Motor control method and motor control device

Abstract

To appropriately execute slip control even in an electric vehicle in which all wheels can be drive wheels.SOLUTION: There is provided a motor control method for controlling the operation of each of a first drive motor 21 and a second drive motor 31 on the basis of a first torque command value Tmf_f* and a second torque command value Tmr_f*. This motor control method includes a first torque command value calculation step of calculating a first torque command value Tmf_f* by executing slip rotation speed control on the basis of a first rotation speed ωmf and a first basic torque command value Tmf*, and a second torque command value calculation step of calculating a second torque command value Tmr_f* on the basis of a second basic torque command value Tmr*. In particular, in the second torque command value calculation step, the second torque command value Tmr_f* is calculated by limiting the second basic torque command value Tmr* using the disturbance estimated value T^dist, which is an estimated value of the disturbance acting on the electric vehicle 10, and the first torque command value Tmf_f*.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a motor control method and a motor control device. [Background technology]

[0002] Conventionally, there is known a technique for suppressing a slip state in an electric vehicle in which wheels (drive wheels) are driven by an electric drive motor. For example, Patent Document 1 proposes a slip control that detects a slip state of the drive wheels using the rotation speed of the drive motor and the speed (corresponding to an estimated vehicle speed) of a driven wheel that is not driven by the drive motor, and calculates a slip control command torque when slip of the drive wheels is detected, thereby limiting the output of the drive motor and suppressing slip. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-158337 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, slip control is performed by detecting the slip state of the drive wheels using the rotation speed of the non-slip driven wheels. However, in the case of an electric vehicle in which all wheels are drive wheels (a so-called 4WD electric vehicle), it is assumed that all drive wheels will slip. In this case, it is not possible to obtain a wheel speed that is appropriately correlated with the vehicle speed, making it difficult to appropriately detect the slip state.

[0005] Therefore, an object of the present invention is to provide a motor control method and a motor control device that can appropriately execute slip control even in an electric vehicle in which all wheels can be drive wheels. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a motor control method for an electric vehicle in which multiple drive wheels are independently driven by multiple drive motors, the method determining a first torque command value for a first drive motor driving a first drive wheel and a second torque command value for a second drive motor driving a second drive wheel, and controlling the operation of each of the first drive motor and the second drive motor based on the first torque command value and the second torque command value.

[0007] This motor control method includes a rotational speed acquisition step of acquiring a first rotational speed, which is the rotational speed of a first drive motor, and a second rotational speed, which is the rotational speed of a second drive motor; a base torque calculation step of calculating a first base torque command value, which is a base torque command value of the first drive motor, and a second base torque command value, which is a base torque command value of the second drive motor; a first torque command value calculation step of calculating the first torque command value by performing slip rotational speed control based on the first rotational speed and the first base torque command value; and a second torque command value calculation step of calculating the second torque command value based on the second base torque command value.

[0008] In particular, in the second torque command value calculation step, the second basic torque command value is limited by the first torque command value and an external disturbance estimated value that is an estimate of a disturbance acting on the electric vehicle, thereby calculating the second torque command value. Effect of the Invention

[0009] According to the present invention, slip control can be appropriately performed even in an electric vehicle in which all wheels can serve as drive wheels. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a system configuration of an electric vehicle. [Diagram 2] FIG. 2 is a flowchart showing the overall flow of motor control. [Diagram 3] FIG. 3 is a diagram showing an example of an accelerator opening-torque table. [Figure 4]FIG. 4 is a block diagram showing the details of the torque distribution calculation unit. [Diagram 5] FIG. 5 is an explanatory diagram showing parameters used in the equation of motion of an electric vehicle. [Figure 6] FIG. 6 is a block diagram showing the details of the slip suppression calculation process. [Figure 7] FIG. 7 is a block diagram showing the details of the rear torque limit calculation unit. [Figure 8] FIG. 8 is a block diagram showing details of the disturbance estimation calculation unit according to the first embodiment. [Figure 9] FIG. 9 is a flowchart showing the process in the disturbance torque limiting section according to the first embodiment. [Figure 10] FIG. 10 is a block diagram showing details of the limit torque calculation unit. [Figure 11] FIG. 11 is a flowchart showing the process in the torque limiting unit according to the first embodiment. [Figure 12] FIG. 12 is a flowchart showing the process in the vehicle speed estimation unit. [Figure 13] FIG. 13 is a block diagram showing details of the disturbance estimation calculation unit according to the second embodiment. [Figure 14] FIG. 14 is a block diagram showing details of the rear torque limit calculation unit according to the third embodiment. [Figure 15] FIG. 15 is a block diagram showing details of the disturbance estimation calculation unit according to the third embodiment. [Figure 16] FIG. 16 is a time chart showing the control results according to the comparative example. [Figure 17] FIG. 17 is a time chart showing the control results according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] [First embodiment] (I. Overall System Configuration) 1 is a schematic diagram showing an example of the system configuration of an electric vehicle 10. In this embodiment, an electric vehicle 10 equipped with independent motors (electric motors) at the front and rear will be described as an example. That is, the electric vehicle 10 is a four-wheel drive vehicle in which the front wheels 22 and the rear wheels 32 are each driven by a different motor. The electric vehicle 10 includes a front-wheel drive system 11, a rear-wheel drive system 12, a battery 13, and a motor controller 14.

[0013] The front-wheel 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-wheel drive system 11 includes a front inverter 23, a rotation sensor 24, a current sensor 25, and the like.

[0014] The front motor 21 is, for example, a three-phase AC synchronous motor that generates driving force using AC power input from the front inverter 23 and transmits the driving force to the front wheels 22 via the front reduction gear 26 and the drive shaft 27. That is, the output torque of the front motor 21 generates torque (driving force) on the front wheels 22. In addition, when the drive shaft of the front motor 21 is rotated by the front wheels 22 while the electric vehicle 10 is traveling, the front motor 21 generates regenerative driving force (so-called regenerative torque). This allows the front motor 21 to recover the kinetic energy of the electric vehicle 10 as electrical energy.

[0015] The front wheels 22 are drive wheels disposed at the front of the electric vehicle 10. The front wheels 22 are connected to the front motor 21 via a front reduction gear 26 and a drive shaft 27.

[0016] The front inverter 23 includes, for example, two pairs of switching elements for each phase of the front motor 21. The front inverter 23 turns these switching elements on / off in response to a PWM (Pulse Width Modulation) signal input from the motor controller 14. As a result, the front inverter 23 converts DC power supplied from the battery 13 into AC power, and passes a desired current through 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.

[0017] In the following description, the reference characters representing parameters related to the front wheel drive system 11 are suffixed with the letter "f", and the reference characters representing parameters related to the rear wheel drive system 12 are suffixed with the letter "r".

[0018] The rotation sensor 24 detects the front rotor phase αf. The front rotor phase αf corresponds to the rotor phase α of the front motor 21, i.e., the electrical angle [rad] of the front motor 21. The rotation sensor 24 is, for example, a resolver or an encoder. The detected front rotor phase αf is input to the motor controller 14.

[0019] The current sensor 25 detects the current value (i uf ,i vf ,i wf ) are detected. These current values ​​i uf ,i vf ,i wf is input to the motor controller 14.

[0020] The front wheel drive system 11 also includes other sensors (for example, wheel rotation sensors (not shown)). The wheel rotation sensors are sensors that detect the wheel rotation speeds of the left and right front wheels 22.

