JP6597174B2 - Electric vehicle control device and electric vehicle control method - Google Patents

Description

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

  2. Description of the Related Art Conventionally, a regenerative brake control device for an electric vehicle that includes a setting unit that can arbitrarily set a regenerative braking force of an electric motor and performs regeneration of the electric motor with a regenerative braking force set by the setting unit is known (see Patent Document 1). ).

JP-A-8-79907

  However, in the technique disclosed in Patent Document 1, when the regenerative braking force set by the setting unit is large, when the electric vehicle decelerates with the set regenerative braking force and the speed becomes zero, There is a problem that vibration (acceleration vibration) occurs in the longitudinal direction of the vehicle body.

  In response to this problem, the inventors of the present invention adjust the motor torque as the motor rotational speed decreases and reduce the motor torque using a vehicle model configured based on a linear transfer characteristic from the motor torque to the motor rotational speed. By executing stop control that converges to a disturbance torque estimated value that is roughly a gradient resistance, smooth deceleration without acceleration vibration is achieved immediately before stopping regardless of flat roads, uphill roads, and downhill roads. I'm considering holding.

  However, when the vehicle decelerates and stops on an uphill road, the motor torque changes from negative to positive, and therefore a section (dead zone) in which the motor torque is not transmitted to the drive wheels occurs due to gear backlash. Since the estimated disturbance torque is calculated using a vehicle model configured based on a linear transfer characteristic, a modeling error occurs between the vehicle model and the actual vehicle state in the dead zone, and the disturbance torque is reduced. There are issues that cannot be estimated accurately.

  An object of the present invention is to suppress the influence of modeling errors that occur between the vehicle model and the actual vehicle state in the dead zone, and to accurately estimate the disturbance torque.

  An electric vehicle control method according to the present invention is an electric vehicle control method that sets a motor torque command value based on vehicle information and controls the torque of a motor connected to a drive wheel, and detects an accelerator operation amount of a driver. Detecting vehicle parameters proportional to motor rotation speed, inputting motor torque command value, motor torque including dead zone characteristics of gear backlash that motor torque is not transmitted to the drive shaft of the vehicle, to motor rotation speed The disturbance torque acting on the motor is estimated using a nonlinear transfer characteristic model. When the accelerator operation amount decreases and the electric vehicle is about to stop, the motor torque is converged to disturbance torque as the vehicle parameters decrease.

  According to the present invention, disturbance torque is estimated using a non-linear transfer characteristic model from a motor torque including a dead band characteristic of a gear backlash to a motor rotation speed in addition to a vehicle model configured based on a linear transfer characteristic. . Thereby, it is possible to suppress the influence of the modeling error generated between the vehicle model configured based on the linear transfer characteristic and the actual vehicle state, and accurately estimate the disturbance torque.

FIG. 1 is a block diagram illustrating a main configuration of an electric vehicle including a control device for an electric vehicle according to the first embodiment. FIG. 2 is a flowchart showing a flow of processing performed by the motor controller. FIG. 3 is a diagram illustrating an example of an accelerator opening-torque table. FIG. 4 is a diagram modeling a vehicle driving force transmission system. FIG. 5 is a block diagram for realizing the stop control process. FIG. 6 is a diagram for explaining the details of the motor rotation speed F / B torque setting device. FIG. 7 is a block diagram for realizing calculation of a disturbance torque estimated value by the disturbance torque estimator according to the first embodiment. FIG. 8 is a block diagram for realizing calculation of a drive shaft torsion angle estimated value by the drive shaft torsion angle estimator according to the first embodiment. FIG. 9 is a block diagram for realizing calculation of a disturbance torque estimated value by the disturbance torque estimator according to the second embodiment. FIG. 10 is a block diagram for realizing calculation of a drive shaft torsion angle estimated value by the drive shaft torsion angle estimator according to the second embodiment. FIG. 11 is a diagram for explaining a control result by the control device for the electric vehicle according to the first embodiment and the second embodiment.

-First embodiment-
FIG. 1 is a block diagram illustrating a main configuration of an electric vehicle including the control device according to the first embodiment. The electric vehicle is an automobile that includes an electric motor as a part or all of the drive source of the vehicle and can run by the driving force of the electric motor, and includes an electric car and a hybrid car.

  The motor controller 2 receives signals indicating vehicle states such as the vehicle speed V, the accelerator opening θ, the rotor phase α of the electric motor 4, and the currents iu, iv, iw of the electric motor 4 as digital signals. The motor controller 2 generates a PWM signal for controlling the electric motor 4 based on the input signal. Further, a drive signal for the inverter 3 is generated according to the generated PWM signal.

  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 IGBT and MOS-FET) provided for each phase. Then, a desired current is passed through the electric motor 4.

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

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

  The rotation sensor 6 is, for example, a resolver or an encoder, and detects the rotor phase α of the motor 4 as a vehicle parameter proportional to the rotation speed of the motor 4.

  FIG. 2 is a flowchart showing a flow of processing performed by the motor controller 2. The processing from step S201 to step S205 is always executed at regular intervals while the vehicle system is activated.

  In step S <b> 201, a signal indicating the vehicle state is input to the motor controller 2. Here, the vehicle speed V (km / h), the accelerator opening θ (%), the rotor phase α (rad) of the electric motor 4, the rotational speed Nm (rpm) of the electric motor 4, and the three-phase AC flowing through the electric motor 4 The currents iu, iv, iw and the DC voltage value Vdc (V) of the battery 1 are input.

