JPH118912A - Motor torque controller for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moor torque controller which improves the operability of low traveling speed and starting a car on a grade without feeling being out of place. SOLUTION: A motor torque controller 1 is provided with a detecting part 2, a controlling part 3 and an outputting part 4. The detecting part 2 is provided with a road inclination detecting means 5, an accelerator operation detecting means 6 and a brake operation detecting means 7. the controller part 3 consists of a memory means 15, a judging means 16, a calculating means 17 and an indicating means 18. The memory means 15 is provided with first to fifth memory parts 19-23. The judging part 16 is provided with a first judging part 26 and a second judging part 27. The calculating means 17 is provided with first to fifth calculating parts 28-32. First or the fifth calculating part 28 or 32 calculates creep torque. The indicating means 18 adds inertia and regenerative torque to the creep torque. The motor torque controller 1 makes a motor 12 generate creep torque which corresponds to road inclination Kr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor torque control device for an electric vehicle, which generates a torque corresponding to the creep torque of a vehicle equipped with an automatic transmission.

[0002]

2. Description of the Related Art In an electric vehicle, when the motor torque is controlled so that the motor torque becomes zero when the operation amount of the accelerator is zero, a creep torque like a vehicle equipped with an automatic transmission (hereinafter referred to as an automatic vehicle) is generated. do not do. For this reason, a driver who is used to driving an automatic vehicle is obliged to operate the vehicle.

[0003] Therefore, conventionally, a motor torque control device that generates torque to a motor when both an accelerator pedal and a brake pedal are not operated has been used. This motor torque control device generates a torque equivalent to the creep torque of an automatic vehicle by generating a constant torque in the motor.

Further, as disclosed in Japanese Patent Application Laid-Open No. 6-216418, when a vehicle speed is equal to or lower than a predetermined value and a brake pedal is operated, a motor generates a creep torque corresponding to a road gradient. Torque control devices are also known.

[0005]

If the above-described motor torque control device for generating a creep torque of a constant value is used, the vehicle is difficult to move forward and may move backward unless an accelerator pedal or the like is operated during climbing a hill. Was.

When the control device disclosed in Japanese Patent Application Laid-Open No. 6-216418 is used, creep torque is generated when the brake pedal is operated when stopping on a flat road. For this reason, it may be difficult to stop at a desired position, and the driver may feel uncomfortable, such as increasing the amount of brake operation to stop at the desired position.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor torque control device for an electric vehicle which does not give a driver an uncomfortable feeling and improves operability at low speed running and starting on a slope.

[0008]

According to a first aspect of the present invention, there is provided a motor torque control device for an electric vehicle, wherein the creep is increased when the road gradient detected by the road gradient detecting means is increased. Since the torque control means gradually increases the creep torque of the motor, the vehicle can be started smoothly while restraining the vehicle from moving backward without performing a brake operation when starting on a slope.

When the brake operation detecting means detects the brake operation, the creep torque control means does not generate a creep torque, so that the vehicle can be stopped at a desired position on a flat road without increasing the brake operation amount.

[0010] Preferably, the vehicle may be further restrained from retreating by providing a reverse-preventing means for further increasing the creep torque when the vehicle retreats, for example, when starting up an uphill road.

According to a second aspect of the present invention, there is provided a motor torque control apparatus for an electric vehicle, wherein the creep torque generated by the above-described creep torque control means includes a power running torque corresponding to an accelerator operation amount, and a motor generated at the time of deceleration. Add the regenerative torque. For this reason, torque according to the driver's operation can be generated smoothly, and operability can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a motor torque control device 1 for an electric vehicle includes a detection unit 2
, A control unit 3, an output unit 4, and the like.

The detecting section 2 comprises a road gradient detecting means 5, an accelerator operation detecting means 6, a brake operation detecting means 7, a vehicle speed detecting means 8, a motor speed detecting means 9, and the like. The accelerator operation detecting means 6 detects an on / off operation and an operation amount of an accelerator pedal, and outputs an accelerator pedal operation signal Ac to the control unit 3. The brake operation detecting means 7 detects the ON / OFF operation and the operation amount of the brake pedal, and outputs a brake pedal operation signal Br to the control unit 3.

The vehicle speed detecting means 8 is obtained by a known speed sensor or the like capable of detecting the rotation of the wheels 14 and the like.
The vehicle speed of the electric vehicle is detected, and a vehicle speed signal V is output to the control unit 3.

