变频供电条件下异步电机空载磁场及损耗分布特点

No-Load Magnetic Field and Loss Distribution of Asynchronous Motor under Variable Frequency Power Supply Conditions

以一台空间矢量脉宽调制(SVPWM)供电的5.5 k W异步电机为例,利用时步有限元法分析不同载波频率和调制比下电机定转子铁心磁密变化规律及其对损耗密度分布的影响。结果表明,变频供电时,定转子铁心磁密谐波主要集中在定子齿顶区域,随载波频率增加,电机总铁耗下降,但总体变化较小;调制比增加导致变频器输出电压谐波含量降低,电机内部定子铁心谐波损耗密度减小,电机总损耗随调制比增加而降低。对不同载波频率和调制比空载运行状态进行试验对比,验证了分析的正确性。

Taking a 5. 5 k W motor fed by SVPWM as an example,time-stepping finite element method was utilized to study the changing regulations of the flux density in stator and rotor cores and the distribution of loss density of motor which fed by different frequency of carrier wave and modulation index. The results showed that,the harmonic flux density of iron focuses on the center of stator and rotor tooth tip under variable frequency power supply. With the carrier frequency increase,the total iron losses decreased but the variation was minor. With the modulation index increased,the harmonic content of the inverter output voltage and the loss density of harmonic loss in stator core reduce,and the total iron loss decreases. The correctness was verified by the experiment on the no-load operating status of 5.5kW motor.