Electric vehicle control method and electric vehicle control device

Abstract

Provided is a method for controlling an electric vehicle having a front motor for driving front wheels and a rear motor for driving rear wheels, wherein pitching of the electric vehicle is controlled by moving a driving force between the front wheels and the rear wheels. In this control method, a standard pitch response, which is a standard response related to pitching of the electric vehicle, is calculated on the basis of a driving force command value for commanding driving forces of the front wheels and the rear wheels, an actual pitch response, which is an actual response related to pitching of the electric vehicle, is acquired, and a driving force movement amount representing a driving force to be moved between the front wheels and the rear wheels is calculated on the basis of the standard pitch response and the actual pitch response. A correction driving force movement amount is calculated by subjecting the driving force movement amount to phase-advancing compensation processing for advancing a phase of a predetermined frequency band including a resonance frequency of pitching, a correction driving force command value is calculated by correcting the driving force command value using the correction driving force movement amount, and the front motor and the rear motor are driven on the basis of the correction driving force command value.

Description

Control method for electric vehicle and control device for electric vehicle

[0001] The present invention relates to a control method and a control device for an electric vehicle.

[0002] JP2013-240258A discloses a control method for suppressing vehicle vibrations caused by pitching motion in an electric vehicle using one motor as a drive source by performing a predetermined filtering process on a motor torque command value.

[0003] When a vehicle accelerates or decelerates, pitching occurs, which changes the vehicle's posture. In a four-wheel drive vehicle, where the front wheels and rear wheels are driven separately, the behavior of the pitch angle λ and pitch rate λ' can be controlled by adjusting the distribution of driving force between the front and rear wheels.

[0004] It is desirable that the pitch angle λ smoothly increases (decreases) in response to the acceleration (deceleration) of the vehicle without oscillating and converge to a constant value. It is also desirable that the pitch rate λ' increases in response to the acceleration (deceleration) of the vehicle and then converges to zero without oscillating. In other words, when controlling pitch behavior by adjusting the driving force distribution, it is desirable to suppress oscillatory changes in the pitch angle λ and pitch rate λ'. However, conventional pitch control may not be able to sufficiently suppress oscillatory changes in the pitch angle λ and pitch rate λ'.

[0005] An object of the present invention is to provide a control method for an electric vehicle and a control device for an electric vehicle that can better suppress oscillatory changes in pitch angle λ and pitch rate λ'.

[0006] One aspect of the present invention is a control method for an electric vehicle having a front motor that drives the front wheels and a rear motor that drives the rear wheels, in which pitching of the electric vehicle is controlled by transferring driving force between the front and rear wheels. The control method calculates a reference pitch response that is a reference response related to pitching of the electric vehicle based on a driving force command value that commands driving forces for the front and rear wheels, obtains an actual pitch response that is an actual response related to pitching of the electric vehicle, and calculates a driving force transfer amount that represents the driving force to be transferred between the front and rear wheels based on the reference pitch response and the actual pitch response. Then, a phase-lead compensation process is performed on the driving force transfer amount to advance the phase of a predetermined frequency band that includes the pitching resonance frequency, thereby calculating a corrected driving force transfer amount. The corrected driving force transfer amount is used to correct the driving force command value to calculate a corrected driving force command value, and the front motor and the rear motor are driven based on the corrected driving force command value.

[0007] FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle. FIG. 2 is a flowchart showing a control mode of the electric vehicle. FIG. 3 is a graph showing the relationship between the rotation speed and accelerator opening degree and the target driving force. FIG. 4 is a block diagram of driving force distribution processing. FIG. 5 is an explanatory diagram showing forces generated in the electric vehicle during acceleration. FIG. 6 is a block diagram showing a configuration for performing pitch angle control calculation processing. FIG. 7 is a block diagram showing the configuration of a reference pitch response calculation unit. FIG. 8 is a block diagram showing the configuration of a driving force transfer amount calculation unit. FIG. 9 is a Bode plot showing changes in gain and phase due to phase lead correction processing. FIG. 10 is a graph showing changes in longitudinal acceleration, pitch angle, pitch rate, etc. in a comparative example. FIG. 11 is a graph showing changes in longitudinal acceleration, pitch angle, pitch rate, etc. in this embodiment. FIG. 12 is a block diagram showing a configuration for performing pitch angle control calculation processing according to a modified example.

[0008] [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0009] Fig. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle 100. As shown in Fig. 1, the electric vehicle 100 is a four-wheel drive vehicle in which a front motor 21 drives front wheels 22 and a rear motor 31 drives rear wheels 32.

[0010] The electric vehicle 100 includes a front drive system 11 , a rear drive system 12 , a battery 13 , and a controller 14 .

[0011] The front drive system 11 is a system that drives front wheels 22 by a front motor 21. In addition to the front motor 21 and the front wheels 22, the front drive system 11 also includes a front inverter 23, a rotation sensor 24, a current sensor 25, and the like.

[0012] The front motor 21 is, for example, a three-phase AC synchronous motor, and is driven by AC power input from the front inverter 23. The output torque of the front motor 21 generates a driving force for the front wheels 22. Furthermore, when the front motor 21 is rotated by the front wheels 22, it generates so-called regenerative torque. This allows the front motor 21 to recover the kinetic energy of the electric vehicle 100 as electrical energy.

[0013] The front wheels 22 are a pair of drive wheels located at the front of the electric vehicle 100. The front wheels 22 are connected to the front motor 21 via a front reduction gear 26 and a drive shaft 27. In this embodiment, the front wheels 22 consist of a right front wheel and a left front wheel. However, since the right front wheel and the left front wheel are connected by the drive shaft 27 and driven integrally, in this embodiment, the right front wheel and the left front wheel are not distinguished from each other and are collectively referred to as the front wheels 22.

[0014] The front inverter 23 includes a pair of switching elements for each phase of the front motor 21. The front inverter 23 opens and closes these switching elements in response to a PWM (Pulse Width Modulation) signal input from the controller 14. As a result, the front inverter 23 converts DC power supplied from the battery 13 into AC power and inputs it to the front motor 21 to drive the front motor 21. The switching elements constituting the front inverter 23 are, for example, power semiconductor elements such as insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistors (MOS-FETs). During regenerative control, the front inverter 23 converts AC power generated by the front motor 21 into DC power and inputs it to the battery 13.

[0015] The rotation sensor 24 detects the rotor phase α of the front motor 21. ｆ Detect the rotor phase α ｆ is a so-called electrical angle [rad]. The rotation sensor 24 is, for example, a resolver or an encoder. The detected rotor phase α ｆ is input to the controller 14.

[0016] The current sensor 25 detects the currents (hereinafter referred to as three-phase currents) i flowing through the respective phases of the front motor 21. ｕｆ , i ｖｆ , i ｗｆ The three-phase current i of the front motor 21 is detected. ｕｆ , i ｖｆ , i ｗｆ is input to the controller 14.

