A control method for single-pedal mode of electric vehicle meeting functional safety

Abstract

The present invention discloses a control method for a single-pedal mode of an electric vehicle that meets functional safety, comprising the following steps: S1, a user turns on or off the single-pedal mode and selects different levels of energy recovery intensity through a control panel; S2, a vehicle VCU performs risk avoidance and risk degradation when the vehicle is running in the single-pedal mode according to a preset functional safety concept in the single-pedal mode. The present invention improves the driving safety of the vehicle in the single-pedal mode.

Description

Technical Field

[0001] The invention relates to a single-pedal control method for an electric vehicle, and in particular to a control method for a single-pedal mode of an electric vehicle that meets functional safety requirements. Background Art

[0002] During the general vehicle braking process, the brakes will generate huge friction, causing kinetic energy to be converted into resistance heat energy and wasted in the air. Electric vehicles can convert this kinetic energy wasted due to braking into electrical energy through brake energy recovery technology and store it in the power battery again, thereby increasing the driving range. The single-pedal mode of electric vehicles only requires one power pedal to complete the acceleration and deceleration process, improving the driving comfort in congested urban road conditions. However, the single-pedal control strategy in the existing technology often cannot meet the driving safety requirements. Summary of the invention

[0003] The object of the present invention is to provide a control method for a single-pedal mode of an electric vehicle that meets functional safety requirements, so as to solve the safety problem of driving in the single-pedal mode.

[0004] In order to solve the above technical problems, the present invention provides a technical solution: a control method for a single-pedal mode of an electric vehicle that meets functional safety, comprising the following steps:

[0005] S1. The user turns on or off the single pedal mode and selects different levels of energy recovery intensity through the control panel;

[0006] S2. The vehicle VCU performs risk avoidance and risk degradation when the vehicle is operating in the single-pedal mode according to the preset functional safety concept in the single-pedal mode;

[0007] Among them, the functional safety concept is obtained by conducting functional safety analysis on different hazardous events based on functional safety standards; hazardous events include unexpected acceleration and unexpected deceleration in driving state, and lack of braking force and unexpected deceleration in braking state;

[0008] The functional safety analysis process is as follows: first, the fault tree analysis method is used to obtain the fault causes corresponding to different hazardous events; then, the HARA is used to analyze the SEC value of each hazardous event. The SEC value includes severity, exposure, and controllability; the SEC value is looked up in the table according to the functional safety standard to obtain the ASIL level, and the ASIL level is assigned to the corresponding safety goal to obtain the safety status of each hazardous event. The safety status of each hazardous event is integrated to obtain the functional safety requirements, and the controller communication signal is configured according to the functional safety requirements to obtain the technical safety requirements.

[0009] According to the above scheme, when the single-pedal mode is turned on, if the driver steps on the brake pedal, the deceleration will increase.

[0010] According to the above scheme, when the single-pedal mode is turned on, if the driver presses the accelerator pedal and the brake pedal at the same time, the braking request will be met first.

[0011] According to the above scheme, when it is detected that the accelerator pedal reaches the maximum opening within x seconds, the vehicle protection mode is turned on. First, the kinetic energy is stored in the power battery without outputting the acceleration torque. Then, an acceleration warning is given on the control panel. If the accelerator pedal remains at the maximum opening for y seconds, the vehicle protection mode is exited and full throttle acceleration is performed; wherein x and y are preset calibration values.

[0012] According to the above scheme, x=1, y=3.

[0013] According to the above scheme, when the front radar detects that the distance between the vehicle and the vehicle in front is less than a certain value and the vehicle does not slow down, the assisted driving mode is entered and braking is performed.

[0014] According to the above scheme, for unexpected acceleration when the vehicle is in the single-pedal driving mode, the VCU performs risk avoidance and risk degradation processes as follows:

[0015] Detect faulty accelerator pedal sensors to avoid excessive positive torque caused by incorrect processing of accelerator pedal sensing values ​​and excessive positive torque caused by incorrect processing of wheel-side torque.

[0016] According to the above scheme, for unexpected deceleration when the vehicle is in the single-pedal mode, the VCU performs risk avoidance and risk degradation processes as follows:

[0017] Detect faulty accelerator pedal sensors to avoid excessive negative torque caused by incorrect processing of accelerator pedal sensing values ​​and excessive negative torque caused by incorrect wheel-side torque.

[0018] According to the above scheme, in response to the lack of braking force when the vehicle is in the braking state of the single-pedal mode, the VCU performs risk avoidance and risk degradation processes to avoid excessive braking torque caused by incorrect handling of the braking torque request.