[0021] The rear-wheel drive system 12 is a system that drives rear wheels 32 by a rear motor 31, and is configured symmetrically to the front-wheel drive system 11. Therefore, in addition to the rear motor 31 and rear wheels 32, the rear-wheel 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 configure the rear-wheel drive system 12 function in the same way as the components of the front-wheel drive system 11. In other words, the rear wheels 32 are drive wheels disposed at the rear of the electric vehicle 10. The rotation sensor 34 detects a rotor phase α of the rear-wheel drive system 12 (hereinafter referred to as "rear rotor phase αr"). The current sensor 35 detects the current value (i ur ,i vr ,i wr ) to detect.

[0022] The battery 13 is provided in common to the front wheel drive system 11 and the rear wheel drive system 12, and discharges power by supplying it to drive the front motor 21 and the rear motor 31. During regenerative control, the battery 13 is charged by regenerative power generated by the front motor 21 and the rear motor 31.

[0023] The motor controller 14 is a control device for the electric vehicle 10. The motor controller 14 acquires various vehicle variable signals as digital signals, and generates PWM signals for controlling the front motor 21 and the rear motor 31 based on these vehicle variables. The motor 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. In other words, the motor controller 14 generates drive signals for the front inverter 23 and the rear inverter 33 through drive circuits in accordance with the PWM signals.

[0024] The vehicle variables are parameters that represent the control state of the electric vehicle 10. The motor controller 14 uses, as the vehicle variables, for example, the front rotor phase αf and the current value i uf ,i vf ,i wf, rear rotor phase αr and current value i ur ,i vr ,i wr In addition, the motor controller 14 acquires vehicle variables such as an accelerator opening θ and a DC voltage value Vdc (not shown) of the battery 13. The accelerator opening θ is a parameter that indicates the amount of operation of the accelerator (not shown) by the driver. The accelerator opening θ and vehicle variables such as the DC voltage value Vdc of the battery 13 can be detected appropriately as necessary by a sensor (not shown). The motor controller 14 may acquire the vehicle variables directly from a sensor or the like, or may acquire some or all of the vehicle variables from another controller (computer) (not shown).

[0025] (II. Overall Control) Fig. 2 is a flowchart showing the overall flow of motor control. Each process shown in Fig. 2 is executed by any one of the motor controller 14, the front inverter 23 (more specifically, a controller built in the front inverter 23), and the rear inverter 33 (more specifically, a controller built in the rear inverter 33), or by two or more of them in a distributed manner.

[0026] 2, the motor control in this embodiment includes input processing (step S201), basic target torque calculation processing (step S202), slip suppression calculation processing (step S203), current command value calculation processing (step S204), and current control calculation processing (step S205). That is, the motor controller 14, the front inverter 23, and / or the rear inverter 33 are programmed to function as an input processing unit that executes the input processing (step S201), a basic target torque calculation unit that executes the basic target torque calculation processing (step S202), a slip suppression calculation unit that executes the slip suppression calculation processing (step S203), a current command value calculation unit that executes the current command value calculation processing (step S204), and a current control calculation unit that executes the current control calculation processing (step S205).

[0027] In step S201, the motor controller 14 executes an input process to input signals necessary for each process described below. Alternatively, the motor controller 14 may obtain each of these signals from another controller through a predetermined communication. For example, the motor controller 14 obtains vehicle variables and the like necessary for controlling the front motor 21 and the rear motor 31.

[0028] Specifically, the motor controller 14 controls the three-phase current value i uf ,i vf ,i wf , and the three-phase current value i of the rear motor 31 ur ,i vr ,i wr is obtained from the current sensors 25 and 35. The three-phase current value i uf ,i vf ,i wf Since the sum of these is 0, the motor controller 14 can obtain, for example, the currents for two of these phases and calculate the current for the remaining phase. This is because the three-phase current value i ur ,i vr ,i wr The same applies to.

[0029] Furthermore, motor controller 14 acquires front rotor phase αf and rear rotor phase αr (electrical angle) [rad] from rotation sensors 24, 34. Furthermore, motor controller 14 acquires a DC voltage value Vdc [V] of battery 13. This DC voltage value Vdc [V] may be acquired from a voltage sensor provided on a DC power supply line, or may be acquired from a power supply voltage value transmitted from the battery controller.

[0030] Furthermore, the motor controller 14 controls, for example, the rotational angular velocity ω mf ") [rad / s], and the rotational angular velocity of the rear motor 31 (hereinafter referred to as "rear motor angular velocity ω mr The front motor angular velocity ω mfis the mechanical angular velocity, which is calculated by differentiating the rotor phase αf (electrical angle) and dividing it by the number of pole pairs of the front motor 21. Similarly, the rear motor angular velocity ω mr is the mechanical angular velocity, which is calculated by differentiating the rotor phase αr (electrical angle) and dividing it by the number of pole pairs of the rear motor 31.

[0031] In this embodiment, the front motor angular velocity ω mf and rear motor angular velocity ω mr However, for example, the rotation speed N mf [rpm] and the rotation speed N of the rear motor 31 mr The rotation speed N of the front motor 21 may be used as a parameter representing the rotation speed of the electric motor. mf is obtained by dividing the rotor angular velocity ω of the front motor 21 by the number of pole pairs of the front motor 21, and calculating the front motor angular velocity ω mf After calculating the front motor angular velocity ω mf The rotation speed N of the rear motor 31 can be calculated by multiplying the rotation speed N by a unit conversion coefficient (60 / 2π) from [rad / s] to [rpm]. mr can be calculated in the same way.

[0032] In addition, the wheel rotation speed ω wfr , ω wfl , ω wrr , ω wrl [km / h] is obtained by multiplying each wheel rotation speed by the tire dynamic radius r to obtain the wheel rotation speed v [m / s], and applying a unit conversion coefficient (3600 / 1000) from [m / s] to [km / h] to the value obtained by these calculations. The left and right wheel rotation speeds of the front wheels 22 and the rear wheels 32 can be obtained based on the number of rotations detected by the wheel rotation sensors.

[0033] Furthermore, the accelerator opening θ [%] may be obtained from an accelerator opening sensor, or may be obtained from the vehicle controller or another controller via communication.

[0034] In step S202, the motor controller 14 determines a target value (target torque command value T m * Specifically, the motor controller 14 executes a basic target torque calculation process to calculate the basic target torque based on the accelerator opening θ and the front motor angular velocity ω mf and / or rear motor angular velocity ω mr Based on this, the target torque command value T m * Set.

[0035] 3 is a diagram showing an example of an accelerator opening-torque table, in which accelerator openings θ0 to θ8 respectively indicate 0 / 8 (fully closed), 1 / 8, 2 / 8, 3 / 8, 4 / 8, 5 / 8, 6 / 8, 7 / 8, and 8 / 8 (fully open).

[0036] As shown in FIG. 3, the electric vehicle 10 has, for example, an accelerator opening θ and a front motor angular velocity ω mf and / or rear motor angular velocity ω mr and the target torque command value T m * An accelerator opening / torque table in which the accelerator opening θ and the front motor angular velocity ω are associated with each other based on experiments, simulations, or the like is stored in advance. The motor controller 14 references the accelerator opening / torque table shown in FIG. mf and / or rear motor angular velocity ω mr The target torque command value T m * It is possible to obtain

[0037] In addition, the motor controller 14 calculates a front target torque command value T mf * and the rear target torque command value T mr * Set the following.

