Electric vehicle
Patent Information
- Application Number
- PCT/JP2026/010629
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-26
- Filing Date
- 2026-03-18
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026010629_01102026_PF_FP_ABST
Abstract
Description
Electric vehicles
[0001] This matter concerns an electric vehicle equipped with a front-wheel drive source and a rear-wheel drive source.
[0002] In four-wheel drive electric vehicles, the front-wheel drive source for driving the front wheels and the rear-wheel drive source for driving the rear wheels may be provided separately. For example, electric vehicles are known in which the front wheels are driven by one motor and the rear wheels are driven by two motors. Electric vehicles are also known in which each of the four wheels is driven by an in-wheel motor (see Patent Documents 1 and 2).
[0003] Japanese Patent Publication No. 2021-172247 Japanese Patent Publication No. 2005-151691
[0004] When the drive source and the wheels are connected by a drive shaft, a response delay occurs due to torsional deformation of the drive shaft. This response delay can reduce the responsiveness of the torque difference (left-right torque difference) between the left and right wheels, which are fixed to the drive shaft, potentially reducing the stability of the vehicle's behavior.
[0005] One of the objectives of this invention is to provide an electric vehicle that can improve the stability of vehicle behavior, as devised in light of the above-mentioned problems. In addition to this objective, other objectives of this invention include achieving effects that cannot be obtained with conventional technology, which are derived from each configuration shown in the "Modes for Carrying Out the Invention" described later.
[0006] The disclosed electric vehicle can be realized in the following embodiments (examples of application) and solves at least some of the above-mentioned problems. Embodiment 2 is an additional embodiment that can be selected as appropriate and is optional. Embodiment 2 does not disclose any embodiments or configurations that are essential to this case.
[0007] Embodiment 1. The disclosed electric vehicle comprises a pair of first motors that individually drive the first left and right wheels for one of the front wheels and the rear wheels; a pair of second motors that supply driving force to the second left and right wheels for the other of the front wheels and the rear wheels; a pair of drive shafts connected to each of the second left and right wheels; a power distribution mechanism interposed between the pair of drive shafts and the pair of second motors; and a control device that controls the first motors and the second motors.
[0008] The control device includes a required torque calculation unit that calculates the required torque for each of the first left and right wheels and the second left and right wheels; a torque difference calculation unit that calculates the difference in required torque between the second left and right wheels; an estimation unit that calculates the estimated torque difference between the second left and right wheels, including the torque response delay caused by the drive shaft; a deficiency torque difference calculation unit that calculates the deficiency torque difference, which is the deviation between the required torque difference and the estimated torque difference; and a control unit that controls the drive torque of each of the first motors so that the deficiency torque difference is compensated for by the first left and right wheels.
[0009] Embodiment 2. With respect to embodiments including Embodiment 1 described above, it is preferable that the control unit adds half of the insufficient torque difference to the required torque of one of the first left and right wheels, subtracts half of the insufficient torque difference from the required torque of the other of the first left and right wheels, adds half of the insufficient torque difference to the required torque of one of the second left and right wheels, and subtracts half of the insufficient torque difference from the required torque of the other of the second left and right wheels.
[0010] According to the disclosed electric vehicle, the difference in insufficient torque between the second left and right wheels on the drive shaft can be compensated for by a pair of first motors, allowing for the precise generation of the vehicle's yaw moment. Therefore, the stability of the vehicle's behavior can be improved.
[0011] This is a block diagram showing the configuration of an electric vehicle. This is a block diagram showing the control flow performed by the control device. This is a graph illustrating the control operation, where (A) is the steering angle, (B) is the driver-requested yaw moment, and (C) is the generated yaw moment.
[0012] The disclosed electric vehicle (also referred to as the vehicle) is a four-wheel drive vehicle. This vehicle is equipped with at least a pair of front-wheel motors that drive the front wheels and a pair of rear-wheel motors that drive the rear wheels. Either the front-wheel motors or the rear-wheel motors are in-wheel motors. The pair of in-wheel motors are built into each of the left and right wheels. No drive shafts are interposed between the in-wheel motors and the left and right wheels. The in-wheel motors may be applied to the front wheels or to the rear wheels.
