JP6720714B2 - 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.

Patent Document 1 discloses a vehicle vibration damping control device using a motor. This vibration suppression control device includes a feedforward compensator (Gm(s)) including a transfer characteristic (Gp(s)) of a controlled object that linearly approximates the torque response and a reference response (Gm(s)) that idealizes the torque response. /Gp(s)). In addition, a motor angular velocity estimation unit that estimates the motor angular velocity from the final torque command value using the transfer characteristic (Gp(s)) is provided. Further, a filter (H(s)/Gp(s) including an inverse characteristic of the transfer characteristic (Gp(s)) and a bandpass filter (H(s)) based on the deviation between the estimated motor angular velocity value and the detected motor angular velocity value. ) Through a feedback compensator for calculating the feedback torque.

By providing such a feedforward/feedback control system, when there is no delay element in the control system, the ideal vehicle response intended by the designer can be obtained both for the torque command value and for disturbance. To be In addition, Gp(s) of Patent Document 1 has an equation as a damping component of the torsional vibration, for example, mainly with a coefficient (Kt) relating to tire and road surface friction.

JP, 2003-9566, A

By the way, in an actual vehicle, a viscous term corresponding to the torsional angular velocity of the motor exists in the torque transmission path from the motor to the drive shaft. However, the vehicle model (Gp(s), etc.) of Patent Document 1 described above assumes a case where there is no viscous term corresponding to the torsional angular velocity of the motor, and therefore behaves differently from the actual vehicle state. Therefore, even when there is no disturbance, the estimated motor angular velocity and the detected motor angular velocity differ from each other when the torque target value changes, and unnecessary feedback torque is generated in the feedback compensator. As a result, there is a problem in that the torque response of the drive shaft overshoots when the accelerator is stepped on, causing a vehicle behavior that is uncomfortable for the driver.

Therefore, the present invention provides a control method for an electric vehicle and a control device for an electric vehicle that can suppress a vehicle behavior that is uncomfortable for a driver by reducing an overshoot of a torque response of a drive shaft of the electric vehicle. The purpose is to do.

A control method for an electric vehicle according to an aspect of the present invention calculates a torque command value based on a torque target value set based on vehicle information, and controls a torque of a motor connected to a drive wheel based on the torque command value. It is a control method of an electric vehicle. This control method includes an estimated value calculation step of inputting a torque command value to a transfer characteristic representing a relationship between a motor torque and a motor angular velocity to calculate a motor angular velocity estimated value, a motor angular velocity estimated value, and a motor angular velocity detection. And a feedback step of calculating a first feedback torque to be added to the torque command value by inputting a difference between the value and the value to a filter formed by a product of an inverse characteristic of a transfer characteristic and a bandpass filter. The motor angular velocity estimated value is calculated by adding a viscosity term generated according to the twist angular velocity of the motor to the transfer characteristic.

According to the above aspect, unnecessary feedback torque is suppressed when the torque target value changes, and overshoot of the torque response of the drive shaft is suppressed, so that a vehicle behavior that is uncomfortable for the driver can be suppressed.

FIG. 1 is a block diagram showing a system configuration of an electric vehicle including the control device for the electric vehicle according to the first embodiment. FIG. 2 is a flowchart showing the flow of processing of motor current control performed by the motor controller. FIG. 3 is a diagram showing an example of the accelerator opening-torque table. FIG. 4 is a damping control block diagram of the control device for the electric vehicle according to the first embodiment. FIG. 5 is a block diagram of a vibration suppression control FF calculation unit and a vibration suppression control FB calculation unit that form the control device for the electric vehicle of the first embodiment. FIG. 6 is a diagram modeling a driving force transmission system of an electric vehicle. FIG. 7 is a diagram showing frequency characteristics of the bandpass filter H(s). FIG. 8: is a figure which shows an example of the control effect by the control apparatus of the electric vehicle of this embodiment. FIG. 9 is a vibration suppression control block diagram which constitutes the control device for the electric vehicle of the second embodiment. FIG. 10 is a vibration damping control block diagram which constitutes a control device for an electric vehicle according to the third embodiment. FIG. 11 is a diagram showing equivalent conversion of the vibration suppression control block diagram of FIG. 10.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
<System configuration of electric vehicle>
FIG. 1 is a block diagram showing a system configuration of an electric vehicle 10 including a control device for the electric vehicle 10 according to the first embodiment. The electric vehicle 10 is a vehicle that includes a motor 18 as a part or all of a drive source of the vehicle and can travel by the driving force of the motor 18, and includes an electric vehicle and a hybrid vehicle.

Signals indicating vehicle states such as vehicle speed V, accelerator opening, rotor phase α of the motor 18, three-phase alternating currents iu, iv, iw of the motor 18 are input to the motor controller 12 (control device) as digital signals. It The motor controller 12 generates PWM signals tu, tv, tw for controlling the motor 18 based on the input signal. In addition, a drive signal for the inverter 16 is generated according to the generated PWM signals tu, tv, and tw.

