JP2020205682A - Electric-vehicular control method and control apparatus - Google Patents

Abstract

To provide an electric-vehicular control method applicable to an electric vehicle with all wheels being drive wheels and suppressing slippage of the drive wheel appropriately.SOLUTION: A control method, for use in an electric vehicle having motors 4f, 4r being travel dive sources, includes: calculating a motor torque instruction value; determining whether drive wheels 9f, 9r connected to the motors 4f, 4r is slipping; calculating a wheel drive force estimation value of the drive wheels 9f, 9r on the basis of the motor torque instruction value and a motor rotation speed; calculating a wheel drive force instruction value on the basis of a value that is related to a maximum value or a minimum value of the wheel drive force estimation value; controlling the motors 4f, 4r by using the motor torque instruction value in the case of determining that the drive wheels 9f, 9r are not slipping; calculating a slip suppression control torque instruction value on the basis of the wheel drive force instruction value in the case of determining that the drive wheels 9f, 9r is slipping; and controlling the motor 4f, 4r by using the slip suppression control torque instruction value instead of the motor torque instruction value, thus suppressing a slip.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control method for an electric vehicle and a control device.

Conventionally, in an electric vehicle in which wheels are driven by a motor, when slip of the drive wheels is detected, the slip generated is suppressed by controlling the target rotation speed of the motor connected to the drive wheels based on the speed of the driven wheels. A slip control method is known (see Patent Document 1).

JP-A-2017-158337

However, since the above-mentioned control method disclosed in Patent Document 1 calculates the target rotation speed of the motor based on the speed of the driven wheel, it is premised that the driven wheel is provided. Therefore, the slip control method described above cannot be applied to an electric vehicle in which all wheels are driving wheels and no driven wheels.

An object of the present invention is to provide a technique capable of appropriately suppressing slippage of drive wheels even when applied to an electric vehicle in which all wheels are drive wheels.

The vehicle control method according to one aspect of the present invention is an electric vehicle control method using a motor as a traveling drive source, calculates a motor torque command value, and determines whether or not the drive wheels connected to the motor are slipping. Then, the wheel driving force estimated value of the driving wheel is calculated based on the motor torque command value and the motor rotation speed, and the wheel driving force command value is calculated based on the value correlated with the maximum value or the minimum value of the wheel driving force estimated value. Is calculated. If it is determined that the drive wheels are not slipping, the motor is controlled based on the motor torque command value, and if it is determined that the drive wheels are slipping, the motor is controlled based on the wheel driving force command value. The slip suppression control torque command value is calculated, and the slip suppression control that controls the motor based on the slip suppression control torque command value is executed instead of the motor torque command value.

According to the present invention, the slip suppression control torque command value can be calculated without using the driven wheel speed, and the slip suppression control based on the slip suppression control torque command value can be executed. Therefore, all the wheels are driven wheels. Even if it is applied to a certain electric vehicle, the slip of the drive wheel can be appropriately suppressed.

Embodiments of the present invention will be described in detail below with the accompanying drawings.

FIG. 1 is a block diagram showing a system configuration of an electric vehicle to which the electric vehicle control method of one embodiment is applied. FIG. 2 is a flowchart showing a flow of processing performed by the motor controller of one embodiment. FIG. 3 is a diagram showing an example of an accelerator opening degree-torque table. FIG. 4 is a block diagram that realizes front-rear driving force distribution processing. FIG. 5 is a block diagram showing a slip control calculation processing unit. FIG. 6 is a block diagram showing a slip determination unit. FIG. 7 is a block diagram showing a motor angular acceleration estimation unit. FIG. 8 is a block diagram showing a motor angular acceleration calculation unit. FIG. 9 is a diagram for explaining the equation of motion of a vehicle in which motors are mounted independently in the front and rear directions. FIG. 10 is a block diagram showing a disturbance torque estimation unit. FIG. 11 is a block diagram showing a slip determination calculation unit based on the front motor angular velocity. FIG. 12 is a block diagram showing a slip determination calculation unit based on the angular acceleration of the front motor. FIG. 13 is a block diagram showing a front slip control calculation unit. FIG. 14 is a block diagram showing a front driving force estimation unit. FIG. 15 is a block diagram showing a front driving force command value calculation unit. FIG. 16 is a block diagram showing a front slip suppression control torque calculation unit. FIG. 17 is a block diagram showing a system configuration example of an electric vehicle (left and right wheel drive vehicle) to which the present invention is applied. FIG. 18 is a block diagram showing a system configuration example of an electric vehicle (4WD left and right wheel drive vehicle) to which the present invention is applied. FIG. 19 is a block diagram showing a system configuration example of an electric vehicle (four-wheel independent drive vehicle) to which the present invention is applied. FIG. 20 is a diagram for explaining an example of a control result of the control method of the electric vehicle of one embodiment. FIG. 21 is a diagram for explaining another example of the control result of the control method of the electric vehicle of one embodiment.

[One Embodiment]
First, the system configuration (system configuration 1) of the vehicle to which the present invention is applied will be described.

FIG. 1 is a block diagram showing a main system configuration (system configuration 1) of an electric vehicle to which the first embodiment of the present invention is applied. The electric vehicle here is a vehicle that is provided with at least one drive motor (electric motor) as a drive source of the vehicle and travels by the driving force of the drive motor, and includes an electric vehicle and a hybrid vehicle. ..

The battery 1 discharges the drive power to the front drive motor 4f and the rear drive motor 4r, and is charged by the regenerative power from the front drive motor 4f and the rear drive motor 4r.

The electric motor controller 2 (hereinafter, also simply referred to as controller 2) includes an accelerator opening θ, a rotor phase αf of the front drive motor 4f, a rotor phase αr of the rear drive motor 4r, and a current (three-phase AC) of the front drive motor 4f. In the case of, signals of various vehicle variables indicating the vehicle state such as iu, iv, iwa) and the current of the rear drive motor 4r (iu, iv, iwa in the case of three-phase AC) are input as digital signals. The controller 2 generates PWM signals for controlling the front drive motor 4f and the rear drive motor 4r based on the input signals, respectively. Further, the drive signals of the front inverter 3f and the rear inverter 3r are generated according to the generated PWM signals.

The front inverter 3f and the rear inverter 3r (hereinafter collectively referred to as front / rear inverter 3f and 3r) are two switching elements (for example, power semiconductor elements such as IGBTs and MOS-FETs) provided for each phase. ) Is turned on / off to convert or reverse the direct current supplied from the battery 1fr to alternating current, and a desired current is passed through the front drive motor 4f and the rear drive motor 4r.

The front drive motor 4f (three-phase AC motor) and the rear drive motor 4r (three-phase AC motor) are (hereinafter collectively referred to as front / rear drive motors 4f and 4r, or simply motors 4f and 4r), front / Driving force is generated by the AC current supplied from the rear inverters 3f and 3r, and the front drive wheels 9f and the rear drive are driven via the front reduction gear 5fr, the rear reduction gear 5r, and the front drive shaft 8f and the rear drive shaft 8r. The driving force is transmitted to the wheels 9r (hereinafter collectively referred to as front / rear drive wheels 9f and 9r). Further, the front / rear drive motors 4f and 4r generate regenerative driving force when the front / rear drive wheels 9f and 9r rotate while the vehicle is traveling, thereby converting the kinetic energy of the vehicle into electrical energy. Collect as. In this case, the front / rear inverters 3f and 3r convert the alternating current generated during the regenerative operation into a direct current and supply it to the battery 1.

