A Direct Performance Comparison of Double-Stator Single-Rotor Axial-Flux and Inrunner Radial-Flux BLDC Motors at the 10 kW Power Level

In this study, two Brushless Direct Current (BLDC) motor topologies—a dual-stator single-rotor axial-flux (DSSR-AF) BLDC motor and a radial-flux inner-rotor (RF inrunner) BLDC motor—are comparatively investigated under identical rated power (10 kW) and equivalent electrical and magnetic material properties. The two motor topologies are designed with distinct magnetic flux paths and structural architectures. The axial-flux motor employs an axial-flux path combined with a dual-stator configuration, whereas the radial-lux motor is based on a conventional inner-rotor structure with a radial-flux path.

During the preliminary design stage, analytical sizing methods are utilized, while the final electromagnetic performance evaluations are conducted using ANSYS RMxprt-assisted modeling and transient finite element analysis (FEA) performed in ANSYS Maxwell 2D. The comparative assessment includes key electromagnetic performance metrics such as average torque, torque ripple, magnetic flux density, efficiency, copper and iron losses, total losses, and torque and power density.

The simulation results indicate that the RF-BLDC motor achieves an efficiency approximately 4.71% higher than that of the DSSR-AF-BLDC motor. The average torque values are 24.6 Nm for the RF-BLDC motor and 13.7 Nm for the DSSR-AF-BLDC motor. The maximum air-gap magnetic flux densities are observed to be 0.48 T and 0.69 T, respectively. These findings demonstrate that the DSSR-AF-BLDC motor offers superior performance in terms of power and torque density, whereas the RF-BLDC motor exhibits an advantage in efficiency.

Although comparative studies on axial- and radial-flux BLDC motor topologies exist in the literature, direct comparisons of DSSR-AF-BLDC motors and conventional RF inrunner BLDC motors at the same power level under fully equivalent electromagnetic and material conditions remain limited. This study provides an original contribution by clearly revealing the efficiency–power density and torque-orientated performance trade-off for BLDC motor topology selection in electric unmanned aerial and ground vehicle applications at the 10 kW power level.