JP6728632B2 - 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.

There is known a regenerative brake control device for an electric vehicle, which is provided with a setting unit that can arbitrarily set the regenerative braking force of the electric motor and regenerates the electric motor with the regenerative braking force set by the setting unit.

However, in an electric vehicle controlled by such a regenerative brake control device, in the torque transmission system in which torque is transmitted from the motor to the drive wheels, there are phase shifts in the motor and dead zones of the gear due to wheel characteristics. It has been known. Therefore, even if an electric vehicle is stopped by controlling the motor by directly using the target torque value for the motor calculated from the accelerator opening degree, the vehicle speed, etc., vibration of the natural vibration frequency component of the torque transmission system of the vehicle occurs. It may end up.

On the other hand, Patent Document 1 discloses a technique using an FF (feed forward) calculation unit that performs a filtering process for damping control. According to this technique, the FF calculation unit includes a linear filter that reduces a natural vibration frequency component of torque transmission of a vehicle, a filter that calculates a drive shaft torsion angle, a saturation function (limiter), and a wheel having a drive shaft torsion angle. It is composed of inertia and a filter that compensates for a phase shift due to tire frictional force. By using the FF calculation unit including such a saturation function, the dead zone characteristic due to the backlash of the gear is taken into consideration, so that the torsional vibration generated in the drive shaft can be suppressed.

JP, 2013-223373, A

In an actual electric vehicle, mechanical loss exists in the torque transmission path from the motor to the drive shaft, and this loss may act as torque disturbance. For example, an error occurs in the calculation result of the vehicle state quantity such as the drive shaft torsion angle in the filter processing, and torsional vibration occurs in the drive shaft. However, in Patent Document 1, since the mechanical loss of the torque transmission path is not taken into consideration, the torsional vibration generated in the drive shaft cannot be sufficiently suppressed.

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 according to the present invention is a control method for an electric vehicle that sets a target torque command value for a motor based on vehicle information and controls the motor connected to a drive wheel using the target torque command value. There is a correction step for correcting the target torque command value according to the torque loss from the motor to the drive shaft, and a dead zone where the motor torque is not transmitted to the drive shaft of the vehicle for the corrected target torque command value. And a motor control step of controlling the motor based on the target torque command value after the filter processing.

According to one aspect of the present invention, the filtering step of reducing the natural vibration frequency of the driving force transmission system of the vehicle and the correction step of considering the torque loss amount from the motor to the drive shaft are executed. By performing the correction step in addition to the filter processing step, it becomes possible to accurately obtain the vehicle state quantity of the control system that takes into account the torque loss amount, so even if there is a torque loss, the vibration of the drive shaft torque can be reduced. Can be suppressed.

FIG. 1 is a schematic configuration diagram of an electric vehicle controlled by the control method of the present invention. 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 diagram showing a vehicle model of an electric vehicle. FIG. 7 is a control block diagram of an example of the FF calculation unit. FIG. 8 is a control block diagram of another example of the FF calculation unit. FIG. 9 is a control block diagram of an example of the FB calculation unit. FIG. 10 is a control block diagram of an example of the FF calculation unit and the FB calculation unit. FIG. 11 is a diagram showing frequency characteristics of H(s). FIG. 12 is an explanatory diagram of a state of the electric vehicle.

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

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 for 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 current 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 current 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 transmits the drive force 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 driving wheels when the vehicle is running, and generates regenerative braking force and regenerative electric 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 S201, input processing 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 sum of the three-phase current values becomes zero, for example, iw may be calculated from iu and iv instead of being acquired by the sensor input.

The rotor phase α (electrical angle) [rad] of the motor 3 is acquired by a rotation sensor such as a resolver or an encoder. By differentiating the rotor phase α (electrical angle), the rotor angular velocity ω (electrical angle) [rad/s] is obtained. 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] can be obtained by multiplying the vehicle speed v [m/s] by a unit conversion coefficient (3600/1000) from [m/s] to [km/h]. .. 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 θ may be acquired by an accelerator opening 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 S202, basic target torque calculation processing is performed. The motor controller 5 sets the basic target torque command value T _m ^* based on the accelerator opening θ and the vehicle speed V using the table showing the relationship between the accelerator opening and the torque shown in FIG.

