Numerical Optimization Approach of the Gap between the Magnet and Coil for Electromagnetic Vibration Energy Harvesters Design
In the design of the micro electromagnetic vibration harvester, an important goal is maximization of the magnetic flux linkage gradient, which directly determines the induced voltage and output power of the electromagnetic vibration harvester. This paper established a numerical model based on structure of the electromagnetic vibration energy harvester. An analytic expression for the magnetic field of rectangular permanent magnets is used to build up an electromagnetic coupling model. The magnetic field distribution of the rectangular permanent magnet was analyzed. The effects of the gap between the magnet and the coil on the load voltage of the electromagnetic vibration energy harvester were investigated. According to the formula, the magnetic flux linkage and flux gradient were calculated to optimize the geometrical parameter of the magnet and coil. The method and boundary conditions of optimizing the gap between the magnet and coil were presented. The maximum output voltage can be obtained by optimizing the gap between the magnet and the coil. A simple prototype was fabricated and measured to validate the theoretical deducing and the feasibility of method.