B2b frequency how to speed
How does changing the power frequency to change the speed of the motor? When the motor is connected to the power supply to drive the normal operation of the load, at this time to change the power frequency, such as the current frequency down, the motor armature rotating magnetic field speed will decline, the rotor conductor cutting magnetic field speed decreases, turn from the induced potential , The rotor current decreases, the torque decreases, the load on the shaft does not change, the torque will be less than the load resistance torque, the motor rotor speed decreases, the rotor conductor cutting the magnetic field line speed increases, the rotor induced potential increases, the rotor current increases, The torque rises until it is equal to the load resistance torque, and the speed is smaller than the original. After stabilizing the work, the torque of the motor is the same as that of the original. (The motor torque is the same as the load torque, the load is constant and the motor torque is not changed)
AC motor speed control methods are four: frequency, transformer, variable pole and winding motor to change the rotor loop resistance of the speed control method. Its source is based on the motor speed formula: n = (1-s) * 60f / p where: n --- motor speed s --- motor slip f --- power frequency p --- motor pole Logarithm
can be seen from the formula: frequency f changes, the speed will follow the change. 2) When the motor connected to the public grid, you can use the inverter (2) When the motor is connected to a single motor, you can change the output frequency of the generator directly to change the output frequency of the generator. Change the frequency of the power supply to the motor to change the speed of the motor.
