Efficient Motion Control of a PMSM and Design of a Mechanic Energy Storage for a Four Stroke Free Piston Engine

The free piston engine is a certain kind of internal combustion engine which is able to convert the chemically stored energy (e.g. fuel) into mechanical energy without a crank shaft. The mechanical energy can then be directly converted into electrical energy using an electric linear machine. The conversion of mechanical into electrical takes place in the expansion stroke. In the other strokes electrical energy has to be used to realize the four stroke process. The additional degree of freedom, gained by omitting the transformation in rotary motion, allows the trajectory to be adjusted but there is a frequent conversion between mechanical and electrical energy resulting in increased copper losses. To relieve the electrical machine, it is possible to temporarily store the mechanical energy in a spring. The spring must be optimized depending on a trajectory and a load. This optimization problem is considered below. In addition, a control structure for highly dynamic trajectory tracking will be explained.