JP3156357B2 - Electric vehicle braking control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for an electric vehicle, and more particularly to a braking control at the time of shifting.

[0002]

2. Description of the Related Art An electric vehicle is a vehicle driven by a motor, and its braking means includes mechanical braking by hydraulic pressure or the like and regenerative braking by regeneration of a driving motor. FIG.
1 shows a configuration of an electric vehicle capable of mechanical braking and regenerative braking. This electric vehicle is disclosed in JP-A-1-198.
No. 201 is described.

The electric vehicle shown in FIG. 1 is equipped with an AC motor 10 as a drive source. The driving power of the AC motor 10 is supplied from the battery 12 via the power converter 14. The power converter 14 converts the output of the battery 12 into, for example, three-phase AC power, and supplies the obtained power to the motor 10. The shaft output of the motor 10 is transmitted to the wheels 16 via a mechanism (not shown), so that the electric vehicle runs.

[0004] The power converter 14 is configured as an inverter circuit or the like. Therefore, it is possible to control the output torque of the motor 10 by controlling the operation of the power converter 14. For this control, a control unit 18 is provided.

The control section 18 comprises an output torque calculation section 20 and a motor control section 22. The output torque calculation unit 20 detects the number of rotations of the motor 10 by a pulse generator 24 laid on the motor 10 and further calculates a torque command value according to an accelerator amount, a brake amount, and the like.
The motor control unit 22 controls the power converter 14 based on the calculated torque command value. Thereby, the output torque of the motor 10 is controlled to the torque command value.

On the other hand, this conventional example is used as a mechanical braking means.
It has a so-called hydraulic brake mechanism. This mechanism is
When the brake pedal 26 is depressed, the master cylinder 3
At 0, a hydraulic pressure is generated, and the hydraulic pressure is supplied to a wheel cylinder provided on the wheel 16. Thereby, the wheels 16 are mechanically braked.

The amount of depression of the brake pedal 26 (brake amount) is detected by a brake amount detecting section 28 and inputted to the control section 18. In this case, the control unit 18 generates a torque command value in a regeneration region to regenerate energy from the motor 10. Therefore, in this conventional example, it is possible to use both mechanical braking and regenerative braking at the time of braking.

When a transmission is mounted on an electric vehicle, how to reduce the shock caused by the difference between the rotation speed of the motor and the rotation speed of the output shaft of the transmission during shifting becomes a problem. For example, Japanese Patent Laying-Open No. 50-100714 discloses a device for reducing this shock by controlling the motor speed.

FIG. 6 shows a main configuration of an apparatus according to this publication. As shown in the figure, a comparison circuit 32 for comparing the field current of the driving motor with a set value is provided, and an exclusive OR of an output of the comparison circuit 32 and a signal obtained by delaying the output by the delay circuit 34 is calculated. It is determined by EOR36. The output of EOR 36 is used to open and close the gate by transistor 38, and the output of transistor 38 is used to excite relay 40. The relay 40 is a relay that switches the value of a resistor inserted into an armature of a driving motor (not shown). That is, when the relay 40 is on, the armature insertion resistance is a parallel value of the resistors 42 and 44, and when the relay 40 is off, only the resistor 44 is provided. Therefore, by using such a circuit, the rotation speed of the motor can be controlled.

[0010]

Therefore, it is conceivable to control the motor speed by reducing the motor torque during gear shifting in order to reduce shift shock in an electric vehicle that performs mechanical braking and regenerative braking. In particular, when an automatic transmission is used, in this control, it is conceivable that only mechanical braking is performed without performing regenerative braking even if a braking operation is performed during gear shifting. This prevents the occurrence of a shock due to motor torque fluctuation during gear shifting.

However, in this case, if the braking operation (depressing the brake pedal) is continued even after the shift is completed, a shock may occur immediately after the shift is completed. As shown in FIG. 7, when the depression of the brake pedal is started during the shift period and the brake pedal is depressed even after the shift period ends, the above control does not generate the regenerative braking torque during the shift period. , The regenerative braking torque is generated immediately after the shift is completed. Since the generation of such a torque appears as a stepwise change in the deceleration G, it is not preferable in terms of brake feeling.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a configuration in which a motor torque is reduced at the time of shifting, a braking operation is started during a shifting period, and after a shifting is completed. It is an object of the present invention to realize a braking control device that does not cause the brake feeling to deteriorate even when the braking control is continued.

[0013]

In order to achieve the above object, the present invention relates to a means for generating only a mechanical braking force when a braking operation is started in a state where a transmission is performing a shift operation. Means for gradually generating a regenerative braking force when the braking operation is continued at the time when the shifting operation of the transmission is completed.

