Vehicle control device

Abstract

To provide a vehicular control device that is able to stabilize the traveling behavior of an electric vehicle in a low vehicle speed range.SOLUTION: A vehicular control device mounted on an electric vehicle is able to control a plurality of rotary electric machines that are able to drive a left wheel and a right wheel independently so as to reduce a wheel speed difference when the wheel speed difference occurs between the left wheel and the right wheel. When a correlation parameter correlated with a vehicle speed of the electric vehicle is less than a predetermined value, the control device controls, based on information on the rotation angle difference between the left wheel and the right wheel, the plurality of rotary electric machines so as to reduce the wheel speed difference.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 discloses a technology in which, in a control device for a vehicle with independent drive for left and right wheels, a final torque for each of the left and right wheels is calculated by adding or subtracting a speed difference correction torque calculated based on the rotational speeds of the left and right wheels to the torque command output from a torque command setting unit, and a final torque command that absorbs the imbalance in the speed difference between the left and right wheels is given to the left wheel drive motor and the right wheel drive motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-242506 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, since it is necessary to stabilize the vehicle's traveling behavior based on the minute difference in speed between the left and right wheels at low speeds, a higher accuracy in detecting the speed difference is desired.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a vehicle control device that can stabilize the traveling behavior of an electric vehicle in a low vehicle speed range. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the vehicle control device of the present invention is a vehicle control device mounted on an electric vehicle, which is capable of controlling a plurality of rotating electric machines capable of independently driving the left and right wheels, so as to reduce the wheel speed difference when a wheel speed difference occurs between the left and right wheels, and is characterized in that when a correlation parameter correlating with the vehicle speed of the electric vehicle is less than a predetermined value, the plurality of rotating electric machines are controlled so as to reduce the wheel speed difference based on information regarding the difference in rotational angle between the left and right wheels.

[0007] This makes it possible to accurately detect the occurrence of a wheel speed difference between the left and right wheels at low vehicle speeds using information relating to the difference in rotational angle between the left and right wheels, thereby stabilizing the driving behavior of the electric vehicle.

[0008] In the above, the information relating to a difference in rotation angle between the left wheel and the right wheel may be a difference in rotation angle between rotors included in each of the plurality of rotating electric machines.

[0009] As a result, even at low vehicle speeds, the occurrence of a wheel speed difference between the left and right wheels can be accurately detected using the difference in rotational angle of the rotors of the rotating electric motors that drive the left and right wheels, thereby stabilizing the driving behavior of the electric vehicle. Effect of the Invention

[0010] The vehicle control device according to the present invention has the advantage of being able to accurately detect the occurrence of a wheel speed difference between the left and right wheels using information relating to the difference in rotational angle between the left and right wheels, even at low vehicle speeds, thereby stabilizing the driving behavior of the electric vehicle. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an electric vehicle according to an embodiment. [Diagram 2]FIG. 2 is a block diagram showing an example of a control circuit for an electric vehicle according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing the setting of the velocity term gain (kv) and the angle term gain (kθ) by the controller. [Figure 4] FIG. 4 is a diagram showing the relationship between the vehicle speed and the angle term gain (kθ). [Diagram 5] FIG. 5 is a diagram showing the relationship between the vehicle speed and the speed term gain (kv). [Figure 6] FIG. 6 is a diagram for explaining the difference calculation process when setting the angle term gain (kθ). [Figure 7] FIG. 7 is a diagram showing an example of the offset cancellation process. [Figure 8] FIG. 8 is a flowchart showing an example of control performed by the cancellation determination unit. [Figure 9] FIG. 9 is a diagram showing signal waveforms of the rotation angles θL and θR. [Figure 10] FIG. 10 is a diagram showing an example of a method for calculating the rotation angle difference in the first pattern. [Figure 11] FIG. 11 is a diagram showing an example of a method for calculating the rotation angle difference in the second pattern. [Figure 12] FIG. 12 is a diagram showing an example of a method for calculating the rotation angle difference in the third pattern. [Figure 13] FIG. 13 is a diagram showing an example of a method for calculating the rotation angle difference in the fourth pattern. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle control device according to the present invention will be described below. However, the present invention is not limited to the embodiment.

