| 摘要 |
<p>The chopper control is intended to replace switched rheostatic control for motor torque or speed variation. An oscillator generates a frequency corresponding to the highest chopping rate required, and is used to feed the switch-off circuit directly. It also feeds circuit elements which invert the signal to produce the switch-on impulses. A control circuit determines the frequency required for the immediate motor needs, and feeds signals to control blocks to produce switching impulses to obtain the correct mark-space ratio from the chopper. Logic circuits are used in this part of the control, and include two groups of three AND gates and two OR gates.</p> |
