Vehicle drive control method and vehicle drive control device

Abstract

Provided is a vehicle drive control method that, when a parking lock of an electric vehicle is released, controls the output torque of a drive motor mounted in the electric vehicle. In the vehicle drive control method, a first gradient estimation value determined on the basis of the longitudinal acceleration of the electric vehicle is acquired, and a second gradient estimation value determined on the basis of the rotation state of the drive motor is acquired. When the first gradient estimation value and the second gradient estimation value satisfy a prescribed first control permission condition, the output torque is set to a shock suppression torque for suppressing a shock which is generated when releasing the parking lock. When the first gradient estimation value and the second gradient estimation value do not satisfy the first control permission condition, the output torque is set to a prescribed basic torque.

Description

Vehicle drive control method and vehicle drive control device

[0001] The present invention relates to a vehicle drive control method and a vehicle drive control device for controlling the output torque of a drive motor mounted on an electric vehicle.

[0002] JP4297135B2 proposes a control method that calculates torsional torque based on the engine rotation speed when reverse gear is established during parking shift operation (operating the shift lever to the "P" position), and operates the motor generator so as to apply a torque in the opposite direction to that torsional torque, thereby preventing the sudden release of torsional torque when the parking gear is unlocked.

[0003] In the control method of JP4297135B2, the magnitude of the reverse torque is estimated from the mechanical characteristics when the driving force is being transmitted. Therefore, depending on the vehicle condition (e.g., whether the vehicle is stopped on a slope), the estimated magnitude of the reverse torque may deviate from the actually required value. Therefore, outputting such an inaccurate reverse torque may lead to unintended sudden acceleration.

[0004] Therefore, an object of the present invention is to prevent unintended sudden acceleration while reducing the shock caused by the torsional torque that occurs when the parking lock is released.

[0005] According to one aspect of the present invention, there is provided a vehicle drive control method for controlling the output torque of a drive motor mounted on an electric vehicle when the parking lock of the electric vehicle is released.

[0006] In this vehicle drive control method, a first gradient estimate is obtained based on the longitudinal acceleration of the electric vehicle, and a second gradient estimate is obtained based on the rotational state of the drive motor. If the first gradient estimate and the second gradient estimate satisfy a predetermined first control permission condition, the output torque is set to a shock suppression torque for suppressing a shock that occurs when the parking lock is released. If the first gradient estimate and the second gradient estimate do not satisfy the first control permission condition, the output torque is set to a predetermined basic torque.

[0007] FIG. 1 is a block diagram showing the main configuration of an electric vehicle according to an embodiment of the present invention. FIG. 2 is a block diagram showing the detailed configuration of a controller. FIG. 3 is a flowchart illustrating details of a first control permission determination process. FIG. 4 is a flowchart illustrating details of a second control permission determination process. FIG. 5 is a flowchart illustrating details of a torque output process. FIG. 6 is a diagram showing an example of a specific mode for determining a shock suppression torque command value. FIG. 7 is a timing chart showing an example of a control result according to this embodiment.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The control device for an electric vehicle of the present invention is applicable to an electric vehicle that has an electric motor as part or all of the vehicle's drive source and can run using the driving force of the electric motor. Electric vehicles include not only electric vehicles, but also hybrid vehicles and fuel cell vehicles.

[0009] FIG. 1 is a block diagram showing the main configuration of an electric vehicle 10 for implementing a vehicle drive control method according to this embodiment.

[0010] As shown in the figure, an electric vehicle 10 of this embodiment includes a drive motor 2, an inverter 3 that controls the drive motor 2, a high-voltage battery 4, and a controller 50. The inverter 3 is connected to the high-voltage battery 4, and power charged in the high-voltage battery 4 is supplied to the drive motor 2 via the inverter 3.

[0011] The drive motor 2 is configured by a three-phase synchronous motor or the like, and functions as a drive source for the electric vehicle 10. The drive motor 2 is connected to wheels 7 via a drive shaft 5 and an axle 6.

[0012] The inverter 3 is a power conversion device that converts DC power output from the high-voltage battery 4 into AC power and supplies it to the drive motor 2 when driving the drive motor 2. In particular, the inverter 3 includes a power module for driving the motor. Furthermore, the inverter 3 converts a torque command value T ＊＊ ｍ The power module (each switching element) is operated using the input, and the torque command value T ＊＊ ｍThe drive motor 2 is supplied with electric power according to the above.

[0013] The high-voltage battery 4 is a DC power supply that functions as a drive power source for the drive motor 2. For example, the high-voltage battery 4 is configured as an in-vehicle battery such as a lithium-ion secondary battery.

