| With the rapid development of electronic technology and the emergence of high performance permanent magnet materials, the performance of permanent magnet brushless DC motor has been greatly improved in original basis. The permanent magnet brushless DC motor is adopted in industry filed widely.At present, the most use of the electric power steering motor for electric forklift is brush DC motor, but the electric brush and commutator make its complex in structure, phase change will produce a spark and wear that reduce the reliability, needing regular maintenance, maintenance costs increase, at the same time, the existence of the commutator also affects the motor dynamic performance. Compared to the brush DC motor, permanent magnet brushless DC motor costs higher, but has the advantages of simple structure, no electric spark and wear, high efficiency, high reliability, longer life,convenient control and quick response due to the absence of brush and commutator. Electric forklift electric power steering motor will gradually be replaced by permanent magnet brushless DC motor. According to the actual needs of enterprises, this paper designs and studies the electric power steering system of electric power steering.First, this paper introduces the basic structure and characteristic of permanent magnet brushless DC motor, and taking an example of permanent magnet brushless DC motor with three-phase poles expounds its working principle, and then the mathematical model of permanent magnet brushless DC motor was deduced, at the same time analyzed the mechanical characteristics and starting characteristics of permanent magnet brushless DC motor.Second, completed the permanent magnet brushless DC motor electromagnetic design and mechanical structure design. With the aid of a rotary motor cad software Ansoft Rmxprt the motor model is established. And the performance of the permanent magnet brushless DC motor has carried on the preliminary analysis, for subsequent magnetic field of permanent magnet brushless DC provide the basis of finite element analysis. In addition, completed the design of mechanical structure of the motor such as casing, end cover, then draw the overall assembly drawing of the motor.Again, with the aid of the electromagnetic field finite element analysis software Ansoft16 motor Maxwell 2d simulation model is established, the design of this article carries out the static analysis of permanent magnet brushless DC motor, the no-load transient analysis andload transient analysis. The rationality of the design of magnetic circuit of permanent magnet brushless DC motor, running stability, and requirements of the motor temperature rise was analyzed and validated. In addition, we also research the influence of motor stator chute in reluctance torque of permanent magnet brushless DC motor.Finally, the permanent magnet brushless DC motor principle prototype is researched.Experimental results show that the performance of the prototype meet the design requirements. |
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