JP2016111777A - Drive power controller of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive power controller of an electric vehicle capable of correcting torque command values of motors and improving straight running performance and turning performance of a vehicle, without requiring a yaw rate sensor.SOLUTION: The drive power controller of an electric vehicle having a right motor 4R for transmitting drive power to a right driven wheel, and a left motor 4L for transmitting drive power to a left driven wheel estimates the torque difference between left and right motors on the basis of a steering angle of the electric vehicle and rotational speed of the left and right motors, and calculates torque command values of the left and right motors, on the basis of the condition of the vehicle. The controller calculates a target motor torque difference being a target value of the torque difference between the left and right motors, on the basis of last torque command values of the left and right motors, and calculates torque correction values of the left and right motors on the basis of the estimated torque difference between the left and right motors, and the target motor torque difference. Subsequently, on the basis of the calculated torque correction values, the controller corrects at least one of the torque command value of the right motor and the torque command value of the left motor.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an apparatus for controlling driving force of an electric vehicle.

  Conventionally, if it is determined that the yaw rate is generated when it is determined that the straight traveling is instructed based on the steering angle, the left and right wheels provided corresponding to the left and right wheels so that the yaw rate matches the target yaw rate. A technique for correcting a torque command value for an electric motor is known (see Patent Document 1). According to this technique, the driving force of each wheel can be controlled as intended to improve straightness and turning performance.

JP 2005-184911 A

  However, in the technique described in Patent Document 1, a torque command value to the left and right electric motors is corrected based on the detected value of the yaw rate, and thus a highly accurate sensor is required to detect a minute yaw rate. There is a high cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a technique capable of correcting a torque command value of a motor without requiring a yaw rate sensor and improving the straight traveling performance and turning performance of the vehicle.

  The driving force control apparatus for an electric vehicle according to the present invention is a driving force control apparatus for an electric vehicle having a right motor that transmits driving force to the right driving wheel and a left motor that transmits driving force to the left driving wheel. Steering angle detecting means for detecting the steering angle, right motor rotating speed detecting means for detecting the rotating speed of the right motor, and left motor rotating speed detecting means for detecting the rotating speed of the left motor. The driving force control device for the electric vehicle further includes motor torque difference estimation means for estimating a torque difference between the left and right motors based on the steering angle of the electric vehicle and the rotational speed of the left and right motors, and left and right based on the state of the vehicle. The motor torque command value calculation means for calculating the torque command value of the motor and the torque command value of the left and right motors are input and at least one of them is corrected, and if corrected, the corrected torque command value is used as the final torque command value. And a motor torque command value correcting means for outputting the input torque command value as a final torque command value when it is not corrected. The driving force control device for the electric vehicle further has a target value for the difference in torque between the left and right motors based on the final torque command value for the right motor and the final torque command value for the left motor output from the motor torque command value correction means. Target motor torque difference calculating means for calculating a target motor torque difference; torque correction value calculating means for calculating torque correction values for the left and right motors based on the estimated torque difference between the left and right motors and the target motor torque difference; Is provided. The motor torque command value correcting means corrects at least one of the torque command values of the left and right motors based on the torque correction value calculated by the torque correction value calculating means.

  According to the present invention, since the estimated value of the left and right motor torque difference is obtained based on the steering angle of the electric vehicle and the rotation speeds of the left and right motors, a minute left and right motor torque difference is detected without using a yaw rate sensor. The motor torque command value can be corrected.

FIG. 1 is a block diagram illustrating a main configuration of an electric vehicle including a control device for an electric vehicle according to an embodiment. FIG. 2 is a flowchart showing a flow of processing of motor current control performed by the electric motor controller. FIG. 3 is a diagram illustrating an example of an accelerator opening-torque table. FIG. 4 shows the corrected final right motor torque command value after correcting the right motor torque command value Tm _r1 ^* and the left motor torque command value Tm _L1 ^* calculated based on the first torque command value Tm _L1 ^*. Tm _r2 ^*, is a diagram showing a control block for calculating a final left motor torque command value Tm _L2 ^*. FIG. 5 is a diagram modeling the lateral movement of the vehicle. FIG. 6 is a diagram modeling the longitudinal motion of the vehicle. FIG. 7 is a diagram modeling the rotational motion of the electric motor. FIG. 8 is a block diagram illustrating a detailed configuration of the left and right motor torque difference correction value calculation unit. FIG. 9 is a block diagram showing a detailed configuration of the left and right torque distribution calculation unit. FIG. 10 is a flowchart illustrating a procedure of calculation processing performed by the left and right torque correction value calculation unit. FIG. 11 is a diagram illustrating an example of a motor rotation speed-upper limit torque table. FIG. 12 is a flowchart illustrating a procedure of processing performed by the slip determination processing unit. FIG. 13 is a flowchart illustrating a procedure of processing performed by the left and right different diameter tire determination processing unit.