[0038] 4 is a block diagram showing an example of a functional configuration of a torque distribution calculation unit 40 provided in the motor controller 14. The torque distribution calculation unit 40 includes a front wheel distribution gain multiplication unit 41 and a rear wheel distribution gain multiplication unit .

[0039] The torque distribution calculation unit 40 calculates the target torque command value T m * to the front wheels 22 and the rear wheels 32. mf * and the rear target torque command value T mr * The front target torque command value T mf * is the target torque command value T m * The rear target torque command value T mr * is the target torque command value T m * The torque to be output by the rear motor 31 is a target value. f is a value for setting the front and rear motor torque distribution, and is set to a value between 1 and 0. Note that the front and rear driving force distribution gain K f is set based on the driving force required by the electric vehicle 10. For example, the front / rear driving force distribution gain K f It is possible to set

[0040] Specifically, the torque distribution calculation unit 40 calculates the target torque command value T m * Front and rear drive force distribution gain K f By multiplying this, the front target torque command value T mf * In addition, the torque distribution calculation unit 40 sets the target torque command value T m * Front and rear driving force distribution gain (1-K f ) to obtain the rear target torque command value T mr* Set.

[0041] In step S203, the motor controller 14 executes a slip suppression calculation process to suppress slip of the electric vehicle 10. Specifically, the motor controller 14 executes a slip rotation speed control for one of the front wheels 22 and the rear wheels 32, and executes a torque limit control for the other wheel to limit the torque and reduce the amount of slip. In the slip suppression calculation process, the motor controller 14 also executes a front final torque command value T mf_f * and rear final torque command value T mr_f * The slip suppression calculation process will be described later.

[0042] In step S204, the front inverter 23 and the rear inverter 33 calculate the target values ​​of the currents to be input to the front motor 21 and the rear motor 31 (dq-axis current target values ​​id * , iq * In the current command value calculation process, a current target value in a so-called dq-axis coordinate system is calculated. That is, in the current command value calculation process, the front final torque command value T mf_f * , rear final torque command value T mr_f * , front motor angular velocity ω mf , rear motor angular velocity ω mr , and the DC voltage value Vdc of the battery 13, the dq-axis current target value id * , iq * Request.

[0043] Specifically, the front inverter 23 outputs a front final torque command value T mf_f * , front motor angular velocity ω mf , and the DC voltage value Vdc of the battery 13, the dq-axis current target value idf * ,iqf * Similarly, the rear inverter 33 calculates the rear final torque command value T mr_f* , rear motor angular velocity ω mr , and the DC voltage value Vdc of the battery 13, the dq axis current target value idr of the rear motor 31 * ,iqr * Calculate the following.

[0044] In addition, the electric vehicle 10 has a front final torque command value T mf_f * , front motor angular velocity ω mf , and the dq-axis current target value idf of the front motor 21 with respect to the DC voltage value Vdc of the battery 13 * ,iqf * In the same manner, the electric vehicle 10 stores a table in which the rear final torque command value T mr_f * , rear motor angular velocity ω mr , and the dq-axis current target value idr of the rear motor 31 with respect to the DC voltage value Vdc of the battery 13 * ,iqr * The motor controller 14 stores in advance a table in which the dq-axis current target value idf of the front motor 21 is associated with the dq-axis current target value idf of the front motor 21 by means of an experiment, a simulation, or the like. * ,iqf * , and the dq-axis current target value idr of the rear motor 31 * ,iqr * Calculate the following.

[0045] In step S205, the front inverter 23 and the rear inverter 33 execute current control calculation processing to calculate PWM signals for driving the front motor 21 and the rear motor 31, respectively.

[0046] More specifically, the front inverter 23 converts the three-phase current value i uf ,i vf ,i wf Next, the front inverter 23 calculates the dq-axis current target values ​​idf and iqf of the front motor 21 calculated in step S204 based on the front rotor phase αf. *,iqf * The dq-axis voltage command values ​​vdf, vqf are calculated based on the deviation between the dq-axis current values ​​idf, iqf and the front inverter 23. At this time, the front inverter 23 may add a so-called non-interference control.

[0047] Next, the front inverter 23 calculates three-phase voltage command values ​​vuf, vvf, and vwf based on the dq-axis voltage command values ​​vdf, vqf and the front rotor phase αf. Then, the motor controller 14 calculates PWM signals (on duty) tu[%], tv[%], and tw[%] based on the three-phase voltage command values ​​vuf, vvf, and vwf and the DC voltage value Vdc of the battery 13.

[0048] By controlling the opening and closing of the switching elements of the front inverter 23 using the PWM signal obtained in this manner, it is possible to drive the front motor 21 with the desired torque specified by the torque command value. Note that although the calculation of the PWM signal that drives the front motor 21 has been described above, the calculation of the PWM signal that drives the rear motor 31 is similar.

[0049] (III. Slip Suppression Calculation Processing) The slip suppression calculation process (S203) of the present embodiment is described in detail below. m from motor rotation angular velocity ω m In the following, a transfer function Gp(s) is used that expresses the transfer characteristics up to 10 ...

[0050] Fig. 5 is an explanatory diagram showing parameters used in the equations of motion of electric vehicle 10. When the driving force transmission system of electric vehicle 10 is modeled as shown in Fig. 5, the equations of motion of electric vehicle 10 are expressed by the following formulas (1) to (5).

[0051]

number

[0052] The parameters in Fig. 5 and the above equations of motion are as follows. In Fig. 5, the "f" at the end of the auxiliary symbol (subscript) of each parameter indicates front and "r" indicates rear. Also, the "*" symbol at the top right of the parameters in (1) to (5) above indicates time differentiation.

[0053] J m : Motor inertia J w : Inertia of the drive wheels (for one axle) M: Mass of the vehicle K d : Torsional rigidity of the drive system K t : Friction coefficient between the tire and the road surface N: Overall gear ratio r: tire rolling radius ω m : Motor rotation angular velocity T m :Motor torque T d : Drive wheel torque F: Force applied to the vehicle V:Vehicle speed ω w : Angular velocity of the drive wheels

[0054] Equations (1) to (5) are transformed into a Laplace transform to obtain the motor torque T m From the motor rotation angular velocity ω m The transfer function Gp(s) from

[0055]

number

[0056] Here, the coefficient b in equation (6) 0 ~b 3 and coefficient a 1 ~a 4 are expressed by the following formulas (7) to (14), respectively.

[0057]

number

[0058] When examining the poles and zeros of the transfer function Gp(s) shown in equation (6), it can be approximated to the transfer function Gp(s) shown in equation (15) below, with one pole and one zero showing very close values. This corresponds to α and β in equation (15) showing very close values.

[0059]

number

[0060] Therefore, by performing pole-zero cancellation (approximating α=β) in equation (15), it is possible to express the transfer function Gp(s) in a quadratic / cubic form as shown in the following equation (16).

[0061]

number

[0062] Here, equation (16) can be rewritten as equation (17) below.

[0063]

number

[0064] Here, ζz, ωz, ζp, and ωp shown in equation (17) are expressed by the following equations (18) to (21), respectively.

[0065]

number

[0066] Next, the slip suppression calculation process will be described in detail with reference to FIG.

[0067] 6 is a block diagram showing details of the slip suppression calculation process (S203). As shown in the figure, the motor controller 14 includes a rear torque limit calculation unit 601, a vehicle speed estimation unit 602, and a front slip rotation speed control unit 603 as means for realizing the slip suppression calculation process.

