With the development of traction motors for new energy vehicles toward higher rotational speeds and power density

magnetic flux leakage in rotor bridges has emerged as a primary constraint on flux utilization efficiency. To address this challenge

an interior permanent magnet synchronous motor(IPMSM)was proposed featuring a novel dual-V-shaped broken-bridge rotor structure. The design eliminates conventional external flux barriers and interpolar ribs

effectively blocking leakage flux paths and improving permanent magnet utilization. To enable rapid calculation of the no-load air-gap magnetic field in this structure

a hierarchical analytical modeling approach was developed based on the subdomain method. By the proposed method

the dual-V-shaped rotor was decomposed into two independent V-shaped substructures

their respective magnetic field distributions were computed

and the results were superimposed while incorporating correction coefficients to account for the modulation effects of zero-flux regions. Validation against finite element analysis demonstrates excellent agreement

with only a 3.4% deviation in no-load back-EMF calculation. The results confirm that the proposed method provides both computational efficiency and accuracy in predicting electromagnetic performance

offering a valuable analytical tool for optimizing multi-layer interior permanent magnet motor designs.