What is the difference between a servo motor and a linear motor?

A servo motor is an engine that controls the operation of mechanical components in a servo system. It is an auxiliary motor indirect speed change device. The servo motor can control speed and position with great accuracy. It can also convert voltage signals into torque and speed to drive the control object and achieve closed-loop control.

A linear motor is a transmission device that converts electrical energy into linear motion mechanical energy without the need for any other conversion mechanism. It can also be viewed as a rotating motor that is radially cut and unfolded into a plane. The side derived from the stator is called the primary, and the side derived from the rotor is called the secondary. In actual use, the primary and secondary are made into different lengths to ensure that the coupling between the primary and secondary remains unchanged within the required travel area. A linear motor can also have a short primary and a long secondary, or a long primary and a short secondary. Taking into account the manufacturing cost and operating costs, a short primary and a long secondary are currently commonly used.

Linear motors have compact structure, low power loss, high fast moving speed, high acceleration, and high speed (linear motors can also complete high-precision positioning control in different areas from high speed to low speed by driving the load at the same time; they are selected for automatic doors in subways.

Servo motors are prone to low-frequency vibrations at low speeds. The vibration frequency is related to the load and the performance of the driver. It is generally believed that the vibration frequency is half of the motor's no-load starting frequency. These low-frequency vibrations, which are determined by the working principle of the servo motor, are very inconvenient for the normal operation of the machine. When the servo motor is working at a low speed, damping technology should usually be used to solve the low-frequency vibration phenomenon, such as adding a damper to the motor, or using subdivision technology on the driver.

Currently, most of the servo motors used in computer embroidery machines are five-phase hybrid servo motors, which use high-phase stepper motors to reduce the step angle and improve control accuracy. However, the performance improvement obtained by using this method is limited, and the investment is also relatively high. The use of subdivided drive technology can also change the running quality of the servo motor as much as possible, reduce torque fluctuations, suppress oscillations, reduce noise, and improve step resolution.

In fact, linear motors are also a type of servo motors. In theory, any system that only needs feedback (linear motors usually use Hall or linear grating feedback) should be a servo system. Therefore, servo motors should be broadly divided into two categories: rotary servo motors and linear servo motors. The characteristics of linear motors are: high dynamic characteristics, high rigidity, corresponding to traditional linear transmission structures (such as screws, electric cylinders), maintenance-free, but higher investment.