Control method for electric vehicle, control device for electric vehicle

Abstract

To provide an electric vehicle control method and an electric vehicle control device which enable an electric vehicle to stop at a target stop position, set by a driver, in front of an obstacle such as a preceding vehicle, with high accuracy, when stopping the electric vehicle at regenerative torque.SOLUTION: In an electric vehicle control method, which when a predetermined condition for determining that the vehicle stops soon is satisfied, the electric vehicle is stopped by generating regenerative torque on the basis of a second torque target value that is converged into disturbance torque, a third torque target value, set in accordance with a target stop position and a vehicle speed, at which the electric vehicle can be stopped at the target stop position, is set, the regenerative torque is generated on the basis of a first torque target value and a third torque target value which are set based on an accelerator operation amount, whichever is low, until the predetermined condition for determining that the vehicle stops soon is satisfied, and the third torque target value is calculated based on regenerative torque at which deceleration becomes nearly constant until the predetermined condition for determining that the vehicle stops soon is satisfied.SELECTED DRAWING: Figure 11

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for controlling regenerative torque by switching between a first torque target value calculated based on vehicle information and a second torque target value that converges to the disturbance torque, thereby stopping an electric vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-133799 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not take into consideration the case where an obstacle such as a preceding vehicle is present, and it is difficult to perform control that can avoid approaching the preceding vehicle.

[0005] An object of the present invention is to provide a control method for an electric vehicle that can stop the electric vehicle with high accuracy at a target stopping position set by the driver in front of an obstacle such as a preceding vehicle when stopping the electric vehicle using regenerative torque, and a control device for the electric vehicle. [Means for solving the problem]

[0006] A control method for an electric vehicle according to the present invention detects the rotational speed of a motor that drives the electric vehicle, estimates disturbance torque acting on the electric vehicle, calculates a first torque target value based on an accelerator operation amount, calculates a second torque target value that converges to the disturbance torque as the motor rotational speed decreases, and generates regenerative torque based on the second torque target value to stop the electric vehicle when a predetermined condition for determining that the vehicle is about to stop is met. In this control method, a position at a predetermined relative distance set by an occupant from a target ahead in the direction of travel of the electric vehicle is set as a target stop position, a third torque target value that is set according to the target stop position and vehicle speed and enables the electric vehicle to stop at the target stop position, and generates regenerative torque based on the lower of the first torque target value and the third torque target value until the predetermined condition for determining that the vehicle is about to stop is met. The third torque target value is then calculated based on the regenerative torque that results in a substantially constant deceleration until the predetermined condition for determining that the vehicle is about to stop is met. [Effects of the Invention]

[0007] According to the present invention, the target angular velocity is calculated in accordance with the distance to the target stopping position when the motor torque is switched to that derived from the second torque target value, and the motor torque is controlled, thereby making it possible to stop the vehicle at a targeted position. Furthermore, since the regenerative torque is calculated so that the deceleration is approximately constant until a predetermined condition is met that determines that the vehicle is about to stop, the distance to the target stopping position and the vehicle speed when the motor torque is switched to that derived from the second torque target value can be uniquely determined, thereby suppressing fluctuations in acceleration when the vehicle is about to stop and achieving a smooth stop. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the basic configuration of an electric vehicle equipped with a control device for an electric vehicle according to this embodiment. [Figure 2] FIG. 2 is a flowchart of the motor current control executed by the motor controller. [Figure 3]FIG. 3 is a diagram showing an example of an accelerator opening-torque table. [Figure 4] FIG. 4 is a diagram modeling the drive force transmission system of an electric vehicle. [Figure 5] FIG. 5 is a block diagram showing an example of a functional configuration for realizing stop control processing. [Figure 6] FIG. 6 is a block diagram of a motor angular velocity FB torque setter. [Figure 7] FIG. 7 is a block diagram of a disturbance torque estimator. [Figure 8] FIG. 8 is a block diagram showing an example of a functional configuration for realizing vibration suppression control processing for suppressing vibration of the drive force transmission system of an electric vehicle. [Figure 9] FIG. 9 is a diagram showing an example of a band-pass filter for realizing transfer characteristic H2(s). [Figure 10] FIG. 10 is a block diagram showing an example of a functional configuration for realizing target stop position calculation processing. [Figure 11] FIG. 11 is a block diagram showing an example of a functional configuration for realizing constant regeneration torque calculation processing. [Figure 12] FIG. 12 is a time chart until the electric vehicle stops at the target stop position. FIG. 12(a) shows the case where the electric vehicle is stopped at the target stop position according to the prior art with initial speeds of V0, V1, V2 (V0 < V1 < V2), and FIG. 12(b) shows the case where the electric vehicle is stopped at the target stop position by the control of the control device of the electric vehicle of the present embodiment with initial speeds of V0, V1, V2 (V0 < V1 < V2). [Embodiments for Carrying Out the Invention]

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

[0010] [Basic Configuration of Control Device] FIG. 1 is a diagram showing an example of the basic configuration of an electric vehicle 1 equipped with a control device for the electric vehicle 1 of the present embodiment.

[0011] The control device for an electric vehicle 1 in this embodiment is applicable to an electric vehicle 1 that has a motor 6 (drive motor) as part or all of the vehicle's drive source and can run using the driving force of the motor 6. The electric vehicle 1 includes not only electric vehicles, but also hybrid vehicles and fuel cell vehicles.

[0012] The control device of the electric vehicle 1 illustrated in Fig. 1 controls the acceleration, deceleration, and stopping of the vehicle solely through the operation of the accelerator pedal. The driver of this electric vehicle 1 depresses the accelerator pedal when accelerating, and reduces the amount of depression of the accelerator pedal or sets the accelerator pedal to zero when decelerating or stopping. On an uphill road, the driver may approach a stop while depressing the accelerator pedal to prevent the vehicle from rolling back.

[0013] The motor controller 2 receives digital signals indicating vehicle conditions such as the vehicle speed V, accelerator opening θ, rotor phase α of the motor 6, and three-phase AC currents iu, iv, and iw of the motor 6, as well as relative distance and steering paddle operation signals, which will be described later. Based on the received signals, the motor controller 2 generates a PWM signal for controlling the power supplied to the motor 6, and supplies the generated PWM signal to the inverter 3 to control the opening and closing of the switching elements of the inverter 3.

[0014] The inverter 3 converts the direct current supplied from the battery 4 into alternating current by, for example, turning on / off two switching elements (for example, power semiconductor elements such as IGBTs and MOS-FETs) for each phase, and supplies the desired current to the motor 6.

[0015] The motor 6 is realized by, for example, a three-phase AC motor. The motor 6 generates driving force using the AC current output from the inverter 3, and transmits the driving force to left and right driving wheels 81, 82 via a speed reducer 7 and a drive shaft 8. When the motor 6 is rotated by the driving wheels 81, 82 while the electric vehicle 1 is running, the motor 6 generates regenerative driving force to recover the kinetic energy of the electric vehicle 1 as electrical energy. In this case, the inverter 3 converts the AC current generated during regenerative operation of the motor 6 into DC current and supplies it to the battery 4.

