external disturbance torque T f3 The distribution ratio K f3 is a ratio at which a target value of a torque that should be output with respect to the front motor 21 and the rear motor 31 as a whole is distributed to the front torque instruction value T mf1 * and the rear torque instruction value T mr1 * The distribution ratio K f3 is set to a value that is greater than or equal to zero to a value that is less than or equal to 1, for example. In a normal running state where the stop control S13 is not performed, the first torque target value T m1 * is distributed according to the distribution ratio K f3 In a state where the stop control S13 is performed, the second torque target value T m2 * is distributed according to the distribution ratio K f3And the distribution. The distribution ratio K f3 Is input to the torque distribution section 55.

[0137] The 2nd torque target value operation section 53 operates the 2nd torque target value T ω Based on the vehicle body speed feedback torque T d And the vehicle exterior disturbance torque T m2 * In this embodiment, the 2nd torque target value operation section 53 is an adder, and operates the 2nd torque target value T ω By adding the vehicle body speed feedback torque T d And the vehicle exterior disturbance torque T m2 * In this embodiment, the 2nd torque target value operation section 53 is an adder, and operates the 2nd torque target value T

[0138] The 2nd torque target value T m2 * Is a criterion for determining whether or not the stop control S13 should be executed, that is, whether or not the electric vehicle 100 is about to stop. In the state of being about to stop in which the stop control S13 is executed, the 2nd torque target value T m1 * Is used instead of the 1st torque target value T m2 * As the target value of the torque that should be output with respect to the entire front motor 21 and the entire rear motor 31. In addition, as described above, the vehicle body speed feedback torque T ω Converges to zero as the vehicle body speed of the electric vehicle 100 decreases, and therefore the 2nd torque target value T m2 * Converges to the vehicle exterior disturbance torque T d As the vehicle body speed of the electric vehicle 100 decreases. Therefore, at the time when the electric vehicle 100 stops, the 2nd torque target value T m2 * Indicates the torque for maintaining the stopped state of the electric vehicle 100 against the vehicle exterior disturbance torque T d . For example, on an uphill road, the 2nd torque target value T m2 * Converges to a positive torque corresponding to the road surface slope, on a downhill road, the 2nd torque target value T m2 * Converges to a negative torque corresponding to the road surface slope. Also, on a flat road, the 2nd torque target value T m2 * Converges to approximately zero. The 2nd torque target value T m2 * Is input to the torque comparison section 54.

[0139] The torque comparison section 54 compares the 1st torque target value T m1 *and the 2nd torque target value T m2 * based on the comparison result thereof as the 3rd torque target value T m3 * the 1st torque target value T m1 * or the 2nd torque target value T m2 * is output. Specifically, in a case where the 2nd torque target value T m2 * is greater than the 1st torque target value T m1 * , the torque comparison section 54 determines that the electric vehicle 100 is in the state of imminent stop, and outputs the 2nd torque target value T m3 * as the 3rd torque target value T m2 * . On the other hand, in a case where the 2nd torque target value T m2 * is less than or equal to the 1st torque target value T m1 * , the torque comparison section 54 determines that the electric vehicle 100 is not in the state of imminent stop, but in the normal traveling state, and outputs the 1st torque target value T m3 * as the 3rd torque target value T m1 * . That is, the torque comparison section 54 determines whether the electric vehicle 100 is in the state of imminent stop by comparing the 1st torque target value T m1 * and the 2nd torque target value T m2 * . Also, the torque comparison section 54 outputs the 2nd torque target value T m3 * as the 3rd torque target value T m2 * in the case where the electric vehicle 100 is in the state of imminent stop, thereby setting to execute the stop control S13.

[0140] The torque distribution section 55 distributes the 3rd torque target value T f3 to the front torque command value T m3 * and the rear torque command value T mf1 * based on the distribution ratio K mr1 * . The torque distribution section 55 has a front torque command value calculation section 56 and a rear torque command value calculation section 57. In the present embodiment, the front torque command value calculation section 56 distributes the 3rd torque target value Tm3 * Multiply by the distribution ratio K f3 The forward torque command value T mf1 * In addition, the rear torque command value calculation unit 57 calculates the third torque target value T m3 * Multiply by "1-K f3 "And the torque command value T mr1 * Perform calculations.

[0141] When it is determined that the electric vehicle 100 is about to stop, the third torque target value T m3 * The actual state is the second torque target value T m2 * , so the torque distribution unit 55 actually sets the second torque target value T m2 * Assigned to the front torque command value T mf1 * The torque command value T mr1 * On the other hand, when the electric vehicle 100 is not in a state of being about to stop but in a normal running state, the third torque target value T m3 * The actual state is the first torque target value T m1 * , so the torque distribution unit 55 actually converts the first torque target value T m1 * Assigned to the front torque command value T mf1 * The torque command value T mr1 * .

[0142] As mentioned above, the distribution ratio K f3 Based on the vehicle external disturbance torque T d Regardless of the third torque target value T m3 * The actual state is the first torque target value T m1 * and the second torque target value T m2 * That is, when it is determined that the electric vehicle 100 is about to stop, the vehicle external disturbance torque T is substantially determined based on the estimated vehicle external disturbance torque T. d The distribution ratio K is appropriately set f3 The second torque target value T is allocated m2 *Thus, the stop control S13 is realized in which the electric vehicle 100 is stopped or maintained in a stopped state by the front motor 21 and the rear motor 31. Also, even when the electric vehicle 100 is not in a state of about to stop but in a normal running state, the distribution ratio K is appropriately set on the basis of the estimated vehicle exterior disturbance torque T d and the like f3 , and the first torque target value T m1 is distributed * . Thus, even in the case of a normal running state, for example, the appropriate front torque command value T mf1 and the rear torque command value T * are set on the basis of the road surface slope, the respective wheel loads of the front wheels 22 and the rear wheels 32, and the like mr1 * . As a result, a stable running state is realized.

[0143] Next, the detailed configuration of the vehicle body speed estimation section 51 and the exterior disturbance torque estimation section 52 will be described.

[0144] Figure 6 is a block diagram showing the configuration of the vehicle body speed estimation section 51. As shown in Figure 6 , the vehicle body speed estimation section 51 has a first estimated vehicle body speed operation section 61, a second estimated vehicle body speed operation section 62, and a vehicle body speed feedback torque operation section 63.

[0145] The first estimated vehicle body speed operation section 61 operates the first estimated vehicle body speed V mf on the basis of the rotational angular speed ω f of the front motor 21. The first estimated vehicle body speed operation section 61 is constituted, for example, by a transfer characteristic G mf (s) from the rotational angular speed ω ωfV of the front motor 21 to the vehicle body speed of the drive shaft 27 of the front drive system 11. In the present embodiment, the transfer characteristic G ωfV (s) is a constant K f defined by the overall transmission ratio N f of the front drive system 11 and the dynamic tire load radius r ωfV of the front wheels 22, as shown in the following expression (33). ωfV The constant K f is represented by the following expression (33) using the overall transmission ratio N f of the front drive system 11 and the dynamic tire load radius r

[0146] [Expression 19]

[0147] G ωfV (s) = K ωfV (32)

[0148]

[0149] Further, the transfer characteristic G ωfV (s) constituting the first estimated vehicle speed operation section 61 can be replaced by a constant K ωfV constituted in the above-described manner, a filter represented by the following expression (34) that approximates the transfer characteristic from the rotational angular velocity ω mf of the front motor 21 to the vehicle speed, or the like is used.