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 value of the accelerator opening θ. The motor controller 5 sets a torque obtained from the accelerator opening θ and the motor angular velocity ω _m using this table as a basic target torque command value T _m ^* . The rotation speed N [rpm] of the motor 3 can be converted from the motor angular velocity ω _m [rad/s].

In step S203, 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 basic 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 _m3 ^* is calculated. The details of the damping control calculation process will be described later with reference to FIG.

In step S204, a current command value calculation process is performed. Motor controller 5, the final torque value T _m3 ^* calculated in S203, the motor angular speed omega _m, from the DC voltage value Vdc, dq axis current target showing the target value of the current to flow to the motor 3 in a synchronous rotating coordinate The values id ^* and iq ^* are obtained. Specifically, the motor controller 5 determines the relationship between the DC voltage value Vdc, the motor angular velocity ω _m , the basic target torque command value T _m ^*, and the d-axis current target value id ^* and the q-axis current target value iq ^*. Is stored in advance, and the dq-axis current target values id ^* , iq ^* are obtained using this table.

In step S205, 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 S204 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 PWM signal obtained in S201 to S205 is used to operate ON/OFF of the switching element of the inverter 2. 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, the details of the vibration suppression control calculation process (S203) shown in FIG. 2 will be described with reference to FIGS. 4 and 5.

FIG. 4 is a flowchart of the vibration suppression control calculation process executed by the motor controller 5.

In the vibration suppression control calculation process, loss consideration process (S401), FF (feed forward) calculation process (S402), FB (feedback) calculation process (S403), compensation value addition process (S404), and loss compensation process ( S405) is performed.

In the present embodiment, the loss consideration process (S401) corrects the input value to the FF calculation process (S402) to an effective value in consideration of the decrease due to the torque loss. At the same time, the loss compensation process (S405) is performed on the output value from the compensation value addition process (S404), so that the reduction amount of the drive torque with respect to the command value due to the torque loss is compensated.

By performing the loss consideration process (S401) and the loss compensation process (S405) as described above, the electric vehicle is operated only by the FF calculation process (S402), the FB calculation process (S403), and the compensation value addition process (S404). Since the torque loss is taken into consideration, the vibration damping property can be further improved as compared with the case of suppressing the vibration.

Details of the processing in S401 to S405 will be described with reference to FIG.

FIG. 5 is a control block diagram of the vibration suppression control calculation processing. In this figure, a loss consideration unit 501 that executes a loss consideration process (S401), an FF calculation unit 502 that executes an FF calculation process (S402), an FB calculation unit 503 that executes an FB calculation process (S403), A compensation value addition unit 504 that performs a compensation value addition process (S404) and a loss compensation unit 505 that performs a loss compensation process (S405) are shown.

The loss consideration unit 501 corrects the basic target torque command value T _m ^* to a value that takes into account the loss of torque due to the torque loss from the motor 3 to the drive shaft 8. Specifically, the effective torque component T _m1 ^* that contributes to the rotational movement is calculated by the following equation.

As shown in the equation (1), the torque loss depends on the component (ηT _m1 ^* ) proportional to the magnitude of the torque due to the transmission efficiency of the transmission and the magnitude of the torque such as the static friction force. , And an offset component (T _f ) having a substantially constant magnitude. 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 direction opposite 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. Note that the torque transmission efficiency η and the offset torque T _f may be fixed values, but in order to more accurately consider the loss, the torque transmission efficiency η and the offset torque T _f change according to related parameters such as the motor angular velocity and the motor torque as necessary. You may let me.

The FF calculation unit 502 performs FF calculation processing (S402) on the effective torque component T _m1 ^* output from the loss consideration unit 501 and outputs the FF calculation unit output FF _out . The detailed configuration of the FF calculation unit 502 will be described later with reference to FIG. 7.

The FB calculation unit 503 is supplied with an FF calculation unit output FF _out which is a command value to the motor 3 and a motor angular velocity ω _m which is a response value of the motor 3. The FB calculation unit 503 obtains the deviation between the command value and the response value in the motor 3, and outputs the FB calculation unit output FB _out according to this deviation. The detailed configuration of the FB calculation unit 503 will be described with reference to FIGS.

The compensation value addition unit 504 adds the FF calculation unit output FF _out and the FB calculation unit output FB _out to generate the post-damping control torque command value T _m2 ^* .

