Vehicle control system

Abstract

To secure responsiveness and reduce shock equally.SOLUTION: In a vehicle control apparatus 1 for use in controlling an automobile 100 traveling on a motor 2 as a power source, when torque of the motor 2 decreases from a positive zone to a negative zone, a control part 10 used for controlling the motor 2 controls the motor 2 so that a torque rate in the negative zone is smaller than that in the positive zone. Because a torque rate in the positive zone is large, it is possible to reduce deterioration in responsiveness when a driver of the automobile 100 operates the automobile to decelerate. A torque rate in the negative zone is small, it is possible to reduce a shock due to response in deceleration being quick when the driver of the automobile 100 operates the automobile to deceleration. Therefore, it is possible to secure responsiveness and reduce a shock equally.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle control device.

Background Art

[0002] Techniques for controlling an automobile that runs using an electric motor as a power source have been proposed. For example, in Patent Document 1, in a coasting mode in which coasting is performed, an instruction torque for following the target torque of the electric motor is made close to 0, and after the instruction torque approaches 0, an instruction torque is calculated such that the change amount per unit time of the instruction torque is smaller than in the normal running mode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the above-described technology, when the driver of an automobile performs a deceleration operation, there may be a deterioration in responsiveness such that the driver still feels the acceleration of the automobile. Also, in the above-described technology, when the driver of an automobile performs a deceleration operation, an impact may occur due to the rapid rise of deceleration.

[0005] Therefore, an object of the present invention is to provide a vehicle control device that can achieve both ensuring responsiveness and reducing impact.

Means for Solving the Problems

[0006] The present invention relates to a vehicle control device for controlling an automobile that runs using an electric motor as a power source, comprising a control unit for controlling the electric motor, wherein the control unit controls the electric motor such that, when the torque of the electric motor decreases from a positive torque region (where the torque of the electric motor accelerates the automobile) to a negative torque region (where the torque of the electric motor decelerates the automobile), the torque rate, which is the rate of change of torque per unit time, is smaller in the negative torque region than in the positive torque region.

[0007] According to this configuration, a vehicle control device that controls an automobile powered by an electric motor includes a control unit that controls the electric motor. The control unit controls the electric motor so that, when the torque of the electric motor decreases from the positive torque region (where the torque accelerates the automobile) to the negative torque region (where the torque decelerates the automobile), the torque rate, which is the rate of change of torque per unit time, is smaller in the negative torque region than in the positive torque region. Since the torque rate in the positive torque region is relatively large, it is possible to reduce the deterioration in responsiveness that causes the driver to still feel the automobile accelerating when they perform a deceleration operation. On the other hand, since the torque rate in the negative torque region is relatively small, it is possible to reduce the shock caused by a rapid start of deceleration when the driver performs a deceleration operation. Therefore, it is possible to achieve both responsiveness and shock reduction.

[0008] In this case, it is preferable for the control unit to control the motor such that, as the motor's torque decreases from the positive torque region to the negative torque region, the torque rate decreases as the torque approaches zero in the positive torque region, and increases as the torque approaches zero in the negative torque region.

[0009] In this configuration, the control unit controls the motor so that when the motor's torque decreases from the positive torque region to the negative torque region, the torque rate is relatively large in the positive torque region, but decreases as the torque approaches zero, and in the negative torque region, the torque rate is relatively small, but increases as the torque approaches zero. As a result, the torque rate fluctuation becomes smoother near the boundary between the positive and negative torque regions where the torque is zero, reducing the impact on the vehicle's behavior. [Effects of the Invention]

[0010] The vehicle control device of the present invention makes it possible to achieve both responsiveness and reduction of impact. [Brief explanation of the drawing]

[0011] [Figure 1] A branch office of an automobile including a vehicle control device according to an embodiment. [Figure 2] (A) is a graph showing the change in speed of a conventional automobile, (B) is a graph showing the change in torque of the electric motor that causes the change in speed in (A), (C) is a graph showing the change in speed of an automobile using the vehicle control device according to the embodiment, and (D) is a graph showing the change in torque of the electric motor that causes the change in speed in (C). [Figure 3] (A) is a diagram showing a map for setting the torque rate of a conventional electric motor, and (B) is a diagram showing a map for setting the torque rate of the electric motor of this embodiment. [Figure 4] This graph shows the relationship between torque and torque rate according to the vehicle control device according to the embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, a vehicle control device according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in Figure 1, the vehicle control device 1 of this embodiment is mounted on an automobile 100 and controls the automobile 100 which runs using an electric motor 2 as a power source. The automobile 100 is, for example, a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a fuel cell vehicle (FCEV), an electric vehicle (BEV), etc., and is a large vehicle such as a bus or truck. In other words, the automobile 100 may be equipped with an internal combustion engine or the like as a power source in addition to the electric motor 2.