The inverter 16 turns on/off two switching elements (for example, power semiconductor elements such as IGBT and MOS-FET) provided for each phase to convert a direct current supplied from the battery 14 into an alternating current. Then, a desired current is passed through the motor 18.

The motor 18 (three-phase AC motor) generates a driving force by the AC current supplied from the inverter 16, and transmits the driving force to the left and right driving wheels 24a and 24b via the speed reducer 20 and the driving shaft 22. Further, the motor 18 recovers the kinetic energy of the vehicle as electric energy by generating a regenerative driving force when the motor 18 rotates while being rotated by the drive wheels 24a and 24b during traveling of the vehicle. In this case, the inverter 16 converts the alternating current generated during the regenerative operation of the motor 18 into a direct current and supplies it to the battery 14.

The current sensor 26 detects the three-phase alternating currents iu, iv, iw flowing through the motor 18. 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 28 is, for example, a resolver or an encoder, and detects the rotor phase α of the motor 18.

<Control flow of the entire system>
FIG. 2 is a flowchart showing a flow of processing performed by the motor controller 12. The processing from step S201 to step S205 is constantly executed at regular intervals while the vehicle system is activated.

In step S201, a signal indicating the vehicle state (vehicle information) is input to the motor controller 12. Here, the vehicle speed V (km/h), the accelerator opening degree (%), and the rotor phase α (rad) of the motor 18 are input. Further, the rotation speed Nm (rpm) of the motor 18, the three-phase AC currents iu, iv, iw flowing in the motor 18, and the DC voltage value Vdc (V) of the battery 14 are input.

The vehicle speed V (km/h) is acquired by communication from a vehicle speed sensor (not shown) or another controller. Further, the motor controller 12 obtains the vehicle speed V (m/s) by multiplying the detected motor angular velocity value ωm by the tire radius r and dividing by the gear ratio N of the final gear, and by multiplying by 3600/1000. The vehicle speed V (km/h) can be obtained by unit conversion.

The accelerator opening (%) is acquired from an accelerator opening sensor (not shown) or is communicated from another controller such as a vehicle controller (not shown).

The rotor phase α(rad) of the motor 18 is acquired from the rotation sensor 28. The detected motor angular velocity ωm, which is the mechanical angular velocity of the motor 18, is obtained by dividing the rotor angular velocity ω (electrical angle) by the number p of pole pairs of the motor 18. The rotation speed Nm (rpm) of the motor 18 is obtained by multiplying the obtained motor angular velocity detection value ωm by 60/(2π). The rotor angular velocity ω is obtained by differentiating the rotor phase α.

The three-phase alternating currents iu, iv, iw(A) flowing through the motor 18 are acquired from the current sensor 26.

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 14 and the inverter 16. The DC voltage value V _dc (V) may be detected from a signal related to the power supply voltage value transmitted from a battery controller (not shown).

In step S202, the motor controller 12 sets the torque target value Tm ^* as the basic target torque. Specifically, the motor controller 12 sets the torque target value Tm ^* by referring to the accelerator opening-torque table shown in FIG. 3 based on the accelerator opening and the vehicle speed V input in step S201. .. However, the accelerator opening-torque table is an example, and is not limited to the one shown in FIG.

In step S203, the vibration suppression control calculation unit 30 (FIG. 4) performs vibration suppression control calculation processing. Specifically, the torque target value Tm ^* and the motor angular velocity detection value ωm set in step S202 are input, and the driving force transmission system vibration (twist of the drive shaft 22 is twisted without sacrificing the torque response of the drive shaft 22). Set the final torque command value Tmf ^* that suppresses vibration). Details of the vibration suppression control calculation process for setting the final torque command value Tmf ^* will be described later.

In step S204, based on the final torque command value Tmf ^* calculated in step S203, the detected motor angular velocity value ωm, and the DC voltage value V _dc , the current command value calculation unit 66 (FIG. 4) causes the d-axis current command value id. ^* , q-axis current command value iq ^* is calculated. For example, a table defining the relationship between the final torque command value Tmf*, the rotation speed Nm of the motor 18, the DC voltage value Vdc, and the d-axis current command value and the q-axis current command value is prepared in advance. Then, the d-axis current command value id ^* and the q-axis current command value iq ^* are obtained by referring to this table.

In step S205, the current control calculation unit 68 (FIG. 4) matches the d-axis current id and the q-axis current iq with the d-axis current command value id ^* and the q-axis current command value iq ^* obtained in step S204, respectively. To control the current. Therefore, first, the d-axis current id and the q-axis current iq are obtained based on the three-phase alternating currents iu, iv, iw input in step S201 and the rotor phase α of the motor 18. Then, the d-axis voltage command value vd is calculated from the deviation between the d-axis current command value id ^* and the d-axis current id, and the q-axis voltage command value vq is calculated from the deviation between the q-axis current command value iq ^* and the q-axis current iq. To calculate. The non-interference voltage required to cancel the interference voltage between the dq orthogonal coordinate axes may be added to the calculated d-axis voltage command value vd and the q-axis voltage command value vq.

