FRT Method for Matrix Converter to Ensure Compatibility between Generator Torque Control and Grid Reactive Current Control

Abstract

This paper proposes an FRT (Fault ride through) method for a matrix converter in a grid-connected system to control the grid reactive current and the generator torque during a three-phase short voltage sag. In the proposed method, the control period of the system is divided into three modes. In the first mode, all switches are turned off, and in the second mode, a zero vector is obtained at the output of the matrix converter. By using these two modes along with a snubber circuit in the matrix converter, the generator torque is controlled during the three-phase voltage sag. Further, in the third mode a non-zero vector is selected to connect the generator to the grid for providing the reactive current to the grid. In addition, the paper proposes a feedback control to obtain a stable ride through operation. From the experimental results, it is confirmed that grid reactive current of 0.86p. u. and generator torque of 1.07 p.u. are achieved by the proposed FRT method during the three-phase voltage sag.