Electric vehicle control system

Abstract

To reflect the intention of a driver associated with an operation of the driver.SOLUTION: An electric-vehicle control apparatus 1 includes: an accelerator opening-degree detection part 4 for detecting an accelerator opening degree of an electric vehicle 2; a motor rotation speed detection part 5 for detecting a motor rotation speed; and a motor control part 7 for controlling a motor 3. The motor control part 7 performs: calculating target torque on the basis of the accelerator opening degree and motor rotation speed; calculating a torque rate being a change amount of torque per a unit time, on the basis of the accelerator opening degree; and controlling the motor 3 so that torque of the motor 3 equals the target torque at the calculated torque rate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric vehicle control device that controls an electric vehicle having a motor as a drive source.

Background Art

[0002] In an electric vehicle having a motor as a drive source, the electric vehicle is driven by generating driving torque in the motor, and the battery is charged by generating regenerative torque in the motor (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the driving state of generating driving torque in the motor, it is considered that the driver reduces the accelerator opening when wanting to accelerate the electric vehicle slowly and increases the accelerator opening when wanting to accelerate the electric vehicle immediately. However, generally, the torque rate of the command torque for controlling the motor is constant (see, for example, Patent Document 1). For this reason, in the driving state, the intention of the driver based on the above-described accelerator operation cannot be sufficiently reflected.

[0005] Furthermore, in the regenerative state, when the motor generates regenerative torque, if the torque rate is the same as in the accelerating state, the deceleration of the electric vehicle becomes overly sensitive, making it difficult for the driver to match the target deceleration. Moreover, motors have the characteristic of high torque at low rotation speeds and low torque at high rotation speeds. For this reason, in the regenerative state, if the motor is rotating at a low speed, a sudden deceleration unintended by the driver may occur, potentially causing the driver to re-accelerate or the cargo to shift.

[0006] Furthermore, the technology described in Patent Document 2 changes the torque rate depending on whether the target torque is increasing or not, but does not change the torque rate based on the accelerator opening, and therefore cannot solve the above-mentioned problem.

[0007] Therefore, the object of the present invention is to provide an electric vehicle control device that can appropriately reflect the driver's intentions regarding the acceleration and deceleration of the electric vehicle in response to the driver's operation. [Means for solving the problem]

[0008] The electric vehicle control device of the present invention is as follows.

[0009] [1] An electric vehicle control device for controlling the acceleration and deceleration of an electric vehicle driven by a motor, comprising: an accelerator opening detection unit for detecting the accelerator opening of the electric vehicle; a motor rotation speed detection unit for detecting the motor rotation speed; and a motor control unit for controlling the motor, wherein the motor control unit determines a target torque based on the accelerator opening and the motor rotation speed, determines a torque rate which is the amount of change in torque per unit time based on the accelerator opening, and controls the motor so that the torque of the motor becomes the target torque at the torque rate.

[0010] This electric vehicle control system can change the torque rate based on the accelerator pedal position, which is the driver's operation, thus appropriately reflecting the driver's intentions regarding the acceleration and deceleration of the electric vehicle in response to the driver's actions.

[0011] [2] The motor control unit determines the torque rate based on the motor rotation speed, as described in [1].

[0012] This electric vehicle control system calculates the torque rate based on the accelerator opening and motor rotation speed, allowing it to adjust the torque rate to account for the effects of varying driving resistance depending on the vehicle speed. This enables, for example, to provide the driver with a good driving feel at different speed ranges.

[0013] [3] The electric vehicle control device according to [1] or [2], further comprising a current torque detection unit for detecting the current torque generated by the motor, wherein in a powered state where the target torque is greater than the current torque, the motor control unit reduces the torque rate when the accelerator opening is below a threshold opening to less than the torque rate when the accelerator opening is above the threshold opening.

[0014] In this electric vehicle control system, when the accelerator opening is below a threshold opening during powered operation, the torque rate is set lower than when the accelerator opening is above the threshold opening. This allows the system to reflect the driver's intention to accelerate the electric vehicle slowly, as the torque rate is lower when the accelerator opening is small. Conversely, when the accelerator opening is large, the torque rate is higher, reflecting the driver's intention to accelerate the electric vehicle quickly.

