Design of a high current pulse generator for magnetoforming

Magneto forming of tube or sheet metal parts can significantly extend the range of geometries conceivable with state-of-the-art forming methods. Major advantage is the considerably higher forming speed of the process achievable by using a magnetic piston without inertia. Key for this technology is the development of reliable, long-lifetime, high current pulse power generators able to deliver tens to hundreds of kiloamps of peak current to a mainly inductive load which is highly variable in time during the forming process. We report on the design of a pulse generator for peak currents of up to 200 kA at a pulse width of typically 80 mus, depending on the load parameters. In order to meet lifetime requirements suitable for industrial applications, the short circuit handling capability of peak currents of up to 450 kA is a major issue in the pulse generator design. A modular, 3-branch design has been adopted to achieve the requirements concerning reliability, lifetime, and short circuit handling. The prototype design is based upon off-the-shelf devices, including high-current discharge switches based on semiconductor devices. The basic concept of the pulse generator is presented, including results from extensive circuit modeling concerning nominal performance as well as short circuit behavior