| 摘要 |
A sewing machine includes as a driving element the low-inertia electric motor which is controlled by an electronic controller which receives signals from a digital/analog converter controlled by a microprogrammed controller. The low-inertia motor includes an electronic tachometer electrically connected to a speed controller which is comprised of an adjusting and control stage and a power distribution stage. The adjusting and control stage receives signals from a tachometric feed-back circuit as well as signals from a feed-back circuit of the intensity consumed by the low-inertia motor and also a reference signal from the digital analog controller. The adjusting and control stage supplies a signal of the state of motion for the coupling interphase with the controller and signals of speed control and operating speed control of the low-inertia motor. The power distribution stage comprises an alternating to direct current converter followed by a controlled direct to alternating current converter connected to the primary of a transformer having a ferrita core, the secondary of which is connected to a second direct to alternating current converter which feeds the low inertia motor. The adjusting and control stage at all times makes a comparison by means of operational amplifiers of their input signals, as a result of which comparison it porportions an output which controls the controlled direct to alternating current converter as well as a second output susceptible of activating conduction, depending on the polarity of a pair of transistors incorporated in the feed-back circuit of the low-inertia motor, which transistors control the direction of rotation of the motor.
|