[0014] The electric vehicle 10 is also provided with a parking lock mechanism 8 that mechanically locks the rotation of the drive shaft 5 of the wheels 7. For example, a lock pin mechanically protrudes and fits into a predetermined position on a gear member that rotates together with the drive shaft 5, restricting the rotation of the gear member (rotation of the drive shaft 5), and releasing the protrusion of the lock pin releases the rotation of the gear member (rotation of the drive shaft 5).

[0015] Furthermore, when the shift lever 9 is operated to the parking position (when the shift range is in the parking range), the parking lock mechanism 8 is electrically activated to mechanically lock the rotation of the drive shaft 5. This allows the electric vehicle 10 to be maintained in a stopped state even if the driver stops the electric vehicle 10 on an inclined road such as a slope and releases the operation of the brake pedal 11.

[0016] The electric vehicle 10 also includes a shift position sensor 21 for detecting a shift range, a brake stroke sensor 22 for detecting an operation amount (braking force) of the brake pedal 11, and a longitudinal acceleration G acting on the electric vehicle 10. ｆｒ the G sensor 23 that detects the rotation speed of the drive motor 2 (motor rotation speed ω ｍ and an accelerator pedal position sensor 25 that detects the amount of operation of an accelerator pedal (not shown) (accelerator pedal position APO). The detected values ​​obtained by these various sensors are output to a controller 50.

[0017] The controller 50 controls each part of the electric vehicle 10 based on various programs stored in a storage unit (not shown). In particular, the controller 50 is configured with one or more computers, such as a VCM (Vehicle Control Module) and a computer for realizing a so-called VDC (Vehicle Dynamics Control) function.

[0018] In the electric vehicle 10 having the above configurations, when the parking lock mechanism 8 is activated while the vehicle is stopped on a slope, the wheels 7 are mechanically locked, but a torsional torque is generated in the drive shaft 5 due to a rotational force generated in accordance with the slope θ. For example, when the electric vehicle 10 is stopped on a downhill slope in the parking lock state, a forward rotational force is generated in the drive shaft 5, generating a torsional torque. On the other hand, because the rotation of the drive shaft 5 is restricted by the parking lock mechanism 8, a torsional torque is accumulated in the drive shaft 5.

[0019] For this reason, when the parking lock is released when starting the electric vehicle 10, the torsional torque accumulated in the drive shaft 5 is suddenly released (the drive shaft 5 is released from torsion), causing an unintended torque fluctuation (shock). In contrast, in this embodiment, under the control of the controller 50, the output torque of the drive motor 2 (hereinafter referred to as the "motor torque T ｍ More specifically, the controller 50 corrects the quantities (hereinafter referred to as "first gradient estimated value tanθ") that are determined by different systems (different parameters and / or calculation algorithms) but indicate the same gradient θ of the road. Ａ " and "second gradient estimate tanθ Ｂ Only when these satisfy a predetermined condition (first control permission condition), shock suppression processing is executed to reduce the shock that occurs when the parking lock is released. In particular, in the shock suppression processing, the basic torque command value (a third torque command value T ＊ ｍ３ ) instead of the shock suppression torque command value T ＊ ｍｃ is set to operate the drive motor 2. Details of the control by the controller 50 will be described below.

[0020] 2 is a block diagram showing a detailed configuration of the controller 50. As shown in the figure, the controller 50 has a first torque command value calculation unit 52, an FB torque calculation unit 54, a disturbance torque calculation unit 56, an adder 57, a comparator 58, a first gradient calculation unit 60, a second gradient calculation unit 62, a first control permission determination unit 64, a second control permission determination unit 65, and a torque output unit 66.

[0021] The first torque command value calculation unit 52 calculates the torque command value by calculating the accelerator opening APO and the motor rotation speed ω ｍ is input, and the first torque command value T ＊ ｍ１ Specifically, the first torque command value calculation unit 52 calculates the accelerator opening APO and the motor rotation speed ω by referring to a predetermined accelerator opening-torque table. ｍ to the first torque command value T ＊ ｍ１ In the accelerator opening-torque table of this embodiment, the larger the accelerator opening APO or the motor rotation speed ω ｍ The torque is set so that the smaller the accelerator opening APO is, the larger the torque becomes. Also, when the accelerator opening APO is 0 (fully closed), the motor torque T ｍ This allows the electric vehicle 10 to accelerate, decelerate, or stop simply by operating the accelerator pedal.

[0022] The FB torque calculation unit 54 calculates the motor rotation speed ω ｍ is used as an input, and a feedback torque T ω In particular, the FB torque calculation unit 54 calculates the motor rotation speed ω ｍ is multiplied by a negative gain to obtain the feedback torque T ω The negative gain is calculated as follows: ｍ The larger the motor rotation speed ω is, the smaller the value (the larger the absolute value). ｍ The greater the vehicle speed, the greater the feedback torque T ω becomes a small value (the regenerative braking force becomes large).

