Why is a single phase ac motor that can be adjusted by voltage
Synchronous motor torque = motor power/(2 * PI * RPM / 60) N · m. 2, the frequency of the alternating current (ac) of 50 hz, synthesis of the synchronous speed of the magnetic field of 50 r/s, which is 3000 r/min, if motor more than a pair of poles, further analysis can also get synchronous speed. 3, 4 pole synchronous speed is 1500r/min, 6 pole synchronous speed is 1000r/min, 8 pole synchronous speed is 750r/min. The asynchronous motor speed = (60 * frequency/logarithmic) times the error rate. 5, the synchronous motor stator voltage is reduced, according to article 1, motor torque, asynchronous motor, conforms to article 4 formula, slip is less than 1, motor speed down. If the torque of the motor is in balance with the external resistance torque, the slip rate is stable, the speed is stable and the motor is successful. After the 5th and 6th, the stator voltage of the motor is improved, and the process is reversed. The voltage regulation is implemented in this way.
The low voltage is not the equivalent of lowering the torque, so it's not going to be big, it's going to be low, I understand that
In simple terms, if the voltage is reduced and the rotor spins at the same speed, the stator gets a small current. Electromagnetic torque is reduced, in under the action of load torque, the same slip increase led to the decrease of the rotational speed, speed fall in reflection impedance decreases, and according to the size form again low impedance of the rotational speed of voltage and current of balance, and maintain at a low speed.