It should be noted that the front drive wheels 9f described in the present specification indicate the left and right drive wheels in front of the vehicle, and the rear drive wheels 9r indicate the left and right drive wheels in the rear of the vehicle.

The front rotation sensor 6f and the rear rotation sensor 6r are, for example, a resolver and an encoder, and detect the rotor phases αf and αr of the front / rear drive motors 4f and 4r, respectively.

The front wheel rotation speed sensor 10f and the rear wheel rotation speed sensor 10r detect the wheel rotation speeds of the two front drive wheels 9f and the two rear drive wheels 9r, respectively.

FIG. 2 is a flowchart showing a flow of processing performed by the controller 2. The processes according to steps S201 to S205 are programmed to be constantly executed at regular intervals while the vehicle system is running.

In step S201, a signal indicating the vehicle state is input to the controller 2. Here, the signals related to the front / rear configurations required for the control calculation described below are acquired from the sensor input or communication from another controller. In the present embodiment, the controller 2 has a motor rotor phase α (electric angle) [rad], wheel rotation speed ωm [m / s] of each wheel, accelerator opening θ [%], motors 4f, 4r. The motor rotation speed angle speed ω, the three-phase AC currents iu, iv, iw flowing through the motors 4f and 4r, the DC voltage value Vdc (V) of the battery 1, and the steering rotation angle ωstr [rad] (not shown) are input. ..

The three-phase alternating currents iu, iv, and iw flowing through the motors 4f and 4r are acquired by using the current sensors 7f and 7r. However, since the total of the current values of the three phases is 0, the current value of one of the three phases (for example, iw) is not acquired, and the current value of the other two (for example, iu, iv) is calculated. You may.

The rotor phase α (electrical angle) [rad] of the front / rear motor is acquired by using rotation sensors 6f and 6r composed of a resolver, an encoder, or the like. Then, the rotor angular velocity ω [rad / s] of the motor is obtained by differentiating the rotor phase α.

The front / rear motor rotation speed Nm [rpm] is the motor rotation angular velocity ωm (rad / rad /), which is the mechanical angular velocity of the electric motor 4 by dividing the rotor angular velocity ω (electric angle) by the number of pole pairs p of the electric motor. s) is obtained, and it is obtained by multiplying the obtained motor rotation angular velocity ωm by 60 / (2π).

The wheel rotation speed of each of the four wheels is acquired from the wheel rotation speed sensors 10r and 10f. Then, the controller 2 obtains the wheel rotation speed v [m / s] by multiplying each wheel rotation speed by the tire dynamic radius r, and the unit conversion coefficient "m / s" to [km / s] " By multiplying by "3600/1000", the wheel rotation speeds ωwfr, ωwfl, ωwrr, and ωwrl are obtained.

The accelerator opening degree θ (%) is obtained from an accelerator opening degree sensor (not shown). The accelerator opening degree θ (%) may be obtained from another controller such as a vehicle controller (not shown).

The DC voltage value Vdc (V) is detected by a voltage sensor (not shown) provided in the DC power supply line between the battery 1 and the inverter 3. The DC voltage value Vdc (V) may be detected by a signal transmitted from a battery controller (not shown).

The steering rotation angle θstr [rad] is acquired by using a rotation sensor (not shown) composed of a resolver, an encoder, or the like.

In step S202, the controller 2 sets the target torque command value T ^* m (motor torque command value) as the basic target torque required by the driver based on the vehicle information. Specifically, first, the controller 2 makes a target by referring to the accelerator opening-torque table shown in FIG. 3 based on the accelerator opening θ input in step S201 and the calculated front motor rotation speed ωmf. Set the torque command value T ^* m. Next, the controller 2 executes the front-rear driving force distribution process (see FIG. 4) to calculate the front target torque command value T ^* mf and the rear target torque command value T ^* mr.

FIG. 4 is a diagram for explaining the front-rear driving force distribution process. Kf in the figure is a value for distributing the driving force output according to the target torque command value Tm ^* as the driver required torque to the front drive motor 4f and the rear drive motor 4r, and is 0 to 1. Set to a value between. The controller 2 calculates the front target torque command value Tmf ^* for the front drive system by multiplying the target torque command value Tm ^* by Kf set to a value between 0 and 1. At the same time, the controller 2 calculates the rear target torque command value Tmr ^* of the rear drive system by multiplying the target torque command value Tm ^* by 1-Kf.

In step S203, the controller 2 performs slip control calculation processing. In the slip control calculation process of the present embodiment, the final front torque command value T ^* mf_f for suppressing slip and the final rear torque command value T ^* mr_f are calculated. The details of the slip control calculation process of this embodiment will be described later.

In step S204, the controller 2 performs the current command value calculation process. Specifically, the controller 2 is based on the front / rear final torque command values T ^* mf_f and T ^* mr_f calculated in step S203, as well as the front / rear motor rotational angular velocities ωmf and ωm and the DC voltage value Vdc. Obtain the d-axis current target value id ^* and the q-axis current target value iq ^* of the front / rear drive motors 4f and 4r, respectively. Specifically, the controller 2 prepares in advance a table that defines the relationship between the torque command value, the motor rotation angular velocity, and the DC voltage value, and the d-axis current target value and the q-axis current target value. By referring to this table, the d-axis current target value id ^* and the q-axis current target value iq ^* are calculated.

In step S205, current control is performed in the front / rear inverter to match the d-axis current id and the q-axis current iq with the d-axis current target value id ^* and the q-axis current target value iq ^* obtained in step S204, respectively. .. Therefore, first, based on the three-phase AC current values iu, iv, and iw acquired in step S201 and the rotor phase α of the front / rear motors 4f and 4r, the d-axis current id and q-axis current for each motor Find iq. Subsequently, the d-axis and q-axis voltage command values vd and vq are calculated from the deviations between the d-axis and q-axis current command values id ^* and iq ^* and the d-axis and q-axis current id and iq. Here, non-interference control may be applied to the calculated d-axis and q-axis voltage command values vd and vq.

Next, from the d-axis and q-axis voltage command values vd and vq for the front / rear motors 4f and 4r and the rotor phase α of the front / rear motors 4f and 4r, the front / rear motors 4f and 4r, respectively. The three-phase AC voltage command values vu, vv, and vw are obtained. Then, the PWM signals tu (%), tv (%), and tw (%) are obtained from the obtained three-phase AC voltage command values vu, vv, vw and the DC voltage value Vdc. By opening and closing the switching elements of the front / rear inverters 3f and 3r with the PWM signals tu, tv, and tw obtained in this way, the front / rear motors 4f and 4r are set to the final front torque command value T ^* mf_f and the final rear torque. It can be driven by the desired torque indicated by the command value T ^* mr_f.

<Slip control calculation processing>
Hereinafter, the details of the slip control calculation process executed in step S203 will be described.

FIG. 5 is a diagram showing a configuration example of a control block (slip control calculation processing unit 50) for executing slip control calculation processing.

The slip control calculation processing unit 50 includes a slip determination unit 501, a front slip control calculation unit 502, and a rear slip control calculation unit 503.

