【作者】 张建国；

【导师】 李杨民； 隆志力；

【作者基本信息】 哈尔滨工业大学 ， 控制科学与工程， 2019， 博士

【摘要】 随着先进材料和高新技术的不断发展,特种加工制造技术逐渐成为发展国家工业、航空航天和军用产品的关键技术。旋转超声加工是特种加工制造技术的重要组成部分,旋转超声加工技术应用于数控机床加工硬脆材料和先进复合材料等,具有加工效率高和加工切削力小等优点。松耦合变压器是旋转超声加工技术实现非接触式无线能量传输的关键部件。然而,在研究中发现采用松耦合变压器的方法存在超声刀柄建模困难、等效参数受环境影响大、控制复杂度高的问题,为相关的研究工作带来了较大的挑战。本文主要研究了超声驱动系统设计、超声换能器等效负载模型、松耦合变压器补偿优化和机械振幅控制算法等关键性的理论与技术问题,其主要工作如下:针对超声加工中超声换能器工作功率较大的特性,设计了面向旋转超声加工领域的变频式超声波驱动器,其可以在多频带内驱动不同的超声加工刀柄,智能搜索驱动部件的最佳工作频率并且实现动态锁相。开发的硬件电路包括控制最小系统、信号发生电路、有效值采集电路和相位采集电路等。旋转超声加工刀柄由松耦合变压器和超声换能器组成,基于开发的超声驱动系统,研究了超声换能器在不同电压驱动下其频率阻抗特性变化趋势。通过实验分析了超声换能器的输入电流和输出振幅在不同频率驱动时动态对应关系,证明了超声换能器的输入电流和输出振幅呈正相关关系。研究了超声刀柄和超声换能器两者的谐振频率与阻抗偏差的问题。这种偏差问题会导致超声刀柄在谐振频率驱动时,输出电压、电流在初始时振荡以及稳态时衰减现象。为了分析超声换能器的负载特性,构建了超声换能器的机电等效阻抗模型,其对超声换能器的谐振频率和阻抗特性具有指导设计的作用。本文分析了超声换能器中夹紧螺母的预紧扭矩和加工工具伸出长度对于其频率阻抗特性的影响趋势。基于超声换能器的等效动力学模型和电学等效模型,建立了超声换能器等效传递函数模型。通过电机运动平台、力传感器和阻抗分析仪等测试设备搭建了切削力测试平台,获得了超声换能器在不同切削力下超声换能器的电学等效特性。发现随着切削力的增大,超声换能器的谐振频率和阻抗在一定范围内随之增大,超声换能器的等效传递函数模型也发生改变。基于线性参数拟合方法,建立了换能器的动态传递函数模型,该动态阻抗模型较好的解释了超声换能器在负载下电流响应特性。为了解决旋转超声加工系统中超声刀柄与超声换能器的谐振频率和阻抗的偏差问题,提出了利用两种补偿结构实现无线能量传输补偿:双边补偿和单边补偿。在双边补偿结构中,构建了基于T型等效电路的松耦合变压器的漏感等效模型。基于零相位等高线法,直观地发现四种补偿结构下,双边补偿存在多个解的问题。为了消除谐振频率和阻抗的偏差,建立了多目标优化数学模型。基于Pareto边界方法,获得了超声刀柄相位、超声刀柄与超声换能器之间阻抗差的最优分布。基于多目标遗传优化算法,优化双边补偿的电容值,发现串联-串联补偿的优化电容值消除了超声刀柄与超声换能器之间谐振频率和阻抗的偏差。构建了四种补偿结构的状态空间方程获得了超声刀柄振动系统的动态响应特性,分析了不同拓扑的输出电压和输出电流响应趋势。构建了超声刀柄振动系统的MATLAB仿真平台,其全方位的分析了超声刀柄输入输出电压、电流和相位差的瞬态响应曲线。通过实验证明了串联-串联补偿结构使得松耦合变压器电压增益从无补偿的0.333提高到0.920。与没有补偿时相比,输出有功功率提高了7.634倍。超声刀柄阻抗监控切削力的灵敏度提高,监控切削力的阻抗上升速率从1.151提升至1.823。在单边补偿结构中,提出一种原边补偿的方法,实现超声刀柄和超声换能器的谐振频率和阻抗同时匹配。基于松耦合变压器T型网络漏感等效模型,松耦合变压器在一定的空气间隙范围内,随着空气间隙距离增大,其线圈自感和等效串联电阻呈指数下降、漏感呈直线上升的趋势,在用原边串联补偿结构时,松耦合变压器的输出电压增益增大。基于以上松耦合变压器的物理特性,对超声刀柄在扫描频率和谐振频率驱动的电压、电流响应进行理论计算和实验验证。通过实验表明,相比于无补偿时,采用原边串联补偿方法,电压增益从0.267增加到0.90,输出有功功率提高了11.3倍,监控阻抗的灵敏度提高了1.54倍。在原边串联补偿的基础上,通过实验发现超声刀柄和超声换能器的谐振频率与阻抗的偏差会随着外部切削力增大而增大。本文提出了模糊PID神经网络自校正算法,使得超声刀柄振动系统在不同切削力下,可以追踪超声换能器的谐振频率,通过实验验证了该算法的可行性。为了解决超声振动系统在切削力作用下衰减的问题,基于自抗扰控制器实现超声刀柄振幅恒定输出。建立了MATLAB仿真平台,研究了在无负载和噪声干扰下的电流响应曲线变化趋势。通过实验分析了自抗扰控制器跟踪微分器、状态扩张观测器和状态误差反馈控制器不同参数在无负载下对于电流响应曲线的影响,验证了在不同切削力下,自抗扰控制器对于电流响应的影响。保证超声刀柄振动系统振幅实现恒定无衰减输出。搭建了加工实验平台,验证了本文建立的超声加工系统的有效性。更多还原

【Abstract】 With the development of advanced materials and new high technology,special processing technology has gradually become a key technology for the national industrial,aerospace and military product technologies.Rotary ultrasonic machining(RUM)is an important part of special processing.RUM technology is applied to CNC machining machines for processing hard and brittle materials and advanced composite materials with high processing efficiency and small cutting force.The loosely coupled transformer is a key component of RUM for contactless energy transmission.However,it is found that the method of loosely coupled transformer features difficult modeling of ultrasonic tool holder,equivalent parameters are greatly affected by the environment and high control complexity.It brings great challenges to related research work.The key theoretical and technical problems of ultrasonic driving system design,equivalent impedance modeling of ultrasonic transducer,loosely coupled transformer compensation optimization and vibration amplitude control algorithm are studied in this dissertation.The main work is as follows:Aiming at the high operating power of ultrasonic transducers in rotary ultrasonic machining,a variable frequency ultrasonic driver for the rotary ultrasonic machining is designed to drive different ultrasonic tool holders in multiple frequency bands,intelligently search for the optimal operating frequency of the driving components,realize dynamical phase locking.A control minimum system,a signal generation circuit,an