JP6711064B2 - 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, the motor rotation speed detection means and the torque command value calculation means are provided, and the torque command value is adjusted as the detected value of the motor rotation speed decreases, and the motor torque is converged to a disturbance torque estimated value that is approximately a gradient resistance. A control device for an electric vehicle that executes control is known (see Patent Document 1). The control device for the electric vehicle performs the stop vibration control and the vibration suppression control that suppresses the torsional vibration of the driving force transmission system in combination to execute the acceleration vibration control regardless of the flat road, the uphill road, and the downhill road. It is possible to realize smooth deceleration just before the vehicle is stopped and to maintain the stopped state.

JP, 2005-133799, A

By the way, in the above-mentioned stop control, by configuring the feedback control system of the motor rotation speed detection value, even if the motor rotation speed detection value vibrates due to the influence of disturbance, the torque command value is suppressed so as to suppress the vibration. By calculating, the influence of the disturbance generated in the driving force transmission system is suppressed.

However, when the motor rotation speed detection and the torque command value calculation are performed by different controllers, the phase of the vibration acquired by the torque command value calculation means via the feedback control system is affected by the communication delay between the controllers. Will be misaligned. For this reason, the disturbance suppression effect by calculating the torque command value using the motor rotation speed feedback control system is reduced, and, for example, an acceleration shock occurs in a scene crossing a gear backlash during stop control on an uphill road. There is a fear.

It is an object of the present invention to provide a technique capable of suppressing the reduction of the disturbance suppression effect due to the influence of the communication delay between the controllers even when the stop control is executed using a plurality of controllers.

A control method for an electric vehicle according to the present invention includes a vehicle control controller that calculates a torque command value according to an accelerator operation amount by a driver, and a motor controller that controls a motor based on the torque command value. A speed parameter detection step of detecting a motor rotation speed or a speed parameter proportional to the motor rotation speed, a disturbance torque estimation step of estimating a disturbance torque acting on the motor, and a torque command calculated by the vehicle controller. The value is input to the motor controller, and the damping control that suppresses the torsional vibration that occurs in the driving force transmission system of the electric vehicle is performed by using the feedback control system that feeds back the motor rotation speed or speed parameter to the torque command value. The vibration control step for calculating the final torque command value, the motor control step for controlling the motor in accordance with the final torque command value, and when the electric vehicle is on the verge of stopping, the torque command value is disturbed as the motor rotation speed or speed parameter decreases. A stop control determination step of determining whether or not stop control for converging to torque is being executed. When it is determined in the stop control determination step that the stop control is being executed, the feedback gain of the feedback control system is made larger than that in the case where it is determined that the stop control is not being executed in the motor controller.

According to the present invention, the response of the motor rotation speed feedback relating to the vibration suppression control can be accelerated by increasing the feedback gain of the vibration suppression control that is also used in the stop control only when the vehicle is in the stop control. Therefore, the disturbance suppression effect during the stop control can be improved.

FIG. 1 is a block diagram showing 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 executed by the control device for the electric vehicle according to the first embodiment. FIG. 3 is a diagram showing an example of an accelerator opening-torque table. FIG. 4 is a diagram for explaining a driving force transmission system of a vehicle. FIG. 5 is a block diagram for explaining the stop control process. FIG. 6 is a diagram for explaining the details of the motor rotation speed F/B torque setting device shown in FIG. FIG. 7 is a diagram for explaining the details of the disturbance torque estimation value unit shown in FIG. FIG. 8 is a block diagram for explaining the vibration suppression control process. FIG. 9 is a diagram for explaining the frequency characteristic of the bandpass filter H ₂ (s). FIG. 10 is a diagram for explaining a control result by the control device for the electric vehicle according to the first embodiment. FIG. 11 is an example of a vibration suppression control feedback gain-motor rotation speed table used in the control device for the electric vehicle according to the second embodiment. FIG. 12 is an example of a disturbance torque estimated value-motor rotation speed threshold value table used in the control device for the electric vehicle according to the second 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 electric vehicle is a vehicle that includes an electric motor as a part or all of a drive source of the vehicle and can travel by the driving force of the electric motor, and includes an electric vehicle and a hybrid vehicle.

