JPH02250603A - Regenerative brake controller for electric vehicle - Google Patents

Abstract

PURPOSE:To prevent shifted braking by detecting failure of liquid pressure brake of any one of right and left systems through a regenerative brake control section and producing a regenerative torque command variable signal in such a manner that the regenerative control amount will be smaller than the regenerative control amount of wheel motor at failure side. CONSTITUTION:A liquid pressure sensor 34a produces a regenerative torque command variable signal sigmaB* while a liquid pressure sensor 34b produces a regenerative torque command variable signal sigmaB**. Then they are compared in a control circuit 32. If they do not match each other, it is judged that any one system brake is detective. If sigmaB*>sigmaB**, regenerative control torque command T1 to be fed to a motor drive circuit 30a is brought lower than a regenerative brake torque command T2 being fed to the defective motor drive circuit 30b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a regenerative braking control device for an electric vehicle, and particularly to a regenerative braking control device for an electric vehicle that is equipped with separate wheeled motors for driving left and right wheels of the vehicle. This relates to a control device.

[Prior Art] Conventionally, regenerative braking has been known in electric vehicles, in which a braking force equivalent to engine braking in an engine vehicle is exerted by regenerative braking of a driving motor, and a battery is further charged with the generated energy. By recovering this energy, the driving distance per battery charge is increased.

Furthermore, in order to enhance the effect of such energy recovery, some brakes perform regenerative braking of the drive motor in response to the amount of operation of the brake operator of the hydraulic brake. This increases braking force, increases recovered energy, and - extends the mileage per charge.

An example of an electric vehicle using such regenerative braking is disclosed in Japanese Patent Application Laid-Open No. 59-209004, and the applicant has further proposed a regenerative braking control device that improves such regenerative braking. (Jitgan 62-151)
No. 901).

Further, in the hydraulic brake, a dual system brake is employed to ensure safety in the event of failure, that is, to provide a complementary function in the event of failure. Japanese Patent Publication No. 58-15644
Publication No. 8 discloses a device that detects the differential pressure between the output brakes of two brake systems and issues an alarm when this differential pressure exceeds a predetermined amount to prevent serious failures from occurring. .

In addition, models that use dual-system hydraulic brakes use means for controlling the two systems in a sash pattern, with one system for each of the left and right front wheels and one system for the opposite left and right rear wheels. has been done.

According to this type of dual-system hydraulic brake, even if a failure occurs in the hydraulic brake of one system, the braking force of the other system can apply braking force to both the left and right wheels. It is possible to compensate for the deficiencies of

FIG. 6 shows an example of a regenerative braking control device for an electric vehicle having two systems of hydraulic braking means in the form of a sash. A mask cylinder 12 is configured to be driven by depression of a brake pedal 10, which is a brake operator, and a brake switch 14 is attached to detect whether or not the brake pedal 10 is depressed.

The mask cylinder 12 has a first chamber 12a and a second chamber 12.
b is formed, and pressure oil is supplied to the brake system of each system. The first chamber 12a includes brake piping 16.
a, 16b and 16c are connected. The pipes 16b and 18c are used to apply hydraulic brakes to the front left wheel 18a and the rear right wheel 20a of the vehicle, respectively. Pipes 22a, 22b, and 22c are coupled to the second chamber 12b to brake the right front wheel 18b and the left rear wheel 20b.

In order to detect the hydraulic pressure of these hydraulic brakes, one hydraulic pressure sensor 24 is installed at a predetermined location on the piping. This hydraulic pressure sensor 24 detects a hydraulic pressure corresponding to the depression force of the brake pedal 10, and outputs a regenerative torque command variable signal δB1 proportional to this hydraulic pressure.

As for the drive motors, wheeled motors 26a and 26b are provided, one for each of the front wheels 18a and 18b. Rotation sensors 28a and 28b are attached to each wheeled motor, respectively.

Rotation control and regenerative braking control of the respective wheeled motors 26a and 26b during running are performed by correspondingly provided motor drive circuits 30a and 30b. These motor drive circuits 30a and 30b
, are driven based on a control signal from the control circuit 32.

According to such an electric vehicle, the hydraulic brake control system is divided into two systems in the form of a sash, so that even if one system fails, the other system's hydraulic brake system can apply braking force to the left and right wheels. .

