Fluid Field Analysis And Temperature Calculation Of Permanent Magnet Torque Motor

In order to improve the utilization rate of materials and reduce the manufacturing cost,permanent magnet torque motor(PMTM)electromagnetic load is designed higher and higher.High temperature rise, coming with high electromagnetic load, it is the key factor threateningsafe operation of the motor. Reasonable design of cooling system can reduce the temperaturerise of the motor, while the accurate calculation of temperature rise can guide the rationaldesign of motor’s cooling system. Changeing the magnetic circuit structure to improve theutilization rate of effective material is also a way to reduce the production cost of the motor.The fluid field, temperature field and electromagnetic field of water cooled PMTM are studiedin this article, main contents are as follows:First of all, the fluid field of water-cooled permanent magnet motor was analyzed. Therelationship between the cooling water flow rate and temperature rise was deduced with theanalytical formula, a relation curve was made, and the curve inflection point was calculated.The curve distribution was validated by the finite volume method and test. In addition, withsame flow, the cooling water pressure drop was analyzed under different channel number ofthe motor, and the relationship between the channel number within limited space and thetemperature rise was studied. Considering the temperature rise and different channel numberdrive loss, reasonable cooling channel number of the PMTM was given.Secondly, the cooling system is improved according to the fluid field analysis, and thesurface and embedded circuit structure of PMTM temperature rise is calculated by analysissoftware FLUENT, and the temperature rise calculation results is contrasted. The test has beendone to illustrate the small error of the method calculation motor temperature rise, which cansatisfy the need of engineering.Finally, in order to reduce manufacturing cost, magnetic circuit structure of the PMTM isstudied, and a embedded magnetic circuit structure with permanent magnet high utilizationrate was used. However, compared with the surface magnetic circuit structure, the magneticleakage of this magnetic structure is large and the air gap flux density waveform is poor.Therefore, the article adopted a series of measures to reduce magnetic leakage, optimize theair gap flux density waveform and reduce the cogging torque of the embedded magnetic structure. The flux leakage factor of the embedded magnetic circuit structure droped to1.51,and the no-load air gap magnetic flux density waveform distortion rate also droped12.05percentage points. The performance and manufacturing cost are contrasted between embeddedand surface magnetic circuit structure for PMTM, and the actual work conditions needs to beconsidered when selecting motor circuit structures.