Control device

Abstract

To execute damping control with little adverse effect even when a vehicle passes a step on a road surface.SOLUTION: A control device for controlling a vehicle drive device including a rotary electric machine includes a step entry determination unit, an acceleration / deceleration state determination unit, a damping torque calculation unit, and a damping control unit. The damping control unit causes the rotary electric machine to output restricted damping torque smaller than normal damping torque calculated by the damping torque calculation unit when a wheel has entered a step and a predetermined restriction condition is satisfied.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] For example, vehicles equipped with rotating electric machines as drive power sources for wheels, such as electric vehicles and hybrid vehicles, are in use. An example of a control device for controlling such a vehicle drive device is disclosed in Japanese Patent Laid-Open Publication No. 2023-46935 (Patent Document 1).

[0003] The control device (control device 20) of Patent Document 1 is configured to be able to execute vibration suppression control that cancels or suppresses vibration components that may be included in the rotation speed of the wheel (wheel 2f) by using the torque of the rotating electric machine (motor generator 16) in order to avoid adverse effects on ABS control caused by the vibration components. The torque (damping torque) of the rotating electric machine output by this vibration suppression control is determined so as to have an opposite phase to the vibration components that should be canceled or suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-46935 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the vibration damping control described in Patent Document 1 is not necessarily effective in all situations. For example, when a vehicle passes over a step on the road surface, the wheels may lift off the road surface at the step. If such lifting of the wheels occurs, the vibration damping control may increase torsion in the power transmission system when the vehicle subsequently touches down again, which may actually increase vibration in the vehicle.

[0006] Therefore, it is desirable to be able to perform vibration suppression control with minimal adverse effects even when the vehicle passes over a step on the road surface. [Means for solving the problem]

[0007] The control device according to the present disclosure includes: A control device for controlling a vehicle drive device including a rotating electric machine and a power transmission system that transmits a driving force of the rotating electric machine to wheels, a step entry determination unit that determines whether the wheel has entered a step on a road surface; an acceleration / deceleration state determination unit that determines an acceleration / deceleration state of the vehicle; a damping torque calculation unit that calculates a damping torque of the rotating electric machine for reducing torsion occurring in the power transmission system; a vibration damping control unit that controls the vibration damping torque output from the rotating electric machine, The vibration-damping torque calculated by the vibration-damping torque calculation unit is set as a normal vibration-damping torque, When the step entry determination unit determines that the wheel has entered the step, and the acceleration / deceleration state of the vehicle and the speed difference between the rotational speed of the wheel and the rotational speed of the rotating electric machine converted to the same position in the power transmission system satisfy predetermined restriction conditions, the vibration control unit outputs a limited vibration control torque that is smaller than the normal vibration control torque to the rotating electric machine as the vibration control torque.

[0008] With this configuration, it is possible to determine a situation in which wheel lift is likely to occur when the vehicle passes over a bump on the road surface, based on the acceleration / deceleration state of the vehicle and the rotational speed difference (converted value) between the wheel and the rotating electric machine. When such a situation is determined, a post-limiting damping torque that is smaller than the normal damping torque calculated by the damping torque calculation unit is output to the rotating electric machine as the damping torque, thereby minimizing torsion occurring in the power transmission system. In other words, even when the vehicle passes over a bump on the road surface, vibration damping control can be performed with minimal adverse effects.

[0009] Further features and advantages of the techniques according to the present disclosure will become more apparent from the following description of exemplary and non-limiting embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a vehicle equipped with a vehicle drive device and a control device according to an embodiment; [Figure 2] Control device block diagram [Figure 3] Conceptual diagram of how to determine damping torque (normal damping torque) [Figure 4] Schematic diagram showing the behavior of a vehicle when passing over a step [Figure 5] Time chart of each part during vibration suppression control during deceleration [Figure 6] Flowchart showing the processing procedure for vibration suppression control [Figure 7] Results of a demonstration experiment on the vibration reduction effect of vibration suppression control [Figure 8] Graph showing the relationship between the output time of the limited vibration suppression torque and the peak value of the drive shaft torque DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the control device will be described with reference to the drawings. As shown in Fig. 1, this control device 1 is a control device for a vehicle drive device that controls a vehicle drive device 3 mounted on a vehicle V. In this embodiment, the vehicle V is described as an electric vehicle (electrically driven vehicle) as an example. That is, the control device 1 of this embodiment is a control device for an electric vehicle drive device.

[0012] In the following description, the term "rotating electric machine" is used as a concept that includes motors (electric motors), generators (electric generators), and motor-generators that function as both motors and generators as needed.

