JP6880674B2 - Electric vehicle control method and electric vehicle control device - Google Patents

Description

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

Conventionally, in a vehicle acceleration / deceleration control system, when the accelerator operation amount is less than a predetermined value, the deceleration is controlled according to the accelerator operation amount, and when the accelerator operation amount is equal to or more than a predetermined value, the acceleration is adjusted according to the accelerator operation amount. A control technique is known (see Patent Document 1). According to this acceleration / deceleration control system, the target acceleration / deceleration can be set according to the accelerator operation amount. Therefore, if the target acceleration / deceleration is set to 0, the accelerator operation can be performed even on an uphill road. It is possible to maintain a constant vehicle speed without the need to adjust the amount.

Japanese Unexamined Patent Publication No. 2000-205015

Here, in order to maintain a constant vehicle speed on an uphill road without adjusting the accelerator operation amount, the road surface gradient is estimated, and the driving torque of the vehicle is applied to drive the vehicle when traveling on a flat road according to the estimated road surface gradient. It is necessary to correct the torque by adding the gradient resistance.

However, when the battery is fully charged or in a scene where the regenerative power is limited by the heating protection of the motor or the like, the friction braking force by the friction brake may be applied to the vehicle in addition to the regenerative braking force.

The friction braking force is a gradient resistance that acts in the opposite direction to the driving torque in the traveling direction of the vehicle. Therefore, when the vehicle body speed falls below a predetermined value, the positive or negative of the vehicle body speed is reversed if there is a gradient on the road surface. By doing so, the positive and negative of the correction amount of the drive torque corresponding to the gradient resistance may be reversed, and vibration may occur in the vehicle body.

An object of the present invention is to provide a technique for suppressing vibration in a vehicle body even when the speed of the vehicle is equal to or less than a predetermined value.

The method for controlling an electric vehicle according to the present invention is a method for controlling an electric vehicle including a motor that functions as a traveling drive source and applies a regenerative braking force to the vehicle, and a friction braking unit that applies a friction braking force to the vehicle. Detects the rotation speed of the motor or a speed parameter proportional to the rotation speed, calculates the disturbance torque estimate value which is the estimated value of the torque generated by the disturbance acting on the motor, and detects or estimates the friction braking amount due to the friction brake. The friction braking amount is excluded from the disturbance torque estimate, and the disturbance torque estimate is corrected so that the disturbance torque estimate matches the gradient disturbance. When the electric vehicle is below a predetermined vehicle speed, and controls the motor so that the motor torque with a decrease in rotational speed or speed parameters of the motor converges to the disturbance torque, the following electric dynamic vehicle Jo Tokoro vehicle speed, the friction braking amount When the drive torque in the traveling direction is equal to or greater than the absolute value , the amount of correction for disturbance torque is reduced.

According to the present invention, the amount of correction to the disturbance torque estimated value is reduced as the vehicle speed decreases, so that vibration of the vehicle body is suppressed even when the vehicle slightly retracts when the vehicle speed approaches zero. be able to.

FIG. 1 is a block diagram showing a main configuration of an electric vehicle including a control device for an electric vehicle according to an embodiment. FIG. 2 is a flow of processing of motor current control performed by the motor controller included in the control device of the electric vehicle according to the first embodiment. FIG. 3 is a diagram showing an example of an accelerator opening degree-torque table. FIG. 4 is a diagram modeling a driving force transmission system of a vehicle. FIG. 5 is a diagram modeling a braking force transmission system for wheels. FIG. 6 is a block diagram for realizing the stop control process. FIG. 7 is a diagram for explaining a method of calculating the motor rotation speed F / B torque Tω based on the motor rotation speed ωm. FIG. 8 is a diagram for explaining a method of calculating the disturbance torque estimated value Td. FIG. 9 is a diagram for explaining a method of calculating a brake torque correction value based on the brake braking amount B and the wheel speed ωw. FIG. 10 is a diagram showing an example of the relationship between the brake torque correction factor and the absolute value of the vehicle speed. FIG. 11 is a flowchart showing a flow of correction of the disturbance torque estimated value by the brake torque correction value. FIG. 12 is a diagram showing an example of a control result by the control device of the electric vehicle of one embodiment.

Hereinafter, an example in which the control device for an electric vehicle according to the present invention is applied to an electric vehicle whose drive source is an electric motor (hereinafter, referred to as an electric motor or simply a motor) will be described.

[One Embodiment]
FIG. 1 is a block diagram showing a main configuration of an electric vehicle including a control device for an electric vehicle according to an embodiment. The control device for an electric vehicle of the present invention includes an electric motor 4 (hereinafter, also simply referred to as a motor 4) as a part or all of the drive source of the vehicle, and can be applied to an electric vehicle that can travel by the driving force of the electric motor. is there. Electric vehicles include not only electric vehicles but also hybrid vehicles and fuel cell vehicles. In particular, the control device for an electric vehicle according to the present embodiment can be applied to a vehicle that can control acceleration / deceleration and stop of the vehicle only by operating the accelerator pedal. In this vehicle, the driver depresses the accelerator pedal when accelerating, and reduces the depressing amount of the accelerator pedal when decelerating or stopping, or sets the depressing amount of the accelerator pedal to zero. On an uphill road, the vehicle may approach a stopped state while depressing the accelerator pedal in order to prevent the vehicle from moving backward.

