Electric vehicle control method and electric vehicle control device

Abstract

The present invention relates to an electric vehicle control method in which the size of the regenerative braking force produced by an electric motor is switched according to a driver-originated mode setting. With this method of controlling an electric vehicle, on the basis of the accelerator operation amount, electric motor rpm, and mode setting, a base-torque target value for the electric motor is set. Then, on the basis of the base-torque target value and the rolling resistance, determination is made as to whether the electric vehicle will accelerate owing to insufficient regenerative braking force with respect to the rolling resistance, and if it is determined that the electric vehicle will accelerate, regardless of the driver-originated mode setting, the base-torque target value is corrected so as to augment the regenerative braking force.

Description

Control method for electric vehicle and control device for electric vehicle

[0001] The present invention relates to a control method and a control device for an electric vehicle.

[0002] JP6135775B2 discloses a control method for an electric vehicle in which a disturbance torque is estimated and a torque command value for an electric motor is corrected in accordance with the estimated disturbance torque.

[0003] In some electric vehicles, the driver can set or adjust the magnitude of the regenerative braking force generated by the electric motor, i.e., the effectiveness of the regenerative braking. However, if the regenerative braking force is reduced, the electric vehicle may accelerate against the driver's will.

[0004] Specifically, when the regenerative braking force is reduced, the driver typically expects the vehicle speed to be maintained or to decelerate gradually. Therefore, even if the regenerative braking force is reduced, the driver does not expect the electric vehicle to accelerate without depressing the accelerator pedal. However, for example, when the road surface changes from flat to downhill while the driver is traveling with the accelerator pedal released and the regenerative braking force is reduced, even if the vehicle speed was maintained or decelerated on the flat road, the regenerative braking force may be insufficient when the electric vehicle enters the downhill road, causing it to accelerate. For a driver who still expects the regenerative braking force to maintain or decelerate the vehicle speed, simply reducing the regenerative braking force may result in unexpected acceleration.

[0005] The present invention aims to provide a control method for an electric vehicle in which the driver can set the magnitude of the regenerative braking force, and a control device for the electric vehicle, which can suppress unexpected acceleration when the regenerative braking force is reduced.

[0006] One aspect of the present invention is a control method for an electric vehicle that switches the magnitude of regenerative braking force generated by an electric motor in accordance with a mode setting by a driver. In this control method for an electric vehicle, a basic torque target value for the electric motor is set based on an accelerator operation amount, a rotational speed of the electric motor, and the mode setting. Then, based on the basic torque target value and running resistance, it is determined whether the electric vehicle will accelerate due to insufficient regenerative braking force relative to the running resistance. If it is determined that the electric vehicle will accelerate, the basic torque target value is corrected to increase the regenerative braking force, regardless of the mode setting by the driver.

[0007] FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle. FIG. 2 is a flowchart showing basic control aspects of an electric vehicle. FIG. 3 is an explanatory diagram showing a dynamic model of an electric vehicle. FIG. 4 is a block diagram showing a configuration of a controller. FIG. 5 is a graph showing an overview of a torque table. FIG. 6 is a block diagram showing a configuration of a running resistance estimator. FIG. 7 is a block diagram showing a configuration of a base torque target value correction unit. FIG. 8 is a graph showing changes in rotation speed, etc. in a comparative example. FIG. 9 is a graph showing changes in rotation speed, etc. in this embodiment. FIG. 10 is an explanatory diagram showing an acceleration region. FIG. 11 is a block diagram showing a configuration of a controller in a second embodiment. FIG. 12 is a block diagram showing a configuration of a base torque target value correction unit in the second embodiment. FIG. 13 is a graph showing changes in rotation speed, etc. in the second embodiment. FIG. 14 is a flowchart relating to a method of setting a correction mode according to a second modified example. FIG. 15 is a flowchart of control according to a third embodiment.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] [First embodiment] Fig. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle 100. As shown in Fig. 1, the electric vehicle 100 is a hybrid vehicle or an electric automobile that uses an electric motor 10 as all or part of a drive source and a braking source. Specifically, in addition to the electric motor 10, the electric vehicle 100 includes a battery 11, an inverter 12, and a controller 13.

[0010] The electric motor 10 is configured by, for example, a three-phase AC synchronous motor, and is driven by power supplied from a battery 11. The torque T ｍ is transmitted to the drive wheels 16 via the reducer 14 and the drive shaft 15, generating a driving force for the electric vehicle 100. On the other hand, when the electric motor 10 is rotated by the drive wheels 16, the electric motor 10 generates a regenerative braking force for the electric vehicle 100.

[0011] The magnitude of the regenerative braking force generated by the electric motor 10 can be set (adjusted) by the driver. In this embodiment, the magnitude of the regenerative braking force is set or changed as appropriate using, for example, a paddle switch (not shown) provided on the steering wheel. In this embodiment, a plurality of operation modes with different magnitudes of regenerative braking force are provided in advance, and the driver can set the operation mode of the electric motor 10 (hereinafter referred to as mode setting S) using the paddle switch. ｍｏｄｅ By switching between these two modes, the magnitude of the regenerative braking force can be changed.

[0012] Specifically, the electric vehicle 100 operates in a coasting mode (S ｍｏｄｅ = 0), weak regeneration mode (S ｍｏｄｅ = 1), and strong regeneration mode (S ｍｏｄｅ = 2). ｍｏｄｅ = 0) is an operating mode that does not generate a regenerative braking force substantially and simulates coasting. ｍｏｄｅ The strong regeneration mode (S = 1) is an operation mode that generates a regenerative braking force and actively supports braking of the electric vehicle 100 and recovery of regenerative power. ｍｏｄｅ =2) is an operation mode that generates a regenerative braking force greater than that in the weak regeneration mode, thereby providing particularly strong support for braking of the electric vehicle 100 and recovery of regenerative power.

[0013] The battery 11 is a DC power source that supplies power to the electric motor 10. The battery 11 is rechargeable, and can be charged, for example, by regenerative power generated by the electric motor 10. The battery 11 is connected to the electric motor 10 via an inverter 12. The DC voltage V output by the battery 11 isｄｃ (not shown) can be obtained appropriately using, for example, a voltage sensor (not shown).

[0014] The inverter 12 converts DC power from the battery 11 into AC power and supplies it to the electric motor 10. During regeneration, the inverter 12 converts AC power (regenerated power) generated by the electric motor 10 into DC power and inputs it to the battery 11.

[0015] The controller 13 is a control device programmed to comprehensively control each part of the electric vehicle 100, and is configured by, for example, one or more computers. Specifically, the controller 13 generates a PWM (Pulse Width Modulation) signal based on vehicle variables. The controller 13 then drives the inverter 12 based on the PWM signal, thereby controlling the operation of the electric motor 10.

[0016] The vehicle variables used by the controller 13 are, for example, the accelerator operation amount θ, the mode setting S ｍｏｄｅ , brake switch signal SW Ｂ , the rotor phase α [rad] (electrical angle) of the electric motor 10, the current flowing through each phase of the electric motor 10 (hereinafter referred to as the three-phase current i ｕｖｗ ), and the DC voltage V of the battery 11 ｄｃ The accelerator operation amount θ is a parameter that indicates the operation amount of the accelerator pedal, and is acquired by a sensor (not shown). Ｂ is a signal output by a brake switch (not shown) that detects the operation of the friction brake pedal. ＷＢ For example, when the brake pedal is depressed, Ｂ = 1), and when the brake pedal is not operated, it is turned off (SW Ｂ The rotor phase α is detected appropriately using a rotation sensor 17 configured by an encoder, a resolver, or the like. The three-phase current i ｕｖｗ is suitably detected by the current sensor 18.

[0017] The controller 13 may acquire other vehicle information through calculations. In this embodiment, the controller 13 calculates the rotational speed ω of the electric motor 10 using the rotor phase α of the electric motor 4. ｍ In this embodiment, the rotation speed ω is used as a parameter representing the rotation state of the electric motor 10. ｍ The controller 13 uses the rotation speed ω ｍ By converting the units, the rotation speed N ｍ Therefore, in this embodiment, the controller 13 calculates the rotation speed ω as a parameter representing the rotation state of the electric motor 10. ｍ Alternatively, the rotational speed ω ｍ At the same time, the rotation speed N ｍ may also be used.

[0018] 2 is a flowchart showing basic control aspects of the electric vehicle 100. As shown in FIG. 2, the controller 13 executes an input process S11, a torque command value calculation process S12, a current command value calculation process S13, and a current control process S14.

[0019] The input process S11 is a process of receiving input of vehicle variables and calculating, as necessary, vehicle variables to be used in the torque command value calculation process S12 and subsequent processes. In this embodiment, the controller 13 receives input of the accelerator operation amount θ, the mode setting S by the driver, and the vehicle variables to be used in the torque command value calculation process S12 and subsequent processes. ｍｏｄｅ , brake switch signal SW Ｂ , rotor phase α, and DC voltage V ｄｃ The controller 13 also obtains the rotational speed ω of the electric motor 10 by differentiating the rotor phase α. ｍ Calculate.