In addition, a regenerative torque command variable signal 6 is output from the hydraulic pressure sensor 24.
Based on B11, the control circuit 32 controls the motor drive circuit 30a.
A control signal can be sent to 30b and 30b to output a regenerative braking amount proportional to the amount of depression of the brake pedal 10.

[Problems to be Solved by the Invention] Among the conventional regenerative braking control devices mentioned above, Japanese Patent Laid-Open No. 59-20
The control device disclosed in Publication No. 9004 and related to Utility Application No. 151901/1989 filed by the applicant is related to regenerative braking control when the mechanical brake is operating normally. No consideration has been given to measures to be taken in the event that the mechanical brake fails, and there is a problem in that a safety control device is required in the event of such failure.

Furthermore, the device disclosed in Japanese Patent Application Laid-open No. 58-156448 only issues an alarm when it detects a failure in the two-brake system, so it is insufficient as a safety control and prevents failures. When the degree of danger is large, there is a problem in that it is difficult to avoid danger.

Furthermore, according to the device shown in FIG. 6, if one of the two sash-like hydraulic brake systems fails, it is possible to apply braking to the left and right wheels using the other brake system. However, in order to apply more braking to the front wheels of the vehicle within the membrane, the amount of braking on the front wheels is increased, for example at a ratio of about 8:2, so if one system fails, the hydraulic brakes will not work. Can be left or right handed. For this reason,
There is a problem in that during braking, a moment acts that tends to rotate the vehicle, necessitating correction by operating the steering wheel. In this device, the hydraulic pressure sensor 24 is
Since it is not used to detect a failure state of the hydraulic brake, but is used only to detect the amount of depression of the brake pedal 10, it has been difficult to take safety control measures against failure of the hydraulic brake. .

Purpose of the Invention The present invention has been made to solve the above-mentioned problems, and its purpose is to perform regenerative braking control of the drive motor when one of the two left and right hydraulic brake systems fails. An object of the present invention is to provide a regenerative braking control device for an electric vehicle that can prevent one-handedness during braking.

[Means for Solving the Problems] In order to achieve the above object, a regenerative braking control device for an electric vehicle according to the present invention includes wheeled motors that are respectively installed on the left and right wheels of an electric vehicle and transmit rotational driving force to the corresponding wheels. and a regenerative braking control device for an electric vehicle having two systems of hydraulic brakes for braking at least left and right front wheels in separate systems, the system separately detecting the hydraulic pressure of each of the two systems of hydraulic brakes. a hydraulic pressure sensor unit that separately outputs one type of regenerative torque command variable signal according to each detection result; and a regenerative unit that outputs a regenerative braking torque command value based on the regenerative torque command variable signal from the hydraulic pressure sensor unit. The regenerative braking control section compares the two types of output signals of the hydraulic pressure sensor section, detects failure of the hydraulic brake of either the left or right system, and detects failure of the hydraulic brake of either the left or right system, and The present invention is characterized in that a regenerative braking torque command value is determined and outputted so that the regenerative braking amount of the wheeled motor on the left and right opposite wheels is smaller than the regenerative braking amount of the failed wheeled motor.

[Function] The regenerative braking control unit can detect failure of either the left or right hydraulic brake system based on the fluid pressure of each of the two hydraulic brake systems detected by the hydraulic pressure sensor unit. Based on this detection result, each wheeled motor is controlled so that the regenerative braking amount of the wheeled motor installed on the wheel on the left and right sides opposite to the defective side is made smaller than the regenerative braking amount of the wheeled motor of the wheel on the defective side. A regenerative torque command variable signal can be output to. As a result, if the hydraulic brake system that brakes either the left or right front wheel fails, the braking force on the failed side can be supplemented by regenerative braking, reducing the rotational moment applied to the vehicle. . In other words, the amount of regenerative braking applied to the wheeled motor of the wheel on the side where the brake has failed is relatively larger than the amount of regenerative braking applied to the wheeled motor of the wheel on the normally operating side, so that the braking force is applied to the vehicle in a one-sided state. It becomes possible to reduce the moment and maintain the running direction of the vehicle without operating the steering wheel.

[Embodiments] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic explanatory diagram of an electric vehicle having a regenerative braking control device for an electric vehicle according to the present invention. Elements similar to those of the conventional device shown in FIG. Omitted.