[0019] According to the above scheme, in response to unexpected deceleration that occurs when the vehicle is in the single-pedal mode braking state, the VCU performs risk avoidance and risk degradation processes to avoid no braking torque or insufficient braking torque caused by erroneous processing of braking energy recovery requests and erroneous processing of operating modes.

[0020] The beneficial effects of the present invention are: obtaining the functional safety concept of the vehicle under various hazardous events through functional safety analysis, and performing risk avoidance and risk downgrading for hazardous events based on the functional safety concept, thereby improving driving safety in single-pedal mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of functional safety requirements in a single-pedal mode according to an embodiment of the present invention;

[0022] Figure 2 A braking system for a single-pedal mode according to an embodiment of the present invention;

[0023] Figure 3 A schematic diagram of a fault tree analysis method for unexpected acceleration of a vehicle during driving according to an embodiment of the present invention;

[0024] Figure 4 A schematic diagram of a fault tree analysis method for unexpected vehicle deceleration during driving according to an embodiment of the present invention;

[0025] Figure 5 A schematic diagram of a fault tree analysis method for a vehicle's braking force loss during braking according to an embodiment of the present invention;

[0026] Figure 6 FIG. 1 is a schematic diagram of a fault tree analysis method for unexpected deceleration of a vehicle during braking according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0028] A control method for a single-pedal mode of an electric vehicle that meets functional safety requirements comprises the following steps:

[0029] S1. The user turns on or off the single pedal mode and selects different levels of energy recovery intensity through the control panel;

[0030] S2. The vehicle VCU performs risk avoidance and risk degradation when the vehicle is operating in the single-pedal mode according to the preset functional safety concept in the single-pedal mode;

[0031] Among them, the functional safety concept is obtained by conducting functional safety analysis on different hazardous events based on the functional safety standard GB / T 34590-2017; hazardous events include unexpected acceleration and unexpected deceleration in the driving state, and the lack of braking force and unexpected deceleration in the braking state;

[0032] The functional safety analysis process is as follows: first, the fault tree analysis method is used to obtain the fault causes corresponding to different hazardous events; then the HARA is used to analyze the SEC value of each hazardous event. The SEC value includes severity, exposure, and controllability; the SEC value is looked up in the table according to the functional safety standard to obtain the ASIL level, and the safety status of each hazardous event is obtained by assigning the ASIL level to the corresponding safety goal. The functional safety requirements are obtained by integrating the safety status of each hazardous event. Figure 1 ; Configure the controller communication signal according to the functional safety requirements to obtain the technical safety requirements; the fault tree analysis diagram for different hazard events can be found in Figure 3 to Figure 6 .

[0033] Furthermore, when the single-pedal mode is on, if the driver steps on the brake pedal, the deceleration increases.

[0034] Furthermore, when the single-pedal mode is on, if the driver presses the accelerator pedal and the brake pedal at the same time, the braking request will be given priority.

[0035] Furthermore, when it is detected that the accelerator pedal reaches the maximum opening within 1 second, the vehicle protection mode is turned on. First, the kinetic energy is stored in the power battery without outputting the acceleration torque. Then, an acceleration warning is given on the control panel. If the accelerator pedal is maintained at the maximum opening for 3 seconds, the vehicle protection mode is exited and full throttle acceleration is performed.

[0036] Furthermore, when the front radar detects that the distance between the vehicle and the vehicle in front is less than a certain value and the vehicle does not slow down, the assisted driving mode is entered and braking is performed.

[0037] Furthermore, for unexpected acceleration when the vehicle is in the single-pedal driving mode, the VCU performs risk avoidance and risk degradation processes as follows:

[0038] Detect faulty accelerator pedal sensors to avoid excessive positive torque caused by incorrect processing of accelerator pedal sensing values ​​and excessive positive torque caused by incorrect processing of wheel-side torque.

[0039] Furthermore, for unexpected deceleration when the vehicle is in the single-pedal driving mode, the VCU performs risk avoidance and risk degradation processes as follows:

[0040] Detect faulty accelerator pedal sensors to avoid excessive negative torque caused by incorrect processing of accelerator pedal sensing values ​​and excessive negative torque caused by incorrect wheel-side torque.

[0041] Furthermore, in response to the lack of braking force when the vehicle is in the braking state of the single-pedal mode, the VCU performs risk avoidance and risk degradation processes to avoid excessive braking torque caused by incorrect processing of the braking torque request.