The slip determination unit 501 has a front target torque command value T ^* mf, a rear target torque command value T ^* mr, a front motor angular velocity ωmf, a rear motor angular velocity ωmr, a right front wheel rotation speed ωwfr, a left front wheel rotation speed ωwfl, and a right rear wheel. Rotation speed ωwrr, left rear wheel rotation speed ωwrl, front driving force command value F ^* f, front driving force estimated value, rear driving force command value F ^* r, and rear driving force estimated value are input, and the front final slip control flag The slip_flg_f and the rear final slip control flag slip_flg_r are output. Details of the slip determination unit 501 will be described later with reference to FIG.

In the formula or the drawing of the present specification, the front driving force estimated value and the rear driving force estimated value are represented by the following reference numerals. However, the symbols of the front driving force estimated value and the rear driving force estimated value in the following sentences are omitted.

The front slip control calculation unit 502 inputs the front final slip control flag slip_flg_f, the front motor angular velocity ωmf, the front target torque command value T ^* mf, and the steering rotation angle θstr, and inputs the front driving force command value F ^* f and the front driving force estimation. The value and the front final torque command value T ^* mf_f are output.

The rear slip control calculation unit 503 inputs the rear final slip control flag slip_flg_r, the rear motor angular velocity ωmr, the rear target torque command value T ^* mr, and the steering rotation angle θstr, and inputs the rear driving force command value F ^* r and the rear driving force estimated value. , And the rear final torque command value T ^* mr_f is output.

<Slip judgment calculation processing>
Hereinafter, the details of the slip determination calculation process executed by the slip determination unit 501 will be described.

FIG. 6 is a diagram showing a configuration example of the slip determination unit 501.

The slip determination unit 501 includes a motor angular acceleration estimation unit 601, a slip determination calculation unit 602 based on the front motor angular velocity, a slip determination calculation unit 603 based on the front motor angular acceleration, a front slip control release determination unit 604, and a front slip determination unit. 605, a slip determination calculation unit 606 based on the rear motor angular velocity, a slip determination calculation unit 607 based on the rear motor angular acceleration, a rear slip control release determination unit 608, and a rear slip determination unit 609 are included.

The motor angular acceleration estimation unit 601 has a front target torque command value T ^* mf, a rear target torque command value T ^* mr, a right front wheel rotation speed ωwfr which is a rotation speed of each wheel, a left front wheel rotation speed ωwfl, and a right rear wheel. The rotation speed ωwrr and the left rear wheel rotation speed ωwrl are input, and the front motor angular acceleration estimated value and the rear motor angular acceleration estimated value are output.

In the formula or the drawing of the present specification, the front motor angular acceleration estimated value and the rear motor angular acceleration estimated value are represented by the following reference numerals. However, the symbols of the front motor angular acceleration estimated value and the rear motor angular acceleration estimated value in the following sentences are omitted.

The slip determination calculation unit 602 based on the front motor angular velocity (hereinafter, also referred to as the front angular velocity slip determination calculation unit 602) inputs the front motor angular acceleration estimated value and the front motor angular velocity ωmf, and outputs the front slip control flag 1 (slip_flg1_f). ..

The slip determination calculation unit 603 based on the front motor angular acceleration (hereinafter, also referred to as the front angular acceleration slip determination calculation unit 603) inputs the front motor angular acceleration estimated value and the front motor angular velocity ωmf, and sets the front slip control flag 2 (slip_flg2_f). Output.

The front slip control release determination unit 604 receives the front drive force estimated value and the front drive force command value F ^* f as inputs, and outputs the front slip control release flag stop_flg_f. The front slip control release flag stop_flg_f is set to 1 when the front driving force estimated value is larger than the absolute value of the value obtained by multiplying the front driving force command value F ^* f by a predetermined gain. The predetermined gain here is a value found in advance by experiments, simulations, etc., and is appropriate as an index for determining that the road surface condition has transitioned to a high μ road in comparison with the front driving force estimated value. The value is set.

The front slip determination unit 605 takes the front slip control flag 1 (slip_flg1_f) and the front slip control flag 2 (slip_flg2_f) as inputs, calculates the logical sum (or) of these, and outputs the front final slip control flag slip_flg_f. .. However, when the front slip control release flag stop_flg_f is 1, it is determined that the road surface condition has changed to a high μ road, and the front final slip control flag slip_flg_f is set to 0. As a result, when the slip suppression control is released, the front final torque command value is the front motor torque calculated from the front slip suppression control torque T ^* msf by the front torque command value switching unit 1304 described later according to the accelerator opening. It is gradually returned to the command value T ^* mr.

The slip determination calculation unit 606 based on the rear motor angular velocity (hereinafter, also referred to as the rear angular velocity slip determination calculation unit 606) receives the estimated value of the rear motor angular acceleration and the rear motor angular velocity ωm and outputs the rear slip control flag 1 (slip_flg1_r).

The slip determination calculation unit 607 based on the rear motor angular acceleration (hereinafter, also referred to as the rear angle acceleration slip determination calculation unit 607) receives the rear motor angular acceleration estimated value and the rear motor angular velocity ωm as inputs, and outputs the rear slip control flag 2 (slip_flg2_r).

The rear slip control release determination unit 608 receives the rear driving force estimated value and the rear driving force command value F ^* r as inputs, and outputs the rear slip control release flag stop_flg_r. The rear slip control release flag stop_flg_r is set to 1 when the estimated rear driving force is larger than the absolute value of the rear driving force command value F ^* r multiplied by a predetermined gain.

The rear slip determination unit 609 takes the rear slip control flag 1 (slip_flg1_r) and the rear slip control flag 2 (slip_flg2_r) as inputs, calculates the logical sum (or) of these, and outputs the rear final slip control flag slip_flg_r. .. However, when the rear slip control release flag stop_flg_r is 1, it is determined that the road surface condition has changed to a high μ road, and the rear final slip control flag slip_flg_r is set to 0. The control after the slip suppression control is released is the same as the control related to the front motor described above.

Next, the details of the motor angular acceleration estimation unit 601 will be described with reference to FIG. 7.

FIG. 7 is a diagram showing a configuration example of a control block that realizes the motor angular acceleration estimation unit 601. The motor angular acceleration estimation unit 601 includes a wheel speed selection unit 701, a disturbance torque estimation unit 702, a control system calculation delay processing unit 703, a motor response delay processing unit 704, motor torque distribution gains 705 and 706, and a motor angle. It includes an acceleration calculation unit 707, sensor signal processing delay processing units 708 and 709, an adder 710, and a subtractor 711.

The adder 710 calculates the target torque command value T ^* m by adding the front target torque command value T ^* mf and the rear target torque command value T ^* mr. The calculated target torque command value T ^* m is output to the wheel speed selection unit 701, the disturbance torque estimation unit 702, and the subtractor 711.

The wheel speed selection unit 701 inputs the right front wheel rotation speed ωwfr, the left front wheel rotation speed ωwfl, the right rear wheel rotation speed ωwrr, and the left rear wheel rotation speed ωwrl, and among the four wheels, the non-slip wheel In other words, the rotation speed of the wheel that seems to be the closest to the actual vehicle body speed is selected and output as the select wheel rotation speed ωv.

