JP2001197613A - Motor controller for electric motor car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller for electric car, which can control the torque of the motor of an electric motor car corresponding to the running state of the car so that the car exhibits smooth acceleration capability and sufficient climbing ability. SOLUTION: The motor controller, which decides the then target torque of the motor of the electric motor car, according with the present running state of the car and controls the torque of the motor according to the decided target torque is provided with a means which calculates the estimated external force applied to the car, by performing prescribed arithmetic processing, using the set values of the weight and running resistance of the car and the target torque, a means which decides such a motor torque that cancels the calculated estimated external force as an auxiliary torque, and a means which corrects the target torque, by adding the auxiliary torque to the target torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for an electric vehicle which controls a driving motor in the electric vehicle.

[0002]

2. Description of the Related Art Conventionally, in an electric vehicle such as a golf cart having no transmission, an accelerator opening and a current speed of the vehicle are detected, and a speed is previously set as a parameter based on each detection result. The target torque at that time is determined using a table in which the characteristics of the target torque with respect to the accelerator opening are set, and the torque control of the driving motor is performed according to the determined target torque. .

As shown in FIG. 4, a general torque characteristic of a motor in such an electric vehicle is often not flat in a practical rotation speed region due to a maximum applied voltage and a maximum allowable current.

[0004] In this case, if the characteristic is set so that the maximum torque is output at an accelerator opening of 100%, excessive torque is generated in a low speed range, causing uneven acceleration, and the drive feeling is deteriorated. . In order to avoid this, as shown by the dotted line in the figure, when the limiter control is performed such that the motor torque is kept below a certain value in the low speed range,
Although smooth acceleration can be performed and drive feeling is improved, the torque performance of the motor cannot be sufficiently exhibited, and the ability to climb a hill and the like is reduced.

[0005]

The problem to be solved is that the characteristic of the target torque with respect to the accelerator opening is set in advance by using the speed as a parameter based on each detection result of the accelerator operation amount and the current speed of the vehicle. When the target torque at that time is determined using the table that has been set, and the torque control of the drive motor of the electric vehicle is performed in accordance with the determined target torque, the output torque of the motor is suppressed in a low speed range to achieve a smooth operation. If the target torque is set in a table with such characteristics that acceleration can be performed, the torque performance of the motor cannot be sufficiently exhibited, and the climbing ability and the like will be reduced.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a motor for an electric vehicle which determines a target torque at that time in accordance with a current driving state of the vehicle and performs torque control of the motor in accordance with the determined target torque. In the control device, in order to perform the torque control of the motor in accordance with the running state of the vehicle so that the smooth acceleration performance and sufficient uphill performance can be exhibited, each set value of the vehicle weight and the running resistance and Means for calculating an estimated external force applied to the vehicle by a predetermined calculation process using the target torque, means for determining a motor torque that cancels out the calculated estimated external force as an auxiliary torque, and applying the auxiliary torque to the target torque. In addition, means for correcting the target torque is provided, and the torque of the motor is controlled in accordance with the corrected target torque.

[0007]

FIG. 1 shows an example of the configuration of a motor control device for an electric vehicle for carrying out the present invention.

The motor control device for an electric vehicle includes an accelerator opening detector 1 for detecting an accelerator opening, a rotation detector 2 for detecting a rotation speed of a motor 6 for driving the vehicle, and a motor 6 for detecting the detected motor 6. The current speed of the vehicle at that time is obtained from the rotation speed of the vehicle, and the characteristic of the target torque with respect to the accelerator opening is previously set using the speed as a parameter based on the detected accelerator opening and the current speed. And an arithmetic processing unit 3 for obtaining a motor drive control amount according to the obtained target torque, and controlling the drive of the motor 6 via the inverter 5 in accordance with the obtained control amount. And a motor control unit 4 for performing the operation.

The arithmetic processing unit 3 and the motor control unit 4 are specifically constituted by an ECU. As the motor 6, for example, a three-phase magnet synchronous motor capable of controlling torque is used.

The target torque is set in the table with such a characteristic that the output torque of the motor can be suppressed in a low speed range and smooth acceleration can be performed.

The present invention is constructed as described above, and in particular, the present invention is applied to a vehicle which performs predetermined arithmetic processing using set values of vehicle weight and running resistance and the target torque obtained as described above. Means for calculating an estimated external force according to the present invention, means for determining a motor torque that cancels out the calculated estimated external force as an auxiliary torque, and means for correcting the target torque by adding the auxiliary torque to the target torque. Is provided, and the torque of the motor is controlled in accordance with the corrected target torque.

Specifically, each of these means is executed in the arithmetic processing unit 3.

FIG. 2 shows a flow of processing in executing each of those means.

Hereinafter, the present invention will be described with reference to the processing flow shown in FIG.

First, the accelerator opening and the current speed are detected at a predetermined control cycle ΔT (step S).
1) Based on the respective detection results, a propulsion force F1 corresponding to a target torque serving as a reference at that time is obtained from a table (step S2).

