Electric motor offers high performance without rare earth materials
Researchers have developed a permanent magnet assisted synchronous reluctance machine that is completely free of rare earth materials. This achievement is a major step to the design if electric vehicles with a driving range comparable to today’s conventional combustion engines. At the same time, this type of motor has a political dimension: It makes the European industry less dependent on China as the most important supplier of such materials.
In today’s electric vehicles, engines are involved, which are dependent on the use of rare earth metals to produce permanent magnets. Although they are a key building block for these engines, these metals are equally the highest barrier to the achievement of the necessary improvements to a more powerful introduction of electric vehicles. In fact, the majority of these metals come from China, which not only increases the cost of electric vehicles, but also puts the car industry at risk. “There is a risk that geopolitics could influence the delivery of permanent magnets from China to European vehicle manufacturers,” explains Michele De Gennaro, project coordinator of the SyrNemo research project. “This in turn could paralyze the production and delivery of electric vehicles in Europe.”
The problem: If these magnets are removed from the engine, they lose three quarters of their power. The SyrNemo project was able to solve this problem by designing and testing prototypes of a rare earth-free permanent magnet assisted synchronous reluctance machine (PMaSYRM). “This machine has been developed specifically to avoid the use of rare earth materials in magnets by the use of ferrites,” says De Gennaro. “That’s why we’ve been driving the development of other engine components, such as a new hairpin winding for the stator and an innovative lightweight module design for the rotor.”
In addition to the engine, the project also provided the design for a complete drive with integrated power electronics and an air-cooled housing. According to the test results, the final drive design has a maximum torque output of 133 Nm at 3 600 rpm and a maximum output of 52.9 kW at 4 300 rpm.
The SyrNemodesign is delivered at level 5 of Technology Readiness Level 5, suitable for production at medium production volumes of the order of tens of thousands of units per year and fully adaptable to various vehicle segments. The SyrNemodesign is evaluated on the basis of two of the relevant guide values for electric motors, the mechanical constant of the mechanical power and the torque density values, which show an improvement of +45% and +25% compared to the best guideline values of 2016. “SyrNemo is thus the best rare-earth synchronous machine in its class,” says De Gennaro.
Under the Kyoto Protocol, the EU is committed to reduce greenhouse gas emissions by 20% below 1990 levels and by 80 to 90% by 2050. To achieve this goal, the transport sector wants to reduce its emissions by 60% by 2050. Most of these reductions are likely to be realized in road transport, which today is responsible for 7 billion tonnes of CO2 / year, equivalent to one fifth of the EU’s total greenhouse gas emissions.
Participating entities in the SyrNemo project included, among other, AVL List GmbH, Centro Ricerche Fiat SCPA and the universities of Bologna, Hannover and Brussels.
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