For automotive applications, permanent magnet synchronous motors are the most common and usually contain rare-earth permanent magnets, such as neodymium magnets. The use of this type of magnet guarantees high efficiencies, torques and power densities. However, rare earth elements have a high cost and there is concern about the stability of supply and environmental damage caused by their extraction. For this reason, efforts are now being made to find an alternative to the use of rare-earth magnets, i.e. rare-earth-free magnets, in all sectors that require permanent magnets, including the automotive industry. During this thesis work, carried out in collaboration with the company Volvo Cars, a synchronous motor with internal permanent magnets was designed using rare-earth-free magnets, mainly composed of iron and nitrogen, elements that are among the most abundant magnetic materials on Earth.