JP2019170054A - Electric vehicle control method, and electric vehicle controller - Google Patents

Abstract

To suppress motor torque fluctuation.SOLUTION: An electric vehicle control method is a control method by which a torque command value according to vehicle information is calculated, and an electric vehicle comprising a motor, which is driven according to said torque command value, is controlled. This electric vehicle control method has: a first torque target value calculation step at which a first torque target value, which is a target value of an output torque of the motor, is calculated on the basis of vehicle information; a second torque target value calculation step at which a second torque target value, which is used for feedback control, is calculated on the basis of a motor rotation speed; a third torque target value calculation step at which a limit value is set to a value according to the first torque target value, and a third torque target value is generated on the basis of the second torque target value; and a torque command value calculation step at which a torque command value is calculated by addition of the first torque target value and the third torque target value. When an absolute value of the first torque target value is lower than a prescribed torque value at a limitation step, setting of a limit value according to the first torque target value is interrupted.SELECTED DRAWING: Figure 2

Description

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

  In the control method of the electric vehicle, the first torque target value corresponding to the vehicle information such as the operation amount of the accelerator pedal and the motor rotation speed is obtained, and depending on the difference between the actual value of the motor rotation speed and the estimated value. A second torque target value, which is a feedback component, is obtained, and the motor is controlled using the sum of the first torque target value and the second torque target value as a torque command value.

  However, in such a control method, when the first torque target value is small, the second torque target value fluctuates due to disturbance such as unevenness on the road surface on which the vehicle travels, and the sign of the torque command value is reversed. May cause abnormal noise in the reducer.

  Therefore, according to the technique disclosed in Patent Document 1, the second torque target value is limited by the limit values (upper limit value and lower limit value) corresponding to the first torque target value, whereby the first torque target value and the first torque target value are reduced. The sum with the 2 torque target value has the same sign as the first torque target value. By doing so, the torque command value is not reversed between positive and negative, and the occurrence of abnormal noise is suppressed.

JP 2012-075257 A

  However, in a vehicle that stops without performing creep travel when the accelerator pedal is not depressed, the first torque target value is zero on a flat road, so that the second torque target value is also zero. It will be restricted. For this reason, when the first torque target value is zero, feedback control is not performed, so even if torque ripple occurs on the motor output shaft, the ripple cannot be suppressed. Torque resulting from the torque ripple is transmitted to the tire via the drive shaft, causing fluctuations in the motor rotation speed and fluctuations in the motor torque. When this motor torque fluctuation is transmitted to the electric vehicle, there is a problem that vibration that is uncomfortable for the occupant occurs.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a method for controlling an electric vehicle that suppresses fluctuations in motor torque.

  One aspect of the method for controlling an electric vehicle according to the present invention is a method for controlling an electric vehicle that calculates a torque command value according to vehicle information and controls a motor according to the torque command value. The electric vehicle control method includes a first torque target value calculation step for calculating a first torque target value, which is a target value of the output torque of the motor based on the vehicle information, and a second used for feedback control based on the rotational speed of the motor. A second torque target value calculating step for calculating a torque target value; a limit value is set to a value corresponding to the first torque target value; and a third torque target value is generated based on the second torque target value A torque target value calculating step; and a torque command value calculating step of calculating a torque command value by adding the first torque target value and the third torque target value. In the limiting step, when the absolute value of the first torque target value is lower than the predetermined torque value, the setting of the limiting value according to the first torque target value is interrupted.

  According to one embodiment of the present invention, it is possible to suppress fluctuations in motor torque.

FIG. 1 is a block diagram of an electric vehicle controlled by the control method of the first embodiment. FIG. 2 is a block diagram illustrating the vibration suppression control unit and the motor. FIG. 3 is an explanatory diagram showing an equation of motion of the drive torsional vibration system. FIG. 4 is a graph showing the characteristics of H (s). FIG. 5 is a block diagram illustrating a vibration suppression control unit and a motor of a comparative example. FIG. 6 is a graph showing torque limiting characteristics. FIG. 7 is a graph showing torque limiting characteristics of the comparative example. FIG. 8A is a timing chart showing the relationship between the torque command value, the rotation speed, and the vehicle front-rear G in the comparative example. FIG. 8B is a timing chart showing the relationship between the torque command value, the rotational speed, and the vehicle front-rear G in the present embodiment. FIG. 9 is a block diagram illustrating a vibration suppression control unit and a motor according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an electric vehicle 100 according to the first embodiment.