[0013] As shown in FIG. 1, the vehicle drive device 3 includes a rotating electric machine 31, a power transmission device 32, and an output shaft 33. These are housed in a case 35. The rotating electric machine 31 functions as a driving force source for the wheels W. As is well known, the rotating electric machine 31 includes a stator fixed to the case 35, which is a non-rotating member, and a rotor rotatably supported radially inside the stator. The rotating electric machine 31 receives a supply of electric power from an electric storage device (not shown) for power running, or supplies electric power generated by the inertial force of the vehicle or the like to the electric storage device for storage.

[0014] The power transmission device 32 is provided in a power transmission path connecting the rotating electric machine 31 and the wheels W, and transmits the driving force of the rotating electric machine 31 to the wheels W. The power transmission device 32 is configured to include, for example, a speed change mechanism, a differential gear mechanism, etc., and may also be configured to include, for example, a counter drive mechanism, a clutch, etc. The output shafts 33 function as output members of the vehicle drive system 3, and are provided in pair on the left and right. Each of the pair of output shafts 33 is drivingly connected to the wheels W (specifically, the front wheels) via, for example, a drive shaft. In this embodiment, the various shafts, gears, engaging members, etc. included in the power transmission device 32 and the output shafts 33 form a "power transmission system."

[0015] The control device 1 functions as a core for controlling the operation of each part of the vehicle drive device 3. The control device 1 mainly controls the operation of the rotating electric machine 31 as a driving force source for the wheels W. The control device 1 is configured to include, for example, an inverter circuit including a switching element, a smoothing capacitor, a control board, etc., and may also be configured to include, for example, a boost circuit, etc. In the illustrated example, the control device 1 is provided integrally with a case 35 of the vehicle drive device 3.

[0016] 2, the control device 1 includes an integrated control unit 11, a rotating electrical machine control unit 12, a vibration-damping torque calculation unit 13, a step approach determination unit 14, an acceleration / deceleration state determination unit 15, and a vibration-damping control unit 16. Each of these functional units is configured by software (programs) stored in a storage medium such as a memory, or by hardware such as a separately provided arithmetic circuit, or by both. The functional units are configured to be able to exchange information with each other. The control device 1 is also configured to be able to acquire information on the detection results of various sensors (in this example, first sensor 41 to sixth sensor 46) provided in various parts of the vehicle V.

[0017] The first sensor 41 detects the rotation speed of the rotating electric machine 31 (specifically, the rotor). The second sensor 42 detects the rotation speed of the wheels W. The third sensor 43 detects the amount of operation of an accelerator pedal (accelerator opening) provided on the vehicle V. The fourth sensor 44 detects the amount of operation of a brake pedal (brake operation amount) provided on the vehicle V. The fifth sensor 45 detects the vehicle speed (travel speed of the vehicle V; vehicle body speed). The sixth sensor 46 detects the vertical acceleration of a spring in a suspension provided on the vehicle V.

[0018] The control device 1 can also calculate the rotational acceleration, which is the rate of change over time, based on the rotational speed of each rotating member detected by the first sensor 41 and the second sensor 42. The control device 1 can also calculate the rate of change over time based on the vehicle speed detected by the fifth sensor 45.

[0019] The integrated control unit 11 performs control that integrates various controls necessary for the vehicle V to travel as a whole of the vehicle V. The integrated control unit 11 calculates the torque required to drive the vehicle V (vehicle required torque) based on, for example, vehicle speed information calculated based on the detection result by the second sensor 42 and accelerator opening information detected by the third sensor 43. If the rotating electric machine 31 is the only driving force source for the wheels W as in this embodiment, the vehicle required torque becomes the torque required of the rotating electric machine 31 (rotating electric machine required torque).

[0020] Furthermore, in this embodiment, the integrated control unit 11 calculates the torque (required braking torque) required to decelerate the vehicle V based on, for example, the amount of brake operation detected by the fourth sensor 44. The integrated control unit 11 determines the share (hydraulic braking portion) of the hydraulic brakes provided on the vehicle and the share (regenerative braking portion) of the negative torque output by the rotating electric machine 31 to cover the required braking torque.

[0021] The rotating electric machine control unit 12 controls the rotating electric machine 31. The rotating electric machine control unit 12 can execute torque control and rotational speed control of the rotating electric machine 31 according to the running state of the vehicle. Torque control of the rotating electric machine 31 is control that commands a target torque (for example, a torque according to the above-mentioned rotating electric machine required torque or braking torque) to the rotating electric machine 31 and makes the output torque of the rotating electric machine 31 follow the target torque. Rotational speed control of the rotating electric machine 31 is control that commands a target rotational speed to the rotating electric machine 31 and adjusts the output torque so that the rotational speed of the rotating electric machine 31 follows the target rotational speed.

[0022] The rotating electric machine control unit 12 mainly controls the rotating electric machine 31 to output torque for driving the vehicle V, i.e., vehicle required torque (rotating electric machine required torque). Furthermore, when decelerating the vehicle V, the rotating electric machine control unit 12 controls the rotating electric machine 31 to output a regenerative braking portion of the required braking torque. Furthermore, the rotating electric machine control unit 12 controls the rotating electric machine 31 to output a damping torque determined by the damping control unit 16, separate from the vehicle required torque (rotating electric machine required torque) and the regenerative braking portion of the required braking torque.

