Zhu Qiqiu from the School of Electrical and Information Engineering of Jiangsu University and Prof. J. Hugel from the Swiss Federal Institute of Technology in Zurich jointly developed the world's first industrial prototype of bearingless permanent magnet sheet motor with a power of 4kW.
The origin and development of bearingless motors
After Ferraris and Tesla invented the multiphase AC system, in the mid-1980s, Dovolo Wolski invented a three-phase asynchronous motor that does not require brushes and commutators, but operates at high speed for long periods of time. Bearing maintenance is still a problem.
After World War II, the development of DC magnetic bearing technology made it possible to operate the motor and transmission system without contact, but this transmission system is expensive because ferromagnetic objects cannot be stably suspended in a constant magnetic field. The invention of the active magnetic bearing solves this problem, but the use of the active magnetic bearing to support the rigid rotor imposes a control force on five degrees of freedom, and the magnetic bearing is bulky, complicated in structure, and high in cost.
In the second half of the 20th century, in order to meet the development and utilization of nuclear energy, ultra-high-speed centrifugal separation was required to produce enriched uranium. Magnetic bearings can meet the requirements of high-speed motor support. So, various magnetic bearing plans were started in Europe. In 1975, Hermann applied for a patent for a bearingless motor. The patent proposed a relationship between the pole pair number of the motor winding and the pole pair of the magnetic bearing windings of ±1. With Herman's proposal, it was impossible to manufacture a bearingless motor at that time.
With the further improvement of the magnetic properties of magnetic materials, it has established a strong competitive position for permanent magnet synchronous motors. At the same time, with the application of bipolar transistors and the combination of the lossless switching circuit proposed by Berliner, it is possible to manufacture a new generation of high performance power amplifiers that meet the requirements of bearingless motors. Around 1985, the emergence of fast and load-capable power switching devices and digital signal processors made it possible to apply more than 20 years of AC motor vector control technology, thus solving the problem of digital control of bearingless motors. On the basis of these technological advances, Bicker of the Federal Institute of Technology in Zurich, Switzerland, first produced a bearingless motor in the late 1980s.
Almost at the same time as Bicker, in 1990 A. Chiba of Japan realized the bearingless technology of reluctance motors for the first time.
In 1993, R.Schoeb of the Federal Institute of Technology in Zurich realized the bearingless technology of AC motors for the first time.
The bearingless motor has achieved practical application. The key breakthrough is the development of a bearingless permanent magnet synchronous blade motor by Baletta in the Federal Institute of Technology in Zurich in 1998. The motor structure is simple, which greatly reduces the cost of the control system and has great application value in many fields. .
In 2000, S.Sliber of the Federal Institute of Technology in Zurich developed a bearingless single-phase motor, once again taking a step forward in the history of bearingless motor research, reducing the cost of the control system, making the practical application of bearingless motors not just conceivable And economic. Bearingless motors are as simple as motors supported by mechanical bearings. The electrical control system is not complicated, and it is economical to use bearingless motors in many areas. We believe that this technology will be widely used in China in the near future.
Bearingless motor characteristics and applications
The bearingless motor is based on the similarity of the principle of electromagnetic force generated by the magnetic bearing and the motor. The winding generating the radial force in the magnetic bearing is mounted on the stator of the motor, and the independent control of the motor torque and the radial levitation force is realized through decoupling control. . Bearingless motors have all the advantages of magnetic suspension magnetic bearings, requiring maintenance-free, long-life operation, and the transmission of sterile, non-polluting and toxic and hazardous liquids or gases is a typical application for bearingless motors. The following applications are currently available.
1. Semiconductor industry
Corrosive chemical liquids are used in etching, plate making, cleaning or polishing. The quality of the product depends largely on the quality of the chemical liquid. The liquid transfer pump is a key link. For chemical liquids such as acid, organic solvents, etc., the pump must be reliably transported without pollution, and the pump must have corrosion resistance and temperature resistance requirements. Conventional pneumatic and sheet pumps have a short life span. Most of the temperature resistance is only about 100 °C. The moving valves and sheets still produce a small amount of particles, and the liquid transmission also has uneven pulsation, which affects the quality of the process. The use of a bearingless motor sealed pump can solve the defects in the traditional transmission, and greatly meet the requirements of the production process of precision semiconductor devices. At present, a bearingless motor sealed pump with a power of 300W has been applied in the semiconductor industry.
