Electric vehicle control device

Abstract

To provide a control apparatus for an electric vehicle capable of suppressing the occurrence of regeneration loss of energy in consideration of load state and / or towing state.SOLUTION: A control apparatus for an electric vehicle includes a motor with at least power generating function and is configured to brake the electric vehicle with regenerative torque of the motor during deceleration. The control apparatus includes a controller for controlling the electric vehicle. The controller calculates a center of gravity H(H_add) of the vehicle and a drive wheel distance L(L_add), which is a distance from the center of gravity to a drive wheel 2, estimates a load on the drive wheel 2 on the basis of the calculated center of gravity H(H_add) and drive wheel distance L(L_add;), and sets an amount of regeneration of the motor on the basis of the estimated load.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device for an electric vehicle that controls the amount of regeneration of a motor connected to a drive wheel. [Background technology]

[0002] Patent Document 1 describes a regenerative braking control device for an electric vehicle that is configured to recover energy while achieving a good braking feel during deceleration. The control device described in Patent Document 1 is configured to brake the vehicle using braking torque from a mechanical brake device (friction braking device) and regenerative braking (regenerative torque) from a motor. Specifically, the control device is configured to estimate the maximum braking torque (ideal braking torque) within a range in which the wheels do not lock, set the mechanical braking torque to be smaller than the ideal braking torque, and set the braking torque that is the difference between the ideal braking torque and the mechanical braking torque as the regenerative braking torque. Note that the ideal braking torque is estimated based on the vehicle weight and height (or height of the center of gravity) of the electric vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-200590 Summary of the Invention [Problem to be solved by the invention]

[0004] In electric vehicles, it is desirable to set a large amount of regeneration from the motor. The regeneration amount is set according to the vehicle weight. The control device described in the aforementioned Patent Document 1 is configured to estimate the ideal braking torque based on the vehicle weight and brake the vehicle using mechanical braking torque and regenerative braking torque. However, in the case of a towing vehicle, such as a truck, the vehicle weight varies significantly depending on the load condition. For example, if the target regeneration amount is set according to a heavy load, when the load decreases, the regenerative torque braking amount may become excessive, causing the drive wheels to slip. On the other hand, if the target regeneration amount is set according to a light load, when the load increases, the regeneration amount decreases, resulting in reduced regenerative efficiency. Furthermore, even with the same load and vehicle weight, the limit at which the drive wheels slip changes depending on the shape of the load or the position and method of loading or towing, and ultimately the regeneration amount also changes. In such cases, depending on the loading state or towing state of the vehicle, the efficiency of energy regeneration may decrease, which may result in energy regeneration loss.

[0005] This invention was conceived with a view to solving the above technical problems. , pull An object of the present invention is to provide a control device for an electric vehicle that can suppress the occurrence of regenerative energy loss by taking into account the traction state. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a control device for an electric vehicle that includes at least a motor having a power generating function and that is configured to brake the vehicle by using a regenerative torque of the motor during deceleration, the control device including a controller that controls the electric vehicle, the controller controlling the electric vehicle, and of The electric vehicle is During transportation Find the center of gravity and During transportation A drive wheel distance, which is the distance from the center of gravity position to the drive wheel, is calculated, and a weight of the electric vehicle including the weight of the transported object is calculated based on the drive wheel distance, the wheel base of the electric vehicle, and the weight of the electric vehicle. The present invention is characterized in that the load acting on the drive wheels is estimated, and the amount of regeneration of the motor is set based on the estimated load. [Effects of the Invention]

