基于双向可控硅的无“频闪”电机转速控制

Flickering Free Motor Speed Control Using Triac

设计了一款利用双向可控硅(Triac)控制电机转速的无"频闪"电路。鉴于传统可控硅导通角控制在电感性负载情形下存在"频闪"的缺点,结合Triac的伏—安特性,进行了电路设计。设计后,触发时刻由齐纳管电压和电机反电动势之差决定,并保持齐纳管电压的相对稳定。随着负载的增大,电机反电动势下降,工作电流加强,使得电机的可控转速与加载在电机上的负载无关。电路运行更安全、控制更平滑、成本更低廉,适合诸如钻孔机、电锤等电感性负载的电动工具转速控制。

A circuit controlling the motor speed without flickering is designed using Triode AC semiconductor switch （Triac）. In view of the flickering disadvantage existed in controlling the traditional thyristor conducting angle in the case of inductive load, and combined with volt-ampere characteristics of Triac, the circuit design is performed. After the design, the triggering timing is determined by the difference between the voltage of the zener and the counter electromotive force of the motor, and the relative stability of the zener voltage is maintained. With the load increase, the counter electromotive force of the motor is decreased and the working current is strengthened, so that the controllable speed of the motor is independent on the load on the motor. Such a circuit is with safer operation, smoother control and lower cost, which is suitable for the motor speed control of electric tools with inductive load including drilling machine and electric hammer.