[0013] Fig. 1 is a diagram showing a schematic configuration of an electric vehicle 100 according to an embodiment. As shown in Fig. 1, the electric vehicle 100 includes a left front wheel FL and a right front wheel FR, a left rear wheel RL and a right rear wheel RR, motor generators MGL, MGR, a battery 8, inverters 20L, 20R, and an ECU (Electronic Control Unit) 30. The electric vehicle 100 employs a two-wheel independent drive system in which the left front wheel FL and the right front wheel FR are drive wheels, and the left rear wheel RL and the right rear wheel RR are driven wheels, and the left front wheel FL and the right front wheel FR are independently driven by the motor generators MGL, MGR, respectively.

[0014] The electric vehicle 100 may be configured such that the left rear wheel RL and the right rear wheel RR are drive wheels, and the left front wheel FL and the right front wheel FR are driven wheels, with the left rear wheel FL and the right rear wheel FR being driven independently by the motor generators MGL and MGR, respectively. The electric vehicle 100 may also be configured such that one of the left front wheel FL and the right front wheel FR or the left rear wheel RL and the right rear wheel RR is driven independently by the motor generators MGL and MGR, and the other is driven by one common motor generator. The electric vehicle 100 may also be configured such that the four wheels, the left front wheel FL and the right front wheel FR, and the left rear wheel RL and the right rear wheel RR, are driven independently by four motor generators, respectively.

[0015] The motor generators MGL, MGR are connected to drive shafts 2, 4 of the left front wheel FL and the right front wheel FR, respectively, and independently drive the left front wheel FL and the right front wheel FR via the drive shafts 2, 4. The motor generators MGR, MGL are, for example, three-phase AC motors, and are driven by electric power stored in a battery 8.

[0016] During regenerative braking of electric vehicle 100, motor generators MGL, MGR are rotated by left and right front wheels FL, FR, respectively, to operate as generators. At this time, the electric power generated by motor generators MGL, MGR is charged into battery 8 via inverters 20L, 20R.

[0017] For example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery is used as the battery 8. Moreover, as a power storage device in place of the battery 8, a large-capacity capacitor such as an electric double-layer capacitor may be used.

[0018] The inverters 20L, 20R drive and control the motor generators MGL, MGR, respectively. When a DC voltage is supplied from the battery 8, the inverters 20L, 20R convert the DC voltage into an AC voltage based on signals PWMIL, PWMIR from the ECU 30 and supply the AC voltage to the motor generators MGL, MGR. As a result, the motor generators MGL, MGR are driven to generate a torque according to the required drive torque.

[0019] During regenerative braking of electric vehicle 100, inverters 20L, 20R convert the AC voltage generated by motor generators MGL, MGR to a DC voltage based on signals PWMIL, PWMIR from ECU 30 and supply the converted DC voltage to battery 8.

[0020] The electric vehicle 100 includes an accelerator position sensor 50 that detects an accelerator pedal position (accelerator opening) AP, a brake pedal position sensor 52 that detects a brake pedal position BP, a shift position sensor 54 that detects a shift position SP, a steering wheel 7, and a steering wheel angle (steering angle) θ of the steering wheel 7. s The electric vehicle 100 also includes wheel speed sensors 40, 42, 44, 46 that detect rotation speeds ωFL, ωFR of the left front wheel FL and the right front wheel FR and rotation speeds ωRL, ωRR of the left rear wheel RL and the right rear wheel RR, respectively. The electric vehicle 100 also includes a steering angle sensor 56 that detects rotation speeds ωFL, ωFR of the left front wheel FL and the right front wheel FR and rotation speeds ωRL, ωRR of the left rear wheel RL and the right rear wheel RR. L ,θ R The detection signals from these sensors are input to the ECU 30.

[0021] The ECU 30 is a vehicle control device that is electrically connected to the inverters 20L, 20R and the battery 8, and controls the driving state of the motor generators MGR, MGL and the charging state of the battery 8 in an integrated manner.

[0022] Here, in the electric vehicle 100 according to the embodiment, the left front wheel FL and the right front wheel FR are driven independently by the motor generators MGL and MGR, respectively. Therefore, if a speed difference occurs between the rotational speeds (wheel speeds) ωFL and ωFR of the left front wheel FL and the right front wheel FR, the traveling behavior of the electric vehicle 100 may become unstable.

[0023] For example, when the electric vehicle 100 is traveling on a highway, the vehicle speed is high, and if it encounters a crosswind when exiting a tunnel or overtaking a large vehicle, a trajectory deviation (yaw movement and inner / outer wheel difference) occurs in the electric vehicle 100, resulting in a wheel speed difference between the left front wheel FL and the right front wheel FR.

