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This paper introduces a double-stator synchronous reluctance motor (DS-SynRM) as a solution for reducing the torque ripple of single-stator synchronous reluctance motors (SS-SynRMs). To speed up the design and performance parameter prediction of the DS-SynRM, a magnetic equivalent circuit (MEC) is proposed. To ensure accurate performance prediction of the motor designs using the MEC, a saturation factor is considered in the proposed MEC based on finite element analysis (FEA) results. The accuracy of the developed MEC is validated using 2-D FEA results. A design algorithm based on the proposed MEC in the dq reference frame is introduced. The study investigates four different DS-SynRM designs with similar volume based on the proposed design algorithm. The performance parameters of the proposed designs are compared with a conventional SS-SynRM and two previously introduced single-stator SynRMs constructed by expensive materials (i.e., dual phase materials). The simulation results demonstrate the capability of the DS-SynRM in production of a similar torque compared to the SS-SynRM. It is shown that the proper adjustment of the second stator location produces a lower torque ripple using the DS-SynRM topology.

This paper proposes a quasi-resonant step-up DC-DC converter to provide the DC-link voltage for piezoelectric transmitters (PZETs). The resonance not only provides a soft-switching condition for the converter switches, but also helps to decrease the converter element sizes for marine applications. Operation modes of the proposed converter are discussed. The current and voltage of the converter components are derived analytically, and hence the converter gain is obtained. The performance of the proposed high-step-up, high-power density converter is examined through a comprehensive simulation study. The simulation results demonstrate the soft-switching operation and short transient time required for the converter to reach the reference output voltage. The converter output voltage remains unchanged when an inverter with a passive filter is placed at its output while supplying the PZET. The proposed DC-DC converter is prototyped to validate the converter gain and soft-switching operation experimentally. The converter gain and soft-switching results in simulation are well matched with those of the experimental tests. The converter efficiency in three different switching frequencies is obtained experimentally. The power density of the proposed topology is determined via the designing of a printed circuit board. The experimental results demonstrate the appropriate gain and efficiency of the converter in the tested power range.

In some applications such as electric vehicles, electric motors should operate in a wide torque and speed ranges. An efficiency map is the contour plot of the maximum efficiency of an electric machine in torque-speed plane. It is used to provide an overview on the performance of an electric machine when operates in different operating points. The electric machine losses in different torque and speed operating points play a prominent role in the efficiency of the machines. In this paper, an overview about the change of various loss components in torque-speed envelope of the electric machines is rendered to show the role and significance of each loss component in a wide range of torque and speeds. The research gaps and future research subjects based on the conducted review are reported. The role and possibility of the utilization of the computational intelligence-based modeling of the losses in improvement of the loss estimation is discussed.