【作者】 张士雄；

【导师】 皮佑国；

【作者基本信息】 华南理工大学 ， 控制理论与控制工程， 2010， 博士

【摘要】 本文研究数控机床进给轴用高性能伺服驱动控制技术。现代数控机床用高性能伺服系统均采用永磁同步电动机,并采用SVPWM控制方式。本文针对数控机床对伺服系统的高性能要求,深入分析了数控机床的进给机械、永磁同步电动机和基于SVPWM的逆变器的运动机理、数学模型和存在的时变、线性和非线性扰动。研究了高性能伺服驱动系统中常规系统建模假设的适用程度；重点分析了PWM引起的转矩脉动对加工质量的影响、伺服电动机控制策略中存在的Iq和Id不解耦对转矩的影响；各轴参数一致性,尤其是通过工件强耦合时各轴一致性和协调性对加工性能的影响。在此基础上,以数学模型和分析描述相结合研究了数控机床进给伺服驱动的模型。深入分析和研究了SVPWM逆变器的工作机理。逆变器是实现永磁同步电动机SVPWM控制的基础,而PWM是通过一定频率的载波进行脉冲宽度调制实现的。每一个正弦波都是由数个脉冲合成。这种方式必然引起谐波,尤其是在低速时会导致转矩、转速的波动,并直接影响到数控机床的加工性能。本文在深入分析载波频率对转矩的影响以及受功率器件特性的限制基础上,研究了兼顾开关特性和驱动器性能的载波频率自适应优化方法。深入分析了基于SVPWM控制的交流伺服电动机驱动系统。矢量控制基本的假设是转矩电流Iq和励磁电流Id解耦,而电动机本身是一个强耦合的一体化对象,并存在一些非线性因素和时变因素影响。本文在对电动机的数学模型和非线性、时变因素,以及SVPWM控制机理进行深入分析的基础上,对转矩电流Iq和励磁电流Id的耦合及其解耦方法进行了研究,并针对电动机参数时变和存在的扰动研究了相应的自适应控制策略。伺服系统是一种典型的控制系统,本身对包括稳定性、快速性和精度等跟随性能有较高的要求。除了上述驱动器本身的性能要求外,由于数控机床进给轴通过工件强耦合在一起,数控机床的加工过程需要各进给轴的精确配合才能完成高性能的加工任务。这就决定了在数控机床伺服驱动的速度控制器设计中除了保证系统本身具有优秀的品质外,还要保证各个轴之间的一致性和协调性。而在实际加工过程中,由于在各进给轴上惯量不同且随工件变化、所受的扰动也不尽相同,Z轴和其它两轴间的耦合时断时连,这些都给速度环的控制器设计增加了难度。本文在对控制对象模型及其所受扰动进行分析研究的基础上,研究了基于模型参考机理的速度控制器和补偿器的设计。在理论分析和仿真研究的基础上,为了实际验证所作理论分析与仿真研究的效果,并完成省部产学研资助项目的任务,本文设计和制作了实际的伺服驱动装置,并安装在广州诺信数控设备有限公司生产的XKHL650型立式加工中心上,为本文搭建了实际的研究平台。对每一科学问题和控制策略,均利用开发的驱动装置进行实验研究,最后在加工中心上,进行实际的加工调试和测试。本文介绍了相应的实验过程及部分实验结果。更多还原

【Abstract】 This dissertation focus on high-performance servo drive for feeding of NC(Numerical Control) machines. PMSM and SVPWM technique are applied into almost all the modern NC machines. Due to the high-performance demand of NC machines, the feeding mechanism, PMSM, SVPWM-based inverter and disturbances are deeply analyed. The range of application for mathematical assumes in high-performance servo drive is studied. Influences of torque ripple caused by PWM and coupling between Iq and Id are selectively analysis. Parameter differences among difference axis will cause bad machining effect, especially when couplling existing through workpieces. Researches on mathematical model and descriptions of NC machine feeding servo drives are carried out.The principle of SVPWM inverter work principle is further analyed and studied. Inverter is the basis of SVPWM. PWM is achieved by a certain frequency carrier. Every sine wave is composed of some pulses. Harmonics are caused by this approach inevitablely, especially in low speed section; torque and speed ripples are generated, which deteriorate machining performance. The effect of carrier frequency is analyed. Based on this, the switching characters and carrier frequency control methods are studied.AC drive systems based on SVPWM is deeply analyed. The basis of vector control is the decoupling between Iq and Id, while AC servo motor is a close coupling object. At the same time, some nonlinearities and time-variable factors exist. Based on the analysis, coupling between Id and Iq and decoupling methods are studied in this dissertation. Adaptive control strategies are studied aiming at the time-variable character of the servo motor.As a kind of typical control system, servo system has high performance demanding on stability, rapidity and precision. The feeding axis of NC machines are coupled through workpieces. Exactly coordinating multi-axis is needed during the high-performance machining process. Hence, besides the excellent characters of the system itself, consistency must be kept. During the machining process, initia variation with workpieces, different disturbances on every axis, and the coupling between Z-axis and the others axis on and off, all this set handicaps for system designing. Adaptive control principle-based speed controller and compensator are studied based on the disturbances analysis. To validate the effect of analysis and simulation results and accomplish the Enterprise-College-Research(ECR) cooperation project, real servo drives are made based on the analysis and simulations. The XKHL650 vertical machining centre(VMC) with the drives are setup as the test bench. All the control strategies are validated on this bench. At last, three typical workpieces are machined by this VMC. The experiments and part of experiment results are shown in this dissertation.更多还原