electric vehicles

Abstract

In an electric vehicle equipped with a first motor that inputs and outputs driving force to the first axle and a second motor that inputs and outputs driving force to the second axle, the aim is to reduce the discomfort experienced by the driver or passengers when the timing of the target torques of the first and second motors exceeds the play range in which play occurs is misaligned. [Solution] When the target torque of the first and second motors exceeds the play region where play occurs relative to the current operating torque, an intermediate torque near the play region is set as the target torque, and the operating torques of the first and second motors are adjusted so that they reach the target torque simultaneously.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle, and more particularly to an electric vehicle including a first electric motor that inputs and outputs a driving force to a first axle and a second electric motor that inputs and outputs a driving force to a second axle.

Background Art

[0002] Conventionally, as this type of electric vehicle, when the driving force transmission mechanism of one of the front motor and the rear motor passes through a backlash section (play region), it has been proposed to correct the torque of the other motor (see, for example, Patent Document 1). In this electric vehicle, by correcting the torque of the other motor, the acceleration / deceleration desired by the driver is realized.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electric vehicle including a first electric motor for the front wheels and a second electric motor for the rear wheels, when the target torque straddles the play region of each driving force transmission mechanism with respect to the current torque (execution torque), if the timing for the first electric motor to straddle the play region and the timing for the second electric motor to straddle the play region differ even slightly, the acceleration of the vehicle may deviate from the target acceleration, or the collision energy at the time of play coupling may change, causing an unexpected shock and discomfort to the driver and passengers.

[0005] The electric vehicle of this disclosure is an electric vehicle equipped with a first electric motor that inputs and outputs driving force to a first axle and a second electric motor that inputs and outputs driving force to a second axle, and its main purpose is to reduce the discomfort caused to the driver or passengers when the timing of the target torques of the first electric motor and the second electric motor is misaligned when they exceed a play range in which play occurs. [Means for solving the problem]

[0006] The electric vehicle of this disclosure employs the following means to achieve the main objective described above.

[0007] The electric vehicle disclosed herein is A first electric motor that inputs and outputs driving force to the first axle, A second electric motor that inputs and outputs driving force to a second axle different from the first axle, A control device for controlling the first motor and the second motor, An electric vehicle equipped with, When the target torque of the first and second motors exceeds a play region where play occurs relative to the current operating torque, the control device sets an intermediate torque near the play region as the target torque and adjusts the operating torque of the first and second motors so that they simultaneously reach the target torque. It is characterized by the following:

[0008] The electric vehicle of this disclosure includes a first electric motor that inputs and outputs driving force to a first axle, a second electric motor that inputs and 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 backlash region where backlash occurs relative to the current operating torque, an intermediate torque near the backlash region is set as the target torque, and the operating torque of the first electric motor and the second electric motor are adjusted so that they reach the target torque (intermediate torque) simultaneously. As a result, the operating torque of the first electric motor and the second electric motor can cross the backlash region almost simultaneously. As a result, the discomfort caused to the driver or passengers due to the timing difference when the operating torque of the first electric motor and the second electric motor crosses the backlash region can be reduced.

[0009] In the electric vehicle of this disclosure, the intermediate torque may be a torque that slightly exceeds the backlash region (a torque that exceeds a predetermined torque) when viewed from the current operating torque of the first and second electric motors. In this way, the operating torques of the first and second electric motors can cross the backlash region almost simultaneously.

[0010] In the electric vehicle of this disclosure, the control device may calculate a rate value such that the effective torque of the first electric motor and the second electric motor simultaneously becomes the intermediate torque, and set the effective torque by rate limit processing using the rate value. In this way, the effective torque can be easily brought to the intermediate torque simultaneously. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing the configuration of an electric vehicle 20 as one embodiment of the present disclosure. [Figure 2] This flowchart shows an example of the execution torque setting process performed by the electronic control unit 60. [Figure 3] This flowchart shows an example of the torque rate setting process performed by the electronic control unit 60. [Figure 4] This is an explanatory diagram illustrating an example of how the target torques T1* and T2* of the first motor 22 and the second motor 32 cross the backlash region when viewed from the actual torques T1 and T2. [Modes for carrying out the invention]

[0012] Next, embodiments for implementing this disclosure will be described. Figure 1 is a schematic diagram showing the configuration of an electric vehicle 20 as one embodiment of this disclosure. The electric vehicle 20 of this embodiment includes a first motor 22, a first inverter 24, a second motor 32, a second inverter 34, a battery 40, and an electronic control unit 60.