The motor controller 2 is a controller that controls the electric motor 4 (hereinafter, simply referred to as the motor 4). The motor controller 2 includes a vehicle speed V, a rotor phase α of the motor 4, drive wheel angular velocities of the drive wheels 9a and 9b, signals indicating vehicle states such as currents iu, iv, and iw of the motor 4, and vehicle control described later. The torque command value calculated by the controller 10 is input as a digital signal. The motor controller 2 generates a PWM signal for controlling the motor 4 based on the input signal. Further, a drive signal for the inverter 3 is generated according to the generated PWM signal.

The vehicle control controller 10 is a controller that controls the driving force of the vehicle. The accelerator opening θ and the motor rotation speed ωm detected by the motor controller 2 are input to the vehicle controller 10 via a communication unit such as CAN. The vehicle controller 10 calculates a torque command value for causing the motor 4 to generate a desired torque based on the input signal. The calculated torque command value is output to the motor controller 2 via communication means such as CAN.

The inverter 3 converts a direct current supplied from the battery 1 into an 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 motor 4.

The 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 9a and 9b via the speed reducer 5 and the driving shaft 8. Further, the motor 4 collects the kinetic energy of the vehicle as electric energy by generating a regenerative driving force when the motor 4 rotates while being rotated by the drive wheels 9a and 9b when 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, iw flowing in the motor 4. However, since the sum of the three-phase alternating currents iu, iv, and iw is 0, an arbitrary two-phase current may be detected and the remaining one-phase current may be calculated.

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

FIG. 2 is a flowchart showing a flow of processing performed by the motor controller 2 or the vehicle controller 10. The processing from step S201 to step S206 is constantly executed at regular intervals while the vehicle system is activated.

In step S201, a signal indicating the vehicle state is input to the motor controller 2 or the vehicle controller 10. Here, the accelerator opening degree θ (%) is input to the vehicle controller 10, and the rotor phase α (rad) of the motor 4, the drive wheel rotation angle (rad) of the drive wheels 9a and 9b, and the rotation speed Nm of the motor 4 are input. (Rpm), the three-phase AC currents iu, iv, iw flowing through the motor 4, and the DC voltage value Vdc (V) of the battery 1 are input to the motor controller 2.

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 a vehicle speed v (m/s) by multiplying the rotor mechanical angular velocity ωm by the tire radius r and dividing by the gear ratio of the final gear to obtain a unit by multiplying by 3600/1000. After conversion, the vehicle speed V (km/h) is obtained.

The accelerator opening degree θ (%) is obtained from an accelerator opening degree sensor (not shown) or by communication from another controller.

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 speed ω (electrical angle) by the number p of pole pairs of the motor to obtain the motor rotation speed ωm (rad/s) which is the mechanical angular speed of the motor 4. , And 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 currents iu, iv, iw(A) flowing in the motor 4 are acquired from the current sensor 7.

The DC voltage 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 vehicle controller 10 calculates the first torque target value Tm1 ^* as the basic target torque. Specifically, the vehicle control controller 10 refers to the accelerator opening degree-torque table shown in FIG. 3 based on the accelerator opening degree θ and the motor rotation speed ωm input in step S201 to determine the first The target torque value Tm1 ^* is calculated. However, the accelerator opening-torque table is an example, and is not limited to the one shown in FIG.

In step S203, the motor controller 2 and the vehicle controller 10 perform stop control processing. Specifically, the motor controller 2 detects the motor rotation speed, and transmits the detected motor rotation speed to the vehicle control controller 10. The vehicle controller 10 determines whether or not the vehicle is on the verge of stopping, and if it is not on the verge of stopping, sets the first torque target value Tm1 ^* calculated in step S202 to the third torque target value Tm3 ^* and stops the vehicle ^. In the case of just before, the second torque target value Tm2 ^* is set to the third torque target value Tm3 ^* . The second torque target value Tm2 ^* converges to the disturbance torque command value Td as the motor rotation speed acquired from the motor controller 2 decreases. The torque target value Tm2 ^* is positive torque on an uphill road, negative torque on a downhill road, and flat. It is almost zero on the road. The calculated third torque target value Tm3 ^* is transmitted to the motor controller 2 via a communication unit such as CAN, and is set as a torque command value for causing the motor 4 to generate a desired torque. As a result, the stopped state can be maintained regardless of the slope of the road surface. Details of the stop control process will be described later.

