Identification of NVH Characteristics of Air Compressor for Fuel Cell Electric Vehicles

This paper evaluates the NVH characteristics of an air compressor for fuel cell electric vehicles(FCEVs) by conducting experimental as well as on-road tests. For the experiment, five eddy-current-type displacement sensors measured the vibration amplitudes of the shaft at the impeller and thrust runner ends, one three-axis accelerometer measured the acceleration of the compressor housing, and one microphone placed 1 m away from the test air compressor measured the acoustic pressure during rotor speed-up and coastdown up to 100 k r/min. For the on-road test, the air compressor was installed under the stack frame of a proto-type FCEV. The stack frame supports a fuel cell stack and is fixed on the sub-frame of the FCEV. In addition to five eddy-current-type displacement sensors and one three-axis accelerometer installed in the air compressor housing, two three-axis accelerometers installed on the stack frame and the sub-frame measured their accelerations during FCEV speed-up and break-down up to 115 km/h. One microphone installed 30 cm behind the air compressor recorded the acoustic pressure. All measured displacements, accelerations, and acoustic pressures were analyzed in the frequency domain. The test results revealed that the air compressor has the highest rotor vibrational amplitude and housing acceleration at the maximum rotor speed of 100 k r/min. However, the vibrations of the air compressor are well dampened while transmitteed to the sub-frame of the FCEV.