[0013] The first motor 22 and the second motor are configured, for example, as synchronous regenerative motors. The rotor of the first motor 22 (not shown) is connected to a drive shaft 26 which is connected to the front wheels 29a and 29b via a differential gear 28. The rotor of the second motor 32 (not shown) is connected to a drive shaft 36 which is connected to the rear wheels 39a and 39b via a differential gear 38. The first motor 22 and the second motor 32 are fitted with rotation position detection sensors 22a and 32a, respectively, for detecting the rotational position of the rotors.

[0014] The first inverter 24 and the second inverter 34 are configured as well-known inverter circuits having six transistors and six diodes. The first inverter 24 and the second inverter 34 are connected to a power line 42 connected to a battery 40. The first inverter 24 converts DC power from the battery 40 into three-phase AC power by PWM control and applies it to the first motor 22 to drive the first motor 22. The second inverter 24, similar to the first inverter 24, converts DC power from the battery 40 into three-phase AC power by PWM control and applies it to the second motor 32 to drive the second motor 32.

[0015] The battery 40 is configured as, for example, a lithium-ion battery and is connected to the power line 32. Voltage sensors (not shown) for detecting the battery voltage Vb are attached to both terminals of the battery 40. Current sensors (not shown) for detecting the battery current Ib are attached to the terminals of the battery 40. A smoothing capacitor 44 and a voltage sensor 46 for detecting its voltage VH are attached to the power line 42.

[0016] The electronic control unit 60 is configured as a microcomputer centered around a CPU 62. In addition to the CPU 62, the electronic control unit 60 includes a ROM 64, RAM 66, flash memory (not shown), input ports (not shown), output ports (not shown), and the like.

[0017] The electronic control unit 60 inputs the rotational positions θ1 and θ2 of the first motor 22 and the second motor 32 detected by the rotational position detection sensors 22a and 32a, the voltage VH detected by the voltage sensor 44, etc. via the input ports. The electronic control unit 60 also inputs the start signal ST from the start switch 70, the shift position SP detected by the shift lever position sensor 72 attached to the shift lever 71, the accelerator opening Acc detected by the accelerator pedal position sensor 74 attached to the accelerator pedal 73, and the brake pedal position BP detected by the brake pedal position sensor 76 attached to the brake pedal 75. The electronic control unit 60 also inputs the vehicle speed V detected by the vehicle speed sensor 78 and the acceleration α detected by the acceleration sensor 80.

[0018] The electronic control unit 60 outputs switching control signals to the first inverter 24 and the second inverter 34, display control signals to the display 82, etc. via the output ports. The electronic control unit 60 calculates the rotational speeds Nm1 and Nm2 of the first motor 22 and the second motor 32 based on the rotational positions θ1 and θ2 of the rotors of the first motor 22 and the second motor 32, and calculates the state of charge SOC of the battery 40 based on the integrated value of the battery current Ib.

[0019] Next, the operation of the electric vehicle 20 of the embodiment will be described, particularly when the target torques T1* and T2* of the first motor 22 and the second motor 32 cross a play region in the drive force transmission system (differential gears 28, 38, etc.) where play occurs, relative to the current execution torques T1 and T2. Figure 2 is a flowchart showing an example of the execution torque setting process performed by the electronic control unit 60, and Figure 3 is a flowchart showing an example of the torque rate setting process performed by the electronic control unit 60. The following will be explained in order. In the electric vehicle 20 of the embodiment, the vehicle-required torque Tdrv* is set at a predetermined timing according to the accelerator opening Acc and the vehicle speed V, the front wheel-required torque Tf* and the rear wheel-required torque Tr* are determined using a front-to-rear distribution ratio according to the driving state, and the target torques T1* and T2* of the first motor 22 and the second motor 32 are set by multiplying the front wheel-required torque Tf* and the rear wheel-required torque Tr* by the gear ratio of the drive force transmission system.

