Nonlinear control of axial flux flywheel motor/generator set of coil launchers

One of the main challenges in Electromagnetic Launcher (EML) studies is pertinent to the requirement of a huge amount of energy for a very short time period. In space and defense applications, launching operation takes just a couple of seconds but it requires power in mega- or terawatt levels. Generally speaking, there are two major types of power source to meet such a requirement; capacitor sets and motor/generator sets. In this study, a nonlinear velocity tracking controller for an Axial Flux Permanent Magnet (AFPM) motor/generator set with a flywheel is designed. The AFPM machine can operate in both motor and generator mode so that the machine serves as main supply to store mechanical energy on a flywheel mounted on the shaft of the machine in motor mode of operation. In generator mode of operation, on the other hand, the AFPM machine will supply the coils of EML by converting the mechanical energy stored in the flywheel into electrical energy. Designed controller aims to achieve performance specifications in both modes of operation. Numerical results are also presented to show the performance and feasibility of the proposed nonlinear control scheme.