The motor controller 2 functions as a controller for controlling the vehicle system. The motor controller 2 indicates the vehicle state of the vehicle speed V, the accelerator opening degree θ (accelerator operation amount), the rotor phase α of the motor (three-phase AC motor) 4, the three-phase AC currents iu, iv, iw of the motor 4, and the like. The signal is input as a digital signal. The motor controller 2 generates a PWM signal for controlling the driving force and the regenerative braking force of the motor 4 based on the input signal. Further, the motor controller 2 controls the opening and closing of the switching element of the inverter 3 according to the generated PWM signal. The motor controller 2 further generates a friction braking amount command value according to the accelerator operation amount by the driver or the operation amount of the brake pedal 10.

The inverter 3 converts the direct current supplied from the battery 1 into alternating current by turning on / off two switching elements (for example, power semiconductor elements such as IGBTs and MOS-FETs) provided for each phase. Then, a desired current is passed through the motor 4.

The motor 4 generates a driving force by an alternating current supplied from the inverter 3, and transmits the driving force to the left and right drive wheels 9a and 9b via the speed reducer 5 and the drive shaft 8. Further, the motor 4 recovers the kinetic energy of the vehicle as electric energy by generating a regenerative driving force when the motor 4 is rotated by the drive wheels 9a and 9b while the vehicle is traveling. In this case, the inverter 3 converts the alternating current generated during the regenerative operation of the motor 4 into a direct current and supplies it to the battery 1.

The current sensor 7 detects the three-phase alternating currents Iu, Iv, and Iw flowing through the motor 4. However, since the sum of the three-phase alternating currents Iu, Iv, and Iw is 0, the current of any two phases may be detected and the current of the remaining one phase may be obtained by calculation.

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

The brake controller 11 outputs to the friction brake 13 a brake actuator command value that generates a brake hydraulic pressure (pressure of the master cylinder) according to the friction braking amount command value generated by the motor controller 2. Further, the brake controller 11 performs feedback control so that the brake hydraulic pressure detected by the hydraulic pressure sensor 12 follows a value determined according to the friction braking amount command value.

The hydraulic pressure sensor 12 functions as a brake braking amount detecting means, acquires a brake braking amount B by detecting the brake hydraulic pressure of the friction brake 13, and uses the acquired brake braking amount B as the brake controller 11 and the motor controller 2. Output to.

The friction brake 13 functions as a friction braking unit. Specifically, the friction brake 13 is provided on each of the left and right drive wheels 9a and 9b, and presses the brake pad against the brake rotor according to the brake fluid pressure to generate a braking force in the vehicle. In the following description, the magnitude of this braking force is referred to as the friction braking amount.

The friction braking force by the friction brake 13 is a friction braking amount command output from the motor controller 2 when the maximum regenerative braking torque is insufficient with respect to the braking torque intended by the driver calculated from the accelerator operation amount and the vehicle speed. Used according to the value. Further, the friction braking force is desired by the driver because the regenerative power is limited by the fully charged battery 1 or the heating protection of the motor 4 even when the braking force intended by the driver is smaller than the maximum regenerative braking torque. It is also used when the braking force to be applied cannot be covered by the regenerative braking torque alone. The friction braking force is used not only when it is required according to the accelerator operating amount, but also when the desired braking force is achieved by the driver's brake pedal operating amount.

FIG. 2 is a flowchart showing a flow of processing of motor current control performed by the motor controller 2.

In step S201, a signal indicating the vehicle state is input to the motor controller 2. Here, the vehicle speed V (m / s), the accelerator opening degree θ (%), the rotor phase α (rad) of the motor 4, the rotation speed Nm (rpm) of the motor 4, and the three-phase direct current iu flowing through the motor 4. The iv, iv, the DC voltage value V _dc (V) between the battery 1 and the inverter 3, the brake operation amount, and the brake braking amount B are input.

The vehicle speed V (km / h) is the wheel speed of the wheels (driving wheels 9a, 9b) that transmit the driving force when the vehicle is driven. The vehicle speed V is acquired by communication from the wheel speed sensors 14a and 14b and other controllers (not shown). Alternatively, the vehicle speed V (km / h) is obtained by multiplying the rotor mechanical angular velocity ωm by the tire moving radius r and dividing by the gear ratio of the final gear to obtain the vehicle speed v (m / s) and multiply by 3600/1000. It is obtained by converting the unit by doing so.

The accelerator opening degree θ (%) is acquired from an accelerator opening degree sensor (not shown) or by communication from another controller such as a vehicle controller (not shown) as an index indicating the amount of accelerator operation by the driver.

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

The three-phase alternating currents iu, iv, and iwa (A) flowing through the motor 4 are acquired from the current sensor 7.

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

The brake braking amount B is acquired from the brake hydraulic pressure sensor value detected by the hydraulic pressure sensor 12. Alternatively, a detection value (brake operation amount) by a stroke sensor (not shown) or the like that detects the amount of depression of the brake pedal by the driver's pedal operation may be used.

In the torque target value calculation process in step S202, the motor controller 2 sets ^{the first torque target value Tm1 *.} Specifically, refer to the first accelerator opening-torque table shown in FIG. 3, which shows one aspect of the driving force characteristic calculated according to the accelerator opening θ and the motor rotation speed ωm input in step S201. By doing so, the first torque target value Tm1 ^* is set. As described above, the control device for the electric vehicle according to the present embodiment can be applied to a vehicle that can control acceleration / deceleration and stop of the vehicle only by operating the accelerator pedal, and at least the vehicle can be operated by fully closing the accelerator pedal. In order to enable the vehicle to be stopped, in the accelerator opening-torque table shown in FIG. 3, a negative motor torque is set so that a regenerative braking force is applied when the accelerator opening is 0 (fully closed). .. However, the accelerator opening-torque table is not limited to that shown in FIG.