In step S204, the motor controller 2 performs the vibration suppression control process. Specifically, based on the third torque target value Tm3 ^* set in step S203 and the motor rotation speed ωm, the drive force transmission system vibration (drive shaft) can be performed without sacrificing the drive shaft torque response. The sixth torque target value Tm6 ^* is set as the final torque command value for suppressing the torsional vibration of 8). Details of the vibration suppression control calculation processing for setting the sixth torque target value Tm6 ^* will be described later.

In step S205, the motor controller 2 determines the d-axis current target value id ^* , the q-axis current based on the sixth torque target value Tm6 ^* , the motor rotation speed ωm, and the DC voltage value V _dc calculated in step S204. Find the target value iq ^* . For example, by preparing in advance a table that defines the relationship between the motor torque command value, the motor rotation speed, the DC voltage value, and the d-axis current target value and the 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 S206, the motor controller 2 performs current control for matching 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. .. Therefore, 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, 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. In addition, you may make it add the non-interference voltage required in order to cancel the interference voltage between dq orthogonal coordinate axes with respect to the calculated d-axis and q-axis voltage command values vd and vq.

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

Hereinafter, details of the stop control process executed in step S203 in the control device for the electric vehicle according to the embodiment will be described.

<Stop control>
First, the transfer characteristic G _p (s) from the motor torque Tm to the motor rotation speed ωm of the control device for an electric vehicle according to the present embodiment will be described. The transfer characteristic Gp(s) is used as a vehicle model that models the driving force transfer system of the vehicle in the stop control process including the estimation of the disturbance torque.

FIG. 4 is a diagram in which the driving force transmission system of the vehicle is modeled, and each parameter in the diagram is as shown below.
J _m : Inertia of motor J _w : Inertia of drive wheel M: Weight of vehicle K _d : Torsional rigidity of drive system K _t : Coefficient of friction between tire and road surface N: Overall gear ratio r: Tire load radius ω _m : Motor rotation speed T _m ^* : Motor torque command value T _d : Torque of driving wheel F: Force applied to vehicle V: Vehicle speed ω _w : Angular speed of driving wheel Then, from FIG. 4, derive the following equation of motion. You can

When the transfer characteristic Gp(s) from the motor torque Tm to the motor rotation speed ωm is obtained based on the equations of motion shown by the equations (1) to (5), it is expressed by the following equation (6).

However, a ₃ , a ₂ , a ₁ , a 0, b ₃ , b ₂ , b ₁ , b ₀ in the formula (6) are represented by the following formula (7).

When the poles and zeros of the transfer function shown in Expression (6) are examined, they can be approximated to the transfer function shown in the following Expression (8), and one pole and one zero point show extremely close values. This corresponds to that α and β in the following equation (8) show extremely close values.

Therefore, by performing the pole-zero cancellation (approximating to α=β) in the equation (8), Gp(s) is transmitted in the (second)/(third) as shown in the following equation (9). Configure characteristics.

Further, since the stop control according to the present embodiment also uses the vibration suppression control (feedforward compensator) of the subsequent step S204, the vehicle model Gp(s) is calculated by the following Gp(s) and the vibration suppression control algorithm. As shown in the equation (10), it can be regarded as the vehicle response Gr(s) when the damping control is applied.

Subsequently, the details of the stop control process will be described with reference to FIGS.

FIG. 5 is a block diagram for realizing the stop control process. The stop control process is transmitted from the motor controller 2 using the motor rotation speed F/B torque setting device 501, the disturbance torque estimator 502, the adder 503, and the torque comparator 504 included in the vehicle control controller 10. It is performed based on the motor rotation speed ωm. 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 motor rotation speed ωm transmitted from the motor controller 2. Details will be described with reference to FIG.

FIG. 6 is a diagram for explaining a method for calculating the motor rotation speed F/B torque Tω based on the motor rotation speed ωm. The motor rotation speed F/B torque setting unit 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 stop of the electric vehicle, and is appropriately set by, for example, experimental data or the like. The motor rotation speed F/B torque Tω is set as a torque that provides a larger braking force 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 for the motor rotation speed ωm is described. The motor rotation speed F/B torque Tω may be calculated using a regenerative torque table that defines the above, an attenuation rate table that stores the attenuation rate of the motor rotation speed ωm in advance, or the like.

The disturbance torque estimator 502 shown in FIG. 5 calculates the disturbance torque estimation value T _d based on the motor rotation speed ωm transmitted from the motor controller 2 and the third torque target value Tm3 ^* . Details of the disturbance torque estimator 502 will be described with reference to FIG. 7.

