Voltage Synchronization Scheme and Control Strategy for 50 T Flat-Top Pulsed Magnetic Field Power System

At the Wuhan National High Magnetic Field Center (WHMFC), a 100 MJ/100 MVA pulsed generator is used to energize two 12-pulse power converter modules for 50 T flat-top pulsed magnetic field. In this paper, to get a high stability of the magnetic field, a voltage synchronization scheme and a specific control strategy for the power system are designed. Three prime factors which influence the precision of voltage synchronization are analyzed. By using a band-pass filter to smooth out the synchronized line-voltage, a fast response phase locking technique based on zero-crossing detection is adopted to reduce the effects of the above three factors. Then, considering the load characteristics of the 50 T dual-coil magnet about the mutual inductance of two coils and the dramatic increase of the thermal resistance, a no-flat control strategy which could decrease the variation of the firing angle and lower the voltage distortion is employed. By this means, 50 T pulsed field of 100 ms flat-top duration with a ripple of less than 0.5% had been produced, which verified the feasibility of the voltage Synchronization scheme and the control strategy.