基于场路耦合法的变频感应电机铁耗计算

Calculation of iron losses in inverter-fed induction motor based on field-circuit coupled method

相对于正弦激励,变频器输出电压中包含大量的谐波分量使得感应电机铁耗的计算变得更加复杂。为了准确地计算电机铁耗和研究铁耗在变频感应电机内的分布特点,建立了二维时步有限元的铁耗计算模型,基于场路耦合法,以一台1.5 kW的变频感应电机为实例,计算了空载运行时电机的铁耗,并分别对正弦激励和变频器供电下感应电机内部铁耗的具体分布特点进行了对比分析,在此基础上,研究了变频器不同的控制策略对变频感应电机铁耗的影响。对样机进行空载实验测量电机铁耗,研究结果表明,实验结果与仿真分析吻合良好,以往在正弦激励下被忽略的转子铁耗在变频感应电机中不可忽视且以谐波为主集分布在转子齿顶部分。为进一步优化电机铁芯结构来降低铁耗和电机的温升研究提供了一定的技术支持。

Compared to the sinusoidal excitation,iron losses in inverter-fed induction motors are calculated more complex due to many harmonic components in the inverter.In order to calculate iron losses in inverter-fed induction motors accurately,an computation iron losses model was established based on 2-D circuit-field coupled time-stepping finite element method.Taking a 1.5 kW motor as an example,iron losses in the motor were calculated at the no-load condition.The specific distribution of iron losses in the induction motor under sinusoidal and inverter excitation were also studied and compared respectively.Based on the above analysis,the influences of the control strategy for the inverter on iron losses were also investigated.Finally,iron losses in the prototype motor were measured by the noload test.The results indicate that the calculated value can make a good agreement with the measured,and iron losses at the rotor side which is normally neglected in the sinusoidal supply can＇t be neglected.The iron losses in the tooth area are due to high harmonics.The achievement can provide some technical support for developing optimized design of core structure to reduce iron losses and temperaturerise study in motors.