The difference between this embodiment and the conventional device is that hydraulic pressure sensors 34a and 34b corresponding to each system are provided as a hydraulic pressure sensor section for detecting two systems of hydraulic brakes. Then, the control circuit 32 selects one of the systems based on the regenerative torque command variable signals δB'' and δ3m' output from the respective hydraulic pressure sensors 34a and 34b according to the hydraulic pressure, that is, by comparing both signals. The system is characterized in that it detects failure of the brake system and adjusts and controls the amount of regenerative braking of the wheeled motors 28a and 28b provided on the left and right front wheels 18a and 18b, respectively.

Next, the control operation of this embodiment will be explained based on FIG. 2.

FIG. 2 is a flowchart showing the control logic of regenerative braking according to this embodiment. First, when the brake pedal 10 is depressed, the brake switch 14 is turned on (S
l is Yes) o In addition, if the brake pedal 10 is not depressed and the brake switch is OFF (Sl is No), B
The rk Flag (brake flag) is set to 0, and regenerative braking is not controlled.

If Sl is Yes, the regenerative torque command variable signals respectively output from the hydraulic pressure sensors 34a and 34b are compared. The hydraulic pressure sensor 34a outputs a regenerative torque command variable signal δB8 based on the hydraulic pressure of a brake system that brakes the left front wheel 18a and the right rear wheel 20a. The hydraulic pressure sensor 34b outputs a regenerative torque command variable signal δ gg based on the hydraulic pressure of a hydraulic brake system that brakes the right front wheel 18b and the left rear wheel 20b. Then, these regenerative torque command variable signals δBI' and δB- are compared in the control circuit 32. If both signals almost match (Ye
s), the wheeled motors 26a and 26b are controlled based on a predetermined calculation to obtain a common regenerative braking amount, which will be described later.

If the comparison results of the regenerative torque command variable signals δB″ and δBl differ to such an extent that they cannot be recognized as being consistent (in the case of No), in S3, which system of the two hydraulic brake systems An operation is performed to determine whether a failure has occurred in the brake. In other words, if the relationship between the two regenerative torque command variable signals is 611>δB″″ (in the case of Yes), the left The front wheel 18 on the right side is lower than the hydraulic pressure of the hydraulic brake system that brakes the front wheel 18a.
This indicates that the hydraulic pressure of the hydraulic brake that performs the braking of b is lower than that of the hydraulic brake, and it is determined that some kind of failure has occurred in the hydraulic brake on the right front wheel 18b side.

In this case, in S4, the defective right front wheel 18b
The regenerative braking torque command value T2 is supplied to the motor drive circuit 30a of the left front wheel 18a on the hydraulic brake side that is normally operating with respect to the regenerative braking torque command value T2 supplied to the motor drive circuit 30b on the side. , is calculated to be lower than T2 by a predetermined amount.

This calculation is performed based on a preset regenerative torque command variable signal and a map showing the relationship between the regenerative braking torque command value and the regenerative braking amount determination coefficient as shown in FIG. In the figure, τ is a coefficient for determining the amount of regenerative braking according to the brake fluid pressure when the hydraulic brake is working normally. On the other hand, e indicates a coefficient for determining the amount of regenerative braking that is weakened by a predetermined amount that is instructed to the non-failure side drive motor (normally operating side) when a failure occurs in the hydraulic brake.

With this map, the motor drive circuit 30 on the defective side
The regenerative braking torque command value T2 supplied to the b side is τ・δB
Regenerative braking torque command value T supplied to the motor drive circuit 30a on the pneumatic brake side that is normally operating.
, is calculated as e·δB8.

Further, if both regenerative torque command variable signals do not have a relationship of δ g >δBs'', that is, if NO in S3, it is assumed that a failure has occurred in the hydraulic brake system that performs the braking operation of the left front wheel 18a. be judged.

Therefore, contrary to the above, the regenerative torque command value T1 supplied to the motor drive circuit 30a on the side where the pneumatic brake has failed in S5 is calculated as τ・δB''' and is supplied to the motor drive circuit 30b on the opposite side. The regenerative braking torque command value T2 is calculated as e·δB−.

That is, the respective command values T1 and T2 are calculated based on the normal regenerative braking torque command value.

In this manner, the control circuit 32 can detect failure of the hydraulic brake in either system based on the comparison result based on the regenerative torque command variable signals from the hydraulic pressure sensors 34a and 34b. The wheeled motor 26a or 26b drives the wheel on the brake failure side depending on the brake failure side.
The amount of regenerative braking exerted by this can be made relatively larger than the amount of regenerative braking of the normally operating wheeled motor on the hydraulic brake side. In this example,
Wheeled motors 26a and 26b are respectively provided on the front wheel side, and it is possible to set a difference in the amount of regenerative braking with respect to the front wheel side, where approximately 80% of the braking amount of the hydraulic brake is applied. It is also possible to reduce the moment exerted on the vehicle by a system hydraulic brake failure to a small amount that does not cause the vehicle to rotate.

