| 摘要 |
The present invention relates to a device and a method for properly and safely controlling the speed of an automatic door using a brushless direct current motor. An automatic door control device using the brushless direct current motor includes: a voltage control circuit controlling a level of generated voltage using a PWM signal; a PWM control circuit including a variable voltage PWM control circuit capable of varying the voltage input by motor, and a motor PWM control circuit for controlling the speed of the motor; the motor controlling the speed thereof by the PWM control circuit; and a driving transistor comprising a pair of transistors controlling the power applied to coils of the motor by receiving a PWM signal from the PWM control circuit to rotate an inner rotor, wherein one transistor is used to lead the electricity inside by corresponding to the each coil and the other transistor is used to lead the electricity out. The motor is controlled by the motor PWM control circuit when rotating in the high speed. The motor is controlled by the motor PWM control circuit and the variable voltage PWM control circuit when rotating in the low speed. The applied voltage supplied for low speed rotation is reduced, but a pulse width is increased so the influence of a harmonic wave is reduced. So, a BLDC motor can be stably operated in a direct connection structure without a reduction gear. |
