What’s the difference between a servo motor and an ordinary motor?

servo motor classification:

According to the application scenarios of servo motors, servo motors are divided into brushless DC and AC motors, and can also be divided into 360-degree continuous rotation, linear and fixed-angle motors according to the working mode. Usually, the servo motor contains three wires, power, control and ground. The appearance and size of the servo motor varies according to different application scenarios. The most common RC servo motor is mostly used in small intelligent equipment such as robots and model cars, because it can be easily controlled by a microprocessor.

DC servo motor

Usually, this kind of motor has an independent DC power supply on the winding and armature winding, and realizes motor control by controlling the armature current or the excitation current. Based on different usage scenarios, excitation control and armature control have their own advantages. The DC servo motor has a low armature inductive reactance, so it can realize accurate and fast start or stop functions. They are mostly used in equipment that can be controlled by a microcontroller or computer.

AC servo motor

AC servo motors contain encoders, which together with the controller provide closed-loop control and feedback. Generally, AC servo motors have more advanced designs and are equipped with better bearings. AC servo motors have a higher working voltage, so the torque is greater, and the accuracy is higher. At the same time, they can be controlled in full accordance with the requirements of the application scenario. AC servo motors are mainly used in robotics, automation equipment, CNC and other mechanical equipment.

Angle adjustable servo motor

This is a common servo motor, such as 180 degree servo motor, 90 degree servo motor and so on. This type of motor achieves the limitation of the maximum angle by setting a limit device on the gear mechanism. It is more common in products such as remote control cars, remote control boat models, remote control airplanes, and model robots.

360 degree servo motor

The appearance of this type of motor is similar to that of a fixed-angle motor. The difference is that it has no fixed angle and can rotate 360 degrees continuously. The control signal intelligently controls the direction and speed of rotation, but cannot set a fixed position, that is to say, a 360-degree servo motor cannot set an angle. This kind of motor is mostly used as a driving motor for mobile robots.

 Linear servo motor

The linear servo motor is similar to the angle adjustable servo motor, but it has an additional gear to make the output shaft reciprocate. This type of motor is not very common, and it has been found occasionally on some high-end models.

What is the difference between a servo motor and an ordinary motor:

In simple terms, the servo motor can achieve precise control. It can rotate as much as you make it rotate, and it will also feedback to achieve the so-called closed loop. The encoder will feedback to see if it has actually rotated that much, so that the control accuracy is even better. high. Ordinary motors turn when power is on, and stop when there is no power. In addition to turning, if you have to say that it has any function, it is forward and reverse.

The structure of the servo motor is actually no different from the ordinary two-phase AC asynchronous motor. The stator of the servo motor has two AC windings with a difference of 120 degrees in electrical angles, which are called excitation windings and control windings. The rotor is the squirrel cage winding of a common cage asynchronous motor.

The general structure of the industrial robot electric servo system is three closed-loop controls, namely, current loop, speed loop and position loop. Generally, for AC servo drives, various functions such as position control, speed control, and torque control can be realized by manually setting its internal function parameters.

Generally, servo motors are used to drive the joints of robots, and the requirements are to have the maximum power-to-mass ratio and torque-to-inertia ratio, high starting torque, low inertia, and a wide and smooth speed adjustment range.

The above shared with you is the difference between servo motors and ordinary motors. Servo motors are widely used in industrial robots because of their high starting torque, large torque, and low inertia. However, there are many different types of servo motors today. Model, in order for the robot to perform its best, we must pay attention to the relevant details in the selection.