A novel synchronism method for thyristor power converters using the space vector approach

Phase-controlled operation of thyristor power rectifiers requires instantaneous phase information of the fundamental component of the grid voltage in order to generate the proper gating sequence. In many high-power, high-precision applications, such as driving the bending magnets of large particle accelerators, the power converters are fed from a local grid, which produces significant frequency variations and large voltage notches superimposed to the sinusoidal AC voltage due to the commutation interval. These strong disturbances impose some difficulties in measuring the phase of the mains, affecting the precision of the converter. In this paper, we present a new method to generate a fast and precise synchronism signal based on the concept of space vectors. The proposed method allows to track line frequency changes within one cycle of the mains in spite of the large voltage notches produced by the commutation overlap angle. Simulation and experimental results are provided.