  The vehicle speed V (km / h) is acquired by communication from a vehicle speed sensor (not shown) or another controller. Alternatively, the motor controller 2 obtains the vehicle speed v (m / s) by multiplying the rotor mechanical angular velocity ωm by the tire dynamic radius r and dividing by the gear ratio of the final gear, and multiplying the unit by multiplying by 3600/1000. The vehicle speed V (km / h) is obtained by conversion.

  The motor controller 2 acquires the accelerator opening θ (%) from an accelerator opening sensor (accelerator operation amount detection unit) (not shown). The accelerator opening degree θ (%) may be acquired from another controller such as a vehicle controller (not shown).

  The rotor phase α (rad) of the electric motor 4 is acquired from the rotation sensor 6. The rotational speed Nm (rpm) of the electric motor 4 is obtained by dividing the rotor angular speed ω (electrical angle) by the pole pair number p of the electric motor, and the motor rotational speed ωm (rad / s) that is the mechanical angular speed of the electric motor 4. ) And the obtained motor rotation speed ωm is multiplied by 60 / (2π). The rotor angular velocity ω is obtained by differentiating the rotor phase α.

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

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

In step S202, the motor controller 2 sets a first torque target value Tm1 ^* as a basic target torque. Specifically, the motor controller 2 refers to the accelerator opening-torque table shown in FIG. 3 on the basis of the accelerator opening θ and the vehicle speed V input in step S201, whereby the first torque target value Tm1. Set ^* . However, the accelerator opening-torque table is an example and is not limited to that shown in FIG.

In step S203, the motor controller 2 performs a stop control process for controlling the electric vehicle to stop. Specifically, the stop time of the electric vehicle is determined. Before the stop, the first torque target value Tm1 ^* calculated in step S202 is set to the third torque target value Tm3 ^* . As the motor rotation speed decreases, a second torque target value Tm2 ^* that converges to a disturbance torque estimated value _Td described later is set as a third torque target value Tm3 ^* . The second torque target value Tm2 ^* is positive torque on an uphill road, negative torque on a downhill road, and almost zero on a flat road. Thereby, a stop state can be maintained regardless of the gradient of the road surface. Further, in the stopped state, the third torque target value Tm3 ^* coincides with the disturbance torque estimated value _Td (Tm3 ^* = _Td ). Then, the third torque target value Tm3 ^* is used as a motor torque command value Tm ^* for causing the motor 4 to generate a desired motor torque, in the subsequent current command value calculation process according to step S204. Details of the stop control process will be described later.

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

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

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

Here, before describing the details of the stop control process performed in step S203, the transfer characteristic G _p (which constitutes the vehicle model from the motor torque Tm to the motor rotational speed ωm of the control device for the electric vehicle in the present embodiment). s) will be described.

FIG. 4 is a diagram in which a driving force transmission system of a vehicle is modeled, and each parameter in the figure is as shown below.
J _m : Inertia of electric motor J _w : Inertia of drive wheel (for one axis)
M: body weight K _d : torsional rigidity K _{t of} drive system: coefficient N _al regarding friction between tire and road surface: overall gear ratio r: tire load radius ω _m : motor rotation speed T _m : motor torque T _d : drive wheel Torque F: Driving force (for 2 axes)
V: body speed ω _w : angular velocity of driving wheel θ: torsion angle of driving shaft When the dead zone due to backlash is expressed by the difference between the linear function and the saturation function, the following equations of motion (1) to (6) are derived from FIG. be able to.

  However, Sat (θ) in the equation (4) is a saturation function and is defined by the following equation (7).

Θ _BL in the equation (7) is an overall gear backlash amount (dead band width) from the motor 4 to the drive shaft 8.

  When the above formulas (1) to (6) are Laplace converted and the transfer characteristic from the torque command value to the motor rotation speed is obtained, it can be expressed by the following formula (8).

  In Expression (8), the first term on the right side including Gp (s) represents a linear transfer characteristic model that does not include the dead band characteristic of the gear backlash, and the second term represents a transfer characteristic that functions as gear backlash compensation. This represents a non-linear transfer characteristic model composed of Gps (s) and a saturation function. Gp (s) and Gps (s) are represented by the following equations (9) and (10), respectively.

However, b ₃ , b ₂ , b ₁ , b ₀ , c ₂ , c ₁ in the formulas (9) and (10) are represented by the following formula (11), respectively.

By rearranging equation (9), Gp (s) can be expressed as in the following equation (12). In a general vehicle, when the poles and zeros of the transfer function of Expression (12) are examined, one pole and one zero show extremely close values. This corresponds to the fact that α and β in Equation (12) show extremely close values. However, ζ _p in the following expression is a damping coefficient of the drive shaft torsional vibration system, and ω _p is a natural vibration frequency of the drive shaft torsional vibration system.

Therefore, by performing pole-zero cancellation (approximate with α = β) in equation (12), the transfer characteristic G _p (s) of (second order) / (third order) is obtained as shown in the following equation (13). Constitute.

  Next, details of the stop control process executed by the motor controller 2 will be described with reference to FIG.

