JP2005348497A - Driving force controller at braking for electric motor vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of pitch behavior in a car body caused by the swing-back of nose-dive, immediately after braking. <P>SOLUTION: In step S1, whether a vehicle is in a braking state or not is judged. In the next step S2, when the vehicle is in the braking state, whether the vehicle speed is in a state near stoppage immediate before stop or not is judged. In the next step S3, when the vehicle is in the state near stoppage, whether the vehicle is in an emergency braking operation or not is judged. In the next step S4, when the vehicle is not in the emergency braking operation, driving force control at the time of braking is started. In the driving force control at the time of braking, a motor controller 8 computes the additional drive force of a sine waveform to output the additional drive force Sin of the computed sine waveform to a motor control unit 6 as a command value. The generation start time t<SB>0</SB>and the stoppage time t<SB>2</SB>of the additional drive force Sin are computed from detected vehicle speed and deceleration speed G1. As a result, a vehicle 21 gradually approaches 0 immediate before stoppage, after maintaining a first deceleration speed G1 at the initial stage of the state near stoppage, making the deceleration speed G to 0 at the stoppage time t<SB>2</SB>to stop the vehicle. When the vehicle speed and the deceleration speed reach 0 at the stoppage time t<SB>2</SB>, step S4 is advanced to step S5, completing the driving force control at the time of braking of the step S4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for making use of the high responsiveness of an electric motor to suppress the occurrence of pitch behavior in a vehicle body due to swinging back immediately after braking.

When the vehicle stops due to braking, the deceleration by the brake mechanism generally continues until the stop, so that there is a problem that nose dive swings back immediately after stopping.
This nose dive rocking, combined with the natural vibration of the suspension device that suspends the front wheels of the vehicle, causes pitch behavior that repeats bouncing and rebounding, and deteriorates ride comfort performance. FIG. 5A and FIG. 5B are time charts showing the deceleration during braking and the pitch behavior.

As shown in FIG. 5 (a) in general, the deceleration G due to braking continues with G1 until the stop time t ₁ at which the vehicle is stopped, and 0 to intermittently changed at the stop time t ₁ Become. Pitch behavior Therefore vehicle, as shown in FIG. 5 (b), the vehicle is to stop time t ₁ pitch angle φ is nose dive to maintain the posture + [deg] of the previous edge of .phi.1. After the stop time t _1, the pitch angle φ once passes through 0 and becomes a forward rising posture − [deg], and the nose dive swings back. Thereafter, the pitch angle φ is attenuated while repeatedly increasing and decreasing.

Conventionally, for example, the one described in Patent Document 1 is known as an invention for suppressing the pitch behavior after nose dive swinging back and stopping.
The preceding vehicle follow-up control device described in Patent Document 1 reduces the nose dive amount and prevents the swing-back from occurring by relaxing the deceleration caused by the brake mechanism when stopping following the preceding vehicle. To do.
JP 2001-30795 A

  However, the preceding vehicle follow-up control device as described above causes problems as described below. In other words, the brake hydraulic mechanism that generates the braking force in the preceding vehicle follow-up control device as described above has a large control nonlinearity and a large response time constant, so it cannot accurately follow the pitch behavior and rebounds. Is difficult to completely prevent.

On the other hand, among industrial electric motors, it is known that the responsiveness of SR motors and the like is generally responsive to 100 Hz or more, and even motors for electric vehicles can be controlled with similar responsiveness. it can. For this reason, it is possible to control the torque at intervals of several [msec].
This invention pays attention to the high response performance which the drive motor of an electric vehicle has, and the technique which can suppress effectively said pitch behavior generate | occur | produced immediately after a stop by the high response drive force control via the said motor. This is a proposal.

For this purpose, the braking force driving force control apparatus for an electric vehicle according to the present invention is as described in claim 1.
In an electric vehicle comprising brake means for applying a braking force to a wheel to stop the vehicle, and a motor for driving the wheel,
Means for detecting the vehicle speed and deceleration during braking by the brake means, and calculating an additional driving force of the wheel that suppresses the pitch behavior of the vehicle body that occurs immediately after the vehicle stops according to the detected vehicle speed and deceleration. Additional driving force calculating means for
And a motor driving force control means for controlling the driving force of the motor so that the additional driving force is applied to the wheels.

  According to the braking force driving force control apparatus for an electric vehicle of the present invention, the deceleration G immediately before the stop can be prevented from intermittently becoming zero, and therefore, the generation of pitch behavior due to the nose dive swinging back. Can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view schematically showing an overall configuration of an electric vehicle (electric vehicle) including a braking driving force control device according to an embodiment of the present invention.
The electric vehicle 21 has a total of four wheels 1, 2, 3, 4 on the front, rear, left and right. Of these, the rear wheels 3 and 4 are driven by a motor 5. The motor 5 is connected to a driving power source 7 via a motor controller 6. The motor controller 6 controls the driving force of the motor 5 by controlling the power supplied to the motor 5. The motor controller 8 calculates a command value of the target driving force necessary for normal traveling and outputs the calculated command value tT to the motor controller 6.