[0007] According to this invention, the transported object of Vehicle based on pulling status During transportation Center of gravity position During transportation The system is configured to calculate the drive wheel distance, which is the distance from the center of gravity to the drive wheel, and estimate the load acting on the drive wheel based on the drive wheel distance, the wheel base of the electric vehicle, and the weight of the electric vehicle including the weight of the transported object, thereby grasping the deceleration limit value (slip limit) at which the drive wheel does not slip.The system is then configured to set the regeneration amount of the motor according to the load acting on the drive wheel and the deceleration limit value. , pull Even if the load acting on the drive wheels differs depending on the position and method of pulling, of It is possible to set the regeneration amount according to the vehicle state. That is, it is possible to set an appropriate regeneration amount according to the vehicle state, and as a result, it is possible to avoid or suppress the occurrence of regeneration loss. In other words, it is possible to avoid or suppress the decrease in energy efficiency. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically illustrating a vehicle to which an embodiment of the present invention is applied; [Figure 2] 10A and 10B are diagrams for explaining the center of gravity position and the driving wheel distance; [Figure 3] FIG. 10 is a diagram for calculating a change in driving wheel distance. [Figure 4] 10 is a diagram for calculating the variation of the center of gravity position and the driving wheel distance. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following embodiments are merely examples of specific embodiments of the present invention and are not intended to limit the scope of the present invention.

[0010] The vehicle targeted in the embodiments of the present invention is an electric vehicle equipped with at least a motor having a power generating function and a battery capable of supplying and receiving electric power to the motor, or may be a hybrid vehicle further equipped with an engine as a power source.

[0011] FIG. 1 shows a specific example of an electric vehicle according to an embodiment of the present invention. The electric vehicle (hereinafter referred to as vehicle) Ve shown in FIG. 1 generates driving force by transmitting driving torque output by a motor 1, which is a driving force source, to rear wheels 2. In other words, FIG. 1 shows the configuration of a rear-wheel drive vehicle in which the rear wheels 2 are the driving wheels. Note that the vehicle Ve in the embodiment of the present invention may also be a front-wheel drive vehicle in which the front wheels 3 are the driving wheels. Alternatively, it may be a four-wheel (all-wheel) drive vehicle in which both the front wheels 3 and the rear wheels 2 are driving wheels. Furthermore, when an engine is mounted as the driving force source, a transmission (not shown) may be provided on the output side of the engine, and the driving torque output by the driving force source may be configured to be transmitted to the driving wheels via the transmission.

[0012] The motor (MG) 1 is configured, for example, by a permanent magnet synchronous motor or an induction motor. Therefore, the motor 1 generates driving torque when supplied with electric power, and generates electricity when forced to rotate by the inertial force of the vehicle Ve. The negative torque generated by this power generation becomes the braking force (braking torque) of the vehicle Ve.

[0013] The motor 1 is connected to a power supply device 4. This power supply device 4 supplies power to the motor 1 and also includes a power storage device that stores the power generated by the motor 1, an inverter that converts the voltage or frequency, and the like.

[0014] The output shaft (rotor shaft) of the motor 1 is connected to a differential gear 5, which is a final reduction gear. The differential gear 5 is configured to output a driving torque for running to rear wheels (drive wheels) 2. The front wheels 3 are steerable wheels, and a steering mechanism 6 is connected to them.

[0015] A brake device 7 is provided on each of the front wheels 3 and the rear wheels 2. The brake device 7 is a brake similar to a conventionally known brake mechanism and may be a friction brake such as a disc brake, drum brake, or powder brake. In other words, the brake device 7 is configured to generate a friction force using hydraulic pressure, electromagnetic force, or the like, thereby generating a braking force in a direction that stops the rotation of the front wheels 3 and the rear wheels 2.

[0016] Also provided is a pedal 8 for operating driving conditions such as acceleration and deceleration. The pedal 8 may be two pedals, an accelerator pedal and a brake pedal, or may be a so-called one-pedal acceleration / deceleration operating device.

[0017] An electronic control unit (hereinafter referred to as ECU) 9 is provided to control the motor 1, the power supply device 4, the brake device 7, etc. The ECU 9 corresponds to the "controller" in the embodiment of the present invention, and is mainly composed of a microcomputer. It performs calculations using input data, pre-stored data, and programs, and outputs the calculation results as control command signals. The input data includes, for example, vehicle speed, acceleration, accelerator opening (which is the required driving amount), brake pedal force, road friction coefficient μ, vehicle weight, wheel speed of each wheel, the position (or height) of the center of gravity of the vehicle Ve, the distance from the center of gravity to the drive wheels (drive wheel distance), the on / off status of the towing switch, the rotation speed and torque of the motor 1, and various other sensor values. The pre-stored data includes a map that determines the regenerative braking torque based on the center of gravity position and drive wheel distance. The EC U9 isAs control command signals, it outputs a torque (driving torque, regenerative torque) command signal for the motor 1, a braking torque command signal for the brake device, etc. Although the example in FIG. 1 shows an example in which one ECU is provided, multiple ECUs may be provided, for example, for each device to be controlled or for each control content.

