振动发电机的系统建模与频率特性分析

System modeling and frequency characteristics analysis of vibration-to-electrical generator

采用两自由度振动模型对振动发电机进行描述,由于非线性磁力的影响,该模型表明电磁式振动发电机是非线性非自治系统。基于该模型,对正弦振动激励下的系统响应进行仿真分析,结果表明,动子与定子的相对位移响应出现了明显的倍频现象,而输出电动势的频率分布更加复杂,不但有对应激励频率的主振动解和亚谐振动解,而且还有对应固有频率的亚谐振动解和超谐振动解,表明系统具有较强的非线性,且随着输入振动能量增大,系统的非线性特征更加明显。在10Hz正弦振动激励下的测试发现,输出电动势的幅频特性在10Hz、20Hz和30Hz处出现峰值,表明输出电动势出现了明显的倍频信号,实验结果与仿真结果的频率特性一致。

A vibration model of two degrees of freedom is built for the vibration-to-electrical generator. The model shows that the generator is a nonlinear and non-autonomous system due to the nonlinear magnetic force. The system responses generated by sinusoidal vibrations are calculated on the basis of the model proposed above. The relative displacements between the mover and the stator have obvious frequency multiplication. On the other hand,the system has strong nonlinearity,because the output electromotive force（ EMF） contains not only solutions to the main and sub-harmonic vibrations that correspond to vibration frequency,but also the sub-harmonic and the super harmonic vibration solutions that correspond to the nature frequency of the generator. The system will be more nonlinear with more vibration energy input. The tested results show that the amplitude-frequency characteristic of output EMF has obvious peak value at 10 Hz,20 Hz and 30 Hz under the 10 Hz sinusoidal vibration. The output EMF has obvious frequency multiplication which is consistent with the calculated results.