With the features of lower noise, lower vibration, and wider speed range, YPF series electric motors can be matched with various kinds of SPWM frequency converting devices. The motors can keep the constant torque for the frequency up to 50HZ, and keep the constant output power for 50HZ upwards. They are distinguished by the stable speed regulation without torque ripple, high start torque, low start current, and therefore widely applied to various driving machine for speed regulation, such as light industry, textile, chemical industry, metallurgy, print, packing, food, machine tools, blowers, pumps and transportation lines.