  FIG. 1 is a block diagram illustrating a main configuration of an electric vehicle including a driving force control device for an electric vehicle according to an embodiment. The electric vehicle includes an electric motor as a part or all of the drive source of the vehicle, and is a vehicle that can travel by the driving force of the electric motor, for example, an electric vehicle, but is not limited to an electric vehicle, It may be a hybrid vehicle or a fuel cell vehicle. This electric vehicle includes two electric motors 4R and 4L corresponding to the left and right drive wheels in order to drive the left and right drive wheels independently.

The electric motor controller 2 includes vehicle speed V, accelerator opening θ, rotor phase α of electric motors (three-phase AC motors) 4R, 4L, steering angle δ _f , currents iu, iv, iw of electric motors 4R, 4L, etc. A signal indicating the vehicle state is input as a digital signal, and a PWM signal for controlling the electric motors 4R and 4L is generated based on the input signal. Further, a drive signal for the inverter 3 is generated according to the generated PWM signal.

  The inverter 3 includes, for example, two pairs of switching elements (for example, power semiconductor elements such as IGBTs and MOS-FETs) for each phase. The supplied direct current is converted into alternating current, and a desired current is supplied to the electric motor 4R.

  The electric motor 4 </ b> R is an in-wheel motor disposed in the wheel of the right drive wheel 9 </ b> R, and generates a driving force by an alternating current supplied from the inverter 3. The generated driving force is transmitted to the right driving wheel 9R via the reduction gear 8R. The electric motor 4R also collects the kinetic energy of the vehicle as electric energy by generating a regenerative driving force when the vehicle is driven and rotated by the drive wheels 9R during traveling of the vehicle. In this case, the inverter 3 converts an alternating current generated during the regenerative operation of the electric motor 4 </ b> R into a direct current and supplies the direct current to the battery 1. In the following description, “right motor” refers to the electric motor 4R.

  The current sensor 7R detects three-phase alternating currents iu, iv, iw flowing through the electric motor 4R. However, since the sum of the three-phase alternating currents iu, iv, and iw is 0, any two-phase current may be detected, and the remaining one-phase current may be obtained by calculation.

  The steering angle sensor 5 detects the steering angle. The rotation sensor 6R is, for example, a resolver or an encoder, and detects the rotor phase α of the electric motor 4R.

  The inverter 3 also turns on / off the switching element in accordance with the drive signal, thereby converting the direct current supplied from the battery 1 into alternating current and causing a desired current to flow through the electric motor 4L.

  The electric motor 4L is an in-wheel motor arranged in the wheel of the left driving wheel 9L, and generates a driving force by an alternating current supplied from the inverter 3. The generated driving force is transmitted to the left driving wheel 9L via the reduction gear 8L. The electric motor 4L also collects the kinetic energy of the vehicle as electric energy by generating a regenerative driving force when the vehicle is driven and rotated by the drive wheels 9L during traveling of the vehicle. In this case, the inverter 3 converts the alternating current generated during the regenerative operation of the electric motor 4L into a direct current and supplies the direct current to the battery 1. In the following description, “left motor” refers to the electric motor 4L.

  The current sensor 7L detects three-phase alternating currents iu, iv, iw flowing through the electric motor 4L. However, since the sum of the three-phase alternating currents iu, iv, and iw is 0, any two-phase current may be detected, and the remaining one-phase current may be obtained by calculation.

  The rotation sensor 6L is, for example, a resolver or an encoder, and detects the rotor phase α of the electric motor 4L.

  FIG. 2 is a flowchart showing a flow of processing of motor current control performed by the electric motor controller 2. In the following description, the electric motor 4R will be described. However, the same processing is performed for the electric motor 4L. However, since the process of step S202 is the same process common to both the electric motors 4R and 4L, when the process is performed on one motor, a calculated value is used for the other motor. You may do it.

In step S201, a signal indicating the vehicle state is input. Here, the vehicle speed V (km / h), the accelerator opening θ (%), the rotor phase α (rad) of the electric motor 4R, the rotational speed Nm (rpm) of the electric motor 4R, and the three-phase AC flowing through the electric motor 4R The currents iu, iv, iw, the DC voltage value Vdc (V) between the battery 1 and the inverter 3 and the steering angle δ _f are input.

