QC/T 1132-2020Noise measurement methods for electric powertrains of electric vehicles (English PDF)

4.4 Measuring instrument

4.4.1 Acoustic instrument systems, including microphones and cables, shall meet the requirements of Level 1 in GB/T 3785.1-2010.

4.4.2 The filter shall meet the requirements of Level 1 in GB/T 3241-2010.

4.4.3 Before and after each series of measurements, it shall use an acoustic calibrator, that meets the requirements of level 1 in GB/T 15173-2010, to verify the entire measurement system, at one or more frequencies within the measurement frequency range. For the difference between the readings, which are obtained by calibration before and after each series of measurement, it shall not be more than 0.5 dB.

5.1 Test object

Refer to Appendix A for the typical structure of the electric power train system, which is applicable to this document.

5.2 Installation conditions

5.2.1 Electric power train system

5.2.1.1 It is recommended to use the original vehicle suspension system and drive shaft. The installation posture shall meet the design requirements.

5.2.1.2 For the connection between the drive shaft and the load dynamometer, it shall have at least one set of elastic coupling, which has vibration isolation function.

5.2.1.3 For the installation of the motor controller, it is described as follows:

a) For the drive motor system, where the motor controller and the motor are integrated, the motor controller is regarded as a part of the motor; the motor controller and the motor are installed, according to actual matching conditions;

b) For a drive motor system, where the motor controller and the motor can be separated, the motor controller shall be kept away from the motor, AND acoustic treatment shall be performed on it, so that it does not affect the noise test results of the motor itself. It runs under the peak torque, peak power, continuous torque, continuous power conditions, of the electric and power generation states. The test power supply shall meet the design requirements of the device under test.

6.2.2 Drive motor system and motor controller

6.2.2.1 The cooling shall meet the design requirements.

6.2.2.2 The operating conditions shall be implemented in accordance with the requirements of 6.2.1.2 ~ 6.2.1.5.

6.3 Determination of measurement environment and measurement surface

6.3.1 Electric power train system

The measurement environment and measurement surface of the sound power level of the electric power train system shall meet the requirements of Table 1.

Note: The descriptions of a) and b) in 5.2.1.3 apply to Table 1.

6.3.2 Drive motor system

The measurement environment and measurement surface of the sound power level of the drive motor system shall meet the requirements of Table 2.

Note: The descriptions of a) and b) in 5.2.1.3 apply to Table 2.

6.3.3 Motor controller

The sound power level of the motor controller shall be measured using the method in Table 3.

Where:

Lpi - The sound pressure level of the ith microphone position. n - The number of microphone positions.

8.1 Background noise correction

According to requirements of Chapter 6 and Chapter 7, measure the background noise, when the sound source is not working. The average sound pressure level of the background noise is L''. The average sound pressure level, which is measured when the sound source is running, is L'. Background noise correction value K1 (A weighting or frequency band) is calculated by formula (2), in the unit of dB:

Where: When deltaL >= 15 dB, no correction is needed.

When 6 dB <= deltaL< 15 dB, it shall be corrected according to formula (2). When the measurement is invalid on a single frequency band, if deltaL > 6 dB, the A weighting value is valid, where deltaL = L'A - L''A.

When deltaL < 6 dB, it does not meet the requirements of this standard. The accuracy of the measurement result is reduced. However, it can still be corrected according to formula (2). The result is regarded as the upper limit of the noise source of the measured sound source. It is explained in the text of the report and the result icon.

8.2 Correction of environmental noise

Environmental correction K2 (A weighting or frequency band) is measured, according to one of the methods, which are given in Appendix A of GB/T 3767-2016. If K2 <= 4 dB, the environment meets the requirements.