Synchronous motors are increasingly used in industry, and they need to be made more energy efficient. To do this, it is possible to optimize the rotor of the synchronous motor by changing the design, obtaining the best option due to topological optimization. But the standard design of a synchronous motor is quite complicated for calculations by the finite element method, so it is necessary to simplify it as much as possible. To make all elements the simplest from the geometric point of view (rectangles, straight lines as much as possible, etc.), and to make for calculation not the complete model, but the smallest sector for which topological optimization can be adequately calculated. To do this, it is necessary to calculate the magnetic moment for a standard design, for each step of structural change, and compare these values. If there is a slight discrepancy in the data, it will be necessary to choose the sector correctly and confirm the adequacy of the model by comparison. All these calculations should be performed for the predicted model, which should be obtained after topological optimization.