[0017] The rear drive system 12 is a system that drives rear wheels 32 by a rear motor 31, and is configured symmetrically to the front drive system 11. Therefore, in addition to the rear motor 31 and rear wheels 32, the rear drive system 12 also includes a rear inverter 33, a rotation sensor 34, a current sensor 35, a rear reduction gear 36, a drive shaft 37, etc. These components that make up the rear drive system 12 function in the same way as the components of the front drive system 11. In other words, the rear wheels 32 are a pair of drive wheels located at the rear of the electric vehicle 100. The rear wheels 32 consist of a right rear wheel and a left rear wheel, but in this embodiment, these are not distinguished and the right rear wheel and the left rear wheel are collectively referred to as the rear wheels 32. The rear wheels 32 are second drive wheels in comparison with the front wheels 22, which are other drive wheels. The rotor phase of the rear drive system 12 detected by the rotation sensor 34 is "α ｒ The current flowing through each phase of the rear motor 31 detected by the current sensor 35 is "i ｕｒ , i ｖｒ , i ｗｒ "

[0018] The battery 13 is provided in common to the front drive system 11 and the rear drive system 12, and supplies power to drive the front motor 21 and the rear motor 31. During regenerative control, the battery 13 is charged by the regenerative power generated by the front motor 21 and the rear motor 31.

[0019] The controller 14 is a control device for the electric vehicle 100. The controller 14 is configured by one or more computers including, for example, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 14 is also programmed to control the front motor 21, the rear motor 31, and the like at a predetermined control period. For example, the controller 14 acquires various vehicle variables and generates PWM signals for driving the front motor 21 and the rear motor 31 based on these vehicle variables. The controller 14 then inputs the generated PWM signals to the front inverter 23 and the rear inverter 33, respectively, to drive the front motor 21 and the rear motor 31 in accordance with the vehicle variables.

[0020] The vehicle variables are parameters that represent the control state of the electric vehicle 100. For example, the controller 14 may use the rotor phase α of the front motor 21 as the vehicle variables. ｆ and three-phase current i ｕｆ , i ｖｆ , i ｗｆ , the rotor phase α of the rear motor 31 ｒ and three-phase current i ｕｒ , i ｖｒ , i ｗｒ In addition, the controller 14 acquires, for example, the accelerator opening A ｐｏ , the DC voltage V of the battery 13 ｄｃ , the rotation speed N of the front motor 21 ｆ , the rotation speed N of the rear motor 31 ｒ , and the pitch angle λ or pitch rate (pitch angular velocity) λ' are acquired as vehicle variables. ｐｏ is a parameter that represents the amount of accelerator pedal operation by the driver. Pitch rate λ' is the time rate of change of pitch angle λ. The vehicle variables can be detected appropriately as needed using, for example, a sensor (not shown). The vehicle variables can also be obtained by calculation.

[0021] 2 is a flowchart showing the control mode of the electric vehicle. As shown in FIG. 2, the controller 14 functions as an input processing unit, a basic target driving force calculation unit, a pitch angle control calculation unit, a vibration damping control calculation unit, a current command value calculation unit, and a current control calculation unit. Specifically, in step S201, the controller 14 executes input processing. The input processing is processing for acquiring vehicle information and the like required for calculations of various processes described below.

[0022] In step S202, the controller 14 executes a basic target driving force calculation process. ＊ and calculate the target driving force F ＊ is expressed as the first front wheel driving force command value F ｆ１ ＊ and the first rear wheel driving force command value F ｒ１ ＊ This is the process of distributing the

[0023] Target driving force F ＊ is a command value that determines the total driving force required for the electric vehicle 100, that is, the driving force F that should be generated in the electric vehicle 1 as a whole, and the accelerator opening A ｐｏ , and the rotation speed N [rpm] of the front motor 21 or the rear motor 31.

[0024] FIG. 3 shows the relationship between the rotation speed N and the accelerator opening A ｐｏ and the target driving force F ＊ In this embodiment, the controller 14 controls the rotation speed N of the front motor 21. ｆ As shown in FIG. 3, the controller 14 controls the engine speed and the accelerator opening A ｐｏ The target driving force F ＊ A map (accelerator opening - driving force map) is stored in advance, and by referring to this, the rotation speed and accelerator opening A ｐｏ Target driving force F according to ＊ Calculate the following.

[0025] First front wheel driving force command value F ｆ１ ＊is a command value that determines the driving force that should be generated at the front wheels 22 (hereinafter referred to as the driving force of the front wheels 22) out of the target driving force F. Similarly, the first rear wheel driving force command value F ｒ１ ＊ is a command value that determines the driving force to be generated at the rear wheels 32 (hereinafter referred to as the driving force of the rear wheels 32) out of the target driving force F. The controller 14 allocates the target driving force F ＊ is expressed as the first front wheel driving force command value F ｆ１ ＊ and the first rear wheel driving force command value F ｒ１ ＊ Distribute to.

[0026] 4 is a block diagram of the driving force distribution process S401. As shown in FIG. 4, the driving force distribution process S401 includes a front wheel driving force calculation process S402 and a rear wheel driving force calculation process S403. The front wheel driving force calculation process S402 calculates the target driving force F ＊ The distribution ratio K for the front wheels 22 is ｆ By multiplying the target driving force F ＊ to the first front wheel driving force command value F ｆ１ ＊ The rear wheel driving force calculation process S403 calculates the target driving force F ＊ The distribution ratio for rear wheels 32 is 1-K. ｆ ” to obtain the first rear wheel driving force command value F ｒ１ ＊ This is a process for calculating the distribution ratio K for the front wheels 22. ｆ is set in advance to a value between zero and one depending on the operating state of the electric vehicle 1, for example. ｆ " is the distribution ratio K for the front wheels 22 ｆ In this embodiment, for simplicity, K ｆ = 0.5.

[0027] When the basic target driving force calculation process is completed, the controller 14 executes pitch angle control calculation process in step S203 (see FIG. 2). The pitch angle control calculation process is a process for performing calculations to suppress pitching that occurs in (or has occurred in) the electric vehicle 100. Specifically, the pitch angle control calculation process is a process for performing calculations to suppress pitching that occurs in (or has occurred in) the electric vehicle 100. Specifically, the pitch angle control calculation process is a process for performing calculations to suppress pitch angle λ, pitch rate λ', or changes in pitch angle λ and pitch rate λ' (hereinafter referred to as pitch response) of the electric vehicle 100. ｆ１ ＊ and the first rear wheel driving force command value F ｒ１ ＊ By correcting the second front wheel driving force command value F ｆ２ ＊ and the second rear wheel driving force command value F ｒ２ ＊ The pitch angle control calculation process will be described in detail later. Hereinafter, the first front wheel driving force command value F ｆ１ ＊ and the first rear wheel driving force command value F ｒ１ ＊ is the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ and the second front wheel driving force command value F ｆ２ ＊ and the second rear wheel driving force command value F ｒ２ ＊ is the corrected driving force command value F ｆ２ ＊ , F ｒ２ ＊ In addition, the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ A normative pitch response calculated based on the above is referred to as a normative pitch response, and a pitch response that actually occurs in the electric vehicle 100 is referred to as an actual pitch response.

[0028] In step S204, the controller 14 executes a vibration suppression control calculation process. The vibration suppression control calculation process is a process for performing calculations to suppress vibrations, such as torsional vibrations, that occur in the driving force transmission system.