[0015] [4] In the regenerative state where the target torque is smaller than the current torque, the motor control unit makes the torque rate when the current torque is below the threshold torque smaller than the torque rate when the current torque is above the threshold torque, for the electric vehicle control device according to [3].

[0016] In this electric vehicle control device, in the regenerative state, the torque rate when the current torque is below the threshold torque is made smaller than the torque rate when the current torque is above the threshold torque. Thereby, when the current torque is low as in the case where the motor is rotating slowly, it is possible to suppress the occurrence of sudden deceleration unintended by the driver. As a result, it is possible to suppress inducing the driver to re-accelerate or the load from collapsing. On the other hand, when the current torque is small, it is possible to suppress a decrease in the regenerative amount of the motor.

[0017] [5] The motor control unit makes the torque rate in the regenerative state smaller than the torque rate in the power running state under the condition that the accelerator opening is the same, for the electric vehicle control device according to [4].

[0018] In this electric vehicle control device, by making the torque rate in the regenerative state smaller than the torque rate in the power running state, the deceleration of the electric vehicle becomes gentle and it becomes easier for the driver to match the target deceleration.

Effect of the Invention

[0019] According to the present invention, it is possible to appropriately reflect the will of the driver regarding the acceleration and deceleration of the electric vehicle accompanying the operation of the driver.

Brief Description of the Drawings

[0020] [Figure 1] It is a block configuration diagram showing the electric vehicle control device of the embodiment. [Figure 2] It is a graph showing an example of the relationship between the accelerator opening, the motor speed, and the torque of the motor. [Figure 3]This is a figure corresponding to FIG. 2 for explaining the torque rate in each state. [Figure 4] This is a flowchart showing an example of the processing operation of the electric vehicle control device.

Mode for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0022] FIG. 1 is a block configuration diagram showing the electric vehicle control device 1 of the embodiment. As shown in FIG. 1, the electric vehicle control device 1 according to the present embodiment is mounted on an electric vehicle 2 having a motor 3 as a drive source, and controls the acceleration and deceleration of the electric vehicle 2. Examples of the electric vehicle 2 include a hybrid vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a fuel cell vehicle (FCEV: Fuel Cell Electric Vehicle), a battery electric vehicle (BEV: Battery Electric Vehicle), and the like. The electric vehicle control device 1 controls the motor 3 as control of the acceleration and deceleration of the electric vehicle 2.

[0023] The motor 3 is a motor generator that functions as an electric motor or a generator. The motor 3 functions as an electric motor and drives the electric vehicle 2 by generating a driving torque that is a positive-side torque. On the other hand, the motor 3 functions as a generator and charges a battery (not shown) by generating a regenerative torque that is a negative-side torque.

[0024] The electric vehicle control device 1 includes an accelerator opening detection unit 4, a motor speed detection unit 5, a current torque detection unit 6, and a motor control unit 7.

[0025] The accelerator pedal position detection unit 4 detects the accelerator pedal position of the electric vehicle 2, which is the amount of input from the driver. For example, an accelerator pedal position sensor that detects the accelerator pedal position can be used as the accelerator pedal position detection unit 4. The accelerator pedal position detection unit 4 transmits the detected accelerator pedal position detection signal to the motor control unit 7.

[0026] The motor rotation speed detection unit 5 detects the motor rotation speed, which is the rotation speed of the motor 3. For example, a rotation speed sensor such as a rotary encoder that detects the rotation speed of the motor 3 can be used as the motor rotation speed detection unit 5. In this case, the motor rotation speed and the vehicle speed of the electric vehicle 2 are proportionally related. Therefore, the motor rotation speed can be converted to the vehicle speed of the electric vehicle 2. The motor rotation speed detection unit 5 transmits the detected motor rotation speed detection signal to the motor control unit 7.

[0027] The current torque detection unit 6 detects the current torque, which is the torque generated by the motor 3. For example, the current torque detection unit 6 can be a torque sensor that detects the torque of the motor 3. The current torque detection unit 6 transmits the detected current torque signal to the motor control unit 7.