The propulsion force F1 of the vehicle according to the motor torque
If the vehicle weight is M on a flat road, the vehicle's inherent running resistance is μ, the current speed is V, and the acceleration applied to the vehicle is A, it is approximated by the equation of motion expressed by the following equation (1). You.

F1 = M × A + μ × V (1)

In accordance with this approximate expression, the values of the vehicle weight M and the running resistance μ set in advance are used to follow the propulsion force F1 of the vehicle corresponding to the current speed V and the target torque obtained at that time. The acceleration A is calculated by the following equation (2) (step S3).

A = (F1−μ × V) / M (2)

This approximate expression is based on the vehicle weight M and the running resistance μ.
This is true only when the vehicle is traveling on a flat road, and when running on an uphill road or receiving strong wind from the front, external forces such as climbing force and wind resistance work. And it does not hold. If the external force is G,
It can be estimated by the following equation (3).

G = F1−M × A−μ (3)

Next, based on the equation (3), the estimated external force G
Is calculated (step S4), and the auxiliary propulsion force F2 corresponding to the calculated auxiliary torque corresponding to the calculated estimated external force G is derived from a preset map (step S5).

The present invention is basically based on the target torque T1 determined according to the accelerator opening and the current speed, and the added auxiliary propulsion F2 added to the thrust F1 corresponding to the target torque. Perform correction (Step S
8) The drive control of the motor is performed according to the corrected target torque (step S9).

At this time, when the estimated external force G is directly added to the target torque as an auxiliary torque to perform motor control, if the estimated external force G is small, the feedback control swings in the positive and negative directions and becomes unstable. I will.

Therefore, in the present invention, in order to stably perform the torque control of the motor, the low-pass filter processing of the auxiliary propulsion force F2 according to the auxiliary torque corresponding to the estimated external force G is performed (step S6).

In the present invention, it is further determined whether or not the auxiliary propulsion force F2 is greater than a preset threshold value fs (step S7). If F2> fs, that is, if the estimated external force G is The target torque is corrected only when the value exceeds a certain value (step S
8).

In the present invention, it is further determined whether or not the auxiliary propulsion force F2 is greater than a preset threshold value fs (step S7). If F2> fs, that is, if the estimated external force G is The target torque is corrected only when the value exceeds a certain value (step S
8).

FIG. 3 shows the characteristic of the auxiliary propulsion force F2 with respect to the estimated external force G at that time.

When the torque of the motor is controlled by adding the estimated external force G as an auxiliary torque to the target torque as it is as the value of fs, the control by the feedback does not swing in the positive and negative directions and becomes unstable. Set to value.

If F2 ≦ fs at this time, the motor torque is controlled with the propulsion force F1 corresponding to the target torque determined according to the accelerator opening and the current speed (step S10).

The above-described processing is repeatedly executed at regular intervals ΔT.

Further, the present invention is provided with means for detecting the running torque of the vehicle, so that the target torque is corrected when the calculated estimated external force G applied to the vehicle exceeds the detected running torque. It is also possible.

[0031]

As described above, the present invention determines the target torque at that time according to the current driving state of the vehicle, and controls the motor torque in accordance with the determined target torque. A means for calculating an estimated external force applied to the vehicle by a predetermined calculation process using each set value of the vehicle weight and the running resistance and a target torque, and assisting a motor torque that cancels the calculated estimated external force. A means for determining the torque and a means for correcting the target torque by adding the auxiliary torque to the target torque are provided, and the torque of the motor is controlled according to the corrected target torque. In addition, it is possible to control the torque of the motor according to the running condition of the vehicle so that the smooth acceleration performance and sufficient climbing ability can be exhibited. The it has.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a motor control device of an electric vehicle for implementing the present invention.

FIG. 2 is a diagram showing a flow of processing in a motor control device for an electric vehicle according to the present invention.

FIG. 3 is a flowchart for correcting a target torque when an estimated external force G exceeds a threshold value fs.
It is a figure which shows the characteristic of the auxiliary propulsion force F2 with respect to.

FIG. 4 is a diagram showing general torque characteristics of a drive motor in an electric vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Accelerator opening detector 2 Rotation detector 3 Operation processing part 4 Motor control part 5 Inverter 6 Motor

Claims (4)

[Claims] 1. A motor control device for an electric vehicle that determines a target torque at that time according to a current driving state of the vehicle and controls torque of a motor according to the determined target torque. Means for calculating an estimated external force applied to the vehicle by predetermined calculation processing using each set value of the resistance and the target torque; means for determining a motor torque that cancels the calculated estimated external force as an auxiliary torque; Means for correcting the target torque by adding the auxiliary torque to the torque, and controlling the motor torque in accordance with the corrected target torque. apparatus. 2. The motor control device for an electric vehicle according to claim 1, wherein a low-pass filter process is performed when outputting the auxiliary torque. 3. The electric vehicle according to claim 1, wherein the target torque is corrected when the calculated estimated external force applied to the vehicle exceeds a preset threshold value. Motor control device. 4. A device for detecting a running torque of a vehicle, wherein a target torque is corrected when a calculated estimated external force applied to the vehicle exceeds the detected running torque. A motor control device for an electric vehicle according to claim 1.