超磁致伸缩超声振动系统的机电转换效率研究

Research on the Electromechanical Conversion Efficiency for Giant Magnetostrictive Ultrasonic Machining System

为提高超声振动系统的能量转换效率和功率容量,提出超磁致伸缩超声振动系统的设计方法,研究导磁体材料特性对超声系统振动性能的影响规律。采用硅钢、铁氧体和磁粉心三种磁性材料设计导磁体,并建立超声振动系统的等效电路模型;通过阻抗分析建立3种超声振动系统的阻抗圆曲线,得到谐振频率和机电转换系数等参数,提出导磁材料特性对系统机电能量转换效率的影响规律。为验证阻抗分析结果的正确性,试验测定3种超声系统在不同电压幅值激励下的振幅-电流灵敏度与频率的关系曲线,验证导磁材料参数与系统机电能量转换效率之间的关系。结果表明:高磁导率铁氧体材料可提高超声振动系统在小功率工作条件下的机电能量转换效率,而对于大功率超声振动系统而言,需要兼顾磁导率和饱和磁通密度,使导磁体工作于非磁饱和状态,以提高系统换能效率,这有助于指导不同功率大小超声振动系统的导磁体材料选择。

In order to improve the efficiency and capability of ultrasonic machining system, the design method of Giant magnetostrictive ultrasonic machining systems （GMUMS） is presented and the influence of magnetic material for the closed magnetic circuit on the vibration performance is studied. Three kinds of magnetic materials, including silicon steel, ferrite and magnetic powder core, are applied and the equivalent circuit is proposed. Based on impedance analysis method, the impedance circle is plotted to determine the resonant frequency and eleetromechanical conversion coefficient so that the rule of magnetic material properties and electromechanical conversion coefficient can be put forward. To verify the impedance analysis results, the relation of amplitude-current sensitivity and excitation frequency under four excitation voltage levels is established and the optimization selection method of the magnetic material for different power-capability ultrasonic system is proposed. The results reveal that a low-power GMUMS can generate a higher electromechanical conversion coefficient by using high permeability ferrite material, while the magnetic powder core with higher saturation magnetic flux density is well-suited for high-power GMUMS due to the influence of both the permeability and saturation magnetic flux density on the vibration performance. It is useful in choosing magnetic materials for the GMUMS with different levels of power.