KR20100005764A - Auto hold control method for hybrid and fuel cell vehicle - Google Patents

Abstract

PURPOSE: An auto hold implementation method of a hybrid fuel cell vehicle is provided to improve a control method on a drive motor and a brake control system. CONSTITUTION: An auto hold implementation method of a hybrid fuel cell vehicle comprises: a step for braking by putting a brake pedal; a step for sensing the number of rotation of the motor in a speed sensing sensor and sensing the location of an accelerating pedal simultaneously; a step for converting the control mode of a motor from a torque control mode to a speed control mode in case the position angle of the accelerating pedal is lower than critical angle; and a step for continuously keeping vehicle braking by controlling the speed of the motor to zero.

Description

Auto hold control method for hybrid fuel cell vehicle

The present invention relates to a method for implementing an autohold of a hybrid fuel cell vehicle, and more particularly, to maintain a braking force even when a foot is removed from a road congestion or hill road using a motor or a hydraulic brake system of a hybrid or fuel cell vehicle. The present invention relates to a method for autoholding a hybrid fuel cell vehicle.

The auto hold system of a vehicle is a kind of convenience device that solves the inconvenience of having to continuously press the brake through the pressure maintaining function of the brake when the driver stops for convenience and safe driving.

The autohold system includes a hydraulic solenoid valve mounted on a master cylinder, which is one of the brakes of a general gasoline vehicle, a control unit for controlling the solenoid valve, a speed sensor for detecting the speed of the vehicle, and whether the accelerator pedal is touched or not. And a touch sensor for detecting the brake sensor and a brake sensor for detecting the presence or absence of stepping on the brake pedal.

When the brake pedal is pressed in the D stage (drive stage) or N stage (neutral stage) when the vehicle stops or waits for the intersection signal, it is detected by the brake sensor and sent to the control unit, and the solenoid valve is operated by the control unit. By maintaining the hydraulic pressure of the master cylinder, the vehicle remains in braking state even if the driver takes his foot off the brake pedal after a few seconds.

As such, the autohold system has the advantage that the driver can rest comfortably through the brake pressure maintaining function and can restart the vehicle without being pushed even on a hill or a severe slope.

In addition, it is known that the system operates only when the vehicle is stopped, and that the system does not operate while driving and in reverse.

Of course, the braking force of the vehicle is maintained by the operation of the auto hold system, and the braking force is automatically released when the accelerator pedal is pressed at the start.

The autohold system may be applied to a hybrid vehicle or a fuel cell vehicle, which is a future vehicle to be released in the future, but as the above-described solenoid valve and a control unit need to be additionally installed, the cost may be increased.

The present invention has been made in view of the above, and newly improved control method for a driving motor or a brake control system included in a hybrid vehicle and a fuel cell vehicle, thereby improving the autohold function without adding a separate device. It is an object of the present invention to provide a method for implementing an autohold of a hybrid fuel cell vehicle so as to be easily implemented.

According to an aspect of the present invention, there is provided a method for implementing an autohold of a hybrid fuel cell vehicle, comprising: braking the vehicle by pressing a brake pedal; Sensing the rotational speed of the motor by a speed sensor and simultaneously detecting the position of the accelerator pedal; Switching the control mode of the motor from the torque control mode to the speed control mode if the rotational speed of the motor is equal to or less than a critical rotational speed and the position angle of the accelerator pedal is equal to or less than the critical angle; After the control mode for the motor is switched to the speed control mode, controlling the speed of the motor to zero to maintain the braking state of the vehicle; Characterized in that it comprises a.

According to another aspect of the present invention, there is provided a method for implementing an autohold of a hybrid fuel cell vehicle, the method including: braking the vehicle by pressing a brake pedal; Sensing the rotational speed of the motor by a speed sensor and simultaneously detecting the position of the accelerator pedal; If the rotational speed of the motor is equal to or less than the critical rotational speed and the position angle of the accelerator pedal is equal to or less than the critical angle, continuously operating the brake oil pump under the control of the hydraulic brake braking unit; Continuously operating the brake oil pump to maintain a braking state of the vehicle; Characterized in that it comprises a.