[0018] In an electric vehicle Ve configured as described above, it is preferable to set the motor's regeneration amount to a large value. On the other hand, in a towing vehicle such as a truck, the regeneration amount varies depending on the loading condition of the cargo. For example, when the load is heavy or light, or even when the load and vehicle weight are the same, the limit value at which the drive wheels slip changes depending on the shape of the load (the transported object in this invention) and the loading or towing position and method, and as a result, the regeneration amount also changes. In such cases, the energy regeneration efficiency decreases, and eventually energy regeneration loss may occur. Therefore, in an embodiment of the present invention, the regeneration amount is set to a large value depending on the towing condition of the vehicle. In a positive manner The regeneration amount is set in response to the change in the torque.

[0019] Specifically, E.C. To U9 Therefore, the system is configured to calculate the upper limit deceleration that can be regenerated by the motor 1. In other words, the system is configured to calculate the deceleration limit value (slip limit value) at which the rear wheels 2 do not slip.

[0020] Figure 2 is a diagram for explaining the center of gravity position of a vehicle Ve and the distance between that center of gravity position and the drive wheels (hereinafter simply referred to as drive wheel distance), where (a) of Figure 2 is a diagram for explaining the center of gravity position H_base and drive wheel distance Lr_base when not towing, (b) of Figure 2 is a diagram for explaining the center of gravity position H_add(a) and drive wheel distance Lr_add(a) when a towing object 10 such as luggage or a trailer house is towed behind the vehicle, and (c) of Figure 2 is a diagram for explaining the center of gravity position H_add(b) and drive wheel distance Lr_add(b) when a towing object 10 such as luggage is loaded on top of the vehicle.

[0021] In this embodiment of the present invention, the regeneration amount in the non-towing state shown in FIG. 2(a) is set as a reference state, and the vehicle weight M_add, the height of the center of gravity when towing H_add, and the drive wheel distance Lr_add are calculated relative to this reference state. In other words, correction values ​​for these three parameters are calculated. The load acting on the drive wheels is then calculated based on these correction values. The slip limit (deceleration that does not cause slip) is then calculated based on the load acting on the drive wheels (i.e., rear wheels 2), and a target regeneration amount is set. The ellipses in FIG. 2(a) to (c) indicate the friction limit (slip limit). In other words, they indicate the magnitude of the load (friction circle range) acting between the rear wheels 2 and the road surface.

[0022] The drive wheel distance Lr_add may be calculated depending on whether the wheels (wheels of the towed object) of the towed object 10 are in contact with the road surface, or whether the towed object is a load that does not contact the road surface. Drive wheel distance Lr_add may also be calculated based only on the increase or decrease in the distance in the front-to-rear direction of the vehicle, and may also take into account the increase or decrease in the vehicle's height. Furthermore, if the towed object 10 moves laterally while traveling, the correction value may be set smaller than in normal cases where the towed object 10 does not move while traveling, taking into account slippage during turns, etc.

[0023] The friction limit ar of the rear wheels (drive wheels) 2 shown by the friction circles in Figure 2(a) to (c) can be expressed as follows. First, the load Wr and the load change dw of the rear wheels 2, which are regenerative wheels, are expressed as follows: Wr = M × g × (L - Lr) / L (1) dw=(M×ar×H) / L (2) where M represents the vehicle weight, g represents the gravitational acceleration, and L represents the predetermined wheelbase. , Lr is the distance from the center of gravity of the vehicle to the drive wheels (drive wheel distance) Using these equations, the friction limit ar of rear wheel 2 can be calculated as follows: M×ar=μ× (Wr+dW) =μ×(M×g×(L-Lr) / L+(M×ar×H) / L) and Note that μ indicates the coefficient of friction of the road surface. Ultimately, the friction limit ar of rear wheel 2 is ar×(1-(μ×H) / L)=g×(μ×(L-Lr) / L) And further organizing it, ar=g×(μ×(L-Lr)) / (L-μ×H)...(3) becomes Note that H indicates the height of the center of gravity.

