A Reverse Electromagnetic Force Suppression Circuit and Its Control Method for Reluctance Coil-Gun

To realize high-speed launch of reluctance coil-gun (RCG) requires the suppression of reverse electromagnetic (EM) force, when the center of the coil coincides with the center of the projectile to disconnect the coil power supply to quickly reduce the current is an effective means. In this study, the problems in the existing researches are explained in terms of circuit theory, and two technical difficulties are pointed out. One is to find the exact coincide time, which is basically estimated by the finite element method (FEM) at present, there are problems of slow calculation speed, and the results are affected by the accuracy of the input electrical parameters. Second, a sudden shutdown of a charged IGBT will create a large inductive electric potential and may be damaged. In this study, the treatment methods are proposed for these two points, respectively. On the one hand, an algorithm model is proposed to quickly estimate the coincide time based on the measured current data in the coil; compared with the FEM, it has the advantages of no need to know the electrical parameters and fast calculation speed. On the other hand, a new circuit topology is proposed, in which the IGBT is moved to the coil branch for current breaking at any time and a resistor–capacitor (RC) absorption circuit is connected in parallel to the coil side to protect the IGBT. The comparison of experimental and simulation results proves that the method proposed in this study is feasible, and it avoids both the tedious operation of testing component parameters and the errors caused by inaccurate parameter input, showing the convenience in application.