| 摘要 |
914,056. Control of D.C. motors. GENERAL ELECTRIC CO. May 25, 1959 [May 23, 1958], No. 17730/59. Class 38 (3). [Also in Groups XXVI, XXVII and XXXV] As shown, an electric motor 21 is supplied from a generator 20 whose output voltage P 0 is not inherently in direct proportion to the excitation voltage S 2 supplied to its field winding 22, the arrangement being such that the voltage P 0 is made to be a linear function of the signal voltage S 1 applied to a field winding 25 of an exciter-amplifier 24 which is selected to have a fixed linear relation between its output voltage S 2 and its input voltage S 1 . For this purpose, the effect of the winding 25 is modified by a field winding 26 supplied with a control voltage S 4 which is a fraction of the difference between the voltage S 2 and a voltage S 0 . The latter is a fraction of the voltage P 0 and is derived from a voltage divider 28. The voltage S 4 is attenuated by the relative number of turns in the windings 25, 26, or by a voltage divider. The differential voltage (S 2 - S 0 ) may be adjusted by a variable resistor 29. Transient variations are prevented by a filter circuit 67, 67a, connected across the field winding 22, and a filter circuit 68, 68a, across the voltage divider 28. In a calendering machine for plastics, heated rollers 41-44, stripper roller 50, and a conveyer 52 are each driven by an electric motor having a separate generator network 60-65 as described. The critical relative speed of each motor is adjusted whilst the machine is operating at minimum speed, after which a master controller 66 is turned to increase the speed signal S 1 to all the generator networks 60-65 simultaneously to multiply the speed of each roller by an equal amount. In this manner, the relative speeds of the various components of the machine are maintained accurately during acceleration to prevent breaking of the plastic sheet. The same arrangement may be applied to other machines, such as machine tools. A similar control system may be used for non-electric prime movers, Figs. 6, 7 (not shown).
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