Method for controlling electric vehicle and device for controlling electric vehicle

Abstract

One embodiment of the present invention is a method for controlling an electric vehicle having a power consumption suppression mode and a travel performance mode as a control mode for distributing a requested torque to a front torque and a rear torque and adjusting the distribution of the requested torque. In the control method for the electric vehicle, in the case of the power consumption suppression mode, the requested torque is distributed to the front torque or the rear torque more, and in the case of the driving performance mode, the front torque or the rear torque to which the requested torque is distributed more in the power consumption suppression mode is reduced. Furthermore, the temperature of the front drive system or the rear drive system is acquired, and the output of the front torque or the rear torque is limited by setting an upper limit value corresponding to the temperature of the front drive system or the rear drive system for the distributed front torque or rear torque. Furthermore, when the control mode is the power consumption suppression mode, the control mode is switched to the driving performance mode after the upper limit value is reduced and before the output of the front torque or the rear torque is limited to the upper limit value.

Description

Technical Field

[0001] The invention relates to a control method of an electric vehicle and a control device of an electric vehicle. Background Art

[0002] JP2020-082988A discloses a driving mode control device for a vehicle, which drives the front wheels with the power of an engine and drives the rear wheels with the power of an electric generator, and switches between two-wheel drive and four-wheel drive by adjusting the distribution of the driving force of the engine and the electric generator. In addition, the structure of the driving mode control device aims to reduce the area in which the operation is performed in the four-wheel drive state and expand the area in which the operation is performed in the two-wheel drive state for a hybrid vehicle, thereby stabilizing the operation of the hybrid vehicle that suppresses power consumption. Summary of the invention

[0003] Four-wheel drive electric vehicles sometimes adjust the torque (driving force) distribution between the front and rear wheels. Specifically, the torque distribution is adjusted to substantially drive the electric vehicle in two wheels to suppress power consumption or to drive the electric vehicle in four wheels to improve driving performance.

[0004] Torque distribution to suppress power consumption As described above, the electric vehicle is essentially driven in a two-wheel drive state, so either the front wheel drive system or the rear wheel drive system is operated intensively. For example, in the case of two-wheel drive with the front wheels to suppress power consumption, the electric motor and inverter driving the front wheels are operated intensively. As a result, depending on the driving scene, either the front wheel drive system or the rear wheel drive system may fall into an overheated state.

[0005] In addition, when the motor, inverter, etc. may fall into an overheating state, the output torque is limited to prevent damage caused by overheating. For example, when the motor driving the front wheels may become overheated, the output limit is implemented for the torque of the front wheels allocated from the requested torque. When the output limit for overheating protection is implemented, part of the torque that should be output by the front and rear wheels is reduced, so the electric vehicle is not driven with the requested torque.

[0006] That is, when a four-wheel drive electric vehicle is driven with torque distribution that suppresses power consumption, the electric vehicle may not be driven with the requested torque in order to protect the drive system from overheating depending on the driving scene.

[0007] An object of the present invention is to provide a control method and a control device for an electric vehicle, which can protect a drive system from overheating and drive the vehicle at a requested torque even when torque distribution is adjusted to a distribution that suppresses power consumption.

[0008] A certain mode of the present invention is a control method for an electric vehicle as follows, that is, as a control mode for allocating a requested torque to a torque generated at the front wheel, i.e., a front torque, and a torque generated at the rear wheel, i.e., a rear torque, and adjusting the distribution of the requested torque, there is a power consumption suppression mode that gives priority to the suppression of power consumption and a driving performance mode that gives priority to driving performance. With regard to the control method for the electric vehicle, in the power consumption suppression mode, the requested torque is allocated more to either the front torque or the rear torque, and in the driving performance mode, the front torque or the rear torque to which the requested torque is allocated more in the power consumption suppression mode is reduced. In addition, the temperature of a drive system corresponding to the front torque or the rear torque to which the requested torque is allocated more in the power consumption suppression mode is obtained in the front drive system that drives the front wheels or the rear drive system that drives the rear wheels. For the front torque or the rear torque to which the requested torque is allocated more in the power consumption suppression mode, an upper limit value corresponding to the temperature of the corresponding drive system is set, thereby limiting the front torque or the rear torque to which the requested torque is allocated more in the power consumption suppression mode. Furthermore, when the control mode is the power consumption reduction mode, after the upper limit value is lowered, the control mode is switched to the running performance mode before the front torque or the rear torque to which the requested torque is largely allocated in the power consumption reduction mode is limited to the upper limit value. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is an explanatory diagram showing the structure of an electric vehicle.

[0010] Figure 2 This is a block diagram showing the configuration of a controller involved in torque distribution.

[0011] Figure 3 This is a block diagram showing the structure of a torque distribution unit.

[0012] Figure 4 This is a block diagram showing the structure of an output limit calculation unit.

[0013] Figure 5 : is a schematic graph showing the manner in which the output is limited based on the temperature of the front motor.

[0014] Figure 6 : is a schematic graph showing a method of output limitation based on the temperature of the front inverter.

[0015] Figure 7 This is a flowchart for the case where the power consumption suppression mode is canceled and the control mode is switched to the driving performance mode.

[0016] Figure 8 This is a flowchart for when returning to the power consumption reduction mode.

[0017] Fig. 9 It is a graph schematically showing the transition of the temperature and torque of each motor and the vehicle speed of the electric vehicle of the comparative example.

[0018] Fig.10 This is a graph schematically showing changes in the temperature and torque of each motor and the vehicle speed of the electric vehicle according to the present embodiment.

[0019] Fig.11 This is a graph schematically showing changes in the temperature and torque of each motor and the vehicle speed when the electric vehicle according to the present embodiment returns to the power consumption reduction mode. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] Figure 1 1 is an explanatory diagram showing the structure of the electric vehicle 100. The electric vehicle 100 is an electric four-wheel drive vehicle that uses an electric motor to drive the front wheels 22 and the rear wheels 32 as driving wheels. In addition, the electric vehicle 100 can adjust the torque (driving force) generated at the front wheels 22, that is, the front torque T f and the torque (driving force) generated at the rear wheel 32, that is, the rear torque T r Therefore, electric vehicle 100 may be substantially in a two-wheel drive state in some cases according to the torque distribution.

[0022] like Figure 1 As shown, the electric vehicle 100 has a front drive system 11 , a rear drive system 12 , a battery 13 , and a controller 14 .

[0023] The front drive system 11 is a system for driving the front wheels 22 using the front motor 21. The front drive system 11 includes a front inverter 23, a rotation sensor 24, a current sensor 25, and the like in addition to the front motor 21 and the front wheels 22.

[0024] The front motor 21 is, for example, a three-phase AC synchronous motor, and is driven by AC power input from the front inverter 23. The output torque of the front motor 21 (front torque T f ) causes the front wheel 22 to generate torque (driving force). In addition, the front motor 21 generates so-called regenerative torque when its drive shaft is rotated by the front wheel 22. Thus, the front motor 21 can recover the kinetic energy of the electric vehicle 100 as electric energy.

[0025] The front wheel 22 is a pair of drive wheels disposed in front of the electric vehicle 100. The front wheel 22 is connected to the front motor 21 via the front speed reducer 26 and the drive shaft 27. In the present embodiment, the front wheel 22 is composed of a right front wheel and a left front wheel. However, the right front wheel and the left front wheel are connected by the drive shaft 27, and are driven as a whole. Therefore, in the present embodiment, the right front wheel and the left front wheel are not distinguished and are collectively referred to as the front wheel 22. In addition, the front wheel 22 is the first drive wheel in comparison with the different drive wheel, that is, the rear wheel 32.

[0026] The front inverter 23 has two pairs of switching elements for each phase of the front motor 21. The front inverter 23 opens and closes the switching elements according to the PWM (Pulse Width Modulation) signal input from the controller 14. As a result, the front inverter 23 converts the DC power supplied from the battery 13 into AC power and inputs it to the front motor 21 to drive the front motor 21. The switching elements constituting the front inverter 23 are, for example, power semiconductor elements such as insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistors (MOS-FETs). During regenerative control, the front inverter 23 converts the AC power generated by the front motor 21 into DC power and inputs it to the battery 13.

