High efficiency adjustable speed control of IPMSM with variable permanent magnet flux linkage

An interior permanent magnet synchronous motor (IPMSM) with variable permanent magnet flux linkage is introduced in this paper. By adapting movable flux-shortening iron pieces in the flux barriers of the rotor, it is possible to decrease the permanent magnet flux linkage to some extent. In the flux-weakening control region, the required d-axis current to weaken the armature flux linkage becomes smaller due to the decrease of the permanent magnet flux linkage. The constant output power operating range of the proposed IPMSM can be extended compared to the conventional IPMSM under the same limitation of the supply ability of the inverter. The becoming smaller d-axis current also contributes to the improvement of the efficiency as well as the power factor characteristics especially at light load, high speed operation. By choosing suitable inserting scheme of the movable iron pieces, it is possible to realize optimal operating performance for the proposed IPMSM. The advantages of the IPMSM proposed in this paper are verified with experiments