JP6728633B2 - Electric vehicle control method and control device - Google Patents

Description

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

In a control device for an electric vehicle equipped with a motor, a target torque value for the motor is calculated from the accelerator opening degree, the vehicle speed, and the like. However, in a torque transmission system in which torque is transmitted from a motor to driving wheels, there are phase shifts due to wheel characteristics, dead zones of gears, and the like. Therefore, it is known that vibration is generated in the drive shaft of the vehicle even if the motor is controlled by using the calculated target torque value as it is.

Therefore, in Patent Document 1, a vehicle model that models the characteristics from the motor torque to the drive shaft torsion angular velocity and a drive shaft torsion angular velocity FB that corrects the torque target value using the pseudo drive shaft torsion angular velocity obtained from the vehicle model A control device for an electric vehicle including an FF (feedforward) compensator utilizing a (feedback) model is disclosed. According to this control device, since the drive shaft torsion angular velocity feedback system is configured in a pseudo manner, it is possible to suppress the vibration generated in the drive shaft without affecting the stability.

Further, in Patent Document 1, the gear backlash characteristic can be simulated by giving the drive shaft torque of the vehicle model a dead zone characteristic. By doing so, it is possible to suppress drive shaft torsional vibration that occurs even when gear backlash occurs.

International publication WO2013/157315

In an actual electric vehicle, there is a mechanical loss in the torque transmission path from the motor to the drive shaft, and this mechanical loss may act as a torque disturbance on the vehicle model. However, in the vehicle model of Patent Document 1, since the influence of such mechanical loss is not taken into consideration, in an actual electric vehicle in which mechanical loss exists, torsional vibration may occur in the drive shaft.

In particular, when passing through the gear backlash, due to the influence of this mechanical loss, the relative positional relationship between the gear on the motor shaft side of the reducer of the vehicle and the gear on the drive shaft side is the relative positional relationship determined by the vehicle model. It does not match with. Such erroneous recognition of the relative positional relationship of the gears is difficult to sufficiently prevent even if the dead zone characteristic is taken into consideration in the vehicle model.

The present invention has been made in view of such problems, and an object of the present invention is to provide a control method and a control device for an electric vehicle that can suppress torsional vibration generated in a drive shaft.

One aspect of a control method for an electric vehicle of the present invention is a feedforward compensation step of performing a feedforward compensation process for a target torque command value to a motor calculated based on vehicle information of the electric vehicle, and a feedforward compensation step. A motor control step of controlling the motor connected to the drive wheels of the electric vehicle using the processed target torque command value, and the feedforward compensation step models the characteristics from the motor torque to the drive shaft torsion angular velocity. Using the vehicle model, a pseudo drive shaft torsional angular velocity calculation step of calculating the pseudo drive shaft torsional angular velocity according to the target torque command value, and a torsional angular velocity feedback step of feeding back the pseudo drive shaft torsional angular velocity to the target torque command value. A method for controlling an electric vehicle having the method, further comprising a correction step of performing correction on a target torque command value in consideration of a torque loss from a motor to a drive shaft.

According to one aspect of the present invention, the correction step is executed in consideration of the torque loss amount from the motor to the drive shaft with respect to the target torque command value. By doing so, in addition to performing the FB control using the drive shaft torsional angular velocity calculated using the vehicle model, the torque loss is taken into consideration, so that the FB control can be performed while passing through the gear backlash. , It is possible to reduce the risk of erroneously recognizing the relative relationship of the gears. Therefore, the torsional vibration generated on the drive shaft can be suppressed.

FIG. 1 is a schematic configuration diagram of an electric vehicle controlled by the control method of the first embodiment. FIG. 2 is a flowchart of motor control by the motor controller. FIG. 3 is a table showing the relationship between the accelerator opening and the torque. FIG. 4 is a flowchart of the damping control calculation process. FIG. 5 is a control block diagram of the vibration suppression control calculation processing. FIG. 6 is a control block diagram of the FF compensation unit. FIG. 7 is a control block diagram of the FB compensation unit. FIG. 8 is a diagram showing a vehicle model of an electric vehicle. FIG. 9 is an explanatory diagram of a state of the electric vehicle. FIG. 10 is a flowchart of the vibration suppression control calculation process of the second embodiment. FIG. 11 is a flowchart of the FF compensation process. FIG. 12 is a control block diagram of the vibration suppression control calculation process. FIG. 13 is a control block diagram of the FF compensation unit.

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

(First embodiment)
FIG. 1 is a diagram showing an electric vehicle controlled by the control method of the present invention.