[0027] The rotation sensor 24 detects the rotor phase α of the front motor 21 f . Rotor phase α f The rotation sensor 24 is, for example, a resolver or an encoder. The detected rotor phase α f Input to the controller 14.

[0028] The current sensor 25 detects the current flowing through each phase of the front motor 21 (hereinafter referred to as the three-phase current). uf 、i vf 、i wf The three-phase current i of the front motor 21 uf 、i vf 、i wf Input to the controller 14.

[0029] The rear drive system 12 is a system that utilizes the rear motor 31 to drive the rear wheel 32, and is constructed to be symmetrical with the front drive system 11. Therefore, in addition to the rear motor 31 and the rear wheel 32, the rear drive system 12 also has a rear inverter 33, a rotation sensor 34, a current sensor 35, a rear reducer 36, a drive shaft 37, etc. The above-mentioned parts that constitute the rear drive system 12 function in the same way as the parts of the front drive system 11. That is, the rear wheel 32 is a pair of drive wheels arranged at the rear of the electric vehicle 10. The rear wheel 32 is composed of a right rear wheel and a left rear wheel, but in the present embodiment, the above-mentioned components are not distinguished and the right rear wheel and the left rear wheel are collectively referred to as the rear wheel 32. The rear wheel 32 is the second drive wheel in comparison with the front wheel 22, which is a different drive wheel. The rotor phase of the rear drive system 12 detected by the rotation sensor 34 is α r The current flowing in each phase of the rear motor 31 detected by the current sensor 35 is i ur 、i vr 、i wr .

[0030] The battery 13 is provided in common to the front drive system 11 and the rear drive system 12, and supplies electric power for driving the front motor 21 and the rear motor 31. In addition, the battery 13 is charged by the regenerative electric power generated by the front motor 21 and the rear motor 31 during regenerative control.

[0031] The controller 14 is a control device for the electric vehicle 100. The controller 14 is composed of, for example, one or more computers including a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). In addition, the controller 14 is programmed to control the front motor 21 and the rear motor 31, etc., in a predetermined control cycle. For example, the controller 14 obtains various vehicle variables, and generates PWM signals for driving the front motor 21 and the rear motor 31, respectively, based on the above-mentioned vehicle variables. Moreover, the controller 14 inputs the generated PWM signals to the front inverter 23 and the rear inverter 33, respectively, thereby driving the front motor 21 and the rear motor 31 according to the vehicle variables.

[0032] The vehicle variable is a parameter indicating the control state of the electric vehicle 10. As described above, the controller 14 sets, for example, the rotor phase α of the front motor 21. f And the three-phase current i uf 、i vf 、i wf , the rotor phase α of the rear motor 31 r And the three-phase current i ur 、i vr 、i wr Obtained as a vehicle variable.

[0033] In addition, the controller 14 sets the accelerator opening A PO and the DC voltage V of the battery 13 dc The accelerator opening degree A is obtained as a vehicle variable. PO The accelerator pedal opening A is a parameter indicating the amount of operation of the accelerator pedal by the driver. For example, the accelerator opening A is appropriately detected as required by a sensor not shown. PO and the DC voltage V of the battery 13 dc .

[0034] In addition, the controller 14 calculates the acceleration generated in the electric vehicle 100, the temperature of the front drive system 11, the temperature of the rear drive system 12, and the slope of the road on which the electric vehicle 100 is traveling (hereinafter referred to as the road slope ψ road ) etc. are obtained as vehicle variables.

[0035] More specifically, the controller 14 obtains the acceleration in the front-rear direction caused by acceleration and deceleration (hereinafter referred to as the front-rear acceleration Ac1) and the lateral acceleration caused by turning (hereinafter referred to as the lateral acceleration Ac2) as the acceleration generated in the electric vehicle 100. For example, the front-rear acceleration Ac1 and the lateral acceleration Ac2 are appropriately detected as needed using an acceleration sensor (not shown).

[0036] As the temperature of the front drive system 11, the controller 14 obtains the temperature θ of the front motor 21. f-MOT and the temperature θ of the front inverter 23 f-INV More realistically, regarding the front motor 21, the temperature of the permanent magnet of the rotor, the temperature of the stator coil constituting the stator, and other temperatures are obtained for each part constituting the front motor 21. However, in this embodiment, in order to simplify the description, the temperature of each part is set to the temperature θ of the front motor 21. f-MOT Similarly, regarding the front inverter 23, for example, the temperature of each switching element can be obtained, but in this embodiment, in order to simplify the description, the temperature of each part constituting the front inverter 23 is set to the temperature θ of the front inverter 23. f-INV In the present embodiment, the temperatures of the front motor 21, the front inverter 23 and other components constituting the front drive system 11 are simply collectively referred to as the temperature of the front drive system 11. The temperature θ of the front motor 21 is appropriately detected by a temperature sensor (not shown) as needed or estimated by calculation using vehicle variables. f-MOT , the temperature θ of the front inverter 23 f-INV .

[0037] Similar to the temperature of the front drive system 11, the controller 14 can obtain the temperature θ of the rear motor 31 as the temperature of the rear drive system 12.r-MOT , the temperature θ of the rear inverter 33 r-INV The temperature θ of the rear motor 31 is detected by a temperature sensor (not shown) as needed or estimated by calculation using vehicle variables. r-MOT , the temperature θ of the rear inverter 33 r-INV .

[0038] The controller 14 can obtain the road surface slope ψ based on information of the planned travel route pre-registered in the vehicle navigation system and the current position of the electric vehicle 100 determined by GPS (Global Positioning System), for example. road .

[0039] In addition, the controller 14 of the present embodiment directly acquires vehicle variables using various sensors in principle, but the controller 14 can acquire part or all of the vehicle variables from other controllers (computers) not shown.

[0040] In addition, the controller 14 can obtain new vehicle variables by performing calculations using the obtained vehicle variables. For example, the controller 14 calculates the rotational angular velocity ω of the front motor 21. mf [rad / s] and the rotational angular velocity ω of the rear motor 31 mr The rotational angular velocity ω of the front motor 21 is calculated as [rad / s]. mf is the mechanical angular velocity, and the rotor phase α f The differential is performed and the differential result is divided by the number of pole pairs of the front motor 21 to perform the calculation. Similarly, the rotational angular velocity ω of the rear motor 31 is mr is the mechanical angular velocity, and the rotor phase α r The controller 14 calculates the rotational angular velocity ω of the front motor 21 by performing differentiation and dividing the differentiation result by the number of pole pairs of the rear motor 31. mf [rad / s] to obtain the vehicle speed V [km / h] of the electric vehicle 100.

[0041] Figure 2 is a block diagram showing the structure of the controller 14 involved in torque distribution. Figure 2 As shown, the controller 14 includes a request torque calculation unit 41 and a torque distribution unit 42 .

[0042] The requested torque calculation unit 41 calculates the output torque (hereinafter referred to as requested torque T ) requested from the electric vehicle 100 based on the operation of the accelerator pedal by the driver or the like. req In the present embodiment, the requested torque calculation unit 41 calculates the accelerator opening A based on the accelerator opening A. PO and the rotational angular velocity ω of the front motor 21 mf For the requested torque T reqThe requested torque calculation unit 41 refers to, for example, the accelerator opening A PO and the rotational angular velocity ω of the front motor 21 mf and the requested torque T req The corresponding diagram is related to the accelerator opening A PO and the rotational angular velocity ω of the front motor 21 mf The corresponding requested torque T req Perform calculations.

[0043] The torque distribution unit 42 is based on the requested torque T req For the indicated front torque T f The torque command value T before f * and indicated rear torque T r The torque command value T r *Calculation is performed. The controller 14 calculates the torque command value T based on the previous torque command value T f * and the torque command value T r *, using the front motor 21 to transfer the front torque T f Output and use the rear motor 31 to convert the rear torque T r That is, the torque distribution unit 42 outputs the requested torque T req Distributed to the front torque T f and the rear torque T r .

[0044] In this embodiment, the front torque T is adjusted. f After the torque T r The requested torque T req Regarding the distribution of power, that is, the control mode of torque distribution, electric vehicle 100 has two control modes, namely, a power consumption suppression mode and a driving performance mode.

