【作者】 杨建飞；

【导师】 胡育文；

【作者基本信息】 南京航空航天大学 ， 电机与电器， 2011， 博士

【摘要】 永磁同步电机由于具有高效率、高功率密度、高转矩惯量比等特点，在各种调速系统中应用越来越广泛，研究分析高性能的永磁同步电机驱动系统具有十分重要的经济和社会意义。目前，在高性能永磁同步电机调速领域，研究较多的主要有两种控制方案：一种是矢量控制，也称为磁场定向控制(FOC)；一种是直接转矩控制(DTC)。众所周知，对电机的控制本质上是对电机转矩的控制，矢量控制主要通过对电机直交轴电流的控制来间接控制转矩，实现过程中要求严格的磁场定向，而直接转矩控制则是将电机和逆变器作为一个整体，直接以转矩为控制对象，通过优选的空间电压矢量实现对电机转矩的直接控制。直接转矩控制技术首先是针对异步电机提出并得到成功应用的，直到1997年才由南京航空航天大学和澳大利亚新南威尔士大学合作提出了正弦波永磁同步电机DTC方案，该方案自提出后迅速成为热点研究问题。本文的研究内容就是围绕永磁同步电机DTC技术展开，以正弦波和方波永磁同步电机为研究对象，对采用DTC时的若干关键问题进行理论分析和仿真实验研究，为永磁同步电机DTC技术的进一步发展和工程应用打下坚实的基础。本文研究内容如下：对永磁同步电机DTC技术国内外研究现状进行了综述，指出，目前对正弦波永磁同步电机DTC研究的广度和深度都已经达到一个新的高度，涉及的方向很多，内容非常丰富，大致可以归纳为下面几个方向：降低转矩脉动方法的研究；无传感器运行的研究；定子磁链控制方法的研究等。而对于方波永磁同步电机，由于电机电流非正弦，存在关断相等特点，在采用DTC方法时有其特殊性，近几年正逐渐成为研究热点。介绍了正弦波永磁同步电机不同坐标系下的数学模型和传统DTC的基本理论，给出了不同定子绕组连接方式下传统DTC方法的实现过程。针对采用DTC时首先需要解决的参数测定问题，详细介绍了一种DTC条件下额定定子磁链幅值等重要电机参数的测定方法，分析了不同运行条件下参数的变化规律，并进行了实验验证。该方法对一般DTC下电机参数的确定具有借鉴意义，有助于推动直接转矩控制的进一步工程应用。针对正弦波永磁同步电机传统DTC在数字控制条件下的特点，在分析定子磁链幅值、转矩角和转矩变化规律的基础上，以降低稳定运行时的转矩脉动和减少起动时间为目标，提出了一种DTC转矩调节器设计方法，该方法既保证了电机稳定运行时较低的转矩脉动又实现了电机具有较短的起动时间，仿真和实验验证了该方法的正确性和有效性，对一般电机DTC中转矩调节器的设计具有指导意义。针对传统DTC中磁链幅值恒定，转子永磁体单独励磁的特点，从减少无功电流，降低电机损耗，提高电机效率角度出发提出了一种磁链自适应DTC方法，实现了在满足负载转矩要求的条件下对定子磁链给定的动态调整，通过在线实时调整定子磁链给定保证了电机在运行过程中始终具有较少的无功电流和较高的功率因数，仿真和实验验证了该方法的可行性和有效性。从正弦波永磁同步电机传统DTC方法的实现过程不难看出，其还是受到了异步电机DTC方法的影响，仍然采用磁链和转矩双闭环的不解耦控制方式。而正弦波永磁同步电机中转子永磁体磁链为定值，定子磁链幅值和转矩角均为可控变量，因此，实现直接转矩控制的方法不唯一。对不同转矩控制方法进行了分析和比较，提出了一种无磁链闭环DTC方法，该方法实现过程中直接根据转矩的控制要求选择最优空间电压矢量，实现了对转矩更快更准确的控制，省去了磁链控制环节。仿真和实验证明了该方法的正确性和可行性，为DTC的进一步研究提供了参考。方波永磁同步电机由于变量的非正弦，存在关断相等特点，使得在采用DTC方法时有其特殊性。在实现直接转矩控制方法时，只要根据转矩控制要求选择交轴分量最优的空间电压矢量作用于电机即可实现对转矩的快速控制，无需观测定子磁链。为保证电机稳定运行，在无磁链观测条件下需要对电流进行限制，由于采用120度导通方式，通过控制转矩能够实现对电流的限制。仿真和实验验证了提出的无磁链观测DTC方法理论的正确性和方法的可行性，为进一步提高方波永磁同步电机DTC的性能奠定了基础。基于TI公司高性能数字控制器设计了永磁同步电机实验平台，不同控制策略下进行的实验证明了该平台的可靠性。更多还原

