GB/T 45417-2025Guidelines for defect analysis of vehicle regenerative braking function (English PDF)

3.1 Regenerative braking function

The function of converting vehicle kinetic energy into electrical energy during processes such as coasting, deceleration, or downhill driving.

3.2 Regenerative braking system

Hardware and software systems for implementing regenerative braking function.

3.2.1 Regenerative braking system of category A

A regenerative braking system that does not belong to the service braking system.

[Source. GB 21670-2008, 3.1.16.2, modified]

3.2.2 Regenerative braking system of category B

The regenerative braking system that belongs to the service braking system.

[Source. GB 21670-2008, 3.1.16.3, modified]

3.3 Defect

The common occurrence of situations in the same batch, model, or category of automotive products that do not comply with national or industry standards for safeguarding personal and property safety, or other unreasonable dangers that endanger personal and property safety.

[Source. GB/T 43387-2023, 3.1, modified]

3.4 Defect clue

Information about possible defects in the product.

NOTE. Including accident investigation, consumer complaints, online public opinion, and overseas recall information.

[Source. GB/T 43387-2023, 5.3, modified]

3.5 Defect analysis

Technical analysis activities conducted by producers, recall authorities, or recall technical institutions on the presence of defects in products.

3.6 Risk assessment

The process of determining the comprehensive level of severity and likelihood of occurrence of a hazardous event or situation.

[Source. GB/T 43387-2023, 5.13]

6.1 Analysis of defect clue characteristics

Conduct defect clue feature analysis based on the defect clues collected in Chapter 5. The analysis mainly includes.

a) Vehicle characteristics, such as vehicle type, usage mode, regenerative braking type, regenerative braking intensity, vehicle braking control software version, etc.;

b) Scene features, such as traffic conditions, road environment conditions, weather conditions, etc.;

c) Driver characteristics, such as driving experience, driver age, etc.

6.2 Characteristic analysis of regenerative braking function

Analyze the characteristics of regenerative braking function for vehicle regenerative braking system. The analysis mainly includes.

a) Control mode, default state, actual state distribution, adjustment method, reminder situation, vehicle speed correlation logic, relationship with charge state, and relationship with service braking strategy of regenerative braking function;

b) Hardware information and control strategies related to regenerative braking function, such as vehicle controller, drive motor and controller, battery state of charge, accelerator pedal status, brake pedal status, etc.

6.3 Association analysis

Compare and analyze the correlation between the comprehensive defect clue characteristics and the regenerative braking function characteristics. The analysis methods mainly include. big data analysis, expert analysis, accident scene reproduction, closed road testing, driving simulator testing, virtual simulation testing, etc.

If there is a correlation between the defect clue characteristics and the regenerative braking function characteristics, such as a high accident rate in a specific regenerative braking function mode or a high accident rate in a specific scenario, it is advisable to conduct risk assessment work according to Chapter 7.If there is no correlation, the analysis should be terminated.

7.1 Overview

Risk assessment is an important component of the analysis of defects in regenerative braking function. This mainly includes identifying hazardous events or situations, analyzing the severity of hazardous events or situations, conducting likelihood analysis, and forming a comprehensive risk level rating. Based on the comprehensive risk level rating results, further defect determination can be carried out.

7.2 Identification of hazardous events or situations

According to vehicle malfunctions and accident manifestations, the main hazardous events or situations caused by the regenerative braking function of the vehicle and their analysis methods are shown in Table 1.Other possible hazardous events or situations can also be comprehensively analyzed through on-board data, images, experimental reproduction, and expert demonstration.

When conducting analysis, the main hazardous events or situations can be identified among multiple hazardous events or situations. Conduct risk assessments for major hazardous events or situations. If it is difficult to distinguish between primary and secondary dangerous events or situations, any danger can be set first. The event or situation is a major hazardous event or situation, and a risk assessment is conducted for it.

Table 1 -- Main hazardous events or situations and their analysis methods Dangerous events or situations Due to design, manufacturing, and other reasons Analysis methods Applicable types of regenerative braking systems analysis results. Revise the preliminary assessment of severity.

NOTE. The accident scenario includes the accident environment, road characteristics, weather, etc.

7.4 Probability analysis of hazardous events or situations

7.4.1 Probability level of hazardous events or situations

The possibility of hazardous events or situations caused by regenerative braking function includes five levels. high, comparatively high, medium, comparatively low, and low. The evaluation process includes two parts. preliminary assessment of possibilities and revision of results.

7.4.2 Preliminary assessment of possibility

It is advisable to consider the type of regenerative braking system and the possible causes of hazardous events or situations according to the analysis methods listed in Table 1.Conduct preliminary probability analysis for different hazardous events or situations. The preliminary evaluation principles are as follows.

a) If the scenarios where dangerous events or situations occur are common, it is believed through experimental reproduction or analysis that there are common problems with the software or hardware system, and the preliminary assessment of the possibility is high or comparatively high;

b) If it is impossible or difficult to reproduce a hazardous event or situation through experimentation, but it is believed through analysis and demonstration that it may occur, the preliminary assessment of the possibility may be comparatively high or medium;

c) If it is impossible or difficult to reproduce a hazardous event or situation through experimentation, and the scenario where the hazardous event or situation is considered extreme through analysis and argumentation, the preliminary assessment of the possibility may be comparatively low or low.

7.4.3 Possible result correction

If the vehicle has effective fault or accident warning measures, the likelihood assessment results can be appropriately reduced. If the vehicle has effective accident mitigation measures, the likelihood assessment results can be appropriately reduced.

In addition to the above correction factors, analysis can also be conducted by comprehensively considering factors such as vehicle handling mode, usage rate of different modes, accident scenarios, and test analysis results to revise the preliminary assessment results of the possibility. ......