In step S203, the motor controller 2 performs the stop control process. Specifically, the motor controller 2 determines whether or not the vehicle is about to stop (or less than a predetermined vehicle speed, or the speed parameter proportional to the vehicle speed is less than or equal to a predetermined default value), and if it is not just before the stop, it is calculated in step S202. The first torque target value Tm1 ^* is set to the motor torque command value Tm ^* , and the second torque target value Tm2 ^* is set to the motor torque command value Tm ^{* when the vehicle is about to stop.} This second torque target value Tm2 ^* converges to the disturbance torque command value Td, which becomes a gradient resistance as the motor rotation speed decreases, and is positive torque on uphill roads, negative torque on downhill roads, and flat roads. It is almost zero. As a result, the state in which the motor torque and the gradient resistance are balanced is maintained, so that the stopped state can be maintained regardless of the gradient of the road surface.

Here, when a vehicle equipped with a motor that functions as a traveling drive source and gives a regenerative braking force to the vehicle stops, the vehicle first decelerates by the regenerative braking force. However, in a scene where the regenerative power is limited by the heating protection of the motor or when the battery is fully charged, the friction braking force by the friction brake is applied to the vehicle in addition to the regenerative braking force in order to obtain the deceleration desired by the driver. In some cases. Since this friction braking force acts as a resistance component that is not related to the gradient resistance with respect to the motor torque, in order to realize a smooth stop on an uphill road, it depends on the magnitude of the friction braking force (friction braking amount). Therefore, it is necessary to correct the disturbance torque estimated value Td so that the disturbance torque estimated value Td and the gradient resistance are substantially the same.

Therefore, when calculating the disturbance torque estimated value Td in step S203, the friction braking amount acting on the motor 4 as a resistance component not related to the gradient is excluded from the disturbance torque estimated value, and the disturbance torque estimated value is referred to as the gradient disturbance. Disturbance torque correction processing is performed to roughly match.

Further, since the friction braking force is regarded as a gradient resistance acting in the opposite direction to the driving torque in the traveling direction of the vehicle, when the disturbance torque estimated value Td is corrected according to the friction braking amount, the vehicle The positive or negative of the correction changes depending on the direction of travel. Therefore, when the positive / negative of the vehicle body speed is reversed, such as when the vehicle slightly retreats when the vehicle speed on the uphill road becomes close to zero (below the predetermined vehicle speed), the positive / negative of the correction amount of the drive torque for the gradient resistance is reversed. Vibration may occur in the vehicle body.

In order to suppress such vibration, in the present embodiment, a correction amount adjustment process for adjusting the correction amount for the disturbance torque estimated value in the disturbance torque correction process according to the vehicle speed V is also executed. Details of the stop control process including these processes will be described later.

In the following step S204, the motor controller 2 performs a current command value calculation process. Specifically, in addition to the torque target value Tm ^* (motor torque command value Tm ^{* ) calculated in step S203, the d-axis current target value id *} and the q-axis current are based on the motor rotation speed ωm and the DC voltage value Vdc. Find the target value iq ^* . For example, by preparing in advance a table that defines the relationship between the torque command value, the motor rotation speed, and the DC voltage value, and the d-axis current target value and the q-axis current target value, by referring to this table, Obtain the d-axis current target value id ^* and the q-axis current target value iq ^*.

In step S205, current control is performed to match the d-axis current id and the q-axis current iq with the d-axis current target value id ^* and the q-axis current target value iq ^{* obtained in step S204, respectively.} Therefore, first, the d-axis current id and the q-axis current iq are obtained based on the three-phase AC currents iu, iv, and iwa input in step S201 and the rotor phase α of the electric motor 4. Subsequently, the d-axis and q-axis voltage command values vd and vq are calculated from the deviations between the d-axis and q-axis current command values id ^* and iq ^{* and the d-axis and q-axis current id and iq.}

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

_{Here, prior to the description of the stop control process executed in step S203, the transmission characteristic G p} (s) of the control device of the electric vehicle according to the present embodiment from the motor torque Tm to the motor rotation speed ω m will be described. The transmission characteristic G _p (s) is used as a vehicle model that models the driving force transmission system of the vehicle in the stop control process including the estimation of the disturbance torque.

FIG. 4 is a diagram modeling a driving force transmission system of a vehicle, and each parameter in the figure is as shown below.
J _m : Electric motor inertia J _w : Drive wheel inertia M: Vehicle weight K _d : Drive system torsional rigidity K _t : Coefficient related to friction between tire and road surface N: Overall gear ratio r: Tire load radius ω _m : Motor rotation speed T _m : Torque target value ^{T m *}
T _d : Drive wheel torque F: Force applied to the vehicle V: Vehicle speed ω _w : Drive wheel angular velocity Then, the following equation of motion can be derived from FIG.

^{However, the asterisk (*} ) attached to the upper right of the code in the equations (1) to (3) represents the time derivative.

_{When the transmission characteristic G p} (s) from the motor torque Tm of the motor 4 to the motor rotation speed ωm is obtained based on the equations of motion represented by the equations (1) to (5), it is expressed by the following equation (6).

However, each parameter in the equation (6) is represented by the following equation (7).

By examining the poles and zeros of the transfer function shown in equation (6), it can be approximated to the transfer function of equation (8), and one pole and one zero show extremely close values. This corresponds to the fact that α and β in the following equation (8) show extremely close values.