[0013] The vehicle control device 1 includes a control unit 10 that controls the electric motor 2. The electric motor 2 is, for example, a permanent magnet synchronous motor and is also capable of generating electricity. The output shaft of the electric motor 2 is connected to the input shaft of the transmission 3. The output shaft of the transmission 3 is connected to the left and right drive wheels 7 via a propeller shaft 4, a differential 5, and a drive shaft 6. If the electric motor 2 is an in-wheel motor built into the drive wheel 7, the transmission 3, propeller shaft 4, differential 5, and drive shaft 6 may be omitted. The automobile 100 includes a battery 8 for supplying power to the electric motor 2. The battery 8 supplies power to the electric motor 2 via an inverter 9. The inverter 9 generates a control signal to rotate the electric motor 2 based on a command signal from the control unit 10.

[0014] The control unit 10 is composed of an ECU (Electronic Control Unit). The ECU is an electronic control unit that includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The ECU realizes various functions, for example, by loading a program recorded in ROM into RAM and executing the program loaded into RAM with the CPU. The ECU may be composed of multiple electronic units.

[0015] The control unit 10 controls the torque rate, which is the rate of change of torque per unit time, when the torque of the electric motor 2 decreases from the positive side of the torque range, where the torque of the electric motor 2 accelerates the automobile 100, to the negative side of the torque range, where the torque of the electric motor 2 decelerates the automobile 100.

[0016] When the torque of the electric motor 2 decreases from the positive torque region to the negative torque region, for example, accelerator-off regeneration or retarder regeneration is performed. Accelerator-off regeneration rotates the electric motor 2 using the rotational force of the drive wheels 7 of the coasting vehicle 100 when the accelerator pedal is released, causing the electric motor 2 to generate electricity. Accelerator-off regeneration converts the kinetic energy of the vehicle 100 into electrical energy and charges the battery 8. Retarder regeneration is based on a conventional retarder and controls the torque (regenerative torque) of the electric motor 2 according to the position of the operating lever to assist in braking the vehicle 100 during deceleration.

[0017] Furthermore, the vehicle control device 1 of this embodiment may be applied when the torque of the electric motor 2 decreases from the positive torque region to the negative torque region in a system in which the acceleration and deceleration of the automobile 100 are controlled solely by the operation of the accelerator pedal. In this system, acceleration and deceleration (regeneration) are performed in accordance with the opening of the accelerator pedal.

[0018] In this system, for example, when the accelerator pedal is pressed (ON), the motor 2 generates power torque (torque in the positive range). On the other hand, when the accelerator pedal is not pressed (OFF), the motor 2 generates regenerative torque (torque in the negative range). This system expands the regenerative range and allows for efficient acquisition of regenerative torque during deceleration. Furthermore, even when the accelerator pedal is pressed, if the pedal depression is small, the motor 2 may generate regenerative torque in the negative range, and when the accelerator pedal is off, the motor 2 may also generate regenerative torque in the negative range. In other words, this system controls both the positive and negative sides of the torque based on the amount the accelerator pedal is depressed.

[0019] Hereinafter, the operation of the vehicle control device 1 of the present embodiment will be described. Conventionally, in order to ensure drivability such as suppressing the generation of shocks associated with sudden changes in the torque of the electric motor 2, a torque rate [Nm / s], which is the rate of change of torque per unit time, has been set. Conventionally, considering factors that have a large impact on drivability with respect to changes in the torque of the electric motor 2, the torque rate has been set by the following method.

[0020] Conventionally, when controlling the speed of the automobile 100 as shown in FIG. 2(A), the torque rate is set based on, for example, the accelerator opening (% of the amount of depression of the accelerator pedal) and the rotational speed of the electric motor 2 as shown in FIG. 3(A). Also, conventionally, the torque rate is set based on the gear ratio (gear position) of the transmission 3 and the rotational speed of the electric motor 2. In FIG. 3(A), Y1 < Y2 <... < Yi <... < Y(n - 1) < Yn and Z1 < Z2 <... < Zi <... < Z(n - 1) < Zn (n and i are arbitrary natural numbers, and 1 < i < n).

[0021] Conventionally, as shown in the slope of the graph in FIG. 2(B), when the torque of the electric motor 2 decreases from the positive torque region to the negative torque region, the torque rate is constant, and the torque rate in the positive torque region of the torque is equal to the torque rate in the negative torque region of the torque. For example, in FIG. 3(A), the torque rates αi1, αi2,..., αii,..., αi(n - 1), αin for each accelerator opening Z1, Z2,..., Zi,..., Z(n - 1), Zn with respect to the rotational speed Yi of the electric motor 2 are set to be constant, i.e., αi1 = αi2 =... = αii =... = αi(n - 1) = αin.