  The vehicle speed V (km / h) is acquired by communication from a vehicle speed sensor (not shown) or another controller such as a brake controller (not shown). Alternatively, the vehicle speed v (m / s) is obtained by multiplying the average value of the left and right motor rotation speeds by the tire dynamic radius R and dividing by the gear ratio of the final gear, and unit conversion is performed by multiplying by 3600/1000. Thus, the vehicle speed V (km / h) is obtained.

  The accelerator opening θ (%) is acquired from an accelerator opening sensor (not shown), or is acquired by communication from another controller such as a vehicle controller (not shown).

  The rotor phase α (rad) of the electric motor 4R is acquired from the rotation sensor 6R. The rotational speed Nm (rpm) of the electric motor 4R is obtained by dividing the angular speed ω (electrical angle) of the rotor by the number of pole pairs of the electric motor 4R to obtain a motor rotational speed ωm (rad / s) is obtained by multiplying the obtained motor rotational speed ωm by 60 / (2π). The angular velocity ω of the rotor is obtained by differentiating the rotor phase α.

  Currents iu, iv, iw (A) flowing through the electric motor 4R are acquired from the current sensor 7R.

  The DC voltage value Vdc (V) is obtained from a power supply voltage value transmitted from a voltage sensor (not shown) provided on a DC power supply line between the battery 1 and the inverter 3 or a battery controller (not shown).

The steering angle δ _f is acquired from the steering angle sensor 5.

In step S202, a torque command value Tm _r1 ^* for the electric motor 4R and a torque command value Tm _L1 ^* for the electric motor 4L are obtained. Specifically, first, the first torque command value Tm ₁ ^* is obtained by referring to the accelerator opening-torque table shown in FIG. 3 based on the accelerator opening θ and the vehicle speed V input in step S201. Set. Next, the torque command value Tm _R1 ^* for the electric motor 4R and the torque command value Tm _L1 ^* for the electric motor 4L are obtained by the following equations (1) and (2). Hereinafter, the torque command value Tm _R1 ^* for the electric motor 4R is called a right motor torque command value Tm _r1 ^* , and the torque command value Tm _L1 ^* for the electric motor 4L is called a left motor torque command value Tm _L1 ^* .

  However, in the formulas (1) and (2), α is an arbitrary value that satisfies 0 ≦ α ≦ 1, and is set to α = ½ during straight traveling.

In step S203, the torque command value Tm _R1 ^* for the electric motor 4R calculated in step S202 is corrected to calculate a final torque command value Tm _R2 ^* . Details of the correction processing will be described later.

In step S204, the d-axis current target value id ^* and the q-axis current target value iq ^* are calculated based on the final torque command value Tm _R2 ^* , the motor rotation speed ωm, and the DC voltage value Vdc of the electric motor 4R calculated in step S203. Ask. For example, by preparing in advance a table that defines the relationship between the torque command value, the motor rotation speed, the DC voltage value, the d-axis current target value, and the q-axis current target value, and referring to this table, The d-axis current target value id ^* and the q-axis current target value iq ^* are obtained.

In step S205, current control is performed 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. For this reason, first, the d-axis current id and the q-axis current iq are obtained based on the three-phase AC current values iu, iv, iw input in step S201 and the rotor phase α of the electric motor 4R. Subsequently, d-axis and q-axis voltage command values vd and vq are respectively calculated from 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. In addition, you may make it add the non-interference voltage required in order to cancel the interference voltage between dq orthogonal coordinate axes with respect to the calculated d-axis and q-axis voltage command values vd and vq.

  Next, three-phase AC voltage command values vu, vv, vw are obtained from the d-axis and q-axis voltage command values vd, vq and the rotor phase α of the electric motor 4R. Then, PWM signals tu (%), tv (%), and tw (%) are obtained from the obtained three-phase AC voltage command values vu, vv, and vw and the DC voltage value Vdc. The electric motor 4R can be driven with a desired torque indicated by the torque command value by opening and closing the switching element of the inverter 3 by the PWM signals tu, tv, and tw obtained in this way.

FIG. 4 shows the corrected right motor torque command value Tm _R1 ^* and left motor torque command value Tm _L1 ^* calculated based on the first torque command value Tm _L1 ^* , and the corrected final right motor torque command value. Tm _R2 ^*, is a diagram showing a control block for calculating a final left motor torque command value Tm _L2 ^*. Hereinafter, processing performed by the left and right motor torque difference correction value calculation unit 401 and the left and right torque distribution calculation unit 402 will be described. Note that the current command value calculation processing units 41R and 41L in FIG. 4 perform the process of step S204 in FIG. 2, and the current control calculation units 42R and 42L perform the process of step S205 in FIG.