[0023] The disturbance torque calculation unit 56 calculates the motor rotation speed ω ｍ and torque command value T ＊＊ ｍ (hereinafter referred to as the previous torque command value T ＊＊ ｍ_ｚ ") is input, and the disturbance torque estimate T ｄ More specifically, the disturbance torque calculation unit 56 calculates the motor rotation speed ω ｍ , the motor rotation speed ω ｍ From the motor torque T ｍ The first torque estimation value is calculated by applying a transfer characteristic to the motor rotation speed ω and a predetermined low-pass filter process. ｍ From the motor torque T ｍ The transmission characteristics to the previous torque command value T ＊＊ ｍ_ｚ Further, the disturbance torque calculation unit 56 subtracts the first torque estimation value from the second torque estimation value to obtain a disturbance torque estimation value T ｄ Ask for.

[0024] Here, possible disturbances include air resistance, modeling errors due to variations in vehicle mass M caused by the number of occupants and the load, tire rolling resistance, and road surface gradient resistance. The disturbance factors vary depending on the driving conditions of the electric vehicle 10, but the dominant disturbance factor when the vehicle is about to come to a stop is gradient resistance. That is, the disturbance torque estimated value T calculated as above ｄ can be regarded as a quantity that uniquely indicates the magnitude of the gradient θ of the road when the electric vehicle 10 is about to stop.

[0025] The adder 57 calculates the feedback torque T ω and the estimated disturbance torque T ｄ The second torque command value T ＊ ｍ２ is calculated and output to the comparator 58. That is, the second torque command value T ＊ ｍ２ is the motor rotation speed ω ｍ As the vehicle speed approaches 0, the estimated disturbance torque T ｄA profile that approaches (converges to) is taken.

[0026] The comparator 58 detects the first torque command value T ＊ ｍ１ and the second torque command value T ＊ ｍ２ are input, and the larger of these values ​​is used as the third torque command value T ＊ ｍ３ That is, the third torque command value T ＊ ｍ３ (basic torque command value) is the first torque command value T ＊ ｍ１ (Accelerator opening APO and motor rotation speed ω ｍ In a scene where the disturbance torque estimation value T ｄ The second torque command value T ＊ ｍ２ is the third torque command value T ＊ ｍ３ Therefore, when the electric vehicle 10 is stopped, the stopped state of the electric vehicle 10 can be maintained against the gradient even if the accelerator opening APO is zero. On the other hand, when the electric vehicle 10 is running normally (other than when it is about to stop), the first torque command value T ＊ ｍ１ is the third torque command value T ＊ ｍ３ Therefore, the desired motor torque T according to the accelerator opening APO and the vehicle speed is ｍ can be output.

[0027] The first gradient calculation unit 60 calculates the longitudinal acceleration G ｆｒ is used as an input, and the first gradient estimate tanθ Ａ In particular, the first gradient calculation unit 60 calculates the longitudinal acceleration G ｆｒ , the gravitational acceleration g, and the gradient θ of the road. ｆｒ to the first gradient estimate tanθ Ａ The longitudinal acceleration G detected by the G sensor 23 is calculated. ｆｒ In order to extract only the component due to the gradient θ from the vehicle speed, the longitudinal acceleration component due to the running of the electric vehicle 10 is calculated from the vehicle speed detected separately, and the longitudinal acceleration Gｆｒ The first gradient estimated value tanθ is calculated based on the value obtained by removing the longitudinal acceleration component from Ａ That is, the first gradient estimate tanθ may be calculated. Ａ is the motor rotation speed ω based on the detection value of the G sensor 23. ｍ This is a suggested amount of the gradient θ that is calculated without depending on the parameters of the motor control system, including

[0028] The second gradient calculation unit 62 calculates the disturbance torque estimated value T ｄ is used as an input to obtain the second gradient estimate tanθ Ｂ More specifically, the second gradient calculation unit 62 calculates the disturbance torque estimated value T ｄ is multiplied by a predetermined unit conversion gain to obtain the second gradient estimate tanθ Ｂ That is, the second gradient estimate tanθ is calculated. Ｂ is the motor rotation speed ω ｍ The gradient θ is an indication of the gradient θ calculated based on the above and other factors, without relying on the detection value of the G sensor 23.

[0029] The first control permission determination unit 64 determines the first gradient estimated value tanθ Ａ and the second gradient estimate tanθ Ｂ is input, and a first control permission flag f1 is set, which indicates whether or not the shock suppression process can be executed.

[0030] 3 is a flowchart showing the details of the process (first control permission determination process) executed by the first control permission determination unit 64. Note that each process shown in FIG. 3 is repeatedly executed at a predetermined calculation cycle.