Battery 1 mounted on an electric vehicle is a chargeable/dischargeable battery. The electric power discharged from the battery 1 is supplied to the motor 3 via the inverter 2. When regenerative power is generated by the motor 3, the regenerative power generated by the motor 3 is charged in the battery 1 via the inverter 2. A current sensor 4 is provided between the inverter 2 and the motor 3, and the current sensor 4 measures the current between the inverter 2 and the motor 3.

The inverter 2 is a circuit composed of a plurality of electronic devices and converts direct current and alternating current. For example, the inverter 2 is composed of two switching elements in each phase. Note that, for example, a power semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOS-FET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used as the switching element.

In the inverter 2, ON/OFF switching operation of the switching element is performed according to the PWM signal generated by the motor controller 5. By such a switching operation, the direct current supplied from the battery 1 to the inverter 2 is converted into alternating current, and an alternating current of a desired magnitude is applied to the motor 3. When the motor 3 performs regenerative braking, the regenerative power generated by the motor 3 is output as an alternating current, converted into direct current by the inverter 2, and then charged in the battery 1.

The motor controller 5 is a controller that controls the drive torque of the motor 3. Signals of vehicle variables such as a vehicle speed V, an accelerator opening θ, a rotor phase α of the motor 3, a current I flowing through the motor 3 and a DC voltage value Vdc in a DC power supply line are input to the motor controller 5 as digital signals. ..

The rotor phase α input to the motor controller 5 is measured by the rotation sensor 6 (for example, resolver or encoder) provided in the motor 3. The DC voltage value Vdc is measured by the battery controller 1a that controls the battery 1. Further, since the motor 3 is a three-phase AC motor, the current sensor 4 measures the currents iu, iv, iw flowing in the motor 3 and outputs the measured current value to the motor controller 5.

The motor controller 5 generates a PWM signal used for rotation control of the motor 3 based on the input vehicle variable. Then, the motor controller 5 uses a drive circuit (not shown) to generate a drive signal for the inverter 2 according to the PWM signal.

The motor 3 generates drive torque by the alternating current supplied from the inverter 2. The drive torque of the motor 3 is transmitted to the drive wheels 9a and 9b via the speed reducer 7 and the drive shaft (drive shaft) 8. Further, the motor 3 rotates along with the drive wheels 9a and 9b during traveling of the vehicle to generate regenerative braking force and regenerative power. In this way, the kinetic energy of the vehicle can be recovered as electrical energy.

FIG. 2 is a flowchart of motor control performed by the motor controller 5.

In step S21, an input process is performed. Specifically, a signal (vehicle variable) indicating vehicle information necessary for motor control is acquired by sensor input or communication with another controller.

As described above, the three-phase currents iu, iv, iw flowing through the motor 3 are acquired by the current sensor 4. Since it is known that the total of the three-phase current values becomes zero, for example, iw may be calculated from the three-phase currents iu and iv instead of being acquired by the sensor input.

The rotor phase (electrical angle) α[rad] of the motor 3 is acquired by a rotation sensor such as a resolver or an encoder. The rotor angular velocity (electrical angle) ω [rad/s] is obtained by differentiating the rotor phase (electrical angle) α. The motor angular velocity ω _m [rad/s] that is the mechanical angular velocity of the motor 3 is obtained by dividing the rotor angular velocity ω (electrical angle) by the number of pole pairs of the motor 3.

The vehicle speed V [km/h] can be calculated as follows. First, the vehicle speed v [m/s] is obtained by multiplying the motor angular velocity ω _m by the tire radius R and dividing by the gear ratio of the final gear. Then, the vehicle speed V [km/h] is obtained by multiplying the vehicle speed v [m/s] by a unit conversion coefficient (3600/1000) from the second speed [m/s] to the hourly speed [km/h]. You can The vehicle speed V [km/h] may be acquired by communication from another controller such as a meter or a brake controller (not shown).

The accelerator opening degree θ [%] is a value corresponding to the amount of depression of the accelerator pedal by the driver. The accelerator opening degree θ may be acquired by an accelerator opening degree sensor, or may be acquired by communication from a vehicle controller or another controller.

The DC voltage value Vdc [V] is output from the battery controller 1a. The DC voltage value Vdc [V] may be measured by a voltage sensor provided on the DC power supply line.

In step S22, basic target torque calculation processing is performed. The motor controller 5 sets the target torque command value T _m ^* based on the accelerator opening θ and the rotation speed N of the motor 3 using the table showing the relationship between the accelerator opening and the torque shown in FIG. 3.