[0045] The power consumption suppression mode is a control mode in which the torque distribution unit 42 performs torque distribution with priority given to suppression of power consumption (power consumption). Specifically, when the control mode is the power consumption suppression mode, the torque distribution unit 42 adjusts the torque distribution to a two-wheel drive state (or a state close thereto) in which the electric vehicle 100 is driven by either the front wheel 22 or the rear wheel 32, thereby suppressing power consumption. In the present embodiment, when the control mode is the power consumption suppression mode, the torque distribution unit 42 adjusts the torque distribution to a two-wheel drive state (or a state close thereto) in which the electric vehicle 100 is driven by either the front wheel 22 or the rear wheel 32, thereby suppressing power consumption. f With the rear torque T r The requested torque T is distributed more than req , the electric vehicle 100 is actually driven by the front wheels 22 in a two-wheel drive mode. That is, in the present embodiment, the torque distribution in the power consumption reduction mode is in principle T f :T r≈100:0. However, the torque distribution unit 42 further adjusts the torque distribution in the power consumption reduction mode based on the vehicle speed V.

[0046] The driving performance mode is a control mode in which the torque distribution unit 42 performs torque distribution with priority given to driving performance. Specifically, when the control mode is the driving performance mode, the torque distribution unit 42 adjusts the torque distribution so that the electric vehicle 100 is in a four-wheel drive state (or a state close thereto), thereby improving the driving performance of the electric vehicle 100. Therefore, when the control mode is the driving performance mode, the torque distribution unit 42 adjusts the torque distribution so that the electric vehicle 100 is in a four-wheel drive state (or a state close thereto), thereby improving the driving performance of the electric vehicle 100. f Less requested torque T req , for the rear torque T r The requested torque T is allocated more req In this embodiment, the torque distribution of the driving performance mode is in principle T f :T r =50:50. However, the torque distribution unit 42 further adjusts the torque distribution unit 42 based on the longitudinal acceleration Ac1, the lateral acceleration Ac2, and the road surface gradient ψ road etc. and adjust the torque distribution of the driving performance mode.

[0047] The driver sets the control mode related to torque distribution using a control switch (not shown) or the like. In the present embodiment, the control mode is set to the power consumption suppression mode in principle. Furthermore, when the driving performance mode is clearly set using a control switch or the like, the control mode is set to the driving performance mode.

[0048] However, even when the power consumption suppression mode is selected, the torque distribution unit 42 (controller 14) may automatically and forcibly cancel the power consumption suppression mode. In other words, the torque distribution unit 42 may switch the control mode from the power consumption suppression mode to the driving performance mode. This is to maintain the previous torque T f After the torque T r The sum of the torque (hereinafter referred to as total torque ΣT) and the requested torque T req equal, and protect the front drive system 11 from overheating.

[0049] The automatic and mandatory change of the control mode is temporary in principle. When the possibility of damage to the front drive system 11 due to overheating is reduced, the torque distribution unit 42 (controller 14) automatically restores the control mode to the power consumption suppression mode. That is, when the torque distribution unit 42 automatically switches the control mode to the driving performance mode without the driver's selection, when it is not necessary to maintain the driving performance mode, the torque distribution unit 42 automatically switches the control mode from the temporarily set driving performance mode to the original power consumption suppression mode.

[0050] The torque distribution unit 42 switches the control mode automatically based on the temperature of the front drive system 11 or the rear drive system 12. In the present embodiment, when the control mode is the power consumption suppression mode, the front drive system 11 is operated intensively, and may overheat depending on the driving scene. Therefore, the torque distribution unit 42 switches the control mode automatically based on the temperature of the front drive system 11. In addition, the front motor 21 and the front inverter 23 in the front drive system 11 may overheat due to the power consumption suppression mode. Therefore, the torque distribution unit 42 switches the control mode automatically based on the temperature of the front motor 21. f-MOT and the temperature θ of the front inverter 23 f-INV The above-mentioned automatic control mode switching is performed.

[0051] In addition, as described above, the electric vehicle 100 is substantially in a two-wheel drive state according to the selection of the power consumption suppression mode, and is in a four-wheel drive state according to the selection of the driving performance mode. Therefore, in the present embodiment, the switching of the control mode involving torque distribution is equivalent to the switching between two-wheel drive and four-wheel drive. However, according to the power consumption suppression mode, it is not necessary to strictly or always form a two-wheel drive state. In the power consumption suppression mode, for example, sometimes the control mode is adjusted to T f :T r =80:20 equal torque distribution.

[0052] Figure 3 4 is a block diagram showing the structure of the torque distribution unit 42. Figure 3 As shown, the first torque distribution calculation unit 51 , the second torque distribution calculation unit 52 , the output limit calculation unit 53 , the torque distribution selection unit 54 , and the change rate limiter 55 are provided.

[0053] The first torque distribution calculation unit 51 is based on the requested torque T req and vehicle speed V, the first front torque command value T f1 * and the first post torque command value T r1 *Calculation is performed. 1st torque command value T f1 * and the first post torque command value T r1 *Distribution of the requested torque T for torque distribution in the power consumption suppression mode req The front torque T f After the torque T r That is, the first torque distribution calculation unit 51 calculates the torque command value for the power consumption suppression mode.

[0054] As described above, in this embodiment, the torque distribution in the power consumption reduction mode is T f :T r ≈100:0, so the first front torque command value Tf1 *Approximately equivalent to the requested torque T req , the first post torque command value T r1 * is substantially zero. However, the first torque distribution calculation unit 51 performs correction according to the vehicle speed V, thereby actually adjusting the first front torque command value T for suppressing power consumption. f1 * and the first post torque command value T r1 *Calculate the first torque command value T f1 * and the first post torque command value T r1 *It is called the torque command value for power consumption suppression mode (T f1 *, T r1 *).

[0055] The second torque distribution calculation unit 52 calculates the torque based on the requested torque T req , front and rear acceleration Ac1, lateral acceleration Ac2 and road slope ψ road , for the second front torque command value T f2 * and the second rear torque command value T r2 *Calculation is performed. Second front torque command value T f2 * and the second rear torque command value T r2 *To distribute the requested torque T with respect to the torque distribution in the driving performance mode req The front torque T f After the torque T r That is, the second torque distribution calculation unit 52 calculates the torque command value for the driving performance mode.

[0056] As mentioned above, in this embodiment, the torque distribution of the driving performance mode is in principle T f :T r =50:50, so the second front torque command value T f2 * and the second rear torque command value T r2 *Approximately the requested torque T req However, the second torque distribution calculation unit 52 calculates the torque distribution according to the longitudinal acceleration Ac1, the lateral acceleration Ac2 and the road surface gradient ψ road By correcting this, the second front torque command value T which actually improves the running performance is adjusted. f2 * and the second rear torque command value T r2 *Calculate the second torque command value T f2 * and the second rear torque command value T r2 *It is called the torque command value for the driving performance mode (T f2 *, T r2 *).

[0057] The output limit calculation unit 53 determines the front torque T that should be set to protect against damage caused by overheating based on the temperature of the front drive system 11 or the temperature of the rear drive system 12. f Or rear torque T r In the present embodiment, when the control mode is the power consumption suppression mode, the front drive system 11 is operated intensively, and may overheat depending on the driving scene. Therefore, the output limitation calculation unit 53 calculates the output limitation based on the temperature θ of the front motor 21. f-MOT and the temperature θ of the front inverter 23 f-INV , for overheat protection against the allocated front torque T f The upper limit value (hereinafter referred to as the upper limit torque UL) is set FT ) to perform the operation.

[0058] Upper limit torque UL FT is a variable value, depending on the temperature θ of the front motor 21 f-MOT and the temperature θ of the front inverter 23 f-INV Specifically, when it is impossible to exceed the heat resistance temperature of the front motor 21 and the front inverter 23, the upper limit torque UL FT is substantially equal to the maximum output torque of the front motor 21. On the other hand, when the temperature θ of the front motor 21 f-MOT If the heat resistance temperature of the front motor 21 is exceeded, or the temperature θ of the front inverter 23 is f-INV If the heat-resistant temperature of the front inverter 23 is likely to be exceeded, the upper limit torque UL FT The value of the maximum output torque of the front motor 21 is reduced to a value less than the maximum output torque of the front motor 21. f-MOT and the temperature θ of the front inverter 23 f-INV The upper limit torque UL FT The setting method is described in detail.

