This thesis deals with the design and testing, both in simulation and real testbench environments, of two non-invasive methods for the online estimation of the Permanent Magnets (PMs) temperature in Synchronous machines. The Interior Permanent Magnet (IPM) motors present the best cost versus performance tradeoff for traction applications; this translates into very high efficiency and torque density, associated to Constant Power Speed Range capability. This thesis is in collaboration with a company, which provided the test case and related Matlab - Simulink model and one of the two PMs temperature estimation methods under investigation; due to confidentiality issues, the description and implementation of this method are not presented, while simulation results will be.