A state-of-the-art review on low-frequency nonlinear vibration isolation with electromagnetic mechanisms

Vibration isolation is one of the most efficient approaches to protecting host structures from harmful vibrations,especially in aerospace,mechanical,and architectural engineering,etc.Traditional linear vibration isolation is hard to meet the requirements of the loading capacity and isolation band simultaneously,which limits further engineering application,especially in the low-frequency range.In recent twenty years,the nonlinear vibration isolation technology has been widely investigated to broaden the vibration isolation band by exploiting beneficial nonlinearities.One of the most widely studied objects is the"three-spring"configured quasi-zero-stiffness(QZS)vibration isolator,which can realize the negative stiffness and high-static-low-dynamic stiffness(HSLDS)characteristics.The nonlinear vibration isolation with QZS can overcome the drawbacks of the linear one to achieve a better broadband vibration isolation performance.Due to the characteristics of fast response,strong stroke,nonlinearities,easy control,and low-cost,the nonlinear vibration with electromagnetic mechanisms has attracted attention.In this review,we focus on the basic theory,design methodology,nonlinear damping mechanism,and active control of electromagnetic QZS vibration isolators.Furthermore,we provide perspectives for further studies with electromagnetic devices to realize high-efficiency vibration isolation.

Design and Optimization of the Electromagnetic Actuator in Active-Passive Hybrid Vibration Isolator

The design and optimization of actuators are difficult andcritical for the active-passive hybrid vibration control system. Inthis paper, an electromagnetic actuator model is establishedbased on Ohm’s Law for magnetic circuit considering theleakage flux. The 600N electromagnetic actuators are designedand optimized based on ANSYS simulation according to theengineering request. Its transient characteristics are studied. Theeffects of different structural parameters on its output force areanalyzed. The experimental results show that the structureparameters and output force characteristics of the designedelectromagnetic actuators satisfy the practical requirement.

High-static-low-dynamic stiffness isolator based on an electromagnetic negative stiffness spring with long linear stroke

Negative stiffness mechanisms can improve low-frequency vibration isolation performance and have been widely used in the vibration isolation of precision equipment. However, the negative stiffness mechanism usually introduces a nonlinear stiffness,resulting in a nonlinear response and worsening the vibration isolation performance, especially under large amplitude vibration.In this paper, an electromagnetic spring with linear negative stiffness(ESLNS) is proposed, in which the antagonistic ampere forces of the energized coils are used to generate negative stiffness within a long linear stroke. The magnetic field distribution is improved through the design of the magnetic circuit, thereby increasing the stiffness generation efficiency. The stiffness can be adjusted bidirectionally by current within the range of positive and negative stiffness. An electromagnetic stiffness model was established based on the equivalent magnetic circuit method. Experimental measurements verified the accuracy of the model and proved the linearity of the electromagnetic spring. A vibration isolator with high static and low dynamic stiffness(HSLDS) based on the ESLNS is designed and tested. The experimental results prove that the introduction of the ESLNS can effectively expand the isolation frequency band without changing the equilibrium position. Moreover, the vibration isolator with ESLNS does not produce nonlinear response. The proposed electromagnetic spring with linear negative stiffness extends the application range of HSLDS isolators to a large amplitude vibration environment.

Dynamic interactions of an integrated vehicle–electromagnetic energy harvester–tire system subject to uneven road excitations

An investigation is undertaken of an integrated mechanical-electromagnetic coupling system consisting of a rigid vehicle with heave, roll, and pitch motions, four electromagnetic energy harvesters and four tires subject to uneven road excitations in order to improve the passengers' riding comfort and harvest the lost engine energy due to uneven roads. Following the derived mathematical formulations and the proposed solution approaches, the numerical simulations of this interaction system subject to a continuous sinusoidal road excitation and a single ramp impact are completed. The simulation results are presented as the dynamic response curves in the forms of the frequency spectrum and the time history, which reveals the complex interaction characteristics of the system for vibration reductions and energy harvesting performance. It has addressed the coupling effects on the dynamic characteristics of the integrated system caused by: (1) the natural modes and frequencies of the vehicle; (2) the vehicle rolling and pitching motions; (3) different road excitations on four wheels; (4) the time delay of a road ramp to impact both the front and rear wheels, etc., which cannot be tackled by an often used quarter vehicle model. The guidelines for engineering applications are given. The developed coupling model and the revealed concept provide a means with analysis idea to investigate the details of four energy harvester motions for electromagnetic suspension designs in order to replace the current passive vehicle isolators and to harvest the lost engine energy. Potential further research directions are suggested for readers to consider in the future.