[0059] Upper limit torque UL FT Used to limit the distributed front torque T f In addition, in this embodiment, the upper limit torque UL FT The upper limit torque UL is used as a criterion for automatically and forcibly canceling the power consumption suppression mode and switching the control mode from the power consumption suppression mode to the driving performance mode. FT Used as a criterion for automatically returning the control mode to the power consumption suppression mode.

[0060] The torque distribution selection unit 54 selects and outputs a torque command value (T ) for the power consumption reduction mode as a torque command value for controlling the electric vehicle 100. f1 *, T r1*) or the torque command value for the driving performance mode (T f2 *, T r2 Thereby, the torque distribution selection unit 54 selects the torque distribution to be applied in the control of the electric vehicle 100 .

[0061] When the driving performance mode is set by the driver, the torque distribution selection unit 54 selects the torque command value (T ) for the driving performance mode as the torque command value for controlling the electric vehicle 100. f2 *, T r2 *). Thus, the torque distribution selection unit 54 sets the torque distribution of the electric vehicle 100 to the torque distribution of the running performance mode. In this case, the control mode is the running performance mode.

[0062] When the power consumption reduction mode is set by the driver or when the driving performance mode is not explicitly selected, the torque distribution selection unit 54 selects the torque command value (T ) for the power consumption reduction mode as the torque command value for controlling the electric vehicle 100. f1 *, T r1 *). As a result, the torque distribution selection unit 54 sets the torque distribution of the electric vehicle 100 to the torque distribution of the power consumption suppression mode. In this case, the control mode is the power consumption suppression mode. In addition, "the case where the driving performance mode is not clearly selected" refers to the case where the control mode is initially set or automatically set without the driver setting the power consumption suppression mode and the driving performance mode, and the case where the driving performance mode can be set using an operation button not shown in the figure but the operation button is not operated. That is, even if the power consumption suppression mode is not set by the driver, it is sometimes automatically changed to the power consumption suppression mode when the driver does not set the driving performance mode.

[0063] Furthermore, in the present embodiment, when the control mode is the power consumption suppression mode, the torque distribution selection unit 54 may select the upper limit torque UL according to the upper limit torque UL. FT The control mode is automatically and forcibly switched to the driving performance mode due to changes in the vehicle's driving conditions.

[0064] Specifically, at the upper limit torque UL FT After decreasing according to the change in the temperature of the front drive system 11, the front torque T f The output is limited to the upper torque limit UL FT Previously, the torque distribution selection unit 54 switched the control mode to the running performance mode.

[0065] In the present embodiment, the criterion for determining whether to cancel the power consumption suppression mode and switch to the running performance mode is the upper limit torque UL FT The torque distribution selection unit 54 determines the upper limit torque UL FTThe first threshold TH1 is set to the upper limit torque UL FT When the power consumption reduction mode is equal to or less than the first threshold value TH1, the power consumption reduction mode is cancelled and the driving performance mode is switched. The first threshold value TH1 is a threshold value for determining whether to cancel the power consumption reduction mode (power consumption reduction mode cancellation threshold value).

[0066] As described above, when the front motor 21 and the front inverter 23 are likely to exceed the heat-resistant temperature, the upper limit torque UL FT The first threshold TH1 is set to detect the possibility that the front motor 21 and the front inverter 23 exceed the heat-resistant temperature. Therefore, the first threshold TH1 is set to a value in the range lower than the maximum output torque of the front motor 21, for example, to a value near the maximum output torque. The specific value of the first threshold TH1 is predetermined by experiments or simulations.

[0067] Furthermore, in the present embodiment, when the control mode is automatically and forcibly switched from the power consumption suppression mode to the running performance mode, the torque distribution selection unit 54 may automatically return the control mode to the power consumption suppression mode.

[0068] Specifically, the upper limit torque UL FT When it is determined that the front motor 21 and the front inverter 23 are unlikely to exceed the heat-resistant temperature due to the increase in the temperature of the front drive system 11 , the torque distribution selection unit 54 automatically returns the control mode to the power consumption suppression mode.

[0069] In the present embodiment, the torque distribution selection unit 54 determines the upper limit torque UL FT The second threshold TH2 is set to the upper limit torque UL FT When it is greater than or equal to the second threshold value TH2, the control mode is restored to the power consumption suppression mode. The second threshold value TH2 is a threshold value that becomes a restoration condition to the power consumption suppression mode (power consumption suppression mode restoration threshold value). Therefore, the second threshold value TH2 is set to a value greater than or equal to the first threshold value TH1 and less than or equal to the maximum output torque of the front motor 21. In particular, in the present embodiment, the second threshold value TH2 is set to a value greater than the first threshold value TH1. As a result, the automatic switching and restoration of the control mode has a hysteresis, thereby suppressing oscillation. That is, it is difficult to repeatedly switch and restore the control mode in a short period of time. In addition, the specific value of the second threshold value TH2 is predetermined by experiments or simulations.

[0070] The rate limiter 55 limits the front torque T f After the torque T r Specifically, the rate of change limiter 55 is a torque command value (T f1*, T r1 *) or the torque command value for the driving performance mode (T f2 *, T r2 *) to limit the amount of change per unit time. Thus, the rate of change limiter 55 makes the front torque T f After the torque T r Changes smoothly.

[0071] In the present embodiment, the change rate limiter 55 acts when the control mode is switched from the power consumption suppression mode to the driving performance mode and thereafter, when the control mode is restored to the power consumption suppression mode. That is, in the present embodiment, the change rate limiter 55 limits the front torque T when the torque distribution selection unit 54 substantially switches the control mode. f After the torque T r As a result, even at the start of traveling or during traveling, the control mode can be switched smoothly without causing vibration or the like in the electric vehicle 100.

[0072] Figure 4 is a block diagram showing the structure of the output limit calculation unit 53. Figure 4 As shown, the output limit calculation unit 53 includes a first limit calculation unit 61 , a second limit calculation unit 62 , and an upper limit torque calculation unit 63 .

[0073] The first limit calculation unit 61 calculates the temperature θ of the front motor 21 based on the temperature θ of the front motor 21. f-MOT , for the front torque T f The upper limit value of the front torque T (hereinafter referred to as the first upper limit torque Lim1) is calculated. The first upper limit torque Lim1 is to prevent the front motor 21 from becoming overheated. f The limit value implemented.

[0074] The second limit calculation unit 62 calculates the temperature θ of the front inverter 23 based on the temperature θ f-INV , for the front torque T f The second upper limit torque Lim2 is calculated to prevent the front inverter 23 from becoming overheated. f The limit value implemented.

[0075] The upper limit torque calculation unit 63 determines the smaller of the first upper limit torque Lim1 and the second upper limit torque Lim2 as the upper limit torque T to be adjusted. f The final upper limit torque UL implemented FT This prevents the front motor 21 and the front inverter 23 from becoming overheated.

[0076] Figure 5 is the temperature θ of the front motor 21 f-MOTA schematic diagram of the output limitation method. Figure 5 As shown, the temperature θ of the front motor 21 f-MOT When the torque T is low enough to avoid overheat protection, the first upper limit torque Lim1 is 100%. Therefore, from the perspective of protecting the front motor 21 from overheating, the front motor 21 can maximize the front torque T f Output.

[0077] The temperature θ of the front motor 21 f-MOT In the case where the temperature of the front motor 21 rises relative to a temperature that is low enough to not require overheat protection, if the temperature θ f-MOT When the temperature exceeds A1, the first upper limit torque Lim1 is set according to the temperature θ of the front motor 21. f-MOT The temperature θ of the front motor 21 is set to gradually decrease along the line L1. f-MOT If the temperature exceeds A1, the output front torque T is limited from the viewpoint of protecting the front motor 21 from overheating. f .

[0078] In particular, in this embodiment, if the temperature θ of the front motor 21 is f-MOT is greater than or equal to the temperature A2, the first upper limit torque Lim1 is 0%. f-MOT If the temperature is greater than or equal to the temperature A2, the front motor 21 cannot output torque in order to protect the front motor 21 from overheating. The temperatures A1, A2 and the shape of the line L1 are predetermined according to the specific heat dissipation properties of the front motor 21.

