Simulation of Electromechanical Systems Driven by Large Random Vibrations

In order to simulate vibration energy harvesters driven by broadbanded vibrations, lumped electromechanical models driven by large noise signals must be implemented. We accomplish this in SPICE using externally generated random input signals. The random signals are modeled as colored noise obtained by Altering white noise. A damped mass-spring system, with a Duffing spring, is used as a test case to verify the procedure. An electrostatic vibration energy harvester is then simulated using the same procedure. The power output and RMS mass displacement of the energy harvester are calculated as functions of capacitor gap and electric loading. We have demonstrated the feasibility of simulating random vibrations in a standard circuit simulator and showed a practical way of doing it.