Magnetic Circuit of an Electrodynamic Shaker

The realization of this project was the beginning of a fruitful and long-term collaboration with a client manufacturing large testing systems for the automotive and defence industry. Its aim was to improve an electrodynamic shaker performance by finding an optimal design of the magnetic circuit and maximizing magnetic flux density across the air gap containing the movable armature coils. The higher the magnetic flux density amplitude, the higher the force acting on the movable parts of the shaker. 

The model was created using COMSOL Multiphysics software utilizing the AC/DC and Design modules. The governing Amper’s law equation was prescribed by the Magnetic Fields physics interface, further applying the Coil interface for both static and harmonic field coils. The magnetic circuit was composed of nonlinear material defined by a B-H curve. Further, thin, high-conductivity plates were represented by transition boundary conditions, protecting the magnetic circuit from eddy currents. For computational time reduction, the model took advantage of a sector symmetry, effectively running the simulation only for one-fourth of the entire geometry.

The simulation output was a magnetic flux density distribution inside the magnetic circuit and across the air gap. Based on the obtained results, improvements to the magnetic circuits were proposed and tested on the virtual system. The results were verified by calculating the electromagnetic force acting on the movable parts, a value measurable on the actual machine. Besides a significant improvement in performance, the model further helped to better shield the system from eddy currents and find an optimal number of windings having a beneficial effect on the system efficiency and power consumption.