Hollow cup motor and permanent magnet

Everyone may have heard of the hollow cup motor. What is the hollow cup motor and how is it different from the general motor? What kind of permanent magnets are used in hollow cup motors? Today I will take you to understand the hollow cup motor and its permanent magnet.

With the continuous development of science and technology, motor technology is also constantly innovating. Especially nowadays, the industrial field has continuously raised higher expectations and requirements for the servo characteristics of electric motors, and hollow cup motors have emerged. The hollow cup motor is a DC permanent magnet servo and control motor, which can also be classified as a micro special motor. The hollow cup motor has outstanding energy-saving characteristics, sensitive and convenient control characteristics and stable operation characteristics, and technical advancement is very obvious. As a high-efficiency energy conversion device, it represents the development direction of electric motors in many fields.

The structure and principle of hollow cup motor

The following figure is a schematic diagram of the structure of a general hollow cup motor. The hollow cup motor is a DC permanent magnet motor. The main difference from ordinary brushed and brushless DC motors is the use of ironless rotors, also called hollow cup rotors.

The rotor is made directly by wire winding. There is no other structure to support these windings. The winding itself is made into a cup shape to form the structure of the rotor (as shown below). Due to changes in the rotor structure, the motor’s operating characteristics have been greatly improved. Not only does it have outstanding energy-saving features, but more importantly, it has control and drag characteristics that cannot be achieved by iron core motors.

The hollow cup motor is divided into two types, brushed and brushless. The rotor of the brushed hollow cup motor has no iron core, and the stator of the brushless hollow cup motor has no iron core. Common types of hollow cup motors in the market include diameters Φ4, Φ6, Φ7, Φ8, Φ10, Φ12, Φ15, etc.

The advantages and application of hollow cup motor

The hollow cup motor has a series of advantages such as high power density, high efficiency, no torque lag, no cogging effect, low starting torque, no radial force between the rotor and stator, smooth speed curve, low noise, good heat dissipation and other advantages .

The application of the hollow cup motor has been rapidly developed in the past ten years from the military and high-tech fields to the large industry and civil fields, especially in industrially developed countries, which has involved most industries and many products.

Follow-up system that needs quick response. Such as the rapid adjustment of the flight direction of the missile, the follow-up control of the high magnification optical drive, fast automatic focusing, highly sensitive recording and testing equipment, industrial robots, bionic prosthetics, etc., the hollow cup motor can meet its technical requirements well.

Products that require smooth and long-lasting driving elements. Such as all kinds of portable instruments, personal personal equipment, field equipment, electric vehicles, etc., the same set of power supplies, power supply time can be extended more than doubled.

Various aircrafts, including aviation, aerospace, aeromodelling, etc. The hollow cup motor has the advantages of light weight, small size and low energy consumption, which can reduce the weight of the aircraft to the greatest extent.

All kinds of civil appliances and industrial products. The use of hollow cup motors as actuators can improve product quality and provide superior performance.

Because of the small size of the hollow cup motor, many small-volume products use hollow cups as power components. For example; toy gifts (toy cars, model airplanes, etc.), beauty massage products (face washing brushes, induction instruments, face massagers, etc.), daily necessities (electric toothbrushes, shampoo brushes, straighteners, etc.)

Hollow cup motor magnet

Hollow cup motors generally use sintered NdFeB permanent magnets, which have the characteristics of high remanence, high coercive force, and high magnetic energy product, and are currently the most permanent magnet materials on the market that meet the requirements of hollow cup motors. Under the same size motor and winding data, the strength of the magnetic steel directly affects the speed of the motor. The common NdFeB magnets suitable for hollow cup motors are ring-shaped, with properties such as N40, N45, etc., and the temperature resistance is around 100 ° C.