[0079] On the other hand, the temperature θ of the front motor 21 f-MOT When the first upper limit torque Lim1 is reduced from the state of 0%, if the temperature θ of the front motor 21 is f-MOT If the temperature is lower than B2, the first upper limit torque Lim1 is set according to the temperature θ of the front motor 21. f-MOT The temperature θ of the front motor 21 is set to gradually increase along the line L2. f-MOT When the temperature is equal to or lower than the temperature B1 along the line L2, the first upper limit torque Lim1 is set to return to 100%.

[0080] The temperature B2 is at least set to be less than or equal to the temperature A2, and can be set to a value equal to the temperature A2. In addition, the line L2 can be set to be equal to the line L1. However, in this embodiment, the temperature B2 is at least set to a value less than the temperature A2, and as a result, the line L2 is different from the line L1. Therefore, the first upper limit torque Lim1 is relative to the temperature θ of the front motor 21. f-MOTThe first upper limit torque Lim1 has hysteresis in this way because the first upper limit torque Lim1 is transmitted through the final upper limit torque UL FT It is used to determine the switching of control modes.

[0081] For example, when the temperature θ of the front motor 21 is f-MOT In the case where the switching of the control mode is dominant, if the temperature θ of the front motor 21 is f-MOT When the temperature exceeds A1, the control mode is immediately forcibly switched from the power consumption suppression mode to the driving performance mode. Furthermore, by switching the control mode to the driving performance mode, if the distributed front torque T f is reduced, the load of the front motor 21 is reduced, and the temperature θ of the front motor 21 is reduced. f-MOT Turning to a decreasing trend.

[0082] At this time, if the first upper limit torque Lim1 does not have the above-mentioned hysteresis, the first upper limit torque Lim1 rises along the line L1. f-MOT When the first upper limit torque Lim1 returns to 100%, the control mode returns to the power consumption suppression mode. f As a result, the temperature θ of the front motor 21 increases. f-MOT Therefore, when the first upper limit torque Lim1 does not have the above-mentioned hysteresis, even if the control mode is restored to the power consumption suppression mode, it may be forcibly switched to the running performance mode again immediately thereafter.

[0083] That is, the first upper limit torque Lim1 is provided with the above-mentioned hysteresis in order to suppress hunting associated with automatic switching and recovery of the control mode. The temperatures B1 and B2 and the shape of the line L2 are predetermined by experiments, simulations, or the like.

[0084] In addition, the temperature θ of the front motor 21 f-MOT When the first upper limit torque Lim1 starts to decrease while descending along the line L1, the first upper limit torque Lim1 is maintained at the temperature θ of the front motor 21 until it reaches a point on the line L2 or returns to a point on the line L1. f-MOT For example, the first upper limit torque Lim1 decreases along the line L1, and the temperature θ of the front motor 21 f-MOT The starting temperature T relative to point α α Then, the temperature θ of the front motor 21 f-MOT When the temperature of the front motor 21 decreases further, f-MOT Change to temperature T βAnd until reaching point β on line L2, the value of the first upper limit torque Lim1 at point α (50%) is maintained. This is to suppress hunting associated with automatic switching and recovery of the control mode.

[0085] Similarly, the temperature θ of the front motor 21 f-MOT When the first upper limit torque Lim1 starts to rise in the middle of rising along the line L2, the first upper limit torque Lim1 is maintained at the temperature θ of the front motor 21 until reaching a point on the line L1 or returning to a point on the line L2. f-MOT The value at which the rise starts.

[0086] Figure 6 is the temperature θ of the front inverter 23 f-INV A schematic diagram of the output limitation method. Figure 6 As shown, the second upper limit torque Lim2 is set according to the characteristics of the front inverter 23 based on the same principle as the first upper limit torque Lim1 described above.

[0087] The temperature θ of the front inverter 23 f-INV When the torque increases, the temperature C1 at which the second upper limit torque Lim2 starts to decrease from 100%, the lowest temperature C2 at which the second upper limit torque Lim2 is set to 0%, and the shape of the line during this period are preset according to the heat resistance temperature of the front inverter 23 (especially the switching element). f-INV When reduced, the temperature D2 at which the second upper limit torque Lim2 starts to rise from 0%, the temperature D1 at which the second upper limit torque Lim2 returns to 100%, and the shape of the line during this period are predetermined through experiments or simulations in order to suppress the oscillations involved in the automatic switching and recovery of the control mode.

[0088] Next, the automatic switching and recovery of the control mode of the electric vehicle 100 configured as described above will be described. In the following, it is assumed that the driving performance mode is not set by the driver and the control mode is set to the power consumption reduction mode in principle.

[0089] Figure 7 FIG. 2 is a flowchart for the case where the power consumption suppression mode is canceled and the control mode is switched to the driving performance mode. Figure 7 As shown, in step S10, the first torque distribution calculation unit 51 calculates the torque command value (T f1 *, T r1 In step S11, the second torque distribution calculation unit 52 calculates the torque command value (T f2 *, T r2 In step S12, the temperature θ of the front motor 21 is obtained.f-MOT and the temperature θ of the front inverter 23 f-INV Then, in step S13, the output limit calculation unit 53 calculates the temperature θ of the front motor 21 based on the temperature θ of the front motor 21. f-MOT and the temperature θ of the front inverter 23 f-INV , for the upper limit torque UL FT Perform calculations.

[0090] Then, in step S14, the torque distribution selection unit 54 sets the upper limit torque UL FT The torque is compared with the first threshold value TH1. In step S14, if it is determined that the upper limit torque UL FT If the torque command value is less than or equal to the first threshold value TH1, the process proceeds to step S15, and the torque distribution selection unit 54 sets the torque command value T f * and the torque command value T r * The torque command value to be output is the torque command value for the power consumption reduction mode (T f1 *, T r1 *) Torque command value for switching to driving performance mode (T f2 *, T r2 *) In step S16, the change rate limiter 55 performs a change rate limiting process to make the switching smooth.

[0091] Therefore, in order to protect the front drive system 11 from overheating, the front torque T f Limited to upper torque limit UL FT Previously, the control mode related to torque distribution was automatically and forcibly switched to the driving performance mode. Moreover, compared with the case where the control mode remains in the power consumption suppression mode, the requested torque T req Forward torque T f As a result, the load on the front drive system 11 is reduced and the heat generation thereof is suppressed. Therefore, the front drive system 11 is reliably protected from overheating. In addition, in the driving performance mode, the requested torque T req There will be no over or under torque T f After the torque T r Therefore, even if the control mode is switched, the electric vehicle 100 can continue to output the requested torque T req .

[0092] Furthermore, in step S14, when it is determined that the upper limit torque UL FT If the torque command value (T ) for the power consumption suppression mode is greater than the first threshold value TH1, the possibility that the front drive system 11 will fall into an overheated state is low even if the power consumption suppression mode is continued as it is. Therefore, the process proceeds to step S17, and the torque distribution selection unit 54 sets the torque command value (T ) for the power consumption suppression mode to f1 *, Tr1 *) should be used as the previous torque command value T f * and the torque command value T r *The torque command value output is output. Thus, the power consumption suppression mode is continued.

[0093] Figure 8 This is a flowchart for the case where the power consumption reduction mode is restored. Figure 8 As shown in step S20, after the automatic switching from the power consumption suppression mode to the driving performance mode, the torque command value (T f1 *, T r1 In addition, in step S21, the torque command value (T f2 *, T r2 *) is calculated. Similarly, in step S22, the temperature θ of the front motor 21 is obtained. f-MOT and the temperature θ of the front inverter 23 f-INV In step S23, the upper limit torque UL FT Perform calculations.

[0094] Then, in step S24, the torque distribution selection unit 54 sets the upper limit torque UL FT The torque is compared with the second threshold value TH2. In step S24, if it is determined that the upper limit torque UL FT If the value is greater than or equal to the second threshold value TH2, the process proceeds to step S25, where the torque command value T f * and the torque command value T r * The torque command value to be output is switched to the torque command value for the power consumption reduction mode (T f1 *, T r1 *) In step S26, the change rate limiter 55 performs a change rate limiting process to make the switching smooth.

[0095] Thus, the control mode related to torque distribution is switched to the power consumption suppression mode when the possibility of the front drive system 11 falling into an overheating state decreases. Therefore, the period during which the control mode is forcibly switched to the driving performance mode is suppressed to a minimum, not only is it unlikely that the front drive system 11 will fall into an overheating state, but power consumption is also suppressed.