Therefore, by performing the pole-zero cancellation (approximate to α = β) in the equation (8), G _p (s) is of (second order) / (third order) as shown in the following equation (9). Consists of transmission characteristics.

Next, the transmission characteristic Gb (s) from the brake braking amount B to the motor rotation speed ωm will be described.

FIG. 5 is a diagram modeling the braking force transmission system of the wheel, and each parameter in the figure is as shown below.
rb: Radius to the point of action where the friction braking force acts F / B: Brake braking amount at the point of action of the friction brake
B: Brake braking amount Then, the following equation of motion can be derived from FIG.

However, the F / B in the equation (10) is as follows.
ωw> 0: F / B> 0
ωw = 0: F / B = 0
ωw <0: F / B <0
Then, the following equation of motion can be derived from FIGS. 4 and 5.

Based on the equations of motion shown by the equations (1), (3), (4), (5), and (11), the transmission characteristic Gb (s) from the brake braking amount B to the motor rotation speed ωm is obtained as follows. It is represented by the equation (12).

However, each parameter in the equation (12) is represented by the following equation (13).

Subsequently, the details of the stop control process executed in step S203 will be described with reference to FIGS. 6 to 11.

<Stop control>
FIG. 5 is a block diagram for realizing the stop control process. The stop control process is performed using the motor rotation speed F / B torque setter 501, the disturbance torque estimator 502, the adder 503, and the torque comparator 504. Hereinafter, each configuration will be described in detail.

The motor rotation speed F / B torque setter 501 calculates the motor rotation speed feedback torque (hereinafter referred to as motor rotation speed F / B torque) Tω based on the detected motor rotation speed ωm. Details will be described with reference to FIG.

FIG. 7 is a diagram for explaining a method of calculating the motor rotation speed F / B torque Tω based on the motor rotation speed ωm. The motor rotation speed F / B torque setting device 501 includes a multiplier 601 and calculates the motor rotation speed F / B torque Tω by multiplying the motor rotation speed ωm by the gain Kvref. However, Kvref is a negative (minus) value required to stop the electric vehicle just before the electric vehicle is stopped, and is appropriately set based on, for example, experimental data. The motor rotation speed F / B torque Tω is set as a torque at which a larger braking force can be obtained as the motor rotation speed ωm increases.

Although the motor rotation speed F / B torque setting device 501 has been described as calculating the motor rotation speed F / B torque Tω by multiplying the motor rotation speed ωm by the gain Kvref, the regenerative torque with respect to the motor rotation speed ωm has been described. The motor rotation speed F / B torque Tω may be calculated by using a regenerative torque table in which the above is set, a damping rate table in which the attenuation rate of the motor rotation speed ωm is stored in advance, or the like.

The explanation will be continued by returning to FIG. The disturbance torque estimator 502 calculates the disturbance torque estimation value T _d based on the detected motor rotation speed ωm and the motor torque command value Tm ^*. Details of the disturbance torque estimator 502 will be described with reference to FIG.

FIG. 8 shows disturbance based on the motor rotation speed ωm, the motor torque command value Tm ^*, and the brake torque correction value calculated based on the wheel speed ωw as a speed parameter indicating the brake braking amount B and the vehicle speed V. It is a block diagram for demonstrating the method of calculating the torque estimate value T _d. The disturbance torque estimator 502 includes a control block 801, a control block 802, a brake torque estimator 803, an addition / subtractor 804, and a control block 805.

The control block 801 functions as a filter having a transmission characteristic of H (s) / G _p (s), and estimates the first motor torque by inputting the motor rotation speed ωm and performing filtering processing. Calculate the value. G _p (s) is a model of the transmission characteristics of the torque input to the vehicle and the rotation speed of the motor, and is represented by the equation (9). H (s) is a low-pass filter having a transfer characteristic in which the difference between the denominator order and the numerator order is equal to or greater than the difference between the denominator order and the numerator order of _{the model G p (s).}

The control block 802 functions as a low-pass filter having a transmission characteristic of H (s), and calculates a second motor torque estimated value by inputting ^{a motor torque command value Tm * and performing filtering processing.} To do.

The brake torque estimator 803 calculates a brake torque estimated value as a braking force applied to the vehicle by the friction brake 13 based on the brake braking amount B and the wheel speed ωw. Then, a value obtained by multiplying the calculated brake torque estimated value by a ratio corresponding to the wheel speed ωw is output as a brake torque correction value.

The details of the brake torque estimator 803 will be described with reference to FIG. FIG. 9 is a control block diagram for explaining a method of calculating a brake torque correction value based on the brake braking amount B and the wheel speed ωw.

The control block 901 filters the brake braking amount B according to the transmission characteristic Gb (s) described above, and calculates an estimated brake rotation speed. Here, the braking force due to the brake acts in the deceleration direction both when the vehicle is moving forward and backward, and is therefore proportional to the vehicle front-rear speed (body speed, wheel speed, motor rotation speed, drive shaft rotation speed, or these values. It is necessary to invert the sign of the brake torque estimate value according to the sign of the speed parameter). Therefore, the control block 901 sets the sign of the brake rotation speed estimation value to be negative if the vehicle is moving forward and positive if the vehicle is moving backward, according to the input wheel speed ωw.

_{The control block 902 functions as a filter having a transmission characteristic of H (s) / G p} (s) using a low-pass filter H (s), and inputs an estimated brake rotation speed to perform filtering processing. To calculate the estimated brake torque value. The calculated brake torque estimated value is output to the correction factor adjuster 903.

