| Centrifugal loads such as fans and pumps are widely used in industry.However,the traditional method uses valves or baffles to adjust the flow rate,which leads to lower operating efficiency.In this paper,a magnetic coupling is installed between the driving motor and the centrifugal load to adjust the speed to obtain better energy-saving benefits.Since the magnetic coupling is used for slip speed regulation,that is,the greater the slip,the greater the heat generation.If the heat cannot be dissipated in time,the permanent magnet will be irreversibly and permanently demagnetized,causing the magnetic coupling to fail.The existing air-cooled cylindrical magnetic coupling has problems such as low operating efficiency and poor heat dissipation capacity.A Speed-Regulating Outer Squirrel Cage Magnetic Coupling(SOMC)is proposed in this paper,which uses the SOMC conductor rotor as the outer rotor,and uses a good conductor end ring to connect the conductor rotor.The guide bars are connected to make the induced current flowing through the guide bars form a closed loop,so as to solve the problem of low operating efficiency caused by only induced eddy currents in the existing endless ring cage rotor magnetic coupling guide bars;in addition,by adding radiating fins and shaft end fan blades on the surface of the outer yoke and the end surface of the conductor rotor,respectively,to effectively solve the heat generated by the slip speed regulation.Around the SOMC proposed in this article,the following research work has been carried out:(1)The research background and significance of magnetic couplings are introduced,the advantages and disadvantages of speed control of frequency converters,fluid couplings and magnetic coupling are compared and analyzed;the current development status of magnetic couplings at home and abroad,classification of speed control magnetic couplings and heat dissipation methods are introduced in detail;An Speed-Regulating Outer Squirrel Cage Magnetic Coupling is proposed to solve the problems of excessive axial dimension and poor heat dissipation capacity of the existing cylindrical magnetic coupling.(2)Based on the equivalent magnetic circuit method,the magnetic circuit structure of SOMC is analyzed,the magnetic density of air gap and electromagnetic torque model are established;the speed regulation characteristics and operating efficiency of SOMC under different load conditions are analyzed,the mathematical expressions of SOMC loss and operating efficiency varying with slip rate are given.(3)The starting and running characteristics,speed regulation characteristics,overload characteristics and locked rotor characteristics of SOMC are analyzed;the principle of SOMC axial magnetic pulling force generation is introduced,and based on the equivalent magnetic charge method,the calculation model of axial magnetic tension is established,the magnitude of the SOMC axial magnetic pull is analyzed by the finite element method under different coupling lengths,which provides a basis for the design of the prototype speed control mechanism.(4)The basic principles of heat transfer are introduced,the temperature field mathematical model and flow field control equations of SOMC are established,the three-dimensional heat dissipation model of SOMC is established by Solid Works,and the thermal flow field is analyzed by Flow simulation.The results show that: After the heat dissipation structure is installed,the air flow rate outside the conductor rotor of the SOMC model is increased from 10.7m/s to 25.7m/s,the air flow rate inside the conductor rotor is increased from 8.5 m/s to 15 m/s,and the maximum temperature of the permanent magnet is reduced from 98.67℃ to 59.54℃,which proves the effectiveness of the heat dissipation structure.(5)A 37 k W experimental prototype of SOMC is designed and developed,the prototype experimental platform is built,SOMC’s transmission performance,speed control performance and temperature are tested,the experimental data is compared with the theoretical value and the simulation value,and it is proved that the deviation is within the error precision range,which verifies the correctness of the SOMC’s theory and finite element analysis in this paper. |
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