[0042] Furthermore, in response to unexpected deceleration that occurs when the vehicle is in the braking state of single-pedal mode, the VCU performs risk avoidance and risk degradation processes to avoid no braking torque or insufficient braking torque caused by erroneous processing of braking energy recovery requests and erroneous processing of operating modes.

[0043] See also Figure 2 , a braking system for a single-pedal mode, comprising a VCU, a series braking module, and a parallel braking module, wherein the series braking module comprises a first braking control module, a vehicle control module, and a first brake light control module electrically connected in sequence, and the first braking module is electrically connected to the VCU; the parallel braking module comprises a second braking control module and a second brake light control module, and the second braking control module and the second brake light control module are both electrically connected to the VCU;

[0044] The first brake control module receives the total brake torque command sent by the VCU, returns the electric brake torque request to the VCU, and transmits the brake light switch signal to the first brake light control module through the vehicle control module; the second control module receives the mechanical brake deceleration request sent by the VCU, and returns the brake deceleration feedback to the VCU; the second brake light switch receives the brake light switch signal sent by the VCU.

[0045] The above system avoids safety hazards caused by hardware failure and control software vulnerabilities, and achieves functional safety in single-pedal mode.

[0046] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A control method for a single-pedal mode of an electric vehicle that meets functional safety, characterized in that: The following steps are included: S1. The user turns on or off the single pedal mode and selects different levels of energy recovery intensity through the control panel; S2. The vehicle VCU performs risk avoidance and risk degradation when the vehicle is operating in the single-pedal mode according to the preset functional safety concept in the single-pedal mode; Among them, the functional safety concept is obtained by conducting functional safety analysis on different hazardous events based on functional safety standards; hazardous events include unexpected acceleration and unexpected deceleration in driving state, and lack of braking force and unexpected deceleration in braking state; The functional safety analysis process is as follows: first, the fault tree analysis method is used to obtain the fault causes corresponding to different hazardous events; then, the HARA is used to analyze the SEC value of each hazardous event, which includes severity, exposure, and controllability; the SEC value is looked up in the table according to the functional safety standard to obtain the ASIL level, and the ASIL level is assigned to the corresponding safety goal to obtain the safety status of each hazardous event. The safety status of each hazardous event is integrated to obtain the functional safety requirements, and the controller communication signal is configured according to the functional safety requirements to obtain the technical safety requirements; When it is detected that the accelerator pedal reaches the maximum opening within x seconds, the vehicle protection mode is activated. First, kinetic energy is stored in the power battery without outputting acceleration torque. Then, an acceleration warning is given on the control panel. If the accelerator pedal remains at the maximum opening for y seconds, the vehicle protection mode is exited and full throttle acceleration is performed; x and y are preset calibration values.

2. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: When one-pedal mode is on, deceleration increases when the driver steps on the brake pedal.

3. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: When the single-pedal mode is on, if the driver presses the accelerator pedal and the brake pedal at the same time, the braking request will be given priority.

4. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: x=1, y=3.

5. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: When the front radar detects that the distance between the vehicle and the vehicle in front is less than a certain value and the vehicle is not slowing down, the assisted driving mode is entered and braking is performed.

6. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: In response to unexpected acceleration when the vehicle is in single-pedal mode, the VCU performs risk avoidance and risk degradation as follows: Detect faulty accelerator pedal sensors to avoid excessive positive torque caused by incorrect processing of accelerator pedal sensing values ​​and excessive positive torque caused by incorrect processing of wheel-side torque.

7. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: In response to unexpected deceleration when the vehicle is in single-pedal mode, the VCU performs risk avoidance and risk degradation as follows: Detect faulty accelerator pedal sensors to avoid excessive negative torque caused by incorrect processing of accelerator pedal sensing values ​​and excessive negative torque caused by incorrect wheel-side torque.

8. The control method of the electric vehicle single-pedal mode meeting functional safety according to claim 1, characterized in that: In response to the lack of braking force when the vehicle is in the braking state of single-pedal mode, the VCU performs risk avoidance and risk degradation processes to avoid excessive braking torque caused by incorrect handling of braking torque requests.

9. The control method of the electric vehicle single pedal mode meeting functional safety according to claim 1, characterized in that: In response to unexpected deceleration when the vehicle is in the braking state of single-pedal mode, the VCU performs risk avoidance and risk degradation processes to avoid no braking torque or insufficient braking torque caused by erroneous processing of braking energy recovery requests and erroneous processing of operating modes.

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