| 摘要 |
<p>1515187 Automatic control SIEMENS AG 22 Aug 1975 [22 Aug 1974] 35056/75 Heading G3N A plant is automatically controlled by applying a characteristic quantity q of the plant 11 to a v/f converter 16 and the resultant pulse-train applied to a store SP1 through a frequency-divider 17. The contents of the store SP1 is transferred at intervals to a store SP2 and compared, after D/A conversion (not shown), by a comparator 20. The comparison, represent K#q(n 1 ) is limited by device 21 and compared in a comparator 22 with a value p. The result is fed through a polarity reversing device 23 and as a desired charge #yn in a controlled variable y n from store SP4 is added in a device 24 and fed to a store SP3 from which it is used as the valve y applied to the controlled plant 11. The sequencing of switches 12, 19, 25, and 26 is determined by a pulse sequence S1-S3 from a control unit 27 responsive to a pulse train f 2 derived from a pulse-generator 28 through a frequency -divider 29. The frequency-division effected by dividers 29, 17 is controlled manually by a device 30. The polarity-reversing device 23 is cycled by a bi-stable switch 31 triggered by pulses S1. The effect of the optimizing cycle is to approach the optimum value of q as shown in Fig. 2 with the optimum value being maintained by encursions P in the controlled variable y producing minimal perturbations of the characteristic quantity q. The plant is stated to be a ball mill for the manufacture of cement.</p> |