FIG. 7 is a block diagram for explaining a method of calculating the disturbance torque estimated value T _d 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 control block 702, and a subtractor 703.

The control block 701 has a function as a filter having a transfer characteristic of H ₁ (s)/Gr(s). By performing a filtering process on the motor rotation speed ωm, a first motor torque estimated value is obtained. To calculate. H ₁ (s) is a low-pass filter having a transfer characteristic such that the difference between the denominator order and the numerator order is equal to or greater than the difference between the denominator order and the numerator order of the vehicle response Gr(s) (see equation (10)). ..

The control block 702 has a function as a low-pass filter having a transfer characteristic of H ₁ (s), and performs a filtering process on the third torque target value Tm3 ^* to obtain a second motor torque estimated value. To calculate.

Then, the subtracter 703 calculates the deviation between the first motor torque estimated value and the second motor torque estimated value to calculate the disturbance torque estimated value Td which is a parameter representing the disturbance acting on the vehicle. It

The disturbance torque estimated value Td calculated as described above is estimated by the disturbance observer as shown in FIG. 7, but may be estimated by using a measuring device such as a vehicle front-rear G sensor.

Here, as the disturbance acting on the vehicle, air resistance, modeling error due to changes in vehicle mass due to the number of passengers and the loading capacity, tire rolling resistance, road surface gradient resistance, etc. can be considered. The dominant disturbance factor at the start is the gradient resistance. The disturbance factor varies depending on the operating condition, but the disturbance torque estimator 502 determines the disturbance based on the motor torque command value Tm ^* , the motor rotation speed ωm, and the transfer characteristic Gr(s) when the vibration suppression control is applied. Since the estimated torque value Td is calculated, the above-mentioned disturbance factors can be collectively estimated. As a result, it is possible to realize a smooth stop from deceleration under any driving condition.

The adder 503 shown in FIG. 5 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. By doing so, the second target torque 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 the disturbance torque estimation according to the decrease in the motor rotation speed ωm. It converges on 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 to the third torque target value Tm3 ^* . .. While the vehicle is traveling, the second target torque value Tm2 ^* is smaller than the first target torque value Tm1 ^* , and when the vehicle decelerates to the verge of stopping (the vehicle speed is equal to or lower than the predetermined vehicle speed), the first target torque value Tm1 ^* . ^Greater 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 about to stop, and sets the first torque target value Tm1 ^* to the third torque. Set as the target value Tm3 ^* . Further, 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 on the verge of stopping, and determines that the second torque target value Tm1 ^* is not the second torque target value Tm1 ^* . The target torque value Tm2 ^* is set as the third target torque value Tm3 ^* . In order to maintain the stopped state, the second torque target value Tm2 ^* converges to positive torque on an uphill road, negative torque on a downhill road, and almost zero on a flat road.

The above is the details of the stop control process. By performing such processing, it is possible to smoothly stop the vehicle and maintain the stopped state regardless of the gradient of the road surface on which the vehicle is traveling.

<Vibration suppression control>
Next, details of the vibration suppression control processing executed in step S204 according to FIG. 2 described above will be described with reference to FIG. The vibration suppression control process described below is executed by the motor controller 2.

FIG. 8 is a block diagram illustrating details of the vibration suppression control process used in this embodiment. The vibration suppression control process includes a feedforward compensator and a feedback compensator. The feedforward compensator 801 (hereinafter referred to as the F/F compensator 801) is a model Gp of the vehicle response Gr(s) shown in the above equation (10) and the torque input to the vehicle and the transfer characteristic of the rotation speed of the motor. It has a function as a filter having a transfer characteristic of Gr(s)/Gp(s) composed of an inverse system of (s). The F/F compensator 801 calculates the fourth torque target value Tm4 ^* by performing the filtering process on the third torque target value Tm3 ^* .

The control blocks 802 and 803 and the gain compensator 804 are filters used in a feedback compensator (hereinafter, feedback is referred to as F/B). The control block 802 is a filter having a transfer characteristic of Gp(s) represented by the equation (9), and the fourth torque target value Tm4 ^* described above and the output from the gain compensator 804 which will be described later are fifth. The motor rotation speed estimated value is calculated by performing a filtering process on the value obtained by adding the torque target value Tm5 ^* . Then, the subtractor 806 subtracts the detected motor rotation speed ωm from the motor rotation speed estimation value output from the control block 802. The output value from the subtractor 806 is input to the control block 803.