  The electric vehicle 100 includes an accelerator opening sensor 1, a motor torque setting unit 2, a vibration suppression control unit 3, a motor torque control unit 4, a motor 5, a motor rotation angle sensor 6, a drive shaft 7, and drive wheels 8 and 9. Have.

  The accelerator opening sensor 1 is a sensor that detects the accelerator opening A according to the accelerator pedal operation of the user of the electric vehicle 100, and transmits the detected accelerator opening A to the motor torque setting unit 2.

The motor torque setting unit 2 is a first torque that is a target value of the motor torque based on an accelerator opening A detected by the accelerator opening sensor 1 and a rotation speed y detected by a motor rotation angle sensor 6 described later. A target value T ^* is obtained. Then, the motor torque setting unit 2 outputs the obtained first torque target value T ^* to the vibration suppression control unit 3.

As a specific example, the motor torque setting unit 2 stores in advance a map in which the accelerator opening A, which is vehicle information, the rotation speed y, and the ideal torque target value T _d ^* are associated with each other. The motor torque setting unit 2 reads the ideal torque target value T _d ^* corresponding to the input accelerator opening A and the rotational speed y using the map. Further, the motor torque setting unit 2 performs a filtering process having a transfer characteristic of Gm (s) / Gp (s) obtained by a vehicle model described later on the read ideal torque target value T _d ^* . Thus, the first torque target value T ^* is obtained.

  As will be described later, Gm (s) is a transfer characteristic in the ideal model of electric vehicle 100 with a torque command value as an input value and a motor rotation speed as an output value. Gp (s) is a transfer characteristic with the torque command value as an input value and the motor rotation speed as an output value in an actual vehicle model.

As another example, electrically powered vehicle 100 may have a host controller, and the host controller may determine first torque target value T ^* instead of motor torque setting unit 2. In such a case, the first torque target value T ^* is input to the vibration suppression control unit 3 from the host controller.

As will be described later with reference to FIG. 2, the vibration suppression control unit 3 calculates a motor torque command value T ^{′ *} according to the input of the first torque target value T ^* and the rotational speed y, and the motor torque command The value T ^{′ *} is output to the motor torque control unit 4.

The motor torque control unit 4 obtains an applied voltage so that the output torque of the motor 5 matches or follows the motor torque command value T ^{′ *} , and outputs the obtained applied voltage to the motor 5.

  The motor 5 generates torque according to the applied voltage from the motor torque control unit 4 and transmits the generated torque to the drive wheels 8 and 9 via the drive shaft 7.

Note that the functions of the motor torque setting unit 2, the vibration suppression control unit 3, and the motor torque control unit 4 may be realized by, for example, one or a plurality of microcomputers. In such a case, control is performed by executing a program stored in the microcomputer. Further, the motor 5 includes an inverter, and the inverter may be driven by a PWM signal generated in the motor torque control unit 4 according to the motor torque command value T ^{′ *} .

  FIG. 2 is a block diagram of a configuration including the vibration suppression control unit 3.

The vibration suppression control unit 3 outputs the motor torque command value T ^{′ *} to the adder 110 in response to the input of the first torque target value T ^* . In the adder 110, the disturbance torque d is input, the sum of the motor torque command value T ^{′ *} and the disturbance torque d is obtained, and the sum is output as a command value to the control block 120. The control block 120 outputs the rotational speed y of the motor 5 according to the input command value.

  The vibration suppression control unit 3 includes a motor rotation speed estimation block 30, a subtractor 31, a second torque target value setting block 32, a third torque target value setting block 33, and a motor torque command value calculation block 34. .

The motor rotation speed estimation block 30 transmits a transfer characteristic Gp (s) to a motor torque command value T ^{′ *} obtained by adding a third torque target value T ₃ ^{* as} a feedback component to the first torque target value T ^* . Then, the rotational speed command value y ^ is calculated. The motor rotation speed estimation block 30 outputs the rotation speed command value y ^ to the subtractor 31.

  The subtractor 31 calculates a deviation e from the motor rotational speed y output from the control block 120 from the rotational speed command value y ^ output from the motor rotational speed estimation block 30.

The second torque target value setting block 32 performs a process of H (s) / Gp (s) composed of the transfer characteristic Gp (s) and the transfer characteristic H (s) on the deviation e obtained by the subtractor 31. Then, the second torque target value T ₂ ^* is calculated.