[0020] When the execution torque setting process shown in Figure 2 is executed, the electronic control unit 60 acquires the execution torques T1 and T2 and torque rates Tr1 and Tr2 that were set when this process was last executed (step S100). Torque rates Tr1 and Tr2 are acquired by inputting those set by the torque rate setting process shown in Figure 3, which will be described later. Then, the new execution torques T1 and T2 (T1 = previous T1 + Tr1, T2 = previous T2 + Tr2) are set by adding the torque rates Tr1 and Tr2 to the previous execution torques T1 and T2, respectively (step S110), and this process ends. Once the execution torques T1 and T2 are set, the switching elements of the first inverter 24 and the second inverter 34 are switched to control so that the set execution torques T1 and T2 are output from the first motor 22 and the second motor 32.

[0021] When the torque rate setting process of FIG. 3 is executed, the electronic control unit 60 first acquires the execution torques T1 and T2 and the target torques T1* and T2* of the first motor 22 and the second motor 32 (step S200). Then, it is determined whether or not the target torques T1* and T2* of the first motor 22 and the second motor 32 cross a backlash region where backlash occurs in the drive force transmission system when viewed from the execution torques T1 and T2 (step S210). Since the backlash region is basically a region where the torque crosses the value 0, the determination of whether or not it crosses the backlash region is a determination of whether or not the target torques T1* and T2* cross the value 0 when viewed from the execution torques T1 and T2.

[0022] When it is determined in step S210 that the target torques T1* and T2* do not cross the backlash region when viewed from the execution torques T1 and T2, the variable k is calculated by dividing the time required for the execution torques T1 and T2 to reach the target torques T1* and T2* by the repetition period of the execution torque setting process (step S240), and the torque rates Tr1 and Tr2 (Tr1 = (T1* - T1) / k, Tr2 = (T2* - T2) / k) are calculated by dividing the difference obtained by subtracting the execution torques T1 and T2 from the target torques T1* and T2* by the variable k (step S250), and this process ends. Note that the time required for the execution torques T1 and T2 to reach the target torques T1* and T2* can be obtained according to the difference obtained by subtracting the execution torques T1 and T2 from the target torques T1* and T2*. For example, it is possible to consider obtaining the difference obtained by subtracting the execution torques T1 and T2 from the target torques T1* and T2* (the larger of the differences) by dividing it by a predetermined value, an average value, or a median value as the torque rate.

[0023] If, in step S210, it is determined that the target torques T1*, T2* cross the backlash region when viewed from the actual torques T1, T2, then intermediate torques Tm1, Tm2 are set to values ​​near the backlash region, for example, values ​​that slightly exceed the backlash region by a predetermined value when viewed from the actual torques T1, T2 (step S220), and the set intermediate torques Tm1, Tm2 are set as the target torques T1*, T2* (step S230). Then, the time required for the actual torques T1, T2 to reach the target torques T1*, T2* is divided by the time around the repetition of the actual torque setting process to calculate the variable k (step S240), and the torque rates Tr1, Tr2 are calculated by dividing the difference (target torques T1*, T2* minus the actual torques T1, T2) by the variable k (step S250), and this process is terminated. By setting intermediate torques Tm1 and Tm2 as values ​​near the backlash region, and by processing the set intermediate torques Tm1 and Tm2 as target torques T1* and T2*, the effective torques T1 and T2 of the first motor 22 and the second motor 32 simultaneously reach the intermediate torques Tm1 and Tm2. As a result, the effective torques T1 and T2 of the first motor 22 and the second motor 32 simultaneously cross the backlash region.