When the target torque command value is positive, the wheel speed selection unit 701 of the present embodiment determines that the smallest (slowest) value among the wheel rotation speeds is the closest to the vehicle body speed because the driving force is in the forward direction. Then, the smallest wheel rotation speed among the wheel rotation speeds is output as the select wheel rotation speed ωv. On the other hand, since the driving force of the wheel speed selection unit 701 is in the reverse direction when the target torque command value is negative, the wheel rotation speed is the highest among the wheel rotation speeds on the assumption that the wheel rotation speed is represented by a negative value. It is determined that the large (slow) value is the closest to the vehicle body speed, and the largest wheel rotation speed among the wheel rotation speeds is output as the select wheel rotation speed ωv.

The disturbance torque estimation unit 702 inputs the select wheel rotation speed ωv and the target torque command value T ^* m, and outputs the disturbance torque estimation value Tdist. Details of the method for calculating the disturbance torque estimated value Tdist will be described later with reference to FIG.

Subtractor 711 outputs the corrected target torque command value T ^* m @ 2 calculated by subtracting the disturbance torque estimated value Tdist from the target torque command value T ^* m to the control system operation lag processing unit 703.

In the control system calculation delay processing unit 703 and the motor response delay processing unit 704, the control calculation delay time required for the control calculation including the calculation of the corrected target torque command value T ^* m2 with respect to the corrected target torque command value T ^* m2. First-order delay processing Ga (= 1) using the wasted time processing e- ^{L1s of} L1 and the transfer function Ga (s) that simulates the delay from the input of the corrected target torque command value to the generation of the actual torque. By applying / (τas + 1)), the target torque command value T ^* m3 is calculated after the control system delay calculation.

The motor torque distribution gain 705 is obtained by multiplying Kf, which is set to a value between 0 and 1, by the target torque command value T ^* m3 after the control system delay calculation, so that the front target torque command value T ^* mf3 after the control system delay calculation is performed. Is calculated.

The motor torque distribution gain 706 calculates the rear target torque command value T ^* mr3 after the control system delay calculation by multiplying 1-Kf by the target torque command value T ^* m3 after the control system delay calculation.

The motor angular acceleration calculation unit 707 inputs the front target torque command value T ^* mf3 after the control system delay calculation and the rear target torque command value T ^* mr3 after the control system delay calculation, and sets the front motor angular acceleration estimated value before the delay correction. Outputs the estimated value of rear motor angular acceleration before delay correction. Details of the calculation method of the front motor angular acceleration estimated value before delay correction and the rear motor angular acceleration estimated value before delay correction will be described later with reference to FIG. 8 and the like.

The sensor signal processing delay processing unit 708 processes the time required to detect a signal by various sensors such as rotation sensors 6f and 6r and the detected signal value with respect to the estimated value of the front motor angular acceleration before delay correction. The waste time processing e- ^L2s of the sensor signal processing time L2, which is the time required for the sensor signal processing time, is performed, and the estimated value of the front motor angular acceleration is output.

The sensor signal processing delay processing unit 709 processes the time required to detect a signal with various sensors such as rotation sensors 6f and 6r and the detected signal value with respect to the estimated value of the rear motor angular acceleration before delay correction. The waste time processing e- ^L2s of the sensor signal processing time L2, which is the required time, is performed, and the estimated value of the rear motor angular acceleration is output.

The delay calculation processing of these control systems performed by using the control system calculation delay processing unit 703, the motor response delay processing unit 704, and the sensor signal processing delay processing units 708 and 709 is for controlling the front / rear drive motors 4f and 4r. To detect the time delay required for various calculations, the time delay until the actual torque is generated in the front / rear drive motors 4f and 4r with respect to the motor torque command value, and the vehicle state, and perform a predetermined process. This is a process that takes into consideration the time delay caused by the required time (the time delay caused by the time required to detect and process the signal by various sensors such as the rotation sensor 6 and the wheel rotation speed sensor). The motor angular acceleration estimation unit 701 can reduce the estimation error of the motor angular acceleration estimated value by including at least one of the above-mentioned processing units that execute the delay calculation process for compensating for the delay of these control systems.

Next, the details of the motor angular acceleration calculation unit 707 will be described.

FIG. 8 shows a configuration example of a control block that realizes the motor angular acceleration calculation unit 707. The control block constituting the motor angular acceleration calculation unit 807 shown in FIG. 8 is a vehicle model configured equivalent to the equation of motion of the 4WD vehicle described below with reference to FIG. 9.

FIG. 9 is a diagram modeling the driving force transmission system of the vehicle (4WD vehicle) according to the system configuration 2, and each parameter in the figure is as follows. The auxiliary symbol f indicates the front and r indicates the rear.

Jmf, Jmr: Motor inertia Jwf, Jwr: Drive shaft inertia (for one shaft)
Kdf, Kdr: Torsional rigidity of drive shaft Ktf, Ktr: Coefficient related to friction between tire and road surface Nf, N _r : Overall gear ratio rf, r _r : Tire load radius ωmf, ωmr: Motor rotation angular velocity ω ^ mf, ω ^ mr : Motor rotation angular velocity estimated value θmf, θmr: Motor angle ωwf, ωwr: Drive wheel angular velocity θwf, θwr: Drive wheel angle Tmf, Tmr: Motor torque Tdf, Tdr: Drive shaft torque Ff, Fr: Driving force (for 2 axes)
θdf, θdr: Drive shaft torsion angle V: Body speed M: Body mass

From FIG. 9, the equation of motion of the 4WD vehicle is represented by the following equations (1) to (11).

The dead zone shown in FIG. 8 is a dead zone model that simulates the gear back crash characteristics of the front drive shaft torque Tdf related to the front drive shaft 8f and the rear drive shaft torque Tdr related to the rear drive shaft 8r. It is expressed by the following equation (12).

However, θ _deadf in the equation (12) is the amount of overall gear backlash from the front drive motor 4f to the front drive shaft 8f, and θ _deadr is the overall gear backlash from the rear drive motor 4r to the rear drive shaft 8r. The amount.

Next, the details of the disturbance torque estimation unit 702 will be described with reference to FIG. 10 and the like.

FIG. 10 is a diagram showing a configuration example of a control block that realizes the disturbance torque estimation unit 702. The disturbance torque estimation unit 702 estimates the disturbance torque acting on the motors 4f and 4r. The disturbance torque estimation unit 702 includes a control block 1001, a filter 1002, and a subtractor 1003.

Possible disturbances acting on the vehicle include air resistance, modeling error due to fluctuations in vehicle mass due to the number of occupants and the load capacity, rolling resistance of tires, gradient resistance of the road surface, and the like. Which of these disturbance factors becomes the dominant factor differs depending on the operating conditions, but the disturbance torque estimation unit 702 can collectively estimate the above-mentioned disturbance factors as the disturbance torque acting on the drive motor. ..

The control block 1001 is composed of a low-pass filter H (s) and an inverse system of the vehicle response Gr (s).

The vehicle response Gr (s) is set by the following equation (13) using the equivalent mass obtained from the vehicle body mass M, the motor inertia Jm, and the drive shaft inertia Jw.

The low-pass filter H (s) is a low-pass filter having a transmission characteristic in which the difference between the denominator order and the numerator order is equal to or greater than the difference between the denominator order and the numerator order of the vehicle response Gr (s). ).

In the control block 1001, the rotation speed of the rotating body that correlates with the rotation speed of the drive shaft 9 and represents the speed closest to the vehicle body speed by H (s) / Gr (s) configured as described above. The first motor torque estimated value is calculated by applying the filtering process to the select wheel rotation speed ωv.

