High-Efficiency Synchronous Motors with Permanent Magnets

The paper deals with highly efficient Permanent Magnet Synchronous Motors (PMSM) and Line Start Permanent Magnet Motors (LSPMM). LSPMM are well recognized and used, also in the heavy industry in the drives which do not need a change of the rotation speed, but they can not drive the machines requiring high starting torque or machines with big inertia torque (for example, mills or belt conveyors while fully loaded during start-up). The novel design of LSPMM with winding in the rotor was developed, described, manufactured and tested. LSPMM with winding in the rotor (LSPMMwWR) do not need frequency inverters for start-up and operation, and that kind of motor can be used for driving machines with big inertia torque or machines requiring high and long-lasting starting torque. The advantage of LSPMMwWR over LSPMM is characterized mainly by minimizing thermal losses in the rotor, which do not cause thermal overheating of permanent magnets, and also by higher starting torque. The experimental model of the LSPMMwWR was manufactured and tested, and the results are presented in the paper. Additionally, the paper shows an example of the use of PMSM in suspended trains for underground applications in coal mines. The train and the motors are supplied from lithium-ion batteries designed and tested for the explosion-risk areas.