[0031] As shown in the figure, the first control permission determination unit 64 first calculates the first gradient estimated value tanθ Ａ is compared with a predetermined threshold value α (step S110). Here, the threshold value α is set to an appropriate value from the viewpoint of determining whether the gradient θ of the road on which the electric vehicle 10 is traveling is large enough that the shock generated when the parking lock is released cannot be ignored. Although not limited to a specific numerical value, the threshold value α can be set to, for example, 1% to 10% (particularly, 5% or less).

[0032] Then, the first control permission determination unit 64 calculates the first gradient estimated value tanθ ＡIf it is determined that the difference is equal to or less than the threshold value α, the first control permission flag f1 is set to “0” (OFF), and the process ends (Yes in step S110 and step S130). That is, in this case, the shock that occurs when the parking lock is released is negligibly small, so the execution of the shock suppression process is not permitted.

[0033] On the other hand, the first control permission determination unit 64 determines the first gradient estimated value tanθ Ａ exceeds the threshold value α, the first gradient estimate tanθ Ａ and the second gradient estimate tanθ Ｂ Difference of | tanθ Ａ -tan θ Ｂ is compared with a predetermined threshold value β (No in step S110 and step S120).

[0034] Here, the threshold value β is set to a value that is large enough to suspect the occurrence of some abnormality. Ａ and the second gradient estimate tanθ Ｂ The threshold value β is set to an appropriate value from the viewpoint of determining whether or not the values ​​deviate from each other. Although not limited to a specific numerical value, the threshold value β can be set within a range of several percent to 10%, for example.

[0035] As described above, the first gradient estimate tanθ Ａ and the second gradient estimate tanθ Ｂ are determined by different systems (different parameters and / or calculation algorithms), but both are quantities that indicate the gradient θ of the road on which the electric vehicle 10 is traveling. Therefore, if these values ​​significantly deviate from each other, it can be assumed that some abnormality has occurred in the various sensors or in the gradient estimation calculation. Therefore, the determination in step S120 (first gradient estimated value tanθ Ａ and the second gradient estimate tanθ Ｂ Through this comparison, it is possible to accurately detect the occurrence of an abnormality that requires suspension of the shock suppression process.

[0036] Then, the first control permission determination unit 64 calculates the difference |tanθ Ａ -tan θ ＢIf it is determined that | exceeds the threshold value β, the first control permission flag f1 is set to "0" (OFF) and the process ends (Yes in step S120 and step S130). In other words, in this case, since it is estimated that some abnormality has occurred, the execution of the shock suppression process is not permitted.

[0037] On the other hand, the first control permission determination unit 64 calculates the difference |tanθ Ａ -tan θ Ｂ If it is determined that | is equal to or less than the threshold value β, the first control permission flag f1 is set to "1" (ON) and the process ends (No in step S120 and step S140). That is, in this case, it is estimated that the shock that occurs when the parking lock is released is large and that no abnormality has occurred, so the execution of the shock suppression process is permitted.

[0038] Returning to FIG. 2, the second control permission determination unit 65 determines whether the first control permission flag f1 and the detection signal of the brake stroke sensor 22 (hereinafter referred to as the "brake signal S ｂ "), and the detection signal of the shift position sensor 21 (hereinafter referred to as "range signal S ｒ ") is input, and a second control permission flag f2 is set, which indicates whether or not the shock suppression process can be performed.

[0039] FIG. 4 is a flowchart showing the details of the process (second control permission determination process) executed by the second control permission determination unit 65.

[0040] As shown in the figure, the second control permission determination unit 65 first refers to the value of the first control permission flag f1 set by the first control permission determination unit 64 (step S210). If the second control permission determination unit 65 determines that the first control permission flag f1 is not "1" (is "0"), it ends this process (No in step S210).

[0041] On the other hand, when the second control permission determination unit 65 determines that the first control permission flag f1 is "1", the range signal S ｒ The currently selected shift range is determined by referring to the value of the shift range selection register (Yes in step S210 and step S220).

[0042] If the second control permission determination unit 65 determines that the currently selected shift range is other than the parking range (P range) (i.e., if it determines that the currently selected shift range is the D range, R range, or N range), it sets the second control permission flag f2 to "0" (step S240) and ends this process. In other words, in this case, the parking lock mechanism 8 is not activated and the shock suppression process is not necessary, so the execution of the shock suppression process is not permitted.

[0043] On the other hand, when the second control permission determination unit 65 determines that the currently selected shift range is the P range, it outputs the brake signal S ｂ The braking force B determined based on the above equation is compared with a predetermined determination value γ[θ, M] (step S230).

[0044] Here, the judgment value γ[θ,M] is set to an appropriate value from the viewpoint of determining whether a braking force B is applied that is sufficient to keep the electric vehicle 10 stationary on a sloped road. In particular, the judgment value γ[θ,M] is set as a function of the slope θ and the vehicle mass M (in particular, a variable value that increases as the slope θ or the vehicle mass M increases). Furthermore, the slope θ that determines the judgment value γ[θ,M] is determined by multiplying the first slope estimated value tanθ by the slope θ. Ａ and / or the second gradient estimate tanθ Ｂ , preferably the first gradient estimate tanθ Ａ Furthermore, the vehicle mass M for determining the determination value γ[θ, M] can be determined by a known value according to the specifications of the electric vehicle 10 or a mass estimated value obtained by a known vehicle weight estimation method. In particular, the first gradient estimated value tanθ Ａ , vehicle mass M, and the judgment value γ[θ, M] are prepared in advance, and the vehicle mass M and the first gradient estimated value tanθ calculated by the first gradient calculation unit 60 are used. Ａ It is preferable to adopt a logic for determining the judgment value γ[θ, M] by applying the above to the map.

[0045] If the second control permission determination unit 65 determines that the braking force B is equal to or greater than the determination value γ[θ, M], it sets the second control permission flag f2 to "1" (ON) and terminates this process (Yes in step S230 and step S250). On the other hand, if the second control permission determination unit 65 determines that the braking force B is less than the determination value γ[θ, M], it sets the second control permission flag f2 to "0" (OFF) and returns to the determination in step S220 (No in step S230 and step S220). This makes it possible to permit the execution of the shock suppression process only when the braking force B is large enough to maintain the electric vehicle 10 stopped on a sloped road.

[0046] Returning to FIG. 2, the torque output unit 66 outputs the third torque command value T ＊ ｍ３ , a first control permission flag f1, a second control permission flag f2, and a brake signal S ｂ , range signal S ｒ , and a parking lock signal S indicating the operating state of the parking lock mechanism 8. ｐ The torque command value T of the drive motor 2 is calculated by referring to ＊＊ ｍ is determined and output to the inverter 3.

[0047] FIG. 5 is a flowchart showing the details of the process (torque output process) executed by the torque output unit 66.

[0048] As shown in the figure, the torque output unit 66 first refers to the value of the first control permission flag f1 set by the first control permission determination unit 64 and the value of the second control permission flag f2 set by the second control permission determination unit 65 (steps S310, S320).

[0049] When the torque output unit 66 determines that at least one of the first control permission flag f1 and the second control permission flag f2 is not "1", the torque output unit 66 outputs the third torque command value T ＊ ｍ３ Torque command value T ＊＊ ｍ(Step S310 or S320 is No, and Step S380). That is, if execution of the shock suppression process is not permitted in either the first control permission determination process or the second control permission determination process, the torque output unit 66 outputs the third torque command value T ＊ ｍ３ (More specifically, the first torque command value T ＊ ｍ１ or the second torque command value T ＊ ｍ２ ) and then actuates the drive motor 2.

[0050] On the other hand, when the torque output unit 66 determines that both the first control permission flag f1 and the second control permission flag f2 are "1", it outputs the range signal S ｒ and parking lock signal S ｐ , and determines whether or not the shift lever 9 has been operated (whether or not an operation to shift from the P range to another range has been performed) (step S330).

[0051] When a transition operation from the P range to another range occurs, the torque output unit 66 outputs the torque command value T ＊＊ ｍ The shock suppression torque command value T ＊ ｍｃ and output to the inverter 3 (step S340). As a result, the shock suppression torque command value T ＊ ｍｃ Since the above setting is made, it is possible to effectively suppress the shock that occurs when the parking lock is released.

[0052] FIG. 6 shows the shock suppression torque command value T ＊ ｍｃ 1 is a diagram showing an example of a specific manner in which the shock suppression torque command value T ＊ ｍｃ is determined as a variable value that changes at a constant rate toward an upper limit value corresponding to the gradient θ (the larger the gradient θ, the larger the upper limit value). ＊ ｍｃis set to a profile that changes the torque at a constant rate, ＊ ｍｃ It is possible to prevent the occurrence of sudden torque fluctuations (vehicle body vibrations) when the shock suppression torque command value T ＊ ｍｃ The upper limit of the third torque command value T ＊ ｍ３ (In particular, the first torque command value T ＊ ｍ１ ) (the minimum value for suppressing shock). In particular, in this embodiment, the gradient θ and the shock suppression torque command value T ＊ ｍｃ The relationship between the first gradient estimated value tanθ and the second gradient estimated value tanθ is prepared in advance as a table. Ａ and / or the second gradient estimate tanθ Ｂ (More preferably, the first gradient estimate tanθ Ａ ) to obtain an appropriate shock suppression torque command value T ＊ ｍｃ It is preferable to adopt a logic that determines

[0053] Returning to FIG. 5, the torque output unit 66 outputs the range signal S ｒ and / or parking lock signal S ｐ When the torque output unit 66 determines that the range transition is complete, it outputs the brake signal S ｂ , and determines whether the brake pedal 11 is being operated (step S360). That is, the determination in step S360 detects a situation in which the driver releases the brake pedal 11 to allow the electric vehicle 10 to travel after the shift range has been changed from the P range to another range.

