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七十年代,国际上逐渐以微型电机牙钻取代了传统的三关节低速牙钻,大部分国家采用微型直流电机或气动马达。其后又出现了微型交流电机牙钻。由于它结构简单,运行可靠,使用寿命长,因而是目前各国致力研究的课题之一。我们在七七、七八两年,研制了三相定点变频电源驱动的微型三相交流异步电动机牙钻,取得初步成果。在设计方案选取上,为简化电源结构和降低成本,采用定点调速代替无级调速。在电源设计中,使电源输出电压随频率作正比变化,从而保证在不同频率下电机能有近似恒定的工作特性。
Seventies, the international gradually miniature dental drills to replace the traditional three-joint low-speed dental drill, most countries use micro-DC motor or air motor. Then appeared miniature AC motor dental drill. Due to its simple structure, reliable operation and long service life, it is one of the topics that various countries are devoted to research. We have developed the three-phase fixed-point variable frequency power-driven miniature three-phase AC asynchronous motor dental drill in seven or seven or eight years, and achieved initial results. Selection of design options, in order to simplify the power structure and reduce costs, the use of fixed-point speed control instead of stepless speed regulation. In the power supply design, the output voltage of the power supply is changed in proportion to the frequency so as to ensure that the motor can have approximately constant operating characteristics under different frequencies.