Switching control between variable frequency and power frequency of emulsion pump in coal mine

In view of problem of high impulse current when scheme of multiple pumps linkage with one frequency converter applied in coal mine emulsion pump station, asynchronous switching and synchronous switching control scheme between variable frequency and power frequency of emulsion pump were proposed. The field test results show that the synchronous switching control can avoid impulse current more effectively and truly realize free switching between variable frequency and power frequency.