A new open-loop synchronization method based on compensation of phase deviation for pulsed generator converter

At Wuhan National High Magnetic Field Center (WHMFC), 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 a 100 MVA/100 MJ pulsed generator and two 67.5 MW converter modules. In this high power occasion, the voltages undergo harmonics, notches, amplitude variation, frequency fluctuation and phase step. Synchronization method with fast dynamics, excellent harmonics rejection and smooth time-domain response is expected, which is difficult for synchronous reference frame PLL (SRF-PLL). Therefore the paper presents a synchronization method based on compensation of phase deviation. The phase of voltages, which is achieved by compensating phase of a given rotating dq reference frame with filtered phase deviation, is open-loop computed directly. The attributes are the fact that its dynamics free from the input vector amplitude, better harmonics rejection/dynamics tradeoff and smoother time domain response. Comparative experiments are performed between the proposed method and SRF-PLL.