The motor rotation speed detecting means 9 is connected to the output unit 4.
And outputs the motor rotation speed signal Mt to the control unit 3 by detecting the rotation speed of the motor 12.

If the electric vehicle is provided with a transmission, if necessary, a shift position detecting means 10 for detecting a shift position of the transmission and outputting a shift position signal St to the control unit 3 is provided. It is desirable.

The road gradient detecting means 5 calculates, among the forces acting on the vehicle traveling on the road, a force directed along the road and toward the rear of the vehicle, that is, a so-called gradient resistance Kr. It has the function of outputting to the user. The gradient resistance Kr calculated by the road gradient detecting means 5
Is a combination of a force generated by gravitational acceleration and a force due to friction from a road surface or the like on an uphill having a gradient. The gradient resistance Kr indicates the road gradient described in this specification.

The road gradient detecting means 5 includes a tire driving force F obtained from the torque output from the motor 12 and the like.
The gradient resistance Kr is calculated using Expression 1 derived from the fact that the sum of the acceleration resistance Ra acting on the vehicle during traveling and the traveling resistance is substantially equal.

W × sin θ = F−Ra−W × μr−μc × S × V ² −Rc Equation 1 where W × sin θ: gradient resistance W: gross vehicle weight θ: gradient F: tire driving force or Tire braking force Ra: acceleration resistance μr: rolling resistance coefficient μc: air resistance coefficient S: vehicle front projected area V: vehicle speed Rc: turning resistance Note that the road gradient detecting means 5 is used before traveling such as the total vehicle weight W. A clear numerical value is stored, and a numerical value such as a vehicle speed V that needs to be detected during traveling is supplied from the vehicle speed detecting means 8 or the like. As described above, the road gradient detecting means 5 calculates the road gradient based on the balance of the force related to the traveling of the vehicle, and estimates the road gradient.

The output section 4 comprises a power conversion circuit 11. The power conversion circuit 11 includes a motor 12
And the battery 13 are connected. Power conversion circuit 11
Is an inverter or the like, and controls the powering torque of the motor 12 by changing the frequency and the like of the voltage supplied from the battery 13 and applied to the motor 12 in accordance with a later-described final command torque TT output from the control unit 3. It has the function to do. The power conversion circuit 11 has a function of controlling a regenerative torque for accumulating electric power generated by forcibly rotating the motor 12 in the battery 13.

The motor 12 has a wheel 14 as an output shaft.
And the motor rotation speed detecting means 9 and the like are connected. The motor 12 generates a powering torque for driving the wheels 14 by applying a voltage supplied from the battery 13 through the power conversion circuit 11, and also generates electric power by being forcibly rotated by the wheels 14. I do.

The control section 3 comprises storage means 15, determination means 16, calculation means 17, and instruction means 18. The control unit 3 calculates a final command torque TT based on the signals Kr, Ac, Br, V, St, and Mt output from the detection unit 2 and outputs the calculated torque to the power conversion circuit 11. I have.

The storage means 15 includes a first storage unit 19, a second storage unit 20, a third storage unit 21, and a fourth storage unit 2.
2 and a fifth storage unit 23. First storage unit 1
3, a first command creep 9 is a first command creep proportional to the calculated gradient resistance Kr output from the road gradient detecting means 5 with the first predetermined torque T1 obtained from the maximum torque of the motor 12 as an upper limit as shown in FIG. First to calculate torque KT1
Is stored.

As shown in FIG. 4, the second storage section 20 stores a vehicle speed signal V (vehicle speed) output by the vehicle speed detecting means 8.
The second map 25 in which the gain becomes smaller as the time becomes faster is stored.

The second map 25 shows that the gain is inversely proportional to the vehicle speed signal V when the vehicle speed signal V (vehicle speed) is faster than the target vehicle speed VL calculated by a third calculating section 30 of the calculating means 17 described later. Let's make it gradually smaller. When the vehicle speed signal V exceeds the sum of the target vehicle speed VL and the first predetermined vehicle speed N, the gain becomes zero.

The first predetermined vehicle speed N is, for example, 5 km / h
It is desirable to use a relatively low speed, such as. Note that the sum of the target vehicle speed VL and the first predetermined vehicle speed N indicates a constant vehicle speed described in this specification.

The second map 25 is designed to maintain the first predetermined gain G1 when the vehicle speed signal V (vehicle speed) is earlier than 0 and lower than the target vehicle speed VL. When the vehicle speed signal V is negative, that is, when the vehicle is moving backward, the second predetermined gain G2 is set as an upper limit and the first predetermined gain G1 is set as the vehicle speed decreases, that is, as the reverse vehicle speed increases. And the gain is increased proportionally.