[0013] Either the front wheel motor or the rear wheel motor is a non-in-wheel motor (a motor that is not an in-wheel motor). This motor supplies driving force to the left and right wheels via a power distribution mechanism and a drive shaft. The pair of non-in-wheel motors are connected to the power distribution mechanism. A drive shaft is interposed between the power transmission mechanism and the left and right wheels. The non-in-wheel motor is applied to wheels to which in-wheel motors are not applied. The non-in-wheel motor may be applied to the front wheels or the rear wheels.
[0014] The power distribution mechanism is a mechanism having at least a differential gear. The power distribution mechanism is interposed between the left drive shaft connected to the left wheel and the right drive shaft connected to the right wheel. The power distribution mechanism includes, for example, a reduction mechanism, a gear shift mechanism, a planetary gear mechanism, etc. The power distribution mechanism in this embodiment is a differential mechanism with a yaw control function [AYC (Active Yaw Control) function].
[0015] Yaw control is a function that stabilizes the vehicle's attitude by adjusting the yaw moment through actively controlling the ratio of driving force (driving torque) distributed between the left and right wheels. The vehicle drive system, including non-in-wheel motors and a power distribution mechanism, is also called a DM-AYC (Dual Motor AYC) system. The DM-AYC system amplifies the torque difference between a pair of non-in-wheel motors and transmits it to each of the left and right wheels.
[0016] Specific examples of vehicles disclosed include electric vehicles (BEV, Battery Electric Vehicle), hybrid vehicles (HEV, Hybrid Electric Vehicle), plug-in hybrid vehicles (PHEV, Plug-in Hybrid Electric Vehicle), and fuel cell vehicles (FCEV, Fuel Cell Electric Vehicle).
[0017] A plug-in hybrid vehicle refers to a hybrid vehicle that can be charged or powered externally. External charging means charging the vehicle's battery using electricity from charging equipment installed outside the vehicle (charging stations, private charging equipment, household outlets, etc.). External power supply means supplying power from the vehicle's battery to electrical appliances other than those installed in the vehicle.
[0018] Plug-in hybrid vehicles are equipped with a charging port (inlet) for inserting a charging cable that supplies power from an external charging station, and an outlet for supplying power to electrical appliances. When a vehicle drive system is applied to a hybrid vehicle or a plug-in hybrid vehicle, a separate drive motor and internal combustion engine may be provided, or the internal combustion engine may be built into (or integrated with) the vehicle drive system itself.
[0019] The disclosed vehicle may be equipped with not only front and rear wheel motors, but also an engine (internal combustion engine) and a generator. The engine may start up and generate driving force according to the vehicle's driving conditions, for example. The engine's driving force may be sufficient to propel the vehicle on its own, or it may be added to the driving force of the front and rear wheel motors. Alternatively, the engine's driving force may be used to generate electricity to drive the front and rear wheel motors. The generator may, for example, generate electricity using the engine's driving force, or it may generate driving force that is added to the driving force of the front and rear wheel motors.
[0020] [1. Configuration] Figure 1 is a block diagram of an electric vehicle 1 (vehicle) as an embodiment. This vehicle 1 is equipped with a front wheel drive device 11 that drives front wheels 2, and a rear wheel drive device 12 that drives rear wheels 7. In the drawings of the embodiment, the alphabets L and R added to numerical reference numerals indicate the arrangement position of the element related to the reference numeral (that the element is located on the left side or the right side of the vehicle 1). For example, 2L represents the left front wheel of the front wheels 2 located on the left side of the vehicle 1, and 2R represents the right front wheel of the front wheels 2 located on the right side of the vehicle 1.
