JP4203873B2 - Electric vehicle motor control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a motor control device for an electric vehicle that controls a drive motor in the electric vehicle.
[0002]
[Prior art]
Conventionally, in an electric vehicle such as a golf cart that does not have a transmission, the accelerator opening and the current speed of the vehicle are detected, and based on the respective detection results, the speed is used as a parameter in advance for the accelerator opening. A target torque at that time is determined using a table in which the characteristics of the target torque are set, and torque control of the drive motor is performed according to the determined target torque.
[0003]
The general torque characteristics of a motor in such an electric vehicle are often not flat in the practical rotational speed region due to the maximum applied voltage and the maximum allowable current, as shown in FIG.
[0004]
In such a case, if the characteristic is set such that the maximum torque is output at the accelerator opening of 100%, excessive torque is generated in the low speed region, resulting in uneven acceleration, resulting in poor drive feeling. To avoid this, as shown by the dotted line in the figure, when the limiter control is performed to keep the motor torque below a certain level in the low speed range, smooth acceleration can be achieved and drive feeling is improved. However, the torque performance of the motor cannot be fully exhibited, and the climbing ability and the like are reduced.
[0005]
[Problems to be solved by the invention]
The problem to be solved is based on the detection results of the accelerator operation amount and the current vehicle speed, using a table in which the target torque characteristics for the accelerator opening are set in advance using the speed as a parameter. When the target torque is determined and the torque control of the drive motor of the electric vehicle is performed according to the determined target torque, the motor output torque can be suppressed in the low speed range so that smooth acceleration can be performed. If the target torque is set in a table with characteristics, the torque performance of the motor cannot be fully exhibited, and the climbing ability and the like are reduced.
[0006]
[Means for Solving the Problems]
The present invention relates to a motor controller for an electric vehicle that determines a target torque at that time according to the current driving state of the vehicle and performs torque control of the motor according to the determined target torque. Each set value of the vehicle weight and running resistance and the target determined as described above in order to perform motor torque control suitable for the running state of the vehicle so that the performance and sufficient climbing ability can be exhibited. Means for obtaining a target speed by a predetermined calculation process using torque, means for obtaining an auxiliary torque by a predetermined calculation process based on a deviation between the obtained target speed and the current speed, and the auxiliary torque as a target torque Means for correcting the target torque by adding a torque to the motor, and the torque control of the motor is performed in accordance with the corrected target torque.
[0007]
【Example】
FIG. 1 shows a configuration example of a motor control device for an electric vehicle for carrying out the present invention.
[0008]
The motor control device for the electric vehicle includes an accelerator opening detector 1 that detects the accelerator opening, a rotation detector 2 that detects the rotation speed of the motor 6 for driving the vehicle, and the rotation speed of the detected motor 6. The current torque of the vehicle at that time is obtained from the table, and the target torque at that time is determined from a table in which the characteristics of the target torque with respect to the accelerator opening are set in advance based on the detected accelerator opening and the current speed. And a calculation processing unit 3 for obtaining a control amount for driving the motor in accordance with the obtained target torque, and a motor control for controlling the driving of the motor 6 via the inverter 5 in accordance with the obtained control amount. Part 4.
[0009]
The arithmetic processing unit 3 and the motor control unit 4 are specifically configured by an ECU. As the motor 6, for example, a three-phase magnet synchronous motor capable of torque control is used.
[0010]
In the table, the target torque is set with such characteristics that the motor output torque can be suppressed and smooth acceleration can be performed in the low speed range.
[0011]
The present invention is configured as described above. In particular, the target speed is obtained by a predetermined calculation process using the set values of the vehicle weight and the running resistance and the target torque determined as described above. Means, means for obtaining an auxiliary torque by a predetermined calculation process based on a deviation between the obtained target speed and the current speed, and means for correcting the target torque by adding the auxiliary torque to the target torque. The torque control of the motor is performed according to the corrected target torque.
[0012]
Specifically, each of those means is executed in the arithmetic processing unit 3.
[0013]
FIG. 2 shows a processing flow when executing each of these means.
[0014]
Hereinafter, the present invention will be described together with the processing flow shown in FIG.
[0015]
First, the accelerator opening and the current speed are detected with a predetermined control period ΔT (step S1), and a propulsive force F1 corresponding to the target torque serving as a reference at that time is obtained from the table based on each detection result. (Step S2).
[0016]
When the vehicle propulsive force F1 according to the motor torque is a flat road, the vehicle weight is M, the inherent running resistance of the vehicle is μ, the current speed is V, and the acceleration applied to the vehicle is A, F1 = M It is approximated by the equation of motion of × A + μ × V.
[0017]
In accordance with this approximate expression, the target acceleration A according to the propulsive force F1 of the vehicle corresponding to the current speed V and the target torque obtained at that time using the preset values of the vehicle weight M and the running resistance μ. Is calculated by the following equation (1) (step S3).
[0018]
A = (F1−μ × V) / M (1)
[0019]
Then, by integrating the calculated target acceleration A over time, a reference target speed Vo is obtained in an update manner as shown in the following equation (2) (step S4).
[0020]
Vo = Vo + ΔT × A (2)
[0021]
Next, a deviation Err between the obtained target speed Vo and the current speed V is obtained (step S5), and it is determined whether or not the deviation Err at that time is smaller than a preset threshold value α (step S5). Step S6).