According to still another aspect of the present invention, there is provided a method for implementing an autohold of a hybrid fuel cell vehicle, the method including: braking the vehicle by pressing a brake pedal; Sensing the rotational speed of the motor by a speed sensor and simultaneously detecting the position of the accelerator pedal; Switching the control mode of the motor from the torque control mode to the speed control mode if the rotational speed of the motor is equal to or less than a critical rotational speed and the position angle of the accelerator pedal is equal to or less than the critical angle; Determining the SOC of the energy storage device while measuring the total required braking torque required for braking; In accordance with the SOC of the energy storage device, the total demand braking torque is divided into a braking torque by a motor and a braking torque by a hydraulic brake system; Controlling the speed of the motor to be zero according to the braking torque of the motor and operating the brake oil pump according to the braking torque of the hydraulic brake system; Characterized in that it comprises a.

Preferably, when the detected value of the accelerator position sensor for detecting the position of the accelerator pedal is greater than or equal to the threshold angle, the control mode of the motor is switched to the torque control mode again to restart the vehicle.

Through the above problem solving means, the present invention provides the following effects.

According to the present invention, when the hybrid or fuel cell vehicle is stopped in a traffic congestion or hillside situation, the motor is switched to the speed control mode to maintain the braking state, or the braking state due to the continuous operation of the hydraulic brake system. Continually maintains braking conditions by properly maintaining the braking torque to the motor and the hydraulic brake system according to the amount of charge of the energy storage device, or to maintain the auto hold function easily without adding a separate hardware device. Can be implemented.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a power transmission configuration of a hybrid and a fuel cell vehicle includes driving an energy generation and storage device 10 corresponding to a battery or a fuel cell, and a wheel 12 of a vehicle. A motor 14 connected to the motor 14, an inverter 16 for controlling the motor 14, a hydraulic brake system 18 for providing a braking force to the wheel 12, an HCU 20 as a main controller, The motor control MCU 22 and the like, and in the case of a hybrid vehicle, further include an engine, an automatic transmission, and an engine control unit 24 (ECU) for controlling the engine, in addition to the motor 14 as a driving source.

Unlike general gasoline vehicles, such hybrid and fuel cell vehicles include a hydraulic brake system for appropriately adjusting the torque of the motor and the brake in order to maximize recovery and storage of regenerative energy during braking.

According to the present invention, without additional hardware to the hybrid and fuel cell system as described above, by switching the motor connected to the wheel from the torque control mode to the speed control mode based on the sensing value of the acceleration pedal and the vehicle speed sensing It is possible to provide an autohold function to maintain the braking force or to maintain the braking force using a hydraulic brake braking system.

 Herein, a description will be given of each embodiment of an autoholder implementation method of a hybrid fuel cell vehicle according to the present invention.

First embodiment

EV (electric vehicle) mode, which is a pure electric vehicle mode using only motor power, of a hybrid or fuel cell vehicle, and recovers braking and inertial energy of the vehicle during generation by braking or inertia from the motor through generation of battery. There is Regenerative Braking (RB) mode.

When the vehicle travels in this driving mode, the motor operates in the torque control mode through the control of the main control unit HCU (Motor Control Unit) and the motor controller (Motor Control Unit).

If the driver presses the brake pedal while the motor is operating in the torque control mode, regenerative braking is performed to recover the braking and inertial energy of the vehicle through generation of power from the motor and braking of the vehicle is performed.

In order to implement the auto hold according to the first embodiment of the present invention, the control mode for the motor operation during braking of the vehicle is switched from the torque control mode to the speed control mode.

That is, with the braking by the brake pedal 26, the speed of the motor 14, which has completed power generation for regenerative braking, is sensed by the speed sensor 28, and the position of the accelerator pedal 30 is accelerated. As a result of sensing by the sensor 32, the detected value of detecting the rotational speed of the motor 14 is less than or equal to the threshold rotational speed, and the detected value of the accelerator position sensor sensing the position of the accelerator pedal 30 is less than or equal to the critical angle. In this case, the HCU 20 or the MCU 22 switches the control mode of the motor from the torque control mode to the speed control mode.

Therefore, after the control mode for the motor is switched to the speed control mode, the HCU 20 or the MCU 20 controls the speed of the motor 14 to be zero.

In this way, if the speed of the motor is controlled to be controlled, the speed of the motor is kept at zero even if the driver takes his foot off the brake pedal, so that the wheels of the vehicle coaxially connected with the motor do not move. An auto hold function is implemented to allow the driver to rest comfortably.

On the other hand, if the detected value of the accelerator position sensor 32 for detecting the position of the accelerator pedal 30 is greater than or equal to the threshold angle, the HCU 20 or MCU 22 that receives it is recognized as a restart of the vehicle and the motor The control mode of the vehicle is switched back to the torque control mode, whereby the vehicle starts running by the motor drive, that is, the vehicle runs by the electric vehicle (EV) mode.

Second embodiment

The autohold implementation method according to the second embodiment of the present invention is characterized by using a hydraulic brake control system, unlike the first embodiment.

The hydraulic brake control system for braking a hybrid or fuel cell vehicle is composed of a hydraulic brake braking device having a brake oil pump and a hydraulic brake control unit for controlling the brake.

Accordingly, as described above, the speed of the motor 14 is completed by the speed detecting sensor 28 and the position of the accelerator pedal 30 is sensed by the brake pedal 26, and the rotation speed of the motor 14 that has been developed for regenerative braking. Is detected by the accelerator position sensor 32, the detected value of detecting the rotational speed of the motor 14 is less than the threshold rotational speed, and the position of the accelerator position sensor 32 that sensed the position of the accelerator pedal 30 If the detected value is less than or equal to the threshold angle, the hydraulic brake braking unit 18 controls to continuously operate the brake oil pump 34.

Therefore, even when the driver releases the brake pedal, the brake oil pump 34 continuously operates to brake the wheels of the vehicle. Thus, the auto hold function is implemented to allow the driver to rest comfortably. It is done.

Similarly, if the detected value of the accelerator position sensor 32 that detects the position of the accelerator pedal 30 is greater than or equal to a critical angle, the HCU 20 or MCU 22 that receives the received recognition of the accelerator pedal 30 recognizes the restart of the vehicle and the motor. By executing the torque control mode for the vehicle, vehicle driving by the electric vehicle (EV) mode is restarted.

Third embodiment

The implementation method of the autohold according to the third embodiment of the present invention is characterized in that the motor and the hydraulic brake control system are used together in consideration of the amount of charge of the battery.

In the case of maintaining the braking force using the motor as in the above-described first embodiment, if the charging energy of the energy storage device (battery) is depleted, the motor itself cannot be driven, and thus, the implementation of the autohold function for maintaining the braking force is also achieved. Impossible cases may occur.

When the braking force is maintained by using the hydraulic brake system as in the above-described second embodiment, the electric oil pump of the hydraulic brake system must be continuously driven, which may cause a problem in reducing fuel consumption and noise.

In view of this, the autohold implementation method according to the third embodiment of the present invention has a braking torque for the motor and the hydraulic brake system in consideration of SOC (STATE OF CHARGE) of the energy storage and generation device. If the SOC is sufficient, use the motor to secure the braking force for the auto holder to prevent fuel consumption or noise, while if the SOC is low, use the hybrid brake system for the auto hold. It is characterized in that it is secured.

Herein, the autohold implementation method according to the third embodiment of the present invention will be described in detail.

As described above, the accelerator position sensor for detecting the position of the accelerator pedal 30 and the rotational speed of the motor 14 after the power generation for regenerative braking with braking by the brake pedal 26 is less than or equal to the threshold rotational speed If the detected value of 32 is less than or equal to the threshold angle, the control mode of the motor is switched from the torque control mode to the speed control mode in the HCU 20 or the MCU 22.

After the control mode for the motor is switched to the speed control mode, the HCU 20 or the MCU 22 is set to a state before controlling the speed of the motor to zero.

At this time, the total required braking torque (Ttb) required for braking is measured, and the amount of charge of the energy storage and generation device 10, that is, SOC is checked.

Therefore, according to the charge amount of the energy storage and generation device 10, that is, the SOC, the total required braking torque is Tm (motor torque) by a motor and braking torque (Tb) by a hydraulic brake system. torque).

That is, in the HCU 20 which is the main controller, the total demand braking torque Ttb is determined by the motor braking torque Tm = F (SOC) × Ttb and the braking torque Tb = (1-F). (SOC) x Ttb).

Accordingly, the speed of the motor is controlled to be zero according to the braking torque Tm of the motor, and the brake oil pump 34 is continuously operated to match the braking torque Tb of the hydraulic brake system. Through control, an autohold function according to the third embodiment is implemented.

In the embodiment of the autohold according to the first to the third embodiments as described above, the accelerator position sensor 32 for detecting the position of the accelerator pedal 30 and the speed sensor 28 for detecting the speed of the motor 14. Braking performance for the autoholding of the vehicle due to the sensing limit of the sensor and an error in the control process for implementing the autoholding based on the detected values by the accelerator position sensor 32 and the speed detecting sensor 28. There is a possibility of causing a decrease.

