Design And Analysis Of Rare-earth Permanent Magnet Brushless DC Motor

Rare-earth PM brushless DC motor has no brush and no ring, its rotating speed is high and its structure is simple with smaller volume. It has non-excitation wastage and excellent performance, and can be used in aviation, spaceflight, exactitude instrument, industry controller and so on. So study of rare-earth PM brushless DC motor has great meaning.Traditional method of rare-earth PM brushless DC motor design is magnetic circuit, and static state operation point and dynamic operation point were gained by alnico operation curve .But the precise result cannot be gained .So the finite element method (FEM) is applied to analyze the magnetic fields of the motor. And then some important parameters of the motor are calculated accurately, including flux leakage coefficient, computed pole embrace, and computed armature length and so on .This paper presented a new way of rare-earth PM brushless DC motor design, which combine magnetic circuit method with finite element method for getting virtues of the two methods.This paper has introduced the motor's structure, theory and the principium design at first, and then presented that how the new way is used in the rare-earth PM brushless DC motor design in detail, including finite element method of parameters, electromotive force, electro- magnetism torque and so on, which are important for motor's performance.Because the leakage inductance shouldn't be ignored in high-speed motors, the finite element method of leakage inductance of rare-earth PM brushless DC motor are deduced in the fourth sector, and equivalent resistant is presented here, which makes the design more appropriate. Reason and the minimize way of torque ripple were presented also. This paper introduces foundation and method of the test for proving validity of parameters at last.