Why EC Motors Are More Suitable for Multi-line Speed Regulation Control

Key Points of Fan Permanent Magnet Selection for Fan EC Motors Part Seven-Why EC Motors Are More Suitable for Multi-line Speed Regulation Control

1. Energy Saving Principle of EC Motor

The large structure of EC motor can be considered as permanent magnet synchronous motor+vector control controller. Permanent Magnet Synchronous Motor (PMSM) is a synchronous motor that is excited by permanent magnets to generate synchronous rotating magnetic field. The rotor is embedded with permanent magnets or surface-mounted permanent magnets to generate rotating magnetic field. Compared with the three-phase asynchronous motor, the permanent magnet synchronous motor reduces the iron loss and copper loss of the rotor excited by the motor. Therefore, the permanent magnet synchronous motor has higher conversion efficiency for converting electric energy into kinetic energy than the three-phase asynchronous motor, and the permanent magnet synchronous motor meets the national standard level I energy efficiency /IE4 energy efficiency.

2: EC motor speed control

The average efficiency of EC motor in the whole speed regulation range (high/low speed) can reach above 75% in the low speed and low load range, and the rated efficiency of permanent magnet synchronous motor is above 90%. High efficiency means less loss, and the calorific value of permanent magnet synchronous motor is much less than that of asynchronous motor. Compared with asynchronous motor, the starting torque is increased to 2.5 times (feedback is increased). The direct-control three-phase asynchronous motor's starting current is too large (4~10 times rated current) which impacts the power grid and affects the operation of other equipment. The starting of permanent magnet synchronous motor can avoid the phenomenon of starting current impacting the power grid through reasonable excitation process. EC motor is more suitable for fan speed control.