Speed control of interior permanent magnet synchronous motor drive for flux weakening operation

A novel flux-weakening scheme for an interior permanent magnet synchronous motor (IPMSM) is proposed. It is implemented based on the output of the synchronous PI current regulator-reference voltage to PWM inverter. The onset of flux weakening and the level of the flux are adjusted inherently by the outer voltage regulation loop to prevent the saturation of the current regulator. Attractive features of this flux weakening scheme include no dependency on the machine parameters, the guarantee of current regulation at any operating condition, and smooth and fast transition into and out of the flux weakening mode. Experimental results at various operating conditions including the case of detuned parameters are presented to verify the feasibility of the proposed control scheme.