  FIG. 5 is a block diagram for realizing the stop control process. The stop control process in the present embodiment is performed using a motor rotation speed F / B torque setter 501, a disturbance torque estimator 502, a subtractor 503, a torque comparator 504, and a vibration suppression control calculator 505. Is called. Details of each configuration will be described below.

  The motor rotation speed F / B torque setter 501 calculates a 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. 6 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 setter 501 includes a multiplier 601 and calculates a motor rotation speed F / B torque Tω by multiplying the motor rotation speed ωm by a gain Kvref. However, Kvref is a negative (minus) value required to stop the electric vehicle just before the electric vehicle stops, and is appropriately set based on, for example, experimental data. The motor rotation speed F / B torque Tω is set as a torque that provides a greater braking force as the motor rotation speed ωm increases.

  The motor rotation speed F / B torque setter 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 motor rotation speed F / B torque Tω may be calculated using a regenerative torque table that defines torque, an attenuation rate table that stores in advance the attenuation rate of the motor rotation speed ωm, or the like.

Returning to FIG. The disturbance torque estimator 502 calculates a disturbance torque estimated value _Td based on the detected motor rotation speed ωm and the third torque target value Tm3 ^* . Details of the disturbance torque estimator 502 will be described later.

The subtractor 503 calculates a deviation between the motor rotation speed F / B torque Tω calculated by the motor rotation speed F / B torque setting unit 501 and the disturbance torque estimation value T _d calculated by the disturbance torque estimator 502. Then, the second torque target value Tm2 ^* is calculated. When the motor rotation speed ωm decreases and approaches 0, the motor rotation speed F / B torque Tω also approaches 0. Therefore, the second torque target value Tm2 ^* is estimated as disturbance torque according to the decrease in the motor rotation speed ωm. It converges to the value _Td .

The torque comparator 504 compares the magnitudes of the first torque target value Tm1 ^* and the second torque target value Tm2 ^* , and sets the larger torque target value as the third torque target value Tm3 ^* . . 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 comes to a stop (the vehicle speed is equal to or less than a predetermined vehicle speed), the first torque target value Tm1 ^* Be bigger than. 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 just before stopping and determines the first torque target value Tm1 ^* as the third torque. Set as target value Tm3 ^* . In addition, when the second torque target value Tm2 ^* becomes larger than the first torque target value Tm1 ^* , the torque comparator 504 determines that the vehicle is about to stop, and uses the third torque target value Tm3 ^* as the first torque target value. The value Tm1 ^* is switched to the second torque target value Tm2 ^* . In order to maintain the stop state, the second torque target value Tm2 ^* converges to a positive torque on an uphill road, a negative torque on a downhill road, and approximately zero on a flat road.

The vibration suppression control computing unit 505 performs vibration suppression control that suppresses torsional vibration of the driving force transmission system on the third torque target value Tm3 ^* output from the torque comparator 504, and performs post-vibration control. The third torque target value Tm3 ^* (hereinafter simply referred to as the third torque target value Tm3 ^* ) is output. As the vibration suppression control, for example, the vibration suppression control described in International Publication No. WO2013 / 157315 is applied.

  Next, details of the disturbance torque estimator 502 characteristic of the present invention will be described with reference to FIG.

FIG. 7 is a block diagram for explaining a method of calculating a disturbance torque estimated value _Td based on the motor rotation speed ωm and the third torque target value Tm3 ^* . The disturbance torque estimator 502 includes a control block 701, a drive shaft torsion angle estimator 702, a non-linear transfer characteristic model 710 including a limiter 703 and a control block 704, an adder 705, a subtractor 706, And a control block 707.

The control block 701 functions as a filter having a linear transfer characteristic Gp (s) expressed by the above equation (13), and performs a filtering process on the third torque target value Tm3 ^* . Thus, a first motor rotational speed estimated value is calculated. The calculated first motor rotation speed estimated value is output to adder 705.

The drive shaft torsion angle estimator 702 calculates the drive shaft torsion angle estimated value θ _d based on the third torque target value Tm3 ^* . Details of the drive shaft torsion angle estimator 702 will be described with reference to FIG.

FIG. 8 is a block diagram for explaining a method of calculating the drive shaft torsion angle estimated value θ _d based on the third torque target value Tm3 ^* . The block diagram shown in FIG. 8 is derived based on Expression (16) described below.

First, when the above equations (1) to (6) are Laplace transformed, the drive shaft torsion angular velocity ω _m / N−ω _w is expressed by the following equation (14). N represents the final gear ratio.

However, H _w (s) in Expression (14) is represented by the following Expression (15).

  From the above equations (4), (6) and (14), the following equation (16) is obtained.

From the equation (16), the block diagram shown in FIG. 8 is derived. FIG. 8 shows a vehicle model 810 that is configured based on the equation (16) and that models the characteristics from the motor torque to the drive shaft torsion angle, including the dead band characteristics of the gear backlash. Tm in Expression (16) corresponds to the third torque target value Tm3 ^* , and (θ−Sat (θ)) based on Expression (4) corresponds to the limiter 801. Accordingly, the drive shaft torsion angle estimator 702 can calculate the drive shaft torsion angle estimated value θd based on the third torque target value Tm3 ^* .