[0150] [mathematical expression 20]

[0151]

[0152] The second estimated vehicle speed operation section 62 operates the second estimated vehicle speed V mr based on the rotational angular velocity ω r of the rear motor 31. The second estimated vehicle speed operation section 62 is constituted, for example, by a transfer characteristic G mr (s) from the rotational angular velocity ω ωrV of the rear motor 31 to the vehicle speed of the drive shaft 37 of the rear drive system 12. In the present embodiment, the transfer characteristic G ωrV (s) is a constant K r defined by the overall transmission ratio N r of the rear drive system 12 and the dynamic tire load radius r ωrV of the rear wheel 32, as shown in the following expression (35). The constant K ωrV is represented by the following expression (36) using the overall transmission ratio N r of the rear drive system 12 and the dynamic tire load radius r r of the rear wheel 32.

[0153] [mathematical expression 21]

[0154] G ωrV (s) = K ωrV (35)

[0155]

[0156] Further, the transfer characteristic G ωrV (s) constituting the second estimated vehicle speed operation section 62 can be replaced by a constant K ωrV constituted in the above-described manner, a filter represented by the following expression (37) that approximates the transfer characteristic from the rotational angular velocity ω mr of the rear motor 31 to the vehicle speed, or the like is used.

[0157] [mathematical expression 22]

[0158]

[0159] The vehicle body speed feedback torque calculation section 63 calculates the vehicle body speed feedback torque T f by multiplying the first estimated vehicle body speed V vref by a gain K ω . The gain K vref is appropriately set in advance based on experiments or simulations, etc. The gain K vref is negative (K vref < 0). In addition, the vehicle body speed feedback torque calculation section 63 can also calculate the vehicle body speed feedback torque T r by multiplying the second estimated vehicle body speed V vref by a gain K ω .

[0160] Figure 7 is a block diagram showing the structure of the external disturbance torque estimation section 52. As shown in Figure 7 , the external disturbance torque estimation section 52 has a total torque calculation section 71, a first estimated torque calculation section 72, a second estimated torque calculation section 73, a third estimated torque calculation section 74, a first drive wheel external disturbance torque estimation section 75, a second drive wheel external disturbance torque estimation section 76, a selector 77, and a distribution ratio calculation section 78.

[0161] The total torque calculation section 71 calculates a target value of the sum of the torques that should be output by the plurality of drive wheels, i.e., the total torque T m * . In the present embodiment, the total torque calculation section 71 is an adder that calculates the total torque T mff * by adding the preceding final torque command value T mrf * and the succeeding final torque command value T m * . With respect to the front drive system 11 and the rear drive system 12, in cases where the total transmission ratio N f , N r , the dynamic tire load radius r f , r r are different, the total torque calculation section 71, for example, multiplies the succeeding final torque command value T mrf * by a gain that converts to the output shaft torque of the front motor 21. The total torque T m * is input to the second estimated torque calculation section 73 and the selector 77.

[0162] In addition, the total torque calculation section 71 is an adder that can add the preceding final torque command value T mff* (previous value) and the final torque command value T mrf * (Last value) Different parameters for total torque T m * For example, the third torque target value T m3 * is one of the parameters indicating the sum of the torques to be outputted by the front wheels 22 and the rear wheels 32. Therefore, the total torque calculation unit 71 can obtain the third torque target value T m3 * And set it as the total torque T m * Among them, the final torque command value T mff * The final torque command value T mrf * Since it is the final command value after the vibration reduction control S14, it is preferable that the total torque calculation unit 71 uses the previous final torque command value T mff * The final torque command value T mrf * For the total torque T m * This can improve the vehicle external disturbance torque T calculated by the external disturbance torque estimation unit 52. d and distribution ratio K f3 accuracy.

[0163] The first estimated torque calculation unit 72 calculates the torque based on the first estimated vehicle body speed V f ^For the first estimated torque T m1 ^Calculation is performed. The first estimated torque T m1 ^ is about the front motor torque T mf And the subsequent motor torque T mr That is, the first estimated torque T m1 ^ represents the torque corresponding to the driving force that the electric vehicle 100 should produce as a whole (hereinafter referred to as vehicle torque). m1 ^ represents the vehicle torque after the error caused by the change of the wheel load of the front wheel 22 and the rear wheel 32 is superimposed. In this embodiment, the first estimated torque calculation unit 72 is formed by the filter H1(s) / G r1 (s), the filter H1(s) / G r1 (s) is responded by the vehicle G r1 (s) and a low-pass filter H1(s). That is, the first estimated torque calculation unit 72 uses the filter H1(s) / G r1 (s) For the first estimated vehicle body speed V f^The first estimated torque T is filtered and m1 ^Perform calculations.

[0164] Vehicle response G r1 (s) Using the equivalent mass M of the electric vehicle 100 v and coefficient K Mf It is expressed by the following formula (38). v The vehicle mass M of the electric vehicle 100 and the motor inertia J of the front motor 21 and the rear motor 31 are used. mf 、J mr , Inertia of drive shafts 27, 37 (wheel inertia) J wf 、J wr The coefficient K is expressed by the following formula (39). Mf Using the total transmission ratio N of the front drive system 11 f and the tire load radius r of the front wheel 22 f It is represented by the following formula (40).

[0165] [Mathematical formula 23]

[0166]

[0167] The low-pass filter H1(s) is specified to be greater than or equal to the vehicle response G r1 The difference between the denominator and numerator of (s). In this embodiment, the low-pass filter H1(s) is represented by the following equation (41).

[0168] [Mathematical formula 24]

[0169]

[0170] The second estimated torque calculation unit 73 is based on the total torque T m * The second estimated torque T m2 In this embodiment, the first estimated torque T m1 ^ and the third estimated torque T m3 According to the estimation method of ^, the second estimated torque calculation unit 73 uses the low-pass filter H1(s) to calculate the total torque T m * The second estimated torque T is filtered. m2 ^Calculation is performed. Second estimated torque T m2 ^ represents the vehicle torque corresponding to the driving force that the electric vehicle 100 should produce as a whole. m2 ^ represents the vehicle torque in an ideal state without adding errors caused by changes in wheel loads of the front wheels 22 and the rear wheels 32. Therefore, the second estimated torque T m2^ input to the first drive wheel outside disturbance torque estimation section 75 and the second drive wheel outside disturbance torque estimation section 76, is used as the first drive wheel outside disturbance torque T df and the second drive wheel outside disturbance torque T d in the calculation of the first estimated vehicle speed V

[0171] The third estimated torque calculation section 74 calculates the third estimated torque T r based on the second estimated vehicle speed V m3 The third estimated torque T m3 is a value estimated with respect to the total amount of the front motor torque T mf and the rear motor torque T mr . That is, the third estimated torque T m3 represents the vehicle torque corresponding to the driving force that should be exerted by the electric vehicle 100 as a whole. Here, the third estimated torque T m3 represents the vehicle torque to which an error caused by a change in the wheel load of the front wheels 22 and the rear wheels 32, or the like, is superimposed. In the present embodiment, the third estimated torque calculation section 74 is constituted by a filter H1(s) / G r2 (s) that is constituted by a vehicle response G r2 (s) and a low-pass filter H1(s). That is, the third estimated torque calculation section 74 calculates the third estimated torque T r2 based on the second estimated vehicle speed V r2 by filtering the second estimated vehicle speed V r with the filter H1(s) / G m3 (s).