  The transfer characteristic H (s) is set such that the difference between the denominator order and the numerator order is equal to or greater than the difference between the denominator order and the numerator order of the transfer characteristic Gp (s). As a result, the control system can be stabilized.

The third torque target value setting block 33 performs torque limitation on the second torque target value T ₂ ^* according to the first torque target value T ^* . Specifically, the third torque target value setting block 33 limited the second torque target value T ₂ ^* input from the second torque target value setting block 32 based on the limit value. The target value is output to the motor torque command value calculation block 34 as the third torque target value T ₃ ^* . The limit value is set to a value corresponding to the first torque target value T ^* , as will be described later, and the setting to the value corresponding to the first torque target value T ^* is interrupted under certain conditions. Is done.

The motor torque command value calculation block 34 is an adder, and the third torque target value T ₃ ^* output from the third torque target value setting block 33 and the first torque target calculated by the motor torque setting unit 2. The motor torque command value T ^{′ *} is calculated by adding the value T ^* . The motor torque command value calculation block 34 outputs the calculated motor torque command value T ^{′ *} to the motor rotation speed estimation block 30 and the adder 110.

Adder 110 adds disturbance torque d generated in the vehicle to motor torque command value T ^{′ *} calculated by motor torque command value calculation block 34, and outputs the added value to control block 120.

  The control block 120 controls the vibration suppression control unit 3 and the motor 5 and has a transfer function (transfer characteristic) Gp (s) characteristic. The control block 120 outputs the rotational speed y of the motor 5 in response to the input of the command value obtained by addition in the adder 110. The rotational speed y is measured by the motor rotational angle sensor 6 and is fed back to the subtractor 31 of the vibration suppression control unit 3.

  Next, the transmission characteristic Gp (s) determined by the model having the transmission characteristic of the output of the rotational speed y with respect to the input of the torque command value in the electric vehicle 100 will be described.

FIG. 3 is a diagram modeling the driving force transmission system of electric vehicle 100. In these drawings, the following parameters are shown.
J _m : Inertia of electric motor J _w : Inertia of driving wheel M: Vehicle mass K _D : Torsional rigidity of driving system K _T : Coefficient related to friction between tire and road surface N: Overall gear ratio r: Excess radius of tire ω _m : Angular speed T _{m of} electric motor: Motor torque T _D : Driving wheel torque ω _w : Driving wheel angular speed F: Force applied to vehicle V: Vehicle speed

  If these parameters are used, the following equation of motion is derived from the configuration of FIG.

From the equations (1) to (5), the transmission characteristic from the motor torque T _m to the drive shaft torsion angle θ is obtained as the following equation.

  However, each parameter in the equation (6) is as follows.

  When the poles and zeros of the transfer characteristic shown in equation (6) are examined, it can be approximated to the transfer characteristic of the following equation, and one pole and one zero show extremely close values. This corresponds to the fact that α and β in this equation show extremely close values. Therefore, the equation (6) can be expressed as the following equation.

  Therefore, by performing pole-zero cancellation (approximate α = β) in equation (15), a (second order) / (third order) transfer characteristic Gp (s) as shown in the following equation can be configured. .

  In order to realize the transfer characteristic Gp (s) represented by the equation (16) by microcomputer processing, for example, the following equation is obtained by performing z-transform using the equation (17) and discretizing.

  However, T shows sampling time.

  Next, H (s) which is a band pass filter will be described with reference to FIG.

  Since H (s) is a bandpass filter, it is a feedback element that reduces only vibration. Since H (s) has the characteristics shown in FIG. 4, the effect of reducing vibrations can be enhanced. That is, the bandpass filter H (s) has the same attenuation characteristics on the low-pass side and the high-pass side, and the torsional resonance frequency of the drive system is the central part of the passband on the logarithmic axis (log scale). It is preferable to set as follows.

For example, if H (s) is composed of a first-order low-pass filter and a high-pass filter, H (s) can be expressed as the following equation, assuming that the torsional resonance angular frequency of Gp (s) is ω _p. Can do.

  Here, in order to obtain k with the highest vibration damping effect in the equation (18), a configuration including the vibration damping control unit 3 ′ as shown in FIG. 5 will be examined.