Left and right motor torque difference correction value calculation unit 401, rotational speed .omega.m _L rotational speed .omega.m _R, the electric motor 4L of the electric motor 4R, final right motor torque command value Tm _r2 ^*, final left motor torque command value Tm _L2 ^*, the steering The angle δ _f and the vehicle speed V are input, and the left and right motor torque difference correction amount ΔTd is calculated. A detailed calculation method of the left and right motor torque difference correction amount ΔTd will be described later.

Right and left torque distribution calculation unit 402, the left and right motor torque difference correction amount .DELTA.Td, rotational speed .omega.m _R of the electric motor 4R, speed .omega.m _L of the electric motor 4L, the right motor torque command value Tm _R1 ^*, left motor torque command value Tm _L1 ^* , steering angle δ _f , and vehicle speed V are input to calculate the final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* . A detailed calculation method of the final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* will be described later.

The adder 403 calculates the final right motor torque command value Tm _R2 ^* by adding the final right motor torque correction value ΔTm _R3 ^* to the right motor torque command value Tm _R1 ^* .

The adder 404 by adding the final left motor torque correction value? Tm _L3 ^* left motor torque command value Tm _L1 ^*, and calculates the final left motor torque command value Tm _L2 ^*.

  A detailed method by which the left and right motor torque difference correction value calculation unit 401 calculates the left and right motor torque difference correction amount ΔTd will be described below.

  FIG. 5 is a diagram modeling the lateral movement of the vehicle, and shows four wheels 51 to 54. The equations of motion in the lateral direction and rotational direction of the vehicle are expressed by the following equations (3) and (4).

Here, each parameter in the equations (3) and (4) is as shown below.
m: vehicle mass V: vehicle speed beta: slip angle of the tire gamma: yaw rate K _f: front wheel of the generated cornering force K _r: cornering force l _f occurrence of rear wheels to a distance from the front wheel axis to the center of gravity l _r: After Distance from wheel axis to center of gravity δ _f : Steering angle of front wheel I _z : Moment of inertia in the yaw direction F _R : Driving force of right wheel F _L : Driving force of left wheel l _w : Distance of 1/2 of rear wheel tread width FIG. 6 is a diagram modeling the longitudinal motion of the vehicle. The driving forces F _R and F _{L for the} left and right wheels are expressed by the following equations (5) and (6), respectively.

Here, each parameter in the equations (5) and (6) is as shown below.
K _t : Coefficient related to friction between tire and road surface R: Tire load radius N: Overall gear ratio ωm _R : Right wheel motor rotational speed ωm _L : Left wheel motor rotational speed FIG. 7 shows the rotational motion of the electric motor (4R, 4L). It is the modeled figure. Equations of motion in the rotation direction of the electric motors 4R and 4L are expressed by the following equations (7) and (8), respectively.

Here, each parameter in the formulas (7) and (8) is as shown below.
J _m : Motor inertia J _w : Drive shaft inertia Tm _R : Torque Tm _L of the electric motor 4R: Torque of the electric motor 4L Rotational speed difference Δωm between the electric motor 4R and the electric motor 4L (hereinafter referred to as left and right motor rotational speed difference Δωm) ) Is defined as Δωm = ωm _R −ωm _L , and the torque difference ΔTm between the electric motor 4R and the electric motor 4L (hereinafter referred to as the left and right motor torque difference ΔTm) is defined as ΔTm = Tm _R −Tm _L. When the transfer characteristic from the steering angle δ _f to the left-right motor rotational speed difference Δωm is obtained, the following equation (9) is obtained. However, Gp (s) and Gd (s) in the formula (9) are represented by the following formulas (10) and (11), respectively. Gp (s) represented by Expression (10) represents a transfer characteristic from the left / right motor torque difference ΔTm to the left / right motor rotation speed difference Δωm.

  The constants of the terms in the expressions (10) and (11) are constants obtained from the vehicle specifications described above.

  From equation (9), an estimated value ΔTm ^ of the left and right motor torque difference is calculated by the following equation (12).

However, G _H (s) in the equation (12) is a primary low-pass filter, and is represented by the following equation (13). In Expression (13), ω _H is a cutoff frequency of the low-pass filter.

Further, a target left / right motor torque difference ΔTm ^* , which is a target value of the left / right motor torque difference, is calculated from the following equation (14).

Then, as shown in the following equation (15), the left / right motor torque difference correction amount ΔTd is calculated by obtaining the difference between the target left / right motor torque difference ΔTm ^* and the estimated value ΔTm ^ of the left / right motor torque difference.

FIG. 8 is a block diagram illustrating a detailed configuration of the left and right motor torque difference correction value calculation unit 401. From the equations (12), (14), and (15), the left and right motor torque difference correction value calculation unit 401 that calculates the left and right motor torque difference correction amount ΔTd is rotated from the steering angle δ _f to the left and right motor rotations as shown in FIG. A control block 801 representing the transfer characteristics G _H (s) · Gd (s) up to the speed difference Δωm and a control including an inverse model of the transfer characteristics Gp (s) from the left-right motor torque difference ΔTm to the left-right motor rotation speed difference Δωm. A block 802 and a low-pass filter 803 are used.

  Next, the left and right torque distribution calculation unit 402 in FIG. 4 will be described. FIG. 9 is a block diagram illustrating a detailed configuration of the left / right torque distribution calculation unit 402.

Left and right torque correction value calculating section 901, the rotational speed .omega.m _L rotational speed .omega.m _R, the electric motor 4L of the electric motor 4R, the right motor torque command value Tm _R1 ^*, left motor torque command value Tm _L1 ^*, left and right motor torque difference correction The amount ΔTd is input to calculate the right motor torque correction value ΔTm _R1 ^* and the left motor torque correction value ΔTm _L1 ^* . Details of the calculation processing performed by the left and right torque correction value calculation unit 901 will be described later.

The slip determination processing unit 902 inputs the vehicle speed V, the right motor torque correction value ΔTm _R1 ^* , the left motor torque correction value ΔTm _L1 ^*, and outputs the right motor torque correction value ΔTm _R2 ^* and the left motor torque correction value ΔTm _L2 ^* . If it is calculated and it is determined that at least one of the left and right drive wheels 9R, 9L is slipping, a process of interrupting correction of the motor torque command values Tm _R1 ^* and Tm _L1 ^* is performed. Details of the processing performed by the slip determination processing unit 902 will be described later.

Right and left different-diameter tire determination processing unit 903, the steering angle [delta] _f, the rotational speed .omega.m _L rotational speed .omega.m _R, the electric motor 4L of the electric motor 4R, the right motor torque correction value? Tm _R2 ^*, left motor torque correction value? Tm _L2 ^* When the final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* are calculated and it is determined that the tire diameters of the left and right drive wheels 9R, 9L are different, the motor torque command value Processing for interrupting correction of Tm _R1 ^* and Tm _L1 ^* is performed. Details of processing performed by the left and right different diameter tire determination processing unit 903 will be described later.

  Details of the calculation process performed by the left-right torque correction value calculation unit 901 will be described. FIG. 10 is a flowchart showing a procedure of calculation processing performed by the left and right torque correction value calculation unit 901.

In step S1001, the right motor torque correction value ΔTm _R1 ^* and the left motor torque correction value ΔTm _L1 ^* are calculated by the following equations (16) and (17).

In step S1002, the final right motor torque command value Tm _R2 ^* and the final left motor torque command value Tm _L2 ^* are calculated from the following equations (18) and (19).

In step S1003, based on the motor rotational speed ωm _R of the electric motor 4R, referring to the motor rotational speed-upper limit torque table shown in FIG. 11, the upper limit torque of the electric motor 4R (hereinafter referred to as the right motor torque upper limit value). Is calculated. Further, based on the motor rotation speed ωm _L of the electric motor 4L, the upper limit torque of the electric motor 4L (hereinafter referred to as the left motor torque upper limit value) is calculated with reference to the motor rotation speed-upper limit torque table shown in FIG. To do.

In step S1004, it is determined whether or not the final right motor torque command value Tm _R2 ^* calculated in step S1002 is equal to or less than the right motor torque upper limit value calculated in step S1003, and the final left motor torque command calculated in step S1002 is determined. It is determined whether or not the value Tm _L2 ^* is less than or equal to the upper limit value of the left motor torque calculated in step S1003. If the determination is affirmative, the right motor torque correction value ΔTm _R1 ^* and the left motor torque correction value ΔTm _L1 ^* calculated in step S1001 are output, and the process of the flowchart ends. On the other hand, if the determination is negative, the process proceeds to step S1005.

  In step S1005, it is determined whether the sign of the left and right motor torque difference correction amount ΔTd is positive. If it is determined that the sign of the left and right motor torque difference correction amount ΔTd is positive (ΔTd> 0), the process proceeds to step S1006, and if it is determined negative (ΔTd <0), the process proceeds to step S1007.

In step S1006, the right motor torque correction value ΔTm _R1 ^* and the left motor torque correction value ΔTm _L1 ^* are calculated from the following equations (20) and (21).

In step S1007, the right motor torque correction value ΔTm _R1 ^* and the left motor torque correction value ΔTm _L1 ^* are calculated from the following equations (22) and (23).

  Next, details of processing performed by the slip determination processing unit 902 in FIG. 9 will be described. FIG. 12 is a flowchart illustrating a procedure of processing performed by the slip determination processing unit 902.

In step S1201, the following equation (24), (25) than to calculate a slip ratio lambda _L of the slip ratio lambda _R and left drive wheels 9L of the right driving wheel 9R.

In step S1202, the determining whether the slip ratio lambda _R and left slip ratio lambda _L of the drive wheels 9L of the right driving wheel 9R computed is both less than the predetermined value in step S1201. If it is determined that the slip ratio λ _{R for the} right wheel and the slip ratio λ _L for the left wheel are both less than the predetermined value, it is determined that the left and right drive wheels 9R, 9L are not slipping, and the process proceeds to step S1203. If it is determined that the slip ratio is equal to or greater than the predetermined value, it is determined that at least one of the left and right drive wheels 9R, 9L is slipping, and the process proceeds to step S1204.

In step S1203, the right motor torque correction value ΔTm _R2 ^* and the left motor torque correction value ΔTm _L2 ^* are calculated from the following equations (26) and (27). That is, if it is determined that the left and right drive wheels 9R and 9L are not slipping, the right motor torque correction value ΔTm _R1 ^* and the left motor torque correction value ΔTm _L1 ^* calculated by the left and right torque correction value calculation unit 901 are directly used as the right motor. The torque correction value ΔTm _R2 ^* and the left motor torque correction value ΔTm _L2 ^* are output.

On the other hand, in step S1204, as shown in the following expressions (28) and (29), the right motor torque correction value ΔTm _R2 ^* and the left motor torque correction value ΔTm _L2 ^* are set to 0, respectively. That is, when it is determined that at least one of the left and right drive wheels 9R and 9L is slipping, the correction of the motor torque command values Tm _R1 ^* and Tm _L1 ^* is interrupted by setting the correction amount to zero. The final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* for correcting the motor torque command values Tm _R1 ^* and Tm _L1 ^* are determined by the left and right different diameter tire determination processing unit 903. When the right motor torque correction value ΔTm _R2 ^* and the left motor torque correction value ΔTm _L2 ^* are 0, the final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* are also 0. It becomes.

  Next, details of processing performed in the left and right different diameter tire determination processing unit 903 in FIG. 9 will be described. FIG. 13 is a flowchart illustrating a procedure of processing performed by the left and right different diameter tire determination processing unit 903.

  In step S1301, it is determined whether the left-right motor rotational speed difference Δωm is equal to or greater than a predetermined speed. If it is determined that the left-right motor rotational speed difference Δωm is equal to or greater than the predetermined speed, the process proceeds to step S1302, and if it is determined that the difference is less than the predetermined speed, the process proceeds to step S1303.

In step S1302, the final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* are calculated from the following equations (30) and (31).

In step S1303, it is determined whether the steering angle δ _f is less than a predetermined angle. _{If it} is determined that the steering angle δ _f is less than the predetermined angle, the process proceeds to step S1302.

In step S1304, the steering angle [delta] _f starts timer counting up for measuring at a time more than a predetermined angle.

In step S1305, it is determined whether or not the duration for which the steering angle δ _f is equal to or greater than a predetermined angle is less than the predetermined time. _{If it} is determined that the duration for which the steering angle δ _f is equal to or greater than the predetermined angle is less than the predetermined time, the process proceeds to step S1302, and if it is determined that the duration is equal to or greater than the predetermined time, the process proceeds to step S1306.

In step S1306, as shown in the following equations (32) and (33), the final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* are set to 0, respectively. That is, when the difference between the left and right motor rotational speeds Δωm is less than the predetermined speed, the tire diameters of the left and right drive wheels 9R and 9L are different if the steering angle δ _f is longer than the predetermined angle and the duration is longer than the predetermined time. If the correction amount is set to 0, the correction of the motor torque command values Tm _R1 ^* and Tm _L1 ^* is interrupted.

As described above, the driving force control apparatus for an electric vehicle according to an embodiment calculates the right motor torque command value Tm _R1 ^* and the left motor torque command value Tm _L1 ^* based on the state of the vehicle, and the steering angle δ of the electric vehicle. _{Based on f} , the rotational speed ωm _R of the right motor 4R, and the rotational speed ωm _L of the left motor 4L, an estimated value ΔTm ^ of the left and right motor torque is obtained. Further, a target left / right motor torque difference ΔTm ^* is calculated based on the final right motor torque command value Tm _R2 ^* and the final left motor torque command value Tm _L2 ^*, and the estimated value ΔTm ^ of the left / right motor torque difference and the target left / right motor torque are calculated. A left / right motor torque difference correction amount ΔTd is calculated based on the difference ΔTm ^* . Then, based on the calculated left and right motor torque difference correction amount ΔTd, at least one of the right motor torque command value Tm _R1 ^* and the left motor torque command value Tm _L1 ^* is corrected, and the final right motor torque command value Tm _R2 ^* and The final left motor torque command value Tm _L2 ^* is calculated. Steering angle [delta] _f and the left and right motor 4R electric vehicle, 4L rotational speed .omega.m _R of, based on .omega.m _L, so obtaining an estimate of the left and right motor torque difference? Tm ^, without using a yaw rate sensor, minute lateral motor The motor torque command value can be corrected by detecting the torque difference. Further, the steering angle [delta] _f and the left and right motor 4R, the rotational speed .omega.m _R of 4L, and the estimated value of the left and right motor torque difference obtained based on .omega.m _L? Tm ^, the left and right motor 4R, final against 4L motor torque command value Tm _A left / right motor torque difference correction amount ΔTd is calculated based on the target left / right motor torque difference ΔTm ^* obtained based on _R2 ^* and Tm _L2 ^* , and the right motor torque is calculated based on the calculated left / right motor torque difference correction amount ΔTd. Since at least one of the command value Tm _R1 ^* and the left motor torque command value Tm _L1 ^* is corrected, even if different command values are intentionally given to the left and right motor torque command values during turning, the generated torque error Only can be corrected.

Further, the inverse model of the transfer characteristics Gp from the left and right motor torque difference ΔTm to the left and right motor speed difference Δωm (s), transfer characteristic Gp (s) · Gd (s from the steering angle [delta] _f to the left and right motor speed difference Derutaomegaemu ) Is used to obtain the estimated value ΔTm ^ of the left and right motor torque difference, so that the estimated value ΔTm ^ of the left and right motor torque difference can be obtained with high accuracy.

Further, based on the final right motor torque command value Tm _R2 ^* , the final left motor torque command value Tm _L2 ^*, and the rotational speeds ωm _R and ωm _{L of} the left and right motors 4R and 4L, the left and right motor torque difference correction amount ΔTd is calculated. The correction ratio to be distributed to the correction values of the torque command values of the left and right motors 4R, 4L is determined. Specifically, the right motor torque upper limit value and the left motor torque upper limit value are set based on the rotational speeds ωm _R and ωm _L of the left and right motors 4R and 4L, the final right motor torque command value Tm _R2 ^* , the final left Compare the motor torque command value Tm _L2 ^* with the right motor torque upper limit value and the left motor torque upper limit value so that the final right motor torque command value Tm _R2 ^* does not exceed the right motor torque upper limit value. At least one of the right motor torque command value Tm _R1 ^* and the left motor torque command value Tm _L1 ^* is corrected so that the final left motor torque command value Tm _L2 ^* does not exceed the upper limit value of the left motor torque. Thereby, the motor torque command value can be corrected within the power performance range of the vehicle.

Furthermore, each of the slip ratio left and right driving wheels lambda _R, calculates the lambda _L, the slip ratio lambda _R of the calculated left and right drive wheels, when at least one of the slip rate of the lambda _L is determined to be equal to or greater than the predetermined value, The right motor torque command value Tm _R1 ^* and the left motor torque command value Tm _L1 ^* are not corrected (by setting the right motor torque correction value ΔTm _R2 ^* and the left motor torque correction value ΔTm _L2 ^* to 0, the final right motor Torque correction value ΔTm _R3 ^* and final left motor torque correction value ΔTm _L3 ^* are set to 0). Thus, when slip occurs in the left and right drive wheels, it is possible to prevent the vehicle from becoming unstable by correcting the torque command values for the left and right motors 4R and 4L.

Further, when the left-right motor rotational speed difference Δωm is less than the predetermined speed and the state where the steering angle δ _f is equal to or greater than the predetermined angle continues for a predetermined time, the right motor torque command value Tm _R1 ^* and the left motor torque command value Tm _L1 ^* (The final right motor torque correction value ΔTm _R3 ^* and the final left motor torque correction value ΔTm _L3 ^* are set to 0). Accordingly, when it is detected that the left and right drive wheels 9R and 9L are traveling with different tire diameters, the correction of the torque command values for the left and right motors 4R and 4L can be stopped.

  The present invention is not limited to the embodiment described above. For example, in the above description, the rotation speeds of the left and right wheels may be substituted when performing calculations using the rotation speeds of the electric motors 4R and 4L.

2. Electric motor controller (motor torque difference estimating means, motor torque command value calculating means, motor torque command value correcting means, target motor torque difference calculating means, torque correction value calculating means)
3 ... Inverter 4R, 4L ... Electric motor 5 ... Steering angle sensor 6R ... Rotation sensor (right motor rotation speed detection means)
6L ... rotation sensor (left motor rotation speed detection means)
9R, 9L ... Drive wheels

Claims (5)

In a driving force control device for an electric vehicle having a right motor that transmits driving force to the right driving wheel and a left motor that transmits driving force to the left driving wheel,
Steering angle detecting means for detecting a steering angle of the electric vehicle;
Right motor rotation speed detection means for detecting the rotation speed of the right motor;
Left motor rotation speed detecting means for detecting the rotation speed of the left motor;
Motor torque difference estimating means for estimating a torque difference between the right motor and the left motor based on a steering angle of the electric vehicle, a rotation speed of the right motor, and a rotation speed of the left motor;
Motor torque command value calculating means for calculating the torque command value of the right motor and the torque command value of the left motor based on the state of the vehicle;
Input the torque command value of the right motor and the torque command value of the left motor calculated by the motor torque command value calculation means to correct at least one of them, and if corrected, use the corrected torque command value as the final torque. A motor torque command value correcting means for outputting the command value as a final torque command value when the command value is not corrected and
Based on the final torque command value of the right motor and the final torque command value of the left motor output from the motor torque command value correcting means, a target motor torque that is a target value of a torque difference between the right motor and the left motor Target motor torque difference calculating means for calculating the difference;
The right motor and the left motor based on the torque difference between the right motor and the left motor estimated by the motor torque difference estimating means and the target motor torque difference calculated by the target motor torque difference calculating means. Torque correction value calculating means for calculating the torque correction value of
With
The motor torque command value correcting means corrects at least one of the torque command value of the right motor and the torque command value of the left motor based on the torque correction value calculated by the torque correction value calculating means;
A driving force control apparatus for an electric vehicle characterized by the above. The driving force control apparatus for an electric vehicle according to claim 1,
The motor torque difference estimating means includes an inverse model of transfer characteristics from a torque difference between the right motor and the left motor to a rotation speed difference between the right motor and the left motor, and the right motor and the left motor from the steering angle. The torque difference between the right motor and the left motor is estimated using the transfer characteristic up to the rotational speed difference of
A driving force control apparatus for an electric vehicle characterized by the above. In the driving force control device for an electric vehicle according to claim 1 or 2,
The motor torque command value correction means is configured to determine the torque correction value based on a final torque command value of the right motor and a final torque command value of the left motor, and a rotation speed of the right motor and a rotation speed of the left motor. Determining a correction ratio to distribute the torque correction value calculated by the calculation means to the correction value of the torque command value of the right motor and the correction value of the torque command value of the left motor;
A driving force control apparatus for an electric vehicle characterized by the above. In the driving force control device for an electric vehicle according to any one of claims 1 to 3,
A slip ratio calculating means for calculating the slip ratio of each of the left and right drive wheels;
When the motor torque command value correction means determines that at least one of the slip ratios of the left and right drive wheels calculated by the slip ratio calculation means is greater than or equal to a predetermined value, the torque command value of the right motor and Do not correct the torque command value of the left motor,
A driving force control apparatus for an electric vehicle characterized by the above. In the driving force control device for an electric vehicle according to any one of claims 1 to 4,
The motor torque command value correcting means is configured such that when the difference in rotational speed between the right motor and the left motor is less than a predetermined speed, the state where the steering angle is equal to or greater than a predetermined angle continues for a predetermined time, the torque command for the right motor The value and the torque command value of the left motor are not corrected,
A driving force control apparatus for an electric vehicle characterized by the above.

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