Industry News

The structure & applications of coreless motors

2023-12-02

There are many types of motors,from a structural point of view, they can be roughly divided into two categories. One is our common iron core motor, and the other is coreless motor. In this article we focus on coreless motors.

We all know that the two most important parts of a motor are the rotor and the stator. Coreless motor, as the name suggests, means that the inside of the rotor is empty. You can imagine it as an empty cup with a shaft passing through the middle. This is the rotor of the coreless motor. The structure of the motor is divided into two categories. The first category is that the coils are made into the rotor, the magnets are made into the stator, and the coils are fixed by special means. The second type is to make the coil into the stator and the magnetic steel into the rotor. Generally, high-power hollow cups have this structure.


We mainly talk about the advantages and disadvantages of these two types of coreless motors:


(1) There are three types of motor losses: 1. Copper loss 2. Iron loss 3. Mechanical loss. Because the coreless motor has no iron core, the coreless motor only has two major losses. Therefore, the first major advantage of coreless motors is low loss and high efficiency.

(2) The first type of coreless motor, because it has no iron core, has small moment of inertia, high and stable rotation speed, low noise and low heat generation.

(3) The second type of coreless motor, due to the special stator technology, has strong overload capacity, usually 3 times the rated value, and the duration is about 60S. Because the internal resistance of the motor is small and the heat generation is small, the rotation speed is very stable and the torque is stable. Even at 1 rpm, the torque can still be maintained, and the vibration is small and the noise is small.


The disadvantages of coreless cups are as obvious as their advantages. The biggest disadvantage is the high price. Generally, only mid-to-high-end industries will use coreless motors. In addition, the second type of motors (here specifically refers to brushless coreless cups) have too small internal resistance. The recoil current is large during emergency stop, so the requirements on the driver are relatively high.Since the coreless motor has overcome the technical obstacles of the iron core motor, and its outstanding features are concentrated on the main performance of the motor, it has a wide range of applications. Let me list a few widely used fields:


1. Air pump industry. It is generally used in respiratory pumps on medical machinery. As long as it is a pump with high requirements for stable flow, coreless motors will basically be used. After all, stable speed is its advantage.

2. Various aircraft, including aviation, aerospace, model aircraft, etc. Taking advantage of the coreless motor's advantages of light weight, small size and low energy consumption, the weight of the aircraft can be reduced to the greatest extent.

3. AGV industry. The working environment of AGV cars often requires climbing hills and starting with heavy loads, which requires the overload capacity of the coreless motor. For ordinary motors, it may be fine once or twice, but after a long time, the motor will burn out.

4. Service robot industry. From a safety perspective, service robots generally require low voltage. Low-voltage motors with iron cores are also made. However, the lifespan is still lacking in terms of torque and rotational speed stability. Therefore, more high-end service robots use coreless motors

5. Various household appliances and industrial products. Using coreless motors as actuators can improve product quality and provide superior performance.


With the advancement of industrial technology, the strict technical conditions of various electromechanical equipment have placed higher and higher technical requirements on servo motors. At the same time, the application scope of coreless motors has completely broken away from the limitations of high-end products and is rapidly expanding in general applications. Application scope on low-end products such as civilian products to widely improve product quality.