| 摘要 |
<p>967,849. Control of D.C. motors. ENGLISH ELECTRIC CO. Ltd. Jan. 3, 1961 [Jan. 7, 1960], No. 617/60. Heading H2J. [Also in Division H3] In an arrangement for controlling a reversible D.C. current flowing through a motor 10 (Fig. 1), two rectifier networks 15, 16 forming D.C. output circuits of magnetic amplifiers 17, 18, respectively, are connected in series opposition, and through that rectifier network which for the time being develops the smaller D.C. output voltage is circulated in the opposite direction a direct current at least as great as that flowing through such rectifier network from the load whereby such rectifier presents a low impedance to the load current. The magnetic amplifiers 17, 18 are supplied from an A.C. source 19, are biased for class " A " operation, and have control windings 17a, 18a in series which are fed from a D.C. source 20. Auxiliary circuits 22, 23 include rectifier networks 26, 27 supplied by magnetic amplifiers 28, 29 having control windings 28a, 28b and 29a, 29b, respectively. When speed regulator 21 is set to neutral, zero control current flows in windings 17a, 18a so that the output voltages are equal and opposite and no current flows in the motor armature circuit. Currents flowing in circuits 22, 23 from rectifier networks 15, 16 are equal and control windings 28a, 29a carry equal currents and provide equal negative components of amplifier excitation. Control windings 28b, 29b are unenergized. Adjustment of regulator 21 to a " forward speed " position causes positive control current to flow in windings 17a, 18a, resulting in increase in output voltage of amplifier 17 and decrease in output voltage of amplifier 18. Current then flows in the motor armature circuit to rotate the motor 10. The increase in output voltage of network 15 increases current flow in network 22 and the increased current flowing in winding 28a increases the negative excitation while current flowing in winding 28b still further increases the negative excitation, the output voltage of amplifier 28 consequently being at a low level. On the other hand flow of the armature current through winding 29b tends to increase the output voltage of amplifier 29, although this positive excitation is countered by increase in negative excitation due to winding 29a. Balance is reached when the current circulated through network 16 by amplifier 29 is substantially equal to 120% of the motor armature current. Movement of regulator 21 in the opposite sense results in reversal of current flow through the motor armature. Amplifier 29 is biased more negatively and amplifier 28 operates to increase its current flow through network 15 to maintain it at a value equal to 120% of the current flowing in the motor armature circuit. In an alternative arrangement (Fig. 2) voltages are developed across rectifier networks 26, 27 by secondary windings 31, 32 of a supply transformer 33 and inductors 34, 35, and across each resistor 24, 25 is developed a voltage slightly greater than that across networks 15, 16.</p> |