Here, referring to FIG. 3, there is shown the torque [Tm] that should be generated by the motor 3 when the motor 3 is at the rotation speed N [rpm] according to the accelerator opening degree θ. The motor controller 5 uses this table to set the torque obtained from the accelerator opening θ and the motor angular velocity ω _m as the target torque command value T _m ^* . The rotation speed N [rpm] of the motor 3 can be obtained by converting the motor angular velocity ω _m [rad/s].

In step S23, damping control calculation processing is performed. It should be noted that the vibration of the drive shaft torque can be suppressed by performing the processing in consideration of the vibration suppression control in the vibration suppression control calculation processing. The motor controller 5 suppresses drive force transmission system vibration (torsional vibration of the drive shaft, etc.) according to the target torque command value T _m ^* and the motor angular velocity ω _m without sacrificing the response of the drive shaft torque. Thus, the final torque target value T _mf ^* is calculated. The details of the damping control calculation process will be described later with reference to FIG.

In step S24, a current command value calculation process is performed. The motor controller 5 uses the final torque target value T _mf ^* calculated in S23, the motor angular velocity ω _m , and the DC voltage value Vdc to indicate the target value of the current to be passed through the motor 3 in synchronous rotation coordinates. The values id ^* and iq ^* are obtained. Specifically, the motor controller 5 has a relationship between the DC voltage value Vdc, the motor angular velocity ω _m , the target torque command value T _m ^*, and the d-axis current target value id ^* and the q-axis current target value iq ^*. The table shown is stored in advance, and the dq-axis current target values id ^* , iq ^* are obtained using this table.

In step S25, current control calculation processing is performed. The motor controller 5 first calculates the dq-axis current values id, iq from the three-phase current values iu, iv, iw and the rotor phase α of the motor 3. Next, the deviations between the dq-axis current target values id ^* , iq ^* calculated in S24 and the dq-axis currents id, iq are obtained, and the dq-axis voltage command values vd, vq are calculated according to the deviations. Note that non-interference control may be added to this portion.

Then, the motor controller 5 calculates the three-phase voltage command values vu, vv, vw from the dq axis voltage command values vd, vq and the rotor phase α of the motor 3. From the three-phase voltage command values vu, vv, vw and the DC voltage Vdc, the PWM signals (on duty) tu[%], tv[%], tw[%] are obtained.

The ON/OFF of the switching element of the inverter 2 is operated using the PWM signal obtained through the processing of S21 to S25. By doing so, desired electric power is supplied to the motor 3, so that the motor 3 is driven with a torque according to the torque command value.

Next, details of the damping control calculation process (S23) shown in FIG. 2 will be described with reference to FIGS.

FIG. 4 is a flowchart of the damping control calculation process.

In the vibration suppression control calculation processing, FF (feed forward) compensation processing (S41), FB (feedback) compensation processing (S42), and compensation value addition processing (S43) are performed. Then, in the FF compensation process (S41), the control system delay element calculation process (S411), the loss consideration calculation process (S412), the vehicle model calculation process (S413), and the torsion angular velocity FB model calculation process (S414) are performed. Be seen.

Of these processes, the processes of S41, S42, and S43 are shown in the control block diagram of FIG. Further, the processing of S411 to S414 in the FF compensation calculation processing (S41) is performed in the FF compensation unit 51 of FIG. 5, and a control block diagram is shown in FIG.

FIG. 5 is a control block diagram of the vibration suppression control calculation processing. In this figure, an FF compensating unit 51 that executes an FF arithmetic process (S41), an FB compensating unit 52 that executes an FB arithmetic process (S42), and a compensation value adding unit 53 that performs a compensation value adding process (S43). It is shown.

In the FF compensator 51, FF compensation control is performed, and the first torque target value T _m1 ^* is output according to the target torque command value T _m ^* . Further, the FF compensating unit 51 obtains an estimated value of the motor angular velocity with respect to the first torque target value T _m1 ^{* and} outputs it as the first estimated motor angular velocity value ω _m1 ^.

The first motor angular velocity estimated value ω _m1 ^ corresponding to the command value to the motor 3 and the motor angular velocity ω _m that is the response value of the motor 3 are input to the FB compensation unit 52. The FB compensation unit 52 obtains a deviation between the input first motor angular velocity estimated value ω _m1 ^ and the motor angular velocity ω _m, and obtains a second torque target value T _m2 ^* according to the deviation. The detailed processing in the FB compensation unit 52 will be described later with reference to the control block diagram of FIG. 7.

Compensation value adding section 53, the first torque target value T _m1 ^*, by adding the ^* second torque target value T _{m @ 2,} to produce the final torque target value T _mf ^*.

Next, details of the processing in the FF compensation unit 51 will be described.

FIG. 6 is a control block diagram showing a detailed configuration of the FF compensation unit 51.