[0068] (III-1. Rear torque limit calculation section) The rear torque limit calculation unit 601 calculates the front final torque command value T mf_f * (especially the feedback value), rear target torque command value T mr * , and rear motor angular velocity ω mr The rear final torque command value T mr_f * Calculate.

[0069] 7 is a block diagram showing details of the rear torque limit calculation section 601. As shown in the figure, the rear torque limit calculation section 601 includes a disturbance estimation calculation section 701, a limit torque calculation section 702, and a torque limit section 703.

[0070] The disturbance estimation calculation unit 701 calculates the rear final torque command value T mr_f * , Front final torque command value T mf_f * , and the front motor angular velocity ω mf Based on this, the estimated value of the disturbance torque acting on the vehicle body (hereinafter referred to as the "disturbance torque estimated value T^ dist The corrected disturbance torque estimate T^ dist_lim Calculate.

[0071] 8 is a block diagram showing details of the disturbance estimation calculation unit 701. As shown in the figure, the disturbance estimation calculation unit 701 includes a first motor torque estimated value calculation unit 801, a final total torque command value calculation unit 802, a second motor torque estimated value calculation unit 803, a subtraction unit 804, and a disturbance torque limiting unit 805.

[0072] The first motor torque estimate calculation unit 801 calculates the front motor torque Tmf and the front motor angular velocity ω mf Model G of the transfer characteristics pf H(s) / G using a low-pass filter H(s) whose order is equal to or greater than the difference between the denominator order and the numerator order of (s) pf At (s), the front motor angular velocity ω mf That is, the first motor torque estimate is calculated based on the front motor angular velocity ω mf is a motor torque estimate based on

[0073] The final total torque command value calculation unit 802 calculates the front final torque command value T mf_f * (especially the feedback value) and the rear final torque command value T mr_f * The final total torque command value T mto_f * The front final torque command value T mf_f * The rear final torque command value T mr_f * Alternatively, a configuration in which the above is added may be adopted.

[0074] The second motor torque estimation value calculation unit 803 calculates the final total torque command value T mto_f * is filtered by a low-pass filter H(s) to calculate a second motor torque estimate. That is, the second motor torque estimate is calculated based on the front final torque command value T mf_f * and rear final torque command value T mr_f * is a motor torque estimate based on

[0075] The subtraction unit 804 subtracts the first motor torque estimated value calculated by the first motor torque estimated value calculation unit 801 from the second motor torque estimated value calculated by the second motor torque estimated value calculation unit 803, thereby obtaining a disturbance torque estimated value T^ dist Calculate.

[0076] The disturbances that are the subject of this embodiment include various interference factors that affect the motor control system, such as air resistance acting on the electric vehicle 10, modeling errors due to variations in vehicle mass (number of passengers, load), rolling resistance of tires, and gradient resistance. In particular, in the example shown in FIG. 8, the front final torque command value T mf_f * , rear final torque command value T mr_f * , and the front motor angular velocity ω mf is used as input, and the transfer characteristic model G pf (s) is used to estimate the disturbance torque T^ dist In order to calculate the disturbance torque estimate T^ dist includes the effects of the various interference factors mentioned above.

[0077] Although the magnitude of the influence of each interference factor assumed as a disturbance varies depending on the driving conditions of the electric vehicle 10, the influence of the external force (torque) acting on the vehicle body according to the magnitude of the gradient, particularly in driving scenes such as uphill and downhill roads, and the slip component of the front wheel 22 or the rear wheel 32 (the difference between the output torque determined from the vehicle model and the actual output torque) is dominant. In other words, the disturbance torque estimate value T^ calculated in this case dist can be roughly regarded as the sum of the torque component and slip component acting on the vehicle body according to the magnitude of the gradient.

[0078] The disturbance torque limiting unit 805 then calculates the final total torque command value T mto_f * (especially its sign) and the disturbance torque estimate T^ dist By performing a calculation process to remove the gradient resistance component contained in the disturbance, the corrected disturbance torque estimate T^ dist_lim Calculate.

[0079] FIG. 9 is a flowchart showing the process in the disturbance torque limiting section 805.

[0080] As shown in the figure, in step S901, the disturbance torque limiting unit 805 calculates the final total torque command value Tmto_f * The sign of the final total torque command value T mto_f * ≧0. Then, the final total torque command value T mto_f * If the sign is positive or 0, the process proceeds to step S902, and if the sign is negative, the process proceeds to step S903.

[0081] In steps S902 and S903, the disturbance torque limiting unit 805 calculates the disturbance torque estimated value T^ dist The magnitude relationship between the estimated disturbance torque value T^ and a predetermined value (0 in this embodiment) is determined. dist It is determined whether or not ≧0.

[0082] In particular, in the judgment of step S902, the disturbance torque estimated value T^ dist If it is equal to or greater than 0, the process proceeds to step S904, and if it is less than 0, the process proceeds to step S905.

[0083] In step S904, the disturbance torque limiting unit 805 calculates the corrected disturbance torque estimated value T^ dist_lim On the other hand, in step S905, the disturbance torque limiting unit 805 sets the disturbance torque estimated value T^ dist The corrected disturbance torque estimate T^ dist_lim is set forth below.

[0084] In addition, in the judgment of step S903, the disturbance torque estimated value T^ dist If it is equal to or greater than 0, the process proceeds to step S906, and if it is less than 0, the process proceeds to step S907.

[0085] In step S906, the disturbance torque limiting unit 805 calculates the disturbance torque estimated value T^ dist The corrected disturbance torque estimate T^ dist_lim On the other hand, in step S907, the corrected disturbance torque estimate T^ dist_lim Set to 0.

[0086] According to the above-described process shown in FIG. 9, the final total torque command value T mto_f * It is determined whether the electric vehicle 10 is in a driving state or a regenerative state, and if it is in a driving state, the disturbance torque estimated value T^ dist The corrected disturbance torque estimate T^ is set to 0 or less. dist_lim If the regenerative state is in effect, the disturbance torque estimate T^ dist The corrected disturbance torque estimate T^ is set to 0 or more. dist_lim Therefore, in a scene where the electric vehicle 10 is traveling on an uphill road, the disturbance torque estimated value T^ can be determined. dist The corrected disturbance torque estimate T^ obtained by removing the gradient resistance component from dist_lim can be obtained.

[0087] In the judgment of step S902 and / or step S903, the parameter to be compared with the predetermined value (0 in this embodiment) is the corrected disturbance torque estimated value T^ dist_lim However, any parameter that indicates the magnitude of the gradient on the road on which the electric vehicle 10 runs can be used. As such a parameter, for example, a gradient resistance R g can be used. g can be obtained by referring to, for example, a detection value of a G sensor (not shown) provided in the electric vehicle 10, or road information that can be acquired from an external server.

[0088] Returning to FIG. 7, the limit torque calculation unit 702 calculates the front final torque command value T mf_f * and the corrected disturbance torque estimate T^ dist_lim is input, and the torque limit value T lim Calculate.

[0089] 10 is a block diagram showing details of the limit torque calculation unit 702. As shown in the figure, the limit torque calculation unit 702 includes an adder 1001. The adder 1001 calculates the front final torque command value T mf_f *and the corrected disturbance torque estimate T^ dist_lim The sum is output.

[0090] Returning to FIG. 7, the torque limiting unit 703 determines the rear target torque command value T mr * and torque limit value T lim The rear final torque command value T mr_f * Calculate.

