在工业领域，大功率重载设备大部分都采用大型高压交流电动机进行拖动。但是大型电动机在直接起动时会产生大量重问题，起动冲击电流大，会导致电网电压急剧下降，影响同电网内其他设备正常运行。本文分析了降压软起动和变频软起动的原理和特点，并指出变频软起动是当前解决大功率电机软起动的最佳途径；起动电流小，起动转矩大，起动平滑无冲击。
In the industrial field, more and more high-voltage AC motor has been applied in high-power heavy equipment. But large AC motor will produce a large number of serious problems when starting directly. There will be a sudden sharp decline in the grid, which causes that other elec-trical equipment in the power system can’t operate normally. This paper analyzes the principles and performance of step-down soft start and variable frequency soft start, and shows that variable frequency soft start is the best way to solve the large motor soft starting, with small starting current, big starting torque and starting no impact on the smooth.