[0029] In the vibration suppression control calculation process, the controller 14 calculates the corrected driving force command value F ｆ２ ＊ , F ｒ２ ＊ is converted into a value equivalent to the motor torque based on the gear ratios and tire diameters of the front wheels 22 and the rear wheels 32, and the torque command value T ｆ ＊ and a torque command value T for the rear motor 31 ｒ ＊ The controller 14 also calculates the front rotor phase α ｆ The rotation speed N of the front motor 21 is calculated based on the above. ｆ Similarly, the controller 14 calculates the rear rotor phase α ｒ The rotation speed N of the rear motor 31 is calculated based on the above. ｒ Then, the controller 14 calculates the torque command values ​​T ｆ ＊ , T ｒ ＊ and the rotation speeds N of the front motor 21 and the rear motor 31. ｆ , N ｒ and calculates final motor torque command values ​​(hereinafter referred to as post-vibration suppression control motor torque command values) for the front motor 21 and the rear motor 31. The controller 14 drives the front motor 21 and the rear motor 31 based on these post-vibration suppression control motor torque command values, thereby suppressing vibrations that occur in the driving force transmission system, such as torsional vibrations of the drive shafts 27, 37, without sacrificing torque response. Note that if the electric vehicle 100 does not have drive shafts 27, 37 or if torsional vibrations and the like are suppressed by a mechanical mechanism, the vibration suppression control calculation process in step S204 may be omitted.

[0030] In step S205, the controller 14 executes a current command value calculation process. The current command value calculation process calculates the target value i of the d-axis current for the front motor 21 and the rear motor 31. ｄ ＊ and the target value of the q-axis current i ｑ＊ (Hereinafter, the dq axis current target value i ｄ ＊ , i ｑ ＊ Specifically, the controller 14 calculates the motor torque command value after vibration suppression control and the rotation speed N ｆ , N ｒ and the DC voltage V of the battery 13 ｄｃ Based on this, the dq axis current target value i ｄ ＊ , i ｑ ＊ The controller 14 calculates the motor torque command value after vibration suppression control, the rotation speed N ｆ , N ｒ , and the DC voltage V of the battery 13 ｄｃ and the dq axis current target value i ｄ ＊ , i ｑ ＊ Therefore, the controller 14 can refer to this map to obtain the d-axis current target values ​​i ｄ ＊ , i ｑ ＊ Calculate the following.

[0031] In step S206, the controller 14 executes a current control calculation process. The current control calculation process calculates the d-axis current target value i ｄ ＊ , i ｑ ＊ This is a process of calculating PWM signals for controlling the opening and closing of the switching elements of the front inverter 23 and the rear inverter 33 based on the above.

[0032] Specifically, the controller 14 controls the three-phase current i ｕｆ , i ｖｆ , i ｗｆ and three-phase current i ｕｒ , i ｖｒ , i ｗｒ and the front rotor phase α ｆ and rear rotor phase α ｒ and the d-axis current i of the front motor 21 and the rear motor 31 ｄ and q-axis current iｑ (Hereinafter, dq-axis current i ｄ , i ｑ Then, the controller 14 calculates the d-axis current i ｄ , i ｑ and the dq axis current target value i ｄ ＊ , i ｑ ＊ Based on the deviation of ｄ and the q-axis voltage command value v ｑ (Hereinafter, the dq axis voltage command value v ｄ , v ｑ Then, the controller 14 calculates the d-axis voltage command value v ｄ , v ｑ and the front rotor phase α ｆ and rear rotor phase α ｒ The controller 14 calculates three-phase voltage command values ​​for the front motor 21 and the rear motor 31 based on the three-phase voltage command values ​​and the DC voltage V of the battery 13. ｄｃ Based on the calculated PWM signals, the PWM signals to be input to the front inverter 23 and the rear inverter 33 are calculated. The front inverter 23 and the rear inverter 33 open and close their built-in switching elements in accordance with the PWM signals calculated in this way. As a result, the front motor 21 and the rear motor 31 are each driven at the desired torque determined by the post-vibration damping control motor torque command value.

[0033] The pitch angle control calculation process will be described in detail below.

[0034] 5 is an explanatory diagram showing forces acting on the electric vehicle 100 during acceleration. Here, the sprung mass (the portion above the suspension) of the body of the electric vehicle 100 (hereinafter simply referred to as the body) is assumed to be a rigid body. In this case, the electric vehicle 100 is subjected to a reaction force of the driving force of the electric vehicle 100 (hereinafter referred to as the driving force reaction force), an inertial force, and an instantaneous rotation angle θ determined by the operating state of the suspension. ｆ , θ ｒ The vertical force corresponding to the instantaneous rotation angle θ acts on the sprung mass of the vehicle body. ｆ , θ ｒThe vertical forces corresponding to the above are the so-called anti-dive force and anti-scatter force, or the pitching moment M λ The parameters used in the equations of motion and the like described below are as shown in Table 1 below.

[0035]

[0036] Pitching moment M λ is expressed by the following equation (1) using the above parameters. ｆ , θ ｒ Since the change in the instantaneous rotation angle θ is small during the stroke, it is treated as a known fixed value here. ｆ , θ ｒ is determined in advance by simulation, experiment, or the like based on the specific configuration of electric vehicle 100.

[0037]

[0038] The equation of motion around the center of rotation of pitching is expressed by the following equation (2). λ and coefficient K λ are expressed by the following equations (3) and (4).

[0039]

[0040] By Laplace transforming the above equation (2), the pitch angle λ is calculated as ｐλ Using (s), the transfer characteristic G can be expressed in the form shown in the following equation (5). ｐλ (s) is the driving force F of the front wheels 22 and the rear wheels 32 ｆ , F ｒ The transfer characteristic is from the pitch angle λ to the ｐλ (s) is expressed as a second-order response as shown in the following equation (6). λ is the damping coefficient and ω λ is the natural frequency. ｐλ (s) damping coefficient ζ λ and natural angular frequency ω λ is expressed by the following formula (7). ｆ and Mｒ is expressed by the following formula (8): M ｆ corresponds to the pitching moment generated by the front wheels 22, and M ｒ corresponds to the pitching moment generated by the rear wheels 32.

[0041]

[0042] The standard response of the pitch angle λ (hereinafter referred to as the standard pitch angle response) is expressed by the transfer characteristic G ｒλ (s) The transfer characteristic of the reference pitch angle response G ｒλ (s) is the transfer characteristic G ｐλ (s) damping coefficient ζ λ is set to 1, and the transfer characteristic does not have vibration characteristics. ｒλ The pitch angle (λ) calculated using (s) is set as the reference pitch angle λ of the electric vehicle 100. ｒ The detected or estimated value of the pitch angle λ actually generated in the electric vehicle 100 is referred to as the reference pitch angle λ. ｒ To distinguish it from the actual pitch angle λ, it is sometimes called the actual pitch angle λ.

[0043]

[0044] The pitch rate λ' (pitch angular velocity) is calculated by differentiating the pitch angle λ. Therefore, the pitch rate λ' is calculated by the transfer characteristic G ｐλ′ Using (s), the transfer characteristic G can be expressed in the form shown in the following equation (10). ｐλ′ (s) is the driving force F of the front wheels 22 and the rear wheels 32 ｆ , F ｒ The transfer characteristic G is the transfer characteristic from the pitch rate λ′ to the pitch rate λ′. ｐλ′ (s) is expressed by the following equation (11).