[0091] FIG. 11 is a flowchart showing the process in the torque limiting section 703.

[0092] As shown in the figure, in step S1101, the torque limiting unit 703 limits the rear target torque command value T mr * That is, the sign of the rear target torque command value T mr * ≧0. Then, the rear target torque command value T mr * If the sign is positive or 0, the process proceeds to step S1102, and if the sign is negative, the process proceeds to step S1103.

[0093] In steps S1102 and S1103, the torque limiting unit 703 calculates the rear target torque command value T mr * and the torque limit value T lim That is, the rear target torque command value T mr * ≧Torque limit value T lim It is determined whether or not

[0094] In particular, in step S1102, the rear target torque command value T mr * is the torque limit value T lim If it is equal to or greater than the torque limit value T lim If it is less than that, the process proceeds to step S1105.

[0095] In step S1104, the torque limiting unit 703 calculates the rear final torque command value T mr_f * Torque limit value T lim On the other hand, in step S1105, the torque limiting unit 703 determines the rear target torque command value T mr * The rear final torque command value T mr_f * is set forth below.

[0096] In step S1103, the rear target torque command value T mr * is the torque limit value T lim If it is equal to or greater than the torque limit value T lim If it is less than that, the process proceeds to step S1107.

[0097] In step S1106, the torque limiting unit 703 calculates the rear target torque command value T mr * The rear final torque command value T mr_f * On the other hand, in step S1107, the torque limiting unit 703 determines the rear final torque command value T mr_f * Torque limit value T lim is set forth below.

[0098] By the above-described process shown in FIG. 11, the rear target torque command value T mr * , and if the rear motor 31 is in the power running state or the regenerative running state, the rear target torque command value T mr * The upper limit of the torque limit value T lim The rear final torque command value T mr_f * If the regenerative braking operation is in progress, the rear target torque command value T mr * The lower limit of the torque limit value T lim The rear final torque command value T mr_f *This makes it possible to prevent the rear motor 31 from outputting excessive torque in both cases, during power running and regenerative operation of the rear motor 31, and to suppress spinning of the rear wheels 32.

[0099] (III-2.Vehicle speed estimation part) Returning to FIG. 6, the vehicle speed estimation unit 602 calculates the rear target torque command value T mr * , right rear wheel rotation speed ω wrr , and the left rear wheel rotation speed ω wrl Using this as input, the vehicle speed estimate V^ is calculated.

[0100] FIG. 12 is a flowchart showing the process in the vehicle speed estimation unit 602.

[0101] As shown in the figure, in step S1201, the vehicle speed estimation unit 602 calculates the rear target torque command value T mr * That is, the sign of the rear target torque command value T mr * It is determined whether the rear target torque command value T mr * If the sign is positive or 0, the process proceeds to step S1202, and if the sign is negative, the process proceeds to step S1203.

[0102] In steps S1202 and S1203, the vehicle speed estimation unit 602 estimates the right rear wheel rotation speed ω wrr and the left rear wheel rotation speed ω wrl That is, the right rear wheel rotation speed ω wrr ≧ Left rear wheel rotation speed ω wrl It is determined whether or not

[0103] In particular, in step S1202, the right rear wheel rotation speed ω wrr is the left rear wheel rotation speed ω wrl If so, the process proceeds to step S1204, and the right rear wheel rotation speed ω wrr is the left rear wheel rotation speed ω wrlIf it is less than that, the process proceeds to step S1205.

[0104] In step S1204, the vehicle speed estimation unit 602 calculates the vehicle speed estimate V^ by multiplying the left rear wheel rotation speed ω wrl On the other hand, in step S1205, the vehicle speed estimation unit 602 calculates the vehicle speed estimate V^ based on the right rear wheel rotation speed ω wrr is set forth below.

[0105] In addition, in the determination of step S1203, the right rear wheel rotation speed ω wrr is the left rear wheel rotation speed ω wrl If so, the process proceeds to step S1206, and the right rear wheel rotation speed ω wrr is the left rear wheel rotation speed ω wrl If it is less than that, the process proceeds to step S1207.

[0106] In step S1206, the vehicle speed estimation unit 602 calculates the vehicle speed estimate V^ by multiplying the right rear wheel rotation speed ω wrr On the other hand, in step S1207, the vehicle speed estimation unit 602 calculates the vehicle speed estimate V^ based on the left rear wheel rotation speed ω wrl is set forth below.

[0107] As described above, in this embodiment, the corrected disturbance torque estimate value T^ calculated by the disturbance estimation calculation unit 701 dist_lim (Disturbance torque estimate T^ dist (a value corrected to remove the gradient resistance component) and the front final torque command value T mf_f * The rear target torque command value T mr * By limiting the rear final torque command value T mr_f * In this way, the amount of slip on the rear side (rear wheels 32) to which the slip control by torque limitation is applied is lower than that on the front side (front wheels 22) to which the above-mentioned slip rotation speed control is applied. For this reason, the drive wheel speed (ω wrr Or ω wrl ) is the driving wheel speed (ω wfr Or ω wfl) is closer to the vehicle speed than the driving wheel speed (ω wrr Or ω wrl ) to calculate the estimated vehicle speed V^.

[0108] Furthermore, during acceleration (rear target torque command value T mr * is positive), it is assumed that the wheel speed of the left rear wheel or the right rear wheel that is slipping will be higher. Therefore, in this case, the wheel speed of the left rear wheel (i.e., the left rear wheel rotation speed ω wrl ) and the wheel speed of the right rear wheel (right rear wheel rotation speed ω wrr The lower of the two values ​​is set as the vehicle speed estimate V^. On the other hand, during regeneration (rear target torque command value T mr * When the sign of ω is negative, it is assumed that the wheel speed of the left rear wheel or the right rear wheel that is slipping is low. Therefore, in this case, the wheel speed of the left rear wheel (i.e., the left rear wheel rotation speed ω wrl ) and the wheel speed of the right rear wheel (right rear wheel rotation speed ω wrr The higher of these two values ​​is determined as the estimated vehicle speed V^.

[0109] This makes it possible to obtain an appropriate vehicle speed estimate V^ during both acceleration and regeneration, making it unnecessary to additionally mount a sensor for detecting the vehicle speed (for example, a GPS accelerometer).

[0110] (III-3. Front slip rotation speed control unit) Returning to FIG. 6, the front slip rotation speed control unit 603 determines the front target torque command value T mf * , front motor angular velocity ω mf , and the vehicle speed estimation value V^ calculated by the vehicle speed estimation unit 602 are input, and the front final torque command value T mf_f * Calculate.

[0111] More specifically, the front slip rotation speed control unit 603 calculates the vehicle speed estimate V^ and the front motor angular velocity ω mfA difference value between the drive wheel speed determined based on and is calculated, and if this difference value becomes a predetermined value or more, it is determined that a slip state exists.

[0112] When the front slip rotation speed control unit 603 detects a slip state, it adjusts the front motor angular speed ω mf The existing control (slip rotation speed control) is performed to make the front final torque command value T mf_f * The front target rotational angular velocity can be set to an angular velocity value equivalent to the rotational speed that causes the front wheels 22 to slip at a predetermined slip ratio with respect to the vehicle speed estimate V^. In particular, the front target rotational angular velocity is calculated by multiplying the rotational speed of the rear motor 31 (i.e., the rear motor angular velocity ω mr In particular, as described above, the amount of slip of the rear wheels 32 is kept low compared to the amount of slip of the front wheels 22, and the rear motor angular velocity ω mr By using this, the front target rotational angular velocity can be set to an appropriate value.

[0113] Furthermore, when the slip state is not detected (when the difference value is less than a predetermined value), the front slip rotation speed control unit 603 adjusts the front target torque command value T mf * The final torque command value T mf_f * The output is as follows:

[0114] According to the above motor control method, slip rotation speed control is executed for the front wheel drive system 11. Then, for the rear wheel drive system 12, the slip rotation speed control is applied to obtain a front final torque command value T mf_f * and the corrected disturbance torque estimate T^ dist_lim Using this, the rear target torque command value T mr * The rear final torque command value T mr_f *Since the slip amount of the front wheels 22 and the rear wheels 32 can be appropriately adjusted without adding a sensor for detecting the vehicle speed.

[0115] Furthermore, in the above motor control method, the disturbance torque estimated value T^ is a collective index of various interference factors acting on the electric vehicle 10 (particularly, interference factors caused by gradients). dist The corrected disturbance torque estimate T^ with the gradient resistance component removed dist_lim Using the rear target torque command value T mr * The rear final torque command value T mr_f * Therefore, in a scene where the electric vehicle 10 is traveling on a road having a gradient of a certain level or more, such as an uphill road, the rear target torque command value T mr * This makes it possible to prevent a situation in which the restriction on the rotational speed of the rear wheels 32 becomes insufficient (the actual output torque of the rear wheels 32 becomes excessive), and more reliably suppresses spinning / locking of the rear wheels 32.

[0116] The configuration and effects of the motor control method according to the present embodiment described above will now be described.

[0117] According to this embodiment, in an electric vehicle 10 in which a plurality of drive wheels are independently driven by a plurality of drive motors, a first torque command value (front final torque command value T mf_f * ) and a second torque command value (rear final torque command value T mr_f * ) is determined, and the front final torque command value T mf_f * and rear final torque command value T mr_f * A motor control method is provided for controlling the operation of each of the front motor 21 and the rear motor 31 based on the above.

[0118] This motor control method is performed by controlling the rotation speed of the front motor 21 at a first rotation speed (front motor angular velocity ω mf ), and the second rotation speed (rear motor angular velocity ω mr ) which is a basic torque command value of the front motor 21, and mf * ), and a second basic torque command value (rear target torque command value T mr * ) and a basic torque calculation step (step S202) for calculating the front motor angular velocity ω mf and front target torque command value T mf * Based on this, slip rotation speed control is performed to obtain the front final torque command value T mf_f * A first torque command value calculation process (front slip rotation speed control unit 603) for calculating a rear target torque command value T mr * Based on this, the rear final torque command value T mr_f * and a second torque command value calculation step (rear torque limit calculation section 601) for calculating:

[0119] In particular, in the second torque command value calculation process, a disturbance estimated value (disturbance torque estimated value T^ dist ) and the front final torque command value T mf_f * The rear target torque command value T mr * By limiting the rear final torque command value T mr_f * (see "805" in FIG. 8 and "702" and "703" in FIG. 7).

[0120] As a result, the torque command value (front final torque command value T mf_f *), and a parameter indicative of a disturbance including a slip component of the front wheels 22 and / or the rear wheels 32 (the disturbance torque estimate T^ dist ), the basic torque command value (rear target torque command value T mr * ) to limit the final torque command value (rear final torque command value T mr_f * ) can be determined. This reduces the amount of slip of the rear wheels 32 and suppresses the occurrence of spinning / locking.

[0121] More specifically, in this embodiment, in the second torque command value calculation process, the disturbance torque estimated value T^ dist The corrected disturbance torque estimate T^ corresponds to the value with the gradient resistance component removed. dist_lim ) is calculated (see the disturbance torque limiting unit 805 in FIG. 8 and FIG. 9). Then, the corrected disturbance torque estimated value T^ dist_lim and front target torque command value T mf * The rear target torque command value T mr * By limiting the rear final torque command value T mr_f * (see "702" and "703" in FIG. 7).

[0122] As a result, the disturbance torque estimated value T^ is obtained by collectively indexing various interference factors acting on the electric vehicle 10 (particularly, interference factors caused by gradients). dist The corrected disturbance torque estimate T^, which removes the gradient resistance component of the road, is dist_lim Then, the corrected disturbance torque estimate T^ can be obtained. dist_lim Using the rear target torque command value T mr * By limiting the rear final torque command value T mr_f * Therefore, when the electric vehicle 10 is traveling on a road having a gradient of at least a certain level, such as an uphill road or a downhill road, the occurrence of spinning / locking of the rear wheels 32 can be more reliably suppressed.

[0123] In particular, in the second torque command value calculation process, the rear motor angular velocity ω mr , Front final torque command value T mf_f * , and the rear final torque command value T mr_f * Based on the feedback value of dist (see "801" to "804" in FIG. 8). Then, when the electric vehicle 10 is driven (Yes in step S901 in FIG. 9), the corrected disturbance torque estimated value T^ is calculated. dist_lim The disturbance torque estimate T^ dist On the other hand, during regeneration of the electric vehicle 10, the corrected disturbance torque estimated value T^ is set to the following value (steps S902, S904, and S905). dist_lim The disturbance torque estimate T^ dist The above values ​​are set (steps S903, S906, and S907).

[0124] As a result, the corrected disturbance torque estimate T^ dist_lim The disturbance torque estimate T^ dist By setting the following, when the electric vehicle 10 is traveling on an uphill road, the rear target torque command value T mr * On the other hand, the occurrence of a situation in which the limit on the corrected disturbance torque estimate value T^ is insufficient (the actual output torque of the rear wheels 32 becomes excessive) can be suppressed. dist_lim The disturbance torque estimate T^ dist By setting the above, when the electric vehicle 10 is traveling on a downhill road, the rear target torque command value T mr * In other words, when the electric vehicle 10 is traveling on an uphill road or a downhill road, the electric vehicle 10 determines whether the electric vehicle 10 is in a driving state or a regenerative state, and adjusts the rear target torque command value T mr * More specific control logic can be implemented to appropriately adjust the

[0125] More specifically, in the second torque command value calculation process of the present embodiment, when the electric vehicle 10 is driven (Yes in step S901 in FIG. 9), the disturbance torque estimated value T^ dist If is greater than or equal to 0, the corrected disturbance torque estimate T^ dist_lim is set to 0 (Yes in step S902 and step S904), and the disturbance torque estimated value T^ dist If is less than 0, the disturbance torque estimate T^ dist The corrected disturbance torque estimate T^ dist_lim On the other hand, when the electric vehicle 10 is in regeneration mode (No in step S901), the disturbance torque estimated value T^ dist If is greater than or equal to 0, the disturbance torque estimate T^ dist The corrected disturbance torque estimate T^ dist_lim (Yes in step S903 and step S906), and the disturbance torque estimated value T^ dist If is less than 0, the corrected disturbance torque estimate T^ dist_lim is set to 0 (No in step S903 and step S907).

[0126] When the electric vehicle 10 is driven on an uphill road, the disturbance torque estimate T^ is affected by the gradient resistance component (opposite to the vehicle travel direction). dist On the other hand, the disturbance torque estimate T^ dist Since the slip component contained in is oriented along the vehicle travel direction, its value is negative. In contrast, with the above control, the corrected disturbance torque estimate T^ dist_lim Since the rear target torque command value T mr * This makes it possible to more reliably prevent the occurrence of a situation in which the restriction on the torque output from the rear wheels 32 is insufficient (a situation in which the actual output torque from the rear wheels 32 is excessive).