[0021] The front wheel drive device 11 includes a pair of front motors 3 (first motors), an engine 4 (internal combustion engine), a transaxle 5, a generator 6, and front drive shafts 51. The front motors 3 are in-wheel motors that individually drive the left front wheel 2L and the right front wheel 2R (first left and right wheels). The front motors 3 are operated by electric power from an on-vehicle battery (not shown). The front motor 3 includes a left front motor 3L built in the left front wheel 2L and a right front motor 3R built in the right front wheel 2R. The left front motor 3L drives the left front wheel 2L, and the right front motor 3R drives the right front wheel 2R.
[0022] The engine 4 is connected to the generator 6 and the front wheels 2 via the transaxle 5. The driving force of the engine 4 can be used for regenerative power generation by the generator 6, and can also be used for driving the front wheels 2 (for example, assisting the front motors 3). The driving force of the generator 6 can be used not only for regenerative power generation but also for driving the front wheels 2 (for example, assisting the front motors 3).
[0023] The transaxle 5 includes, for example, a differential mechanism, a speed reduction mechanism, a speed change mechanism, a planetary gear mechanism, and the like. The front drive shafts 51 are connected to each of the left front wheel 2L and the right front wheel 2R. A left front drive shaft 51L is interposed between the transaxle 5 and the left front wheel 2L, and a right front drive shaft 51R is interposed between the transaxle 5 and the right front wheel 2R.
[0024] The front motor 3 is directly connected to the front wheels 2. No left front drive shaft 51L is interposed between the left front wheel 2L and the left front motor 3L, and no right front drive shaft 51R is interposed between the right front wheel 2R and the right front motor 3R. When the vehicle 1 is an electric vehicle, the engine 4, the transaxle 5, the generator 6, and the front drive shaft 51 are omitted. When the vehicle 1 is a series hybrid electric vehicle, the transaxle 5 and the front drive shaft 51 are omitted.
[0025] The rear wheel drive device 12 includes a pair of rear motors 8 (second motors), a power distribution mechanism 9, and a rear drive shaft 52. The rear motor 8 is a non-in-wheel motor that supplies driving force to the left rear wheel 7L and the right rear wheel 7R (second left and right wheels). The rear motor 8 is operated by electric power from an on-vehicle battery (not shown). The rear motor 8 includes a left rear motor 8L arranged on the left side of the vehicle 1, and a right rear motor 8R arranged on the right side of the vehicle 1. Both the left rear motor 8L and the right rear motor 8R are connected to the power distribution mechanism 9.
[0026] The power distribution mechanism 9 distributes the driving force transmitted from the left rear motor 8L and the right rear motor 8R to the left rear wheel 7L and the right rear wheel 7R. The power distribution mechanism 9 includes at least a differential gear. The power distribution mechanism 9 of the present embodiment is a DM-AYC device. The power distribution mechanism 9 includes a planetary gear mechanism and a differential gear for realizing a yaw control function. The rear drive shaft 52 is connected to each of the left rear wheel 7L and the right rear wheel 7R. A left rear drive shaft 52L is interposed between the power distribution mechanism 9 and the left rear wheel 7L, and a right rear drive shaft 52R is interposed between the power distribution mechanism 9 and the right rear wheel 7R.
[0027] The operating states of the front motor 3 and the rear motor 8 are controlled by the control device 20. The control device 20 is one of the electronic control units (ECUs) mounted on the vehicle 1. The control device 20 incorporates a processor (central processing unit), memory (main memory), storage device, interface device, etc. (not shown), and these are connected to each other via an internal bus so that they can communicate with one another. The decisions and controls performed by the control device 20 are recorded and stored in memory as firmware or application programs, and when a program is executed, the contents of the program are loaded into the memory space and executed by the processor.
[0028] The control device 20 is connected to a vehicle speed sensor 13, an accelerator pedal position sensor 14, a brake sensor 15, a steering angle sensor 16, a front resolver sensor 17, a rear resolver sensor 18, and a wheel speed sensor 19. The vehicle speed sensor 13 detects the vehicle's speed. The accelerator pedal position sensor 14 detects the amount the accelerator pedal is pressed (accelerator position) and the speed at which it is pressed. The brake sensor 15 detects the amount the brake pedal is pressed (brake pedal stroke) and the speed at which it is pressed. The steering angle sensor 16 detects the steering angle and the actual steering angle.