[0045]

[0046] The reference response of the pitch rate λ′ (hereinafter referred to as the reference pitch rate response) is expressed by the transfer characteristic G ｒλ′ The transfer characteristic of the reference pitch rate response G ｒλ′ (s) is the transfer characteristic G ｐλ′(s) damping coefficient ζ λ is set to 1, and the transfer characteristic does not have vibration characteristics. ｒλ′ The pitch rate (λ') calculated using (s) is set to the reference pitch rate λ of the electric vehicle 100. ｒ The detected or estimated value of the pitch rate λ' actually generated in the electric vehicle 100 is referred to as the reference pitch rate λ ｒ To distinguish it from the actual pitch rate λ′, it is sometimes called the actual pitch rate λ′.

[0047]

[0048] When a disturbance (hereinafter referred to as a pitch disturbance d) that causes the electric vehicle 100 to pitch occurs, the amount of driving force (hereinafter referred to as a driving force transfer amount) that should be transferred between the front wheels 22 and the rear wheels 32 to suppress the pitching is defined as F ｄ At this time, the corrected driving force command value F ｆ２ ＊ , F ｒ２ ＊ is the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ and the driving force movement amount F ｄ and is expressed by the following equation (13), for example.

[0049]

[0050] The pitch rate λ′ when the driving force is transferred between the front wheels 22 and the rear wheels 32 is expressed as F ｆ , F ｒ to F in equation (13) ｆ２ ＊ , F ｒ２ ＊ By substituting the above, it can be expressed by the following equation (14).

[0051]

[0052] Therefore, the driving force movement amount F ｄ The transfer characteristic from the pitch rate λ′ to the pitch rate λ′ is the inverse model of the reference pitch rate response (1 / G ｐλ′(s)), it is expressed by the following equation (15).

[0053]

[0054] Furthermore, the pitch rate λ′ when a pitch disturbance d occurs is expressed by the following equation (16) by adding the pitch disturbance d to equation (10). ｄ is a filter that determines the disturbance response (hereinafter referred to as the disturbance response filter) H ｄ (s), standard pitch rate λ ｒ If it can be expressed in the form of the following equation (17) using the pitch disturbance d and pitch rate λ′, the transfer characteristic (λ′ / d) from the pitch disturbance d to the pitch rate λ′ can be expressed by the following equation (18).

[0055]

[0056] The transfer characteristic (λ' / d) from the pitch disturbance d to the pitch rate λ' is expressed as the transfer characteristic G of the reference pitch rate response. ｒλ′ Similarly to (s), the reference disturbance response G ｒｄ (s), the disturbance response filter H ｄ (s) is expressed by the following equation (20): ｄ (s) is the natural angular frequency ω λ The filter can be configured with a bandpass filter in the

[0057]

[0058] Here, the driving force movement amount F ｄ Transfer characteristics from pitch rate λ' to pitch rate λ' (λ' / F ｄ ), and the transfer characteristic (λ' / d) from the pitch disturbance d to the pitch rate λ' have been explained. Following this, we will now consider the driving force transfer amount F ｄ Transfer characteristics from pitch angle λ to pitch angle λ (λ / F ｄ ), and the transfer characteristic (λ / d) from the pitch disturbance d to the pitch angle λ can be determined.

[0059] Fig. 6 is a block diagram showing a configuration for performing the pitch angle calculation process (S203). As shown in Fig. 6, the controller 14 includes, as components for performing the pitch angle calculation process (S203), a reference pitch response calculation unit 41, a deviation calculation unit 42, a driving force transfer amount calculation unit 43, a phase lead compensation unit 44, a command value correction unit 45, and a phase difference compensation unit 46. The reference pitch response calculation unit 41, the deviation calculation unit 42, the driving force transfer amount calculation unit 43, and the phase lead compensation unit 44 form a feedback compensator 47.

[0060] The reference pitch response calculation unit 41 calculates the reference pitch response (λ ) of the electric vehicle 100 based on the driving force command values ​​for the front wheels 22 and the rear wheels 32. ｒ and / or λ ｒ In this embodiment, the reference pitch response calculation unit 41 calculates the transfer characteristic G ｐλ′ By using (s), the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ Based on the normative pitch rate λ ｒ The specific configuration of reference pitch response calculation section 41 will be described in detail later.

[0061] The reference pitch response calculation unit 41 calculates the transfer characteristic G ｐλ Using (s), the standard pitch angle λ ｒ In this case, in this embodiment, the reference pitch rate λ ｒ Subsequent calculations using the actual pitch rate λ′ and the reference pitch angle λ ｒ and the actual pitch angle λ. ｆ２ ＊ , F ｒ２ ＊ The reference pitch response may be calculated based on:

[0062] The deviation calculation unit 42 acquires the actual pitch response and calculates the difference between the reference pitch response and the actual pitch response. ｒ ' and the actual pitch rate λ' deviation Δλ' (= λ ｒThe deviation calculation unit 42 functions as an actual pitch response acquisition unit that acquires the actual pitch response.

[0063] In principle, the driving force transfer amount calculation unit 43 calculates the driving force transfer amount F that suppresses the pitch response of the electric vehicle 100 based on the difference between the reference pitch response and the actual pitch response. ｄ In this embodiment, the driving force transfer amount calculation unit 43 calculates the transfer characteristic G ｐλ′ Inverse characteristic 1 / G of (s) ｐλ′ (s) to obtain the reference pitch rate λ ｒ Based on the deviation Δλ′ between the actual pitch rate λ′ and the actual pitch rate λ′, the driving force movement amount F ｄ The specific configuration of the driving force movement amount calculation unit 43 will be described in detail later.

[0064] The phase lead compensation unit 44 calculates the driving force movement amount F calculated by the driving force movement amount calculation unit 43. ｄ By performing a phase lead compensation process on the phase-corrected driving force movement amount F ｄ The phase lead compensation process calculates the resonance frequency f λ (=2πω λ The phase lead compensation process is a process of advancing the phase of a predetermined frequency band including the λｆｆ It is represented by (s).

[0065]

[0066] Transfer characteristic G of phase lead compensation processing λｆｆ (s) has a time constant τ ｆｆ１ , τ ｆｆ２ is a parameter that determines the frequency range (i.e., the above-mentioned predetermined frequency band) in which the phase is advanced by the phase lead compensation process. ｆｆ１ The upper limit of the specified frequency band changes depending on the time constant τ ｆｆ２ The lower limit of a given frequency band changes depending on the time constant τ ｆｆ２ is a coefficient α smaller than 1 (α<1) and a numerator time constant τ ｆｆ１ Using τ ｆｆ２ = α × τ ｆｆ１ It is expressed as the time constant τ ｆｆ１, τ ｆｆ２ The coefficient α is set in advance based on an experiment, a simulation, or the like.