[0024] Figure 4 is an explanatory diagram illustrating an example of how the target torques T1* and T2* of the first motor 22 and the second motor 32 cross the backlash region relative to the actual torques T1 and T2. As shown in the figure, the target torques T1* and T2* of the first motor 22 and the second motor 32 are positive values, and the actual torques T1 and T2 are negative values. Therefore, the target torques T1* and T2* cross the backlash region where the torque is 0 relative to the actual torques T1 and T2. In this embodiment, intermediate torques Tm1 and Tm2 are set to values ​​slightly larger than 0, and the actual torques T1 and T2 reach intermediate torques Tm1 and Tm2 simultaneously. As a result, the actual torques T1 and T2 of the first motor 22 and the second motor 32 cross the backlash region simultaneously. Therefore, shocks caused by a timing difference in how the actual torques T1 and T2 of the first motor 22 and the second motor 32 cross the backlash region are not felt by the driver or occupants. On the other hand, if the effective torques T1 and T2 are made to reach the target torques T1* and T2* simultaneously without setting intermediate torques Tm1 and Tm2, ​​the timing of when the effective torques T1 and T2 of the first motor 22 and the second motor 32 cross the play region may be out of sync, causing discomfort such as shocks to the driver or passengers.

[0025] In the electric vehicle 20 of the embodiment described above, when the target torques T1* and T2* of the first motor 22 and the second motor 32 cross the backlash region with respect to the actual torques T1 and T2, intermediate torques Tm1 and Tm2 are set to values ​​near the backlash region or values ​​that exceed the backlash region by a predetermined amount, and the set intermediate torques Tm1 and Tm2 are set to target torques T1* and T2*. Next, the variable k is calculated based on the time required for the actual torques T1 and T2 to reach the target torques T1* and T2*, and the torque rates Tr1 and Tr2 are calculated by dividing the difference (subtraction of the actual torques T1 and T2 from the target torques T1* and T2*) by the variable k. Then, the actual torques T1 and T2 are set by rate limit processing using these torque rates Tr1 and Tr2, and the switching elements of the first inverter 24 and the second inverter 34 are switched to control so that the set actual torques T1 and T2 are output from the first motor 22 and the second motor 32. This ensures that the effective torques T1 and T2 of the first motor 22 and the second motor 32 cross the play region simultaneously, preventing the driver or occupants from feeling shocks caused by a timing mismatch in the effective torques T1 and T2 of the first motor 22 and the second motor 32 crossing the play region.

[0026] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the first motor 22 corresponds to the "first electric motor," the second motor 32 corresponds to the "second electric motor," and the electronic control unit 60 corresponds to the "control device."

[0027] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0028] Although the present disclosure has been described above using embodiments, the present disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of the present disclosure. [Industrial applicability]

[0029] This disclosure can be used in industries such as electric vehicle manufacturing. [Explanation of symbols]

[0030] 20 Electric vehicle, 22 First motor, 22a Rotation position detection sensor, 24 First inverter, 26 Drive shaft, 28 Differential gear, 29a, 29b Front wheels, 32 Second motor, 32a Rotation position detection sensor, 34 Second inverter, 36 Drive shaft, 38 Differential gear, 39a, 39b Rear wheels, 40 Battery, 42 Power line, 44 Capacitor, 46 Voltage sensor, 60 Electronic control unit, 62 CPU, 64 ROM, 66 RAM, 70 Start switch, 71 Shift lever, 72 Shift position sensor, 73 Accelerator pedal, 74 Accelerator pedal position sensor, 75 Brake pedal, 76 Brake pedal position sensor, 78 Vehicle speed sensor, 80 Acceleration sensor, 82 Display.

Claims

1. A first electric motor that inputs and outputs driving force to the first axle, A second electric motor that inputs and outputs driving force to a second axle different from the first axle, A control device for controlling the first motor and the second motor, An electric vehicle equipped with, When the target torque of the first motor and the second motor exceeds a play region where play occurs relative to the current operating torque, the control device sets an intermediate torque near the play region as the target torque and adjusts the operating torque of the first motor and the second motor so that they simultaneously reach the target torque. An electric vehicle characterized by the following features.

2. The electric vehicle according to claim 1, The aforementioned intermediate torque is a torque that slightly exceeds the aforementioned backlash region when viewed from the current operating torque of the first and second electric motors. Electric car.

3. The electric vehicle according to claim 1, The control device calculates a rate value such that the effective torque of the first motor and the second motor simultaneously becomes the intermediate torque, and sets the effective torque by rate limiting processing using the rate value. Electric car.

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