  Returning to FIG. 7, the description will be continued. The drive shaft torsion angle estimated value output from the drive shaft torsion angle estimator 702 is input to the nonlinear transfer characteristic model 710. The transfer characteristic model 710 includes a limiter 703 and a control block 704 having a transfer characteristic of Gps (s) expressed by the above equation (10).

In limiter 703, based on the equation (7), from the drive shaft estimated torsion angle value theta _d, estimated torsion angle value limits the drive shaft is calculated. The calculated value is output to the control block 704.

  The control block 704 functions as a filter having a transfer characteristic of Gps (s) represented by the above formula (10). Gps (s) functions as a gear back ash compensation filter configured to compensate for the dead band characteristics. The control block 704 calculates a motor rotation speed correction value for compensating for the dead band characteristic of the gear backlash based on the drive shaft torsion angle estimated value limit value that is an output from the limiter 703.

  The adder 705 adds the first motor rotation speed estimated value that is the output of the control block 701 having a linear transfer characteristic and the motor rotation speed correction value that is the output of the nonlinear transfer characteristic model 710 to add the first motor rotation speed correction value. 2 is estimated.

As a result, the first estimated motor rotation speed value calculated using the linear transfer characteristic Gp (s) is corrected by the motor rotation speed correction value calculated using the nonlinear transfer characteristic model 710. By correcting the first motor rotational speed estimated value in this way, the gear back having a non-linear characteristic is obtained from the first motor rotational speed estimated value calculated using Gp (s) having a linear transfer characteristic. The dead zone characteristics of the rush are compensated. Thereby, even if the section where the vehicle straddles the gear backlash section occurs, the motor rotation speed can be appropriately estimated from the third torque target value Tm3 ^* .

  However, the non-linear transfer characteristic model 710 is not limited to the above-described configuration, and includes a limiter 801 (see FIG. 8) included in the drive shaft torsion angle estimator 702 and a control block 704 without using the limiter 703. Also good. In that case, the drive shaft torsion angle estimated value limit value output from the limiter 801 is directly input to the control block 704 without going through the limiter 703.

  The subtractor 706 calculates a difference between the motor rotation speed ωm and the second motor rotation speed estimated value, and calculates a motor rotation speed deviation.

  The control block 707 has a function as a filter composed of a low-pass filter H (s) and an inverse system of the transfer characteristic Gr (s) configured based on the following equation (17). Is subjected to filtering processing to calculate a disturbance torque estimated value.

The transfer characteristic Gr (s) is a vehicle response used when the vibration suppression control computing unit 505 shown in FIG. 5 is used in the calculation of the third torque target value Tm3 ^* . Gr (s) is expressed by the following equation (17) by Gp (s) expressed by the above equation (13) and the vibration suppression control algorithm constituting the vibration suppression control computing unit 505.

However, ζ _r in the equation (17) represents a reference damping coefficient of the drive shaft torsional vibration system.

Note that if the vibration suppression control is not used in the calculation of the third torque target value Tm3 ^* , it is not necessary to consider the interference with the vibration suppression control. Therefore, the control block 707 replaces the transfer characteristic Gr (s). The transfer characteristic Gp (s) represented by the above equation (13) is used. When the vibration suppression control is not used together, the output of the torque comparator 504 shown in FIG. 5 is set as the third torque target value Tm3 ^* .

  By calculating the estimated disturbance torque by the above processing, the estimated disturbance torque can be calculated by compensating for the deadband characteristics of the gear backlash even in a scene where the vehicle straddles the gear backlash just before stopping on the uphill road. Therefore, the fluctuation of the estimated disturbance torque can be suppressed and the vehicle can be stopped smoothly.

As described above, the control device for the electric vehicle according to the first embodiment sets the motor torque command value based on the vehicle information, and realizes the control method for the electric vehicle that controls the torque of the motor 4 connected to the drive wheels 9a and 9b. The device detects the accelerator operation amount of the driver, detects a vehicle parameter proportional to the motor rotational speed ωm, inputs the third torque target value Tm3 ^* , and the motor torque is not transmitted to the drive shaft of the vehicle A disturbance torque estimated value acting on the motor is estimated using a nonlinear transfer characteristic model 710 from the motor torque including the dead band characteristic of the gear backlash to the rotational speed of the motor 4. When the accelerator operation amount decreases and the electric vehicle is about to stop, the torque of the motor 4 is converged to disturbance torque as the vehicle parameters decrease.

  This makes it possible to accurately calculate the disturbance torque estimate even when the motor torque changes from negative to positive just before stopping on an uphill road, for example, due to the effects of modeling errors between the vehicle model and the actual vehicle. The fluctuation of the disturbance torque estimated value can be suppressed, and the acceleration shock caused by the fluctuation of the disturbance torque estimated value can be suppressed.

Further, the control device for the electric vehicle according to the first embodiment calculates the drive shaft torsion angle estimated value θd based on the third torque target value Tm3 ^* as the motor torque command value, and the third torque target value Tm3 ^*. To calculate the first motor rotational speed estimated value using the linear transfer characteristic model Gp (s) from the motor torque not including the dead band characteristic to the rotational speed of the motor 4 to estimate the drive shaft torsion angle. Using a nonlinear transfer characteristic model 710 composed of a limiter 703 that limits the upper and lower limit values by inputting the value θd and a backlash compensation filter Gps (s) that compensates for gear backlash, A correction value is calculated. Then, a second motor rotational speed deviation is calculated based on the second motor rotational speed estimated value obtained by correcting the first motor rotational speed estimated value by the motor rotational speed correction value and the motor rotational speed ωm. Then, a disturbance torque is obtained by subjecting the motor rotational speed deviation to a filtering process using a filter composed of an inverse model 1 / Gp (s) of the transfer characteristic Gp (s) and a low-pass filter H (s). Calculate an estimate.