The ABS function 904 calculates the absolute value of the input wheel speed ωw and outputs the calculated value to the low-pass filter 905.

The low-pass filter 905 outputs a value obtained by performing a filtering process for canceling high-frequency noise with respect to the absolute value of the wheel speed ωw to the correction factor calculator 906.

The correction factor calculator 906 determines the ratio of the brake torque estimated value to be canceled from the disturbance torque estimated value according to the vehicle speed. Specifically, the correction factor calculator 906 calculates the ratio of the estimated brake torque value (brake torque correction factor) to be added to the estimated disturbance torque value according to the absolute value of the wheel speed ωw, and the calculated brake torque correction The rate is output to the correction factor adjuster 903. A method of calculating the brake torque correction factor will be described with reference to FIG.

FIG. 10 is a diagram showing an example of the relationship between the vehicle speed V (wheel speed ωw) and the brake torque correction factor [%]. As shown in the figure, the correction factor calculator 906 reduces the brake torque correction factor as the absolute value of the wheel speed ωw decreases when the absolute value of the wheel speed ωw is less than a predetermined value (1 km / h). .. The predetermined value may be any value as long as it can be determined that the electric vehicle is stopped, and is set to, for example, 1 km / h in the present embodiment. Therefore, the brake torque correction factor in this embodiment is set to 1 (100%) when the wheel speed ωw is 1 km / h or more. Then, as the vehicle decelerates further and the vehicle speed gradually approaches 0, the brake torque correction factor is set to a smaller value, and when the wheel speed ωw drops to 0.5 km / h, the brake torque correction factor becomes It is set to 0 (0%). The calculated brake torque correction factor is output to the correction factor adjuster 903.

The correction factor adjuster 903 calculates the brake torque correction value by multiplying the brake torque estimated value output from the control block 902 and the brake torque correction factor. By calculating the brake torque correction value in this way, the correction amount for the disturbance torque estimated value can be adjusted according to the vehicle speed. That is, in the present embodiment, for example, when the wheel speed ωw is 1 km / h or more, the brake torque correction factor is 1 (100%), so the brake torque estimated value output from the control block 902 is used as the brake torque correction value as it is. It is output. If the wheel speed ωw is less than 1 km / h, the brake torque correction factor corresponding to that value is multiplied by the brake torque estimated value to correct the disturbance torque estimated value compared to when the wheel speed ωw is 1 km / h or more. A reduced amount of brake torque correction value is output. When the wheel speed ωw is, for example, 0.5 km / h or less, the brake torque correction factor becomes 0%, and the correction amount to the disturbance torque estimated value becomes 0. The calculated brake torque correction value is output to the adder / subtractor 804 shown in FIG.

The adder / subtractor 804 subtracts the first motor torque estimated value from the second motor torque estimated value and adds the brake torque correction value. In the adder / subtractor 804, the disturbance torque estimated value Td in which the brake torque caused by the brake braking amount B is canceled at an appropriate ratio by adding the brake torque correction value having a negative sign with respect to the traveling direction of the vehicle. Can be calculated in the latter stage. The calculated value is output to the control block 805.

Here, prior to the description of the control block 805, the correction flow of the disturbance torque estimated value based on the brake torque correction value described with reference to FIG. 9 will be described with reference to the flowchart shown in FIG.

FIG. 11 is a flowchart illustrating a process for adjusting the correction amount in the correction process according to the vehicle speed V in the correction process of the disturbance torque estimated value based on the brake torque correction value.

Here, when the vehicle decelerates on an uphill road and reaches a stop, the vehicle speed gradually approaches zero. At this time, in the above-mentioned stop control, the vehicle speed overshoots 0 due to the accuracy of the wheel speed sensor, a slight change in the motor rotation speed due to the backlash of the gear, etc., and becomes negative with respect to the traveling direction. It may retreat slightly. Then, since the sign of the brake torque estimated value is set according to the wheel speed ωw, the sign of the brake torque correction value for correcting the disturbance torque estimated value is reversed according to the traveling direction of the vehicle. As a result, the value of the disturbance torque estimated value to which the brake torque correction value is added suddenly changes, and accordingly, the motor torque (control drive torque) that converges to the disturbance torque estimated value suddenly changes, and the vehicle vibrates. ..

The flow described below causes a sudden change in the estimated disturbance torque even when the friction braking force of the friction brake 13 acts on the motor 4 and the vehicle speed overshoots 0 when the vehicle decelerates and stops. This is a process for suppressing the vibration of the vehicle.

In step S1100, the motor controller 2 determines whether or not the vehicle deceleration control is being executed. Specifically, the motor controller 2 determines that deceleration control is being executed when the accelerator pedal opening degree (accelerator operation amount) becomes smaller when the driver releases the accelerator pedal. Further, it may be determined that the deceleration control is being executed even when it is detected that the driver has stepped on the brake pedal. If it is determined that the deceleration control is being executed, the subsequent process of step S1101 is executed. If it is determined that the deceleration control is not being executed, the process of step S1100 is looped in a constant cycle until it is determined that the deceleration control is being executed.

In step S1101, the motor controller 2 detects the brake braking amount B. The brake braking amount B is detected from the brake hydraulic pressure sensor value detected by the hydraulic pressure sensor 12 or the brake actuator command value output from the brake controller 11 to the friction brake 13. Alternatively, it may be obtained from the amount of operation of the brake pedal by the driver. After the brake braking amount B is detected, the motor controller 2 executes the subsequent process of step S1102.

