The robot servo system has successively passed through the two stages of open-loop stepper motor servo system and DC motor servo system. Now it has entered the phase of synchronous motor servo system, which is divided into brushed DC motor and AC asynchronous motor.
1 brushed DC motor
Brushed DC motors have large starting torque, high efficiency, convenient speed regulation, and good dynamic characteristics. Their good control performance is unmatched by other AC motors. But relatively speaking, the structure of a DC motor is relatively complicated, and its complicated structure limits the volume and weight of the DC motor. The bigger the motor's capacity and the higher the speed, the bigger the problem. The armature winding and commutator are placed on the rotor of the DC motor. When the brush and the commutator slide contact, it is easy to cause machine wear and sparks. Therefore, the DC motor has many faults, low reliability, short life, maintenance and maintenance work. large. It can be said that the brushes and commutators of ordinary DC motors restrict the development of DC motors towards high speed and large capacity.
2 AC asynchronous motor
Compared with DC motors, AC asynchronous motors have many advantages such as simple structure, reliable operation, long life, low cost, and simple and convenient maintenance. But at the same time, AC asynchronous motors also have disadvantages such as poor speed regulation performance, small starting torque, low overload capacity and low efficiency. The generation of the rotating magnetic field of AC asynchronous motors needs to draw reactive power from the grid, so the power factor is low, and the situation is particularly prominent at light loads, which greatly increases the losses of the line and the grid. AC asynchronous motors have always dominated where speed regulation is not required. Since the development of the AC motor variable frequency speed regulation system, AC asynchronous motors can also be used in applications that require speed regulation.