China 3 phase induction motor suppliers told you about the comparison of three-phase induction motor control technology.
The technician pointed out that the induction motor can provide torque when the frequency of the three-phase stator voltage and current omae is higher than the rotating frequency omare of the electric shaft. This difference is called the transition frequency Ω slim, and its normalized value relative to Ω E is the transition difference. The following details about this knowledge.
The motor itself can increase or decrease the torque according to the change of the mechanical load, and reduce or increase the shaft speed within the range of about 20 <UNK>. Using an inverter, the frequency of Ω E can be changed and the starting current can be greatly reduced.
The rotor speed can be changed by changing the synchronization frequency omae. If the voltage amplitude remains constant, the electromagnetic flux will change and saturation problems may occur. However, by maintaining a constant ratio between the stator voltage range and Ω E, the electromagnetic flux can remain constant. This technique is called V/f control.
Assuming that the load is constant, this method causes the rotor speed to change with a constant rotation difference to minimize power loss. Since this is an open-loop control technology, for the fixed value Ω E, the increase or decrease of the mechanical load will lead to a change in the rotor speed.
By implementing the closed-loop version of the technology, developers can improve their ability to control the speed of the motor while retaining the combination of low cost and low dynamic performance provided by the open-loop version. The speed sensor must be used to change the rotation frequency according to the actual rotor speed and mechanical load.
The only MCU peripherals required for these technologies are timers for generating six PWM signals and DAC for debugging. Closed-loop technology also requires a timer to decode the speed / position sensor output.
