1、 Basic structure

AC servo motor consists of stator and rotor:

Stator: Two phase windings arranged at a 90 ° electrical angle to each other in space

Excitation winding: connected to a constant AC voltage Uf

Control winding: Receive control signal voltage Uc, and maintain a phase difference of 90 ° between the two to achieve a circular rotating magnetic field

Rotor: Usually adopts a squirrel cage structure or hollow cup design, and small motors commonly use permanent magnet rotors to improve response speed

2、 Core working principle

1. Rotating magnetic field generation

1.1 Excitation winding and control winding are respectively fed with alternating current with a phase difference of 90 ° to generate a synthesized rotating magnetic field

1.2 By adjusting the amplitude or phase of the control voltage, the ellipticity of the magnetic field can be changed, thereby controlling the torque and speed

2. Energy Conversion Mechanism

2.1 The rotor conductor cuts magnetic induction lines in a rotating magnetic field, generating induced current and generating electromagnetic torque to drive the rotor to rotate

2.2 The speed is determined by the frequency of the control signal, and the steering is controlled by the phase relationship between the two-phase voltages (reverse when the voltage is in phase opposition)

3. Closed-loop feedback control

3.1 The encoder detects the rotor position/speed in real-time and transmits the feedback signal to the driver to form a closed-loop system

3.2 Compare the target value and feedback value of the driver, dynamically adjust the output to achieve precise positioning (accuracy up to 0.001mm)

3、 Key characteristics

1. No rotation phenomenon

When the control voltage returns to zero, the rotor immediately stops rotating due to the high resistance value generating braking torque, avoiding inertial sliding

2. Linear control response

The mechanical characteristics are linearly related to the regulating characteristics, and the speed decreases uniformly with the increase of torque

3. Dynamic response advantage

Response time as short as milliseconds, supporting fast start stop and instantaneous reverse rotation