JP2002199513A - Torque controller for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hunting in the region where opening level of an accelerator is low and to improve sense of acceleration in the region where opening level of the accelerator is intermediate. SOLUTION: A controller is loaded with a map of the opening level of the accelerator and a load factor of a motor, and calculates a torque command value based on the load factor of the motor obtained by referring to the map by the opening level of the accelerator. Variation of the load factor of the motor responding to the change in the opening level of the accelerator is set small in the region where the opening level of the accelerator is low, and is set large where the opening level of the accelerator is intermediate. Fine adjustment of the torque command value is enabled in the region where the opening level of the accelerator is low, and hunting is prevented. Variation of the torque command value is increased and the sense of acceleration is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling electric power supplied to a motor of an electric vehicle based on a torque command value, that is, a torque control device for an electric vehicle.

[0002]

2. Description of the Related Art An electric vehicle is a vehicle on which a battery and a motor are mounted and the motor is a driving source. FIG. 5 shows a schematic configuration of an electric vehicle.

A main battery indicated by reference numeral 10 in FIG. 1 supplies a predetermined DC voltage to an inverter 12. The inverter 12 converts the DC voltage from the main battery 10 into three-phase AC power under the control of the controller 14 and supplies the three-phase AC power to the motor 16. The motor 16 rotates by receiving power supply from the inverter 12 and supplies the mechanical output to drive wheels via a shaft or the like. The controller 14 detects the rotation speed N of the motor 16 with the rotation speed sensor 18 and controls the operation of the inverter 12 according to an accelerator signal, a brake signal, and the like.

Specifically, a controller 14 determines a torque command value in accordance with an accelerator opening input as an accelerator signal or the like, and based on the torque command value, turns on / off each switching element of the inverter 12. By controlling the operation, the torque of the motor 16 is controlled to a motor command value. At this time, the controller 14 determines the torque command value so as to be linear with respect to the accelerator opening as shown in FIG.

[0005]

However, in such a device that determines the torque command value linearly with respect to the accelerator opening, it is difficult to finely adjust the motor torque in a region where the accelerator opening is low. That is, the change in the actual motor torque with respect to the change in the accelerator opening may be larger than the change requested by the driver, and as a result, hunting may occur.

In the region where the accelerator opening is medium,
Since the change in the motor torque with respect to the change in the accelerator opening is smaller than the driver's request, an acceleration sensation that matches the driver's feeling may not be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to prevent hunting and the like in a region where the accelerator opening is low, and to improve the feeling of acceleration in a region where the accelerator operation is moderate. Aim.

[0008]

In order to achieve the above object, a torque control device according to the present invention has a small torque command value with respect to a change in the accelerator opening in a region where the accelerator opening is low. It is characterized in that the torque command value is calculated so that the amount of change in the torque command value with respect to the change in the accelerator opening becomes large in a region where the degree is medium.

A torque control device according to a second aspect of the present invention calculates a smoothing torque command value so as to gradually approach a torque command value calculated based on the accelerator opening with time. The value is given to the control means as a torque command value. Further, the torque control device according to claim 3 of the present invention provides a torque command value for a previous torque command value such that the motor torque changes more slowly than a change in the torque command value calculated based on the accelerator opening. Calculating a smoothing torque command value corresponding to a value obtained by adding a part of the change amount to the previous torque command value according to the smoothing constant, and providing the smoothing torque command value to the control means as a torque command value. Features.

[0010]

In the present invention, the amount of change in the torque command value is set small in a region where the accelerator opening is low. Therefore,
The torque command value can be finely adjusted according to the accelerator opening, and hunting and the like are prevented. In a region where the accelerator opening is medium, the amount of change in the torque command value is set large. Therefore, for example, the torque command value greatly changes with respect to the accelerator opening as compared with a region where the accelerator opening is low, so that the feeling of acceleration is improved.

According to the second and third aspects of the present invention, the torque of the motor is controlled based on the smoothing torque command value calculated to approach the torque command value. Therefore, transient motor torque fluctuation is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

The torque control according to the feature of the present invention can be implemented in an electric vehicle having a configuration as shown in FIG. 5, for example. FIG. 1 shows a flow of operation of the controller 14 at a predetermined cycle when the torque control according to the first embodiment of the present invention is performed by the controller 14 shown in FIG.