5 is compared with the block diagram of the vibration suppression control unit 3 shown in FIG. 2, the third torque target value setting block 33 is deleted. Therefore, the second torque target value T ₂ ^* output from the second torque target value setting block 32 is output to the motor torque command value calculation block 34 as it is. In this block diagram, when the first torque target value T ^* is considered to be zero as a state in which vibration due to feedback torque is likely to occur, the following equations (19) to (22) are derived.

  In the following, the Laplace operator is omitted.

  Substituting equation (22) into equation (19), the response of the motor rotation speed to the disturbance torque d is expressed by the following equation.

In the equation (23), when the equations (17) and (18) are substituted into the transfer characteristic G _p (1−H (s)) from d to y, the following equation is obtained.

  A high damping effect means that no vibration is caused by the disturbance torque d. Therefore, if 2-k = 2ξp, the denominator and the numerator in the equation (24) are canceled out by zero, and the following equation: Thus, the transmission characteristics do not cause vibration.

  From the above, k that gives the highest vibration damping effect is expressed by the following equation.

  Substituting equation (26) into equation (18), H (s) is expressed by the following equation.

  G (s) and H (s) obtained in this way are used in the motor rotation speed estimation block 30, the second torque target value setting block 32, and the control block 120.

  FIG. 6 is a diagram illustrating a torque limiting characteristic. This torque limiting characteristic is used for the processing in the third torque target value setting block 33 shown in FIG.

When the predetermined torque is T _x , the upper limit is obtained when the first torque target value T ^* is smaller than the predetermined −T _x or larger than + T _x (T ^* <− T _x , + T _x <T ^* ). The value _Th is set to the absolute value of the first torque target value T ^* , and the lower limit value _Tl is set to a negative value obtained by inverting the sign of the absolute value of the first torque target value T ^* . That is, in this region, the limit value used for torque limitation is set to a value corresponding to the first torque target value T ^* .

On the other hand, when the first torque target value T ^* is larger than −T _x and smaller than + T _x (−T _x <T ^* <+ T _x ), the upper limit value _Th is set to T _x and the lower limit value T _l is set to -T _x. That is, in this region, setting of a value corresponding to the first torque target value T ^* of the limit value is interrupted. In the present embodiment, when the setting of the first torque target value T ^* value corresponding to the limit value is interrupted, the limit value has been described an example in which the absolute value is set to a predetermined T _x However, it is not limited to this. The limit value may be set to a value whose absolute value is larger than zero.

Note that T _x is preferably equal to the torque ripple amplitude of the motor 5. With such a T _x, it can be limited interruptions setting value corresponding to the first torque target value T ^* as described below. The torque ripple is, for example, torque pulsation generated by the interaction between magnet magnetic flux and current magnetic flux in the motor 5, and is a periodic disturbance including each mechanical angular order component (24th order, 48th order, 96th order). .

The third torque target value setting block 33 shown in FIG. 2 determines whether or not the second torque target value T ₂ ^* is in a range between the upper limit value _Th and the lower limit value T _l .

When the second torque target value T ₂ ^* is in the range between the upper limit value _Th and the lower limit value T _l of the torque limit value, the third torque target value setting block 33 sets the second torque target value T _2. ^The same value as ^* is output as the third torque target value T ₃ ^* .

If the second torque target value T ₂ ^* is not in the range between the upper limit value _Th and the lower limit value T _l of the torque limit value (T ₂ ^* <− T _l , + T _h <T ₂ ^* ), The torque limit value T ₂ ^{* is} limited by the upper limit value _Th or the lower limit value T _l . Specifically, when the second torque target value T ₂ ^* is larger than the upper limit value _{T h (+ T h <T} 2 *) , the third torque target value setting block 33, the upper limit value T _h 3 Output as torque target value T ₃ ^* . When the second torque target value T ₂ ^* is smaller than the lower limit value T ₁ (T ₂ ^* <− T _l ), the third torque target value setting block 33 sets the lower limit value T ₁ to the third torque target value T 1. Output as ₃ ^* .

  Below, the effect by performing the torque restriction | limiting shown by FIG. 6 like this embodiment is demonstrated.

  FIG. 7 is a diagram illustrating a torque limiting characteristic as a comparative example.