Nonlinear Vibration Isolation of Spacecraft System by a Bionic Variable-Stiffness Device Enhanced by Electromagnetic Component

This study addresses the modified bionic vibration isolation technology by introducing the electromagnetic system to simulate biological damping characteristics.It has been proven effective in improving the vibration environment.By assuming the spacecraft-adapter system as a two-degree-of-freedom system,an excellent simplified model can be derived.The novel bionic vibration isolation device(ABVS-EMVI),which combines an active bionic variable-stiffness device(ABVSVI)with the electromagnetic system,is proposed for the purpose of isolating vibration and harvesting energy at the same time.The dynamic equations of the spacecraft-adapter system with ABVS-EMVI are obtained using the Taylor expansion within the framework of the Lagrange equation,and the harmonic balance method is introduced to acquire the amplitude and voltage response of the system.The results indicate that the electromagnetic system can enhance the vibration isolation performance and provide energy harvesting capabilities.After confirming the ability of ABVS-EMVI to deal with different forms and amplitudes of excitation,the performance of vibration isolation and energy harvesting is investigated in terms of various parameters,and several new conclusions have been drawn.

电磁吸盘-摩擦摆复合隔震支座理论分析与试验研究

为解决摩擦摆支座在外部荷载激励下不具备抗拔性的缺点,基于电磁原理和半主动控制思想,提出了一种以电磁力为基础,结合传统摩擦摆的电磁吸盘-摩擦摆复合隔震支座(Electromagnetic Chuck-Friction Pendulum System,ECFPS)。介绍了该复合隔震支座的构造特点和耗能机制,并基于电磁原理推导出电磁吸盘吸力以及ECFPS的等效刚度、周期和等效阻尼比等理论公式,建立了ECFPS计算模型。设计并制作了一个缩尺比为1∶3的ECFPS试件,对不同输入电流、竖向荷载和不同位移幅值下的滞回性能进行了试验研究,探究了不同输入电流对抗拔性能的影响。试验结果表明:理论值与试验值吻合度较高,验证了理论公式推导的正确性;等效刚度和单位循环耗能变化明显,两者最大变化幅度分别为19.81%和28.16%;随着电磁吸盘输入电流的增大,ECFPS支座的抗拔性能提高,实现了支座竖向抗拔的功能。

特快速空间辐射暂态电磁场测量装置研究

为研究隔离开关操作条件下GIS的瞬态辐射电磁场特性,该文开展特快速高频辐射电磁场测量装置的研制。开关操作辐射电磁场具有上升陡度大、幅值高、频带宽等特点,因此该文选择双锥天线和电小环天线进行电场和磁场的测量,设计特快速辐射电场、磁场与VFTO联合测量方案。通过特快速高频辐射电磁场测量装置对550 kV GIS试验平台隔离开关操作产生的特快速辐射电场、磁场进行测量。结果表明:开关操作时GIS变电站电磁环境极其恶劣,分闸时电场强度可达3.5 kV/m,磁场强度可达220 A/m;合闸时电场强度为2.5 kV/m,磁场强度为150 A/m。单次脉冲持续时间约5μs,主要频率成分为8 MHz,46 MHz,58 MHz。

基于FirmSys平台的优选模块故障分析与防护研究

针对核电站优选模块故障的根本原因,进行深入的理论与工程应用分析。基于电磁兼容(EMC)防护原理及要求,开展干扰源及关键特性识别技术研究。采用继电器隔离的方案防护电磁干扰。增加续流二极管方案防护反向电动势。经试验验证,继电器隔离方案可满足优选模块反馈通道的电磁干扰防护要求,而续流二极管方案可满足优选模块输出通道的反向电动势防护要求。该研究提升了安全级信号采集回路的抗电磁干扰能力、建立了基于EMC试验的强干扰测试技术方案,从而有效解决了在实验室内无法准确产生瞬态干扰的难题。

采用环形变压器的小功率隔离型DC-DC变换器共模电磁干扰噪声建模与抑制

环形变压器具有隔离电容小、易于实现印制电路板(PCB)和集成电路(IC)等优点,在小功率隔离DC-DC变换器设计中的应用日益广泛。实际产品设计中,针对共模EMI噪声的准确预测和有效抑制是至关重要的,而变压器是隔离变换器共模EMI噪声的主要传播通路。然而,目前鲜有针对环形变压器共模电磁干扰(EMI)特性的相关研究,也缺乏针对性的噪声抑制方法。该文针对多种常见于小功率隔离型DC-DC变换器应用的环形变压器对称绕组结构,推导证明其具有统一的对称共模等效集总电容模型。该模型的参数易于获取,且可直接用于预测共模EMI噪声。分析了常用隔离变换器拓扑采用环形变压器时的共模噪声特性,同时给出噪声预测方法,并经实验验证了模型的正确性和有效性。此外,还提出多种环形变压器的共模EMI噪声抑制方法并加以分析,所提方法已在两台样机上得到验证,共模噪声的抑制效果显著。

自修复聚二甲基硅氧烷/单壁碳纳米管电磁屏蔽材料的制备及性能

传统金属屏蔽材料以反射电磁波为主,易产生二次辐射,且存在高密度、高硬度及易腐蚀等问题。因此,开发新型的以吸收电磁波为主的柔性聚合物电磁屏蔽材料成为研究热点。文中利用超声分散辅助液相沉积技术,将单壁碳纳米管包覆在具有动态性的聚二甲基硅氧烷粉末表面,并通过热压工艺制备了复合材料。由扫描电子显微镜分析,表明单壁碳纳米管在聚合物基体中形成了隔离网络结构。通过矢量网络分析仪测试电磁屏蔽性能,单壁碳管质量分数为1%时,在X波段电磁屏蔽性能超过20 dB;当质量分数为5%时,屏蔽效能高达70 d B,而且吸收损耗占比高达93%。此外,复合材料中聚合物基体的动态性与碳管的光电特性相结合,可以实现在热、电、近红外光等多种刺激下的自修复。

系留多旋翼无人机通信系统天线布局及仿真分析

设计了一种适用于系留多旋翼无人机通信系统的天线布局,采用FEKO仿真软件进行了电磁兼容仿真分析,并进行了实装试飞。仿真及实测表明,该天线布局方式可适用于多旋翼无人机通信系统。

采用电磁分流阻尼的反作用飞轮隔振方法设计与分析

反作用飞轮是重要的卫星姿态控制执行机构,也是星上最主要的微振动源。针对反作用飞轮转速范围宽的工作特点,本文提出采用六脚隔振装置结合电磁分流阻尼技术的隔振方法。考虑陀螺效应的耦合作用,建立了反作用飞轮与隔振装置的一体化动力学模型。通过理论分析和数值仿真,研究了陀螺效应对系统的模态、固有频率以及隔振性能的影响,并分析了关键参数对系统隔振性能的影响。开展了隔振优化设计,对优化后的隔振性能进行分析,并对隔振装置中的单个隔振单元进行实验验证,验证了电磁分流阻尼和弹簧刚度对隔振性能的影响。

扫地机器人噪声分析与控制

在开发阶段某扫地机器人在强力和标准模式下存在明显异响,不满足声品质体验要求。针对强力模式,应用频谱分析等方法判断异响频率为风机组件的叶片通过频率(Blade Passing Frequency,BPF),为此通过仿真和试验手段对叶轮进行参数优化,实验与仿真结果具有较好的一致性,同时也成功找到异响解决方案。对于标准模式,采用瞬间通断电等方法论证异响来源于电机定子发出的电磁噪声,并且该电磁噪声通过风机组件中的支架被进一步放大。最终从噪声源和传递路径两方面着手,设计变更绕组连接方式及增加隔振元件两个针对性改善方案,两个方案经验证均有效果。以上分析思路可为扫地机器人噪声控制提供参考。

基于EIS的电磁流量计流体电导率检测方法研究

为了优化电磁流量计传感器2个电极在附加激励源时对流体电导率的测量方法,基于电化学阻抗谱(EIS)分析方法,研究了传感器电极双电层模型时由等效电阻、电容和常相位角元件(CPE)组成的等效回路,通过对模型在频域时的分析,提出了1种激励频率的选择方法和附加激励时的流体电导率检测方法,并设计了1种相应的检测电路,最后通过实验对所提出的方法的可行性进行了验证。