[0023] Damping torque calculation unit 13 calculates damping torque. Damping torque is torque that is output to rotating electric machine 31 to reduce torsion that occurs in the power transmission system. The power transmission system includes various shafts, gears, etc., and even when these rotate in conjunction with one another, the rotational speeds on the upstream side (the rotating electric machine 31 side, which is the driving force source) and the downstream side (the wheel W side) may not completely match due to the influence of inertia, disturbance, etc., causing torsion. Damping torque is calculated as torque for reducing, and preferably eliminating, such torsion.

[0024] 3, while the rotational speed of the wheel W (hereinafter referred to as "wheel speed") decreases at a constant rate of change, the converted rotational speed of the rotating electric machine 31 at the position of the wheel W (hereinafter simply referred to as "converted rotational speed" of the rotating electric machine 31) periodically decreases and increases repeatedly. Here, the difference between the wheel speed and the converted rotational speed of the rotating electric machine 31, i.e., the value obtained by subtracting the wheel speed from the converted rotational speed of the rotating electric machine 31, is referred to as "differential rotation" in this embodiment. (Differential rotation) = (Converted rotation speed of the rotating electrical machine 31) - (Wheel speed)

[0025] In this example, during periods (a) and (b), the converted rotational speed of rotating electric machine 31 is lower than the wheel speed, and the differential rotation is negative. Therefore, during these periods, a positive vibration-damping torque is calculated to increase the converted rotational speed of rotating electric machine 31 so that the differential rotation approaches zero. In this case, during period (a), the positive vibration-damping torque is calculated to gradually increase in response to the gradual increase in the negative differential rotation, and during period (b), the positive vibration-damping torque is calculated to gradually decrease in response to the gradual decrease in the negative differential rotation. The same is true for periods (e) and (f).

[0026] Furthermore, in periods (c) and (d), the converted rotational speed of rotating electric machine 31 is higher than the wheel speed, and the differential rotation is positive. For this reason, in these periods, a negative vibration-damping torque is calculated to decrease the converted rotational speed of rotating electric machine 31 so that the differential rotation approaches zero. In this case, in period (c), the negative vibration-damping torque is calculated to gradually increase on an absolute value basis in response to the gradual increase in the positive differential rotation, and in period (d), the negative vibration-damping torque is calculated to gradually decrease on an absolute value basis in response to the gradual decrease in the positive differential rotation.

[0027] In this way, roughly speaking, the vibration damping torque is calculated as a torque that vibrates in the opposite phase to the vibration of the differential rotation and that increases in absolute value standard as the differential rotation increases. In this embodiment, the vibration damping torque calculated by vibration damping torque calculation unit 13 is referred to as "normal vibration damping torque". In other words, vibration damping torque calculation unit 13 calculates normal vibration damping torque so that it vibrates in the opposite phase to the vibration of the differential rotation and that increases in absolute value standard as the differential rotation increases.

[0028] Incidentally, there may be a step D on the road surface R that is too large to ignore when the vehicle V is traveling. FIG. 4 shows an example of the behavior of the vehicle V when passing over the step D. In this example, it is assumed that the vehicle V passes over the step D while decelerating in response to a brake operation. When the wheel W (here, the front wheel, which is the drive wheel) passes over the step D, the wheel W temporarily lifts off the road surface R, during which the wheel speed drops sharply (times t1 to t2 in FIG. 5). After that, when the wheel W contacts the road surface R, the grip force is restored and the wheel speed recovers to a rotational speed corresponding to the vehicle speed (times t2 to t3). After that, the wheel W bounces, temporarily lifts off the road surface R again, and the wheel speed drops sharply (times t3 to t4), and the wheel speed may recover to a rotational speed corresponding to the vehicle speed when the wheel W contacts the road surface again (times t4 to t5). This process may be repeated.

[0029] In such a case, there is a concern that performing vibration damping control using the normal vibration damping torque calculated by vibration damping torque calculation unit 13 may actually exacerbate torsion in the power transmission system. That is, when wheel W first lifts off road surface R, the wheel speed drops suddenly as described above. Although rotating electric machine 31 follows suit, the rotation change is delayed due to its large inertia, resulting in a positive differential rotation. Therefore, the normal vibration damping torque that cancels this is a negative torque (shown by the dashed line in FIG. 5). Thereafter, wheel W returns to the ground, causing a sudden increase in wheel speed, and the rotation change of rotating electric machine 31 is delayed, resulting in a state of reduced rotation speed for a while, resulting in a negative differential rotation. If a negative normal vibration damping torque is applied when or shortly before a negative differential rotation occurs, there is the adverse effect of increasing torsion in the power transmission system.