Next, three-phase AC voltage command values vu, vv, vw are obtained from the d-axis voltage command value vd, the q-axis voltage command value vq, and the rotor phase α of the motor 18. Then, the PWM signals tu(%), tv(%), 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 16 by the PWM signals tu, tv, tw obtained in this way, the motor 18 is driven with a desired torque designated by the torque command value (final torque command value Tmf ^* ). (See FIG. 4).

<Vibration suppression control calculation processing>
Hereinafter, the details of the damping control calculation process executed in step S203 in the control device for the electric vehicle 10 according to the present embodiment will be described.

FIG. 4 is a damping control block diagram of the control device for the electric vehicle 10 according to the first embodiment. The final torque command value Tmf ^* is set by performing the damping control calculation processing on the target torque value Tm ^* . In FIG. 4, the vibration suppression control calculation unit 30 performing step S203, the current command value calculation unit 66 performing step S204, and the current control calculation unit 68 performing step S205 form part of the motor controller 12.

The vibration suppression control calculation unit 30 includes a vibration suppression control feedforward calculation unit (damping control FF calculation unit 32), a vibration suppression control feedback calculation unit (damping control FB calculation unit 58), and an adder 64.

The vibration suppression control FF calculation unit 32 (feedforward calculation means) performs the feedforward process of the present application. The vibration suppression control FF calculation unit 32 outputs the torque command value Tm1 ^* by inputting the torque target value Tm ^* and performing filtering processing (described later) for suppressing torsional vibration in the drive shaft 22. .. Further, the vibration suppression control FF calculation unit 32 calculates the motor angular velocity estimated value ωm^ in the process of calculating the torque command value Tm1 ^* . Details of the calculation of the vibration suppression control FF calculation unit 32 will be described later.

The vibration suppression control FB calculation unit 58 (feedback calculation means) performs the feedback process of the present application. The vibration suppression control FB calculation unit 58 calculates a torque correction value Tm2 ^* (first feedback torque) in consideration of disturbance and model error based on the difference between the motor angular velocity estimated value ωm^ and the detected motor angular velocity ωm. is there. Details of the calculation of the vibration suppression control FB calculation unit 58 will be described later.

The adder 64 adds the torque command value Tm1 ^* and the torque correction value Tm2 ^* and outputs the final torque command value Tmf ^* .

FIG. 5 is a block diagram of the vibration suppression control FF calculation unit 32 and the vibration suppression control FB calculation unit 58 that form the control device for the electric vehicle 10 according to the first embodiment. First, the calculation in the vibration suppression control FF calculation unit 32 will be described. As shown in FIG. 5, the vibration suppression control FF calculation unit 32 includes a vehicle model 34 configured by a dead zone model that simulates vehicle parameters and gear backlash. Further, the drive shaft twist angular velocity FB calculation unit 52 is provided that subtracts Tm ^* from the target torque value by multiplying the estimated twist angular velocity of the drive shaft 22 (ωd^, pseudo twist angular velocity) by the gain K _FB1 (feedback gain).

The vehicle model 34 of this embodiment will be described. FIG. 6 is a diagram modeling the driving force transmission system of the electric vehicle 10. Based on FIG. 6, the equation of motion of the electric vehicle 10 is the following equations (1) to (7).

Here, each parameter is as follows.

Jm: Motor inertia Jw: Drive axis inertia (for one axis)
Kd: Torsional rigidity of drive shaft Kt: Coefficient relating to friction between tire and road surface N: Overall gear ratio r: Tire load radius ωm: Motor angular velocity ωw: Driving wheel angular velocity Tm: Motor torque Td: Driving shaft torque F: Driving force (2 Axis)
V: Vehicle speed θ: Twist angle of drive shaft C: Viscosity coefficient according to motor twist angular velocity Tc: Viscous torque according to motor twist angular velocity

By the way, the twist angular velocity of the motor 18 has a correlation with the twist angular velocity of the drive shaft 22 (ωd=(ωm/N)−ωw). Therefore, the viscous torque Tc in the motor 18 can be calculated by multiplying the torsional angular velocity of the drive shaft 22 by the viscosity coefficient C.

When the transfer characteristics from the motor torque Tm (torque target value Tm ^* ) to the motor angular velocity (motor angular velocity estimated value ωm^) are obtained by Laplace transforming the equations (1) to (7), the following equation is obtained.

However, each parameter is as follows.

In the equation (10), a2 has a viscosity term (2JwMC/N) according to the torsional angular velocity of the motor 18, and a1 also has a viscosity term (CKt(Mr ² +2Jw)/N). The transfer characteristic from the motor torque Tm to the drive shaft torque Td is given by the following equation.

However, each parameter is as follows.

From the equations (2), (4), (5), and (6), the transfer characteristic from the motor angular velocity (motor angular velocity estimated value ωm^) to the drive wheel angular velocity ωw is obtained by the following equation.

From the equations (7), (9) and (11), the transfer characteristic from the motor torque Tm to the drive wheel angular velocity ωw is given by the following equation.

