Optimization of Magnetic Planetary gear Topology to avoid auto slip during various torque requirements for passenger car application.

Authors: Gowtham Raj R, Kiran Rao Mercedes-Benz Research and Development India Private Limited Key Words: Transmission, Magnetic planetary gears (MPG), PM Machine, MATLAB Simulation, Magnetic field Abstract: The automotive industry recently has started implementing magnetic gear in different types as alternative design for transmission system, one such design being Magnetic planetary gear permanent magnet (MPG-PM) machine. The current methodology and the relevant formulas helps to design magnetic planetary gear system, which does not have design considerations for permanent magnet machine and influence of magnetic field. The influence of design characteristics of PM machine, Magnetic field and its material plays a vital role in designing the MPG-PM for electric vehicle applications. A method of optimizing the Gear topology design parameters of a magnetic planetary gear permanent magnet machine (MPG-PM machine) is proposed. The Analytical calculations regarding the design parameters proposed in relation to power, gear ratios, and other design constraints like packaging parameters i.e. outer diameter, the overall length of the machine. The analytical calculation further optimized based on the required torque density in the MPG part and Power generation in the PM motor part by varying magnetic strength on the inner and outer sides of ring gear. The analytical method also considers different materials for Ring gear, sun gear and planet gear in order to vary the magnetic flux through the ring gear to create different degrees of isolations between MPG and PM sections of the machine and to ensure the structural integrity of all the components. The study focuses on evaluating Design parameters with consideration of effect of PM characteristics Comparison analysis performed with proposed method and existing method as: 1. Magnetic field vs axis of magnet vs Torque capacity (Ring gear) 2. Torque capacity of MPG Ring gear Vs No of planet gears 3. Slip angle vs no of magnet. 4. Torque capacity vs number of pole pairs in planet gear Conclusion: 1. Characteristics of PM is included in base MPG system and Several theories are compared and discussed 2. The studies shows the significant increase in torque capacity (nearly 18%-27%) by introducing the effect of magnetic field in design considerations. 3. The effect of Power density analyzed with respect to various materials in consideration of characteristics of permanent motor.