| In the ship gyro stabilizer application,the motor needs to drive the gyro load with thick shaft and large moment of inertia to rotate at a high speed,therefore,the rotor core is very thin and the starting time is so long.Moreover,the inside of the gyro stabilizer is in a vacuum-tight environment,which is not conducive to heat dissipation,so the motor is required to have high efficiency.According to the technical indicators,a 10-pole 12-slot permanent magnet synchronous motor(PMSM)was designed and prototyped.However,when the gyro shaft is thicker or the speed is higher,it will be difficult to meet the requirements for the motor,and Halbach PMSM will be an option.In this paper,the research on the Halbach PMSM for the ship gyro stabilizer is carried out for the particularity of thin rotor core and the problems of the over-current during startup and the low efficiency of the prototype.The main contents are as follows:(1)Design and Optimization of 10/12 PMSM.The electromagnetic design of 10/12 PMSM is introduced,which is optimized by digging slot between the rotor poles,and the electromagnetic performances of the initial motor and optimized motor are compared by finite element method.The finite element analysis shows that after optimization,the flux leakage of the permanent magnet is effectively suppressed with the no-load air-gap flux density and waveform of the no-load back EMF obviously improved,as well as the cogging torque significantly reduced.(2)Experiment and Analysis of 10/12 PMSM.The prototype is made according to the design scheme,and the experimental platform is built to test it for verifying the effectiveness of the design scheme.The problems of 10/12 PMSM is pointed out by the prototype experiment and the reasons of the problems are analyzed.The field-circuit coupling simulation platform is established,the system efficiency simulation results by introducing the correction coefficient of controller loss and mechanical loss are compared with the measured results to verify the effectiveness of the field-circuit coupling analysis method,and lay the foundation for the field-circuit coupling analysis of the Halbach PMSM design scheme.The comparison results are more consistent and the maximum error is 5%,which can meet the needs of engineering applications,so the method has certain feasibility.(3)Design and optimization of Halbach PMSM.Based on 10/12 PMSM,the electromagnetic performances of 10/12 Halbach and 10/12 PMSM are compared,and then the excellent properties of Halbach array applied to PMSM are summarized.In order to solve the shortcomings of 10/12 PMSM,from the perspective of pole-slot combination and electromagnetic load,the inductance and efficiency are used as optimization indicators to design and analyze two different pole-slot combination Halbach PMSM.Then the design scheme is determined through the performance comparison and comprehensive consideration,and it is optimized and analyzed from the perspective of reducing the process.The finite element analysis shows that the Halbach is more suitable for the motor with thin rotor core.Under the premise of the main performance index,the rotor core thickness of 10/12 Halbach can be reduced by 56.6%,which can drive the gyro load with thicker shaft.Compared to 10/12 PMSM,the d-axis inductance and the q-axis inductance of 6/9 Halbach can be more than doubled,with higher operating efficiency under different loads at rated speed and a wider efficient operating area.(4)Field-Circuit Coupling Simulation of Halbach PMSM.Based on the field-circuit coupling simulation platforms of two-phase conduction control and vector control,6/9 Halbach and 10/12 PMSM under rated condition are analyzed and compared.The results show that the 6/9 Halbach has lower torque ripple and higher rated efficiency under the two control modes,which further validates the effectiveness of the design scheme. |
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