From the expressions (9) and (13), the transfer characteristic from the drive shaft torque Td to the drive wheel angular velocity ωw is given by the following expression.

By transforming equation (1),
Therefore, the drive shaft torsional angular velocity (ωm/N)−ωw can be expressed by the following equation from the equations (14) and (15).

However,
Is.

When the backlash characteristic from the motor 18 to the drive shaft 22 is modeled in the dead zone, the drive shaft torque Td is expressed by the following equation.

Here, θd is the overall backlash amount of the gear that transmits torque from the motor 18 to the drive shaft 22. Accordingly, the vehicle model 34 is a model including the transfer characteristic Gp(s) and including a dead zone in which the torque of the motor 18 is not transmitted to the drive shaft of the electric vehicle 10.

The vehicle model 34 is considered according to the twist angular velocity estimated value ωd̂ of the drive shaft 22. Thus, the torque command value (loss before considering) Tm1 ^*, the viscosity torque corresponding to torsion angular velocity of the motor 18 Tc, the motor torque as Tm used to calculate the torsional angular speed of the drive shaft 22, the vehicle model 34 , The calculation shown in the following equation is performed.

In addition, in the electric vehicle 10 with the speed reducer 20 (transmission mechanism), the viscosity term (viscosity coefficient C) according to the torsional angular velocity of the motor 18 is set to a value according to the gear ratio N, and C(N) Become.

Next, the drive shaft twist angular velocity FB calculation unit 52 will be described. The torque command value Tm1 ^* , which is the output of the drive shaft twist angular velocity FB calculation unit 52, is represented by the following equation using the target torque value Tm ^* and a drive shaft twist angular velocity FB command value T _FB (second feedback torque) described later. To be done.

From the equations (20) and (21), the relationship between the target torque value Tm ^* and the motor torque Tm is expressed by the following equation.

The drive shaft twist angular velocity FB command value T _FB is expressed by the following equation using the drive shaft twist angular velocity estimated value (ωd^=(ωm/N)−ωw) calculated from the vehicle model 34.

Further, the above equation can be rewritten as the following equation from the equations (4) and (6).

Further, the equation (11) can be transformed into the following equation (25).

Here, ζp is the damping coefficient of the drive torque transmission system, and ωp is the natural vibration frequency of the drive torque transmission system. Further, when the poles and zeros of the equation (25) are examined, α≈c ₀ /c ₁ is obtained, and therefore, the pole-zero cancellation results in the following equation.

From equations (22), (24) and (26), the drive shaft torque Td is represented by the following equation.

When the equation (27) is modified, the transfer characteristic of the drive shaft torsional angular velocity FB system is expressed by the following equation.

A normative response, which is an idealized torque response from the motor 18 to the drive shaft 22, is expressed by the following equation when it is considered that the response from Tm′ to Td does not form a vibration system (undershoot).

The condition that the transfer characteristic of the drive shaft torsion angular velocity FB system and the normative response match is as follows.

From the equation (29), the feedback gain is determined by the following equation.

As shown in FIG. 5, the vehicle model 34 includes a subtractor 36 that outputs Tm. Further, the vehicle model 34 includes a subtractor 40a, an integral element 40b for generating ωd^, an integral element 40c for generating θ, a dead zone element 40d(I(θ)), a proportional element 40e(Kd), and a filter 40f(Hw(Hw( s)), and a negative feedback loop 40 including a subtractor 40a.

Here, the output (Tm) of the subtractor 36 that has passed through the proportional element 38 (1/JmN) (Tm/JmN) is input to the plus side of the subtractor 40a, and the filter 40f( The output (Hw(s)·Td) of Hw(s)) is input. The output of the integration element 40b (equation (17)) is output to the drive shaft twist angular velocity FB calculation unit 52.

In the dead zone element 40d(I(θ)), θ calculated by the integrating element 40c is converted as follows according to the equation (19).

The vehicle model 34 is the output (Td) of the subtractor 36 and the output (Td/Jm) through the proportional element 42 (1/Jm), and the output (Td) of the proportional element 40e (Kd). And a subtractor 46 that outputs the difference from the output (Td/JmN) through the proportional element 44 (1/JmN). Further, an integration element 48 that integrates the output of the subtractor 46 and outputs a motor angular velocity estimated value ωm^ (equation (16)) is provided. Therefore, the vehicle model 34 can perform the estimated value calculation process of the estimated motor angular velocity ωm^.

Further, the vehicle model 34 includes a proportional element 50(C) for multiplying the output (ωd^) of the integral element 40c by the viscosity coefficient C corresponding to the torsional angular velocity of the motor 18, and the output of the proportional element 50(C) is a subtractor. It is input to the minus side of 36.

As shown in FIG. 5, the drive shaft torsional angular velocity FB calculation unit 52 includes a proportional element 54 (K _FB1 ), which multiplies the output (ωd̂) of the integral element 40 b by a gain K _FB1 , a target torque value Tm ^*, and a proportional element 54. Output (drive shaft twist angular velocity FB command value T _FB ) and a subtractor 56 that outputs the difference as a torque command value Tm1 ^* . Therefore, the drive shaft twist angular velocity FB calculation unit 52 can consequently perform the feedforward process.

