Analysis and calculation of the winding loss and rotor loss of solid rotor induction motors for flywheel energy storage system considering the influence of inverter power supply

The high-speed solid rotor induction motor (SRIM) has been widely used in the flywheel energy storage system. The loss of the high-speed SRIM directly affects the energy conversion efficiency of flywheel energy storage system. In order to realize the fast and accurate calculation of the loss in the motor design stage, the analytical models of the winding AC loss and rotor loss of the high-speed SRIM supplied by inverter are established. Based on the principle of area equivalence, the layered method is adopted to consider the influence of stator slot type and irregular conductor distribution in the slot. Besides, the analytical model of the winding AC loss can consider the influence of radial magnetic field and spatial harmonic. The eddy current effect, hysteresis effect and saturation effect of the rotor can be considered by using the layering method. The harmonic distribution of phase voltage and phase current is obtained by circuit simulation. On this basis, the winding AC loss and rotor loss are calculated under the condition of inverter power supply. Besides, the effects of current frequency, conductor diameter and carrier wave ratio on the winding AC loss are studied, and the effects of the air gap length and carrier wave ratio on the rotor loss are studied. Finally, an experimental platform for the loss and temperature rise characteristics of the high-speed SRIM is built, and the accuracy of analytical calculation and finite element simulation is verified through the winding temperature rise experiment and rotor loss experiment. • The analytical model of the winding AC loss considering the influence of inverter power supply, irregular conductor distribution in the slot, irregular slot type, radial magnetic field and spatial harmonics is established. • The analytical model of the rotor loss considering the influence of inverter power supply, rotor hysteresis effect, saturation effect and eddy current effect is established. To the best of the authors' knowledge, this is the first time that the analytical calculation model of winding loss and rotor loss can fully consider the above factors affecting the calculation of the loss. • By applying the analytical model proposed in this paper, the winding loss and the rotor loss of the high-speed SRIM can be calculated quickly and accurately. Compared with the finite element method, the calculation time is greatly reduced.