[0022]
At this time, if Err <α, the value of the speed deviation Err is left as it is.
[0023]
At that time, if Err ≧ α, Err = α is set so that the value of the speed deviation Err at that time does not exceed α (step S7), and the target speed Vo is set to the current speed V Is corrected by adding an α value to (step S8).
[0024]
As the threshold value α, when Vo = V + α and the target speed Vo is limited to the current speed V plus an α value, for example, when the accelerator pedal is depressed on an uphill road, the vehicle accelerates rapidly. It is set to such a value that an auxiliary propulsive force F <b> 2 can be obtained.
[0025]
Next, it is determined whether or not the value of the speed deviation Err is greater than 0, that is, whether or not the target speed Vo is in an acceleration state in which the target speed Vo is greater than the current speed V and an auxiliary torque is required (step S9). .
[0026]
At this time, if Err> 0, a value obtained by subtracting a preset value β from the Err value is set as a new Err value (step S10). That is, when the auxiliary torque is output, in order to prevent control oscillation, the speed deviation Err is obtained when a certain value β is exceeded.
[0027]
As the value of β, if the Err value is too small, the feedback control for converging to the target speed at that time will swing in the positive and negative directions and become unstable. When generating, the auxiliary propulsive force F2 at that time is set to a value that does not become negative.
[0028]
At this time, if Err ≦ 0, the Err value is left as it is.
[0029]
Next, using the Err value, an auxiliary propulsive force F2 corresponding to the auxiliary torque at that time is obtained according to the following equation (3) (step S11).
[0030]
F2 = ΣErr × G (3)
Here, G is a preset integral control gain value.
The auxiliary propulsive force F2 is calculated using the new Err value (step S12).
[0031]
Next, a limiter process for the auxiliary propulsive force F2 is performed (step S13). In the case of integral control, the limiter process limits the auxiliary propulsive force F2 in accordance with the accelerator opening because the torque continues to increase unless the deviation becomes zero. Specifically, the limiter process is performed by multiplying the detected accelerator opening or speed deviation Err by the auxiliary propulsive force F2.
[0032]
Finally, the target torque is corrected by adding the auxiliary propulsive force F2 corresponding to the auxiliary torque to the auxiliary propulsive force F1 corresponding to the target torque derived from the table based on the accelerator opening and the current speed. (Step S14), and drive control of the motor is performed according to the corrected target torque.
[0033]
The above process is repeatedly executed at regular intervals ΔT.
[0034]
At this time, the present invention is such that when the deviation Err between the target speed Vo and the current speed V exceeds a preset value, such as when the accelerator pedal is depressed on an uphill road, for example, in the arithmetic processing unit 3. Further, the target torque is corrected by adding the auxiliary propulsive force F2 corresponding to the auxiliary torque to the auxiliary propulsive force F1 corresponding to the target torque.
[0035]
Further, according to the present invention, the arithmetic processing unit 3 determines that the accelerator opening has changed in the decreasing direction, and the auxiliary propulsive force F1 according to the target torque until then according to the amount of change in the accelerator opening at that time. The auxiliary propulsive force F2 corresponding to the auxiliary torque applied to is reduced.
[0036]
【The invention's effect】
As described above, the present invention provides a motor control device for an electric vehicle that determines a target torque at that time according to the current driving state of the vehicle and performs torque control of the motor according to the determined target torque. The target speed is obtained by a predetermined calculation process using each set value of the weight and running resistance and the target torque, and the auxiliary torque is obtained by a predetermined calculation process based on a deviation between the obtained target speed and the current speed. Because the target torque is corrected by adding the auxiliary torque to the target torque, the torque control of the motor in accordance with the running state of the vehicle that can exhibit smooth acceleration performance and sufficient climbing ability It has the advantage that can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a motor control device for an electric vehicle for carrying out the present invention.
FIG. 2 is a diagram showing a processing flow in a motor control device for an electric vehicle according to the present invention.
FIG. 3 is a diagram showing general torque characteristics of a drive motor in an electric vehicle.
[Explanation of symbols]
1 Accelerator opening detector 2 Rotation detector 3 Arithmetic processing unit 4 Motor control unit 5 Inverter 6 Motor

Claims (5)

In a motor control device for an electric vehicle that determines a target torque at that time according to the current driving state of the vehicle and performs torque control of the motor according to the determined target torque, each set value of vehicle weight and running resistance Means for determining a target speed by a predetermined calculation process using the target torque, means for determining an auxiliary torque by a predetermined calculation process based on a deviation between the determined target speed and the current speed, A motor control apparatus for an electric vehicle, characterized in that a means for correcting the target torque by applying an auxiliary torque is provided, and the torque control of the motor is performed according to the corrected target torque. 2. The motor control device for an electric vehicle according to claim 1, wherein the target speed is limited so that a deviation between the target speed and the current speed becomes smaller than a preset threshold value. 2. The motor control device for an electric vehicle according to claim 1, wherein the auxiliary torque is limited based on an accelerator opening or a speed deviation. 2. The motor control device for an electric vehicle according to claim 1, wherein an auxiliary torque is applied when a deviation between the target speed and the current speed exceeds a preset value. 2. The motor control device for an electric vehicle according to claim 1, wherein the auxiliary torque is reduced in accordance with a change amount when the accelerator opening changes in a decreasing direction.

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