[0172] The vehicle response G r2 (s) is represented by the following expression (42) using the equivalent mass M v of the electric vehicle 100 and a coefficient K Mr . The equivalent mass M v is represented by the aforementioned expression (39). The coefficient K Mr is represented by the following expression (43) using the total transmission ratio N r of the rear drive system 12 and the tire load radius r r of the rear wheels 32.

[0173] [Expression 25]

[0174]

[0175] The first drive wheel outside disturbance torque estimation section 75 calculates the first drive wheel outside disturbance torque T m1 based on the first estimated torque T m2 and the second estimated torque T dfis calculated. In the present embodiment, the first drive wheel outside disturbance torque estimator 75 is a subtractor that subtracts the third estimated torque T m2 from the second estimated torque T m1 to calculate the first drive wheel outside disturbance torque T df . The drive wheel outside disturbance torque is an estimated value with respect to the outside disturbance torque acting on the drive wheel. That is, the first drive wheel outside disturbance torque T df represents the outside disturbance torque estimated in accordance with the driving state of the front motor 21 (or the front wheel 22 or the front drive system 11). The first drive wheel outside disturbance torque T df is input to the selector 77 and the distribution ratio calculator 78.

[0176] The second drive wheel outside disturbance torque estimator 76 calculates the second drive wheel outside disturbance torque T m3 based on the third estimated torque T m2 and the second estimated torque T dr . In the present embodiment, the second drive wheel outside disturbance torque estimator 76 is a subtractor that subtracts the third estimated torque T m2 from the second estimated torque T m3 to calculate the second drive wheel outside disturbance torque T dr . The second drive wheel outside disturbance torque T dr is an estimated value with respect to the outside disturbance torque acting on the drive wheel. That is, the second drive wheel outside disturbance torque T dr represents the outside disturbance torque estimated in accordance with the driving state of the rear motor 31 (or the rear wheel 32 or the rear drive system 12). The second drive wheel outside disturbance torque T df should be the same value as the aforementioned first drive wheel outside disturbance torque T df . However, in reality, in a case where the wheel loads of the front wheel 22 and the rear wheel 32 differ due to the road surface slope or the like, the first drive wheel outside disturbance torque T dr and the second drive wheel outside disturbance torque T dr also differ accordingly. The second drive wheel outside disturbance torque T m is input to the selector 77 and the distribution ratio calculator 78.

[0177] The selector 77 selects one of the first drive wheel outside disturbance torque T * or the second drive wheel outside disturbance torque T df based on the total torque T dr and outputs it as the vehicle outside disturbance torque T d . Specifically, as shown in the following expression (44), the selector 77 selects the first drive wheel outside disturbance torque T m * when the total torque Tdf and the external disturbance torque T of the second driving wheel dr The minimum value of the vehicle external disturbance torque T d On the other hand, the total torque T m * When the value is greater than or equal to zero (zero or positive), the selector 77 sets the first driving wheel external disturbance torque T df and the external disturbance torque T of the second driving wheel dr The maximum value of the vehicle external disturbance torque T d That is, the selector 77 outputs the first driving wheel external disturbance torque T based on the first driving wheel external disturbance torque T estimated for each of the front wheels 22 and the rear wheels 32. d f and the external disturbance torque T of the second driving wheel dr The vehicle's external disturbance torque T d The selector 77 also functions as a slip detection unit that detects slip of the front wheels 22 or the rear wheels 32 caused by changes in the wheel loads. Furthermore, the selector 77 also functions as a slip suppression unit that reduces or suppresses the vehicle external disturbance torque T corresponding to changes in the wheel loads of the front wheels 22 and the rear wheels 32. d The slip of the front wheel 22 or the rear wheel 32 caused by the change of the wheel load is suppressed by the change of the wheel load. In addition, slip refers to the rotation speed difference between the front wheel 22 and the rear wheel 32 as the driving wheels. As mentioned above, in addition to the vehicle external disturbance torque T d In addition to being output to the second torque target value calculation unit 53, the selector 77 also outputs the vehicle external disturbance torque T d The result is output to the distribution ratio calculation unit 78 .

[0178] [Mathematical formula 26]

[0179]

[0180] Furthermore, the external disturbances acting on the electric vehicle 100 include air resistance, modeling errors caused by the actual vehicle mass due to the number of passengers and load, tire rolling resistance, and slope resistance. Among these, slope resistance is dominant when the electric vehicle 100 is about to stop. The factors of these external disturbances vary depending on the specific operating conditions, but the external disturbance torque estimating unit 52 estimates the torque based on the previous torque command value T as described above. mf1 *, rear torque command value T mr1 * and equivalent mass M V The vehicle's external disturbance torque T d Therefore, the above-mentioned external disturbance factors can be estimated collectively. dBy controlling the output torque of the front motor 21 and the rear motor 31 , the electric vehicle 100 can be reliably controlled under various operating conditions.

[0181] The distribution ratio calculation unit 78 calculates the first drive wheel external disturbance torque T df and the external disturbance torque T of the second driving wheel dr , and the vehicle external disturbance torque T d For the distribution ratio K f3 Perform calculations.

[0182] Figure 8 78 is a block diagram showing the structure of the distribution ratio calculation unit 78. Figure 8 As shown, the distribution ratio calculation unit 78 includes a first distribution ratio calculation unit 81 , a second distribution ratio calculation unit 82 , and a third distribution ratio calculation unit 83 .

[0183] The first distribution ratio calculation unit 81 is based on the vehicle external disturbance torque T d For the first distribution ratio K f1 Perform calculation. The first distribution ratio K f1 This is the basic distribution ratio of the driving force under an ideal state where the wheel load of the driving wheel does not change. In this embodiment, the first distribution ratio calculation unit 81 uses the external disturbance torque T d Transfer characteristic G to distribution ratio of driving force dN1 (s), the first distribution ratio K is calculated according to the following formula (45): f1 Perform calculation. Transfer characteristic G dN1 (s) Utilization coefficient K dN1 It is expressed by the following formula (46). dN1 It is appropriately defined in advance based on experiments, simulations, or the like.

[0184] [Mathematical formula 27]

[0185] K f1 =0.5-G dN1 (s)T d (45)

[0186]

[0187] The second distribution ratio calculation unit 82 is composed of, for example, a first calculation unit 84 and a second calculation unit 85. The first calculation unit 84 calculates the first drive wheel external disturbance torque T df and the external disturbance torque T of the second driving wheel dr The deviation of the external disturbance torque of the driving wheel is ΔT d In this embodiment, the first calculation unit 84 calculates the driving wheel external disturbance torque deviation from the first driving wheel external disturbance torque T dfSubtract the external disturbance torque T of the second driving wheel dr The external disturbance torque deviation of the driving wheel ΔT d The second calculation unit 85 uses the external disturbance torque deviation ΔT from the drive wheel to calculate d Transfer characteristic G to distribution ratio of driving force dN2 (s), the second distribution ratio K is calculated according to the following formula (47): f2 In this embodiment, as shown in the following formula (48), the transfer characteristic G dN2 (s) is a coefficient K appropriately determined in advance based on experiments or simulations. dN2 . The second distribution ratio K f2 The first distribution ratio K is the basic distribution ratio. f1 The distribution ratio that works by the correction term or adjustment term is the external disturbance torque T of the first driving wheel. df and the external disturbance torque T of the second driving wheel dr Works when there are differences.

