Active Noise Cancellation with electric drives

Besides comfort functions, acoustic perception in vehicles, especially in the premium segment, is very important for the well-being of the driver and passengers. Tonal disturbing noises from the tires at a specific speed or functional sounds of electric drives that appear when running the electric window lifter can be very annoying for the passengers and can lead to expensive customer complaints for the manufacturer.

Active Noise Cancellation is an efficient solution to this problem. The disturbing noise is detected by sensors, e.g. a microphone in the passenger compartment or a acceleration sensor at a specific point on the vehicle structure. An acoustic source emits inversely phased waves that minimize the disturbing noise. The special feature of the system developed here is that the acoustic source cancelling the disturbing noise is an electric motor that is already present in the car, e.g. the electric drive of the sunroof, the power steering or the window lifter. The motor can be controlled in a way that it emits specific acoustic waves independently of its actual drive function and reduces the disturbing noise at the sensor location. The advantage of this system is that no additional loudspeakers or ECUs have to be assembled in the car, which reduces space, weight and costs.

In addition to the actual cancellation of the disturbing noise, which works very well in first tests on test benches and in the vehicle, further measures have to be taken that are dealt with in this project. So the transmission behaviour of the motor itself and the vehicle structure must be determined, an optimum location of the sensor for cancellation of the disturbing noise must be found and the parameters must be adapted automatically over the whole lifetime of the vehicle. The aim of this project is to have parameterizable algorithms implemented in a demonstrator that can be adapted quickly for each application.