Study on verification of AFE rectifier control for electric propulsion ship

Abstract

Electric propulsion ships are frequently subject to fluctuations in the generator output voltage and current due to load vari-ations from unpredictable environmental changes, including those of the maritime environment. The variation in the generator output affects the detection of the phase angle of the supply voltage, which is a key factor in the control of the active front end (AFE) rectifier of an electric propulsion system. In this study, an improved supply voltage phase-angle controller was proposed and applied to accu-rately detect the supply voltage phase angle required for the control of the AFE rectifier. The controller can be applied even under fluctuations in the output voltages of the generator owing to various circumstances that may arise in the electric propulsion ship. To demonstrate the effectiveness of the proposed improved supply voltage phase-angle controller, an irregular waveform with harmonics and zero-crossing in the output voltage of the generator was arbitrarily generated and inserted into the phase-angle detector. The pro-posed supply voltage phase-angle controller promoted a remarkable improvement in the phase-angle detection performance compared with that of the zero-crossing technique, a conventional method of phase-angle detection, even under irregular variations in the output voltage of the generator.