【作者】 王硕；

【导师】 吴爱国； 王显明；

【作者基本信息】 天津大学 ， 控制工程， 2014， 硕士

【摘要】 当今全球能源的消耗主要来源于在工业现场中的各类电机。永磁无刷直流电机具有更高的工作效率以及功率密度，加之成本低，体积小，使用寿命长，维护方便，抗干扰强等显著优点，受到了广泛的关注，成为了电机市场发展的方向。直流无刷电机由于采用方波驱动，再加上换相过程中由于电感的存在，电流不能突变，在换相时刻会产生转矩脉动，这限制了直流无刷电机应用于具有较高的动态特性和静态特性要求的场合，如何抑制换相引起的转矩脉动一直是直流无刷电机的研究热点与难点。本文详细分析了直流无刷电机的数学模型，在模型基础上着重推导了无刷电机的构造中点相对真实中性点的数学关系，本文在现有模型的基础上，在直流无刷电机的PWM调制作用下，对端电压的实验波形形成原因进行了分析，以及PWM调制作用对电机中性点电压的影响，对比永磁同步电机的中性点，指出直流无刷电机的中性点电压会形成方波与梯形波交替的复杂波形。在无刷电机的换相过程中，本文对转矩脉动的形成原因以及数学关系进行了分析，由于电感的作用，换流过程中换相电流的上升速率和下降速率的不相等，可以产生换相转矩脉动，针对转矩脉动问题，采用直接转矩控制方法控制直流无刷电机的动态转矩，通过Simulink下仿真建模得到仿真波形，对圆锯齿磁链的形成原因进行了分析，分析并提出了不同滞环宽度对系统的设计的影响，通过Simulink仿真对比双闭环调速方法，结果证明了直接转矩控制方法减小了转矩脉动，加快了电机转矩动态响应速度。在系统需求分析条件下，构建了基于TMS320F2812的直流无刷电机控制系统平台。自行搭建了整流、逆变电路，自行构建了三层结构的无刷电机控制器。在该硬件基础条件下，可以实现电压和电流的采样，PWM的产生、通信接口、过流过压保护、外部中断、位置信号的捕获等。在硬件实验平台的基础上，利用C语言在CCS编译环境下完成了系统软件的编写，包括，电机启动程序，PI调节程序，AD采样滤波程序、换相中断程序及系统保护中断程序等，通过对比例积分参数的调整，转速可以平稳的达到转速的设定值，转速快速性和稳定性良好。最后，利用自行搭建的实验平台，给出了无刷电机在实际运行中的实测波形，并对实验结果进行了分析。实验结果验证了该控制方法在无刷直流电机控制系统的正确性和有效性。更多还原

【Abstract】 Nowadays, global energy consumption is mainly comes from all kinds of motorsin industrial field. Permanent magnet brushless dc motor (BLDC) has higherefficiency and power density, in addition to the other significant advantages like thelow cost, the small volume, the long life, easy maintenance, and stronganti-interference, which receives widespread attention and has become thedeveloping direction of the motor market. Because of the square-wave drive and theexistence of inductance during the commutation process, the current of the brushlessdc motor can’t mutate. Torque ripple is produced, which limits the brushless dc motorto the applications which have higher requirements of the dynamic characteristic andstatic characteristic. how to inhibit the torque ripple caused by commutation has beenthe research hotspot and difficulty in the brushless dc motor field.In this paper, the mathematical model of brushless dc motor are analyzed in detail.On the basis of the existing models, the mathematical relationship between the realthe brushless motor neutral point and the construction of the midpoint is derived.Under the action of brushless dc motor PWM modulation, the experiment of terminalvoltage waveform formation reasons are analyzed, and also the PWM modulationfunction influences the neutral point voltage of motor, in contrast to the neutral pointof permanent magnet synchronous motor, the neutral point voltage of brushless dcmotor can form complex waveforms with square wave and trapezoidal wave.In this paper, during the process of brushless motor commutation state, thereasons for the formation of commutation torque ripple and the mathematicalrelationship is analyzed in detail. Due to the effect of inductance, the phase currentflow in the process of commutation of rise and decline rate is not equal, which canproduce commutation torque ripple. According to the torque ripple problem, bymeans of the method of direct torque control, dynamic torque can be easily controlled.The simulation waveform is obtained by the simulation modeling in simulink, thereasons for the formation of circular-saw magnetic chain are analyzed, the paper putforward the influence of the different hysteresis width on the design of the system, bycomparison with Simulink double closed loop speed control method, the results of direct torque control method reduces the torque ripple and accelerate the motor torquespeed of dynamic response.Under the condition of system requirements analysis, brushless dc motor controlsystem platform is established. The system main circuit like rectifier and invertercircuit and the three layers of structure of the brushless motor controller are set up.Under the condition of the hardware platform, the controller can realize the voltageand current sampling, the generation of PWM, communication, the over-voltage andover-current protection, external interruption, and the capture of the position signal,etc. On the basis of the hardware experimental platform, the use of C language in CCScompile environment is completed with the program of the system software, including,the program of the motor start, the program of PI adjustment, the program of ADsampling and filtering program, the program of commutation interrupt program andsystem protection interrupt, etc. Through the adjustment of pid parameters, speed canbe smoothly to achieve the speed set point, rapidity and stability is well achieved.Finally, by means of building experiment platform, brushless motor measuredwaveform is given the in actual operation, and the experiment results are analyzed.The experimental results verified the DTC in brushless dc motor control system ofthe correctness and effectiveness.更多还原