Development of the Active Sound Generation Technology Using Motor Driven Power Steering System

As the original engine sound is usually not enough to satisfy the driver’s desire for a sporty and fascinating sound, Active Noise Control (ANC) and Active Sound Design (ASD) have been great technologies in automobiles for a long time. However, these technologies which enhance the sound of vehicles using loud speakers or electromagnetic actuators etc. lead to the increase of cost and weight due to the use of external amplifiers or actuators. This paper presents a new technology for generating a target sound by the active control of a permanent magnet synchronous motor (PMSM) of a mass-production steering system. The existing steering hardware or motor is not changed, but only additional software is added. Firstly, an algorithm of this technology, called Active Sound Generation (ASG), is introduced which is compiled and included in the ECU target code. Then the high frequency noise issue and its countermeasures are presented. Afterwards, an ASG test bench is designed using a motor driven power steering (MDPS) system and the influence of ASG on the original function or steering feel of MDPS is investigated. Thirdly, the transfer path of motor-induced vibration is measured and then the level of steering wheel vibration is presented in the view of human perception. Finally, various target sounds are implemented in this ASG system. From the results, it is verified that ASG is a useful way to reproduce a target signal in a vehicle without adding actuators. So it is expected to be an alternative way to the ASD method based on speakers or additional vibration actuators in the future.