[0024] In addition, for example, when the electric vehicle 100 is stopped at an intersection or the like, if the vehicle speed is low and the left front wheel FL and right front wheel FR are in ruts formed on the road surface, a wandering phenomenon occurs in which the left front wheel FL and right front wheel FR move sideways within the rut, resulting in a wheel speed difference between the left front wheel FL and right front wheel FR.

[0025] Therefore, in the electric vehicle 100 according to this embodiment, when a wheel speed difference occurs between the left front wheel FL and the right front wheel FR, the ECU 30 controls the motor generators MGL, MGR so as to reduce the wheel speed difference.

[0026] The wheel speed difference between the left front wheel FL and the right front wheel FR, which occurs when the electric vehicle 100 is in a high vehicle speed range, is sufficiently large and easy to detect. On the other hand, the wheel speed difference between the left front wheel FL and the right front wheel FR, which occurs when the electric vehicle 100 is in a low vehicle speed range, is extremely small and difficult to detect.

[0027] Therefore, in the electric vehicle 100 according to the embodiment, when a correlation parameter (vehicle speed or wheel speed) correlated with the vehicle speed is less than a predetermined value, in other words, when the vehicle speed is in a low vehicle speed range, the ECU 30 uses the rotation angle θ of the rotors provided in the motor generators MGL, MGR as information regarding the rotation angles of the left front wheel FL and the right front wheel FR. L ,θ R On the basis of the difference between the wheel speeds, the ECU 30 controls the motor generators MGL, MGR so as to reduce the wheel speed difference. Furthermore, when a correlation parameter correlating with the vehicle speed is equal to or greater than a predetermined value, in other words, for example, in a high vehicle speed range, the ECU 30 controls the motor generators MGL, MGR on the basis of the wheel speed difference between the left front wheel FL and the right front wheel FR so as to reduce the wheel speed difference.

[0028] Fig. 2 is a block diagram showing an example of a control circuit of the electric vehicle 100 according to the embodiment. Fig. 3 is a diagram showing settings of a speed term gain (kv) and an angle term gain (kθ) by the controller 32. Fig. 4 is a diagram showing the relationship between the vehicle speed and the angle term gain (kθ). Fig. 5 is a diagram showing the relationship between the vehicle speed and the speed term gain (kv).

[0029] As shown in FIG. 2, the ECU 30 calculates a pre-correction driving force F based on the accelerator position AP detected by the accelerator position sensor 50, the shift position SP detected by the shift position sensor 54, and the like. x_L ,F x_R The controller 32 of the ECU 30 controls the rotation angle θ L ,θ R The corrected driving force F' is calculated by using the corrected driving force F'. x_L ,F' x_R to inverters 20L, 20R which perform drive control of motor generators MGL, MGR.

[0030] As shown in FIG. 3, the controller 32 detects the rotation angle θ L ,θ RIn order to reduce the wheel speed difference between the left front wheel FL and the right front wheel FR, a speed term gain (kv) and an angle term gain (kθ) are set as control gains of a feedback control that corrects the pre-correction driving force with the correction driving force using the above formula. That is, as shown in FIG. 3, in the controller 32, a differential processing unit 322 calculates the rotation angle θ L ,θ R 3, the controller 32 performs a differential process on the rotation angle θ L ,θ R 4 and 5, the angle term gain setting unit 330 sets the angle term gain (kθ) by performing a difference calculation process on the above. At this time, as shown in FIG. 4 and FIG. 5, the angle term gain (kθ) is increased in a low vehicle speed range (for example, a vehicle speed of 20 [km / s] or less), and the speed term gain (kv) is increased in a high vehicle speed range (for example, a vehicle speed of 80 [km / s] or more).

[0031] 6 is a diagram for explaining the difference calculation process performed by the difference calculation unit 328 to set the angle term gain (kθ). L ,θ R In the method of detecting the wheel speed difference using the rotation angle difference as in the present embodiment, when the electric vehicle 100 is moving straight, the rotation angle θ L ,θ R Therefore, in the difference calculation process performed by the difference calculation unit 328 to set the angle term gain (kθ), as shown in FIG. 7, when the ECU 30 determines that the electric vehicle 100 is in a straight-line state while it is traveling, the ECU 30 subtracts the rotation angle at the time when the straight-line state was determined (time T in FIG. 7) as an offset amount to obtain the rotation angle θ L ,θ R At the same time, an offset cancellation process is performed to reset the offset to 0[deg].

