1. 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 an important practical value.

High-speed permanent magnet motor

Permanent magnet motors are favored in high-speed applications due to their high efficiency, high power factor, and wide speed range. Compared with the outer rotor permanent magnet motor, the inner rotor permanent magnet motor has the advantages of small rotor radius and strong reliability, and has become the first choice for high-speed motors.

At present, among the high-speed permanent magnet motors at home and abroad, the high-speed permanent magnet motor with the highest power is researched in the United States. The power is 8MW and the speed is 15000r/min. It is a surface-mounted permanent magnet rotor. The protective cover is made of carbon fiber, and the cooling system adopts The combination of air and water cooling is used for high-speed motors matched with gas turbines.

The Swiss Federal Institute of Technology Zurich designed a high-speed permanent magnet motor with the highest speed. The parameters are 500000 r/min, the power is 1kW, the line speed is 261m/s, and the alloy protective sleeve is used.

Domestic research on high-speed permanent magnet motors is mainly concentrated in Zhejiang University, Shenyang University of Technology, Harbin University of Technology, Harbin Institute of Technology, Xi’an Jiaotong University, Nanjing Aerospace Motor, Southeast University, Beihang University, Jiangsu University, Beijing Jiaotong University, Guangdong University of Technology, CSR Zhuzhou Electric Co., Ltd., etc.

They carried out relevant research work on the design characteristics, loss characteristics, rotor strength and stiffness calculation, cooling system design and temperature rise calculation of high-speed motors, and produced high-speed prototypes with different power levels and speeds.

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.