In the comparative example shown in FIG. 7, the third torque target value setting block 33 sets the upper limit value _Th and the lower limit value T _l according to the first torque target value T ^* regardless of the first torque target value T ^*. The second torque target value T ₂ ^{* is} set and limited by the upper limit value _Th and the lower limit value T _l . The upper limit value _Th is set to the absolute value of the first torque target value T ^* , and the lower limit value _Tl is set to a negative value obtained by inverting the sign of the absolute value of the first torque target value T ^* . For example, when the first torque target value T ^* is T _1a ^* is a positive value of the upper limit value is the absolute value of T _1a of the torque limit value (+ | T _1a |), and the lower limit value of the torque limit value the - (| | T _1a) the negative value of the absolute value of T _1a.

In the comparative example shown in this figure, the first torque target value T ^* , which is a hatched region in the figure, is larger than −T _{x when} compared with the torque limiting characteristic of the present embodiment shown in FIG. And there is a difference in a region smaller than + T _x (−T _x <T ^* <+ T _x ). In this region, in the comparative example, the upper limit value T _h is set to T _x and the lower limit value T _l is set to −T _x , that is, the limit value is set to a value corresponding to the first torque target value T ^*. . In contrast, in the present embodiment, the upper limit value T _h and the lower limit value T _l are each T _x, -T _x, setting a value corresponding to the first torque target value T ^* is interrupted.

Due to the torque limiting characteristic of the comparative example, the torque target value is as follows. For example, consider a case where the first torque target value T ^* is a negative value and the second torque target value T ₂ ^* is positive greater than the absolute value of the first torque target value T ^* . In such a case, the third torque target value T ₃ ^* to be limited to the absolute value of the ^* first torque target value T, the first torque target value T ^* and the third torque target value T ₃ ^* The sum does not become positive, and the sum does not differ in sign from the first torque target value T ^* .

That is, due to such a limitation of the comparative example, the absolute value of the third torque target value T ₃ ^* is smaller than the absolute value of the first torque target value T ^* . Thus, the signs of the first torque target value T ^* and the motor torque command value T ^{′ *} are the same before and after the motor torque command value calculation block 34 shown in FIG. Therefore, the direction of the torque generated in the motor 5 is the same in the motor torque command value T ^{′ *} and the first torque target value T ^* . As a result, the generation of rotational torque in the direction opposite to the rotational direction is suppressed, so that noise caused by gear meshing can be reduced.

However, in the comparative example, when the electric vehicle 100 stops without creeping on a flat road, the first torque target value T ^* is zero, so the second torque target value T ₂ ^* that suppresses vibration is also used. Therefore, if the torque limitation shown in FIG. 7 is performed, the third torque target value T ₃ ^* output from the third torque target value setting block 33 is limited to zero. Therefore, if feedback control does not function effectively and torque ripple occurs in electrically powered vehicle 100, ripple cannot be suppressed.

On the other hand, in the present embodiment, since the torque limitation shown in FIG. 6 is performed, when the first torque target value T ^* is zero and the second torque target value T ₂ ^* is a relatively small value. The setting of the limit value according to the first torque target value T ^* is interrupted, and the limit value is set to a predetermined T _x whose absolute value is greater than zero. For this reason, the third torque target value T ₃ ^*, which is the value limited by the limit value of the second torque target value T ₂ ^* , does not become zero, so that feedback control functions and torque ripple can be suppressed.

  Below, the effect derived | led-out by this embodiment is demonstrated using a simulation result.

  FIG. 8A shows a case in the comparative example, and FIG. 8B shows a case in the present embodiment.

  In each of FIG. 8A and FIG. 8B, the torque command value, the number of rotations of the motor 5, and the front and rear G of the electric vehicle 100 are shown with time from the top. In the case of the electric vehicle 100 as shown in FIG. 1, the torque ripple is rotational speed dependent and synchronizes with the torsional resonance of the drive shaft.

As shown in FIG. 8A, in the comparative example, since the feedback control is suppressed, the motor torque command value changes while pulsating, and vibration with a large pulsation width is generated as indicated by the rotational speed and front and rear G. On the other hand, in the present embodiment shown in FIG. 8B, the feedback control functions to reduce the pulsation width of the motor torque command value, so that the occurrence of vibration can be suppressed. Further, the predetermined torque T _x in FIG. 6, because it is equivalent to the torque ripple amplitude of the motor 5, when the torque ripple occurs, to the extent necessary for feedback control, according to the first torque target value T ^* Setting the limit value is interrupted. Therefore, since necessary feedback control is performed, the vibration suppression effect of torque ripple can be improved.