RMS acquisition circuit,and a phase acquisition circuit are included in the self-developed hardware circuit.The rotary ultrasonic machining tool holder consists of a loosely coupled transformer and an ultrasonic transducer.The frequency impedance characteristic of ultrasonic transducer under different voltages is studied based on the developed ultrasonic driving system.The dynamic correspondences of input current and output vibration amplitude are analyzed under different frequencies.It is proved that the input current and output vibration amplitude of the ultrasonic transducer are positively correlated.The problem of resonant frequency and impedance deviation between the ultrasonic tool holder and the ultrasonic transducer is investigated in this dissertation.This deviation problem causes the output voltage and output current both oscillate at the initial moment and attenuate at the steady time when the ultrasonic tool holder is operated at the resonant frequency of ultrasonic transducer.To analyze the equivalent load characteristics of ultrasonic transducers,an equivalent impedance model of ultrasonic transducer is constructed to predict the resonant frequency and impedance characteristics of ultrasonic transducers.The effects of the tightening torque of the clamping nut and the extension length of the machining tool on the resonant frequency and impedance of ultrasonic transducer are analyzed in this dissertation.An equivalent transfer function model of the ultrasonic transducer is established based on the equivalent dynamics model and the electrical equivalent model.The cutting force testing platform is established by a motor motion platform,a force driver and an impedance analyzer.The electrical equivalent parameters of the ultrasonic transducer under different cutting forces are obtained by the testing platform.It is found that the resonant frequency and impedance of the ultrasonic transducer increase as the cutting force increases.The equivalent transfer function model of the ultrasonic transducer varies with the cutting force.Based on the linear parameter fitting method,the dynamic transfer function model of the transducer is established.It is found that the dynamical transfer function model can better describe the current response characteristic of the ultrasonic transducer under different external cutting forces.In order to solve the deviation of the resonant frequency and impedance between the ultrasonic tool holder and the ultrasonic transducer in the RUM system,two compensation topologies are proposed to realize the compensation of wireless power transfer system: bilateral compensation and unilateral compensation.In the bilateral compensation structure,an equivalent leakage inductance model of a loosely coupled transformer based on T-network leakage inductance equivalent circuit is constructed in this dissertation.Based on the zero-phase contour line method,it is found that the bilateral compensation exists multiple solutions problem in four compensation topologies visually.A multi-objective optimization mathematical model is established to eliminate the deviation of resonant frequency and impedance in this dissertation.Based on Pareto frontier method,the optimum distribution of phase difference of ultrasonic tool holder,and impedance difference between ultrasonic tool holder and ultrasonic transducer is obtained in this dissertation.Based on a multi-objective genetic optimization algorithm,the compensation capacitance values are optimized in bilateral compensation topologies.It is found that the optimization capacitance values of series-series compensation topology can solve the problem of