This article introduces methods for controlling the torque of synchronous motors for reference.
1. The electromagnetic torque of a synchronous motor is the interaction between the stator rotating magnetic field generated by the power supply voltage and the rotor's main magnetic field.
2. The angle between the pole axes of the stator rotating magnetic field and the rotor main magnetic field is called the power angle;
3. When the power angle is zero, the electromagnetic torque is zero. The larger the power angle, the greater the torque and the greater the stator current. It's like when you pull a cart, the greater the elongation of the rope, the greater the pulling force.
4. Of course, the torque and current are at their maximum when the power angle is close to 90 degrees.
5. When the power angle is greater than 90 degrees, the torque begins to decrease and enters the unstable operating region. At this time, it will quickly lose synchronism, just like when the rope breaks while pulling the car!
6. The physical quantities related to the magnitude of the work angle are:
1) Electromagnetic torque;
2) Stator current;
3) Output power (related to rotational speed);
7. When the power angle increases from zero to 90 degrees, it is a monotonically increasing function of current, torque, and power. Simply put, as the power angle increases, the current, torque, and power also increase.
8. By simply measuring the current of the synchronous motor, we can determine the magnitude of the power angle and the torque!
9. For example, if you detect that the current of the synchronous motor is the rated current, then it goes without saying that the power angle is the rated power angle and the torque is the rated torque!
10. For synchronous motors, variable frequency starting starts from zero Hz, and the current increases from zero. When the current increases to the rated current, the power angle is the rated power angle, and the torque is the rated torque. At this time, the power is at its minimum. As the speed increases to the rated speed, the power reaches the rated power!
11. As long as the control current is the rated current, the power angle is the rated power angle, and the torque is the rated torque!
12. With a constant current, the voltage can be increased to strengthen the magnetic field and increase the torque. This is the second method of torque control!
Disclaimer: This article is a reprint. If it involves copyright issues, please contact us promptly for deletion (QQ: 2737591964 ) . We apologize for any inconvenience.
