GB920009A - Improvements in or relating to alternating current uni-polar machines - Google Patents

Abstract

920,009. Homopolar machines. HENSCHELWERKE G.m.b.H. April 1, 1960 [April 9, 1959], No. 11683/60. Class 35. In a homopolar generator which is caused to generate A.C. by A.C. excitation of its field winding W, and in which tne rotor current is taken back across the stator pole-face to compensate for armature reaction, the collector ring through which the working flux # passes is subdivided into contact segments F to avoid circulating currents and additional stator and rotor conductors L 1 are provided for bucking the transformer voltage induced by the field fluctuations. Current collection may be made by brushes B whose number corresponds to the number of compensating conductors C, which is different from the number of rotor bars D. The width of the brushes is less than the width of insulation between the rotor collector segments, so that at all times, there is at least one break in the rotor ring. At the other end of the rotor a collector R 2 is engaged by a brush B 1 . Alternatively, collection may be by jets of conducting liquid, which are unequally spaced for the same purpose. Sparking at these brushes or jets may be avoided by connecting discharge resistances between both stator and rotor segments. This introduces resistive loss which is overcome, according to the invention by means of additional stator and rotor bars L 1 projecting axially from the contact segments F to closed rings R 1 , R<SP>1</SP> 1 . As a result of this connection the total flux entering and leaving any loop is zero, so that no transformer voltage is induced between collector segments. To save copper, the rotor conductor bar extensions L 1 and the ring R 1 are placed in the right-hand rotor immediately beside or coaxial with the working conductors D and the outer collector-ring R 2 . Additional stator bars are then not necessary. With this arrangement, both halves of the machine may constitute active conductors, the two sections being connected in series. The conductors may consist of radial plates connected to the shaft. The iron cores may be of radial plates or wire embedded in resin. The machine may be combined with a transformer. Hollow conductor-bars may be used for cooling, and the machine may be of disc form.