JP5454448B2 - Electric vehicle torque control device - Google Patents

Description

  The present invention relates to a torque control device for an electric vehicle that suppresses vehicle body vibration that occurs when a shift position is switched.

  In recent years, an electric vehicle in which an electric motor is mounted as a travel drive source instead of an internal combustion engine has begun to spread rapidly. Such an electric vehicle obtains a driving force of the vehicle by driving an electric motor with electric power supplied from a driving power source such as a fuel cell or a battery. In this electric vehicle, the output torque value output by the electric motor is calculated based on the running state of the vehicle, the current corresponding to the output torque value is supplied to the electric motor, and the driver's request is met. Appropriate driving is realized.

  However, an electric motor mounted on an electric vehicle has a very high response compared to an internal combustion engine, and may respond excessively to an accelerator operation or a brake operation by a driver. As a result, when the electric motor responds excessively to requests for a sudden torque change during vehicle start, stop, and acceleration / deceleration, vehicle body vibration is generated due to the reaction of the rotation.

  In particular, during forward or reverse travel, the shift position is switched from the drive (D) range to the reverse (R) range, or from the reverse (R) range to the drive (D) range, and traveling in the reverse direction is required. In this case, since a more rapid torque change is required, vehicle body vibration becomes significant.

  Therefore, conventionally, a torque control device has been provided that suppresses vehicle body vibration that occurs in the vehicle when the shift position is switched between the D range and the R range. Such a torque control device for an electric vehicle is disclosed in Patent Document 1, for example.

Japanese Patent No. 3259735

  Here, in the conventional torque control device, after the shift position is changed, the output torque value is set to zero until the running speed becomes equal to or lower than the predetermined running speed, and the torque change in the reverse direction is prohibited. . However, in such a torque control method, the longer the vehicle travels at a higher speed than the predetermined traveling speed, the longer the period in which the output torque value becomes zero (the period until the output torque is output) after the shift position is switched. Therefore, the vehicle is difficult to decelerate, and the time from when the shift position is switched to when the vehicle travels in the reverse direction is relatively long.

  Further, in the conventional torque control device, the output torque value is limited according to the traveling speed of the vehicle. Therefore, when the driving wheel rotates on a slippery road surface, the driving wheel moves on the road surface. Although the vehicle slides and rotates at a high speed, the vehicle travels at a low speed, and a large reverse torque is applied to a large output torque value after the shift position is switched. As a result, the output torque may not be output smoothly, and a sudden torque change is required, so that vehicle body vibration becomes significant.

  Therefore, the present invention solves the above problem, and when switching the shift position between the drive range and the reverse range, while suppressing vehicle body vibration, shortening the time to travel in the reverse direction, And it aims at providing the torque control apparatus of the electric vehicle which can output output torque smoothly.

An electric vehicle torque control device according to a first aspect of the present invention for solving the above-described problems is provided.
In an electric vehicle torque control device that controls an output torque value output by a motor that is a driving source of a vehicle,
Shift position detecting means for detecting a shift position of a shift lever capable of switching the operating state of the motor;
A drive wheel that is driven to rotate by driving the motor;
Drive wheel rotation speed detection means for detecting the drive wheel rotation speed of the drive wheel;
When switching between the drive range and the reverse range at the shift position is detected by the shift position detecting means, the driving wheel rotational speed at the time of the shift position switching is equal to or higher than a preset boundary driving wheel rotational speed. Includes a torque limiting means for constantly limiting the output torque value to a limit torque value larger than zero ,
The torque limiting means is
When the driving wheel rotation speed at the time of shift position switching is less than the preset boundary driving wheel rotation speed, the output torque value is gradually increased from the limit torque value as the driving wheel rotation speed decreases. It is characterized by restricting to.

An electric vehicle torque control device according to a second aspect of the present invention for solving the above-described problem is provided.
Motor rotation speed detection means for detecting the motor rotation speed of the motor;
The torque limiting means is
When switching between the drive range and the reverse range at the shift position is detected by the shift position detection means,
When the motor rotation speed at the time of shift position switching is equal to or higher than a preset boundary motor rotation speed, the output torque value is constantly limited to a limit torque value larger than zero ,
When the motor rotation speed at the time of shift position switching is less than the preset boundary motor rotation speed, the output torque value is gradually increased from the limit torque value as the motor rotation speed decreases. It is characterized by limiting to .

