GB1028116A - Electric control systems for wound rotor type induction machines - Google Patents

Abstract

1,028,116. Automatic control of speed and tension. F.SHIBATO. Sept 15,1964 [Sept 30, 1963; Oct 1, 1963;Oct 5, 1963;Oct 23, 1963], No. 37568/64. Heading G3R. [Also in Division H2] The speed of a polyphase, wound rotor induction machine 1 is controlled by adjustment of the field current of at least one of two D.C. machines 2, 3 connected in series to its secondary windings via a convertor 4. One of the D.C. machines is mechanically coupled to the induction machine and the other to a fourth rotating machine 5. In the arrangement shown, 1 is a motor, 5 is normally an A.C.generator and 2 and 3 may be excited for either motoring or generating. The motor 1 may be dynamically braked by applying D.C. or reverse A.C.,the machine 3 then acting as a motor energized from 1 and 2. The convertor 4 may comprise valve, metal or semiconductor rectifiers, controlled or otherwise, a magnetic amplifier, mercury arc rectifiers fed via a variable transformer (Fig. 9, not shown), or a rotary convertor. (Fig. 3, not shown). In another arrangement (Fig. 4, not shown) there are a plurality of induction motors 1,41 each mechanically coupled to a D.C. machine 2,42, the wound secondaries, convertors and D.C. machines being paralleled and connected to a single D.C. machine 3 coupled to an A.C. generator 5. Adjustment of the field of the single D.C. machine 3 varies the group speed of all the induction motors, while adjustment of the fields of the individual D.C. machines controls the speed of its associated motor only. In another embodiment (Fig. 8, not shown) both 5 and 3 are driven by a prime mover 20. In the arrangement of Fig. 2 (not shown) the induction machine 1 is a dynamo-electric coupling, driven by a prime-mover 20, and its output speed to a load 23 is controlled by adjustment of the fields of D.C. machines 2, 3. In a further arrangement (Fig. 5, not shown), 1 and 2 are A.C.and D.C. generators driven by a diesel engine, waste gases from which produce steam for a turbine driving 5, also a generator; 3 operates as a motor, energized from 1 and 2,and assists in driving 5. The A C output of 5 is used in parallel with an auxiliary diesel driven AC. generator. In an embodiment described in relation to Fig. 6 (not shown) 5 is a generator whose speed is kept constant by controlling the field of 2 (generating) or 3 (motoring) in response to a tachogenerator 56. 1 is an A.C. generator driven by a prime mover 55. The invention is also applied to an arrangement for keeping constant tension in a web W, (Fig. 7 not shown). The speed of reel motor 1 is adjusted to compensate for the radius of the material on reel 69 by control of D.C. machine fields 6, 7. The field 7 is controlled by a device 57 which compares current flow between the machines at 61 with a reference 59, with correction for acceleration by a device 62, 63. The field 6 is controlled by device 58 which compares the output of capstan tachogenerator 65 with the voltage across D.C. machine 3.