2. Under the harsh conditions of radioactive environment or high temperature radiation environment in chemical industry, the use of bearingless motor sealed pump for waste treatment can solve the problem of mechanical bearing wear and maintenance. In the chemical industry, the demand for effective sealed transmission and production systems is further enhanced. Conventional shaft-sealed sealed pumps and mechanical bearings require lubrication. It is reported that 80% of failures are caused by seal failures, and 20% are bearings and connections. And other faults. For safe production and environmental pollution, the use of bearingless motor sealed pumps is the best choice. At present, the Zurich Federal Institute of Technology and Sulzer Pumps have completed the development and testing of a 30kW-free bearingless sealed pump prototype and entered the trial operation phase.
3. Life sciences
The heart is the perpetual motion of life, and it is difficult to repair once it fails. The partial or complete replacement of heart function by artificial heart has become a evangelist of the life of heart patients. Blood pumps that use mechanical bearings create friction and heat, which can damage blood cells, cause hemolysis, blood clotting and blood clots, and even endanger the patient's life. A blood pump driven by a bearingless permanent magnet motor developed by the Zurich Federal Institute of Technology and Levitronix and a left ventricular assist device that can be transplanted into the human body have been clinically applied.
Research and application prospects
China has carried out research on magnetic levitation trains and magnetic bearings for many years. Since the late 1990s, Jiangsu University, Shenyang University of Technology and Nanjing University of Aeronautics and Astronautics have received funding from the National Natural Science Foundation, and carried out research on bearingless motors in theory and experiment. Some achievements have been made. Zhu Qiqiu from the School of Electrical and Information Engineering of Jiangsu University and Prof. J. Hugel from the Swiss Federal Institute of Technology in Switzerland jointly carried out the research and application of the bearingless permanent magnet synchronous motor with a power of 4kW, and solved the key technical problems such as sensor detection and power loss. The world's first bearingless permanent magnet sheet motor with a power of 4kW is expected to be used in the chemical industry and semiconductor industry this year.
In the United States, Japan and other countries, bearingless motors have been applied in the fields of life sciences, pharmaceutical industry, chemical industry, semiconductor industry, food industry and so on. With the further development of China's economy, traditional transmission and transmission methods will be changed in many special electric transmission fields, which will play an important role in improving product quality, reducing costs and reducing pollution. Therefore, in China, bearingless motors have a large potential application market, and it is realistic and far-reaching to actively carry out research and application of bearingless motors.
The origin and development of bearingless motors
After Ferraris and Tesla invented the multiphase AC system, in the mid-1980s, Dovolo Wolski invented a three-phase asynchronous motor that does not require brushes and commutators, but operates at high speed for long periods of time. Bearing maintenance is still a problem.
After World War II, the development of DC magnetic bearing technology made it possible to operate the motor and transmission system without contact, but this transmission system is expensive because ferromagnetic objects cannot be stably suspended in a constant magnetic field. The invention of the active magnetic bearing solves this problem, but the use of the active magnetic bearing to support the rigid rotor imposes a control force on five degrees of freedom, and the magnetic bearing is bulky, complicated in structure, and high in cost.
In the second half of the 20th century, in order to meet the development and utilization of nuclear energy, ultra-high-speed centrifugal separation was required to produce enriched uranium. Magnetic bearings can meet the requirements of high-speed motor support. So, various magnetic bearing plans were started in Europe. In 1975, Hermann applied for a patent for a bearingless motor. The patent proposed a relationship between the pole pair number of the motor winding and the pole pair of the magnetic bearing windings of ±1. With Herman's proposal, it was impossible to manufacture a bearingless motor at that time.
With the further improvement of the magnetic properties of magnetic materials, it has established a strong competitive position for permanent magnet synchronous motors. At the same time, with the application of bipolar transistors and the combination of the lossless switching circuit proposed by Berliner, it is possible to manufacture a new generation of high performance power amplifiers that meet the requirements of bearingless motors. Around 1985, the emergence of fast and load-capable power switching devices and digital signal processors made it possible to apply more than 20 years of AC motor vector control technology, thus solving the problem of digital control of bearingless motors. On the basis of these technological advances, Bicker of the Federal Institute of Technology in Zurich, Switzerland, first produced a bearingless motor in the late 1980s.
Almost at the same time as Bicker, in 1990 A. Chiba of Japan realized the bearingless technology of reluctance motors for the first time.
In 1993, R.Schoeb of the Federal Institute of Technology in Zurich realized the bearingless technology of AC motors for the first time.