The third storage unit 21 stores a third map for calculating a target vehicle speed VL during creep running from the vehicle speed signal V. The third storage unit 21 may include a congestion determining unit that determines whether or not there is a congestion. If this traffic congestion determination means is provided and it is determined that there is no traffic congestion, it is desirable to set the target vehicle speed VL to an extremely low speed, for example, 2 km / h. On the other hand, if it is determined that there is traffic, the target vehicle speed VL is
It is desirable to set the second predetermined vehicle speed as an upper limit and to make the speed proportional to the average vehicle speed within a relatively short predetermined time such as, for example, 30 seconds.

The congestion determining means calculates a running time ratio, which is a ratio of the average vehicle speed within a relatively long predetermined time, such as three minutes, to the predetermined time and the actual running time within the predetermined time. Then, it is determined whether or not there is a traffic jam.

The fourth storage unit 22 has a third predetermined gain as an upper limit and is proportional to the elapsed time from when the accelerator operation detecting means 6 and the brake operation detecting means 7 stop detecting the accelerator operation and the brake operation. A fourth map for calculating the obtained gain is stored. In the fourth map, the gain is 0 when one or both of the accelerator operation and the brake operation are detected.

The first predetermined time during which the third predetermined gain is equal to the gain calculated by the fourth map is calculated in accordance with the calculated gradient resistance Kr calculated by the road gradient detecting means 5. desirable. At this time, it is desirable that the first predetermined time is shortened as the calculated gradient resistance Kr increases, that is, as the gradient of the road becomes steeper.

The fifth storage section 23 stores the judgment means 1
In a case where the motor 12 is overheated and the motor 12 is judged to be overheated by the second determination unit 27 to be described later, the accelerator operation detecting means 6 and the brake operation detecting means 7 detect the accelerator operation and the brake operation. A fifth map is stored in which the gain gradually decreases with respect to the elapsed time after the stop.

The determination means 16 includes a first determination unit 26
And a second determination unit 27. The first determination unit 26 has a function of determining whether to generate a creep torque, as shown in FIG. The first determination unit 26 does not generate creep torque when the brake pedal is operated, and generates creep torque in other cases.

The second judging section 27 has a function of judging whether or not the motor is overheated. The second determination unit 27
The motor has a function of determining a motor overheating condition when the motor 12 is in a motor locked state in which the motor 12 is easily overheated and the rotation speed is lower than a predetermined rotation speed and the torque is higher than a second predetermined torque. It is desirable that the above-mentioned predetermined number of revolutions and the second predetermined torque be set based on the performance and specifications of the motor 12.

The calculating means 17 includes a first calculating unit 28
, A second computing unit 29, a third computing unit 30, a fourth computing unit 31, and a fifth computing unit 32. The calculation means 17 can read the first map 24 to the fifth map of the storage means 15 freely, as indicated by an arrow R shown in FIGS.

As shown in FIG. 2, the first calculating section 28 uses the first map 24 of the first storage section 19 to calculate the first map 24 from the calculated slope resistance Kr output by the road slope means 5. The first command creep torque KT1 is calculated and output to the second calculator 29.

The second calculating section 29 stores the vehicle speed signal V output from the vehicle speed detecting means 8, the target vehicle speed VL calculated by the third calculating section 30, and the second map 25 of the second storage section 20. And the gain obtained by using the first arithmetic unit 2
8 is multiplied by the first command creep torque KT1 calculated, and the second command creep torque KT2 is calculated by the fourth calculation unit 3
1 is output.

The second operation unit 29 and the second operation unit 29
And the storage unit 20 constitute the retreat prevention means described in this specification. The third calculation unit 30 calculates the target vehicle speed VL from the vehicle speed signal V output by the vehicle speed detection means 8 using the third map of the third storage unit 21 and calculates the second vehicle speed VL.
Is output to the calculation unit 29.

The fourth arithmetic unit 31 calculates the gain obtained by using the fourth map of the fourth storage unit 22 with the second command creep torque K output by the second arithmetic unit 29.
The second command creep torque KT3 is output by multiplying T2.

In the fourth map, when one or both of the accelerator operation and the brake operation are detected, the gain is 0, so that one or both of the accelerator operation and the brake operation are detected. In this case, the fourth computing unit 31 does not generate creep torque. In addition, the first arithmetic unit 28,
The first storage unit 19, the fourth calculation unit 31, and the fourth storage unit 22 constitute a creep torque control unit described in this specification.