[0020] The torque command value calculation process S12 calculates the torque T that the electric motor 10 should actually generate. ｍ (hereinafter, the torque command value T ｍ１ ＊ This is the process of calculating the

[0021] Specifically, the controller 13 controls the accelerator operation amount θ and the rotation speed ω of the electric motor 10. ｍ , and mode setting Sｍｏｄｅ Based on this, the basic torque target value T ｍ０ ＊ Set the basic torque target value T ｍ０ ＊ is the torque T that the electric motor 10 should output. ｍ The controller 13 also estimates or detects the running resistance R of the electric vehicle 100. The controller 13 then determines the basic torque target value T ｍ０ ＊ By correcting the torque command value T ｍ１ ＊ Calculate the following.

[0022] At this time, the controller 13 calculates the basic torque target value T ｍ０ ＊ and the running resistance R, it is determined whether the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the running resistance R. Then, when it is determined that the electric vehicle 100 will accelerate, the controller 13 determines whether the mode setting S ｍｏｄｅ In this way, the controller 13 balances the running resistance R and the regenerative braking force, or makes the regenerative braking force exceed the running resistance R. As a result, the mode setting S by the driver ｍｏｄｅ Whatever the speed of the electric vehicle 100 is, the speed of the electric vehicle 100 is maintained or the electric vehicle 100 is decelerated.

[0023] As described above, the torque command value T ｍ１ ＊ The running resistance R used in the calculation of the above is, for example, the disturbance torque T ｄ Therefore, in this embodiment, the running resistance R can be estimated based on the disturbance torque T ｄ (hereinafter referred to as the disturbance torque estimated value T ｄ However, when the longitudinal acceleration of the electric vehicle 100 is detected by a sensor or the like, the running resistance R may be estimated based on the longitudinal acceleration. Furthermore, when the road surface gradient ψ can be acquired from a navigation system or the like, the running resistance R can also be simply estimated based on the road surface gradient ψ.

[0024] In addition, the controller 13 may adjust the torque command value T calculated in the torque command value calculation process S12 in order to suppress, for example, torsional vibration of the drive shaft 15. ｍ１ ＊ By further correcting the torque command value T, the final torque command value for the electric motor 10 can be set. However, in this embodiment, for the sake of simplicity, a description of the correction related to the vibration damping control and the like will be omitted. Therefore, in this embodiment, the torque command value T ｍ１ ＊ is used as the final torque command value.

[0025] The current command value calculation process S13 calculates the torque command value T ｍ１ ＊ and the rotation speed ω of the electric motor 10 ｍ , and the DC voltage V of the battery 11 ｄｃ In this embodiment, the controller 13 calculates a current command value that determines the current to be passed through the electric motor 10 based on the torque command value T ｍ１ ＊ , rotational speed ω ｍ , and DC voltage V ｄｃ and the current command value in the dq-axis coordinate system (hereinafter referred to as the dq-axis current command value i ｄｑ ＊ The controller 13 has a dq-axis current command value map (not shown) in which the torque command value T ｍ１ ＊ , rotational speed ω ｍ , and DC voltage V ｄｃ The dq-axis current command value i ｄｑ ＊ Calculate the following.

[0026] In the current control process S14, the current flowing through the electric motor 10 is controlled in accordance with the current command value calculated in the current command value calculation process S13. Specifically, the controller 13 controls the three-phase current i ｕｖｗ and the rotor phase α, the dq axis current i ｄｑ Calculate the dq axis current i ｄｑ is the dq axis current command value i ｄｑ ＊The voltage command value for each phase (hereinafter referred to as the three-phase voltage command value V ｕｖｗ ＊ Then, the controller 13 determines the three-phase voltage command value V ｕｖｗ ＊ and DC voltage V ｄｃ The inverter 12 is driven using a PWM signal based on the torque command value T ｍ１ ＊ Torque T according to ｍ As a result, a driving force or a regenerative braking force is generated in the electric vehicle 100.

[0027] 3 is an explanatory diagram showing a dynamic model of the electric vehicle 100. The parameters shown in FIG.

[0028] J ｍ : Inertia of electric motor J ｗ : Inertia of drive wheels M : Mass of vehicle K Ｄ : Torsional rigidity of wheel drive system K ｔ : Coefficient of friction between the drive wheels and the road surface N: Overall gear ratio r: Load radius of the drive wheels ω ｍ : Rotation speed of electric motor T ｍ : Torque of electric motor T Ｄ : Torque of the drive wheels F: Force applied to the electric vehicle V: Speed ​​of the electric vehicle (vehicle speed) ω ｗ : Angular velocity of the drive wheels

[0029] The following equations of motion (1) to (5) can be derived from the dynamic model of electric vehicle 100 shown in Fig. 4. Note that the symbol "*" in equations (1) to (3) represents a time derivative.

[0030]

[0031] Torque T ｍ from the rotational speed ω ｍ Transfer characteristics G ｐ (s) can be calculated from the above equations of motion (1) to (5) and is expressed by the following equation (6). １ ~a ４ and coefficient b０ ~b ３ is expressed by equations (7) to (14).

[0032]

[0033] The transfer characteristic G shown in the above formula (6) ｐ When the poles and zeros of (s) are examined, they can be approximated to the form shown in the following equation (15). One pole and one zero show very close values. This means that α and β in the following equation (15) show very close values.

[0034]

[0035] Therefore, by performing pole-zero cancellation that approximates α=β in equation (15), the (second-order) / (third-order) transfer characteristic G ｐ Therefore, the torque T ｍ from the rotational speed ω ｍ The reference response up to is the transfer characteristic G ｒ It is represented by (s).

[0036]

[0037] 4 is a block diagram showing the configuration of the controller 13. Here, the configuration relating to the torque command value calculation process S12 is shown, and the illustration and description of the other configurations are omitted.

[0038] As shown in FIG. 4 , the controller 13 includes a basic torque target value setting unit 21 , a running resistance estimator 22 , and a basic torque target value correcting unit 23 .

[0039] The basic torque target value setting unit 21 is configured to set the accelerator operation amount θ and the rotation speed ω of the electric motor 10. ｍ , and the mode setting S by the driver ｍｏｄｅ Based on this, the basic torque target value T ｍ０ ＊ Specifically, the basic torque target value setting unit 21 sets the accelerator operation amount θ and the rotation speed ω ｍ and the basic torque target value T ｍ０ ＊The torque table has a correspondence between the mode setting S and the torque setting S based on an experiment or a simulation. ｍｏｄｅ That is, in this embodiment, the basic torque target value setting unit 21 sets the basic torque target value for each coasting mode (S ｍｏｄｅ = 0), torque table for weak regeneration mode (S ｍｏｄｅ = 1) and the torque table for the strong regeneration mode (S ｍｏｄｅ Therefore, the basic torque target value setting unit 21 has a torque table for the mode setting S ｍｏｄｅ By referring to the torque table corresponding to the accelerator operation amount θ and the rotation speed ω ｍ The basic torque target value T ｍ０ ＊ Set.

[0040] The running resistance estimator 22 estimates the running resistance R. In this embodiment, the rotation speed ω of the electric motor 10 is ｍ and the final torque command value for the electric motor 10 (torque command value T ｍ１ ＊ ) and the disturbance torque estimated value T ｄ That is, the running resistance estimator 22 of this embodiment is a disturbance torque estimator (so-called disturbance observer).

[0041] As described above, the running resistance estimator 22 calculates the disturbance torque estimated value T ｄ The rotation speed ω is used to calculate ^ ｍ is used, but the rotation speed ω ｍ Instead of the above, other parameters correlated with the vehicle speed of the electric vehicle 100 are used to calculate the disturbance torque estimate T ｄ For example, the running resistance estimator 22 can calculate the rotation speed N ｍ or the vehicle speed V itself is used to calculate the disturbance torque estimate T ｄ ^ can be calculated.

[0042] The basic torque target value correction unit 23 corrects the basic torque target value T ｍ０ ＊ Correct the following.

[0043] Specifically, the basic torque target value correction unit 23 determines whether, in a situation (scene) in which a regenerative braking force should be generated, the regenerative braking force is smaller than the running resistance R, and the running resistance R cannot be canceled out by the regenerative braking force, causing the electric vehicle 100 to accelerate due to the running resistance R. In other words, it determines whether the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the running resistance R. A typical example of a scene in which the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the running resistance R is when the mode setting S ｍｏｄｅ In this scene, the electric vehicle 100 enters a downhill road in a state where the regenerative braking force is reduced by changing the braking force.

[0044] Then, when it is determined that the regenerative braking force cannot cancel out the running resistance R and the electric vehicle 100 accelerates in a situation where a regenerative braking force should be generated, the basic torque target value correcting unit 23 corrects the basic torque target value T ｍ０ ＊ By correcting the mode setting S ｍｏｄｅ As a result, the running resistance R is reduced or cancelled out by the increased regenerative braking force. ｍｏｄｅ The regenerative braking force (basic torque target value T ｍ０ ＊ ) is insufficient, the acceleration of the electric vehicle 100 is reduced. As a result, the vehicle speed V of the electric vehicle 100 is maintained, or the electric vehicle 100 begins to decelerate.