The bearingless motor has achieved practical application. The key breakthrough is the development of a bearingless permanent magnet synchronous blade motor by Baletta in the Federal Institute of Technology in Zurich in 1998. The motor structure is simple, which greatly reduces the cost of the control system and has great application value in many fields. .
In 2000, S.Sliber of the Federal Institute of Technology in Zurich developed a bearingless single-phase motor, once again taking a step forward in the history of bearingless motor research, reducing the cost of the control system, making the practical application of bearingless motors not just conceivable And economic. Bearingless motors are as simple as motors supported by mechanical bearings. The electrical control system is not complicated, and it is economical to use bearingless motors in many areas. We believe that this technology will be widely used in China in the near future.
Bearingless motor characteristics and applications
The bearingless motor is based on the similarity of the principle of electromagnetic force generated by the magnetic bearing and the motor. The winding generating the radial force in the magnetic bearing is mounted on the stator of the motor, and the independent control of the motor torque and the radial levitation force is realized through decoupling control. . Bearingless motors have all the advantages of magnetic suspension magnetic bearings, requiring maintenance-free, long-life operation, and the transmission of sterile, non-polluting and toxic and hazardous liquids or gases is a typical application for bearingless motors. The following applications are currently available.
1. Semiconductor industry
Corrosive chemical liquids are used in etching, plate making, cleaning or polishing. The quality of the product depends largely on the quality of the chemical liquid. The liquid transfer pump is a key link. For chemical liquids such as acid, organic solvents, etc., the pump must be reliably transported without pollution, and the pump must have corrosion resistance and temperature resistance requirements. Conventional pneumatic and sheet pumps have a short life span. Most of the temperature resistance is only about 100 °C. The moving valves and sheets still produce a small amount of particles, and the liquid transmission also has uneven pulsation, which affects the quality of the process. The use of a bearingless motor sealed pump can solve the defects in the traditional transmission, and greatly meet the requirements of the production process of precision semiconductor devices. At present, a bearingless motor sealed pump with a power of 300W has been applied in the semiconductor industry.
2. Under the harsh conditions of radioactive environment or high temperature radiation environment in chemical industry, the use of bearingless motor sealed pump for waste treatment can solve the problem of mechanical bearing wear and maintenance. In the chemical industry, the demand for effective sealed transmission and production systems is further enhanced. Conventional shaft-sealed sealed pumps and mechanical bearings require lubrication. It is reported that 80% of failures are caused by seal failures, and 20% are bearings and connections. And other faults. For safe production and environmental pollution, the use of bearingless motor sealed pumps is the best choice. At present, the Zurich Federal Institute of Technology and Sulzer Pumps have completed the development and testing of a 30kW-free bearingless sealed pump prototype and entered the trial operation phase.
3. Life sciences
The heart is the perpetual motion of life, and it is difficult to repair once it fails. The partial or complete replacement of heart function by artificial heart has become a evangelist of the life of heart patients. Blood pumps that use mechanical bearings create friction and heat, which can damage blood cells, cause hemolysis, blood clotting and blood clots, and even endanger the patient's life. A blood pump driven by a bearingless permanent magnet motor developed by the Zurich Federal Institute of Technology and Levitronix and a left ventricular assist device that can be transplanted into the human body have been clinically applied.
Research and application prospects
China has carried out research on magnetic levitation trains and magnetic bearings for many years. Since the late 1990s, Jiangsu University, Shenyang University of Technology and Nanjing University of Aeronautics and Astronautics have received funding from the National Natural Science Foundation, and carried out research on bearingless motors in theory and experiment. Some achievements have been made. Zhu Qiqiu from the School of Electrical and Information Engineering of Jiangsu University and Prof. J. Hugel from the Swiss Federal Institute of Technology in Switzerland jointly carried out the research and application of the bearingless permanent magnet synchronous motor with a power of 4kW, and solved the key technical problems such as sensor detection and power loss. The world's first bearingless permanent magnet sheet motor with a power of 4kW is expected to be used in the chemical industry and semiconductor industry this year.
In the United States, Japan and other countries, bearingless motors have been applied in the fields of life sciences, pharmaceutical industry, chemical industry, semiconductor industry, food industry and so on. With the further development of China's economy, traditional transmission and transmission methods will be changed in many special electric transmission fields, which will play an important role in improving product quality, reducing costs and reducing pollution. Therefore, in China, bearingless motors have a large potential application market, and it is realistic and far-reaching to actively carry out research and application of bearingless motors.
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