[0067] In this embodiment, the transfer characteristic G λｆｆ Time constant τ (s) ｆｆ１ , τ ｆｆ２ is the torque (T ｆ , T ｒ ) until the actual pitch response (λ, λ') is generated. λ In this embodiment, τ ｆｆ１ =DT λ As a result, the predetermined frequency band in which the phase is advanced by the phase lead compensation process is at least the pitching resonance frequency f λ Specifically, the predetermined frequency band includes f Ｌ = 1 / τ ｆｆ１ <f λ <f Ｈ = 1 / τ ｆｆ２ In terms of angular frequency, the predetermined frequency band includes the range of f Ｌ / 2π=ω Ｌ <ω λ <ω Ｈ = f Ｈ In other words, the phase lead compensation process includes the range of at least the pitching resonance frequency f λ A predetermined frequency band (f Ｌ <f<f Ｈ ) Driving force movement amount F ｄ In this embodiment, the gain of the phase lead compensation process is set by setting the coefficient α, and the phase lag of the driving force movement amount F ｄ is adjusted so that the phase delay is approximately zero degrees (0 deg).

[0068] The pitching resonance frequency f λ is roughly determined by the vehicle mass and suspension characteristics (K ｆ , K ｒ , C ｆ , C ｒ ) is determined by the pitching resonance frequency f λvaries depending on the specific configuration of the electric vehicle 100. However, typically, the resonant frequency f λ is about 1 Hz or more and about 2 Hz or less (1≦f λ ≦2). Therefore, it is particularly preferable that the predetermined frequency band in which the phase is advanced by the phase lead compensation process includes this frequency band of 1 to 2 Hz. λｆｆ Time constant τ (s) ｆｆ１ , τ ｆｆ２ is the torque (T ｆ , T ｒ ) until the actual pitch response (λ, λ') is generated. λ If the frequency band is set based on the above, the frequency band of 1 to 2 Hz is usually included in the predetermined frequency band.

[0069] The command value corrector 45 calculates the correction driving force movement amount F ｄ ', the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ By correcting the driving force command value F ｆ２ ＊ , F ｒ２ ＊ In this embodiment, the command value corrector 45 calculates the first front wheel driving force command value F ｆ１ ＊ Correction driving force movement amount F ｄ ' to obtain the first rear wheel driving force command value F ｒ１ ＊ to the corrected driving force movement amount F ｄ By subtracting ', the corrected driving force command value F ｆ２ ＊ , F ｒ２ ＊ Calculate the following.

[0070] The phase difference compensator 46 calculates the corrected driving force command value F ｆ２ ＊ , F ｒ２ ＊ The corrected driving force command value F is set to reduce the phase difference between the front wheels 22 and the rear wheels 32. ｆ２ ＊ , F ｒ２ ＊Specifically, the phase difference compensator 46 includes a first phase difference compensator 48 and a second phase difference compensator 49.

[0071] The first phase difference compensator 48 has a transfer characteristic G ｒ (s) and transfer characteristic G ｒｒ (s) is used to perform phase difference compensation processing. ｒ (s) is the torque T of the front motor 21 ｆ The rotation speed N of the front motor 21 ｆ The transfer characteristic is G ｒｒ (s) is the torque T of the rear motor 31 ｒ The rotation speed N of the rear motor 31 ｒ The transfer characteristic is G ｒ (s), G ｒｒ (s) includes vibration suppression control, and the transfer characteristic G ｒ (s), G ｒｒ (s) represent the dynamic characteristics of the front wheels 22 and rear wheels 32, respectively.

[0072] In this embodiment, the first phase difference compensator 48 calculates the second front wheel driving force command value T ｆ２ ＊ , the transfer characteristic G ｒ Inverse characteristic 1 / G of (s) ｒ (s) and transfer characteristic G ｒｒ Phase difference compensation filter G configured by (s) ｒｒ (s) / G ｒ By processing the signals with (s), the phase difference between the front wheels 22 and the rear wheels 32 is reduced. ｒｒ (s) / G ｒ (s) is expressed by the following equation (22): In equation (22), the natural angular frequency ω ｐｆ is the resonant frequency f of the torsional vibration of the front drive system 11 (drive shaft 27) ｐｆ Similarly, the natural angular frequency ω ｐｒ is the resonant frequency f of the torsional vibration of the rear drive system 12 (drive shaft 37) ｐｒ Corresponds to.

[0073]

[0074] In addition, the transfer characteristic G ｒ(s) is expressed in the form shown in the following equation (23). Similarly, the transfer characteristic G ｒｒ (s) is expressed in the format shown in the following equation (24).

[0075]

[0076] The first phase difference compensator 48 also calculates the second rear wheel driving force command value T ｒ２ ＊ By correcting the second rear wheel driving force command value T ｒ２ ＊ Phase difference compensation filter G ｒ (s) / G ｒｒ (s) is the transfer characteristic G ｒｒ Inverse characteristic 1 / G of (s) ｒｒ (s) and the transfer characteristic G ｒ (s)

[0077] The second phase difference compensator 49 is a compensator for the torque T ｆ The delay time τ from the actual pitch response (λ, λ') ｆ and the torque T of the rear motor 31 ｒ The delay time τ from the actual pitch response (λ, λ') ｒ The difference Δτ ｆｒ In this embodiment, the second phase difference compensator 49 performs the phase difference compensation process based on the delay time τ ｆ , τ ｒ The corrected driving force command value with the smaller delay is calculated as the difference Δτ ｆｒ By delaying the correction driving force command value F ｆ２ ＊ , F ｒ２ ＊ For example, the phase difference of τ ｆ <τ ｒ When the second phase difference compensator 49 determines the second front wheel driving force command value F ｆ２ ＊ The phase difference Δτ ｆｒ Conversely, the delay is determined by τ ｆ >τ ｒ When the second phase difference compensator 49 determines the second rear wheel driving force command value F ｒ２ ＊ The phase difference Δτｆｒ The delay time is τ ｆ , τ ｒ is determined in advance based on the specific configuration of the electric vehicle 100. Therefore, the target and correction amount of the phase difference compensation process by the second phase difference compensator 49 are determined in advance based on experiments or simulations.

[0078] 7 is a block diagram showing the configuration of reference pitch response calculation unit 41. As shown in FIG. 7, reference pitch response calculation unit 41 includes dead time processing units 51 and 52, filter processing units 53 and 54, pitching moment multiplication units 55 and 56, an adder 57, a filter processing unit 58, and a dead time processing unit 59.

[0079] The dead time processing units 51 and 52 calculate the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ Depending on the dead time from the input to the occurrence of the pitch response, the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ Here, the dead time processor 51 adjusts the phase of the delay time τ ｆ Based on the first front wheel driving force command value F ｆ１ ＊ The dead time processor 51 adjusts the phase of exp(-τ ｆ Similarly, the dead time processor 52 calculates the delay time τ ｒ Based on the first rear wheel driving force command value F ｒ１ ＊ The dead time processor 52 adjusts the phase of exp(-τ ｒ s).

[0080] The filter processing unit 53 has a transfer characteristic G ｒ (s) to calculate the first front wheel driving force command value F ｆ１ ＊ Similarly, the filter processing unit 54 filters the transfer characteristic G ｒｒ (s) to calculate the first front wheel driving force command value F ｒ１ ＊ In this way, the filter processing units 53 and 54 take into consideration the delay (dead time) caused by vibration suppression control in the calculation of the reference pitch response.

[0081] The pitching moment multiplication unit 55 calculates the first front wheel driving force command value F ｆ１ ＊ In contrast, the pitching moment M ｆ Similarly, the pitching moment multiplication unit 56 multiplies the first front wheel driving force command value F ｒ１ ＊ In contrast, the pitching moment M generated by the rear wheel 32 ｒ Multiply by.

[0082] The adder 57 calculates the pitching moment M ｆ The first front wheel driving force command value F ｆ１ ＊ and pitching moment M ｒ The first rear wheel driving force command value F ｒ１ ＊ Add.

[0083] The filter processing unit 58 calculates a reference pitch response using the output of the adder 57. In this embodiment, the filter processing unit 58 calculates a transfer characteristic G ｒλ′ By applying (s), the reference pitch rate λ ｒ ' is calculated.

[0084] The dead time processing unit 59 calculates a delay time τ ｆ , τ ｒ Dead time τ due to factors not included in ｓｅｎ The dead time processor 59 adjusts the phase of the reference pitch response output by the filter processor 58 in accordance with exp(-τ ｓｅｎ s).

[0085] As described above, the reference pitch response calculation unit 41 calculates the reference pitch response based on the formula (10) or the formula (5) in principle. In this embodiment, the reference pitch response calculation unit 41 includes, as described above, particularly the dead time processing units 51, 52, and 59. In this way, in the calculation of the reference pitch response, the dead time τ ｆ , τ ｒ , τｓｅｎ By taking this into consideration, the phase shift between the reference pitch response and the actual pitch response is reduced. As a result, the driving force shift amount F to be corrected later in the phase lead compensation unit 44 is ｄ This allows the phase shift (phase delay) to be reduced in advance.

[0086] Fig. 8 is a block diagram showing the configuration of the driving force movement amount calculation unit 43. As shown in Fig. 8, the driving force movement amount calculation unit 43 calculates the reference pitch response λ in accordance with the above-mentioned equation (17). ｒ The deviation Δλ′ between the actual pitch rate λ′ and the driving force shift amount F ｄ In this embodiment, the driving force movement amount calculation unit 43 calculates H ｄ (s) / G ｐλ′ (s) and the output of the filter 61 is 1 / (M ｆ -M ｒ ) and a multiplier 62 that multiplies

[0087] The deviation Δλ between the standard pitch angle λr and the actual pitch angle λ is used to calculate the driving force movement amount F ｄ When calculating the driving force movement amount, the filter 61 of the driving force movement amount calculation unit 43 calculates G ｐλ′ G instead of (s) ｐλ Using (s), H ｄ (s) / G ｐλ It is configured to have the properties of (s).

[0088] The operation of the pitch control performed by the electric vehicle 100 configured as described above will now be described.

[0089] 9A and 9B are Bode diagrams showing changes in gain and phase due to phase lead compensation processing. FIG. 9A shows gain versus frequency, and FIG. 9B shows phase versus frequency. In FIG. 9, the dashed lines show gain and phase in a comparative example, and the solid lines show gain and phase in this embodiment. In the comparative example, the driving force movement amount F ｄ 10 is an example in which no phase lead compensation processing is performed on the phase lead signal (i.e., the phase lead compensation unit 44 is not provided).

[0090] As shown by the broken line in FIG. 9B, the driving force movement amount F calculated by the driving force movement amount calculation unit 43 ｄIf no phase lead compensation process is performed, the pitching resonance frequency f λ A predetermined frequency band (f Ｌ <f<f Ｈ ) in which the driving force movement amount F ｄ Therefore, the phase of the driving force movement amount F ｄ is used as it is to obtain the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ When correcting for , the actual pitch response may not perfectly track the intended pitch response.

[0091] In contrast to this, in this embodiment, as shown by the solid line in Figure 9A, by introducing phase lead compensation, the gain increases in the predetermined frequency band and the higher frequency bands thereafter. And, as shown by the solid line in Figure 9B, by the phase lead compensation process, the pitching resonance frequency f λ A predetermined frequency band (f Ｌ <f<f Ｈ ) in which the driving force movement amount F ｄ In this way, the phase delay of the corrected driving force movement amount F ｄ ' to obtain the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ When the pitch response is corrected, it becomes easier for the actual pitch response to follow the intended pitch response than in the comparative example. Specifically, this is as follows.

[0092] 10A and 10B are graphs showing the transition of the longitudinal acceleration, pitch angle, pitch rate, etc. in a comparative example. ｆ , and the torque T of the rear motor 31 ｒ FIG. 10B shows the acceleration A ｃ (Longitudinal acceleration) and (C) of the front motor 21. ｆ FIG. 10(D) shows the rotation speed N ｒ 10(E) shows the pitch angle λ. And FIG. 10(F) shows the pitch rate λ'. Here, the vehicle moves from a stopped state to time t１ The figure illustrates a scene in which the accelerator pedal is depressed and the electric vehicle 100 accelerates (starts). ｆ is 0.5 (front wheels:rear wheels = 50:50). The dashed lines in Figures 10(A) to 10(F) show the transition of each parameter when the driving force distribution between the front wheels 22 and the rear wheels 32 is fixed at 50:50 and no driving force transfer is performed, i.e., when pitch control is not performed.

[0093] In the comparative example, the driving force movement amount F ｄ Using the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ That is, in the comparative example, the driving force movement amount F ｄ Although the phase advance processing is not performed for the time t １ When the accelerator pedal is depressed and the electric vehicle 100 pitches, as shown in FIG. 10B, the accelerator opening A ｐｏ Acceleration A according to ｃ While the torque T ｆ , T ｒ and rotation speed N ｆ , N ｒ changes compared to the case where pitch control is not performed (dashed line). As a result, as shown in FIG. 10(E), in the comparative example, the overshoot of the pitch angle λ is reduced compared to the case where pitch control is not performed (dashed line). Also, as shown in FIG. 10(F), in the comparative example, the oscillatory behavior (amplitude) of the pitch rate λ' is suppressed compared to the case where pitch control is not performed (dashed line). In other words, in the comparative example, the pitch response that is likely to be uncomfortable for the driver is reduced compared to the case where pitch control is not performed.

[0094] However, the ideal behavior of the pitch angle λ when the electric vehicle 100 accelerates is to smoothly increase to a constant pitch angle λ according to the acceleration and then converge. In contrast, as shown in FIG. 10(E), in the comparative example, the pitch angle λ increases at time t ２The increase subsides around this time, then increases again and converges to the final value. Therefore, there is room for improvement in the behavior of the pitch angle λ by the pitch control in the comparative example.

[0095] Furthermore, the ideal behavior of pitch rate λ' when electric vehicle 100 accelerates is one in which it increases in response to acceleration and then converges to zero as smoothly and quickly as possible. In contrast, as shown in FIG. 10(F), in the comparative example, the behavior of pitch rate λ' is still oscillatory and converges slowly. For this reason, there is room for improvement in the behavior of pitch rate λ' obtained by pitch control in the comparative example.

[0096] 11A to 11F are graphs showing the transition of longitudinal acceleration, pitch angle, pitch rate, etc. in this embodiment. The parameters shown in FIGS. 11A to 11F are the same as those in FIGS. 10A to 10F. Also in FIG. 11A, the transition of longitudinal acceleration, pitch angle, pitch rate, etc. from a stopped state to time t １ The figure shows a scene in which the accelerator pedal is depressed and the electric vehicle 100 accelerates (starts). ｆ is 0.5 (front wheels:rear wheels = 50:50). The dashed lines in Figures 11(A)-(F) are the same as the dashed lines in Figures 10(A)-(F), and show the transition of each parameter when pitch control is not performed.

[0097] In this embodiment, the corrected driving force movement amount F ｄ ' to obtain the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ Therefore, at time t １ When the accelerator pedal is depressed and the electric vehicle 100 pitches, as shown in FIG. 11(B), the accelerator pedal opening A ｐｏ Acceleration A according to ｃ While the torque T ｆ , T ｒ and rotation speed N ｆ , N ｒ The change in these parameters is compared with the case where pitch control is not performed (broken line). ｄ10A, 10B, and 10C, and is different from the comparative example (FIGS. 10A, 10C, and 10D) described above, due to the phase lead compensation processing being performed on the signal.

[0098] As a result, as shown in FIG. 11(E), in this embodiment, the pitch angle λ increases more smoothly than in the comparative example (FIG. 10(E)), and converges to a constant value in response to acceleration. Also, as shown in FIG. 11(F), in this embodiment, the pitch rate λ' has reduced oscillatory components compared to the comparative example (FIG. 10(F)), and after increasing in response to acceleration, it converges smoothly and quickly. That is, in this embodiment, the pitch response is closer to the ideal pitch response than in the comparative example.

[0099] 10 and 11 illustrate a scene in which the electric vehicle 100 accelerates, but the present invention is not limited to this. In the pitch control according to this embodiment, even in a scene in which the electric vehicle 100 decelerates, the behavior of the pitch angle λ and the pitch rate λ′ approaches an ideal behavior with less vibration than in the comparative example.

[0100] 12 is a block diagram showing a configuration for performing the pitch angle control calculation process (S203) according to a modified example. As shown in FIG. 12, the controller 14 can include a feedforward compensator 71 (FF compensator) in addition to the feedback compensator 47. The feedforward compensator 71 adjusts the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ In this way, even when the feedforward compensator 71 is used in combination, the feedback compensator 47 corrects the basic driving force command value F ｆ１ ＊ , F ｒ１ ＊ As in the above embodiment, the driving force movement amount F ｄ and the correction driving force movement amount F ｄ As a result, even when the feedforward compensator 71 is used, oscillatory changes in the pitch angle λ and pitch rate λ' are suppressed.

[0101] As described above, the control method for an electric vehicle according to the above embodiment and modified example is a control method for an electric vehicle 100 having a front motor 21 that drives the front wheels 22 and a rear motor 31 that drives the rear wheels 32, in which pitching of the electric vehicle 100 is controlled by transferring driving force between the front wheels 22 and the rear wheels 32. In this control method, a driving force command value (F ｆ１ ＊ , F ｒ１ ＊ ), the reference pitch response (λ ｒ ′ or λ ｒ ) to obtain the actual pitch response (λ′ or λ), which is the actual response to pitching, and the reference pitch response (λ ｒ ′ or λ ｒ ) and the actual pitch response (λ' or λ), a driving force transfer amount F representing the driving force to be transferred between the front wheels 22 and the rear wheels 32 is calculated. ｄ Then, the driving force movement amount F ｄ whereas the pitching resonance frequency f λ A predetermined frequency band (f Ｌ <f<f Ｈ ) is subjected to a phase lead compensation process to advance the phase of the corrected driving force movement amount F ｄ ' and corrected driving force movement amount F ｄ ' to obtain the driving force command value (F ｆ１ ＊ , F ｒ１ ＊ ) is corrected to obtain the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) and calculates the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) to drive the front motor 21 and the rear motor 31.

[0102] In this way, the driving force movement amount F ｄ The phase lead compensation process is performed on the pitching resonance frequency f λ A predetermined frequency band (f Ｌ <f<f Ｈ) the phase of the corrected driving force movement amount F ｄ When pitch control is performed using the pitch angle λ and pitch rate λ', the oscillations of the pitch angle λ and pitch rate λ' can be suppressed. In other words, compared to conventional pitch control, the behavior of the pitch angle λ and pitch rate λ' approaches ideal behavior with reduced oscillations.

[0103] In the control method for the electric vehicle according to the above embodiment and modification, the torque (T ｆ , T ｒ ) to the actual pitch response (λ' or λ) (τ ｆ or τ ｒ ), the width of the predetermined frequency band in the phase lead compensation process (f Ｌ and f Ｈ ) to set the

[0104] In this way, the characteristics of the phase lead compensation process (G λｆｆ (s)) as torque T ｆ , T ｒ delay time from the actual pitch response (τ ｆ or τ ｒ ), the predetermined frequency band in the phase lead compensation process is set based on the pitching resonance frequency f λ and the driving force movement amount F ｄ As a result, the oscillations of the pitch angle λ and the pitch rate λ' are easily suppressed.

[0105] In the phase lead compensation process in the control method for an electric vehicle according to the above embodiment and modification, at least the resonant frequency f λ In this case, the driving force movement amount F ｄ The driving force movement amount F ｄ Advance the phase of

[0106] In this way, the driving force movement amount F ｄ The phase delay of the pitching resonance frequency f λ The driving force movement amount F ｄ When a phase lead compensation process is performed on the pitch angle λ and the pitch rate λ', it is particularly easy to suppress the oscillations of the pitch angle λ and the pitch rate λ'.

[0107] In the control method for an electric vehicle according to the above embodiment and modification, the predetermined frequency band (f Ｌ <f<f Ｈ ) includes at least the range of 1 Hz to 2 Hz.

[0108] A typical pitching resonance frequency f of the electric vehicle 100 λ is about 1 to 2 Hz, so as described above, by the phase lead compensation process, the driving force movement amount F ｄ By advancing the phase of the pitch angle λ and the pitch rate λ', it is particularly easy to suppress the oscillations of the pitch angle λ and the pitch rate λ'.

[0109] In the control method for the electric vehicle according to the above embodiment and modification, the torque (T ｆ , T ｒ ) to the actual pitch response (λ' or λ) (τ ｆ or τ ｒ ) based on the reference pitch response (λ ｒ ′ or λ ｒ ) and adjust the driving force movement amount F ｄ The calculation of is the phase-adjusted reference pitch response (λ ｒ ′ or λ ｒ ) is used.

[0110] Driving force movement amount F ｄ When performing phase lead compensation processing on the torque (T ｆ , T ｒ The delay time (τ ｆ , τ ｒ ) in advance in the calculation of the reference pitch response (λ', λ), it is particularly easy to suppress the oscillation of the pitch angle λ and the pitch rate λ'. This is because the delay time (τ ｆ , τ ｒ ) and the reference pitch response (λ ｒ ′, λ ｒ ) is calculated, the actual pitch response (λ′, λ) and the reference pitch response (λ ｒ ′, λ ｒ ) are in phase with each other, and as a result, the driving force movement amount F calculated using these deviations Δλ is ｄThis is because the accuracy of the calculation is improved.

[0111] In the control method for the electric vehicle according to the above embodiment and modification, the torque T ｆ delay time τ from the actual pitch response (λ' or λ) ｆ and the torque T of the rear motor 31 ｒ delay time τ from the actual pitch response (λ' or λ) ｒ The difference Δτ ｆｒ Based on this, the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) is further subjected to a phase difference compensation process to reduce the phase difference between the front wheels 22 and the rear wheels 32.

[0112] In this way, the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) is further subjected to a phase difference compensation process, the oscillation of the pitch angle λ and the pitch rate λ' is particularly easily suppressed. ｆ , τ ｒ The difference Δτ ｆｒ The phase difference compensation process based on the driving force movement amount F ｄ The setting error of the phase lead compensation process for τ ｆ and τ ｒ Even if there is a substantial difference in the driving force movement amount F ｄ The phase lead compensation process for τ ｆ and τ ｒ Regardless of whether the pitch angle λ and pitch rate λ' are set based on the above formula, the oscillations of the pitch angle λ and pitch rate λ' are suppressed particularly effectively.

[0113] In the control method for the electric vehicle according to the above embodiment and modification, the torque T ｆ The rotation speed N of the front motor 21 ｆ Transfer characteristics G ｒ (s) and the torque T of the rear motor 31 ｒ The rotation speed N of the rear motor 31 ｒ Transfer characteristics G ｒｒ(s) to obtain the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) is further subjected to a phase difference compensation process to reduce the phase difference between the front wheels 22 and the rear wheels 32.

[0114] In this way, the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ), the oscillation of the pitch angle λ and the pitch rate λ' is particularly easily suppressed. ｒ (s) and transfer characteristic G ｒｒ The phase difference compensation process based on (s) can reduce errors caused by differences in the dynamic characteristics of the front wheels 22 and the rear wheels 32, including vibration damping control. As a result, vibrations in the pitch angle λ and pitch rate λ' are particularly effectively suppressed.

[0115] The control device for an electric vehicle according to the above embodiment and modified example is a control device (controller 14) for an electric vehicle 100 having a front motor 21 that drives front wheels 22 and a rear motor 31 that drives rear wheels 32, and controls pitching of the electric vehicle 100 by transferring driving force between the front wheels 22 and the rear wheels 32. This control device (controller 14) controls pitching of the electric vehicle 100 by transferring driving force between the front wheels 22 and the rear wheels 32. ｆ１ ＊ , F ｒ１ ＊ ), the reference pitch response (λ ｒ ′ or λ ｒ ), an actual pitch response acquisition unit (42) that acquires an actual pitch response (λ' or λ), which is an actual response related to pitching, and a reference pitch response (λ ｒ ′ or λ ｒ ) and the actual pitch response (λ' or λ), a driving force transfer amount F representing the driving force to be transferred between the front wheels 22 and the rear wheels 32 is calculated. ｄ a driving force movement amount calculation unit 43 that calculates the driving force movement amount F ｄ whereas the pitching resonance frequency f λ A predetermined frequency band (fＬ <f<f Ｈ ) is subjected to a phase lead compensation process to advance the phase of the corrected driving force movement amount F ｄ and a phase lead compensation unit 44 that calculates the correction driving force movement amount F ｄ ' to obtain the driving force command value (F ｆ１ ＊ , F ｒ１ ＊ ) is corrected to obtain the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) and a command value correcting unit 45 that calculates the corrected driving force command value (F ｆ２ ＊ , F ｒ２ ＊ ) to drive the front motor 21 and the rear motor 31.

[0116] In this way, the driving force movement amount F ｄ The phase lead compensation process is performed on the pitching resonance frequency f λ A predetermined frequency band (f Ｌ <f<f Ｈ ) the phase of the corrected driving force movement amount F ｄ When pitch control is performed using the pitch angle λ and pitch rate λ', the oscillations of the pitch angle λ and pitch rate λ' can be suppressed. In other words, compared to conventional pitch control, the behavior of the pitch angle λ and pitch rate λ' approaches ideal behavior with reduced oscillations.

[0117] The above describes embodiments and modifications of the present invention, but the configurations described in the above embodiments and modifications merely illustrate some of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

Claims

1. A control method for an electric vehicle having a front motor that drives the front wheels and a rear motor that drives the rear wheels, the method controlling pitching of the electric vehicle by transferring driving force between the front wheels and the rear wheels, the method comprising: calculating a reference pitch response that is a reference response related to the pitching based on a driving force command value that commands the driving forces of the front wheels and the rear wheels; obtaining an actual pitch response that is an actual response related to the pitching; calculating a driving force transfer amount that represents the driving force to be transferred between the front wheels and the rear wheels based on the reference pitch response and the actual pitch response; calculating a corrected driving force transfer amount by applying phase lead compensation processing to the driving force transfer amount that advances the phase of a predetermined frequency band that includes the pitching resonance frequency; calculating a corrected driving force command value by correcting the driving force command value using the corrected driving force transfer amount; and driving the front motor and the rear motor based on the corrected driving force command value.

2. A control method for an electric vehicle according to claim 1, wherein the width of the predetermined frequency band in the phase lead compensation process is set based on the delay time from the torque of the front motor or the rear motor to the actual pitch response.

3. A control method for an electric vehicle as claimed in claim 1, wherein the phase lead compensation process advances the phase of the driving force transfer amount so that the phase lag of the driving force transfer amount becomes zero degrees at least at the resonant frequency.

4. A method for controlling an electric vehicle according to claim 1, wherein the predetermined frequency band in the phase lead compensation process includes at least a range of 1 Hz to 2 Hz.

5. A control method for an electric vehicle as claimed in claim 1, wherein the phase of the reference pitch response is adjusted based on the delay time from the torque of the front motor or the rear motor to the actual pitch response, and the calculation of the driving force movement amount is performed using the reference pitch response whose phase has been adjusted.

6. A control method for an electric vehicle as claimed in claim 1, further comprising: applying a phase difference compensation process to the corrected driving force command value to reduce the phase difference between the front wheels and the rear wheels, based on the difference between the delay time from the torque of the front motor to the actual pitch response and the delay time from the torque of the rear motor to the actual pitch response.

7. A control method for an electric vehicle as claimed in claim 1, further comprising: applying a phase difference compensation process to the corrected driving force command value to reduce the phase difference between the front wheels and the rear wheels, using a transfer characteristic from the torque of the front motor to the rotation speed of the front motor and a transfer characteristic from the torque of the rear motor to the rotation speed of the rear motor.

8. A control device for an electric vehicle having a front motor that drives the front wheels and a rear motor that drives the rear wheels, the control device for controlling pitching of the electric vehicle by transferring driving force between the front wheels and the rear wheels, the control device for an electric vehicle comprising: a reference pitch response calculation unit that calculates a reference pitch response that is a reference response related to the pitching based on a driving force command value that commands the driving forces of the front wheels and the rear wheels; an actual pitch response acquisition unit that acquires an actual pitch response that is an actual response related to the pitching; a driving force transfer amount calculation unit that calculates a driving force transfer amount that represents the driving force to be transferred between the front wheels and the rear wheels based on the reference pitch response and the actual pitch response; a phase lead compensation unit that calculates a corrected driving force transfer amount by applying phase lead compensation processing to the driving force transfer amount that advances the phase of a predetermined frequency band that includes the pitching resonance frequency; and a command value correction unit that calculates a corrected driving force command value by correcting the driving force command value using the corrected driving force transfer amount, wherein the control device for an electric vehicle drives the front motor and the rear motor based on the corrected driving force command value.

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