[0022] However, with such a torque rate setting, priority is given to gently increasing the deceleration rate in the negative torque region, and when a small torque rate is set, when the accelerator pedal is turned off after being turned on, the driver still feels the acceleration of the vehicle 100. That is, a deterioration in responsiveness occurs. On the other hand, when a large torque rate is set by prioritizing the reduction of the feeling that the driver still feels acceleration when the accelerator pedal is turned off on the positive torque side, the rise of the deceleration rate is fast and an impact occurs. For example, there is a possibility of deterioration in riding comfort, impact on passengers, and impact on luggage.

[0023] The drawback of the conventional torque rate setting method is that due to the relationship of the axis items of the set torque rate map, it is impossible to clearly separate the positive torque side (acceleration side) and the negative torque side (deceleration side) of the torque. Therefore, in this embodiment, the following two points are implemented. (1) Change the axis items of the torque rate map. (2) Optimize the torque rate value.

[0024] As the change of the axis items of the torque rate map in (1) above, in this embodiment, as shown in bold in FIG. 3(B), by changing the axis items of the torque rate map to the rotational speed and the torque of the motor 2, it is possible to clearly separate the positive torque side and the negative torque side of the torque. In FIG. 3(B), X1 < X2 <... < X(i - K) <... < Xi <... < X(i + L) <... < X(n - 1) < Xn (n, i, K, and L are arbitrary natural numbers, 1 < i < n, 1 < K < i - 1, 1 < L < n - i). Xi = 0. X1 < X2 <... < X(i - K) <... < Xi is the region of the negative torque side, and Xi <... < X(i + L) <... < X(n - 1) < Xn is the region of the positive torque side.

[0025] As an optimization of the torque rate value in (2) above, in the present embodiment, as shown in FIGS. 2(C), 2(D), and 3(B), when the torque of the motor 2 decreases from the positive torque region to the negative torque region, the control unit 10 controls the motor 2 so that the torque rate in the negative torque region is smaller than the torque rate in the positive torque region. For example, in the example of FIG. 2(D), when the torque of the motor 2 decreases from the positive torque region to the negative torque region, the torque rate represented by the gradient of the graph is smaller in the negative torque region than in the positive torque region of the torque. That is, the gradient of the graph is gentle.

[0026] For example, in FIG. 3(B), the torque rates βi1, βi2, …, βi(i-K), …, βii, …, βi(i+L), …βi(n-1), βin for the torques X1, X2, …, X(i-K), …, Xi, …, X(i+L), …, X(n-1), Xn with respect to the rotational speed Yi of the motor 2 are smaller than the torque rates βi(i+L), …, βi(n-1), βin in the positive torque region Xi < … < X(i+L) < … < X(n-1) < Xn, which are the torque rates in the negative torque region Xi > … > X(i-K) > … > X2 > X1, namely βi1, βi2, …, βi(i-K).

[0027] The torque rates βi1, βi2, …, βi(i-K), …, βii, …, βi(i+L), …βi(n-1), βin for the torques X1, X2, …, X(i-K), …, Xi, …, X(i+L), …, X(n-1), Xn with respect to the rotational speed Yi of the motor 2 satisfy βi1 ≤ βi2 ≤ … ≤ βi(i-K) ≤ … ≤ βii ≤ … ≤ βi(i+L) ≤ … ≤ βi(n-1) ≤ βin, and the torque rate decreases as the torque decreases. In the torque regions X1, X2, …, X(i-K), …, Xi, …, X(i+L), …, X(n-1), Xn, it is only necessary that the torque rate as a whole decreases with respect to the decrease in torque, and there may be a region where the torque rate is constant with respect to the decrease in torque in part.

[0028] In this embodiment, further, when the torque of the electric motor 2 decreases from the positive torque region to the negative torque region, in the positive torque region, as the torque approaches 0, the torque rate decreases, and in the negative torque region, as the torque approaches 0, the torque rate increases, and the control unit 10 controls the electric motor 2. As shown in the portions surrounded by the thick lines in FIGS. 2(D) and 3(B), in the positive torque region Xi <... < X(i+L), as the torque approaches 0, the torque rate decreases, and in the negative torque region Xi >... > X(i-K), as the torque approaches 0, the torque rate increases, and the fluctuation of the torque rate near 0 is reduced.

