Electric vehicle

Abstract

When the target torque of the first motor and the second motor exceeds a gap region in which a gap is generated with respect to the current execution torque, the intermediate torque near the gap region is set as the target torque, and the execution torque of the first motor and the second motor is adjusted so as to simultaneously reach the target torque.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrified vehicle, and more particularly to an electrified vehicle equipped with a first electric motor that inputs / outputs driving force to a first axle and a second electric motor that inputs / outputs driving force to a second axle. BACKGROUND

[0002] In the past, as such an electrified vehicle, there has been proposed an electrified vehicle in which, when a driving force transmission mechanism of one of a front motor and a rear motor crosses a backlash region, the torque of the other electric motor is corrected. For example, refer to Japanese Patent Application Publication No. 2024-098879. In this electrified vehicle, by correcting the torque of the other electric motor, the acceleration or deceleration desired by the driver is realized. SUMMARY

[0003] In an electrified vehicle equipped with a first electric motor for front wheels and a second electric motor for rear wheels, when a target torque crosses a backlash region of each driving force transmission mechanism with respect to a current torque (executed torque), if the timing at which the first electric motor crosses the backlash region and the timing at which the second electric motor crosses the backlash region are slightly different, the acceleration of the vehicle sometimes deviates from a target acceleration, or the impact energy at the time of backlash engagement changes to cause an unexpected impact. This causes the driver or attendant to feel discomfort.

[0004] The electrified vehicle of the present application is equipped with a first electric motor that inputs / outputs driving force to a first axle and a second electric motor that inputs / outputs driving force to a second axle. The main object of the electrified vehicle is to reduce the discomfort of the driver or attendant caused by the timing at which the target torque of the first electric motor and the target torque of the second electric motor cross a backlash region in which backlash occurs deviating.

[0005] In order to achieve the above main object, the electrified vehicle of the present application employs the following means.

[0006] The electrified vehicle of the present application is characterized by being equipped with:

[0007] a first electric motor that inputs / outputs driving force to a first axle;

[0008] a second electric motor that inputs / outputs driving force to a second axle different from the first axle; and

[0009] a control device that controls the first electric motor and the second electric motor,

[0010] When the target torque of the first electric motor and the second electric motor exceeds a gap region in which a gap is generated with respect to the current execution torque, the control device sets an intermediate torque in the vicinity of the gap region to the target torque, and adjusts so that the execution torques of the first electric motor and the second electric motor reach the target torque at the same time.

[0011] The electric vehicle of the present application includes a first electric motor that inputs / outputs driving force to a first axle, a second electric motor that inputs / outputs driving force to a second axle different from the first axle, and a control device that controls the first electric motor and the second electric motor. When the target torque of the first electric motor and the second electric motor exceeds a gap region in which a gap is generated with respect to the current execution torque, the control device sets an intermediate torque in the vicinity of the gap region to the target torque. The control device adjusts so that the execution torques of the first electric motor and the second electric motor reach the target torque at the same time. Thus, the execution torques of the first electric motor and the second electric motor can cross the gap region at substantially the same time. As a result, the feeling of discomfort of the driver or the attendant due to the timing of the execution torques of the first electric motor and the second electric motor exceeding the gap region shifting can be reduced.

[0012] In the electric vehicle of the present application, the intermediate torque can be a torque that slightly exceeds the gap region with respect to the current execution torques of the first electric motor and the second electric motor (a torque that exceeds a prescribed torque). Thus, the execution torques of the first electric motor and the second electric motor can cross the gap region at substantially the same time.

[0013] In the electric vehicle of the present application, the control device performs the following processing:

[0014] The rate value is calculated so that the execution torques of the first electric motor and the second electric motor reach the intermediate torque at the same time,

[0015] The execution torques can be set by a rate limit process using the rate value.

[0016] Thus, the execution torques can be easily made to reach the intermediate torque at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0017] Features, advantages, and technical and industrial significance of exemplary embodiments of the present application will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

[0018] Figure 1 is a schematic configuration view that shows the configuration of the electric vehicle 20 as an embodiment of the present application.

[0019] Figure 2 is a flowchart that shows an example of the execution torque setting processing performed by the electronic control unit 60.

