A doubly salient permanent magnet motor capable of field weakening

Permanent magnet (PM) machines have been used widely for industrial applications. However, the operating speed range in most of these applications is very limited due to the difficulty of achieving field weakening in most PM structures. This difficulty is one of the major stumbling blocks to widespread application of PM machines. A new doubly salient PM motor topology is proposed in this paper which offers the possibility of low cost, high performance and robust realization of field adjustment. It is shown that by controlling the field winding, 100% field weakening and 2 p.u. torque capability can be achieved without sacrificing other performance characteristics of the machine. Hence, machines of good efficiency throughout a field weakened speed range exceeding five to one can be readily devised. This feature makes this new motor a potential candidate in future motor drive systems