Drive control device and drive control method of rotary electric machine

Abstract

To detect a dead zone approach of a power transmission system by using information only on a rotational speed of a drive device.SOLUTION: A drive control device of a rotary electric machine for driving a rotary electric machine connected with a load via a torque transmission element having a dead zone has: a torque command acquiring part for acquiring a toque command value of the rotary electric machine; a rotational speed calculating part for calculating a rotational speed of the rotary electric machine; and a storage part for storing the rotational speed calculated by the rotational speed calculating part on and after a first time when a code of the torque command value acquired by the torque command acquiring part reverses. Further, the drive control device has a dead zone start time estimating part for calculating a second time when an amount of change from the rotational speed on the first time firstly becomes a predetermined amount or more to estimate a third time earlier than the second time as the start time of the dead zone.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a drive control device and a drive control method for a rotating electric machine. [Background technology]

[0002] In the past, in vehicles in which power is transmitted from an on-board drive unit to wheels and tires attached to the wheels via various gears, backlash (dead zone) inevitably exists in the gears, causing noise and vibration, and reducing ride comfort. This is because the occurrence of backlash temporarily cuts off the mechanical connection between the motor and tires, making the motor lighter and accelerating rapidly, and then when the gears are re-engaged (overcoming the dead zone), a shock occurs due to a collision between the gears. In response to this, a drive control technology is known that suppresses the effects of noise and vibration caused by such backlash (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-29832 Summary of the Invention [Problem to be solved by the invention]

[0004] The prior art described in Patent Document 1 aims to "more appropriately detect the dead zone of the power transmission system." In this prior art, "a rotation state detection unit 61 detects the torque of the drive shaft," and "a dead zone determination unit 62 determines the dead zone of the power transmission system caused by the backlash of the gears provided in the power transmission system based on the torque of the drive shaft."

[0005] As described above, Patent Document 1 is premised on detection of drive shaft torque or wheel speed, but there may be cases where a torque sensor is not provided, or where a torque sensor is provided but fails. Also, wheel speed sensor values ​​cannot always be obtained with high accuracy or frequency, and there is a demand for a means of detecting entry into the dead zone without relying on a torque sensor or wheel speed sensor.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a drive control device that detects entry into the dead zone of a power transmission system using only information on the rotational speed of the drive device. [Means for solving the problem]

[0007] In order to achieve the above object, in the present invention, a drive control device for a rotating electric machine that drives a rotating electric machine connected to a load via a torque transmission element having a dead zone region is characterized in having a torque command acquisition unit that acquires a torque command value of the rotating electric machine, a rotational speed calculation unit that calculates the rotational speed of the rotating electric machine, a memory unit that stores the rotational speed calculated by the rotational speed calculation unit after a first time at which the sign of the torque command value acquired by the torque command acquisition unit is reversed, and a dead zone start time estimation unit that calculates a second time at which an amount of change from the rotational speed at the first time becomes greater than or equal to a predetermined value for the first time, and estimates a third time that is earlier than the second time as the start time of the dead zone region. Effect of the Invention

[0008] According to the present invention, by using only the rotation speed information of the drive device, which is generally always obtainable, it is possible to detect the entrance of the dead zone without the need to obtain other information. By correcting the torque based on the entrance of the dead zone detected in this way, it is possible to suppress noise and vibration at the exit of the dead zone. Problems, configurations, and effects other than those described above will become clear from the description of the embodiments below. [Brief description of the drawings]

[0009] [Figure 1] 1 is an explanatory diagram showing the overall configuration of a vehicle equipped with a drive control device according to a first embodiment. [Diagram 2] 1 is an explanatory diagram showing a component configuration and a physical model of a drive section of a vehicle equipped with a drive control device according to a first embodiment. FIG. [Diagram 3] 2 is an explanatory diagram showing an example of a gear backlash (dead zone) element in a drive section of a vehicle equipped with the drive control device according to the first embodiment. FIG. [Figure 4] FIG. 2 is an explanatory diagram showing a physical phenomenon of a drive unit of a vehicle equipped with a drive control device according to the first embodiment. [Diagram 5] 1 is a block diagram showing a configuration of a drive control device according to a first embodiment. [Figure 6] FIG. 3 is an explanatory diagram showing an example of behavior of the drive control device according to the first embodiment. [Figure 7] 4 is an explanatory diagram showing an example of behavior of a rotation speed storage unit 5 of the drive control device according to the first embodiment. FIG. [Figure 8] 4 is an explanatory diagram showing an example of behavior of a dead-zone start time estimation unit 6 of the drive control device according to the first embodiment. FIG. [Figure 9] 4 is an explanatory diagram showing an example of the behavior of a torque correction unit 7 of the drive control device according to the first embodiment. FIG. [Figure 10] 4 is an explanatory diagram showing an example of the behavior of a torque correction unit 7 of the drive control device according to the first embodiment. FIG. [Figure 11] 4 is an explanatory diagram showing an example of the behavior of a torque correction unit 7 of the drive control device according to the first embodiment. FIG. [Figure 12] 4 is a flowchart showing a drive control process of the drive control device according to the first embodiment. [Figure 13] 10 is an explanatory diagram showing an example of the behavior of a torque correction unit 7 of the drive control device according to the second embodiment. FIG. [Figure 14] FIG. 10 is an explanatory diagram showing the effect of the drive control device according to the second embodiment. [Figure 15] 13 is an explanatory diagram showing an example of the behavior of a torque correction unit 7 of the drive control device according to the third embodiment. FIG. [Figure 16] FIG. 11 is an explanatory diagram showing the effect of the drive control device according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment does not limit the present invention, and not all of the components and combinations thereof described in the embodiment are necessarily essential to the solution of the invention. The number of each component in the following embodiment may be singular or plural, unless otherwise specified.

[0011] In the following embodiments, the same reference numerals are used to refer to the same items as in the previous embodiments, and the description of the following embodiments is omitted, and the description focuses on the differences. In the following embodiments, a combination of part or all of one embodiment with part or all of another embodiment is also included in the embodiments of the present application as long as there is no contradiction and there is consistency.

[0012] In the following description, identical or similar components will be denoted by the same reference numerals. When there are multiple identical or similar components, they may be denoted by different subscripts. When there is no need to distinguish between multiple components, the subscripts may be omitted.

[0013] [Embodiment 1] First, a drive control device 1 according to a first embodiment will be described with reference to Figures 1 to 12. The drive control device 1 controls the torque of a motor (rotating electric machine) for accelerating and decelerating a vehicle such as an automobile.

[0014] 1 is an explanatory diagram showing the overall configuration of a vehicle 21 equipped with a drive control device 1 according to embodiment 1. FL wheel means the front left wheel, FR wheel means the front right wheel, RL wheel means the rear left wheel, and RR wheel means the rear right wheel, and tires 20FL, 20FR, 20RL, and 20RR that come into contact with (adhere to) the road surface are mounted on the FL wheel, FR wheel, RL wheel, and RR wheel, respectively.

[0015] The vehicle 21 is equipped with a motor 22 as a drive device that generates a drive torque (drive force) for controlling the acceleration / deceleration in the traveling direction of the vehicle 21. The drive control device 1 receives power from a battery (not shown) mounted on the vehicle body, and controls the current of the motor 22 to generate a drive torque according to a torque command value (described later).

[0016] The drive control device 1 transmits the drive torque generated by the motor 22 to the left and right drive shafts 24L, 24R via the differential gear 23. Then, the drive control device 1 transmits the drive torque to the left and right front tires 20FL, 20FR directly connected to the drive shafts 24L, 24R, thereby accelerating and decelerating the vehicle 21.

[0017] Although the vehicle 21 will be described as an electric vehicle equipped with a motor 22, an engine may be used as a drive device (drive source) instead of a motor. Furthermore, the vehicle 21 will be described as a front-wheel drive vehicle, but it may also be a rear-wheel drive or four-wheel drive vehicle.

[0018] The vehicle 21 also includes a steering control mechanism 30 for controlling the traveling direction, a brake control mechanism 33, and a driving control device 25 (sometimes referred to as a higher-level controller) that calculates command values ​​for the drive control device 1. The vehicle 21 also includes a steering control device 28 that controls the steering control mechanism 30 based on command values ​​from the driving control device 25, and a braking control device 35 that controls the brake control mechanism 33 based on the command values ​​and adjusts the distribution of braking force to each wheel.

[0019] Although not shown in detail in Fig. 1, the drive control device 1 has a power semiconductor (e.g., IGBT) that controls the current of the motor 22 by switching, a CPU, a ROM, a RAM, and an input / output device for controlling the switching of the power semiconductor. The ROM stores a drive control flow to be described later with reference to Fig. 6 etc.