[0054] When the torque output unit 66 determines that the brake pedal 11 is not being operated, the torque command value T ＊＊ ｍ The shock suppression torque command value T ＊ ｍｃ to the third torque command value T＊ ｍ３ (In particular, the first torque command value T ＊ ｍ１ ) (Yes in step S360 and step S380).

[0055] That is, when the brake pedal 11 is released and the electric vehicle 10 starts to move, it is estimated that the influence of the torsional torque release that occurs when the parking lock is released has disappeared. Therefore, the shock suppression torque command value T ＊ ｍｃ The output of the motor torque T ｍ is returned to the original value according to the accelerator opening APO, etc. This reduces the shock that occurs when the parking lock is released, while still allowing the torque command value T ＊＊ ｍ is the original third torque command value T ＊ ｍ３ (In particular, the first torque command value T ＊ ｍ１ ) and the shock suppression torque command value T ＊ ｍｃ In this case, it is possible to suppress unintended torque fluctuations that would otherwise occur when the vehicle starts moving while maintaining the torque command value T ＊＊ ｍ When switching, the actual motor torque T ｍ In order to prevent the change in the motor torque T ｍ It is preferable to limit the rate of change (slope) of the

[0056] On the other hand, when the torque output unit 66 determines that the brake pedal 11 is being operated, it waits for a predetermined time and then outputs the torque command value T ＊＊ ｍ The shock suppression torque command value T ＊ ｍｃ to the third torque command value T ＊ ｍ３(No in step S360, step S370, and step S380). Here, the predetermined time is set to an appropriate value, starting from the timing at which the range transition is completed, as the time until the influence of the torsional torque release that occurs when the parking lock is released disappears. Although not limited to a specific numerical value, the predetermined time can be set, for example, between several tens of milliseconds and several hundred milliseconds.

[0057] Therefore, in this embodiment, when the brake pedal 11 is being operated continuously, the shock suppression torque command value T ＊ ｍｃ The output of the motor torque T ｍ is returned to the original value according to the accelerator opening APO, etc. As a result, even in a situation where the brake pedal 11 is being operated continuously (a situation where it is unclear whether the influence of the torsional torque release has disappeared), the shock suppression torque command value T ＊ ｍｃ This allows for a more reliable reduction in the shock that occurs when the parking lock is released.

[0058] In particular, the processing from step S370 to step S380 is executed in a situation where at least the brake pedal 11 is operated and the electric vehicle 10 has not yet started moving. ＊＊ ｍ is the original third torque command value T ＊ ｍ３ (In particular, the first torque command value T ＊ ｍ１ ) and the shock suppression torque command value T ＊ ｍｃ This can suppress unintended torque fluctuations that would otherwise occur when starting while maintaining the torque.

[0059] Next, the control results when the processes described with reference to FIGS. 3 to 5 are executed will be described.

[0060] 7 is a timing chart showing an example of the control results of the vehicle drive control method of this embodiment, assuming that the control mode is under a condition in which the brake pedal 11 is continuously operated.

[0061] As shown, the first gradient estimate tanθ Ａ and the second gradient estimate tanθ Ｂ At time t1 when the difference between the shift lever 9 and the parking lock mechanism 8 is equal to or smaller than the threshold value β, the shock suppression process is permitted based on the logic of the first control permission determination process. Then, from time t2 when the shift lever 9 starts to be operated and the parking lock mechanism 8 starts to be released, to time t3 when the shift range changes from the P range to another range, the shock suppression torque command value T ＊ ｍｃ This sets the motor torque T ｍ will be output.

[0062] Furthermore, after time t3 when the range transition is completed, the torque command value T ＊＊ ｍ is the shock suppression torque command value T ＊ ｍｃ to the third torque command value T ＊ ｍ３ (More specifically, the first torque command value T ＊ ｍ１ ) is switched to. As a result, while the shock at the time of releasing the parking lock is reduced as described above, when the electric vehicle 10 starts thereafter, an appropriate motor torque T ｍ can be output.

[0063] The configuration of the vehicle drive control method of the present embodiment described above and the resulting effects will now be described.

[0064] According to this embodiment, when the parking lock of the electric vehicle 10 is released, the output torque (T ｍ A vehicle drive control method for controlling the vehicle speed is provided.

[0065] In this vehicle drive control method, the longitudinal acceleration G ｆｒ The first gradient estimate tanθ is determined based on Ａ and obtain the rotation state (ω ｍ ) The second gradient estimate tanθ Ｂ Then, the first gradient estimate tanθ is obtained. Ａ and the second gradient estimate tanθ Ｂ satisfies a predetermined first control permission condition (No in step S110 and No in step S120), the output torque (T ｍ ) is used to reduce the shock that occurs when the parking lock is released. ＊ ｍｃ ), and the first gradient estimate tanθ Ａ and the second gradient estimate tanθ Ｂ does not satisfy the first control permission condition, the output torque (T ｍ ) to a predetermined basic torque (T ＊ ｍ３ )

[0066] As a result, in a scene where the parking lock of the electric vehicle 10 is released on a sloped road, the first gradient estimated value tanθ Ａ and the second gradient estimate tanθ Ｂ Based on the above, it is possible to check the conditions (first control permission conditions) suitable for the execution of control (shock suppression processing) to suppress the shock that occurs when the parking lock is released, and then determine whether or not to execute the control. If the first control permission conditions are met, the shock suppression torque (T ＊ ｍｃ ) based on the output torque (T ｍ ) can suppress the shock that occurs when the parking lock is released. On the other hand, when the first control permission condition is not satisfied, the basic torque (T ＊ ｍ３ ) based on the output torque (T ｍ ) can prevent excessive torque from being output.

[0067] In addition, the first control permission condition of this embodiment includes the first gradient estimated value tanθ Ａand the second gradient estimate tanθ Ｂ Difference of | tanθ Ａ -tan θ Ｂ | is equal to or less than a predetermined value (threshold value β).

[0068] As a result, the first control permission condition is set as the first gradient estimated value tanθ Ａ and the second gradient estimate tanθ Ｂ Therefore, in a situation where it is estimated that some abnormality has occurred in the various sensors or in the gradient estimation due to the deviation of these estimated values ​​by more than a certain amount, the shock suppression torque (T ＊ ｍｃ ) is not set, excessive torque output can be more reliably prevented.

[0069] In this embodiment, the first gradient estimated value tanθ Ａ and the second gradient estimate tanθ Ｂ If the first control permission condition is satisfied (Yes in step S210), the selected shift range and the brake braking force B based on the brake operation are referenced to determine whether a predetermined second control permission condition is satisfied (No in step S220 and No in step S230). If the second control permission condition is satisfied, the output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃ In particular, the second control permission condition includes that the selected shift range is the parking range and that the braking force B is equal to or greater than a predetermined determination value γ[θ, M].

[0070] As a result, the first gradient estimate tanθ Ａ and the second gradient estimate tanθ Ｂ On the assumption that the first control permission condition based on the above is satisfied, in a situation where the shift range is in the P range and a brake braking force B based on a brake operation of a certain level or more is obtained (a situation where the second control permission condition is satisfied), the output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃIn other words, the shock suppression process can be executed in a spot manner when necessary, thereby suppressing the shock that occurs when the parking lock is released and avoiding unintended torque fluctuations.

[0071] Furthermore, in this embodiment, when the second control permission condition is satisfied, it is determined whether or not a transition operation from the parking range to another range has occurred, and if a transition operation has occurred, the output torque (T ｍ ) to the basic torque (T ＊ ｍ３ ) to shock suppression torque (T ＊ ｍｃ ) and output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃ ) and then it is determined whether the shift range transition is complete. When the shift range transition is complete, it is determined whether a brake operation is being performed. If it is determined that a brake operation is being performed, the output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃ ) to the basic torque (T ＊ ｍ３ )

[0072] This allows the system to properly detect a situation where the brake pedal 11 is released and the electric vehicle 10 starts to move (a situation where the influence of the torsional torque release that occurs when the parking lock is released disappears), and calculates the output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃ ) to the basic torque (T ＊ ｍ３ ) can be returned to the shock suppression torque command value T ＊ ｍｃ This can suppress unintended torque fluctuations caused by maintaining the torque.

[0073] In this embodiment, when it is determined that the brake operation is not being performed, the output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃ ) to the basic torque (T＊ ｍ３ )

[0074] This allows the system to properly detect the time that has passed since the shift range transition was completed, during which the influence of the torsional torque release that occurs when the parking lock is released remains, and calculate the output torque (T ｍ ) to the shock suppression torque (T ＊ ｍｃ ) to the basic torque (T ＊ ｍ３ ) can be returned to the shock suppression torque command value T ＊ ｍｃ This can suppress unintended torque fluctuations caused by maintaining the torque.

[0075] The first gradient estimate tanθ Ａ is the detection value of the G sensor 23 (G ｆｒ ) and the second gradient estimate tanθ Ｂ is the output torque (T ｍ ) feedback value (T ＊＊ ｍ_ｚ ) and motor rotation speed ω ｍ It is preferable to calculate it based on the following formula.

[0076] This allows for a specific manner to be realized for determining two estimates that suggest the same gradient θ.

[0077] Furthermore, in this embodiment, a controller 50 is provided that functions as a vehicle drive control device suitable for executing the above-described vehicle drive control method.

[0078] The controller 50 controls the longitudinal acceleration G ｆｒ The first gradient estimate tanθ is determined based on Ａ a first gradient estimation value acquisition unit (60) that acquires the rotation state (ω ｍ ) The second gradient estimate tanθ Ｂ a second gradient estimate value acquisition unit (62) that acquires a first gradient estimate value tanθ Ａ and the second gradient estimate tanθ Ｂ satisfies a predetermined first control permission condition (No in step S110 and No in step S120), the output torque (Tｍ ) is used to reduce the shock that occurs when the parking lock is released. ＊ ｍｃ ), and a shock suppression torque setting unit (64, 66) that sets the first gradient estimated value tanθ Ａ and the second gradient estimate tanθ Ｂ does not satisfy the first control permission condition, the output torque (T ｍ ) to a predetermined basic torque (T ＊ ｍ３ and a basic torque setting unit (64, 66) for setting the basic torque to the

[0079] The processing procedures shown in each of the above-described embodiments are examples for realizing each embodiment, and the order of some of the processing procedures may be changed within the scope that allows each embodiment to be realized, and some of the processing procedures may be omitted or other processing procedures may be added.

[0080] Furthermore, each process shown in each embodiment is executed based on a program for causing a computer to execute each processing procedure, and therefore each embodiment can also be understood as an embodiment of a program that realizes the function of executing each process, or a recording medium that stores the program.

[0081] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A vehicle drive control method for controlling the output torque of a drive motor mounted on an electric vehicle when the parking lock of the electric vehicle is released, the vehicle drive control method comprising: obtaining a first gradient estimation value determined based on longitudinal acceleration of the electric vehicle; obtaining a second gradient estimation value determined based on the rotational state of the drive motor; if the first gradient estimation value and the second gradient estimation value satisfy a predetermined first control permission condition, setting the output torque to a shock suppression torque for suppressing a shock that occurs when the parking lock is released; and if the first gradient estimation value and the second gradient estimation value do not satisfy the first control permission condition, setting the output torque to a predetermined basic torque.

2. A vehicle drive control method according to claim 1, wherein the first control permission condition includes a condition that the difference between the first gradient estimated value and the second gradient estimated value is equal to or less than a predetermined value.

3. A vehicle drive control method as described in claim 1, wherein, when the first gradient estimated value and the second gradient estimated value satisfy the first control permission condition, a determination is made as to whether a predetermined second control permission condition is satisfied by referring to the selected shift range and the braking force based on brake operation, and if the second control permission condition is satisfied, the output torque is set to the shock suppression torque, and the second control permission condition includes the selected shift range being a parking range and the braking force being equal to or greater than a predetermined judgment value.

4. A vehicle drive control method as described in claim 3, wherein, when the second control permission condition is satisfied, it is determined whether or not a transition operation from the parking range to another range has been performed, and when the transition operation has been performed, the output torque is switched from the basic torque to the shock suppression torque, and with the output torque set to the shock suppression torque, it is determined whether or not the transition of the shift range has been completed, and when the transition of the shift range has been completed, it is determined whether or not the brake operation has been performed, and when the brake operation has been performed, the output torque is returned from the shock suppression torque to the basic torque.

5. A vehicle drive control method according to claim 4, wherein, when it is determined that the brake operation is not being performed, the output torque is returned from the shock suppression torque to the basic torque after waiting for a predetermined time.

6. A vehicle drive control method according to any one of claims 1 to 5, wherein the first gradient estimated value is calculated based on a detection value of a longitudinal G sensor, and the second gradient estimated value is calculated based on a feedback value of the output torque and a detection value of the motor rotation speed.

7. A vehicle drive control device that controls the output torque of a drive motor mounted on an electric vehicle when the parking lock of the electric vehicle is released, comprising: a first gradient estimation value acquisition unit that acquires a first gradient estimation value determined based on longitudinal acceleration of the electric vehicle; a second gradient estimation value acquisition unit that acquires a second gradient estimation value determined based on the rotational state of the drive motor; a shock suppression torque setting unit that sets the output torque to a shock suppression torque for suppressing a shock that occurs when the parking lock is released, when the first gradient estimation value and the second gradient estimation value satisfy a predetermined first control permission condition; and a base torque setting unit that sets the output torque to a predetermined base torque, when the first gradient estimation value and the second gradient estimation value do not satisfy the first control permission condition.

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