Next, the regenerative braking control operation when it is determined in S2 that both regenerative torque command variable signals δB8 and δB″11 match (in the case of Yes) will be described.

In this case, regenerative braking control prevents deterioration of brake feeling due to increased deceleration because the braking torque increases as the vehicle speed decreases, as shown in the regenerative torque characteristics of the motor shown in Figure 4. It is done for the purpose of

That is, as shown in FIG. 4, when the regenerative torque of the motor exceeds the rated rotational speed n, the maximum regenerative braking torque tends to decrease as the rotational speed increases. Therefore, when the brake pedal 10 is continuously depressed and the vehicle speed decreases, the regenerative torque increases if the regenerative torque command variable signal δB based on the amount of depression is constant. To prevent this, while the brake pedal 10 is continuously depressed, the maximum motor torque command value T"s obtained at the vehicle speed (motor rotation speed) at the time the brake pedal 10 is depressed
The regenerative braking torque command value T is intended to be determined only by the value of the regenerative torque command variable signal δB, which is proportional to the amount of depression of the brake pedal 10, with ax constant.

First, in S6, it is determined whether Brk Flag is 1 (Brk Flag-1?).

If this flag is 0 (S8 is No), this is the first loop in which the brake pedal 10 was depressed, so
In S8, a maximum regenerative braking torque command value T"■aX corresponding to the motor rotational speed at that time is calculated. This calculation is performed by the control circuit 32, but the control circuit 32
The characteristics of the regenerative torque as shown in the figure are stored in advance, and T''max is calculated according to the rotational speed detected by the rotational speed sensors 28a and 28b provided on each wheeled motor 26a and 26b, respectively. .

Then, the maximum regenerative braking torque command value T1■aX is multiplied by the regenerative torque command variable signal δB3 from the hydraulic pressure sensor 34a (the same is true even if it is multiplied by δB0), and the regenerative braking torque command values T1 and Tz are calculated (T+ −Tz−δB”
・T”wax) o As a result, the regenerative braking torque command values T1 and Tz correspond to the amount of depression of the brake pedal 10, that is, the driver's deceleration instruction.Then, the control circuit 32 uses this regenerative braking torque command The values T and Tz are supplied to motor drive circuits 30a and 30b, respectively, to control regenerative braking of each wheeled motor.

Next, after outputting the regenerative braking torque command values T1 and Tz, the Brk Flag is set to 1 in the SIO. This completes the first control loop in which the brake is depressed, and moves on to the next control.

In the second and subsequent loops, if the brake pedal 10 is continued to be depressed, the Brk Flag remains 1, so a Yes determination is made in S6, and the process in S7 is performed. That is, the regenerative braking torques T and Tz are calculated by multiplying the first calculated T''+oax by δB'' from the hydraulic pressure sensor 34a. Then, the regenerative braking of each wheeled motor 26a and 26b is controlled by the regenerative braking torque T and Tz. As a result, while the brake pedal 10 is kept being depressed, the regenerative braking torque command fii! is generated only when the regenerative torque command variable signal δB' changes! T will be changed.

Therefore, when there is no failure in the hydraulic brakes of the two systems, each processing operation from S6 to SIO effectively prevents the regenerative braking torque from increasing as the vehicle speed decreases and worsening the brake feeling. can do.

FIG. 5 is a flowchart showing the operation of another embodiment of the present invention, and the points that differ from the operation of the embodiment shown in FIG.
Each hydraulic pressure sensor 34 detects failure of two systems of hydraulic brakes.
The difference between the regenerative torque command variable signals δI]'' and δgm from a and 34b is detected not by the difference but by the ratio.

In the flowchart of FIG. 5, 5101 and 510
2, the failure of the hydraulic brake is detected, and other processing is the same as in the flowchart of FIG.

