基于开关变压器的中压电动机软起动器的研究

Research of Middle-voltage AC Motor Soft Starter Based on the On-off Transformer

研究了基于开关变压器的中压电动机软起动器,主电路串联变压器一次侧绕组,变压器二次侧绕组与一对反并联晶闸管连接用来解决主电路直接串联晶闸管的耐压问题。因为三相异步电机是一个感性元件,电机功率因数角随转速的变化而变化,进行了功率因数角控制模型的仿真研究。仿真结果显示,有效控制功率因数角可以减小电磁转矩的振荡。利用上述研究结果,提出监测功率因数角变化来进行闭环控制。试验证明,此控制达到预期要求。

The soft-starter is based on the transformer so that it can work under the middle voltage. In order to avoid the high voltage, a pair of anti-parallel SCR was used to connected with the second winding of the transformer and the primary winding was directly connected with the motor＇s stator. In the period of the starting, the power factor angle is changing when the speed of motor changes. According to this, the simulation towards the power factor angle was worked out. And the results show that vibration of electromagnetic could be decreased under the efficient control of power factor angle when the motor is starting. Based on these fruits, the closed-loop control way of power factor angle was pointed out. Finally the experiments in lab and sites demonstrate that this way can meet the requirements of the soft starting fully.