Design and optimization of a magnetically sprung block magnet vibration energy harvester

•Fully-analytic model developed for block magnet vibration energy harvester.•Developed optimization procedure produces a high normalized power density.•Block magnets allow more design flexibility compared to cylindrical.•410μW power output at 0.1g acceleration amplitude at 6.7Hz. A magnetically sprung, electromagnetic vibration energy harvester with block magnets is presented. The harvester achieves one of the highest reported measured normalized power densities for a magnetic levitation energy harvester of 7000μWcm−3g−2. The measured power output at 6.7Hz was 410μW and 304μW at 0.1g and 0.075g acceleration amplitudes, respectively. The energy harvester was constructed using block magnets, which allow more flexibility in design compared to the typical cylindrical magnet devices. The device has been modeled using analytic equations to calculate the nonlinear magnetic forces and flux, which have been input into a time step model of the harvester to calculate power output. The full design procedure to optimize the device is presented.