In the filter 802, the second motor torque torque estimated value is calculated by filtering the motor torque command value T ^* m by the low-pass filter H1 (s).

In the formula or the drawing of the present specification, the first motor torque estimated value and the second motor torque estimated value are represented by the following reference numerals. However, the symbols of the first motor torque estimated value and the second motor torque estimated value in the following sentences are omitted.

Then, the subtractor 1003 calculates the deviation between the first motor torque estimated value and the second motor torque estimated value to calculate the disturbance torque estimated value Tdist.

Next, the details of the front angular velocity slip determination calculation unit 602 will be described.

<Slip judgment calculation based on front motor angular velocity>
FIG. 11 is a diagram showing a configuration example of a control block that realizes the front angular velocity slip determination calculation unit 602. The front angular velocity slip determination calculation unit 602 includes an initialization processing unit 1101, a motor angular velocity estimation unit 1102, and a slip determination unit 1103.

The initialization processing unit 1101 inputs the front motor angular velocity ωmf and outputs the initialization flag flg_ini. The initialization processing unit 1101 calculates the front motor angular acceleration by differentiating the front motor angular velocity ωmf, and when the absolute value of the front motor angular acceleration is less than a predetermined value, the initialization flag flg_ini is set to 1 and the front motor angle is set to 1. When the absolute value of acceleration is equal to or greater than a predetermined value, the initialization flag flg_ini is set to 0.

The motor angular velocity estimation unit 1102 has an integrator and calculates the front motor angular velocity estimated value by integrating the front motor angular velocity estimated value. The integrator is initialized at the front motor angular velocity ωmf when the initialization flag flg_ini is 1. Since the estimated front motor angular acceleration value is calculated using the transmission characteristics from the front motor torque to the front motor angular acceleration in consideration of the torsional rigidity of the drive system and the gear backlash characteristics, the initialization processing as described above can be performed. By applying this, it is possible to reduce the estimation error of the front motor angular velocity estimated value due to the modeling error of the transmission characteristic. The above-mentioned predetermined value, which is a criterion for whether or not the initialization process is performed, is set to an appropriate value derived in advance by an experiment or the like from the viewpoint of reducing the estimation error of the front motor angular velocity estimated value.

In the formula or the drawing of the present specification, the front motor angular velocity estimated value and the front motor angular acceleration estimated value are represented by the following reference numerals. However, the symbols of the front motor angular velocity estimated value and the front motor angular acceleration estimated value in the following sentences are omitted.

The slip determination unit 1103 calculates the deviation between the front motor angular velocity ωmf and the front motor angular velocity estimated value. Then, when the calculated deviation is equal to or greater than a predetermined value, the slip determination unit 1103 determines that the vehicle has slipped and sets the front slip control flag 1 (slip_flg1_f) to 1. On the other hand, when the calculated deviation is less than a predetermined value, the slip determination unit 1103 determines that the vehicle has not slipped and sets the slip control flag 1 (slip_flg1_f) to 0. The predetermined value here is a value derived in advance by experiments, simulations, etc., and is set to a value that can appropriately determine the slip of the vehicle by comparing the deviation between the front motor angular velocity ωmf and the motor angular velocity estimated value. Will be done.

<Slip judgment calculation based on rear motor angular velocity>
The slip determination calculation unit 606 based on the rear motor angular velocity (see FIG. 6) has the same configuration as the slip determination calculation unit 602 based on the front motor angular velocity (see FIG. 11) described above. However, the rear motor angular velocity ωmr is input to the initialization processing unit 1101, the motor angular velocity estimation unit 1102, and the slip determination unit 1103 instead of the front motor angular velocity ωmf, and the motor angular velocity estimation unit 1102 is used as the motor angular acceleration estimated value. Instead, the estimated value of the rear motor angular acceleration is input.

<Slip judgment calculation based on front motor angular acceleration>
FIG. 12 is a diagram showing a configuration example of a control block that realizes the front angular acceleration slip determination calculation unit 603. The front angular acceleration slip determination calculation unit 603 includes a motor angular acceleration calculation unit 1201 and a slip determination unit 1202.

The front motor angular acceleration calculation unit 1201 calculates the front motor angular acceleration by differentiating the front motor angular velocity ωmf. The calculated front motor angular acceleration is output to the slip determination unit 1202.

The slip determination unit 1202 calculates the deviation between the front motor angular acceleration and the estimated front motor angular acceleration. Then, when the calculated deviation is equal to or greater than a predetermined value, the slip determination unit 1202 determines that the vehicle has slipped and sets the front slip control flag 2 (slip_flag2_f) to 1. Further, when the calculated deviation is less than a predetermined value, the slip determination unit 1202 determines that no slip has occurred and sets the front slip control flag 2 (slip_flag2_f) to 0. The predetermined value here is a value derived in advance by experiments, simulations, etc., and is a value at which the slip of the vehicle can be appropriately determined by comparing the deviation between the front motor angular acceleration and the front motor angular acceleration estimated value. Is set.

<Slip judgment calculation based on rear motor angular acceleration>
The slip determination calculation unit 607 based on the rear motor angular acceleration (see FIG. 6) has the same configuration as the slip determination calculation unit 603 based on the front motor angular acceleration (see FIG. 12) described above. However, the rear motor angular velocity ωmf is input to the motor angular acceleration calculation unit 1201 and the slip determination unit 1202 instead of the front motor angular velocity ωmf, and the rear motor angular acceleration is input to the slip determination unit 1202 instead of the front motor angular acceleration estimated value. An estimate is entered.

<Front slip control calculation>
FIG. 13 is a diagram showing a configuration example of a control block that realizes the front slip control calculation unit 502 (see FIG. 5). The front slip control calculation unit 502 includes a front drive force command value calculation unit 1301, a front drive force estimation unit 1302, a front slip suppression control torque calculation unit 1303, and a front torque command value switching unit 1304.

The front driving force command value calculation unit 1301 inputs the front final slip control flag slip_flg_f, the front driving force estimated value, the front target torque command value T ^* mf, and the steering rotation angle θstr, and inputs the front driving force command value F ^* f. Output. Details of the front driving force command value calculation unit 1301 will be described later with reference to FIG.

The front driving force estimation unit 1302 inputs the front final torque command value T ^* mf_f and the front motor angular velocity ωmf, and outputs the front driving force estimation value. Details of the front driving force estimation unit 1302 will be described later with reference to FIG.

The front slip suppression control torque calculation unit 1303 inputs the front driving force command value F ^* f and the front driving force estimated value, and outputs the front slip control suppression torque T ^* msf. Details of the front slip suppression control torque calculation unit 1303 will be described later with reference to FIG.

The front torque command value switching unit 1304 sets the front slip suppression control torque T ^* msf in the front final torque command value T ^* mf_f when the front final slip control flag slip_flg_f is 1 or more, and when the front final slip control flag slip_flg_f is 0, the front torque command value switching unit 1304 sets the front slip suppression control torque T ^* msf. Set the front target torque command value T ^* mf to the front final torque command value T ^* mf_f.