The loss compensation unit 505 adds the torque loss from the motor 3 to the drive shaft to the post-damping control torque command value T _m2 ^* output from the compensation value addition unit 504. Specifically, the final torque target value _Tm3 ^* is calculated using the following formula.

In the equation (2) as well, similarly to the equation (1), η indicates the torque transmission efficiency (0≦η<1), and T _f indicates the torque offset component. Note that the relationship between the final torque target value T _m3 ^{* and} the post-damping control torque command value T _m2 ^{* in the} formula (2) is the effective torque component T _m1 ^* of the basic target torque command value T _m ^{* in the} formula (1). It is the opposite of the relationship. This is because the torque loss component is compensated by the equation (2) while the effective value in which the torque loss component is taken into consideration is calculated by the equation (1).

Here, the FF calculation unit 502 that performs the FF calculation process (S402) and the FB calculation unit 503 that performs the FB calculation process (S403) are used by a vehicle model that models the driving force transmission system of the electric vehicle. Designed. Therefore, a vehicle model showing the driving force transmission system of the electric vehicle will be described.

FIG. 6 is a diagram modeling a driving force transmission system of an electric vehicle.

Here, when the dead zone due to the backlash generated in the gear included in the driving force transmission system is expressed by the difference between the linear function and the saturation function, 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 of friction between tire and road surface N _al : Overall gear ratio r: Tire load radius ω _m : Motor angular velocity ω _w : Drive 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 Further, St(θ) in the equation (6) is a saturation function having the drive shaft torsional angle θ as a variable, and is expressed as follows.

Note that θ _BL is the gear backlash amount in the overall from the motor 3 to the drive shaft 8.

From the equations (3) to (8), the transfer characteristic from the motor torque T _m to the drive shaft torsion angle θ can be obtained by the following equation.

Note that Gt(s) and Fs(s) are transfer functions represented by the following equation.

However, each parameter in these equations is as follows.

Note that 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.

The drive shaft torque _Td can be expressed as follows from the equations (6) and (10).

Here, the normative response of the drive shaft torque is expressed by the following equation.

However, G _tm (s) is a transfer function represented by the following equation.

Note that ζ _m is the damping coefficient of the ideal model, and ω _m is the natural vibration frequency of the ideal model.

Here, when the torque command value T _m such that T _d =T _dm is obtained, the following equation is obtained.

However, G _INV is a transfer function represented by the following equation.

Here, the FF operation unit 502 can be designed by using the above equations (10) and (16).

FIG. 7 is an example of a control block diagram of the FF calculation unit 502.

In this figure, in the FF calculation unit 502, the FF calculation process is performed on the input effective torque component T _m1 ^* , and the result is output as the FF calculation unit output FF _out . In addition, the FF operation unit 502 includes a block 701 that filters G _INV (s), a block 702 that filters G _t (s), and a block 703 that is a saturation function shown in Expression (9). And a block 704 that performs a filter process of Fs(s) shown in Expression (12).

The linear filter G _INV (s) is a filter that reduces the natural vibration frequency component of the torque transmission of the vehicle. The filter G _tm (s) is a filter that calculates the drive shaft torsion angle. Further, the filter F _s (s) is a filter that compensates for the phase shift due to the wheel inertia of the drive shaft torsion angle and the tire frictional force.

Here, the equation (10) can be understood as follows. First, the motor torque T _m and the value obtained by performing the processing of the filter F _s (s) on the saturation function St(θ) indicated using the drive shaft twist angle θ are added. Then, a filter G _t (s) that calculates the drive shaft twist angle from the torque command value is processed for the added value to obtain the drive shaft twist angle θ.

Here, the motor torque T _m, which is the output value, corresponds to the FF calculation unit output FF _out . Therefore, as shown in FIG. 7, in the preceding stage of the block 702 which is the filter G _t (s), the output FF _out of the FF operation unit and the filter Fs( St(θ)·Fs(s) obtained by performing the process of (s) is added. Then, the added value is fed back and the processing of the filter G _t (s) is performed in the block 702, whereby the drive shaft torsion angle θ is obtained.

Further, the equation (16) can be understood as follows. First, the effective torque component T _m1 ^* and F _s (s)·St(θ) are added. Then, the processing of G _INV (s) is performed on the added value. Then, the motor torque T _m (corresponding to the FF calculation unit output FF _out ) is obtained by subtracting F _s (s)·St(θ) from the added value after the processing of G _INV (s).