[0188] [Mathematical formula 28]

[0189] K f2 =(T df -T dr )G dN2 (s) (47)

[0190] G dN2 (s) = K dN2 (48)

[0191] In addition, the transfer characteristic G dN2 (s) can be set as a transfer characteristic with a first-order lag as shown in the following formula (49).

[0192] [Mathematical formula 29]

[0193]

[0194] The third distribution ratio calculation unit 83 calculates the distribution ratio K based on the first distribution ratio K. f1 and the second distribution ratio K f2 The final distribution ratio of driving force is K f3 In this embodiment, the third distribution ratio calculation unit 83 is a subtractor, which calculates the third distribution ratio K from the first distribution ratio K. f1 Subtract the second distribution ratio K f2 For the distribution ratio K f3 As mentioned above, in the electric vehicle 100, according to the distribution ratio K f3 The third torque target value T m3 * Assigned to the front torque command value Tmf1 * The torque command value T mr1 * , thereby distributing driving force to the front wheels 22 and the rear wheels 32. Therefore, even if there is a difference in wheel load between the front wheels 22 and the rear wheels 32 due to the gradient of the road, for example, appropriate driving force corresponding to the situation is distributed to the front wheels 22 and the rear wheels 32.

[0195] Vibration reduction control

[0196] Figure 9 : is a block diagram showing a structure for executing the vibration reduction control S14. Figure 9 As shown, the motor controller 14 functions as a feedforward compensator 91 and a feedback compensator 92 .

[0197] The feedforward compensator 91 is based on the forward torque command value T mf1 * The torque command value T mr1 * The second front torque command value T mf2 * and the second rear torque command value T mr2 * , estimated rotational angular velocity ω of the front motor 21 mf ^ and the estimated rotational angular velocity ω of the rear motor 31 mr ^Calculation is performed. Second front torque command value T mf2 * The second torque command value T after feedforward compensation. mr2 * It is the torque command value after feedforward compensation.

[0198] Figure 10 is a block diagram showing a vehicle model of the electric vehicle 100. Figure 10 The details of the vehicle model shown are as described above. Figure 11 is a block diagram of the feedforward compensator 91. Figure 10 and Figure 11 As shown, the feedforward compensator 91 is configured by adding torsional vibration compensators 101 and 102 and dead zone models 103 and 104 to the vehicle model of the electric vehicle 100 .

[0199] The torsional vibration compensation unit 101 is configured to compensate for the torque command value T mf1 * The torsional vibration compensating unit 101 compensates for the torsional vibration of the drive shaft 27 of the front drive system 11. The torsional vibration compensating unit 101 calculates the estimated torsional angular velocity φ of the drive shaft 27. fis multiplied by the gain k1 to calculate a torsional vibration compensation value. Also, the torsional vibration compensation section 101 calculates a second front torque command value T mf1 * is subtracted from the torsional vibration compensation value (k1φ f ) to calculate a first front torque command value T mf2 * .

[0200] Regarding the transmission characteristics of the torque from the front motor torque T mf to the torque of the drive shaft 27 (hereinafter referred to as the drive shaft torque T DSf ), in the case where the attenuation coefficient appearing in the denominator is designed to be "1", the gain k1 is represented by the following equation (50). Further, ζ pf is the attenuation coefficient of the torque transmission system of the front drive system 11. ω pf is the natural vibration frequency of the torque transmission system of the front drive system 11. g tf is the stable gain from the front motor torque T mf to the drive shaft torque T DSf .

[0201] [Equation 30]

[0202] k1 = 2(1 - ζ pf )ω pf K df / g tf (50)

[0203] The torsional vibration compensation section 102 compensates for the torsional vibration of the drive shaft 37 of the rear drive system 12 with respect to the rear torque command value T mr1 * . The torsional vibration compensation section 102 calculates a torsional vibration compensation value by multiplying the estimated torsional angular velocity φ r of the drive shaft 37 by the gain k2. Also, the torsional vibration compensation section 102 calculates a second rear torque command value T mr1 * by subtracting the torsional vibration compensation value (k2φ r ) from the rear torque command value T mr2 * .

[0204] The gain k2 is set in the same manner as the gain k1. That is, regarding the transmission characteristics of the torque from the rear motor torque T mr to the torque of the drive shaft 37 (hereinafter referred to as the drive shaft torque T DSr ), in the case where the attenuation coefficient appearing in the denominator is designed to be "1", the gain k2 is represented by the following equation (51). Further, ζ pr is the attenuation coefficient of the torque transmission system of the rear drive system 12. ω pris an inherent vibration frequency of the torque transmission system of the rear drive system 12. g tr is a torque from the rear motor Tmr to the drive shaft T D Sr is a stable gain.

[0205] [Equation 31]

[0206] k2 = 2(1 - ζ pr )ω pr K dr / g tr (51)

[0207] The insensitive region model 103 is a model that simulates the back lash characteristics of the gear used in the front drive system 11. The insensitive region model 103 is represented by Equation (52) below. Likewise, the insensitive region model 104 is a model that simulates the back lash characteristics of the gear used in the rear drive system 12. The insensitive region model 104 is represented by Equation (53) below. Further, θ df and θ dr are the torsion angles, and θ deadf and θ deadr are the angles of the insensitive regions (back lash characteristics).

[0208] [Equation 32]

[0209]

[0210] The feedback compensator 92 (refer to Figure 9 ) operates the front final torque command value T mf2 * based on the 2nd front torque command value T mf , the estimated rotational angular velocity ω mf of the front motor 21, and the actual rotational angular velocity ω mff * of the front motor 21. In addition, the feedback compensator 92 operates the rear final torque command value T mr2 * based on the 2nd rear torque command value T mr , the estimated rotational angular velocity ω mr of the rear motor 31, and the actual rotational angular velocity ω mrf * of the rear motor 31. Specifically, the feedback compensator 92 has a 1st feedback operation section 93 that operates the front final torque command value T mff * , and a 2nd feedback operation section 94 that operates the rear final torque command value T mrf * . The feedback compensator 92 is realized by, for example, a microcomputer.

[0211] The first feedback calculation unit 93 includes a deviation calculation unit 93a, a feedback torque calculation unit 93b, and a compensation unit 93c. The deviation calculation unit 93a calculates the estimated rotational angular velocity ω of the front motor 21. mf ^ and the actual angular velocity ω mf Deviation Δω mf In this embodiment, the deviation calculation unit 93a calculates the estimated rotation angular velocity ω from the mf ^ minus the actual angular velocity ω mf And for the deviation Δω mf The feedback torque calculation unit 93b calculates the feedback torque based on the deviation Δω. mf For the second front torque command value T mf2 * Feedback torque T mf3 * The compensation unit 93c calculates the second front torque command value T mf2 * and feedback torque T mf3 * The final torque command value T mff * In this embodiment, the compensation unit 93c calculates the second front torque command value T mf2 * Add feedback torque T mf3 * The final torque command value T mff * Perform calculations.

