【作者】 储剑波；

【导师】 胡育文；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2010， 博士

【摘要】 永磁同步电动机因其具有结构简单、易维护、运行效率高、调速性能好等优点而在中小功率驱动场合得到了广泛应用。随着近年来对空调系统性能、能效比的要求越来越高,空调系统中驱动压缩机的传统的异步电机已逐步被永磁同步电动机所取代。本文紧紧围绕着驱动空调压缩机的永磁同步电动机这个研究对象展开,针对压缩机的负载特性和节能的目的进行了一些新型控制策略的研究和探索。本文首先描述了静止三相、静止两相与旋转两相坐标系下的永磁同步电动机的数学模型,在此基础上主要分析与探讨了永磁同步电动机矢量控制的原理及其应用较多的SVPWM调制方法,然后简单介绍了直接转矩控制原理。并选择id=0的转子磁场定向的速度和电流双闭环控制方案作为驱动压缩机的永磁同步电动机的一种控制策略。由于空调压缩机内部运行环境十分恶劣,传统的机械式位置传感器已经不能使用,本文利用滑模观测器对永磁同步电机的转子位置和转速进行了实时在线的估算。对滑模观测器的原理做了深入的研究和分析,在α-β坐标系下建立了滑模观测器的状态方程。针对算法中出现的抖振现象以及转速计算精度不高的问题,采用了以近似饱和函数取代开关函数以及锁相环代替直接微分计算转速的改进方法。为了降低空调系统中驱动压缩机的永磁同步电动机的能量消耗,本文在驱动压缩机的永磁同步电动机的控制中使用了基于瞬时功率开关表进行直接功率控制的新策略。该策略根据定子磁链所在扇区、瞬时有功功率和瞬时无功功率的两个滞环输出,查询瞬时功率开关表选取合适的空间电压矢量进行输出,从而对瞬时功率进行直接控制达到调速的目的。实验结果表明,该策略可以将无功功率控制在零附近,提高电机的功率因数。在永磁同步电机驱动的单转子压缩机变频空调系统中,呈周期性波动的负载转矩使得永磁同步电机的转速产生同周期的脉动。在低速运行时,速度脉动引起的整个空调系统框架的振动、高噪声等现象尤其明显,同时降低了系统的效率。本文在分析了这类周期性负载扰动对系统速度稳定度的影响的基础上,基于重复控制原理的动态补偿方法提出了在永磁同步电机速度控制环上采用一种重复控制和PI控制相结合的复合控制方案,以抑制周期性负载扰动引起的转速脉动。该方案在稳态时采用重复控制加PI控制以获得较好的稳态性能,而在动态过程中以PI控制作用为主来获得良好的动态响应。仿真和实验结果证明了该控制方案的可行性、正确性并具有很强的工程实用意义。在电动机控制中,三相电流采样是一个核心环节。为了降低变频空调控制器成本、减少其体积,提高效率,本文根据相电流、直流母线电流及逆变器开关状态之间的关系,给出了一种基于单电阻采样直流母线电流的方式进行电机相电流重构的方案。该方案通过空间电压矢量移相的方法解决了三相电流重构的难点。仿真和实验结果表明该方法的有效性和正确性。借助于Matlab软件和全数字控制硬件平台,对上述的理论和策略进行了仿真和实验验证。更多还原

【Abstract】 Permanent Magnet Synchronous Motor(PMSM)has been widely used in motor drive occasions because of its simple structure,easy maintenance, high efficiency, excellent performance. With the air-condition system performance and energy efficiency is becoming increasingly demanding in recent years, the traditional induction motor used in compressor has gradually been replaced by permanent magnet synchronous motor. This paper focuses and elaborates on permanent magnet synchronous motor-driven compressor, and explores new control strategies for the compressor load characteristics and energy-saving purposes.This paper first describes permanent magnet synchronous motor mathematical model in the static three-phase, two-phase stationary phase and two-phase rotating coordinate system. The vector control theory of PMSM and SVPWM modulation method are analyzed and discussed in detail. The principle of direct torque control is then introdued in brief. The rotor flux orientation method of id = 0 is selected to achieve the speed and current dual closed-loop program for permanent magnet synchronous motor-driven compressor system.As the air-conditioning compressor within the operating environment is very poor, the traditional mechanical position sensors can no longer be used, so sliding mode observer is used in this paper to estimate the rotor position and speed of PMSM real-time online. The principle of sliding mode observer and its model of PMSM in theα-βcoordinate system are also analyzed in detail. For chattering phenomenon and the speed of calculation accuracy is not high, approximate saturation function and differential phase-locked loop are used to replace the switching function and directly differential calculation method respectively.In order to reduce energy consumption of PMSM-driven compressor in air-conditioning system, a new strategy namely direct power control is proposed to achieve energy-saving purpose in this paper. Based on the analysis of relationship of the active power、reactive power、torque and stator flux-linkage, the direct power control (DPC) control method for PMSM is studied in detail. It selects optimum space voltage vector to control the instantaneous power through optimum switching table which based on the sector of flux linkage and the output of the active and reactive power hysteresis. The goal of the method is to control reactive power as zero and improve power factor at the same output of active power. Both the results of simulation and experiment show the good performance and accuracy of the proposed method. For a common permanent magnetic synchronous motor (PMSM) single rotor compressor system, cyclical fluctuation of the load torque causes the ripples of speed at the same cycle. The vibration of the air-conditioning system framework, high noise et al. phenomenon caused by the ripple speed is particularly evident when compressor running at low speed. And the efficiency of the system comes down at the same time. After analysis the impact on the system stability of such periodic speed disturbances in detail, a new method aiming to suppress the pulsation of the speed caused by periodic torque disturbance is proposed in this paper. A composite controller consisting of PI controller and repetitive controller which are paralleled together is placed in the speed loop. The PI controller and repetitive controller are used together in the steady-state for better performance of the steady-state, and PI controller is mainly to obtain good dynamic response when non-periodic disturbance appears. Simulation and experimental results show the feasibility and validity of the control program.The sampling of phase current is a core part in motor control. In this paper three-phase current measurement using only a single current sensor in the inverter dc link is proposed based on the relationships among the phase current, DC bus current and inverter switch states, it can minimize the number of current sensors, reduce sensor cost, weight, and volume. The new single current sensor algorithm can solve the difficulty in three-phase current reconstruction by space voltage vector phase-shifting. Simulation and experimental results show that the method is effective and correct.By means of Matlab software and digital control hardware platform, the above-mentioned theories and strategies are verified through simulations and experiments.更多还原