[0028] The motor control unit 7 is an electronic control unit (ECU) that includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The motor control unit 7 performs various controls by, for example, loading a program stored in ROM into RAM and executing it with the CPU. The motor control unit 7 may consist of a single electronic control unit or may consist of multiple electronic control units.

[0029] The motor control unit 7 acquires the accelerator opening detected by the accelerator opening detection unit 4, the motor rotation speed detected by the motor rotation speed detection unit 5, and the current torque detected by the current torque detection unit 6. The motor control unit 7 then controls the motor 3 based on these acquired accelerator opening, motor rotation speed, and current torque. The control of the motor 3 includes power control, which generates a positive torque, or power torque, in the motor 3, and regenerative control, which generates a negative torque, or regenerative torque, in the motor 3.

[0030] The motor control unit 7 determines the target torque to be generated by the motor 3 based on the accelerator opening and motor speed. Figure 2 is a graph showing an example of the relationship between accelerator opening, motor speed, and motor torque. In Figure 2, the vertical axis represents motor torque, and the vertical axis represents motor speed. Also, in Figure 2, torque on the positive side of zero represents positive torque, i.e., power torque, and torque on the negative side of zero represents negative torque, i.e., regenerative torque. As shown in Figure 2, the motor 3 has a predetermined output torque depending on the motor speed. Therefore, the motor control unit 7 determines the target torque based on the accelerator opening and motor speed within the range of the output torque corresponding to the motor speed. The motor control unit 7 may, for example, determine the target torque based on the accelerator opening and motor speed by referring to a table (governor table) that associates accelerator opening, motor speed, and target torque. The governor table may be, for example, a table in which the motor rotation speed is on the horizontal axis and the accelerator opening is on the vertical axis, and the target torque corresponding to each motor rotation speed and accelerator opening is represented in a two-dimensional matrix.

[0031] Here, if the target torque is greater than the current torque, in order to generate the target torque in motor 3, it is necessary to perform power control to increase the torque of motor 3. For this reason, the state in which the target torque is greater than the current torque is called the power state. On the other hand, if the target torque is less than the current torque, in order to generate the target torque in motor 3, it is necessary to perform regenerative control to decrease the torque of motor 3. For this reason, the state in which the target torque is less than the current torque is called the regenerative state.

[0032] The motor control unit 7 determines the target torque and, based on the accelerator opening, calculates the torque rate (Nm / sec), which is the rate of change in torque per unit time. In other words, the motor control unit 7 changes the torque rate based on the accelerator opening. The torque rate is not a fixed value, but a variable value that changes based on the accelerator opening. When the torque rate increases, the rate of change in torque per unit time increases, so in power control, the amount of increase in torque per unit time increases, and in regenerative control, the amount of decrease in torque per unit time increases. On the other hand, when the torque rate decreases, the rate of change in torque per unit time decreases, so in power control, the amount of increase in torque per unit time decreases, and in regenerative control, the amount of decrease in torque per unit time decreases.

[0033] Here, in the powering state, power control is performed to increase the torque of motor 3, so the torque rate in the powering state is called the torque increase rate. The torque increase rate is the amount of torque increase per unit time. On the other hand, in the regenerative state, regenerative control is performed to decrease the torque of motor 3, so the torque rate in the regenerative state is called the torque decrease rate. The torque decrease rate is the amount of torque decrease per unit time.

[0034] In the powered state, the motor control unit 7 determines (changes) the torque increase rate based on the accelerator opening and motor speed. Specifically, the motor control unit 7 makes the torque increase rate when the accelerator opening is below the threshold opening smaller than the torque increase rate when the accelerator opening is above the threshold opening. In other words, under the same motor speed conditions, the motor control unit 7 makes the torque increase rate when the accelerator opening is below the threshold opening smaller than the torque increase rate when the accelerator opening is above the threshold opening. Furthermore, the motor control unit 7 determines (changes) the torque increase rate when the accelerator opening is below the threshold opening and the torque increase rate when the accelerator opening is above the threshold opening according to the motor speed. Note that if the motor speeds are different, the torque increase rate when the accelerator opening is below the threshold opening may be smaller than the torque increase rate when the accelerator opening is above the threshold opening. The threshold opening is not particularly limited, but for example, it can be half-accelerator (50%). For example, if the motor speed is 1000 rpm and the threshold opening is 50%, the torque increase rate at a 40% accelerator opening should be smaller than the torque increase rate at a 60% accelerator opening. Furthermore, the torque increase rate may be multiple values ​​(variable values) depending on the accelerator opening, both when the accelerator opening exceeds the threshold opening and when the accelerator opening falls below the threshold opening.