The FF compensation unit 51 includes a control system delay element calculation unit 511 that performs a control system delay element calculation process (S411), a loss consideration unit 512 that performs a loss consideration process (S412), and a vehicle model calculation process (S413). The calculation unit 513 and the twist angular velocity FB model calculation unit 514 that performs the twist angular velocity FB model calculation process (S414) are configured.

In the control system delay element calculation unit 511, the first torque target value T _m1 ^* output from the torsional angular velocity FB model calculation unit 514 is processed in consideration of the control system delay element. Specifically, in the control system delay element calculation unit 511, the control operation time of the delay time e ^-L1s, delay time G _a motor response (s), and, delay time for a processing time e ^-L2s sensor signals Is added to the first target torque value T _m1 ^* . However, L1 is control calculation time and L2 is sensor signal processing time. The motor response delay G _a (s) is expressed by the following equation.

However, in this equation, τ _a is a motor response time constant.

In the following, for convenience of explanation, the first torque target value T _m1 ^* after the control system delay element calculation processing output from the control system delay element calculation unit 511 is also referred to as the first torque target value T _m1 ^* . Shall be shown.

In the loss consideration unit 512, the torque transmission from the motor 3 to the drive shaft 8 is performed by processing the following equation using the first torque target value T _m1 ^* output from the control system delay element calculation unit 511. The motor torque T _m considering the torque loss in the system is obtained.

As shown in the equation (2), the motor torque T _m in which the torque loss is taken into consideration is a component (ηT _m1 ^* ) which is a component due to the transmission efficiency of the transmission and is proportional to the magnitude of the torque. It is composed of an offset component (T _f ) having a substantially constant magnitude regardless of the magnitude of the torque such as the static friction force. However, η is a torque transmission efficiency and is a value of 0 or more and less than 1 (0≦η<1). Further, since the offset torque T _f acts in the opposite direction to the rotation direction, it has a negative value when the motor 3 is positively rotating, and has a positive value when the motor 3 is negatively rotating. The torque transmission efficiency η and the offset torque T _f may be fixed values, but in order to more accurately consider the loss, parameters such as the motor angular velocity and the motor torque are related to the torque loss as necessary. It may be changed accordingly.

In the vehicle model calculation unit 513, a first motor angular velocity estimated value ω _m1 ^ and a pseudo drive shaft torsion angular velocity ω _d ^ are used in accordance with the motor torque T _m by using a vehicle model that models a torque transmission system. Is required. The pseudo drive shaft torsion angular velocity ω _d ^ is a pseudo calculation of the torsion angular velocity generated in the drive shaft 8 to which the torque of the motor 3 is transmitted. The vehicle model used in the vehicle model calculation unit 513 will be described later with reference to FIG.

In the torsional angular velocity FB model calculation unit 514, the target torque command value T _m ^* and the pseudo drive shaft torsional angular velocity ω _d ^ are input, and the first torque target value T _m1 ^* is obtained from these inputs. In the torsional angular velocity FB model calculation process (S414) by the torsional angular velocity FB model calculation unit 514, the torsional angular velocity FB model is used, and the torsional angular velocity FB model is obtained by using a part of the vehicle model. Therefore, the details of the torsional angular velocity FB model calculation process will be described later using the vehicle model of FIG.

Next, a detailed configuration of the FB compensation unit 52 will be described.

FIG. 7 is a control block diagram showing a detailed configuration of the FB compensation unit 52.

In the FB compensation unit 52, the first motor angular velocity estimated value ω _m1 ^ and the motor angular velocity ω _m are input. Then, the FB compensation unit 52 outputs the second torque target value T _m2 ^* from these inputs.

In order to perform the feedback control, the FB compensation unit 52 uses the transfer characteristic Gp(s) of the vehicle model shown in the block 521 for the second torque target value T _m2 ^* output from itself, A motor angular velocity estimated value (second motor angular velocity estimated value) ω _m2 ^ corresponding to the second torque target value T _m2 ^* is calculated. Then, the first motor angular velocity estimated value ω _m1 ^ and the second motor angular velocity estimated value ω _m2 ^ are added to calculate the final motor rotational speed estimated value ω _mf ^.

Then, the deviation between the final motor angular velocity estimated value ω _mf ^ which is an estimated value and the motor angular velocity ω _m which is a detected value can be obtained. The second torque target value T _m2 ^* is calculated by performing the processing of the filter H(s)/Gp(s) shown in the block 522 on this deviation. The filter H(s)/Gp(s) is composed of an inverse characteristic of the transfer characteristic Gp(s) of the vehicle model and a bandpass filter H(s).

Then, the second torque target value T _m2 ^* is output from the FB compensation unit 52 after the gain processing K shown in the block 523 is performed. The gain of the gain process K is set to a value of 1 or less in order to adjust the stability margin (gain margin, phase margin) of the FB control system.

Next, in the vehicle model calculation process (S413) by the vehicle model calculation unit 513 and the torsion angular velocity FB model calculation process (S414) by the torsion angular velocity FB model calculation unit 514 shown in FIG. 6, the driving force transmission of the electric vehicle is transmitted. A vehicle model that models the system is used. Therefore, the vehicle model will be described below.

FIG. 8 is a diagram modeling a driving force transmission system of an electric vehicle.

The equation of motion of the vehicle is expressed by equations (3) to (8).

However, each parameter in these equations is as follows.
J _m : Motor inertia J _w : Drive axis inertia (for 1 axis)
K _d : Torsional rigidity of drive shaft K _t : Coefficient relating to friction between tire and road surface N: Overall gear ratio r: Tire load radius ω _m : Motor angular velocity ω _w : Driving wheel angular velocity T _m : Motor torque T _D : Drive shaft torque F: Driving force (for 2 axes)
V: Vehicle speed θ: Torsional angle of drive shaft Here, when the transfer characteristics from the motor torque T _m to the motor angular speed ω _m are obtained by Laplace transforming the expressions (3) to (8), the following expression is obtained.

However, Gp(s) is given by the following equation.

The parameters in this equation are as follows.

The transfer characteristic from the motor torque T _m to the drive shaft torque T _d is given by the following equation.

However, each parameter in this equation is as follows.

Here, when the transfer characteristic from the motor angular velocity ω _m to the drive wheel angular velocity ω _{w is obtained} from the equations (4), (6), (7), and (8), the following equation is obtained.

Further, when the transfer characteristics from the motor torque T _m to the drive wheel angular velocity ω _{w are obtained} from the expressions (9), (11), and (12), the following expression is obtained.

From equations (11) and (13), the transfer characteristic from the drive shaft torque T _d to the drive shaft angular velocity ω _w is as follows.

Here, when the equation (3) is modified, the following equation is obtained.

Here, the drive shaft torsional angular velocity ω _d can be expressed by the following equation from the equations (14) and (15).

However, in this equation, H _w (s) and each parameter are as follows.

When the backlash characteristic from the motor 3 to the drive shaft 8 is modeled in the dead zone, the drive shaft torque _Td is given by the following equation.

However, θ _d is the overall backlash amount from the motor 3 to the drive shaft 8.

In this way, the vehicle model calculation unit 513 can obtain the drive shaft torsional angular velocity ω _d by performing the processing shown in Expression (16). The vehicle model calculation unit 513 outputs the drive shaft torsional angular velocity ω _d thus obtained to the torsional angular velocity FB model calculation unit 514 as a pseudo drive shaft torsional angular velocity ω _d ^.

Next, the drive shaft twist angular velocity FB model used in the drive shaft twist angular velocity FB model calculation process (S414) in the twist angular velocity FB model calculation unit 514 will be described.

The first torque target value T _m1 ^* , which is the output of the drive shaft torsional angular velocity FB model, is expressed by the following equation using the target torque command value T _m ^* and the drive shaft torsional angular velocity FB command value T _FB described later. ..

From the expressions (2) and (19), the relationship between the target torque command value T _m ^* and the motor torque T _{m is} as follows.

Here, the drive shaft torsional angular velocity FB command value T _FB is expressed by the following equation using the pseudo drive shaft torsional angular velocity ω _d ^ calculated from the vehicle model.

Further, the expression (21) can be rewritten as the following expression from the expressions (6) and (8).

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

However, in this equation, ζ _p is the damping coefficient of the drive torque transmission system, and ω _p is the natural vibration frequency of the drive torque transmission system.

Further, when the poles and zeros of the equation (23) are examined, α and c ₀ /c ₁ are almost equal. Therefore, if the equation (23) is zero-zero canceled, the following equation is obtained.

However, g _t is shown as follows.

From equations (20), (22), and (24), the drive shaft torque Td is represented by the following equation.

However, _Tm ' is a following formula.

Further, if the equation (25) is modified, the transmission characteristic of the drive shaft torsional angular velocity FB system is expressed by the following equation.

From a T _m 'responses T _d is the nominal response that does not become the vibration system can be shown as follows.

If the transmission characteristics of the drive shaft torsional angular velocity FB system and the normative response agree with each other, the following equation needs to be satisfied.

From the equation (28), when the FB gain K _FBI is a value defined by the following equation, the transfer characteristic of the drive shaft torsional angular velocity FB system and the reference response match.

Next, the effects of the present invention will be described by describing each state of the electric vehicle with reference to FIG. 9.

FIG. 9 is a diagram showing a state of the electric vehicle. 9A shows the target torque command value T _m ^* , FIG. 9B shows the final torque target value T _mf ^* , and FIG. 9C shows the front and rear of the electric vehicle. The directional acceleration a is shown.

In this figure, the accelerator is depressed at time t0 while the vehicle is decelerating with the accelerator off (coast). Then, at time t1, the acceleration of the electric vehicle becomes constant. The target torque command value T _m ^* , the final torque target value T _mf ^* , and the vehicle longitudinal acceleration a in such a state of the electric vehicle are shown. The dotted line shows the case where the vibration suppression control without considering the torque loss is performed (the case where the loss consideration process (S412) is not performed), and the solid line shows the torque loss as in the present embodiment. The figure shows the case where the vibration damping control is performed.

Referring to the target torque command value in FIG. 9A, since the accelerator pedal is not depressed until time t0, the target torque command value T _m ^* is set so that the motor 3 performs regenerative braking to decelerate the vehicle. It will be a negative value. Then, when the accelerator pedal is depressed at time t0, the target torque command value T _m ^* becomes a positive value so that the driving torque is generated in the motor 3 and the vehicle can be accelerated.

Here, when the sign of the target torque command value T _m ^* changes, the gear on the motor 3 side of the speed reducer 7 passes through the backlash existing between the gear on the drive shaft 8 side.

If the relative positional relationship of the gears of the speed reducer 7 is erroneously recognized, excessive FB torque is generated as shown by the dotted line in FIG. 9B due to such erroneous recognition. Then, the final torque target value T _mf ^* overshoots by the time t1 when the vehicle longitudinal acceleration a becomes a constant value. Therefore, as indicated by the dotted line in FIG. 9C, the vehicle longitudinal acceleration a does not change smoothly, and the vehicle behavior that is uncomfortable for the driver is induced.

According to this embodiment, since the disturbance due to the torque loss is taken into consideration, it is less likely that the relative positional relationship of the gears of the speed reducer 7 is erroneously recognized. Therefore, as shown by the solid line in FIG. 9B, the final torque target value T _mf ^* is less likely to overshoot by the time t1. Therefore, as indicated by the solid line in FIG. 9C, the vehicle longitudinal acceleration a changes smoothly, and the driver does not feel uncomfortable.

According to the first embodiment of the present invention, the following effects can be obtained.

According to the control method for the electric vehicle of the first embodiment of the present invention, as shown in FIG. 6, with respect to the target torque command value T _m ^* set in the basic target torque calculation process (S22), The torsional angular velocity FB model calculation processing (S414) is performed using the calculated pseudo torsional angular velocity ω _d ^. Then, the loss consideration unit 512 performs the loss consideration process (S412), so that the correction considering the torque loss amount from the motor 3 to the drive shaft 8 is performed.

In an actual electric vehicle, there is a torque loss between the torque generated by the motor 3 and the drive shaft 8. Therefore, the relative positional relationship between the gear on the motor 3 side and the gear on the drive wheels 9a and 9b side may be erroneously calculated. However, in the present embodiment, since the process of correcting the effective component actually acting on the drive wheels in consideration of the torque loss is performed, the relative position of the gears that mesh with each other can be accurately obtained. In this way, erroneous calculation of the relative positional relationship of gears is suppressed, so that drive shaft torsional vibration can be suppressed.

In particular, as shown in FIG. 9, in the case of re-acceleration in a decelerating state, overshoot of the final torque target value T _mf ^* does not occur, so that the vehicle can be smoothly accelerated. ..

According to the control method of the first embodiment of the present invention, as shown in FIG. 6, the loss consideration unit 512 that performs the loss consideration process (S412) that is the correction step is the vehicle model calculation performed by the vehicle model calculation unit 513. It is provided before the process S413. Since the first torque target value T _m1 ^* _calculated from the target torque command value T _m ^* is _calculated without considering the torque loss, the loss consideration process (S412) is performed on the first torque target value T _m1 ^* . By doing so, the pseudo drive shaft torsional angular velocity ω _d ^ output from the vehicle model calculation unit 513 becomes a more accurate value. Therefore, the torsional angular velocity FB model calculation unit 514 can further suppress the drive shaft torsional vibration.

Further, according to the control method of the first embodiment of the present invention, as shown in the equation (2), the torque loss considered in the correction process changes according to the magnitude of the driving torque of the motor 3. There is a fluctuation component (ηT _m1 ^* ) and a predetermined offset component (T _f ). Thus, by accurately modeling the actual torque loss in the motor 3, the vehicle can be smoothly accelerated and decelerated.