[0016] The rotation sensor 9 is realized by, for example, a resolver or an encoder, and detects the rotor phase α of the motor 6.

[0017] The current sensor 5 detects three-phase AC currents iu, iv, and iw supplied to the motor 6. However, since the sum of the three-phase AC currents iu, iv, and iw is 0 (zero), the currents of any two phases may be detected and the current of the remaining phase may be calculated.

[0018] The camera 10 is configured to capture an image in the traveling direction of the vehicle and measures the relative distance between the vehicle and an object, such as another vehicle or an obstacle, that exists in the traveling direction. However, the camera 10 is merely an example and is not limited to this. Instead of the camera 10, a sensor or radar that can measure the relative distance between the vehicle and a vehicle or an obstacle that exists in the traveling direction may be used. The camera 10 may also be a stereo camera. The traveling direction includes not only the front of the vehicle but also the rear when the vehicle is reversing. Therefore, in order to capture an image in the traveling direction when the vehicle is reversing, it is preferable to provide a camera that can capture not only the front of the vehicle but also the rear. In the following, the traveling direction of the vehicle will be referred to as the front for convenience. In addition, a vehicle that exists in the traveling direction of the vehicle will be referred to as the leading vehicle.

[0019] The steering paddle SW11 detects the operation of the steering paddle by the occupant (driver, etc.).

[0020] [Motor current control] FIG. 2 is a flowchart of the motor current control executed by the motor controller 2.

[0021] In step S201, the motor controller 2 inputs signals indicating the operating state of the electric vehicle 1. The operating state here refers to the DC voltage value Vdc (V) between the battery 4 and the inverter 3, the vehicle speed V (km / h) of the electric vehicle 1, the accelerator opening θ (%), the rotor phase α (rad) of the motor 6, the motor rotation speed ωm (rpm), the three-phase AC currents iu, iv, and iw supplied to the motor 6, and the steering paddle operation signal. The motor controller 2 also inputs relative distances required for control calculations related to the target stop position calculation process, which will be described later.

[0022] The vehicle speed V (km / h) is obtained from a vehicle speed sensor (not shown) or from another controller via communication. Alternatively, the motor controller 2 multiplies the rotational speed ωm (rotor mechanical angular velocity) by the tire dynamic radius R, divides the result by the gear ratio of the final gear to obtain the vehicle speed v (m / s), and then multiplies the vehicle speed v (m / s) by 3600 / 1000 to perform unit conversion to obtain the vehicle speed V (km / h).

[0023] The accelerator opening degree θ (%) is acquired from an accelerator opening degree sensor (not shown) or acquired through communication from another controller (not shown) such as a vehicle controller.

[0024] The rotor phase α (rad) of the motor 6 is acquired from the rotation sensor 9. The rotation speed Nm (rpm) of the motor 6 is obtained by multiplying the motor rotation speed ωm (rad / s), which is the mechanical angular speed of the motor 6, by 60 / (2π). The motor rotation speed ωm (rad / s) is obtained by dividing the rotor angular speed ω (electrical angle) by the number of pole pairs p of the motor 6. The rotor angular speed ω is obtained by differentiating the rotor phase α.

[0025] Three-phase AC currents iu, iv, and iw (A) flowing through the motor 6 are acquired from the current sensor 5.

[0026] The DC voltage value Vdc (V) is obtained from a voltage sensor (not shown) provided on the DC power supply line between the battery 4 and the inverter 3, or is calculated from the power supply voltage value transmitted by a battery controller (not shown).

[0027] The relative distance is obtained as a measurement value measured by the camera 10. Alternatively, it may be obtained by communication from a vehicle controller (not shown) or another controller. Note that the relative distance may also be measured using GPS, radar, a distance sensor, vehicle-to-vehicle communication with the preceding vehicle, or road-to-vehicle communication.

[0028] The steering paddle operation signal may be obtained by acquiring a steering paddle SW signal, or may be acquired by communication from a vehicle controller (not shown) or another controller.

[0029] In step S202, the motor controller 2 sets a first torque target value Tm1*. Specifically, the motor controller 2 sets the first torque target value Tm1* based on the accelerator opening θ and motor rotation speed ωm input in step S201, for example, by referring to an accelerator opening θ-torque table.

[0030] For example, in the accelerator opening θ-torque table shown in Fig. 3, the motor torque is set so that the amount of motor regeneration is large when the accelerator opening θ is 0 (fully closed). In other words, when the motor rotation speed indicates a positive value and at least when the accelerator opening θ is 0 (fully closed), a negative motor torque is set so that a regenerative braking force acts on the electric vehicle 1. However, the accelerator opening θ-torque table is not limited to that shown in Fig. 3.

[0031] In step S203, the motor controller 2 executes a target stop position calculation process. In the target stop position calculation process, the target stop position is set based on the relative distance to the preceding vehicle or obstacle acquired by the camera 10 in step S201 and the steering paddle operation signal. In addition, the motor controller 2 determines whether to intervene in stop position control based on the accelerator opening θ and the relative distance to the preceding vehicle, and sets the stop position control start flag to 1. The target stop position calculation process will be described in detail later.

[0032] In step S204, the motor controller 2 executes a constant regenerative torque calculation process. In the constant regenerative torque calculation process, a third torque target value Tm3* (constant regenerative torque Tg) that will result in a constant deceleration until control switches to stop is calculated according to the target stop position and motor rotation speed ωm (vehicle speed V) set in step S203, and the first torque target value Tm1* and the third torque target value Tm3* set in step S202 are compared in magnitude, and the lower value is set as a fourth torque target value Tm4*. Details of the constant regenerative torque calculation process will be described later.

[0033] In step S205, the motor controller 2 executes stop control processing. In the stop control processing, according to the stop position control start flag set in step S203, when the stop position control start flag = 0, 0 is added to the second torque target value Tm2* that converges to the disturbance torque estimated value Td determined by the disturbance torque estimation means as the motor rotation speed ωm decreases, and when the stop position control start flag = 1, a standard response feedback torque Tm (hereinafter, "feedback" will be referred to as "FB") corresponding to the difference between the standard motor rotation speed ωm* determined from the distance to the target stop position set in step S201 and the motor rotation speed ωm is added to the second torque target value Tm2*.

[0034] In step S205, the second torque target value Tm2* and the fourth torque target value Tm4* set in step S204 are compared in magnitude, and the higher value (the value with the smaller regenerative torque) is set as the fifth torque target value Tm5*.

[0035] The second torque target value Tm2* is a positive torque on an uphill road, a negative torque on a downhill road, and approximately zero on a flat road. This allows the vehicle to be kept stopped regardless of the gradient. Details of the stop control process will be described later.