  The vehicle 21 is braked by hydraulic brake devices 11, 12, 13, and 14 provided on the wheels 1, 2, 3, and 4, respectively. During braking, the vehicles 21, 12, 13, 14 brake the wheels 1, 2, 3, 4 so that the deceleration G according to the driver's braking operation amount is reached, and the vehicle 21 stops until the vehicle 21 stops. A deceleration G1, which will be described later, is applied.

The motor controller 8 executes the driving force control during braking, which is the object of the present invention described above, when the vehicle 21 is stopped.
Therefore, the motor controller 8 detects the signal vsp from the vehicle speed sensor 9 that detects the vehicle speed of the vehicle 21, the signal on / off from the brake switch 10 that detects depression of a brake pedal (not shown), and the longitudinal deceleration. The signal G from the deceleration sensor 15 to be input is input.

  The motor controller 8 reads these input information at every control cycle of 10 [msec] at the latest by the scheduled interruption, and executes the control program shown in the flowchart in FIG. Execute.

First, in step S1, it is determined whether the brake pedal is depressed. If the brake pedal is not depressed (No), this control is terminated and the brake operation is continuously monitored. If the vehicle is being depressed (Yes), a deceleration G1 and a pitch angle φ, which will be described later, act on the vehicle 21, and the process proceeds to step S2.
In the next step S2, it is determined whether or not the vehicle speed is in the vicinity of the stop just before the stop. This determination is made by determining whether the vehicle speed is equal to or less than a predetermined value of, for example, 5 [km / h]. If the vehicle speed exceeds 5 [km / h] and it is determined that the vehicle is not in the vicinity of the stop (No), this control is terminated and the process returns to step S1.

  If it is determined that the vehicle is in the vicinity of a stop (Yes), the process proceeds to step S3, where it is determined whether an emergency brake operation is being performed. This determination is made, for example, by determining whether the detection value of the deceleration sensor 15 exceeds 0.3 [G], which is the upper limit of the normal brake deceleration. When the detected value of the deceleration sensor 15 exceeds 0.3 [G] (Yes), the driver is in an emergency brake operation and therefore needs a full brake (full braking) state, and executes a braking driving force control described later. That is not desirable. For this reason, this control is complete | finished and it returns to step S1. [G] is a unit of gravity acceleration.

When the detected value of the deceleration sensor 15 is 0.3 [G] or less (No), the driver is in a normal braking operation (No), so the driving force control during braking is started in the next step S4.
The braking driving force control will be described based on a time chart.
The motor controller 8 calculates an additional driving force having a sine waveform and outputs the calculated additional driving force Sin having a sine waveform to the motor controller 6 as a command value tT. Generation start time t ₀ of the additional driving force Sin is the before stop time t ₁ of the vehicle when not running braking driving force control of the present invention. Start time t ₀ and stop time t ₂ in size as well as the control of the additional driving force Sin is calculated from the detected vehicle speed and deceleration G1. Start time _{t 0} is about 0.05 seconds before the stop time _{t 2.}

The pitch behavior of the vehicle is an eigenvalue for each vehicle type, and is 5 to 20 Hz for a normal passenger car, and generally about 10 Hz. For this reason, in the driving force control of the present embodiment in which the pitch angle φ returns to 0 from the nose dive state, 10 Hz which is a general eigenvalue of the pitch behavior, that is, 0 which is a half cycle of a 0.1 second cycle. based on the .05 seconds, the start time _{t 0.}
Incidentally, even if the eigenvalues of pitching behavior executes the driving force control in 0.05 seconds if not 10 Hz, the pitch activity that occurs immediately after the vehicle stop time t ₂ is very small, deteriorating the ride comfort of the passenger It doesn't come to let me. Of course, conducted experiments to determine the natural frequency of pitching behavior for each vehicle model, it may be determined start time t ₀ based on experimental results.
For comparison, FIG. 3A shows a conventional deceleration, and the deceleration G1 when this control is not performed is indicated by a thin line.

By applying the additional driving force Sin to the electric vehicle 21 being braked in the vicinity of the stop, the deceleration G of the vehicle 21 is set to the initial deceleration G1 in the initial state in the vicinity of the stop as shown in FIG. after maintaining smoothly approaches zero immediately before stop, allowed to stop the vehicle with becomes 0 at the stop time t ₂ subsequent to t _1.