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

According to the vehicle control method of the first embodiment, the third torque target value setting block 33 performs torque limitation on the second torque target value T ₂ ^* used for feedback control. Then, in the motor torque command value calculation block 34, the first torque target value T ^* and the third torque target value T ₃ ^* which is the second torque target value T ₂ ^* subjected to torque limitation are added, The added value is used for controlling the motor 5. In the third torque target value setting block 33, as shown in FIG. 6, when the absolute value of the first torque target value T ^* exceeds the predetermined torque T _x is the upper limit value T _h and the lower limit value T _l is Although is set to a value corresponding to the first torque target value T ^*, if the absolute value of the first torque target value T ^* is below a predetermined torque T _x is the upper limit value T _h and the lower limit value T _l 1 The setting of the value corresponding to the torque target value T ^* is interrupted.

In this way, the first torque target value T, such as during stop ^* is when the zero corresponding to the limit value (upper limit value T _h and the lower limit value T _l) of the first torque target value T ^* Value setting is interrupted. Therefore, the second torque target value T ₂ ^* is not limited to zero according to the first torque target value T ^* . Thereby, even if the first torque target value T ^* is zero, the feedback control is performed, so that torque ripple can be suppressed.

According to the vehicle control method of the first embodiment, when the absolute value of the first torque target value T ^* is less than the predetermined torque T _x , the absolute value is greater than zero (the upper limit value _Th and the lower limit value). _Tl ) is set.

In this way, even when the first torque target value T ^* becomes zero, not limit (the upper limit value T _h and the lower limit value T _l) is zero, the third torque target value T ₃ ^* Is not zero. Thereby, even if the first torque target value T ^* is zero, the feedback control functions, so that torque ripple can be suppressed.

According to the vehicle control method of the first embodiment, the predetermined torque Tx is substantially equal to the amplitude of the torque ripple generated in the electric vehicle 100. Here, when in the region ^where the ^* first torque target value T is (-Tx <T ^* <Tx) is of a value corresponding to the first torque target value of the upper limit value T _h and the lower limit value T _l T ^* Since the setting is interrupted, feedback control functions in this region. Therefore, a predetermined torque Tx by substantially equal to the amplitude of the torque ripple, in the region where the torque ripple is generated ^{(-Tx <T * <Tx)} , the first torque target value of the upper limit value T _h and the lower limit value T _l T ^* Since the setting of the corresponding value is interrupted, feedback control is performed. By doing in this way, a torque ripple can be suppressed.

Further, when vibration exceeding the torque ripple occurs, the limit value is a value corresponding to the first torque target value T ^* , and therefore, similarly to the comparative example, the motor torque command value T ^{′ *} and the first torque target value. The sign of T ^* is the same and the rotation direction is the same. For this reason, generation of torque in the reverse rotation direction is suppressed, so that noise caused by gear meshing can be reduced.

(Second Embodiment)
In the first embodiment, as shown in FIG. 6, an example has been described in which a predetermined torque T _x that is a threshold at which setting of a value according to the first torque target value T ^* of the limit value is interrupted is fixed. . In the present embodiment, an example in which the predetermined torque T _x is variable will be described.

  FIG. 9 is a block diagram of a configuration including the vibration suppression control unit 3 of the second embodiment.

  This embodiment is different from the configuration of the first embodiment shown in FIG. 2 in that the rotational speed y output from the control block 120 is input to the third torque target value setting block 33.

  The third torque target value setting block 33 uses a torque limit characteristic as shown in FIG. 6 and a limit value as shown in FIG. 7 according to the magnitude of the rotational speed y. And switch.

  Here, in the low rotation region of the motor 5, torque ripple vibration is likely to occur due to resonance between the drive shaft and the torque ripple order component. Further, since the rotational speed fluctuation is small, the vibration torque pulsation in the case where there is a detection error in the motor rotational angle sensor 6 which is the rotational speed detection means becomes small. The error in the motor rotation angle sensor 6 is detected by this resolver because, for example, an angle detection error occurs in a resolver that is relatively inexpensive and generally used in motor angle detection means. An error that occurs when the rotation speed is detected by converting the angle may be considered.

When the rotation speed y is smaller than the predetermined rotation speed, it can be determined that the rotation speed region is low. Therefore, the third torque target value setting block 33 performs torque limiting using the torque limiting characteristics shown in FIG. 6, so that the setting of the value corresponding to the first torque target value T ^* of the limiting value is interrupted. Therefore, torque ripple can be suppressed by feedback control.

When the rotation speed y is larger than the predetermined rotation speed, it can be determined that the rotation speed region is high. In the high rotation region, the frequency of occurrence of torque ripple resonance is very low, but since the rotational speed fluctuation is large, vibrational torque pulsations due to detection errors of the motor rotation angle sensor 6 are likely to occur. Therefore, the third torque target value setting block 33 performs the torque limitation shown in FIG. 7, whereby the limitation value is set to a value corresponding to the first torque target value T ^* , and vibration torque pulsation can be suppressed. .

The predetermined rotational speed is set to a rotational speed at which the torsional frequency and torque ripple order component generated when the motor torque is transmitted to the drive shaft resonate. By setting in this way, only when the rotational speed y is lower than the predetermined rotational speed and there is a high possibility of occurrence of torque ripple due to resonance, the first torque target value T ^* as shown in FIG. Since the setting of the limit value is interrupted, feedback control is performed and vibration of torque ripple can be suppressed. On the other hand, when the rotational speed y is higher than the predetermined rotational speed and the vibrational torque pulsation is large, the limit value is a value corresponding to the first torque target value T ^* as in the torque limiting characteristic shown in FIG. And vibration torque pulsation is suppressed.

  In addition, the predetermined value may be variable and the state transition may have hysteresis or inclination.

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

According to the control method for the electric vehicle according to the second embodiment, the third torque target value setting block 33 generates a torque ripple caused by resonance in the low rotation region when the rotation speed y is smaller than the predetermined rotation speed. As shown in FIG. 6, when the second torque target value T ₂ ^* is close to zero as shown in FIG. 6, the setting of the value according to the first torque target value T ^* of the limit value is interrupted. Torque ripple can be suppressed.

  On the other hand, when the rotational speed y is larger than the predetermined rotational speed, a relatively large vibration torque pulsation occurs due to a detection error of the motor rotational angle sensor 6. Therefore, even if the torque is limited by the torque limiting characteristic shown in FIG. 7 and the feedback control is limited, vibrational torque pulsations caused by detection errors in the motor rotation angle sensor 6 can be suppressed.

As described above, in the low rotation region, the feedback control can be executed by interrupting the setting of the value corresponding to the first torque target value T ^* of the limit value, so that torque ripple can be suppressed. On the other hand, in a high rotation region, even if torque limitation is performed using a limit value corresponding to the first torque target value T ^* , a relatively large vibration torque caused by a detection error of the motor rotation angle sensor 6 is obtained. Generation of pulsation can be suppressed. Thus, the front-rear G generated in the electric vehicle 100 can be efficiently suppressed by selectively switching the control.

  According to the control method of the electric vehicle of the second embodiment, the third torque target value setting block 33 is driven by the torque of the motor 5 as the predetermined rotation speed which is a threshold used for switching the torque limitation in FIGS. The rotational frequency at which the torsional vibration frequency generated when transmitted to the shaft and the torque ripple order component resonate is set.

  By setting in this way, when there is a high possibility of resonance, the torque ripple shown in FIG. 7 can be performed to suppress torque ripple vibration. On the other hand, when the possibility of resonance is low, the torque limitation shown in FIG. 6 can be performed to suppress the occurrence of oscillatory torque pulsation due to the detection error of the motor rotation angle sensor 6.

(Modification)
In 2nd Embodiment, the example in which the torque limitation characteristic shown by FIG. 6 and FIG. 7 was switched was demonstrated. In this modification, an example in which the predetermined torque T _x is variably described will be described.

In this variation, the third torque target value setting block 33, to reduce the predetermined torque T _x as the rotation speed y increases, increasing the predetermined torque T _x as the rotation speed y decreases.

When the rotation speed y is small, a low rotation region torque ripple is likely to occur, so that torque ripple tends to be suppressed by the feedback control, by increasing the predetermined torque T _x, the first torque target value T ^* The area where the setting of the limit value according to is interrupted is widened. On the other hand, when the rotational speed y is large, the torque ripple is difficult to occur because of the high rotational speed region. Therefore, the predetermined torque T _x is reduced and the limit value is set according to the first torque target value T ^*. By narrowing the interrupted area, the occurrence of vibration torque pulsation is suppressed.

