QC/T 1089-2017Requirements and test methods for regenerative braking system in electric vehicles (English PDF)

1 Scope

This standard specifies the scope, terms and definitions, symbols, requirements, test methods, processing of test results for the test of regenerative braking system in electric vehicles.

This standard applies to pure electric passenger vehicles which use the rechargeable energy storage systems as power storage batteries. Pure electric commercial vehicles may be implemented with reference to this standard.

2 Normative references

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.

GB/T 18386 Electric vehicles - Energy consumption and range - Test procedures

GB/T 19596 Terminology of electric vehicles

GB 7258 Safety specifications for power-driven vehicles operating on roads

GB 21670 Technical requirements and testing methods for passenger car braking systems

GB 18352 Limits and measurement methods for emissions of pollutants from light-duty vehicles

3 Terms and definitions

The terms and definitions as defined in GB/T 19596 as well as the following terms and definitions apply to this standard.

4 Symbols

The following symbols apply to this standard.

E1: Recovered braking energy (kW · h).

E2: Theoretical maximum braking energy (kW · h).

eta: Braking energy recovery efficiency.

D1: The driving range of the electric vehicle when the brake energy recovery function is turned on (km).

D2: The driving range of the electric vehicle when the brake energy recovery function is turned off (km).

P1: Brake energy recovery range contribution rate.

I: The current as fed back from the braking energy recovery system to the busbar of the rechargeable energy storage system (A).

U: Voltage across the rechargeable energy storage system (V).

E3: The reduction of kinetic energy during deceleration of the vehicle (kW · h).

V: Vehicle's speed during deceleration of the vehicle (km/h).

A, B, C: Vehicle's taxi coefficient.

m: Vehicle's reference mass (kg).

V1, V2: The speed of the vehicle during deceleration, wherein V1 is the speed of the previous moment and V2 is the speed of the latter moment, and V1 > V2, in the unit of km/h.

5 General requirements

Appendix A (Normative) Test methods for brake safety of regenerative braking system in electric vehicle

A.1 Test vehicle, site, running-in, etc. shall be in accordance with the requirements of test method 7 of GB 21670.

A.2 Follow the requirements of clause 7 in the test method of GB 21670 to carry out test.

A.3 Test of the stability of the braking efficiency of the rechargeable energy storage system in vehicle under different SOC conditions. The selected vehicles are tested in the following three states:

a) The vehicle is fully charged or the SOC is above 95%;

b) The vehicle discharges and finishes 1/3 constant speed driving range;

c) The vehicle discharges and finishes 2/3 constant speed driving range.

A.3.1 The vehicle is unloaded. The initial braking speed as specified in this test is 80% of the maximum vehicle speed; it shall not exceed 160 km/h. During the test, first confirm that the average temperature of the service brake on the axle which has the highest temperature is within 65 °C ~ 100 °C. On a level road which has good adhesion coefficient, accelerate the vehicle to the test speed of 5 km/h or more. When the vehicle's speed decreases to the speed as specified in the test, apply the service brake.

A.3.2 For vehicles whose electric drive train cannot be disengaged from the wheel, the test is carried out under the conditions of engagement of electric drive train.

A.3.3 During the braking of the vehicle from the specified initial speed to 10 km/h, the wheel shall not be locked. Record the braking distance S1.

A.3.4 According to the test results, calculate the mean fully developed braking deceleration (MFDD1) of vehicle.

A.3.5 Turn on the braking energy recovery function. Repeat A.3.1 ~ A.3.3. According to the test results, calculate the MFDD under these three conditions as well as its standard deviation S and mean value.

Appendix B (Normative) Test method for braking energy recovery efficiency of regenerative braking system in electric vehicle

B.1 Test vehicles, sites, running-in requirements shall be in accordance with the requirements as specified in GB/T 18386.

B.2 This test is divided into constant-speed test and working condition test. Firstly, follow the requirements of B.3 to carry out the constant-speed test, mainly to verify the turn-on/off state of the braking energy recovery system. When the test result is confirmed to be effective, follow the requirements of B.4 to carry out the working condition test.