First, if the brake switch is turned on, 1;
At 5101, it is determined whether the relationship δB8/δIII>l+α holds true. This determination is to determine whether the ratio of δB8 output by the hydraulic pressure sensor 34a to the regenerative torque command variable signal δB0 output by the hydraulic pressure sensor 34b is greater than a predetermined value (1+α). If Yes here, it means that the hydraulic pressure detected by the hydraulic pressure sensor 34b is relatively low, and the hydraulic pressure for braking the right front wheel 18b of the system detected by the hydraulic pressure sensor 34b is It is determined that the brake has failed. In this case, at 5103, the same process as 84 in FIG. 2 is performed. That is, the control circuit 32 sets the regenerative braking torque command value T supplied to the motor drive circuit 30b of the right front wheel 18b on the failure side based on the map shown in FIG.
2, τ・δB1, and the regenerative braking torque command value T calculated by e・δBI′ is supplied to the motor drive circuit 30a of the left front wheel 18m on the hydraulic brake side which is normally operating. .

Next, if 5IOI is No, it is determined in 5102 whether the ratio of the output signal δB- of the hydraulic pressure sensor 34b to the output signal δBI' of the hydraulic pressure sensor 34a is smaller than a predetermined value (1-β). Here, δts”/δB0ku1−
If β is Yes, it means that the hydraulic pressure of the hydraulic brake in the system detected by the hydraulic pressure sensor 34g is relatively low, and the hydraulic brake on the side that brakes the left front wheel 18a has failed. It is determined that this is occurring.

Then, in 5104, the same process as S5 in ff12E is performed, and the motor drive circuit 3 of the left front wheel 18a
The regenerative braking torque command value T calculated by τ・δ gm is supplied to 0a, and the motor drive circuit 30b of the right front wheel 18b on the normally operating side is supplied with e・δ gm.
A regenerative braking torque command value T2 calculated by is supplied.

According to this embodiment, similar to the operation of the embodiment shown in FIG. The moment in the rotational direction caused by failure of the hydraulic brake in the system can be reduced to an extent that does not affect the running of the vehicle.

Furthermore, according to this embodiment, the regenerative torque command variable signal δ,
Since it is decided to detect a failure based on the ratio of , it is possible to detect a failure even when both variable signals 68'' and δ,1 have small values during light braking.

[Effects of the Invention] As explained above, according to the regenerative braking control device for an electric vehicle according to the present invention, when either one of the two left and right hydraulic brake systems fails, the drive motors for the left and right wheels are activated. The amount of regenerative braking can be adjusted. As a result, when one side of the hydraulic brake fails, the braking force can be balanced by the regenerative braking amount of the wheeled motor, and the moment in the rotational direction against the vehicle caused by one-handed brake can be reduced. It is possible to improve driving safety.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of an electric vehicle using the regenerative braking control device for an electric vehicle according to the present invention, FIG. 2 is a flowchart showing the operation of the embodiment, and FIG. 3 is a normal state and a state used in the embodiment. A map diagram showing the coefficients for determining the regenerative braking torque command value at the time of brake failure. Figure 4 is a regenerative torque characteristic diagram showing the relationship between regenerative torque and motor rotation speed. Figure 5 is the operation of another embodiment. FIG. 6 is a schematic explanatory diagram of an electric vehicle using a conventional regenerative braking control device. 10... Brake pedal 12... Mask cylinder 14... Brake switch 18... Front wheel 20... Rear wheel 16.22... Pressure fluid piping 26... Wheeled motor 32... Control circuit

Claims (1)

[Scope of Claims] A wheeled motor that is individually installed on the left and right wheels of an electric vehicle and transmits rotational driving force to the corresponding wheels, and two systems of hydraulic brakes, one on the left and one on the left, that brake at least the left and right front wheels in separate systems. A regenerative braking control device for an electric vehicle, comprising: a hydraulic pressure sensor that separately detects the hydraulic pressure of the two systems of hydraulic brakes and separately outputs one type of regenerative torque command variable signal according to each detection result. and a regenerative braking control unit that outputs a regenerative braking torque command value based on a regenerative torque command variable signal from the hydraulic pressure sensor unit, and the regenerative braking control unit is configured to control the two types of hydraulic pressure sensor units. A failure of the hydraulic brake in either the left or right system is detected by comparing the output signals of the system, and the amount of regenerative braking of the wheeled motors of the wheel on the failure side and the opposite left and right wheels is changed to the regenerative braking amount of the wheeled motor on the failure side. A regenerative braking control device for an electric vehicle, characterized in that the regenerative braking torque command value is determined and outputted so as to be smaller than the regenerative braking torque command value.