Referring to FIG. 7, the output from block 704 is F _s (s)·St(θ). Therefore, in the preceding stage of the block 701 which is G _INV (s), the effective torque component T _m1 ^* and the output value from the block 704, F _s (s)·St(θ), are added. Then, the added value is input to the block 701, and the process of G _inv (s) is performed. Then, by subtracting F _s (s)·St(θ) output from the block 704 from the output value from the block 701 that is G _INV (s), the FF calculation unit output FF _out is obtained.

Further, the FF calculation unit 502 is not limited to the configuration shown in FIG. 7, and may have another configuration.

FIG. 8 is another example of a control block diagram of the FF calculation unit 502. In this block diagram, not the filter G _t (s) but the filter G _tm (s) that calculates the ideal response of the drive shaft torsion angle is used as the configuration of the FF calculation unit 502.

First, by substituting the equation (16) into the equation (10), the equivalent conversion can be performed into the following equation.

Comparing the equation (18) with the equation (10) that derives the configuration of FIG. 7, it can be seen that the motor torque T _m that is the FF calculation unit output FF _out is input to the filter G _t (s) of FIG. 7. In contrast, the effective torque component T _m1 ^* is input to the filter G _tm (s) in FIG.

Here, comparing the configuration of FIG. 8 with the configuration of FIG. 7, in FIG. 8, a block 801 that is a filter G _tm (s) is used instead of the block 702 that is a filter G _t (s). .. Then, to the block 801, not the output FF compensator output FF _out which is an output value but the effective torque component T _m1 ^* which is an input value is input.

Next, a method of calculating the FB calculation unit output FB _out output from the FB calculation unit 503 will be described.

When the transfer characteristics from the motor torque T _m to the motor angular velocity ω _m are obtained by Laplace transforming the expressions (3) to (8), the following expression is obtained.

The transfer functions G _p (s) and G _ps (s) are expressed by the following equations.

Note that G _p (s) is a linear plant model showing the transfer characteristic of the motor angular velocity ω _m with respect to the motor torque input to the electric vehicle, and G _ps (s) is the back of the motor angular velocity with respect to the gear backlash amount. This is a transfer function for obtaining a rush compensation amount.

However, each parameter in these equations is as follows.

Here, rearranging equation (20) can be expressed as equation (22).

Here, ζ _p is the damping coefficient of the drive torsional vibration system, and ω _p is the natural vibration frequency of the drive torsional vibration system.

Assuming that the vehicle model is a general vehicle, when the poles and zeros of the transfer function of equation (22) are examined, one pole and one zero show extremely close values. This corresponds to that α and β in equation (22) show extremely close values. Therefore, by performing pole-zero cancellation (approximates to α=β) in the equation (22), a (second-order)/(third-order) transfer characteristic G _p (s) as shown in the following equation is formed. be able to.

Here, it is preferable that vibration is reduced in the FB calculation unit output FB _out that is fed back. Therefore, the FB calculation unit output FB _{out is} further processed using the band pass filter H(s).

The details of the bandpass filter H(s) will be described later with reference to FIG.

The FB calculation unit 503 can be configured using such a linear plant model G _p (s), transfer function G _ps (s), and filter H(s).

FIG. 9 is a control block diagram of the FB calculation unit 503 and the compensation value addition unit 504.

The FB calculation unit 503 outputs the FB calculation unit output FB _out according to the difference between the motor angular velocity estimated value ω _me corresponding to the command value to the motor 3 and the motor angular velocity ω _m which is the response value from the motor 3. It has been demanded.

The equation (19) can be understood as follows. Transfer function G _p (s) processed for the motor torque T _m , and transfer function G _ps (s) processed for the saturation function St(θ) shown using the drive shaft torsion angle θ. And are added to obtain the motor angular velocity ω (motor angular velocity estimated value ω _me ).

Referring to FIG. 9, the post-damping control torque command value T _m2 ^* is input to the block 905 which is the linear plant model G _p (s). On the other hand, the saturation function St(θ) is input to the block 904 which is the transfer function G _ps (s). Then, the outputs from the block 904 and the block 905 are added to obtain the motor angular velocity estimated value ω _me .

