大型鼠笼异步机起动性能的计算

Computation of performance of large cage induction motors during starting

采用二维涡流场有限元法计算小型异步电动机起动电流及转矩，已可满足工程要求，但对于大型电机，由于转子端部结构复杂，端部漏阻抗计算值不准确，使起动电流及起动转矩计算误差较大。直接计算三线电磁场，变量过多，费用太大，不易为工厂接受。为此作者提出一种新的二、三维结合的简化模型。它可分离出端部漏阻抗，代入考虑定、转子铁心非线性的二维涡流场程序进行计算，可获得误差小于１０％的计算精度，而机时与内存比直接三维场的计算少得多。对两台电机进行了实际计算，与实测值比较，精度较高。文中还对转子温度对起动参数的影响作了分析计算。

Starting performance of small cage induction motors: can be computed by 2-D FEM accurately, for large cage induction motors, because of the complexity of end structure, this method can not give results with necessary accuracy. Though the use of 3-D FEM can improve the computation, the computing time and computer storage would bring many difficulties if it were used for the whole region analysis of motors. In this paper, a new mixed model of 2-D and 3-D FEM is proposed, by which the rotor 3-D and 2-D eddy current fields are calculated. Through the comparison of these two fields, the end parameters of impedance can be obtained. Putting these parameters into the nonlinear 2-D eddy current field computation system of whole region of stator and rotor, the starting currents and torques of motors can be calculated.Two numerical examples are given. It is shown that the relative computation errors in currents and torques are less than 10% compared with experiment results. In addition, the influence of rotor winding temperature on the starting parameters of motors is also discussed.