  As a result, the deadband characteristic of the gear backlash can be simulated by a nonlinear transfer characteristic model composed of Gps (s) and a saturation function that functions as a linear backlash compensation filter. Thus, there is no need to switch the control when there is no backlash, and the deadband characteristics of the gear backlash can be compensated. That is, the gear backlash can be compensated only by the arithmetic expression without requiring a complicated conditional branch according to the vehicle state.

In addition, the control apparatus for the electric vehicle according to the first embodiment performs the vibration suppression control (vibration suppression control calculator 505) for suppressing the torsional vibration of the driving force transmission system from the motor torque to the motor rotation speed ωm. the desired torque value Tm3 ^* is calculated, if the disturbance torque is estimated on the basis of the third torque target value Tm3 ^* are torsion drive shaft on the basis of the third torque target value as a motor torque command Tm3 ^* An angle estimated value is calculated, a third torque target value Tm3 ^* is input, and a linear transfer characteristic model Gp (s) from the motor torque not including the dead band characteristic to the rotational speed of the motor 4 is used to The estimated rotational speed of the motor is calculated, the estimated drive shaft torsion angle θd is input, the limiter 703 that limits the upper and lower limit values, and the backlash compensation filter Gps ( ) And using the constructed nonlinear transfer characteristic model 710 exits, and calculates the motor rotational speed compensation value. Then, a second motor rotational speed deviation is calculated based on the second motor rotational speed estimated value obtained by correcting the first motor rotational speed estimated value by the motor rotational speed correction value and the motor rotational speed ωm. Then, an inverse model 1 / of the transfer characteristic Gp (s) derived from the transfer characteristic Gp (s) and an algorithm of damping control for suppressing torsional vibration of the driving force transmission system from the motor torque command value to the motor rotation speed. A disturbance torque is estimated by performing a filtering process using a filter composed of Gr (s) and a low-pass filter H (s).

Thereby, in the calculation of the disturbance torque estimated value, since the vibration suppression control in the calculation of the third torque target value Tm3 ^* is taken into consideration, the disturbance torque estimated value is appropriately estimated without interfering with the vibration suppression control. be able to.

  Further, according to the control apparatus for an electric vehicle of the first embodiment, the upper and lower limit values of the limiters 703 and 801 are calculated based on the dead band width of the gear backlash. Thereby, the compensation amount for the gear backlash can be calculated.

  Further, according to the control apparatus for an electric vehicle according to the first embodiment, the estimated value of the drive shaft torsion angle is input from the motor torque command value and includes the dead band characteristic of gear backlash to the drive shaft torsion angular velocity. It is calculated using a vehicle model 810 in which the characteristics of the above are modeled. Thereby, the estimated value of the drive shaft torsion angle can be calculated without using a sensor or the like that detects the rotational speed of the drive wheels 9a and 9b.

-Second Embodiment-
The second embodiment is different from the first embodiment in the configuration of the disturbance torque estimator 502 described with reference to FIG. Hereinafter, details of the disturbance torque estimator 502 in the second embodiment will be described with reference to FIGS. 9 and 10.

FIG. 9 is a block diagram for explaining a method of calculating the disturbance torque estimated value _Td based on the motor rotation speed ωm and the third torque target value Tm3 ^* . The disturbance torque estimator 502 of this embodiment includes a control block 901, a drive shaft torsion angle estimator 902, a non-linear transfer characteristic model 910 including a limiter 903 and a control block 904, an adder 905, and a subtraction. And a control block 907.

The control block 901 functions as a filter having a linear transfer characteristic Gp (s) represented by the above equation (13), and performs a filtering process on the third torque target value Tm3 ^* . Thus, a first motor rotational speed estimated value is calculated. The calculated first motor rotation speed estimation value is output to adder 905.

The drive shaft torsion angle estimator 902 calculates the drive shaft torsion angle estimated value θ _d based on the third torque target value Tm3 ^* and the disturbance torque estimated value. Details of the drive shaft torsion angle estimator 902 will be described with reference to FIG.

FIG. 10 is a block diagram for explaining a method of calculating the drive shaft torsion angle estimated value θ _d based on the third torque target value Tm3 ^* and the disturbance torque estimated value. Hereinafter, a specific process performed to calculate the drive shaft torsion angle estimated value θ _d will be described.

For the equations of motion (1) to (6) expressing the dead zone due to gear backlash by the difference between the linear function and the saturation function, the vehicle body driving force disturbance F _dv which mainly shows gradient disturbance, brake braking, rolling friction, etc. When the driving wheel disturbance F _dw indicating the disturbance is considered as a disturbance acting on the vehicle, the equation of motion of the vehicle is expressed by the following equations (18) to (23).

However, F _dv in Expression (19) represents a vehicle body driving force disturbance, and F _dw in Expression (20) represents driving wheel disturbance for two wheels.