[0029] The front resolver sensors 17 (17L, 17R) detect the angular velocity of each of the front motors 3 (3L, 3R). The rear resolver sensors 18 (18L, 18R) detect the angular velocity of each of the rear motors 8 (8L, 8R). The wheel speed sensors 19 (19L, 19R) detect the angular velocity of each of the rear wheels 7 (7L, 7R). The control device 20 controls the front motors 3 and rear motors 8 based on the information detected by the sensors 13 to 19.
[0030] [2. Control Device] Figure 2 is a block diagram showing the control flow performed by the control device 20. Inside the control device 20 are a driver-requested total torque calculation unit 21, a driver-requested yaw moment calculation unit 22, a requested torque calculation unit 23, a torque difference calculation unit 24, an estimation unit 25, a deficiency torque difference calculation unit 29, a front motor torque limiting unit 30, and a control unit 31.
[0031] Furthermore, the estimation unit 25 is provided with a torque difference transfer function inverse model unit 26, a rear motor torque limiting unit 27, and a torque difference transfer function model unit 28. The control unit 31 may also be provided with a prohibition processing unit 32. These elements are a convenient classification of the functions of the control device 20. These elements may be described as independent programs to realize the functions of each element. Alternatively, multiple elements may be combined and described as a single composite program.
[0032] The driver-requested total torque calculation unit 21 calculates the requested total torque, which is the torque that the driver is requesting from the vehicle 1, based on, for example, the accelerator opening and vehicle speed. The requested total torque corresponds to the sum of the torques requested from each of the left front wheel 2L, right front wheel 2R, left rear wheel 7L, and right rear wheel 7R. The driver-requested yaw moment calculation unit 22 calculates the driver-requested yaw moment, which is the yaw moment that the driver is requesting from the vehicle 1, based on, for example, the steering angle and vehicle speed.
[0033] The requested torque calculation unit 23 calculates the requested wheel torque T for each of the left front wheel 2L, right front wheel 2R, left rear wheel 7L, and right rear wheel 7R based on the requested total torque calculated by the driver requested total torque calculation unit 21 and the requested yaw moment calculated by the driver requested yaw moment calculation unit 22. FL0 ,T FR0 ,T RL0 ,T RR0 The (required torque) is calculated. The torque difference calculation unit 24 calculates the required rear wheel torque difference A (required torque difference), which is the difference between the wheel required torque TRL0 of the left rear wheel 7L and the wheel required torque TRR0 of the right rear wheel 7R. The required rear wheel torque difference A corresponds to the torque difference that the driver is requesting from the rear wheels 7.
[0034] The estimating unit 25 calculates an estimated rear wheel torque difference D (estimated torque difference) of the rear wheels 7 including a torque response delay occurring in the rear drive shaft 52. In calculating the estimated rear wheel torque difference D, the torque difference transfer function inverse model unit 26 calculates a drive torque difference B of the rear motor 8 required to obtain a requested rear wheel torque difference A. The transfer function representing the relationship between the requested rear wheel torque difference A and the drive torque difference B (torque difference transfer function inverse model) is as follows. The denominator on the left side is the requested rear wheel torque difference A, and the numerator is the drive torque difference B.
[0035]
[0036] J DM : Difference in motor inertia between the left rear motor 8L and the right rear motor 8R (motor side) J DL : Difference in inertia between the left rear wheel 7L and the right rear wheel 7R (load side) D DL : Difference in viscosity coefficient between the left rear wheel 7L and the right rear wheel 7R (load side) D s : Sum of viscosity coefficients of the left rear wheel 7L and the right rear wheel 7R (load side) D DM : Difference in viscosity coefficient between the left rear motor 8L and the right rear motor 8R (motor side) K s : Sum of elastic coefficients of the rear drive shaft 52 τ: Time constant
[0037] The rear motor torque limiting unit 27 calculates a corrected drive torque difference C based on at least the drive torque difference B calculated by the torque difference transfer function inverse model unit 26. The corrected drive torque difference C is calculated, for example, by limiting the value of the drive torque difference B to within a predetermined range based on the upper limit torque that can be output by the left rear motor 8L and the right rear motor 8R. When calculating the corrected drive torque difference C, the angular velocity and temperature of the left rear motor 8L and the right rear motor 8R may be taken into consideration.