[0030] In order to reduce such adverse effects as much as possible, the control device 1 of this embodiment is provided with a step approach determination unit 14, an acceleration / deceleration state determination unit 15, and a vibration suppression control unit 16.

[0031] The step entry determination unit 14 determines whether the wheel W (here, the drive wheel) has entered a step D on the road surface R. The step entry determination unit 14 determines whether the wheel W has entered the step D based on the rotational acceleration of the wheel W, the slip state of the wheel W in relation to the vehicle speed, and the vertical acceleration of the suspension spring. In this embodiment, the step entry determination unit 14 determines whether the wheel W has entered the step D based on all three of these factors.

[0032] The condition regarding the rotational acceleration of the wheel W is that the rotational acceleration of the wheel W is equal to or greater than a predetermined sudden change threshold in absolute value. The condition regarding the slip state of the wheel W is that the difference between the actual rotational speed of the wheel W and the estimated rotational speed of the wheel W based on the vehicle speed is equal to or greater than a predetermined slip threshold. The condition regarding the vertical acceleration of the spring is that the vertical acceleration of the spring is equal to or greater than a predetermined fluctuation threshold in absolute value.

[0033] The rotational speed of the wheel W is detected by the second sensor 42, and the rotational acceleration is calculated in the control device 1 based on the detected value. The estimated rotational speed of the wheel W according to the vehicle speed is calculated by proportional calculation in the control device 1 based on the vehicle speed detected by the fifth sensor 45. The vertical acceleration of the spring is detected by the sixth sensor 46. The specific values ​​of the sudden change threshold, slip threshold, and fluctuation threshold may each be set appropriately according to the required specifications.

[0034] In this embodiment, the step entry determination unit 14 determines that the wheel W has entered a step D when all of the conditions related to the rotational acceleration of the wheel W, the slip state of the wheel W, and the vertical acceleration of the suspension spring are satisfied. The step entry determination unit 14 determines that the wheel W has not entered a step D when at least one of the above three conditions is not satisfied. The step entry determination unit 14 outputs the determination result as to whether the wheel W has entered a step D to the vibration damping control unit 16.

[0035] The acceleration / deceleration state determination unit 15 determines the acceleration / deceleration state of the vehicle V. The acceleration / deceleration state determination unit 15 determines whether the vehicle V is in an accelerating state, a decelerating state, or neither an accelerating state nor a decelerating state. In this embodiment, the acceleration / deceleration state determination unit 15 determines the acceleration / deceleration state of the vehicle V based on the rate of change of the vehicle speed, whether or not the accelerator pedal is operated, and whether or not the brake is operated. The acceleration / deceleration state determination unit 15 determines that the vehicle V is in an accelerating state when the rate of change of the vehicle speed is positive when the accelerator pedal is operated. The acceleration / deceleration state determination unit 15 determines that the vehicle V is in a decelerating state when the brake is operated and the rate of change of the vehicle speed is negative. The acceleration / deceleration state determination unit 15 determines that the vehicle V is neither in an accelerating state nor a decelerating state when neither of the above two cases applies.

[0036] The rate of change of the vehicle speed is calculated in the control device 1 based on the vehicle speed detected by the fifth sensor 45. Whether or not the accelerator is operated is determined based on the detected value of the third sensor 43, and whether or not the brake is operated is determined based on the detected value of the fourth sensor 44. The acceleration / deceleration state determination unit 15 outputs the determination result regarding the acceleration / deceleration state of the vehicle V to the vibration damping control unit 16.

[0037] Vibration damping control unit 16 controls the vibration damping torque to be output to rotating electric machine 31. In principle, vibration damping control unit 16 causes rotating electric machine 31 to output the normal vibration damping torque calculated by vibration damping torque calculation unit 13, but under specific conditions causes rotating electric machine 31 to output limited vibration damping torque that is smaller than the normal vibration damping torque. In this embodiment, the specific conditions are that it is determined that wheel W has entered step D, and the acceleration / deceleration state of vehicle V and the speed difference between the rotational speed of wheel W and the rotational speed of rotating electric machine 31 in a state converted to the same position in the power transmission system satisfy a predetermined limiting condition.

[0038] Here, whether or not the wheel W has entered the step D is determined by the step entry determination unit 14 as described above, and the determination result is output from the step entry determination unit 14 to the vibration damping control unit 16. Based on the information on the determination result received from the step entry determination unit 14, the vibration damping control unit 16 determines whether or not the specific condition (particularly, the step entry condition, which is the first requirement) is satisfied.

[0039] Conceptually, the limiting condition is a condition that indicates a situation in which the change in the rotational speed of the rotating electric machine 31 lags behind the change in the rotational speed of the wheel W due to the wheel W lifting off the ground. More specifically, the limiting condition is that the vehicle V is in an accelerating state when entering the step D, and the converted rotational speed of the wheel W is higher than the converted rotational speed of the rotating electric machine 31, or that the vehicle V is in a decelerating state when entering the step D, and the converted rotational speed of the wheel W is lower than the converted rotational speed of the rotating electric machine 31.

[0040] Here, the acceleration / deceleration state of vehicle V when approaching step D is determined by acceleration / deceleration state determination unit 15 as described above, and the determination result is output from acceleration / deceleration state determination unit 15 to vibration damping control unit 16. Furthermore, the rotational speed of rotating electric machine 31 is detected by first sensor 41, and the rotational speed of wheel W is detected by second sensor 42, and based on these detected values, the control device 1 calculates the respective converted rotational speeds at the same positions in the power transmission system. Vibration damping control unit 16 determines whether or not a specific condition (particularly, the limiting condition, which is the second requirement) is satisfied, based on the information on the determination result received from acceleration / deceleration state determination unit 15 and the detected values ​​of first sensor 41 and second sensor 42 (including those calculated from them).

[0041] In this embodiment, the condition regarding the rotational speed difference, which is one of the limiting conditions, is determined by comparing the rotational speed (wheel speed) of wheel W with the converted rotational speed of rotating electric machine 31 at the position of wheel W in the power transmission system. As defined in the explanation regarding the calculation of vibration damping torque by vibration damping torque calculation unit 13, in this embodiment, a "differential rotation" is managed, which is calculated by subtracting the wheel speed from the converted rotational speed of rotating electric machine 31. Using this concept of "differential rotation," the rotational speed (wheel speed) of wheel W being higher than the converted rotational speed of rotating electric machine 31 is equivalent to the differential rotation being negative. Similarly, the rotational speed (wheel speed) of wheel W being lower than the converted rotational speed of rotating electric machine 31 is equivalent to the differential rotation being positive.

[0042] That is, in this embodiment, the restriction condition is that the vehicle V is in an accelerating state when entering the step D and the differential rotation is negative, or that the vehicle V is in a decelerating state when entering the step D and the differential rotation is positive.

[0043] When it is determined that wheel W has entered step D and the above-mentioned limiting condition is satisfied, vibration damping control unit 16 causes rotating electrical machine 31 to output limited vibration damping torque that is smaller than the normal vibration damping torque, instead of the normal vibration damping torque calculated by vibration damping torque calculation unit 13. Here, with regard to the limited vibration damping torque, "smaller than the normal vibration damping torque" means that the normal vibration damping torque is smaller in absolute value terms, without the positive or negative sign being reversed. When the normal vibration damping torque is positive (here, this is represented as "+T" using the positive number T), the corresponding limited vibration damping torque is a value equal to or greater than zero (0) and less than the normal vibration damping torque (+T). When the normal vibration damping torque is negative (here, this is represented as "-T" using the positive number T), the corresponding limited vibration damping torque is a value greater than the normal vibration damping torque (-T) and equal to or less than zero (0).

[0044] If vehicle V is accelerating when approaching step D and the differential rotation is negative, it is highly likely that wheel W is spinning while lifted off road surface R. In this situation, when wheel W returns to the ground, wheel W regains grip and the wheel speed drops sharply, moving in the direction of eliminating the negative differential rotation; however, by outputting a post-limitation damping torque that is smaller than the normal damping torque to rotary electric machine 31, it is possible to prevent the torsion of the power transmission system from becoming too large.

[0045] Furthermore, if vehicle V is decelerating when approaching step D and the differential rotation is positive, it is highly likely that wheel W is braking suddenly while lifted from road surface R. In such a situation, when wheel W returns to the ground, wheel W regains grip and the wheel speed increases rapidly, moving in the direction of eliminating the positive differential rotation, but by outputting a post-limiting vibration damping torque that is smaller than the normal vibration damping torque to rotary electric machine 31, it is similarly possible to prevent the torsion of the power transmission system from becoming too large.

[0046] If the post-limiting vibration-damping torque is smaller than the normal vibration-damping torque, it can at least suppress an increase in torsion in the power transmission system that may occur when approaching step D, but in this embodiment, the post-limiting vibration-damping torque is set to zero as shown in Fig. 5. By doing so, it is possible to maximize or nearly maximize the effect of suppressing an increase in torsion in the power transmission system.

[0047] Furthermore, in this embodiment, an additional restriction condition is imposed that the negative differential rotation when the vehicle V is in an accelerating state when entering the step D, or the positive differential rotation when the vehicle V is in a decelerating state when entering the step D, must be the first time. In other words, the restriction condition is that the first time that the differential rotation is in a negative state when the vehicle V is in an accelerating state when entering the step D, or the first time that the differential rotation is in a positive state when the vehicle V is in a decelerating state when entering the step D.

