JP2022121270A - Control method of vehicle and control system of vehicle - Google Patents

Abstract

To provide a control method of a vehicle and a control system of the vehicle which prevent heat generation of a driving motor and deterioration of an electric mileage upon stoppage of the vehicle.SOLUTION: A control method of a vehicle includes a control step (step S203) of controlling a torque of a driving motor 4 so as to converge disturbance actuated to the vehicle 10 into a disturbance torque estimated value determined by estimating the disturbance when the vehicle 10 stops based on an acceleration amount. In the control step, of a period when the vehicle 10 is decelerating to a stop: in a first period from a time with a relatively high vehicle speed range to a time with a relatively low vehicle speed range, the torque of the driving motor 4 is controlled to converge into a disturbance torque estimated value; and in a second period from a time with the relatively low vehicle speed range to a time after stoppage of the vehicle 10, the torque of the driving motor 4 is controlled to converge into a torque target value in which an extent of the disturbance torque estimated value is reduced based on an inclination of a traveling path of the vehicle 10.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle control method and vehicle control system driven by a drive motor.

Conventionally, there has been proposed a technique of stopping a vehicle by using regenerative braking force of a drive motor when the amount of operation of the accelerator pedal is reduced or becomes zero, and furthermore controlling the torque of the drive motor to maintain the stopped state. there is For example, when the accelerator pedal operation amount is less than a predetermined value and the vehicle is about to stop, a technique has been proposed in which the estimated vehicle speed decreases and the torque command value converges to the disturbance torque estimated value. (See Patent Document 1, for example).

JP 2019-22339 A

In the conventional technology described above, when the vehicle is about to stop, the estimated vehicle speed decreases and the drive torque of the drive motor is adjusted to converge to the estimated disturbance torque value that is roughly the gradient resistance. Here, when the vehicle runs on sandy ground or deep snow, the running resistance increases due to the sinking characteristics of the tires on sandy ground or deep snow, and the disturbance torque estimation value often increases. Therefore, when the vehicle is stopped on a road surface such as sand or deep snow using the conventional technology described above, the estimated disturbance torque value may become a larger value than the slope resistance that increases according to the slope of the road surface. . In this case, the drive torque of the drive motor output to maintain the stopped state may become larger than necessary. Therefore, it is important to prevent the heat generation of the drive motor and the deterioration of the electricity consumption due to the continuous stopping of the vehicle while the unnecessary driving torque is continuously input.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent heat generation of a drive motor and deterioration of electricity consumption when a vehicle is stopped.

One aspect of the present invention is a control method for a vehicle that uses a drive motor as a traveling drive source and decelerates by regenerative braking force of the drive motor. This control method includes a control step of controlling torque of a drive motor so as to converge to a disturbance torque estimated value obtained by estimating a disturbance acting on the vehicle when the vehicle stops based on an accelerator operation amount. . In this control step, the torque of the drive motor is converged to the disturbance torque estimated value in a first period from a relatively high vehicle speed range to a relatively low vehicle speed range among the periods when the vehicle stops. In the second period from the relatively low vehicle speed range to after the vehicle stops, the magnitude of the disturbance torque estimate is based on the gradient of the road on which the vehicle is running. is controlled so as to converge the torque of the drive motor to the torque target value with the reduced value.

According to the present invention, it is possible to prevent heat generation of the drive motor and deterioration of electricity consumption when the vehicle is stopped.

FIG. 1 is a block diagram illustrating the main system configuration of a vehicle. FIG. 2 is a block diagram showing a main system configuration example of the vehicle. FIG. 3 is a flowchart showing an example of the procedure of vehicle control processing by the motor controller. FIG. 4 is a diagram showing an example of an accelerator opening-torque table used when obtaining a target value of motor torque. FIG. 5 is a diagram that models the driving force transmission system of the vehicle. FIG. 6 is a diagram showing an example of a calculation method for calculating the slope resistance estimated value used in the stop control process. FIG. 7 is a block diagram showing a functional configuration example of a motor controller. FIG. 8 is a block diagram showing a functional configuration example of a vehicle speed F/B torque setting unit. FIG. 9 is a block diagram showing a functional configuration example of a disturbance torque estimator. FIG. 10 is a block diagram showing a functional configuration example of a stop maintaining torque switching unit. FIG. 11 is a diagram showing a map used when the stop maintaining torque switching unit calculates the stop maintaining torque. FIG. 12 is a block diagram showing a functional configuration example of a motor controller. FIG. 13 is a diagram showing H ₂ (s) frequency characteristics. FIG. 14 is a time chart when the stop control process is executed on a flat road. FIG. 15 is a time chart when the stop control process is executed on an uphill road. FIG. 16 is a diagram showing a configuration example of a 4WD electric vehicle.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Vehicle configuration example]
FIG. 1 is a block diagram illustrating the main system configuration of a vehicle 10 to which the control method according to this embodiment is applied.

Note that the vehicle 10 in the present embodiment is assumed to be an electric vehicle that includes a drive motor 4 (electric motor) as a travel drive source and can travel by the driving force of the drive motor 4 . Such electric vehicles include electric vehicles (EV), hybrid vehicles (HEV), and the like.

As shown in FIG. 1, a vehicle 10 mainly includes a battery 1, a motor controller 2, an inverter 3, a drive motor 4, and various sensors (rotation sensor 6, current sensor 7, longitudinal acceleration sensor 11). including.

The battery 1 functions as a power source that supplies (discharges) drive power to the drive motor 4, and is connected to the inverter 3 so that it can be charged by receiving regenerative power supplied from the drive motor 4. there is Note that the battery 1 is an example of a DC power supply.

The motor controller 2 is, for example, a computer composed of a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input/output interface (I/O interface).

The motor controller 2 receives the value a detected by the longitudinal acceleration sensor 11, the vehicle speed V, the accelerator opening Apo, the rotor phase θ of the drive motor 4, and the current flowing through the drive motor 4 (hereinafter also simply referred to as "motor current Im"). ) are inputted as digital signals of various vehicle variables indicating the vehicle state. The motor controller 2 calculates a torque command value as the torque to be output by the drive motor 4 based on various signals that are input. Furthermore, the motor controller 2 generates a PWM signal for driving the inverter 3 based on the calculated torque command value.

The inverter 3 has two switching elements (for example, power semiconductor elements such as IGBTs and MOS-FETs) provided corresponding to each phase. The inverter 3 turns on/off the switching element based on the PWM signal generated by the motor controller 2 to convert the DC current supplied from the battery 1 to AC current or inversely convert it to the AC current, which is supplied to the drive motor 4. Adjust the supplied current to the desired value.

The drive motor 4 is configured as a three-phase AC motor. The drive motor 4 generates a drive force (or regenerative braking force) for the vehicle 10 from the alternating current supplied by the inverter 3 . The driving force (or regenerative braking force) generated by the driving motor 4 is transmitted to the driving wheels 9L and 9R via the power transmission system (reduction gear 5, drive shaft 8, etc.) of the vehicle 10.

The drive motor 4 recovers the kinetic energy of the vehicle 10 as electrical energy by generating regenerative braking force when rotated by the driving wheels 9L and 9R while the vehicle 10 is running. In this case, the inverter 3 converts alternating current generated during regenerative operation into direct current and supplies the direct current to the battery 1 .

The rotation sensor 6 detects the rotor phase θ of the drive motor 4 and outputs it to the motor controller 2 . Note that the rotation sensor 6 is composed of, for example, a resolver, an encoder, or the like.

The current sensor 7 detects each phase component of the motor current Im, particularly the three-phase alternating current (i _u , _iv , i _w ). Since the sum of the three-phase AC currents (i _u , _iv , i _w ) is 0, any two phase currents are detected by the current sensor 7, and the remaining one phase current is calculated. good too. Below, the detected values of the three-phase AC currents ( _iu , _iv , _iw ) are also referred to as "three-phase current detected values ( _{iu_d} , _{iv_d} , _{iw_d} )".

The longitudinal acceleration sensor 11 is a sensor that measures the longitudinal acceleration of the vehicle 10 and outputs the detected value a to the motor controller 2 . Further, by measuring the acceleration in the longitudinal direction of the vehicle 10 with the longitudinal acceleration sensor 11, it is possible to measure the degree of movement, inclination, vibration, etc. of the vehicle 10. FIG. Note that the longitudinal acceleration sensor 11 is an example of means for measuring or estimating the road surface inclination.

