Description
Definition:
The structure of the stator of IEMENS servo motor is basically similar to that of a capacitor phase separated single-phase asynchronous motor. Its stator is equipped with two windings that are 90 ° apart from each other, one is the excitation winding Rf, which is always connected to the AC voltage Uf; The other is to control winding L and connect the control signal voltage Uc.
Basic Information ：
So AC servo motors are also known as two servo motors. The rotor of an AC servo motor is usually designed as a squirrel cage, but in order to provide the servo motor with a wide speed range, linear mechanical characteristics, no “self rotation” phenomenon, and fast response performance, it should have two characteristics compared to ordinary motors: high rotor resistance and low moment of inertia. There are two forms of rotor structures that are widely used: one is a squirrel cage rotor made of high resistivity conductive materials with high resistivity bars. In order to reduce the rotational inertia of the rotor, the rotor is made slender; Another type is a hollow cup-shaped rotor made of aluminum alloy, with a very thin cup wall of only 0.2-0.3mm. In order to reduce the magnetic resistance of the magnetic circuit, a fixed internal stator needs to be placed inside the hollow cup-shaped rotor. The rotational inertia of the hollow cup-shaped rotor is very small, the reaction is rapid, and the operation is smooth, so it is widely used. When there is no control voltage, only the pulsating magnetic field generated by the excitation winding is present in the stator of the AC servo motor, and the rotor remains stationary. When there is a control voltage, a rotating magnetic field is generated inside the stator, and the rotor rotates in the direction of the rotating magnetic field. Under constant load, the speed of the motor varies with the magnitude of the control voltage. When the phase of the control voltage is opposite, the servo motor will reverse.
technical specifications
The working principle of SIEMENS servo motors is similar to that of phase separated single-phase asynchronous motors, but the rotor resistance of the former is much higher than that of the latter. Therefore, compared with single machine asynchronous motors, servo motors have three significant characteristics:
1. Due to the high rotor resistance, there is a significant difference in the torque characteristic curve between curve 1 and curve 2 of a regular asynchronous motor, resulting in a high starting torque. It can make the critical slip rate S0>1, which not only makes the torque characteristics (mechanical characteristics) closer to linearity, but also has a larger starting torque. Therefore, when the stator has a control voltage, the rotor immediately rotates, which has the characteristics of fast starting and high sensitivity.
2. Wide operating range
3. A servo motor that operates normally without self rotation will immediately stop running as soon as the control voltage is lost. When the servo motor loses control voltage, it operates in a single-phase state. Due to the high resistance of the rotor, the two opposing rotating magnetic fields in the stator interact with the rotor to produce two torque characteristics (T1-S1, T2-S2 curves) and a composite torque characteristic (T-S curve)
The output power of AC servo motors is generally 0.1-100W. When the power frequency is 50Hz and the voltage is 36V, 110V, 220, 380V; When the power frequency is 400Hz, there are various voltages such as 20V, 26V, 36V, 115V, etc.
The communication servo motor runs smoothly and has low noise. However, the control characteristics are nonlinear, and due to the large rotor resistance, high losses, and low efficiency, compared with DC servo motors of the same capacity, they are bulky and heavy, so they are only suitable for low-power control systems of 0.5-100W.
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