[0048] The control device 1 keeps track of the number of times the differential rotation has become positive (how many times the positive differential rotation has continued) and the number of times the differential rotation has become negative (how many times the negative differential rotation has continued) using counters (see FIG. 5). The limiting condition is that the negative differential rotation is continued for the first time (first time) when the vehicle V is accelerating when entering the step D, or the positive differential rotation is continued for the first time (first time) when the vehicle V is decelerating when entering the step D. In the example of FIG. 5, where the vehicle is decelerating, the period from time t1 to after t2, which is the first period of negative differential rotation, satisfies the limiting condition, but the period around time t4, which is the second period of negative differential rotation, does not satisfy the limiting condition.

[0049] Even if wheel W repeatedly lifts off and touches down after entering step D, the resulting fluctuation in differential rotation is usually greatest due to the first lift and the subsequent first touchdown. For this reason, during both acceleration and deceleration, by outputting post-limiting damping torque to rotating electric machine 31 only the first time, it is possible to effectively prevent torsion in the power transmission system from becoming too large at the time of the first touchdown, while thereafter using normal damping torque to appropriately reduce torsion in the power transmission system.

[0050] The processing procedure for vibration damping control will be described with reference to Fig. 6. Although not specifically stated here, it is assumed that vibration damping torque calculation unit 13 is always calculating vibration damping torque (i.e., normal vibration damping torque) (however, if no differential rotation occurs, the normal vibration damping torque is zero).

[0051] First, it is determined whether the wheel W (drive wheel) has entered a step D (step #01). If it is determined that the wheel W has entered a step D (#01: Yes), it is determined whether the vehicle V is accelerating, decelerating, or neither (#02, #03). If it is determined that the vehicle V is accelerating (#02: Yes), it is next determined whether the differential rotation is negative (#04). If it is determined that the vehicle V is decelerating (#02: No, #03: Yes), it is next determined whether the differential rotation is positive (#05).

[0052] If it is determined that the vehicle V is accelerating and the differential rotation is negative (#04: Yes), or if it is determined that the vehicle V is decelerating and the differential rotation is positive (#05: Yes), it is then determined whether this is the first time (#06). If it is the first time (#06: Yes), the damping torque to be output by the rotating electric machine 31 is set to a limited damping torque that is smaller than the normal damping torque (#07). In this embodiment, the damping torque is set to zero.

[0053] On the other hand, if it is the second or subsequent time (#06: No), the damping torque to be output from the rotating electric machine 31 is set to the normal damping torque (#08). Also, if it is determined that the differential rotation is zero when the vehicle V is in an accelerating or decelerating state (#04: No, #05: No), the damping torque to be output from the rotating electric machine 31 is set to the normal damping torque (#08). Then, the set damping torque (limited damping torque / normal damping torque) is output from the rotating electric machine 31 (#09).

[0054] The vibration reduction effect of the vibration damping control of this embodiment was confirmed through a demonstration test. The results are shown in FIG. 7. Vehicle V was decelerated while traveling on road surface R having step D, and the vehicle speed, wheel speed, and rotational speed of rotating electric machine 31 were measured. The drive shaft torque when vibration damping torque was output to rotating electric machine 31 was also measured. The point in time when step D was passed is indicated by a downward-pointing black triangle. In the comparative example, after passing step D, the normal vibration damping torque calculated by vibration damping torque calculation unit 13 was output to rotating electric machine 31 as is. In the example, after passing step D, limited vibration damping torque in which the initial negative torque portion of the normal vibration damping torque calculated by vibration damping torque calculation unit 13 (the portion surrounded by a dashed line in the comparative example of FIG. 7 ) was set to zero was output to rotating electric machine 31. In the example, the subsequent negative torque portion and positive torque portion of the normal vibration damping torque were output to rotating electric machine 31 as is.

[0055] It was confirmed that the initial negative peak value of the drive shaft torque was reduced by approximately 3% in the example compared to the comparative example. By reducing the peak value of the drive shaft torque, it is possible to reduce fluctuations in the drive shaft torque, and ultimately reduce vibrations of the vehicle V.

[0056] In this experiment, it was also confirmed how the first negative peak value of the drive shaft torque changes when the time for which limited damping torque (zero torque in this example) is output to the rotating electrical machine 31 as the damping torque is changed. The results are shown in Figure 8. This graph reveals that there is an optimum value for the output time of the limited damping torque that gives a local minimum to the first negative peak value of the drive shaft torque.

[0057] The optimum value for the output time of this limited damping torque depends on the size of the step D, but it generally coincides with the time required for the wheel W to first touch the ground after entering the step D. For this reason, it is preferable for the vibration damping control unit 16 to cause the rotating electric machine 31 to output a limited damping torque that is smaller than the normal damping torque after entering the step D until the wheel W first touches the ground.

[0058] Other Embodiments (1) In the above embodiment, an example has been described in which the step entry determination unit 14 determines whether the wheel W has entered the step D based on all of the rotational acceleration of the wheel W, the slip state of the wheel W in relation to the vehicle speed, and the vertical acceleration of the suspension spring. However, the present invention is not limited to such a configuration, and the step entry determination unit 14 may determine whether the wheel W has entered the step D based only on the slip state of the wheel W and the vertical acceleration of the suspension spring. Furthermore, if a camera that captures images in front of the vehicle is installed on the vehicle V, the step entry determination unit 14 may also determine whether the wheel W has entered the step D based on other information, such as using the image recognition results of the captured image.

[0059] (2) In the above embodiment, an example has been described in which the acceleration / deceleration state determination unit 15 determines the acceleration / deceleration state of the vehicle V based on the rate of change of the vehicle speed, whether or not the accelerator pedal is operated, and whether or not the brake is operated. However, the present invention is not limited to such a configuration, and the acceleration / deceleration state determination unit 15 may determine the acceleration / deceleration state of the vehicle V based only on, for example, the rate of change of the vehicle speed. Furthermore, the acceleration / deceleration state determination unit 15 may determine the acceleration / deceleration state of the vehicle V based on other information as well, such as using information on the pitch angle of the vehicle V obtained from a pitch angle sensor installed on the vehicle V.

[0060] (3) In the above embodiment, the satisfaction of the condition regarding the rotational speed difference among the limiting conditions is determined by comparing the rotational speed (wheel speed) of the wheel W with the converted rotational speed of the rotating electric machine 31 at the position of the wheel W in the power transmission system. However, the present invention is not limited to such a configuration, and the satisfaction of the condition may be determined by comparing the rotational speed of the rotating electric machine 31 with the converted rotational speed of the wheel W at the position of the rotating electric machine 31 in the power transmission system. Alternatively, the satisfaction of the condition may be determined by comparing the converted rotational speed of the wheel W with the converted rotational speed of the rotating electric machine 31 at an arbitrary position in the power transmission system (for example, the position of the counter shaft when the power transmission device 32 includes a counter drive mechanism). These methods are essentially the same, differing only in where the same phenomenon is specifically observed.

[0061] (4) In the above embodiment, the post-limiting damping torque is set to zero. However, the present invention is not limited to such a configuration, and the post-limiting damping torque may be set to a value at least smaller than the normal damping torque. The post-limiting damping torque is preferably set to ½ or less of the normal damping torque, more preferably ¼ or less, and even more preferably 1 / 10 or less.

[0062] (5) In the above embodiment, an example has been described in which the period during which post-limited damping torque is output instead of normal damping torque is the period from when wheel W enters step D until first contact with the ground. However, the present invention is not limited to such a configuration, and the period during which post-limited damping torque is output may be the period from when wheel W enters step D until slightly before first contact with the ground. Alternatively, the period during which post-limited damping torque is output may be the period from when wheel W first contacts step D until slightly after. In this case, the period during which post-limited damping torque is output may be, for example, the period from when wheel W first contacts step D until differential rotation disappears.

[0063] (6) In the above embodiment, an example has been described in which the vehicle required torque and the required braking torque are calculated by the integrated control unit 11 provided in the control device 1. However, the present invention is not limited to such a configuration, and for example, the vehicle required torque and the required braking torque may be calculated by a vehicle ECU provided separately from the control device 1, and the control device 1 may receive this information from the vehicle ECU and perform various controls.

[0064] (7) In the above embodiment, the control device 1 is described as an example of a configuration in which the object to be controlled by the control device 1 is a drive device for an electric vehicle (electrically driven vehicle) that has only a rotating electric machine 31 as a drive power source for the wheels W. However, the control device 1 is not limited to such a configuration, and can also be used to control a drive device for a hybrid vehicle that has an internal combustion engine in addition to the rotating electric machine 31 as a drive power source for the wheels W.

[0065] (8) The configurations disclosed in the above-described embodiments (including the above-described embodiments and other embodiments; the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction occurs. Regarding other configurations, the embodiments disclosed in this specification are illustrative in all respects and can be appropriately modified within the scope of the present disclosure.

[0066] Summary of the embodiment To summarize the above, the control device according to the present disclosure preferably has the following configurations.

[0067] A control device (1) for controlling a vehicle drive device (3) including a rotating electric machine (31) and a power transmission system that transmits a driving force of the rotating electric machine (31) to wheels (W), a step entry determination unit (14) that determines whether the wheel (W) has entered a step (D) on a road surface (R); an acceleration / deceleration state determination unit (15) that determines the acceleration / deceleration state of a vehicle (V); a damping torque calculation unit (13) that calculates a damping torque, which is a torque of the rotating electric machine (31) for reducing torsion occurring in the power transmission system; a vibration damping control unit (16) that controls the vibration damping torque output from the rotating electric machine (31), The vibration-damping torque calculated by the vibration-damping torque calculation unit (13) is set as a normal vibration-damping torque, When the step entry determination unit (14) determines that the wheel (W) has entered the step (D), and the acceleration / deceleration state of the vehicle (V) and the speed difference between the rotational speed of the wheel (W) and the rotational speed of the rotating electric machine (31) converted to the same position in the power transmission system satisfy predetermined limiting conditions, the vibration damping control unit (16) outputs a limited vibration damping torque that is smaller than the normal vibration damping torque to the rotating electric machine (31) as the vibration damping torque.

[0068] With this configuration, a situation in which there is a high possibility that the wheels (W) will lift when the vehicle (V) passes over a step (D) on the road surface (R) can be determined based on the acceleration / deceleration state of the vehicle (V) and the rotational speed difference (converted value) between the wheels (W) and the rotating electric machine (31). When such a situation is determined, a limited damping torque that is smaller than the normal damping torque calculated by the damping torque calculation unit (13) is output to the rotating electric machine (31) as the damping torque, thereby minimizing torsion occurring in the power transmission system. In other words, even when the vehicle (V) passes over a step (D) on the road surface (R), vibration damping control can be performed with minimal adverse effects.

[0069] In one embodiment, The vibration damping control section (16) preferably sets the post-limit vibration damping torque to zero.

[0070] This configuration can further reduce torsion occurring in the power transmission system.

[0071] In one embodiment, The restriction condition is preferably that the vehicle (V) is in an accelerating state when entering the step (D) and the rotational speed of the wheels (W) is higher than the converted rotational speed of the rotating electric machine (31), or that the vehicle (V) is in a decelerating state when entering the step (D) and the rotational speed of the wheels (W) is lower than the converted rotational speed of the rotating electric machine (31).

[0072] This configuration makes it possible to accurately determine a situation in which there is a high possibility that the wheels (W) will lift off when the vehicle (V) passes over a step (D) on the road surface (R). Therefore, it is possible to appropriately perform vibration damping control when the vehicle (V) passes over a step (D) on the road surface (R).

[0073] In one embodiment, When the limiting condition is not satisfied, the vibration damping control unit (16) preferably causes the rotating electric machine (31) to output the normal vibration damping torque as the vibration damping torque.

[0074] According to this configuration, in a situation where there is little possibility of the wheels (W) lifting up when the vehicle (V) passes over a step (D) on the road surface (R), the normal damping torque calculated by the damping torque calculation unit (13) is output as the damping torque to the rotating electric machine (31), thereby making it possible to effectively perform damping control in that situation.

[0075] It is sufficient for the control device according to the present disclosure to achieve at least one of the above-described effects. [Explanation of symbols]

[0076] 1: control device, 3: vehicle drive device, 11: integrated control unit, 12: rotating electric machine control unit, 13: vibration damping torque calculation unit, 14: step approach determination unit, 15: acceleration / deceleration state determination unit, 16: vibration damping control unit, 31: rotating electric machine, 32: power transmission device, 33: output shaft, 35: case, 41: first sensor, 42: second sensor, 43: third sensor, 44: fourth sensor, 45: fifth sensor, 46: sixth sensor, D: step, R: road surface, V: vehicle, W: wheel

Claims

1. A control device for controlling a vehicle drive device including a rotating electric machine and a power transmission system that transmits a driving force of the rotating electric machine to wheels, a step entry determination unit that determines whether the wheel has entered a step on a road surface; an acceleration / deceleration state determination unit that determines an acceleration / deceleration state of the vehicle; a damping torque calculation unit that calculates a damping torque of the rotating electric machine for reducing torsion occurring in the power transmission system; a vibration damping control unit that controls the vibration damping torque output from the rotating electric machine, The vibration-damping torque calculated by the vibration-damping torque calculation unit is set as a normal vibration-damping torque, The vibration damping control unit is a control device that, when the step entry determination unit determines that the wheel has entered the step, and when the acceleration / deceleration state of the vehicle and the speed difference between the rotational speed of the wheel and the rotational speed of the rotating electric machine when converted to the same position in the power transmission system satisfy predetermined limiting conditions, outputs a limited vibration damping torque that is smaller than the normal vibration damping torque to the rotating electric machine as the vibration damping torque.

2. The control device according to claim 1 , wherein the vibration damping control section sets the post-limit vibration damping torque to zero.

3. 3. The control device according to claim 1, wherein the restriction condition is that the vehicle is in an accelerating state when entering the step and the converted rotational speed of the wheels is higher than the converted rotational speed of the rotating electric machine, or that the vehicle is in a decelerating state when entering the step and the converted rotational speed of the wheels is lower than the converted rotational speed of the rotating electric machine.

4. The control device according to claim 1 or 2, wherein the vibration damping control unit causes the rotating electrical machine to output the normal vibration damping torque as the vibration damping torque when the limiting condition is not satisfied.

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