Optimization Design of High-speed Interior Permanent Magnet Motor with High Torque Performance Based on Multiple Surrogate Models

In order to obtain better torque performance of high-speed interior permanent magnet motor(HSIPMM) and solve the problem that electromagnetic optimization design is seriously limited by its mechanical strength, a complete optimization design method is proposed in this paper. The object of optimization design is a 15 kW、20000 r/min HSIPMM whose permanent magnets in rotor is segmented. Eight structural dimensions are selected as its optimization variables. After design of experiment(DOE), multiple surrogate models are fitted, a set of surrogate models with minimum error is selected by using error evaluation indexes to optimize, the NSGA-II algorithm is used to get the optimal solution. The optimal solution is verified by load test on a 15 kW, 20000 r/min HSIPMM prototype. This paper can be used as a reference for the optimization design of HSIPMM.

Analysis of Temperature Rise in High-Speed Permanent Magnet Synchronous Traction Motors by Coupling the Equivalent Thermal Circuit Method and Computational Fluid Dynamics

To solve the problem of temperature rise caused by the high power density of high-speed permanent magnet synchronous traction motors,the temperature rise of various components in the motor is analyzed by coupling the equivalent thermal circuit method and computational fluid dynamics.Also,a cooling strategy is proposed to solve the problem of temperature rise,which is expected to prolong the service life of these devices.First,the theoretical bases of the approaches used to study heat transfer and fluid mechanics are discussed,then the fluid flow for the considered motor is analyzed,and the equivalent thermal circuit method is introduced for the calculation of the temperature rise.Finally,the stator,rotor loss,motor temperature rise,and the proposed cooling method are also explored through experiments.According to the results,the stator temperature at 50,000 r/min and 60,000 r/min at no-load operation is 68℃ and 76℃,respectively.By monitoring the temperature of the air outlets inside and outside the motor at different speeds,it is also found that the motor reaches a stable temperature rise after 65 min of operation.Coupling of the thermal circuit method and computational fluid dynamics is a strategy that can provide the average temperature rise of each component and can also comprehensively calculate the temperature of each local point.We conclude that a hybrid cooling strategy based on axial air cooling of the inner air duct of the motor and water cooling of the stator can meet the design requirements for the ventilation and cooling of this type of motors.

The Slot Number and Air-Gap Effect on Performance of the High-Speed Brushless Permanent Magnet Motor

This paper describes the key issues of high-speed brushless permanent magnet motor design, such as rotor design, stator design, and determination of the main dimensions, and the overall design process was given. In this paper, a two-pole three-phase high-speed brushless PM （permanent magnet） motor with ratings air-gap length and stator slot number on the motor performance of 7.5 kW, 30,000 rpm is designed, and the effect of the different was analyzed. The results show that larger number of stator slot decreases the rotor loss and the rotor torque ripple. Larger air-gap length decreases the rotor loss.

A sensorless efficiency test system for a high-speed permanent magnet synchronous motor

We present a sensorless efficiency test system with energy recovery for a high-speed permanent magnet synchronous motor(PMSM). In the system, two identical high-speed PMSMs are used as the motor under test(MUT)and the load machine(LM),respectively.A new sensorless vector control(VC) method based on a hypothetical reference frame is presented to control both the MUT and the LM.Also,a regenerating unit is used to implement energy circulation to save energy.Experiments were carried out on a prototype, with a digital controller based on the TMS320 F28335, to verify the adequacy of the sensorless VC method.As a result,the efficiency test system achieves the load test at the speed of 21000 r/min without any reduction equipment. During the test, the energy regenerated by the LM could be fed back to the MUT by the regenerating unit, and 81.31% electrical power was saved.In addition, with the proposed sensorless VC method,both the MUT and the LM can work at i_d = 0 without a position sensor.

兆瓦级高速永磁电机新型转子冷却结构研究

兆瓦级高速永磁电机转子侧无强迫冷却措施时转子侧温升高、永磁体失磁风险高,基于此问题,提出一种新型的加强筋转子轴向通风结构,该结构能够提高转子侧的壁面对流散热系数、提升转子侧的散热能力、降低电机温度。以一台1 MW、18000 r/min的高速永磁电机为例,建立该电机的三维全域流固耦合求解模型,基于计算流体力学和有限元法对电机流体场与温度场进行分析,揭示电机在额定工况下的流体与温度分布规律。将新冷却结构与传统冷却结构的散热性能及温升变化进行对比,验证新型冷却结构在提升电机散热性能方面的有效性。最后,分析入口风速对电机最高温度的影响,得到适合该冷却结构的入口风速范围,为外部风压设备的选择提供理论支撑。

兆瓦级超高速内置式永磁电机转子磁极结构优化

为了解决兆瓦级超高速永磁电机转子圆周速度大带来的机械与电气问题,文章提出一种叠片内置磁钢,间隔高强度非导磁加强筋嵌入的磁极结构。针对同一工程实际需求,设计并对比了三种转子磁极结构,分析了各自特点。通过等效环法计算转子强度,并进行结构场仿真验证计算结果。针对机械分析的可行结构,利用电磁性能仿真软件进行电气性能分析,对比三种结构的电磁性能。结果表明,采用非导磁高强度加强筋的新型内置式转子磁极结构机械强度好,电磁性能优异,磁钢用量更少。