The control block 803 is composed of a transfer characteristic H ₂ (s) and an inverse system of the model Gp(s) of the transfer characteristic of the torque input to the vehicle and the rotation speed of the motor Gp(s). It is a filter having the following transfer characteristic, and performs filtering processing on the output from the subtractor 806. By performing the filtering process, the deviation between the motor rotation speed estimated value and the motor rotation speed ωm is converted into torque (F/B compensation torque). The torque value corresponds to the disturbance acting on the vehicle. The F/B compensation torque is output to the gain compensator 804.

The transfer characteristic H ₂ (s) will be described. H ₂ (s) becomes a feedback element that reduces only the vibration generated in the driving force transmission system when configured as a bandpass filter. By setting the frequency characteristic of the transfer characteristic H ₂ (s) forming the bandpass filter as shown in FIG. 9, the greatest damping effect can be obtained. That is, the transfer characteristic H ₂ (s) is such that the damping characteristics on the low-pass side below the frequency f _LC and on the high-pass side above the frequency f _Hc are approximately the same, and the torsional resonance frequency f _p of the drive shaft is the logarithmic axis. It is set so as to be in the vicinity of the center of the pass band on the (log scale).

For example, when the transfer characteristic H ₂ (s) is composed of a first-order high-pass filter and a first-order low-pass filter, the transfer characteristic H ₂ (s) is formed by the following expression (11).

However, τ _L =1/(2πf _HC ), f _HC =k·f _p , τ _H =1/(2πf _LC ), f _LC =f _p /k. Further, the frequency f _p is a torsional resonance frequency of the drive system, and k is an arbitrary value forming a bandpass.

The gain compensator 804 is a filter that configures the feedback gain K _FB (hereinafter simply referred to as gain K _FB ) of the F/B compensator relating to vibration suppression control, and by adjusting the value of the gain K _FB , vibration suppression is performed. The stability of the F/B compensator used in the control process or the disturbance suppression performance can be adjusted. For example, by increasing the value of the gain K _FB , it is possible to compensate for the communication delay between the motor controller 2 and the vehicle controller 10 in the feedback control system of the motor rotation speed, and improve the disturbance suppression performance. .. However, in the F/B compensator used in the vibration suppression control process, when the value of the feedback gain is increased, a high-frequency torque component may be largely output due to the influence of noise generated by the motor rotation angle and speed detection. ..

For example, a vibration component in the 25 to 150 Hz band generated while the vehicle is traveling may generate a so-called muffled sound when the vibration generated from the motor unit, the drive shaft, or the like is transmitted to the vehicle body via the mount or the like. Therefore, if the feedback gain of the F/B compensator is increased for the purpose of improving the disturbance suppression performance, the above-mentioned high-frequency torque component becomes large, and the muffled sound becomes prominent. As a result, the setting of the feedback gain has a trade-off relationship with the muffled sound, and therefore the feedback gain cannot always be set to the ideal state (feedback gain=1) regardless of the running state of the vehicle.

However, when the vehicle is in the stop control in which the vehicle is in the low speed range, the vibration component generated in the vehicle is dominated by the vibration component in the 25 to 150 Hz band or lower. Therefore, the control device for an electric vehicle according to the present invention determines whether or not the vehicle is under stop control, and when it is determined that the vehicle is under stop control, the value of the gain K _FB is other than during stop control. Change to a value greater than. As a result, the disturbance suppression effect during the stop control can be improved without increasing the high-frequency torque component that causes the muffled sound.

The determination as to whether or not the vehicle is under stop control is made based on the above-described first torque target value Tm1 ^* and second torque target value Tm2 ^* . Specifically, the torque comparator 504 is used to compare the first torque target value Tm1 ^* and the second torque target value Tm2 ^*, and the second torque target value Tm2 ^* becomes the first torque target value. When it becomes larger than the value Tm1 ^* , it is determined that the vehicle is under stop control.

The result of damping control by the control device for the electric vehicle according to the first embodiment described above will be described with reference to FIG. 10.

FIG. 10 is a comparison diagram of the control result according to the first embodiment and the control result according to the conventional technique. FIG. 10A shows the control result according to the conventional technique, and FIG. 10B shows the control result according to the first embodiment. In both drawings, the motor rotation speed, the motor torque command value, and the vehicle longitudinal acceleration are shown in order from the top.

FIG. 10 shows the control result in the scene where the vehicle executes the stop control at a gentle climbing slope.

At time t0, the first torque target value Tm1 ^* and the second torque target value Tm2 ^* are compared by the torque comparator 504 shown in FIG. 5, and the second torque target value Tm2 ^* becomes the first torque target value. When it is determined that the vehicle is about to stop at the timing when the value becomes larger than the value Tm1 ^* , the stop control is started.

From the time t0 when the stop control is started to the time t2, the motor rotation speed asymptotically converges to 0 by the stop control, and the motor torque stops at an uphill road to a positive value for maintaining the stop. Converges asymptotically. Here, when the vehicle is stopped on the uphill road by the stop control, the motor torque changes from a negative value to a positive value, and therefore the vehicle torque passes through a section that straddles the gear backlash between times t1 and t2.

At this time, according to the control result by the conventional technique (FIG. 10A), the motor rotation speed vibrates greatly when passing through the backlash section between time t1 and time t2. This is because the motor rotation speed detected by the motor controller 2 is fed back to the vehicle control controller 10, and the torque instruction value is calculated from the vehicle control controller 10 that calculates the torque instruction value based on the acquired motor rotation speed to the motor controller 2. This is due to the fact that the disturbance suppression performance due to the feedback of the motor rotation speed deteriorates due to the communication delay between the controllers related to the feedback loop at the time of outputting.

On the other hand, in the control result (FIG. 10B) according to the first embodiment, the motor rotation speed in the vibration suppression control is increased by increasing the value of the gain K _FB indicated by the gain compensator 804 in FIG. 8 during the stop control. Since the communication delay between the controllers is compensated for by increasing the feedback response of, the vibration of the motor rotation speed when passing through the backlash section between the times t1 and t2 can be reduced. In addition, the vehicle under stop control is in the low speed range, and the motor rotation speed is slower than that during non-stop control. Therefore, even if the feedback gain is increased, there is a vibration component in the 25 to 150 Hz band that causes muffled noise. It will not be significantly amplified.

As described above, the control device for the electric vehicle according to the first embodiment includes the vehicle controller 10 that calculates the torque command value according to the accelerator operation amount by the driver and the motor controller 2 that controls the motor based on the torque command value. A control device for realizing a control method for an electric vehicle, comprising: a speed parameter detection step of detecting a motor rotation speed or a speed parameter proportional to the motor rotation speed; and a disturbance torque estimation for estimating a disturbance torque acting on the motor. Steps and torque command values calculated by the vehicle controller are input to the motor controller, and a feedback control system that feeds back the motor rotation speed or speed parameter to the torque command values is used to generate the driving force transmission system of the electric vehicle. The vibration suppression control step that calculates the final torque command value with the vibration suppression control that suppresses torsional vibration, the motor control step that controls the motor according to the final torque command value, and the motor rotation speed when the electric vehicle is about to stop. Alternatively, a stop control determination step of determining whether or not stop control for converging the torque command value to the disturbance torque is being executed as the speed parameter is decreased. When it is determined in the stop control determination step that the stop control is being executed, the feedback gain of the feedback control system is made larger than that in the motor controller 2 when it is determined that the stop control is not being executed. .. As a result, even when the calculation of the torque command value and the control of the motor 4 based on the calculated torque command value are executed using separate controllers, the disturbance suppression effect of the feedback control system of the motor rotation speed can be improved. Therefore, the acceleration shock due to the gear backlash can be reduced even in the scene of crossing the gear backlash section during the stop control on the uphill road.

Further, the control device for the electric vehicle according to the first embodiment includes a first torque target value calculation step of calculating a first torque target value based on the vehicle information, and a disturbance torque estimation with a decrease in the motor rotation speed or the speed parameter. It further includes a second torque target value calculation step of calculating a second torque target value that converges to a value, and a torque target value comparison step of comparing the first torque target value and the second torque target value. .. The stop control determination step determines that the stop control is being executed when the second torque target value becomes larger than the first torque target value. As a result, the feedback gain can be changed at the timing when the stop control is executed and before the vehicle crosses the gear backlash section, so that the acceleration shock due to the gear backlash can be reliably reduced. can do.

Further, according to the control device for an electric vehicle of the first embodiment, the disturbance torque is estimated to be a positive value on an uphill road, a negative value on a downhill road, and approximately zero on a flat road. As a result, regardless of the slope of the road on which the vehicle is traveling, the vehicle can be smoothly stopped only by the motor torque and the stopped state can be maintained.

-Second Embodiment-
The control device for an electric vehicle according to the second embodiment described below is different from the first embodiment described above in that a method for determining whether or not the stop control, which is the timing for increasing the value of the gain K _FB , is started. different. Specifically, in the control device for an electric vehicle according to the second embodiment, the motor controller 2 determines whether the stop control is started according to the motor rotation speed based on the table shown in FIG. Change the value of K _FB .

FIG. 11 is a diagram showing the relationship between the value of the gain K _FB and the motor rotation speed. The horizontal axis of FIG. 11 represents the motor rotation speed, and the vertical axis represents the value of the gain K _FB . Motor rotation speeds ω _mL and ω _mH in the figure are threshold values for determining the timing of changing the value of the gain K _FB . As shown in the figure, in the present embodiment, it is determined that the stop control is started with the motor rotation speed ω _mH as the threshold value, and the value of the gain K _FB is increased over the motor rotation speed ω _mL . The motor rotation speed ω _mH is a threshold value at which it is possible to determine that the stop control can be started when the vehicle speed is in the low speed range, and is, for example, 500 rpm. The motor rotation speed ω _mL is a threshold value with which it is possible to determine that the vehicle speed has further decreased and the stop control has been started reliably, and is, for example, 200 rpm.

As described above, by determining whether or not the stop control is being performed according to the motor rotation speed, it is possible to reduce the amount of calculation involved in determining whether or not the stop control is being performed, as compared to the first embodiment. The calculation load of the software in 2 can be reduced.

Further, since the value of the motor rotation speed that starts the stop control changes according to the gradient of the road surface of the vehicle, the threshold values ω _mL and ω _{mH of the} motor rotation speed are changed according to the estimated disturbance torque value calculated during the stop control processing. May be changed.

FIG. 12 is a diagram showing the relationship between the estimated disturbance torque and the motor rotation speeds ω _mL and ω _mH . The horizontal axis of FIG. 12 represents the estimated disturbance torque value, and the vertical axis represents the motor rotation speed threshold value. The larger the estimated disturbance torque value, that is, the larger the road gradient on the uphill road, the higher the motor rotation speed when entering the backlash section during the stop control.

Therefore, in the second embodiment, as shown in FIG. 12, the motor rotation speeds ω _mL and ω _mH , which are the thresholds for measuring the timing of changing the value of the gain K _FB , are increased as the disturbance torque estimated value increases. It may be set to. As a result, even if the motor rotation speed entering the backlash section changes during the stop control according to the road surface gradient, the value of the gain K _FB can be increased before straddling the backlash section. The resulting acceleration shock can be reliably suppressed.

As described above, according to the control device for the electric vehicle of the second embodiment, the stop control determination step compares the motor rotation speed or the speed parameter with the threshold value for determining whether the vehicle is on the verge of stopping to determine the motor rotation speed. Alternatively, when the speed parameter becomes equal to or less than the threshold value, it is determined that the stop control is being executed. As a result, it is possible to reduce the calculation load for determining whether or not the stop control is being executed.

Further, according to the control device for the electric vehicle of the second embodiment, the stop control determination step changes the magnitude of the threshold value to be compared with the motor rotation speed or the speed parameter according to the gradient of the road surface on which the electric vehicle is traveling. To do. As a result, the acceleration shock due to the gear backlash can be reliably reduced regardless of the slope of the road surface on which the vehicle is traveling.

The present invention is not limited to the above embodiment. For example, the motor controller 2 may be provided with each configuration related to the disturbance torque estimation value used for the stop control or the calculation of the second torque target value Tm2 ^* . Specifically, for example, the motor controller 2 includes a motor rotation speed F/B torque setting device 501, a disturbance torque estimator 502, and an adder 503, and calculates based on the detected motor rotation speed ωm. The torque target value Tm2 ^* of 2 may be transmitted to the vehicle controller 10.

Further, in the description of the second embodiment, the determination as to whether or not the stop control has been started is performed by the motor controller 2, but may be performed by the vehicle controller 10. In that case, the vehicle controller 10 may be configured to receive from the motor controller 2 the motor rotation speed that is the threshold value for the determination.

Further, in the above description, it is assumed that the vehicle is traveling on an uphill road while straddling the gear backlash section during the stop control, but the motor torque is not limited to the uphill road during the stop control. If it changes from 0 to positive or from positive to negative over 0, there is a possibility of crossing the gear backlash section even on a flat road or a downhill road. Therefore, the control method for an electric vehicle according to the present invention, when the vehicle crosses the gear backlash section during the stop control, causes an acceleration shock due to the gear backlash regardless of the slope of the road surface on which the vehicle is traveling. It can be reduced.

2... Motor controller (speed parameter detection unit, vibration suppression control unit, stop control determination unit, motor control unit)
10... Vehicle control controller (disturbance torque estimation unit)

Claims (6)

In a control method for an electric vehicle including a vehicle control controller that calculates a torque command value according to an accelerator operation amount by a driver, and a motor controller that controls a motor based on the torque command value,
A speed parameter detecting step of detecting a motor rotation speed or a speed parameter proportional to the motor rotation speed,
A disturbance torque estimating step of estimating a disturbance torque acting on the motor,
The torque command value calculated by the vehicle controller is used as an input to the motor controller, and a feedback control system that feeds back the motor rotation speed or the speed parameter to the torque command value is used to drive a driving force transmission system for an electric vehicle. A damping control step of calculating a final torque command value that has been subjected to damping control to suppress the torsional vibration that occurs in
A motor control step of controlling the motor according to the final torque command value,
When the electric vehicle is on the verge of stopping, a stop control determination step of determining whether or not a stop control for converging the torque command value to the disturbance torque is being executed together with a decrease in the motor rotation speed or the speed parameter, and ,
When it is determined that the stop control is being executed in the stop control determining step, the feedback gain of the feedback control system is set to be higher than that when the stop control is determined to be not executed in the motor controller. Enlarge,
A method for controlling an electric vehicle, comprising: A first torque target value calculation step of calculating a first torque target value based on vehicle information;
A second torque target value calculation step of calculating a second torque target value that converges to the disturbance torque as the motor rotation speed or the speed parameter decreases.
Further comprising a torque target value comparison step of comparing the first torque target value and the second torque target value,
The stop control determination step determines that the stop control is being executed when the second torque target value becomes larger than the first torque target value.
The method for controlling an electric vehicle according to claim 1, wherein The stop control determination step compares the motor rotation speed or the speed parameter with a threshold value for determining whether the vehicle is about to stop, and when the motor rotation speed or the speed parameter is equal to or less than the threshold value, Judge that stop control is being executed,
The method for controlling an electric vehicle according to claim 1, wherein The stop control determination step changes a magnitude of the threshold value to be compared with the motor rotation speed or the speed parameter according to a gradient of a road surface on which the electric vehicle is traveling,
The method for controlling an electric vehicle according to claim 3, wherein. The disturbance torque is estimated to be a positive value on an uphill road, a negative value on a downhill road, and approximately zero on a flat road,
The control method for an electric vehicle according to any one of claims 1 to 4, characterized in that: In a control device for an electric vehicle including a vehicle controller that calculates a torque command value according to an accelerator operation amount by a driver, and a motor controller that controls a motor based on the torque command value,
A speed parameter detection unit that detects a motor rotation speed or a speed parameter proportional to the motor rotation speed,
A disturbance torque estimation unit that estimates a disturbance torque that acts on the motor;
The torque command value calculated by the vehicle controller is used as an input to the motor controller, and a feedback control system that feeds back the motor rotation speed or the speed parameter to the torque command value is used to drive a driving force transmission system for an electric vehicle. A vibration suppression control unit that calculates the final torque command value that has undergone vibration suppression control that suppresses torsional vibration that occurs in
According to the final torque command value, a motor control unit for controlling the motor,
When the electric vehicle is on the verge of stopping, a stop control determination unit that determines whether or not stop control for converging the torque command value to the disturbance torque is being performed along with a decrease in the motor rotation speed or the speed parameter, ,
When it is determined that the stop control is being performed by the stop control determination unit, the feedback gain that the feedback control system has is greater than when the stop control is determined to be not being performed by the motor controller. Enlarge,
A control device for an electric vehicle, comprising: