Exploring coupled electromagnetic field and thermal field for two types of rotor configuration of brushless DC (BLDC) motor

Aim. The introduction of the full paper reviews the achievements of Refs. 1 through 5. We now propose using the mathematically more accurate finite element analysis of coupled electromagnetic field and thermal field to explore the locations of trouble for two types of rotor configuration of a BLDC motor: surface-mounted radial exciting and interior tangential exciting. Sections 1, 2 and 3 explain our method of exploration; they are respectively entitled electromagnetic field, thermal field and the finite element analysis of coupled electromagnetic field and thermal field. In section 3, Figs. 1 through 4 give the calculated results for the two types of rotor configuration (unfortunately NWPU Journal prints them in black and white instead of in color as they should be). Section 4 presents in Figs. 5, 8 and 9 the experimental results for the two types of rotor configuration. Section 5 gives concluding remarks; its core consists of: (1) the temperature rise in the retaining sleeve of surface-mounted configuration is severest and we offer suggestions on how to alleviate it; (2) the flux leakage is highest in the magnet terminal of interior configuration, causing circulating flow in the current, and we offer suggestions on how to alleviate it.