  Therefore, according to the torque control device for an electric vehicle according to the present invention, when the shift position of the shift lever is switched between the drive range and the reverse range, the output torque value output by the motor is limited by the torque limiting means. Thus, it is possible to suppress the vehicle body vibration, shorten the time until the vehicle travels in the reverse direction, and output the output torque smoothly.

1 is a schematic configuration diagram of a torque control device for an electric vehicle according to an embodiment of the present invention. It is a characteristic view which shows the change state of the torque value at the time of the shift position switching between a drive range and a reverse range.

  Hereinafter, a torque control device for an electric vehicle according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, an electric vehicle (vehicle) 1 is equipped with a motor (AC motor) 11 as a travel drive source. The output shaft 11 a of the motor 11 is connected to a transaxle 12 in which a reduction gear and a differential gear are integrated. A pair of left and right drive shafts 13 are connected to the transaxle 12. A drive wheel 14 is attached to each drive shaft 13.

  In addition, an inverter unit 15 is connected to the motor 11, and a battery 16 as a driving power source is connected to the inverter unit 15. The inverter unit 15 converts the direct current from the battery 16 into an alternating current and supplies it to the motor 11 to control the output torque of the motor 11. Thereby, the electric vehicle 1 can be run by driving the motor 11 with the current supplied from the battery 16 and rotating the drive wheels 14.

  Further, a motor control unit 17 as an electronic control device is connected to the inverter unit 15. The motor control unit 17 sets an output torque value of the motor 11 and sends an instruction torque signal corresponding to the output torque value (a signal corresponding to an instruction torque value Tb described later) to the inverter unit 15. It is designed to output. Thus, by controlling the inverter unit 15 according to the command torque signal output from the motor control unit 17, the output torque value of the motor 11 is changed to the torque value (command torque value Tb) corresponding to the command torque signal. can do.

  The motor control unit 17 includes a target torque calculator (torque calculator) 17a and a target torque limiter (torque limiter) 17b. Details of the target torque calculator 17a and the target torque limiter 17b are as follows. Will be described later.

  Further, the electric vehicle 1 is provided with a shift lever 21 for switching the operation state (rotation state) of the motor 11. As the shift position (shift range) of the shift lever 21, each position of a P (parking: parking) range, an R (reverse: reverse) range, an N (neutral: neutral) range, and a D (drive: forward) range. Is set.

  Further, the electric vehicle 1 includes a shift position sensor (shift position detecting means) 31, an accelerator sensor (vehicle running state detecting means) 32, a brake sensor (vehicle running state detecting means) 33, a motor rotation speed sensor (motor rotation speed detection). Means) 34 and a driving wheel rotational speed sensor (driving wheel rotational speed detecting means) 35 are provided, and each sensor 31, 32, 33, 34, 35 is connected to the motor control unit 17.

  The shift position sensor 31 detects a shift position currently selected by the shift lever 21, and the detected shift position of any one of the P range, R range, N range, and D range is calculated as a target torque. It outputs to the part 17a and the target torque limitation part 17b.

  The accelerator sensor 32 detects an accelerator operation amount (depression amount) A of an accelerator pedal (not shown), and outputs the detected accelerator operation amount A to the target torque calculator 17a. The brake sensor 33 detects a brake operation amount (depression amount) B of a brake pedal (not shown), and outputs the detected brake operation amount B to the target torque calculation unit 17a. Yes. The accelerator operation amount A and the brake operation amount B are parameters indicating the traveling state of the electric vehicle 1.

  The motor rotation speed sensor 34 detects the motor rotation speed Nm of the output shaft 11a of the motor 11, and outputs the detected motor rotation speed Nm to the target torque limiter 17b. The drive wheel rotation speed sensor 35 detects the drive wheel rotation speed Nh of the drive wheel 14 (drive shaft 13), and outputs the detected drive wheel rotation speed Nh to the target torque limiting unit 17b. It has become.

