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This study presents an analytical method to calculate instantaneous electromagnetic torque in slotless axial flux brushless DC (BLDC) motors. This method is based on Lorentz force theorem and using phase induced back electromagnetic force (EMF) and phase current. A new analytical method was introduced to compute induced back EMF. 3D finite element computations validate the proposed method. This method requires much less computation time than conventional 3D finite elements, and is therefore suitable for optimisation purposes. Due to practical limitation, phase current approximated by the trapezoidal function. Torque ripple dependency on design parameters was studied and optimum parameters were extracted for slotless axial flux BLDC motor.

This study presents a novel configuration for stacked multicell (SM) converters. The main advantage of the proposed converter, in comparison with the conventional one, is that the number of required dc voltage sources is reduced from two to one in the proposed topology which results in decreasing the cost and size of the converter. This progress is achieved by adding four lowfrequency switches to the conventional configuration of SM converter whereas the number and voltage rating of high-frequency switches and clamping capacitors as well as the number of high-frequency switchings during a full cycle are kept constant. This converter is controlled by phase shifted carrier-sinusoidal pulse width modulation technique; therefore the self-balancing phenomenon of clamping capacitors' voltages is maintained. This study also presents a state-space representation model to analyse the dynamic of clamping capacitor's self-balancing phenomenon in the proposed SM converter by obtaining the switching instants of the pulse width modulation in terms of the Kapteyn series. Numerical solution of obtained state-space representation model of the proposed converter and simulation results as well as measurements taken from an experimental set-up are presented in order to validate the effectiveness and advantages of the proposed configuration as well as its control strategy and state-space model.

This study describes the systematic signal flow graph (SFG) modelling of a single inductor triple output (SITO) DC/DC converters. The multi-stages operation of SITO converter and the parasitic elements cause obtaining a model to predict the all behaviours of converter be more difficult than typical converters. By SFG method, all small-signal transfer functions can be derived. Derivations of large-signal, small-signal and steady-state models are demonstrated by considering a single inductor triple output boost/boost convert. The effect of inductor ripple current has been considered to determine the acceptable region of SFG modelling method. Simulation and experimental results are included to show the validity of the obtained model.