[0127] In addition, during regeneration when the electric vehicle 10 is traveling downhill, the disturbance torque estimate value T^ is affected by the gradient resistance component (direction along the vehicle travel direction). distOn the other hand, the disturbance torque estimate T^ dist Since the slip component contained in is opposite to the vehicle travel direction, its value is positive. On the other hand, with the above control, the corrected disturbance torque estimate T^ dist_lim Since the rear target torque command value T mr * This makes it possible to more reliably prevent the occurrence of a situation in which the restriction on the regenerative torque of the rear wheels 32 is insufficient (a situation in which the actual regenerative torque of the rear wheels 32 is excessive).

[0128] Furthermore, in this embodiment, a motor control device (motor controller 14, front inverter 23, and / or rear inverter 33) suitable for executing the above motor control method is provided.

[0129] This motor control device controls the first rotation speed (front motor angular velocity ω mf ), and the second rotation speed (rear motor angular velocity ω mr ) which is a basic torque command value of the front motor 21, and mf * ), and a second basic torque command value (rear target torque command value T mr * ) (step S202), and a basic torque calculation unit that calculates the front motor angular velocity ω mf and front target torque command value T mf * Based on this, slip rotation speed control is performed to obtain the front final torque command value T mf_f * A first torque command value calculation unit (front slip rotation speed control unit 603) that calculates a rear target torque command value T mr * Based on this, the rear final torque command value T mr_f * and a second torque command value calculation unit (rear torque limit calculation unit 601) that calculates the following.

[0130] In particular, the rear torque limit calculation unit 601 calculates a disturbance estimated value (disturbance torque estimated value T^ dist ) and the front final torque command value T mf_f * The rear target torque command value T mr * By limiting the rear final torque command value T mr_f * (see "805" in FIG. 8 and "702" and "703" in FIG. 7).

[0131] [Second embodiment] The second embodiment will be described below. The same elements as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In the motor control method of this embodiment, a disturbance estimation calculation unit 701 has a different configuration from that described in the first embodiment (see FIG. 8).

[0132] Fig. 13 is a block diagram showing details of the disturbance estimation calculation unit 701 of this embodiment. As shown in the figure, the disturbance estimation calculation unit 701 of this embodiment differs from the disturbance estimation calculation unit 701 shown in Fig. 7 in that a total torque command value correction unit 806 is added and the disturbance torque limiting unit 805 is not provided.

[0133] In particular, the total torque command value correction unit 806 corrects the final total torque command value T mto_f * from gradient resistance R g The obtained value is output to the second motor torque estimate value calculation unit 803. Note that the gradient resistance R g can be determined by referring to the detection value of a G sensor (not shown) provided in the electric vehicle 10, or road information that can be acquired from an external server.

[0134] Then, the second motor torque estimate calculation unit 803 calculates the second motor torque estimate from the above value. Furthermore, the subtraction unit 804 calculates a value obtained by subtracting the first motor torque estimate from the above second motor torque estimate as a corrected disturbance torque estimate T^. dist_lim That is, in this embodiment, the total torque command value correction unit 806 outputs the final total torque command value T mto_f * From the above, the gradient resistance R corresponding to the gradient resistance component included in the disturbance is g After removing the external disturbance torque estimate value T^, the external disturbance torque estimate value T^ is calculated by using the external disturbance torque estimate value T^ in the second motor torque estimate value calculation unit 803 and the subtraction unit 804. dist The corrected disturbance torque estimate T^ obtained by removing the gradient resistance component from dist_lim can be calculated directly.

[0135] According to the motor control method of the present embodiment described above, in the second torque command value calculation process (rear torque limit calculation unit 601), the gradient resistance R acting on the electric vehicle 10 is calculated. g and obtain the rear motor angular velocity ω mr , Front final torque command value T mf_f * , rear final torque command value T mr_f * The feedback value of and the gradient resistance R g Based on this, the corrected disturbance torque estimate T^ dist_lim Calculate.

[0136] As a result, the disturbance torque estimated value T^ is obtained by collectively indexing various interference factors acting on the electric vehicle 10 (particularly, interference factors caused by gradients). dist From the above, it is possible to realize one embodiment of a specific control logic for removing the gradient resistance component of the road. dist From the corrected disturbance torque estimate T^ dist_lim By omitting the determination process (the process shown in FIG. 9) for determining the above, the control logic can be further simplified.

[0137] [Third embodiment] The third embodiment will be described below, in which the same elements as those in the first or second embodiment are given the same reference numerals and the description thereof will be omitted.

[0138] Fig. 14 is a block diagram showing details of the rear torque limit calculation section 601 of this embodiment, and Fig. 15 is a block diagram showing details of the disturbance estimation calculation section 701 of this embodiment.

[0139] As shown in the figure, the disturbance estimation calculation unit 701 of this embodiment calculates the rear motor angular velocity ω mr , Front final torque command value T mf_f * , and rear final torque command value T mr_f * The disturbance torque estimate T^ is calculated using the feedback value of dist That is, the disturbance estimation calculation unit 701 of this embodiment calculates the disturbance torque estimate T^ including the gradient resistance component. dist This is output as is to the limit torque calculation unit 702.

[0140] The limit torque calculation unit 702 calculates the front final torque command value T mf_f * and the estimated disturbance torque T^ dist The torque limit value T lim That is, the limit torque calculation unit 702 of this embodiment calculates the corrected disturbance torque estimate value T^ input to the summation unit 1001 in the block shown in FIG. dist_lim The disturbance torque estimate T^ dist Based on the logic replaced by lim Calculate.

[0141] The torque limiting unit 703 is a front final torque command value T mf_f * , rear target torque command value T mr * , and the torque limit value T lim The rear final torque command value T mr_f * More specifically, the torque limiting unit 703 calculates the front final torque command value T mf_f* , rear target torque command value T mr * , and the torque limit value T lim The value obtained by performing the minimum select calculation on the rear final torque command value T mr_f * That is, the rear final torque command value T mr_f * is min[T mf_f * ,T mr * ,T lim ] can be calculated.

[0142] According to the motor control method of the present embodiment described above, in the second torque command value calculation process (rear torque limit calculation section 601), the rear motor angular velocity ω mr , Front final torque command value T mf_f * , and rear final torque command value T mr_f * Based on the feedback value of dist Calculate the disturbance torque estimate T^ dist and the front final torque command value T mf_f * Based on the torque limit value T lim Then, the front final torque command value T mf_f * , rear target torque command value T mr * , and the torque limit value T lim The smallest value among these is the rear final torque command value T mr_f * It is calculated as follows.

[0143] As a result, the disturbance torque estimated value T^ is obtained by collectively indexing various interference factors acting on the electric vehicle 10 (particularly, interference factors caused by gradients). dist While taking into account the gradient resistance component of the roadway included in the value, the rear target torque command value T mr * By limiting the rear final torque command value T mr_f *A specific control logic for calculating

[0144] [Control results] In the following, the control results when the motor control method (example) in the above embodiment is executed will be described while being compared with the control results when the motor control method according to the comparative example is executed.

[0145] 16 is a time chart showing the control result according to the comparative example. Note that the motor control method in the comparative example uses the disturbance torque estimation value T^ dist The motor control method differs from the motor control method of the embodiment in that no process is performed to remove the gradient resistance component from the vehicle speed. In addition, in the following description, for the sake of simplicity, it is assumed that the front / rear driving force distribution ratio is 50:50 (front / rear driving force distribution gain K f =0.5).

