| About two-thirds of China's industrial power consumption is consumed by the motor dragging the load;among them,the power consumption of centrifugal loads such as fans and pumps accounts for about half of it,while the shaft power and speed of the centrifugal loads are cubic It is proportional to the output power of the centrifugal load when the speed decreases,so the research on the speed regulation of the centrifugal load has good theoretical significance and application value.Magnetic coupler can realize non-contact speed and torque transmission,and has the characteristics of light load start and overload protection.Magnetic coupler belongs to variable slip speed regulation,so in the state of large slip speed regulation,slip loss(also called eddy current loss)will be formed between the inner and outer rotors.Most of the existing cage rotor magnetic couplers use the mature and reliable Y2 series squirrel cage rotor as the inner rotor,and the permanent magnet rotor as the outer rotor,that is,the slip loss occurs in the inner rotor.The outer rotor shield cannot be dissipated outwards,causing most of the heat to be transmitted to the outer rotor permanent magnets through the air gap,which increases the temperature of the permanent magnets.When the maximum working temperature of the permanent magnets is reached or exceeded,the permanent magnets will be weakened or even permanent demagnetization.In addition,Y2 series squirrel cage rotors have short-circuited end rings at both ends,which increase the axial length of the coupler.In order to solve the above problems,this paper designs an Outer-caged Rotor Magnetic Coupler(ORMC),which uses the cage rotor as the outer rotor and the permanent magnet rotor as the inner rotor,and is designed to be suitable for its stability The heat dissipation structure of the operation can make the ORMC operate stably for a long time under the conditions of air cooling and large slip.In addition,the outer cage rotor structure designed in this paper also eliminates the squirrel cage end ring in the inner cage rotor structure,which effectively shortens the axial length of ORMC and improves its running stability.The main research works done in this article are:(1)The development and status of magnetic couplers at home and abroad are described,the advantages and disadvantages of different types are analyzed,and an outer cage rotor magnetic coupler-ORMC is designed.The ORMC is analyzed by analytical methods and finite element methods.The air gap magnetic density was analyzed and calculated to establish the ORMC torque equation required in this paper.(2)Based on the structure characteristics of ORMC,an eddy current loss calculation model suitable for ORMC is established.By analyzing the influence of key parameters on eddy current loss,the important parameters of the model are determined.The permanent magnet is a key part of its stable operation,but it is more sensitive to temperature.Through the analysis of the output speed,output torque and eddy current loss of ORMC,the operating point of the largest eddy current loss of ORMC is the slip rate of 1/3 At this time,the magnetic properties of the permanent magnet are most affected.(3)The temperature field analysis of the maximum working point of eddy current loss through the finite element method verifies that the designed heat dissipation structure can effectively reduce the operating temperature of the ORMC permanent magnet,ensuring that the temperature rise of the permanent magnet when the eddy current loss is maximum is still less than its maximum Allowable operating temperature. |
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