航空变频电源下笼型感应电机矩形转子槽结构优化分析

当前大功率的航空发电机开始采用360~800Hz的变频输出方式,在航空变频电源的直接供电下,感应电机的性能受到频率变化最大的影响是在高频时起动转矩太低。针对笼型感应电机,采用解析计算的方法对矩形转子槽尺寸进行优化,在不改变稳态性能的条件下获得最大起动转矩。深槽尺寸的变化将影响集肤效应系数和槽漏感2个方面,二者对起动转矩的作用相反。通过综合2个方面的因素,建立起包含槽型尺寸和频率的动态转子参数模型,并采用该动态转子参数对传统的转矩公式进行调整,进而获得关于转子槽尺寸的起动力矩解析式,同时基于该解析式实现对起动力矩的优化。采用该解析方法对7.5kW感应电机进行深槽转子优化,并对航空变频电源驱动时的起动特性进行了仿真和样机实验,验证了该方法在矩形转子槽优化设计中的有效性。

Optimization analysis of rectangular rotor slot of cage induction motor operating with aero variable frequency power

Currently high power aero-generators start to adopt variable frequency power output ranging from 360 Hz to 800 Hz, the most distinct influence of which is low starting torque of induction motor at high frequency when the variable frequency power is supplied directy. An analytical method is proposed to optimize the rectangular rotor slot of cage induction motor for starting torque maximization under the premise of invariant steady-state performance. Skin effect coefficient and slot leakage are affected by slot modification and will produce both positive and negative effects on starting torque. Combining the two factors, a dynamic rotor parameter model including slot sizes and frequency is established to revise the traditional torque formula and the starting torque equation regarding rotor slot sizes is obtained, which gains ground for the starting torque optimization. The rotor slot of a 7.5 kW induction motor is optimized with analytical method. Simulation and tests were conducted to verify the starting characteristics of the motor under aero variable frequency power supply, which verified the effectiveness of the optimization method for rectangular rotor slot.