The fifth calculating section 32 calculates the gain obtained by using the fifth map in the fifth storage section 23 when the second determining section 27 determines that the motor is overheated. The third command creep torque KT3 output by the fourth calculation unit 31 is multiplied to output a fourth command creep torque KT4.

The instruction means 18 is, as shown in FIG.
The fourth command creep torque KT4 obtained through the first calculation unit 28 to the fifth calculation unit 32 or the third command creep obtained through the first calculation unit 28 to the fourth calculation unit 31 The final command torque TT is calculated by adding the regenerative torque command signal BT and the powering torque command signal AT by the accelerator pedal 33 to the torque KT3,
The final command torque TT is output to the power conversion circuit 11.

In the control section 3, as shown in FIG. 2, the command creep torques KT3 and KT4 are applied between the fifth arithmetic section 32 and the instruction means 18 by the motor 1 as shown in FIG.
It is desirable to provide a limiter section 34 which does not exceed the maximum torque of 2.

When a transmission is provided, it is desirable to provide a shift compensator 35 for correcting the creep torque according to the shift position of the transmission. In the illustrated example, it is provided between the first arithmetic unit 28 and the second arithmetic unit 29.

According to the above-described configuration, as shown in FIG. 5, first, at step S1, it is determined whether or not to generate a creep torque. In step S1, the first determination unit 26 determines whether or not the brake pedal is operated. If the brake pedal is not operated, the process proceeds to step S2 and step S3.

In step S2, the first calculating section 28 calculates the first command creep torque KT1 and executes step S2.
4 and in step S3, the third operation unit 30
Calculates the target speed VL and proceeds to step S4.

In step S4, the second operation unit 29
Calculates the second command creep torque KT2 by multiplying the first command creep torque KT1 by a gain based on the second map 25, and proceeds to step S5.

In step S5, the fourth operation unit 31
Calculates the third command creep torque KT3 by multiplying the second command creep torque KT2 calculated in step S4 by a gain based on the fourth map, and calculates the third command creep torque KT3.
Proceed to 6.

In step S6, the second determination unit 27
Is determined whether or not the motor is overheated. Second determination unit 27
If it is determined that the motor is overheated as described above, the process proceeds to step S7, and if it is determined that the motor is not overheated, the process proceeds to step S8.

In step S7, the fifth command unit 32 multiplies the third command creep torque KT3 calculated in step S5 by a gain based on the fifth map, and obtains a fourth command creep torque KT3.
Of the command creep torque KT4 of step S8
Proceed to.

In step S8, the third command creep torque KT3 calculated in step S5 or the fourth command creep torque KT4 calculated in step S7.
The command means 18 adds the regenerative torque command signal BT and the powering torque command signal AT to the final command torque TT
Is output.

The power conversion circuit 11 controls the voltage applied to the motor 12 in accordance with the final command torque TT obtained in this manner, thereby controlling the creep torque generated by the motor 12. Then, the process from step S1 is repeated.

According to the motor torque control device 1 of the above embodiment, as shown in FIG. 3, the first map 24 generates a creep torque proportional to the calculated slope resistance Kr calculated by the road slope detecting means 5. Therefore, an appropriate creep torque is generated according to the gradient of the road and the like.

Also, as shown in FIG.
However, as the vehicle speed increases, the creep torque is reduced, so that the vehicle can move forward at a substantially constant vehicle speed when climbing a hill or the like, thereby improving the operability of the driver. In addition, when the vehicle retreats,
Since the second map 25 increases the creep torque,
This means that the vehicle is prevented from moving backward.

The speed of the vehicle moving forward at this time depends on the third speed.
And the target vehicle speed VL calculated by the calculation unit 30
And the first predetermined vehicle speed N. Further, since no creep torque is generated when the brake pedal is operated, the driver does not feel uncomfortable.

Further, since the fourth calculating section 31 gradually increases the creep torque using the fourth map, the vehicle starts smoothly. The second determination unit 27 determines whether or not the motor is overheated. If the motor is overheated, the creep torque is gradually reduced. Motor 12
And so on.

Further, since the road gradient detecting means 5 calculates a value obtained by adding the force due to the gravitational acceleration and the force due to the friction of the road surface, the creep corresponding to the inclination angle of the vehicle detected using a gyro or the like. It is possible to generate a more appropriate creep torque as compared with a case where a torque is generated.