[Vehicle system configuration example]
FIG. 2 is a block diagram showing a main system configuration example of the vehicle 10. As shown in FIG. The vehicle 10 includes a battery 1, an inverter 3, a drive motor 4, a rotation sensor 6, a current sensor 7, a torque target value calculator 101, a slope resistance estimator 102, a stop controller 103, a torque comparator A section 104 , a damping control section 105 , a current-voltage converter 106 , a current controller 107 , coordinate converters 108 and 110 , a PWM converter 109 , and a rotation speed calculator 111 . Each part from the torque target value calculation part 101 to the rotation speed calculator 111 corresponds to the motor controller 2 shown in FIG. 1 are assigned the same reference numerals as those in FIG. 1 for description.

Torque target value calculation unit 101 performs first torque target value calculation processing for calculating first torque target value T _m 1 ^* based on accelerator opening Apo and rotational speed detection value ω _m (or vehicle speed V). is executed. Note that the first torque target value calculation process will be described in detail with reference to step S202 in FIG.

The slope resistance estimator 102 calculates a slope resistance estimated value T _d 1 based on the road surface inclination. Specifically, the gradient resistance estimator 102 calculates the gradient resistance estimated value T _d 1 based on the detected value a obtained by the longitudinal acceleration sensor 11 and the motor rotation speed ω _m . The estimated slope resistance value T _d 1 is a value indicating the torque of the drive motor 4 required to keep the vehicle 10 stopped on the road surface on which the vehicle 10 exists. estimated based on A method for calculating the slope resistance estimated value T _d 1 will be described in detail with reference to FIG.

The stop control unit 103 executes stop control processing for stopping the vehicle 10 . Specifically, the stop control unit 103 calculates the gradient resistance estimated value T _d 1 calculated by the gradient resistance estimation unit 102, the rotation speed detection value ω _m output from the rotation speed calculator 111, the torque comparison unit 104 A second torque target value T _m 2 ^* is calculated based on the third torque target value T _m 3 ^* output from and is output to torque comparison section 104 . Note that the stop control unit 103 will be described in detail with reference to FIG.

The torque comparator 104 outputs a third torque target value T _m 3 ^* used for stop control processing for stopping the vehicle 10 . Specifically, the torque comparison unit 104 compares the first torque target value T _m 1 ^* calculated by the torque target value calculation unit 101 and the second torque target value T _m 2 calculated by the stop control unit 103 . ^* , and outputs the third torque target value T _m 3 ^* to the damping control unit 105 based on the comparison result. The stop control processing executed by the stop control section 103 and the torque comparison section 104 will be described in detail with reference to step S203 in FIG. Also, the torque comparison unit 104 will be described in detail with reference to FIG.

The vibration suppression control unit 105 performs vibration suppression control based on the third torque target value T _m 3 ^* output from the torque comparison unit 104 and the rotation speed detection value ω _m output from the rotation speed calculator 111. It executes the process. The damping control process will be described in detail with reference to step S204 in FIG. Also, the damping control unit 105 will be described in detail with reference to FIG.

The current-voltage converter 106 uses the torque command value T _m 6 ^* input to the drive motor 4, the rotation speed detection value ω _m of the drive motor 4, and the voltage detection value Vdc of the battery 1 input to the inverter 3 as indices. Calculation of dq-axis current command values id ^{*, iq* and dq-axis non-interference voltage command values Vd_dcpl*} _, ^Vq_dcpl _{* by} ^map _retrieval ⁽ maps are stored in memory in advance) , and each value is output to the current controller 107 .

The current controller 107 executes current control calculation based on each value output from the current-voltage converter 106 and the dq-axis current detection values i _d and i _q output from the coordinate converter 110, It calculates the dq-axis voltage command values V _d ^* and V _q ^* , and outputs the dq-axis voltage command values V _d ^* and V _q ^* to the coordinate converter 108 . Specifically, the current controller 107 performs low-pass filter processing on the dq-axis non-interference voltage command values V _d _dcpl ^* and V _q _dcpl ^* calculated by the current-voltage converter 106 to obtain V _d _dcpl_flt ^* and V _q _dcpl_flt. Ask for ^* . Then, the current controller 107 converts the _dq -axis current command values id ^{* and iq*, Vd_dcpl_flt*} _and ^Vq_dcpl_flt* _after ^low _- ^pass filtering, and the _dq -axis current detection values id and _iq into Based on this, the dq-axis voltage command values V _d ^* and V _q ^* are calculated.

The coordinate converter 108 inputs the dq-axis voltage command values V _d ^* and V _q ^* and the magnetic pole position detection value θ of the drive motor 4, and converts the voltage commands for each UVW phase by coordinate conversion processing according to the following equation (1). Values _Vu ^* , _Vv ^* , _Vw ^* are calculated and output.

PWM converter 109 generates drive signals D _uu ^* , D _ul ^* , D _vu ^* , D _vl ^* , D _wu for switching elements of inverter 3 according to voltage command values V _u ^* , V _v ^* , V _w ^* . ^* and D _wl ^* are generated and output to the inverter 3 .

The inverter 3 converts the DC voltage of the battery 1 into AC voltages _Vu ^* , _Vv ^* , Vw* according to the drive signal, and supplies the drive motor 4 with the AC voltages Vu*, Vv*, _Vw ^* .

The current sensor 7 detects currents of at least two phases out of the three phases (for example, i _u and _iv of the U phase and V phase) and inputs them to the coordinate converter 110 . In addition, when the current sensor is attached to only two phases, the current value of the remaining one phase that is not detected can in principle be obtained by Equation (2).
_iw = _-iu - _iv (2)

The coordinate converter 110 calculates dq-axis current detection values i _d and i _q according to the following equation (3).

A rotation sensor (magnetic pole position detector) 6 detects the magnetic pole position of the rotor of the drive motor 4 and outputs the detected value (magnetic pole position detection value θ). Note that the magnetic pole position detection value θ will also be referred to as the rotor phase θ.

The rotation speed calculator 111 receives the magnetic pole position detection value θ, calculates the rotation speed detection value ω _m , and outputs the calculated rotation speed detection value ω m .

By controlling the opening and closing of the switching elements of the inverter 3 with the PWM signal obtained in this way, the drive motor 4 can be driven with the desired torque indicated by the torque command value.

In this way, the motor controller 2 is an example of a control device that executes control of deceleration by the regenerative braking force of the drive motor 4 when the accelerator operation amount decreases or becomes zero. The motor controller 2 also includes motor torque command value calculation means for calculating a motor torque command value, disturbance torque estimation means for estimating disturbance acting on the vehicle 10, and angular velocity (motor rotation It is an example of means for detecting speed, wheel angular velocity, etc.). Also, the motor controller 2 is an example of angular velocity F/B torque calculation means for calculating the angular velocity F/B torque by multiplying the angular velocity by a predetermined gain. In addition, the motor controller 2 determines when the vehicle is about to stop by the motor torque command value calculating means, adjusts the braking/driving force applied to the vehicle 10 by the angular velocity F/B torque calculating means, and adjusts the disturbance torque estimated value determined by the disturbance torque estimating means. It is an example of stop control means for convergence.

[Motor controller operation example]
Various processes related to the electric vehicle control method according to the present embodiment will be described below. Various processes described below are executed by the motor controller 2 according to a program stored in a storage area (such as a ROM).

FIG. 3 is a flow chart showing an example of a vehicle control process performed by the motor controller 2. As shown in FIG. It should be noted that each of the following processes is repeatedly executed at a predetermined calculation cycle.

FIG. 4 is a diagram showing an example of an accelerator opening-torque table used when obtaining a target value of motor torque. This accelerator opening-torque table will be described with reference to the process of step S202.

In step S201, the motor controller 2 performs input processing for acquiring various parameters (various signals necessary for control calculation) used for executing the processing after step S202.

Specifically, the motor controller 2 communicates with various sensors or an arbitrary controller different from the motor controller 2 (for example, a higher-level vehicle control controller) to detect the accelerator opening Apo (%), the rotor phase θ [ rad], three-phase current detection values ( _{iu_d} , _{iv_d} , _{iw_d} ) [A], the detection value a by the longitudinal acceleration sensor 11, and the DC voltage value Vdc [V] of the battery 1 are acquired.

The accelerator opening Apo is acquired as a detected value of an accelerator opening sensor, or through communication with an arbitrary controller different from the motor controller 2 (for example, a superior vehicle control controller). Also, the rotor phase θ is obtained, for example, as a detected value of a rotation sensor such as a resolver or an encoder, or communicated with an arbitrary controller different from the motor controller 2 (for example, a superior vehicle controller). Obtained by Further, the DC voltage value Vdc is obtained, for example, by a detected value of a voltage sensor provided on the DC power supply line of the battery 1, or by communication with an arbitrary controller other than the motor controller 2 (for example, a battery controller). . Further, the detected value a is obtained, for example, as a detected value of the longitudinal acceleration sensor 11, or obtained through communication with an arbitrary controller different from the motor controller 2 (for example, a superior vehicle controller). . Also, the three-phase current detection values (i _u _d, _iv _d, i _w _d) are obtained as detection values of current sensors (not shown), or are obtained from any other controller different from the motor controller 2 (for example, obtained through communication with a superior vehicle control controller). Since the sum of the three-phase current values is 0, for example, i _w is calculated based on the values of i _u and _iv using the above equation (2) without inputting from the current sensor. You can also ask for

Next, based on the acquired parameters, the motor controller 2 determines the electrical angular velocity ω _e [rad/s] of the drive motor 4, the motor rotation speed ω _m [rad/s], the DC voltage value Vdc [V], Also, the vehicle speed V [km/h] is calculated as in (i) to (iii) below.

(i) Electrical angular velocity ω _e (electrical angle)
It is calculated by time-differentiating the rotor phase θ (electrical angle).

(ii) Motor rotation speed ω _m [rpm]
After obtaining the motor rotation speed ω _m [rad/s], which is the mechanical angular speed of the drive motor 4, by dividing the electric angular speed ω _e by the pole logarithm of the drive motor 4, is obtained by multiplying by a unit conversion factor (60/2π).

(iii) Vehicle speed V [km/h]
The motor rotation speed ω _m is multiplied by the tire dynamic radius R, and the value obtained by this multiplication is multiplied by the gear ratio (input rotation speed/output rotation speed) of the speed reducer 5 to calculate the vehicle speed v [m/s]. . Further, the vehicle speed V [km/h] is obtained by multiplying the calculated vehicle speed v [m/s] by a unit conversion factor (3600/1000). It should be noted that the information may be acquired through communication with any controller other than the motor controller 2 (for example, a meter controller or a brake controller).

Note that the vehicle speed V and the motor rotation speed ω _m can be regarded as control parameters (speed parameters) that are substantially equivalent to each other except for the reduction ratio in the power transmission path between the drive motor 4 and the drive wheels 9 . Therefore, from the viewpoint of simplifying the explanation, the following processing will focus on an example in which the motor rotation speed ω _m is used as the speed parameter. On the other hand, the following description can be similarly applied to the case where the vehicle speed V is used as the speed parameter by taking into consideration the above-described difference in speed reduction ratio.

Next, in step S202, the motor controller 2 (the torque target value calculator 101 shown in FIG. 2) executes a first torque target value calculation process. Specifically, the torque target value calculation unit 101 refers to an accelerator opening-torque table _exemplified in FIG. , a first torque target value _Tm1 ^* as a basic torque target value is calculated. That is, the first torque target value T _m1 ^* is a basic target value of the motor torque T that is determined from the required driving force according to the driver's operation or the command of the automatic driving controller while the vehicle 10 is running.

In step S203, the motor controller 2 (stop control unit 103 and torque comparison unit 104 shown in FIG. 2) executes stop control processing. Specifically, the motor controller 2 determines whether the vehicle 10 is about to stop. It should be noted that "just before stopping" means a period during which the vehicle 10 stops based on the amount of accelerator operation. For example, it is possible to determine that the vehicle 10 is about to stop when the vehicle speed becomes equal to or less than a predetermined value during the period when the vehicle 10 is stopped based on the accelerator operation amount. Further, for example, the torque comparison unit 104 can determine that the vehicle is about to stop when the first target torque value _Tm1 ^* becomes equal to or less than the second target torque value _Tm2 ^* . Note that, of the period after it is determined that the vehicle 10 is about to stop, the period from the relatively high vehicle speed range until it is determined that the vehicle 10 has stopped is referred to as a first period. Further, a period during which the vehicle 10 is maintained in a stopped state after it is determined that the vehicle 10 is about to stop is referred to as a second period. It should be noted that the first period may be a period from a relatively high vehicle speed range to a relatively low vehicle speed range within the period after it is determined that the vehicle is about to stop. In this case, the period from the relatively low vehicle speed range to the time after the vehicle 10 has stopped is defined as the second period.

Then, before it is determined that the vehicle is about to stop, the motor controller 2 sets the first torque target value _Tm1 ^* calculated in step S202 as the third torque target value _Tm3 ^* . In addition, after it is determined that the vehicle is about to stop, the motor controller 2 performs a second calculation that converges to the disturbance torque estimated value _Td obtained by the disturbance torque estimator 400 (see FIG. 7) as the rotation speed of the drive motor 4 decreases. The torque target value _Tm2 ^* is set to the third torque target value _Tm3 ^* . At a predetermined timing after it is determined that the vehicle is about to stop, the motor controller 2 sets the gradient resistance estimated value T _d 1 instead of the second torque target value T _m 2 ^* that converges to the disturbance torque estimated value T _d . A second torque target value T _m 2 ^* that converges to the stop maintaining torque T _d 2 obtained based on this is set as a third torque target value T _m 3 ^* . As a result, it is possible to maintain the stopped state of the vehicle irrespective of the gradient with an appropriate motor torque. The stop control process will be described in detail with reference to FIGS. 7 to 11. FIG.

In step S204, the motor controller 2 (the damping control section 105 shown in FIG. 2) executes damping control processing. Specifically, the motor controller 2 inputs the third torque target value T _m 3 ^* calculated in step S203 and the motor rotation speed ω _m . A sixth torque target value _Tm6 ^* for suppressing torque transmission system vibration (torsional vibration of the drive shaft, etc.) is calculated. The damping control process will be described in detail with reference to FIGS. 12 and 13. FIG.

In step S205, the motor controller 2 (current-voltage converter 106 shown in FIG. 2) executes current-voltage command value calculation processing. Specifically, based on the motor rotation speed _ωm and the DC voltage value Vdc obtained in step S201, and the sixth torque target value _Tm6 ^* calculated in step S204, the motor controller 2 preliminarily The dq-axis current command values id ^{*, iq* and the dq-axis non-interference voltage command values Vd_dcpl*} _, ^Vq_dcpl _{* are} ^calculated _with ^reference to a table stored in an internal memory or the like.

In step S206, the motor controller 2 executes drive motor control processing. Specifically, the motor controller 2 executes each process after the process of the current controller 107 shown in FIG. 2 to control the drive motor 4 .

Next, the details of the stop control process in step S203 will be described.

[Vehicle state control]
First, each transmission characteristic in the driving force transmission system of the vehicle 10 used in the stop control process in this embodiment will be described.

1. Vehicle response Gr (s)
First, the setting of the vehicle response G _r (s) based on a vehicle model that models the driving force transmission system of the vehicle 10 will be described. It should be noted that the motor controller 2 uses the vehicle response G _r (s) determined according to the calculation algorithm described below as necessary for various processes related to the stop control process, such as calculation of the disturbance torque estimated value T _d described later. Apply.

FIG. 5 is a diagram modeling the driving force transmission system of the vehicle 10. As shown in FIG. Each parameter in FIG. 5 is as follows.
J _m : Inertia of drive motor 4 J _w : Inertia of drive wheel 9 M : Weight of vehicle 10 K _d : Torsional rigidity of drive train K _t : Coefficient of friction between tire and road surface N: Overall gear ratio r: Tire load Radius ω _m : Rotation speed of drive motor 4 T _m : Motor torque (torque command value T _m ^** )
T _d : Torque of drive wheel 9 F: Force applied to vehicle 10 V: Velocity of vehicle 10 (vehicle speed)
ω _w : Angular velocity of drive wheel 9

From FIG. 5, the equations of motion of the vehicle 10 are represented by the following equations (4) to (8).