[0020] Although details will be described later, the drive control device 1 calculates the motor torque to be generated based on the torque command value 2 received from the travel control device 25 and the motor rotation angle 60 and motor rotation speed 61 acquired by a rotation angle sensor 51 attached to the motor 22 (see FIG. 4).Then, the drive control device 1 switches the power semiconductor to control the current flowing through the motor 22, aiming for the calculated motor torque.

[0021] Next, the operation of the brakes of the vehicle 21 will be described. When the driver is driving the vehicle 21, the force applied by the driver to the brake pedal 32 is boosted by a brake booster (not shown) if necessary. For this purpose, a master cylinder (not shown) generates hydraulic pressure according to the driver's pedal force. The generated hydraulic pressure is supplied via a brake control mechanism 33 to wheel cylinders 36FL, 36FR, 36RL, and 36RR provided on each wheel.

[0022] Each of the wheel cylinders 36FL to 36RR is composed of a cylinder, a piston, a pad, a disc rotor, etc. (not shown). The piston is driven by hydraulic fluid supplied from a master cylinder. The pad connected to the piston is pressed against the disc rotor by the driving force of the piston. The disc rotor rotates together with the wheel. Therefore, the brake torque acting on the disc rotor becomes a braking force acting between the wheel and the road surface.

[0023] In this way, braking force can be generated at each wheel in response to the driver's brake pedal operation. Note that the vehicle 21 equipped with the drive control device 1 of this embodiment does not necessarily need to be equipped with a brake booster or master cylinder. In other words, the brake pedal 32 and the brake control mechanism 33 may be directly connected, and the brake control mechanism 33 may be directly operated when the driver depresses the brake pedal 32.

[0024] 1, the braking control device 35 has, for example, a CPU, a ROM, a RAM, and an input / output device. For example, sensor signals are input to the braking control device 35 from a combine sensor 34 capable of detecting longitudinal acceleration, lateral acceleration, and yaw rate, wheel speed sensors 31FL, 31FR, 31RL, and 31RR installed on each wheel, and a handlebar angle detection device 41 via the steering control device 28. In addition, a braking force command value from the travel control device 25 and the like are input to the braking control device 35.

[0025] The braking control device 35 is connected to a brake control mechanism 33 having a pump and a control valve (not shown), and can generate any braking force on each wheel independently of the driver's brake pedal operation. The braking control device 35 can generate any braking force on the vehicle 21 based on a braking force command value received from the driving control device 25, and plays a role of automatically performing braking in automatic driving without driver operation. However, in this embodiment, the present invention is not limited to the braking control device 35, and other actuators such as a brake-by-wire may be used.

[0026] Next, a description will be given of the steering operation of the vehicle 21. The steering torque detection device 27 and the steering wheel angle detection device 41 respectively detect the steering torque and the steering wheel angle input by the driver via the steering wheel 26 while the driver is driving the vehicle 21. The steering control device 28 controls the steering motor 29 to generate an assist torque based on the detected steering torque and steering wheel angle.

[0027] 1, the steering control device 28 also has, for example, a CPU, a ROM, a RAM, and an input / output device, similar to the braking control device 35. The steering control mechanism 30 operates by the resultant force of the steering torque of the driver and the assist torque of the steering motor 29, and the front wheels (FL wheels, FR wheels) are turned. Meanwhile, a reaction force from the road surface is transmitted to the steering control mechanism 30 according to the turning angle of the front wheels, and is then transmitted to the driver as a road reaction force.

[0028] It should be noted that the vehicle 21 equipped with the drive control device 1 of this embodiment does not necessarily need to be equipped with the steering torque detection device 27. The vehicle 21 may have a mechanism (so-called heavy steering) in which the steering control device 28 does not operate when the driver operates the steering wheel 26 and no assist torque is generated.

[0029] The steering control device 28 can generate torque by the steering motor 29 and control the steering control mechanism 30, independent of the steering operation of the driver. Therefore, the driving control device 25 transmits a steering force command value to the steering control device 28, and the steering control device 28 that receives the steering force command value can control the front wheels to an arbitrary turning angle, and plays a role of automatically performing steering in automatic driving without driver operation. However, in this embodiment, it is not limited to the steering control device 28, and other actuators such as steer-by-wire may be used.

[0030] Next, a description will be given of the operation of the accelerator of the vehicle 21. The amount of depression of the accelerator pedal 37 by the driver is detected by a stroke sensor 38, converted into a torque command value 2 by the driving control device 25, and input to the drive control device 1.

[0031] 1, the driving control device 25 and the drive control device 1 also have, for example, a CPU, a ROM, a RAM, and input / output devices, similar to the braking control device 35. The driving control device 25 controls the motor torque of the motor 22 in response to, for example, the depression amount of the accelerator pedal 37. In this way, the vehicle 21 can be accelerated in response to the driver's operation of the accelerator pedal.

[0032] Furthermore, the cruise control device 25 can command the motor torque of the motor 22 independently of the accelerator operation by the driver. Therefore, by transmitting a torque command value to the drive control device 1, the cruise control device 25 can control the motor torque of the motor 22 to generate any desired acceleration in the vehicle 21, and plays a role of automatically accelerating in automatic driving without driver operation.

[0033] Furthermore, on slippery road surfaces, the cruise control device 25 has the role of performing traction control by changing the torque command value 2 so as to prevent tires from spinning (slipping) regardless of the driver's accelerator or brake commands.

[0034] The vehicle 21 equipped with the drive control device 1 of this embodiment does not necessarily need to be an electric vehicle whose main drive device is an electric motor, and the main drive device may be an engine. In this case, the cruise control device 25 calculates the throttle opening according to the depression amount of the accelerator pedal 37. The drive control device 1 also controls the engine operating state to realize the throttle opening.

[0035] As described above, in this embodiment, the driving control device 25 calculates command values ​​(braking force command value, steering force command value, torque command value (acceleration command value)) based on signals obtained from various sensors and the like arranged in the vehicle 21. Then, the driving control device 25 transmits the calculated command values ​​(braking force command value, steering force command value, torque command value (acceleration command value)) to each control device (the brake control device 35, the steering control device 28, the drive control device 1). In this way, the driving control device 25 can control the braking force, front wheel turning angle, acceleration, and the like of the vehicle 21, and arbitrarily control the driving state of the vehicle 21.

[0036] In the above explanation, the vehicle 21 is described as being equipped with the steering wheel 26, the accelerator pedal 37, and the brake pedal 32, but the vehicle may not be equipped with these input devices. In this case, the vehicle may be a fully automated vehicle that does not require driver operation, or a remotely operated vehicle that receives driving instructions remotely and drives, and the driving control device 25 serves as the brain of the vehicle.

[0037] It is also possible to adopt a configuration in which the driving control device 25 is not provided and the drive control device 1 calculates (generates) the command values.

[0038] In the following, for the sake of simplicity, the drive shaft connected to the drive wheels which are connected to the motor 22 and driven to rotate will be referred to as the drive shaft 24, the tires mounted on the drive wheels as the tires 20, and the wheel speed sensors installed on the drive wheels as the wheel speed sensors 31.

[0039] With reference to FIG. 2, the drive section of the vehicle 21, which is composed of the motor 22, the differential gear 23, the drive shaft 24, etc., will be described.

[0040] 2(a) is an explanatory diagram showing a component configuration of a drive section of a vehicle 21 equipped with a drive control device 1 according to embodiment 1. Drive torque generated in a motor 22 is transmitted to a differential gear 23 via a reduction gear 52. This drive torque is distributed to left and right wheels by the differential gear 23, and then transmitted to tires 20 via a drive shaft 24.

[0041] FIG. 2(b) is an explanatory diagram showing a physical model of the drive unit of the vehicle 21 equipped with the drive control device 1 according to the first embodiment. As shown in FIG. 2(b), the drive unit can be represented by a physical model of a two-inertia system in which there are two inertias, the motor 22 and the tire 20, and a spring, the drive shaft 24, connects them. Although not shown in this figure, the tire 20 comes into contact with the road surface, and thus a nonlinear frictional force is generated between the tire 20 and the road surface. Furthermore, the motor 22 is installed on the vehicle body via a motor mount 53. Since the motor mount 53 generally has an elastic material for shock absorption, a spring element is also assumed between the motor 22 and the vehicle body as shown in FIG. 2(b). Here, the motor 22 is sometimes referred to as the motor side, and the tire 20 side (including the inertia of the vehicle 21) is sometimes referred to as the load side.

[0042] FIG. 3 is an explanatory diagram showing an example of a backlash (dead zone) element of a gear in a drive section of a vehicle equipped with the drive control device 1 according to the first embodiment. Gears, which are torque transmission elements such as the differential gear 23 and the reducer 52, generally have a dead zone (backlash) as shown in FIG. 3. FIG. 3 is a schematic diagram drawn assuming a state in which two spur gears are meshed, and the backlash indicates a gap intentionally provided in the direction of movement as circled in the figure. Backlash is an essential element for smoothly rotating gears without strain, but when the gear meshing direction is reversed, the mechanical connection between the gears is broken, and collision occurs when the gears are refastened, which may cause abnormal noise and vibration.