[0014]

According to the present invention, when a braking operation is started during a gear shift period, the braking force is only the mechanical braking force, the rotational speed of the drive motor is controlled, and shift shock is reduced. Further, when the braking operation started during the shift period is continued at the end of the shift, control is performed such that the regenerative braking force is gradually generated. As a result, sudden deceleration does not occur at the end of the shift, and the brake feeling is improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The same components as those of the conventional example shown in FIGS. 5 to 7 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows the configuration of an electric vehicle according to one embodiment of the present invention. As shown in this figure,
An automatic transmission (A / T) 46 between the motor 10 and the wheels 16
Is arranged. The A / T 46 is a three-speed A / T without a torque converter. Reference numeral 48 denotes a differential gear (differential).

In this embodiment, an EV controller 50, an inverter controller 52, and an ECT
54 are provided. The EV controller 50 calculates a torque command value based on an accelerator pedal depression amount (accelerator amount), a brake amount, and the like, and provides the calculation result to the inverter controller 52 as a torque command. The inverter controller 52 issues a current command according to the command value, and controls the output torque of the motor 10 by controlling the power converter 14.

The EV controller 50 starts control at the time of braking in response to turning on of a brake switch. The brake switch is a switch that is turned on when a brake pedal is depressed. When the brake pedal is depressed, a mechanical braking force acts on the wheels 16 by the same hydraulic brake mechanism as in the first conventional example shown in FIG. Almost at the same time as EV
Since the torque command in the regenerative region is issued by the controller 50, the regenerative braking works normally together with the mechanical braking.

The ECT 54 is a controller for inputting information such as the accelerator amount and the vehicle speed from the EV controller 50, and controlling the A / T 46. That is, when it is recognized that the predetermined shift condition is satisfied based on the information such as the accelerator amount and the vehicle speed, the ECT 54 issues a shift command to the A / T 46 to execute the shift operation. Also, ECT 54 is E
The shift signal (and the amount of torque reduction) to the V controller 50
Is given as a signal. The shift signal is turned on at the start of the shift operation and turned off at the end. The torque reduction amount indicates a torque reduction amount of the motor 10 for controlling the rotation speed of the motor 10 and suppressing a shock at the time of shifting.

The feature of this embodiment is that A / T
A step 46 is to prevent a shock from being generated when the brake pedal is depressed while the shift is being performed and the brake pedal is continuously depressed even after the shift is completed. That is, as shown in FIG. 2, the braking feeling is improved by gradually increasing the regenerative braking force and gradually increasing the deceleration G after the shift period ends.

FIG. 3 shows a flow of the operation of the EV controller 50 in this embodiment. The operation shown in this figure is a one-cycle operation related to the operation shown in FIG.

First, at the start of the cycle, the EV controller 50 determines whether or not the shift signal from the ECT 54 is on (100). When the shift signal is not on, there is no need to perform control to reduce the torque of the motor 10. Thus, the EV controller 50 executes a normal control.

In normal control, first, in step 102,
Is executed. In step 102, the EV controller 50 determines whether or not the brake pedal is depressed. This determination is made based on the state of the brake switch. If it is not stepped on, the EV controller 50 calculates the torque command value T in the powering region because there is no need to perform braking (104). Thereby, motor 10 generates the driving force of the vehicle, and the cycle shown in the figure ends.

If it is determined in step 102 that the brake pedal is depressed, the EV controller 50 sets The process proceeds to flag determination (106). G. FIG. fl
“ag” is a flag indicating whether or not the brake pedal is depressed during the shift period. If the flag is initially set to “0”, it has a value of “0” in normal times. Therefore, when the brake pedal is depressed at a time other than the gear shift period, G.P. fla
Since g = 0, after execution of step 106, step 1
08.

In step 108, the EV controller 50 calculates a torque command value T based on the brake amount and the like. The torque command value T obtained here is a value belonging to the regeneration region. Thereby, the battery 1 is
2 regenerates the energy, a regenerative braking force is generated, and the cycle shown in this figure ends. At this time, since the brake pedal is depressed, a mechanical braking force is also generated.

If it is determined in step 100 that the shift signal is on, the EV controller 50
Shifts to torque down control. In this control, first, it is determined whether or not the brake pedal is depressed (1).
10). If the brake pedal is not depressed, E
The V controller 50 has a G. After setting the flag to 0, (112) the torque command value T is set to the torque down value (114). How much torque is reduced
Determined according to the amount of torque reduction from ECT 54. When the output torque of the motor 10 is controlled based on the torque command value T, the motor torque during the shift period decreases, the rotation speed changes, and the rotation speed of the motor 10 at the end of the shift period and A / T4
6, the difference in the number of rotations of the output shaft is reduced. As a result, the shock due to the shift is reduced.