[0045] In this embodiment, the basic torque target value correction unit 23 calculates the basic torque target value T ｍ０ ＊ and the estimated disturbance torque T ｄ Based on the above, it is determined whether the electric vehicle will accelerate due to a lack of regenerative braking force relative to the running resistance R.

[0046] In this embodiment, the basic torque target value correction unit 23 corrects the basic torque target value T ｍ０ ＊ and the estimated disturbance torque T ｄ Based on the above, the basic torque target value T ｍ０ ＊Correction torque for (hereinafter referred to as correction torque T ｃ Then, the basic torque target value correction unit 23 calculates the correction torque T ｃ is input to the adder 24, and the basic torque target value T ｍ０ ＊ Correction torque T ｃ As a result, the basic torque target value correction unit 23 adds the basic torque target value T ｍ０ ＊ is corrected, and the torque command value T ｍ１ ＊ Calculate the following.

[0047] 5A and 5B are graphs showing an outline of the torque table. ｍｏｄｅ FIG. 5B is a torque table for the weak regeneration mode (S ｍｏｄｅ 5C is a torque table for the coasting mode (S ｍｏｄｅ 5A to 5C, the line when the accelerator is fully closed, that is, the accelerator operation amount θ is zero (θ=0 / 4), is shown by a thick line. As described above, these torque tables are used in the basic torque target value setting unit 21.

[0048] As shown in FIG. 5A, in the strong regeneration mode, when the electric vehicle 100 is moving forward at a certain speed, the accelerator operation amount θ is equal to or exceeds a predetermined value Th θ When the basic torque target value T ｍ０ ＊ is set to a negative value, and a large regenerative braking force is generated in the electric vehicle 100. Therefore, a driver who has set the operation mode to the strong regenerative mode expects that when the accelerator pedal is released, particularly when the accelerator pedal is released, a strong regenerative braking force will be used to assist in braking the electric vehicle 100 and recovering regenerative power. As can be seen from the figure, the predetermined value Th θ For example, 0 / 4≦Th θ It is set to a value that satisfies <1 / 4.

[0049] As shown in FIG. 5B, in the weak regeneration mode, when the electric vehicle 100 is moving forward at a certain speed, the accelerator operation amount θ is equal to or greater than the predetermined value Thθ When the basic torque target value T ｍ０ ＊ is set to a negative value, and a regenerative braking force is generated in the electric vehicle 100. However, when the basic torque target value T ｍ０ ＊ The absolute value of is smaller than that in the strong regeneration mode. That is, the regenerative braking force generated in the weak regeneration mode is smaller than the regenerative braking force generated in the strong regeneration mode. Therefore, a driver who has set the operation mode to the weak regeneration mode expects the regenerative braking force to relatively gently (moderately) assist the braking of the electric vehicle 100 and the recovery of regenerative power when the driver releases the accelerator pedal, particularly when the driver releases the accelerator pedal.

[0050] As shown in FIG. 5C, in the coasting mode, when the electric vehicle 100 is moving forward at a certain speed, the accelerator operation amount θ is equal to or greater than a predetermined value Th θ When the basic torque target value T ｍ０ ＊ is set to substantially zero. That is, in the coasting mode, when the accelerator operation amount θ is θ When the vehicle speed V is below 1 / 2000, substantially no regenerative braking force or only a very small regenerative braking force is generated, so that when the driver sets the operating mode to the coasting mode, the driver typically expects the electric vehicle 100 to coast and maintain a substantially constant vehicle speed V when the driver releases the accelerator pedal, particularly when the driver releases the accelerator pedal.

[0051] However, for example, when the vehicle enters a downhill road in coasting mode, the regenerative braking force does not work, so even if the accelerator pedal is not being operated, the electric vehicle 100 may accelerate depending on the magnitude of the negative running resistance R due to the gradient. ｍｏｄｅ Since the change of mode setting S simply adjusts the strength of the regenerative braking force, in many cases the driver does not expect the electric vehicle 100 to accelerate even though the accelerator pedal is released (or released). When the electric vehicle 100 starts to accelerate unexpectedly in this way, a typical driver usually ｍｏｄｅThis change causes the driver to step on the brakes without increasing the regenerative braking force. This makes it easier for the driver to switch from the accelerator pedal to the brake pedal. In addition, the use of friction brakes prevents the recovery of regenerative power that would normally be recovered, resulting in a worsening of fuel economy.

[0052] This also applies when switching from the strong regeneration mode to the weak regeneration mode. That is, when switching from the strong regeneration mode to the weak regeneration mode and reducing the regenerative braking force, depending on the magnitude of the negative running resistance R on a downhill road, the electric vehicle 100 may accelerate due to a lack of regenerative braking force. However, it is difficult for an ordinary driver to anticipate this, and when the electric vehicle 100 starts to accelerate, an ordinary driver usually ｍｏｄｅ This change causes the driver to step on the brakes without increasing the regenerative braking force. This makes it more likely that the driver will switch from the accelerator pedal to the brake pedal. This also worsens fuel economy.

[0053] That is, mode setting S ｍｏｄｅ The regenerative braking force adjustment function (especially the regenerative braking force reduction function) by the brake pedal may cause acceleration that does not match the feeling of the average driver. As a result, the driver is more likely to have to change pedals, which is troublesome. It also worsens the fuel economy.

[0054] 6 is a block diagram showing the configuration of the running resistance estimator 22. As shown in FIG. 6, the running resistance estimator 22 includes a first torque estimator 31, a second torque estimator 32, and a subtractor 33.

[0055] The first torque estimation unit 31 uses a vehicle model of the electric vehicle 100 to estimate the rotation speed ω of the electric motor 10. ｍ Based on this, the first torque estimate T ｅｓｔ１ The first torque estimate T ｅｓｔ１ ^ is the torque T that the electric motor 10 actually outputs ｍ Specifically, the first torque estimation unit 31 estimates H(s) / G ｒ (s) is composed of a filter represented by 1 / G ｒ (s) is the torque T ｍ from the rotational speed ω ｍTransfer characteristic G, which represents the reference response up to ｒ H(s) is the inverse characteristic of the transfer characteristic G ｒ It is a band-pass filter configured so that the order is equal to or greater than the difference between the denominator order and the numerator order of (s).

[0056] The second torque estimation unit 32 calculates a second torque estimation value T ｅｓｔ２ The second torque estimate T ｅｓｔ２ ^ is the torque T that the electric motor 10 should output when driven according to the final torque command value. ｍ In this embodiment, the second torque estimator 32 estimates the torque command value T ｍ１ ＊ The second torque estimate T ｅｓｔ２ Specifically, the second torque estimation unit 32 is configured by a band-pass filter H(s).

[0057] The subtraction unit 33 calculates the first torque estimate T ｅｓｔ１ ^ and the second torque estimate T ｅｓｔ２ The difference between the two is the estimated disturbance torque T ｄ That is, the torque command value T ｍ１ ＊ The torque (T ｅｓｔ２ ^) and the actual torque (T ｅｓｔ１ The difference between the torque generated by the disturbance (disturbance torque T ｄ ) is estimated to be

[0058] In this embodiment, the subtraction unit 33 calculates the second torque estimate T ｅｓｔ２ ^ to the first torque estimate T ｅｓｔ１ By subtracting ^, the disturbance torque estimate T ｄ ^ is calculated. Disturbance torque estimate T ｄ ^ comprehensively reflects various disturbances that may act on the electric vehicle 100.

[0059] The main disturbance factor to be considered in this embodiment is running resistance R. The running resistance R includes air resistance, rolling resistance, and grade resistance. Air resistance increases in proportion to the square of the vehicle speed V. Rolling resistance is constant regardless of the vehicle speed V. Grade resistance varies depending on the road gradient ψ. Specifically, grade resistance acts as a positive torque that reduces the driving force on an uphill road (ψ > 0), is zero on a flat road (ψ = 0), and acts as a negative torque that increases the driving force on a downhill road (ψ < 0).

[0060] Disturbance torque estimate T ｄ ^ includes all of these running resistances R. However, if the driver selects the mode setting S ｍｏｄｅ The driving scene in which the regenerative braking force is reduced by changing the estimated disturbance torque T is, for example, a driving scene in which the vehicle speed V is relatively low, such as when the vehicle is about to stop or when coasting. Therefore, the gradient resistance is the dominant disturbance factor. Therefore, in the following, the estimated disturbance torque T ｄ ^ essentially represents the gradient resistance according to the road surface gradient ψ. That is, the disturbance torque estimated value T ｄ ^ is a positive value on an uphill road (T ｄ ^>0), zero on flat roads (T ｄ ^=0), negative value on downhill road (T ｄ ^<0).

[0061] 7 is a block diagram showing the configuration of the basic torque target value correction unit 23. As shown in FIG. 7, the basic torque target value correction unit 23 includes an acceleration determination unit 41 and a correction torque holder 42.

[0062] The acceleration determination unit 41 determines the basic torque target value T ｍ０ ＊ and the estimated disturbance torque T ｄ ^, it is determined whether or not the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the running resistance R. Then, in this embodiment, the acceleration determination unit 41 uses the result of this determination to calculate the correction torque T ｃ It is expressed by the sign and magnitude of

[0063] Specifically, the acceleration determination unit 41 of this embodiment is composed of a torque deviation calculator 43 and a correction torque setter 44 .

