Simulation and experiments of interface circuits for a magnetically coupled dual-beam nonlinear energy harvesting system under rotational excitation

Rotational energy harvesting technology shows great potential for enabling self-powered operation or extending the service life of microelectronic devices, with broad application prospects in intelligent sensing, structural health monitoring, and the internet of things. In practical applications, low-powered microelectronic devices typically require stable direct current (DC) power, whereas the energy conversion elements in energy harvesting systems generally output alternating current (AC). Therefore, it is necessary to investigate the actual output performance of energy harvesting systems with different interface circuits. In this paper, a magnetically coupled dual-beam nonlinear energy harvesting system under rotational excitation is considered as the research object, and simulation and experiments are carried out for three typical interface circuits: the standard energy harvesting (SEH) circuit, the parallel synchronized switching harvesting on inductor (P-SSHI) circuit, and the series synchronized switching harvesting on inductor (S-SSHI) circuit. The operating principles of the three interface circuits are introduced in detail. Simulations are conducted to analyze the charging processes of the three interface circuits under different input signals, and the voltage conversion characteristics under periodic sinusoidal and random excitations are examined. An experimental setup consisting of the rotational energy harvesting structure connected to the three interface circuits is established. Experimental tests and comparative analyses of the output voltage amplitude, stability, and power characteristics of the three interface circuits are performed under different rotational speeds and load resistance conditions. Experimental results show that the S-SSHI circuit produces a voltage close to 1 V with excellent stability at a rotational speed of 10 r/min, while at 480 r/min, both the SEH and P-SSHI circuits can achieve stable DC outputs of approximately 3 V. Results demonstrate that all three interface circuits are capable of converting the AC output voltage into stable DC voltages required by microelectronic devices, and that both the voltage amplitude and stability improve significantly with increasing the rotational speed. Overall, the P-SSHI circuit exhibits the highest voltage conversion efficiency over a wide range of rotational speeds, whereas the S-SSHI circuit provides superior voltage stability under low-speed conditions, making it more suitable for ultra-low-speed energy harvesting applications.