<Rear slip control calculation>
The rear slip control calculation unit 503 (see FIG. 5) has the same configuration as the front slip control calculation unit 502 (see FIG. 13) described above. However, in the front driving force command value calculation unit 1301 and the front torque command value switching unit 1304, the rear final slip control flag slip_flg_r and the rear final slip control flag slip_flg_r are used instead of the front final slip control flag slip_flg_f and the front final torque command value T ^* mf_f. The torque command value T ^* mr_f is input. Further, the front driving force estimation unit 1302, in place of the front final torque command value T ^* mf_f and the front motor angular Omegamf, a rear final torque command value T ^* mr_f and rear motor angular velocity ωmr is input.

Next, the details of the front driving force estimation unit 1302 will be described.

<Estimated driving force calculation>
FIG. 14 is a diagram showing a configuration example of a control block that realizes the front driving force estimation unit 1302. The front driving force estimation unit includes filters 1401, 1402, and a subtractor 1403.

The filter 1401 is composed of a low-pass filter represented by Ha (s), and the filter 1402 is composed of a low-pass filter represented by Hb (s). The low-pass filters Ha (s) and Hb (s) are as shown in the following equation (16).

First, regarding the above equations (1) and (3), if ωmf / Nf is approximated to ωwf (ωmf / Nf≈ωwf) and the driving force Ff is arranged, it can be expressed by the following equation (15). According to the following equation (15), the front driving force estimated value is based on the front target torque command value Tmf, the front motor rotation angular velocity ωmf, and the transmission characteristics (ka, kb) from the motor rotation speed to the wheel driving force Ft. Can be calculated.

Since the above equation (15) includes the differential term s, processing (LPF processing) using the low-pass filters Ha (s) and Hb (s) is performed and subtraction is performed as shown in (16) below. The front driving force estimated value is calculated by performing the subtraction process using the device 1403.

Regarding the rear driving force estimation value, in the rear driving force estimation unit (not shown) configured in the same manner as the front driving force estimation unit 1302, the front is based on the rear motor angular velocity ωmf and the rear final torque command value T ^* mf_r. It is calculated by performing the same calculation as the above calculation for calculating the driving force estimated value.

Next, the details of the front driving force command value calculation unit 1301 will be described.

<Driving force command value calculation>
FIG. 15 is a diagram showing a configuration example of a control block that realizes the front driving force command value calculation unit 1301. The front driving force command value calculation unit 1301 includes a driving force estimated value peak value calculating unit 1501, a driving force command value adjusting unit 1502, and a driving force estimated value previous processing unit 1503.

The driving force estimated value peak value calculation unit 1501 inputs the front target torque command value T ^* mf, the front driving force estimated value, and the front driving force estimated value peak value previous value, and outputs the front driving force estimated value peak value. .. More specifically, when the front target torque command value T ^* mf is a positive value, the driving force estimated value peak value calculation unit 1501 compares the front driving force estimated value with the front driving force estimated value peak value previous value. Then, the larger value is output as the front driving force estimated value peak value. On the other hand, when the front target torque command value T ^* mf is a negative value, the driving force estimated value peak value calculation unit 1501 compares the front driving force estimated value with the front driving force estimated value peak value previous value. The smaller value is output as the front driving force estimated value peak value.

Then, the driving force command value adjusting unit 1502, which will be described later, calculates the front driving force command value F ^* f according to the front driving force estimated value peak value. Then, the front slip suppression control torque calculation unit 1303, which will be described later, calculates the front slip suppression control torque T ^* mst based on the front driving force command value F ^* f. Here, the magnitude of the front driving force estimated value peak value corresponds to the magnitude of the road surface μ. For example, the peak value of the estimated front driving force is larger on a snow-packed road with a relatively large road surface μ than on a frozen road with a relatively small road surface μ. Therefore, by calculating the front slip suppression control torque T ^* mst according to the front driving force estimated value peak value, it is not necessary to calculate the slip ratio, and the maximum or minimum according to the road surface μ of various road surfaces. Can be calculated as the front slip suppression control torque T ^* mst.

In the formula or the drawing of the present specification, the front driving force estimated value peak value and the front driving force estimated value peak value previous value are represented by the following reference numerals. However, the symbols of the front driving force estimated value peak value and the front driving force estimated value peak value previous value in the following sentences are omitted.

The driving force command value adjusting unit 1502 inputs the front driving force estimated value peak value and the steering rotation angle θstr, and outputs the front driving force command value F ^* f. The front driving force command value F ^* f is calculated by multiplying the front driving force estimated value peak value by a predetermined gain. The gain here is set to, for example, a value of 1 or less for the purpose of adjusting to a more appropriate driving force command value and appropriately generating the stress required for turning.

Further, the predetermined gain here may be changed according to the steering rotation angle θstr. Since the steering rotation angle θstr is related to the degree of turning of the vehicle, slipping during turning can be more preferably suppressed by adjusting the gain according to the steering rotation angle θstr.

The driving force estimated value previous value processing unit 1503 inputs the driving force estimated value peak value and the front final slip control flag Slip_flg_f, and outputs the driving force estimated value peak value previous value. More specifically, the driving force estimated value previous value processing unit 1503 stores the input driving force estimated value peak value and the front final slip control flag Slip_flg_f in the storage medium (memory), and the driving force estimated value peak value. Output the previous value. After that, the driving force estimated value peak value previous value and the front final slip control flag previous value Slip_flg_f_z are updated based on the stored values.

Then, when the front final slip control flag Slip_flg_f and the front final slip control flag previous value Slip_flg_f_z are compared and both are different, the driving force estimated value peak value previous value is reset to 0. As a result, when it is determined that slip has occurred again while slip suppression control is being executed (while it is determined that slip has occurred and the motor is being controlled by the slip suppression control torque), the driving force command is issued. The value can be updated appropriately.

Regarding the rear driving force command value F ^* r, the rear driving force command value estimated value and the rear target torque command value are also provided in the rear driving force command value calculation unit (not shown) configured in the same manner as the front driving force command value calculation unit 1301. It is calculated by performing the same calculation as the above calculation for calculating the front driving force command value F ^* f based on T ^* mr, the rear final slip control flag Slip_flg_r, and the steering rotation angle θstr.

Next, the details of the front slip suppression control torque calculation unit 1303 will be described.

<Slip suppression control torque calculation calculation>
FIG. 16 is a diagram showing a configuration example of a control block that realizes the front slip suppression control torque calculation unit 1303. The front slip suppression control torque calculation unit 1303 includes an integrator 1602, a multiplier 1601, 1603, a subtractor 1604, and an adder 1605.

The subtractor 1604 outputs a value obtained by subtracting the front driving force estimated value from the front driving force command value F ^* f to the integrator 1602 and the multiplier 1601.

The multiplier 1601 outputs a value obtained by multiplying the difference between the front driving force command value F ^* f and the front driving force estimated value by the proportional gain Kp to the adder 1605.

The multiplier 1603 adds a value obtained by multiplying the difference between the front driving force command value F ^* f subjected to the integration processing by the integrator 1602 and the front driving force estimated value by the integrative gain Ki, and the adder 1605. Output to.

Then, the adder 1605 calculates the sum of the value output from the multiplier 1601 and the value output from the multiplier 1603, and outputs the calculated value as the front slip suppression control torque Tmsf. The proportional gain Kp and the integrated gain Ki are appropriately set to values that can reduce the deviation between the front driving force command value F ^* f and the front driving force estimated value and appropriately suppress the slip generated in the front driving wheels. To.

