This paper proposes two biased flux permanent magnet (BFPM) motors in which the torque ripple issue of conventional doubly salient permanent magnet (DSPM) motor, as its predecessor, is greatly suppressed and the torque density of the BFPM structures has been improved. The permanent magnets (PMs) are positioned where they are easily accessible for an even better temperature management compared to other stator-PM structures. The second structure utilizes the available space between stator poles in which two sets of PMs are embedded between stator modules. This increases the torque density even more. The operation principles of these two structures are deeply discussed by identifying working harmonics of each flux source and then evaluated by the finite element method (FEM). An analytical procedure by deriving sizing equations of the structures is introduced and the effect of different design parameters on the electromagnetic performance is comprehensively studied. The performances of the structures are analysed by FEM. To better evaluate the superiority of the proposed structures, a demagnetization analysis is conducted and it is shown that even in high temperatures, the performance degradation of the proposed structures is much lower compared to other stator-PM structures. Finally, the proposed structures are prototyped to verify the simulation results.

In this study, a novel fully soft-switched high step-up dc–dc converter is proposed. The proposed converter comprises the integration of boost and Ćuk converters with the same input inductor and mosfet and series-connected output dc-link voltages. In this topology, the switch is turned-on under zero current switching (ZCS) and low-voltage conditions since the converter works under discontinuous conduction mode due to small output Ćuk inductance. In addition, two coupled inductors are applied to create a similar voltage gain and soft switching conditions for all semiconductor elements. The first coupled inductor is placed in series with the Ćuk diode, which provides a balanced dc link for wide load and input voltage variations and ZCS conditions for the Ćuk diode. The second coupled inductor forms a lossless passive snubber to provide a zero-voltage switching turn-off condition for the main switch. This lossless passive snubber provides a clamped circuit and reduces the turn-off slew rate of the switch voltage. This snubber circuit is simple with minimum elements, and the snubber capacitor discharges to the output while the switch is off. Moreover, the input current is ripple-free, which is appropriate for renewable energy systems integration. The experiments substantiate the effectiveness of the proposed converter.

A new combined boost-Cuk-forward (CBCF) converter with ripple-free input current and low switch voltage stress is proposed for high step-up applications. Two coupled inductors are applied to achieve low switch voltage stress as well as balanced dc-link voltages, wherein the former is placed in series with the boost diode, and the latter is formed as a forward converter. Because these inductors are coupled with the output Cuk inductor, a ripple-free input current is also attained. The proposed converter is run at discontinuous conduction mode (DCM) by applying a low output-side Cuk inductance to reduce the switching loss by providing a ZCS turn-on of MOSFET and removing the diode reverse recovery current. In addition, the proposed converter does not have a problem with ground leakage current. The practical results verify the performance and effectiveness of the proposed CBCF high step-up converter.