[0096] Fig. 9 1 is a graph schematically showing the change of the temperature and torque of each motor and the vehicle speed V of the electric vehicle of the comparative example. The electric vehicle of the comparative example continues the power consumption suppression mode unless the driving performance mode is set by the driver. In addition, regarding the electric vehicle of the comparative example, when overheat protection of the front drive system 11 is required, the front torque T distributed by the torque distribution in the power consumption suppression mode isf (The first front torque command value T f1 *) by upper limit torque UL FT In addition, in order to simplify the description below, according to the temperature θ of the front motor 21 f-MOT The necessity of overheat protection is determined. In addition, the accelerator opening A PO Constant, as a result, the required torque T req Also constant.

[0097] like Fig. 9 As shown in (A), regarding the electric vehicle of the comparative example, by continuing the power consumption suppression mode, if the temperature θ of the front motor 21 f-MOT If the temperature rises and exceeds A1, Fig. 9 (B) shows the upper limit torque UL FT Also, if the upper limit torque UL FT Reduced to less than or equal to the requested torque T req Distributed front torque T f , then the front torque T f Limit to upper torque limit UL FT As a result, the load of the front motor 21 is forcibly reduced, and the heat generation thereof is suppressed. As a result, the front motor 21 is protected from overheating.

[0098] However, the front torque T f Limit to upper torque limit UL FT , so that the front torque T f and the rear torque T r The sum of the total torque ΣT is lower than the requested torque T req Therefore, when the front motor 21 is protected from overheating, the electric vehicle of the comparative example cannot continuously output the requested torque T req As a result, Fig. 9 As shown in (C), for the electric vehicle of the comparative example, if the front torque T f Start limiting to the upper torque limit UL FT , the vehicle speed V will decrease.

[0099] Fig.10 1 is a graph schematically showing the temperature and torque of each motor and the change of the vehicle speed of the electric vehicle 100 according to the present embodiment. Fig.10 (A) shows the temperature θ of the front motor 21 f-MOT If the temperature rises and exceeds A1, Fig.10 (B) shows the upper limit torque UL FT Start lowering.

[0100] Then, regarding the electric vehicle of the comparative example, as described above, before the torque T f Limit to upper torque limit UL FT In the electric vehicle 100 of the present embodiment, the front torque Tf is limited to the upper limit torque UL FT Before, at the upper torque limit UL FT When the control mode is less than or equal to the first threshold value TH1, the control mode is switched from the power consumption suppression mode to the driving performance mode. Fig.10 (B) shows the front torque T f Reduce, rear torque T r As a result, the load of the front motor 21 is forcibly reduced, and the heat generation thereof is suppressed. As a result, the front motor 21 is protected from overheating.

[0101] Furthermore, regarding the electric vehicle 100 of the present embodiment, the previous torque T f Limit to upper torque limit UL FT Previously, the control mode was switched to the driving performance mode, thereby maintaining the total torque ΣT at the requested torque T req Therefore, if Fig. 9 As shown in (C), regarding electric vehicle 100 of the present embodiment, vehicle speed V is maintained.

[0102] Fig.11 1 is a graph schematically showing the temperature and torque of each motor and the change in vehicle speed when the electric vehicle 100 according to the present embodiment returns to the power consumption reduction mode. Fig.11 (A) shows that if the temperature θ of the front motor 21 f-MOT For example, if the temperature is sufficiently reduced to a level less than or equal to temperature B2, then Fig.11 As shown in (B), the upper limit torque UL FT Start to recover (rise). And, if the upper limit torque UL FT If the value is restored to be greater than or equal to the second threshold value TH2, it is determined that the need for overheat protection of the front motor 21 is reduced, and the control mode is restored to the power consumption suppression mode. In both the power consumption suppression mode and the driving performance mode, the front torque T is not excessively or insufficiently applied. f After the torque T r Distributed request torque T req As described above, when the control mode is restored to the power consumption suppression mode, the total torque ΣT is also maintained at the requested torque T req Therefore, in the electric vehicle 100 according to the present embodiment, the vehicle speed V is maintained even when the control mode is returned to the electric power consumption suppression mode.

[0103] Furthermore, in the above embodiment, for the upper limit torque UL FTThe first threshold TH1 and the second threshold TH2 are set, and the upper limit torque UL FT The same threshold value is set for the temperature of the front drive system 11, and the temperature of the front drive system 11 can be used as a criterion for the automatic switching of the control mode. However, as in the above embodiment, the temperature of multiple parts of the front drive system 11 is detected, and the upper limit torque UL is determined by comprehensively considering the above temperature. FT When the upper limit torque UL FT The automatic switching of the control mode is relatively simple and direct. FT When used as a judgment criterion, the control mode can be automatically switched particularly accurately.

[0104] In addition, the automatic switching control of the control mode involved in the above embodiment is particularly suitable for driving scenes with high load on the front drive system 11. This is because, according to the power consumption suppression mode, the front drive system 11 is intensively operated, and when the temperature of the front drive system 11 has already risen, the possibility of the front drive system 11 exceeding the heat-resistant temperature increases in driving scenes with further high load.

[0105] Specifically, the automatic switching control of the control mode involved in the above embodiment is particularly suitable when the electric vehicle 100 is traveling on an uphill road, when the electric vehicle 100 is towing another vehicle, or when the electric vehicle 100 is traveling on an uphill road while towing another vehicle. That is, when the control mode is the power consumption suppression mode and the vehicle is traveling on an uphill road, the upper limit torque UL FT After the reduction, the front torque T f The output is limited to the upper torque limit UL FT As described above, it is preferred that the control mode be automatically and forcibly switched to the driving performance mode. In addition, when the control mode is the power consumption suppression mode and the vehicle is towing other vehicles, the upper limit torque UL FT After the reduction, the front torque T f The output is limited to the upper torque limit UL FT As described above, as in the above-described embodiment, it is preferable that the control mode be automatically and forcibly switched to the driving performance mode.

[0106] Based on the road slope ψ road Whether the electric vehicle 100 is traveling on an uphill road can be determined by the setting of a traction switch (not shown) or the load of other vehicles involved in the traction unit.

[0107] [Modifications]

[0108] In addition, the electric vehicle 100 of the above embodiment is in a two-wheel drive state using the front wheels 22 in the power consumption reduction mode, but the present invention is not limited thereto. The electric vehicle 100 may be configured to be in a two-wheel drive state using the rear wheels 32 in the power consumption reduction mode (or T f :T r =20:80, etc., close to a two-wheel drive state). Therefore, regarding the automatic switching control of the control mode, the electric vehicle 100 that changes to a two-wheel drive state using the front wheels 22 in the power consumption suppression mode is substantially equivalent to the electric vehicle of the modified example that changes to a two-wheel drive state using the rear wheels 32 in the power consumption suppression mode. Therefore, the electric vehicle of the modified example can be configured as follows. That is, in the power consumption suppression mode, the front torque T f Compared with the rear torque T r The requested torque T is allocated more req In the driving performance mode, compared with the power consumption suppression mode, less requested torque T is allocated to the rear torque. req The temperature of the rear drive system 12 driving the rear wheels 32 is obtained. r The upper limit value UL is set according to the temperature of the rear drive system 12 RT , thereby limiting the rear torque T r When the control mode is the power consumption suppression mode, the upper limit value UL RT After the reduction, the rear torque T r The output is limited to the upper limit value UL RT That is, the electric vehicle of this modification has the roles of the front wheels 22 and the front drive system 11 and the rear wheels 32 and the rear drive system 12 interchanged with the electric vehicle 100 of the above embodiment.

[0109] However, if the two-wheel drive state (front-wheel drive) using the front wheels 22 is compared with the two-wheel drive state (rear-wheel drive) using the rear wheels 32, the two-wheel drive state (front-wheel drive) using the front wheels 22 can be driven more stably on all road surfaces such as slippery roads without relying on the driver's skills. Therefore, in the power consumption suppression mode, it is particularly preferable to configure the electric vehicle 100 in a two-wheel drive state using the front wheels 22 as in the above embodiment.