In order to prevent this possibility, in the real time setting of the control gain value of the motor controller (MCU or inverter), the detection information by the inclination angle sensor 36 of the vehicle is further added to the control process for implementing the auto hold. Thus, by controlling the dualization of the + /-driving direction of the motor, it is possible to implement a vehicle braking performance, that is, a more stable auto hold function.

That is, in case the vehicle is braked on a slope such as a hill road, the rotational drive of the motor is positive (+) until the rotation speed of the motor becomes zero based on the detected value of the inclination angle sensor 36. By controlling in the reverse (-) direction, the vehicle is not pushed even on the slope, and it is possible to maintain a stable auto hold state.

On the other hand, when the engine is still started when the hybrid vehicle is stopped, it is possible to implement the auto hold by the motor by separating the clutch between the engine and the motor and attaching the clutch between the motor and the wheel. desirable.

In addition, in order to implement the autohold of the present invention, when the state of charge of the energy storage device is not used (with low SOC) without using the hydraulic brake system, the motor driving mode and the braking performance by the motor A separate integrated starting generator (eg ISG) can be used to secure this.

That is, in a hybrid vehicle in which an engine and a motor are directly connected, the integrated starter generator (ISG) is mechanically connected to the engine, the wheels are mechanically connected to the engine, and the clutch between the engine and the motor is separated. In the state, the motor is driven by the energy secured through the integrated starting generator, and the braking performance for the autohold can be secured by controlling the rotation speed of the motor to be zero when braking.

1 is a block diagram illustrating a system configuration of a hybrid or fuel cell vehicle;

2 is a flowchart illustrating a first embodiment of an autoholding method of a hybrid fuel cell vehicle according to the present invention;

3 is a flowchart illustrating a second embodiment of an autoholding method of a hybrid fuel cell vehicle according to the present invention;

4 is a flowchart illustrating a third embodiment of an autoholding method of a hybrid fuel cell vehicle according to the present invention;

<Explanation of symbols for the main parts of the drawings>

10: energy generation and storage device 12: wheels

14 motor 16 inverter

18: hydraulic brake system 20: HCU

22: MCU 24: ECU

26: brake pedal 28: speed detection sensor

30: accelerator pedal 32: accelerator position sensor

34: brake oil pump 36: vehicle tilt angle sensor

Claims (4)

Pressing the brake pedal to perform braking; Sensing the rotational speed of the motor by a speed sensor and simultaneously detecting the position of the accelerator pedal; Switching the control mode of the motor from the torque control mode to the speed control mode if the rotational speed of the motor is equal to or less than a critical rotational speed and the position angle of the accelerator pedal is equal to or less than the critical angle; After the control mode for the motor is switched to the speed control mode, controlling the speed of the motor to zero to maintain the braking state of the vehicle; Autohold implementation method of a hybrid fuel cell vehicle comprising a. Pressing the brake pedal to perform braking; Sensing the rotational speed of the motor by a speed sensor and simultaneously detecting the position of the accelerator pedal; If the rotational speed of the motor is equal to or less than the critical rotational speed and the position angle of the accelerator pedal is equal to or less than the critical angle, continuously operating the brake oil pump under the control of the hydraulic brake braking unit; Continuously operating the brake oil pump to maintain a braking state of the vehicle; Autohold implementation method of a hybrid fuel cell vehicle comprising a. Pressing the brake pedal to perform braking; Sensing the rotational speed of the motor by a speed sensor and simultaneously detecting the position of the accelerator pedal; Switching the control mode of the motor from the torque control mode to the speed control mode if the rotational speed of the motor is equal to or less than a critical rotational speed and the position angle of the accelerator pedal is equal to or less than the critical angle; Determining the SOC of the energy storage device while measuring the total required braking torque required for braking; In accordance with the SOC of the energy storage device, the total demand braking torque is divided into a braking torque by a motor and a braking torque by a hydraulic brake system; Controlling the speed of the motor to be zero according to the braking torque of the motor and operating the brake oil pump according to the braking torque of the hydraulic brake system; Autohold implementation method of a hybrid fuel cell vehicle comprising a. The method according to any one of claims 1 to 3, When the detected value of the accelerator position sensor for detecting the position of the accelerator pedal is greater than or equal to the critical angle, the auto hold of the hybrid fuel cell vehicle is characterized in that the control mode of the motor is switched back to the torque control mode to restart the vehicle. Way.

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