[0146] As shown in FIG. 16, in the control of the comparative example, at time t1, the front target torque command value T mf * and rear target torque command value T mr * The power running torque is applied to the front wheels 22, and the electric vehicle 10 starts accelerating. Then, at time t2, a slip state of the front wheels 22 is detected. For this reason, from time t2 onwards, the front slip rotation speed control is applied, and the front final torque command value T mf_f * is the front target torque command value T mf * Since the rear target torque command value T mr * Limiting calculation for the disturbance torque estimate T^ dist Torque limit value T based on lim This limits the rear final torque command value T mr_f * is the front final torque command value T mf_f * and the estimated disturbance torque T^ dist The sum of these is the rear target torque command value Tmr * Since the value is obtained by restricting the upper limit of the above, slippage of the rear wheels 32 is suppressed.

[0147] However, after time t3 when the electric vehicle 10 starts traveling uphill, the gradient becomes larger, and the disturbance torque estimated value T^ dist Therefore, the rear final torque command value T mr_f * As a result, at a subsequent time t4, the drive wheel speed of the rear wheels 32 becomes excessive with respect to the vehicle speed V, and the rear motor angular velocity ω mr The drive wheel speed of the front wheels 22, which are subjected to slip rotation speed control based on the front target rotation angular velocity determined from the above, also becomes excessive. As a result, the front wheels 22 and the rear wheels 32 start to spin.

[0148] On the other hand, as shown in FIG. 17, in the control of the embodiment, after time t3 when the electric vehicle 10 starts to travel uphill, the rear final torque command value T mr_f * is the estimated disturbance torque T^ dist Since the process for removing the gradient resistance component contained in the rear target torque command value T mr * By appropriately limiting the rear final torque command value T mr_f * can be determined, thereby suppressing overspinning of the rear wheels 32. As a result, the drive wheel speeds of the front wheels 22 and the rear wheels 32 are adjusted to appropriate values, suppressing spinning thereof.

[0149] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments.

[0150] For example, in each of the above embodiments, the control logic has been described assuming that the front wheels 22 and the front motor 21 are the first drive wheels and the first drive motor, respectively, and the rear wheels 32 and the rear motor 31 are the second drive wheels and the second drive motor, respectively. However, the control logic described in each of the above embodiments may be modified as appropriate to execute control in which the front wheels 22 and the front motor 21 are the second drive wheels and the second drive motor, respectively, and the rear wheels 32 and the rear motor 31 are the first drive wheels and the first drive motor, respectively.

[0151] Furthermore, each process in the above embodiment is executed based on a program for causing a computer to execute various processing procedures. The present embodiment can also be understood as an embodiment of a program for realizing a function for executing each process, and a recording medium for storing the program. For example, an update process for adding a new function to the control device of the electric vehicle 10 can store the program in the storage device of the control device. This makes it possible to cause the updated control device to execute each process shown in the present embodiment. [Explanation of symbols]

[0152] 10 Electric vehicles 11 Front-wheel drive system 12 Rear wheel drive system 13 Battery 14 Motor Controller 21 Front motor 22 Front wheel 23 Front inverter 31 Rear motor 32 Rear wheel 33 Rear inverter

Claims

1. A motor control method for an electric vehicle in which a plurality of drive wheels are independently driven by a plurality of drive motors, the method comprising: determining a first torque command value for a first drive motor that drives a first drive wheel and a second torque command value for a second drive motor that drives a second drive wheel; and controlling operations of the first drive motor and the second drive motor based on the first torque command value and the second torque command value, a rotation speed acquisition step of acquiring a first rotation speed which is a rotation speed of the first drive motor and a second rotation speed which is a rotation speed of the second drive motor; a base torque calculation step of calculating a first base torque command value which is a base torque command value of the first drive motor and a second base torque command value which is a base torque command value of the second drive motor; a first torque command value calculation step of calculating the first torque command value by executing slip rotation speed control based on the first rotation speed and the first basic torque command value; a second torque command value calculation step of calculating the second torque command value based on the second basic torque command value, In the second torque command value calculation step, calculating the second torque command value by limiting the second basic torque command value by a disturbance estimated value that is an estimate of a disturbance acting on the electric vehicle and the first torque command value; Motor control methods.

2. 2. A motor control method according to claim 1, comprising: In the second torque command value calculation step, calculating a corrected disturbance estimate value corresponding to a value obtained by removing a gradient resistance component from the disturbance estimate value; calculating the second torque command value by limiting the second basic torque command value using the corrected disturbance estimation value and the first torque command value; Motor control methods.

3. 3. A motor control method according to claim 2, comprising: In the second torque command value calculation step, calculating the disturbance estimation value based on the second rotation speed, the first torque command value, and a feedback value of the second torque command value; When the electric vehicle is driven, the corrected disturbance estimated value is set to a value equal to or less than the disturbance estimated value; During regeneration of the electric vehicle, the corrected disturbance estimated value is set to a value equal to or greater than the disturbance estimated value. Motor control methods.

4. 4. A motor control method according to claim 3, comprising: In the second torque command value calculation step, When the electric vehicle is driven, if the disturbance estimated value is equal to or greater than 0, the corrected disturbance estimated value is set to 0, and if the disturbance estimated value is less than 0, the disturbance estimated value is used as the corrected disturbance estimated value as it is; During regeneration of the electric vehicle, if the disturbance estimated value is equal to or greater than 0, the disturbance estimated value is used as the corrected disturbance estimated value, and if the disturbance estimated value is less than 0, the corrected disturbance estimated value is set to 0. Motor control methods.

5. 3. A motor control method according to claim 2, comprising: In the second torque command value calculation step, A gradient resistance acting on the electric vehicle is obtained; calculating the corrected disturbance estimation value based on the second rotational speed, the first torque command value, a feedback value of the second torque command value, and the gradient resistance; Motor control methods.

6. 2. A motor control method according to claim 1, comprising: In the second torque command value calculation step, calculating the disturbance estimation value based on the second rotation speed, the first torque command value, and a feedback value of the second torque command value; calculating a torque limit value based on the disturbance estimated value and the first torque command value; calculating, as the second torque command value, a smallest value among the first torque command value, the second basic torque command value, and the torque limit value; Motor control methods.

7. A motor control device for an electric vehicle in which a plurality of drive wheels are independently driven by a plurality of drive motors, the motor control device determining a first torque command value for a first drive motor that drives a first drive wheel and a second torque command value for a second drive motor that drives a second drive wheel, and controlling operations of the first drive motor and the second drive motor based on the first torque command value and the second torque command value, a rotation speed acquisition unit that acquires a first rotation speed that is a rotation speed of the first drive motor and a second rotation speed that is a rotation speed of the second drive motor; a base torque calculation unit that calculates a first base torque command value that is a base torque command value of the first drive motor and a second base torque command value that is a base torque command value of the second drive motor; a first torque command value calculation unit that calculates the first torque command value by executing slip rotational speed control based on the first rotation speed and the first basic torque command value; a second torque command value calculation unit that calculates the second torque command value based on the second basic torque command value, The second torque command value calculation unit calculating the second torque command value by limiting the second basic torque command value by a disturbance estimated value that is an estimate of a disturbance acting on the electric vehicle and the first torque command value; Motor control device.

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