Next, the operation of the vibration suppression control FB calculation unit 58 will be described. The vibration suppression control FB calculation unit 58 includes a subtracter 60 that outputs the difference between the estimated motor angular speed value ωm^ calculated by the vehicle model 34 of the vibration suppression control FF calculation unit 32 and the detected motor angular speed value ωm, and a subtractor 60. The torque correction value Tm2 ^* is calculated by passing the output through the filter 62 (H(s)/Gp(s)) including the inverse characteristic of the transfer characteristic Gp(s) (equation (9)) and the bandpass filter H(s).

FIG. 7 is a diagram showing frequency characteristics of the bandpass filter H(s). Next, the bandpass filter H(s) will be described. The bandpass filter H(S) serves as a feedback element that reduces only vibration. At this time, the greatest effect can be obtained by setting the filter characteristics as shown in FIG. That is, in the bandpass filter H(s), the damping characteristics on the lowpass side and the highpass side are substantially the same, and the torsional resonance frequency of the drive system is near the center of the pass band on the logarithmic axis (Log scale). Is set. For example, when H(s) is composed of a first-order high-pass filter and a first-order low-pass filter, the frequency fp is the torsional resonance frequency of the drive system, f _LC is the low-frequency cutoff frequency, and f _HC is the high-frequency cutoff. The frequency and k are set as arbitrary values and configured as shown in Expression (33).

However, τ _L =1/(2πf _HC ), f _HC =k·fp, τ _H =1/(2πf _LC ), and f _LC =fp/k.

<Example of Control Effect of First Embodiment>
FIG. 8 is a diagram showing an example of a control effect by the control device of the electric vehicle 10 of the present embodiment. FIG. 8 is a comparison diagram of the control result by the control device of the electric vehicle 10 of the present embodiment when the accelerator is depressed at time t0, and the control result by the conventional technique. In the figure, the final torque command value Tmf ^* , torque correction value Tm2 ^* , motor angular velocity detection value ωm, and longitudinal acceleration of the vehicle are shown in order from the top. In addition, the solid line in each figure shows the control result by this embodiment, and the broken line shows the control result by a prior art.

In the prior art, the transmission characteristic representing the relationship between the torque of the motor 18 and the angular velocity of the motor 18 is assumed to have no viscous term (viscosity coefficient C) corresponding to the twist angular velocity of the motor 18. Therefore, the behavior is different from the actual vehicle state, and vibration occurs at a predetermined frequency in the final torque command value Tmf ^* , the torque correction value Tm2 ^* , the detected motor angular velocity ωm, and the vehicle longitudinal acceleration. Particularly, when there is no disturbance with respect to the electric vehicle 10, the torque correction value Tm2 ^* is ideally zero. However, it can be seen that the control of the related art vibrates at a predetermined frequency. This is because, in the related art, the viscosity term is not taken into consideration in the transfer characteristic, and therefore the motor angular velocity estimated value ωm^ and the motor angular velocity detected value ωm deviate even when there is no disturbance. For this reason, unnecessary feedback torque is generated in the conventional control. Therefore, the vehicle longitudinal acceleration overshoots at times t0 to t1 and induces a vehicle behavior that is uncomfortable for the driver.

On the other hand, according to this embodiment, the viscous term (viscosity coefficient C) according to the torsional angular velocity of the motor 18 is taken into consideration in the transmission characteristic, and when there is no disturbance, the torque correction value Tm2* becomes substantially zero, which is unnecessary. No feedback torque is generated. Therefore, even in the final torque command value Tmf ^* , the detected motor angular velocity value ωm, and the vehicle longitudinal acceleration, unnecessary vibration does not occur, and a smooth response without shock can be obtained.

<Effects of First Embodiment>
As described above, the control device (motor controller 12) for the electric vehicle 10 according to the first embodiment calculates the torque command value Tm1 ^* based on the torque target value Tm ^* set based on the vehicle information, The control device (motor controller 12) of the electric vehicle 10 controls the torque of the motor 18 connected to the drive wheels 24a and 24b based on the torque command values (Tm1 ^* , Tmf ^* ). This control device inputs a torque command value Tm1 ^* into a transfer characteristic Gp(s) that represents the relationship between the torque of the motor 18 and the angular velocity of the motor 18, and calculates a motor angular velocity estimated value ωm^ by estimating the vehicle model 34 (estimation). (Value calculation means), the motor angular velocity estimated value ωm^, and the detected motor angular velocity ωm, and a difference between the motor angular velocity detected value ωm and the inverse characteristic of the transfer characteristic Gp(s) and the filter 62 (H (S)/Gp(s)) to calculate a torque correction value Tm2 ^* (first feedback torque) to be added to the torque command value Tm1 ^* , and a vibration suppression control FB calculation unit 58 (feedback means). Including. The transfer characteristic Gp(s) is characterized by including a viscosity term (viscosity coefficient C, see equation (10)) generated according to the twist angular velocity of the motor 18.

