Is the mainstream subway car traction motor, ac or dc?
Big trend is ac traction motor, a few big metro vehicle control system manufacturers (bombardier, Siemens and alstom, modern - rotem, etc.) are in the production of communication control technology products, traction motor of metro vehicle use dc has been rarely, in addition to Beijing line 1 metro vehicle with dc motor, the current of the metro vehicle use is ac motor, the power supply is a dc power supply.
Dc, safety, economy, no harmonic damage, dc motor torque speed, high reliability, low volume,
The main advantage of dc motors is that dc motors can achieve "smooth and economical speed adjustment"; 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 structure is complex and the manufacturing cost is easily damaged (especially by the brush). Before large power controllable thyristor is used in large quantities, dc motor is used for most speed adjustment.
ac motor speed control "FM" adjusting the supply of the frequency of the alternating current motor, alternating current (ac) is a kind of VVVF by (FM) regulating device, commonly known as traction inverter, VVVF to dc traction motor inverter for ac supply, to adjust the motor speed can be adjusted by the frequency of the alternating current and torque can be controlled by adjusting voltage. In high power thyristor industrial production, the ac motor speed control easier, ac motor of low manufacturing cost, long life and other advantages will show it. And the current technology, the ac motor is almost always maintained during the use of the process, providing guarantee for the safe operation of subway vehicles