Further, the processing related to the saturation function St(θ) is blocks 901 to 903. This is a configuration similar to blocks 702 to 704 of FIG. 7 derived by the equation (10). In FIG. 9, the saturation function St(θ) output from the block 902 is input to the block 904.

Then, the difference between the motor angular velocity estimated value ω _me which is the command value and the motor angular velocity ω _m which is the response value is calculated. By processing the transfer function H(s)/G _p (s) of the block 906 with respect to the difference, the FB calculation unit output FB _out is obtained. Then, the compensation value adder 504 adds the FF compensator output FF _out and the FB calculator output FB _out to obtain the post-damping control torque command value T _m2 ^* . The transfer function H(s) is set so that the difference between the denominator order and the numerator order is equal to or larger than the difference between the denominator order and the numerator order of the transfer function G _p (s).

Further, the FB calculation unit 503 may not be configured as shown in FIG. For example, paying attention to the fact that blocks 901 and 902 in FIG. 9 correspond to blocks 702 and 703 in FIG. 7, with respect to block 904, the limit value St of the drive shaft torsion angle from block 703, not from block 902. (Θ) may be input. The FB calculation unit 503 configured in this way is shown in FIG.

FIG. 10 is a block diagram of another example of the FF calculation unit 502, the FB calculation unit 503, and the compensation value addition unit 504.

In this figure, as compared with the configuration of FIG. 9, the blocks 901 to 903 are deleted in the FB operation unit 503, and the saturation function St(θ) output from the block 703 of the FF operation unit 502 is FB. It is input to the block 904 of the arithmetic unit 503. By doing so, the configurations of the FF calculation unit 502 and the FB calculation unit 503 can be simplified.

Here, the transfer function H(s) that is a bandpass filter will be described.

FIG. 11 is a diagram showing an example of the characteristic of H(s).

Referring to this figure, in H(s), the damping characteristics on the low-pass side and the high-pass 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). It has the following characteristics. For example, when H(s) is composed of a first-order high-pass filter and a first-order low-pass filter, and the frequency f _p is the torsional resonance frequency of the drive system, the transfer function H(s) has a k of an arbitrary value. The value can be configured as in the following formula.

However, each parameter is as follows.

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

FIG. 12 is a diagram showing a state of the electric vehicle. 12A shows a basic target torque command value T _m ^* , FIG. 12B shows a final target torque value T _m3 ^* , and FIG. 12C shows an electric vehicle. The longitudinal 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 vehicle becomes constant. The basic target torque command value T _m ^* , the final target torque value T _m3 ^* , and the vehicle longitudinal acceleration a in such a vehicle state are shown. The dotted line shows the case where the conventional damping control is being performed (the case where the loss consideration process and the loss compensation process are not being performed), and the solid line shows the case where the damping control of the present application is being performed. ing.

Referring to the target torque command value in FIG. 12A, since the accelerator pedal is not depressed until time t0, the basic 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 basic 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 basic 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 the present invention, since the disturbance due to the torque loss is taken into consideration, the misrecognition of the relative positional relationship of the gears of the speed reducer 7 is less likely to occur. 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 shown by the solid line in FIG. 9C, the vehicle longitudinal acceleration a changes smoothly, and it becomes difficult for the driver to feel uncomfortable vehicle behavior.

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

According to the control method of the electric vehicle of the present invention, the vibration damping property can be improved by performing the loss consideration process (S401) in consideration of the influence of the torque loss before the FF calculation process (S402). Specifically, as shown in FIG. 5, in the loss consideration unit 501, the torque from the motor 3 to the drive shaft 8 as shown in the equation (1) is compared with the basic target torque command value Tm ^* . A loss consideration process (S401) of performing correction according to the loss and calculating the effective torque component T _m1 ^* is performed.

Then, with respect to the effective torque component T _m1 ^* , the FF calculation processing by the FF calculation unit 502 including the block 703 that is a saturation function that models the dead zone in which the torque of the motor 3 is not transmitted to the drive shaft 8 of the vehicle (S402), Further, the FB calculation processing (S403) is performed by the FB calculation unit 503 having the filter H(s) that reduces the natural vibration frequency of the driving force transmission system of the vehicle. Then, the compensation value addition unit 504 adds the FF calculation unit output FF _out output from the FF calculation unit 502 and the FB calculation unit output FB _out output from the FB calculation unit 503 to obtain the torque after vibration suppression control. Calculate the command value T _m2 ^* . Then, the control process (S205) of the current flowing to the motor 3 is performed based on the torque command value T _m2 ^* after the vibration suppression control.

