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After active neutral point clamped(ANPC) adopts SiC-MOSFETs, SiC-MOSFETs are easily damaged due to the excessive peak voltage. This paper establishes a single-phase parasitic inductance model of ANPC based on the SiC-MOSFET half-bridge modules. Then, based on this model, the cause of peak voltage on SiC-MOSFETs during ANPC commutation is analyzed. Finally, a short-loop commutation modulation strategy is proposed under the full working conditions of ANPC. The modulation strategy considers the influence of modulation carriers selection and dead time on ANPC commutation and optimizes the ANPC commutation loop to suppress the overvoltage on SiC-MOSFETs during ANPC commutation.

In order to improve the thrust density and efficiency of linear induction motors (LIM) in large load transport situations, a cross-shaped linear induction motors (CSLIM) structure is proposed in this paper. Firstly, for analyzing the characteristics of CSLIM, the magnetic field and electromagnetic thrust expression of long primary double-sided linear induction motors (LP-DSLIM) when considering the saturation of iron core are deduced, based on which the effect of iron saturation on electromagnetic thrust is analyzed. Secondary, the equivalent circuit of CSLIM is proposed and the effect of coupling on the electromagnetic thrust is analyzed. The results show that, the maximum electromagnetic thrust is reduced and the corresponding slip frequency is increased when iron saturation and coupling. For improving the problem of iron core saturation and coupling of CSLIM, a structure with square-type iron and lap winding is further proposed, and the rationality of CSLIM structure is verified by comparing the finite element simulation results of flux density on core, eddy current on secondary and the electromagnetic thrust.

Permanent magnet linear synchronous motor (PMLSM) has the advantages of high thrust density and good control accuracy, which can be applied in high-power and high-speed occasions. In this paper, the analytical models are established to obtain the electromagnetic performance for the PMLSMs with dual secondaries and dual primaries. The air-gap flux density and the electromagnetic thrust are also obtained by the finite element model to verify theoretical analysis. Besides, an improved structure is also put forward in order to suppress the thrust fluctuation of the PMLSM. Finally, the advantages and disadvantages of two PMLSMs topologies are listed. These analyses would provide a guide for the design of PMLSMs applied in high-power and high-speed occasions.