[0035] The motor control unit 7 may, for example, determine the torque increase rate based on the accelerator opening and motor speed by referring to a table (torque increase rate table) that associates the accelerator opening, motor speed, and torque increase rate. The torque increase rate table may be, for example, a two-dimensional matrix table in which the motor speed is on the horizontal axis and the accelerator opening is on the vertical axis, representing the torque increase rate corresponding to each accelerator opening and each motor speed.

[0036] In regenerative braking mode, the motor control unit 7 determines (changes) the torque reduction rate based on the current torque and motor speed of the motor 3. Specifically, the motor control unit 7 sets the torque reduction rate when the current torque is below the threshold torque to be smaller than the torque reduction rate when the current torque is above the threshold torque. In other words, under the same motor speed conditions, the motor control unit 7 sets the torque reduction rate when the current torque is below the threshold torque to be smaller than the torque reduction rate when the current torque is above the threshold torque. Furthermore, the motor control unit 7 determines (changes) the torque reduction rate when the current torque is below the threshold torque and the torque reduction rate when the current torque is above the threshold torque according to the motor speed. Note that if the motor speeds are different, it is not necessary to make the torque reduction rate when the current torque is below the threshold torque smaller than the torque reduction rate when the current torque is above the threshold torque. The threshold torque is not particularly limited.

[0037] The motor control unit 7 may, for example, determine the torque reduction rate based on the current torque and motor speed of the motor 3 by referring to a table (torque reduction rate table) that associates the current torque, motor speed, and torque reduction rate. The torque reduction rate table may be, for example, a table in which the torque reduction rate corresponding to each current torque and each motor speed is represented in a two-dimensional matrix with motor speed on the horizontal axis and current torque on the vertical axis.

[0038] Furthermore, the motor control unit 7 makes the torque decrease rate in the regenerative state smaller than the torque increase rate in the motorized state, under the same accelerator opening condition. However, if the accelerator opening is different, it is not necessary to make the torque decrease rate in the regenerative state smaller than the torque increase rate in the motorized state.

[0039] Here, with reference to Figure 3, the torque rates for each of the above states will be explained. Figure 3 is a diagram corresponding to Figure 2 for explaining the torque rates for each state. As shown in Figure 3, the state in which the accelerator opening exceeds the threshold opening during powering is called the high-accelerator state A, and the state in which the accelerator opening falls below the threshold opening during powering is called the low-accelerator state B. In the high-accelerator state A, it is assumed that the driver is pressing the accelerator with the intention of accelerating the electric vehicle 2 immediately, so the torque increase rate is increased. In other words, the amount of torque increase per unit time is increased. On the other hand, in the low-accelerator state B, it is assumed that the driver is pressing the accelerator with the intention of accelerating the electric vehicle 2 slowly, so the torque increase rate is smaller than in the high-accelerator state A. In other words, the amount of torque increase per unit time is smaller than in the high-accelerator state A.

[0040] Furthermore, in the regenerative state, the state in which the current torque falls below the threshold torque is called the low regenerative torque state C, and in the regenerative state, the state in which the current torque exceeds the threshold torque is called the high regenerative torque state D. In the high regenerative torque state D, the torque decrease rate is reduced to suppress sudden deceleration that is not intended by the driver. In other words, the amount of torque decrease per unit time is reduced. On the other hand, in the low regenerative torque state C, the torque decrease rate is increased compared to the high regenerative torque state D in order to suppress a decrease in the amount of regeneration from motor 3. In other words, the amount of torque decrease per unit time is increased compared to the high regenerative torque state D.