[0043] Fig. 4 is an explanatory diagram showing a physical phenomenon of the drive unit of the vehicle 21 equipped with the drive control device 1 according to the embodiment 1. In the two-inertia system configuration shown in Fig. 2, the dead zone of the gear as shown in Fig. 3 is mainly a dead zone element between the motor 22 and the differential gear 23. In this configuration, when the torque of the motor 22 changes in the reverse direction (for example, when it changes from a positive value to a negative value, or from a negative value to a positive value: referred to here as zero crossing), vibration of the motor rotation speed 61 as shown in Fig. 4 occurs.

[0044] FIG. 4 shows the results of measurements taken on an electrically driven vehicle. In FIG. 4(a) and FIG. 4(b), the horizontal axis indicates time, and the vertical axis indicates motor rotation speed 61. In FIG. 4(c) and FIG. 4(d), the horizontal axis indicates time, and the vertical axis indicates motor torque (final torque value 8). FIG. 4(a) and FIG. 4(b) respectively show the motor rotation speed 61 and final torque value 8 over the entire two seconds. FIG. 4(c) and FIG. 4(d) respectively show an enlarged view of the time period from 0.5 to 1 second in FIG. 4(a) and FIG. 4(b), which is centered on the time of passing through the dead zone, during the two seconds.

[0045] In the example shown in FIG. 4, the driver releases the accelerator in creep mode at 0 seconds, and the vehicle slowly decelerates due to the negative torque of the final torque value 8. After that, by gradually depressing the accelerator from 0.5 seconds, the final torque value 8 crosses zero at about 0.6 seconds and changes from a negative value to a positive value. Immediately after that, the gears are no longer meshed and enter the dead zone (entrance of the dead zone), and the motor has only light inertia, so the motor rotation speed 61 rapidly accelerates at 0.6 to 0.7 seconds. After that, at 0.7 seconds, the exit of the dead zone, that is, the meshing position of the opposite side of the gears, is reached.

[0046] Between the entrance to the dead zone and the exit of the dead zone, the motor rotation speed increases rapidly, but the tire rotation speed (not shown) does not change much, and a collision occurs due to the relative speed difference between the two, causing the motor rotation speed 61 to vibrate from 0.7 seconds. This vibration of the motor rotation speed 61 is a resonance phenomenon caused by the drive shaft 24 acting as a spring. Alternatively, the vibration of the motor rotation speed 61 may be a resonance phenomenon caused by the spring element of the motor mount 53. In this way, vibration occurs due to the mechanical disconnection of the gear when passing through the dead zone, and the object of this embodiment is to reduce this vibration.

[0047] Fig. 5 is a block diagram showing the configuration of the drive control device 1 according to embodiment 1. As shown in Fig. 5, the drive control device 1 includes at least a torque command acquisition unit 3, a rotation speed calculation unit 4, a rotation speed storage unit 5, a dead zone start time estimation unit 6, and a torque correction unit 7.

[0048] The torque command acquisition unit 3 receives a torque command value 2 (a command value for causing the motor 22 to generate a motor torque in order to generate a predetermined acceleration in the vehicle 21) from the driving control device 25, which is a higher-level controller. For example, when the driver is depressing the accelerator pedal 37, the torque command value 2 is received as a positive value for accelerating the vehicle 21. On the other hand, when the driver is not depressing the accelerator pedal 37 or is depressing the brake pedal 32, the torque command value 2 is received as a negative value corresponding to regenerative braking or engine braking. The method of receiving the torque command value 2 from the driving control device 25 generally uses digital communication such as CAN (Controller Area Network).

[0049] As described above, the driving control device 25 may not be provided, and the drive control device 1 may calculate (generate) the command values.

[0050] The rotation speed calculation unit 4 time-differentiates (calculates the amount of change per unit time) the motor rotation angle 60 acquired by the rotation angle sensor 51 attached to the motor 22, and calculates the motor rotation speed 61. The rotation angle sensor 51 is generally a sensor capable of acquiring the absolute angle of the motor 22, such as an encoder or a resolver.

[0051] The rotational speed memory unit 5 stores the motor rotational speed 61 at each hourly sample of the drive control device 1 from zero cross time 1 (simply referred to as time 1 (first time)) when a zero cross occurs in the torque command value 2 acquired by the torque command acquisition unit 3.

[0052] The rotation speed storage unit 5 holds the value of the motor rotation speed 61 at time 1 as a reference rotation speed 62 (hereinafter, sometimes referred to as a "first calculation method of the reference rotation speed 62").

[0053] Alternatively, the rotation speed storage unit 5 has an internal acceleration / deceleration model of the vehicle that excludes gear backlash components, and predicts (calculates) and stores the speed of the vehicle 21 when there is no gear dead zone based on the torque command value 2 as a reference rotation speed 62 for each hourly sample. This calculation method of the reference rotation speed 62 may be hereinafter referred to as a "second calculation method of the reference rotation speed 62."

[0054] Alternatively, the standard rotation speed 62 may be calculated by extrapolating the speed change tendency of the motor rotation speed 61 at time 1 (hereinafter, this may be referred to as a "third calculation method of the standard rotation speed 62"). In this case, the standard rotation speed 62 is equivalent to predicting the rotation speed on the tire side.

[0055] Fig. 6 is an explanatory diagram showing an example of the behavior of the drive control device 1 according to the first embodiment. Fig. 6 is used to illustrate an example of the transition over time of the behavior of the rotation speed storage unit 5. Fig. 6(a) shows an example of the transition over time of the motor torque, Fig. 6(b) shows the motor rotation speed, and Fig. 6(c) shows an example of the transition over time of a backlash position 65, which will be described later. Fig. 6 shows an example of a series of behaviors of the drive control device 1 including a dead zone start time estimation unit 6 and a torque correction unit 7, which will be described later, and points not described here will be described later.

[0056] First, the time transition of the motor torque in Fig. 6(a) is similar to the behavior of the actual vehicle shown in Fig. 4, in which the driver gradually depresses the accelerator while the vehicle is creeping, causing the torque command value 2 (dashed line) to gradually increase from a negative value, and change from negative to a positive value at time 1. After time 1, the rotation speed storage unit 5 stores the time transition of the motor rotation speed 61 (solid line) shown in Fig. 6(b), and simultaneously calculates the reference rotation speed 62 (two-dot chain line).

[0057] In Fig. 6(b), the torque command value 2 enters the gear dead zone at a certain point after time 1 when the torque command value 2 crosses zero. As shown after time 1 in Fig. 6(b), the motor rotation speed 61 increases rapidly, and the speed deviation 63 of the motor rotation speed 61 from the reference rotation speed 62 calculated assuming no dead zone increases. In Fig. 6, the calculation of the reference rotation speed 62 is illustrated as the simplest example in which the motor rotation speed 61 at time 1 is continuously calculated as a constant value.

[0058] Fig. 7 is an explanatory diagram showing an example of the behavior of the rotation speed storage unit 5 of the drive control device 1 according to the first embodiment. Another example of a method in which the rotation speed storage unit 5 calculates the reference rotation speed 62 will be shown using Fig. 7. Fig. 7(a) and Fig. 7(b) each show two methods of calculating the reference rotation speed 62 different from Fig. 6. Fig. 7(a) shows a method of calculating the reference rotation speed 62 based on the motor rotation speed. Fig. 7(b) shows a method of calculating the reference rotation speed 62 based on the motor torque.

[0059] 7(a) shows an example of calculating the reference rotation speed 62a by the second calculation method of the reference rotation speed 62 described above. Here, the motor torque crosses zero from a negative value to a positive value at time 1, in accordance with the torque command value 2, and continues to increase linearly thereafter. However, this motor torque is assumed to be of a magnitude sufficient to cause slight acceleration or deceleration, such as creep, as described in FIG.

[0060] At this time, the standard rotation speed 62 is calculated as having an increasing tendency after the motor torque changes to a positive value after time 1. However, since the acceleration / deceleration model has a large inertia, that is, the vehicle body mass, the increase over time is small compared to the motor rotation speed 61, which is caused only by the motor inertia due to entering the dead zone. Therefore, the difference between the motor rotation speed 61 and the standard rotation speed 62a gradually increases. The second calculation method of the standard rotation speed 62 has the advantage that there is less risk of erroneously determining that the gear has entered the dead zone if the gear does not enter the dead zone after time 1 (for example, if the gear has already been engaged on the acceleration side at time 1), etc.

[0061] A first calculation example and a second calculation example of the reference rotation speed 62 in the second calculation method will be described. Here, the equation of rotational motion of the controlled object is expressed in the form of a state equation of equation (1) and an output equation of equation (2).

[0062]

number

[0063]

number

[0064] Here, x is a state vector, and the superscript dot indicates the time derivative. A, B, and C are all matrices determined by a physical model of the controlled object, u is the input to the controlled object, and y is a physical quantity to be output as the reference rotation speed (the motor rotation speed in this embodiment).

[0065] First, the first calculation example will be described. The first calculation example is a method of expressing an ideal equation of rotational motion that does not include torsional vibration of the drive unit, according to the state equation of equation (3) and the output equation of equation (4).

[0066]

number

[0067]

number

[0068] Here, Jm represents the inertia of the motor, and JL represents the inertia of the load side. In this modeling, JL is the sum of the tire and the vehicle body. Also, ωm represents the standard rotation speed 62, N represents the reduction ratio between the motor rotation shaft and the axle rotation shaft (the reduction gear of the motor itself multiplied by the reduction ratio of the differential gear), Td represents the estimated value of the disturbance torque, and Tm represents the torque command value 2. In this first calculation example, as shown in FIG. 7(a), the standard rotation speed 62 has a waveform that increases smoothly without vibration components. However, this acceleration / deceleration model does not model the resonance caused by the spring element of the drive shaft 24 or the motor mount 53 described above. Therefore, depending on the operating conditions, the second calculation method may not be able to distinguish between the motor rotation speed fluctuation due to the gear entering the dead zone and the motor rotation speed fluctuation due to resonance, and may erroneously take the motor rotation speed fluctuation due to resonance as the motor rotation speed fluctuation due to the gear entering the dead zone.

[0069] Next, the second calculation example is shown. The second calculation example is a method of expressing a higher-dimensional model by dividing the inertia of the motor and the tire into a rotational motion equation including the torsion between the two, as shown in the state equation (5) and the output equation (6).

[0070]

number

[0071]

number

[0072] Here, Jm represents the motor inertia, JL represents the load inertia (the sum of the tire and the vehicle body when the tire is sticking, and the tire when the tire is spinning). Also, ωm represents the reference rotation speed 62, θs represents the estimated value of the torsion angle (the difference between the motor rotation angle and the tire rotation angle), ωw represents the estimated value of the tire rotation speed, and Ks represents the torsional rigidity of the drive shaft. Also, Ksd represents the torsional viscosity of the drive shaft, N represents the reduction ratio between the motor rotation shaft and the axle rotation shaft (the reduction gear of the motor itself multiplied by the reduction ratio of the differential gear), Td represents the estimated value of the disturbance torque, and Tm represents the torque command value 2.

[0073] In the first calculation example, the reference rotation speed 62 is calculated as a waveform including vibrations caused by the spring element of the drive shaft 24 or the motor mount 53, as compared to Fig. 7(a). When the first calculation example is applied, it becomes easier to distinguish between motor rotation speed fluctuations caused by the gear entering the dead zone and motor rotation speed fluctuations caused by resonance, but since the acceleration / deceleration model becomes high-order, the calculation load on the drive control device, etc., may become an issue.

[0074] 7(b) shows the second calculation method of the above-mentioned standard rotation speed 62. In the second calculation method, on the premise that the change over time (rotational acceleration) of the motor rotation speed 61 at time 1 is maintained, standard rotation speed 62(b) is calculated linearly regardless of the change in torque command value 2. The advantage of the second calculation method is that when the gear enters the dead zone after time 1, the standard rotation speed becomes closer to the speed of the tire (vehicle), making it possible to more reliably determine entry into the dead zone.

[0075] After time 1, the dead zone start time estimation unit 6 calculates a speed deviation 63, which is the difference between the motor rotation speed 61 and the reference rotation speed 62, as a sample every hour. When the speed deviation 63 exceeds a preset speed deviation value 64, the time is defined as a change detection time 2 (simply called time 2 (second time)). Since a sufficient amount of speed deviation 63 has already occurred at time 2, it is considered that a long time has already passed since the intrusion of backlash. Therefore, the dead zone start time estimation unit 6 refers to the stored time transition of the motor rotation speed 61 going back from time 2, and estimates the dead zone start time 3 (simply called time 3 (third time)), which is the backlash intrusion time, from the characteristics of the waveform.

[0076] First, an example of the behavior of the dead zone start time estimation unit 6 over time is illustrated using Fig. 6. As shown in Fig. 6(b), the dead zone start time estimation unit 6 sets the time when the speed deviation 63 reaches a preset value 64 as time 2, and estimates the dead zone start time 3. Time 3 is set as a point in time at least in the past than time 2, and may be time 1 or before or after time 1 depending on the conditions. Fig. 6 shows an example in which a point in time after time 1 is estimated as time 3.

[0077] Fig. 8 is an explanatory diagram showing an example of the behavior of the dead-zone start time estimator 6 of the drive control device 1 according to embodiment 1. Fig. 8 shows an example in which time 3 is before or after time 1 depending on conditions.

[0078] First, Fig. 8(a) shows an example in which time 3 is later than time 1. In this case, the vehicle 21 is given an accelerating force due to a reason such as a downward slope. In this case, at time 1 when the torque crosses zero, the motor rotation speed is zero torque, so no accelerating force is generated due to the motor, but since an accelerating force is generated on the vehicle side, the motor side also tends to accelerate as it is pulled by the load side.

[0079] Therefore, at time 1, the gears are engaged when the motor rotates on the regenerative side, and in order for the gears to engage on the driving side, the motor needs to generate an accelerating force to lead the load side. Due to the above mechanism, time 3, which is the dead zone start time of the gears, is after time 1. For the above reasons, if the motor rotation speed 61 is tending to accelerate at time 1, it is highly likely that it is more accurate to estimate time 3 as being in the future than time 1, so dead zone start time estimation unit 6 sets time 3 to be in the future than time 1.

[0080] Next, Fig. 8(b) shows an example of the case where time 3 is before time 1. In this example, the vehicle 21 is subjected to a deceleration force due to running resistance, an uphill gradient, mechanical braking, etc. In this case, since a deceleration force is generated on the vehicle side, the motor side becomes the acceleration side relatively before the motor torque approaches zero from the deceleration (regeneration) side.

[0081] In other words, at time 1, the motor has already shifted to the relatively accelerating side, and time 3, which is the start time of the gear dead zone, occurs before time 1. And at time 1, when the motor torque becomes 0, the gear dead zone has already been entered, and the motor side is no longer transmitting force from the load side. At this time, the motor rotation speed has zero torque, so no acceleration or deceleration caused by the motor occurs, but the tendency to decelerate continues due to the influence of rotational resistance, etc.

[0082] For the above reasons, if the motor rotation speed 61 is tending to decelerate at time 1, it is likely to be more accurate to estimate time 3 as being earlier than time 1, so the dead zone start time estimation unit 6 sets time 3 to be earlier than time 1.

[0083] In this way, the dead zone start time estimation unit 6 estimates the time 3 based on the rotation speed of the motor 22 and the traveling state of the vehicle 21 including the acceleration of the vehicle 21 equipped with the motor 22 and the load. This makes it possible to more accurately detect the entry into the dead zone of the power transmission system even in cases where a torque sensor is not provided or where the torque sensor is broken.

[0084] At time 2, torque correction unit 7 calculates correction torque 67 based on torque command value 2, motor rotation speed 61, motor rotation speed 61 and reference rotation speed 62 stored in rotation speed storage unit 5, and time 3 estimated by dead zone start time estimation unit 6. Correction torque 67 is a torque that reduces the shock of gear re-engagement at the exit of the dead zone and the resulting resonance in the drive unit.

[0085] After time 2, the torque command value 2 is corrected by replacing it with the calculated torque value described above, and the final torque value 8 is calculated. Then, the torque correction is terminated when a torque correction termination condition is met. If the torque correction is not being performed, the torque command value 2 is followed.

[0086] Fig. 9 is an explanatory diagram showing an example of the behavior of the torque correction unit 7 of the drive control device 1 according to the first embodiment. A method for calculating the correction torque by the torque correction unit 7 at time 2 will be described using Fig. 9. Fig. 9(a) shows a speed deviation 63, Fig. 9(b) shows a backlash position 65, and Fig. 9(c) shows a correction torque 67. Fig. 9 is an image of the transition over time of past and future values ​​of each physical quantity grasped by the torque correction unit 7 at time 2.

[0087] 9(a), the torque correction unit 7 acquires the speed deviation 63 stored from time 3 to time 2 from the rotation speed storage unit 5. Then, the speed deviation 63 at the current time (time 2) is set to ω0.

[0088] Next, as shown in FIG. 9(b), from time 3 to time 2, the speed deviation 63 is integrated for each hourly sample to obtain the time transition of the backlash position 65. This is because the speed deviation 63 is equivalent to the difference between the motor rotation speed 61 and the tire rotation speed, that is, the relative speed of both teeth in the gear. Here, an example is shown in which a negative value obtained by dividing half the backlash width 66 (defined as Δθ) by 2 is given as the initial value of the backlash position 65 at time 3. This method can handle both zero crossing directions, negative → positive and positive → negative. The backlash position 65 at the current time (time 2) is defined as θ0.

[0089] Using ω0 and θ0 at time 2, a future point in time is set as the end time 4 of the dead zone (simply called time 4). Then, a constant acceleration problem is solved so that at time 4, the speed deviation 63 is 0 and the amount of change in the rotational position of the backlash position 65 from time 3 is equal to the backlash width 66. Therefore, the correction torque 67 is as shown in equation (7). Time 4 is also called the fourth time.

[0090]

number

[0091] Here, Tadj is the correction torque 67, Jm is the motor inertia, and Td is an estimated value of the disturbance torque. Td becomes the correction torque 67 that takes into account deceleration factors other than the motor torque by inputting values ​​for Coulomb friction and viscosity on the motor shaft. However, Td is generally very small, varies depending on the operating conditions, and is difficult to obtain accurately, so it does not necessarily have to be added. In this case, time 4 is as shown in equation (8).

[0092]

number

[0093] Here, T4 represents time 4 and T2 represents time 2.

[0094] In this correction torque design method, the speed deviation decreases linearly from time 2 to time 4, which is a future time period, as shown by dashed line 63' in FIG. 9(a), and becomes exactly 0 at time 4. This means that the backlash position is planned to be a positive value obtained by dividing exactly half of the backlash width 66 by 2 at time 4 (the position change from time 3 is exactly the backlash width 66=first predetermined value), as shown by backlash position 65' shown by dashed line in FIG. 9(b). As a result, the correction torque is planned as shown by correction torque 67 shown by solid line in FIG. 9(c) from time 2 to time 4, regardless of torque command value 2.

[0095] Based on the torque correction method described above, an example of the time transition of a series of behaviors of the torque correction unit 7 from time 1 to time 4 will be described with reference to FIG.

[0096] First, the torque correction unit 7 estimates a backlash position 65 from time 3 to time 2 based on the motor rotation speed 61 and standard rotation speed 62 stored from time 3 to time 2, as shown in backlash position 65 in Fig. 6(c). Furthermore, based on the speed deviation 63, which is the deviation between the motor rotation speed 61 and standard rotation speed 62 at time 2, and the backlash position 65, a certain point in time in the future is set as time 4, and the correction torque is calculated as described above.

[0097] Then, as shown in the time progression from time 2 to time 4 in FIG. 6(a), the torque command value 2 is replaced with the correction torque to obtain the final torque value 8 from time 2 to time 4 or until the dead zone exit determination is made.

[0098] The effect of the torque correction described above will now be described. In all of the waveforms shown in Figures 6(a) to 6(c), the dashed lines indicate a conventional technique without torque correction, and the solid lines indicate an example of behavior resulting from torque correction according to this embodiment. In the motor torque shown in Figure 6(a), the torque command value 2 is equivalent to the conventional technique without torque correction, whereas in this embodiment, it is replaced by a correction torque 67 from time 2 to time 4, and is generated as a final torque value 8.

[0099] At this time, looking at Figure 6(b), the motor rotation speed 61' in the conventional technology increases suddenly after time 1 due to entering the dead zone, and continues to increase after time 2, reaching a peak immediately afterwards and then decreasing suddenly in rotation speed. Then, after a swing back in the negative direction, it returns to the original speed around time 4. This means that near the speed peak, the exit of the dead zone is reached and gear meshing (collision) occurs, causing a sudden decrease in speed and generating vibrations due to the spring components of the drive shaft 24 and motor mount 53.

[0100] In contrast, in this embodiment, the increase in the motor rotation speed after time 2 starts to decelerate gradually (almost in a straight line), and the speed returns to the original speed exactly at time 4. There is no sudden change in speed caused by the gear meshing (collision) at the exit of the dead zone, and no subsequent vibrations, reducing the vibrations and abnormal noise that can cause discomfort to the driver and lead to a deterioration in ride comfort.

[0101] The above effects can also be seen from the change in the backlash position over time in Figure 6(c). The backlash position 65' in the conventional technology starts to increase from time 3, and without slowing down in pace, it reaches a displacement equivalent to the backlash width 66 after time 2 (near the peak of the motor rotation speed 61'), then changes discontinuously to a constant value. This discontinuous change indicates a collision.

[0102] In contrast, in this embodiment, the increase in the backlash position 65 slows down after time 2, and at time 4, it reaches a displacement that corresponds to the backlash width 66, and at the same time, the inclination becomes almost horizontal and continuously converges. This indicates that no collision has occurred.

[0103] In the behavior examples described so far, time 3, which is the time when the dead zone is entered, is merely an estimated value. Also, the backlash position from time 3 to time 2 is acquired by integrating speed deviation 63, and motor rotation speed 61, which is the basis for calculating speed deviation 63, is an actual value. On the other hand, reference rotation speed 62 is an estimated value based on an acceleration / deceleration model.

[0104] Furthermore, in this embodiment, the backlash width 66 is set in advance based on the design value of the gear, etc., but the backlash width 66 may deviate from the actual value due to aging, individual differences in the gear, etc. Therefore, there is always an estimation error in the backlash position 65, and it is not necessarily the case that the dead zone exit is reached exactly at time 4.

[0105] That is, any of the following patterns may occur: the motor reaches the exit of the dead zone before time 4 and the gears are re-engaged; the motor has not yet reached the exit of the dead zone at time 4; or the motor starts to reverse in the dead zone before time 4 as the motor rotation speed 61 slows down from the time 1. Therefore, in addition to the condition that the motor reaches time 4, the calculation of the torque correction end timing (fifth time) requires the addition of a condition that the motor rotation speed 61 returns to the speed at time 1 (or the reference rotation speed 62 at time 2) before time 4, that is, "end of rotation speed change." This makes it possible to deal with the estimation error of the backlash position 65. The torque correction end timing (fifth time) is the time when the motor rotation speed 61 becomes within a second predetermined value with respect to the motor rotation speed at time 1.

[0106] Fig. 10 and Fig. 11 are explanatory diagrams showing an example of the behavior of the torque correction unit 7 of the drive control device according to the first embodiment. Using Fig. 10 and Fig. 11, it will be shown that when the time at which the backlash exit is reached deviates from time 4, it is possible to deal with the end of torque correction by adding the condition of "end of rotation speed change". Fig. 10(a) and Fig. 11(a) show the motor torque. Fig. 10(b) and Fig. 11(b) show the motor rotation speed. Fig. 10(c) and Fig. 11(c) show the backlash position.

[0107] 10 and 11, for simplicity, an example is shown in which the vicinity of the time when the motor torque crosses zero is estimated as time 3. In addition, as a method for calculating the reference rotation speed 62, the first calculation method of the reference rotation speed 62 described above with reference to FIG.

[0108] First, Figure 10 shows a case where the estimate of time 3 is before time 3', which is the actual time of entering the dead zone, and the exit is not reached at time 4, or the motor rotation speed becomes negative before that. In Figure 10(a), at time 3 when the torque crosses zero, the gear has not yet entered the dead zone. This is a phenomenon that can occur when the motor rotation speed is accelerating at the time of zero crossing, as shown in Figure 8(a).

[0109] As shown in Fig. 10(b), the reference rotation speed 62 maintains the value of the motor rotation speed 61 at time 3 as a constant value. Because the motor torque becomes a positive value after time 3, the motor rotation speed gradually accelerates, and the speed deviation 63 increases with respect to the reference rotation speed 62. As a result, as shown in Fig. 10(c), the backlash position 65 starts to increase after time 3.

[0110] However, in the example of Fig. 10, since the actual entry into the dead zone occurs at time 3', the actual backlash position is smaller than the predicted backlash position 65, as shown by backlash position 65' in Fig. 10(c). Therefore, even though torque correction is started from time 2 (Fig. 10(a)), and the motor rotation speed returns to the original speed (reference rotation speed 62) at time 4 (Fig. 10(b)), the backlash position 65' at time 4 has not yet reached the movement distance equivalent to the backlash width 66 (Fig. 10(c)).

[0111] In other words, at time 4, the motor is still in the middle of the dead zone and has not yet reached the exit of the dead zone. Therefore, as shown in FIG. 10(a), after the correction of the final torque value 8 ends at time 4, the torque value becomes equal to the torque command value 2 (i.e., accelerates). Therefore, as shown by the motor rotation speed 61 in FIG. 10(b) and the backlash position 65' in FIG. 10(c) after time 4, the motor rotation speed 61 and the backlash position 65' increase toward the exit of the dead zone. For this reason, a slight collision occurs at time 4' (the fifth time) when the exit of the dead zone is actually reached.

[0112] However, this collision is smaller than the collision of the conventional technology in FIG. 6, so the effect of "reducing vibrations and abnormal noises that lead to discomfort for the driver and a decrease in ride comfort" is achieved.

[0113] Next, Fig. 11 shows a case where the estimate of time 3 is after time 3', which is the actual time of entering the dead zone, and reaches the exit of the dead zone before time 4. In Fig. 11(a), the gear has already entered the dead zone at time 3', which is before time 3, when the torque crosses zero. This is a phenomenon that can occur when the motor rotation speed is decelerating at the time of the zero crossing, as shown in Fig. 8(b).

[0114] As shown in Fig. 11(b), the reference rotation speed 62 holds the value of the motor rotation speed 61 at time 3 as a constant value. Since the motor torque becomes a positive value after time 3 and has already entered the dead band area, the motor rotation speed rapidly accelerates and the speed deviation 63 increases with respect to the reference rotation speed 62. As a result, as shown in Fig. 11(c), the backlash position 65 starts to increase after time 3. However, the actual backlash, as shown by backlash position 65', has already started to increase at time 3', prior to time 3, and is always ahead of the predicted backlash position 65'.

[0115] At this time, as shown in Fig. 11(a), the torque correction unit 7 starts torque correction from time 2, and as shown in Fig. 11(b), the motor rotation speed starts to decrease toward time 4. Then, as shown in Fig. 11(c), at time 4' before time 4, the backlash position 65' has already reached a movement distance equivalent to the backlash width 66.

[0116] At that point, the gears are re-engaged, and after time 4', the motor rotation speed 61 drops sharply as shown in Fig. 11(b). Furthermore, there is a high possibility that the motor rotation speed 61 will continue to fluctuate downward below the reference rotation speed 62 due to vibrations caused by the spring components of the drive shaft 24 and the motor mount 53.

[0117] Therefore, in this case, although time 4 has not yet been reached, the condition of "end of rotational speed change" is met, and as shown by the behavior of the final torque value 8 immediately after time 4' in Figure 11(a), the torque correction ends and is made equal to the torque command value 2. Under this condition, a slight collision will occur at time 4' when the dead zone exit is reached, just like in Figure 10.

[0118] However, this collision will be smaller than that of the conventional technology in Fig. 6, so the effect of "reducing vibrations and abnormal noises that lead to discomfort for the driver and a decrease in ride comfort" is achieved. Also, if torque correction were to continue until time 4 without judging the "end of rotation speed change" condition, the motor rotation speed would receive negative torque even after the gears are re-engaged, so it would again enter the dead zone of the gears and start running in reverse. By adding the "end of rotation speed change" condition, it is possible to prevent this undesirable behavior.

[0119] In addition, when the deviation as described in FIG. 10 and FIG. 11 occurs frequently, it is assumed that the backlash width 66 is different from the original backlash width of the gear as described above. In this case, it is desirable to change the value of the backlash width 66 according to the frequency and direction of the deviation. Specifically, when the phenomenon shown after time 4 in FIG. 10 occurs frequently, the value of the backlash width 66 is increased. Also, when the torque correction end due to the condition of "end of rotation speed change" as shown in FIG. 11 occurs frequently, the value of the backlash width 66 is decreased. That is, the drive control device 1 may learn the deviation between the fourth time and the fifth time described above, and correct the first predetermined value (backlash width 66) so that the deviation becomes 0 based on the learning result. In this way, the torque correction is performed taking into consideration the individual differences and aging deterioration of the gears that are torque transmission elements such as the differential gear 23 and the reducer 52, and the shock of the gear collision when going over the dead zone can be reduced.

[0120] As described above, the torque correction unit 7 corrects the torque when entering the dead zone, and calculates the final torque value 8. Thereafter, the drive control device 1 controls the current flowing through the motor 22 by switching the power semiconductors so that the motor 22 generates the final torque value 8. At this time, if the motor 22 is a permanent magnet synchronous motor, it is common to perform vector control based on the motor rotation angle 60.

[0121] A motor rotation angle 60 of the motor 22 is acquired by a rotation angle sensor 51 attached to the motor 22 and input to a rotation speed calculation unit 4 of the drive control device 1.

[0122] 12 is a flowchart showing the drive control process of the drive control device 1 according to embodiment 1. In the drive control process, it is determined for each calculation step whether to follow the torque command value 2 as the final torque value 8 or to perform torque correction.

[0123] First, in step S101, the drive control device 1 acquires the torque command value 2. In a normal state, the torque command value 2 is equal to the final torque value 8.

[0124] Next, in step S102, the drive control device 1 determines whether or not a zero cross of the torque command value 2 has been detected. If a zero cross has not been determined (time 1 has not been set) (step S102 No), the drive control device 1 ends the drive control. That is, the final torque value 8 is maintained equal to the torque command value 2. On the other hand, if a zero cross has been determined (time 1 has been set) (step S102 Yes), the drive control device 1 proceeds to step S103. In step S103, the drive control device 1 stores the motor rotation speed 61 for each hour, and calculates and stores the reference rotation speed 62.

[0125] Next, in step S104, the drive control device 1 determines whether the amount of change in the motor rotation speed has reached or exceeded a predetermined value (the calculated speed deviation 63 has exceeded a predetermined value 64). If it is determined that the amount of change in the motor rotation speed has reached or exceeded the predetermined value (Yes in step S104), the drive control device 1 moves the process to step S105. On the other hand, if it is determined that the amount of change in the motor rotation speed is less than the predetermined value (No in step S104), the drive control device 1 returns the process to step S103. When the process is returned to step S103, the state in which the final torque value 8 is equal to the torque command value 2 is maintained.

[0126] On the other hand, in step S105, the drive control device 1 estimates the dead band region start time 3 going back in time, sets time 4, and calculates the correction torque 67. Next, in step S106, the drive control device 1 overwrites the correction torque 67 with the final torque value 8.

[0127] Next, in step S107, the drive control device 1 judges whether the set time 4 has been reached or the condition of "end of rotation speed change" is satisfied. If the condition is satisfied (step S107 Yes), the drive control device 1 ends the drive control process. That is, the final torque value 8 returns to a state equal to the torque command value 2. At this time, the stored values ​​of times 1 to 4 set in the series of operations, the motor rotation speed 61, and the reference rotation speed 62 are reset.

[0128] On the other hand, if the condition is not satisfied (No in step S107), the engine control device 1 returns the process to step S106. When the process is returned to step S106, the state in which the final torque value 8 is overwritten on the correction torque 67 is maintained.

[0129] In the above-described embodiment 1, the entry of the gear into the dead zone is appropriately determined using only the information on the torque command value 2 and the motor rotation speed 61, and the time of entry and exit of the dead zone is estimated to perform torque correction. This makes it possible to provide a drive control device that reduces collisions caused by re-engagement of the gears at the exit of the dead zone, and reduces vibrations and abnormal noises that lead to discomfort for the driver and deterioration of ride comfort.

[0130] [Embodiment 2] Next, a drive control device 1B according to a second embodiment will be described with reference to Figures 13 and 14. Note that the same components as those in the first embodiment will be given the same reference numerals and the description thereof will be omitted.

[0131] In the first embodiment, a torque correction means has been described as an example in which the final torque value 8 immediately (in a step-like manner) returns to the torque command value 2 when time 4 or the "end of rotational speed change" condition is reached. However, at the time when the torque correction ends, the gears are usually already re-engaged, and if such a step-like torque change occurs thereafter, this change may induce resonance in the drive shaft 24 and the motor mount 53. In the second embodiment described below, a means is provided for gradually canceling the torque correction when the torque correction ends so as not to induce this resonance.

[0132] 5, the drive control device 1B according to this embodiment is configured to include at least a torque command acquisition unit 3, a rotation speed calculation unit 4, a rotation speed storage unit 5, a dead zone start time estimation unit 6, and a torque correction unit 7. Of these, the behavior of the torque command acquisition unit 3, the rotation speed calculation unit 4, the rotation speed storage unit 5, and the dead zone start time estimation unit 6 is the same as in the embodiment, and therefore description thereof will be omitted.

[0133] At time 2, torque correction unit 7 calculates correction torque 67 based on torque command value 2, motor rotation speed 61, motor rotation speed 61 and reference rotation speed 62 stored in rotation speed storage unit 5, and time 3 estimated by dead zone start time estimation unit 6. Correction torque 67 is a torque that reduces the shock of gear re-engagement at the exit of the dead zone and the resulting resonance in the drive unit.

[0134] After time 2, the torque command value 2 is corrected by replacing it with the calculated torque value described above to calculate a final torque value 8. Then, the torque correction is terminated when a torque correction termination condition is met.

[0135] When torque correction is not being performed, the torque command value 2 is followed, but when torque correction is ended, the torque command value 2 is not immediately followed, but is changed from the correction torque 67 to the torque command value 2 at a certain time change rate. Alternatively, the torque correction end time may be set as the initial time, the initial value of the torque as the correction torque 67, and the torque command value 2 as the command value, and the torque command value 2 may be gradually followed based on a filter (transfer function) such as a first-order lag.

[0136] Fig. 13 is an explanatory diagram showing an example of the behavior of the torque correction unit 7 of the drive control device 1B according to the second embodiment. Fig. 13 shows an example of "changing from the correction torque 67 to the torque command value 2 at a constant time change rate" as described above. The notation in Fig. 13 conforms to Fig. 6(a). The behavior up to time 2 is also similar to Fig. 6(a), and therefore description thereof will be omitted.

[0137] When the torque correction is completed at time 4, the torque correction unit 7 corrects the final torque value 8 toward the torque command value 2 at a constant gradient, as shown after time 4 in FIG. 13. In practice, this can be achieved by setting a rate limiter in the upward direction of the final torque value 8. However, if a rate limiter is present during normal operation, the performance of the drive control device 1 to follow the torque command value 2, which is its original role, is reduced. For this reason, it is desirable to operate this rate limiter only when the torque correction is completed, and to release the rate limiter when the final torque value 8 matches the torque command value 2. The gradient of the rate limiter may be set to a constant value in advance, or may be changed depending on the magnitude of the torque command value 2. For example, the larger the torque command value 2, the larger the upper limit value of the rate limiter is set. In this way, the torque correction unit 7 generates the correction torque so that the time change amount of the correction torque at the fifth time is smaller than the time change amount of the correction torque at the second time.

[0138] FIG. 14 is an explanatory diagram showing the effect of the drive control device 1B according to the second embodiment. FIG. 14(a) shows the results of a simulation using the vehicle motion model of the first embodiment, and FIG. 14(b) shows the results of a simulation using the vehicle motion model of the second embodiment. FIG. 14(a) and FIG. 14(c) show the motor rotation speed (a motor rotation speed 61' according to the conventional technology and the motor rotation speed 61 according to this embodiment, which are superimposed). FIG. 14(b) and FIG. 14(d) show the motor torque (torque command value 2 and torque final value 8, where the torque final value 8 in the conventional technology is equal to the torque command value 2). The time progression of the motor torque command value 2 and the motor rotation speed 61 here conform to FIG. 4, and the vehicle motion model is adjusted so that the generated vibration waveform matches the phenomenon in the actual vehicle as much as possible. Also, as in FIG. 4(d) and FIG. 4(d), the period from 0.5 to 1 second is enlarged.

[0139] In the example of the first embodiment shown in FIG. 14(a), the torque correction is started at 0.7 seconds, and the torque final value 8a changes in a step-like manner at the circled point around 0.83 seconds (time 4) and returns to the torque command value 2. At this time, the motor rotation speed 61a decelerates slightly linearly for a while after 0.7 seconds when the torque correction is started, but the slope in the deceleration direction increases at 0.8 seconds, suggesting that the backlash exit is reached before time 4. That is, the behavior is the same as that of FIG. 11. Here, focusing on the behavior around 0.83 seconds, it can be seen that a discontinuous change (a pointed mountain) occurs in the acceleration direction at the moment when the torque final value 8a changes in a step-like manner while the slope in the deceleration direction increases. After that, the motor rotation speed 61a generates a vibration with an amplitude of about 3 rad / s, suggesting that in addition to the vibration caused by the collision of the gear re-engagement at around 0.83 seconds, the step-like change in the torque final value 8a induced this vibration. However, this vibration is smaller than the vibration of about 8 rad / s in the conventional technology, and as mentioned in Figure 11, the effect of "reducing vibrations and abnormal noise that lead to discomfort for the driver and a decrease in ride comfort" is achieved.

[0140] On the other hand, in the example of embodiment 2 shown in Figure 14(b), similar to Figure 14(a), torque correction of the final torque value 8b begins at 0.7 seconds, and it can be seen that at the point circled in around 0.83 seconds (time 4), the torque correction gradually changes at a constant slope and returns to the torque command value 2.

[0141] In this example, the rate limiter is set to 100 Nm / s. At this time, the motor rotation speed 61(a) decelerates linearly after 0.7 seconds, as in Figure 14(a), and at 0.8 seconds, the inclination in the deceleration direction increases. If we focus on the behavior around 0.83 seconds, we can see that while the inclination in the deceleration direction increases, when the final torque value 8b starts to change, it naturally changes to the acceleration direction, and the sharp peak seen in Figure 14(a) does not occur.

[0142] After that, the motor rotation speed 61(a) vibrates with an amplitude of about 3 rad / s. This vibration is thought to be a residual vibration caused by the collision of the gear re-engagement at about 0.83 seconds. However, this vibration is smaller than the vibration of about 8 rad / s in the conventional technology, and as mentioned in Figure 11, the effect of "reducing vibrations and abnormal noises that lead to discomfort for the driver and a deterioration in ride comfort" is achieved.

[0143] In the example described above, there is not much difference between the vibration amplitude after 0.83 seconds in embodiment 1 and embodiment 2, but depending on the conditions, the vibration amplitude after 0.83 seconds is reduced in embodiment 2. Therefore, according to embodiment 2 described above, it is possible to provide a drive control device that further reduces vibrations and abnormal noises that lead to discomfort for the driver and deterioration of ride comfort by reducing the sudden fluctuation in torque under the torque correction end condition.

[0144] [Embodiment 3] Next, a drive control device 1C according to a third embodiment will be described with reference to Figures 15 and 16. Note that the same components as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted.

[0145] In the first and second embodiments, the torque correction starts from time 2, but the start time of the torque correction does not necessarily have to be time 2, and may be set to be after time 2 (but before reaching the exit of the dead zone).

[0146] The configuration of a drive control device 1C according to this embodiment is the same as that of embodiment 1 and shown in Fig. 5. That is, the drive control device 1C includes a torque command acquisition unit 3, a rotation speed calculation unit 4, a rotation speed storage unit 5, a dead zone start time estimation unit 6, and a torque correction unit 7. Of these, the behavior of the torque command acquisition unit 3, the rotation speed calculation unit 4, the rotation speed storage unit 5, and the dead zone start time estimation unit 6 is the same as in embodiment 1, so a description thereof will be omitted.

[0147] At time 2, torque correction unit 7 sets dead zone exit time 4 based on torque command value 2, motor rotation speed 61, motor rotation speed 61 and reference rotation speed 62 stored in rotation speed storage unit 5, and time 3 estimated by dead zone start time estimation unit 6. Then, torque correction unit 7 calculates correction torque 67 which is a torque that reduces the shock of gear re-engagement at time 4 and the drive unit resonance caused thereby.

[0148] At this time, if the correction torque 67 (or the difference of the correction torque 67 with respect to the torque command value 2) does not reach the threshold value 68, no torque correction is performed at time 2, and the correction torque 67 is calculated again at the next time sample. At this time, as more time passes from time 2, ω0 and θ0 become larger, and time 4 is set earlier. That is, the torque correction is corrected more toward the negative value side (in the case of a negative to positive zero crossing as described in this embodiment). This can be seen from the fact that, as shown in equations (7) and (9), the correction torque Tadj is calculated to be a more negative value as ω0 and θ0 become larger, and T4, which is time 4, approaches T2.

[0149] Fig. 15 is an explanatory diagram showing an example of the behavior of the torque correction unit 7 of the drive control device 1C according to the third embodiment. The notation in Fig. 15 conforms to Fig. 6(a). The behavior up to time 2 is also similar to Fig. 6(a), so its description is omitted. This embodiment differs from Fig. 6 in that it has a threshold value 68 (two-dot chain line) for torque correction.

[0150] At time 2, similarly to the first embodiment, a target torque is generated as shown by a final torque value 8' (dotted line) based on a torque command value 2, a stored motor rotation speed 61 and a reference rotation speed 62, and a time 3 estimated by a dead zone start time estimation unit 6. The target torque is a torque that reduces the shock of gear re-engagement at the exit of the dead zone and the resulting resonance of the drive unit.

[0151] At this time, the correction torque after time 2 does not fall below threshold value 68. Therefore, in the third embodiment, the final torque value 8' is not generated for the time sample in which the correction torque does not fall below threshold value 68, and the process moves to the next time sample. Thereafter, the correction torque and time 4 are continuously calculated for each hourly sample, and the final torque value 8 is generated at time 2' (sixth time) when the correction torque falls below threshold value 68 for the first time. That is, instead of at time 2 (second time), the torque correction unit 7 generates the correction torque after time 2', which is later than time 2, and corrects the torque command value using the correction torque.

[0152] FIG. 16 is an explanatory diagram showing the effect of the drive control device 1C according to the third embodiment. FIG. 16(a) shows the behavior of the first embodiment, and FIG. 16(b) shows the behavior of the third embodiment, both of which show the results of a simulation using a vehicle motion model under the same conditions as FIG. 14. The notation in FIG. 16 conforms to FIG. 14. FIG. 14(a) and FIG. 14(b) show the motor rotation speed (a motor rotation speed 61' according to the conventional technology and a motor rotation speed 61 according to this embodiment, plotted together). FIG. 14(c) and FIG. 14(d) show the motor torque (torque command value 2 and final torque value 8, where the final torque value 8 in the conventional technology is equal to the torque command value 2).

[0153] In the first embodiment shown in FIG. 16(a), torque correction for the final torque value 8a starts at 0.7 seconds, and returns to the torque command value 2 at about 0.83 seconds (time 4) at the point indicated by the dashed line. The final torque value 8(a) during this period is close to 0 Nm. After time 4, the motor rotation speed 61a vibrates with an amplitude of about 3 rad / s. As described with reference to FIG. 14, this vibration is smaller than the vibration of about 8 rad / s in the conventional technology, and the effect of "reducing vibrations and abnormal noises that lead to discomfort for the driver and deterioration of ride comfort" is achieved.

[0154] On the other hand, in the second embodiment of Fig. 16(b), torque correction is started at 0.74 seconds, which is about 0.04 seconds later than in the first embodiment, for the final torque value 8b. Then, as shown by the arrow in the figure, the torque command value returns to 2 at about 0.79 seconds (time 4), which is about 0.04 seconds earlier than in the first embodiment, as indicated by the dashed dotted line. During this period, the final torque value 8a is larger on the negative side than in the first embodiment, and is about -4 Nm. The effect of the third embodiment is that time 4 is brought forward by about 0.04 seconds.

[0155] After time 4, vibrations with an amplitude of about 1 rad / s occur in the motor rotation speed 61b, which are smaller than those in embodiment 1. Whether or not a vibration reduction effect is realized depends on the operating conditions, but in other words, this suggests that there is no disadvantage (trade-off) from advancing time 4. The vibrations with an amplitude of about 1 rad / s after time 4 are very small compared to the vibrations of about 8 rad / s in the conventional technology, and the effect of "reducing vibrations and abnormal noises that lead to discomfort for the driver and reduced ride comfort" is achieved.

[0156] In this embodiment, an example is shown in which the condition is set such that the torque correction exceeds the threshold value 68. However, this is not limited to this, and a method may also be used in which the final torque value 8 and time 4 are set at a time delayed by a predetermined time (number of samples) from time 2.

[0157] In the above-described third embodiment, by setting the torque correction after time 2, the torque at the time of the torque correction becomes more negative, and time 4, which is the exit of the dead zone, is advanced, thereby improving the speed at which the dead zone is passed. It is possible to provide a drive control device that realizes a linear acceleration / deceleration feeling with little delay in response to the driver's accelerator work, while reducing vibrations and abnormal noise that can lead to discomfort for the driver and a decrease in ride comfort.

[0158] In the above-described first to third embodiments, the case where the zero crossing changes from negative to positive has been described, but the case where the zero crossing changes from positive to negative is similar. In this case, each graph in the first to third embodiments, in which the horizontal axis represents time, is symmetrical with respect to the horizontal axis. In addition, since the speed deviation 63 is calculated as a negative value, the predetermined value 64 of the speed deviation is set as a negative value, and the torque correction amount calculated at or after time 2 or time 2' is changed to the positive direction with respect to the torque command value 2.

[0159] In the above-described first to third embodiments, an electric vehicle (also called an electric car) using an electric drive motor as a power source has been described as an example, but the present invention can be applied to any vehicle in which power is transmitted to tires via a thin shaft such as a drive shaft. For example, the present invention can be applied to engine vehicles, hybrid automobiles, construction machinery (mining dump trucks, etc.), small mobility such as a small one-seater car, etc. Also, instead of distributing power to the left and right wheels via a differential gear, it is also possible to mount electric motors independently on the left and right, and each of them transmits power to the left and right wheels via a shaft.

[0160] The present invention is not limited to the above-described embodiment, but includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those including all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0161] In addition, the above-mentioned configurations, functions, processing units, processing means, etc. may be realized in part or in whole by hardware, for example, by designing them as integrated circuits. In addition, the above-mentioned configurations and functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a memory, a storage device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0162] In addition, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other. [Explanation of symbols]

[0163] 1: Drive control device, 3: Torque command acquisition unit, 4: Rotation speed calculation unit, 5: Rotation speed storage unit, 6: Dead zone start time estimation unit, 7: Torque correction unit, 8: Torque final value, 20 (20FL, 20FR, 20RL, 20RR): Tire, 21: Vehicle, 22: Motor (drive device), 23: Differential gear, 24 (24L, 24R): Drive shaft, 25: Travel control device, 27: Steering torque detection device, 28: Steering control device, 29: Steering motor, 30: Steering control mechanism, 31 (31FL, 31FR, 31RL, 31RR): Wheel speed sensor sensor, 32: brake pedal, 33: brake control mechanism, 34: combine sensor, 35: braking control device, 36FL, 36FR, 36RL, 36RR: wheel cylinder, 37: accelerator pedal, 38: stroke sensor, 41: steering wheel angle detection device, 51: motor rotation angle sensor, 52: reducer, 53: motor mount, 60: motor rotation angle, 61: motor rotation speed, 62: reference rotation speed, 63: speed deviation, 64: specified value of speed deviation, 65: backlash position, 66: backlash width, 67: correction torque, 68: correction torque threshold.

Claims

1. A drive control device that drives a rotating electric machine connected to a load via a torque transmission element having a dead zone, a torque command acquisition unit that acquires a torque command value of the rotating electric machine; a rotation speed calculation unit that calculates a rotation speed of the rotating electric machine; a storage unit that stores the rotation speed calculated by the rotation speed calculation unit at or after a first time when a sign of the torque command value acquired by the torque command acquisition unit is reversed; a dead zone start time estimation unit that calculates a second time when an amount of change from the rotation speed at the first time becomes equal to or greater than a predetermined value for the first time, and estimates a third time that is earlier than the second time as a start time of the dead zone; A drive control device comprising:

2. The drive control device according to claim 1, The dead zone start time estimation unit is calculating a reference rotation speed based on the torque command value, the reference rotation speed being a value obtained by assuming that the dead zone does not exist and being a reference rotation speed after the first time point; The second time is calculated based on a speed deviation that is a difference between the reference rotation speed and the rotation speed, or based on a time change amount of the speed deviation. A drive control device comprising:

3. The drive control device according to claim 1, The dead zone start time estimation unit is The third time is estimated based on a running state of a vehicle including the acceleration of the vehicle including the rotating electric machine and the load. A drive control device comprising:

4. The drive control device according to claim 3, The dead zone start time estimation unit is A time change amount of the rotation speed at the first time is calculated, and when the time change amount is negative, the third time is set further back than when the time change amount is positive. A drive control device comprising:

5. The drive control device according to claim 1, The dead zone start time estimation unit is a fourth time point in the future than the second time point at which a change in the rotational position of the rotating electric machine from the third time point reaches a first predetermined value is estimated as an end time of the dead zone; a torque correction unit that generates a correction torque after the second time such that the rotation speed at the fourth time becomes equal to the rotation speed at the first time, and corrects the torque command value to be output to the rotating electric machine using the correction torque. A drive control device comprising:

6. The drive control device according to claim 5, The torque correction unit is At a fifth time when the rotation speed becomes within a second predetermined value with respect to the rotation speed at the first time, generation of the correction torque and correction of the torque command value are terminated. A drive control device comprising:

7. The drive control device according to claim 6, A deviation between the fourth time and the fifth time is learned, and the first predetermined value is corrected based on the learning result of the deviation. A drive control device comprising:

8. The drive control device according to claim 6, The torque correction unit is The correction torque is generated so that a time change amount of the correction torque at the fifth time is smaller than a time change amount of the correction torque at the second time. A drive control device comprising:

9. The drive control device according to claim 5, The torque correction unit is The correction torque is generated at a sixth time or later, which is later than the second time, instead of the second time, and the torque command value is corrected using the correction torque. A drive control device comprising:

10. A drive control method executed by a drive control device that drives a rotating electric machine connected to a load via a torque transmission element having a dead zone, comprising: a torque command acquisition step of acquiring a torque command value of the rotating electric machine; a rotation speed calculation step of calculating a rotation speed of the rotating electric machine; a storage step of storing, in a storage unit, the rotation speed calculated in the rotation speed calculation step at or after a first time when the sign of the torque command value acquired in the torque command acquisition step is reversed; a dead zone start time estimation step of calculating a second time when an amount of change from the rotation speed at the first time becomes equal to or greater than a predetermined value for the first time, and estimating a third time that is earlier than the second time as a start time of the dead zone; A drive control method comprising the steps of:

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