Kang, H., Chung, T., Lee, H., and Ihm, H., "Active Booming Noise Control for Hybrid Vehicles," SAE Int. J. Passeng. Cars - Mech. Syst. 9(1):167-173, 2016, doi:10.4271/2016-01-1122.
Pressure variation during engine combustion generates torque fluctuation that is delivered through the driveline. Torque fluctuation delivered to the tire shakes the vehicle body and causes the body components to vibrate, resulting in booming noise. HKMC (Hyundai Kia Motor Company)’s TMED (Transmission Mounted Electric Device) type generates booming noises due to increased weight from the addition of customized hybrid parts and the absence of a torque converter. Some of the improvements needed to overcome this weakness include reducing the torsion-damper stiffness, adding dynamic dampers, and moving the operation point of the engine from the optimized point. These modifications have some potential negative impacts such as increased cost and sacrificed fuel economy. Here, we introduce a method of reducing lock-up booming noise in an HEV at low engine speed. Generating a torque profile via the propulsion motor, which has the anti-phase profile of the driveline vibration, can therefore suppress driveline fluctuation. Engine vibration extracted from the HSG (Hybrid Starter Generator) is used for the desired input signal. The generated signal, based upon the rotation angle of the driving motor, is used as a reference input for the RLS adaptive filter. The filter updates its coefficients to minimize the phase difference between the reference signal and the desired input signal. Frequency response characteristics of the powertrain driveline components are used to generate the anti-phase vibration profile of the point causing booming. Effectiveness was verified with development vehicles under various driving conditions. The results show an 8dB(C) improvement in booming noise, and 9dB and 4dB improvements in floor panel vibration and steering wheel vibration, respectively.