[0064] The torque deviation calculator 43 calculates the basic torque target value T ｍ０ ＊ and the estimated disturbance torque T ｄ In this embodiment, the torque deviation calculator 43 calculates the deviation of the basic torque target value T ｍ０ ＊ From the estimated disturbance torque T ｄ The torque deviation ΔT is calculated by subtracting ^.

[0065] The torque deviation ΔT is a criterion for determining whether or not the electric vehicle 100 accelerates due to a lack of regenerative braking force relative to the running resistance R. θ In a situation where a regenerative braking force is to be generated, the basic torque target value T ｍ０ ＊ is the estimated disturbance torque T ｄ When the torque deviation ΔT is positive (ΔT>0), the electric vehicle 100 accelerates due to the running resistance R. On the other hand, when the accelerator operation amount θ is greater than the predetermined value Th θ In a situation where a regenerative braking force is to be generated, the basic torque target value T ｍ０ ＊ is the estimated disturbance torque T ｄ When the torque deviation ΔT is negative (ΔT<0), the electric vehicle 100 is decelerated by the regenerative braking force.

[0066] The correction torque setter 44 sets the correction torque T ｃ Specifically, the correction torque T ｃ The sign of the correction torque T is set to be opposite to the sign of the torque deviation ΔT. In addition, in a scene where the torque deviation ΔT is positive and the electric vehicle 100 accelerates due to the running resistance R, ｃ The absolute value of the torque deviation ΔT is set to be equal to or greater than the absolute value of the torque deviation ΔT. ｍｏｄｅ Even if the regenerative braking force is reduced by changing the accelerator operation amount θ, θ When the regenerative braking force should be generated, the regenerative braking force is increased appropriately, and the running resistance R is cancelled out.

[0067] On the other hand, in a scene where the torque deviation ΔT is zero and the vehicle speed V is maintained, or in a scene where the torque deviation ΔT is negative and the electric vehicle 100 is decelerating, the correction torque T ｃ The absolute value of is set to zero. θ When the regenerative braking force is to be generated, the mode setting S ｍｏｄｅ A regenerative braking force corresponding to the

[0068] Therefore, simply put, the correction torque setter 44 calculates the basic torque target value T based on the torque deviation ΔT. ｍ０ ＊ and running resistance R (disturbance torque estimate T ｄ Based on this, the correction torque T ｃ The amount of increase in the regenerative braking force is determined so that the vehicle speed V of the electric vehicle 100 is maintained or so that the electric vehicle 100 decelerates.

[0069] The correction torque holder 42 maintains the correction torque T ｃ As a result, the regenerative braking force remains increased until the driver detects a specific operation. On the other hand, when the driver detects a specific operation, the correction torque setter 44 sets the correction torque T ｃ This updates (resets) the regenerative braking force. That is, when a specific operation is detected, the regenerative braking force is updated (reset) according to the mode setting S ｍｏｄｅ The regenerative braking force returns to the value according to the

[0070] The specific operation is an explicit operation that changes the driving force or braking force of the electric vehicle 100. Specifically, the specific operation is an increase in the accelerator operation amount θ, an operation of the brake (friction brake), or a change in the mode setting S ｍｏｄｅ This is a change.

[0071] That is, the correction torque T output by the correction torque setter 44 ｃEven if the regenerative braking force T becomes zero, the correction torque holder 42 maintains the correction torque T to increase the regenerative braking force so as to cancel the running resistance R until a specific operation is performed. ｃ (T ｃ However, when an increase in the accelerator operation amount θ is detected, the correction torque holder 42 maintains the correction torque T ｃ Update the brake switch signal S ＷＢ Even when the brake operation is detected by the ｃ Also, update the mode setting S ｍｏｄｅ Even if a change is detected, the correction torque holder 42 ｃ As a result, the regenerative braking force is updated according to the mode setting S ｍｏｄｅ The regenerative braking force returns to the value according to the

[0072] The following describes the operation of the regenerative braking force adjustment control in the electric vehicle 100 configured as described above.

[0073] FIG. 8 shows the rotation speed ω ｍ 10 is a graph showing the transition of the basic torque target value T ｍ０ ＊ is not corrected, and the torque command value T ｍ１ ＊ Specifically, Fig. 8(A) to (F) show examples in which the road surface gradient ψ and the estimated disturbance torque T ｄ ^, Mode setting S ｍｏｄｅ , basic torque target value T ｍ０ ＊ , torque deviation ΔT, and rotation speed ω ｍ Shows.

[0074] In the comparative example, the basic torque target value T ｍ０ ＊ Without correcting the torque command value T ｍ１ ＊ 8E is used as the torque deviation ΔT, and therefore the torque deviation ΔT is not calculated. Therefore, the torque deviation ΔT in FIG. 8E is shown only as a schematic diagram for comparison with the present embodiment. Also, the vehicle speed V of the electric vehicle 100 is calculated by multiplying the rotation speed ω ｍis calculated by multiplying the rotational speed ω by the dynamic radius of the tire and dividing by the final gear ratio. ｍ substantially represents the vehicle speed V.

[0075] As shown in Fig. 8A, it is assumed here that the road surface gradient ψ changes from zero to a negative value. That is, the electric vehicle 100 enters a downhill road from a flat road. At this time, the disturbance torque estimated value T ｄ ^ changes as shown in FIG. 8(B). Specifically, when the electric vehicle 100 is traveling on a flat road, the disturbance torque estimated value T ｄ is zero, but thereafter, when the electric vehicle 100 enters a downhill road, the disturbance torque estimated value T ｄ ^ changes to a negative value according to the road surface gradient ψ. ３ is the time when the electric vehicle 100 enters a downhill road from a flat road.

[0076] On the other hand, here, the driver keeps the accelerator pedal released (θ=0) and sets the mode setting S ｍｏｄｅ Specifically, when the vehicle is traveling on a flat road, the operation mode is changed to the strong regeneration mode (S ｍｏｄｅ = 2) to weak regeneration mode (S ｍｏｄｅ =1), and then enters coasting mode (S ｍｏｄｅ = 0). That is, the scene described here is a scene in which the electric vehicle 100 is decelerated by regenerative braking force without using friction brakes, and then transitions to coasting. Therefore, the driver usually expects that a constant vehicle speed V will be maintained after deceleration. Note that at time t １ is the time when the strong regeneration mode is changed to the weak regeneration mode, and time t ２ is the time when the mode is changed from the weak regeneration mode to the coasting mode.

[0077] Basic torque target value T ｍ０ ＊ is the above mode setting S ｍｏｄｅ Specifically, as shown in FIG. 8(D), the basic torque target value T ｍ０ ＊ The value of the mode setting Sｍｏｄｅ Then, at time t ２ When the mode shifts to the coasting mode, the basic torque target value T ｍ０ ＊ becomes zero, and then the basic torque target value T ｍ０ ＊ is maintained at zero.

[0078] At this time, the torque deviation ΔT changes as shown in FIG. ０ From time t ３ When the electric vehicle 100 is traveling on a flat road during the period from ｄ ^ is zero, and the basic torque target value T ｍ０ ＊ Therefore, the torque deviation ΔT increases stepwise. ｍ０ ＊ The voltage gradually increases according to the change of ２ After that, it remains at zero. ３ When the electric vehicle 100 enters a downhill road, the disturbance torque estimated value T ｄ ^ is a negative value according to the road surface gradient ψ. ３ After that, the torque deviation ΔT increases and becomes a value greater than zero.

[0079] As a result, the rotation speed ω ｍ Specifically, when the strong regeneration mode or the weak regeneration mode is set, the transition of the ０ From time t ２ So, the rotation speed ω ｍ That is, the electric vehicle 100 is decelerated by the regenerative braking force. ２ When the coasting mode is entered, the rotation speed ω ｍ Therefore, the electric vehicle 100 maintains the vehicle speed V.

[0080] After that, at time t ３ When the electric vehicle 100 enters a downhill road, the rotational speed ω ｍ Therefore, the accelerator operation and mode setting S ｍｏｄｅEven though no change operation is performed at time t ３ The subsequent acceleration may be difficult for a driver who intends to simply reduce the regenerative braking force and coast. In other words, this acceleration may not match the driver's feeling. When trying to suppress such acceleration that does not match the driver's feeling, many drivers choose the mode setting S. ｍｏｄｅ This causes the driver to apply the brakes without adjusting the regenerative braking force. This makes it more likely that the driver will have to change the pedal, which can be cumbersome. It also worsens fuel economy.

[0081] FIG. 9 shows the rotation speed ω ｍ 9(D) is a graph showing the transition of the basic torque target value T ｍ０ ＊ is shown by a dashed line, and the torque command value T ｍ１ ＊ is shown by a solid line.

[0082] 9A to 9C, the assumed driving scenario is the same as that of the comparative example. That is, the electric vehicle 100 decelerates on a flat road by regenerative braking force, and then enters a downhill road while coasting. At this time, in this embodiment, the torque command value T ｍ１ ＊ , torque deviation ΔT, and rotation speed ω ｍ changes as shown in FIGS. 9(D) to 9(F).