Expressions (18) to (23) are subjected to Laplace transform to obtain a transfer characteristic from the motor torque command value T _m to the motor rotational speed ω _{m in} consideration of the vehicle body driving force disturbance F _dv and the driving wheel disturbance F _dw. And expressed by the following equation (24).

  However, the functions, Gp (s), Gps (S), Gdw1 (s), and Gdv1 (2) in Expression (24) are respectively expressed by Expressions (25) to (28) below.

  However, d11 in Formula (27) and d10 in Formula (28) are as the following Formula (29).

  From the formulas (24), (27), and (28), when the term relating to the disturbance torque is arranged as d, the following formula (30) is obtained.

  Next, the drive shaft torsion angle θ is calculated. When formulas (18) to (23) are Laplace transformed to calculate a drive function of the drive shaft torsion angle, it is expressed by the following formula (31).

  However, d21 and d20 in Formula (31) are as the following Formula (32).

  Further, from Expression (30), Expression (31) can be modified as the following Expression (33) by replacing the term relating to the disturbance torque with d.

  Gd ′ (s) in the equation (33) is as the following equation (34).

Equation (34) is a so-called non-proper transfer function in which the numerator order (third order) is larger than the denominator order (first order). Therefore, in order to eliminate non-properity, a process of applying a low-pass filter G _L (s) = ω _n ² / (s ² + 2ω _n s + ω _n ² ) to Gd ′ (s) is performed as follows: As shown in 35), a third-order / third-order proper transfer function is constructed.

However, ω _n is a cutoff frequency of the low-pass filter G _L (s).

  From the equations (21), (33), (35), the following equation (36) can be obtained.

And the block diagram of FIG. 10 is derived | led-out from Formula (36). FIG. 10 is a block diagram showing a vehicle model 1010 that models the characteristics from the motor torque to the drive shaft torsion angle, including the dead band characteristics of the gear backlash, and the estimated disturbance torque input to the vehicle model 1010. Is. Accordingly, the drive shaft torsion angle estimator 902 can calculate the drive shaft torsion angle estimated value θd based on the third torque target value Tm3 ^* and the disturbance torque estimated value.

  Returning to FIG. 9, the description will be continued. The drive shaft torsion angle estimated value output from the drive shaft torsion angle estimator 902 is input to the nonlinear transfer characteristic model 910. The transfer characteristic model 910 includes a limiter 903 and a control block 904 having a transfer characteristic of Gps (s) expressed by the above equation (10).

In limiter 903, based on the equation (7), from the drive shaft estimated torsion angle value theta _d, estimated torsion angle value limits the drive shaft is calculated. The calculated value is output to the control block 904.

  The control block 904 has a function as a filter having a transfer characteristic of Gps (s) expressed by the above formula (10), and functions as a gear backlash compensation filter. The control block 904 calculates a motor rotation speed correction value for compensating for the dead band characteristic of the gear backlash based on the drive shaft torsion angle estimated value limit value that is an output from the limiter 903.

  The adder 905 adds the first motor rotation speed estimated value that is the output of the control block 901 having a linear transfer characteristic and the motor rotation speed correction value that is the output of the transfer characteristic model 910 having a nonlinear transfer characteristic. Then, a second estimated motor rotation speed value is calculated.

  Thus, the first motor rotation speed estimated value calculated using the transfer characteristic Gp (s) having a linear transfer characteristic is corrected by the motor rotation speed correction value calculated using the nonlinear transfer characteristic model 910. Is done. By correcting the first motor rotational speed estimated value in this way, the gear having nonlinear characteristics from the first motor rotational speed estimated value calculated using Gp (s) having linear transfer characteristics. Backlash deadband characteristics are compensated.

Further, as indicated by the addition of Gd (s) · d in equation (36), the disturbance torque estimated value is fed back to the drive shaft torsion angle estimator 902. As a result, the vehicle model 1010 is corrected with the estimated disturbance torque value, and an error in the drive shaft torsion angle caused by a disturbance such as a gradient can be compensated. As a result, the drive shaft torsion angle estimated value can be estimated more accurately, so that even if the vehicle straddles the gear backlash section, the third torque target value Tm3 ^* and the disturbance torque estimated value are Based on this, the motor rotation speed can be accurately estimated.

  However, the nonlinear transfer characteristic model 910 is not limited to the above-described configuration, and may be configured by the limiter 1001 of FIG. 10 and the control block 904 without using the limiter 903. In that case, the drive shaft torsion angle estimated value limit value output from the limiter 1001 is directly output to the control block 904 without going through the limiter 903.

The subtractor 906 calculates a difference between the motor rotation speed ω _m and the second motor rotation speed estimated value to calculate a motor rotation speed deviation.

  The control block 907 functions as a filter having a transfer characteristic of H (s) / Gp (s), and calculates an estimated disturbance torque value by performing a filtering process on the motor rotation speed deviation.

  As described above, the transfer characteristic Gp (s) is a filter having a linear transfer characteristic represented by the above equation (13). The low-pass filter H (s) is set so that the difference between the denominator order and the numerator order of the low-pass filter H (s) is equal to or greater than the difference between the denominator order and the numerator order of the transfer characteristic Gp (s). However, in the present embodiment, the motor torque command is applied by applying damping control (see FIG. 5, damping control calculator 505) that suppresses torsional vibration of the driving force transmission system from the motor torque to the motor rotation speed. A value has been calculated. For this reason, the cutoff frequency of the low-pass filter H (s) is set to a value smaller than the natural frequency of the drive shaft torsional vibration system. Thereby, it is possible to appropriately estimate the disturbance torque estimated value in which the dead band characteristic of the gear backlash is compensated without interfering with the vibration suppression control.

