How to make the motor speed (control speed), can not use frequency
In general, the torque generated by the motor is reduced with decreasing frequency (decrease in speed), and the reduced actual data is given in some frequency converter manuals. By using the flux vector control of the inverter, will improve the motor at low speed torque, even in the low speed area motor can also output enough torque. When the frequency converter to speed up to 60Hz frequency, the motor output torque will reduce the normal motor is designed to 50Hz (60Hz) voltage, the rated torque is given in this voltage range. So the rated frequency under the speed is called constant torque speed, the inverter output frequency is greater than 50Hz frequency, the motor torque to be inversely proportional to the frequency of the relationship between the decline. When the motor is running at a frequency greater than 60 Hz, the magnitude of the motor load must be taken into account to prevent the motor output torque from being insufficient. For example, when the torque generated by the motor at 100 Hz is about to be reduced to about 50 Hz, the torque is generated. So the rated frequency above the speed is called constant power speed.
Do not use the variable frequency motor with the speed motor
If you use AC asynchronous motor speed control in three ways:
1 / variable speed control. By changing the motor stator pole pairs to speed, not the linear speed for the sub-file speed, the motor structure and electrical control more complex.
2 / electromagnetic speed control. Driven by the magnet magnet, the electromagnetic coil through the variable size of the DC to speed, for the linear speed, but a waste of energy
3 / frequency control. Through the inverter speed, stepless speed regulation, speed control effect is good, but one-time investment.
If the DC motor speed is to change the armature or the excitation coil voltage to achieve speed. Application in the relatively high demand, a one-time investment is relatively large
