A New Open-Loop Synchronization Method Based on Compensation of Phase Deviation for Pulsed Generator Converter

Abstract

At Wuhan National High Magnetic Field Center, a 100-MVA/100-MJ pulsed generator and two 67.5-MW converter modules have been installed as power supply for pulsed magnets. Long-pulsed magnetic field with 50-T/100-ms flat-top has been produced and 100-T pulse magnetic field is under commissioning by utilizing this pulsed generator converter. In this high-power occasion, the three-phase voltages undergo serious harmonics, large notches, amplitude variation, rapid frequency fluctuation, and phase jump simultaneously. Synchronization method with fast dynamics, excellent harmonics rejection, and smooth time-domain response is expected, which is difficult for the conventional synchronous reference frame phase-locked loop (SRF-PLL). Therefore, this paper presents a new synchronization method based on compensation of phase deviation. In this method, the phase of three-phase voltages, which is achieved by summing filtered phase deviation and phase of a given $d$ - $q$ rotating reference frame, is open-loop computed directly. The main attributes of the method are the fact that its dynamics is independent of the input vector amplitude, better harmonics rejection/dynamics tradeoff, and smooth time-domain response. Comparative experiments are performed between the proposed synchronization method and SRF-PLL.