High-speed motor definition, application, key technology, development direction

Introduction of high-speed motor

High-speed motors usually refer to motors with a speed of more than 10,000 r/min. The high-speed motor is small in size and can be directly connected with high-speed loads, eliminating the need for traditional mechanical speed-increasing devices, reducing system noise and improving system transmission efficiency. At present, the main ones that have successfully achieved high speed are induction motors, permanent magnet motors, and switched reluctance motors.

The main features of high-speed motors are high rotor speed, high frequency of stator winding current and magnetic flux in the iron core, high power density and high loss density. These characteristics determine that high-speed motors have key technologies and design methods that are different from those of constant-speed motors, and the design and manufacturing difficulty is often double that of ordinary-speed motors.

Application areas of high-speed motors:

(1) High-speed motors are used in various applications such as centrifugal compressors in air conditioners or refrigerators.

(2) With the development of hybrid vehicles in the automotive industry, high-speed generators with small size and light weight will be fully valued, and have good application prospects in hybrid vehicles, aviation, ships and other fields.

(3) The high-speed generator driven by the gas turbine is small in size and has high mobility. It can be used as a backup power source for some important facilities, and can also be used as an independent power source or a small power station to make up for the lack of centralized power supply and has important practical value.

The key technology of high-speed motor

High-speed and ultra-high-speed applications have broad prospects but at the same time bring extremely high challenges to the motor. After combining these problems with similar items, we found that there are six categories. They are heat dissipation, type selection, rotor structure, vibration and noise, high-efficiency design, and bearings.

At present, there are two main protection measures: one is to use carbon fiber to bind the permanent magnet, and the other is to add a high-strength non-magnetic alloy protective sleeve outside the permanent magnet. However, the electrical conductivity of the alloy sheath is relatively large, and the space and time harmonics will generate a large eddy current loss in the alloy sheath. The electrical conductivity of the carbon fiber sheath is much smaller than that of the alloy sheath, which can effectively suppress the eddy current in the sheath. However, the thermal wire of the carbon fiber sheath is very poor, the heat of the rotor is difficult to dissipate, and the processing technology of the carbon fiber sheath is complex, which requires high processing accuracy. However, for high-speed external rotor permanent magnet motors, protection measures are not required, so there are few studies on rotor stress analysis.

The main research and development directions of high-speed motors are:

Research on key issues of high-power high-speed motors and ultra-high-speed motors; coupling design based on multi-physics and multi-disciplines; theoretical research and experimental verification of stator and rotor losses; permanent magnet materials with high strength and high temperature resistance, high thermal conductivity Development and application of new materials such as fiber materials; research on high-strength rotor lamination materials and structures; application of high-speed bearings under different power and speed levels; design of good heat dissipation systems; development of high-speed motor control systems; meeting industrialization requirements Rotor processing and assembly new technology.

by Jessica