  The target torque calculator 17a calculates the target torque value Ta based on the input shift position, accelerator operation amount A, and brake operation amount B, and then calculates the calculated target torque value Ta to the target torque. The data is output to the limiting unit 17b.

  The calculation process of the target torque calculation unit 17a will be specifically described. First, when a shift position of the P range or the N range is input, the calculation is performed with the target torque value Ta set to zero.

  When the shift position of the D range or the R range is input, the target torque value Ta is calculated based on the accelerator operation amount A and the brake operation amount B.

  Next, the target torque limiter 17b calculates the command torque value Tb based on the input target torque value Ta, shift position, motor rotation speed Nm, and drive wheel rotation speed Nh, and then calculates the calculated command torque. The value Tb is output to the inverter unit 17. That is, the target torque value Ta is limited based on the shift position and motor rotation speed Nm, or the shift position and drive wheel rotation speed Nh, or the shift position and motor rotation speed Nm and the shift position and drive wheel rotation speed Nh. It is supposed to be.

  The calculation (limitation) processing of the target torque limiting unit 17b will be specifically described. First, when the shift position of the P range or the N range is continuously input, the target torque that is zero is input. The value Ta is directly calculated as the indicated torque value Tb.

  When the shift position of the D range or the R range is continuously input, the target torque value Ta calculated according to the accelerator operation amount A and the brake operation amount is calculated as the instruction torque value Tb as it is. .

  Further, when the shift position of the R range switched from the D range is input, the absolute value of the target torque value Ta at the time of the shift position switching (a time point immediately before switching to the R range) is set as the motor rotational speed Nm and When the drive wheel rotational speed Nh is equal to or higher than the preset boundary motor rotational speed Nmo and the boundary drive wheel rotational speed Nho, the torque is limited to a torque value (limit torque value) To larger than zero.

  On the other hand, when the motor rotational speed Nm and the drive wheel rotational speed Nh are less than the preset boundary motor rotational speed Nmo and the boundary drive wheel rotational speed Nho, the absolute value of the target torque value Ta is determined. You may restrict | limit so that it may increase gradually from the limiting torque value To as wheel rotational speed Nh becomes small (refer FIG. 2).

  That is, the absolute value of the target torque value Ta is such that the motor rotation speed Nm and the drive wheel rotation speed Nh are the boundary motor rotation speed Nmo and the boundary drive wheel rotation speed from the time when the shift position is switched from the D range to the R range. The limit value is constant up to the point of Nho. Then, the target torque value Ta limited according to the motor rotation speed Nm and the drive wheel rotation speed Nh is calculated as the instruction torque value Tb.

  Furthermore, when the shift position of the D range switched from the R range is input, the absolute value of the target torque value Ta at the time of the shift position switching (the time immediately before switching to the D range) is calculated as the motor rotation speed Nm. When the drive wheel rotation speed Nh is equal to or higher than the preset boundary motor rotation speed Nmo and the boundary drive wheel rotation speed Nho, the torque is limited to a limit torque value To that is greater than zero.

  On the other hand, when the motor rotational speed Nm and the drive wheel rotational speed Nh are less than the preset boundary motor rotational speed Nmo and the boundary drive wheel rotational speed Nho, the absolute value of the target torque value Ta is determined. You may restrict | limit so that it may increase gradually from the limiting torque value To as wheel rotational speed Nh becomes small (refer FIG. 2).

  That is, the absolute value of the target torque value Ta is such that the motor rotational speed Nm and the driving wheel rotational speed Nh are the boundary motor rotational speed Nmo and the boundary driving wheel rotational speed from the time when the shift position is switched from the R range to the D range. The limit value is constant up to the point of Nho. Then, the target torque value Ta limited according to the motor rotation speed Nm and the drive wheel rotation speed Nh is calculated as the instruction torque value Tb.

  In the above-described embodiment, when the target torque value Ta is limited to the command torque value Tb, both the motor rotation speed Nm of the motor 11 and the drive wheel rotation speed Nh of the drive wheel 14 are used. Any one of these may be used.

  Therefore, according to the torque control device of the present invention, when the shift position of the shift lever 21 is switched between the D range and the R range, the absolute value of the target torque value Ta at the time of switching the shift position is determined by the motor rotation. When the speed Nm and the drive wheel rotation speed Nh are equal to or higher than the boundary motor rotation speed Nmo and the boundary drive wheel rotation speed Nho that are set in advance, the limit torque value To is limited to the instruction torque value. Calculation is made as Tb.

  Thereby, since the sudden change of the target torque value Ta can be suppressed at the time of the shift position switching, the vehicle body vibration generated in the electric vehicle 1 can be suppressed.

  Also, in the high rotation region of the motor 11 and the drive wheel 14 with the boundary motor rotation speed Nmo and the boundary drive wheel rotation speed Nho as the boundary, by setting a limit torque value To that is zero or greater, immediately after switching the shift position Since the reverse rotation torque can be immediately applied, the time until the electric vehicle 1 travels in the reverse direction can be shortened.

  Further, when the target torque value Ta is limited to the command torque value Tb, the driving wheel 14 slips on the road surface by using the motor rotation speed Nm of the motor 11 and the driving wheel rotation speed Nh of the driving wheel 14. When the electric vehicle 1 is rotating at a high speed and the electric vehicle 1 is traveling at a low speed, even if the shift position is switched between the D range and the R range, a small limit torque value To is obtained for a large output torque value. Since reverse torque can be applied, the torque of the motor 11 can be output smoothly.

  Note that when the torque limit value To is an output torque value equivalent to engine braking in a vehicle running on an internal combustion engine, no significant vehicle body vibration is generated, so that the driver does not feel uncomfortable.

  The present invention can be applied to an electric vehicle in which drivability is improved.

DESCRIPTION OF SYMBOLS 1 Electric vehicle 11 Motor 11a Output shaft 12 Transaxle 13 Drive shaft 14 Drive wheel 15 Inverter unit 16 Battery 17 Motor control unit 17a Target torque calculator 17b Target torque limiter 21 Shift lever 31 Shift position sensor 32 Accelerator sensor 33 Brake sensor 34 Motor rotation speed sensor 35 Drive wheel rotation speed sensor Ta Target torque value Tb Instruction torque value To Limit torque value A Accelerator operation amount B Brake operation amount Nm Motor rotation speed Nh Drive wheel rotation speed Nmo Boundary motor rotation speed Nho Boundary drive wheel rotation speed

Claims (2)

In an electric vehicle torque control device that controls an output torque value output by a motor that is a driving source of a vehicle,
Shift position detecting means for detecting a shift position of a shift lever capable of switching the operating state of the motor;
A drive wheel that is driven to rotate by driving the motor;
Drive wheel rotation speed detection means for detecting the drive wheel rotation speed of the drive wheel;
When switching between the drive range and the reverse range at the shift position is detected by the shift position detecting means, the driving wheel rotational speed at the time of the shift position switching is equal to or higher than a preset boundary driving wheel rotational speed. Includes a torque limiting means for constantly limiting the output torque value to a limit torque value larger than zero ,
The torque limiting means is
When the driving wheel rotation speed at the time of shift position switching is less than the preset boundary driving wheel rotation speed, the output torque value is gradually increased from the limit torque value as the driving wheel rotation speed decreases. A torque control device for an electric vehicle, characterized by being limited to In the electric vehicle torque control device according to claim 1,
Motor rotation speed detection means for detecting the motor rotation speed of the motor;
The torque limiting means is
When switching between the drive range and the reverse range at the shift position is detected by the shift position detection means,
When the motor rotation speed at the time of shift position switching is equal to or higher than a preset boundary motor rotation speed, the output torque value is constantly limited to a limit torque value larger than zero ,
When the motor rotation speed at the time of shift position switching is less than the preset boundary motor rotation speed, the output torque value is gradually increased from the limit torque value as the motor rotation speed decreases. A torque control device for an electric vehicle characterized by being limited to

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