The notice of ac and dc servo motor

The servo motor is divided into two types, including ac and dc servo motor. The servo motor is widely used in various fields. There is some notice of ac and dc servo motor when we use.

Improving the dc servo motor commutation

As the dc servo motor rotates, armature winding components enter from a branch through the brush to the other branch. The direction of current in components is changed, which is called commutation. The time of the commutation process is short. The direction of current is changed in a short time, and the commutation components possess inductance. The generated self-induced emf is pretty strong, resulting in the spark on the surface of the electric brush and the commutator. The most effective way to improve the commutation of DC servo motor is to add a commutator pole, but you must pay attention to as follows:

  1. Correct selection of reversing the polarity. As for a motor, the commutator polarity should be in contrast to the next major polarity along with armature turning. So does the electric generator.
  2. Commutating winding must make the series connection with the armature winding.
  3. The commutator magnetic circuit should be unsaturated.

In addition, should select suitably the electric brush. The contact resistance between the brush and commutator is required to be big to the greatest extent. And the abrasion resistance of the brush should be good. Electrochemical graphite brush is commonly applied to the DC servo motor, and metal shicui brush is generally applied to the low voltage and large current motor. And the servo motor hard to the commutation adopts the split brush.

Cautions for wiring of ac servo driver

  1. Signal line, encoder input line, please use shielded wire. Length of wiring: Length of the signal line from NC to AC servo driver less than 3M, Length of input line from AC driver to encoder less than 20 m.
  2. Use thick wire as far as possible for the grounding wire, and please follow the third grounding standard (grounding resistance less than 100Ω) to connect the ground wire with one-point grounding. If the motor is insulated from the machine tool, please ground the motor.
  3. Avoiding the wrong behaviors caused by disturbing pulse, please take the measures as follows:
  • If the integrated servo actuator uses the same power supply as an electric welding machine, electric discharge machining equipment, etc., or does not use the same power supply, there is high-frequency disturbing equipment in the neighboring space, and please use the insulated isolating transformer or power filter.
  • Strong power cables (power cables, motor cables, and other strong power circuits) are wired with signal cables more than 30CM apart and should not be wired in the same wiring slot.
  • Note the terminal connection of the analog input signal cable (as the analog input signal is very susceptible to high-frequency interference).

4. After wiring is completed, check all the wiring to confirm whether the plug terminal is too wide, whether the welding terminal and the crimping terminal are good, whether the screws are tightened, whether the plug is connected correctly, especially to check whether the polarity of the linear servo motor and encoder is connected correctly.

5. Make sure the motor phase sequence meets the requirements of the servo drive, otherwise the motor will not be able to operate.

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