The difference between low inertia and high inertia of servo motor

We have introduced in detail the advantages and disadvantages of servo motor speed regulation methods before. It can be seen that there are four speed regulation methods for this motor, namely: commutator motor speed regulation, stator voltage regulation and speed regulation, rotor string resistance speed regulation, and electromagnetic rotation. Differential clutch speed regulation. So what are the differences between low inertia and high inertia of servo motors? Let’s find out together below!

Moment of inertia = radius of rotation * mass

Low inertia can be understood this way, that is, the servo motor is relatively long and flat, and the inertia of the main shaft is small. When the motor performs repeated movements with high frequency, if the inertia is small, the heat will be small. Therefore, low-inertia motors are more suitable for high-frequency reciprocating motion. But the general torque is relatively small.

The high inertia servo motor is relatively thick and has a large torque. It is more suitable for occasions with large torque but not fast reciprocating motion. Because of the high-speed movement to stop, the driver needs to generate a large reverse drive voltage to stop the large inertia. At this time, the heat will be very large.

Inertia is a measure of the inertia of a rigid body rotating around an axis, and rotational inertia is a physical quantity that represents the rotational inertia of a rigid body. It is related to the mass of the rigid body and the distribution of the mass relative to the axis of rotation.

A rigid body refers to an object that does not change in an ideal state. The motor inertia is encountered when selecting it, which is also an important indicator of the servo motor. It refers to the inertia of the servo motor rotor itself, which is very important for the acceleration and deceleration of the motor. If you can't match the inertia well, the motor will move very erratically.

Generally speaking, motors with small inertia have good braking performance, fast response to start, acceleration and stop, and good high-speed reciprocation. They are suitable for some light load and high-speed positioning situations, such as some linear high-speed positioning mechanisms. Motors with medium and large inertia are ly suitable for situations with large loads and high stability requirements, such as some circular motion mechanisms and some machine tool industries.

If the load is relatively large or the acceleration characteristics are relatively large, and a motor with a small inertia is selected, this may cause too much damage to the motor shaft. The selection should be based on factors such as the size of the load and the magnitude of the acceleration. Generally, There are relevant energy calculation formulas in the selection manual, and we can also follow this.

The response control of the servo motor driver to the motor is the ratio of the load inertia to the motor rotor inertia, which cannot exceed five times. Through the design of the mechanical transmission device, the ratio of the load inertia to the motor rotor inertia can be close to one or smaller.

When the inertia of the load is indeed very large and the corresponding mechanical design cannot make the ratio of the load inertia to the motor rotor inertia less than five times, a motor with a larger motor rotor inertia can be used, which is a so-called large inertia motor. When using a large inertia motor, it should be noted that in order to achieve a response of , the capacity of the driver should be larger.