[0212] The feedback torque calculation unit 93b is formed by using a bandpass filter H f (S) and the aforementioned transfer characteristic G pff (s) filter H f (s) / G pff (s). The band-pass filter Hf(s) is set so that the attenuation characteristics of the low-pass side and the high-pass side are roughly the same, and the torsional resonance frequency of the front drive system 11 is located approximately in the center of the pass bandwidth on the logarithmic axis. In the case of a 1st-order low-pass filter and a 1st-order high-pass filter, the band-pass filter Hf(s) is set so that the attenuation characteristics of the low-pass side and the high-pass side are roughly the same, and the torsional resonance frequency of the front drive system 11 is located in the center of the pass bandwidth on the logarithmic axis. f (s) is expressed by the following equation (54). The time constant and cutoff frequency are expressed by the following equations (55) to (58). pf ” is the torsional resonance frequency of the front drive system 11. In addition, “k f ” is a coefficient appropriately specified in advance based on experiments or simulations.

[0213] [Mathematical formula 33]

[0214]

[0215] τ Lf =1 / (2πf HCf ) (55)

[0216] f HCf =k f ·f pf (56)

[0217] τ Hf =1 / (2πf LCf ) (57)

[0218] f LCf =f pf / k f (58)

[0219] The second feedback calculation unit 94 is configured similarly to the first feedback calculation unit 93 described above. Specifically, the second feedback calculation unit 94 includes a deviation calculation unit 94a, a feedback torque calculation unit 94b, and a compensation unit 94c. The deviation calculation unit 94a calculates the estimated rotational angular velocity ω of the rear motor 31. mr ^ and the actual rotational angular velocity ω mr Deviation Δω mr The feedback torque calculation unit 94b calculates the feedback torque based on the deviation Δω. mr For the second rear torque command value T mr2 * Feedback torque T mr3 * The compensation unit 94c calculates the second rear torque command value T mr2 * and feedback torque T mr3 * The final torque command value T mrf * Perform calculations.

[0220] The feedback torque calculation unit 94b is composed of a band-pass filter H r (s) and the aforementioned transfer characteristic G prr (s) filter H r (S) / G prr (s) composition. Bandpass filter H r (s) is set so that the attenuation characteristics of the low-pass side and the high-pass side are roughly the same, and the torsional resonance frequency of the rear drive system 12 is approximately in the center of the pass bandwidth on the logarithmic axis. In the case of a configuration consisting of a first-order low-pass filter and a first-order high-pass filter, the band-pass filter H r (s) is expressed by the following equation (59). The time constant and cutoff frequency are expressed by the following equations (60) to (63). pr ” is the torsional resonance frequency of the rear drive system 12. In addition, “kr is a coefficient that is appropriately set in advance based on experiments or simulations.

[0221] [Equation 34]

[0222]

[0223] τ Lr = 1 / (2πf Hcr ) (60)

[0224] f HCr = k r · f pr (61)

[0225] τ Hr = 1 / (2πf LCr ) (62)

[0226] f LCr = f pr / k r (63)

[0227] <Effects>

[0228] Next, the effects of the electric vehicle 100 according to the present embodiment configured in the above-described manner are described in comparison with the comparative example. Here, as one example, a scene in which the stop control S13 is executed on an uphill road of a constant slope and a low-friction road surface is described. The comparative example is an example in which the external disturbance torque (vehicle external disturbance torque T d ) that reduces the input errors of the front motor torque Tmf and the rear motor torque Tmr, respectively, is estimated as if the external disturbance torque acts on the rear wheel 32 and the front wheel 22, respectively, and the stop control S13 is executed based on the external disturbance torque. In addition, in the comparative example, the distribution ratio of the driving force with respect to the front wheel 22 and the rear wheel 32 is a fixed value (1:1 here) that is set in advance.

[0229] Figure 12 is a time chart that shows the progress of the torque command value T * , the vehicle body speed V, the front-rear acceleration A c , and the external disturbance torque T d of the comparative example and the control of the present embodiment. Figure 12 (A) to Figure 12 (D) show the progress of the torque command value T * , the vehicle body speed V, the front-rear acceleration A c , and the external disturbance torque T d of the comparative example, respectively. Figure 12 (E) to Figure 12 (H) show the torque command value T* the front final torque command value T mff * and the rear final torque command value T mrf * , the vehicle body speed V, the front-rear acceleration A c and the external disturbance torque T d of the vehicle. Figure 12 (C) and Figure 12 (G) of "A c * " is the front-rear acceleration matched to the road surface gradient. Figure 12 (D) and Figure 12 (H) of "T d * " is the external disturbance torque caused by the road surface gradient. Figure 12 (A) to Figure 12 (H) is the time at which it is determined that the vehicle is about to stop and the stop control S13 is started. Also, slip occurs between the time tl and the time t2 due to changes in the wheel loads of the front wheels 22 and the rear wheels 32.

[0230] As Figure 12 (A) to Figure 12 (H) show, if the stop control S13 is started at the time tl due to deceleration starting from the time tO, the vehicle body speed V gradually approaches zero until the time t3 as shown in Figure 12 (B) and Figure 12 (F) by the stop control S13. Also, as shown in Figure 12 (D) and Figure 12 (H), in either case of the control of the embodiment and the control of the comparative example, the estimated external disturbance torque T d is substantially close to the external disturbance torque T d * caused by the road surface gradient until the time t2.

[0231] At this time, in the control of the comparative example, as shown in Figure 12 (D), slip occurs due to changes in the wheel loads of the front wheels 22 and the rear wheels 32, so that after the time t2, the estimated external disturbance torque T d deviates from the actual external disturbance torque T d * caused by the road surface gradient. Therefore, in the control of the comparative example, as shown in Figure 12 (C), after the start of the stop control S13, the front-rear acceleration A c does not reach the front-rear acceleration A c * matched to the road surface gradient. As a result, as shown inFigure 12 (B) shows that, in the control of the comparative example, after the electric vehicle 100 temporarily stops, the stopped state cannot be maintained and slips down.

[0232] On the other hand, in the control of the present embodiment, as shown in Figure 12 (H), when slip occurs due to a change in the wheel load of the front wheels 22 and the rear wheels 32, the actual state of the vehicle external disturbance torque T d is switched to the driving-wheel external disturbance torque estimated with respect to the driving wheel that is not slipping. Therefore, the accuracy of the estimated vehicle external disturbance torque T d is maintained even after time t2, and the vehicle external disturbance torque T d gradually approaches the actual external disturbance torque T d * caused by the road surface slope. In addition, as shown in Figure 13 (E), the appropriate driving force is distributed to the front wheels 22 and the rear wheels 32 in accordance with a change in the wheel load of the front wheels 22 and the rear wheels 32, and the like. Therefore, in the control of the present embodiment, as shown in Figure 14 (G), after the start of the stop control S13, the front-rear acceleration A c gradually approaches the front-rear acceleration A c * that matches the road surface slope. Moreover, as shown in Figure 14 (F), the electric vehicle 100 is able to stop by the stop control S13 and maintain the stopped state.

[0233] In the above-described embodiment, the electric vehicle 100 having the front drive system 11 and the rear drive system 12 and the front wheels 22 and the rear wheels 32 as the driving wheels was described as an example, but the present application can be appropriately implemented even for an electric vehicle of a different mode. In each of the following modified examples, the structure of another mode of electric vehicle in which the present application can be appropriately implemented is described. However, in each of the modified examples, the same structure as that of the above-described embodiment or other modified examples is denoted by the same reference numeral and the description thereof is omitted. In addition, in each of the modified examples, the specific control mode of the vehicle external disturbance torque T d is the same as that of the above-described embodiment.

[0234] [First Modified Example]

[0235] Figure 15is a block diagram showing the structure of an electric vehicle 130 to which the first modification pertains. The electric vehicle 130 has a right rear wheel drive system 131 that drives a right rear wheel 32R with a first rear motor 31R, and a left rear wheel drive system 132 that drives a left rear wheel 32L with a second rear motor 31L. That is, the electric vehicle 130 has the right rear wheel 32R and the left rear wheel 32L that are drive wheels driven independently of each other, and the first rear motor 31R and the second rear motor 31L that respectively cause the above drive wheels to generate driving force.

[0236] The right rear wheel drive system 131 has, in addition to the right rear wheel 32R and the first rear motor 31R, a first rear inverter 33R, a rotation sensor 34R, a current sensor 35R, a first rear speed reducer 36R, and a drive shaft 37R. Also, the left rear wheel drive system 132 has, in addition to the left rear wheel 32L and the second rear motor 31L, a second rear inverter 33L, a rotation sensor 34R, a current sensor 35R, a second rear speed reducer 36L, and a drive shaft 37L. The functions and the like of the above structure are the same as those of the corresponding structure of the front drive system 11 or the rear drive system 12 of the above embodiment. Therefore, the motor controller 14 is able to perform the same control as in the above embodiment with respect to the right rear wheel drive system 131 and the left rear wheel drive system 132 by using the three-phase current i ur1 , i vr1 , i wr1 , and the rotor phase a r1 , and the three-phase current i ur2 , i vr2 , i wr2 , and the rotor phase a r2 of the second rear motor 31L.

[0237] Further, in the first modification, the electric vehicle 130 in which the right rear wheel 32R and the left rear wheel 32L are provided as drive wheels is described, but the present application can be appropriately implemented with respect to an electric vehicle in which a right front wheel and a right rear wheel are provided as drive wheels.

[0238] [Second Modification]

[0239] Figure 15 is a block diagram showing the structure of an electric vehicle 140 to which the second modification pertains. As shown in ​ , the electric vehicle 140 provides the front wheel 22, the right rear wheel 32R, and the left rear wheel 32L as drive wheels, respectively. The structure of the front drive system 11 that drives the front wheel 22 is the same as in the above embodiment. Also, the structure of the right rear wheel drive system 131 that drives the right rear wheel 32R, and the structure of the left rear wheel drive system 132 that drives the left rear wheel 32L are the same as in the above first modification.

[0240] In the electric vehicle 140, the motor controller 14 is able to perform the same control as the above-described embodiment by using the respective three-phase currents and the respective rotor phases of the front motor 21, the 1st rear motor 31R, and the 2nd rear motor 31L. Specifically, the motor controller 14 calculates the drive-wheel-external-disturbance torque with respect to the front wheel 22, the right rear wheel 32R, and the left rear wheel 32L, respectively, and sets the above-described minimum value or maximum value as the vehicle-external-disturbance torque T d , thereby being able to perform the same control as the above-described embodiment.

[0241] Further, the present application is described herein by way of example with the electric vehicle 140 in which the front wheel 22, the right rear wheel 32R, and the left rear wheel 32L are set as the drive wheels, but the present application can be appropriately implemented for an electric vehicle in which the right front wheel 22R, the left front wheel 22L, and the rear wheel 32 are set as the drive wheels.

[0242] [3rd Modification]

[0243] ​ is a block diagram showing the structure of an electric vehicle 150 to which the 3rd modification is applied. As shown in ​ , the electric vehicle 150 sets the right front wheel 22R, the left front wheel 22L, the right rear wheel 32R, and the left rear wheel 32L as the drive wheels, respectively. Therefore, the electric vehicle 150 has a right front wheel drive system 151, a left front wheel drive system 152, a right rear wheel drive system 131, and a left rear wheel drive system 132.

[0244] The right front wheel drive system 151 drives the right front wheel 22R by using the 1st front motor 21R. The right front wheel drive system 151 has, in addition to the right front wheel 22R and the 1st front motor 21R, a 1st front inverter 23R, a rotation sensor 24R, a current sensor 25R, a 1st front speed reducer 26R, and a drive shaft 27R. In addition, the left front wheel drive system 152 drives the left front wheel 22L by using the 2nd front motor 21L. The left front wheel drive system 152 has, in addition to the left front wheel 22L and the 2nd front motor 21L, a 2nd front inverter 23L, a rotation sensor 24L, a current sensor 25L, a 1st front speed reducer 26L, and a drive shaft 27L. The functions and the like of the above-described structure are the same as those of the corresponding structure of the front drive system 11 or the rear drive system 12 of the above-described embodiment. The three-phase currents i uf1 , i vf1 , i wf1 , and the rotor phase a f1 of the 1st front motor 21R and the three-phase currents i uf2 , i vf2 , i wf2 , and the rotor phase a f2is input to the motor controller 14. In addition, the right rear wheel drive system 131 and the left rear wheel drive system 132 are the same structure as the above-described first modification example or second modification example.

[0245] In the electric vehicle 150, the motor controller 14 is able to perform the same control as the above-described embodiment by using each three-phase current and each rotor phase of the first front motor 21R, the second front motor 21L, the first rear motor 31R, and the second rear motor 31L. Specifically, the motor controller 14 calculates the drive wheel external disturbance torque with respect to the right front wheel 22R, the left front wheel 22L, the right rear wheel 32R, and the left rear wheel 32L, respectively, and sets the above-described minimum value or maximum value to the vehicle external disturbance torque T d , whereby the same control as the above-described embodiment can be performed.

[0246] Further, the above-described embodiment and each modification example are described taking the electric vehicle 150 in which the right front wheel 22R, the left front wheel 22L, the right rear wheel 32R, and the left rear wheel 32L are set as the drive wheels as an example, but the present application can be appropriately implemented for an electric vehicle having five or more drive wheels.

[0247] In the above-described embodiment and each modification example, the vehicle external disturbance torque T d is adjusted by the distribution ratio K f3 , and the stop control S13 is performed, but this is one example of a specific usage of the vehicle external disturbance torque T d . Therefore, the vehicle external disturbance torque T d estimated in the above-described embodiment and each modification example can be used for the stop control S13 (calculation of the second torque target value T m2 * , and only for adjustment of the distribution ratio K f3 . In addition, the vehicle external disturbance torque T d estimated in the above-described embodiment and each modification example can not be used for adjustment of the distribution ratio K f3 , and only for the stop control S13 (calculation of the second torque target value T m2 * . Furthermore, the vehicle external disturbance torque T d estimated in the above-described embodiment and each modification example can be used for control other than adjustment of the distribution ratio K f3 and the stop control S13 (calculation of the second torque target value T m2 * .

[0248] The configuration for executing the vibration damping control S14 in the above embodiment and its modifications is an example. The vibration damping control S14 can be executed by feedforward control and feedback control in a manner different from the feedforward compensator 91 and feedback compensator 92 described in the above embodiment and the like.

[0249] As described above, the control method of the electric vehicle according to the above embodiment and various modifications is a control method for an electric vehicle (e.g., electric vehicle 100) having: a plurality of drive wheels (e.g., front wheels 22 and rear wheels 32); and a plurality of motors (e.g., front motor 21 and rear motor 31) that generate drive forces for the plurality of drive wheels. In this control method, the rotational speed (e.g., rotational angular velocity ω) of the electric motor is determined based on the rotational speed of the electric motor. mf 、ω mv ), the vehicle body speed (for example, the first estimated vehicle body speed V f ^ and the second estimated vehicle body speed V r Furthermore, based on the vehicle body speed estimated for each driving wheel, the external disturbance torque acting on the driving wheel, that is, the driving wheel external disturbance torque (for example, the first driving wheel external disturbance torque T df and the external disturbance torque T of the second driving wheel dr ) is estimated. Based on the driving wheel external disturbance torque estimated for each driving wheel, the actual external disturbance torque acting on the electric vehicle as a whole, that is, the vehicle external disturbance torque T d The vehicle external disturbance torque T is estimated based on the vehicle external disturbance torque T d Instead, the torques to be output to each of the plurality of electric motors are controlled.

[0250] In this way, the external disturbance torque (driving wheel external disturbance torque) is estimated for each driving wheel, and the real external disturbance torque (vehicle external disturbance torque T d ) is estimated, thereby being able to accurately estimate the true external disturbance torque without relying on changes in the wheel load of the drive wheel. d By controlling the output torque of each electric motor, the electric vehicle is reliably controlled regardless of changes in the wheel load of the drive wheels.

[0251] In the above-mentioned embodiment and various modifications, in particular, the torque to be output to the plurality of drive wheels (for example, the front final torque command value T mff * And the final torque command value T mrf * ) is the total torque T m *Calculate. And, based on the total torque T m * The external disturbance torque of the driving wheel and the external disturbance torque of the vehicle T d Perform calculations.

[0252] In this way, based on the total torque T m * The external disturbance torque on the driving wheel and the vehicle external disturbance torque T d The calculation is performed to accurately calculate the external disturbance torque of the driving wheel and the external disturbance torque of the vehicle T d More specifically, by using the total torque T m * The external disturbance torque of the driving wheel is accurately calculated based on the total torque T. m * And the accurate driving wheel external disturbance torque, thus the vehicle external disturbance torque T d It can accurately represent the real external disturbance torque. Therefore, based on the total torque T m * The external disturbance torque of the driving wheel and the external disturbance torque of the vehicle T d By performing the calculation, the electric vehicle is controlled particularly reliably, independent of changes in the wheel load of the drive wheels.

[0253] In the above-described embodiment and modified examples, the vehicle body speed estimated for each driving wheel (for example, the first estimated vehicle body speed V f ^ and the second estimated vehicle body speed V r ^), a torque corresponding to the driving force that the electric vehicle as a whole should exert, that is, a vehicle torque, is estimated for each driving wheel. For example, the first estimated torque T m1 ^ and the third estimated torque T m3 In addition, based on the total torque T m * The vehicle torque is calculated. For example, the second estimated torque T m2 Then, the vehicle torque (first estimated torque T m1 ^ and the third estimated torque T m3 ^) and based on the total torque T m * The estimated vehicle torque (second estimated torque T m2 ^) deviation, the driving wheel external disturbance torque (the first driving wheel external disturbance torque T df and the external disturbance torque T of the second driving wheel dr ) to make an inference.

[0254] Thus, by estimating the vehicle torque based on the vehicle body speed and the total torque T m * the deviation of the estimated vehicle torque, the drive wheel outside disturbance torque is calculated, and thus a particularly accurate drive wheel outside disturbance torque is estimated with respect to each drive wheel. As a result, the estimation accuracy of the vehicle outside disturbance torque T d is also improved. Thus, as described above, by estimating the vehicle torque based on the vehicle body speed and the total torque T m * the deviation of the estimated vehicle torque, the drive wheel outside disturbance torque is calculated, and thus the electric vehicle is particularly reliably controlled regardless of changes in the wheel load of the drive wheels and the like.

[0255] In the above-described embodiment and each modification example and the like, in a case where the total torque T m * is zero or positive, the maximum value of the drive wheel outside disturbance torque estimated with respect to each drive wheel is estimated as the vehicle outside disturbance torque T d . In addition, in a case where the total torque T m * is negative, the minimum value of the drive wheel outside disturbance torque estimated with respect to each drive wheel is estimated as the vehicle outside disturbance torque T d . That is, as indicated by the above-described equation (44).

[0256] If the vehicle outside disturbance torque T d is thus estimated, in a case where an arbitrary drive wheel slips in accordance with changes in the wheel load of each drive wheel, the drive wheel outside disturbance torque estimated with respect to a drive wheel that does not relatively slip (so-called non-slip wheel) becomes the vehicle outside disturbance torque T d . Thus, even if there are changes in the wheel load of each drive wheel, the accuracy of the vehicle outside disturbance torque T d is maintained. As a result, the electric vehicle is particularly reliably controlled regardless of changes in the wheel load of the drive wheels and the like.

[0257] In the above-described embodiment and each modification example and the like, in particular, the distribution ratio K df of the drive force with respect to the drive wheels is set based on the drive wheel outside disturbance torque (for example, the 1st drive wheel outside disturbance torque T dr and the 2nd drive wheel outside disturbance torque T d and the vehicle outside disturbance torque T f3 , and the torque that each of the plurality of electric motors should output is controlled in accordance with the distribution ratio K f3 .

[0258] Thus, by estimating the vehicle torque based on the drive wheel outside disturbance torque and the vehicle outside disturbance torque T dAnd set the distribution ratio K f3 , thereby appropriately distributing the driving force according to changes in the wheel load of the driving wheels, etc. Therefore, the electric vehicle is controlled particularly reliably without depending on changes in the wheel load of the driving wheels, etc. Based on the external disturbance torque of the driving wheels and the external disturbance torque T d The distribution ratio K f3 The setting of can achieve a special effect in the stop control S13, which is the same as explained in the effect of the above embodiment.

[0259] In the above-described embodiment and various modifications, the deviation of the driving wheel external disturbance torque estimated for each driving wheel, ie, the driving wheel external disturbance torque deviation ΔT d Furthermore, based on the driving wheel external disturbance torque deviation ΔT d and the vehicle external disturbance torque T d And set the distribution ratio K f3 .

[0260] In this way, the external disturbance torque deviation ΔT of the driving wheel is d and the vehicle external disturbance torque T d And set the distribution ratio K f3 , so that when a change in the wheel load of the driving wheel occurs, a particularly appropriate distribution ratio K corresponding to the change in the wheel load of the driving wheel is set. f3 Therefore, the electric vehicle is controlled particularly reliably, independent of changes in the wheel load of the drive wheels.