[0020] Figure 3 is a flowchart showing an example of the torque ratio setting processing performed by the electronic control unit 60.

[0021] Figure 4 is an explanatory diagram showing an example of the case where the target torques T1*, T2* of the first and second motors 22, 32 cross the gap region with respect to the applied torques T1, T2. DETAILED DESCRIPTION

[0022] Next, a mode (embodiment) for implementing the present application will be described. Figure 1 is a configuration diagram showing an outline of the structure of the electric vehicle 20 as an embodiment of the present application. The electric vehicle 20 of the embodiment is provided with the first motor 22, the first inverter 24, the second motor 32, the second inverter 34, the battery 40, and the electronic control unit 60.

[0023] The first and second motors 22, 32 are configured as synchronous motor generators, for example. A not-shown rotor of the first motor 22 is connected to a drive shaft 26, which is linked to front wheels 29a, 29b via a differential gear 28. A not-shown rotor of the second motor 32 is connected to a drive shaft 36, which is linked to rear wheels 39a, 39b via a differential gear 38. Rotational position detection sensors 22a, 32a that detect the rotational positions of the rotors are attached to the first and second motors 22, 32.

[0024] The first and second inverters 24, 34 are configured as known inverter circuits having six transistors and six diodes. The first and second inverters 24, 34 are connected to a power line 42 connected to the battery 40. The first inverter 24 converts direct-current electric power from the battery 40 into three-phase alternating current through PWM control and applies it to the first motor 22, thereby driving the first motor 22. Similarly to the first inverter 24, the second inverter 24 converts direct-current electric power from the battery 40 into three-phase alternating current through PWM control and applies it to the second motor 32, thereby driving the second motor 32.

[0025] The battery 40 is configured as a lithium ion battery, for example, and is connected to the power line 42. A not-shown voltage sensor that detects a battery voltage Vb is attached to both terminals of the battery 40. A not-shown current sensor that detects a battery current Ib is attached to a terminal of the battery 40. A capacitor 44 for smoothing or a voltage sensor 46 that detects a voltage VH thereof is attached to the power line 42.

[0026] The electronic control unit 60 is configured as a microcomputer centered on the CPU 62. The electronic control unit 60 has, in addition to the CPU 62, a ROM 64, a RAM 66, a flash memory (not shown), an input port (not shown), an output port (not shown), and the like.

[0027] The electronic control unit 60 inputs, via the input port, the rotational position θ1, θ2 of the first motor 22 or the second motor 32 detected by the rotational position detection sensor 22a, 32a, the voltage VH detected by the voltage sensor 44, and the like. The electronic control unit 60 also inputs the start signal ST from the start switch 70, the shift position SP, the accelerator opening degree Acc, the brake pedal position BP. The shift position SP is detected by a shift lever position sensor 72 installed to the shift lever 71. The accelerator opening degree Acc is detected by an accelerator pedal position sensor 74 installed to the accelerator pedal 73. The brake pedal position BP is detected by a brake pedal position sensor 76 installed to the brake pedal 75. The electronic control unit 60 also inputs the vehicle speed V detected by a vehicle speed sensor 78, the acceleration α detected by an acceleration sensor 80.

[0028] The electronic control unit 60 outputs, via the output port, a switching control signal to the first inverter 24 or the second inverter 34, a display control signal to the display 82, and the like. The electronic control unit 60 calculates the rotational speed Nm1, Nm2 of the first motor 22 or the second motor 32 based on the rotational position θ1, θ2 of the rotor of the first motor 22 or the second motor 32. The electronic control unit 60 calculates the charge ratio SOC of the battery 40 based on the cumulative value of the battery current Ib.

[0029] Next, the operation of the electric vehicle 20 of the embodiment will be described. In particular, the operation when the target torque T1*, T2* of the first motor 22 and the second motor 32 crosses the gap region in which a gap is generated in the drive force transmission system (differential gears 28, 38, and the like) with respect to the current execution torque T1, T2 will be described. Figure 2 is a flowchart showing an example of execution torque setting processing executed by the electronic control unit 60, Figure 3 is a flowchart showing an example of torque ratio setting processing executed by the electronic control unit 60. The following will be described in order. In the electric vehicle 20 of the embodiment, at a prescribed timing, the vehicle requested torque Tdrv* is set in accordance with the accelerator opening degree Acc and the vehicle speed V. The front wheel requested torque Tf* and the rear wheel requested torque Tr* of the vehicle requested torque Tdrv* are calculated using the front-rear distribution ratio based on the running state. The target torque T1*, T2* of the first motor 22 and the second motor 32 are set by multiplying the front wheel requested torque Tf* and the rear wheel requested torque Tr* by the gear ratio of the drive force transmission system.

[0030] If the execution Figure 2If the execution torque setting process is performed, the electronic control unit 60 obtains the execution torques T1 and T2 and torque rates Tr1 and Tr2 set during the last execution of this process (S100). The torque rates Tr1 and Tr2 are input via the parameters described later. Figure 3 The torque rate setting process obtains the target torques T1* and T2*. Furthermore, the values ​​obtained by adding the torque rates Tr1 and Tr2 to the previously executed torques T1 and T2 respectively are set as the new executed torques T1 and T2 (T1 = previous T1 + Tr1, T2 = previous T2 + Tr2) (S110), and the process ends. If the executed torques T1 and T2 are set, the switching elements of the first inverter 24 and the second inverter 34 are switched to output the set executed torques T1 and T2 from the first motor 22 and the second motor 32.

[0031] If executed Figure 3 In the torque rate setting process, the electronic control unit 60 first acquires the execution torques T1 and T2 of the first motor 22 and the target torques T1* and T2* of the second motor 32 (S200). Furthermore, it determines whether the target torques T1* and T2* of the first motor 22 and the second motor 32 cross the gap region that creates a gap in the drive force transmission system relative to the execution torques T1 and T2 (S210). The gap region is essentially the area where the torque crosses a value of 0; therefore, determining whether the gap region is crossed becomes a determination of whether the target torques T1* and T2* cross a value of 0 relative to the execution torques T1 and T2.

[0032] If, in S210, it is determined that the target torques T1* and T2* have not crossed the gap region relative to the executed torques T1 and T2, the variable k is calculated by dividing the time required for the executed torques T1 and T2 to reach the target torques T1* and T2* by the repetition cycle of the executed torque setting process (S240). The torque ratios Tr1 and Tr2 are calculated by dividing the difference between the executed torques T1* and T2* (T1 = (T1* - T1) / k, Tr2 = (T2* - T2) / k) by the variable k (S250). This process ends. Furthermore, the time required for the executed torques T1 and T2 to reach the target torques T1* and T2* can be obtained from the difference between the executed torques T1* and T2*. For example, the larger of the values ​​(differences) obtained by subtracting the execution torques T1 and T2 from the target torques T1* and T2* can be divided by a specified value or used as the average or median value of the torque ratio.

[0033] In S210, if it is determined that the target torques T1* and T2* cross the gap region relative to the executed torques T1 and T2, the values ​​near the gap region, such as values ​​that exceed the gap region by only a small predetermined value relative to the executed torques T1 and T2, are set as intermediate torques Tm1 and Tm2 (S220). The set intermediate torques Tm1 and Tm2 are set as target torques T1* and T2* (S230). Furthermore, the variable k is calculated by dividing the time required for the executed torques T1 and T2 to reach the target torques T1* and T2* by the repetition period of the executed torque setting process (S240). The torque ratios Tr1 and Tr2 are calculated by dividing the value (difference) obtained by subtracting the executed torques T1 and T2* from the target torques T1* and T2* by the variable k (S250). This process ends. Thus, the intermediate torques Tm1 and Tm2 are set as values ​​near the gap region, and the set intermediate torques Tm1 and Tm2 are processed as target torques T1* and T2*. Therefore, the execution torques T1 and T2 of the first motor 22 and the second motor 32 simultaneously reach the intermediate torques Tm1 and Tm2. Consequently, the execution torques T1 and T2 of the first motor 22 and the second motor 32 simultaneously cross the gap region.

[0034] Figure 4 This is an explanatory diagram illustrating an example of the target torques T1* and T2* of the first motor 22 and the second motor 32 crossing a gap region relative to the execution torques T1 and T2. As shown, the target torques T1* and T2* of the first motor 22 and the second motor 32 are positive values. The execution torques T1 and T2 are negative values. Therefore, the target torques T1* and T2* cross a gap region where the torque value is 0 relative to the execution torques T1 and T2. In this embodiment, a value slightly greater than 0 is set as the intermediate torques Tm1 and Tm2. The execution torques T1 and T2 reach the intermediate torques Tm1 and Tm2 simultaneously. Therefore, the execution torques T1 and T2 of the first motor 22 and the second motor 32 simultaneously cross the gap region. Thus, the driver or passenger will not experience any impact or other disturbances due to a misalignment in the timing of the execution torques T1 and T2 crossing the gap region. On the other hand, if intermediate torques Tm1 and Tm2 are not set and the execution torques T1 and T2 simultaneously reach the target torques T1* and T2*, the timing of the execution torques T1 and T2 of the first motor 22 and the second motor 32 crossing the gap region will be off. This will cause discomfort such as shock to the driver or crew.

[0035] In the electric vehicle 20 described above, when the target torques T1* and T2* of the first motor 22 and the second motor 32 cross a gap region relative to the execution torques T1 and T2, the values ​​near the gap region or the values ​​exceeding the gap region by only a predetermined value are set as intermediate torques Tm1 and Tm2. These intermediate torques Tm1 and Tm2 are then set as target torques T1* and T2*. Next, based on the time required for the execution torques T1 and T2 to reach the target torques T1* and T2*, a variable k is calculated, and the difference between the target torques T1* and T2* and the execution torques T1 and T2 is divided by the variable k to calculate torque rates Tr1 and Tr2. Furthermore, the execution torques T1 and T2 are set using a rate limiting process for these torque rates Tr1 and Tr2. Switching control is applied to the switching elements of the first inverter 24 and the second inverter 34 to output the set execution torques T1 and T2 from the first motor 22 and the second motor 32. Therefore, the execution torques T1 and T2 of the first motor 22 and the second motor 32 simultaneously cross the gap region. This prevents the driver or passenger from feeling any impact or other disturbance caused by the timing of the execution torques T1 and T2 of the first motor 22 and the second motor 32 crossing the gap region.

[0036] The correspondence between the main elements of the implementation method and the main elements of the invention described in the solution to the problem section will be explained. In the implementation method, the first motor 22 is equivalent to "first electric motor", the second motor 32 is equivalent to "second electric motor", and the electronic control unit 60 is equivalent to "control device".

[0037] Furthermore, the correspondence between the main elements of the implementation method and the main elements of the invention described in the "Solution to Solve the Problem" column is merely an example of how the implementation method is used to carry out the invention described in the "Solution to Solve the Problem" column. This does not limit the elements of the invention described in the "Solution to Solve the Problem" column. That is, the interpretation of the invention described in the "Solution to Solve the Problem" column should be based on the description in that column, and the implementation method is merely a specific example of the invention described in the "Solution to Solve the Problem" column.

[0038] The present invention has been described above using embodiments, but the present invention is not limited to such embodiments. It can of course be implemented in various ways without departing from the spirit of the present invention.

[0039] This invention can be applied to industries such as electric vehicle manufacturing.

Claims

1. An electric vehicle, characterized by comprising: Possessing: a first motor that inputs / outputs driving force to a first axle; a second motor that inputs / outputs driving force to a second axle different from the first axle; and a control device that controls the first motor and the second motor, when target torque of the first motor and the second motor exceeds a gap region in which a gap is generated with respect to current execution torque, the control device sets intermediate torque in the vicinity of the gap region as the target torque, and adjusts so that execution torque of the first motor and the second motor simultaneously reaches the target torque.

2. The electric vehicle according to claim 1, wherein the intermediate torque is torque that slightly exceeds the gap region with respect to current execution torque of the first motor and the second motor.

3. The electric vehicle according to claim 1, wherein the control device performs the following processing: calculates a rate value so that execution torque of the first motor and the second motor simultaneously reaches the intermediate torque, sets the execution torque by a rate limiting process using the rate value.

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