Therefore, the control method of the electric vehicle 10 according to the first embodiment calculates the torque command value (Tm1 ^* , Tmf ^* ) based on the torque target value Tm ^* set based on the vehicle information, and calculates the torque command value as the torque command value. This is a control method of the electric vehicle 10 that controls the torque of the motor 18 connected to the drive wheels 24a and 24b based on the above. This control method includes an estimated value calculation step of inputting the torque command value Tm1 ^* into the transfer characteristic Gp(s) representing the relationship between the torque of the motor 18 and the angular velocity of the motor 18 to calculate the estimated motor angular velocity value ωm^. Including. Further, the difference between the motor angular velocity estimated value ωm^ and the detected motor angular velocity ωm is calculated by calculating the filter 62(H(s) that is the product of the inverse characteristic of the transfer characteristic (Gp(s)) and the bandpass filter H(s). )/Gp(s)) to calculate a torque correction value Tm2 ^* (first feedback torque) to be added to the torque command value Tm1 ^* . Then, the motor angular velocity estimated value ωm^ is calculated by adding a viscous term (viscosity coefficient C, see equation (10)) generated according to the twist angular velocity of the motor 18 to the transfer characteristic Gp(s). ..

As a result, unnecessary feedback torque is suppressed when the target torque value Tm ^* changes, and overshoot of the torque response of the drive shaft 22 is suppressed, so that a vehicle behavior that is uncomfortable for the driver can be suppressed.

The above control method includes a feedforward step of calculating the torque command value Tm1 ^* based on the target torque value Tm ^* . In the feedforward process, the torque command value Tm1 ^* is used by using the vehicle model 34 of the electric vehicle 10 including the transfer characteristic Gp(s) and having the dead zone in which the torque of the motor 18 is not transmitted to the drive shaft 22 of the electric vehicle 10 ^. From this, the twist angular velocity estimated value ωd^ of the drive shaft 22 is calculated. In addition, the second feedback torque (T _FB1) obtained by multiplying the torque angular value estimated value ωd^ by the target torque value Tm ^* and the gain K _FB1 relating to the normative response in which the torque response from the motor 18 to the drive shaft 22 is idealized. ) And, the torque command value Tm1 ^* is calculated. Then, the vehicle model 34 estimates the twist angular velocity ωd based on the difference between the torque command value Tm1 ^* and the viscosity torque Tc obtained by multiplying the twist angular velocity estimated value ωd^ by the viscosity coefficient C in the torsion direction of the motor 18. It is characterized by calculating ^. As a result, drive shaft torsional vibration that occurs due to modeling errors between the vehicle model 34 and the actual electric vehicle 10 can be suppressed.

In the above control method, the estimated value calculating step is a step of calculating the motor angular velocity estimated value ωm^ when the torsional angular velocity estimated value ωd^ is calculated using the vehicle model 34. As a result, the twist angular velocity estimated value ωd^ and the motor angular velocity estimated value ωm^ correspond to each other with high accuracy, so that a calculation error can be suppressed.

In the above control method, the viscosity term (viscosity coefficient C) is set according to the gear ratio N of the speed reducer 20 that transmits the torque of the motor 18 to the drive shaft 22. As a result, even if the gear ratio N of the speed reducer 20 is changed, unnecessary feedback torque when the target torque value Tm ^* changes is suppressed, and the overshoot of the torque response of the drive shaft 22 is suppressed. It is possible to suppress unnatural vehicle behavior. It should be noted that this feature can also be applied to second and third embodiments to be described later that similarly include Gp(s).

<Second Embodiment>
FIG. 9 is a vibration suppression control block diagram which constitutes the control device for the electric vehicle 10 according to the second embodiment. In the control device for the electric vehicle 10 according to the second embodiment, the damping control FB calculation unit 58 and the adder 64 according to the first embodiment are commonly applied. However, the vibration suppression control FF calculation unit 72 is composed of a filter of Gm(s)/Gp(s), and the second transfer characteristic for calculating the motor angular velocity estimated value ωm^ by inputting the final torque command value Tmf ^*. The difference is that 74 Gp(s) is used.

The second transfer characteristic 74 (Gp(s)) is a function similar to the transfer characteristic Gp(s) of the first embodiment. The second transfer characteristic 74 (Gp(s)) is a linear plant model that represents the transfer characteristic between the torque of the motor 18 and the angular velocity of the motor 18 of the electric vehicle 10, and the dead zone due to gear backlash is taken into consideration. It has not been. On the other hand, Gm(s) is an ideal model showing the transfer characteristic between the motor torque input to the vehicle and the response target of the motor rotation speed. Further, Gm(s) can be expressed by a function similar to Gp(s), and like Gp(s), includes a viscous term and performs zero-zero cancellation (see equation (25)). Is possible. Therefore, if ζp is the damping coefficient of the driving torque transmission system, ωp is the natural vibration frequency of the driving torque transmission system, ζm is the damping coefficient of the ideal model, and ωm is the natural vibration frequency of the ideal model, then Gm(s)/Gp( s) can be expressed by the following equation.

When it is not necessary to consider the viscosity term in Gm(s), the viscosity coefficient C may be set to zero (see formula (10)).

<Effects of Second Embodiment>
Therefore, the control method (control device) for the electric vehicle 10 according to the second embodiment includes the feedforward step of calculating the torque command value Tm1 ^* based on the target torque value Tm ^* . Then, in the feedforward process, the inverse characteristic of the second transmission characteristic 74 representing the relationship between the torque of the motor 18 and the angular velocity of the motor 18 and the torque response from the motor 18 to the drive shaft 22 of the electric vehicle 10 are idealized. A feature is that the torque command value Tm1 ^* is calculated from the target torque value Tm ^* by using the vibration suppression control FF calculation unit 72 that is a product of the reference response and the standard response. As a result, the feedforward calculation can be performed with a simple configuration.

In the above control method, in the feedforward step, the torque command value Tm1 ^* is calculated by adding the viscosity term (viscosity coefficient C) generated according to the torsional angular velocity of the motor 18 to the second transfer characteristic 74. To do. Thereby, the feedforward calculation can be performed with a simple configuration while considering the viscosity term.

In the above control method, in the estimated value calculation step using the second transfer characteristic 74, the torque command value Tm1 ^* and the torque correction value Tm2 ^* (first feedback torque) are added (final torque command value Tmf ^*). ), the motor angular velocity estimated value ωm^ is calculated. As a result, the estimated motor angular velocity value ωm is calculated based on the final torque command value Tmf ^* , so that the torque correction value Tm2 ^* can be calculated with high accuracy.

<Third Embodiment>
FIG. 10 is a vibration damping control block diagram which constitutes the control device for the electric vehicle 10 according to the third embodiment. FIG. 11 is a diagram showing equivalent conversion of the vibration suppression control block diagram of FIG. 10. The control device for the electric vehicle 10 according to the third embodiment is common in that the damping control FB calculation unit 58 and the second transfer characteristic 74 (not shown in FIGS. 10 and 11) are used as in the second embodiment. .. However, the vibration control FF calculation unit 76 uses the linear filter 78 that reduces the natural vibration frequency component of the driving force transmission system of the electric vehicle 10 that has a dead zone in which the torque of the motor 18 is not transmitted to the drive shaft 22 to obtain the torque target. The difference is that the torque command value Tm1 ^* is calculated from the value Tm ^* .

In the above filter, the dead zone section due to the backlash of the driving force transmission system is expressed by the difference between the linear function depending on the twist angle θ of the drive shaft 22 and the saturation function (equation (41)) having the twist angle θ as a variable. be able to. Therefore, based on FIG. 5, the equation of motion of the vehicle is represented by the following (35) to (40).

Here, each parameter is as follows.
Jm: Motor inertia Jw: Drive axis inertia (for one axis)
M: mass of vehicle Kd: torsional rigidity of drive shaft Kt: coefficient related to friction between tire and road surface N: overall gear ratio r: tire load radius ωm: motor angular velocity ωw: drive wheel angular velocity Tm: motor torque Td: drive shaft torque F : Driving force (for 2 axes)
V: vehicle speed θ: twist angle of drive shaft

However, St(θ) is a saturation function,
It is defined as. θBL is the gear backlash amount in the overall from the motor 18 to the drive shaft 22.

From the equations (35) to (40), the transfer characteristic from the torque command value (torque target value Tm ^* ) to the drive shaft torsion angle θ can be obtained by the following equation.

However,
Where ζp is the damping coefficient of the driving force transmission system, and ωp is the natural vibration frequency of the driving force transmission system.

Therefore, the drive shaft torque Td is calculated from the equations (38) and (42).
Is expressed as

Here, the normative response Tdm related to the torque response of the drive shaft 22 is represented by the following equation.

Here, ζm and ωm are the damping coefficient and the natural vibration frequency of the ideal model, respectively.

When the motor torque Tm such that Td=Tdm is obtained, the following equation is obtained.

Therefore, as shown in FIG. 10, the vibration suppression control FF calculation unit 76 determines the drive shaft torsion angle θ and the linear filter 78 (G _INV (s)) that reduces the natural vibration frequency component of the torque transmission of the electric vehicle 10. A filter 80 (Gtm(s)) to be calculated, a saturation function 82 (St(θ)) serving as a limiter, and a filter 84 (Fs(s)) for compensating the phase shift due to the wheel inertia of the drive shaft torsion angle and the tire frictional force. ). Further, the vibration suppression control FF calculation unit 76 includes a positive feedback loop that feeds back the output of the filter 84 to the adder 86 in a series circuit in which the adder 86, the filter 80, the saturation function 82, and the filter 84 are connected in this order. The torque command value Tm1 ^* is input to the adder 86, and the torque command value Tm1 ^* and the output of the filter 84 are added. The damping control FF calculation unit 76 includes an adder 88 that adds the torque target value Tm* and the output of the filter 84. Further, a subtractor 90 is provided which outputs the difference between the output of the adder 88, which has passed through the linear filter 78 (G _INV (s)), and the filter 84 as the torque command value Tm1*.

Substituting the expression (49) into the expression (42) gives the following expression.

Therefore, considering the equivalent conversion of the vibration suppression control FF calculation unit 76 shown in FIG. 10, it can be configured as shown in FIG. The block diagram of the equivalent conversion shown in FIG. 11 has substantially the same form as that of FIG. 10, except that the output of the filter 84 and the target torque value Tm ^* are input to the adder 86.

<Effects of Third Embodiment>
By providing the damping control FF calculation unit 76 as in the present embodiment, unlike the case of the first embodiment, there is no integral element, and therefore the torque command value Tm1 ^* can be calculated with higher accuracy.

Although the embodiment of the present invention has been described above, the above embodiment merely shows a part of the application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

10 Electric Vehicle 12 Motor Controller 32 Vibration Suppression Control FF Calculator 34 Vehicle Model 50 Proportional Element 58 Vibration Suppression Control FB Calculator 68 Current Control Calculator

Claims (9)

A method for controlling an electric vehicle, which calculates a torque command value based on a torque target value set based on vehicle information, and controls the torque of a motor connected to driving wheels based on the torque command value,
An estimated value calculation step of calculating the motor angular velocity estimated value by inputting the torque command value into a transfer characteristic that represents the relationship between the torque of the motor and the angular velocity of the motor,
The difference between the estimated motor angular velocity value and the detected motor angular velocity value is input to a filter composed of a product of the inverse characteristic of the transfer characteristic and a bandpass filter to calculate a first feedback torque to be added to the torque command value. And a feedback step to
A method for controlling an electric vehicle, comprising adding a viscosity term generated according to a twist angular velocity of the motor to the transfer characteristic to calculate the motor angular velocity estimated value. The control method for the electric vehicle according to claim 1,
A feedforward step of calculating the torque command value based on the torque target value,
In the feedforward step,
Using the vehicle model of the electric vehicle including the transfer characteristic and having a dead zone in which the torque of the motor is not transmitted to the drive shaft of the electric vehicle, the torsional angular velocity estimated value of the drive shaft is calculated from the torque command value. , Based on a difference between the torque target value and a second feedback torque obtained by multiplying the twist angular velocity estimated value by a gain relating to a normative response in which the torque response from the motor to the drive shaft is idealized, Calculate the torque command value,
The vehicle model is
The torsional angular velocity estimated value is calculated based on a difference between the torque command value and a viscous torque obtained by multiplying the torsional angular velocity estimated value by a viscosity coefficient in the torsional direction of the motor. Control method. The control method for the electric vehicle according to claim 2,
The estimated value calculation step,
A method of controlling an electric vehicle, comprising the step of calculating the motor angular velocity estimated value when calculating the twist angular velocity estimated value using the vehicle model. The control method for the electric vehicle according to claim 1,
A feedforward step of calculating the torque command value based on the torque target value,
In the feedforward step,
A filter formed by a product of an inverse characteristic of a second transfer characteristic representing a relationship between the motor torque and an angular velocity of the motor and a reference response obtained by idealizing a torque response from the motor to the drive shaft of the electric vehicle. A method of controlling an electric vehicle, characterized in that the torque command value is calculated from the torque target value using the torque command value. The control method for an electric vehicle according to claim 4,
In the feedforward step,
A method for controlling an electric vehicle, comprising adding a viscosity term generated according to a twist angular velocity of the motor to the second transfer characteristic to calculate the torque command value. The control method for the electric vehicle according to claim 1,
A feedforward step of calculating the torque command value based on the torque target value,
In the feedforward step,
Calculating the torque command value from the torque target value using a filter that reduces the natural vibration frequency component of the driving force transmission system of the electric vehicle having a dead zone where the torque of the motor is not transmitted to the drive shaft of the electric vehicle A method for controlling an electric vehicle, comprising: The control method for an electric vehicle according to any one of claims 4 to 6,
In the estimated value calculation step,
A method for controlling an electric vehicle, wherein the motor angular velocity estimated value is calculated based on a sum of the torque command value and the first feedback torque. The control method for an electric vehicle according to any one of claims 1 to 7,
A method for controlling an electric vehicle, wherein the viscosity term is set according to a gear ratio of a speed reducer that transmits torque of the motor to a drive shaft of the electric vehicle. In a control device for an electric vehicle that calculates a torque command value based on a torque target value that is set based on vehicle information, and controls the torque of a motor that is connected to drive wheels based on the torque command value,
Estimated value calculation means for calculating the motor angular velocity estimated value by inputting the torque command value into a transmission characteristic that represents the relationship between the torque of the motor and the angular velocity of the motor,
The difference between the estimated motor angular velocity value and the detected motor angular velocity value is input to a filter composed of a product of the inverse characteristic of the transfer characteristic and a bandpass filter to calculate a first feedback torque to be added to the torque command value. Feedback means for
The control device for an electric vehicle, wherein the transfer characteristic includes a viscosity term generated according to a twist angular velocity of the motor.