Then, the transmission characteristic G _p (s) from the torque command value T _m ^** to the motor rotation speed ω _m is expressed by the following equation (9) obtained by transforming the above equations (4) to (8) while performing the Laplace transform. be done.

However, each parameter in Expression (9) is defined as in Expression (10) below.

Here, when examining the poles and zeros of the transfer function shown in Equation (9), it can be approximated to the transfer function of Equation (11) below, and one pole and one zero show extremely close values. This corresponds to the very close values of α and β in the following equation (11).

Therefore, by performing pole-zero cancellation (approximating α=β) in Equation (11), the (secondary)/(third-order) transfer characteristic G _p (s) configure.

Further, G _p (s) can be regarded as G _r (s) shown in the following equation (13) from the vehicle model G _p (s) and the damping control algorithm.

Next, the transmission characteristic G _pv (s) from the motor torque T _m to the vehicle speed V will be explained.

If the transfer characteristic G _pv (s) is obtained based on the equations of motion (4) to (8) described above, the following equation (14) is obtained.

Further, when the transfer characteristic Gω _v (s) from the motor rotation speed ω _m to the vehicle speed V is obtained based on the equations of motion (11) and (14), the following equation (15) is obtained.

Next, the transmission characteristic G _pF (s) from the motor torque T _m to the driving force F will be explained.

Obtaining the transfer characteristic G _pF (s) based on the equations of motion (4) to (8) yields the following equation (16).

[Operation example of stop control processing]
Next, the stop control process (S203) shown in FIG. 3 will be described in detail with reference to FIGS. 6 to 11. FIG.

[Calculation example of slope resistance estimate]
FIG. 6 is a diagram showing an example of a calculation method for calculating the slope resistance estimated value used in the stop control process. This gradient resistance estimation value calculation processing is executed by the gradient resistance estimation unit 102 shown in FIG.

FIG. 6 shows a simplified state in which the vehicle 10 is stopped on an uphill road with a gradient angle of α. Here, the slope angle α can be estimated based on the detected value a (longitudinal acceleration signal) by the longitudinal acceleration sensor 11 . That is, the inclination of the vehicle 10 obtained based on the detected value a by the longitudinal acceleration sensor 11 can be used as the inclination angle α. The load radius r of the tire and the force F applied to the vehicle 10 are the parameters described above.

As shown in FIG. 6, when the vehicle 10 is stopped on an uphill road with a gradient angle α, the following formula (17) is used to calculate the driving force _Fd that prevents the vehicle 10 from falling backward. can be done. Note that the driving force _Fd is a driving force corresponding to a slope, and can also be called a driving force balanced with a slope resistance. Also, g is the gravitational acceleration (=9.8 m/s ² ).
F _d =M·g·sinα (17)

Next, the driving torque T _d 1 is calculated by adding the tire load radius r and the overall gear ratio N. Specifically, the driving torque T _d 1 can be calculated using the following equation (18). Note that, in the present embodiment, the drive torque T _d 1 is referred to as the slope resistance estimated value T _d 1 .
_Td1 = _Fd.N.r (18)

Also, the gradient resistance estimated value T _d 1 can be expressed as in the following equation (19) using the above equations (17) and (18).
T _d 1=M·g·sinα·N·r (19)

Thus, the slope angle α can be obtained based on the detected value a by the longitudinal acceleration sensor 11, and the slope resistance estimated value T _d 1 can be calculated based on the slope angle α. That is, the road surface inclination can be detected using the longitudinal acceleration signal of the vehicle 10 when the vehicle is stopped, and the slope resistance estimated value T _d 1 required to keep the vehicle stopped on the road surface inclination can be accurately calculated.

[Example of stop control processing]
FIG. 7 is a block diagram showing a functional configuration example of the motor controller 2. As shown in FIG. The example shown in FIG. 7 shows an example of the functional configuration when executing the stop control process. FIG. 8 is a block diagram showing a functional configuration example of the vehicle speed F/B torque setting section 300 shown in FIG. FIG. 9 is a block diagram showing a functional configuration example of the disturbance torque estimator 400 shown in FIG. FIG. 10 is a block diagram showing a functional configuration example of the stop maintaining torque switching section 500 shown in FIG. FIG. 11 is a diagram showing a map used when the stop maintaining torque switching section 500 shown in FIG. 10 calculates the stop maintaining torque.

As shown in FIG. 7 , the motor controller 2 includes a gradient resistance estimating section 102, a torque comparing section 104, a vehicle speed F/B torque setting section 300, a disturbance torque estimating section 400, and a stop maintaining torque switching section 500. , and a computing unit 600 . The gradient resistance estimating section 102 and the torque comparing section 104 correspond to the sections with the same names shown in FIG. Vehicle speed F/B torque setting section 300, disturbance torque estimating section 400, stop maintaining torque switching section 500, and computing section 600 correspond to stop control section 103 shown in FIG.

A vehicle speed F/B torque setting unit 300 calculates a vehicle speed F/B torque Tω based on the motor rotation speed ω _m . Vehicle speed F/B torque setting section 300 will be described with reference to FIG.

As shown in FIG. 8 , vehicle speed F/B torque setting section 300 includes estimated vehicle speed calculation section 301 and vehicle speed F/B torque calculation section 302 .

Estimated vehicle speed calculation unit 301 calculates estimated vehicle speed VA based on motor rotation speed _ωm , taking into consideration _Gωv of the above-described equation (15). It should be noted that an approximated transfer characteristic may be used for Gω _v in the above equation (15). For example, Gω _v ' shown in the following equation (20) can be used as an approximate transfer characteristic.

A vehicle speed F/B torque calculator 302 multiplies the estimated vehicle speed VA by a gain K _vref to calculate a vehicle speed F/B torque Tω. However, K _vref <0. In this example, the estimated vehicle speed VA is multiplied by a predetermined gain to calculate the vehicle speed F/B torque Tω. The speed F/B torque Tω may be calculated.

Returning to FIG. 7, the disturbance torque estimator 400 calculates the disturbance torque estimated value _Td based on the motor rotation speed _ωm and the third torque target value _Tm3 ^* . The disturbance torque estimator 400 will be described with reference to FIG.

As shown in FIG. 9 , disturbance torque estimator 400 includes first motor torque estimated value calculator 401 , second motor torque estimated value calculator 402 , and calculator 403 .

A first motor torque estimation value calculation unit 401 uses H ₁ (s)/G _r (s) to filter the motor rotation speed ω _m to calculate a first motor torque estimation value. Here, H ₁ (s) is a low-pass filter equal to or greater than the difference between the denominator and numerator orders of the vehicle response G _r (s) derived from the damping control algorithm and the vehicle model G _p (s).

A second motor torque estimated value calculation 402 uses a low-pass filter H ₁ (s) to filter the motor torque command value T _m 3 ^* to calculate a second motor torque estimated value.

The calculation unit 403 calculates the deviation between the first motor torque estimation value and the second motor torque estimation value, and sets the deviation as the disturbance torque estimation value _Td .

Here, the disturbances targeted in this embodiment include air resistance, modeling errors due to changes in vehicle mass (number of passengers, load capacity), rolling resistance of tires, slope resistance, etc. The disturbance factor that becomes is the gradient resistance. The _disturbance ^factor varies depending on the operating conditions, but in the disturbance torque _estimation unit ₄₀₀ , the vehicle response G Since the disturbance torque estimated value _Td is calculated based on _r (s), these disturbance factors can be collectively estimated. As a result, smooth deceleration and smooth stopping of the vehicle can be realized under any driving conditions.

Returning to FIG. 7, the stop-maintaining torque switching unit 500 operates based on the disturbance torque estimated value T _d calculated by the disturbance torque estimating unit 400 and the gradient resistance estimated value T _d 1 calculated by the gradient resistance estimating unit 102. , the target value (disturbance torque estimated value T _d or stop maintaining torque T _d 2) of the drive motor 4 used for stop control is output. The stop maintaining torque switching unit 500 will be described with reference to FIGS. 10 and 11. FIG.

As shown in FIG. 10 , the stop maintaining torque switching section 500 includes a stop maintaining torque calculating section 501 and a switching section 502 .