Next, the results of a hill start experiment performed to confirm the operation of the control unit 3 of the above embodiment will be described with reference to FIGS. In this experiment, an electric vehicle provided with a motor torque control device that generates a constant creep torque on several types of uphills having different slopes (hereinafter referred to as a comparative example), and an electric vehicle provided with the motor torque control device 1 described above. (Hereinafter referred to as the present invention) was placed with a brake applied, then the brake was released, and the retreat distance and vehicle speed at this time were measured.

In the comparative example, the elapsed time from when the brake was released was set to about 0.4 to 0.5 seconds.
The elapsed time from the release of the brake is about 10 seconds. The vehicle speed shown in FIG. 7 indicates the speed immediately after the brake is released.

First, as shown in FIG. 6, in the relationship between the uphill slope and the retreat distance, the retreat distance of the present invention is approximately 1/2 of the retreat distance of the comparative example. In the comparative example, since the vehicle moves backward as shown in the drawing in about 0.4 to 0.5 seconds, it is clear that the vehicle continues to move backward unless the brake pedal is operated. On the other hand, since the present invention retracts only about half the distance of the comparative example even after 10 seconds, it has been clarified that the present invention hardly retracts.

Further, as shown in FIG. 7, in the relationship between the uphill gradient and the vehicle speed, the present invention climbs uphill with the forward vehicle speed on any uphill with any gradient. On the other hand, the comparative example does not have the forward vehicle speed at any gradient, and retreats on an uphill slope of about 16% or more.

It should be noted that comparing FIG. 6 and FIG. 7, the present invention has a forward vehicle speed despite having a reverse distance when the uphill gradient is about 16% or more. This is because the vehicle has retreated due to the gradient from immediately after the brake was released until the creep torque was generated. In other words, the rise of the creep torque is intended to cause the vehicle to transmit smoothly. Therefore, the rise of the creep torque is gradually performed, and the vehicle moves backward while the torque during this period is smaller than that at which the vehicle is transmitted. When the torque further increases, the vehicle moves forward.

[0063]

According to the first aspect of the present invention, the backward movement of the vehicle can be suppressed as much as possible without performing the brake operation when starting on a slope, so that the operability when starting on a slope can be improved. In addition, on a flat road or the like, the driver can stop at a desired position without increasing the brake operation amount, so that the driver does not feel uncomfortable.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the power running torque by the accelerator operation and the regenerative torque generated by the motor are added to the creep torque generated by the creep torque control means. This improves the operability of the driver.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a motor torque control device for an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a control unit of the motor torque control device of the embodiment shown in FIG.

FIG. 3 is a view showing a first map of the motor torque control device shown in FIG. 2;

FIG. 4 is a view showing a second map of the motor torque control device shown in FIG. 2;

FIG. 5 is a flowchart showing a procedure of a process of the motor torque control device shown in FIG. 2;

FIG. 6 is a diagram showing a relationship between an ascending slope and a retreat distance obtained in a slope start experiment for the product of the present invention and a comparative example.

FIG. 7 is a diagram showing the relationship between the vehicle speed and the ascending slope obtained in a slope start experiment for the product of the present invention and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Motor torque control device 5 ... Road gradient detection means 6 ... Accelerator operation detection means 7 ... Brake operation detection means 12 ... Motor 19 ... 1st storage part (creep torque control means) 22 ... 4th storage part (creep torque) Control means) 28 first calculation unit (creep torque control means) 31 fourth calculation unit (creep torque control means) V ... vehicle speed signal (vehicle speed) Kr ... calculation slope resistance (road slope)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tomiji Owada 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (2)

[Claims] An electric vehicle comprising: vehicle speed detecting means for detecting a vehicle speed; road gradient detecting means for detecting a road gradient; accelerator operation detecting means for detecting an accelerator operation; and brake operation detecting means for detecting a brake operation. In the motor torque control device of an automobile, when the vehicle speed detecting means detects a vehicle speed equal to or less than a predetermined value, and the accelerator operation detecting means and the brake operation detecting means do not detect an accelerator operation and a brake operation,
A motor torque control device for an electric vehicle, comprising: a creep torque control unit that generates a creep torque corresponding to a road gradient to a motor based on an output signal of the road gradient detection unit. 2. When the accelerator operation detecting means detects an accelerator operation, a powering torque corresponding to an accelerator operation amount and a regenerative torque generated by the motor during deceleration are added to the creep torque generated by the motor. 2. The motor torque control device for an electric vehicle according to claim 1, wherein: