【作者】 陈智；

【导师】 曲荣海；

【作者基本信息】 华中科技大学 ， 电气工程， 2023， 博士

【摘要】 在数控机床等高端装备制造领域,直线电机作为核心部件得到广泛的关注和应用。推力密度和推力波动是直线电机驱动系统的两个核心性能指标,采用传统的电机拓扑结构和控制算法难以兼顾推力密度的提高和推力波动的抑制,这是制约直线电机推广应用的瓶颈之一。本文针对直线电机驱动系统存在的问题和技术难点,以游标永磁直线电机为研究对象,深入研究磁场调制拓扑提升推力密度的原理,详细推导了推力波动的数学模型,并从控制策略设计的角度对游标永磁直线电机系统的推力波动抑制展开研究。本文首先从磁场调制原理的角度分析了游标永磁直线电机的基本运行原理,然后将直线电机的推力波动分为空载推力波动和负载推力波动,分别研究其产生原理并推导数学模型。空载推力波动为铁心和永磁相互作用产生的固有扰动力,负载推力波动为电流激励产生的扰动力,两种推力波动的产生原理不同,需要对二者进行解耦分析,并采用不同的控制算法实现抑制。本文选取三模块和单模块游标永磁直线电机作为研究对象,其中三模块游标永磁直线电机通过电磁结构设计优化,完全消除了负载推力波动的影响,可以用于空载推力波动抑制算法的验证;单模块游标永磁直线电机具有更简单的电磁结构,但是同时受到空载和负载推力波动的影响,在排除空载推力波动影响的情况下可以用于负载推力波动抑制算法的验证。针对直线电机的空载推力波动问题,本文设计了推力波动观测器和高带宽电流控制器,实现对空载推力波动的精确观测和精确补偿。为了实现对空载推力波动的准确观测,本文将推力波动作为系统的扩展状态,设计了扩展状态观测器。通过合理的参数设计,观测器带宽能够覆盖推力波动的主要谐波,从而实现观测器对推力波动的准确观测。然后将观测的推力波动换算为补偿电流注入电机,补偿电流产生推力和空载推力波动相抵消,从而实现对空载推力波动的补偿。为了提高补偿精度,本文采用谐振电流控制器代替传统电流控制器,实现谐波电流控制精度的提高。实验结果表明,推力波动观测器和谐振电流控制器相结合显著抑制了空载推力波动对控制系统精度的影响,由空载推力波动引起的速度闭环控制误差降低90%。针对直线电机的负载推力波动问题,本文分别研究了谐波电流的分配方法和控制方法。在谐波电流的分配方法方面,本文创新地提出在直线电机控制系统中引入电流负序分量实现对负载推力波动的抑制,并根据负载推力波动的数学模型给出了正、负序电流指令的分配方法。基于所提出的负序电流注入算法,负载推力波动幅值降低60%以上。在负序电流注入算法的基础之上,本文设计了反电势不对称性观测器,并将观测的反电势各分量幅值用于正、负序电流的分配计算,实现负载推力波动抑制算法的在线运行。在谐波电流的控制方法方面,本文创新地提出了一种基于“虚拟绕组”概念的新型谐波电流控制器,解决负载推力波动抑制算法中的正、负序电流闭环控制问题。本文首先将基于辅助绕组的双三相控制系统作为研究对象,分析了双三相拓扑应用于双频电流闭环控制的可行性,然后采用虚拟绕组代替辅助绕组,完成虚拟双三相拓扑控制器的设计,实现对电机正、负序电流的精确闭环控制。在虚拟双三相拓扑的基础上继续引入虚拟三相拓扑,构建基于虚拟多相拓扑的谐波电流控制器,实现多谐波电流的完全解耦以及精确闭环控制,解决了传统谐波闭环控制策略无法兼顾动态响应速度和稳态精度的问题。本文针对游标永磁直线电机中的空载和负载推力波动进行解耦分析并分别设计控制策略。所设计的控制策略有效抑制了推力波动对直线电机控制系统精度的影响,有助于游标永磁直线电机在高端装备制造领域的推广应用。更多还原