[0024] When the friction limit ar is calculated from the above-mentioned examples of (b) and (c) of Figure 2 using equation (3), the driving wheel distance Lr_add is smaller in (b) of Figure 2 than in (c) of Figure 2, and the height of the center of gravity H_add is smaller in (b) of Figure 2 than in (c) of Figure 2. ) is better 2(c). Therefore, the friction limit ar is larger in Figure 2(b) than in Figure 2(c), and therefore the friction circle (slip limit) is also larger in Figure 2(b). In other words, even when towing an object with the same load, the friction circle (slip limit) is larger in Figure 2(b) than in Figure 2(c). Better , the amount of regeneration is greater than when the batteries are loaded upward as in Figure 2(c).

[0025] As described above, in this embodiment of the present invention, the regeneration amount, which differs depending on the towing position and method, is set by determining the friction limit (i.e., slip limit) from the center of gravity position, drive wheel distance, and the load acting on the drive wheels (rear wheels) 2. Therefore, an appropriate regeneration amount can be set according to the state of the vehicle Ve, and as a result, regeneration loss can be avoided or suppressed. In short, the friction limit ar changes depending on the center of gravity position H_add and drive wheel distance Lr_add, which in turn changes the amount of power that can be regenerated. Therefore, by setting the target regeneration amount according to the friction limit ar, it is possible to avoid or suppress a decrease in energy regeneration efficiency.

[0026] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described example and may be modified as appropriate within the scope of achieving the object of the present invention. As described above, the friction limit ar varies depending on the vehicle weight M_add, center of gravity position H_add, and drive wheel distance L_add, which are amounts of change from the reference values, and the amount of regeneration also varies accordingly. Therefore, the method of calculating the friction limit ar is not limited to the above-described example.

[0027] For example, the vehicle weight M_add may be calculated from the driving power required during acceleration. The driving wheel distance L_add may be calculated based on the change in the acceleration sensor, the amount of lift of the vehicle in the vertical direction, or the change in the viewing angle of the vehicle-mounted camera. , pull The center of gravity position has changed from the state without the object being transported based on the pulling state, etc. (When transporting Calculate the center of gravity position, During transportation It may also be calculated according to the center of gravity position. For example, as shown in Fig. 3, the amount of change in driving wheel distance L_add is calculated based on the acceleration and sensor values ​​for an arbitrary number of times (for example, four times). Also, as shown in Fig. 4, the amount of change in the center of gravity position H_add may be detected by an in-vehicle camera 11 in front of the vehicle, and the amount of change may be displayed on a display (for example, a display of a navigation system) 12. In this case, the center of gravity position H_add and driving wheel distance L_add are corrected according to the amount of change shown by the solid line with respect to the reference shown by the dashed line. Note that Fig. 4(a) shows the change with respect to the reference when accelerating without towing, and Fig. 4(b) shows the change with respect to the reference when accelerating with towing. [Explanation of symbols]

[0028] 1 motor 2 rear wheels (drive wheels) 3 Front wheels 4 Power supply 5 Differential gear 6 Steering mechanism 7 Brake system 8 pedals 9 Electronic Control Unit (ECU) 10 Traction 11. In-car camera 12 Display Vehicle

Claims

[Claim 1] A control device for an electric vehicle including a motor having at least a power generating function, the control device being configured to brake the vehicle by a regenerative torque of the motor during deceleration, a controller for controlling the electric vehicle; The controller determining a center of gravity position of the electric vehicle during transportation based on a towing state of the transported object transported by the electric vehicle; Calculating a drive wheel distance, which is the distance from the center of gravity position during transport to the drive wheel; estimating a load acting on the drive wheels based on the drive wheel distance, a wheel base of the electric vehicle, and a weight of the electric vehicle including a weight of the transported object; The amount of regeneration of the motor is set based on the estimated load. A control device for an electric vehicle.

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