The load is changed with many factors such as temperature , magnetic reluctivity , etc . and its parameters are difficult to measure . so the worst working situation is difficult to know , which is a serious problem when the starting issue is studied 在研究逆变器的启动问题时，由于负载变化大，参数很难准确的测量，无法得知可能出现最严重的工况，给研究带来了很大的困难。
