With the development of intelligent control of many mechanical equipments becoming more and more obvious, this has brought many opportunities and challenges to motor manufacturers. For example, more actions of a fully automatic production line require the coordination of control systems. How can the matching motors be Effective integration with the control system is a very important issue.

 

 

So, what is motor control?How to understand it?

 

 

Motor control refers to the control of starting, accelerating, running, decelerating and stopping the motor.There are different requirements and purposes according to different motor types and motor use occasions.For the motor, through motor control, the purpose of the motor's quick start, quick response, high efficiency, high torque output and high overload capacity can be achieved.

 

XNUMX. Speed ​​control of the motor

Motor speed control methods include series resistance speed control, frequency conversion speed control, pole-changing speed control and vector control, direct torque control, etc.

 

 

Series resistance speed regulation is mainly used for asynchronous motors, and the speed regulation range is limited by the maximum torque of the motor.

 

 

Frequency conversion speed regulation is suitable for induction motors, and the purpose of speed regulation is achieved by adjusting the synchronous speed.

 

 

Pole-changing speed regulation produces 1/2, 1/3... rotation speed by changing the number of motor poles.

 

 

XNUMX. Motor start control

 

 

The three-phase asynchronous motor start mode includes full voltage direct start, step-down start, and start by increasing the resistance of the rotor loop.

 

 

Step-down start.Mainly include autotransformer start, star-delta change start, variable voltage start, etc.When the asynchronous motor is started, the rotor is at a standstill and the starting current is relatively large. The starting current can be reduced by step-down starting.Since the starting torque of an asynchronous motor is proportional to the square of the voltage, it is necessary to ensure that the motor has a certain starting ability for step-down starting.

 

 

Increase the start of the rotor circuit.It is suitable for wound rotors, deep-slot rotors and double-cage rotors. This method cannot be used for squirrel-cage rotors.

 

 

Start of a single-phase asynchronous motor.Including capacitor start, resistance start, PTC start, shaded pole start, etc.Since the single-phase winding of the induction motor cannot generate a rotating magnetic potential when the rotor is stationary, an asynchronous motor with only a single-phase winding cannot start automatically.In this regard, it is necessary to install an auxiliary winding 90° to the main winding on the single-phase asynchronous motor.This winding is mainly used to start the motor. When the motor is started, it can be cut off or used for the operation of the motor.

 

 

 

Frequency conversion start.When starting with a variable frequency, the rate of change of the starting voltage frequency is usually set. When the motor runs to 60% to 80% of the rated speed, the rated frequency is added to the motor to directly bring synchronization.Asynchronous motor drives start similarly.