[0032] The determination as to whether or not to perform the offset cancel process is made by a cancel determination unit 340 of the controller 32 based on the vehicle speed and the steering angle θs This is performed by determining whether or not the electric vehicle 100 is moving straight based on the above.

[0033] FIG. 8 is a flowchart showing an example of the control executed by the cancellation determination unit 340. As shown in FIG.

[0034] First, in step S1, the cancellation determination unit 340 determines whether or not the vehicle speed is greater than a preset threshold value A. When the cancellation determination unit 340 determines that the vehicle speed is greater than the threshold value A (Yes in step S1), in step S2, the cancellation determination unit 340 cancels the steering wheel angle θ s The cancellation determination unit 340 determines whether the absolute value of the steering wheel angle θ is smaller than a preset threshold value B. s If it is determined that the absolute value of is smaller than threshold value B (Yes in step S2), it is determined in step S3 that the electric vehicle 100 is in a straight-ahead state, the cancel execution flag is turned ON, and the series of controls is terminated.

[0035] Furthermore, if the cancellation determination unit 340 determines that the vehicle speed is not greater than the threshold A (No in step S1), then in step S4 it determines that the electric vehicle 100 is not traveling straight, turns off the cancellation execution flag, and ends the series of controls.

[0036] In addition, the cancellation determination unit 340 determines whether the steering wheel angle θ s If it is determined that the absolute value of is not smaller than threshold value B (No in step S2), it is determined in step S4 that the electric vehicle 100 is not moving straight, the cancellation execution flag is turned OFF, and the series of controls is terminated.

[0037] Then, when the cancellation determination unit 340 determines that the electric vehicle 100 is moving straight, the "cancellation execution flag" is turned ON, and the rotation angle θ L ,θ R The offset cancelling units 342L and 342R of the controller 32 carry out offset cancelling processing on this signal.

[0038] Rotation angle θ after offset cancellation processing is performed L ,θ R The rotation angle difference calculation unit 344 performs a rotation angle difference calculation process to obtain the rotation angle difference (Δθ F ) is calculated.

[0039] FIG. 9 shows the rotation angle θ L ,θ R As shown in FIG. 9, the rotation angle θ L ,θ R The signal is a sawtooth wave of 0 to 360[deg]. On the other hand, the rotation angle θ L ,θ R When the difference between the rotation angles θ is calculated, the rotation angle difference may jump. Therefore, the rotation angle difference calculation unit 344 corrects and calculates the rotation angle difference based on the four condition patterns of the first pattern to the fourth pattern. L and the rotation angle θ R The difference in rotation angle is the rotation angle θ L from rotation angle θ R The value minus (θ L -θ R ) is the default value, and this default value (θ L -θ R ) and make appropriate corrections.

[0040] Fig. 10 is a diagram showing an example of a method for calculating the rotation angle difference in the first pattern. In Fig. 10, ΔT is a control period, and n and n-1 are the number of periods. In Fig. 10, an upward arrow indicates that the rotation angle difference is a positive value.

[0041] The first pattern is a rotation angle θ at time (n-1)ΔT. L and the rotation angle θ R The difference in rotation angle between F (n-1) is a positive value (dθ F (n-1)>0) and the rotation angle θ at time nΔT L and the rotation angle θ R The difference in rotation angle between F (n) is a positive value (dθF In the first pattern, the rotation angle difference is Δθ F =θ L -θ R It is calculated as follows.

[0042] Fig. 11 is a diagram showing an example of a method for calculating the rotation angle difference in the second pattern. In Fig. 11, an upward arrow indicates that the rotation angle difference is a positive value, and a downward arrow indicates that the rotation angle difference is a negative value.

[0043] The second pattern is the rotation angle θ at time (n-1)ΔT. L and the rotation angle θ R The difference in rotation angle between F (n-1) is a positive value (dθ F (n-1)>0) and the rotation angle θ at time nΔT L and the rotation angle θ R The difference in rotation angle between F (n) is a negative value (dθ F In the second pattern, the rotation angle difference is Δθ F =θ L -θ R Calculated as +360.

