论文针对交流电动机起动时产生的较大起动电流，可能对电网和其他设备以及电机本身造成不良影响的问题。经过对传统电机起动方式的讨论，确定采用了开关变压器式软起动方法。该方法是目前国内较为新颖的软起动方法，它由于引进了开关变压器的概念，从而解决了电力电子元器件单管耐压不足等问题，可以实现在较大功率电机起动过程中，通过对晶闸管触发角的控制以达到电机起动电流平稳，降低起动转矩的冲击，以及电机加速平滑的效果。 论文对开关变压器式软起动器系统进行了分析与建模，给出了晶闸管触发角度与开关变压器阻抗值之间的关系，为该软起动提供了理论依据。在此基础之上，利用Matlab软件的Simulink功能搭建了软起动器的模型，包括控制器部分、过零采样以及电流采样等部分。并且对模型进行了相关的仿真比较实验，结果表明这种软起动控制系统可以有效地减小电机的起动电流，降低转矩的冲击。基于上述模型的建立与控制原理，论文引入了一种调整系统控制量的模糊PID算法，并将这种算法应用到电机的软起动过程中，通过仿真实验表明该控制算法与传统的PID算法比较具有更好的适应性与鲁棒性。 论文根据开关变压器式软起动器的工作原理，设计了软起动控制器部分的相关软件和硬件。其中硬件部分主要包括，同步过零检测电路、电流反馈检测电路以及晶闸管触发单元电路；而软件部分则给出了具体控制思想的程序流程图和部分程序。最后对所做控制器部分进行了相应的可行性测试,达到设计效果。

In the thesis, adverse effect on the grid and motor itself could be caused by the higher starting current when the AC motor starting. By the discussion of the traditional motor starting mode, the switching transformer soft starting mode is determined. The solution is more novel soft starting method, for the switching transformer concept is introduced; the problem of power electronic components voltage inadequate is solved. In the higher power motor starting process, by the control of thyristor firing angle, the motor starting current is smoothed, the starting torque impact is reduced and the effect of motor fast smooth is achieved. The switching transformer soft starter is analyzed and modeled in the thesis, the relations of thyristor firing angle and switching transformer impedance are given, the theoretical basis of soft starting is provided. On the basis of it, the Simulink package in the Matlab is used for building the soft starter model which including controller section, over-zero sampling and current sampling section. The relevant simulation contrast experiments are putted up; the results show that the motor starting current is reduced effectively and the torque impact is lowered with this soft starting control system. Based on the above model established and control principle, a fuzzy PID algorithm of adjust system control volume is introduced, which is used in the motor soft starting process, the simulation experiments show that it has better adaptability and robustness. According to the switching transformer soft starter working principle, the relevant software and hardware of soft starting controller are designed. The synchronous over-zero testing circuit, current feedback testing circuit and thyristor trigger unit circuit are included in the hardware section; the process flow chart of specific control thought and part of program are given. Finally, the controller is corresponding tested. The result is meet the design effect.