Excitation procedure for brushless wound‐rotor synchronous starter generator with seamless transitions

Abstract

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.

A dynamic functional model of diode bridge rectifier for unbalanced input voltage conditions

“…According to [9], the most common fault condition in a three‐phase system is the single‐phase fault (with 80% probability of occurrence) leading to unequal voltage magnitudes and fundamental phase angle deviation. In addition, in some applications like rotating DBR of the brushless excitation system of wound‐rotor synchronous machine in motoring operation mode, input voltages of DBR are inherently unbalanced with unequal voltage magnitudes and phase angle deviation [10].…”

“…T and ω are fundamental period and frequency of the signal, respectively. Using (10), first-order time-varying phasors of line-to-line voltages are…”

Power sharing strategy for multi‐source electrical auxiliary power unit with bi‐directional interaction capability

“…The functionality of an APU in an aircraft is basically like an uninterruptible power supply (UPS) in a power grid. It is usually interfaced with the main generator to supply load in emergency conditions or during start‐ups [1, 2]. Furthermore, APU can act as a backup for the ground power unit to supply power to critical loads during a stopover at the airports [3, 4].…”