[0044] FIG. 12 shows the rotation angle difference Δθ in the third pattern. F 12 is a diagram showing an example of a method for calculating the rotation angle difference. In FIG. 12, a downward arrow indicates that the rotation angle difference is a negative value.

[0045] The third pattern is the rotation angle θ at time (n-1)ΔT. L and the rotation angle θ R The difference in rotation angle between F (n-1) is a negative value (dθ F (n-1)<0), and the rotation angle θ at time nΔT L and the rotation angle θ R The difference in rotation angle between F (n) is a negative value (dθ F In the third pattern, the rotation angle difference is Δθ F =θL -θ R It is calculated as follows.

[0046] Fig. 13 is a diagram showing an example of a method for calculating the rotation angle difference in the fourth pattern. In Fig. 13, an upward arrow indicates that the rotation angle difference is a positive value, and a downward arrow indicates that the rotation angle difference is a negative value.

[0047] The fourth pattern is the rotation angle θ at time (n-1)ΔT. L and the rotation angle θ R The difference in rotation angle between F (n-1) is a negative value (dθ F (n-1)<0), and the rotation angle θ at time nΔT L and the rotation angle θ R The difference in rotation angle between F (n) is a positive value (dθ F In the fourth pattern, the rotation angle difference is Δθ F =θ L -θ R Calculated as -360.

[0048] Returning to FIG. 3, the controller 32 controls the rotation angle θ L ,θ R The signals of the velocity term gain (kv) and angle term gain (kθ) set by carrying out the various processes described above using are input to a calculator 332 where they are added, and are finally output as a corrected driving force.

[0049] Returning to FIG. 2, the signal of the corrected driving force output from the controller 32 is input to a calculator 34L for the left front wheel and a calculator 34R for the right front wheel, which respectively calculate the pre-correction driving force F x_L ,F x_R and the final corrected driving force F' x_L ,F' x_R The inverters 20L and 20R output the corrected driving forces F' to the motor generators MGL and MGR, respectively. x_L ,F' x_RIn this way, it is possible to reduce the wheel speed difference between the left front wheel FL and the right front wheel FR driven by the motor generators MGL, MGR.

[0050] In the electric vehicle 100 according to the embodiment, in a low vehicle speed range where a correlation parameter correlated with the vehicle speed is less than a predetermined value, the ECU 30 uses the rotation angle θ of the rotors of the motor generators MGL and MGR as information about the rotation angles of the left front wheel FL and the right front wheel FR, rather than the wheel speed difference between the left front wheel FL and the right front wheel FR. L ,θ R Based on the difference between the rotation angles θ, the motor generators MGL and MGR are feedback-controlled so as to reduce the wheel speed difference. As a result, in the electric vehicle 100 according to the embodiment, even in a low vehicle speed range, the occurrence of a wheel speed difference between the left front wheel FL and the right front wheel FR is detected by the motor generators MGL and MGR. L ,θ R By using the difference between these values, it is possible to accurately detect the driving behavior of the electric vehicle 100 and stabilize it. [Explanation of symbols]

[0051] 8 Battery 20L, 20R inverter 30 ECU 32 Controller 34L,34R,332 Arithmetic unit 40, 42, 44, 46 Wheel speed sensor 50 Accelerator position sensor 52 Brake pedal position sensor 54 Shift position sensor 56 Steering angle sensor 60L, 60R Rotation angle sensor 100 Electric Vehicles 340 Cancellation Judgment Unit 342L, 342R offset cancel part 344 Rotation angle difference calculation unit FL front left wheel FR right front wheel RL left rear wheel RR right rear wheel MGL, MGR Motor generator

Claims

1. A vehicle control device mounted on an electric vehicle, the vehicle control device being capable of controlling a plurality of rotating electric machines capable of independently driving a left wheel and a right wheel, when a wheel speed difference occurs between the left wheel and the right wheel, so as to reduce the wheel speed difference, a control device for a vehicle, characterized in that, when a correlation parameter correlating with a vehicle speed of the electric vehicle is less than a predetermined value, the plurality of rotating electric machines are controlled so as to reduce the wheel speed difference based on information regarding a rotation angle difference between the left wheel and the right wheel.

2. 2. The vehicle control device according to claim 1, wherein the information regarding the difference in rotation angle between the left wheel and the right wheel is a difference in rotation angle between rotors provided in the plurality of rotating electric machines.

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