【Abstract】 Permanent magnet synchronous motor has been widely applied in various AC drive systems for itsmerits of high efficiency, high power density and high torque/inertia ratio and the research ofpermanent magnet synchronous motor drive system with high performance deserves importanteconomy and society value.At present, there are mainly two control schemes in high performancedrive systems: one is vector control or called field orientation control, and the other is direct torquecontrol(DTC).As known, the essence of motor control is the control of motor torque.In vector controlscheme, the torque control is indirectly achieved by the control of d-axis and q axis current,in thisprocess,the accurate flux linkage orientation is needed.And DTC method considers the motor andinverter as a whole,and controls the torque directly by applying the optimal voltage vectors. DTC waspresented and applied in induction motor firstly and the DTC method for sinusoidal permanentmagnet synchronous motor was not presented until1997which was introduced by Nanjing Universityof Aeronautics and Astronautics and University of New South Wales. DTC has been the hot researchissuse since it was introduced.The main content of this thesis is about direct torque control ofpermanent magnet synchronous motor.Both of the sinusoidal and trapezoidal motors areresearched.The theoretical analysis, simulation and experiments are taken to solve the key issues indirect torque control of the two motors which helps to laying the foundation for further developmentand application of DTC.The main research issues are as follows:The research of permanent magnet synchronous motor at home and aboard is reviewed.It ispointed that the width and depth of DTC research on sinusoidal motor have been a new level,manysubjects are included and the content is very rich, and they can be roughly divided into three subjects:the research about torque ripple reduction; the research about sesorless operation;the control of statorflux linkage and so on.But for the trapezoidal motor,there is some specificity with DTC for thenon-sinusoidal voltage and current,and the turn-off phase.And the research of DTC of trapezoidalmotor has been the hot research issuses.The models of sinusoidal permanent magnet synchronous motor under different coordinate systemsand the traditional direct torque control basic theory are introduced,and the implementation procseesof traditional DTC with different stator winding connection styles are presented.With respect to theproblem of parameter determination,taking a sinusoidal permanent magnet synchronous motor forinstance, a parameter determination method for DTC is introduced detailedly.And the parametervariation under different situations is analyzed and the results are verified by the experiments.Theproposed parameter determination method is helpful for the normal DTC application.The characteristics of traditional DTC for sinusoidal motor under digital control are analyzedincluding the stator flux linkage variation,torque angle variation and the torque variation.The resultsshow that: the lag control of stator flux linkage exits in digital congrol system;the influence of rotorflux linkage positon variation can not be neglected under high speed operation;and the control ofmotor torque by voltage vectors shows the positive and negative asymmetry; the maintenance strengthof zero voltage vector to the torque depends on the motor speed.On the base of analysis of traditionalDTC,a torque regulator design method is proposed, and low torque ripple and short starting time can be achieved with this method,simulation and experiment results validate the regulator designmethod.The torque regulator design method provides the guidance for normal torque regulator designin DTC.Taking the non-salient pole sinusoidal permanent magnet synchronous motor for example,therelationship between stator flux linkage d-axis and q-axis components and motor torque.A stator fluxlinkage adaptive direct torque control is presented, in this method,the stator flux linkage referenceadaptive control is achieved,meanwhile, it also meets the requirement of load torque,and high powerfactor is gained.Simulation and experiment results verified the effectiveness and validity.It can be seen from sinusoidal permanent magnet synchronous motor traditional DTC that itsimplementation is still affected by induction motor DTC,in which flux linkage and torque close loopcontrol method is adopted.In fact, the amplitude of stator flux linkage and torque angle arecontrollable variables while the rotor flux linkage is constant in sinusoidal permanent magnetsynchronous motor,therefore,the implementation of DTC is not unique.After analyzing andcomparing different methods,a DTC method without flux linkage close loop control is presented.Themain feature of optimal direct torque control is that the rapid torque response is achieved bycontrolling the stator flux linkage q-axis component directly,and the optimal voltage vector is selectedaccoding to the torque requirement only,in this method,the flux linkage control loop iseliminated.The optimal control of torque is achieved by making using of the characteristic of constantrotor flux linkage in sinusoidal motor.This method provides the reference for further research in DTC.The direct torque control method of trapezoidal permanent magnet synchronous motor has its ownspecificity for the non-sinusoidal voltage and current,turn-off pahse.The torque variation is analyzedfrom the normal torque expression of trapezoidal motor, and the results show that the amplitude offlux linkage vector which is induced from rotor flux linkage is not constant,it is the function of rotorpositon.And for a certain rotor position,the torque variation is only decided by the variation of statorflux linkage q-axis component.Therefore,the direct torque control of trapezoidal motor can beachieved by choosing the voltage vector which the q-axis component is optimal according to therequirement of torque control,and there is no need to observe the stator flux linkage.And the currentlimitation is achieved by control the motor torque under120degree conduction mode.Theeffectiveness and validity of the proposed DTC method without flux linkage observation is verified bythe simulation and experiment results.The permanent magnet synchronous motor general experiment platform is designed based on TIhigh performance digital controller, and the stability is verified by different experiments mentionedabove.更多还原