As shown in this figure, in the present embodiment, when controlling the torque of the motor 16 in response to the depression of the accelerator, first, the motor load factor RMP is determined (100). That is, in the present embodiment, the controller 14 has a map of the accelerator opening and the motor load ratio RMP, and the controller 14 refers to this map based on the accelerator opening input as the accelerator signal, thereby obtaining the motor load. Determine the rate RMP. As shown in FIG. 2A, for example, the map mounted on the controller 14 is such that the amount of change in the motor load ratio RMP in a region where the accelerator opening is low is smaller than in the past, and the amount of change in a medium region is Larger maps can be used. Further, the change amount of the motor load ratio RMP in the region where the accelerator opening is high is almost the same as that in the region where the accelerator opening is low. Further, as shown in FIG. 2B, when the accelerator opening becomes extremely high, the motor load ratio RMP
May be almost constant.

The controller 14 has a motor load factor RMP
Is calculated, a torque command value Tc is calculated based on the motor load factor RMP (102). This calculation is performed for the motor 1
6 is a calculation for apportioning the torque range determined by the maximum torque Tmax and the minimum torque Tmin with the motor load factor RMP. That is, the torque command value Tc is calculated based on the following equation. Note that the maximum torque Tmax and the minimum torque Tmin may be obtained by referring to the Tmax table and the Tmin table based on the rotation speed N. The controller 14 has these tables.

Tc = (Tmax−Tmin) × RMP + Tmin The controller 14 executes torque control based on the torque command value Tc calculated in this way (104). For example, a PW having a pulse width corresponding to the torque command value Tc
M signal is generated, and the inverter 1 is
By controlling the two switching elements, the motor 1
6 is controlled.

When such control is performed, hunting is prevented in a region where the accelerator opening is low, and the feeling of acceleration is improved in a region where the accelerator operation is moderate. That is, FIG.
Since the rate of change of the motor load ratio RMP is low in the region where the accelerator opening is low, the motor load ratio RMP according to the accelerator opening and, consequently, the torque command value Tc
Can be fine-tuned, which reduces hunting. Further, in a region where the accelerator opening is medium, the amount of change in the motor load ratio RMP with respect to the change in the accelerator opening is large, so that a higher feeling of acceleration can be obtained than when the accelerator is depressed.

FIG. 3A shows a flow of the operation of the controller 14 according to the second embodiment of the present invention. This embodiment differs from the first embodiment shown in FIG. 1 in that smoothing control is performed on the torque command value Tc. That is, in this embodiment, steps 102 and 10
During steps 4, steps 106 and 108 are performed.

In step 106, step 10
It is calculated how much the torque command value calculated in 2 has changed from the previous torque command value. here,
Assuming that the torque command value obtained in the previous execution of the step 108 is Tc and the torque command value calculated in the immediately preceding step 102 is Tc0, the torque command value change amount ΔTc obtained in the step 106 is ΔTc = Tc0−Tc It is expressed as

In step 108, a new smoothing torque command value Tc is calculated using the torque command value change amount ΔTc thus obtained and the previous torque command value Tc. That is, Tc = Tc + ΔTc / n is calculated. Here, n is an annealing constant.

When the processing shown in FIG. 3A is sequentially and repeatedly executed, the change in the torque command value with respect to the accelerator operation is as shown in FIG. 3B. In this figure, what is indicated as Tc0 is the torque command value calculated in step 102 of FIG. 3A, and increases or decreases in a stepwise manner according to the operation of the accelerator. The torque command value Tc indicated by the broken line is a smoothing torque command value calculated in step 108,
Since the change with respect to the previous torque command value Tc is suppressed by the smoothing constant n, the change is dull with respect to the torque command value Tc0.

Therefore, according to the present embodiment, the torque change accompanying the accelerator operation can be reduced, and the transient torque fluctuation of the motor 16 can be suppressed. As a result, torque shock is reduced.

Further, by such smoothing control, a feeling close to that of a gasoline-powered vehicle can be obtained. In a gasoline-powered vehicle, the change in the output torque with respect to the accelerator operation is slightly smaller than the change in the output torque of the motor 16 in the electric vehicle. Therefore, by performing the smoothing control on the torque command value Tc as in the present embodiment, A feeling close to a gasoline car can be obtained.