数字磁耦隔离器的磁场抗扰度评价方法研究

在电磁兼容测试领域,缺乏适用于数字磁耦隔离器的磁场抗扰度评价方法。针对此问题,研究数字磁耦隔离器的工作原理,基于电磁兼容原理和IEC等标准,建立一套基于GTEM小室法的针对数字磁耦隔离器的磁场抗扰度评价方法。搭建测试系统,设计电路板,采用测试座法解决抗扰测试中磁场耦合方向不正确和强度不足的问题,定义电平波动和固定0/1两种失效模式和判据,设计结构分析对照表。对GL1200P型号数字磁耦隔离器进行案例验证,验证测试方法可行性,确定器件抗扰失效敏感频率为113 MHz,评级为400 V/m—C级。案例验证说明该方法可以对数字磁耦隔离器抗扰度进行评价。

基于模糊PID控制的准零刚度磁悬浮隔振平台的设计与实现

为有效降低系统固有频率,获得外部振动在多频段的强衰减,以永磁电磁混合作动器为负刚度结构提出并设计了一种准零刚度的磁悬浮隔振平台,实现了基于模糊PID(proportional integral differential)算法的振动主动控制系统.首先,通过特性分析与参数计算,基于准零刚度理论完成了准零刚度磁悬浮隔振平台的方案设计;其次,建立磁悬浮隔振系统模型,提出基于模糊PID算法的振动主动控制策略,可主动调节系统的等效刚度和阻尼;最后,基于Speedgoat实时目标机开发振动主动控制系统,搭建隔振测试平台,并开展了隔振性能测试.研究结果表明:本文设计的准零刚度磁悬浮隔振平台通过采用模糊PID的控制策略能够主动调节PID参数,动态调整系统的等效刚度和阻尼;外部振动频率在20~100 Hz频率段内,振动衰减率大于80%;外部振动频率在100~500 Hz频率段内,振动衰减率大于90%.

多路电磁阀及比例阀驱动接口复用的设计与实现

电磁阀的驱动信号通常是开关量(高电平阀门开通、低电平关断),比例阀的驱动信号通常是脉宽调制(PWM),驱动电流一般在3 A甚至更大。文中设计一种基于数字信号处理器(DSP)TMS320F28335的电磁阀、比例阀驱动系统,创新地设计使用隔离电源模块替代半桥驱动芯片自举电容的方式,实现电磁阀、比例阀驱动接口复用,即一个接口既可以输出开关量信号,也可以输出PWM信号。所设计系统可以驱动多路电磁阀或比例阀,以4路输出驱动接口为例,设计一种基于互锁电路的每一支路硬件过流保护,各支路经过并入串出移位器将其过流状态输入给DSP。试验结果表明,系统不仅占用接口资源少,而且占用片上资源少,具有可靠性和稳定性高等特点,对于片上资源紧缺的项目具有较高的实用价值。

燃料电池空压机用永磁电机降振优化设计

在永磁电机的转动过程中,其气隙处所合成的磁场中能够产生径向电磁力,该作用力可使永磁电机结构中的定子齿部出现振动,产生电磁噪声。为了降低电机振动,采用了基于隔磁磁桥修形的降振优化方法。在Maxwell环境下建立电机的电磁场模型,通过理论推导与有限元计算,确定降振优化方案。结果表明,该方案可以显著提高改进后的电机振动特性,保证了电机的电磁性能。证明了隔磁磁桥修形的降振优化方法的有效性与准确性,可为电机降振优化设计提供指导。

电磁式准零刚度隔振器设计与试验

针对承载质量变化时准零刚度隔振器的综合刚度会偏离设计匹配状态而导致振动放大的问题,利用电磁力稳定输出且便于调节的结构特性,提出一种基于正负刚度并联的电磁式准零刚度隔振器。对电磁负刚度、机械弹簧正刚度、柔性铰链和电涡流阻尼等模块进行结构设计,并对这4个模块的力学特性进行定性分析和有限元仿真,开展电磁式准零刚度隔振器的静态和动态性能试验。结果表明:电磁负刚度的引入使隔振器固有频率由3.00 Hz降为1.75 Hz,在船舶常见特征线谱的激励频率下,线圈电流2 A时能产生45 dB~52 dB的振动衰减效果,为超低频隔振的准零刚度装置原型设计拓展了思路。

航空电磁探测设备隔振系统动力学研究

采用电磁探测技术进行深部勘测时需要收集微弱的低频信号,而隔振系统的动力学特性对信号采集至关重要。基于气压传动原理设计了一种双气室的气缸式空气弹簧隔振系统,对其刚度、频率等力学参数对隔振性能的影响进行理论分析,并基于热力学和流体力学理论建立了隔振系统的非线性动力学特性模型,并对不同横截面积的气缸隔振性能进行了分析,得到了系统在最佳隔振性能时的气缸相关参数。