The stop maintaining torque calculator 501 calculates the stop maintaining torque _Td2 based on the disturbance torque estimated value _Td and the grade resistance estimated value _Td1 . A calculation example of the stop maintaining torque T _d 2 will be described in detail with reference to FIG. 11 .

FIG. 11 shows a MAP in which the horizontal axis indicates the estimated gradient resistance value T _d 1 and the vertical axis indicates the estimated disturbance torque value T _d . On the horizontal axis shown in FIG. 11 , an example is shown in which the angle of the gradient of the uphill road on which the vehicle 10 exists increases toward the right side, and the angle of the gradient of the downhill road on which the vehicle 10 exists increases toward the left side. . It should be noted that when the horizontal axis shown in FIG. 11 is 0 [Nm], it is assumed that the vehicle 10 exists on a flat road with no slope.

A straight line L11 indicates the case where gradient resistance estimated value T _d 1=disturbance torque estimated value T _d . For example, under an ideal condition where the running resistance is 0, gradient resistance estimated value T _d 1=disturbance torque estimated value T _d . However, in reality, the gradient resistance estimated value T _d 1 ≠ the disturbance torque estimated value T _d due to the running resistance of the road surface. On a road surface with high running resistance, such as a sandy or deep snow road surface, the difference between the estimated gradient resistance value T _d 1 and the estimated disturbance torque value T _d increases.

The running resistance can be obtained from the absolute value of the difference between the disturbance torque estimated value _Td and the gradient resistance estimated value _Td1 . Specifically, it can be obtained by the following equation (21).
Running resistance RR1= |disturbance torque estimated value T _d -gradient resistance estimated value T _d 1| (21)

Further, the section IN1 is a range indicating a gradient that allows the vehicle 10 to be kept stopped even with a motor torque of 0 [Nm]. In other words, the section IN1 is a range in which the vehicle 10 can be kept stopped when the motor torque command value is 0 [Nm]. Also, the range of the section IN1 is set based on the magnitude of the running resistance RR1. Further, a range including positive and negative values is set as the section IN1 with the slope resistance estimated value T _d 1=0 as a reference. For example, the interval IN1 can be twice the running resistance RR1. That is, the stop maintaining torque T _d 2 is set to 0 when the absolute value of the slope resistance estimated value T _d 1 is smaller than the running resistance RR1.

Note that FIG. 11 shows an example in which the positive range and the negative range are the same when the gradient resistance estimated value T _d 1=0 is used as a reference, but different ranges are set for the positive range and the negative range. may Also, the interval IN1 can be appropriately set using various experimental data.

For example, when the road surface with a gentle slope is sandy or deep snow, the running resistance RR1 is assumed to be large, but the slope resistance is small. For example, when the vehicle 10 stops moving forward on such an uphill road with a gentle gradient, the gradient resistance estimated value T _d 1<disturbance torque estimated value T _d is established. On the other hand, when the vehicle 10 is reversed and stopped on such a gentle uphill road, the gradient resistance estimated value _{Td1>the disturbance torque estimated value Td .} In these cases, the running resistance RR1 is compared with the slope resistance estimated value T _d 1, and when the slope resistance estimated value T _d 1 is small, the vehicle can be stopped even if the stop maintaining torque T _d 2 is set to 0. . That is, on a gentle gradient road surface with a large running resistance RR1, when the gradient resistance is small, even if the stop maintaining torque _Td2 is set to 0, the vehicle can continue to be stopped.

Therefore, as indicated by the solid line L1, the stop maintaining torque _Td2 is set to 0 when the slope resistance estimated value _Td1 is within the range of the interval IN1. That is, when the estimated slope resistance value T _d 1 is approximately 0 (in other words, when the road surface inclination of the vehicle 10 is approximately 0), the stop maintaining torque T _d 2 is set to 0, and the motor torque command value is set to 0 [Nm ]. Thus, when the gradient resistance estimated value T _d 1 is approximately 0, stop control for convergence to the disturbance torque estimated value T _d is stopped, and the motor torque command value is set to 0 [Nm] (that is, the motor torque is set to 0 converge) and continue the stop. As a result, continuation of unnecessary torque input to the drive motor 4 can be suppressed.

Further, FIG. 11 shows a setting example of the stop maintaining torque T _d 2 when the running resistance RR1 is a predetermined value. Broken lines L2 and L3 are straight lines parallel to straight line L11, and indicate straight lines in which the distance between broken lines L2 and L3 on the horizontal axis is the same as section IN1.

A thick solid line L1 indicates the stop maintaining torque T _d 2 output by the stop maintaining torque calculation unit 501 . In FIG. 11, for ease of explanation, the value of the stop maintaining torque T _d 2 is the value on the vertical axis.

Further, as indicated by the solid line L1, when the estimated slope resistance value T _d 1 is outside the range of the section IN1, the stop maintaining torque T _d 2 is set according to the magnitude of the estimated slope resistance value T _d 1. . That is, on a road surface with a certain grade or more (that is, a road surface in which the absolute value of the estimated slope resistance value T _d 1 is greater than the running resistance RR1), if the stop maintaining torque T _d 2 is set to 0, the vehicle 10 may slide down. There is

Therefore, in the example shown in FIG. 11, when the slope resistance estimated value T _d 1 is outside the range of the interval IN1 and is a negative value, a value along the dashed line L2 is set as the stop maintaining torque T _d 2. do. Further, when the slope resistance estimated value T _d 1 is outside the range of the section IN1 and is a positive value, a value along the dashed line L3 is set as the stop maintaining torque T _d 2 .

Here, running resistance such as sand or deep snow is added to the slope resistance on the forward side of the uphill road, and is subtracted from the slope resistance on the backward side of the uphill road. Therefore, if the torque of the drive motor 4 for keeping the vehicle 10 stopped on the slope is set to a motor torque command value within a range obtained by adding/subtracting the running resistance to the slope resistance, the vehicle 10 can be kept stopped. be able to. Therefore, when the slope resistance estimated value T _d 1 is outside the range of section IN1, the stop maintaining torque T _d 2 can be calculated using the following equations (22) and (23).
Uphill road stopping torque T _d 2 = Estimated grade resistance value T _d 1 - Running resistance RR1 (22)
Downhill stop maintaining torque T _d 2 = Estimated grade resistance value T _{d 1} + Running resistance RR1 (23)

In this manner, on an uphill road or a downhill road, the stop maintaining torque T _d 2 obtained by calculating the gradient resistance estimated value T _d 1 and the running resistance RR1 is set as the motor torque command value. As a result, it is possible to maintain the stopped state with as small a motor torque as possible, and it is possible to make a maximum contribution to the heat generation of the drive motor 4 and the improvement of the electricity consumption.

In addition, instead of executing the calculations of formulas (22) and (23), a plurality of maps (maps shown in FIG. 11) corresponding to the running resistance RR1 are prepared in advance, and the maps corresponding to the running resistance RR1 are used. The stop maintaining torque T _d 2 may be obtained.

Similarly, the stop maintaining torque T _d 2 when the vehicle 10 is stopped on a steep road surface can be calculated using equations (22) and (23 ₎ .

In this way, the stop maintaining torque T _d 2 can be set as the minimum motor torque command value capable of maintaining the stop on the slope, which is obtained based on the slope resistance estimated value T _d 1 and the running resistance RR1. In other words, the stop maintaining torque T _d 2 can be set as a predetermined torque required to balance with the road gradient, which is obtained based on the measured or estimated road gradient. That is, the stop-maintaining torque T _d 2 is a value that optimizes electricity consumption, allows the vehicle to continue to stop on a slope, and minimizes the motor torque.

In the above description, FIG. 11 is used to obtain the stop maintaining torque T _d 2, and equations (22) and (23) are used to obtain the stop maintaining torque T _d 2. Here, since the estimated slope resistance value T _d 1 is the torque of the drive motor 4 required to keep the vehicle 10 stopped on the road, the torque of the drive motor 4 and the estimated slope resistance value T _d 1 will be balanced with the road slope. Therefore, the stop maintaining torque T _d 2 may be used as the slope resistance estimated value T _d 1 . Thus, by converging the torque of the drive motor 4 to the estimated slope resistance value T _d 1 that balances with the road surface inclination, the torque that balances with the road surface inclination can be appropriately set.