【Abstract】 In the field of high-end equipment manufacturing such as computer numerical control machine tools,linear machines have received widespread attention and have been widely used as the core component.Thrust density and thrust ripple are core performance indicators of linear machine drive systems.It is difficult to take into account the improvement of thrust density and the suppression of thrust ripple by using traditional machine topology and control algorithm,which is one of the bottlenecks restricting the application of linear machines.In this thesis,aiming at the existing problems and technical difficulties of the linear machine drive systems,the principle of thrust density enhancement of the linear vernier permanent magnet motor(LVPMM)based on the principle of magnetic field modulation is studied in depth.The mathematical model of thrust ripple is deduced in detail.From the perspective of control strategy,the suppression of thrust ripple is studied.Firstly,the basic operating principle of the LVPMM is analyzed from the perspective of the magnetic field modulation principle.Then,the thrust ripple of the linear machine is divided into the no-load thrust ripple and the load thrust ripple.Their generation principles are studied respectively,and the mathematical models are derived.The no-load thrust ripple is the inherent disturbance generated by the interaction between the iron core and the permanent magnet,and the load thrust ripple is the disturbance generated by the current.The generation principles of the two thrust ripples are different.It is necessary to conduct decoupling analysis and apply different control algorithms for suppression.A three-module LVPMM and a single-module LVPMM are taken as research objects.The three-module LVPMM completely eliminates the influence of load thrust ripple through the optimization of electromagnetic structure.It can be used for the verification of the no-load thrust ripple suppression algorithm.The single-module LVPMM has a simpler electromagnetic structure,but is affected by both no-load and load thrust ripples.It can be used to verify the load thrust ripple suppression algorithm under the condition that the no-load thrust ripple is excluded.To suppress the no-load thrust ripple,a thrust ripple observer and a high bandwidth current controller are designed to achieve accurate observation and compensation of no-load thrust ripple.In order to achieve accurate observation of no-load thrust ripple,the thrust ripple is regarded as the extended state of the system,and an extended state observer is proposed.Through reasonable design of the parameters,the bandwidth of the observer can cover the main harmonic components of the thrust ripple,and the accurate observation of the thrust ripple is realized.The observed value is converted into harmonic current and injected into the machine.The injected current generates thrust and cancels out no-load thrust ripple,and the compensation of no-load thrust ripple is realized.In order to improve the accuracy of compensation,the resonant current controller is used to replace the traditional current controller.Control accuracy of harmonic current is improved.The experimental results show that the combination of the thrust ripple observer and the high-bandwidth current controller significantly suppresses the influence of no-load thrust ripple on the control system accuracy.The speed control error caused by no-load thrust ripple is reduced by 90%.To suppress the load thrust ripple,the distribution method and control method of harmonic current are studied respectively.In terms of the distribution method of the harmonic current,the thesis innovatively introduces the negative-sequence current into the linear machine control system,and the load thrust ripple is suppressed.The distribution method of the positive-and negative-sequence current is given according to the mathematical model of the load thrust ripple.Through the proposed negative-sequence current injection algorithm,the amplitude of load thrust ripple is reduced by more than60%.On the basis of the negative-sequence current injection algorithm,an asymmetrical back-EMF observer is designed in this thesis.The observed values are used for the calculation of positive-and negative-sequence current distribution,and the load thrust ripple suppression algorithm can be realized online.In terms of harmonic current control methods,a novel harmonic current controller based on the concept of "virtual winding" is proposed.The problem of positive-and negative-sequence current control in the load thrust ripple suppression algorithm is solved.Firstly,taking the dual-three-phase control system based on auxiliary windings as the research object,the feasibility of applying the dual-three-phase topology to dual-frequency current closed-loop control is analyzed.Then the virtual winding is used to replace the auxiliary winding,and the design of a virtual dual three-phase topology controller is completed.Precise closed-loop control of positiveand negative-sequence currents is realized.On the basis of the virtual dual-three-phase topology,more virtual three-phase topologies can be introduced.A harmonic current controller based on the virtual multi-phase topology is constructed.Decoupling and precise closed-loop control of multiple harmonic currents are realized.The proposed controller solves the problems that the traditional harmonic closed-loop control strategy cannot take into account both dynamic response speed and steady-state accuracy.In this thesis,the decoupling analysis of no-load and load thrust ripples in LVPMMs is carried out,and thrust ripple suppression control strategies are designed respectively.The designed control strategies effectively suppress the impact of thrust ripple on the precision of the linear machine control systems.It is helpful for the popularization and application of LVPMMs in the field of high-end equipment manufacturing.更多还原