Further, according to the control method of the first embodiment of the present invention, in the vehicle model calculation process (S413) performed by the vehicle model calculation unit 513, the motor 3 is driven by the drive shaft as shown in the equation (18). Backlash characteristics up to 8 are modeled in the dead zone. By doing so, it is possible to simulate the gear backlash characteristics, and it is possible to suppress drive shaft torsional vibration even when gear backlash occurs.

Further, according to the control method of the first embodiment of the present invention, in the dead zone model in the equation (18), the dead zone width of the drive shaft torque of the vehicle model is added with the gear backlash amount from the motor 3 to the drive shaft 8. The combined overall backlash amount, θ _d, is used. By doing this, it is possible to reproduce the gear backlash characteristics by setting the total backlash amount as the dead band width without individually setting the backlash amounts for multiple gears. Vibration can be suppressed.

(Second embodiment)
In the first embodiment, the loss consideration process is performed in the FF compensation process (S41) performed by the FF compensation unit 51, but the present invention is not limited to this. It is also possible to perform processing in consideration of torque loss in a stage before the FF compensation process (S41) performed by the FF compensating unit 51 and in a stage after the compensation value summing process (S43) performed by the compensation value adding unit 53. In the second embodiment, such processing will be described.

FIG. 10 is a flowchart of the vibration suppression control calculation process of this embodiment.

Compared with the flowchart of the vibration suppression control calculation process of the first embodiment shown in FIG. 4, the flowchart shown in FIG. 10 has a loss consideration process (S101) provided before the FF compensation process (S41). The difference lies in that the loss compensation processing (S102) is provided after the compensation value addition processing (S43).

FIG. 11 is a flowchart showing detailed processing of the FF compensation processing (S41) of this embodiment. In the FF compensation process shown in FIG. 11, the loss consideration process (S412) is deleted as compared with the FF compensation calculation process (S41) in the vibration suppression control calculation process of the first embodiment shown in FIG. The points are different.

FIG. 12 is a control block diagram of the vibration suppression control calculation processing of this embodiment. Compared with the control block diagram of the first embodiment shown in FIG. 5, the control block diagram shown in FIG. 12 includes a loss consideration unit 121 that performs a loss consideration process (S101) and a loss compensation process (S102). A loss compensating unit 122 is added.

The loss consideration unit 121 considers the torque loss (torque transmission efficiency and torque offset component) from the motor 3 to the drive shaft 8 so that the first FF compensation process (S41) performed by the FF compensation unit 51 in the subsequent stage is performed. It becomes possible to accurately calculate various quantities related to the rotational movement such as the estimated motor angular velocity value ω _m1 ^. Specifically, the target torque command value T _m loss account target torque command value considering loss for ^* T _m ^'*, is calculated by the following equation.

However, in this equation, η is the torque transmission efficiency (0≦η<1), and T _f is the offset torque.

The loss compensator 122 operates from the motor 3 to the drive shaft so that the third torque target value T _m3 ^* calculated by the compensation value adder 53 in the preceding stage effectively acts on the rotational movement from the motor 3 to the drive shaft 8. The torque loss up to 8 (torque transmission efficiency and torque offset component) is added to the third target torque value T _m3 ^* . Specifically, the final torque target value T _mf ^* considering the loss with respect to the third torque target value T _m3 ^{* is} calculated by the following formula.

In the equation (31), η indicates the torque transmission efficiency (0≦η<1) and T _f indicates the torque offset component, as in the equation (30). The relationship between the final torque target value T _mf ^* in the equation (31) and the third torque target value T _m3 ^{* is} the relationship between the loss-considered target torque command value T _m ^{'* and} the target torque command value T _m ^{* in the} equation (30). It is the opposite of the relationship. This is because the effective value in which the torque loss is taken into consideration is calculated by the expression (30), while the torque loss is compensated by the expression (31).

FIG. 13 is a control block diagram showing a detailed configuration of the FF compensation unit 51 of this embodiment. The FF compensation unit 51 performs each process in the FF compensation calculation process shown in FIG. Compared to the configuration of the FF compensation unit 51 of the first embodiment shown in FIG. 6, the control block diagram shown in FIG. 13 shows that the processing in the control system delay element calculation unit 511 and the vehicle model calculation unit 513 is It is the same, but the processing in the torsional angular velocity FB model calculation unit 514 is different.

The torsional angular velocity FB model calculation unit 514 of this embodiment is equivalent to the case where η=1 and Tf=0 in the processing of the torsional angular velocity FB model calculation unit 514 of the first embodiment shown in FIG. 5. That is, the equation (29) becomes the following equation.