  According to this modification, the following effects can be obtained.

According to this modification, the third torque target value setting block 33, to reduce the predetermined torque T _x as the rotation speed y increases, increasing the predetermined torque T _x as the rotation speed y decreases.

By setting in this way, when the rotational speed y is small and the torque is likely to be generated in the low rotational range, the predetermined torque T _x is increased to correspond to the first torque target value T ^* of the limit value. Make it easier to interrupt the value setting. Thereby, torque ripple is easily suppressed by feedback control. On the other hand, when the rotation speed y is high and the torque ripple is less likely to occur, the predetermined torque T _x is decreased and the setting of the value according to the first torque target value T ^* of the limit value is interrupted. Since the torque is limited and the sum of the first torque target value and the second torque target value has the same sign as the first torque target value, the generation of abnormal noise is suppressed. Can do.

Depending on the rotational speed y, taking into account the frequency of occurrence of torque ripple and change a region to suppress feedback control of the torque ripple is performed, changing the predetermined torque T _x. Thus, by changing the region where the setting of the limit value of the value according to the first torque target value T ^* is interrupted, it becomes easier to suppress the torque ripple when the torque ripple occurrence frequency is relatively high.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent. Moreover, the said embodiment can be combined suitably.

DESCRIPTION OF SYMBOLS 1 Accelerator opening sensor 2 Motor torque setting part 3, 3 'Vibration suppression control part 4 Motor torque control part 5 Motor 6 Motor rotation angle sensor 7 Drive shaft 8, 9 Drive wheel 30 Motor rotation speed estimation block 31 Subtractor 32 2nd Torque target value setting block 33 Third torque target value setting block 34 Motor torque command value calculation block 36 block 100 Electric vehicle 110 Adder 120 Control block

Claims (7)

A method for controlling an electric vehicle that calculates a torque command value according to vehicle information and controls a motor according to the torque command value,
A first torque target value calculating step for calculating a first torque target value which is a target value of the output torque of the motor based on vehicle information;
A second torque target value calculating step for calculating a second torque target value used for feedback control based on the rotational speed of the motor;
A third torque target value calculating step for setting a limit value to a value corresponding to the first torque target value and generating a third torque target value based on the second torque target value and the limit value;
A torque command value calculating step of calculating the torque command value by adding the first torque target value and the third torque target value;
In the third torque target value calculating step, when the absolute value of the first torque target value is lower than a predetermined torque value, the setting of the limit value according to the first torque target value is interrupted. Control method. A control method for an electric vehicle according to claim 1,
In the third torque target value calculation step, when the absolute value of the first torque target value is less than a predetermined torque value, the limit value is set to a value greater than zero as the absolute value. Method. A method for controlling an electric vehicle according to claim 1 or 2,
The method for controlling an electric vehicle, wherein the predetermined torque value is substantially equal to an amplitude of a torque ripple of the motor. A method for controlling an electric vehicle according to claim 1 or 2,
The method for controlling an electric vehicle, wherein the predetermined torque value is set to be larger as the rotational speed of the motor is smaller. It is a control method of the electric vehicle according to any one of claims 1 to 4,
When the rotational speed of the motor exceeds a predetermined rotational speed, the limit value is set to a value according to the first torque target value;
A method for controlling an electric vehicle, wherein setting of a value corresponding to the first torque target value of the limit value is interrupted when the rotational speed of the motor is less than the predetermined rotational speed. A method for controlling an electric vehicle according to claim 5,
The electric vehicle control method, wherein the predetermined rotational speed is a rotational speed at which a torsional vibration frequency generated when torque of the motor is transmitted to a drive shaft and a torque ripple order component resonate. A control device for an electric vehicle having a sensor for acquiring vehicle information, a motor as a drive source, and a controller for controlling the motor,
The controller is
Calculating a first torque target value that is a target value of the output torque of the motor based on the vehicle information;
Calculating a second torque target value used for feedback control based on the rotation speed of the motor;
A limit value is set to a value corresponding to the first torque target value;
Generating a third torque target value based on the limit value and the second torque target value;
A torque command value is calculated by adding the first torque target value and the third torque target value;
A control device for controlling the motor in accordance with the torque command value,
When the absolute value of the first torque target value falls below a predetermined torque value, the control device for the electric vehicle interrupts the setting of the limit value according to the first torque target value.

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