A new switched reluctance motor (SRM) drive converter requiring only one switch per phase with the capability of providing high demagnetisation voltage is presented. To increase the output torque of the SRM drive system, the phase excitation area must be increased; however, during the demagnetisation interval, this would cause the phase current to extend into the negative torque generation area. To eliminate this problem, the proposed converter provides high demagnetisation voltage in order to perform the phase current commutation faster. The proposed converter inherently operates in continuous conduction mode (CCM); thus, innovative aspect of the proposed converter is exploiting the advantages of operating with high demagnetisation voltage in CCM. The converter operating modes are analysed and the effectiveness of the proposed converter on improvement of SRM drive torque per ampere capability is demonstrated by simulation and experimental results.

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An analytical model of excitation system of brushless wound-rotor synchronous starter generator for aircraft applications is developed and presented in this study. During engine start-up process, the starter generator operates as a motor to start the aircraft turbine and to assist it up to the self-sustaining speed. On the basis of rotation speed of the starter generator in the engine start-up process, there are three excitation modes for the exciter and two transient modes for the field current of the main generator (MG). In this study, for each excitation mode, the relationship between the excitation current (field current of the exciter) and the field current of MG is investigated by taking into account the influence of power electronic parts. This study also proposes a control method for the generator field current in all excitation modes which can detect optimum operating points for transition between excitation modes. Furthermore, a seamless transient control strategy is proposed for the transient modes of the generator field current. Simulation and experimental results are provided to demonstrate the feasibility of the proposed solution.

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