You may have heard of the hollow cup motor. What is the hollow cup motor? What is the difference between it and the general motor? What kind of permanent magnet is used in the hollow cup motor? Today, let's take a look at these questions.
With the continuous development of science and technology, motor technology is also constantly innovating. Especially nowadays, the industrial field has continuously put forward higher expectations and requirements for the servo characteristics of motors, and hollow cup motors have come into being. Hollow cup motors belong to DC permanent magnet servo and control motors, and can also be classified as micro motors.
Hollow cup motors have outstanding energy-saving characteristics, sensitive and convenient control characteristics, and stable operation characteristics, and their technological advancement is very obvious. As a high-efficiency energy conversion device, it represents the development direction of motors in many fields.
The Structure And Principle Of Hollow Cup Motor
The figure below is a simplified diagram of the structure of a general hollow cup motor. The hollow cup motor is a DC permanent magnet motor. The main difference between it and ordinary brushed and brushless DC motors is that it uses a coreless rotor called a hollow cup rotor.
The rotor is directly wound with wires, without any other structure to support the windings. The windings themselves are made into a cup shape, which constitutes the rotor structure (as shown below). Due to the change in the rotor structure, the running characteristics of the motor have been greatly improved. It not only has outstanding energy-saving characteristics, but more importantly, it has control and drag characteristics that iron core motors cannot achieve.
Hollow cup motors are divided into two types: brushed and brushless. The rotor of the brushless hollow cup motor has no iron core, and the stator of the brushless hollow cup motor has no iron core. Common hollow cup motor models on the market have diameters of Φ4, Φ6, Φ7, Φ8, Φ10, Φ12, Φ15, etc.
Advantages and applications of hollow cup motors
Hollow cup motors have 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 the stator, smooth speed curve, low noise, and good heat dissipation.
The application of hollow cup motors has developed rapidly in the past ten years after entering the large industrial and civilian fields By taking advantage of the hollow cup motor's lightweight, small size, and low energy consumption, the weight of the aircraft can be reduced to the maximum extent.
4. Various civil electrical appliances and industrial products. Using the hollow cup motor as an actuator can improve the product grade and performance.
5. Because the hollow cup motor is small in size, many products with relatively small volume requirements use the hollow cup as the power element. For example; toy gifts (toy cars, aircraft models, etc.), beauty massage products (face brushes, induction instruments, facial massagers, etc.), daily necessities (electric toothbrushes, shampoo brushes, hair straighteners, etc.).
Hollow Cup Motor Magnets
Hollow cup motors generally use sintered NdFeB permanent magnets, which have the characteristics of high remanence, high coercivity, and high magnetic energy product. It is the most suitable permanent magnet material for hollow cup motors on the market. Under the same size of motor and wind data, the strength of the magnetic steel performance directly affects the speed of the motor. Common NdFeB magnets suitable for hollow cup motors are in the shape of rings, with performance such as N40, N45, etc., and a temperature resistance of about 80℃-100℃.