[0083] Specifically, as shown in Figures 9(D) to 9(F), the time t ３ Torque command value T in the period up to ｍ１ ＊ , torque deviation ΔT, and rotation speed ω ｍ The transition is the same as in the comparative example.

[0084] On the other hand, in this embodiment, time t ３ When the electric vehicle 100 enters a downhill road, the mode setting S ｍｏｄｅ Even if the torque deviation ΔT is not changed, the basic torque target value Tｍ０ ＊ Therefore, as shown in FIG. 9(D), the torque command value T ｍ１ ＊ is the time t ３ Hereafter, the basic torque target value T ｍ０ ＊ and the disturbance torque estimate T ｄ ^ (running resistance R) to generate a negative value that generates a regenerative braking force. Also, as shown in FIG. 9(E), the torque deviation ΔT is ３ It remains at zero thereafter.

[0085] As a result, as shown in FIG. 9(F), the rotation speed ω of the electric motor 10 ｍ is the time t ３ That is, in this embodiment, even when the electric vehicle 100 enters a downhill road while in the coasting mode, the mode setting S ｍｏｄｅ Even if the mode setting S is not changed, the regenerative braking force increases appropriately, and the electric vehicle 100 does not accelerate much and generally maintains its vehicle speed V. This behavior of the electric vehicle 100 is ｍｏｄｅ This change simply weakens the regenerative braking force, which suits the driver's feeling when coasting. This reduces the number of times the driver has to step on the brakes. In other words, the driver is less likely to have to perform the cumbersome pedal switching operation. This also reduces the deterioration of fuel economy.

[0086] [First Modification] In the first embodiment, the correction torque setter 44 determines acceleration based on the torque deviation ΔT and sets the correction torque T ｃ The correction torque setter 44 sets, for example, the road surface gradient ψ and the rotation speed ω ｍ Acceleration is determined based on the ｃ That is, the correction torque setter 44 can set the road surface gradient ψ and the rotation speed ω ｍ Based on this, the amount of increase in the regenerative braking force, etc. can be determined.

[0087] Specifically, the road gradient ψ and the rotational speed ω ｍBased on this, an acceleration region AA can be defined on the torque map. The acceleration region AA is a region including a driving point where the electric vehicle 100 accelerates due to a lack of regenerative braking force relative to the running resistance R in a situation where regenerative braking force should be generated.

[0088] FIG. 10 is an explanatory diagram showing the acceleration region AA. Here, as an example, the acceleration region AA is shown by hatching on a torque map for the strong regeneration mode. Also, in FIG. 10, the running resistance (R ｕｐ ), running resistance on a flat road (R ｆｌａｔ ), and running resistance on a downhill road (R ｄｏｗｎ ) is shown by the dashed line.

[0089] As shown in FIG. 10, the running resistance R is increased by the rotational speed ω ｍ The running resistance R increases in proportion to the square of the vehicle speed V. In addition, the running resistance R increases or decreases according to the road gradient ψ. That is, in the torque map, the running resistance R shifts up or down according to the road gradient ψ. Specifically, the running resistance (R ｆｌａｔ ) as the standard, the running resistance R increases on an uphill road (R ｕｐ ), and on downhill roads, the running resistance decreases (R ｄｏｗｎ ).

[0090] The reason why the electric vehicle 100 accelerates due to a lack of regenerative braking force in a situation where regenerative braking force should be generated is that the basic torque target value T ｍ０ ＊ is zero or negative, and the basic torque target value T ｍ０ ＊ is the negative running resistance R (= R ｄｏｗｎ ) in the torque map. ｄｏｗｎ ) and rotation speed ω ｍ The region surrounded by the axes is the acceleration region AA, and when the electric motor 10 is driven at an operating point within this acceleration region AA, the electric vehicle 100 accelerates due to a lack of regenerative braking force.

[0091] Therefore, the rotation speed ω ｍIf there is information on the road surface gradient ψ that determines the dashed line, it is determined whether the operating point of the electric motor 10 belongs to the acceleration region AA, and the basic torque target value T ｍ０ ＊ The torque to be compensated for (correction torque T ｃ ) can be determined. ｄ When estimating the regenerative braking force ( ^ ) based on the road gradient ψ, the increase in the regenerative braking force is calculated as a function of the road gradient ψ and the rotational speed ω ｍ The determination can be made based on the following:

[0092] The correction torque setter 44 is configured to set the rotation speed ω ｍ and the road surface gradient ψ and the correction torque T ｃ In this case, the correction torque setter 44 can refer to the correction torque map to determine the rotation speed ω ｍ and a correction torque T according to the road surface gradient ψ ｃ can be set.

[0093] Second Embodiment In the first embodiment and the first modified example, when the electric vehicle 100 accelerates due to a lack of regenerative braking force, the correction torque T ｃ Using the basic torque target value T ｍ０ ＊ For example, when the electric vehicle 100 accelerates due to a lack of regenerative braking force, the driver may set the mode S ｍｏｄｅ Regardless of the setting, the mode is forcibly set to S. ｍｏｄｅ By changing the basic torque target value T ｍ０ ＊ In the second embodiment, the mode setting S ｍｏｄｅ Regardless of the mode setting, the mode setting S is temporarily and forcibly ｍｏｄｅ By changing the basic torque target value T ｍ０ ＊ An example of correcting the above will be described.

[0094] 11 is a block diagram showing the configuration of the controller 13 in the second embodiment. Here, the configuration related to the torque command value calculation process S12 is shown, and the illustration and description of the other configurations are omitted.

[0095] 11 , in the second embodiment as well, the controller 13 includes a base torque target value setting unit 21, a running resistance estimator 22, and a base torque target value correcting unit 23. Of these, the configuration of the running resistance estimator 22 is the same as in the first embodiment.

[0096] On the other hand, the basic torque target value setting unit 21 is configured to set the accelerator operation amount θ and the rotation speed ω of the electric motor 10. ｍ , and the correction mode setting S set by the basic torque target value correction unit 23 ｍｏｄｅ Based on this, the basic torque target value T ｍ０ ＊ That is, the basic torque target value setting unit 21 of the first embodiment sets the mode S ｍｏｄｅ However, in this embodiment, the basic torque target value setting unit 21 directly refers to the mode setting S ｍｏｄｅ Instead of the above, the correction mode setting S ｍｏｄｅ Specifically, the basic torque target value setting unit 21 refers to the correction mode setting S ｍｏｄｅ ', and by referring to the selected torque map, the accelerator operation amount θ and the rotation speed ω ｍ The basic torque target value T ｍ０ ＊ Correction mode setting S ｍｏｄｅ The torque maps that can be selected by ' and their specific contents are the same as those in the first embodiment (see FIG. 5).

[0097] The basic torque target value correction unit 23 corrects the basic torque target value T ｍ０ ＊ This is the same as in the first embodiment. However, the basic torque target value correcting unit 23 of this embodiment corrects the correction mode setting S ｍｏｄｅ ' is set and input to the basic torque target value setting unit 21, the basic torque target value Tｍ０ ＊ Therefore, in this embodiment, the controller 13 does not have the adding unit 24. The basic torque target value setting unit 21 directly corrects the correction mode setting S ｍｏｄｅ The basic torque target value T ｍ０ ＊ is the torque command value T ｍ１ ＊ It is used as (T ｍ１ ＊ =T ｍ０ ＊ ).

[0098] 12 is a block diagram showing the configuration of the base torque target value correction unit 23 in the second embodiment. As shown in FIG. 12, the base torque target value correction unit 23 in the second embodiment includes an acceleration determination unit 41 and a mode setting holder 51.

[0099] The acceleration determination unit 41 determines the basic torque target value T ｍ０ ＊ and the estimated disturbance torque T ｄ ^, it is determined whether or not the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the running resistance R. In this embodiment, the acceleration determination unit 41 then uses the result of this determination to determine the correction mode setting S ｍｏｄｅ It is represented by '.

[0100] Specifically, the acceleration determination unit 41 of this embodiment is configured by a torque deviation calculator 43 and a correction mode setter 52 .

[0101] The torque deviation calculator 43 calculates the basic torque target value T ｍ０ ＊ and the estimated disturbance torque T ｄ The torque deviation ΔT, which is the deviation of ^, is calculated. This is the same as in the first embodiment.

[0102] The correction mode setting unit 52 sets the correction mode setting S so as to cancel the torque deviation ΔT. ｍｏｄｅ Specifically, in a scene where the torque deviation ΔT is positive and the electric vehicle 100 accelerates due to the running resistance R, the correction mode setter 52 sets the mode setting S′ by the driver. ｍｏｄｅ Regardless of the torque deviation ΔT, the correction mode setting Sｍｏｄｅ ', S ｍｏｄｅ '=1 (weak regeneration mode) or S ｍｏｄｅ '=2 (strong regeneration mode).

[0103] In this embodiment, the correction mode setting unit 52 sets a threshold value TH ΔＴ is set, and the torque deviation ΔT is set to the threshold value TH ΔＴ When this is the case, the correction mode setting S ｍｏｄｅ For example, when the vehicle is traveling in the coasting mode, the torque deviation ΔT is set to the threshold value TH ΔＴ In this case, the correction mode setting unit 52 sets the correction mode setting S ｍｏｄｅ ' to S ｍｏｄｅ '=1 (weak regeneration mode). When the vehicle is traveling in the weak regeneration mode, the torque deviation ΔT is set to a value equal to or greater than the threshold value TH ΔＴ In this case, the correction mode setting unit 52 sets the correction mode setting S ｍｏｄｅ ' to S ｍｏｄｅ '=2 (strong regeneration mode).

