Design And Performance Analysis Of Low-speed And High-torque Concentrated Winding Permanent Magnet Motors For Mining

With the improvement of science and technology,permanent magnet motors are widely used in coal mining and metallurgical industries.Limited by the working environment of the mine,the problem of heat dissipation has always been a difficult problem for mining motors,and it is also a stumbling block on the road to further increase the power density of permanent magnet motors.Especially for low-speed and high-torque motors,the main temperature rise of the motor comes from the copper loss of the winding,the heat in the stator slot is difficult to dissipate.The heat dissipation effect of the motor is related to the distance between the cooling device and the heat source.As far as the above issues are concerned,this paper proposes a new type of cooling structure for mining motors,the cooling water pipe and the winding are wound side by side and embedded in the stator slot at the same time,and the winding coil is in direct contact with the cooling system.Compared with the common water cooling method of the motor casing,it can directly participate in the heat dissipation of the windings,take away the heat generated by the windings and has higher heat dissipation efficiency.In this paper,the cooling structure of a new type of mining permanent magnet motor is studied,and the main contents are as follows.Firstly,the research status of permanent magnet motor temperature rise and the related structure and principle of permanent magnet motor cooling method are expounded,The advantages and disadvantages of different cooling structures are analyzed,which leads to the necessity of the winding cooling structure studied in this paper.Secondly,according to the technical requirements of the motor,the electromagnetic scheme is designed,and the electromagnetic schemes for the concentrated winding and the distributed winding are respectively made,and the main parameters of the motor are determined.The simulation software is used to simulate and compare the electromagnetic parameters of the motors with the two structures;and the losses of the two motors are simulated and compared.Thirdly,a new type of cooling structure,the winding parallel-wound cooling structure,is proposed,and its design and analysis are carried out.The designed motor winding is a concentrated winding structure,and the coil is a rectangular coil,so the cooling water pipe also adopts a rectangular hollow coil with the same shape and size as the winding,and the cooling medium is passed into it.According to the positional relationship between the winding coil and the cooling water channel,it is divided into three different winding parallel winding cooling structures,and the characteristics and applications of different cooling structures are analyzed.Next,in order to verify the rationality of the designed winding parallel winding cooling structure,a three-dimensional model of the motor is established through reasonable equivalence and assumptions,and the motor is analyzed based on the CFD fluid field and temperature field.The effects of different parallel winding structures and different water inlet speeds on the heat dissipation of the motor under the same parallel winding structure are analyzed,and the optimal heat dissipation method is finally determined.The simulation analysis shows that the cooling water pipes and the windings are wound in parallel to effectively improve the heat dissipation capacity,which verifies the effectiveness of this cooling method.Finally,according to the above temperature field analysis,improving the power density of the motor can reasonably increase the electromagnetic load of the motor on the basis of satisfying the temperature rise.The electromagnetic and temperature field simulations of the improved motor are performed to verify the rationality of the scheme.