After the three-phase motor is disconnected from the power supply, the motor will slowly stop after a period of time due to inertia. However, some enterprises that produce machinery require the three-phase motor to stop quickly and accurately, so the short-circuit braking requirements for the three-phase motor will be extremely high. Therefore, how to realize short-circuit braking is the most concerned issue. Let's take a look at how the three-phase motor performs short-circuit braking.
Three-phase motor short-circuit braking method 1. Feedback braking When the speed of the three-phase motor is higher than the synchronous speed in actual operation, the motor belongs to the braking state at this time, and the actual speed of the running motor exceeds the rated synchronous speed. At this time, the motor is in a regenerative power generation state, and the torque direction When the direction of the synchronous speed is opposite to that of the synchronous speed, the braking effect will also occur. The regenerative braking is mostly used to limit the speed of the potential load. 2. Reverse brake Reverse connection braking is to suddenly reverse the phase sequence of the running motor power supply. In the production process, it is often necessary to take some measures to stop the motor as soon as possible, so that the rotation direction of the rotating magnetic field is opposite to the actual rotation direction of the rotor. The torque acts as a braking torque. The advantage of turning in the opposite direction is that it is fast, but the disadvantage is that it is not easy to accurately grasp.
3. Energy consumption braking Dynamic braking can make up for the deficiency of reverse braking. After the motor stator is disconnected from the AC power supply, a DC voltage is applied to the stator winding, that is, a DC current is applied, and the effect of the rotor induced current and the static magnetic field is used to turn the motor. The distance can hinder the continuous rotation of the rotor to achieve the purpose of braking.