[0041] Furthermore, in regenerative braking, a high torque rate makes it more difficult to match the target deceleration compared to the powered state. Therefore, under the same accelerator opening conditions, the torque rate (torque decrease rate) in regenerative low torque state C and regenerative high torque state D is made smaller than the torque rate (torque increase rate) in powered high-opening state A and powered low-opening state B. More specifically, under the same motor rotational speed conditions, the torque rate is decreased in the order of powered high-opening state A, powered low-opening state B, regenerative low torque state C, and regenerative high torque state D. Note that the torque increase rate and torque decrease rate have opposite signs, so decreasing the torque rate means decreasing the absolute value of the torque rate.

[0042] As shown in Figure 1, once the motor control unit 7 determines the torque rate, it controls the motor 3 so that the torque of the motor 3 becomes the target torque at the determined torque rate. Specifically, the motor control unit 7 calculates the torque by adding the torque rate to the current torque as the instructed torque. Then, if the instructed torque is less than the target torque, the motor control unit 7 controls the motor 3 with the instructed torque. On the other hand, if the instructed torque is equal to or greater than the target torque, the motor control unit 7 controls the motor 3 with the target torque.

[0043] Next, an example of the processing operation of the electric vehicle control device 1 will be described with reference to Figure 4. Figure 4 is a flowchart showing an example of the processing operation of the electric vehicle control device.

[0044] As shown in Figure 4, first, the electric vehicle control device 1 acquires the accelerator opening, motor speed, and current torque (step S1). The accelerator opening is acquired from the accelerator opening detection unit 4, the motor speed is acquired from the motor speed detection unit 5, and the current torque is acquired from the current torque detection unit 6. Next, the electric vehicle control device 1 determines the target torque based on the accelerator opening and motor speed acquired in step S1 (step S2). The target torque is determined, for example, by referring to a governor map. Next, the electric vehicle control device 1 determines whether the target torque determined in step S2 is greater than the current torque acquired in step S1 (step S3).

[0045] If the motor control device 1 determines that the target torque is greater than the current torque (step S3: YES), it determines that the vehicle is in a powered state and calculates the torque increase rate (torque rate) based on the accelerator opening and motor rotation speed obtained in step S1 (step S4). In step S4, the motor control device 1 calculates the torque increase rate by referring to a torque increase rate table, etc., such that the torque increase rate when the accelerator opening is below the threshold opening is smaller than the torque increase rate when the accelerator opening is above the threshold opening.

[0046] On the other hand, if it is determined that the target torque is not greater than the current torque (Step S3: NO), the electric vehicle control device 1 determines that it is in a regenerative state and calculates the torque reduction rate (torque rate) based on the current torque and motor rotation speed obtained in Step S1 (Step S5). In Step S5, the electric vehicle control device 1 calculates the torque reduction rate by referring to the torque reduction rate table, etc., such that the torque reduction rate when the current torque is below the threshold torque is smaller than the torque reduction rate when the current torque is above the threshold torque. Also, the electric vehicle control device 1 calculates the torque reduction rate by referring to the torque reduction rate table, etc., such that the torque rate is smaller than the torque increase rate that is calculated when it is determined that the target torque is greater than the current torque (Step S3: YES).

[0047] Then, the electric vehicle control device 1 determines the target torque based on the current torque obtained in step S1 and the torque increase rate (torque rate) obtained in step S4 or the torque decrease rate (torque rate) obtained in step S5 (step S6). In step S6, the electric vehicle control device 1 determines the target torque by adding the determined torque increase rate or torque decrease rate to the current torque. Next, the electric vehicle control device 1 determines whether the target torque obtained in step S6 is smaller than the target torque obtained in step S2 (step S7).

[0048] If the motor control device 1 determines that the instructed torque is smaller than the target torque (step S7: YES), it controls the motor 3 with the instructed torque determined in step S6 (step S8). Then, the motor control device 1 terminates the process and repeats from step S1.