  By calculating the estimated disturbance torque value by the above processing, the fluctuation of the estimated disturbance torque value can be suppressed and the vehicle can be stopped smoothly even when the vehicle straddles the gear backlash just before stopping on the uphill road. .

As described above, the control device for an electric vehicle according to the second embodiment performs the vibration suppression control (vibration suppression control calculator 505) for suppressing the torsional vibration of the driving force transmission system from the motor torque to the motor rotation speed ωm. the calculated torque target value Tm3 ^*, if the disturbance torque is estimated on the basis of the third torque target value Tm3 ^* is the cut-off frequency of the low pass filter H (s), the torsional vibration of the drive force transmission system Set lower than the natural frequency.

Thereby, the disturbance torque estimated value can be appropriately estimated without interfering with the vibration suppression control related to the calculation of the third torque target value Tm3 ^* .

  Further, according to the control apparatus for an electric vehicle of the second embodiment, the vehicle model 1010 used for calculating the estimated drive shaft torsion angle is corrected according to the estimated disturbance torque value. As a result, when estimating the drive shaft torsion angle, it becomes possible to compensate for the estimation error of the drive shaft torsion angle caused by disturbance such as a gradient, and the drive shaft torsion angle can be accurately estimated. Can be calculated more accurately.

  Here, in the scene where the vehicle performs stop control on the uphill road, the control result when the first embodiment and the second embodiment described above are applied to the electric vehicle is based on the comparison with the control result according to the conventional example. I will explain.

  FIG. 11 is a time chart when the vehicle performs stop control on the uphill road. FIG. 11 shows the motor rotation speed, the motor torque command value, the vehicle longitudinal acceleration, and the disturbance torque estimated value in order from the top. FIG. 11A shows a conventional example, FIG. 11B shows a control result according to the first embodiment, and FIG. 11C shows a control result according to the second embodiment.

At time t0, the vehicle decelerates with the first torque target value Tm1 ^* calculated in step S202 of FIG.

At time t1, the torque comparator 504 shown in FIG. 5 determines that the vehicle is about to stop when the second torque target value Tm2 ^* exceeds the first torque target value Tm1 ^* , and the final torque target value is the first torque target value. The torque target value 3 is switched from the first torque target value Tm1 ^* to the second torque target value Tm2 ^* .

  Immediately before time t2, since the motor torque command value changes from negative to positive, a section over the gear backlash occurs.

  At this time, in the control according to the conventional example (FIG. 11A), the disturbance torque estimation value is calculated using the linear transfer characteristic Gp (s), and therefore the dead band characteristic of the gear backlash having a non-linear characteristic is appropriately set. Therefore, a modeling error occurs between the vehicle model constituted by the transfer characteristic Gp (s) and the actual vehicle. Therefore, the disturbance torque estimated value fluctuates in a vibrational manner. As a result, the motor torque command value fluctuates in accordance with fluctuations in the estimated disturbance torque value, and an acceleration shock accompanying vibration of the vehicle longitudinal acceleration occurs.

  On the other hand, in the control according to the first embodiment (FIG. 11B), the disturbance torque estimation value is calculated using a nonlinear transfer characteristic model 710 composed of the limiter 703 and the transfer characteristic Gps (s). The dead band characteristic of the gear backlash is compensated, and the influence of the modeling error between the vehicle model constituted by the transfer characteristic Gp (s) and the actual vehicle is reduced. As a result, since the fluctuation of the estimated disturbance torque value is reduced, the fluctuation of the motor torque command value is also reduced, so that the vibration of the vehicle longitudinal acceleration can be suppressed.

  In the control according to the second embodiment (FIG. 11C), in addition to using the nonlinear transfer characteristic model 910 including the limiter 903 and the transfer characteristic Gps (s), the drive shaft torsion angle estimator 902 is used. The estimated value of the drive shaft torsion angle is fed back to compensate for the error of the drive shaft torsion angle caused by the gradient disturbance. Then, a disturbance torque estimated value is calculated based on this drive shaft torsion angle estimated value. For this reason, the influence of the modeling error between the vehicle model constituted by the transfer characteristic Gp (s) and the actual vehicle can be completely compensated. As a result, fluctuations in the estimated disturbance torque value are suppressed and fluctuations in the motor torque command value are also suppressed, so that a smooth stop without vibration of the vehicle longitudinal acceleration can be realized.

  At time t3, the motor torque command value asymptotically converges to the disturbance torque estimated value and the motor rotation speed to zero, and the vehicle stops smoothly without acceleration vibration.

  And after time t3, a stop state is hold | maintained.

  As described above, by applying the present invention exemplified in the first embodiment and the second embodiment to an electric vehicle, the vehicle can be smoothly decelerated or stopped even in a scene where the vehicle straddles a gear backlash scene. Can be made.