In step S1102, the motor controller 2 determines whether or not the brake braking amount B acquired in step S1101 is larger than a predetermined value. This step is a step for determining whether or not the vehicle speed can overshoot 0 when the vehicle stops. Here, during deceleration control, if a frictional braking force equal to or greater than the absolute value of the driving torque in the traveling direction of the vehicle is applied to the vehicle, the vehicle can be stopped by the frictional braking force without slightly retreating. Therefore, the predetermined value in the present embodiment is set to a value corresponding to the brake braking amount that outputs the friction braking force equal to or more than the absolute value of the driving torque in the traveling direction of the vehicle by the friction brake 13. The predetermined value as an index in this step may be obtained by referring to a map containing the relationship between the brake braking amount B prepared in advance and the brake torque by the friction brake 13, or the transmission characteristic Gb (s) described above. ) May be calculated.

Therefore, if the brake braking amount B is larger than the predetermined value, the motor controller 2 executes the subsequent process of step S1103 in order to adjust the correction amount of the disturbance torque estimated value based on the brake torque estimated value. If the brake braking amount B is equal to or less than the above-mentioned predetermined value, the vehicle speed does not overshoot 0. Therefore, the process of step S1106 is performed without adjusting the correction amount based on the estimated brake torque value (steps S1103 to S1105). To execute.

In step S1103, the motor controller 2 acquires a speed parameter proportional to the vehicle speed such as the motor rotation speed or the wheel speed. From the viewpoint of vehicle speed detection accuracy in the extremely low speed range, it is preferable to acquire the motor rotation speed detected by the resolver having excellent detection accuracy in the lower speed range.

In step S1104, the motor controller 2 determines whether or not the acquired vehicle speed is equal to or less than a predetermined value. This step is a step for determining whether or not the vehicle is in the extremely low speed region and the vehicle will stop soon. Therefore, for example, 1 km / h is set as the default value here. As a result, it is possible to detect the timing immediately before the vehicle speed can overshoot 0 when the vehicle stops. If the vehicle speed is less than 1 km / h, the motor controller 2 determines that the vehicle will stop soon, and executes the subsequent process of step S1105 to adjust the correction amount of the disturbance torque estimated value. If the vehicle speed is 1 km / h or more, it is determined that the vehicle has not stopped yet, and the process of step S1106 is executed without adjusting the correction amount. In the process in this step, the vehicle speed detected in step S1103 may be compared with the vehicle speed detected in step S1103 of the previous cycle to determine whether or not the vehicle will soon stop from the deceleration direction of the vehicle.

Step S1105 is a process in the correction factor calculator 906 shown in FIG. 9, and the control driving torque of the vehicle is controlled even in a situation where the friction braking force by the friction brake 13 acts on the vehicle and the vehicle speed can overshoot 0. The ratio of the brake torque estimate that corrects the disturbance torque estimate is calculated in order to suppress the sudden change in. That is, based on the relationship between the vehicle speed [km / h] and the brake torque correction factor [%] shown in FIG. 10, the brake torque correction factor according to the vehicle speed detected in step S1103 is calculated.

Step S1106 is a process in the correction factor adjuster 903 shown in FIG. 9, and is a brake torque that corrects the disturbance torque estimated value by multiplying the brake torque estimated value and the brake torque correction factor calculated in step S1105. Calculate the correction value. As a result, when the friction braking force of the friction brake 13 acts on the vehicle and the vehicle speed can overshoot 0, the brake torque correction value obtained by reducing the correction amount of the disturbance torque estimated value according to the vehicle speed is calculated. can do.

Here, the initial value of the brake torque correction factor is 1 (100%). Therefore, if the friction braking amount by the friction brake 13 is equal to or less than a predetermined value (see step S1102), or if the vehicle has not yet stopped and the vehicle speed cannot overshoot 0 (see step S1104). The value of the estimated brake torque value is calculated as it is as the brake torque correction value.

In the following step S1107, the motor controller 2 corrects the disturbance torque estimated value based on the brake torque correction value. More specifically, in the adder / subtractor 804 shown in FIG. 8, the motor controller 2 adds the brake torque correction value to the value obtained by subtracting the first motor torque estimated value from the second motor torque estimated value. As a result, it is possible to calculate the disturbance torque estimated value Td in which the brake torque caused by the brake braking amount B is canceled at an appropriate ratio according to the vehicle speed.

The above is the details of the correction flow of the disturbance torque estimated value based on the brake torque correction value. Returning to FIG. 8, the description of the stop control will be continued.

The disturbance torque estimated value calculated by the adder / subtractor 804 is output to the control block 805. The control block 805 is a filter having a transmission characteristic of Hz (s), which will be described later, and calculates a disturbance torque estimated value Td by inputting the output of the adder / subtractor 804 and performing a filtering process.

Here, the transmission characteristic Hz (s) will be described. By rewriting the equation (9), the following equation (14) is obtained. However, ζz, ωz, ζp, and ωp in the equation (14) are each represented by the equation (15).

From the above, Hz (s) is represented by the following equation (16).

Here, as the disturbance acting on the motor 4, air resistance, modeling error due to fluctuation of vehicle weight due to the number of occupants and the load capacity, rolling resistance of tires, gradient resistance of the road surface, etc. can be considered, but just before the vehicle stops The dominant disturbance factor is gradient resistance. The disturbance factor differs depending on the operating conditions, but the disturbance torque estimator 502 is a brake that is a ^{resistance component that is not related to the motor torque command value Tm *} , the motor rotation speed ωm, and the gradient, and is adjusted to an appropriate ratio according to the vehicle speed. Since the disturbance torque estimated value Td is calculated based on the torque correction value and the vehicle model G _p (s), the above-mentioned disturbance factors can be collectively estimated regardless of the brake operation amount of the driver. As a result, it is possible to realize a smooth stop from deceleration under any driving conditions.

