Current ac motor has completely replaced dc motor
Definitely not. The performance of dc motor speed system is better, the advantage is that it can achieve smooth and economical speed adjustment, high precision and wide application. The speed adjustment of dc motor does not require the cooperation of other equipments, but by changing the voltage/current of the input, or the excitation voltage/current to speed the adjustment.
Ac permanent magnet synchronous speed adjustment is achieved by changing the frequency, requiring the frequency converter. Dc motors do not need other equipment to help speed the adjustment, but their own structure is complex and manufacturing costs are high. Before large power controllable thyristor is used in large quantities, dc motor is used for most speed adjustment.
No matter Powerful electric cars can communicate without dc Small power hard drives, stripper motors in the optical drive, not all dc