Thus, by stopping the stop control for convergence to the disturbance torque estimated value _Td based on the gradient resistance estimated value _Td1 corresponding to the road surface inclination and setting the stop maintaining torque _Td2 , It is possible to prevent the continuation of unnecessary torque input to the drive motor 4 when the vehicle is stopped on a road surface with high running resistance, such as sandy ground. For example, when performing stop control on sandy ground, heat generation of the drive motor 4 and deterioration of electricity consumption can be suppressed.

Next, the switching unit 502 in FIG. 10 will be described. The switching unit 502 switches between the disturbance torque estimated value _Td and the stop maintaining torque _Td2 based on the motor rotation speed ωm _. Specifically, in the stop control process, when the vehicle 10 is decelerating (that is, when ω _m ≠0 [rpm]), the switching unit 502 outputs the disturbance torque estimated value T _d . Further, after the vehicle 10 stops (that is, ω _m =0 [rpm]), the switching unit 502 outputs the stop maintaining torque T _d 2. Thus, the switching unit 502 switches to the stop maintaining torque T _d 2 after determining that the vehicle 10 is stopped.

In the present embodiment, an example is shown in which the reference for switching from the disturbance torque estimated value T _d to the stop maintaining torque T _d 2 is set after the stop determination of the vehicle 10 (that is, ω _m =0 [rpm]). However, other criteria may be used. For example, on the condition that the motor rotation speed ω _m becomes equal to or less than a predetermined rotation speed (that is, TH1≧ω _m >0 [rpm]) just before the vehicle stops, the disturbance torque estimated value T _d is changed to the stop maintaining torque T _d 2. You may make it switch. Note that the threshold TH1 is a value corresponding to a relatively low vehicle speed range just before the vehicle stops, and can be appropriately set using various experimental data.

In the above, after the vehicle 10 stops (that is, ω _m =0 [rpm]) or when the motor rotation speed ω _m becomes equal to or lower than a predetermined number of rotations (that is, ω _m >0 [rpm]), the disturbance torque An example of switching from the estimated value T _d to the stop maintaining torque T _d 2 has been shown. However, the control using the stop maintaining torque T _d 2 may be executed only when the running resistance of the road surface on which the vehicle 10 exists satisfies a predetermined condition. For example, only when the running resistance RR1 is equal to or greater than the threshold (that is, when the difference between the estimated disturbance torque _Td and the estimated gradient resistance _Td1 is equal to or greater than the threshold), the estimated disturbance torque _Td is converted to the stop maintaining torque. Alternatively, switching to T _d 2 may be performed and control using the stop maintaining torque T _d 2 may be performed. The threshold value shown here can be appropriately set using various experimental data and the like.

Returning to FIG. 7, the calculation unit 600 calculates the motor rotation speed F/B torque Tω calculated by the vehicle speed F/B torque setting unit 300 and the value calculated by the stop maintaining torque switching unit 500 (disturbance torque estimated value T _d or the deviation from the stop maintaining torque T _d 2) is calculated to calculate the second torque target value T _m 2 ^* .

Based on the result of comparison between the first torque target value _Tm1 ^* and the second torque target value _Tm2 ^* calculated in the calculation process (step S202) shown in FIG. Switch the third torque target value T _m 3 ^* . Specifically, when the first torque target value _Tm1 ^* is greater than the second torque target value _Tm2 *, the torque comparison unit 104 outputs the third torque target value _Tm3 ^{* .} , the first torque target value T _m 1 ^* is output. On the other hand, the torque comparison unit 104 determines that the vehicle is about to stop when the first torque target value _Tm1 ^* is equal to or less than the second torque target value _Tm2 ^* , and sets the third torque target value _Tm3 ^* . , from the first desired torque value _Tm1 ^* to the second desired torque value _Tm2 ^* . Thereby, stop control is executed.

By performing the above processing, it is possible to smoothly stop the vehicle regardless of the gradient and maintain the stopped state with an appropriate motor torque only by the motor torque.

[Example of damping control processing]
Next, the damping control process (step S204) shown in FIG. 3 will be described in detail with reference to FIGS. 12 and 13. FIG.

FIG. 12 is a block diagram showing a functional configuration example of the motor controller 2. As shown in FIG. FIG. 12 shows an example of a functional configuration related to damping control processing. Each unit shown in FIG. 12 corresponds to the damping control unit 105 shown in FIG. FIG. 13 is a diagram showing H ₂ (s) frequency characteristics.

The motor controller 2 includes an F/F compensator 701 , feedback compensators 702 to 704 , and computing units 705 and 706 .

The F/F compensator 701 inputs the third torque target value T _m 3 ^* , and uses the transfer function G _r (s)/G _p (s) to obtain the fourth torque target value T _m 4 ^* calculate.

The calculator 705 adds the fourth target torque value _Tm4 ^* and the fifth target torque value _Tm5 ^* to obtain the sixth target torque value _Tm6 ^* .

The feedback compensator 702 inputs the sixth torque target value T _m 6 ^* and uses the vehicle model G _p (s) to calculate the estimated motor rotation speed.

A calculator 706 obtains a difference value between the estimated motor rotation speed and the actual motor rotation speed ω _m .

A feedback compensator 703 inputs the difference value between the motor rotation speed estimated value and the actual motor rotation speed ω _m and calculates the estimated disturbance d using the transfer function H ₂ (s)/G _p (s). The transfer function H ₂ (s) is set such that the difference between the denominator order and the numerator order is greater than or equal to the difference between the denominator order and the numerator order of the transfer function G _p (s).

The feedback compensator 704 multiplies the estimated disturbance d by the feedback gain _KFB to calculate the fifth torque target value _Tm5 ^* .

Next, the transfer function H ₂ (s) will be described with reference to FIG.

The transfer function H ₂ (s) becomes a feedback element that reduces only vibration when used as a bandpass filter. At this time, the greatest effect can be obtained by setting the filter characteristics as shown in FIG. That is, the transfer function H ₂ (s) has substantially the same attenuation characteristics on the low-pass side and the high-pass side, and the torsional resonance frequency of the drive system is near the center of the passband on the logarithmic axis (log scale). is set to be

For example, when H ₂ (s) is composed of a first-order high-pass filter and a first-order low-pass _filter , the following equation (24 ).

In this way, the motor controller 2 calculates the motor torque command value to which the damping control is applied to suppress the torsional vibration of the driving force transmission system of the vehicle 10 based on the motor torque command value, and performs the damping control. The driving motor 4 is controlled based on the motor torque command value. In this case, when the accelerator operation amount decreases or becomes zero and the vehicle 10 is about to stop (a section in which stop control processing for stopping the vehicle 10 is enabled), the motor controller 2 reduces the rotational speed of the drive shaft to The motor torque is adjusted along with the decrease in the correlated angular velocity, and is converged to the disturbance torque estimated value which is roughly the slope resistance. As a result, when the electric vehicle is stopped by the regenerative braking force, it is possible to suppress the occurrence of vibration in the longitudinal direction of the vehicle body. In addition, it is possible to always achieve smooth deceleration without acceleration vibrations just before the vehicle stops, regardless of whether the vehicle is on a flat road, an uphill road, or a downhill road, and the vehicle can be kept in a stopped state.

In the present embodiment, the vehicle in which torsional vibration occurs in the driving force transmission system has been described, so damping control is also used. is. In this case, there is no need to perform the damping control process (step S204) shown in FIG.

[Example of stop control processing on a flat road]
FIG. 14 is a time chart when the stop control process is executed on a flat road. FIG. 14 shows an example in which the stop control process is executed on a flat road such as a sandy road with high running resistance. Also, FIG. 14 shows an example in which it is determined that the vehicle is about to stop at time t1, and the stop control process is started. Further, FIG. 14 shows an example in which the motor rotation speed asymptotically converges to zero in the stop control process from time t1 when the stop control process is started to time t2.

In the solid lines L21 and L31, in the stop control process, the stop control for converging to the disturbance torque estimated value T _d is stopped after the stop of the vehicle 10 is determined at the timing of time t2, and the stop maintaining torque T _d 2 is used. 4 shows a time chart when executing stop control;

Broken lines L22 and L32 show a comparative example in which stop control is performed using the disturbance torque estimated value _Td even after it is determined that the vehicle 10 has stopped at time t2 in the stop control process.

In the dashed line L22, which is a comparative example, the value of the running resistance is large due to sandy ground, etc., so the disturbance torque estimated value _Td is set assuming that the road is an uphill road. Further, as indicated by the dashed line L22, even after the vehicle 10 is determined to be stopped, the state in which the disturbance torque estimated value _Td is set when the vehicle 10 is stopped is maintained. Therefore, as indicated by broken line L32, even after the vehicle 10 is determined to be stopped, the motor torque command value maintains a positive value even if the road is flat. Therefore, in the comparative example, an unnecessary motor torque command value is continuously input, which causes heat generation of the drive motor 4 and deterioration of electricity consumption.

On the other hand, in the present embodiment, as indicated by the solid line L21, after the vehicle 10 is determined to be stopped, using the slope resistance estimated value T _d 1 calculated based on the detected value a by the longitudinal acceleration sensor 11, A switch to the stop maintaining torque T _d 2 is executed. Therefore, as indicated by the solid line L31, after the vehicle 10 is determined to be stopped, the road is flat, so the stopped state can be maintained with the motor torque command value set to 0 [Nm]. As described above, in the present embodiment, since an unnecessary motor torque command value is not input, heat generation of the drive motor 4 can be suppressed, and the power consumption performance can be improved.

[Example of stop control processing on an uphill road]
FIG. 15 is a time chart when the stop control process is executed on an uphill road. FIG. 15 shows an example in which the stop control process is executed on an uphill road such as a sandy road with high running resistance. Also, FIG. 15 shows an example in which it is determined that the vehicle is about to stop at time t11, and the stop control process is started. Further, FIG. 15 shows an example in which the motor rotation speed asymptotically converges to zero in the stop control process from time t11 when the stop control process is started to time t12.

In the solid lines L41 and L51, in the stop control process, the stop control for converging to the disturbance torque estimated value T _d is stopped after the stop of the vehicle 10 is determined at the timing of time t12, and the stop maintaining torque T _d 2 is used. 4 shows a time chart when executing stop control;

Broken lines L42 and L52 show a comparative example in which stop control is performed using the disturbance torque estimated value _Td even after it is determined that the vehicle 10 has stopped at time t12 in the stop control process.

In the dashed line L42, which is a comparative example, the value of running resistance is large due to sand, etc., so the disturbance torque estimated value _Td is set assuming that the road tends to be steeper than the actual road surface. Further, as indicated by the dashed line L42, even after the vehicle 10 is determined to be stopped, the state in which the disturbance torque estimated value _Td is set when the vehicle 10 is stopped is maintained. Therefore, as indicated by the dashed line L52, even after the vehicle 10 is determined to be stopped, the same motor torque command value (positive value) as the value at the time of the stop determination is maintained. Therefore, in the comparative example, an unnecessary motor torque command value is continuously input, which causes heat generation of the drive motor 4 and deterioration of electricity consumption.

On the other hand, in the present embodiment, as indicated by the solid line L41, after the vehicle 10 is determined to be stopped, the gradient resistance estimated value T _d 1 calculated based on the detected value a by the longitudinal acceleration sensor 11 is used to A switch to the stop maintaining torque T _d 2 is executed. Therefore, as indicated by the solid line L51, after the vehicle 10 is determined to be stopped, the motor torque command value can be set so as to provide an appropriate positive torque that balances with the gradient disturbance, and the stopped state can be maintained. As described above, in the present embodiment, since an unnecessary motor torque command value is not input, heat generation of the drive motor 4 can be suppressed, and the power consumption performance can be improved.

In this way, by applying this embodiment, it is possible to appropriately set the torque for keeping the vehicle stopped on a sandy road surface with increased running resistance, thereby suppressing motor heat generation and improving electricity consumption.

[Configuration example of 4WD electric vehicle]
Although the 2WD vehicle 10 has been described above, the present embodiment can also be applied to an electric vehicle having a plurality of drive motors, such as a 4WD electric vehicle, and has the same effects as the present embodiment. Therefore, an example of a 4WD electric vehicle to which the present embodiment can be applied is shown below.

FIG. 16 is a diagram showing a configuration example of a 4WD electric vehicle 800. As shown in FIG. 4WD electric vehicle 800 mainly includes battery 801 , motor controller 802 , longitudinal acceleration sensor 803 , front drive system 810 and rear drive system 820 . The front drive system 810 includes a front inverter 813, a front drive motor 814, a front reduction gear 815, various sensors (rotation sensor 816 and current sensor 817), a front drive shaft 818, front drive wheels 819L, 819R. The rear drive system 820 includes a rear inverter 823, a rear drive motor 824, a rear reduction gear 825, various sensors (rotation sensor 826 and current sensor 827), a rear drive shaft 828, rear drive wheels 829L, 829R. It should be noted that these units correspond to the functionally identical units in FIG.

[Configuration and effects of the present embodiment]
The method of controlling the vehicle 10 according to the present embodiment is a method of controlling a vehicle in which the driving motor 4 is used as a traveling drive source and decelerated by the regenerative braking force of the driving motor 4 . In this control method, when the vehicle 10 stops based on the accelerator operation amount, the torque of the drive motor 4 is controlled so as to converge to the disturbance torque estimated value _Td obtained by estimating the disturbance acting on the vehicle 10. A control step (step S203) is provided. In this control step, the torque of the drive motor 4 is added to the disturbance torque estimated value T _d in the first period from the relatively high vehicle speed range to the relatively low vehicle speed range among the periods when the vehicle 10 stops. Control is performed to converge, and in a second period from a relatively low vehicle speed range to after the vehicle 10 stops in the period when the vehicle 10 stops, based on the slope of the road on which the vehicle 10 runs, Control is performed so that the torque of the drive motor 4 converges to the stop maintaining torque T _d 2 (an example of the torque target value) obtained by decreasing the magnitude of the disturbance torque estimated value T _d based on 0.

According to such a control method for the vehicle 10, by executing the stop control using the stop maintaining torque T _d 2 obtained based on the slope of the road surface, the running resistance is large, such as on a sandy flat road. It is possible to prevent continuation of unnecessary torque input to the drive motor 4 when the vehicle is stopped on the road surface. As a result, heat generation of the drive motor 4 and deterioration of electricity consumption can be suppressed, for example, in stop control on sandy ground or the like.

Further, in the method for controlling the vehicle 10 according to the present embodiment, the first period is defined as a period from a relatively high vehicle speed range until it is determined that the vehicle 10 has stopped (for example, from time t1 to t2 shown in FIG. 14). 15), and the second period is the period during which the vehicle 10 is maintained in the stopped state after the stop determination of the vehicle 10 (for example, the period from time t2 to t3 shown in FIG. 14). the period from time t12 to t13 shown in FIG. 15).

According to this method of controlling the vehicle 10, when the vehicle 10 is stopped on a road surface with high running resistance, such as a sandy flat road, continuation of unnecessary torque input to the drive motor 4 can be appropriately suppressed. can be done.

Further, in the control method of the vehicle 10 according to the present embodiment, in the control step (step S203), the gradient of the road on which the vehicle 10 is traveling is acquired, and the gradient resistance estimated value T _d 1 is calculated based on the gradient. Based on the estimation processing (processing by the gradient resistance estimating unit 102 shown in FIGS. 2 and 7), the disturbance torque estimated value _Td and the gradient resistance estimated value _Td1 , the stop maintaining torque _Td2 (torque target value example) is executed (processing by the stop maintaining torque calculation unit 501 shown in FIG. 10).

According to the control method of the vehicle 10 as described above, the optimum stop maintaining torque T _d 2 can be obtained using the slope resistance estimated value T _d 1 calculated based on the slope of the road on which the vehicle 10 is traveling.

Further, in the control method of the vehicle 10 according to the present embodiment, in the gradient resistance estimation process, based on the acceleration in the longitudinal direction of the vehicle 10 when the vehicle 10 stops, the vehicle 10 is kept stopped on the road. The torque of the driving motor 4 required for , is calculated as the gradient resistance estimated value T _d 1.

According to such a control method for the vehicle 10, it is possible to accurately calculate the slope resistance estimated value T _d 1 required to keep the vehicle stopped on an inclined road surface.

