Specifications and Design of a PM Electric Variable Transmission for Toyota Prius II

This paper focuses on an analysis of technical requirements for the design of a permanent magnet type electric variable transmission (PM-EVT), which is a novel series-parallel hybrid electric vehicle (HEV) powertrain concept. Similar to the planetary gear train used in the Toyota Prius II, the EVT also realizes the power split function. However, it is implemented in an electromagnetic way rather than in a mechanical way, as is the case for the Prius II with a planetary gear. In this paper, a procedure to define the technical requirements of an EVT is presented. Since the Toyota Prius II is a well-known series-parallel HEV, this vehicle is chosen as a reference. The engine, the battery and other necessary components are kept as input data. A dynamic simulation was performed in order to take into account different driving cycles. Then, based on an analysis of the simulation results (torque, speed and power) the technical requirements of the PM-EVT are defined. Finally, the PMEVT machine is designed. The PM-EVT design results are presented and validated using the finite element method. Author Keywords: Electric variable transmission , Permanent magnet machine , Planetary gear , Series-parallel HEV