Intelligent Rotor Assembly Enabling Positive Balancing Concepts for High-Performance Permanent Magnet Rotors

The increasing electrification of vehicles poses new challenges to the automotive industry. Especially in highperformance applications, the drive system is designed for high rotational speeds, best dynamic behaviour and optimal power-to-weight ratio. However, most rotor designs for drivetrain application are commonly designed for negative balancing. In that case, balancing discs are used to enable the subtraction of a small amount of mass, thus balancing the rotor. The excessive mass of the balancing discs must cover all production deviations and leads to massive balancing discs with a weight ratio of up to 10% for the overall rotor system. In order to reduce the weight and the installation space for permanent magnet rotors, this article presents an approach that allows to avoid excessive masses by using a rotor components arrangement with minimized unbalance followed by a positive balancing process. In preliminary investigations, the initial rotor unbalance occurring in a state-of-the-art assembly process was therefore significantly reduced by using an optimized selective assembly. Based on researched state-of-the-art positive balancing concepts, new positive balancing concepts are systematically developed, tested and evaluated for applicability in high-performing motors. It shows that the required balancing quality in high-performance applications (usually