Unified Direct-Flux Vector Control for AC motor drives

The paper introduces an Unified Direct-Flux Vector Control (UDFVC) scheme suitable for simusoidal AC motor drives. The AC drives considered here are the Induction Motor (IM) drives, Synchronous Reluctance (SyR) and synchronous Permanent Magnet (PM) drives of the Interior PM (IPM) and Surface-mounted PM (SPM) types. The proposed controller operates in stator flux coordinates: the stator flux amplitude is directly controlled by the direct voltage component, while the torque is controlled by regulating the quadrature current component. The control firmware is the same for all the motor under test with the only exception of the magnetic model used for flux estimation at low speed. The UDFVC is particularly convenient when flux-weakening is required, since it easily guarantees maximum torque production under current and voltage limitations. Experimental results on four different drives are provided.