[0110] As described above, in the control method of the electric vehicle according to the above-mentioned embodiment and the modified example, as the torque generated at the front wheel 22, that is, the front torque T f and the torque generated at the rear wheel 32, that is, the rear torque T r Distributed request torque T reqAnd adjust the requested torque T req The control mode of the distribution includes a power consumption suppression mode that prioritizes the suppression of power consumption and a driving performance mode that prioritizes the driving performance. Regarding the control method of the electric vehicle, in the power consumption suppression mode, the front torque T f Or rear torque T r The requested torque T is allocated more to either req , in the driving performance mode, the requested torque T is allocated more in the power consumption suppression mode. req The front torque T f Or rear torque T r In addition, the front drive system 11 driving the front wheels 22 or the rear drive system driving the rear wheels 32 is obtained in accordance with the requested torque T which is allocated more in the power consumption reduction mode. req The front torque T f Or rear torque T r The temperature of a corresponding drive system. In the power consumption suppression mode, the requested torque T is allocated more. req The front torque T f Or rear torque T r Set an upper limit value (UL) corresponding to the temperature of the corresponding drive system. FT or UL RT ), thereby limiting the allocation of a larger requested torque T in the power consumption suppression mode. req The front torque T f Or rear torque T r Furthermore, when the control mode is the power consumption suppression mode, the upper limit value (UL FT or UL RT ) is reduced, the requested torque T is allocated more in the power consumption suppression mode. req The front torque T f Or rear torque T r Limited to this upper limit (UL FT or UL RT ), switch the control mode to driving performance mode.

[0111] Thus, when the control mode is the power consumption suppression mode, the upper limit value (UL FT or UL RT ) is reduced, the requested torque T is allocated more req The front torque T f Or rear torque T r The output is limited to the upper limit value (UL FT or UL RT ) before, the control mode is switched to the driving performance mode, thereby reliably protecting the larger distribution of the requested torque T reqThe front drive system 11 or the rear drive system 12 is protected from overheating, and the total torque ΣT is maintained at the requested torque T req That is, according to the control method of the electric vehicle involved in the above-mentioned embodiment and the modified example, the electric vehicle 100 and the electric vehicle of the modified example can protect the drive system from overheating and drive with the requested torque even when the torque distribution is adjusted to a distribution that suppresses power consumption.

[0112] More specifically, for example, the control method of the electric vehicle according to the above embodiment is a control method of the electric vehicle 100 in which the front torque T generated at the front wheel 22 is f and the torque generated at the rear wheel 32, that is, the rear torque T r Distributed request torque T req And adjust the requested torque T req The control mode of the distribution includes a power consumption suppression mode that prioritizes the suppression of power consumption and a driving performance mode that prioritizes the driving performance. Regarding the control method of the electric vehicle 100, in the power consumption suppression mode, the rear torque T r Compared with the front torque T f The requested torque T is allocated more req In the driving performance mode, the front torque T is increased compared to the power consumption suppression mode. f Less requested torque T req In addition, the temperature of the front drive system 11 driving the front wheels 22 is obtained, and the front torque T f The upper limit value (upper limit torque UL ) corresponding to the temperature of the front drive system 11 is set. FT ), thereby limiting the front torque T f Furthermore, when the control mode is the power consumption suppression mode, the upper limit value (upper limit torque UL FT ) is reduced, the front torque T f The output is limited to the upper limit value (upper limit torque UL FT ), switch the control mode to driving performance mode.

[0113] Thus, when the control mode is the power consumption suppression mode, the upper limit value (upper limit torque UL FT ) is reduced, the front torque T f The output is limited to the upper limit value (upper limit torque UL FT ), the control mode is switched to the driving performance mode, thereby reliably protecting the front drive system 11 from overheating and maintaining the total torque ΣT at the requested torque T reqThat is, according to the electric vehicle control method according to the above embodiment, even when the torque distribution is adjusted to suppress power consumption, the electric vehicle 100 can be driven with the requested torque while protecting the drive system from overheating.

[0114] Regarding the control method of the electric vehicle according to the above embodiment, the temperature of the front drive system 11 is the temperature at which the front torque T f The temperature of the motor (front motor 21) θ f-MOT , the temperature θ of the inverter (front inverter 23) driving the motor f-INV Or the temperature of the motor (θ f-MOT ) and the inverter temperature (θ f-INV )Both of these.

[0115] Regarding the front drive system 11, the parts that are particularly prone to overheating are the front motor 21 and the front inverter 23. Therefore, as described above, the temperature θ of the front motor 21 is obtained as the temperature of the front drive system 11. f-MOT , the temperature θ of the front inverter 23 f-INV , the control mode is automatically switched based on the above temperature, thereby easily and particularly accurately protecting the front drive system 11 from overheating.

[0116] Regarding the control method of the electric vehicle according to the above embodiment, the upper limit value (upper limit torque UL FT ), a first threshold value TH1 is pre-set as a switching condition from the power consumption suppression mode to the driving performance mode. FT ) is less than or equal to the first threshold value TH1, the control mode is switched from the power consumption suppression mode to the driving performance mode.

[0117] In this way, if the upper limit torque UL FT By setting the automatic switching control of the control mode as the judgment criterion, even when the front drive system 11 has a plurality of parts to be monitored for overheat protection, the control mode can be switched from the power consumption suppression mode to the driving performance mode easily and particularly reliably.

[0118] Regarding the control method of the electric vehicle according to the above embodiment, when the control mode is switched, the front torque T is limited. f After the torque T r The rate of change.

[0119] In this way, when the control mode is switched, if the change rate limiter 55 is used to limit the front torque T f After the torque T rIf the rate of change of is controlled, the control mode can be switched automatically and forcibly smoothly without causing vibration of the electric vehicle 100.

[0120] In the control method of the electric vehicle according to the above embodiment, after the control mode is switched from the power consumption suppression mode to the driving performance mode, the upper limit value (upper limit torque UL FT ) increases, the control mode is switched from the driving performance mode to the power consumption suppression mode.

[0121] In this way, after the control mode is automatically and forcibly switched to the driving performance mode, if the upper limit torque UL FT When the front drive system 11 is judged to be unlikely to overheat due to the increase in the power consumption suppression mode, the control mode is forcibly switched to the driving performance mode during which the period is suppressed to a minimum. As a result, as long as the front drive system 11 is unlikely to overheat, it is easy to suppress power consumption.

[0122] Regarding the control method of the electric vehicle according to the above embodiment, the upper limit value (upper limit torque UL FT ), a second threshold value TH2 is pre-set as a condition for returning to the power consumption suppression mode, and an upper limit value (upper limit torque UL FT ) is greater than or equal to the second threshold value TH2, the control mode is restored to the power consumption suppression mode.

[0123] In this way, if the upper limit torque UL FT By setting this as a criterion for returning to the power consumption reduction mode, even when the front drive system 11 has a plurality of parts that should be monitored for overheat protection, the control mode can be easily and particularly reliably returned to the power consumption reduction mode.

[0124] Regarding the control method of the electric vehicle according to the above embodiment, when the control mode is the power consumption suppression mode and the vehicle is traveling on an uphill road, the upper limit value (upper limit torque UL FT ) is reduced, the front torque T f The output is limited to the upper limit value (upper limit torque UL FT ), switch the control mode to driving performance mode.

[0125] Driving uphill in the power consumption suppression mode places a higher load on the front drive system 11 than driving on a flat road. Therefore, for example, when driving uphill at high speed in the power consumption suppression mode while the temperature of the front drive system 11 has risen, the possibility of the front drive system 11 overheating is particularly high. Therefore, as described above, when driving uphill, the electric vehicle 100 can automatically and forcibly switch the control mode to reduce the required torque T req output and more reliably protect the front drive system 11 from overheating.

[0126] Regarding the control method of the electric vehicle according to the above embodiment, when the control mode is the power consumption suppression mode and the electric vehicle is traveling by towing another vehicle, after the upper limit value is lowered, the front torque T f The output is limited to the upper limit value (upper limit torque UL FT ), switch the control mode to driving performance mode.

[0127] In the case of towing travel performed in the state where the control mode is the power consumption suppression mode, a particularly high load is applied to the front drive system 11. Therefore, for example, when towing travel is performed at a high speed according to the power consumption suppression mode, when towing travel is performed in a state where the temperature of the front drive system 11 has already risen, or when towing another vehicle and traveling at a high speed in the power consumption suppression mode, the front drive system 11 is particularly likely to fall into an overheated state. Therefore, as described above, when towing travel is performed, if the control mode is switched automatically and forcibly, the electric vehicle 100 can reduce the requested torque T req output and more reliably protect the front drive system 11 from overheating.