[0104] This causes the mode setting S ｍｏｄｅ Even if the regenerative braking force is reduced by changing the accelerator operation amount θ, θ When the regenerative braking force should be generated, the regenerative braking force is increased appropriately, and the running resistance R is cancelled out.

[0105] On the other hand, in a scene where the torque deviation ΔT is zero and the vehicle speed V is maintained, or in a scene where the torque deviation ΔT is negative and the electric vehicle 100 is decelerating, the correction mode setter 52 sets the mode setting S ｍｏｄｅ Correction mode setting S ｍｏｄｅ ' (S ｍｏｄｅ '=S ｍｏｄｅ ). As a result, the accelerator operation amount θ becomes equal to the predetermined value Th θ When the regenerative braking force is to be generated, the mode setting S ｍｏｄｅ A regenerative braking force corresponding to the

[0106] Therefore, simply put, the correction mode setting unit 52 determines the basic torque target value T based on the torque deviation ΔT.ｍ０ ＊ and running resistance R (disturbance torque estimate T ｄ Based on the mode setting S ｍｏｄｅ The regenerative braking force is increased by appropriately changing (overwriting) the value of the regenerative braking force. The amount of increase in the regenerative braking force is determined so that the vehicle speed V of the electric vehicle 100 is maintained or so that the electric vehicle 100 decelerates.

[0107] The mode setting holder 51 holds the correction mode setting S until a specific operation is performed. ｍｏｄｅ This holds the correction mode setting S ｍｏｄｅ When the regenerative braking force is forcibly increased by the mode setting S', the regenerative braking force remains increased until the driver detects a specific operation. On the other hand, when the driver detects a specific operation, the mode setting holder 51 changes the correction mode setting S ｍｏｄｅ As a result, the regenerative braking force returns to the original value. That is, when the specific operation is detected, the regenerative braking force is updated according to the mode setting S ｍｏｄｅ The specific operation is as described above.

[0108] FIG. 13 shows the rotation speed ω ｍ 13(A) to 13(F) correspond to those in FIGS. 8(A) to 8(F) relating to the comparative example and those in FIGS. 9(A) to 9(F) relating to the first embodiment. Note that in FIG. 13(C), the mode setting S ｍｏｄｅ is indicated by a broken line, and the correction mode setting S ｍｏｄｅ 13(E), the torque deviation ΔT in this embodiment is shown by a solid line, and for reference, the torque deviation ΔT in the comparative example is shown by a dashed line.

[0109] 13A to 13C, the assumed driving scenario is the same as that of the comparative example. That is, the electric vehicle 100 decelerates on a flat road by regenerative braking force, and then enters a downhill road while coasting. At this time, in this embodiment, the correction mode setting S ｍｏｄｅ ', basic torque target value T ｍ０ ＊, torque deviation ΔT, and rotation speed ω ｍ changes as shown in FIGS. 13(C) to 13(F).

[0110] Specifically, as shown in FIG. 13(C), the mode setting S ｍｏｄｅ The transition of is the same as in the modified example and the first embodiment. Therefore, as shown in Figures 13(D) to 13(F), the time t ３ The basic torque target value T ｍ０ ＊ (=T ｍ１ ＊ ), torque deviation ΔT, and rotation speed ω ｍ The transition is the same as in the comparative example and the first embodiment.

[0111] On the other hand, in this embodiment, time t ３ When the electric vehicle 100 enters a downhill road, the driver sets the mode S ｍｏｄｅ Even if the torque deviation ΔT is not changed, the correction mode setting S ｍｏｄｅ ' is set.

[0112] Specifically, as shown in FIG. 13(E), when the electric vehicle 100 enters a downhill road, ４ The torque deviation ΔT is equal to the threshold value TH. ΔＴ If this is the case, the correction mode setting S ｍｏｄｅ ' is the mode setting S by the driver ｍｏｄｅ The mode is increased by one step from the coasting mode according to the above and set to the weak regeneration mode (S ｍｏｄｅ '=1).

[0113] Therefore, the basic torque target value setting unit 21 sets the correction mode setting S ｍｏｄｅ 13D, the torque map to be used is switched from the torque map for the coasting mode to the torque map for the weak regeneration mode. ｍ０ ＊ is corrected, and the basic torque target value T ｍ０ ＊ becomes a negative value. Furthermore, as shown in FIG. 13(E), the torque deviation ΔT also decreases in response to the switching of the torque map.

[0114] As a result, as shown in FIG. 13(F), the rotation speed ω of the electric motor 10 ｍ is the time t ３ That is, in this embodiment, even when the electric vehicle 100 enters a downhill road while in the coasting mode, the mode setting S ｍｏｄｅ Even if the mode setting S is not changed, the regenerative braking force increases appropriately, and the electric vehicle 100 does not accelerate much and generally maintains its vehicle speed V. ｍｏｄｅ This change simply weakens the regenerative braking force, which suits the driver's feeling when coasting. This reduces the number of times the driver has to step on the brakes. In other words, the driver is less likely to have to perform the cumbersome pedal switching operation. This also reduces the deterioration of fuel economy.

[0115] [Second Modification] In the second embodiment, the correction mode setting S ｍｏｄｅ By setting the basic torque target value T ｍ０ ＊ The example of correcting the correction mode setting S ｍｏｄｅ The specific method for setting the correction mode setting S' is not limited to the example of the second embodiment. ｍｏｄｅ By setting the basic torque target value T ｍ０ ＊ can be corrected.

[0116] FIG. 14 shows the correction mode setting S of the second modified example. ｍｏｄｅ 1 is a flowchart showing a method for setting the parameter '.

[0117] As shown in FIG. 14, in step S21, the basic torque target value correcting unit 23 calculates the disturbance torque estimated value T ｄ ^, basic torque target value T ｍ０ ＊ (or torque command value T ｍ１ ＊ ) and the previous value of the mode setting S ｍｏｄｅ Get.

[0118] In step S22, the basic torque target value corrector 23 calculates the disturbance torque estimated value T ｄ ^ and the basic torque target value Tｍ０ ＊ At this time, the basic torque target value T ｍ０ ＊ is the estimated disturbance torque T ｄ If it is greater than ^, the process proceeds to step S23.

[0119] In step S23, the basic torque target value correcting unit 23 determines whether the mode setting S ｍｏｄｅ Add 1 to the correction mode setting S ｍｏｄｅ ' (S ｍｏｄｅ '=S ｍｏｄｅ +1). That is, when the electric vehicle 100 accelerates due to the running resistance R due to a lack of regenerative braking force, the mode setting S set by the driver ｍｏｄｅ This increases the level of regenerative braking force.

[0120] On the other hand, in step S22, the basic torque target value T ｍ０ ＊ is the estimated disturbance torque T ｄ If the vehicle speed V is equal to or less than the predetermined value, the process proceeds to step S24. That is, if the running resistance R is cancelled out by the regenerative braking force and the electric vehicle 100 is decelerating or maintaining the vehicle speed V, the process proceeds to step S24.

[0121] In step S24, the basic torque target value correction unit 23 calculates the brake switch signal SW Ｂ Then, SW Ｂ If SW = 0 and the friction brake is not being used, the process proceeds to step S25. Ｂ If the value is 1 and the friction brake is being used, the process proceeds to step S27.

[0122] In step S25, the basic torque target value correcting unit 23 checks the accelerator operation amount θ. If the driver is stepping on the accelerator and the accelerator operation amount θ is not zero (θ≠0), the process proceeds to step S26. Then, in step S26, the basic torque target value correcting unit 23 checks the mode setting S by the driver. ｍｏｄｅ Correction mode setting S ｍｏｄｅ ' (S ｍｏｄｅ '=S ｍｏｄｅThat is, when the electric vehicle 100 is maintaining the vehicle speed V against the running resistance R or is decelerating, if it is detected that the driver has stepped on the accelerator, the basic torque target value correcting unit 23 changes the correction mode setting S ｍｏｄｅ ' is the mode setting S ｍｏｄｅ On the other hand, if it is determined in step S25 that the accelerator operation amount θ is zero (θ=0), the process proceeds to step S27.

[0123] In step S27, the basic torque target value correcting unit 23 determines whether the mode setting S ｍｏｄｅ The value obtained by subtracting 1 from the correction mode setting S ｍｏｄｅ ' (S ｍｏｄｅ '=S ｍｏｄｅ -1). That is, when the driver is stepping on the brake or when the driver is not stepping on either the accelerator pedal or the brake pedal in a situation where the electric vehicle 100 is maintaining or decelerating the vehicle speed V against the running resistance R, the basic torque target value correction unit 23 performs the mode setting S set by the driver. ｍｏｄｅ This reduces the level of regenerative braking force.