According to the second embodiment of the present invention, the following effects can be obtained.

According to the control method of the second embodiment of the present invention, referring to FIG. 12, the loss consideration unit 121 that performs the loss consideration process (S101), which is a correction step, includes the FF compensation unit that performs the FF compensation process (S41). The target torque target value T _m ^* is input to 51 and is performed. By doing so, the input to the FF compensating unit 51 becomes a more accurate value, and therefore the FF compensating unit 51 further suppresses the drive shaft torsional vibration.

Further, according to the control method of the second embodiment of the present invention, referring to FIG. 12, the loss compensation unit 122 performs the loss compensation calculation process (S102) to calculate the final torque target value T _mf ^* . .. In an actual electric vehicle, the output value is reduced with respect to the command value to the motor 3 because of the torque loss. On the other hand, by performing the above-described loss compensation calculation process (S102), the reduction in the driving torque of the motor 3 is compensated, so that the influence of the torque loss of the motor 3 can be reduced.

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. Further, the above embodiments can be combined as appropriate.

1 Battery 2 Inverter 3 Motor 7 Reducer 8 Drive shaft (drive shaft)
501 FF compensation unit 512 Loss consideration unit 513 Vehicle model calculation unit 514 Torsional angular velocity FB model calculation unit 502 FB compensation unit 503 Compensation value addition unit 121 Loss consideration unit 122 Loss compensation unit

Claims (7)

A feedforward compensation step of performing a feedforward compensation process with respect to a target torque command value to the motor calculated based on the vehicle information of the electric vehicle,
A motor control step of controlling a motor connected to the drive wheels of the electric vehicle using the target torque command value after the feedforward compensation process,
The feedforward compensation step is
A correction step of correcting the target torque command value in consideration of torque loss from the motor to the drive shaft;
Using a vehicle model modeling the characteristics from the motor torque to the drive shaft torsion angular velocity, a pseudo drive shaft torsion angular velocity calculation step of calculating a pseudo drive shaft torsion angular velocity according to the target torque command value,
A torsional angular velocity feedback step of feeding back the pseudo drive shaft torsional angular velocity to the target torque command value .
A method for controlling an electric vehicle, comprising: A correction step of performing a correction in consideration of a torque loss from the motor to the drive shaft with respect to a target torque command value to the motor calculated based on vehicle information of the electric vehicle ,
A feedforward compensation step of performing feedforward compensation processing on the target torque command value corrected in the correction step ;
A loss compensation step of performing compensation according to the torque loss for the target torque command value after the feedforward compensation processing,
A motor control step of controlling the motor connected to the drive wheels of the electric vehicle using the target torque command value after the loss compensation processing,
The feedforward compensation step is
Using a vehicle model modeling the characteristics from the motor torque to the drive shaft torsion angular velocity, a pseudo drive shaft torsion angular velocity calculation step of calculating a pseudo drive shaft torsion angular velocity according to the target torque command value,
A torsional angular velocity feedback step of feeding back the pseudo drive shaft torsional angular velocity to the target torque command value .
A method for controlling an electric vehicle, comprising: A method for controlling an electric vehicle according to claim 1 or 2 , wherein
The torque loss includes a fluctuation component according to the torque generated in the motor,
A method for controlling an electric vehicle, comprising: The method of controlling an electric vehicle according to claim 1,
The torque loss includes a predetermined offset component,
A method for controlling an electric vehicle, comprising: It is a control method of the electric vehicle according to any one of claims 1 to 4 ,
The drive force transmission system of the vehicle model has a dead zone in which the motor torque is not transmitted to the drive shaft torque of the vehicle,
A method for controlling an electric vehicle, comprising: The control method for an electric vehicle according to claim 5 ,
The dead zone is a total sum of gear backlash amounts from the motor to the drive shaft. A feedforward compensating unit that performs a feedforward compensating process for a target torque command value to the motor calculated based on the vehicle information of the electric vehicle,
A motor control unit that controls the motor connected to the drive wheels of the electric vehicle using the target torque command value after the feedforward compensation,
The feedforward compensator is
A correction unit that performs correction on the target torque command value in consideration of a torque loss amount from the motor to the drive shaft,
Using a vehicle model that models the characteristics from the motor torque to the drive shaft torsion angular velocity, a pseudo drive shaft torsion angular velocity calculation unit that calculates the pseudo drive shaft torsion angular velocity based on the target torque command value,
And a torsional angular velocity feedback unit that feeds back the pseudo driving shaft torsional angular velocity to the target torque command value .
A control device for an electric vehicle, comprising:

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