Here, in an actual electric vehicle, there is a torque loss between the torque generated by the motor 3 and the drive shaft 8. Therefore, for the basic target torque command value T _m ^* used in the FF calculation process (S401), the correction for calculating the effective component actually acting on the drive wheels in consideration of the torque loss is performed using the equation (1). To do. By doing so, the relative position of the gears that mesh with each other can be accurately obtained, so that the vehicle can be smoothly accelerated and decelerated.

In particular, as shown in FIG. 12, when re-accelerating in a decelerating state, overshoot of the final torque target value T _m3 ^* does not occur, so that the vehicle can be smoothly accelerated. ..

Further, according to the control method for the electric vehicle of the present invention, referring to FIG. 5, the compensation value addition unit 504 outputs the FF calculation unit output FF _out output from the FF calculation unit 502 and the FB calculation unit 503. The FB calculation unit output FB _out is added to obtain the post-damping control torque command value T _m2 ^* . Then, the loss compensation unit 505 performs a loss compensation process (S405) on the post-damping control torque command value T _m2 ^* to obtain the final torque target value T _m3 ^* .

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. Therefore, the torque loss is compensated using the equation (2) with respect to the post-damping control torque command value T _m2 ^* output from the compensation value adding unit 504. By doing so, the reduction in the drive torque of the motor 3 is compensated, so that the influence of the torque loss of the motor 3 can be reduced.

By using the FB calculation unit 503 in order to suppress the torque disturbance caused by the mechanical loss, it is possible to accelerate the convergence of the drive shaft torsional vibration that continues periodically. However, the FB calculation unit 503 cannot suppress the overshoot or the delay in rising that occurs due to the response of the drive shaft torque immediately after passing through the gear backlash, and can be suppressed by using the loss consideration unit 501. be able to.

Further, according to the control method of the electric vehicle of the present invention, as shown in the equations (1) and (2), in the loss consideration processing (S401), the magnitude of the drive torque of the motor 3 is changed. The torque loss between the changing component that changes and the predetermined off-setting component is taken into consideration. As described above, the torque loss in the actual motor 3 is accurately modeled, and the loss consideration process (S401) and the loss compensation process (S405) are performed, so that the acceleration and deceleration of the vehicle can be smoothly performed. it can.

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.

1 Battery 2 Inverter 3 Motor 7 Reducer 8 Drive shaft (drive shaft)
501 loss consideration unit 502 FF calculation unit 503 FB calculation unit 504 compensation value addition unit 505 loss compensation unit

Claims (4)

A method of controlling an electric vehicle that sets a target torque command value for a motor based on vehicle information, and controls a motor connected to driving wheels using the target torque command value,
A correction step of correcting the target torque command value according to the torque loss from the motor to the drive shaft;
With respect to the target torque command value after the correction, a filter processing step of performing a filter process for reducing the natural vibration frequency of the drive force transmission system of the vehicle having a dead zone in which the torque of the motor is not transmitted to the drive shaft of the vehicle,
Compensation step of performing compensation according to the torque loss for the target torque command value after the filter processing in the filter processing step,
Having a motor control step of controlling the motor based on the target torque command value compensated by the compensation step,
A method for controlling an electric vehicle, comprising: The method of controlling an electric vehicle according to claim 1,
The torque loss includes a fluctuation component according to the torque generated in the motor,
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 predetermined offset component,
A method for controlling an electric vehicle, comprising: A control device for an electric vehicle that sets a target torque command value for a motor based on vehicle information, and controls a motor connected to drive wheels using the target torque command value,
A correction unit that corrects the target torque command value according to the torque loss from the motor to the drive shaft;
With respect to the target torque command value after the correction, a filter processing unit that performs a filter process for reducing the natural vibration frequency of the driving force transmission system of the vehicle having a dead zone in which the torque of the motor is not transmitted to the drive shaft of the vehicle,
For the target torque command value after the filter processing by the filter processing unit, a compensation unit that performs compensation according to the torque loss,
Having a motor controller controlling the motor based on the target torque command value compensated by the compensation unit,
A control device for an electric vehicle, comprising:

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