The explanation will be continued by returning to FIG. The adder 503 adds the motor rotation speed F / B torque Tω calculated by the motor rotation speed F / B torque setter 501 and the disturbance torque estimated value Td calculated by the disturbance torque estimator 502. The second torque target value Tm2 ^* is calculated.

The torque comparator 504 compares the magnitudes of the first torque target value Tm1 ^* and the second torque target value Tm2 ^* , and sets the torque target value having the larger value as the motor torque command value Tm ^*. While the vehicle is running, the second torque target value Tm2 ^* is smaller than the first torque target value Tm1 ^* , and when the vehicle decelerates and is about to stop (the speed parameter corresponding to the vehicle speed is equal to or less than a predetermined value), the first It becomes larger than the torque target value Tm1 ^{* of.} Therefore, if the first torque target value Tm1 ^* is larger than the second torque target value Tm2 ^* , the torque comparator 504 determines that the vehicle is about to stop and ^{sets the motor torque command value Tm *} to the first torque target value. Set to Tm1 ^*. Further, the torque comparator 504 determines that the vehicle is about to stop when the second torque target value Tm2 ^* becomes larger than the first torque target value Tm1 ^{* , and sets the motor torque command value Tm *} as the first torque target. The value Tm1 ^* is switched to the second torque target value Tm2 ^*. In order to maintain the stopped state, the second torque target value Tm2 ^* converges to positive torque on uphill roads, negative torque on downhill roads, and approximately zero on flat roads.

The predetermined value, which is an index for determining just before a stop, is a vehicle speed equal to or higher than a default value, which is an index for determining whether or not the vehicle will soon stop in step S1104 described with reference to FIG.

Hereinafter, the effect when the control device for the electric vehicle according to the present embodiment is applied to the electric vehicle will be described with reference to FIG.

FIG. 12 is a diagram comparing an example of the control result by the control device of the electric vehicle in the present embodiment with the control result by the conventional control. FIG. 12 shows the control results when the vehicle is stopped on an uphill road having a constant slope. From the top, (a) vehicle speed, (b) brake braking amount B, (c1) brake torque estimated value in conventional control, and (d1). These are the motor torque in the conventional control, (c2) the estimated brake torque value (brake torque correction value) corrected in the present embodiment, and (d2) the motor torque in the present embodiment.

At time t1, the vehicle decelerates due to the use of a certain amount of brake braking amount B from before time t1, and the vehicle speed falls below a predetermined value (for example, 1 km / h). At this time, the estimated brake torque value is calculated as a torque conversion value of the brake braking amount B in the negative direction as shown in the figure.

From time t1 to t2, the vehicle speed gradually approaches 0. Further, since the brake torque estimated value in the conventional control from the time t1 to t2 is not corrected according to the vehicle speed, it is a constant value like the brake braking amount B.

At time t2, the vehicle tries to stop, but the vehicle speed overshoots 0 due to the accuracy of sensors such as the vehicle speed sensor and the gradient sensor, the influence of gear backlash, and the like, and the vehicle moves backward slightly.

At this time, in the conventional control, the sign of the estimated brake torque value is reversed as the traveling direction of the vehicle is reversed, and the positive and negative directions of the motor torque (control drive torque) of the vehicle are suddenly changed accordingly. The motor torque overshoots the estimated disturbance torque. As a result, the vehicle is shocked or vibrated in the front-rear direction.

Further, even at times t3 to t6, in the conventional technique, vibration is generated due to a sudden change in the motor torque every time the sign of the estimated brake torque value is reversed as in t2.

On the other hand, an example of the control result by the control device of the electric vehicle according to the present embodiment will be described.

As described above, the vehicle speed below the predetermined value (1 km / h) at time t1 gradually approaches 0 from time t1 to t2. At this time, according to the control device for the electric vehicle of the present embodiment, the brake according to the vehicle speed is based on the table showing the relationship between the vehicle speed (wheel speed ωw) and the brake torque correction factor [%] shown in FIG. The torque correction value is calculated. The brake torque correction value is a value obtained by correcting the estimated brake torque value and is reduced according to the vehicle speed. Therefore, as shown in the figure, the brake torque correction value becomes smaller as the vehicle speed approaches 0.

As a result, the brake torque correction value at the time t2 when the vehicle speed becomes 0 becomes 0. Therefore, according to the control device for the electric vehicle of the present embodiment, the correction amount of the disturbance torque estimated value (not shown) at the timing when the vehicle speed crosses 0 is 0, and the disturbance torque estimated value does not change suddenly. As shown in the figure, sudden changes in motor torque can be suppressed, and the vibration of the vehicle caused by the sudden changes can be suppressed.

Further, even in a scene where the vehicle speed straddles 0 at times t3 to t6, the brake torque correction value becomes 0 according to the vehicle speed, so that sudden changes in the motor torque can be suppressed and vibration generation of the vehicle can be suppressed.

As described above, the control device for an electric vehicle according to the embodiment is a control method for an electric vehicle including a motor 4 that functions as a traveling drive source and applies a regenerative braking force to the vehicle, and a friction braking unit that applies a friction braking force to the vehicle. Is a device that realizes the above, detects or estimates the rotation speed of the motor or a speed parameter proportional to the rotation speed, calculates the estimated value of the disturbance torque acting on the motor 4, and detects or estimates the brake braking amount B by the friction brake 13. Then, the disturbance torque estimated value is corrected according to the brake braking amount B. Then, when the electric vehicle becomes the predetermined vehicle speed or less, the motor 4 is controlled so that the motor torque converges to the disturbance torque as the rotation speed or the speed parameter of the motor decreases, and the brake braking amount B is predetermined when the electric vehicle is the predetermined value or less. When it is equal to or more than the value, the correction amount for the estimated disturbance torque value is reduced. As a result, even when the vehicle speed overshoots 0 in the scene where the vehicle decelerates and stops, the correction amount to the disturbance torque estimated value is reduced as the vehicle speed decreases, so that the disturbance torque estimation by the correction is performed. It is possible to suppress sudden changes in the value and suppress the occurrence of vehicle vibration.

Further, according to the control device of the electric vehicle of one embodiment, the friction braking unit is the friction brake 13 provided in the vehicle, and the brake braking amount B is a negative sign if the vehicle is moving forward and a positive sign if the vehicle is moving backward. The brake torque estimated value set in the sign of is calculated, and the correction is executed by adding the brake torque estimated value from the disturbance torque estimated value. Further, when a brake braking amount B equal to or less than a predetermined value is detected after the vehicle is about to stop, the smaller the rotation speed or speed parameter of the motor 4, the smaller the absolute value of the estimated brake torque value to be added to the estimated disturbance torque value. .. As a result, when the friction braking amount by the friction brake 13 acts on the vehicle in the scene where the vehicle decelerates and stops, the correction for canceling the brake braking amount from the estimated disturbance torque is executed and the vehicle speed becomes smaller. Since the ratio of the brake braking amount canceled from the disturbance torque estimated value becomes smaller according to the above, it is possible to suppress a sudden change in the disturbance torque estimated value due to the correction and suppress the occurrence of vibration of the vehicle.

The present invention is not limited to the above-described embodiment. For example, in the above description, when the accelerator operation amount is equal to or less than a predetermined value and the electric vehicle is about to stop, the rotation speed of the electric motor 4 decreases and the estimated disturbance torque after correcting the ^{motor torque command value Tm *.} It has been described as having converged to Td. However, since speed parameters such as wheel speed, vehicle body speed, and drive shaft rotation speed are proportional to the rotation speed of the electric motor 4, the motor torque command value is reduced as the speed parameter is proportional to the rotation speed of the electric motor 4. Tm ^* may be converged to the disturbance torque estimated value Td.

2 ... Motor controller (controller)
4 ... Motor 6 ... Rotation sensor 11 ... Brake controller 13 ... Friction brake 14a, 14b ... Wheel speed sensor

Claims (5)

In a control method for an electric vehicle, which comprises a motor that functions as a traveling drive source and gives a regenerative braking force to the vehicle, and a friction brake that gives a friction braking force to the vehicle.
Detecting the rotational speed of the motor or a speed parameter proportional to the rotational speed,
The disturbance torque estimated value, which is the estimated value of the torque generated by the disturbance acting on the motor, is calculated.
Detecting or estimating the amount of friction braking by the friction brake,
The friction braking amount is excluded from the disturbance torque estimate, and the disturbance torque estimate is corrected so that the disturbance torque estimate matches the gradient disturbance.
When the electric vehicle becomes the predetermined vehicle speed or less, the motor is controlled so that the motor torque converges to the disturbance torque estimated value as the rotation speed of the motor or the speed parameter decreases.
When the electric vehicle is at or below the predetermined vehicle speed and the friction braking amount is equal to or greater than the absolute value of the driving torque in the traveling direction, the correction amount for the disturbance torque estimated value is reduced.
How to control an electric vehicle. In the method for controlling an electric vehicle according to claim 1,
The predetermined vehicle speed or less is a case where the vehicle is about to stop and the rotation speed of the motor or the speed parameter is smaller than a predetermined value.
How to control an electric vehicle. In the method for controlling an electric vehicle according to claim 1 or 2.
From the friction braking amount, a brake torque estimate set to a negative sign if the vehicle is moving forward and a positive sign if the vehicle is moving backward is calculated.
The correction adds the brake torque estimate to the disturbance torque estimate.
How to control an electric vehicle. In the method for controlling an electric vehicle according to claim 2,
When the friction braking amount that is equal to or less than the absolute value of the driving torque in the traveling direction is detected after the vehicle is about to stop, the brake that is added to the disturbance torque as the rotation speed of the motor or the speed parameter becomes smaller. Decrease the absolute value of the torque estimate,
How to control an electric vehicle. In an electric vehicle control device including a motor that functions as a traveling drive source and applies regenerative braking force to the vehicle, a friction brake that applies friction braking force to the vehicle, and a controller that controls the vehicle system.
The controller
The disturbance torque estimated value, which is the estimated value of the torque generated by the disturbance acting on the motor, is calculated.
Obtain the friction braking amount by the friction brake,
The friction braking amount is excluded from the disturbance torque estimate, and the disturbance torque estimate is corrected so that the disturbance torque estimate matches the gradient disturbance.
When the electric vehicle becomes the predetermined vehicle speed or less, the motor is controlled so that the motor torque converges to the disturbance torque estimated value as the rotation speed of the motor or the speed parameter decreases.
When the electric vehicle is at or below the predetermined vehicle speed and the friction braking amount is equal to or greater than the absolute value of the driving torque in the traveling direction, the correction amount for the disturbance torque is reduced.
Control device for electric vehicles.

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