Further, in the method for controlling the vehicle 10 according to the present embodiment, in the torque calculation process, when the slope resistance estimated value T _d 1 is included in the section IN1 (see FIG. 11), the stop maintaining torque T _d 2 (torque target An example of the value) is set to 0. Note that the interval IN1 is an example of a predetermined range including positive and negative values set with 0 as a reference.

According to such a control method for the vehicle 10, by setting the stop maintaining torque T _d 2 to 0 and converging the motor torque to 0 [Nm], continuation of unnecessary torque input can be suppressed.

Further, in the control method of the vehicle 10 according to the present embodiment, in the torque calculation process, if the estimated slope resistance value T _d 1 is not included in the section IN1 (see FIG. 11), the estimated slope resistance value T _d 1 A value obtained by decreasing the magnitude of the disturbance torque estimated value T _d based on is set as the stop maintaining torque T _d 2 (an example of the torque target value).

According to the method for controlling the vehicle 10 as described above, by executing the stop control using the stop maintaining torque T _d 2 obtained based on the inclination of the road surface, the continuation of unnecessary torque input to the drive motor 4 is prevented. It can be deterred appropriately.

Further, in the control method of the vehicle 10 according to the present embodiment, the interval IN1 (see FIG. 11) is based on the running resistance of the vehicle 10 obtained using the disturbance torque estimated value T _d and the slope resistance estimated value T _d 1. set.

According to the method for controlling the vehicle 10 as described above, it is possible to set an appropriate range for setting the stop maintaining torque T _d 2 to zero.

In addition, in the control method of the vehicle 10 according to the present embodiment, in the torque calculation process, the gradient resistance estimated value T _d 1, the disturbance torque estimated value T _d and the gradient resistance estimated value T _d 1 are used to calculate the torque of the vehicle 10. A value obtained by calculation with the running resistance RR1 is assumed to be a stop maintaining torque T _d2 (an example of a torque target value).

According to such a control method of the vehicle 10, it is possible to maintain the stopped state with as small a motor torque as possible, and it is possible to contribute to the improvement of the heat generation of the drive motor 4 and the electricity consumption to the maximum.

Further, in the torque calculation process in the method for controlling the vehicle 10 according to the present embodiment, the slope resistance estimated value T _d 1 is used as the stop maintaining torque T _d 2 (an example of the torque target value).

According to such a control method of the vehicle 10, by converging the motor torque to the slope resistance estimated value _Td1 that balances with the road surface inclination, the torque that balances with the road surface inclination can be appropriately set.

Further, the control system of the vehicle 10 according to the present embodiment includes the drive motor 4 functioning as a travel drive source, and a motor controller that controls the torque of the drive motor 4 and reduces the speed using the regenerative braking force of the drive motor 4. 2 (an example of a controller). The motor controller 2 controls the torque of the drive motor 4 so that the torque of the drive motor 4 converges to the disturbance torque estimated value _Td obtained by estimating the disturbance acting on the vehicle 10 when the vehicle 10 stops based on the accelerator operation amount. stop control processing (step S203). In this stop control process, of the period when the vehicle 10 stops, in the first period from the relatively high vehicle speed range to the relatively low vehicle speed range, the torque of the drive motor 4 is added to the disturbance torque estimated value _Td . is controlled to converge, and in a second period from a relatively low vehicle speed range to after the vehicle 10 stops, out of the period when the vehicle 10 stops, based on the gradient of the road on which the vehicle 10 runs , 0 is controlled so that the torque of the drive motor 4 converges to the stop maintaining torque T _d 2 (an example of the torque target value) obtained by decreasing the magnitude of the disturbance torque estimated value T _d based on 0.

According to such a control system for the vehicle 10, by executing the stop control using the stop maintaining torque T _d 2 obtained based on the slope of the road surface, the running resistance is large, such as on a sandy flat road. It is possible to prevent continuation of unnecessary torque input to the drive motor 4 when the vehicle is stopped on the road surface. As a result, heat generation of the drive motor 4 and deterioration of electricity consumption can be suppressed, for example, in stop control on sandy ground or the like.

Each process shown in this embodiment is executed based on a program for causing a computer to execute each processing procedure. Therefore, the present embodiment can also be understood as an embodiment of a program that realizes the function of executing each process and a recording medium that stores the program. For example, an update operation to add new functionality to the vehicle may cause the program to be stored in the vehicle's memory. As a result, it is possible to cause the updated vehicle to perform each process shown in the present embodiment. Note that the update can be performed, for example, at the time of periodic inspection of the vehicle. Alternatively, the program may be updated by wireless communication.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have.

REFERENCE SIGNS LIST 1 battery 2 motor controller 3 inverter 4 drive motor 5 speed reducer 6 rotation sensor 7 current sensor 10 vehicle

Claims (10)

A control method for a vehicle in which a driving motor is used as a traveling drive source and the vehicle is decelerated by a regenerative braking force of the driving motor,
a control step of controlling the torque of the drive motor so as to converge to the estimated disturbance torque value obtained by estimating the disturbance acting on the vehicle when the vehicle stops based on the accelerator operation amount;
In the control step,
Control is performed so that the torque of the drive motor converges to the estimated disturbance torque value during a first period in which the vehicle speed range changes from a relatively high vehicle speed range to a relatively low vehicle speed range. ,
In a second period from the relatively low vehicle speed range to after the vehicle stops, among the periods when the vehicle stops, the estimated disturbance torque value is calculated based on the slope of the road on which the vehicle runs. controlling the torque of the drive motor to converge to a reduced torque target value;
Vehicle control method. A vehicle control method according to claim 1,
The first period is a period from the relatively high vehicle speed range until it is determined that the vehicle has stopped,
The second period is a period in which the vehicle is maintained in a stopped state after the vehicle is determined to be stopped.
Vehicle control method. The vehicle control method according to claim 1 or 2,
In the control step,
Gradient resistance estimation processing for acquiring the gradient of the travel road and calculating a gradient resistance estimated value based on the gradient;
a torque calculation process for obtaining the torque target value based on the disturbance torque estimated value and the gradient resistance estimated value;
Vehicle control method. A vehicle control method according to claim 3,
In the gradient resistance estimation process, the torque of the drive motor required to keep the vehicle stopped on the road is calculated based on the acceleration in the longitudinal direction of the vehicle when the vehicle stops. calculated as an estimate,
Vehicle control method. The vehicle control method according to claim 3 or 4,
In the torque calculation process, the torque target value is set to 0 when the estimated slope resistance value is within a predetermined range including positive and negative values set with 0 as a reference,
Vehicle control method. A vehicle control method according to any one of claims 3 to 5,
In the torque calculation process, if the estimated gradient resistance value is not included in a predetermined range including positive and negative values set with 0 as a reference, the estimated disturbance torque value is increased based on the estimated gradient resistance value. The torque target value is the value obtained by reducing the
Vehicle control method. The vehicle control method according to claim 5 or 6,
The predetermined range is set based on the running resistance of the vehicle obtained using the estimated disturbance torque value and the estimated slope resistance value.
Vehicle control method. A vehicle control method according to claim 6,
In the torque calculation process, a value obtained by calculation of the estimated slope resistance value and the running resistance of the vehicle obtained using the estimated disturbance torque value and the estimated slope resistance value is set as the target torque value. ,
Vehicle control method. A vehicle control method according to claim 3,
In the torque calculation process, the gradient resistance estimated value is set as the torque target value,
Vehicle control method. A control system for a vehicle, comprising: a drive motor functioning as a travel drive source; and a controller for controlling the torque of the drive motor and decelerating the vehicle by the regenerative braking force of the drive motor,
The controller controls the torque of the drive motor so as to converge to a disturbance torque estimated value obtained by estimating a disturbance acting on the vehicle when the vehicle stops based on an accelerator operation amount. perform the processing,
In the stop control process,
Control is performed so that the torque of the drive motor converges to the estimated disturbance torque value during a first period in which the vehicle speed range changes from a relatively high vehicle speed range to a relatively low vehicle speed range. ,
In a second period from the relatively low vehicle speed range to after the vehicle stops, among the periods when the vehicle stops, the estimated disturbance torque value is calculated based on the slope of the road on which the vehicle runs. controlling the torque of the drive motor to converge to a reduced torque target value;
Vehicle control system.

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