The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. For example, in the above description, when the accelerator operation amount decreases or becomes zero and the electric vehicle is about to stop, the motor torque command value Tm ^* is reduced to the disturbance torque estimated value Td (or zero) as the rotational speed of the motor 4 decreases. ). However, since the speed parameters such as the wheel speed, the vehicle body speed, and the rotational speed of the drive shaft are proportional to the rotational speed of the electric motor 4, the motor torque command value is reduced with a decrease in the speed parameter proportional to the rotational speed of the electric motor 4. You may make it converge Tm ^* to disturbance torque estimated value Td (or zero).

2. Motor controller (disturbance torque estimation unit, motor torque control unit)
4 ... motor 6 ... rotation sensor (vehicle parameter detection unit)
8 ... Drive shaft 9a, 9b ... Drive wheel

Claims (8)

In a control method for an electric vehicle that sets a motor torque command value based on vehicle information and controls the torque of a motor connected to a drive wheel,
Detects the amount of driver's accelerator operation,
Detecting a vehicle parameter proportional to the rotational speed of the motor;
The motor torque command value is input, and the motor torque is applied to the motor using a nonlinear transfer characteristic model from the motor torque including the dead band characteristic of the gear backlash to which the motor torque is not transmitted to the drive shaft of the vehicle to the rotation speed of the motor. The disturbance torque to be
When the accelerator operation amount is reduced and the electric vehicle is about to stop, the torque of the motor is converged to the disturbance torque as the vehicle parameter decreases,
Control method of electric vehicle. Calculate a drive shaft torsion angle estimated value based on the motor torque command value,
The motor torque command value is input, and a motor rotation speed estimated value is calculated using a linear transfer characteristic model Gp (s) from the motor torque not including the dead band characteristic to the rotation speed of the motor,
Using the nonlinear transfer characteristic model configured by inputting the estimated value of the drive shaft torsion angle and limiting the upper and lower limit values and the backlash compensation filter Gps (s) for compensating the gear backlash. To calculate the motor rotation speed correction value,
Based on a corrected motor rotational speed estimated value obtained by correcting the motor rotational speed estimated value by the motor rotational speed correction value and a detected value of the rotational speed of the motor, a motor rotational speed deviation is calculated,
The motor rotation speed deviation is subjected to a filtering process using a filter composed of an inverse model 1 / Gp (s) of the transfer characteristic model Gp (s) and a low-pass filter H (s). Calculate the disturbance torque,
The method for controlling an electric vehicle according to claim 1. When the motor torque command value is calculated by performing vibration suppression control that suppresses the torsional vibration of the driving force transmission system from the motor torque to the motor rotation speed, and the disturbance torque is estimated based on the motor torque command value Is
Calculate a drive shaft torsion angle estimated value based on the motor torque command value,
The motor torque command value is input, and a motor rotation speed estimation value is calculated using a linear transfer characteristic model Gp (s) from the motor torque command value not including the dead band characteristic to the rotation speed of the motor,
Using the nonlinear transfer characteristic model configured by inputting the estimated value of the drive shaft torsion angle and limiting the upper and lower limit values and the backlash compensation filter Gps (s) for compensating the gear backlash. To calculate the motor rotation speed correction value,
Based on a corrected motor rotational speed estimated value obtained by correcting the motor rotational speed estimated value by the motor rotational speed correction value and a detected value of the rotational speed of the motor, a motor rotational speed deviation is calculated,
Transfer characteristics derived from the transfer characteristic model Gp (s) and a damping control algorithm for suppressing torsional vibration of the driving force transmission system from the motor torque command value to the motor rotation speed with respect to the motor rotation speed deviation. Estimating the disturbance torque by applying a filtering process using a filter composed of an inverse model 1 / Gr (s) of Gr (s) and a low-pass filter H (s);
The method for controlling an electric vehicle according to claim 1. When the motor torque command value is calculated by performing vibration suppression control that suppresses the torsional vibration of the driving force transmission system from the motor torque to the motor rotation speed, and the disturbance torque is estimated based on the motor torque command value Is
A cutoff frequency of the low-pass filter H (s) is set lower than a natural frequency of torsional vibration of the driving force transmission system;
The method for controlling an electric vehicle according to claim 2. The upper and lower limit values of the limiter are calculated based on the dead band width of the gear backlash.
The control method of the electric vehicle of any one of Claim 2 to 4. The drive shaft torsion angle estimated value is calculated using a vehicle model that inputs the motor torque command value and models the characteristics from the motor torque to the drive shaft torsion angle, including the dead band characteristics of the gear backlash. The
The control method of the electric vehicle of any one of Claim 2 to 5. The vehicle model used for calculating the drive shaft torsion angle estimated value is corrected according to the disturbance torque.
The method for controlling an electric vehicle according to claim 6. In a control device for an electric vehicle that sets a motor torque command value based on vehicle information and controls the torque of a motor connected to a drive wheel,
An accelerator operation amount detector for detecting the driver's accelerator operation amount;
A vehicle parameter detector for detecting a vehicle parameter proportional to the rotational speed of the motor;
The motor torque command value is inputted, and the motor torque is not transmitted to the drive shaft of the vehicle. A disturbance torque estimation unit for estimating the disturbance torque to be
A motor torque control unit for converging the torque of the motor to the disturbance torque as the vehicle parameter decreases when the accelerator operation amount decreases and the electric vehicle is about to stop;
Control device for electric vehicle.