resonant frequency and impedance deviation between the ultrasonic tool holder and the ultrasonic transducer.The state space equations of four topologies are constructed to analyze the dynamic response characteristics of ultrasonic tool holder vibration system.Therefore,the output voltage and output current response trends of different topologies are analyzed.The MATLAB simulation platform of the ultrasonic tool holder vibration system is constructed to comprehensively analyze the transient response curves of the input and output voltage,current and phase difference of the ultrasonic tool holder.It is proved that the voltage gain of loosely coupled transformer is improved from 0.333 to 0.920 by the series-series compensation structure in the experiments.Compared with no compensation case,the output active power is increased by 7.634 times,the monitoring sensitivity of the ultrasonic tool holder for the external cutting force is improved,and the rising rate of impedance for monitoring cutting force is improved from 1.151 to 1.823.In the unilateral compensation topology structure,a novel primary side compensation method is proposed to achieve double compensation of the resonant frequency and impedance between the ultrasonic tool holder and the ultrasonic transducer.Based on the T-type network equivalent leakage inductance model of loosely coupled transformer,the coil self-inductance and the equivalent series resistance decrease exponentially,and the leakage inductance linearly rises as the length of air gap increases within a certain range.When the series compensation structure in primary side is used in the ultrasonic tool holder,the output voltage gain of the loosely coupled transformer is increased.The theoretical calculation and experimental verification of the response state of the ultrasonic tool holder driven at the sweeping frequency and the resonant frequency are carried out based on the physical characteristics of the loosely coupled transformer.Compared with the uncompensated case,the voltage gain is increased from 0.267 to 0.90,the output active power is increased by 11.3 times,and the sensitivity of impedance for monitoring cutting force is increased by 1.54 times based on the series compensation in primary side.The deviation of the resonant frequency and impedance of the ultrasonic tool holder and the ultrasonic transducer increases as external cutting force increases based on the primary series compensation topology.The fuzzy PID neural network self-correction algorithm is proposed to track the resonant frequency of ultrasonic transducer under different cutting forces,the feasibility of this algorithm is verified by experiments in this dissertation.In order to solve the vibration amplitude attenuation problem of ultrasonic vibration system under the cutting force,the auto disturbance rejection controller(ADRC)is proposed to realize the constant vibration amplitude output of the ultrasonic tool holder.The MATLAB simulation platform is established to achieve the current response curves of ultrasonic tool holder vibration system under no load and noise interference.The effects of different parameters of tracking differentiator,extended state observer and state error feedback controller of ADRC on the current response curve under no load are verified by experiments,and the effects of ADRC on the current response is verified under different cutting forces in this dissertation.The ultrasonic tool holder vibration system is verified to keep the constant vibration amplitude without attenuation.A machining experimental platform is built to verify the effectiveness of the ultrasonic machining vibration system.更多还原