[0128] The control device for the electric vehicle according to the above-described embodiment and the modified example is configured to control the front torque T generated at the front wheel 22. f and the torque generated at the rear wheel 32, that is, the rear torque T r Distributed request torque T req And adjust the requested torque T req The control mode of the distribution includes a power consumption suppression mode that prioritizes the suppression of power consumption and a driving performance mode that prioritizes the driving performance. Regarding the control device of the electric vehicle, in the power consumption suppression mode, the front torque T f Or rear torque T r The requested torque T is allocated more to either req , in the driving performance mode, the requested torque T is allocated more in the power consumption suppression mode. req The front torque T f Or rear torque T rIn addition, the front drive system 11 driving the front wheels 22 or the rear drive system driving the rear wheels 32 is obtained in accordance with the requested torque T which is allocated more in the power consumption reduction mode. req The front torque T f Or rear torque T r The temperature of a corresponding drive system. In the power consumption suppression mode, the requested torque T is allocated more. req The front torque T f Or rear torque T r , set the upper limit value (UL) corresponding to the temperature of the corresponding drive system FT or UL RT ), thereby limiting the allocation of a larger requested torque T in the power consumption suppression mode. req The front torque T f Or rear torque T r Furthermore, when the control mode is the power consumption suppression mode, the upper limit value (UL FT or UL RT ) is reduced, the requested torque T is allocated more in the power consumption suppression mode. req The front torque T f Or rear torque T r is limited to the upper limit value (UL FT or UL RT ), switch the control mode to driving performance mode.

[0129] Thus, when the control mode is the power consumption suppression mode, the upper limit value (UL FT or UL RT ) is reduced, the requested torque T is allocated more req The front torque T f Or rear torque T r The output is limited to the upper limit value (UL FT or UL RT ) before, the control mode is switched to the driving performance mode, thereby reliably protecting the larger distribution of the requested torque T req The front drive system 11 or the rear drive system 12 is protected from overheating, and the total torque ΣT is maintained at the requested torque T req That is, according to the control method of the electric vehicle involved in the above-mentioned embodiment and the modified example, the electric vehicle 100 and the electric vehicle of the modified example can protect the drive system from overheating and drive with the requested torque even when the torque distribution is adjusted to a distribution that suppresses power consumption.

[0130] More specifically, the control device for the electric vehicle according to the above embodiment is a control device (controller 14) for the electric vehicle 100 that generates a torque at the front wheel 22, that is, a front torque T f and the torque generated at the rear wheel 32, that is, the rear torque T r Distributed request torque T req And adjust the requested torque T req The control mode of the distribution includes a power consumption suppression mode that prioritizes the suppression of power consumption and a driving performance mode that prioritizes the driving performance. Regarding the control device (controller 14), in the power consumption suppression mode, the rear torque T r Compared with the front torque T f The requested torque T is allocated more req In the driving performance mode, the front torque T is increased compared to the power consumption suppression mode. f Less requested torque T req In addition, the control device (controller 14) acquires the temperature of the front drive system 11 driving the front wheels 22, and calculates the temperature of the front torque T f , set an upper limit value (upper limit torque UL) corresponding to the temperature of the front drive system 11 FT ), thereby limiting the front torque T f Moreover, regarding the control device (controller 14), when the control mode is the power consumption suppression mode, the upper limit value (upper limit torque UL FT ) is reduced, the front torque T f The output is limited to the upper limit value (upper limit torque UL FT ), switch the control mode to driving performance mode.

[0131] Thus, when the control mode is the power consumption suppression mode, the upper limit value (upper limit torque UL FT ) is reduced, the front torque T f The output is limited to the upper limit value (upper limit torque UL FT ), the control mode is switched to the driving performance mode, thereby reliably protecting the front drive system 11 from overheating and maintaining the total torque ΣT at the requested torque T req That is, according to the electric vehicle control device according to the above embodiment, even when the torque distribution is adjusted to suppress power consumption, the electric vehicle 100 can be driven with the requested torque while protecting the drive system from overheating.

[0132] The embodiments of the present invention have been described above, but the configurations described in the above embodiments and various modifications are merely examples of application 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, comprising: a control mode for distributing a requested torque to a torque generated at a front wheel, i.e., a front torque, and a torque generated at a rear wheel, i.e., a rear torque, and adjusting the distribution of the requested torque; a power consumption suppression mode for giving priority to suppression of power consumption; and a driving performance mode for giving priority to driving performance; wherein: In the electric power consumption suppression mode, the requested torque is allocated more to either the front torque or the rear torque. In the running performance mode, the front torque or the rear torque to which the requested torque is largely allocated in the power consumption suppression mode is reduced; acquiring a temperature of one of a front drive system driving the front wheels or a rear drive system driving the rear wheels corresponding to the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode, An upper limit value corresponding to the temperature of the corresponding drive system is set for the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode, thereby limiting the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode, When the control mode is the power consumption suppression mode, the control mode is switched to the driving performance mode after the upper limit value is lowered and before the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode is limited to the upper limit value.

2. The control method of an electric vehicle according to claim 1, wherein: In the electric power consumption suppression mode, the requested torque is allocated more to the front torque than to the rear torque. In the running performance mode, the requested torque is allocated less to the front torque than in the electric power consumption suppression mode. acquiring the temperature of the front drive system driving the front wheels, The output of the front torque is limited by setting the upper limit value according to the temperature of the front drive system for the distributed front torque, When the control mode is the electric power consumption suppression mode, the control mode is switched to the running performance mode after the upper limit value is reduced and before the output of the front torque is limited to the upper limit value.

3. The control method of the electric vehicle according to claim 2, wherein: The temperature of the front drive system is a temperature of a motor that generates the front torque, a temperature of an inverter that drives the motor, or both the temperature of the motor and the temperature of the inverter.

4. The control method of an electric vehicle according to claim 2, wherein: A first threshold value is set in advance as a switching condition from the power consumption suppression mode to the driving performance mode for the upper limit value, When the upper limit value is less than or equal to the first threshold value, the control mode is switched from the power consumption suppression mode to the running performance mode.

5. The control method of an electric vehicle according to claim 2, wherein: When the control mode is switched, the change rates of the front torque and the rear torque are restricted.

6. The control method of an electric vehicle according to claim 2, wherein: After the control mode is switched from the electric power consumption suppression mode to the running performance mode, when the upper limit value increases, the control mode is switched from the running performance mode to the electric power consumption suppression mode.

7. The control method of the electric vehicle according to claim 6, wherein: A second threshold value is set in advance as a condition for returning to the power consumption reduction mode for the upper limit value, When the upper limit value is greater than or equal to the second threshold value, the control mode is returned to the power consumption reduction mode.

8. The control method of an electric vehicle according to claim 2, wherein: When the control mode is the electric power consumption suppression mode and the vehicle is traveling on an uphill road, the control mode is switched to the traveling performance mode after the upper limit value is reduced and before the output of the front torque is limited to the upper limit value.

9. The control method of an electric vehicle according to any one of claims 2 to 8, wherein: When the control mode is the electric power consumption suppression mode and the vehicle travels by towing another vehicle, the control mode is switched to the traveling performance mode after the upper limit value is reduced and before the output of the front torque is limited to the upper limit value.

10. A control device for an electric vehicle, comprising a power consumption suppression mode giving priority to suppression of power consumption and a driving performance mode giving priority to driving performance as a control mode for distributing a requested torque to a torque generated at a front wheel, i.e., a front torque, and a torque generated at a rear wheel, i.e., a rear torque, and adjusting the distribution of the requested torque, wherein: In the electric power consumption suppression mode, the requested torque is allocated more to either the front torque or the rear torque. In the running performance mode, the front torque or the rear torque to which the requested torque is largely allocated in the power consumption suppression mode is reduced; acquiring a temperature of one of a front drive system driving the front wheels or a rear drive system driving the rear wheels corresponding to the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode, An upper limit value corresponding to the temperature of the corresponding drive system is set for the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode, thereby limiting the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode, When the control mode is the power consumption suppression mode, the control mode is switched to the driving performance mode after the upper limit value is lowered and before the front torque or the rear torque to which the requested torque is more allocated in the power consumption suppression mode is limited to the upper limit value.

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