[0124] As described above, the correction mode setting S ｍｏｄｅ When setting the mode setting S', the same as in the second embodiment, ｍｏｄｅ Even if the regenerative braking force is reduced by changing the setting, it is possible to generate a regenerative braking force that suits the driver's feeling. This reduces the number of times the driver has to step on the brake. In other words, the driver is less likely to have to perform the troublesome pedal switching operation. Furthermore, the deterioration of electricity consumption is suppressed.

[0125] [Third Embodiment] In the first and second embodiments and the first and second modifications, the regenerative braking force is increased when the regenerative braking force is insufficient relative to the running resistance R, causing the electric vehicle 100 to accelerate. However, these automatic adjustment controls of the regenerative braking force can also be applied to other driving situations. For example, when there is a vehicle (hereinafter referred to as a leading vehicle) traveling in front of the host vehicle (electric vehicle 100), the controller 13 can automatically adjust the regenerative braking force in accordance with the examples of the first and second embodiments and the first and second modifications.

[0126] 15 is a flowchart of the control according to the third embodiment. As shown in FIG. 15, in step S31, the controller 13 checks whether there is a preceding vehicle. If there is a preceding vehicle, the process proceeds to step S32, where the controller 13 further calculates the relative distance D ｒｅｌ and relative vehicle speed V ｒｅｌ The controller 13 detects a preceding vehicle using a sensor (not shown), such as a LiDAR (Light Detection and Ranging) sensor or an in-vehicle camera, and obtains a relative distance D ｒｅｌ and relative vehicle speed V ｒｅｌ can be obtained.

[0127] Then, in step S33, the controller 13 calculates the relative distance D ｒｅｌ is set to a predetermined distance threshold Th Ｄ By comparing the relative distance D ｒｅｌ is the distance threshold Th Ｄ If the vehicle is too close to the preceding vehicle, the process proceeds to step S34. In step S34, the controller 13 determines whether the mode setting S ｍｏｄｅ Regardless of the vehicle speed, the regenerative braking force is automatically increased.

[0128] On the other hand, the relative distance D ｒｅｌ is the distance threshold Th Ｄ If the relative vehicle speed V is greater than the predetermined value, the process proceeds to step S35. ｒｅｌis set to a predetermined speed threshold Th Ｖ By comparing the relative vehicle speed V ｒｅｌ is the speed threshold Th Ｖ If there is a possibility that the vehicle will get too close to the preceding vehicle, the process proceeds to step S34. ｍｏｄｅ Regardless of the vehicle speed, the regenerative braking force is automatically increased.

[0129] In step S35, the relative vehicle speed V ｒｅｌ is the speed threshold Th Ｖ If the relative distance D is smaller than the safe distance D, the process proceeds to step S36. ｒｅｌ and the relative vehicle speed V ｒｅｌ If the difference is relatively small, the process proceeds to step S36. Then, in step S36, the controller 13 determines whether the mode setting S ｍｏｄｅ maintains regenerative braking force according to the vehicle speed.

[0130] In this way, the relative distance D ｒｅｌ is the distance threshold Th Ｄ or less, or when the relative vehicle speed V ｒｅｌ is the speed threshold Th Ｖ If the above is true, the controller 13 determines whether the mode setting S ｍｏｄｅ Regardless of the vehicle speed, the regenerative braking force can be increased. This makes it easier for the vehicle (electric vehicle 100) to automatically maintain a safe distance and speed from the vehicle ahead. In addition, the driver has fewer opportunities to apply the brakes in order to maintain a safe distance and speed from the vehicle ahead. As a result, the deterioration of electricity efficiency is also suppressed.

[0131] When there is a preceding vehicle, it is particularly necessary to perform control to increase the regenerative braking force. Therefore, in order to minimize control intervention, the control to increase the regenerative braking force in the first and second embodiments and the first and second modifications may be performed only when there is a preceding vehicle, as described above.

[0132] In the first to third embodiments and the first and second modifications, the regenerative braking force is increased as needed regardless of whether the operating mode being executed is the coasting mode, the weak regeneration mode, or the strong regeneration mode. However, as can be seen from the above embodiments and modifications, the mode setting S ｍｏｄｅ Regardless of the mode, the coasting mode is the mode in which the need to increase the regenerative braking force is most likely to arise. Therefore, the determination of whether the electric vehicle 100 according to each of the above embodiments and modifications will accelerate and the control to increase the regenerative braking force are performed based on the mode setting S ｍｏｄｅ It is preferable to execute this when the vehicle is in coasting mode. ｍｏｄｅ The determination of whether or not the electric vehicle 100 according to each of the above embodiments and modifications will accelerate and the control to increase the regenerative braking force may be executed only when the vehicle is in the coasting mode.

[0133] As described above, the control method for an electric vehicle according to each of the above-described embodiments and modifications controls the magnitude of the regenerative braking force generated by the electric motor 10 based on the mode setting S ｍｏｄｅ In this control method, the accelerator operation amount θ and the rotation speed ω of the electric motor 10 are switched in accordance with ｍ , and mode setting S ｍｏｄｅ Based on this, the basic torque target value T ｍ０ ＊ Also, the basic torque target value T ｍ０ ＊ and running resistance R (T ｄ Based on the running resistance R (T ｄ If it is determined that the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the acceleration, the mode setting S ｍｏｄｅ Regardless of this, the basic torque target value T ｍ０ ＊ Correct the following.

[0134] In this way, the running resistance R (the estimated disturbance torque T ｄ When the electric vehicle 100 accelerates due to a lack of regenerative braking force relative to theｍｏｄｅ Regardless of this, increasing the regenerative braking force can suppress acceleration that is difficult for the driver to predict. This reduces the number of times the driver has to apply the brakes. In other words, the driver is less likely to have to perform the troublesome pedal switching operation. Furthermore, the deterioration of electricity efficiency is suppressed.

[0135] In the control method for an electric vehicle according to the first embodiment and its modification, the correction torque T ｃ Using the basic torque target value T ｍ０ ＊ By correcting the torque T ｍ The torque command value T ｍ１ ＊ The increase in the regenerative braking force is calculated based on the basic torque target value T ｍ０ ＊ and running resistance R (T ｄ Based on the corrected torque T ｃ This is done by increasing

[0136] In this way, the correction torque T ｃ Using the basic torque target value T ｍ０ ＊ When correcting, the correction torque T ｃ The regenerative braking force can be increased by increasing the correction torque T ｃ is a parameter that can be easily adjusted appropriately depending on the amount of insufficiency of the regenerative braking force, and therefore, it is particularly easy to appropriately compensate for the insufficiency of the regenerative braking force.

[0137] In the control method for an electric vehicle according to the second embodiment and its modification, the basic torque target value T ｍ０ ＊ is the torque T that the electric motor 10 should actually generate. ｍ The torque command value T ｍ１ ＊ The increase in the regenerative braking force is used as the basic torque target value T ｍ０ ＊ and running resistance R (T ｄ Mode setting S based on ^) ｍｏｄｅ This is done by modifying

[0138] In this way, the running resistance R (T ｄ When the electric vehicle 100 accelerates due to a lack of regenerative braking force relative to the ｍｏｄｅ By changing (overwriting) the regenerative braking force, the regenerative braking force can be increased. This method allows the regenerative braking force to be adjusted simply and easily.

[0139] In the control method for an electric vehicle according to each of the above embodiments and modifications, in a situation where a regenerative braking force is generated, the basic torque target value T ｍ０ ＊ is the running resistance R (T ｄ When the difference is larger than the difference ^), it is determined that the electric vehicle 100 is accelerating.

[0140] In this way, the basic torque target value T ｍ０ ＊ and running resistance R (disturbance torque estimate T ｄ According to the magnitude relationship between the resistances R and R), it is possible to directly and accurately determine a situation in which the electric vehicle 100 accelerates due to insufficient regenerative braking force relative to the running resistance R in a situation in which regenerative braking force should be generated.

[0141] In the control methods for an electric vehicle according to the above-described embodiments and modifications, the amount of increase in regenerative braking force is determined so that the vehicle speed V of the electric vehicle 100 is maintained or so that the electric vehicle 100 decelerates.

[0142] In this way, if the increase amount of the regenerative braking force is adjusted so that the vehicle speed V of the electric vehicle 100 is maintained or so that the electric vehicle 100 decelerates, the driver can ｍｏｄｅ When the regenerative braking force is reduced by changing the setting, behavior that suits the driver's feeling can be achieved.

[0143] In the control method for an electric vehicle according to the first modification, the running resistance R is estimated based on the road surface gradient ψ. In this case, the increase in regenerative braking force is calculated based on the road surface gradient ψ and the rotational speed ω ｍ is determined based on the

[0144] In this way, the running resistance R can be easily estimated from the road surface gradient ψ. In this case, as described above, the road surface gradient ψ and the rotation speed ω of the electric motor 10 areｍ By using the above formula, the increase amount of the regenerative braking force can be easily and appropriately set.

[0145] In the control method for an electric vehicle according to each of the above-described embodiments and modifications, after the regenerative braking force has been increased, the regenerative braking force is returned to its original state when a predetermined specific operation is performed.

[0146] That is, the driver's mode setting S ｍｏｄｅ Regardless of the above, if the regenerative braking force is increased, the increased state of the regenerative braking force is maintained until a specific operation is performed, and only when a specific operation is performed does the driver change the mode setting S. ｍｏｄｅ This makes it possible to prevent the regenerative braking force from frequently increasing and decreasing repeatedly when, for example, the road surface gradient ψ (running resistance R) changes.

[0147] In the control method for an electric vehicle according to each of the above-described embodiments and modifications, the specific operation is an increase in the accelerator operation amount θ, an operation of the brake (friction brake), or a mode setting S by the driver. ｍｏｄｅ This is a change.

[0148] Driver mode setting S ｍｏｄｅ Regardless of the above, if the regenerative braking force is increased, maintaining the increased state of the regenerative braking force until an explicit operation to change the driving force or braking force of the electric vehicle 100 as described above is detected makes it particularly easy to prevent the regenerative braking force from frequently increasing and decreasing.

[0149] In the control method for an electric vehicle according to each of the above embodiments and modifications, the rotation speed ω ｍ Based on this, the torque T ｍ The first torque estimation value T ｅｓｔ１ ^ is calculated, and the final torque command value (T ｍ１ ＊ ) based on which the torque T that the electric motor 10 should output is calculated. ｍ The second torque estimate T ｅｓｔ２ ^ is calculated, and the running resistance R is calculated as the first torque estimate T ｅｓｔ１ ^ and the second torque estimate T ｅｓｔ２ ^ deviation (disturbance torque estimate T ｄ ^) is calculated based on

[0150] In this way, the first torque estimate T ｅｓｔ１ ^ and the second torque estimate T ｅｓｔ２ The disturbance torque estimate T ｄ If ^ is the running resistance R, it is possible to estimate the running resistance R particularly accurately, taking into account not only gradient resistance but also air resistance, rolling resistance, etc. Therefore, it is possible to particularly accurately identify a situation in which the electric vehicle 100 accelerates due to a lack of regenerative braking force relative to the running resistance R.

[0151] In the control method for an electric vehicle according to the third embodiment, the relative distance D ｒｅｌ is a predetermined distance threshold Th Ｄ or when the relative vehicle speed V ｒｅｌ is a predetermined speed threshold Th Ｖ When the above is true, the driver sets the mode S ｍｏｄｅ Regardless of the above, the regenerative braking force is increased.

[0152] In this way, when there is a preceding vehicle, the relative distance D ｒｅｌ and relative vehicle speed V ｒｅｌ If the regenerative braking force is increased based on this, the host vehicle (electric vehicle 100) can automatically maintain a safe distance and speed from the preceding vehicle more easily. Also, the driver will have fewer opportunities to apply the brakes in order to maintain a safe distance and speed from the preceding vehicle. As a result, the deterioration of electricity efficiency is also suppressed.

[0153] In the control method for an electric vehicle according to each of the above embodiments and modifications, the mode setting S ｍｏｄｅ is the accelerator operation amount θ is the predetermined value Th θ When the basic torque target value T ｍ０ ＊ is set to a negative value, and the accelerator operation amount θ is set to a predetermined value Th θ When the basic torque target value T ｍ０ ＊ The determination of whether or not the electric vehicle 100 will accelerate and the increase in the regenerative braking force are determined by the mode setting S ｍｏｄｅ is in coasting mode.

[0154] Mode setting by driver S ｍｏｄｅ Regardless of the mode, the coasting mode is the mode in which the need to increase the regenerative braking force is most likely to arise. Therefore, as described above, the determination of whether or not the electric vehicle 100 will accelerate and the control to increase the regenerative braking force are determined by the mode setting S ｍｏｄｅ In addition, it is preferable that the determination of whether or not the electric vehicle 100 is accelerating and the control of increasing the regenerative braking force are performed in accordance with the mode setting S by the driver. ｍｏｄｅ It is sufficient to execute it only when the vehicle is in coasting mode.

[0155] The control device for an electric vehicle according to each of the above-described embodiments and modifications controls the magnitude of the regenerative braking force generated by the electric motor 10 based on the mode setting S ｍｏｄｅ The control device (controller 13) of the electric vehicle switches the control mode in accordance with the accelerator operation amount θ and the rotation speed ω of the electric motor 10. ｍ , and mode setting S ｍｏｄｅ Based on this, the basic torque target value T ｍ０ ＊ a basic torque target value setting unit 21 that sets the basic torque target value T ｍ０ ＊ and running resistance R (T ｄ Based on the running resistance R (T ｄ An acceleration determination unit 41 determines whether the electric vehicle 100 will accelerate due to a lack of regenerative braking force relative to the acceleration determination unit 42, and when it is determined that the electric vehicle 100 will accelerate, a mode setting S ｍｏｄｅ Regardless of this, the basic torque target value T ｍ０ ＊ and a basic torque target value correction unit 23 that corrects the basic torque target value.

[0156] In this way, the running resistance R (the estimated disturbance torque T ｄ When the electric vehicle 100 accelerates due to a lack of regenerative braking force relative to the ｍｏｄｅRegardless of this, increasing the regenerative braking force can suppress unpredictable acceleration and reduce the number of times the driver has to brake. In other words, the driver is less likely to have to perform the troublesome pedal switching operation. In addition, the deterioration of electricity consumption can be suppressed.

[0157] The above describes embodiments and modifications of the present invention, but the configurations described in the above embodiments and modifications merely illustrate some of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

Claims

1. A control method for an electric vehicle that switches the magnitude of the regenerative braking force generated by an electric motor in accordance with a mode setting by a driver, the control method comprising: setting a basic torque target value for the electric motor based on an accelerator operation amount, the rotational speed of the electric motor, and the mode setting; determining, based on the basic torque target value and running resistance, whether the electric vehicle will accelerate due to a lack of regenerative braking force relative to the running resistance; and, if it is determined that the electric vehicle will accelerate, correcting the basic torque target value to increase the regenerative braking force regardless of the mode setting by the driver.

2. A control method for an electric vehicle as claimed in claim 1, wherein a torque command value representing the torque that should actually be generated by the electric motor is calculated by correcting the basic torque target value using a correction torque, and the regenerative braking force is increased by increasing the correction torque based on the basic torque target value and the running resistance.

3. A control method for an electric vehicle as claimed in claim 1, wherein the basic torque target value is used as a torque command value representing the torque that should actually be generated by the electric motor, and the regenerative braking force is increased by changing the mode setting based on the basic torque target value and the running resistance.

4. A control method for an electric vehicle according to any one of claims 1 to 3, wherein the control method determines that the electric vehicle will accelerate when the basic torque target value is greater than the running resistance in a situation where regenerative braking force is generated.

5. A control method for an electric vehicle according to any one of claims 1 to 3, wherein the amount of increase in regenerative braking force is determined so that the vehicle speed of the electric vehicle is maintained or so that the electric vehicle decelerates.

6. A control method for an electric vehicle according to any one of claims 1 to 3, wherein the running resistance is estimated based on a road surface gradient, and the amount of increase in regenerative braking force is determined based on the road surface gradient and the rotation speed.

7. A control method for an electric vehicle as set forth in any one of claims 1 to 3, wherein, after the regenerative braking force has increased, when a predetermined specific operation is performed, the regenerative braking force is returned to its original state.

8. A control method for an electric vehicle according to claim 7, wherein the specific operation is an increase in the accelerator operation amount, an operation of the brake, or a change in the mode setting by the driver.

9. A control method for an electric vehicle according to any one of claims 1 to 3, comprising: calculating a first torque estimate, which is an estimate of the torque being output by the electric motor, based on the rotational speed; calculating a second torque estimate, which is an estimate of the torque to be output by the electric motor, based on a final torque command value for the electric motor; and calculating the running resistance as a ratio of the first torque estimate and the second torque estimate (T ｅｓｔ２ A control method for an electric vehicle, in which the control is calculated based on the deviation of 10. A control method for an electric vehicle according to any one of claims 1 to 3, further comprising increasing regenerative braking force when the relative distance to the preceding vehicle is equal to or less than a predetermined distance threshold, or when the relative vehicle speed to the preceding vehicle is equal to or greater than a predetermined speed threshold, regardless of the mode setting made by the driver.

11. A control method for an electric vehicle according to any one of claims 1 to 3, wherein the mode settings include a regeneration mode in which the basic torque target value is set to a negative value when the accelerator operation amount is equal to or less than a predetermined value, and a coasting mode in which the basic torque target value is set to zero when the accelerator operation amount is equal to or less than the predetermined value, and wherein a determination as to whether the electric vehicle will accelerate and an increase in regenerative braking force are made when the mode setting by the driver is the coasting mode.

12. A control device for an electric vehicle that switches the magnitude of the regenerative braking force generated by an electric motor in accordance with a mode setting by a driver, comprising: a basic torque target value setting unit that sets a basic torque target value for the electric motor based on an accelerator operation amount, the rotational speed of the electric motor, and the mode setting; an acceleration determination unit that determines whether the electric vehicle will accelerate due to a lack of regenerative braking force relative to the running resistance based on the basic torque target value and the running resistance; and a basic torque target value correction unit that corrects the basic torque target value so as to increase the regenerative braking force if it is determined that the electric vehicle will accelerate, regardless of the mode setting by the driver.

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