[0049] On the other hand, if it is determined that the instructed torque is not less than the target torque (step S7: NO), the electric vehicle control device 1 controls the motor 3 with the target torque determined in step S2 (step S9). Then, the electric vehicle control device 1 terminates the process and repeats from step S1 again.

[0050] As described above, the electric vehicle control device 1 according to this embodiment can change the torque rate based on the accelerator opening, which is the driver's operation, and can appropriately reflect the driver's intentions regarding the acceleration and deceleration of the electric vehicle 2 in response to the driver's operation.

[0051] Furthermore, this electric vehicle control device 1 can change the torque rate by determining the torque rate based on the accelerator opening and motor rotation speed, taking into account the effects of driving resistance and other factors that vary with vehicle speed. This makes it possible to provide the driver with a good driving feel for each speed range of the vehicle.

[0052] Furthermore, in this electric vehicle control device 1, when the accelerator opening is below a threshold opening during powered operation, the torque rate is set to be smaller than the torque rate when the accelerator opening is above the threshold opening. As a result, when the accelerator opening is small, the torque rate is small, which can reflect the driver's intention to accelerate the electric vehicle 2 slowly. On the other hand, when the accelerator opening is large, the torque rate is large, which can reflect the driver's intention to accelerate the electric vehicle immediately.

[0053] Furthermore, in this electric vehicle control device 1, when the current torque falls below the threshold torque during regenerative braking, the torque rate is set to be smaller than the torque rate when the current torque exceeds the threshold torque. This prevents sudden deceleration that is not intended by the driver when the current torque is high. As a result, it is possible to prevent the driver from being prompted to re-accelerate or the cargo from shifting. On the other hand, when the current torque is low, it is possible to prevent a reduction in the amount of regenerative braking from the motor 3.

[0054] Furthermore, in this electric vehicle control device 1, by making the torque rate in the regenerative state smaller than the torque rate in the accelerating state, the deceleration of the electric vehicle 2 becomes gentler, making it easier for the driver to adjust to the target deceleration.

[0055] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and may be modified or applied to other things without changing the gist of each claim.

[0056] For example, in the above embodiment, the torque increase rate was described as being changed based on the accelerator opening and the motor rotation speed, but the torque increase rate may be changed based on the accelerator opening but not on the motor rotation speed.

[0057] Furthermore, although the above embodiment was described as changing both the torque increase rate and the torque decrease rate, it is also possible to change only the torque increase rate. [Explanation of Symbols]

[0058] 1...Electric vehicle control device, 2...Electric vehicle, 3...Motor, 4...Accelerator opening detection unit, 5...Motor rotation speed detection unit, 6...Torque detection unit, 7...Motor control unit, A...High acceleration opening state, B...Low acceleration opening state, C...Low regenerative torque state, D...High regenerative torque state.

Claims

1. An electric vehicle control device that controls the acceleration and deceleration of an electric vehicle that uses a motor as its driving source, The accelerator opening detection unit detects the accelerator opening of the electric vehicle, A motor rotation speed detection unit that detects the motor rotation speed, A motor control unit that controls the motor, The system includes a current torque detection unit that detects the current torque generated by the motor, The motor control unit, Based on the accelerator opening and the motor rotation speed, the target torque is determined. Based on the aforementioned accelerator opening, the torque rate, which is the amount of change in torque per unit time, is determined. The motor is controlled so that the torque of the motor becomes the target torque at the torque rate. The motor control unit, under the condition that the accelerator opening is the same, makes the torque rate in the regenerative state, when the target torque is smaller than the current torque, smaller than the torque rate in the accelerating state, when the target torque is larger than the current torque. Electric vehicle control device.

2. The motor control unit determines the torque rate based on the motor rotation speed. The electric vehicle control device according to claim 1.

3. In the powering state, the motor control unit makes the torque rate when the accelerator opening is below the threshold opening smaller than the torque rate when the accelerator opening is above the threshold opening. The electric vehicle control device according to claim 1 or 2.

4. In the regenerative state, the motor control unit makes the torque rate when the current torque is below the threshold torque smaller than the torque rate when the current torque is above the threshold torque. The electric vehicle control device according to claim 3.

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