[0261] In the above-mentioned embodiment and each modified example, specifically, based on the vehicle external disturbance torque T d For the first distribution ratio K f1 Calculation is performed based on the driving wheel external disturbance torque deviation ΔT d For the second distribution ratio K f2 Furthermore, based on the first distribution ratio K f1 and the second distribution ratio K f2 The final distribution ratio K is set based on the deviation f3 .

[0262] As mentioned above, the first distribution ratio K f1 This is the basic distribution ratio under ideal conditions without changes in the wheel load of the driving wheel. df and the external disturbance torque T of the second driving wheel dr When there is a difference, that is, when the wheel load of the driving wheel changes, the second distribution ratio K f2 As the distribution ratio K f1 Therefore, as mentioned above, if the first distribution ratio Kf1 and the 2nd distribution ratio K f2 is set based on the deviation of the 1st distribution ratio K f3 from the 2nd distribution ratio K f3 . As a result, the electric vehicle is controlled particularly reliably regardless of the change in the wheel load of the drive wheels and the like.

[0263] In the above-described embodiment and each modification example and the like, the estimated vehicle-external disturbance torque T d is utilized in the stop control S13. Specifically, the vehicle-body-speed feedback torque T f is calculated based on the estimated vehicle-body speed (the 1st estimated vehicle-body speed V r and the 2nd estimated vehicle-body speed V ω ). Further, the torque target value (the 2nd torque target value T d ) that converges to the vehicle-external disturbance torque T ω as the vehicle-body speed decreases is calculated based on the vehicle-external disturbance torque T d and the vehicle-body-speed feedback torque T m2 * . Further, it is determined whether the electric vehicle is about to stop based on the torque target value (the 2nd torque target value T m2 * ). Further, in the case where it is determined that the electric vehicle is about to stop, the torque output by the electric motor (the front motor torque T mf and the rear motor torque T mr ) is controlled to converge to the torque allocated with the 2nd torque target value T f3 based on the distribution ratio K m2 * .

[0264] Thus, by utilizing the estimated vehicle-external disturbance torque T d in the stop control S13, it is possible to stop the electric vehicle and maintain its stopped state even if the change in the wheel load of the drive wheels and the like occurs. That is, the electric vehicle is controlled particularly reliably regardless of the change in the wheel load of the drive wheels and the like.

[0265] The above-described embodiment and each modification example and the like explain only a part of the application examples of the present application, and the gist thereof is not intended to limit the technical scope of the present application.

[0266] For example, the 1st estimated vehicle-body speed V f and the 2nd estimated vehicle-body speed V rThe specific estimation method of T can employ a method other than the method described in the above embodiment. Also, the selector 77 used in the external disturbance torque estimation section 52 can estimate T based on T df and T based on different operations from the operations described in the above embodiment, or the like. dr and set T d . Similarly, the distribution ratio operation section 78 used in the external disturbance torque estimation section 52 can estimate the distribution ratio K based on T df , T dr , and T based on different operations from the operations described in the above embodiment, or the like. d and set K f3 . The same applies to the structure and the like related to the damping control S14, other structures, operations, and the like.

Claims

1. A control method of an electrically driven vehicle having a plurality of drive wheels and a plurality of electric motors that cause the plurality of drive wheels to generate driving force respectively, wherein a vehicle body speed is estimated for each of the drive wheels based on a rotational speed of the electric motor, a driving wheel external disturbance torque that is an external disturbance torque acting on the drive wheel is estimated for each of the drive wheels based on the vehicle body speed estimated for each of the drive wheels, a vehicle external disturbance torque that is a true external disturbance torque acting on the electrically driven vehicle as a whole is estimated based on the driving wheel external disturbance torque estimated for each of the drive wheels, and a torque that each of the plurality of electric motors should output is controlled based on the vehicle external disturbance torque.

2. The control method of an electrically driven vehicle according to claim 1, wherein a total torque that is a sum of the torques that the plurality of drive wheels should output is calculated, and the driving wheel external disturbance torque and the vehicle external disturbance torque are estimated based on the total torque.

3. The control method of an electrically driven vehicle according to claim 2, wherein a vehicle torque that is a torque corresponding to the driving force that the electrically driven vehicle as a whole should exert is estimated for each of the drive wheels based on the vehicle body speed estimated for each of the drive wheels, the vehicle torque is estimated based on the total torque, and the driving wheel external disturbance torque is estimated from a deviation between the vehicle torque estimated based on the vehicle body speed and the vehicle torque estimated based on the total torque.

4. The control method of an electrically driven vehicle according to claim 2 or 3, wherein in a case where the total torque is zero or positive, a maximum value of the driving wheel external disturbance torque estimated for each of the drive wheels is estimated as the vehicle external disturbance torque, and in a case where the total torque is negative, a minimum value of the driving wheel external disturbance torque estimated for each of the drive wheels is estimated as the vehicle external disturbance torque.

5. The control method of an electrically driven vehicle according to any one of claims 1 to 3, wherein a distribution ratio of the driving force for the drive wheels is set based on the driving wheel external disturbance torque and the vehicle external disturbance torque, and the torque that each of the plurality of electric motors should output is controlled according to the distribution ratio.

6. The control method of an electrically driven vehicle according to claim 5, wherein a driving wheel external disturbance torque deviation that is a deviation of the driving wheel external disturbance torque estimated for each of the drive wheels is calculated, and the distribution ratio is set based on the driving wheel external disturbance torque deviation and the vehicle external disturbance torque.

7. The control method of an electrically driven vehicle according to claim 6, wherein a first distribution ratio is calculated based on the vehicle external disturbance torque, a second distribution ratio is calculated based on the driving wheel external disturbance torque deviation, and the distribution ratio is set based on a deviation between the first distribution ratio and the second distribution ratio.

8. The control method of an electrically driven vehicle according to claim 6 or 7, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ based on the vehicle body speed, a vehicle body speed feedback torque is calculated, based on the vehicle exterior disturbance torque and the vehicle body speed feedback torque, a torque target value that converges to the vehicle exterior disturbance torque as the vehicle body speed decreases is calculated, based on the torque target value, it is determined whether the electric vehicle is about to stop, in a case where it is determined that the electric vehicle is about to stop, the torque output by the electric motor is caused to converge to a torque that is allocated the torque target value in accordance with the allocation ratio.

9. A control device of an electric vehicle that has a plurality of drive wheels and a plurality of electric motors that cause the plurality of drive wheels to generate drive forces, respectively, wherein the control device of the electric vehicle has a vehicle body speed estimation unit that estimates a vehicle body speed for each of the drive wheels based on a rotational speed of the electric motor; a drive wheel exterior disturbance torque estimation unit that estimates, for each of the drive wheels, a drive wheel exterior disturbance torque that is an external disturbance torque acting on the drive wheel based on the vehicle body speed estimated for each of the drive wheels; and a vehicle exterior disturbance torque estimation unit that estimates, as a whole, a vehicle exterior disturbance torque that is a true external disturbance torque acting on the electric vehicle based on the drive wheel exterior disturbance torque estimated for each of the drive wheels, the control device of the electric vehicle controls, based on the vehicle exterior disturbance torque, a torque that each of the plurality of electric motors should output.

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