说明：  交流电机降压软启动系统仿真，要求给出电机从静止到进入稳态运行的启动过程中输入电压有效值、电流瞬时值、转矩、转速的变化过程。研究生大作业，调试通过。
(Ac motor step-down soft start system simulation, ask for the steady state of motor static to enter the boot process input voltage RMS, current instantaneous value, the changing process of torque and rotational speed. Graduate students homework, debugging through.)