Hollow cup motor and permanent magnet
With the continuous development of science and technology, electric motor technology is also constantly innovating. Especially in today's industrial field, there are constantly higher expectations and requirements for the servo characteristics of electric motors, and hollow cup motors have emerged as a result. Hollow cup motors belong to DC permanent magnet servo and control motors, and can also be classified as micro special motors. The hollow cup motor has outstanding energy-saving characteristics, sensitive and convenient control characteristics and stable operation characteristics, and its progressiveness technology is very obvious. As an efficient energy conversion device, it represents the development direction of electric motors in many fields.
The structure and principle diagram of a hollow cup motor is a schematic diagram of a general hollow cup motor. Hollow cup motors belong to DC permanent magnet motors, and the main difference from ordinary brushed and brushless DC motors is the use of coreless rotors, also known as hollow cup rotors.
The rotor is directly wound with wires, without any other structural support for these windings. The winding itself is made into a cup shape, which constitutes the structure of the rotor (as shown in the figure below). Due to the structural changes of the rotor, the operating characteristics of the electric motor have been greatly improved. It not only has outstanding energy-saving features, 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 brushed hollow cup motors has no iron core, while the stator of brushless hollow cup motors has no iron core. The common models of hollow cup motors in the market include diameters of 4, 6, 7, 8, 10, 12, 15, etc. The advantages and applications of hollow cup motors include high power density, high efficiency, no torque hysteresis, no cogging effect, low starting torque, no radial force between rotor and stator, smooth speed curve, low noise, and good heat dissipation effect. The application of hollow cup electric motors has experienced rapid development in the past decade, especially in industrialized countries, after entering the fields of military and high-tech industries and civilian use. It has already involved most industries and many products. 1. A responsive follow-up system is required. Hollow cup motors can meet the technical requirements of missiles with fast adjustment of flight direction, high magnification optical drive follow-up control, fast automatic focusing, high-sensitivity recording and detection equipment, industrial robots, bionic prosthetics, etc. 2. Products that require stable and long-lasting dragging of driving components. Various portable instruments, personal equipment, field equipment, electric vehicles, etc., with the same power supply, the power supply time can be extended by more than twice. 3. Various aircraft, including aviation, aerospace, model aircraft, etc. By utilizing the advantages of lightweight, small size, and low energy consumption of hollow cup electric motors, the weight of aircraft can be minimized to the greatest extent possible. 4. Various civilian electrical appliances and industrial products. Using a hollow cup motor as the actuator can improve the product's grade and superior performance. 5. Due to the small size of the hollow cup motor, many products with relatively small volume requirements use hollow cups as the most powerful components. For example; Toys and gifts (toy cars, model airplanes, etc.), beauty massage products (facial brushes, hair dryers, facial massagers, etc.), daily necessities (electric toothbrushes, hair brushes, hair straighteners, etc.). Hollow cup motors generally use sintered neodymium iron boron permanent magnets, which have the characteristics of high remanence, high coercivity, and high magnetic energy product. They are currently the most suitable permanent magnet materials for hollow cup motors on the market. Under the same size of motor and winding data, the strength of magnetic steel performance directly affects the speed of the motor. The commonly used neodymium iron boron magnetic steel for hollow cup motors is circular in shape, with properties such as N40, N45, etc., and a temperature resistance of around 80 ℃ -100 ℃.