Direct Flux Vector Control of Axial Flux IPM Motors for in-wheel traction solutions

The paper describes a Direct-Flux Vector Control (DFVC) scheme suitable for synchronous Permanent Magnet (PM) drives employed in applications that require motor flux-weakening operation, as happens for traction drives. The proposed controller operates in stator flux reference frame and can be easily adapted for Surface-mounted PM (SPM) and Interior PM (IPM) motors. The stator flux is directly controlled by the direct component of the voltage vector, while the torque is controlled by regulating the quadrature current component. The DFVC scheme has been used for an Axial Flux IPM (AFIPM) designed as a wheel motor for light traction application. Experimental results are provided for an 1.2 kW AFIPM prototype, demonstrating good steady-state and transient performance, as well as maximum torque production under current and voltage limitations.