FIG. 4A shows the operation of the controller 14 in the device according to the third embodiment of the present invention. In this embodiment, steps 110 and 112 are executed after execution of step 100 and before execution of step 102.

Step 110 is a step of calculating a motor load factor change amount ΔRMP based on the motor load factor obtained in step 100. Now, the motor load factor obtained in the previous execution of step 112 is represented by RM
P, assuming that the motor load factor obtained in the immediately preceding step 100 is RMP0, the motor load factor change amount ΔRMP obtained in step 110 is expressed as follows.

ΔRMP = RMP0−RMP In step 112, the motor load ratio R is calculated based on the motor load ratio change amount ΔRMP thus obtained.
MP is calculated. That is, RMP = RMP + ΔRMP / n is calculated. As shown in FIG. 4B, the motor load factor RMP obtained in this manner is determined in step 10 as shown in FIG.
This is a motor load factor having a dull change with respect to the motor load factor RMP0 obtained at 0, that is, a smoothed motor load factor. By calculating the torque command value Tc in step 102 using the smoothing motor load factor RMP, the same effect as in the second embodiment shown in FIG. 3 can be obtained.

It should be noted that the smoothing constant n in the second and third embodiments may be set to different values depending on whether the accelerator opening increases or decreases. Further, the smoothing constant n may be set to a different value between a region where the accelerator opening is low and a region where the accelerator opening is high.

[0028]

As described above, according to the present invention,
In the region where the accelerator opening is low, the amount of change in the torque command value with respect to the change in the accelerator opening is small, and in the region where the accelerator opening is medium, the torque command value is calculated so as to be large. In this case, effects such as prevention of hunting and improvement of the feeling of acceleration in a region where the accelerator opening is medium are obtained.

According to claims 2 and 3 of the present invention,
Since the torque command value corresponding to the accelerator opening is set, the transient motor torque fluctuation is mitigated, and the transient torque shock due to mechanical backlash or the like is reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a flow of an operation of a controller in an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing two types of contents of a map mounted on a controller in this embodiment.

3A and 3B are diagrams showing the operation of the controller of the apparatus according to the second embodiment of the present invention, wherein FIG. 3A is a flowchart showing the flow of the operation, and FIG. FIG.

4A and 4B are diagrams showing the operation of the controller of the apparatus according to the third embodiment of the present invention, FIG. 4A is a flowchart showing the flow of the operation of the controller, and FIG. FIG.

FIG. 5 is a block diagram illustrating a schematic configuration of an electric vehicle.

FIG. 6 is a diagram showing a relationship between an accelerator opening and a torque command value in the related art.

[Explanation of symbols]

14 controllers, 16 motors, RMP, RMP0
Motor load factor, Tc, Tc0 Torque command value, n smoothing constant.

Claims (3)

[Claims] 1. A motor comprising: a torque command value calculating means for calculating a torque command value according to an accelerator opening; and a control means for controlling power supplied to a motor of an electric vehicle based on the calculated torque command value. In the torque control device that controls the torque of the accelerator to a torque command value, the torque command value calculating means is configured such that the amount of change in the torque command value with respect to the change in the accelerator opening is small in a region where the accelerator opening is low, and the accelerator opening is moderate. A torque control device that calculates a torque command value such that a change amount of a torque command value with respect to a change in an accelerator opening increases in a region. 2. The torque control device according to claim 1, wherein the torque command value calculating means calculates the smoothing torque command value so as to gradually approach the torque command value calculated based on the accelerator opening with time. A torque control device, wherein a smoothing torque command value is given to a control means as a torque command value. 3. The torque control device according to claim 2, wherein the torque command value calculating means changes the torque of the motor so that the torque of the motor changes more slowly than the change of the torque command value calculated based on the accelerator opening. A smoothing torque command value corresponding to a value obtained by adding a part of the change amount of the torque command value to the command value to the previous torque command value according to the smoothing constant is calculated, and this smoothing torque command value is calculated as the torque command value. A torque control device, wherein the torque control device is provided to a control unit.