对新型电动自行车的关键动力部件——直流无刷电机作了深入的剖析与设计。直流无刷电机是一种具有高效率、低磨损、低噪声的新型直流电机机种。文中所介绍的电动自行车中使用的直流无刷电机, 系参考英国Pats2cent re 国际实验室协作设计产品, 采用全电子操纵系统, 电动自行车的最高时速可达25kmöh , 1 次充电行程为64km。该电机的功率为350W , 重6kg, 具有自充电与过压过流保护功能, 效率可达85% , 性能综合指标远优于传统 的以有刷电机为动力的电动自行车。 关键词: 位置传感器; 无接触换向; 气隙磁密 Abstract: Th is paper intends to make a bet ter design on the DC mo to r, the key part of the new style elect ric bicy2 cle, after the detailed analysis. The DC mo to r w ithout coal brushes is in a new style,w ith h igher wo rk rate, less w ear and tear and low er no ise. Th is k ind ofmo to r discussed in th is paper, is designed in reference to the p roduct de2 signed by Patscent re Internat ional L ab,U K,w h ich is operated w ith elect ronic system comp letely, in the top speed of 25km per hour, covering the distance of 64km each t ime it’s charged. Themo to r is 6kg in w eigh t,w ith the pow er of 350W ,w h ich has the funct ion of self- charge, and comp lete p ro tect ion w hen the elect ric current and vo ltage is over the no rmal levels in the rate clo se to 85%. The comp rehensive index of the funct ions of th is k ind of mo to r is much bet ter than that of all the t radit ional ones w ith coal brushes. Key words: po sit ional senso r; exchange ofA C and D C; the air- space inside and the th ickness ofmagnet ic field in2 tensity