If it is determined in step 110 that the brake pedal is depressed, the EV controller 5
0 is G. After setting the flag to 1 (116), the torque command value T is set to 0 (118). Then, as shown in FIG. 2, the regenerative braking does not work during the shift period, and only the mechanical braking force works as the braking force.
Therefore, the output torque of the motor 10 approaches the torque of the output shaft of the A / T 46 as compared with the case where regenerative braking is also performed during the torque down control, which leads to a reduction in shift shock. This ends the cycle.

When the next cycle is executed in a state where the cycle has been completed through steps 116 and 118, if the speed change operation has not been completed at that time and the brake switch has been kept on, steps 116 and 118 are executed. Are executed again. If the shift operation has not been completed at that time and the brake switch has been turned off, a cycle including steps 112 and 114 is executed, and the process shifts to torque down control. If the shift operation has been completed at that time, the process proceeds to step 102.

The case where the routine proceeds to step 102 after steps 116 and 118 means that the brake switch is not turned off during the shift period and the braking operation is continued after the end of the shift period as shown in FIG. is there. In this case, step 120 is performed first.

In step 120, a torque target value T0 is calculated. The torque target value T0 is a value indicating a regenerative braking torque finally required. This target value T0 is determined based on the brake amount and the like. EV controller 50
Is T0 / 20 per cycle in order to gradually generate a regenerative braking torque corresponding to the determined torque target value T0.
Each time, the torque command value T is increased. Specifically, the torque command value T is obtained as (k / 20) T0 (122),
While incrementing k (124), the cycle including step 122 is repeatedly executed until k reaches 20 (126). When k reaches 20, the torque command value T becomes T0.
Are k and G. The flag is reset to 0 (128).

The cycle executed after the torque command value T = T0 is set in step 104 or 1
08 is a cycle including the number 08. Which cycle is executed depends on the state of the brake switch.

FIG. 4 shows a torque change at the time of upshifting in this embodiment. When the brake switch is not on, first, from the start of the shift operation (t0) to the time when the ECT 54 turns on the shift signal (t1), E
V controller 50 executes a cycle including step 104. Therefore, the output torque of the motor 10 becomes the torque during power running.

Next, when the ECT 54 turns on the shift signal at time t1, the EV controller 50 responds accordingly.
Moves to a cycle that includes steps 112 and 114. Then, since the torque down control of the motor 10 is performed, the output torque of the motor 10 decreases.

Further, assuming that the brake switch is turned on at time t2, the execution cycle of EV controller 50 shifts to a cycle including steps 116 and 118 in response. Therefore, the output torque of the motor 10 is 0
Becomes

Thereafter, when the shift signal is turned off while the brake switch remains on (t3), the execution cycle of the EV controller 50 shifts to a cycle including steps 120 to 128. Therefore, the regenerative braking torque of the motor 10 starts to gradually increase, and ends when the target value T0 is reached (t4).

As described above, according to this embodiment, A / T4
Even when the brake pedal is depressed during the shift operation of the brake pedal 6 and the braking operation is continued even after the shift operation is completed, sudden generation of the regenerative braking torque does not occur. Therefore, an electric vehicle with improved brake feeling is realized.

The torque command value T per cycle T
Is not limited to 1/20 of the target value T0. Further, the increase in the torque command value T may be non-linear.

[0038]

As described above, according to the present invention,
When the braking operation is started during the shift period, the shift shock can be reduced by using only the mechanical braking force as the braking force. Further, when the braking operation started during the shift period is continued at the end of the shift, the regenerative braking force is gradually generated, so that sudden deceleration does not occur at the end of the shift, and the brake feeling is reduced. improves.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electric vehicle according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a deceleration operation in the embodiment.

FIG. 3 is a flowchart showing an operation of the EV controller in the embodiment.

FIG. 4 is a time chart showing an example of a torque change in this embodiment.

FIG. 5 is a block diagram showing a configuration of a first conventional example.

FIG. 6 is a circuit diagram showing a configuration of a first conventional example.

FIG. 7 is a diagram showing a conventional problem.

[Explanation of symbols]

 Reference Signs List 10 motor 12 battery 14 power converter 46 automatic transmission (A / T) 50 EV controller 54 ECT

Claims (1)

(57) [Claims] 1. A drive motor as a drive source of a vehicle, a transmission interposed between an output shaft of the drive motor and wheels, and mechanical braking of wheels and regenerative braking of the drive motor in accordance with a braking operation. In an electric vehicle equipped with a braking means, means for generating only mechanical braking force when a braking operation is started in a state where the transmission is shifting, and braking when the shifting operation of the transmission is completed. Means for gradually generating a regenerative braking force when the operation is continued, a braking control device comprising: