With the advent of PHEV vehicles OEMs face additional NVH issues. A particularly new issue is a low frequency booming noise caused during charging of batteries using the internal combustion engine. During charging the engine is operated at low rotational speeds and high loads, leading to pronounced low frequency noise. While in the past reducing low frequency noise either required large absorbers and/or heavy dampers, today the issue can be tackled by use of an Active Noise Cancellation system.
Jaguar Land Rover decided to introduce an Active Noise Cancellation system in the PHEV variants of some of their vehicles. The system builds upon software by Müller-BBM Active Sound Technology GmbH and makes use of the existing audio amplifiers. The only extra hardware component required are microphones in the vehicle headliner.
Overall the ANC system only adds minimum weight to the vehicle but allows for noise reduction in excess of 10 dB at frequencies below 40 Hz during charge sustain idle operation. In addition, the system enabled JLR to cancel noise at other operating conditions, allowing several mass-dampers to be removed, offering weight opportunities of around 5 kg. This contribution will show how the system is designed, and it will give an idea on the ANC system performance in different operating conditions.