[0036] In step S206, the motor controller 2 performs vibration suppression control processing to suppress vibrations in the driving force transmission system, such as torsional vibrations of the drive shaft 8, without wasting the drive shaft torque. Specifically, the motor controller 2 inputs the fourth torque target value Tm4* calculated in step S204 and the motor rotation speed ωm, and calculates an eighth torque target value Tm8* that suppresses vibrations in the torque transmission system (such as torsional vibrations of the drive shaft 8) without sacrificing the response of the drive shaft torque. Details of the vibration suppression control processing will be described later.

[0037] In step S207, the motor controller 2 calculates the d-axis current target value id* and the q-axis current target value iq* based on the eighth torque target value Tm8* (motor torque command value Tm*), the motor rotational speed ωm, and the DC voltage value Vdc calculated in step S205. For example, a table is prepared in advance, which determines the relationship between the motor torque command value Tm*, the motor rotational speed, the DC voltage value Vdc, and the d-axis current target value id* and the q-axis current target value iq*, based on experimental results, simulation results, etc. Then, upon acquiring the motor torque command value Tm*, the motor rotational speed ωm, and the DC voltage value Vdc, the motor controller 2 calculates the d-axis current target value id* and the q-axis current target value iq* by referring to the prepared table.

[0038] In step S208, the motor controller 2 controls the current so that the d-axis current id coincides with the d-axis current target value id* and the q-axis current iq coincides with the q-axis current target value iq*.

[0039] Specifically, the motor controller 2 calculates the d-axis current id and the q-axis current iq based on the three-phase AC currents iu, iv, and iw input in step S201 and the rotor phase α of the motor 6. Next, the motor controller 2 calculates a d-axis voltage command value vd from the deviation between the d-axis current target value id* and the d-axis current id, and calculates a q-axis voltage command value vq from the deviation between the q-axis current target value iq* and the q-axis current iq.

[0040] Note that a decoupling voltage required to cancel out the interference voltage between the d- and q-axis orthogonal coordinate axes may be added to the d-axis voltage command value vd and the q-axis voltage command value vq calculated by the motor controller 2.

[0041] Next, the motor controller 2 determines PWM signals tu(%), tv(%), and tw(%) from the d-axis voltage command value vd, the q-axis voltage command value vq, the rotor phase α of the motor 6, the three-phase AC voltage command values ​​vu, vv, and vw, and the DC voltage value Vdc. The switching elements of the inverter 3 are turned ON / OFF in accordance with the PWM signals tu, tv, and tw determined in this manner, so that the motor 6 can be driven at the desired torque indicated by the motor torque command value Tm* (eighth torque target value Tm8*).

[0042] [Target stop position calculation process] The target stop position calculation process executed in step S203 of FIG. 2 will be described in detail below.

[0043] FIG. 10 is a block diagram showing an example of a functional configuration for realizing the target stop position calculation process. The target stop position calculation process of this embodiment includes a stop position control start flag setter 1001, an inter-vehicle distance calculator 1002, and a subtracter 1003.

[0044] A stop position control start flag setter 1001 (hereinafter simply referred to as flag setter 1001) executes a stop position control start flag process that sets a stop position control start flag according to the accelerator opening θ and the relative distance to a preceding vehicle or obstacle acquired by the camera 10 (FIG. 1). The flag setter 1001 sets the stop position control start flag to 1 when the accelerator opening θ (operation amount) is zero (fully closed) and the relative distance is within a predetermined value. The flag setter 1001 also sets the stop position control start flag to 0 when the accelerator opening θ is other than zero and the relative distance is equal to or greater than a predetermined value. The predetermined value here is a relative distance that allows determination that the stopping position of the host vehicle will not be too close to a preceding vehicle or obstacle even when conventional stop control that does not set a target stop position is executed, and is set as appropriate to a value found in advance, for example, by experimentation.

[0045] The inter-vehicle distance calculator 1002 executes an inter-vehicle distance calculation process that changes a distance constant to a preceding vehicle or an obstacle in accordance with the steering paddle operation amount by the occupant (driver, etc.) and calculates a target relative distance value when the vehicle is stopped. The distance constant is a constant used to calculate a target value for the relative distance (inter-vehicle distance) between the host vehicle and a preceding vehicle or an obstacle when the vehicle is stopped. In this embodiment, the target inter-vehicle distance when the vehicle is stopped can be arbitrarily changed by changing the distance constant through steering paddle operation by the occupant (driver, etc.). FIG. 10 shows an example in which the target inter-vehicle distance is set to a larger value in stages as the steering paddle operation amount increases. The calculated inter-vehicle distance is output to a subtractor 1004 and a motor angular velocity FB torque setter 501, which will be described later.

[0046] A subtractor 1003 calculates a target stopping position by subtracting the target inter-vehicle distance calculated by the inter-vehicle distance calculator 1002 from the relative distance to the preceding vehicle or obstacle acquired by the camera 10 (FIG. 1). The calculated target stopping position is output to a motor angular velocity FB torque setter 501 (described later) as a target stopping position when the vehicle is stopped by stop control.

[0047] [Constant regenerative torque calculation process] The constant regenerative torque calculation process executed in step S204 will be described below. Fig. 11 is a block diagram showing an example of a functional configuration for realizing the constant regenerative torque calculation process.

[0048] The constant regenerative torque calculation process of this embodiment includes a phase lag compensator 1101 , a constant regenerative torque setter 1102 , a subtractor 1103 , and a torque comparator 1104 .

[0049] The phase lag compensator 1101 sets a dead time (phase lag) in the motor rotation speed ωm according to the detection delay and communication delay of the relative distance (target stop position) of the camera 10 executed in step S201. This makes it possible to reduce the difference in detection time between the relative distance (target stop position) and the motor rotation speed ωm.

[0050] A constant regenerative torque setter 1102 calculates a constant regenerative torque Tg based on the target stop position and the motor rotation speed ωm.

[0051] The detailed calculation method for the constant regenerative torque Tg is shown below. The standard response time constant of the stop control when the vehicle is about to come to a stop and the symbols in the constant regenerative torque calculation formula are as shown below.

[0052] Ra: Tire load radius Nal: Gear ratio Kv: Stop control feedback gain L c : Distance traveled with constant regenerative torque braking L ss : Distance traveled during stop control L * :Target stop position V0: Vehicle speed when constant regenerative torque braking begins V 0ss : Vehicle speed when switching from constant regenerative torque braking to stop control τ: Reference response time constant of stop control M: Mass of the vehicle F c : Constant regenerative driving force F(t): Driving force ω *m(t): motor rotation speed target value ωm(t): Motor rotation speed V(t): Vehicle speed The stop control is expressed as a motor angular velocity FB system expressed by a proportional gain as shown in equation (1).

[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058] Stop control is ω*m=0 and initial velocity V 0ss Since the vehicle speed V(t) converges asymptotically from

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[0059]

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[0060]

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[0061]

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[0062]

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[0063]

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[0064]

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[0065] The constant regenerative torque Tg is the constant regenerative driving force F c , which can be expressed as, for example, equation (13) using equations (14) and (15) described later.

[0066]

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[0067] The subtractor 1103 calculates the deviation between the constant regenerative torque Tg calculated by the constant regenerative torque setter 1102 and the disturbance torque estimated value Td calculated by the disturbance torque estimator 502 described below, and calculates this deviation as the third torque target value Tm3*.