[0038] The torque difference transfer function model unit 28 calculates the estimated rear wheel torque difference D based on the corrected drive torque difference C. The estimated rear wheel torque difference D calculated here takes into account the torque response delay that occurs in the rear drive shaft 52. The estimated rear wheel torque difference D corresponds to a realistic estimated value of the torque difference affected by such a torque response delay. The transfer function (torque difference transfer function) that represents the relationship between the corrected drive torque difference C and the estimated rear wheel torque difference D is as follows: The denominator of the left side is the corrected drive torque difference C, and the numerator is the estimated rear wheel torque difference D. The right side of this torque difference transfer function is the part corresponding to the low-pass filter [1 / (τs+1)] derived from the right side of the inverse model of the torque difference transfer function described above. 2 This is equivalent to the reciprocal of the result after removing the bracket.
[0039]
[0040] The under-torque difference calculation unit 29 calculates the under-torque difference E, which is the deviation between the required rear wheel torque difference A and the estimated rear wheel torque difference D. The under-torque difference E represents the deficiency in the left-right torque difference of the rear wheels 7, taking into account the effect of the torque response delay caused by the rear drive shaft 52. By transferring the under-torque difference E to the left-right torque difference of the front wheels 2, the under-torque difference E of the rear wheels 7 is compensated for by the front wheels 2.
[0041] The front motor torque limiting unit 30 calculates a corrected under-torque difference F based on the under-torque difference E calculated by at least the under-torque difference calculation unit 29. The corrected under-torque difference F is calculated by limiting the value of the under-torque difference E to a predetermined range based on, for example, the upper limit torque that the left front motor 3L and the right front motor 3R can output. The angular velocity and temperature of the left front motor 3L and the right front motor 3R may be taken into consideration when calculating the corrected under-torque difference F.
[0042] The control unit 31 controls the drive torque of each of the front motors 3 so that the undercorrected torque difference F is compensated for by the front wheels 2. The control unit 31 converts half of the undercorrected torque difference F into the wheel-required torque T of the right front wheel 2R. FR0 By adding this to the right front wheel drive torque T FR The right front-wheel drive torque T is calculated and calculated. FRThe right front motor 3R is driven to obtain the following. At this time, the control unit 31 sets half of the corrected under-torque difference F to the wheel-required torque T of the left front wheel 2L. FL0 Subtracting from this, the left front wheel drive torque T FL The left front wheel drive torque T is calculated and calculated. FL The left front motor 3L is driven to obtain the desired result.
[0043] Furthermore, the control unit 31 sets half of the corrected under-torque difference F to the wheel-required torque T of the right rear wheel 7R. RR0 Subtracting from this, the right rear wheel drive torque T RR The right rear-wheel drive torque T is calculated and calculated. RR The right rear motor 8R is driven to obtain the desired torque T of the left rear wheel 7L. Furthermore, the control unit 31 sets half of the corrected under-torque difference F to the wheel-required torque T of the left rear wheel 7L. RL0 By adding this to the left rear wheel drive torque T RL The left rear wheel drive torque T is calculated and calculated. RL The left rear motor 8L is driven to obtain the desired result.
[0044] In this way, the control unit 31 reduces the left-right torque difference of the rear wheels 7 while increasing the left-right torque difference of the front wheels 2, thereby maintaining a constant total left-right torque difference and transferring the left-right torque difference from the rear wheels 7 to the front wheels 2. This improves the stability of the vehicle 1's behavior (especially its cornering behavior). Furthermore, since the sum of the driving torque of the front wheels 2 and the rear wheels 7 does not change, the stability of the vehicle 1's behavior is further improved.
[0045] The prohibition processing unit 32 determines whether or not to move the insufficient torque difference E from the rear wheels 7 to the front wheels 2, and controls the amount of that movement. For example, when TCL (traction control) is being implemented or when it is determined that the road surface on which the vehicle 1 is traveling is prone to slipping, the prohibition processing unit 32 restricts or prohibits the movement of the insufficient torque difference E by reducing its value (or setting it to 0). This further improves the stability of the vehicle 1's behavior.
[0046] Figures 3(A) to 3(C) are graphs illustrating the control operation by the control device 20. As shown in Figure 3(A), time t ０t is the time when the steering wheel is turned from the neutral position to either the left or right, and time t １ This is the time when the steering operation was stopped. Also, time t ２ This is the time when the steering wheel began to be turned in the opposite direction, and time t ３ This is the time when the steering wheel is brought to a nearly neutral position.
[0047] The driver-requested yaw moment is calculated based, for example, on the steering angle and vehicle speed. As shown in Figure 3(B), the driver-requested yaw moment is calculated at time t ０ It increases rapidly from time t, for example. １ After a slight decrease just before time t １ From this point onward, the value remains almost constant. Also, at time t ２ It decreases rapidly from (for example, to a negative value), for example at time t ３ After a slight increase just before time t ３ From this point onward, the value remains almost constant for a while, eventually becoming zero.
[0048] When attempting to generate the above-mentioned driver-requested yaw moment at the rear wheels 7, the torque response delay occurring in the rear drive shaft 52 causes the actual generated yaw moment to fluctuate as shown by the hatching in Figure 3(C). In other words, the generated yaw moment is smaller than the driver-requested yaw moment shown by the thin solid line in Figure 3(C), resulting in low vehicle behavior stability.
[0049] On the other hand, according to the control device 20 of this embodiment, the torque difference E in the rear wheels 7 is transferred to the left-right torque difference of the front wheels 2. As a result, a left-right torque difference corresponding to the deviation between the driver-requested yaw moment shown by the thin solid line in Figure 3(C) and the yaw moment generated at the rear wheels 7 can be generated in the front wheels 2. Therefore, the driver-requested yaw moment shown by the thin solid line in Figure 3(C) is realized, and the stability of the vehicle behavior is improved.
[0050] [3. Effects] (1) The electric vehicle 1 described above comprises a pair of front motors 3, a pair of rear motors 8, a pair of rear drive shafts 52, a power distribution mechanism 9, and a control device 20. The front motors 3 individually drive the front wheels 2 (first left and right wheels 2L, 2R). The rear motors 8 supply driving force to the rear wheels 7 (second left and right wheels 7L, 7R). The rear drive shafts 52 are connected to each of the rear wheels 7 (second left and right wheels 7L, 7R). The power distribution mechanism 9 is interposed between the pair of rear drive shafts 52 and the pair of rear motors 8. The control device 20 controls the front motors 3 and the rear motors 8.
[0051] The control device 20 includes a required torque calculation unit 23, a torque difference calculation unit 24, an estimation unit 25, a deficiency torque difference calculation unit 29, and a control unit 31. The required torque calculation unit 23 calculates the required torque for each of the first left and right wheels 2L, 2R and the second left and right wheels 7L, 7R. The torque difference calculation unit 24 calculates the required rear wheel torque difference A for the second left and right wheels 7L, 7R. The estimation unit 25 calculates the estimated rear wheel torque difference D for the second left and right wheels 7L, 7R, including the torque response delay that occurs in the rear drive shaft 52.
[0052] The under-torque difference calculation unit 29 calculates the under-torque difference E, which is the deviation between the required rear wheel torque difference A and the estimated rear wheel torque difference D. The control unit 31 controls the drive torque of each of the front motors 3 so that the under-torque difference E (corrected under-torque difference F) is compensated for by the first left and right wheels 2L and 2R. With this configuration, the under-torque difference E of the second left and right wheels 7L and 7R related to the rear drive shaft 52 can be compensated for by the pair of front motors 3, and the yaw moment of the vehicle 1 can be generated with high accuracy. Therefore, the stability of the vehicle's behavior can be improved.
[0053] (2) The control unit 31 shown in Figure 2 converts half of the undercorrected torque difference F into the wheel required torque T of one of the first left and right wheels (in this embodiment, the right front wheel 2R) of the front wheel 2. FR0 Adding this to the required torque T of the other wheel (left front wheel 2L in this embodiment) of the first left and right wheels of the front wheel 2, half of the corrected under-torque difference F is added. FL0 It is subtracted from. The control unit 31 also subtracts half of the corrected under-corrected torque difference F from the wheel-required torque T of one of the second left and right wheels (in this embodiment, the left rear wheel 7L) of the rear wheel 7. RL0Adding this to the required torque T of the second left and right rear wheels (right rear wheel 7R in this embodiment), half of the corrected under-torque difference F is added to the required torque T of the other second left and right rear wheel 7. RR0 Subtract from it.
[0054] This configuration allows the total torque of the front 2 wheels to be maintained, the total torque of the rear 7 wheels to be maintained, and the combined torque of the front 2 wheels and rear 7 wheels to be maintained. In other words, the torque difference between the left and right wheels can be transferred from the rear 7 wheels to the front 2 wheels without changing the total torque of the vehicle 1. Therefore, the stability of the vehicle's behavior can be improved.
[0055] [4. Others] The above embodiments are merely illustrative examples, and there is no intention to exclude the use of various modifications and technologies not explicitly stated in these embodiments. Each configuration of these embodiments can be modified in various ways without departing from their intended purpose. Furthermore, each configuration of these embodiments can be selected or combined as needed.
[0056] In the above embodiment, the in-wheel motor drives the front wheel 2 and the non-in-wheel motor drives the rear wheel 7, but the roles of these drive sources may be swapped. In the above embodiment, the control unit 31 adds or subtracts half of the undercorrected torque difference F to the front wheel 2 and the rear wheel 7, respectively, but the specific correction value can be changed as appropriate. For example, a value slightly smaller than half of the undercorrected torque difference F may be added or subtracted to the front wheel 2 and the rear wheel 7, respectively. Also, the correction value of the torque difference added or subtracted to the front wheel 2 may be slightly different from the correction value of the torque difference added or subtracted to the rear wheel 7.
[0057] In the above embodiment, half of the corrected under-torque difference F is set to the wheel requirement torque T of the right front wheel 2R. FR0 and left rear wheel 7L wheel required torque T RL0 Adding this to the required torque T of the left front wheel 2L, half of the corrected torque difference F is used. FL0 and the required torque T for the right rear wheel 7R RR0 Although subtraction is performed from each of them, the targets of addition and subtraction can be reversed between left and right. That is, half of the undercorrected torque difference F is the wheel requirement torque T of the left front wheel 2L. FL0 and the required torque T for the right rear wheel 7R RR0Adding this to the required torque T of the right front wheel 2R, half of the corrected torque difference F is used. FR0 and the required torque T for the left rear wheel 7L RL0 Subtraction may be performed from each of these values. Alternatively, the front motor torque limiting unit 30 may be omitted, and the above addition and subtraction may be performed using the under-torque difference E instead of the corrected under-torque difference F.
[0058] [5. Addendum] The following addendums are disclosed with respect to the above embodiments and modified examples. [Addendum 1] A control device to be mounted on an electric vehicle, wherein the electric vehicle comprises: a pair of first motors that individually drive first left and right wheels for one of the front wheels and the rear wheels of the vehicle; a pair of second motors that supply driving force to second left and right wheels for the other of the front wheels and the rear wheels; a pair of drive shafts connected to each of the second left and right wheels; a power distribution mechanism interposed between the pair of drive shafts and the pair of second motors; and a control device that controls the first motors and the second motors, wherein the control device comprises: a required torque calculation unit that calculates the required torque for each of the first left and right wheels and the second left and right wheels; a torque difference calculation unit that calculates the required torque difference in the second left and right wheels; an estimation unit that calculates the estimated torque difference of the second left and right wheels, including the torque response delay caused by the drive shafts; a deficiency torque difference calculation unit that calculates the deficiency torque difference, which is the deviation between the required torque difference and the estimated torque difference; and a control unit that controls the driving torque of each of the first motors so that the deficiency torque difference is compensated for by the first left and right wheels.
[0059] [Note 2] The control device according to Note 1, characterized in that the control unit adds half of the insufficient torque difference to the required torque of one of the first left and right wheels, subtracts half of the insufficient torque difference from the required torque of the other of the first left and right wheels, adds half of the insufficient torque difference to the required torque of one of the second left and right wheels, and subtracts half of the insufficient torque difference from the required torque of the other of the second left and right wheels.
[0060] This technology is applicable to the manufacturing industry of electric vehicles (electric cars, hybrid electric vehicles) and the manufacturing industry of control devices installed in electric vehicles.
[0061] 1 Electric Vehicle (Vehicle) 2 Front Wheels 2L Left Front Wheel (First Left and Right Wheels) 2R Right Front Wheel (First Left and Right Wheels) 3 Front Motor (First Motor) 3L Left Front Motor 3R Right Front Motor 4 Engine 5 Generator 6 Transaxle 7 Rear Wheels 7L Left Rear Wheel (Second Left and Right Wheels) 7R Right Rear Wheel (Second Left and Right Wheels) 8 Rear Motor (Second Motor) 8L Left Rear Motor 8R Right Rear Motor 9 Power Distribution Mechanism 11 Front Wheel Drive System 12 Rear Wheel Drive System 13 Vehicle Speed Sensor 14 Accelerator Opening Sensor 15 Brake Sensor 16 Steering Angle Sensor 17 Front Resolver Sensor 18 Rear Resolver Sensor 19 Wheel Speed Sensor 20 Control Device 21 Driver Request Total Torque Calculation Unit 22 Driver Request Yaw Moment Calculation Unit 23 Request Torque Calculation Unit 24 Torque Difference Calculation Unit 25 Estimation unit 26 Torque difference transfer function inverse model unit 27 Rear motor torque limiting unit 28 Torque difference transfer function model unit 29 Under-torque difference calculation unit 30 Front motor torque limiting unit 31 Control unit 32 Prohibition processing unit 51 Front drive shaft 51L Left front drive shaft 51R Right front drive shaft 52 Rear drive shaft (drive shaft) 52L Left rear drive shaft 52R Right rear drive shaft A Required rear wheel torque difference (required torque difference) B Drive torque difference C Corrected drive torque difference D Estimated rear wheel torque difference (estimated torque difference) E Under-torque difference F Corrected under-torque difference
Claims
1. An electric vehicle comprising: a pair of first motors that individually drive first left and right wheels for one of the front wheels and the rear wheels; a pair of second motors that supply driving force to second left and right wheels for the other of the front wheels and the rear wheels; a pair of drive shafts connected to each of the second left and right wheels; a power distribution mechanism interposed between the pair of drive shafts and the pair of second motors; and a control device that controls the first motors and the second motors, wherein the control device comprises: a required torque calculation unit that calculates the required torque for each of the first left and right wheels and the second left and right wheels; a torque difference calculation unit that calculates the difference in required torque at the second left and right wheels; an estimation unit that calculates the estimated torque difference at the second left and right wheels, including the torque response delay at the drive shafts; a deficiency torque difference calculation unit that calculates the deficiency torque difference, which is the deviation between the required torque difference and the estimated torque difference; and a control unit that controls the driving torque of each of the first motors so that the deficiency torque difference is compensated for by the first left and right wheels.
2. The electric vehicle according to claim 1, characterized in that the control unit adds half of the insufficient torque difference to the required torque of one of the first left and right wheels, subtracts half of the insufficient torque difference from the required torque of the other of the first left and right wheels, adds half of the insufficient torque difference to the required torque of one of the second left and right wheels, and subtracts half of the insufficient torque difference from the required torque of the other of the second left and right wheels.