**3.1 Single-phase SMRs**

The typical existing single-phase SMR circuits include: (a) boost SMR; (b) buck SMR; (c) buck- boost SMR; (d) Ćuk SMR; (e) SEPIC SMR with coupled inductors; (f) SEPIC SMR; (g) ZETA SMR; (h) buck-boost cascade SMR; (i) boost-buck hybrid SMR; (j) flyback SMR; (k) isolated Ćuk SMR; and (l) isolated ZETA SMR. Some comments are given for these circuits: (i) The SMRs of (a) to (i) belong to non-isolated types, whereas (j) to (l) are isolated ones; (ii) Among the non-isolated SMRs, the boost-type SMR possesses the best PFC control performance, since its AC input current is directly related to the switched inductor current; (iii) The circuits of (d), (i) and (k) possess the common features of having both continuous input and output currents, and hence needing less stringent filter design requirement.

In addition to the SMRs of (j) to (l) mentioned above, some isolated SMRs specifically for PMSM drives (Singh B. & Singh S., 2010) include: (a) push-pull buck; (b) push-pull boost; (c) half-bridge buck; (d) half-bridge boost; (e) full-bridge buck; (f) full-bridge boost. The pushpull boost SMR possesses excellent PFC control ability and high voltage boost ratio.