In this way, the front slip suppression control torque Tmsf is calculated without requiring the vehicle body speed, and the slip suppression control based on the front slip suppression control torque Tmsf is executed, so that a vehicle without a driving wheel (for example, a 4WD vehicle) Even if all the drive wheels slip at the same time, the slip that occurs can be appropriately suppressed.

Regarding the rear slip suppression control torque Tmsr, the rear drive force command value F ^* r and the rear drive force estimation are performed by the rear slip suppression control torque calculation unit (not shown) configured in the same manner as the front slip suppression control torque calculation unit 1303. It is calculated by performing the same calculation as the above calculation for calculating the front slip suppression control torque Tmsr based on the value.

The above is a detailed description of the control method of the electric vehicle of the present embodiment when applied to the vehicle of the system configuration 1 shown in FIG. 1, that is, the vehicle having drive motors on the front and rear drive shafts, respectively. However, the vehicle to which the control method of the present embodiment is applied is not limited to the vehicle having the system configuration 1 described above. The control method of the present embodiment can be similarly applied to a vehicle separately provided with a drive motor (4ra) corresponding to the left and right drive wheels (9ra, 9rb) as shown in FIG.

Further, the control method of the present embodiment is applied to a vehicle having three drive motors (4f, 4ra) as shown in FIG. 18 and a vehicle having four drive motors (4fa, 4ra) as shown in FIG. Can be applied in the same way. However, when applied to a vehicle equipped with three or more drive motors, the driving force distribution process is performed according to the number of drive motors (see FIG. 4), and the slip control calculation is performed according to the number of drive motors. (References such as FIGS. 5 to 8 are executed respectively.

Hereinafter, the effects obtained when the electric vehicle control method of the above embodiment is applied will be described with reference to FIGS. 20 and 21.

FIG. 20 is a time chart showing a control result when the control method according to the present invention is applied to a vehicle (system configuration 1) in which motors are independently mounted on the front and rear. This time chart shows the case where the vehicle starts and accelerates at time t0 on a road surface with a relatively low road surface μ (for example, a snow-packed road) and then transitions to a lower road surface μ (for example, a frozen road) at time t3. ing.

The horizontal axis of FIG. 20 is the time, and the vertical axis is the front / rear slip control flag, front / rear driving force (driving force command value, driving force estimated value), front / rear motor torque (target torque command value) in order from the top. , Final torque command value), and front / rear speed (wheel speed, vehicle body speed).

FIG. 20A is a time chart of the front motor. As can be seen from the fact that the front slip control flag is raised, the front wheel slips at time t2. At this time, the front slip suppression control suppresses front wheel slip by calculating the final torque command value based on the discrepancy between the driving force command value and the driving force estimated value. Further, even if slip occurs again due to a change in the road surface μ at time t3, the driving force command value is updated, and the final torque command is based on the difference between the updated driving force command value and the driving force estimated value. The value is calculated, and the slip that occurs again is appropriately suppressed.

FIG. 20B is a time chart of the rear motor. Similar to the front motor described above, the rear wheel slips at time t1. At this time, the rear slip suppression control suppresses the rear wheel slip by calculating the final torque command value based on the discrepancy between the driving force command value and the driving force estimated value. Further, even if slip occurs again due to a change in the road surface μ at time t3, the driving force command value is updated, and the final torque command is based on the difference between the updated driving force command value and the driving force estimated value. The value is calculated, and the slip that occurs again is appropriately suppressed.

As described above, by applying the electric vehicle control method according to the present embodiment, the slip of the front and rear wheels can be appropriately suppressed without requiring the vehicle body speed. Further, according to the control method of the present embodiment, it is possible to appropriately cope with the change of the road surface μ that occurs during the slip suppression control.

FIG. 21 is a time chart showing a control result when the control method according to the present invention is applied to a vehicle (system configuration 1) in which motors are independently mounted in the front and rear as in FIG. 20. This time chart shows the case where the vehicle starts and accelerates at time t0 on a road surface with a relatively low road surface μ (for example, a snow-packed road) and then transitions to a road surface with a high road surface μ (for example, asphalt road) at time t3. Shown.

The horizontal axis of FIG. 21 is the time, and the vertical axis is the front / rear slip control flag, front / rear driving force (driving force command value, driving force estimated value), front / rear motor torque (target torque command value) in order from the top. , Final torque command value), and front / rear speed (wheel speed, vehicle body speed).

FIG. 21A is a time chart of the front motor. As can be seen from the fact that the front slip control flag is raised, the front wheel slips at time t2. At this time, the front slip suppression control suppresses front wheel slip by calculating the final torque command value based on the discrepancy between the driving force command value and the driving force estimated value. Further, when the estimated driving force exceeds a predetermined value for determining the occurrence of slip due to the change in the road surface μ at time t3, the slip control is released and the final torque command value is gradually changed to the target torque command value. I'm letting you.

FIG. 21B is a time chart of the rear motor. Similar to the front motor described above, the rear wheel slips at time t1. At this time, the rear slip suppression control suppresses the rear wheel slip by calculating the final torque command value based on the discrepancy between the driving force command value and the driving force estimated value. Further, when the estimated driving force exceeds a predetermined value for determining the occurrence of slip due to the change in the road surface μ at time t3, the slip control is released and the final torque command value is gradually changed to the target torque command value. I'm letting you.

As described above, by applying the electric vehicle control method according to the present embodiment, slippage of the front and rear wheels can be suppressed on a low μ road. Further, on a high μ road, by making the final torque command value follow the target torque command value, it is possible to generate an appropriate driving force according to the road surface. In addition, by gradually changing the value of the command value for controlling the motor (final torque command value) from the slip suppression control torque command value to the target torque command value, smoothness without causing a torque step or the like. It is possible to shift to normal control.

As described above, according to the electric vehicle control method according to the present invention, it is possible to suppress slippage of the front and rear drive wheels by generating an appropriate driving force according to various road surfaces having different road surfaces μ without using the vehicle body speed. it can.

As described above, the control method of the electric vehicle of one embodiment is a control method of an electric vehicle using a motor (4f, 4r) as a traveling drive source, and is a motor torque command value (front target torque command value T ^* mf, rear target). The torque command value T ^* mr) is calculated, it is determined whether or not the drive wheels (9f, 9r) connected to the motor are slipping, and the drive wheels (9f, 9r) are determined based on the motor torque command value and the motor rotation speed. ) Wheel driving force estimated value (front driving force estimated value, rear driving force estimated value) is calculated, and the maximum or minimum value of the wheel driving force estimated value (front driving force estimated value peak value, rear driving force estimated value peak) The wheel driving force command value (front driving force command value F ^* f, rear driving force command value F ^* r) is calculated based on the value correlated with the value). When it is determined that the drive wheels (9f, 9r) are not slipping, the motors (4f, 4r) are controlled based on the motor torque command values (T ^* mf, T ^* mr) to control the drive wheels (4f, 4r). When it is determined that 9f, 9r) is slipping, the slip suppression control torque command value (slip suppression control torque command value (F) based on the wheel driving force command value (front driving force command value F ^* f, rear driving force command value F ^* r)). Front slip suppression control torque T ^* msf, rear slip suppression control torque T ^* msr) is calculated, and instead of the motor torque command value (T ^* mf, T ^* mr), the slip suppression control torque command value (front slip suppression control) Torque T ^* msf, rear slip suppression control Torque T ^* msr) is used to control the motor (4f, 4r) to perform slip suppression control.

As a result, the slip suppression control torque command value can be calculated without using the vehicle body speed, and the slip suppression control based on the slip suppression control torque command value can be executed. Therefore, for example, a vehicle having no driven wheel. Even when four wheels slip at the same time, the generated slip can be appropriately suppressed.

Further, according to the control method of the electric vehicle of one embodiment, when it is determined that the drive wheels (9f, 9r) are slipping again during the slip suppression control, the drive wheels (9f, 9r) slip again. Wheel driving force command based on a value that correlates with the maximum or minimum value of the wheel driving force estimated value (front driving force estimated value peak value, rear driving force estimated value peak value) from the time when it is determined to be The values (front driving force command value F ^* f, rear driving force command value F ^* r) are updated. As a result, even if slip occurs again during the slip suppression control, the slip suppression control corresponding to the occurrence of the slip again can be appropriately executed.

Further, according to the control method of the electric vehicle of one embodiment, when the wheel driving force estimated value (front driving force estimated value, rear driving force estimated value) exceeds a predetermined value during slip suppression control, slip suppression is performed. The value of the command value (final torque command value) for controlling the motor while releasing the control is calculated from the slip suppression control torque command value (front slip suppression control torque T ^* msf, rear slip suppression control torque T ^* msr). The motor torque command value (front target torque command value T ^* mf, rear target torque command value T ^* mr) is gradually changed. As a result, the slip suppression control can be appropriately released when the road surface with a low road surface μ transitions to a road surface with a relatively high road surface μ. Further, the control based on the slip suppression control torque command value (front slip suppression control torque T ^* msf, rear slip suppression control torque T ^* msr) is gradually changed to the control based on the motor torque command value (T ^* mf, T ^* mr). By shifting, it is possible to suppress a shock caused by a torque step or the like when the slip suppression control is released.

Further, according to the control method of the electric vehicle of one embodiment, the value correlated with the maximum value or the minimum value of the wheel driving force estimated value (front driving force estimated value, rear driving force estimated value) is the wheel driving force. It is calculated by multiplying the maximum value or the minimum value (front driving force estimated value peak value, rear driving force estimated value peak value) by a predetermined gain. As a result, the slip suppression control torque command value calculated in the subsequent stage can be adjusted to a more appropriate value, and the stress required for turning can be generated more appropriately during the slip suppression control.

Further, according to the control method of the electric vehicle of one embodiment, the predetermined gain is set according to the steering angle. As a result, the slip generated when the vehicle turns can be suppressed more appropriately.

Further, according to the control method of the electric vehicle of one embodiment, the motor torque command value (front target torque command value T ^* mf, rear target torque command value T ^* mr) and the motor rotation speed to the wheel driving force. The wheel driving force estimated value (front driving force estimated value, rear driving force estimated value) is calculated based on the transmission characteristics (ka, kb). As a result, the wheel driving force can be suitably estimated without the need for an additional sensor or the like for estimating the wheel driving force.

Further, according to the control method of the electric vehicle of one embodiment, the motor angular velocity of the motor (4f, 4r) is based on the motor torque command value (front target torque command value T ^* mf, rear target torque command value T ^* mr). Is calculated, and whether or not the drive wheels (9f, 9r) are slipping is determined based on the calculated motor angular velocity and the actual motor angular velocity. Further, according to the control method of the electric vehicle of one embodiment, the motor angle of the motor (4f, 4r) is based on the motor torque command value (front target torque command value T ^* mf, rear target torque command value T ^* mr). The acceleration is calculated, and whether or not the drive wheels are slipping is determined based on the calculated motor angular acceleration and the actual motor angular acceleration. As a result, the driving force of the driving wheels can be calculated from the motor torque command value input to the motor (4f, 4r) and the motor rotation speed which is the output, so that the slip states of the plurality of driving wheels are independent. Can be determined.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

2 ... Controller 4, 4f, 4r, 4fa, 4fb, 4ra, 4rb ... Motor (drive motor)
9, 9f, 9r, 9fa, 9fb, 9ra, 9rb ... Drive wheels

Claims (9)

It is a control method for an electric vehicle that uses a motor as a traveling drive source.
Calculate the motor torque command value based on the accelerator opening,
It is determined whether or not the drive wheels connected to the motor are slipping, and
The wheel driving force estimated value of the driving wheel is calculated based on the motor torque command value and the motor rotation speed.
The wheel driving force command value is calculated based on the value correlated with the maximum value or the minimum value of the wheel driving force estimated value.
If it is determined that the drive wheels are not slipping,
The motor is controlled based on the motor torque command value,
If it is determined that the drive wheels are slipping,
The slip suppression control torque command value is calculated based on the wheel driving force command value.
Instead of the motor torque command value, slip suppression control for controlling the motor is executed based on the slip suppression control torque command value.
A method of controlling an electric vehicle, which is characterized in that. In the method for controlling an electric vehicle according to claim 1,
When it is determined that the driving wheels are slipping again during the slip suppression control, the maximum value or the minimum value of the wheel driving force estimated value from the time when the driving wheels are determined to be slipping again. The wheel driving force command value is updated based on the value correlated with.
How to control an electric vehicle. In the method for controlling an electric vehicle according to claim 1 or 2.
When the estimated driving force exceeds a predetermined value during the slip suppression control, the slip suppression control is released and the command value for controlling the motor is set to the slip suppression control torque command value. To gradually change from to the motor torque command value,
How to control an electric vehicle. In the method for controlling an electric vehicle according to any one of claims 1 to 3,
The value correlated with the maximum value or the minimum value of the wheel driving force estimated value is calculated by multiplying the maximum value or the minimum value of the wheel driving force estimated value by a predetermined gain.
How to control an electric vehicle. In the method for controlling an electric vehicle according to claim 4,
The predetermined gain is set according to the steering angle.
How to control an electric vehicle. In the method for controlling an electric vehicle according to any one of claims 1 to 5,
The wheel driving force estimated value is calculated based on the motor torque command value and the transmission characteristics from the motor rotation speed to the wheel driving force.
How to control an electric vehicle. In the method for controlling an electric vehicle according to any one of claims 1 to 6,
The motor angular velocity of the motor is calculated based on the motor torque command value.
It is determined whether or not the drive wheels are slipping based on the calculated motor angular velocity and the actual motor angular velocity.
How to control an electric vehicle. In the method for controlling an electric vehicle according to any one of claims 1 to 6,
The motor angular acceleration of the motor is calculated based on the motor torque command value.
It is determined whether or not the drive wheels are slipping based on the calculated motor angular acceleration and the actual motor angular acceleration.
How to control an electric vehicle. A control device for an electric vehicle including a motor as a traveling drive source and a controller for controlling the motor.
The controller
Calculate the motor torque command value based on the accelerator opening,
It is determined whether or not the drive wheels connected to the motor are slipping, and
The wheel driving force estimated value of the driving wheel is calculated based on the motor torque command value and the motor rotation speed.
The wheel driving force command value is calculated based on the value correlated with the maximum value or the minimum value of the wheel driving force estimated value.
If it is determined that the drive wheels are not slipping,
The motor is controlled based on the motor torque command value,
If it is determined that the drive wheels are slipping,
The slip suppression control torque command value is calculated based on the wheel driving force command value.
Instead of the motor torque command value, slip suppression control for controlling the motor is executed based on the slip suppression control torque command value.
A control device for an electric vehicle.

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