The pitch behavior of the vehicle 21 as a result of executing the above-described braking driving force control is shown in the time chart of FIG. 3B in comparison with the conventional pitch behavior.
In the prior art, as shown by the thin line in FIG. 3 (a) and FIG. 5 (a), the deceleration G is sustained G1 until the stop time t _1, the vehicle stops at the same time, the intermittent 0 Become. Therefore, as shown by the thin lines in FIGS. 3 (b) and 5 (b), the nose in which the front portion of the vehicle sinks while the pitch angle is φ1 [deg] until the vehicle is stopped during braking. The dive is maintained, and immediately after the vehicle stops, the pitch angle attenuates while vibrating in the positive and negative directions, and the front part of the vehicle bounces and rebounds.
In the present embodiment, together with the smooth form 0 deceleration G immediately before stopping the G1, allowed to stop the vehicle at the time point t ₂ when the deceleration is zero. For this reason, as indicated by the thick line in FIG. 3B, the pitch angle φ smoothly reaches 0 from the initial value φ1 in the vicinity of the stop during braking, and the vehicle stops. Accordingly, the front part of the vehicle that has been nose dive in the early stage of braking starts to be restored from time t _{0 in the} vicinity of the stop, and after the vehicle stops (stop time t ₂ ) Never rebound.

When the vehicle speed and the deceleration becomes 0 at stop time t _2, the process proceeds to step S5, and ends the braking driving force control in step S4, the control is terminated as shown in FIG.

By the way, in the present embodiment, as described above, the vehicle speed sensor 9 and the deceleration sensor 15 that detect the vehicle speed and deceleration during braking,
A motor controller 8 that calculates an additional driving force Sin having a sine waveform that suppresses the pitch behavior of the vehicle body that occurs immediately after the stop according to the detected vehicle speed and deceleration G1;
A motor controller 6 for controlling the driving force of the motor 5 so that the additional driving force Sin is applied to the wheels 3 and 4;
High-response control can be realized by using the drive motor 5 without controlling the deceleration G only by a hydraulic brake mechanism as in the prior art. Therefore, the pitch behavior of the vehicle 21 that occurs immediately after stopping can be effectively suppressed.

Further, in this embodiment, when it is determined in step S2 that the vehicle is in the vicinity of the stop, the motor controller 6 applies the additional driving force Sin having a sinusoidal waveform to the wheels 3 and 4 to reduce the deceleration G during the stop. From 0 to smooth,
Start this control at time t ₀ immediately before the vehicle 21 is stopped, it is possible to perform a control based on a standard number chromatic values in the pitch movement of the vehicle. Accordingly, the deceleration G can be continuously reduced to 0 at the stop time t2, the control accuracy can be improved, the vehicle pitch behavior can be effectively suppressed, and the pitch angle φ can be reduced. It can be changed smoothly from φ1 to 0.

In this embodiment, the brake means of claim 1 is constituted only by the hydraulic brake devices 11, 12, 13, and 14. However, in addition to this embodiment, the motor 5 provides the braking force on the regeneration side on the wheel 3 side. , 4, the hydraulic brake devices 11, 12, 13, 14 and the motor 5 may constitute the brake means of claim 1.
Specifically, when the vehicle 21 is stopped, the motor controller 8 regeneratively controls the motor 5 and uses the braking force Go by the hydraulic brake devices 11, 12, 13, and 14 and the regenerative braking force Gm of the motor 5 in combination. Then, the deceleration G1 (= Go + Gm) near the stop is generated. Then, at time t ₀ immediately before the stop, the motor controller 8 outputs a value obtained by adding the regenerative braking force Gm of the motor 5 and the additional driving force Sin having a sine waveform to the motor controller 6 as a command value. Thereafter, the additional driving force Sin exceeds the regenerative braking force Gm, smoothly close to zero so that additional driving force Sin is a sinusoidal waveform braking force Go by the brake device 11, 12, 13, 14, at stop time t ₂ Deceleration G is set to 0 and the vehicle 21 is stopped. Thereby, the same effects as those shown in FIGS. 3A and 3B can be obtained.

When an additional note for the above embodiment shown in FIG. 3 (a), since the smooth forms and zero deceleration G from G1, stop time t ₂ of the vehicle 21, the stop time t ₁ of the case without the control On the other hand, there is a slight delay.
Therefore, the braking-time driving force control according to another embodiment of the present invention capable of eliminating this delay will be described.
As for the driving force control during braking according to another embodiment, a control program having the same basic configuration as the control program shown in FIG. 2 is executed in the same electric vehicle as the electric vehicle 21 shown in FIG. Therefore, description of parts common to the above embodiment will be omitted, and different control parts will be described.
That is, in this embodiment, in step S4, the additional driving force applied to the wheels 3 and 4 is once set on the braking side and then set on the driving side.

That is, the motor controller 8 first calculates the additional braking force of a sine wave as indicated by a thick line in FIG. 4 (a), additional braking force and deceleration of the sinusoidal waveform calculated from time t ₃ to time t ₄ The sum of G1 is output to the motor controller 6 as a command value.
Next, as shown by a thick line in FIG. 4A, a sinusoidal additional driving force Sin is calculated and time t ₄ is calculated.
From outputs an additional driving force Sin sinusoidal calculated to stop time t ₁ to the motor controller 6 as a command value.
Generation start time t ₃ of the additional braking force Sin sine waveform, and before the stop time t ₁ of the vehicle. Generation start time t ₄ of the additional driving force Sin sinusoidal followed also, and before the stop time t ₁ of the vehicle. Start time t ₃ and the end time t ₄ of the additional braking force according to the control is calculated from the detected vehicle speed and deceleration G1. Start time _{t 3} is about 0.05 seconds before the stop time _{t 1.}

By applying a sinusoidal braking force and a sinusoidal driving force Sin in the electric vehicle 21 being braked, the deceleration G in the vicinity of the stop is maintained at the initial deceleration G1 as shown in FIG. It once increases to Gmax, then decreases and approaches 0 smoothly just before stopping, and becomes 0 at stop time t ₁ to stop the vehicle.

The pitch behavior of the vehicle 21 as a result of executing the braking driving force control according to another embodiment is shown in the time chart of FIG. 4B in comparison with the conventional pitch behavior.
Conventionally, the deceleration G, as shown in FIG. 4 (a) and thin lines in Fig. 5 (a), sustained deceleration G1 until the stop time t _1, the vehicle stops at the same time, intermittently 0. For this reason, as shown by the thin lines in FIGS. 4B and 5B, the front portion of the vehicle sinks while the pitch angle φ remains φ1 [deg] until the vehicle stops during braking. The nose dive is maintained, and immediately after the vehicle stops, the pitch angle φ is attenuated while vibrating positively and negatively, and the front portion of the vehicle bounces and rebounds.

In another embodiment, the deceleration G immediately before stopping in FIG. 4 (a) is increased from G1 to Gmax, and then is smoothly set to 0. When the deceleration G becomes 0, the vehicle is Stop it. Therefore, as shown in above and 4 (b), in addition to being able to suppress the pitch activity phi, the stop time of the vehicle 21, can be the same as conventional stop time t _1, stop delay There is nothing to do. In FIG. 4 (a), since the deceleration G is once increased to Gmax, it is considered that the pitch angle also increases once from φ1, but the pitch behavior is responsive to the change in the deceleration G. Since it is low and the response is delayed, the pitch angle φ does not increase once.

In the another embodiment in this manner, until the time t ₄ from the time t ₃ the stop near state, the motor controller 6 to provide additional braking force of the sine wave to the wheels 3 and 4,
Since the pitch behavior, which is the object of the present invention, can be suppressed, and there is no delay in stoppage, there is a great advantage in terms of safety.

1 is a plan view schematically showing an overall configuration of an electric vehicle including a braking-time driving force control device according to an embodiment of the present invention. It is a flowchart which shows the control program of the driving force control at the time of braking performed in the Example. It is an operation | movement time chart of the driving force control at the time of braking performed in the Example, (a) shows the deceleration G of the vehicle, (b) shows the pitch angle φ of the vehicle. It is an operation | movement time chart of the driving force control at the time of braking performed in the other Example of this invention, (a) shows the deceleration G of a vehicle, (b) shows the pitch angle (phi) of a vehicle. It is the conventional operation | movement time chart which does not perform the driving force control at the time of braking of this invention, (a) shows the deceleration G of a vehicle, (b) shows the pitch angle (phi) of a vehicle.

Explanation of symbols

1, 2, 3, 4 Wheel 5 Motor (Regenerative brake device)
6 Motor controller 7 Power source 8 Control unit 9 Vehicle speed sensor 10 Brake switch 11, 12, 13, 14 Brake device 15 Deceleration sensor

Claims (3)

In an electric vehicle comprising brake means for applying a braking force to a wheel to stop the vehicle, and a motor for driving the wheel,
Means for detecting the vehicle speed and deceleration during braking by the brake means, and calculating an additional driving force of the wheel that suppresses the pitch behavior of the vehicle body that occurs immediately after the vehicle stops according to the detected vehicle speed and deceleration. Additional driving force calculating means for
A braking force driving force control device for an electric vehicle, comprising: motor driving force control means for controlling the driving force of the motor so that the additional driving force is applied to the wheels. The braking-time driving force control device according to claim 1,
The motor driving force control means applies the additional driving force to the wheels to smoothly reduce the deceleration at the time of stopping in the vicinity of the stop, which is the running state immediately before the vehicle stops during the braking. A braking force driving force control apparatus for an electric vehicle characterized by controlling the driving force of the motor. The braking-time driving force control device according to claim 2,
A braking force driving force control apparatus for an electric vehicle, wherein the motor applies an additional braking force to the wheels in the vicinity of the stop.

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