[0068] The torque comparator 1104 compares the magnitudes of the first torque target value Tm1* and the third torque target value Tm3*. If the torque comparator 1104 determines that the third torque target value Tm3* is lower than the first torque target value Tm1* (the regenerative torque is large), it sets the third torque target value Tm3* to the fourth torque target value Tm4*. If the torque comparator 1104 determines that the first torque target value Tm1* is lower than the third torque target value Tm3*, it sets the first torque target value Tm1* to the fourth torque target value Tm4*. The torque comparator 1104 outputs the fourth torque target value Tm4* to a torque comparator 504 (FIG. 5) described below.

[0069] [Transfer characteristic Gp(s)] Next, in describing the stop control processing performed in step S205, first, the transfer characteristic Gp(s) from the motor torque Tm to the motor rotation speed ωm of the electric vehicle 1 in this embodiment will be described.

[0070] FIG. 4 is a diagram showing a model of a vehicle's driving force transmission system, and the parameters in the diagram are as follows:

[0071] Jm: Inertia of motor 6 Jw: Inertia of drive wheels 81, 82 M: Mass of the vehicle Kd: Torsional rigidity of the drivetrain Kt: Coefficient of friction between the tire and road surface N: Overall gear ratio r: tire load radius ωm: Motor rotation speed Tm*: Motor torque command value Tdt: Torque of drive wheels 81 and 82 F: Force applied to the vehicle (driving force) V: Vehicle speed (body speed) ωw: Angular velocity of the drive wheels

[0072] Then, by using the model of the driving force transmission system shown in FIG. 4, the following equation of motion can be derived.

[0073]

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[0074]

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[0075]

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[0076]

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[0077]

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[0078] Based on the equations of motion expressed by the above equations (14) to (18), the transfer characteristic Gp(s), which is the transfer function from the motor torque command value Tm* of the motor 6 to the motor rotation speed ωm, is expressed by the following equation (19).

[0079]

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[0080] However, each parameter in equation (19) is expressed by the following equation (20).

[0081]

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[0082] When examining the poles and zeros of the transfer characteristic Gp(s) expressed by the above equation (19), the transfer characteristic Gp(s) can be approximated to the transfer characteristic shown in the following equation (21), with one pole and one zero showing very close values. This means that α and β in the transfer characteristic Gp(s) of equation (21) show very close values.

[0083]

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[0084] Therefore, the vehicle model Gp(s) derived by performing pole-zero cancellation (approximating α=β) in the above equation (21) has a (second-order) / (third-order) transfer characteristic as shown in the following equation (22).

[0085]

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[0086] Using the vehicle model Gp(s) and the vibration suppression control algorithm, the vehicle model Gp(s) of equation (22) can be regarded as the transfer characteristic Gr(s) shown in the following equation (23).

[0087]

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[0088] Next, the transfer characteristic Gpv(s) from the motor torque Tm to the vehicle speed V will be described.

[0089] When the transfer characteristic Gpv(s) is calculated based on the above equations of motion, that is, equations (14) to (18), the transfer characteristic Gpv(s) is expressed by the following equation (24).

[0090]

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[0091] Here, each parameter in the above equation (24) is expressed by the following equation (25).

[0092]

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[0093] When the transfer characteristic GωV(s) from the motor rotation speed ωm to the vehicle speed V is calculated based on the above equations (22) and (24), the transfer characteristic GωV(s) is expressed by the following equation (26).

[0094]

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[0095] Next, the transfer characteristic GpF(s) from the motor torque Tm to the driving force F of the electric vehicle 1 will be described.

[0096] When the transfer characteristic GpF(s) is calculated based on the above equations of motion, that is, equations (14) to (18), the transfer characteristic GpF(s) is expressed by the following equation (27).

[0097]

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[0098] [Stop control processing] Next, the stop control process performed in step S205 of FIG. 2 will be described in detail.

[0099] Fig. 5 is a block diagram showing an example of a functional configuration for realizing the stop control process, which includes a motor angular velocity FB torque setter 501, a disturbance torque estimator 502, a subtractor 503, and a torque comparator 504.

[0100] The motor angular velocity FB torque setter 501 calculates the motor angular velocity FB torque Tω for stopping the electric vehicle 1 using the regenerative braking force of the motor 6, based on the detected motor rotation speed ωm, the target stop position calculated in the target stop position calculation process, and the stop position control start flag set in the stop position control start flag process. Details will be described with reference to FIG. 6.

[0101] FIG. 6 is a block diagram of the motor angular velocity FB torque setter 501.

[0102] The motor angular velocity FB torque setter 501 includes a multiplier 601 , a subtractor 602 , a multiplier 603 , a torque switcher 604 , a gain setter 605 , a multiplier 606 , and an adder 607 .

[0103] The multiplier 601 calculates the first motor rotation speed target value by multiplying the target stop position output from the subtractor 1003 (FIG. 10) by a gain k1 in step S203. The gain k1 is set by 1 / τ using the aforementioned τ.

[0104] A subtractor 602 calculates a motor rotation speed deviation from the difference between the first motor rotation speed target value calculated by the multiplier 601 and the motor rotation speed ωm.

[0105] A multiplier 603 calculates the reference response FB torque Tm by multiplying the motor rotation speed deviation calculated by the subtractor 602 by a gain k2. The gain k2 may be obtained by using a general PI control.

[0106] The torque switch 604 switches the standard response FB torque according to the stop position control start flag set in step S203. That is, when the stop position control start flag is 1, the standard response FB torque is set to Tm calculated by the multiplier 603, and when the stop position control start flag is 0, the standard response FB torque is set to 0.

[0107] The gain setter 605 is provided with a map showing the relationship between the FB gain (Kvref) and a predetermined inter-vehicle distance to a preceding vehicle or obstacle calculated by the inter-vehicle distance calculator 1002 (FIG. 10). The gain setter 605 refers to the map and outputs Kvref corresponding to the input inter-vehicle distance to the multiplier 606. Here, in the map, Kvref is set to a larger value as the inter-vehicle distance increases. Note that Kvref may be calculated using a formula or the like that uses the inter-vehicle distance as an input value.

[0108] The multiplier 606 multiplies the motor rotation speed ωm by Kvref input from the gain setter 605 to calculate the first motor angular speed FB torque Tω1, and outputs this to the adder 607.

[0109] The adder 607 adds the reference response FB torque Tm output from the torque switch 604 and the first motor angular velocity FB torque Tω1 output from the multiplier 606 to calculate the motor angular velocity FB torque Tω.

[0110] 5, the disturbance torque estimator 502 calculates the disturbance torque estimated value Td based on the motor rotation speed ωm and the fifth torque target value Tm5*. Details of the disturbance torque estimator 502 will be described with reference to FIG.

[0111] 7 is a block diagram of the disturbance torque estimator 502. The disturbance torque estimator 502 includes a control block 701, a control block 702, and a subtractor 703.

[0112] The control block 701 functions as a filter having a transfer characteristic of H1(s) / Gr(s), and calculates a first motor torque estimate by inputting the motor rotation speed ωm and performing filtering processing.

[0113] Of the transfer characteristics of the control block 701, Gr(s) constituting the denominator is the transfer characteristic shown in the above equation (23), and is a vehicle model derived from the vehicle model Gp(s) of equation (22) and the vibration suppression control algorithm. Furthermore, H1(s) constituting the numerator of the transfer characteristic is a low-pass filter having transfer characteristics 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 model Gp(s).

[0114] The control block 702 functions as a filter having a transfer characteristic H1(s), and calculates a second motor torque estimate by inputting the fifth torque target value Tm5* and performing filtering processing taking into account the transfer characteristic H1(s).

[0115] The subtractor 703 outputs the deviation between the first motor torque estimated value and the second motor torque estimated value as the disturbance torque estimated value Td. The subtractor 703 of this embodiment calculates the disturbance torque estimated value Td by subtracting the first motor torque estimated value from the second motor torque estimated value.

[0116] Although the disturbance torque estimated value Td in this embodiment is estimated by the disturbance observer shown in FIG. 8, it may also be estimated using a measuring instrument such as a vehicle longitudinal G sensor.

[0117] Here, possible disturbances acting on the vehicle include air resistance, modeling errors due to variations in vehicle mass resulting from the number of occupants and load, tire rolling resistance, and road surface gradient resistance. However, the dominant disturbance factor when the vehicle is about to come to a stop is gradient resistance. Although the disturbance factors vary depending on the driving conditions, the disturbance torque estimator 502 calculates the disturbance torque estimate value Td based on the fifth torque target value Tm5*, the motor rotation speed ωm, and the transfer characteristic Gr(s) derived from the vibration suppression control algorithm and the vehicle model Gp(s), thereby making it possible to estimate the above-mentioned disturbance factors all at once. This allows the vehicle to decelerate and come to a smooth stop under any driving conditions.

[0118] As shown in FIG. 5, a subtractor 503 calculates the deviation between the motor angular velocity FB torque Tω calculated by the motor angular velocity FB torque setter 501 and the disturbance torque estimated value Td calculated by the disturbance torque estimator 502, and calculates this as a second torque target value Tm2*.

[0119] The torque comparator 504 compares the magnitude of the fourth torque target value Tm4* output from the torque comparator 1104 (FIG. 11) with the magnitude of the second torque target value Tm2* output from the subtractor 503.

[0120] Then, if the torque comparator 504 determines that the second torque target value Tm2* is higher (the regenerative torque is small) than the fourth torque target value Tm4*, or if the stop control start flag set by the flag setter 1001 (FIG. 10) is 1, it determines that a stop is imminent and executes stop control by switching the fifth torque target value Tm5* from the fourth torque target value Tm4* to the second torque target value Tm2*.

[0121] Furthermore, if the torque comparator 504 determines that the fourth torque target value Tm4* is higher than the second torque target value Tm2*, or if the stop control start flag set by the flag setter 1001 (FIG. 10) is 0, it determines that the vehicle is not about to stop, and switches the fifth torque target value Tm5* from the second torque target value Tm2* to the fourth torque target value Tm4*.

[0122] In order to maintain the vehicle stopped state, the second torque target value Tm2* converges to a positive torque on an uphill road, a negative torque on a downhill road, and approximately zero on a flat road.

[0123] [Vibration control processing] Next, the vibration suppression control process performed in step S206 in FIG. 2 will be described in detail.

[0124] 8 is a block diagram showing an example of a functional configuration for implementing vibration suppression control processing that suppresses vibrations in the driving force transmission system of the electric vehicle 1. The vibration suppression control processing is configured by a combination of an FF (feedforward) compensator and an FB (feedback) compensator.

[0125] In FIG. 8, a control block 801 is shown as the FF compensator, and an adder 805, a control block 802, a subtractor 806, a control block 803, and a multiplier 804 are shown as the FB compensator.

[0126] The control block 801 functions as a filter having a transfer characteristic of Gr(s) / Gp(s), and calculates a sixth torque target value Tm6* by inputting the fifth torque target value Tm5* and performing filtering processing to reduce torsional vibrations of the electric vehicle 1.

[0127] Of the transfer characteristics of control block 801, Gp(s) constituting the denominator is the vehicle model Gp(s) of equation (22), and Gr(s) constituting the numerator is the vehicle model of equation (23) derived from the vehicle model Gp(s) and the vibration damping control algorithm.

[0128] An adder 805 adds the output of a multiplier 804 that constitutes an FB compensator to the sixth torque target value Tm6* obtained by FF control, and outputs an eighth torque target value Tm8*.

[0129] The control block 802 functions as a filter having the vehicle model Gp(s). Therefore, the control block 802 receives the sixth torque target value Tm6* and performs filtering processing taking the vehicle model Gp(s) into consideration to calculate the motor rotation speed estimated value ωm^ indicating the estimated value of the motor rotation speed ωm.

[0130] The subtractor 806 outputs the deviation between the motor rotation speed estimated value ωm^ and the motor rotation speed ωm. The subtractor 806 of this embodiment calculates the deviation by subtracting the motor rotation speed ωm from the motor rotation speed estimated value ωm^.

[0131] The control block 803 functions as a filter having a transfer characteristic of H2(s) / Gp(s), and calculates an estimated disturbance d^ indicating an estimated value of the disturbance d by inputting the deviation of the subtractor 806 and performing a filtering process.

[0132] Among the transfer characteristics of the control block 803, the vehicle model Gp(s) of equation (22) and the vehicle model derived from the vibration suppression control algorithm, and H2(s) constituting the numerator, is a band-pass filter having transfer characteristics that serve as an FB element that reduces only vibrations.

[0133] The multiplier 804 multiplies the estimated disturbance d^ from the control block 803 by the FB gain K FB to calculate a seventh torque target value Tm7* that takes into account the control error of the motor rotation speed ωm. Then, an adder 805 adds the seventh torque target value Tm7* to the sixth torque target value Tm6*, and the motor rotation speed ωm is fed back to the eighth torque target value Tm8* so as to suppress the occurrence of torsional vibrations in the electric vehicle 1.

[0134] Next, the transfer characteristic H2(s) of the control block 803 will be described.

[0135] FIG. 9 is a diagram illustrating an example of a band-pass filter for realizing the transfer characteristic H2(s).

[0136] The transfer characteristic H2(s) is set such that the attenuation characteristic on the low-pass side and the attenuation characteristic on the high-pass side are substantially the same, and the torsional resonance frequency of the drive system is near the center of the passband on a logarithmic axis (log scale). By setting the characteristics of the filter in this way, the most significant effect can be obtained.

[0137] For example, when the transfer characteristic H2(s) is constituted using a first-order high-pass filter and a first-order low-pass filter, the transfer characteristic H2(s) is expressed by the following equation (28), where the frequency fp is set to the torsional resonance frequency of the drive system, and k is set to an arbitrary value.

[0138]

Equation

[0139] However, τ L = 1 / (2πf HC ), f HC = k·f p , τ H = 1 / (2πf LC ), f LC = f p / k.

[0140] In this embodiment, since torsional vibration occurs in the drive force transmission system of the electric vehicle 1, stop control and vibration damping control are used in combination. However, for an electric vehicle 1 in which torsional vibration does not occur in the drive force transmission system, the vibration damping control process in step S206 may not be executed.

[0141] [Time Chart] Hereinafter, the effects when this embodiment is applied will be described. FIG. 12 is a time chart until the electric vehicle 1 stops at the target stop position. FIG. 12(a) shows the case where the electric vehicle 1 is stopped at the target stop position according to the prior art with initial speeds V0, V1, V2 (V0 < V1 < V2), and FIG. 12(b) shows the case where the electric vehicle 1 is stopped at the target stop position by the control of the control device of the electric vehicle 1 of this embodiment with initial speeds V0, V1, V2 (V0 < V1 < V2).

[0142] Although detailed explanation will be omitted, in the stop control of an electric vehicle 1 in the prior art (see Patent Document 1), a target rotation speed of the motor 6 is set based on the vehicle speed at the start of the stop control and the target stop position, a regenerative torque is generated based on the difference between the target rotation speed and the detected rotation speed of the motor 6, and control is performed to converge the regenerative torque to the disturbance torque just before stopping, but the regenerative torque is not directly controlled as in this embodiment.

[0143] In the case of an initial speed V0 of the prior art, the driver's accelerator opening operation amount becomes zero at time t0, and at time t4 it is determined that stop control should be started and stop control is initiated (for example, the motor torque command value Tm* switches from being derived from the first torque target value Tm1* to being derived from the second torque target value Tm2*), and by time t6 the motor rotation speed asymptotically converges to zero due to stop control. It can be seen that if the vehicle is stopped short of the distance to a stopped vehicle or obstacle in front, and the distance to the stopped vehicle or obstacle is far enough relative to the initial speed, stop position control does not intervene.

[0144] Next, in the case of an initial velocity V1 (>V0), it is determined that stop position control should be started at time t2, and stop position control is initiated (for example, the motor torque command value Tm* switches from being derived from the first torque target value Tm1* to being derived from the second torque target value Tm2*), and while the motor rotation speed asymptotically converges to zero towards time t6, the position also asymptotically converges to the position of a stopped vehicle in front or an obstacle.

[0145] Similarly, in the case of initial speed V2 (V1), it is determined that stop position control has started at time t1 and stop position control is initiated (for example, the motor torque command value Tm* switches from being derived from the first torque target value Tm1* to being derived from the second torque target value Tm2*), and since the initial speed is larger than the initial speed V0, a ​​strong regenerative torque is output, and while the motor rotation speed asymptotically converges to zero towards time t6, the position also asymptotically converges to the position of a stopped vehicle in front or an obstacle.

[0146] However, it can be seen that the fluctuation range / speed of the torque is large from the time when the initial velocities V1 and V2 are switched to the stop position control torque (derived from the second torque target value Tm2*, for example) at times t1 and t2, respectively, until time t4. Because the fluctuation in motor torque is large, the fluctuation in vehicle deceleration is large, and the vehicle is unable to stop smoothly.

[0147] More specifically, in the prior art, the torque control means before the vehicle is about to stop uses a constant deceleration determined by the driving force map, etc., so the vehicle speed at which position control intervenes and the distance to the stopping position are not uniquely determined. Therefore, when the distance to the target stopping position is short, the regenerative torque is increased after the vehicle is about to stop, generating a strong deceleration to stop the vehicle at the stopping position. This results in large fluctuations in acceleration just before stopping, making it impossible to achieve a smooth stop. Furthermore, if deceleration beyond the maximum regenerative torque of the motor 6 is required, there is a risk that the vehicle will not be able to stop at the stopping position and may rear-end the vehicle in front.

[0148] On the other hand, in this embodiment, when the initial speed is V0, the driver's accelerator opening amount becomes zero at time t0, and it is determined that stop control should be started at time t4, and stop control is started.Towards time t6, the motor rotation speed asymptotically converges to zero due to stop control.

[0149] At this time, from t0 to t4, the first torque target value Tm1* is lower than the third torque target value Tm3*, so the motor torque command value Tm* is derived from the first torque target value Tm1*, and from t4 onwards, the second torque target value Tm2* is higher than the first torque target value Tm1*, so the motor torque command value Tm* is derived from the second torque target value Tm2*.

[0150] At an initial speed of V0, as with the prior art, the vehicle stops at a target stopping position based on the distance to the stopped vehicle or obstacle in front, and it can be seen that stopping position control does not intervene if the distance to the stopped vehicle or obstacle in front is sufficiently far relative to the initial speed.

[0151] Next, in the case of initial velocity V1, the driver's accelerator opening amount becomes zero at time t0, and at the same time, it is determined that stop control has started. A constant motor torque without any change in acceleration is output until time t5, and while the motor rotation speed asymptotically converges to zero from time t5 to time t6, the position also asymptotically converges to the target stop position where the vehicle is stopped.

[0152] At this time, from t0 to t5, the third torque target value Tm3* is lower than the first torque target value Tm1*, so the motor torque command value Tm* is derived from the third torque target value Tm3*, and from t5 onwards, the second torque target value Tm2* is higher than the third torque target value Tm3*, so the motor torque command value Tm* is derived from the second torque target value Tm2*.

[0153] Furthermore, in the case of initial velocity V2, a strong regenerative torque is generated according to the initial velocity from time t0 to time t3, but a constant motor torque without any change in acceleration is output, and from time t3 to time t6, the motor rotation speed similarly converges asymptotically to zero, while the position also asymptotically converges to the target stopping position in front of a stopped vehicle or obstacle ahead.

[0154] At this time, from t0 to t3, the third torque target value Tm3* is lower than the first torque target value Tm1*, so the motor torque command value Tm* is derived from the third torque target value Tm3*, and from t3 onwards, the second torque target value Tm2* is higher than the third torque target value Tm3*, so the motor torque command value Tm* is derived from the second torque target value Tm2*.

[0155] It can be seen that in this embodiment, the motor torque is kept constant from time t0 to time t4, and changes in the vehicle deceleration are suppressed, compared to the conventional technology. Therefore, it can be seen that in this embodiment, the deceleration is kept roughly constant regardless of the initial speed, and the vehicle can be decelerated and stopped smoothly.

[0156] [Effects of this embodiment] According to the control method for an electric vehicle 1 of this embodiment, when stopping the electric vehicle 1 by the regenerative torque of the motor 6 that drives the electric vehicle 1, the rotation speed of the motor 6 is detected, a disturbance torque acting on the electric vehicle 1 is estimated, a first torque target value Tm1* is calculated based on an accelerator operation amount, a second torque target value Tm2* that converges to the disturbance torque as the rotation speed of the motor 6 decreases, and when a predetermined condition that indicates that the vehicle is about to stop is satisfied, a regenerative torque is generated based on the second torque target value Tm2* to stop the electric vehicle 1, and the progress of the electric vehicle 1 is controlled. A position at a predetermined relative distance set by an occupant (driver, etc.) relative to a target object (vehicle ahead, obstacle) ahead in the travel direction is set as a target stop position, a third torque target value Tm3* is set according to the target stop position and vehicle speed and capable of stopping the electric vehicle 1 at the target stop position, a regenerative torque is generated based on the lower of the first torque target value Tm1* and the third torque target value Tm3* until a predetermined condition for determining that the vehicle is about to stop is satisfied, and the third torque target value Tm3* is maintained at a substantially constant deceleration (a constant regenerative driving force F corresponding to the deceleration) until the predetermined condition for determining that the vehicle is about to stop is satisfied. c ) is calculated based on the regenerative torque (constant regenerative torque Tg).

[0157] The above method calculates the target angular velocity (first motor rotational speed target value) according to the distance to the target stopping position when the motor torque switches to that derived from the second torque target value Tm2*, and controls the motor torque, making it possible to stop the vehicle at a targeted position. Furthermore, because the regenerative torque (constant regenerative torque Tg) is calculated so that the deceleration is approximately constant until a predetermined condition is met that determines that the vehicle is about to stop, the distance to the target stopping position and vehicle speed when the motor torque switches to that derived from the second torque target value Tm2* can be uniquely determined, suppressing fluctuations in acceleration when the vehicle is about to stop and achieving a smooth stop.

[0158] In this embodiment, the regenerative torque (constant regenerative torque Tg) that results in a substantially constant deceleration is calculated by calculating the vehicle speed (V0) and the target stop position (L) when the accelerator operation amount becomes zero and the relative distance becomes within a predetermined value. *) (Equations (12) and (13)). This improves the accuracy of calculating the third torque target value Tm3*, making it possible to achieve a smoother stop.

[0159] In this embodiment, when the electric vehicle 1 is decelerated and stopped based on the second torque target value Tm2*, the electric vehicle 1 is decelerated based on a standard deceleration corresponding to the electric vehicle 1, and the third torque target value Tm3* is set as a moving distance (L) of the electric vehicle 1 when the electric vehicle 1 is decelerated with a regenerative torque (constant regenerative torque Tg) based on the third torque target value Tm3*. c ), and the travel distance (L ss ) is the target stop position (L * ) is calculated as follows.

[0160] By using the above method, the distance required to stop the vehicle after the vehicle is about to stop (L ss ) and calculates a regenerative torque (constant regenerative torque Tg) that results in a roughly constant deceleration just before the vehicle stops. This makes it possible to smoothly switch to the torque when switching from normal drive control (when the stop position control flag is 0) to stop control (when the stop position control flag is 1), and also makes it possible to smoothly switch to the torque when switching from normal drive control (when the stop position control flag is 0) to stop control (when the stop position control flag is 1) and to achieve a predetermined target stop position (L * ) and can stop smoothly.

[0161] In this embodiment, the standard deceleration is set based on the first-order transfer characteristic (equation (4)) that causes the rotational speed of the motor 6 to converge from the actual measured value (ωm) to the target value (ωm*), and the time constant of the transfer characteristic (standard response time constant τ) is set to be larger as the relative distance becomes shorter.

[0162] With the above method, when the predetermined relative distance set by the occupant (driver, etc.) is set short, the vehicle converges / stops slowly to the target stopping position compared to normal stopping control, eliminating the sense of anxiety caused by suddenly approaching the vehicle ahead. It also makes it possible to slowly close the relative distance just before stopping, as when the driver stops an electric vehicle. Even if slippage and motor regeneration restrictions occur just before stopping, the vehicle can still stop at the target stopping position without colliding with the vehicle ahead.

[0163] In this embodiment, a regenerative torque (constant regenerative torque Tg) that results in an approximately constant deceleration is calculated based on the target stop position and the actual measured value (ωm) of the rotational speed of motor 6, and phase lag compensation is performed on the actual measured value (ωm) of the rotational speed of motor 6.

[0164] By using the above method, when calculating the regenerative torque (constant regenerative torque Tg) that results in an approximately constant deceleration, the detection delay and communication delay of the current vehicle speed (actual measured value (ωm) of the rotational speed of the motor 6) and the target stop position are taken into consideration, and by aligning the phase, it is possible to suppress regenerative torque fluctuations that occur due to phase shifts.

[0165] In this embodiment, a correction torque (motor angular velocity FB torque Tω) corresponding to the difference between the standard deceleration (first motor rotational speed target value corresponding to the standard deceleration) and the actual deceleration (motor rotational speed ωm corresponding to the actual deceleration) is calculated, and a second torque target value Tm2* is calculated based on the difference between the correction torque (motor angular velocity FB torque Tω) and the disturbance torque (disturbance torque estimated value Td) (FIG. 5).

[0166] Using the above method, a correction torque (motor angular velocity FB torque Tω) corresponding to the difference (which changes according to changes in this difference) between the standard deceleration for stop control (first motor rotational speed target value corresponding to the standard deceleration) and the actual deceleration (motor rotational speed ωm corresponding to the actual deceleration) is calculated, and by adding this to the second torque target value Tm2*, it becomes possible to correct errors (vehicle mass, road surface disturbances, and positional variations of the camera 10) just before stopping, and it becomes possible to accurately stop the vehicle at the target stopping position even if an error occurs between the standard deceleration and the actual deceleration.

[0167] In this embodiment, the position of the target (vehicle ahead, obstacle) is set based on the measurement value of an optical measurement means (for example, camera 10, radar), which makes it possible to calculate the target stopping position easily and quickly.

[0168] In this embodiment, the predetermined condition for determining that the vehicle is about to stop is when, when the lower of the first torque target value Tm1* and the third torque target value Tm3* is set to the fourth torque target value Tm4*, the second torque target value Tm2* becomes higher than the fourth torque target value Tm4* while the electric vehicle 1 is decelerating.

[0169] By using the above method, by selecting high to switch between the fourth torque target value Tm4*, which is the input value for the motor torque command value Tm* before determining that the vehicle is about to stop, and the second torque target value Tm2*, which is the input value for the motor torque command value Tm* after determining that the vehicle is about to stop, it is possible to prevent torque steps at the time of switching, transfer control to a smooth transition, and stop the vehicle at a position at the relative distance intended by the occupant (driver, etc.).

[0170] Furthermore, according to the control device for electric vehicle 1 of this embodiment, the control device for electric vehicle 1 stops electric vehicle 1 by the regenerative torque of motor 6 that drives electric vehicle 1, and includes motor rotation speed detection means (rotation sensor 9) that detects the rotation speed of motor 6, accelerator operation amount detection means (accelerator opening sensor, etc.) that detects the accelerator operation amount, disturbance torque estimation means (disturbance torque estimator 502) that estimates disturbance torque acting on electric vehicle 1 (disturbance torque estimated value Td), and a first a first torque target value setting means (motor controller 2) for setting a torque target value Tm1*; a second torque target value setting means (motor angular velocity FB torque setter 501, disturbance torque estimator 502, subtractor 503) for setting a second torque target value Tm2* that converges to the disturbance torque (disturbance torque estimated value Td) as the rotation speed of the motor 6 decreases; and a target stop position set by a passenger (driver, etc.) at a predetermined relative distance from a target object (vehicle ahead, obstacle) ahead in the traveling direction of the electric vehicle 1. a third torque target value setting means (constant regenerative torque setter 1102, subtractor 1103) for setting a third torque target value Tm3* that is set according to the target stop position and the vehicle speed and that can stop the electric vehicle 1 at the target stop position; a first torque target value selection means (torque comparator 1104) for selecting the lower of the first torque target value Tm1* and the third torque target value Tm3* as a fourth torque target value Tm4*; and a second torque target value selection means (torque comparator 504) that selects and outputs a fourth torque target value Tm4* to the motor 6 side until a predetermined condition for determining that the vehicle is about to stop is satisfied, and selects and outputs a second torque target value Tm2* to the motor 6 side when the predetermined condition for determining that the vehicle is about to stop is satisfied, and a third torque target value setting means (constant regenerative torque setter 1102) that sets the third torque target value Tm3* at a substantially constant deceleration (constant regenerative driving force F corresponding to the deceleration) until the predetermined condition for determining that the vehicle is about to stop is satisfied. c ) is calculated based on the regenerative torque (constant regenerative torque Tg).

[0171] With the above configuration, the target angular velocity (first motor rotational speed target value) is calculated according to the distance to the target stopping position when the motor torque switches to that derived from the second torque target value Tm2*, and by controlling the motor torque, it becomes possible to stop the vehicle at a targeted position. Furthermore, because the regenerative torque (constant regenerative torque Tg) is calculated so that the deceleration is approximately constant until a predetermined condition is met that determines that the vehicle is about to stop, the distance to the target stopping position and vehicle speed when the motor torque switches to that derived from the second torque target value Tm2* can be uniquely determined, which suppresses fluctuations in acceleration when the vehicle is about to stop and achieves a smooth stop.

[0172] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate. [Explanation of symbols]

[0173] 1 Electric vehicle 1, 2 Motor controller, 6 Motor, 9 Rotation sensor, 501 Motor angular velocity FB torque setter, 502 Disturbance torque estimator, 504 Torque comparator, 1001 Inter-vehicle distance calculator, 1102 Constant regenerative torque setter, 1104 Torque comparator

Claims

1. A control method for an electric vehicle, when stopping an electric vehicle by regenerative torque of a motor that drives the electric vehicle, detects a rotational speed of the motor, estimates a disturbance torque acting on the electric vehicle, calculates a first torque target value based on an accelerator operation amount, calculates a second torque target value that converges to the disturbance torque as the rotational speed of the motor decreases, and generates the regenerative torque based on the second torque target value to stop the electric vehicle when a predetermined condition is satisfied that indicates that the vehicle is about to stop, setting a target stop position at a predetermined relative distance set by a driver with respect to a target object ahead in a traveling direction of the electric vehicle; setting a third torque target value that is set in accordance with the target stop position and a vehicle speed and that can stop the electric vehicle at the target stop position; generating the regenerative torque based on the lower of the first torque target value and the third torque target value until a predetermined condition for determining that the vehicle is about to stop is satisfied; a control method for an electric vehicle, the control method calculating the third torque target value based on the regenerative torque that results in a substantially constant deceleration until a predetermined condition is met, whereby it is determined that the vehicle is about to come to a stop;

2. 2. The control method for an electric vehicle according to claim 1, wherein the regenerative torque that results in the approximately constant deceleration is calculated based on the vehicle speed and the target stop position when the accelerator operation amount becomes zero and the relative distance is within a predetermined value.

3. decelerating the electric vehicle based on a reference deceleration corresponding to the electric vehicle when decelerating and stopping the electric vehicle based on the second torque target value; 2. The method for controlling an electric vehicle according to claim 1, wherein the third torque target value is calculated so that the target stop position is a sum of a travel distance of the electric vehicle when the electric vehicle is decelerated by the regenerative torque based on the third torque target value and a travel distance of the electric vehicle until the electric vehicle is decelerated and stopped by the regenerative torque based on the second torque target value.

4. 4. The control method for an electric vehicle according to claim 3, wherein the standard deceleration is set based on a first-order transfer characteristic that causes the rotational speed of the motor to converge from an actual measured value to a target value, and a time constant of the transfer characteristic is set to be larger as the relative distance becomes shorter.

5. 4. The method for controlling an electric vehicle according to claim 3, further comprising: calculating a regenerative torque that results in the substantially constant deceleration based on the target stop position and an actual measurement value of the rotational speed of the motor; and performing phase lag compensation on the actual measurement value of the rotational speed of the motor.

6. 4. The method for controlling an electric vehicle according to claim 3, further comprising the steps of: calculating a correction torque according to a difference between the standard deceleration and an actual deceleration; and calculating the second torque target value based on the difference between the correction torque and the disturbance torque.

7. 2. The method for controlling an electric vehicle according to claim 1, wherein the position of the target object is set based on a measurement value obtained by an optical measurement means.

8. 2. The control method for an electric vehicle according to claim 1, wherein the predetermined condition for determining that the electric vehicle is about to stop is when, when the lower of the first torque target value and the third torque target value is set as a fourth torque target value, the second torque target value becomes higher than the fourth torque target value during deceleration of the electric vehicle.

9. A control device for an electric vehicle that stops an electric vehicle by using a regenerative torque of a motor that drives the electric vehicle, a motor rotation speed detection means for detecting the rotation speed of the motor; accelerator operation amount detection means for detecting an accelerator operation amount; a disturbance torque estimation means for estimating a disturbance torque acting on the electric vehicle; a first torque target value setting means for setting a first torque target value based on the accelerator operation amount; a second torque target value setting means for setting a second torque target value that converges to the disturbance torque as the rotational speed of the motor decreases; a target stop position setting means for setting a position at a predetermined relative distance set by a driver with respect to a target object ahead in a traveling direction of the electric vehicle as a target stop position; a third torque target value setting means for setting a third torque target value that is set in accordance with the target stop position and a vehicle speed and that can stop the electric vehicle at the target stop position; a first torque target value selection means for selecting the lower of the first torque target value and the third torque target value as a fourth torque target value; a second torque target value selection means for selecting the fourth torque target value and outputting it to the motor side until a predetermined condition for determining that the vehicle is about to stop is satisfied, and for selecting the second torque target value and outputting it to the motor side when the predetermined condition for determining that the vehicle is about to stop is satisfied, The third torque target value setting means A control device for an electric vehicle that calculates the third torque target value based on the regenerative torque that results in a substantially constant deceleration until a predetermined condition is met, indicating that the vehicle is about to come to a stop.

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