[0029] In FIG. 3(B), in the positive torque region Xi <... < X(i+L), βii ≦ βi(i+1) ≦ βi(i+2) ≦... ≦ βi(i+(L-1)) ≦ Xi(i+L), and as the torque approaches 0, the torque rate decreases. In the positive torque region Xi <... < X(i+L), it is only necessary that the torque rate decreases as the torque approaches 0 as a whole, and there may be a region where the torque rate is constant with respect to a part of the decrease in torque. Also, in the negative torque region Xi >... > X(i-K), βii ≧ βi(i-1) ≧ βi(i-2) ≧... ≧ βi(i-(K-1)) ≧ βi(i-K), and as the torque approaches 0, the torque rate increases. In the negative torque region Xi >... > X(i-K), it is only necessary that the torque rate increases as the torque approaches 0 as a whole, and there may be a region where the torque rate is constant with respect to a part of the increase in torque.

[0030] Therefore, in this embodiment, near 0 torque, the control unit 10 controls the electric motor 2 according to a graph as shown in FIG. 4. In the example of FIG. 4, β1i, which is the torque rate when the torque is 0 when the rotational speed of the electric motor is Y1, and β21, which is the torque rate when the torque is the minimum value on the negative side when the rotational speed of the electric motor is Y2, are equal, but this is just an example, and the torque rate can take any value.

[0031] Also, in the examples of FIGS. 3(B) and 4, when the torque of the motor 2 decreases from the positive torque region to the negative torque region, the control unit 10 controls the motor 2 such that the torque rate in the negative torque region is smaller than the torque rate in the positive torque region. However, in the region of X(i-K)<…<Xi<…<X(i+L) including the case where the torque is 0, as shown by the broken line in FIG. 4, the torque rate in the positive torque region and the torque rate in the negative torque region may be equal, and the torque rate may vary stepwise.

[0032] That is, the fact that the torque rate in the negative torque region is smaller than the torque rate in the positive torque region includes the case where the torque rate in the positive torque region and the torque rate in the negative torque region are equal in any region of X(i-K)<…<Xi<…<X(i+L) including the case where the torque is 0.

[0033] As a basic concept, in the present embodiment, when the torque of the motor 2 decreases from the positive torque region to the negative torque region, the intermediate layer where the torque rate varies from a large value to a small value is made as close as possible to the point where the torque of the motor 2 is 0 [Nm]. Thereby, it is possible to leave a feeling for the driver as if the vehicle is accelerating and suppress the impact. Also, as a whole, the torque rate in the negative torque region can be determined from the viewpoint of preventing the passengers in the standing area from falling when the vehicle 100 is a bus, and can be determined from the viewpoint of preventing the load from collapsing when the vehicle 100 is a truck.

[0034] In this embodiment, a vehicle control device 1 that controls an automobile 100 that runs using an electric motor 2 as a power source includes a control unit 10 that controls the electric motor 2. When the torque of the electric motor 2 decreases from the positive side of the torque region that accelerates the automobile 100 to the negative side of the torque region that decelerates the automobile 100, the control unit 10 controls the electric motor 2 such that the torque rate, which is the rate of change of torque per unit time, is smaller in the negative side of the torque region than in the positive side of the torque region.

[0035] Because the torque rate is relatively large in the positive torque range, when the driver of car 100 performs a deceleration operation, the deterioration in responsiveness that causes the driver to still feel the acceleration of car 100 can be reduced. On the other hand, because the torque rate is relatively small in the negative torque range, when the driver of car 100 performs a deceleration operation, the shock caused by the rapid onset of deceleration can be reduced. Therefore, it is possible to achieve both responsiveness and shock reduction. By ensuring responsiveness, drivability can be improved.

[0036] Furthermore, in this embodiment, the control unit 10 controls the motor 2 such that when the torque of the motor 2 decreases from the positive torque region to the negative torque region, the torque rate is relatively large in the positive torque region, but decreases as the torque approaches zero, and in the negative torque region, the torque rate is relatively small, but increases as the torque approaches zero. As a result, near the boundary between the positive torque region and the negative torque region where the torque is zero, the fluctuation of the torque rate becomes smoother, and the influence on the behavior of the automobile 100 can be reduced.

[0037] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be implemented in various forms. [Explanation of Symbols]

[0038] 1...Vehicle control device, 2...Electric motor, 3...Transmission, 4...Propeller shaft, 5...Differential, 6...Drive shaft, 7...Drive wheel, 8...Battery, 9...Inverter, 10...Control unit, 100...Automobile.

Claims

[Claim 1] A vehicle control device for controlling an automobile that runs using an electric motor as a power source, The system includes a control unit for controlling the aforementioned electric motor, The control unit, when the torque of the electric motor decreases from the positive side of the torque in the direction that accelerates the vehicle to the negative side of the torque in the direction that decelerates the vehicle, adjusts the torque rate, which is the rate of change of the torque per unit time, The motor is controlled such that the torque rate in the negative region of the torque is smaller than the torque rate in the positive region of the torque. In the positive region of the torque, the torque rate decreases as the torque approaches zero. A vehicle control device that controls the electric motor such that, in the negative region of the torque, the torque rate increases as the torque approaches zero.

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